What is a rotary engine? Operating principle of a rotary engine

Features of a rotary motor

The design is based on a triangular-shaped rotor, each of the faces of which has a convexity (Reuleaux triangle).
The rotor rotates in a planetary manner around a central axis - the stator. The vertices of the triangle describe a complex curve called an epitrochoid. The shape of this curve determines the shape of the capsule within which the rotor rotates. The rotary engine has the same four stroke cycles as its competitor, the piston engine.

Chambers are formed between the edges of the rotor and the walls of the capsule; their shape is variable crescent-shaped, which is the cause of some significant design flaws. To isolate the chambers from each other, seals are used - radial and end plates.

If we compare a rotary internal combustion engine with a piston one, the first thing that catches your eye is that during one revolution of the rotor, the power stroke occurs three times, and the output shaft rotates three times faster than the rotor itself.

The RPD does not have a gas distribution system

, which greatly simplifies its design.
And the high specific power with the small size and weight of the unit is a consequence of the absence of a crankshaft
, connecting rods and other interfaces between the chambers.

Rotary engine - a choice made with the heart!

Ilya [mrjoe]

31.08.2016,

When choosing any path, action or object, you cannot always rely only on reason; sometimes you need to act at the behest of your heart. For your entire life, formed from actions committed to please the rational and practical side, will be devoid of joy, since this is not what you would really like. After all, you acquired or did it because it was convenient, correct, profitable or recognized by society.

A rotary engine in a car is a choice made by the heart, because... There is zero rationality and practicality in such a motor without a stick. Only a true road maniac would buy such a car and drive it subject to constant repairs and diagnostics.

What is a rotary engine?

This is the same internal combustion engine, differing from standard piston engines in its operating principle and design features.
The meaning of everything that happens remains the same - the fuel burns, the car moves. And there are many similar points, for example: there is a piston, an injector, an exhaust, a combustion chamber and the same four cycles of the working process, but the shape of all the parts and the unit itself is slightly different. This is what makes the engine special and powerful relative to its displacement. For those who don’t know, Mazda’s stock 1.3-liter rotor produces 240 hp. If I'm not confusing anything, then this is the only brand of car with a rotary engine that can now be purchased on the open market, though only used, because... They don't make them anymore. Popular models RX-7 and RX-8, both cars were remembered from box-office films, the first in the first Fast and the Furious (Diesel's car), the second appeared in Day Watch (the car of the now deceased Friska).

Operating principle

Forget the design of a conventional internal combustion engine, everything will be completely different there and imagine a cutaway drill.
It contains an electric motor which has a stator (outer part) and a rotor (inner part). The stator is stationary, and the rotor is in rotational motion and drives the drill. It’s the same in a rotary piston engine (RPE), only rotation occurs not from the voltage in the coil, but from the ignition of the working mixture. I won’t describe what and what form, everything will be clearly shown in the figure. Let's move on to the operation of the motor itself. Let's start with the fact that the rotor itself, also known as the piston, is located on a shaft that rotates the flywheel and supplies force to the transmission, but this is not a simple shaft that rotates the rotor around its axis, but an eccentric shaft. The rotor seems to describe the center of the shaft, creating hemispheres in the cavity of the engine working area.

It all starts with suction. The hemisphere is filled with air and fuel, mixing in the cavity (not in the intake manifold). Next, the rotor pushes the fuel mixture into the next chamber, simultaneously compressing it, where ignition occurs from two spark plugs. The mixture burns and gases expand and are pushed into the next chamber, where release occurs. Nothing special, you might think. Yes. You just need to take into account that the rotor is triangular in shape and the process occurs simultaneously. That is, three cycles in one revolution. If you compare it with a conventional engine, then there is one cycle per revolution. This is the whole “trick” of such a system.

As a rule, cars are equipped with two- and three-rotor engines with specific efficiency, which can be compared with “adult” V-shaped engines. For example, 1.3 from RX8 = V6 of any naturally aspirated engine, and 3-rotor = V12. These are the comparative points that captivate potential owners of cars with RPD. But this is an iceberg with such a reason that sometimes you don’t even want to know about it and it’s generally scary.

Pros and cons of rotary piston engines

Pros:

Minimum details. The RPD has 1000 fewer parts than a conventional internal combustion engine;
Smooth and balanced operation. There is virtually no vibration in the engine due to the unidirectional operation of the system (for those who do not know, in a standard internal combustion engine the piston works in different directions);
High efficiency relative to the working volume.

Of the minuses:

Ecology (in our country few people care, but still). Large amount of carbon dioxide emissions;
Fuel consumption. Average consumption is 20-25 liters per 100 km. This happens because the fuel compensates for the low compression ratio (in other words, the compression ratio is low and the engine pours gasoline into the chamber with a reserve);
Low resource. Ideally, the engine will last 150 thousand without major repairs, but this is under the best conditions.
The high cost of maintenance and the lack of a sufficient number of workshops dealing with such internal combustion engines (for example, in Moscow, the fingers of one hand are more than enough to list all the services; 3-4 years ago there was only one sensible service that dealt with this at a high level);
Purely production minus. It costs the manufacturer a pretty penny to produce this motor.

Therefore, when purchasing such a car, you clearly do not plan to save money and practicality is not your strong point. Or maybe you just like the car and don’t care about its disadvantages? This could also happen. By the way, there is a category of citizens who like the design of the same RX-8 and in order to avoid having to repair the rotor, they change it to a regular internal combustion engine.

Why do rotary engines have a short lifespan?

Really?
There are fewer parts and the design is simpler, plus there is no vibration. It's all about the tightness of the hemispheres, and this is very difficult to achieve. Requires expensive components and professional maintenance. It won’t be possible to get more from Ashot in the area. In addition, oil changes are frequent (every 5000), and its consumption is not small - 600 ml per 1000 km. Frequent overheating of the engine is also observed due to the cooling features (the manufacturer is unable to correct these issues). The cost of repairing the RPD depends on the condition. If we take the price for the bulkhead, it will range from 1000-1500 cu. If large components are not damaged, then we pay about 1,500 euros for a repair kit and 700 for each section if they have already arrived. But if a more in-depth analysis is required, then it is cheaper to order a new engine from the USA or Japan (from the USA it is 1000-1500 cheaper).

PS Another advantage is the low weight of the unit itself, which made it possible to make a more balanced “weight distribution” of the entire car, as well as the ability to accelerate the car to 100 km/h without changing gears at 8000 rpm without any consequences.

The structure and principle of operation of a rotary engine

The operating pattern of a rotary engine is something completely different from a conventional internal combustion engine. First, we must leave behind the design of the internal combustion engine as we know it. And secondly, try to absorb new knowledge and concepts.

Like a piston engine, a rotary engine uses pressure that is created by burning a mixture of air and fuel. In piston engines, this pressure is created in the cylinders and moves the pistons back and forth. The connecting rods and crankshaft convert the reciprocating motion of the piston into rotational motion, which can be used to turn the wheels of a car.

The RPD is named so because of the rotor, that is, the part of the motor that moves. Thanks to this movement, power is transferred to the clutch and gearbox. Essentially, the rotor pushes out energy from the fuel, which is then transferred to the wheels through the transmission. The rotor itself is made of alloy steel and has, as mentioned above, a triangle shape.

The capsule where the rotor is located is a kind of matrix, the center of the universe, where all processes take place. In other words, it is in this oval body that what happens:

mixture compression;
fuel injection;
oxygen supply;
ignition of the mixture;
release of burnt elements to the outlet.

In a word, six in one, if you like.

The rotor itself is mounted on a special mechanism and does not rotate around one axis, but seems to run. Thus, cavities isolated from each other are created inside the oval body, in each of which one of the processes occurs. Since the rotor is triangular, there are only three cavities.

