As you know, the operating principle of a rotary engine is based on high speeds and the absence of movements that distinguish an internal combustion engine. This is what distinguishes the unit from. The RPD is also called the Wankel engine, and today we will look at its operation and obvious advantages.

The video describes the design and operating principle of the Zheltyshev rotary engine:

Surprisingly, they tried to introduce RPD in our country. Such an engine was developed 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 manufacturer Mazda will improve the engine and will soon release it with a completely different unit.

Let's take a look inside the RPD

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

The RPD is named so because of the rotor, that is, which 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, as mentioned above, has the shape of a triangle.

The video shows the operating principle of the Zuev rotary piston engine:

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 like this. In the first cavity formed, suction occurs, that is, the chamber is filled with air, 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.

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.

In addition, it was possible to improve the rotary engine. Today, Mazda rotary engines have not one, but two or even three rotors, which significantly increases performance, especially when compared with a conventional internal combustion engine. For comparison: a two-rotor RPD is comparable to a six-cylinder internal combustion engine, and a 3-rotor one is comparable to a twelve-cylinder one. So it turns out that the Japanese turned out to be so far-sighted and immediately recognized the advantages of the rotary engine.

Again, performance is not the only advantage 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.

The operating principle of a rotary piston engine once made many talented engineers raise their eyebrows in surprise. And today talented engineers 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!

In 1957, German engineers Felix Wankel and Walter Freude demonstrated the first working rotary engine. Just seven years later, its improved version took its place under the hood of the German sports car NSU-Spider - the first production car with such an engine. Many automobile companies bought the new product - Mercedes-Benz, Citroen, General Motors. Even VAZ produced cars with Wankel engines in small batches for many years. But the only company that decided on large-scale production of rotary engines and did not abandon them for a long time, despite any crises, was Mazda. Its first model with a rotary engine, the Cosmo Sports (110S), appeared back in 1967.

A STRANGER AMONG THEIR OWN

In a piston engine, the combustion energy of the air-fuel mixture is first converted into reciprocating motion of the piston group, and only then into rotation of the crankshaft. In a rotary engine, this happens without an intermediate stage, which means with less losses.

There are two versions of the gasoline 1.3‑liter naturally aspirated 13B-MSP with two rotors (sections) - standard power (192 hp) and forced (231 hp). Structurally, it is a sandwich of five buildings that form two sealed chambers. In them, under the influence of the energy of combustion of gases, rotors rotate, mounted on an eccentric shaft (similar to a crankshaft). This movement is very tricky. Each rotor not only rotates, but rolls its internal gear around a stationary gear fixed in the center of one of the side walls of the chamber. The eccentric shaft passes through the entire sandwich of housings and stationary gears. The rotor moves in such a way that for every revolution there are three revolutions of the eccentric shaft.

In a rotary engine, the same cycles are carried out as in a four-stroke piston unit: intake, compression, power stroke and exhaust. At the same time, it does not have a complex gas distribution mechanism - timing drive, camshafts and valves. All its functions are performed by the inlet and outlet windows in the side walls (casings) - and the rotor itself, which, when rotating, opens and closes the “windows”.

The operating principle of a rotary engine is shown in the diagram. For simplicity, an example of a motor with one section is given - the second functions in the same way. Each side of the rotor forms its own working cavity with the walls of the housings. In position 1, the cavity volume is minimal, and this corresponds to the beginning of the intake stroke. As the rotor rotates, the inlet windows open and the air-fuel mixture is sucked into the chamber (positions 2–4). In position 5, the working cavity has a maximum volume. Next, the rotor closes the intake windows and the compression stroke begins (positions 6–9). In position 10, when the volume of the cavity is again minimal, the mixture is ignited with the help of candles and the working stroke begins. The energy of combustion of gases rotates the rotor. Gas expansion occurs up to position 13, and the maximum volume of the working cavity corresponds to position 15. Further, up to position 18, the rotor opens the exhaust windows and pushes out the exhaust gases. Then the cycle begins again.

The remaining working cavities work the same way. And since there are three cavities, then in one revolution of the rotor there are as many as three working strokes! And taking into account that the eccentric (crank) shaft rotates three times faster than the rotor, the output is one power stroke (useful work) per shaft revolution for a single-section motor. For a four-stroke piston engine with one cylinder, this ratio is half as much.

In terms of the ratio of the number of power strokes per revolution of the output shaft, the two-section 13B-MSP is similar to a conventional four-cylinder piston engine. But at the same time, with a displacement of 1.3 liters, it produces approximately the same amount of power and torque as a piston engine with 2.6 liters! The secret is that a rotary motor has several times less moving masses - only the rotors and the eccentric shaft rotate, and even then in one direction. With a piston engine, part of the useful work is spent on driving a complex timing mechanism and the vertical movement of the pistons, which constantly changes its direction. Another feature of a rotary engine is its higher resistance to detonation. That is why it is more promising for working on hydrogen. In a rotary engine, the destructive energy of abnormal combustion of the working mixture acts only in the direction of rotation of the rotor - this is a consequence of its design. But in a piston engine it is directed in the opposite direction to the movement of the piston, which causes disastrous consequences.

