20.01.2023

Options for supercharging internal combustion engines. ICE boost systems

Supercharging allows you to increase engine power by increasing the density of air at the inlet to the cylinders, which makes it possible to efficiently burn more fuel. Automotive engines use gas turbine charging systems using turbochargers (TCR) or mechanical charging using drive superchargers (PD). In a TCR, air is compressed by a compressor driven by a turbine, and the turbine is rotated by the flow of exhaust gases (see Fig. 7.22). The PN, compressing air, is driven from the engine crankshaft.

The turbocharger of an automotive engine (Fig. 7.26) is a unit consisting of a housing and a rotor (turbine and compressor united by a shaft rotating in plain bearings). The TKR may contain controls for its operation. Typically, the outer diameter of the wheels of centrifugal compressors and radial-axial turbines TKR is 35...90 mm, which ensures a fairly high efficiency. Compressor wheels are made of aluminum alloy, while turbine wheels are made of high-alloy cast iron, as they must withstand high temperatures. Exhaust gas enters the turbine volute casing 6. It contains one or two tapering guide channels in which the exhaust gas velocity increases. Then they are fed to the blades of the turbine wheel 7, causing it to rotate. She's through the shaft 11 rotates the compressor wheel 2. Air through the compressor inlet 1 enters the compressor wheel 2 , where under the influence of centrifugal forces its speed increases sharply, and exits the wheel into the diffuser, where its speed decreases and density increases. Then the air 4 enters the spiral collector of the compressor housing, from where it is sent to the engine.

Rice. 7.26.

1 - compressor housing; 2 - compressor wheel; 3 - air inlet; 4 - outlet of air compressed in the compressor; 5 - oil supply; 6 - turbine housing; 7- turbine wheel; 8- exhaust gas outlet after the turbine; 9- bearing housing; 10- exhaust gas inlet from the engine; 11 - rotor shaft; 12 - oil drain

A drive supercharger of the “Rute” type in the form of two rotors connected by gears in the shape of eights, rotating in different directions, is shown in Fig. 7.27. The rotors alternately approach the upper edges of the housing and capture the air volume V, having atmospheric pressure r 0 . This amount of air, practically without changing the pressure, is pushed into the outlet chamber of the PN, where the charge with increased pressure is located r k. When reporting volume V with an outlet chamber, the charge present enters it under pressure r k. The seal between the rotors, as well as the rotors and the housing walls, is achieved by creating a minimum gap. At high boost pressures at high speeds, leaks become significant, which reduces the pressure rise and efficiency of the supercharger. Therefore, the maximum degree of pressure increase in such a supercharger does not exceed 1.6... 1.7.

Comparison of turbocharger and supercharger drive. TKR is much more widely used for supercharging automotive vehicles than PN, as it provides higher boost pressure and better efficiency, lower noise levels, smaller weight and dimensions.

Rice. 7.27.

The worse efficiency of the PN, in contrast to the TKR driven by exhaust gas energy, is due to the fact that the PN operates from the crankshaft. Being rigidly connected to the crankshaft, the PN provides higher boost pressure at low speeds and, unlike the TKR, does not have a delay in rotor rotation with a sharp increase in engine load (“turbo lag”). This ensures better dynamics of cars with PN, especially in the initial acceleration phase. At low loads, the power to the PN drive does not decrease, which makes the use of PN particularly unprofitable. PN, which is switched off at low loads and high speeds, is usually used on gasoline engines of passenger cars, for which acceleration dynamics are important, and the deterioration in efficiency is not of great importance.

Charge air coolers (CAC). For automotive engines, when air is compressed in a compressor, the temperature increase is usually 40... 180 °C. With intermediate cooling of air in the air cooler, the mass filling of the cylinders increases due to an increase in air density, which provides increased power and improved engine efficiency. The use of ONV also reduces the temperature of engine parts and the temperature of gases in front of the turbine.

Automotive engines use air-to-air and liquid-to-air NVGs. In the first case, the charge air is cooled by blowing the ONV with the flow of oncoming air when the car is moving and the flow created by the fan, and in the second, liquid from the engine cooling system is mainly used.

Liquid-air The ONV is more compact than the air-to-air one. This is due to the fact that heat exchange from hot air to the coolant occurs more intensely than to the cooling air. This heat exchanger ensures a stable charge air temperature regardless of the ambient temperature. It is mainly installed on off-road vehicles, tractors and special vehicles (mining dump trucks, airfield equipment, etc.).

Air-to-air OH B provides deeper cooling due to the fact that the ambient air temperature is lower than the temperature of the cooling system fluid. Therefore, it is used at low levels of supercharging and in the presence of oncoming air flow, which applies to engines of passenger cars and long-haul trucks.

Boost control systems. With an increase in engine speed, the boost pressure TKR increases by 1.3...1.5 times. This is due to the difference in the hydraulic characteristics of piston (engine) and blade (TKR) machines. Ideally, the TCR can be configured for only one engine operating mode (usually this is the point of the external speed characteristic, located between the maximum torque and rated power modes), at which it will provide the specified boost pressure and have highest efficiency. Then, when the rotation speed decreases, the boost pressure will fall relative to the optimal one, and when the rotation speed increases, it will increase. To solve these problems, various methods of boost control are used on engines.

Exhaust gas bypass, bypassing the turbine is the simplest way to coordinate the operation of the engine and TKR (Fig. 7.28). TKR is adjusted to provide high boost pressure at low and medium diesel engine speeds, and at high speeds, further pressure growth is limited by opening bypass valve 5. It is installed at the turbine inlet 8. When it opens, part of the gas is directed, bypassing the turbine, into the exhaust system. The engine management system regulates the valve opening amount to provide the required boost pressure in each operating mode. However, when the bypass valve is open, engine efficiency decreases, since part of the energy spent on air compression in the TKR compressor is lost.

Changing the flow area by rotating blades at the exhaust gas inlet to the turbine wheel. On low frequency rotation rotary blades 3 at the turbine inlet 1 at low speed (Fig. 7.29, A) rotated to the maximum angle, ensuring a minimum flow area at the exhaust gas inlet into the turbine wheel 1. Then the gas speed at the entrance to the wheel will increase, which increases the rotation speed of the TCR rotor

Rice. 7.28.

