Car engine piston: the part is worthy of praise. Rotary piston engine What does a piston look like in an engine?
- ensures the transmission of mechanical forces to the connecting rod;
- is responsible for sealing the fuel combustion chamber;
- ensures timely removal of excess heat from the combustion chamber
Piston operation takes place in difficult and in many ways dangerous conditions - at elevated temperatures and increased loads, therefore it is especially important that pistons for engines are efficient, reliable and wear-resistant. That is why light but ultra-strong materials are used for their production - heat-resistant aluminum or steel alloys. Pistons are made by two methods - casting or stamping.
Piston design
The engine piston has a fairly simple design, which consists of the following parts:
Volkswagen AG
- ICE piston head
- Piston pin
- Retaining ring
- Boss
- connecting rod
- Steel insert
- Compression ring first
- Second compression ring
- Oil scraper ring
The design features of the piston in most cases depend on the type of engine, the shape of its combustion chamber and the type of fuel that is used.
Bottom
The bottom can have different shapes depending on the functions it performs - flat, concave and convex. The concave shape of the bottom ensures more efficient operation of the combustion chamber, but this contributes to greater formation of deposits during fuel combustion. The convex shape of the bottom improves the performance of the piston, but at the same time reduces the efficiency of the combustion process of the fuel mixture in the chamber.
Piston rings
Below the bottom there are special grooves (grooves) for installing piston rings. The distance from the bottom to the first compression ring is called the fire belt.
Piston rings are responsible for a reliable connection between the cylinder and the piston. They provide reliable tightness due to their tight fit to the cylinder walls, which is accompanied by intense friction. Motor oil is used to reduce friction. Cast iron alloy is used to make piston rings.
The number of piston rings that can be installed in a piston depends on the type of engine used and its purpose. Often systems are installed with one oil scraper ring and two compression rings (first and second).
Oil ring and compression rings
The oil scraper ring ensures timely removal of excess oil from the inner walls of the cylinder, and compression rings prevent gases from entering the crankcase.
The compression ring, located first, absorbs most of the inertial loads during piston operation.
To reduce loads, in many engines a steel insert is installed in the ring groove, which increases the strength and compression ratio of the ring. Compression rings can be made in the shape of a trapezoid, barrel, cone, or with a cutout.
In most cases, the oil scraper ring is equipped with many holes for oil drainage, sometimes with a spring expander.
Piston pin
This is a tubular part that is responsible for the reliable connection of the piston to the connecting rod. Made from steel alloy. When installing the piston pin in the bosses, it is tightly secured with special retaining rings.
The piston, piston pin and rings together form the so-called piston group of the engine.
Skirt
The guiding part of the piston device, which can be made in the shape of a cone or barrel. The piston skirt is equipped with two bosses for connection to the piston pin.
To reduce friction losses, a thin layer of anti-friction substance is applied to the surface of the skirt (graphite or molybdenum disulfide is often used). The lower part of the skirt is equipped with an oil scraper ring.
A mandatory process of operation of a piston device is its cooling, which can be carried out by the following methods:
- splashing oil through holes in the connecting rod or nozzle;
- movement of oil along the coil in the piston head;
- supplying oil to the ring area through the annular channel;
- oil mist
Sealing part
The sealing part and the bottom are connected to form the piston head. In this part of the device there are piston rings - oil scraper and compression. The ring passages have small holes through which waste oil enters the piston and then drains into the crankcase.
In general, the piston of an internal combustion engine is one of the most heavily loaded parts, which is subject to strong dynamic and at the same time thermal influences. This imposes increased requirements both on the materials used in the production of pistons and on the quality of their manufacture.
The piston occupies a central place in the process of converting the chemical energy of the fuel into thermal and mechanical energy. Let's talk about pistons of an internal combustion engine, what they are and their main purpose in operation.
WHAT IS AN ENGINE PISTON?
