Why does Subaru have such a characteristic digging of the exhaust? What is the opposite engine - the pros and cons of the occurrence of the oppository.

The opposite engine is called the engine with horizontal layout of the pistons, that is, the pistons move horizontally relative to the car body. Such a layout is often found on Subaru engines ,.

In the opposite engine, the pistons are located at an angle of 180 °, and their movement is in one horizontal plane relative to each other. Neighboring pistons in the opposite engine are located equally relative to each other. The second name "oppositors" is "Boxer", this name the motors received for the feature of the movement of the pistons, which resembles the battle of boxers. The sound of the opposite motor is difficult to confuse with the sound of an ordinary motor.

Unlike the classic V-shaped, the Opposite Motor has each piston with a connecting rod located on a separate rod crankshaft neck. In V-shaped motors, pistons and connecting rods are on a single rod cervical neck, so if one piston is in the upper dead point (NMT), then the second is in the lower NTC.

The main undeniable "pros" of the opposite engine:

1. Minimum vibration during operation;
2. Low center of gravity;
3. High security in the event of a frontal collision. In the event of a frontal blow, the motor goes under the car, which allows the driver and passenger to survive in an accident and get out of it with minimal injuries.
4. Excellent stability, the car, what is called "holds the road" and perfectly copes even with the coolest turns.
5. The location in one plane with transmission provides the most efficient power transmission.

At the same time, with all the above advantages, the opposite motor has a different problem, due to the features of the design on the engine, the inertia strengths that are trying to deploy it around the vertical axis. The weight of this type of engines is most often much lower than that of V-shaped analogs, this is possible to achieve due to the installation

What do we know about the opposite engine? The fact that the pistons in it move horizontally. That this engine is the face of the Subaru cars. Perhaps all. Let's find out a little more.

The opposite engine is one of the layout of the internal combustion engine, in which the pistons are at an angle of 180 ° and move in a horizontal plane to each other and from each other. At the same time, two adjacent pistons are always in the same position, for example in the upper dead point.

The movement of the pistons in the engine resembles a duel of boxers, so another name of the opposite engine - boxer (Boxer). A feature of the design of the opposite engine is the installation of each piston with a connecting rod on a separate rod crankshaft neck. The opposite engine always has an even number of cylinders (2, 4, 6, 8, 10, 12). The most common four- and six-cylinder "opposites".

The opposite engine does not need to be confused with the V-shaped engine and the corner of the cylinders of 180 °. With external similarity in such an engine, adjacent pistons with connecting rods are located on one rod cervical. Therefore, when one piston reaches the top of the dead point, the other is at the bottom of the dead point.

The indisputable advantages of the opposite motor are the low center of gravity, minimal vibrations when working and a high level of safety at a front collision.

Displays down the center of gravity of the opposite motor allows you to achieve better stability and car charter. Lowly located engine is on a single axis with transmission, which achieves more efficient power transmission.

The opposite engine is almost completely devoid of vibrations (there is only a moment from the second order inertia strength, striving to deploy the engine around the vertical axis). Mutually agreed movement of neighboring pistons provides smooth operation of the engine. Mass balance in the opposite engine allows you to install a crankshaft on three native bearings (instead of the usual five), which significantly reduces the engine length and its weight.

The opposite engine more complies with the requirements of passive security. With a front collision, the motor goes down under the car and, thereby, retains the life of passengers in the cabin. No less important for drivers dignity of the opposite engine is the characteristic sound of its work, differing from other engineers.

Unfortunately, the opposite engine is not deprived of the flaws. The most serious, in our opinion, is a high laboriousness of repair work, associated with a feature of the engine design. So, to perform individual repairs, removal of the engine from the car is required. In some sources, it is noted that the horizontal movement of the piston leads to uneven wear of the cylinder sleeve and, as a result, increased oil consumption. Due to certain overall sizes, the opposite engine is installed on the car only longitudinally.

Currently, opposite engines are developing and installed on their cars of Subaru and Porsche. Previously, the opposite engine could be seen on Alfa Romeo cars, Citroen, Chevrolet, Honda, Lancia, Toyota, Volkswagen and even Ferrari.

Subaru uses opposite engines since 1963. It's four- and six-cylinder Boxer.. The history of four-cylinder engines from Subaru has three generations: series EA. (1966-1994); series EJ. (1989-1998, crankshaft on 5 native bearings, 1999-2010, crankshaft on three native bearings); series FB. (since 2010). Six-cylinder Boxer went into production slightly later - series ER (1987-1991), series EG (1992-1997), series EZ. (since 1999).