It all starts as follows: in the first cavity formed, suction occurs, that is, the chamber is filled with an air-fuel mixture, which is mixed here. After this, the rotor rotates and pushes this mixed mixture into another chamber. Here the mixture is compressed and ignited with the help of two candles.

The mixture then goes into the third cavity, where parts of the used fuel are displaced into the exhaust system.

This is the full cycle of RPD operation. But it's not that simple. We examined the RPD scheme only from one side. And these actions take place constantly. To put it differently, processes occur on three sides of the rotor at once. As a result, in just one revolution of the unit, three cycles are repeated.

Again, performance is not the only benefit of RPD. He has a lot of them. As mentioned above, the rotary engine is very compact and uses as many as a thousand fewer parts than the same internal combustion engine. There are only two main parts in the RPD - the rotor and the stator, and you can’t imagine anything simpler than that.

Design

To understand the principle of operation, you need to understand what the design of a rotary engine is. So, instead of pistons, the energy of fuel combustion in such a power unit is perceived by the rotor. The rotor has the shape of an equilateral triangle. Each side of this triangle plays the role of a piston.

Rotor

To ensure the combustion process, the rotor is placed in a closed space consisting of three elements - two side housings, and one central one, called the stator. The space in which the combustion process takes place is made in the stator; the side housings only ensure the tightness of this space.

Inside the stator there is a cylinder in which the rotor is located. In order for all the necessary processes to take place inside this cylinder, it is made in the form of an oval, with slightly pressed sides.

The stator itself has windows on one side for the intake of the air-fuel mixture or air, and the exhaust of exhaust gases. Opposite them there is a hole for the spark plugs.

Engine device

The peculiarity of the movement of the rotor in the stator cylinder is that its tops are constantly in contact with the surface of the cylinder; its movement is made according to the eccentric type. It not only rotates around its axis, but also shifts relative to it.

For this purpose, a large hole is made in the rotor; on one side of this hole there is a gear sector. On the other side, a shaft with an eccentric is inserted into the rotor.

To ensure rotation, a fixed gear is installed in the side housing, which meshes with the toothed sector of the rotor; it serves as a support point for it. During its eccentric movement, it rests on a fixed gear, and the gearing provides it with rotational movement. As it rotates, it also ensures rotation of the shaft with the eccentric on which it is mounted.

Duty cycle

The Wankel engine uses a four-stroke cycle:

stroke A: The fuel-air mixture enters the engine chamber through the intake port
stroke B: The rotor rotates and compresses the mixture, the mixture is ignited by an electric spark
stroke C: Combustion products press on the rotor surface, transmitting forces to the cylindrical eccentric
stroke D: The rotating rotor forces the exhaust gases into the exhaust port.

Despite the similarity of the cycle, the combustion dynamics of the fuel-air mixture in a rotary piston engine (RPE) are very different from a traditional piston engine.

In a piston engine (PE), the fuel-air charge, passing into the cylinder through the valve at the intake stage, acquires high turbulence, which increases with increasing crankshaft speed, which has a beneficial effect on the completeness of combustion of the mixture. In the RPD, turbulence is lower and at the moment of ignition, the main charge of the mixture ahead of the rotor rotation quickly burns out, while the rear part of the working cavity remains unburned and is released into the atmosphere. This explains the 6-8 times higher percentage of emissions of unburned hydrocarbons into the atmosphere compared to piston engines.

Another difference between the RPD operating cycle and the PD operating cycle is the shift in the moment of maximum heat release in the combustion chamber to the expansion line after passing top dead center. Therefore, the maximum cycle temperatures, at the same compression ratio, are lower for RPDs, and in the exhaust phase the temperature of the exhaust gases is 200 - 250 °C higher than for piston engines. This is thermodynamically unfavorable and leads to an additional decrease in efficiency, but at the same time, for this reason, the emission of nitrogen oxide from the RPD is 20% lower, and at the same compression ratios, the RPD is able to operate without detonation on fuel with an octane rating of 15 units less than the piston engine.

Elimination of the shortcomings of RPM is achieved by complicating injection systems, creating stratification of the fuel-air mixture in the combustion chamber, etc.[3]

The principle of operation of a rotary engine - design, disadvantages and advantages, video

Global automobile concerns launched cars with these power units on the market, but later abandoned these products. What happened? We propose to understand the advantages and disadvantages of rotors, consider the operating principle of the RPD (rotary piston engine).

These heat motors do not require spare parts that convert translational impulse into rotational impulse (crankshaft). This design feature leads to a reduction in losses. If there are pistons in the cylinder, four strokes are performed:

In the rotor, these processes occur in different parts of the chamber.

Bringing a high-efficiency car to the market is the dream of any automaker. Why has it never become widespread? Let's figure it out.

Find out the cost of repairing a rotary engine online in 3 minutes

Don't waste your time - use the Uremont search and get offers from nearby services with specific prices!

Operating principle of a rotary engine

The operating principle of a rotary piston engine once made many talented engineers raise their eyebrows in surprise. And today, the talented engineers of Mazda deserve all praise and approval. It's no joke, believe in the performance of a seemingly buried engine and give it a second life, and what a second life!

Sectional view of a rotary engine

Rotary motor rotor

Rotary engine chamber

The rotor has three convex sides, each of which acts as a piston. Each side of the rotor has a recess in it, which increases the speed of rotation of the rotor as a whole, providing more space for the air-fuel mixture. At the top of each face there is a metal plate, which forms the chambers in which the engine strokes occur. Two metal rings on each side of the rotor form the walls of these chambers. In the middle of the rotor there is a circle in which there are many teeth. They are connected to a drive, which is attached to the output shaft. This connection determines the path and direction that the rotor moves inside the chamber.

The engine chamber is approximately oval in shape (but to be more precise it is an Epitrochoid, which in turn is an elongated or shortened epicycloid, which is a flat curve formed by a fixed point on a circle rolling on another circle). The shape of the chamber is designed so that the three apexes of the rotor are always in contact with the chamber wall, forming three closed gas volumes. In each part of the chamber, one of four cycles occurs:

Inlet
Compression
Combustion
Release

The inlet and outlet openings are located in the walls of the chamber and there are no valves on them. The exhaust port is connected directly to the exhaust pipe, and the intake port is directly connected to the gas.

The output shaft has semicircular cam protrusions placed asymmetrically relative to the center, which means that they are offset from the centerline of the shaft. Each rotor fits onto one of these lugs. The output shaft is analogous to the crankshaft in piston engines. Each rotor moves inside the chamber and pushes its own cam.

Since the cams are installed asymmetrically, the force with which the rotor presses on it creates a torque on the output shaft, causing it to rotate.

Structure of a rotary engine

A rotary engine consists of layers. The twin-rotor engine consists of five main layers, which are held together by long bolts arranged in a circle. Coolant flows through all parts of the structure.

The center consists of two fuel supply chambers, one for each rotor. It also separates the two rotors so its outer surface is very smooth.

At the center of each rotor are two large gears that rotate around smaller gears and are attached to the motor housing. This is the orbit for rotating the rotor.

Of course, if the rotary engine had no disadvantages, then it would definitely be used in modern cars. It is even possible that if the rotary engine had been sinless, we would not have known about the piston engine, because the rotary engine was created earlier. Then the human genius, trying to improve the unit, created a modern piston version of the engine.

But unfortunately, the rotary engine has disadvantages. Such obvious mistakes of this unit include the sealing of the combustion chamber. In particular, this is due to insufficiently good contact of the rotor itself with the cylinder walls. When friction with the cylinder walls, the metal of the rotor heats up and, as a result, expands. And the oval cylinder itself also heats up, and even worse - the heating occurs unevenly.