Engine piston- this is a cylindrical part that performs a reciprocating movement inside the cylinder and serves to convert changes in gas, steam or liquid pressure into mechanical work, or vice versa - reciprocating movement into a change in pressure. Initially, pistons for automobile internal combustion engines were cast from cast iron. With the development of technology, aluminum began to be used, because it provided the following advantages: increased speed and power, lower loads on parts, better heat transfer.
Since then, engine power has increased many times, the temperature and pressure in the cylinders of modern automobile engines (especially diesel engines) have become such that aluminum has reached its strength limit. Therefore, in recent years, such engines have been equipped with steel pistons that can confidently withstand increased loads. They are lighter than aluminum due to thinner walls and lower compression height, i.e. distance from the bottom to the axis of the aluminum pin. And the steel pistons are not cast, but prefabricated.
Among other things, reducing the vertical dimensions of the piston while keeping the cylinder block unchanged makes it possible to lengthen the connecting rods. This will reduce the lateral loads in the piston-cylinder pair, which will have a positive effect on fuel consumption and engine life. Or, without changing the connecting rods and crankshaft, you can shorten the cylinder block and thus lighten the engine
The piston performs a number of important functions:
- ensures the transmission of mechanical forces to the connecting rod;
- is responsible for sealing the fuel combustion chamber;
- ensures timely removal of excess heat from the combustion chamber
Piston operation takes place in difficult and in many ways dangerous conditions - at elevated temperatures and increased loads, therefore it is especially important that pistons for engines are efficient, reliable and wear-resistant. That is why light but ultra-strong materials are used for their production - heat-resistant aluminum or steel alloys. Pistons are made by two methods - casting or stamping.
Extreme conditions determine the material used to make the pistons
The piston is operated under extreme conditions, characterized by high pressure, inertial loads and temperatures. That is why the main requirements for materials for its manufacture include:
- high mechanical strength;
- good thermal conductivity;
- low density;
- low coefficient of linear expansion, antifriction properties;
- good corrosion resistance.
The required parameters are met by special aluminum alloys, which are characterized by strength, heat resistance and lightness. Less commonly, gray cast iron and steel alloys are used in the manufacture of pistons.
Pistons can be:
- cast;
- forged.
In the first version, they are made by injection molding. Forged ones are made by stamping from an aluminum alloy with a small addition of silicon (on average, about 15%), which significantly increases their strength and reduces the degree of piston expansion in the operating temperature range.
Piston design
The engine piston has a fairly simple design, which consists of the following parts:
- ICE piston head
- Piston pin
- Retaining ring
- Boss
- connecting rod
- Steel insert
- Compression ring first
- Second compression ring
- Oil scraper ring
The design features of the piston in most cases depend on the type of engine, the shape of its combustion chamber and the type of fuel that is used.
Bottom
The bottom can have different shapes depending on the functions it performs - flat, concave and convex. The concave shape of the bottom ensures more efficient operation of the combustion chamber, but this contributes to greater formation of deposits during fuel combustion. The convex shape of the bottom improves the performance of the piston, but at the same time reduces the efficiency of the combustion process of the fuel mixture in the chamber.
Piston rings
Below the bottom there are special grooves (grooves) for installing piston rings. The distance from the bottom to the first compression ring is called the fire belt.
Piston rings are responsible for a reliable connection between the cylinder and the piston. They provide reliable tightness due to their tight fit to the cylinder walls, which is accompanied by intense friction. Motor oil is used to reduce friction. Cast iron alloy is used to make piston rings.
The number of piston rings that can be installed in a piston depends on the type of engine used and its purpose. Often systems are installed with one oil scraper ring and two compression rings (first and second).
TYPES OF PISTONS
In internal combustion engines, two types of pistons are used, differing in design - solid and composite.
Solid parts are manufactured by casting followed by machining. The metal casting process creates a blank that is given the overall shape of the part. Next, on metalworking machines, the working surfaces in the resulting workpiece are processed, grooves are cut for rings, technological holes and recesses are made.