Wankel engine: NOT EVERYTHING IS SO SIMPLE

Although a rotary engine has fewer elements than a piston engine, it uses more sophisticated design solutions and technologies. But parallels can be drawn between them.

The rotor housings (stators) are made using sheet metal insertion technology: a special steel substrate is inserted into the aluminum alloy housing. Thanks to this, the design is light and durable. The steel backing is chrome plated with microscopic grooves for better oil retention. In fact, such a stator resembles a familiar cylinder with a dry sleeve and a hone on it.

The side housings are made of special cast iron. Each has inlet and outlet windows. And stationary gears are attached to the outer ones (front and rear). Motors of previous generations had these windows in the stator. That is, in the new design they increased their size and number. Due to this, the characteristics of the intake and exhaust of the working mixture have improved, and at the output - the engine efficiency, its power and fuel efficiency. The side housings paired with the rotors can be compared in functionality to the timing mechanism of a piston engine.

The rotor is essentially the same piston and at the same time a connecting rod. Made of special cast iron, hollow, as lightweight as possible. On each side there is a cuvette-shaped combustion chamber and, of course, seals. A rotor bearing is inserted into the inner part - a kind of connecting rod bearing for the crankshaft.

If a conventional piston uses only three rings (two compression rings and one oil scraper ring), then the rotor has several times more such elements. Thus, apexes (seals at the tops of the rotor) play the role of the first compression rings. They are made of cast iron with electron beam processing - to increase wear resistance in contact with the stator wall.

Apexes consist of two elements - the main seal and the corner. They are pressed against the stator wall by a spring and centrifugal force. The role of the second compression rings is played by the side and corner seals. They ensure gas-tight contact between the rotor and the side housings. Like the apexes, they are pressed against the walls of the housings by their springs. The side seals are cermet (they bear the main load), and the corner seals are made of special cast iron. There are also insulating seals. They prevent some of the exhaust gases from flowing into the intake ports through the gap between the rotor and the side housing. On both sides of the rotor there are also something like oil scraper rings - oil seals. They retain the oil supplied to its internal cavity for cooling.

The lubrication system is also sophisticated. It has at least one radiator for cooling the oil when the engine is running under heavy loads and several types of oil nozzles. Some are built into the eccentric shaft and cool the rotors (essentially similar to piston cooling jets). Others are built into the stators - a pair for each. The nozzles are located at an angle and directed towards the walls of the side housings - for better lubrication of the housings and side seals of the rotor. The oil enters the working cavity and mixes with the air-fuel mixture, providing lubrication to the remaining elements, and burns along with it. Therefore, it is important to use only mineral oils or special semi-synthetics approved by the manufacturer. Unsuitable combustion lubricants produce a large amount of carbon deposits, which leads to detonation, misfires and reduced compression.

The fuel system is quite simple - except for the number and location of injectors. Two are in front of the intake windows (one per rotor), and the same number are in the intake manifold. There are two more injectors in the manifold of the forced engine.

The combustion chambers are very long, and in order for the combustion of the working mixture to be efficient, it was necessary to use two spark plugs for each rotor. They differ from each other in length and electrodes. To avoid incorrect installation, colored marks are applied to the wires and spark plugs.

IN PRACTICE

The service life of the 13B-MSP engine is approximately 100,000 km. Oddly enough, it suffers from the same problems as the piston one.

The first weak link seems to be the rotor seals, which experience high heat and high loads. This is true, but before natural wear and tear they will be finished off by detonation and wear and tear of the eccentric shaft bearings and rotors. Moreover, only the end seals (apexes) suffer, and the side seals wear out extremely rarely.

Detonation deforms the apexes and their seats on the rotor. As a result, in addition to reducing compression, the seal corners can fall out and damage the surface of the stator, which cannot be machined. Boring is useless: firstly, it is difficult to find the necessary equipment, and secondly, there are simply no spare parts for the increased size. Rotors cannot be repaired if the grooves for the apexes are damaged. As usual, the root of the problem is the quality of fuel. Honest 98 gasoline is not so easy to find.

The main bearings of the eccentric shaft wear out the fastest. Apparently, due to the fact that it rotates three times faster than the rotors. As a result, the rotors receive a displacement relative to the stator walls. And the tops of the rotors should be equidistant from them. Sooner or later, the corners of the apexes fall out and lift the surface of the stator. There is no way to predict this misfortune - unlike a piston engine, a rotary engine practically does not knock even when the liners wear out.