1 - solenoid valve; 2 - Vacuum pump; 3 - vacuum chamber; 4 - TKR; 5 - OT bypass valve; 6 - OT input from the engine;
7 - exit compressed air; 8 - turbine; 9 - compressor

and, accordingly, boost pressure. At high frequency engine rotation (Fig. 7.29, b) shoulder blades 3 rotated to a minimum angle, providing maximum flow area at the exhaust gas inlet to the turbine wheel 1. Then the gas speed at the turbine wheel inlet is reduced, which prevents the boost pressure from increasing. At the same time, the back pressure at the outlet of the cylinders is reduced, which leads to a decrease in the ejection work and, as a consequence, to an increase in the power and efficiency of the diesel engine. With this control method on small-sized TCRs, the efficiency of the turbine is significantly reduced due to an increase in the resistance created by the blades along the path of the gas flow, and losses associated with leaks through the gaps between the blades and the walls of the turbine housing. There are also difficulties in ensuring the operability of the rotating blades in conditions of soot deposition. Therefore, TCRs with this method of regulation are used on passenger car engines with a displacement of more than two liters.

Changing the flow area for supplying oxygen to the turbine wheel using a sliding sleeve in the nozzle guide apparatus of the turbine. In the TKR (Fig. 7.30), a horizontally moving bushing can close one of the two channels located in the turbine housing and supplying OT to its wheel. This changes the flow area and, accordingly, the speed of gas entry onto the turbine blades. If open

Rice. 7.29. Adjusting the TKR turbine by turning the blades: A- closed position of the blades, minimum flow area and maximum gas entry speed to the turbine wheel; b- open position of the blades, maximum flow area and minimum gas entry speed to the turbine wheel; 1 - turbine wheel;

2 - swivel ring; 3 - rotating blade; 4 - drive lever; 5 - pneumatic regulator; 6 - exhaust gas flow is only one channel 2 (Fig. 7.30, A), the cross-section in the path of the gas flow is minimal, the gas speed is maximum, the boost pressure increases. If both channels are open 2 And 3 (Fig. 7.30, b), then the flow area is maximum and the gas velocity is minimum. In this case, the boost pressure decreases and the back pressure at the outlet of the cylinders decreases. This control method allows the use of TKR with small wheel diameters, which can be used on small displacement engines.

Rice. 7.30. Adjusting the TKR turbine using a sliding sleeve: A- only one channel supplying gases is open in the turbine housing; b- both channels supplying gases are open in the turbine housing; 1 - turbine wheel; 2 - the first channel in the turbine housing; 3 - second channel in the turbine housing; 4 - sliding sleeve; 5 - bypass channel; 6 - sliding sleeve drive

Since the need for supercharging engines became apparent, many variants of supercharging have appeared. The main types of supercharging are the following:

Figure 1 - Types of supercharging

Supercharging systems can be qualified by:

1) the method of supplying air without a blower due to the inertia of the column of air or gas itself;

2) supercharger design;

3) type of supercharger drive;

4) the type of connection between the supercharging unit and the engine.

Inertial charging (without a supercharger, also called “resonant”, “wave”, “acoustic”) is carried out due to pressure fluctuations in the intake pipe of a piston engine. The wave of pressure decrease in the intake pipe at the entrance to the cylinder during the intake stroke moves at the speed of sound to the opposite open end of the pipe, is reflected from it and, in the form of a pressure wave, moves again at the speed of sound to the intake valve. By choosing the length of the pipeline so that the pressure wave approaches the final period of intake, it is possible to ensure that charge is supplied to the cylinder under excess pressure, thereby supercharging the engine (Figure 2).

Figure 2 - Intake tract diagram 1 - air cleaner housing or special resonator

The pipeline length l required for this can be calculated from the time f of the wave passing from the valve to the open end of the pipeline and back.

The energy to “accelerate” the air column in the intake manifold is taken from the additional work of the piston, i.e. due to increased pumping and mechanical losses of the engine.

Inertial charging as an independent charging system is used in passenger car engines. The length of the intake pipe can vary depending on the engine speed, thereby ensuring high filling of the engine cylinders in a wide range of modes.

In combination with gas turbine supercharging, inertial supercharging was used in diesel engines of trucks - Scher's combined supercharging system (Figure 3).

The level of increase in boost pressure during inertial charging is relatively small, so such systems are usually used not to increase the maximum engine power, but to improve the flow of the torque characteristic.

Figure 3 - Combined supercharging system proposed by G. Sher

Another well-known method of supplying air to engine cylinders under increased pressure is the use of exhaust gas pressure waves in the gas-dynamic machine “Comprex” (the name “Comprex” comes from the English words compression and expanding) (Figure 4).

The principle of operation of this system is based on the fact that the pressure wave passing through the pipeline channel is reflected negatively at the free end, i.e. as a rarefaction wave, and at the closed end as a pressure wave, and, conversely, a suction wave at the open end is reflected as a pressure wave, and at the closed end as a suction wave.

The Kompreks system consists of a rotor with axial channels - cells of a trapezoidal cross-section, open at the ends. The rotor, mounted in bearings and surrounded by a casing, is driven through a belt drive from the engine crankshaft. The power required to rotate the rotor is small, because it is spent only to overcome friction in bearings and ventilation losses.

Figure 4 - Diagram of the Kompreks supercharging system 1 - exhaust pipeline; 2 -- inlet pipeline; VND - low pressure air; VVD - high pressure air; HPG - high pressure gas; GND - low pressure gas; R - rotor.

Air and gas channels converge at the end sides of the housing. The axial channels - the rotor cells - alternately coincide with the end walls of the supercharger housing, then with the inlet or outlet pipelines leading either to the engine or to the atmosphere through an air cleaner or muffler.