If the temperature in the combustion chamber is higher than in the intake/exhaust system, the cylinder must be made of high-tech material installed in different places in the body.

In order for such an engine to start, only two spark plugs are used. No longer recommended due to the nature of the combustion chamber. The RPD is equipped with a completely different combustion chamber and produces power three-quarters of the working time of the internal combustion engine, and the efficiency is as much as forty percent. In comparison: for a piston engine the same figure is 20%.

Intake of the fuel-air mixture in a rotary engine

The intake of the mixture begins at the moment when one of the vertices of the rotor passes the inlet valve in the housing. At this time, the volume of the chamber expands, drawing the fuel-air mixture into its increasing space. The moment the next rotor tip passes the inlet port, the next stroke begins. Compression of the fuel-air mixture in a rotary engine As the rotor rotates, the volume of the mixture captured by the rotor decreases, which leads to an increase in pressure. Maximum pressure is formed at the moment when the fuel-air mixture is in the spark plug area.

Combustion of the fuel-air mixture

To ignite the mixture, as in a piston engine, spark plugs are used. They ignite the mixture simultaneously, that is, they work synchronously. Typically, two spark plugs are used for a rotary engine. The use of two spark plugs is due to the characteristics of the working volume. It seems to be stretched along the wall of the body, which is why it is more effective to use two candles so that the mixture burns more quickly and evenly. In the case of a single spark plug, the mixture will burn longer, so to speak gradually, which will significantly reduce the peak pressure during the explosion when igniting the fuel-air mixture. As a result, from the resulting pressure of the blast wave, a working force is obtained that turns the rotor on the eccentric of the shaft. Torque is transmitted to the output shaft. The rotor rotates to the exhaust outlet.

Exhaust gas emission

As soon as the rotor of one of its apexes crosses the boundary of the exhaust port, the emission of exhaust gases begins. The rotor, by inertia, and also through the second rotor, which operates asynchronously, continues to change its angle and moves its apex to the inlet. Here everything happens again from the intake stroke to the ejection stroke.

Rotary engine design

The operation of all types of engines is based on the pressure generated during fuel combustion.

In units with a piston group, the crankshaft and connecting rods transform reciprocating energy into rotation. As a result, the wheels spin. The Wankel engine (an alternative name for an internal combustion engine with a rotor) uses a different technical solution. The pressure is produced in a chamber that is part of the housing. The closed side of the rotor triangle acts as pistons.

A rotary internal combustion engine produces a rotation similar to a spirograph curve. For a given trajectory, three vertices are in contact with the body. Three independent volumes for gas are formed. When the part rotates, these chambers compress/expand, as a result:

the fuel-air mixture enters the engine;
shrinks;
produces the necessary work as a result of expansion;
comes out through the exhaust.

Rotary motor housing

The body of a rotary engine is like a multi-layer cake. It has its own lids, working chambers, and dividing walls. The best way to understand the design of the case is to look at the picture. It shows that the engine has two chambers separated by a wall and covers on both sides. Everything else, of course, also matters, but what we have listed is paramount. And now we will talk about the working chambers of the rotary engine housing.

The internal cavity of the body has a complex shape, resembling an oval. In fact, the oval has certain compensating ebbs that ensure the sealing of all three chambers separated by the rotor, regardless of the angle of rotation and the ongoing cycle. Each cycle has its own place in the rotary engine housing. Depending on the angle of rotation of the rotor, a corresponding cycle is performed, which is repeated at intervals every 360 degrees of rotation of the rotor. The outlets for the emission of burnt gases are also located in the body of the working chamber. Intermediate wall between the chambers (pictured below)

holds the shaft in its central hole, is sealed with the rotors along the side walls, has elements of the cooling system, injection ports, and guide bushings.

Work phases

How does a rotary engine work? The operating principle (gif images and RPD diagram you can see below) of this motor is as follows. The operation of the engine consists of four repeating cycles, namely:

Fuel supply. This is the first phase of engine operation. It occurs at the moment when the top of the rotor is at the level of the feed hole. When the camera is open to the main compartment, its volume approaches its minimum. As soon as the rotor rotates past it, the fuel-air mixture enters the compartment. After this, the camera becomes closed again.
Compression. As the rotor continues to move, the space in the compartment decreases. Thus, the mixture of air and fuel is compressed. As soon as the mechanism passes the compartment with the spark plugs, the volume of the chamber decreases again. At this moment, the mixture ignites.
Ignition. Often a rotary engine (including VAZ-21018) has several spark plugs. This is due to the large length of the combustion chamber. As soon as the candle ignites the combustible mixture, the pressure level inside increases tens of times. Thus, the rotor is driven again. Further, the pressure in the chamber and the amount of gases continue to increase. At this moment, the rotor moves and torque is created. This continues until the mechanism passes the exhaust compartment.
Release of gases. When the rotor passes this compartment, high-pressure gas begins to move freely into the exhaust pipe. In this case, the movement of the mechanism does not stop. The rotor rotates steadily until the volume of the combustion chamber again drops to a minimum. By this time, the remaining amount of exhaust gases will be squeezed out of the engine.

This is exactly the operating principle of a rotary engine. The VAZ-2108, on which the RPD was also mounted, like the Japanese Mazda, was distinguished by quiet engine operation and high dynamic characteristics. But this modification was never put into mass production. So, we found out what the operating principle of a rotary engine is.

How popular is the rotary diesel engine?

The first cars on which the Wankel internal combustion engine was installed were NSU Spider cars produced in 1964, with a power of 54 hp, which allowed the vehicle to accelerate to 150 km/h. Then, in 1967, a test version of the NSU Ro-80 sedan was created, beautiful and even elegant, with a narrowed hood and a slightly higher trunk. It never went into mass production. However, it was this car that prompted many companies to buy licenses for a rotary diesel engine. These included Toyota, Citroen, GM, Mazda. The novelty didn’t take root anywhere. Why? The reason for this was its serious shortcomings.

The chamber formed by the walls of the stator and rotor significantly exceeds the volume of a classic cylinder; the fuel-air mixture is uneven

. Because of this, even with the use of synchronous discharge of two spark plugs, complete combustion of the fuel is not ensured. As a result, the internal combustion engine is uneconomical and environmentally unfriendly. That is why, when the fuel crisis broke out, NSU, which relied on rotary engines, was forced to merge with Volkswagen, where they abandoned the discredited Wankels.

Mercedes-Benz produced only two cars with a rotor - the C111 of the first (280 hp, 257.5 km/h, 100 km/h in 5 seconds) and the second (350 hp, 300 km/h, 100 km /h in 4.8 sec) generation. Chevrolet also produced two Corvette test cars, with a two-piece 266 hp engine. and with a four-section 390 hp, but everything was limited to their demonstration. For 2 years, starting in 1974, Citroen produced 874 Citroen GS Birotor cars with a power of 107 hp from the assembly line, then they were recalled for liquidation, but about 200 remained with car enthusiasts. This means that there is a chance of meeting them today on the roads of Germany, Denmark or Switzerland, if, of course, their owners have undergone a major overhaul of their rotary engine.

Mazda was able to establish the most stable production; from 1967 to 1972, 1,519 Cosmo cars were produced, embodied in two series of 343 and 1,176 cars. During the same period, the Luce R130 coupe was put into mass production. Wankels began to be installed on all Mazda models without exception since 1970, including the Parkway Rotary 26 bus, which reaches speeds of up to 120 km/h and weighs 2835 kg. Around the same time, the production of rotary engines began in the USSR, although without a license, and, therefore, they figured everything out with their own minds using the example of a disassembled Wankel with NSU Ro-80.