With forced supercharged engines, there are cases when the apex overheats due to a very lean mixture. The spring underneath bends it - as a result, compression drops significantly.

The second weakness is uneven heating of the case. The upper part (here the intake and compression strokes occur) is cooler than the lower part (combustion and exhaust strokes). However, the body is deformed only for forced supercharged engines with a power of more than 500 hp.

As you would expect, the engine is very sensitive to the type of oil. Practice has shown that synthetic oils, even special ones, form a lot of carbon deposits during combustion. It accumulates at the apexes and reduces compression. You need to use mineral oil - it burns almost without a trace. Servicemen recommend changing it every 5000 km.

Oil nozzles in the stator fail mainly due to dirt getting into the internal valves. Atmospheric air enters them through the air filter, and untimely replacement of the filter leads to problems. The injector valves cannot be washed.

Problems with cold starting of the engine, especially in winter, are caused by loss of compression due to wear at the apexes and the appearance of deposits on the electrodes of the spark plugs due to low-quality gasoline.

The spark plugs last for an average of 15,000–20,000 km.

Contrary to popular belief, the manufacturer recommends turning off the engine as usual, and not at medium speeds. “Experts” are confident that when the ignition is turned off in operating mode, all remaining fuel is burned and this facilitates the subsequent cold start. According to servicemen, such tricks are of no use. But what will really be beneficial for the engine is at least a little warming up before starting to move. With warm oil (not lower than 50º), its wear will be less.

With high-quality troubleshooting of the rotary engine and subsequent repairs, it will last another 100,000 km. Most often, replacement of stators and all rotor seals is required - for this you will have to pay at least 175,000 rubles.

Despite the above problems, there are plenty of fans of rotary machines in Russia - to say nothing of other countries! Although Mazda itself has discontinued the rotary V8 and is in no hurry to produce its successor.

Mazda RX-8: ENDURANCE TEST

In 1991, the Mazda 787B with a rotary engine won the 24 Hours of Le Mans race. This was the first and only victory of a car with such an engine. By the way, now not all piston engines survive to the finish line in “long” endurance races.

The main types of internal combustion engines and steam engines have one common drawback. It consists in the fact that reciprocating motion requires transformation into rotational motion. This, in turn, causes low performance, as well as fairly high wear of mechanism parts included in various types of engines.

Quite a lot of people have thought about creating a motor in which the moving elements only rotate. However, only one person managed to solve this problem. Felix Wankel, a self-taught mechanic, became the inventor of the rotary piston engine. During his life, this man did not receive any specialty or higher education. Let's take a closer look at the Wankel rotary piston engine.

Brief biography of the inventor

Felix G. Wankel was born in 1902, on August 13, in the small town of Lahr (Germany). During the First World War, the father of the future inventor died. Because of this, Wankel had to quit studying at the gymnasium and get a job as a sales assistant in a book sales shop at a publishing house. Thanks to this, he became addicted to reading. Felix studied engine specifications, automotive engineering, and mechanics on his own. He gained knowledge from books that were sold in the shop. It is believed that the later implemented Wankel engine circuit (more precisely, the idea of ​​its creation) came to me in a dream. It is not known whether this is true or not, but we can say for sure that the inventor had extraordinary abilities, a passion for mechanics and a unique

Advantages and disadvantages

The converted movement of a reciprocating nature is completely absent in a rotary engine. Pressure is generated in those chambers that are created using the convex surfaces of the triangular rotor and various parts of the housing. The rotor performs rotational movements with the help of combustion. This can reduce vibration and increase rotation speed. Due to the increased efficiency that results from this, the rotary engine is much smaller in size than a conventional piston engine of equivalent power.

A rotary engine has one main component among all its components. This important component is called a triangular rotor, which rotates inside the stator. All three vertices of the rotor, thanks to this rotation, have a constant connection with the inner wall of the housing. With the help of this contact, combustion chambers are formed, or three closed-type volumes with gas. When the rotor rotates inside the housing, the volume of all three formed combustion chambers changes all the time, reminiscent of the actions of a conventional pump. All three side surfaces of the rotor act like a piston.

Inside the rotor is a small gear with external teeth, which is attached to the housing. The gear, which is larger in diameter, is connected to this fixed gear, which sets the very trajectory of the rotational movements of the rotor inside the housing. The teeth in the larger gear are internal.

Due to the fact that the rotor is connected eccentrically to the output shaft, the rotation of the shaft occurs in the same way as a handle would rotate a crankshaft. The output shaft will rotate three times for each rotor revolution.

The rotary engine has the advantage of low weight. The most basic of the rotary engine blocks is small in size and weight. At the same time, the controllability and performance of such an engine will be better. It has less weight due to the fact that there is simply no need for a crankshaft, connecting rods and pistons.

The rotary engine has dimensions that are much smaller than a conventional engine of the same power. Thanks to the smaller engine size, handling will be much better, and the car itself will become more spacious, both for passengers and the driver.