The supercharging units can be driven:

1) from the crankshaft of the internal combustion engine directly or through a switchable device (“drive superchargers”);
2) from an external energy source, for example, the so-called “e-drive” - from an electric motor (“electrically supported supercharging”);

3) from a turbine that uses the energy of the exhaust gases of the internal combustion engine (turbocompressors).

As drive superchargers, either positive displacement superchargers (piston, rotary-gear (Roots type), rotary-screw, rotary-plate (vane)) or blade (usually centrifugal) are used. The Roots drive supercharger (Figure 5) has two specially shaped rotors, the axes of which are interconnected, connected through gears to the supercharger drive gear, which in turn is connected to a pulley driven by the crankshaft via a belt drive. Rotors rotating in opposite directions literally “suck” air through the inlet, pushing air currents into the so-called. distribution compartment.

Figure 5 - Roots drive supercharger

Another representative of mechanical superchargers is a screw (Linholm supercharger) in its shape and structure very similar to the Roots supercharger (Figure 6), but in reality it differs radically from it.

Figure 6 - Linholm Driven Supercharger

The shapes of the screw supercharger rotors are more pointed, and they themselves resemble self-tapping screws or meat grinder screws. When the rotors rotate, the air entering the supercharger is forced through this conveyor of spirals and is already in a compressed state when it exits the housing. In addition, the air is already compressed inside the device, which means that there will be nowhere to counteract the forces that push the air back in the Roots supercharger.

Drive centrifugal blowers (Figure 7) are made in the shape of a snail and have approximately the same properties as turbines.

Figure 7 - Driven centrifugal blower

Air entering the supercharger housing is picked up by the blades of the impeller and, unwinding, is pressed against the outer walls of the housing by centrifugal forces. At this stage, the air flow reaches enormous speed, but its pressure is still too low. Then, using a diffuser, the opposite effect is achieved: when leaving the supercharger, the air flow speed decreases, and the pressure, on the contrary, increases due to the air “pressing” from behind. The efficiency of centrifugal superchargers is proportional to engine speed. At low speeds the increase in power is practically not felt (although it is greater than that of the same turbine), but at medium and high speeds the power soars.

Gas turbine supercharged engines are often referred to as "turbo-piston engines" or "combination engines".

With a turbocharger (Figure 8), the compressor wheel and turbine wheel sit on the same shaft. The energy of the exhaust gas flow, which is not used in conventional engines, is converted here into torque - the exhaust gases leaving the engine cylinders are supplied to the turbine wheel, where their kinetic energy is converted into mechanical rotational energy (torque). The compressor wheel draws in fresh air through the air filter, compresses it and supplies it to the engine cylinders. The amount of fuel that can be mixed with air can be increased, allowing the engine to develop more power. There are also many other turbocharger designs.

Figure 8 - Turbocharger

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Introduction

2. Types of supercharging

3. Advantages and disadvantages of various types of supercharging

4. Limits for increasing power by supercharging

Used Books

Introduction

One of the pressing issues of the modern global and domestic automobile and tractor engine building is the issue of production in Russia of efficient and reliable turbochargers necessary for the production of engines that meet the environmental requirements of Euro-3 and higher.

In the 90s, it was formed and fully tested by the world's leading manufacturers and developers diesel engines the concept that the turbocharging system is an integral component of a modern, environmentally friendly engine. At the same time, turbocharging, unlike the 70-80s, has ceased to be considered as a means of boosting engines, and almost 100% of modern basic models are designed and developed only with supercharging. Environmental priorities in the current development of diesel engines are decisive, and the requirements for meeting ever-tightening standards lead to a revision of already established approaches to the development of engines, as well as systems and supercharging units. These changes are happening all over the world very dynamically and approaches that have been established for decades are collapsing before our eyes during the transition from Euro-2 to Euro-3 standards, and promising environmental requirements for 10-15 years ahead have sharply intensified research on the creation and optimization of systems and supercharging units.

boost engine aggregate power

1. Supercharging

Supercharging - increasing the amount of fresh charge of the combustible mixture supplied to the engine internal combustion, due to increased inlet pressure. Supercharging is usually used to increase power (by 20-45%) without increasing the weight and dimensions of the engine, as well as to compensate for the loss of power in high altitude conditions. Supercharging with “quality control” can be used to reduce the toxicity and smoke of exhaust gases. Aggregate supercharging is carried out using a compressor, turbocharger or a combination. The most widely used boost is a turbocharger, which uses exhaust gas energy to drive it.

Aggregate supercharging is used on almost all types of transport diesel engines (marine, diesel locomotive, tractor). Boost on carburetor engines limited by the occurrence of detonation. The main disadvantages of aggregate supercharging include:

· increased mechanical and thermal stress of the engine due to increased pressure and temperature of gases;

· reduction in efficiency;

· complication of design.

Dynamic supercharging is becoming increasingly common on transport internal combustion engines, which, with minor changes in the design of pipelines, leads to an increase in the filling coefficient up to a wide range of changes in engine speed. An increase during supercharging allows you to boost the diesel in terms of energy indicators in the case of a simultaneous increase in the cyclic fuel supply or improve the economic indicators while maintaining power indicators (with the same cyclic fuel supply). Dynamic supercharging increases the durability of cylinder-piston parts due to lower thermal conditions when operating on lean mixtures.

2. Types of boost

Since the need for supercharging engines became apparent, many variants of supercharging have appeared. The main types of supercharging are the following:

Figure 1 - Types of supercharging

Supercharging systems can be qualified by:

1) the method of supplying air without a blower due to the inertia of the column of air or gas itself;

2) supercharger design;

3) type of supercharger drive;

4) the type of connection between the supercharging unit and the engine.

Figure 2 - Intake tract diagram 1 - air cleaner housing or special resonator

The pipeline length l required for this can be calculated from the time f of the wave passing from the valve to the open end of the pipeline and back.

The energy to “accelerate” the air column in the intake manifold is taken from the additional work of the piston, i.e. due to increased pumping and mechanical losses of the engine.

In combination with gas turbine supercharging, inertial supercharging was used in diesel engines of trucks - Scher's combined supercharging system (Figure 3).