In the component parts, the head and skirt are separated, and they are assembled into a single structure during installation on the engine. Moreover, assembly into one part is carried out by connecting the piston to the connecting rod. For this purpose, in addition to the holes for the piston pin in the skirt, there are special eyes on the head.
The advantage of composite pistons is the ability to combine manufacturing materials, which improves the performance of the part.
Removal of excess heat from the piston
Along with significant mechanical loads, the piston is also exposed to the negative effects of extremely high temperatures. Heat is removed from the piston group:
- cooling system from the cylinder walls;
- the internal cavity of the piston, then the piston pin and connecting rod, as well as the oil circulating in the lubrication system;
- partially cold air-fuel mixture supplied to the cylinders.
From the inner surface of the piston, its cooling is carried out using:
Oil ring and compression rings
The oil scraper ring ensures timely removal of excess oil from the inner walls of the cylinder, and compression rings prevent gases from entering the crankcase.
The compression ring, located first, absorbs most of the inertial loads during piston operation.
To reduce loads, in many engines a steel insert is installed in the ring groove, which increases the strength and compression ratio of the ring. Compression rings can be made in the shape of a trapezoid, barrel, cone, or with a cutout.
In most cases, the oil scraper ring is equipped with many holes for oil drainage, sometimes with a spring expander.
Piston pin
This is a tubular part that is responsible for the reliable connection of the piston to the connecting rod. Made from steel alloy. When installing the piston pin in the bosses, it is tightly secured with special retaining rings.
The piston, piston pin and rings together form the so-called piston group of the engine.
Skirt
The guiding part of the piston device, which can be made in the shape of a cone or barrel. The piston skirt is equipped with two bosses for connection to the piston pin.
To reduce friction losses, a thin layer of anti-friction substance is applied to the surface of the skirt (graphite or molybdenum disulfide is often used). The lower part of the skirt is equipped with an oil scraper ring.
A mandatory process in the operation of a piston device is its cooling, which can be carried out using the following methods:
- splashing oil through holes in the connecting rod or nozzle;
- movement of oil along the coil in the piston head;
- supplying oil to the ring area through the annular channel;
- oil mist
Sealing part
The sealing part and the bottom are connected to form the piston head. In this part of the device there are piston rings - oil scraper and compression. The ring passages have small holes through which waste oil enters the piston and then drains into the crankcase.
In general, the piston of an internal combustion engine is one of the most heavily loaded parts, which is subject to strong dynamic and at the same time thermal influences. This imposes increased requirements both on the materials used in the production of pistons and on the quality of their manufacture.
The engine piston is a cylindrical part that performs reciprocating movements inside the cylinder. It is one of the most characteristic engine parts, since the implementation of the thermodynamic process occurring in the internal combustion engine occurs precisely with its help. Piston:
- sensing gas pressure, transmits the resulting force to;
- seals the combustion chamber;
- removes excess heat from it.
The photo above shows the four strokes of an engine piston.
Extreme conditions determine the material used to make the pistons
The piston is operated under extreme conditions, characterized by high pressure, inertial loads and temperatures. That is why the main requirements for materials for its manufacture include:
- high mechanical strength;
- good thermal conductivity;
- low density;
- low coefficient of linear expansion, antifriction properties;
- good corrosion resistance.
Pistons can be:
- cast;
- forged.
The design features of the piston are determined by its purpose
The main conditions that determine the design of the piston are the type of engine and the shape of the combustion chamber, the features of the combustion process taking place in it. Structurally, the piston is a solid element consisting of:
- heads (bottoms);
- sealing part;
- skirts (guide part).
Is the piston of a gasoline engine different from that of a diesel engine? The surfaces of the piston heads of gasoline and diesel engines are structurally different. In a gasoline engine, the surface of the head is flat or close to it. Sometimes there are grooves in it to facilitate full opening of the valves. The pistons of engines equipped with a direct fuel injection system (DNFT) have a more complex shape. The piston head in a diesel engine is significantly different from a gasoline engine - thanks to the combustion chamber in it having a given shape, better swirl and mixture formation are ensured.