All of the parts of a rotary engine perform continuous rotational movements in the same direction. Changing their movement occurs in the same way as in the pistons of a traditional engine. Rotary engines are internally balanced. This leads to a decrease in the vibration level itself. The rotary engine's power feels much smoother and more even.

The Wankel engine has a special convex rotor with three edges, which can be called its heart. This rotor performs rotational movements inside the cylindrical surface of the stator. The Mazda rotary engine is the world's first rotary engine that was developed specifically for mass production. This development began back in 1963.

What is RPD?

In a classic four-stroke engine, the same cylinder is used for different operations - injection, compression, combustion and exhaust. In a rotary engine, each process is performed in a separate chamber compartment. The effect is not unlike dividing a cylinder into four compartments for each operation.
In a piston engine, the pressure created by the combustion of the mixture forces the pistons to move back and forth in their cylinders. The connecting rods and crankshaft convert this pushing motion into the rotational motion needed to propel the vehicle.
In a rotary engine there is no linear motion that would need to be converted into rotational motion. Pressure is generated in one of the chamber compartments causing the rotor to rotate, this reduces vibration and increases the potential engine speed. The result is greater efficiency and smaller dimensions with the same power as a conventional piston engine.

How does RPD work?

The function of the piston in the RPD is performed by a three-vertex rotor, which converts the gas pressure force into the rotational movement of the eccentric shaft. The movement of the rotor relative to the stator (outer housing) is ensured by a pair of gears, one of which is rigidly fixed to the rotor, and the second to the side cover of the stator. The gear itself is fixedly mounted on the engine housing. The rotor gear is in mesh with it and the gear wheel seems to roll around it.
The shaft rotates in bearings located on the housing and has a cylindrical eccentric on which the rotor rotates. The interaction of these gears ensures the appropriate movement of the rotor relative to the housing, as a result of which three separate chambers of variable volume are formed. The gear ratio is 2:3, so for one revolution of the eccentric shaft the rotor returns 120 degrees, and for a full revolution of the rotor a full four-stroke cycle occurs in each chamber.

Gas exchange is regulated by the rotor apex as it passes through the inlet and outlet ports. This design allows for a 4-stroke cycle without the use of a special gas distribution mechanism.

Sealing of the chambers is ensured by radial and end sealing plates, which are pressed against the cylinder by centrifugal forces, gas pressure and band springs. Torque is obtained as a result of the action of gas forces through the rotor on the eccentric shaft Mixture formation, inflammation, lubrication, cooling, starting - fundamentally the same as in a conventional piston internal combustion engine

Mixing formation

In theory, several types of mixture formation are used in RPD: external and internal, based on liquid, solid, and gaseous fuels.
Regarding solid fuels, it is worth noting that they are initially gasified in gas generators, as they lead to increased ash formation in the cylinders. Therefore, gaseous and liquid fuels have become more widespread in practice.
The mechanism of mixture formation in Wankel engines will depend on the type of fuel used.
When using gaseous fuel, it is mixed with air in a special compartment at the engine inlet. The combustible mixture enters the cylinders in finished form.

The mixture is prepared from liquid fuel as follows:

1. The air is mixed with liquid fuel before entering the cylinders, where the combustible mixture enters.
2. Liquid fuel and air enter the engine cylinders separately, and they are mixed inside the cylinder. The working mixture is obtained when they come into contact with residual gases.

Accordingly, the fuel-air mixture can be prepared outside the cylinders or inside them. This leads to the separation of engines with internal or external mixture formation.

Technical characteristics of the rotary piston engine

options	VAZ-4132	VAZ-415
number of sections	2	2
Engine chamber displacement, cc	1,308	1,308
compression ratio	9,4	9,4
Rated power, kW (hp) / min-1	103 (140) / 6000	103 (140) / 6000
Maximum torque, N * m (kgf * m) / min-1	186 (19) / 4500	186 (19) / 4500
Minimum eccentric shaft rotation speed at idle, min-1	1000	900
Engine weight, kg
Overall dimensions, mm
Oil consumption as a % of fuel consumption
Engine life before the first major overhaul, thousand km
appointment	VAZ-21059/21079	VAZ-2108/2109/21099/2115/2110

models are produced

	RPD engine	Acceleration time 0-100, sec	Maximum speed, km\h
	The final efficiency of the motor consists of three main parts: Research in this area shows that only 75% of fuel burns completely. It is believed that this problem can be solved by separating the combustion and expansion processes of gases. It is necessary to provide for the arrangement of special chambers under optimal conditions. Combustion must occur in a closed volume, subject to an increase in temperature and pressure; the expansion process must occur at low temperatures. Mechanical efficiency (characterizes the work that resulted in the formation of the main axis torque transmitted to the consumer). About 10% of the engine's work is spent on driving auxiliary components and mechanisms. This defect can be corrected by making changes to the engine design: when the main moving working element does not touch the stationary body. A constant torque arm must be present along the entire path of the main working element. Thermal efficiency (an indicator reflecting the amount of thermal energy generated from the combustion of fuel, converted into useful work). In practice, 65% of the generated thermal energy escapes with exhaust gases into the external environment. A number of studies have shown that it is possible to achieve an increase in thermal efficiency in the case where the design of the motor would allow combustion of fuel in a thermally insulated chamber, so that maximum temperatures are reached from the very beginning, and at the end this temperature is reduced to minimum values ​​by turning on the vapor phase. Wankel rotary piston engine