Figure 3 - Combined supercharging system proposed by G. Sher

The supercharging units can be driven:

1) from the crankshaft of the internal combustion engine directly or through a switchable device (“drive superchargers”);

2) from an external energy source, for example, the so-called “e-drive” - from an electric motor (“electrically supported supercharging”);

3) from a turbine that uses the energy of the exhaust gases of the internal combustion engine (turbocompressors).

Figure 5 - Roots drive supercharger

Figure 6 - Linholm Driven Supercharger

Drive centrifugal blowers (Figure 7) are made in the shape of a snail and have approximately the same properties as turbines.

Figure 7 - Driven centrifugal blower

Gas turbine supercharged engines are often referred to as "turbo-piston engines" or "combination engines".

Figure 8 - Turbocharger

3. Advantages and disadvantages of different types of supercharging

Supercharging by drive positive displacement superchargers ensures a quick response to changes in engine speed conditions.

The disadvantages of this method are large mechanical losses at low loads, relatively large size and weight of the supercharging units, the presence of a mechanical transmission, and often difficult placement on the engine. This also applies to a large extent to centrifugal drive blowers. For the most rational use of drive positive displacement superchargers, a device is needed that ensures their disconnection from the engine at low loads, when there is no need for supercharging. In addition, mechanical superchargers reduce efficiency. engine, because Part of the power of the power unit is consumed to drive them.

The advantages of the Roots positive displacement supercharger include high efficiency at low and medium speeds, durable design and low noise. However, when a certain pressure is reached, air begins to leak back, reducing efficiency. systems.

Screw superchargers of the Lysholm type are effective in almost the entire engine speed range, are compact, silent, but very difficult to manufacture, and therefore expensive.

Although Kompreks wave exchangers provide a quick response to changes in the internal combustion engine mode, they are not capable of developing high pressure supercharging, bulky, require a mechanical drive.

Gas turbine supercharging turned out to be the most successful in a wide range of internal combustion engine sizes from motorcycles to ships with a power of tens of thousands of kilowatts. The advantages of this type of supercharging: more complete use of fuel energy by expanding the useful area of the thermodynamic cycle, automatic adjustment (although not always sufficient for transport engines) to change the operating mode of the internal combustion engine, relatively small size and weight, relative freedom of placement on the engine. The disadvantages of turbocharging - deterioration of engine response - are largely offset by the use of special measures for regulating the boost pressure and reducing the inertia of the rotating parts of turbochargers.

4. Limits of power increase by supercharging

The reduction in heat utilization and mechanical efficiency means that power increases more slowly than boost pressure; in particular, when moving from naturally aspirated power to 2 ata supercharged power, power increases not by half, but by approximately 80%.

This raises the question of what is the appropriate limit for increasing the boost pressure and whether there will come a point when the improvement in filling will not be able to compensate for the power consumption of the supercharger and the deterioration in heat utilization.

The results of an analytical study of this problem confirm such concerns and can be presented graphically (Fig. 77).

The curve shows the change in the average effective pressure depending on the boost pressure, plotted on the abscissa, without taking into account the power consumption for the supercharger drive. The river curve depicts the portion of the average effective pressure expended on the drive; supercharger, also depending on pressure: boost. As can be seen from the graph, the growth of rivers initially lags behind the growth of p e, and with a further increase in boost pressure, the gap between these values quickly decreases. To obtain the average effective pressure corresponding to the effective engine power, it is enough to subtract the ordinates of the r e curve from the ordinates of the r curve. Then we obtain a curve p e. changes in the average effective pressure of the engine depending on the boost pressure. The inflection point a determines the most favorable boost pressure - about 5 ata, at which the average effective pressure and power reach their maximum. Graph Fig. 77 is built based on maintaining the final compression pressure equal to 16.7 am at 4 different boost pressures; this corresponds to a compression ratio of e = 7.5 for a naturally aspirated engine. Increased boost pressures correspond to reduced compression ratios; for a critical boost pressure of 5 atm, the compression ratio is e = 2.3. In addition to the final compression pressure, the graph is based on other specific data. Therefore, 5 atm cannot be considered the most favorable boost pressure for all types of engines. Accurate calculations of the critical boost pressure are hardly possible at all, since it is very difficult to take into account all the operating conditions of the machine, the properties of the fuel, and even more so design features engine. Therefore Fig. 77 is given only to show the existence of a limit to the increase in power of an engine equipped with a driving supercharger. Currently, lower boost pressures are used compared to the maximum; the value obtained on the graph.

It should be noted that even if we do not take into account the loss of power to drive the supercharger, the engine power will still not increase indefinitely, since the more the combustible mixture is compressed in the supercharger, the lower the compression ratio can be used in the engine at a certain detonation resistance of the fuel and, therefore, in the limiting case, all compression of the mixture occurs in the supercharger, and the compression ratio (and expansion ratio) of the engine is equal to unity; in this case, the engine power is zero.

Thus, the improvement in filling during boost compensates for the deterioration in thermal efficiency and the power consumption of the supercharger only up to a certain value of the boost pressure.

Conclusion

So: the goal of supercharging an internal combustion engine is to increase its specific power (per unit of cylinder working volume, weight, dimensions) by increasing the fuel supply and, accordingly, the air mass required for its combustion. Increasing the specific power of an internal combustion engine allows you to maintain its size and weight, cost, as well as the size and weight of the vehicle on which the engine is installed, and increase load capacity and speed.

Supercharging of an internal combustion engine with spark ignition, usually with charge air cooling, increases the specific power of the internal combustion engine and improves the dynamic qualities of the car.

In some countries, cars with supercharged engines and small displacement cylinders are subject to lower taxes. Increasing the excess air coefficient when supercharging diesel engines (especially with cooling of the charge air) makes it possible to increase the effective efficiency. (reduce specific fuel consumption) of the engine, and most importantly - reduce harmful emissions from exhaust gases.

Gas turbine charging reduces exhaust noise.