The absolute majority of opposite motors are gasoline engines with a distributed fuel injection and the upper gas distribution system. They have one (SOHC) or two (DOHC) camshafts, which are driven by a crankshaft with a toothed belt or chain. Despite the different amount of camshafts in engines, a four-shield gas exchange scheme is implemented. A number of engines are equipped with turbocharged.

The third generation four-cylinder boxer turned out to be simpler, compact, economical and harmless. To reduce fuel consumption, reduce emissions toxicity, increasing the magnitude of the torque and expanding its border in new engines, many progressive technical solutions are used:

• increased the degree of compression by increasing the piston stroke and reduce the volume of the combustion chamber;
• reduced the weight of moving parts (connecting rod, piston, crankshaft) due to the manufacture of forging;
• in the camshafts of intake and exhaust valves, a gas distribution phase change system (active control system AVCS) is used;
• a new oil pump is applied, providing high lubrication quality and an increase in the engine resource;
• cooling system with separate contours to cool the cylinder block and block head is used.

In 2008, Subaru first introduced diesel Opposite Engine. A four-cylinder engine, a volume of 2.0 liters, develops the power of 150 hp. It uses a Common Rail injection system, a turbocharging system with a turbine with a variable geometry.

Six-cylinder opposite engines are installed on a series of models of cars Porsche (911, Boxster, Cayman). At one time, 8 and 12-cylinder opposite engines were developed for use in the car racing.

The opposite is called the engine, the cylinders of which are horizontally relative to each other. A similar structure of the structure is name: a V-shaped engine with an angle of collapse of cylinders of 180 degrees. From English, the word "Opposite" is translated - "Located opposite". Consider the opposite engine - pluses and cons.

Features of the opposite motor

Despite the similarity with the V-shaped motor, the oppositor has nothing to do with it. The difference is that in the oppository, two adjacent pistons are located in one plane relative to each other. In a V-shaped piston engines when driving at certain points occupy the position of the upper and lower "dead point". In the oppository, they simultaneously reach either the upper "dead point" or lower. Such an improvement in the V-shaped motor was obtained by the location of the cylinders at the unfolded angle.

Another innovation was the location of gas distribution mechanisms in the vertical plane. All this freed the design of power units from imbalance and increased vibrations, and movement on the car made the most comfortable as possible. Now vibrations from the engine are not transmitted to the body and do not shake the car.

Opposite motors always have an even number of cylinders. Four and six-cylinder engines received the greatest distribution.

Features of the design of the Power Unit type "Boxer" have significant advantages over other types of motors:

The center of gravity is shifted down;
Economical fuel consumption;
Low vibration level;
enlarged motor resource;
Passive safety with a frontal collision.

Displaced down the center of gravity allows to achieve the best sustainability of auto and optimal controllability with active maneuvers and
Cool turns. During sudden turns, the roll is significantly reduced. The arrangement of the engine on one axis with transmission provides better power transmission. The absence of equilibrium shafts saves fuel consumption.

Engine runs in smooth mode. The low level of vibration of the motor is achieved due to the agreed rotation of the adjacent pistons. The location of the crankshaft on three bearings, instead of five ordinary, is another advantage of the opposite engine. This significantly reduces the mass of the engine and its length.

The arrangement of the pistons in the horizontal plane gives the system greater rigidity, which significantly reduces the mechanical losses during the operation of the power unit.

Passive security is ensured by the fact that when a collision, the motor easily goes down under the car. As a result, there is a decrease in the intensity of the strike on the passenger interior.

The increased diameter of the cylinders provides the motor high speed, which makes it possible to create a sports type model on this database.

Another feature is the characteristic sound when operating the opposite power unit: it is more pleasant for hearing.

Disadvantages of the opposite engine.

The advantages of the opposite engine are obvious. The disadvantages are:

Labor-intensive repair;
Elevated motor oil consumption.

To repair the engine, it is completely removed. However, this is not the problem. Details for replacement are very expensive, and the engine harvest delivers considerable headaches. If the driver can replace the candles on the repair of the row motor, then it is impossible in the oppository. Any repairs must be carried out on special equipment that is only available on a hundred.

The history of the occurrence of the oppository

Initially, this type of power unit was used in the military industry, in particular, on domestic tanks. In the future, Ikarusi and motorcycle Dnipro MT went on such engines. At this time, the installation of the oppository to its products is engaged in two firms - Porsche and Subaru.

The first developments appeared in the thirties of the last century, when the engineers of the Volkswagen concern began to improve the V-shaped and row engine. In the sixties, the idea was intercepted by the Japanese company Subaru. In 2008, Subaru releases the first oppositor operating on the diesel. Distinctive features - a four-cylinder engine with a capacity of 2 liters. Power indicator - 150 l / s.

Video Principle of Operation Support Engine Subaru

Despite the high cost of spare parts and service in a hundred, pleasure from riding a car equipped with the "boxer", not compare anything. High resistance, easy handling, the responsiveness of the car for all the actions of the driver speaks for themselves.