In the distant 1957 German engineers Wankel and Freude introduced the world to the first rotary engine. Then it was adopted by most automobile companies. Mercedes, and even - they all put rotary engines under the hood of their cars. And the Japanese still use the rotor to this day - although in a modern, improved modification. What makes the Wankel rotary engine successful?

Operating principle of a rotary piston engine

The rotary engine performs the same four strokes as its piston counterpart: intake, compression, power stroke, exhaust. But the rotor works differently. A piston engine performs four strokes in one cylinder. And although the rotary one performs them in one chamber, each of the cycles takes place in its separate part. That is, the cycle seems to be performed in a separate cylinder, and the piston “runs” from one cylinder to another. At the same time, the rotary engine does not have a gas distribution mechanism. Unlike a piston engine, all the work is done by the intake and exhaust ports located in the side housings. The rotor rotates and regulates the operation of the windows: it opens and closes them.

By the way, about the rotor. Needless to say, it is the main element of the motor; it is the rotor that gives the name to the engine itself. What kind of detail is this? The rotor has a triangular shape, it is immovably attached to the eccentric shaft and is mounted off-center on it. When rotated, the element describes a capsule-shaped shape, rather than a circle, due to its location. The rotor transmits power from the engine to the gearbox and clutch; in other words, it pushes out the burnt fuel and transmits rotation to the transmission to the wheels. The cavity in which the rotor rotates is made in the shape of a capsule.

The operating principle of a rotary piston engine is as follows. When rotating, the rotor creates three cavities around itself, isolated from each other. This happens due to the capsule shape of the cavity around the rotor and the triangular shape of the rotor itself. First cavity - suction cavity, it mixes fuel with oxygen. Next, the mixture is distilled into the second chamber by the movement of the rotor and compressed there. Here it is ignited by two spark plugs, it expands and pushes the piston. The rotor rotates in a forward motion, opening the next cavity where exhaust gases and remaining fuel escape.

Disadvantages and advantages of a rotary engine

Like any other internal combustion engine, a rotary engine has both pros and cons. First, let's look at its advantages over other engines.

1. The performance of a rotary engine is several times higher than others. While in conventional internal combustion engines one stroke passes per revolution, then in a rotary engine - three(suction, compression, ignition). Moreover, modern engines are equipped with two or three rotors at once, so a 2-rotor engine can be compared with a 6-cylinder conventional internal combustion engine, and a 3-rotor engine can be compared with 12 cylinders.

2. Few parts. The simplicity of the motor design (rotor and stator) allows the use of fewer parts. Statistics say that an internal combustion engine has 1000 more parts than a rotary engine.

3. Low vibration level. The rotor rotates in a circle without making reciprocating movements. Accordingly, vibration is practically not noticeable. In addition, there are usually two rotary engines, so they balance each other's work.

4. High dynamic performance. In one revolution, the engine completes three strokes. Therefore, even at low speeds the engine develops high speed.

5. Compactness and light weight. Due to the simplicity of the design and the small number of parts, the motor has a small weight and size.

Despite many advantages, the engine also has several disadvantages that do not allow car companies to use it en masse on their cars.

1. Tendency to overheat. During combustion of the working mixture, radiant energy is generated, which aimlessly leaves the combustion chamber and heats the engine. This is due to the shape of the camera, which resembles a capsule or lens, that is, having a small volume, it has a large working surface. To prevent energy from escaping, the chamber had to be spherical.

2.Regular oil changes. The rotor is connected to the output shaft by an eccentric mechanism. This connection method causes additional pressure, which, coupled with high temperatures, heats up the engine. That is why you need to periodically take your car for overhaul and change the oil. Without an oil change, the engine fails.

3. Regular replacement of seals. Increased pressure is generated on the small contact area between the rotor and the shaft. The seals wear out and leaks form in the chambers. As a result, exhaust toxicity increases and efficiency decreases. By the way, on new models this problem was solved by using high-alloy steel.

4.High price. For rotary engines, parts must be manufactured with high geometric accuracy. Therefore, expensive equipment and expensive materials are used in the production of rotary engines. As a result, the price of a rotary motor is high despite the apparent simplicity of the design.