The photo shows a diagram of the engine piston.
Piston rings: types and composition
The sealing part of the piston includes piston rings that ensure a tight connection between the piston and the cylinder. The technical condition of the engine is determined by its sealing ability. Depending on the type and purpose of the engine, the number of rings and their location are selected. The most common scheme is a scheme of two compression rings and one oil scraper ring.
Piston rings are made mainly from special gray high-strength cast iron, which has:
- high stable indicators of strength and elasticity under operating temperatures throughout the entire service life of the ring;
- high wear resistance under conditions of intense friction;
- good anti-friction properties;
- the ability to quickly and effectively break in to the cylinder surface.
The main purpose of the compression ring is to prevent gases from the combustion chamber from entering the engine crankcase. Especially heavy loads fall on the first compression ring. Therefore, when making rings for the pistons of some high-performance gasoline and all diesel engines, a steel insert is installed, which increases the strength of the rings and allows for maximum compression. The shape of compression rings can be:
- trapezoidal;
- barrel-shaped;
- tconical.
The oil scraper ring is responsible for removing excess oil from the cylinder walls and preventing it from penetrating into the combustion chamber. It is distinguished by the presence of many drainage holes. Some rings are designed with spring expanders.
The shape of the piston guide (otherwise known as the skirt) can be cone-shaped or barrel-shaped, which allows you to compensate for its expansion when high operating temperatures are reached. Under their influence, the shape of the piston becomes cylindrical. In order to reduce losses caused by friction, the side surface of the piston is covered with a layer of antifriction material; for this purpose, graphite or molybdenum disulfide is used. Thanks to the holes with bosses made in the piston skirt, the piston pin is fastened.
A unit consisting of a piston, compression and oil rings, as well as a piston pin is usually called a piston group. The function of its connection with the connecting rod is assigned to a steel piston pin, which has a tubular shape. The requirements are:
- minimal deformation during operation;
- high strength under variable load and wear resistance;
- good shock resistance;
- low mass.
- fixed in the piston bosses, but rotates in the connecting rod head;
- secured in the connecting rod head and rotate in the piston bosses;
- freely rotating in the piston bosses and in the connecting rod head.
Fingers installed according to the third option are called floating. They are the most popular because they wear lightly and evenly along the length and circumference. When using them, the risk of jamming is minimized. In addition, they are easy to install.
Removal of excess heat from the piston
Along with significant mechanical loads, the piston is also exposed to the negative effects of extremely high temperatures. Heat is removed from the piston group:
- cooling system from the cylinder walls;
- the internal cavity of the piston, then the piston pin and connecting rod, as well as the oil circulating in the lubrication system;
- partially cold air-fuel mixture supplied to the cylinders.
- splashing oil through a special nozzle or hole in the connecting rod;
- oil mist in the cylinder cavity;
- injecting oil into the ring area, into a special channel;
- circulation of oil in the piston head along a tubular coil.
Video about a four-stroke engine - operating principle:
Piston is one of the parts of the engine crank mechanism and is an integral element conventionally divided into a head and a skirt. It is the basis of the process of converting fuel combustion energy into thermal energy, and then into mechanical energy. The performance of the engine, as well as its reliability and durability, directly depends on the quality of this part.
Purpose and types of pistons
In an engine, the engine piston performs a number of functions, in particular:
- transformation of gas pressure into force transmitted to the connecting rod;
- ensuring the tightness of the combustion chamber;
- heat sink
The piston operates in extreme conditions under consistently high mechanical loads. Therefore, for modern engines they are made from special aluminum alloys, which are lightweight and durable with sufficient heat resistance. Steel pistons are somewhat less common. Previously, they were mainly made from cast iron. The piston markings that are necessarily present on each product will tell you what it is made of. These parts are manufactured using two methods – casting and stamping. Forged pistons, common in tuning, are made by stamping rather than hand-forged.