They differ from each other not only by type of fuel consumed, but also according to constructive features. For example, a large variety of cylinders. Each option has its strengths and weaknesses. In this case, the pros and cons of the opposite engine will be considered.

In the piston engines of internal combustion (and there are also rotary), the placement of cylinders can be different in relation to each other: under an acute angle, in one row, star-like and so on. In the case of opposite cylinders are located in the same plane and placed one opposite the other at an angle of 180 degrees. Unlike many row engines, the opposite unit often has two, as well as a vertical distribution. There are several types of opposite engines. Among them are most famous:

• Boxer ("Boxer"). It is distinguished by the fact that pistons located in front of each other are moving like boxers in the ring. That is, when one of them is at an extreme top point, the second occupies an extremely lower position. They are equally removed from each other all the time;
• Oros - Opposed Piston Opposed Cylinder. The principle of operation in this case is that the pistons are pairwise in the same cylinder (upper and lower piston). They move towards each other, rotating the crankshaft.
• 5 TDF. This is a two-stroke tank engine of Soviet production, which was used on T-64 and T-72 tanks. An interesting feature of this unit consists in its multi-fiction. The main fuel for him is solard. However, using a special switch on a high-pressure fuel pump, it was possible to start the operating mode on gasoline or a mixture of gasoline with kerosene and diesel fuel, as well as the engine could operate on reactive fuel. True, it was also required to adjust the ignition angle (timing injection).

Many companies were actively engaged in the development of power units. For example, Volkswagen paid attention to this type of aggregates from the mid-30s of the last century. It was not just experiments, but the desire to develop their own opposite motor, reduce the level of vibrations that occur during the operation of the traditional V-shaped or row engine, etc. By the way, Volkswagen engineers applied their development in the legendary Volkswagen Beetle car. And since the 60s, opposite engines have become actively used by the Japanese company Subaru, which was engaged in developments in parallel with the Germans.

Advantages of Opposite DVS

By and large, the operation of the opposite engine does not differ from the principle of action of aggregates of other structures. However, such a layout of cylinders has its own advantages, as well as disadvantages.

• The most noticeable advantage of the underlying power plants is considered almost a complete lack of vibration during operation. Such an effect is achieved due to the location that balable each other. This not only adds comfort, but also significantly increases the service life. From here there is a second "plus";
• An impressive resource of the opposite engine. There is evidence that quite often mileage until the first overhaul was at least 500 thousand kilometers. Of course, driving manner makes its substantial adjustments. And, nevertheless, the frequency period is quite large. However, the allegations of specialists and motorists can be found right and nearby, that 800-900 thousand to the first is nothing more than a beautiful fairy tale;
• Motors considered in this design article provide cars low gravity center. Especially this quality is valued in powerful sports cars. After all, passing the turns at high speeds, it is very important to maintain stability;
• It is also impossible not to mention saving space under the hood. Although many this item will seem controversial, because winning in height, you need to make the hood wider or longer.

Here, perhaps, all the essential advantages of oppositors. Now you need to consider the disadvantages, which, unfortunately, is somewhat more.

The main differences, as well as the advantages and disadvantages of 8-valve engines compared to 16 and valve engines. What a power unit is better to choose.

From book V.N. Stepanov
Tuning automotive engines: SPb., 2000. - 82 p.: Il.

5. Modernization of the exhaust gas release system
In a modern car, several important functions are assigned to the exhaust gas production system (OG):
- mild of noise when producing OG to a level not exceeding established sanitary standards;
- Reducing the number of toxic components in ogs to values \u200b\u200bnot exceeding maximum permissible concentrations.
Along with the execution of these functions, the release system must provide:
- good cleaning and purge of engine cylinders;
- minimal losses of exhaust energy on the way from exhaust valves to the vanes of the holling machine of the turbine;
- the work of the turbine with minimal pulsations of the exhaust flow.
In addition, the release system must have a relatively simple design and be technological in manufacturing. The fulfillment of these requirements allows to obtain an acceptable fuel consumption, reduce the likelihood of a breakwate of the turbine blades, reduce the metal-capacity of the release system and facilitate its maintenance.
The main problem with the desire to equip the car an effective noise jumper system is the difficulty of placing a silencer sufficiently large sizes. Usually this problem is solved by installing a car of several (up to three) sequentially connected silencers with smaller dimensions instead of one large. An important requirement for the graduation path is the presence of minimal resistance to the movement of exhaust and reduction due to this engine power loss.
To reduce the number of toxic components in OG in the exhaust tract of modern cars, a catalytic conventor is installed. The feature of the developed constructions of catalytic neutralizers is that effective neutralization of the contained
In the excess of toxic components, they are carried out only with the value of the air excess coefficient α \u003d 0.994 ± 0.003. In order to determine the amount of oxygen contained in the gas and correction (if necessary) the composition of the fuel and air mixture, which ensures the efficient operation of the catalytic neutralizer, the feedback sensor is set in the exhaust path, the so-called lambda probe, which is also called an oxygen sensor. On some Toyota cars, such a sensor is installed both at the inlet of gases to the catalytic converter and at the outlet of it. This allows the control unit to evaluate the effectiveness of the catalytic neutralizer.
It should be noted that when installing a catalytic neutralizer, the resistance of the exhaust path inevitably increases, which is accompanied by some decrease in the efficient engine power (by 2 to 3 kW). In order for the overall resistance of the exhaust path during the installation of a catalytic neutralizer, the latter is usually placed on the place of the preliminary silencer. Since the maximum engine efficiency occurs when operating on depleted mixtures (≈α 1.05 ... 1,15), then the forced engine operation in the entire range of loads on the mixture of almost stoichiometric composition inevitably leads to a decrease in efficiency (up to 5%).