Application of rotary engines: from invention to the present day

Engineers have been developing rotary engines for a very long time. Steam engine inventor James Watt marked the beginning of the dream of a rotary engine. In 1846, engineers had already determined the shape of the combustion chamber and the basics of operation of a rotary internal combustion engine. But the engine remained a dream. But in 1924 The young and talented Felix Wankel began thorough practical work on creating a rotary engine. The twenty-two-year-old engineer had just graduated from high school and entered a technical literature publishing house. It was then that Wankel began to draw up a design for his own engine, relying on extensive theoretical knowledge from the literature. Having created his own laboratory, the engineer began to receive patents for products. In 1934, Wankel applied to the first rotary engine.

But fate decreed otherwise. The talented engineer was noted by the authorities, and he began working for the largest automobile concerns of Nazi Germany. He had to postpone his projects. After the war the engineer was in prison, as an accomplice of the Nazi regime, and his laboratory was taken away by the French. And only in 1951 the scientist restored his name by starting to work for a motorcycle company. There he rebuilt his laboratory and recruited another scientist named Walter Freude to the rotary engine project. Together they released the first rotary engine on February 1, 1957. Initially it ran on methanol, but by July the engine was switched to gasoline. In the 50s, Germany began to recover from the consequences of the war, and accordingly, automobile companies became richer.

The NSU company, where Wankel and Freude worked, was preparing to mass produce cars with a rotary engine. In 1960, the NSU Spider with a Wankel engine under the hood was shown in Munich. And in 1968, NSU Ro-80 was released, which influenced further automotive production. The car accelerated to 180 km/h, from a standstill the car accelerated to 100 km/h in 12.8 s. The Ro-80 became the car of the year, and many concerns bought the rights to the Wankel engine. But due to shortcomings in the engine design and the high cost of production, companies refused to mass produce cars with a rotary engine. But there were prototypes.

For example, Mercedes-Benz, which released the C111 car in 1970. A stylish orange car with a streamlined, reliable body accelerated to 100 km/h in 4.8 seconds. But the gluttony of the car did not allow the company to mass produce the C111.

We became interested in the rotor and... Already in 1972, the first Corvette with a two-section rotary engine was presented to the public. Four-box Corvettes appeared in 1973, but in 1974, due to lack of money, Chevrolet shelved work on rotary engines. Neighboring France also adopted Wankel engines. In 1974, Citroen launched the Citroen GS Birotor. Under the hood was a two-section Wankel engine. But the car was not popular. In two years, the French company sold only 874 cars. In 1977, Citroen recalled the rotary cars with the aim of eliminating them, but it is likely that 200 of them were able to survive.

The USSR also tried to use the Wankel engine. They couldn’t buy a license at the VAZ factories, so they copied a single-section rotary motor from the NSU Ro-80. On its basis, the VAZ-311 engine was assembled in 1976. The development lasted 6 years. The first production VAZ with a rotor under the hood was 21018. But the model failed miserably. All 50 prototypes broke down. In 1983, two-section rotor models appeared in the USSR. Equipped with such an engine, Zhiguli and Volga easily caught up with foreign cars. But then the design bureau turned away from the automotive industry and unsuccessfully tried to use the rotary engine in aviation. This led to the developing industry settling on the VAZ-415 model in 1995.

Until 2012, the Mazda RX-8 model was mass-produced, with an improved Wankel engine. In general, the Japanese are the only ones who have mass-produced rotary machines since 1967. In the 70s, Mazda introduced the RX brand, which denotes the use of rotary engines. The Japanese installed a rotor on any car, including pickups and buses. Maybe that's why the RX-8 has excellent technical and environmental characteristics, which was so unusual for the first cars with a Wankel engine.

“Most people associate it with cylinders and pistons, the gas distribution system and the crank mechanism. This is because the vast majority of cars are equipped with the classic and most popular type of engine - piston.

Today we will talk about the Wankel rotary piston engine, which has a whole set of outstanding technical characteristics, and at one time was supposed to open up new prospects in the automotive industry, but could not take its rightful place and did not become widespread.

History of creation

The very first rotary-type heat engine is considered to be the aeolipile. In the first century AD, it was created and described by the Greek mechanical engineer Heron of Alexandria.

The design of the aeolipile is quite simple: a rotating bronze sphere is located on an axis passing through the center of symmetry. Water vapor, used as a working fluid, flows out of two nozzles installed in the center of the ball opposite each other and perpendicular to the mounting axis.


The mechanisms of water and windmills, using the force of the elements as energy, can also be attributed to the rotary engines of antiquity.

Classification of rotary engines

The working chamber of a rotary internal combustion engine can be hermetically sealed or have a constant connection with the atmosphere when it is separated from the environment by the rotor impeller blades. Gas turbines are built on this principle.