Development was carried out at the VAZ plant. In 1976, the VAZ-311 engine was qualitatively changed, and six years later the VAZ-21018 brand with a 70 hp rotor began to be produced en masse. True, a piston internal combustion engine was soon installed on the entire series, since all the Wankels broke during the run-in, and the rotary engine needed to be replaced. Since 1983, VAZ-411 and VAZ-413 models with 120 and 140 hp began to roll off the assembly line. respectively. The traffic police, the Ministry of Internal Affairs and the KGB were equipped with them. Currently, rotors are exclusively handled by Mazda.

Rotary motor output shaft

The output shaft has eccentrics, in this case there are two of them, since two rotors are installed on the shaft, which operate in antiphase, when one is in the exhaust gas emission cycle, the second in the mixture intake cycle. The use of two rotors makes it possible to compensate for beating during engine operation and, accordingly, reduce detonation. By displacing the eccentric and moving each of the rotors along the walls in the engine housing, they try to rotate the shaft. As a result, a working torque is generated on it.

Advantages of a rotary engine

Fewer moving parts

A rotary engine has many fewer parts than say a 4 cylinder piston engine. A twin rotor engine has three main moving parts: two rotors and an output shaft. Even the simplest 4-cylinder piston engine has at least 40 moving parts, including pistons, connecting rods, rods, valves, rockers, valve springs, timing belts, and the crankshaft. Minimizing moving parts allows rotary engines to achieve higher reliability. This is why some aircraft manufacturers (for example Skycar) use rotary engines instead of piston engines.

Softness

All parts in a rotary engine rotate continuously in one direction, unlike the constantly changing direction of the pistons in a conventional engine. The rotary engine uses balanced rotating counterweights to suppress any vibrations. The power delivery in a rotary engine is also smoother. Each combustion cycle occurs in one rotor revolution of 90 degrees, the output shaft rotates three times for each rotation of the rotor, each combustion cycle occurs in 270 degrees during which the output shaft rotates. This means that a single rotary engine produces three-quarters of the power. Compared to a single cylinder piston engine, combustion occurs every 180 degrees of every revolution, or only a quarter revolution of the crankshaft.

Slowness

Because the rotors rotate at one-third of the rotation of the output shaft, the main parts of the engine rotate more slowly than those in a conventional piston engine. This also helps with reliability.

Small dimensions + high power

The compactness of the system, together with high efficiency (compared to a conventional internal combustion engine), allows the miniature 1.3-liter engine to produce about 200-250 hp. True, along with the main design flaw in the form of high fuel consumption.

Disadvantages of rotary motors

The most important problems in the production of rotary engines:

It is quite difficult (but not impossible) to comply with regulations on CO2 emissions into the environment, especially in the USA.
Production can be much more expensive, in most cases due to low volume production, compared to piston engines.
They consume more fuel because the thermodynamic efficiency of a piston engine is reduced in a long combustion chamber and also due to the low compression ratio.
Rotary engines due to their design have a limited service life - on average it is about 60-80 thousand km

This situation simply forces rotary engines to be classified as sports car models. And not only. Today there are supporters of the rotary engine. This is the famous automaker Mazda, which took the path of the samurai and continued the research of Master Wankel. If we remember the same situation with Subaru, then the success of Japanese manufacturers becomes clear, clinging, it would seem, to everything old and discarded by Westerners as unnecessary. But in fact, the Japanese manage to create new things out of old ones. The same thing happened then with boxer engines, which are today Subaru’s “feature.” At the same time, the use of such engines was considered almost a crime.

The work of the rotary engine also interested Japanese engineers, who this time set about improving the Mazda. They created the 13b-REW rotary engine and equipped it with a twin-turbo system. Now Mazda could easily compete with German models, since it offered as many as 350 horses, but again suffered from high fuel consumption.

Surprisingly, they tried to introduce RPD in our country. Such an engine was designed for installation on the VAZ 21079, intended as a vehicle for special services, but the project, unfortunately, did not take root. As always, there was not enough state budget money, which is miraculously siphoned out of the treasury.

But the Japanese managed to do it. And they don’t want to stop there. According to the latest data, the Mazda manufacturer will improve the engine and a new Mazda will soon be released, with a completely different unit.

Small resource

The main and most significant drawback is the short service life of the engine. On average, it is equal to 100 thousand kilometers for Russia. In Europe, the USA and Japan, this figure is twice as high, thanks to the quality of fuel and competent maintenance.

The highest load is experienced by metal plates, apexes - radial end seals between the chambers. They have to withstand high temperature, pressure and radial loads. On the RX-7, the apex height is 8.1 millimeters, replacement is recommended when wear reaches 6.5, on the RX-8 it was reduced to 5.3 factory values, and permissible wear is no more than 4.5 millimeters.

It is important to monitor compression, the condition of the oil and the oil injectors that supply lubricant to the engine chamber. The main signs of engine wear and impending major overhaul are low compression, oil consumption and difficult hot starting.

Low environmental friendliness

Since the lubrication system of a rotary piston engine involves direct injection of oil into the combustion chamber, and also due to incomplete combustion of fuel, exhaust gases have increased toxicity. This made it difficult to pass the environmental inspections that had to be met in order to sell cars in the American market.

To solve the problem, Mazda engineers created a thermal reactor that burned hydrocarbons before releasing them into the atmosphere. It was first installed on a Mazda R100.

Instead of shutting down production like others, Mazda began selling vehicles with the Rotary Engine Anti-Pollution System (REAPS) in 1972.

Disadvantages of a rotary engine

At the start of sales, the Mazda rotary was in active demand, as the car attracted car enthusiasts with its unusual and powerful engine (especially forced versions with a power of about 500 hp). However, a little later, the owners, already on relatively short runs, encountered the first problems and disadvantages of this type of internal combustion engine.

The main disadvantages are high fuel consumption and the relatively low service life of the 13B-MSP rotary engine. Under ideal conditions, a power plant of this type is capable of operating for about 100 thousand kilometers. As for actual operation, engines often became unusable by 50-60 thousand km. mileage

Rotor seals are usually the first to fail. The reason is quite obvious, since the seals are under high loads and become very hot. Detonation and wear of eccentric shaft bearings, rotors, etc. also make themselves felt.

It is noteworthy that the apexes (seals at the ends) are the first to fail, while the side seals take much longer. As a result of wear of the apexes, as well as their mounting locations on the rotor, compression in the engine drops, and the corners of the seals can fall off, damaging the stator surfaces.

It should also be noted that the main bearings of the eccentric shaft quickly fail. Taking into account the fact that the shaft rotates 3 times faster than the rotors, the rotors are slightly displaced in relation to the stator walls, and the tops of the rotors should always be the same distance from the walls.

We also recommend reading the article about what a hybrid car engine is. From this article you will learn how a hybrid engine works and works, as well as what you need to know about a hybrid engine before buying a car with this type of power plant.

As a result, when the apex corners fall out, scoring will inevitably appear on the stator surface. At the same time, diagnosing a rotary engine is very difficult, since, unlike a conventional motor, a rotary engine does not knock if the liners wear out.

At the same time, we note that on supercharged versions of this engine, running the unit on a lean mixture leads to overheating of the apex. Next, the spring pressing the apex simply bends it and the compression is greatly reduced. Even forced ones (supercharged rotary engines) are characterized by uneven heating of the housing.

The upper part of the internal combustion engine, where the intake and compression strokes occur, is colder. At the same time, the lower part, where the process of combustion of the mixture and the release of hot gases takes place, heats up much more. The result is deformation of the body of the forced versions.