The exhaust path of the system is striving to perform in such a way that when performing the main functions assigned to it, it would be able to more complete the combustion chambers from residual gases and a more complete filling of the engine cylinders with a fresh charge. Depending on the method of organizing the movement of the flow of exhaustion on the plot from the exhaust valves before entering the turbocharger turbine, exhaust systems are divided into systems
constant pressure
impulse
Pulse with pulse converters
Ejection single-tube.

The graduation systems of permanent pressure due to the existing serious flaws on automotive engines are practically no
Apply.
The greatest spread here was pulsed and impulse systems with pulse converters. Consider these systems more.
Due to the cyclicity of the working process flow in the piston DVS in the graduation path, as in the inlet, there is an oscillatory movement of gases, as a result of which the pressure wave is formed.
Due to the large difference in gas pressure in the cylinder and the outlet path, at the first moment, from the beginning of the opening of the exhaust valve, a significant amount of gases comes out of the cylinder. During this period, called the preliminary release, a pressure wave of pressure propagated at the sound speed. This wave, reflecting from the walls of the exhaust pipeline, under certain circumstances can prevent the further flow of gas from the cylinder caused by a high pressure difference in the initial period of release. The subsequent cleaning of the cylinder from the residual gases is carried out in this case only by piston ejecting. Obviously, under such conditions, the number of gases remaining in the combustion chamber from the previous cycle will be the greatest. This will adversely affect the subsequent filling of the cylinder with a fresh charge and, accordingly, at the power, efficiency and environmental indicators of the engine.
However, the resulting pressure wave can also be used to create conditions for the exhaust valve provisions that contribute to improving the cleaning of the cylinder from residual gases. For this, the exhaust system must be configured so that by the end of the release process during the existing phase overlapping valves for the exhaust valve when the wave passes the vacuum was formed. This will increase the number of residual gases arising from the cylinder and improving the filling of its fresh charge. Setting the exhaust system is carried out by selection of length and secting area of \u200b\u200bexhaust pipelines. At the initial stage of work, the named output parameters can be pre-determined by the calculated method, but then the verification and refinement of the results obtained on the test bench are required. When performing these sufficiently laborious work in order to reduce the number of experiments to obtain the expected result, taking advantage of techniques known from the theory of experimentation planning.
The practice of designing exhaust systems shows that the more cylinders combines one exhaust pipeline, the smaller the resulting pressure amplitude resulting in the pipeline resulting from the imposition of individual waves. Therefore, in order to avoid unwanted overlapping of waves, the exhaust system is performed in the form of several fan (one over the other) pipelines, in each of which is the release of gases by no more than three cylinders. To prevent unwanted overlapping waves, gas flows from cylinders are combined by pipelines so as to provide an alternation of gas releases into each pipeline with the highest possible intervals. In this case, it is necessary to strive to provide the same length of exhaust pipelines (In practice, it is not always possible to implement due to existing dimensional restrictions). The execution of these conditions is possible with a fan-shaped arrangement of exhaust pipelines, when they are located one over the other. Ensuring the same pipeline length allows you to configure a system of output to a specific range of rotational speed. In the impulse exhaust system, the supply of exhaust to the turbine is carried out by individual pipelines from each group of cylinders.

In a pulsed exhaust system with a pulse converter, pipelines, combining output from two or three cylinders, are transferred to the pulse conversion Y-shaped pipe, the two paths of which at a certain distance are combined into one. Compared with the classical pulse exhaust system, the pulse system with the pulse converter loses in dimensions, but allows you to increase the efficiency of the turbocharger and increase the turbine resource.