Among rotary piston engines with closed combustion chambers, experts distinguish several groups. Separation can occur according to: the presence or absence of sealing elements, according to the operating mode of the combustion chamber (intermittent-pulsating or continuous), according to the type of rotation of the working body.

It is worth noting that most of the structures described do not have working samples and they exist on paper.
They were classified by the Russian engineer I.Yu. Isaev, who is himself busy creating a perfect rotary engine. He analyzed patents from Russia, America and other countries, more than 600 in total.

Rotary internal combustion engine with reciprocating motion

The rotor in such engines does not rotate, but performs a reciprocating arc swing. The blades on the rotor and stator are stationary, and expansion and compression strokes occur between them.

With pulsating-rotational, unidirectional movement

There are two rotating rotors in the engine housing; compression occurs between their blades when they approach each other, and expansion occurs when they move away. Due to the fact that the rotation of the blades occurs unevenly, the development of a complex alignment mechanism is required.

With sealing flaps and reciprocating movements

The scheme, successfully used in pneumatic motors, where rotation is carried out by compressed air, has not taken root in internal combustion engines due to high pressure and temperatures.

With seals and reciprocating body movements

The scheme is similar to the previous one, only the sealing flaps are located not on the rotor, but on the engine housing. The disadvantages are the same: the inability to ensure sufficient tightness of the housing blades with the rotor while maintaining their mobility.

Engines with uniform movement of the working and other elements

The most promising and advanced types of rotary engines. Theoretically, they can develop the highest speeds and gain power, but so far it has not been possible to create a single working scheme for internal combustion engines.

With planetary, rotational movement of the working element

The latter includes the most widely known rotary piston engine design by engineer Felix Wankel.

Although there are a huge number of other planetary-type designs:

• Umpleby
• Gray & Dremmond
• Marshall
• Spand
• Renault
• Thomas
• Wallinder & Skoog
• Sensand
• Maillard
• Ferro

Wankel history

The life of Felix Heinrich Wankel was not easy; he was left an orphan at an early age (the father of the future inventor died in the First World War), Felix could not raise funds to study at the university, and his working specialty did not allow him to obtain severe myopia.

This prompted Wankel to independently study technical disciplines, thanks to which in 1924 he came up with the idea of ​​​​creating a rotary engine with a rotating internal combustion chamber.


In 1929, he received a patent for the invention, which became the first step towards the creation of the famous Wankel RPD. In 1933, the inventor, finding himself in the ranks of Hitler's opponents, spent six months in prison. After liberation, the BMW company became interested in the development of a rotary engine and began to finance further research, allocating a workshop in Landau for the work.

After the war, it goes to the French as reparation, and the inventor himself goes to prison as an accomplice of the Hitler regime. Only in 1951 did Felix Heinrich Wankel get a job at the NSU motorcycle manufacturing company and continue his research.


In the same year, he began working together with the chief designer of NSU, Walter Freude, who himself had long been engaged in research in the field of creating a rotary piston engine for racing motorcycles. In 1958, the first sample of the engine took place on the test bench.

How does a rotary engine work?

The power unit designed by Freude and Wankel is a rotor made in the shape of a Reuleaux triangle. The rotor rotates planetarily around a gear mounted in the center of the stator - a stationary combustion chamber. The chamber itself is made in the form of an epitrochoid, which vaguely resembles a figure eight with an elongated center; it acts as a cylinder.

Moving inside the combustion chamber, the rotor forms cavities of variable volume in which engine strokes occur: intake, compression, ignition and exhaust. The chambers are hermetically separated from each other by seals - apexes, the wear of which is the weak point of rotary piston engines.

The fuel-air mixture is ignited by two spark plugs at once, since the combustion chamber has an elongated shape and a large volume, which slows down the combustion rate of the working mixture.

On a rotary engine, a retarded angle is used rather than an advanced angle, as on a piston engine. This is necessary so that ignition occurs a little later, and the force of the explosion pushes the rotor in the desired direction.

The Wankel design made it possible to significantly simplify the engine and eliminate many parts. There was no longer a need for a separate gas distribution mechanism, and the weight and size of the engine were significantly reduced.

Advantages

As mentioned earlier, the Wankel rotary engine does not require as many parts as a piston engine, therefore it is smaller in size, weight and power density (number of “horses” per kilogram of weight).

There is no crank mechanism (in the classic version), which makes it possible to reduce weight and vibration load. Due to the absence of reciprocating movements of the pistons and the low mass of moving parts, the engine can develop and maintain very high speeds, reacting almost instantly to pressing the gas pedal.

A rotary internal combustion engine produces power at three quarters of each revolution of the output shaft, while a piston engine produces power at only one quarter.

Flaws

It is precisely because the Wankel engine, for all its advantages, has a large number of disadvantages, that today only Mazda continues to develop and improve it. Although the patent for it was bought by hundreds of companies, including Toyota, Alfa Romeo, General Motors, Daimler-Benz, Nissan and others.