We also note that problems with the lubrication system also appeared separately. In practice, the oil nozzles in the stator often become dirty and stop working. In this case, it is not possible to wash the injector valves, which means they need to be replaced. If the problem is not identified in time, oil starvation causes severe wear of a number of elements of the rotary engine.

Moreover, in all cases and regardless of the reason, in practice it is practically impossible to restore the stator, and it should also be noted that there are no repair parts. This means that if the stator is damaged, it is very difficult and expensive to rebuild the engine. The same applies to the rotor. If the grooves for the apexes are damaged, it is almost impossible to repair the part.

All this means that the motor is actually “disposable” and there is no way to properly repair it. The only way out is to purchase and install a new engine, since contract options in most cases will also be worn out and will not last long. Of course, you can buy a rotary engine without mileage, but the price of a rotary engine will be high.

Difficulty in producing parts

In addition, it is worth noting the high cost of producing parts for this engine, which was explained by the complexity of manufacturing the rotor. In order for this mechanism to correctly pass the epitrochoidal curve, high geometric accuracy is needed (including for the cylinder). Therefore, in the manufacture of rotary engines it is impossible to do without specialized expensive equipment and special knowledge in the technical field. Accordingly, all these costs are included in the price of the car in advance.

Overheating and high loads

Also, due to the special design, this unit was often subject to overheating. The whole problem was the lens-shaped shape of the combustion chamber.

In contrast, classic internal combustion engines have a spherical chamber design. The fuel that burns in the lens-shaped mechanism is converted into thermal energy, which is spent not only on the working stroke, but also on heating the cylinder itself. Ultimately, frequent “boiling” of the unit leads to rapid wear and failure.

Resource

It's not just the cylinder that bears heavy loads. Studies have shown that during rotor operation, a significant part of the load falls on the seals located between the nozzles of the mechanisms. They are subject to a constant pressure drop, so the maximum engine life is no more than 100-150 thousand kilometers.

After this, the engine requires major repairs, the cost of which is sometimes equivalent to purchasing a new unit.

Oil consumption

Also, the rotary engine is very demanding on maintenance.

Its oil consumption is more than 500 milliliters per 1 thousand kilometers, which forces you to fill in fluid every 4-5 thousand kilometers. If you do not replace it in time, the motor will simply fail. That is, the issue of servicing a rotary engine needs to be approached more responsibly, otherwise the slightest mistake can lead to costly repairs of the unit.

Varieties

At the moment, there are five varieties of these types of units:

Rotary motors with reciprocating rotational movements of the shaft.
With uniform shaft rotation. Moreover, its design does not use any sealing mechanisms. The combustion chambers are arranged in a spiral type.
Units with pulsating-rotational movement directed in one direction.
With planetary shaft rotation, without sealing elements. A striking example of this is the Wankel engine.
RPD with uniform operation of working elements and a spiral type of arrangement of combustion chambers.

Rotary engine (VAZ-21018-2108)

The history of the creation of VAZ rotary internal combustion engines dates back to 1974. It was then that the first RPD design bureau was created. However, the first engine developed by our engineers had a similar design to the Wankel engine, which was equipped on imported NSU Ro80 sedans. The Soviet analogue was called VAZ-311. This is the very first Soviet rotary engine. The principle of operation of this engine on VAZ cars has the same algorithm of operation of the Wankel RPD.

The first car on which these engines began to be installed was the VAZ modification 21018. The car was practically no different from its “ancestor” - model 2101 - with the exception of the internal combustion engine used. Under the hood of the new product was a single-section RPD with a capacity of 70 horsepower. However, as a result of research on all 50 model samples, numerous engine failures were discovered, which forced the Volzhsky Plant to abandon the use of this type of internal combustion engine on its cars for the next few years.

The main reason for malfunctions of the domestic RPD was unreliable seals. However, Soviet designers decided to save this project by presenting to the world a new 2-section rotary engine VAZ-411. Subsequently, the VAZ-413 brand internal combustion engine was developed. Their main differences were in power. The first copy developed up to 120 horsepower, the second - about 140. However, these units were again not included in the series. The plant decided to install them only on official vehicles used by the traffic police and the KGB.

Rotary engine. Great, terrible! Perspective?

It seems that he has already become part of history. They don’t remember him at home. It was forgotten in those countries where they placed some kind of bet on it. And even the company, which spent half its life perfecting it, wrote off the capricious design several years ago, moving along the usual course for all manufacturers - refining traditional engines. And suddenly at the last Tokyo Motor Show there was unexpected news - there would be a rotary piston engine under the hood of Mazda! And what do they eat it with, this RPD, or rotor in common parlance? What glorious exploits did he have, and is it worth waiting with anticipation for the continuation of the half-century series?

Euphoria and disappointment

Exotic and the creation, of course, of an engineering genius. For some, the hope is to get something original in the engine compartment. For others, this is the only opportunity to gain a powerful mover. In another case, the face of a brand has suffered more than the creator of this very face. They say that Felix Wankel, the father of the engine that received his name, dreamed of the future brainchild in a dream at the age of 17. Well, such a legend fits well into the aura of mystery and, perhaps, even scandalousness that surrounds the RPD. In general, it is difficult to explain how a self-taught engineer, who had no education and knowledge of mathematics, but who had poor eyesight from birth, was able to generate the idea of such a motor and calculate the complex curve along which the main working element - the rotor - would move. And all sources agree that this was done in the first third of life. After all, at only 34 years old, in 1936, Wankel already had his own workshop from BMW, where he worked on the RPD that interested the Bavarian company. It is clear that at that time, funding for German techies poured like manna from heaven. But left-wing, untalented people, especially companies, were not allowed to the feeding trough.

Undoubtedly, Felix Wankel was the ideological inspirer, thanks to whom the world learned about the rotary piston engine not only in theory. But he wouldn’t have succeeded if he hadn’t found like-minded people, as discussed below

The first working sample of the engine was obtained in the second half of the 50s - after imprisonment, equipment selected for reparation and difficulties with employment. Traditional phenomena that affected engineers working for the Reich in post-war Germany, regardless of their political views. By the way, here another designer comes onto the scene - Walter Frede - a leading specialist at the NSU company, which gave Wankel work and faith in his development. The entire history of the rotary engine before Mazda is closely connected with this name. There is even an opinion that it was Frede who brought the engine to a working condition. One way or another, it’s impossible not to mention this engineer. True, the first unification of RPD and NSU did not work out. The Prinz model, which was supposed to be equipped with a “rotor”, eventually received a 600 cc “two-piece”.

For its time, NSU was a progressive company. Take a look at the Prinz model - how many modifications on one platform appeared in the period 1958-62. Well, the fact that the car was compact (length 3150 mm in the basic version) is a sign of the era

The first production car equipped with RPD was the NSU Spider - actually the NSU Sport Prinz (in the previous photos in the center) with a fabric top. The “rotor” had a volume of 450 “cubes” and developed 50–54 hp. From 1964 to 1967, less than 2,500 copies were produced, but overseas it took part in rallies - and won

The RPD was fully revealed in all respects in another model - the NSU Ro 80. Being two-section, with a volume of 995 cubic meters and a power of 113 hp, the engine provided the light sedan (“equipped” less than 1300 kg) with good dynamic characteristics. But the service life barely reached 50 thousand km.

The NSU Ro 80 was interesting not only because of its engine. Front-wheel drive, disc brakes on all wheels, independent suspension with McPherson struts at the front, transmission with a torque converter and electric-pneumatic gear shift - all this was still unusual in 1967, when the model appeared. Even externally, the sedan (by the way, which had a low aerodynamic drag coefficient of 0.355 at that time) compared favorably with its classmates

Now we can say that it was the “rotor”, and specifically the need for its warranty repairs, that condemned the NSU company. In 1969, it was acquired by VW. True, the Ro 80 was produced until 1977, but the circulation over the decade was small - just over 37 thousand cars. It is curious that in 1969–70. Documentation for RPD was purchased by several companies at once. Did you think that they would definitely cope with the capricious engine, or information about its problems had not yet become publicly available? One way or another, at this time Mercedes, Citroen, Chevrolet were experimenting with it.