Piston design
The piston design is not complicated. This is a solid part, which, for ease of definition, is conventionally divided into a skirt and a head. The specific shape and design features of the piston are determined by the type and model of the engine. In common types of gasoline internal combustion engines, you can only see pistons with flat heads or heads that are extremely close to this shape. They often have grooves designed to allow the valves to open as fully as possible. In engines with direct fuel injection, the pistons are made in a slightly more complex form. The piston of a diesel engine has a head with a specific configuration to ensure optimal swirl for the purpose of high-quality mixture formation.
Engine piston diagram.
Under the head there are grooves on the piston into which the piston rings are installed. The skirts of different pistons are also different: with a shape similar to a cone or barrel. This configuration makes it possible to compensate for the expansion of the piston that occurs when it heats up during operation. It should be noted that the piston acquires its full working volume only after the engine has warmed up to normal temperature.
To minimize the effect of constant lateral friction of the piston on the cylinder, a special anti-friction material is applied to its side surface, the type of which also depends on the type of engine. Also in the piston skirt there are special holes with bosses intended for mounting the piston pin.
The operation of the piston involves intense heating. It is cooled, and in different motors in different ways. Here are the most common ones:
- by supplying oil mist into the cylinder;
- through oil splashing through a connecting rod or a special nozzle;
- through oil injection through an annular channel;
- using constant circulation of oil through a coil located directly in the piston head.
It is not the piston itself that comes into close contact with the cylinder walls, but its rings. To ensure the highest wear resistance, they are made from a special type of cast iron. The number and exact location of these rings depends on the type of motor. Most often, the piston has a pair of compression rings and another oil scraper ring.
Compression rings are designed to prevent gases from the combustion chamber from breaking into the crankcase. The first ring bears the heaviest load, therefore, in all diesel and powerful gasoline engines, a steel insert is additionally present in the groove of the first ring, which increases the strength of the structure. There are many types of compression rings, which are unique to almost every independent manufacturer.
Oil scraper rings- to remove excess oil from the cylinder and prevent it from entering the combustion chamber. Such rings are made with a large number of drainage holes, as well as with spring expanders, although not in all engine models.
Piston device
The engine piston is connected to the connecting rod through a piston pin, a tubular steel part. The most common method of attaching a pin is a floating one, thanks to which the part can be rotated during operation. Special locking rings prevent the pin from moving to the sides. Hard finger hooking is practically not common at the moment due to the obvious greater vulnerability of such structures.
Breakage of the piston and related parts
During intensive or simply prolonged use, the piston may fail due to the presence of a foreign body in the cylinder, which the piston constantly bumps into during movement. Such an object could be a particle of a connecting rod, or something else flying away from the part. The surfaces of such a fracture are gray in color and are not characterized by abrasion, cracks or other visual signs. The piston disintegrates quickly and suddenly.
A fracture caused by metal fatigue is characterized by the formation of raster lines in the problem area. This allows you to determine in advance whether there is a breakdown and replace the piston. In addition to aging, the cause of such a fracture can be detonation ignition, increased piston shaking due to the collision of its head with the cylinder head, or excessive skirt clearance. In any case, cracks form on the part, indicating its imminent failure.
After ring wear, damage to the piston head is the most common.
In addition to wear and tear of the metal, piston-related failures can occur for a variety of reasons, including:
- violation of the combustion mode, for example due to ignition delay;
- improper organization of starting a cold engine;
- filling the cylinder with oil or water with the engine off, which is called;
- unreasonable increase in power as a result of electronics reconfiguration;
- use of unsuitable parts;
- other reasons.
Most often, repairs are carried out by replacing the piston, rings or the entire piston group.
Related terms
Rotary piston engine (RPE), or Wankel engine. An internal combustion engine developed by Felix Wankel in 1957 in collaboration with Walter Freude. In a RPD, the function of a piston is performed by a three-vertex (triangular) rotor, which performs rotational movements inside a cavity of complex shape. After a wave of experimental automobiles and motorcycles in the 1960s and 1970s, interest in RPDs has waned, although a number of companies are still working to improve the Wankel engine design. Currently, Mazda passenger cars are equipped with RPD. The rotary piston engine is used in modeling.