References

1.B.N. Davydkov V.N. Kaminsky Systems and assemblies for supercharging transport engines - textbook Moscow 2011

2. wikipedia.org/wiki/Supercharging

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Supercharging - “Artificial respiration” for the engine

The “iron” 20th century is coming to an end. Our favorite car witnessed and took part in the events of this century, improved and transformed along with man’s ideas about mass vehicle. And on the eve of the magical number 2000, it makes sense to talk about the most important technical principles and solutions used in the design of a car, remember their history and look into the future. The use of supercharging to supply air to internal combustion engines is one such topic. In addition to the historical aspect, talking about supercharging also has a purely practical meaning - after all, there are more and more cars equipped with such devices on our roads.

Design and principle of operation of a rotary-gear compressor of the Roots type

SUPERCHARGING AS A CURE FOR SHARP

How a piston internal combustion engine works was known back in the last century. The mixture of air and fuel, after being compressed in the cylinder, ignites, expands during combustion, pushing the piston and performing useful work, and then flies out into the exhaust pipe in the form of exhaust gases.

As soon as rattling horseless carriages with piston engines appeared on the roads of the world, the struggle of designers began to increase engine power. The extensive method - burning more fuel in the cylinders, increasing the displacement - led to the appearance of ten- and twelve-liter multi-cylinder monsters. And thoughts about that. how to intensify work processes and remove more from the engine Horse power, led motorists to the idea of supercharging.

The fact is that the amount of fuel that can burn in the engine cylinders is strictly related to the volume of air sucked in by the engine during intake. The mass ratio - approximately 1 kg of fuel to 15 kg of air - had to be maintained very strictly, since an over-enriched mixture led, on the contrary, to a drop in power.

How to overcome this limitation? The idea is obvious: supply more air to the cylinders, pumping its iodine with excess pressure!

First, drive, or, in other words, mechanical superchargers appeared - rotary, screw, piston, spiral types, driven into rotation by a mechanical transmission from the engine crankshaft. Gottlieb Daimler experimented with similar devices - his first experiments with supercharging date back to 1885 - and, a little later, Rudolf Diesel. But it turned out to be a tough nut to crack - and when implementing a rather simple idea, the designers had to face a lot of technical difficulties.

As often happens, the military was the first to use mechanical supercharging - on aircraft engines to compensate for the deterioration of cylinder filling during high-altitude flights. It was only after the First World War that the experience gained made it possible to equip gasoline engines with drive superchargers, first in racing cars, and then in sports and touring cars. Overseas in the 1920s, compressors were produced by Duesenberg. Auburn and Cord, and among the “Europeans” Bentley was in the lead. Lancia, Alfa Romeo, Fiat, Bugaiti and, of course, Daimler-Benz - sports “compressor” SS and SSK with switchable Roots-type rotary supercharger drive have become the dream of any collector. The seven-liter six-cylinder engine of the SSKL racing roadster of the late 20s with mechanical supercharging developed 300 hp. e.! By the way, these cars were designed by Ferdinand Porsche himself, who was technical director in Stuttgart at that time.

The idea of supercharging turned out to be very fruitful. We increase the air pressure by 30% - we get an adequate increase in engine power. We add up to 50% - we remove even more “horses”. And so on until... the engine falls apart - after all, compression now begins not at atmospheric pressure inside the cylinders, but at excess pressure, and the actual compression when the supercharger is running will be higher. At the same time, not only power increases, but also the thermal and mechanical load on engine parts. And, of course, the increase in boost pressure of gasoline engines is restrained by the detonation resistance of the fuel - if the compression is too high, then the combustion process of the mixture will take on the character of an explosion, with all the ensuing detonation “charms”...

The Roots compressor was mounted in front of the 7-liter “six”, and its housing and manifold were equipped with fins for better cooling

The most common gas exchange scheme these days is with turbocharging and wastegate

Mechanical superchargers have two main advantages. Firstly, it is an almost inertia-free reaction to changes in fuel supply and, secondly, a wide range of engine speeds at which such supercharging is effective. Modern drive compressors are famous for the fact that they work from the very bottom, almost from idle speed, increasing torque where its lack is felt most strongly.

But there are also disadvantages. The comparative “high speed” of drive superchargers (up to 20,000 rpm or more) gives rise to technological difficulties in manufacturing, and the rather large dimensions lead to layout problems: there is nowhere for an apple to fall inside modern engine compartments...

And the main disadvantage of such a scheme is that the energy for the operation of the supercharger is taken from the crankshaft, taking away a small but still noticeable, about 10%, share of the torque. Of course, this is compensated by an increase in boost pressure, but still...

ENERGY FROM NOWHERE

Drive compressors of those years were very complex and unreliable. For example, the supercharger of the legendary MercedesBenz SSK.L had to be connected only at high speeds (about 4000 rpm) and high speeds and only for 20 seconds - in order to break away from the opponent or complete overtaking. At the same time, the compressor emitted a heartbreaking screech: its rotors rotated four times faster than the crankshaft, quickly reducing the engine's life and its own. It was not for nothing that Sir Bentley, whose cars were then the main rivals of Porsche’s creations in racing, did not like superchargers, but against his will they were installed on 4.5-liter engines at the request of racers.

This is the nature of the change in torque and specific fuel consumption of the VAZ-2106 engine with a NAMI turbocharger (1 - standard engine, 2 -power option for tuning the turbocharger, 3 - economical option)

Gas turbine or simply turbocharging does not have this drawback. It is powered by engine exhaust gases, which usually simply fly out into the chimney, carrying with them and dissipating in the atmosphere a little less than half of the total fuel combustion energy.

Unlike drive superchargers, the designs of which vary greatly depending on the type, all turbochargers operate on the same principle and have a similar design. Instead of a receiving pipe, a turbine housing is attached to the output flange of the engine exhaust manifold - a cast “snail”, inside of which a turbine wheel rotates under the influence of the exhaust gas flow. The torque is transmitted to the coaxial compressor wheel, which rotates in its “snail”, sucking in the air entering through the filter and supplying it under pressure to the carburetor or to the intake manifold. This improves cylinder filling and increases engine power.