The Mercedes-Benz C111 was conceived as a platform for experiments with new engines, which primarily included rotary piston units. Three- and four-section engines with 280 and 370 hp were tested. With them, the prototype with a composite body and doors that opened upwards accelerated to 270 and 300 km/h. In 1976, the RPD was abandoned and replaced by a three-liter diesel “five”, developing 190–230 hp. The latest version was powered by a 4.8-liter 500-horsepower V8. With diesel and V8, the C111 set ten world speed records

In 1967, NSU and Citroen created a joint venture, Comotor SA, which produced rotary engines. The first-born to receive RPD was the original two-volume M35 with hydropneumatic suspension. The car with a 497.5-cc “rotor” that developed 50 hp was produced from 1969 to 1971, but production was small-scale - 267 copies, on which various technical solutions were tested

The Citroen GS Birotor, as its name suggests, was a version of the GS model with an RPD - two-section, 995 cc, 106 hp. The car was mass-produced from 1970 to 1986, but problems with the “rotor” also surfaced here - in total, less than 850 cars with it were produced. It was replaced by four-cylinder “boxer” engines with a volume of 1.0–1.3 liters

Even GM became interested in the rotary engine, in particular the company's president Ed Cole, who initiated the appearance of an interesting prototype of the Corvette XP-897 Two-Rotor. In 1973, a two-section 180-horsepower engine appeared in the base of a car built on a Porsche 914 chassis and covered with a Pininfarina body.

The Chevrolet Aerovette, which appeared in 1976, already had a four-section RPD with a return of 420 forces. That same year it was replaced with a 6.6-liter V8. This is where the story of the “rotor” at GM ends

In 1974–77 The “rotor” was also installed on a motorcycle - on the German Hercules W-2000. With one section with a volume of 294 “cubes” it developed 27–32 hp.

Grasping at straws

What was Mazda before it bought the RPD patent in 1961? Small cars with V-shaped “twos”, tricycles... There was a whole abyss before turning into a full-fledged auto company. No larger platforms, no own engine. “Rotor” became the straw, the chip that simplified the company’s model range, helped it make a profit, and, ultimately, gain a distinctive image. Did the Japanese know the problems they would face? Hardly. It seems that the Germans themselves, who were responsible for finalizing the “rotor”, at that time still perceived it in rosy tones. And there was no operational experience as such - work in the technical departments of NSU and Mazda was carried out in parallel. At the same time, the two-section RPD under the hood of the Japanese car appeared even earlier than that of the Ro 80 - by five months, in May 1967.

The elegant Mazda Cosmo was the face of the company in the late 60s. As distinctive as the 982 cc RPD located under the hood. For example, the rear brakes were drum brakes, and the de Dion suspension was combined with leaf springs. The engine developed 110 hp, but in 1968, as part of the modernization of the coupe, it was boosted to 130 hp

From 1967 (in some sources from 1968) to 1973, Mazda produced the second generation of the Familia model in the Presto Rotary version (in other markets R100) - with the same 982 cc two-section RPD that was installed on the Cosmo. Only the output was reduced to 100 hp. The Familia Rotary Coupe performed well in circuit racing, and its Japanese owners had another pleasant feature - reduced road tax due to the engine capacity being less than a liter

Mazda is now associated with the Skyactiv technology, with the original design and, in general, driver-friendly chassis. And in the 70-80s its second name was rotary. Despite the fact that the same Cosmo since 1975, in addition to the RPD, had conventional engines; Familia, starting in 1977, the “wankels” were completely deprived. But in the same 70s, the two-door Capella and Luce arrived, in 1978 the RX-7/Savanna debuted - for a third of a century it became the “advertising sign” of the company, its victories in the field of combating RPD. At the turn of those decades, the Japanese became so bold that they “turbocharged” the “rotors”, bringing the power of the then new 1.3-liter 13B engine first to 160 and then to 215 hp. What did you have to fight with?

In 1990–96 Mazda released another interesting model, which became a continuation of the Cosmo line - Eunos Cosmo. It was equipped with a three-section (654x3, 1962 cc) twin-turbo 20B engine, developing 280 hp.

Restore cannot be changed

We will not describe in detail the design of the RPD here - everything is clear from the video:

The euphoria of all those engineers - from Wankel to the Japanese - who seized on the idea of producing and fine-tuning such a motor is also understandable. Lightweight, compact, it allowed us to play with the layout of the engine compartment, getting the desired weight distribution and not limiting the choice of suspension design. And what simplicity, manufacturability and economy he promised in production! Instead of a crankshaft with its cranks, there is a short “stump” that is easy to smelt. There are no connecting rods or pistons, which are labor-intensive to manufacture. The block head as such with all its gas distribution “junk” is missing. And one of the variants of the RPD timing belt can again be seen in the video:

In addition, the reciprocating movements of pistons with connecting rods in a conventional engine are known to lead to vibration. In RPD, the rotor (or rotors with two, three or four sections), which plays the role of a piston, and the shaft associated with it rotate in one direction. Plus, the masses of these rotating parts are lower than those of a traditional motor design. Hence the lower level of vibrations and higher power. Another feature of the RPD also works for the latter - for each revolution of the rotor, the output shaft makes three revolutions. Well, it spins well, 8500 rpm is not a problem. As for reliability, one of the main postulates of mechanics says that the fewer parts there are in the unit, the higher it is. From this point of view, the “rotor” generally had to be ideal.

One of the main obvious advantages of the RPD is its compactness. So, with a classic layout and two sections, the engine can be placed within the base, that is, behind the axle of the front wheels

Alas, even the first full-scale experiments showed that RPDs have a lot of shortcomings that are not typical for piston engines. Thus, it is not devoid of vibrations, which are “provided” by the planetary pattern of rotor movement - it rotates with eccentricity around the center of mass of the entire body, that is, causing vibrations. Didn't they cause vibrations of the sealing plates, in the slang "knives", located on the tops of the rotor triangle and playing the role of piston wheels? One way or another, namely the grooves left by these parts on the inner surface of the camera (the poetic Japanese called them marks from the devil’s claws), and in general the wear of the “cylinder mirror” became what the engineers were primarily faced with. They say that the first RPDs worked for only a few hours, and a resource of four days was considered an achievement. By the advent of Ro 80, as mentioned earlier, it was increased to a maximum of 50 thousand km. Piston engines took at least six to eight times more maintenance... The surface was chromed, treated with a steel coating, and a steel strip was “melted in”, which the “knives” had to roll in. One of the latest technologies that the RX-7 and RX-8 have already received is ceramic spraying, which made it possible to increase the service life to 150–200 thousand km.