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.

High consumption

All cars with rotary engines have high fuel consumption.

In addition to Mazda, there were also Mercedes C-111, Corvette XP-882 Four Rotor (four-section, 4-liter capacity), Citroen M35, but these were mostly experimental models, and because of the oil crisis that flared up in the 80s, their production was suspended .

The short stroke length of the rotor and the crescent shape of the combustion chamber do not allow the working mixture to burn out completely. The exhaust port opens even before complete combustion; the gases do not have time to transfer the full force of pressure to the rotor. That is why the temperature of the exhaust gases of these engines is so high.

History of domestic RPD

In the early 80s, the USSR also became interested in technology. True, the patent was not purchased, and they decided to come up with everything on their own, in other words, to copy the operating principle and design of the Mazda rotary engine.

For these purposes, a design bureau was created, and a workshop for mass production was created in Togliatti. In 1976, the first prototype of a single-section VAZ-311 engine with a power of 70 hp. With. installed on 50 cars. In a very short period of time, they developed a resource. The poor balance of the REM (rotary-eccentric mechanism) and the rapid wear of the apexes made themselves felt.


However, the development became interested in the special services, for whom the dynamic characteristics of the engine were much more important than the resource. In 1982, the VAZ-411 two-section rotary engine saw the light of day, with a rotor width of 70 cm and a power of 120 hp. s., and VAZ-413 with a rotor of 80 cm and 140 hp. With. Later, VAZ-414 engines were used to equip KGB, traffic police and Ministry of Internal Affairs vehicles.

Since 1997, the VAZ-415 power unit has been installed on public cars, and the Volga appears with a three-section VAZ-425 RPD. Today in Russia, cars are not equipped with such engines.

List of cars with rotary piston engine

Brand	Model
NSU	Spider
	Ro80
Mazda	Cosmo Sport (110S)
	Familia Rotary Coupe
	Parkway Rotary 26
	Capella (RX-2)
	Savanna (RX-3)
	RX-4
	RX-7
	RX-8
	Eunos Cosmo
	Rotary Pickup
	Luce R-130
Mercedes	C-111
XP-882 Four Rotor
Citroen	M35
	GS Birotor (GZ)
VAZ	21019 (Arcanum)
	2105-09
GAS	21
	24
	3102

List of Mazda rotary engines

Type	Description
40A	First bench copy, rotor radius 90 mm
L8A	Dry sump lubrication system, rotor radius 98 mm, volume 792 cc. cm
10A (0810)	Two-piece, 982 cu. cm, power 110 l. pp., mixing oil with fuel for lubrication, weight 102 kg
10A (0813)	100 l. pp., weight increase up to 122 kg
10A (0866)	105 l. pp., REAPS emission reduction technology
13A	For front-wheel drive R-130, volume 1310 cc. cm, 126 l. s., rotor radius 120 mm
12A	Volume 1146 cc. cm, the rotor material is strengthened, the stator life is increased, the seals are made of cast iron
12A Turbo	Semi-direct injection, 160 l. With.
12B	Single ignition distributor
13B	The most popular engine, volume 1308 cc. cm, low emissions
13B-RESI	135 l. p.s., RESI (Rotary Engine Super Injection) and Bosch L-Jetronic injection
13B-DEI	146 l. p., variable intake, 6PI and DEI systems, injection with 4 injectors
13B-RE	235 l. pp., large HT-15 and small HT-10 turbines
13B-REW	280 l. p., 2 sequential turbines Hitachi HT-12
13B-MSP Renesis	Eco-friendly and economical, can run on hydrogen
13G/20B	Three-rotor motor racing engines, 1962 cc. cm, power 300 l. With.
13J/R26B	Four-rotor, for auto racing, volume 2622 cc. cm, power 700 l. With.
16X (Renesis 2)	300 l. pp., Taiki concept car

Rules for operating a rotary engine

1. Change the oil every 3-5 thousand kilometers. A consumption of 1.5 liters per 1000 km is considered normal.
2. monitor the condition of oil injectors; their average life is 50 thousand.
3. change the air filter every 20 thousand.
4. use only special spark plugs, resource 30-40 thousand kilometers.
5. Fill the tank with gasoline no lower than AI-95, and better yet AI-98.
6. 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.

Today's day

Today, the Mazda RX-8 is in serial production, equipped with a Renesis engine (abbreviation Rotary Engine + Genesis).


The designers managed to reduce oil consumption by half and fuel consumption by 40%, and brought the environmental class to the Euro-4 level. The engine with a displacement of 1.3 liters produces a power of 250 hp. With.

Despite all the achievements, the Japanese do not stop there. Contrary to the claims of most experts that RPD has no future, they do not stop improving the technology, and not so long ago they presented the concept of the RX-Vision sports coupe, with a SkyActive-R rotary engine.