As simple as it is ingenious, the idea of turbocharging turned out to be extremely difficult to implement. The temperature of the exhaust gases that the turbine must withstand is 900-950 °C, and the operating speed of the turbocharger is tens and even hundreds of thousands of revolutions per minute! Gas turbine supercharging was studied at the beginning of the century - the Swiss engineer Alfred Büchi carried out his first experiments before the First World War. Like drive compressors, turbocharging first appeared on aircraft engines. For example, the Frenchman Professor Rato in 1919 equipped the engine of a Breguet airplane with a turbocharger and an intercooler (!) - and the “supercharged” airplane immediately broke the altitude record, breaking through the ten-kilometer mark

But the main obstacle to the widespread use of turbocharging until the 60s remained the lack of inexpensive technology for high-precision casting from heat-resistant materials.

The first production car with a gasoline engine equipped with a turbocharger was the infamous rear-engine Chevrolet Corvair - the one that is “dangerous at any speed.” An air-cooled opposed six, which in its naturally aspirated version produced 95 hp from its 2300 cc. That is, in the turbo version on the 1961 Corvair Monza spider it developed 140, and later 180 hp. e.!

But oversteer, which was initially characteristic of this extraordinary “American,” ruined the Corvair - after lawyer Ralph Neider’s acclaimed book “Unsafe at any speed,” demand for the car fell sharply, and even subsequent modernizations could not rehabilitate the Corvair in the eyes of conservative Yankees. A shadow of disrepute has also fallen on the innocent turbocharger...

Turbocharger rotor: at the top - brand new, at the bottom - ruined by poor-quality lubrication

Thrust and axial bearings made of lead bronze, the life of which came to an untimely end due to the carelessness of the owners...

Torque curves of three Volkswagen engines: naturally aspirated 1.8-liter, 1.5-liter 16-valve and 1.3-liter turbocharged (turbo) and mechanical supercharger (kompr.)

Differences in response latency to feed increasesfuel (engine speed - 2300 rpm, 4th gear). The turbocharger “thinks” a second longer than the drive supercharger!

The next appearance of a turbocharger on passenger cars occurred only a decade later in Mother Europe - 1,600 high-spirited BMW 2002 turbos produced by the company from 1973 to 1974 did not make much of a difference, but showed the way to others. The era of mass-produced turbo engines was ushered in by Porsche cars (911 turbo, 1974) and SAAB 99 turbo, 1978). Well, after 980 goals, technological barriers collapsed, and turbo versions appeared in model range from almost all leading manufacturers.

Turbocharging was established on diesel engines earlier, but not on passenger cars, but on heavy vehicles - ships, tanks, trucks... The fact is that adapting a turbo unit to a diesel engine is easier than to a gasoline engine: in diesel engines, the energy of the exhaust gases at low speeds is greater . And it’s easier for the turbine to work - the temperature of the diesel exhaust gases does not rise above 650-700 "C. The initiator of the mass use of turbodiesels on civilian trucks was DAF in 1958. And on passenger cars Turbodiesels began to appear only in the early 80s, when the struggle to reduce fuel consumption and air pollution was already in full swing between leading automakers, fueled by fuel crises and protests by “greens.”

WHAT IS HIDDEN IN “SNAILS”

As mentioned, although the idea is simple, a turbocharger is very complex to design and manufacture. And especially for a passenger car.

Because compactness requirements increase the cost of the casting process. That is why only specialized companies undertake the production of turbochargers - Garrett (USA), KK (Germany), Holset (England), IHI (Japan) - and it is cheaper for automobile companies to buy units from them. The exceptions are Mitsubishi and Nissan, which have mastered the production of turbochargers on their own and even sell them “outside” (for example, Mitsubishi equipped its SAAB engines with units).

The turbocharger housing and turbine “scroll” are cast from special malleable cast iron, which has high heat resistance, but, alas, can crack if there is a sharp temperature change - for example, when water gets in. Inside the housing, in sliding bearings made of lead bronze, an axis rotates, on one side of which there is a welded turbine wheel made of a heat-resistant alloy, and the compressor impeller is attached to the other end - it, like its “snail”, is not so loaded with heat, which makes it possible to cast these parts made of aluminum alloys.

The shaft is kept from axial movements by a thrust bearing made in the form of a wide washer with a slot. All bearings are lubricated motor oil, which comes under pressure from the engine lubrication system - the supply and drain oil lines are connected to the turbocharger housing. There are also water-cooled units, but rarely

The shaft with impellers is carefully balanced after assembly - the slightest imbalance will cause vibration of the rotor and will inevitably damage the turbocharger. After all, the operating speed of the shaft can exceed 200,000 rpm!

At first, turbochargers were characterized by very large delays in “response”: you have already pressed the gas pedal, but the engine is still waiting and waiting... This is the so-called turbo lag - turbolag. And also - they refused to work at low and medium speeds, when the exhaust gas pressure is low (“turbojam” - a failure of the engine’s torque characteristics up to 2500-3500 rpm). For example, the turbocharger on a Chevrolet Corvair began to work only after the boxer engine spun up to 5000 rpm - almost to maximum speed. This was dealt with by reducing the mass and moment of inertia of the rotor. At the same time, the boost pressure increased in the low-speed zone, but as they increased, excess was formed, which must be “bleeded off” so that the engine does not experience a “hypertensive crisis.”

Curves illustrating the “thermal shock” of turbocharger bearings when the engine stops. Exhaust gas temperature -950 °C

Therefore, all turbochargers of gasoline, and later diesel, engines began to be equipped with a boost pressure regulator. As a rule, it operates at a certain threshold value of the charge air pressure in the compressor - the air presses on the membrane, overcoming the resistance of a calibrated spring, and, through mechanical traction, slightly opens the bypass valve in the turbine housing, diverting part of the exhaust gases past the turbine wheel. Previously, other control schemes were encountered - for example, based on the pressure of the exhaust gases themselves. And now on modern engines this is controlled by electronics.