At the tops of the rotor triangle (on the left), the sealing plates are clearly visible - the main element that provides compression in the engine. Over time, they wear away the coating on which they work. What’s even worse is that when passing through the inlet and outlet windows, they bend, then they are cut off or broken and destroy the coating. In the most advanced cases (in the center), the rotor itself is mechanically damaged. Moreover, the stuffing from its movement even happens on the lids (on the right). Rust in the cooling channels is caused by water use. This also happened. The Japanese would be shocked. There are also cracks in the jumpers of the “shirt”

The RPD turned out to be not at all optimal from the point of view of mixture formation. The spherical chamber of piston engines is almost ideal for mixing gasoline with air and supplying this composition to the spark plugs. And here you get a narrow crescent-shaped cavity, where the combustible mixture burns effectively only in a small volume, near the candles, of which two are needed. In addition, the overlap phase of the intake and exhaust windows turns out to be quite wide - exhaust gases enter the intake. Gases are also capable of breaking through between cavities where various cycles occur. In addition, special nozzles on the intake stroke supply oil to the combustion chambers to lubricate the rotor fins and stator surface. Together, despite exhaust gas recirculation (EGR) and catalysts, this results in high toxicity of exhaust gases - only the RX-8 engine was brought up to Euro 4 standards. And high fuel consumption with engine oil. Even the first single-section RPDs with a volume of less than 500 cubic meters consumed more than ten liters of gasoline. The two-section 1.3-liter 13B, and even with turbocharging, consumes 14–20 l/100 km, and this is not the limit. Oil consumption is about 300 g/1000 km, but it can increase if you get carried away with the speed. Finally, the RPD is also thermally loaded - due to the large contact area of the combustion chamber with the burning mixture and exhaust gases. True, this is compensated by a fairly capacious (about ten liters) cooling system.

For the advent of the RX-8, the two-section 13B-REW was modified. The result was what was called Renesis (from the English rotary engine genesis). Of course, distributed fuel injection consists of six injectors. No turbocharging, two versions with different specifications ranging from 192 to 250 hp. and spin up to 9000 rpm. The main thing is that the exhaust windows, previously located on the walls of the chamber, moved to the side surface, which minimized the overlap phase. In addition, the intake manifold system has become more complex and efficient. It has long and short pipelines, four windows per section, valves in the path and the effect of resonant pressurization. The most powerful versions have six intake ports in each section.

The top window is inlet, the bottom is outlet. On RPDs until the 2000s, it is possible that in the 90s the release was carried out through a port located not on the side surface of the stator-cylinder - on its wall

Unfortunately, all modernizations, whether engineering or “metallurgical”, have not eliminated the problems, the presence of which is closely related to the operating principle of the RPD. For example, if fuel consumption can be reduced by working magic on the intake and exhaust, then there is no escape from oil consumption. How else to lubricate friction pairs here? Surely, no matter what you do, environmental problems will remain - due to the same oil and a “hotter” exhaust, when the still burning mixture enters the tract. And it is unlikely that it will be possible to significantly increase the life of the motor. In any case, all modern technologies for applying various coatings to the cylinder mirror of conventional engines have not led to a “resource revolution”. In general, it is strange that in 2003 Renesis was recognized as the best engine in the world (according to Engine Technology International magazine). Although the selection criteria there are unique, far from the specifics of operation, from reliability and mileage to capital.

That’s why it was strange to hear Mazda representatives say at the Tokyo Motor Show that there will be a rotary engine. The “shell” is already ready for it.

It seems that the RX-Vision concept will also feature an inline eight engine, but it seems that the decision to equip the future Gran Turismo with a rotary engine has been made. Mazda management is talking about exactly this. Let's wait... Let's remember that the Japanese stopped producing RPDs in mid-2012 - with the removal of the RX-8 model from the production line

And what awaits the buyer and owner of the “rotor” in our real conditions, when the car is purchased in Japan or after local operation? Mileage in this case is critical. After all, if the basic rules are not followed - yes, for a rotary motor they are more stringent than for a traditional one - the service life can be reduced by 1.5–2 times. So buying a car close to 100 thousand, even in Japan, even without tuning, is a lottery. One of the advantages, if you do not take into account the exoticism of the rotary Mazda, is the combination of power and volume, that is, “cubes”, for which you will have to pay customs duty. A model with a conventional 200–250 horsepower engine will cost much more.

When choosing a car in Russia, it is worth getting it diagnosed. The first thing you need to pay attention to is compression, which should not be lower than 6.5–7 atm. The second point is oil consumption. If it is not there, the oil nozzles have failed. The engine or individual sections are discarded.

It should be noted that repair of the RPD is possible. In Russia they have even learned how to restore shallow (up to 1 mm) scratches in a ceramic coating (about 100-120 thousand rubles with replacement of seals and rubber bands). But in order not to oversleep the moment when such repairs are possible, it is necessary to periodically check the compression. For example, when replacing spark plugs, this is once every 10 thousand km. By the way, the oil here is changed every 5 thousand km, and this is the case when it is better to turn to a specialized product.

Of course, one can argue about what, exactly, there is in oil for rotary engines (what kind of additives) that is not in products for “widespread use”. The manufacturer recommends a “special fluid”

In advanced situations, restoring the unit may not be practical. One section costs 90,000 rubles. The same amount is for the rotor. Together with work and small rubber parts, the cost of repairs can be half a million or more. The complete engine will cost no less. Another option is a motor rebuilt abroad. In the same America, about ten years ago, a whole enterprise appeared, engaged in the reincarnation of RPD. But even then it is hardly possible to keep within 400,000 rubles. Given that, say, an RX-8 at the age of 10–12 years can be purchased for 300–500 thousand rubles. 2008–09 Coupe Price output reaches 650–700 thousand rubles. And only cars from the last two years of production can cost close to a million. So what to do? Put “Jay Z” - at least 2.5-, at least three-liter. Of course, with it the car will have a different weight distribution, handling will change, Mazda will lose a piece of its soul. However, do not throw away the car itself, which, in addition to its original engine, has interesting qualities.

The author was lucky enough to try on the road an RX-7 with a 1.3-liter 255-horsepower Twin turbo and an RX-8 with the same engine, but naturally aspirated, with a power of 210 hp. The first is an uncompromising 2+2 coupe that doesn’t go up to 3000 rpm, but rages after that and up to six thousand. Rigid, with uninformative brakes, uncomfortable when landing, but with go-kart handling. It is not for nothing that at least the chassis, and sometimes even together with the engine, of the RX-7 becomes the basis for the construction of racing “cramps”, mainly drift ones. By the way, for the RPD there is a set of tuning components, including “knives”-seals (part of the engine preparation is presented in the video above). They squeeze up to 600 forces or more. The RX-8 is different. The “aspirated” engine comes to life from two thousand, picks up at 4500-5000 rpm and willingly spins up to 7250 rpm (the 250-horsepower version, as mentioned above, is even more torquey). Handling, brakes - everything is excellent. I liked the suspension settings better - not hard and not soft. We can talk about the notorious suspension compromise, when the car is pleasant in the city and is able to show something on the ring

Our material would be incomplete without a “domestic trace” in the history of the “rotor”. In 1974, a special design bureau RPD was created at VAZ. It is not clear whether it was possible to agree on a license with Wankel, but already in 1976 the first single-section engine appeared, developing 65-70 hp. The problems with them were the same as with the first German engines. Therefore, 50 “kopecks” from the RPD were very quickly transferred to “piston traction”. But then the KGB/MVD became interested in the unusual unit, thanks to which a two-section 120-horsepower RPD was created. Later it was installed on “fives” - “sevens” and the entire front-wheel drive family. At some point, we managed to achieve a 50,000th resource. And the installation (there is information that it is already 140-horsepower) on the VAZ-2108/09/099 “lived” up to 120 thousand. In the 90s, rotary front-wheel drive vehicles became popular. The program was discontinued either in 1998 or 2002. Even earlier - in the 60s - RPD tried to complete the Ural and Dnepr motorcycles. The story is confusing - it seems to have been a domestic development. By 1973, it was possible to obtain a working model with a power of 40 hp, which was installed on the Dnepr. Then a 48-horsepower modification appeared, air cooling was replaced with water cooling. In the mid-80s, under the RPD, which had already serviced up to 50 thousand km, they created an original chassis/motorcycle and were going to build a new plant. All this remains in the plans. In total, several dozen rotary Dneprs were produced.