Principle of operation
The force of gas pressure from the burnt fuel-air mixture drives a rotor mounted through bearings on an eccentric shaft. The movement of the rotor relative to the engine housing (stator) is carried out through a pair of gears, one of which, larger, is fixed on the inner surface of the rotor, the second, supporting, smaller, is rigidly attached to the inner surface of the side cover of the engine. The interaction of the gears leads to the fact that the rotor makes circular eccentric movements, touching the edges with the inner surface of the combustion chamber. As a result, three isolated chambers of variable volume are formed between the rotor and the engine body, in which the processes of compression of the fuel-air mixture, its combustion, expansion of gases that exert pressure on the working surface of the rotor, and purification of the combustion chamber from exhaust gases occur. The rotational movement of the rotor is transmitted to an eccentric shaft mounted on bearings and transmitting torque to the transmission mechanisms. Thus, two mechanical pairs operate simultaneously in the RPD: the first one regulates the movement of the rotor and consists of a pair of gears; and the second - converting the circular motion of the rotor into rotation of the eccentric shaft. The gear ratio of the rotor and stator gears is 2:3, so in one full revolution of the eccentric shaft the rotor manages to rotate 120 degrees. In turn, for one full revolution of the rotor in each of the three chambers formed by its faces, a full four-stroke cycle of the internal combustion engine is performed.
RPD diagram
1 - inlet window; 2 outlet window; 3 - body; 4 - combustion chamber; 5 – fixed gear; 6 - rotor; 7 – gear; 8 - shaft; 9 – spark plug
Advantages of RPD
The main advantage of a rotary piston engine is its simplicity of design. The RPD has 35-40 percent fewer parts than a four-stroke piston engine. The RPD does not have pistons, connecting rods, or a crankshaft. In the “classic” version of the RPD there is no gas distribution mechanism. The fuel-air mixture enters the working cavity of the engine through the inlet window, which opens the edge of the rotor. Exhaust gases are ejected through an exhaust port, which again intersects the edge of the rotor (this resembles the gas distribution device of a two-stroke piston engine).
The lubrication system deserves special mention, which is practically absent in the simplest version of the RPD. Oil is added to the fuel - as when operating two-stroke motorcycle engines. Lubrication of friction pairs (primarily the rotor and the working surface of the combustion chamber) is carried out by the fuel-air mixture itself.
Since the mass of the rotor is small and is easily balanced by the mass of the counterweights of the eccentric shaft, the RPD is characterized by a low level of vibration and good uniformity of operation. In cars with RPD, it is easier to balance the engine, achieving a minimum level of vibration, which has a good effect on the comfort of the car as a whole. Twin-rotor engines are particularly smooth, in which the rotors themselves act as vibration-reducing balancers.
Another attractive quality of the RPD is its high power density at high speeds of the eccentric shaft. This makes it possible to achieve excellent speed characteristics from a vehicle with RPD with relatively low fuel consumption. Low rotor inertia and increased specific power compared to piston internal combustion engines make it possible to improve vehicle dynamics.
Finally, an important advantage of the RPD is its small size. A rotary engine is approximately half the size of a four-stroke piston engine of the same power. And this allows you to more rationally use the space of the engine compartment, more accurately calculate the location of transmission components and the load on the front and rear axles.
Disadvantages of RPD
The main disadvantage of a rotary piston engine is the low efficiency of sealing the gap between the rotor and the combustion chamber. The RPD rotor, which has a complex shape, requires reliable seals not only along the faces (and there are four of them for each surface - two on the apical faces, two on the side faces), but also on the side surface in contact with the engine covers. In this case, the seals are made in the form of spring-loaded strips of high-alloy steel with particularly precise processing of both working surfaces and ends. The tolerances built into the design of the seals for metal expansion from heating worsen their characteristics - it is almost impossible to avoid gas breakthrough at the end sections of the sealing plates (in piston engines they use a labyrinth effect, installing sealing rings with gaps in different directions).