Of course, when bypassing, the efficiency of the turbocharger decreases, but so far few have been able to avoid this by regulating the performance of the turbocharger in another way - for example, by changing the angle of influence of the exhaust gas flow on the turbine blades depending on the rotor speed. Turbocompressors with variable nozzle geometry, in which the angle of inclination of the nozzle blades is adjusted by a pneumomechanical drive, are produced only by Garrett and a few other leading companies.

DISEASES AND CARE

The turbocharging unit is designed as maintenance-free, that is, it does not require any specific maintenance or adjustment, and after the service life has expired, which is usually equal to or exceeds the service life of the engine itself, it must be replaced. However, it is possible to formulate a few simple recommendations that will arm the owner of a car with a turbo engine with knowledge of situations in which it is undesirable to get into.

Rotor bearings are the main component of a turbocharger, on which the performance of the entire unit mainly depends. And they mainly need abundant and high-quality lubrication. Therefore, the simplest advice - regularly, according to the instructions, change the filter and oil in the engine and monitor its level - should become an iron commandment for the owner of a turbo engine. The oil can be either synthetic or mineral based - this is not so significant. In general, when choosing the type of lubricant, it is better to follow the factory instructions and under no circumstances mix oils, even of the same type, but of different grades. The main thing is that the API oil quality class must be at least SG/CD. It is this index that indicates the quality of the additive package, which must be designed to work in the most intense zone of the turbocharger bearing assembly, where both friction conditions and oil temperature can reach extreme values.

But the oil not only lubricates the bearings, but also cools the assembly, maintaining the temperature at an acceptable level. If lubrication conditions worsen - for example, the oil has not been changed for a long time, and deposits have decreased throughput lines, then the oil begins to stagnate in the bearing assembly, which increases the thermal stress, and this causes coking and even greater clogging of the line. As a result, the bearings sooner or later remain dry, and this is followed by their scuffing and breakdown of the entire unit.

Another turbocharger unit, the serviceability of which also affects the “health” of the engine, is the gas-oil seals of the rotor axis, usually made in the form of elastic steel rings such as piston ones. They isolate the lubrication system from the intake and exhaust cavities of the turbocharger, and when they wear out - and this usually follows radial runout of the rotor or play of its axis - the oil begins to be squeezed into the compressor cavity, enters the cylinders and burns with a characteristic bluish smoke. The owner is sinning on the “piston”, but the problem is in the turbocharger!

At first, this effect manifests itself when starting a cooled engine - a puff of blue smoke from the exhaust pipe may indicate the beginning of wear of the bearing unit and seals. But wear also manifests itself in the same way, for example, valve stem seals or the valve guides of the engine itself...

By the way, a similar picture can be caused by... clogged air filter! When it exhibits significant intake resistance, in the manifold, especially at idle speed in gasoline engines, increased vacuum occurs, for which the seals are simply not designed.

Affects the performance of the turbocharger and the condition of the engine itself. For example, when worn piston rings the resulting excess pressure of crankcase gases can prevent the oil from draining from the turbo unit - with corresponding consequences. The same effect is observed when crankcase ventilation deteriorates. And a violation of fuel adjustments - a malfunction of the injection system - can lead to the fact that carbon deposits formed during incomplete combustion of fuel will be deposited on the turbine wheel and bypass valve, causing an imbalance of the rotor and interfering with normal operation pressure regulator.

The serviceability of the turbocharger can be judged both by the dynamics of acceleration and by the charge air pressure. As a rule, all cars with gasoline turbo engines are equipped with dial gauges for boost pressure in the instrument cluster. On Idling the instrument needle shows a vacuum in the intake manifold and reacts to “gas leaks” without load with a slight deviation. But when accelerating, say, in third gear from low speeds, you can clearly see how after opening the throttle flow damper "to the floor" yes The boost pressure (and vehicle acceleration) increases slowly at first, and then in the region of 2000-2500 rpm at modern cars- the arrow sharply goes to the right all the way, the muffled whistling sound of a turbine is heard from under the hood, and the car powerfully rushes forward. Some people like this “turbo buzz”, others find it difficult to predict the car’s reaction to changes in fuel supply - it’s a matter of taste. In the end, some companies (Opel, Citroen, SAAB) offer the most “charged” versions either with “explosive” four-cylinder turbo engines, or with “smooth” and more torquey “sixes” at low speeds...

And finally, some driving recommendations. There are no special requirements for warming up turbo engines - a working lubrication system with a normal filter ensures an instant supply of oil to the supercharger bearings. But when you turn off the engine after hard driving, when the engine has been running for a long time under heavy load high speeds, it is better to let it idle for a minute or two. The fact is that stopping oil circulation after intense work causes “thermal shock” - cooling abruptly stops, and the oil in the bearing housing of the turbo unit heats up to three hundred degrees, coking and forming deposits. And in extreme cases - for example, when stopping after a long slip in the mud, when the turbine “snail” is red-hot, the rotor bearings can jam and even melt...

Garrett VNT25 turbocharger with variable nozzle geometry. Since 1991 it has been installed on diesel car Fiat Croma 2.5 TD

In the NAMI turbocharging laboratory, the adaptation of the turbocharger to the “eight” engine is in full swing. The results are just around the corner...

And before overcoming water obstacles, you need to assess the depth of the ford - the cast-iron turbine housing may crack after “water procedures,” especially on gasoline engines, where it is hotter.

PROS AND CONS OF TURBOCHARGING

Let's start with the cons. A turbocharged engine (and supercharged engine in general) is more complex and expensive both to manufacture and to operate - it requires the most best oil, and you need to change the lubricant more often. It is still not possible to avoid “turbo lag” and delays inherent in gas turbine supercharging. These phenomena can be reduced by the use of two turbochargers connected in series, “tuned” in different ways - this scheme is called biturbo and was widely used in motorsports, and in passenger cars it was first installed on the car of the same name by Maserati. But, alas, a “biturbo” engine is even more expensive.