Rules for operating a rotary engine

Experts recommend adhering to the following rules when servicing:

Change the oil every 3-5 thousand kilometers. A consumption of 1.5 liters per 1000 km is considered normal.
monitor the condition of oil injectors; their average life is 50 thousand.
change the air filter every 20 thousand.
use only special spark plugs, resource 30-40 thousand kilometers.
Fill the tank with gasoline no lower than AI-95, and better yet AI-98.
measure compression when changing oil. For this, a special device is used; the compression should be within 6.5-8 atmospheres.

When operating with compression below these values, a standard repair kit may not be enough - you will have to replace an entire section, and possibly the entire engine.

Tips and tricks

First of all, the rotary engine must be “fed” only with high-quality high-octane gasoline (not lower than AI-98). Only high-quality fuel avoids detonation and also slows down the process of carbon accumulation on the spark plug electrodes.

It should also be remembered that this engine is extremely sensitive not only to the quality, but also to the type of oil. For example, it is not recommended to pour synthetics, as carbon deposits quickly accumulate on the apexes and compression drops. Such a motor should only be filled with oil recommended by the manufacturer itself or a mineral water that meets all the tolerances.

Also, oil changes need to be done frequently; the oil in a rotary engine is changed every 4-5 thousand km. It is also important to change the engine air filter in a timely manner, since its contamination can lead to coking of the oil nozzles of the lubrication system. As for spark plugs, it is better to replace them every 10-15 thousand km.

As a rule, the main symptom of rotary engine problems is loss of compression, which manifests itself in difficult cold starts. Further, the problems progress, the engine starts to run poorly and even “hot”. Usually in this case, wear at the apexes, accumulation of deposits on the spark plug electrodes, etc. are obvious.

In such a situation, it is necessary to urgently go for diagnostics to specialists in the repair of internal combustion engines of this type. In practice, although repairs are complex and expensive, several centers have recently appeared in the CIS, specializing in the troubleshooting and repair of rotary engines with a guarantee.

As a rule, as part of the repair, stators, rotor seals, rotors themselves, etc. are replaced. Of course, repairs are not cheap, but they are definitely more affordable compared to buying a new power unit.

Finally, we note that, like a piston engine, a rotary engine needs to be warmed up before driving. In this case, until the motor reaches operating temperatures, the unit should not be loaded. With this approach, as well as in combination with high-quality gasoline and oil, as well as timely maintenance, there is every chance that the Mazda RX-8 rotary engine will last about 80 or even 100 thousand km without repair.

World famous cars produced with rotary engines

The Japanese company Mazda was a pioneer in the development of production cars with rotary engines. So the first Mazda Cosmo Sport was released back in 1967. The next generation, the Mazda RX-7, went on sale in 1978. Perhaps it was one of the most successful cars with a rotary engine. And the latest generation of cars with a rotary engine is the Mazda RX-8. And as a result, the most powerful non-turbocharged internal combustion engine was the Renesis engine from Mazda, with a volume of only 1.3 liters. It has a record power to engine displacement, namely 250 hp. With. In recent years, Mazda has managed to significantly improve the performance of rotary engines. Engines have become more environmentally friendly and do not require as much oil for lubrication. Other car manufacturers also produced cars with rotary engines: Audi, Mercedes. In the USSR, AvtoVAZ also produced a number of rotary engines. Rotary engines were installed on car 21079 (1.3 l 140 hp) and were planned for use in special services. In the 90s, the following rotary engines VAZ-416, VAZ-426, VAZ-526 were created at the VAZ Scientific and Technical Center.

Sources

https://dolauto.ru/informations/articles/chto-takoe-rotornyy-dvigatel/
https://krossovery.info/princip-raboty-rotornogo-dvigatelya-plyusy-i-minusy-sistemy/
https://autoleek.ru/dvigatel/dvs/ustrojstvo-rotornogo-dvs.html
https://ru.wikipedia.org/wiki/%D0%A0%D0%BE%D1%82%D0%BE%D1%80%D0%BD%D0%BE-%D0%BF%D0%BE% D1%80%D1%88%D0%BD%D0%B5%D0%B2%D0%BE%D0%B9_%D0%B4%D0%B2%D0%B8%D0%B3%D0%B0%D1% 82%D0%B5%D0%BB%D1%8C
https://zen.yandex.ru/media/halva/rotornyi-dvigatel-princip-raboty-i-tehnika-primeneniia-5ba095896ee05400aa942a3c
https://www.syl.ru/article/158520/new_rotornyiy-dvigatel-printsip-rabotyi-plyusyi-i-minusyi-rotornogo-dvigatelya
https://ZnanieAvto.ru/dvs/rotornyj-dvigatel-vnutrennego-sgoraniya.html

How does a rotary engine differ from a conventional engine?

Technical progress does not stand still, and today, along with the most common piston engine, a rotary piston version can also be found on the automotive market. Today you will learn what a rotary engine is and how it differs from a conventional engine, which is installed in almost all modern cars.

What is RPD?

In order to compare a rotary engine with a piston engine, it is necessary to fully understand what it is. Like the piston version, the rotary engine uses the pressure that appears during the combustion of the fuel-air mixture. The name itself comes from the main part - the moving rotor, due to which the engine operates. The rotor has a triangle-like shape and is attached to a special mechanism. It is noteworthy that its rotation does not occur around a specific axis, but as if it is running around a gear.

The engine has 4 phases: Intake, compression, ignition, exhaust. First, the fuel-air mixture is sucked into the first chamber, where it is mixed. Then, using a rotor, it is compressed into the next chamber and lit with candles. Afterwards the mixture goes further, where the used parts of the fuel are forced out and everything starts all over again.

Today, only the company is engaged in serial production of cars with a rotary engine. Admittedly, they performed well, especially when the company was not so large and took a big risk by launching such engine options.

Advantages over a conventional internal combustion engine

The advantages over a conventional engine turned out to be enough to allow them to be mass-produced and become a serious corporation. What are the advantages of a rotary engine over a conventional one:

Thanks to the mechanical balance of the engine, it has noticeably less vibration during operation, which affects comfort in passenger cars;
The high dynamics of the engine allows you to accelerate the car in low gear to speeds of over 100 km/h at high speeds.
More power with less volume. The 1.3-liter engine can produce up to 250 horsepower. Thanks to this, in Japan, where the main office is located, they were very popular with a high fuel tax;
Fewer moving parts and smaller dimensions. If a piston internal combustion engine has at least 40 moving parts, then, for example, in a two-rotor engine there are only 3 - 2 rotors and an output shaft;
Environmentally friendly. Although the RPD emits too much hydrocarbon, its nitrogen oxide emissions are significantly less than those of conventional internal combustion engines. But even the problem with hydrocarbons was solved by Japanese engineers. After the introduction of the Clean Air Act in the United States, Mazda engines underwent several modifications that reduced hydrocarbon emissions;

Disadvantages of a rotary engine

Like everything in this world, the rotary engine also has its disadvantages:

The price of an engine can sometimes be steep. This is due to the not very popular rotary engines. At one time, the West also considered options for using RPDs, but the idea was quickly rejected and considered obsolete. Interestingly, tests were also carried out in Russia as a variant of cars for special services, but the idea also did not take root due to insufficient funding from the state. Only the Japanese managed to launch serial production of such engines. Therefore, the price is quite high;
High fuel consumption. Due to the fact that the combustion chamber is larger than a typical piston internal combustion engine, it requires more fuel. This is one of the most important disadvantages of the rotary engine version. Moreover, with fuel prices constantly rising in Russia;