In recent years, seal reliability has increased dramatically. Designers have found new materials for seals. However, there is no need to talk about any breakthrough yet. Seals still remain the bottleneck of RPD.
The complex rotor seal system requires effective lubrication of the rubbing surfaces. RPM consumes more oil than a four-stroke piston engine (from 400 grams to 1 kilogram per 1000 kilometers). In this case, the oil burns along with the fuel, which has a bad effect on the environmental friendliness of the engines. There are more substances hazardous to human health in the exhaust gases of RPDs than in the exhaust gases of piston engines.
Special requirements are also imposed on the quality of oils used in RPD. This is due, firstly, to a tendency to increased wear (due to the large area of contacting parts - the rotor and the internal chamber of the engine), and secondly, to overheating (again due to increased friction and due to the small size of the engine itself ). Irregular oil changes are deadly for RPDs - since abrasive particles in old oil dramatically increase engine wear and engine overcooling. Starting a cold engine and insufficiently warming it up lead to the fact that there is little lubrication in the contact area of the rotor seals with the surface of the combustion chamber and side covers. If a piston engine seizes when overheated, then the RPD most often occurs when starting a cold engine (or when driving in cold weather, when cooling is excessive).
In general, the operating temperature of RPMs is higher than that of piston engines. The most thermally stressed area is the combustion chamber, which has a small volume and, accordingly, an increased temperature, which makes it difficult to ignite the fuel-air mixture (RPDs, due to the extended shape of the combustion chamber, are prone to detonation, which can also be attributed to the disadvantages of this type of engine). Hence the RPD’s demands on the quality of candles. They are usually installed in these engines in pairs.
Rotary piston engines, despite their excellent power and speed characteristics, turn out to be less flexible (or less elastic) than piston engines. They produce optimal power only at fairly high speeds, which forces designers to use RPDs paired with multi-stage gearboxes and complicates the design of automatic transmissions. Ultimately, RPDs turn out to be not as economical as they should be in theory.
Practical application in the automotive industry
RPDs became most widespread in the late 60s and early 70s of the last century, when the patent for the Wankel engine was purchased by 11 leading automakers in the world.
In 1967, the German company NSU released a serial business class passenger car, the NSU Ro 80. This model was produced for 10 years and sold around the world in the amount of 37,204 copies. The car was popular, but the shortcomings of the RPD installed in it ultimately ruined the reputation of this wonderful car. Compared to long-lasting competitors, the NSU Ro 80 model looked “pale” - the mileage before engine overhaul at the stated 100 thousand kilometers did not exceed 50 thousand.
Citroen, Mazda, and VAZ have experimented with RPD. The greatest success was achieved by Mazda, which released its passenger car with RPD back in 1963, four years earlier than the appearance of the NSU Ro 80. Today, the Mazda concern equips RX series sports cars with RPD. Modern Mazda RX-8 cars are free from many of the shortcomings of the Felix Wankel RPD. They are quite environmentally friendly and reliable, although they are considered “capricious” among car owners and repair specialists.
Practical application in the motorcycle industry
In the 70s and 80s, some motorcycle manufacturers experimented with RPD - Hercules, Suzuki and others. Currently, small-scale production of “rotary” motorcycles is established only in the Norton company, which produces the NRV588 model and is preparing the NRV700 motorcycle for serial production.
Norton NRV588 is a sportbike equipped with a twin-rotor engine with a total volume of 588 cubic centimeters and developing a power of 170 horsepower. With a dry motorcycle weight of 130 kg, the power supply of a sportbike looks literally prohibitive. The engine of this car is equipped with variable intake tract and electronic fuel injection systems. All that is known about the NRV700 model is that the RPM power of this sportbike will reach 210 hp.