And, of course, the engine itself experiences heavy loads, and the increase in thermal stress and mechanical loads is proportional to the increase in boost pressure (and therefore power). Therefore, on serial turbo engines the pressure is limited to 0.3-0.8 kg/sq.cm, making do with a very modest boost by 30-50% by sporting standards. But this allows, by strengthening the engine parts (piston, connecting rod, etc.), to maintain the engine resource at the “atmospheric” level.

The intercooler, which is an aluminum radiator-heat exchanger included in the intake tract between the compressor and the manifold, allows you to painlessly increase the pressure by another 10-20 percent. It quite effectively reduces the temperature of the compressed air and the heat flow through the engine, allowing more fuel to be burned in the cylinders without the risk of detonation. But again, not cheap...

Well, the advantages of turbocharging - increased liter power, engine efficiency, improved acceleration dynamics, elasticity and (compared to an “aspirated” engine of the same power) fuel efficiency - are obvious. In addition, the use of supercharging makes it possible to reduce the amount of toxic emissions - CO and CH, and with intermediate cooling of the air, also nitrogen oxides NOx. And recently, new arguments in favor of supercharging have appeared.

XXI CENTURY - WITH OR WITHOUT SUPERCHARGE?

Since the second half of the 80s, the world's leading automobile manufacturers have been investing millions of dollars in research and development to reduce toxicity and reduce fuel consumption, while simultaneously striving to increase liter power. Gradually introducing solutions such as replacing the carburetor with injection, electronic optimization of operating modes, catalytic neutralization, resonant intake and exhaust, adjustable phases, engineers brought the Otto four-stroke engine to almost perfection. All that remains is to use direct injection on gasoline engines, which is what Mitsubishi and Subaru are now doing among the first. What's next?

It seems that at the beginning of the next century the internal combustion engine will still prevail over other alternative power plants. And in order to meet very stringent toxicity standards, known as Euro 3, designers will have to look for new ways to radically modernize piston engines. And most likely, you won’t be able to forget about supercharging.

One of the ways is to create engines that implement cycles with internal cooling (Miller-Atkinson cycles) with the mandatory use of supercharging, either mechanical or combined.

The second way is to switch to... a two-stroke cycle! Theoretically, it can provide better performance, and therefore the heirs of the funny DKW engines are now spinning on the test benches of Ford and Jaguar. Again, armed with supercharging...

The third direction is the use, along with direct injection, of various supercharging schemes to ensure operation gasoline engines on ultra-lean mixtures. Some offer a combination of a switchable drive supercharger for low speeds and turbocharging for mid and high speeds. Well, some continue to work on another type of supercharging unit - a wave pressure exchanger

Sotrgekh, combining the advantages of all traditional types of superchargers, but extremely difficult to develop and manufacture.

Improvements are also being made to good old turbocharging. Thanks to the use of ceramics and special plastics, the mass and moment of inertia of the rotor are reduced, gas-lubricated bearings and new seals will reduce friction losses...

So we are on the verge of new significant changes in engine design - and Autoreview, of course. will pay attention to any interesting innovations. It is a pity that Russia is a hopeless outsider in this race.

Although our domestic developments, perhaps, could compete with the “offal” of concept cars from famous companies. It’s nice that the NAMI turbocharging laboratory continues its scientific research and practical development with sheer enthusiasm. For example, a turbocharging unit for “classic” VAZ engines has been made and tested, and a turbocharger for “eighth” engines is being prepared. We will tell you more about them later. By the way, they will try to help those poor souls who suffer from faulty turbocharging of foreign cars...

A. AZBEL L. GOLOVANOV

Since the advent of the internal combustion engine, designers have been faced with the task of increasing its power. And this is only possible in one way - by increasing the amount of fuel burned.

Ways to increase engine power

To solve this problem, two methods were used, one of which was to increase the volume of the combustion chambers. But in conditions of constantly tightening environmental requirements for power units In cars, this method of increasing power is now practically not used, although it was previously a priority.

The second method of increasing power comes down to a forced increase in the amount of combustible mixture. As a result, even small-volume power plants can significantly improve performance.

If there are no problems with increasing the amount of fuel supplied to the cylinders (the fuel supply system is easily adjusted to the required conditions), then with air it is not so simple. The power plant pumps it in independently due to the vacuum in the cylinders and it is impossible to influence the volume of injection. And since for maximum efficient combustion in the cylinders, a fuel-air mixture with a certain ratio must be created, increasing the amount of fuel alone does not give any increase in power, but on the contrary, consumption increases and power decreases.

The way out of the situation is to force air into the cylinders, the so-called engine supercharging. Note that the first devices that pump air into combustion chambers appeared almost from the moment the machine itself appeared, but for a long time they were not used on vehicles. But superchargers were widely used in aviation and on ships.

Types by method of creating pressure

Engine supercharging is a theoretically simple idea. Its essence boils down to the fact that forced injection allows you to significantly increase the amount of air in the cylinders compared to the volume that the engine itself sucks in, and accordingly, more fuel can be supplied. As a result, it is possible to increase the power of the power plant without changing the volume of the combustion chambers

But this is all simple in theory, but in practice many difficulties arise. The main problem comes down to determining which supercharging design is the most efficient and reliable.

In general, three types of superchargers have been developed, differing in the method of pumping air:

Roots
Lysholm (mechanical supercharger)
Centrifugal (turbine)

Each of them has its own design features, advantages and disadvantages.

Roots

The Roots style supercharger was originally introduced as a conventional gear pump (something similar to an oil pump), but over time the design of this supercharger has changed greatly. The modern Roots supercharger replaces the gears with two counter-rotating rotors mounted in a housing. Instead of teeth, the rotors have blade cams that engage the rotors with each other.

The main feature of the Roots supercharging is the way it is charged. Air pressure is created not in the housing, but at the exit from it. Essentially, the rotor blades simply capture air and push it into an outlet passage leading to the intake manifold.

Design and operation of the Roots supercharger

But such a supercharger has several significant drawbacks - the pressure it creates is limited, and air pulsation is still present. But if the designers were able to overcome the second drawback (by giving the rotors and output channels a special shape), then the problem of limiting the created pressure is more serious - either it is necessary to increase the speed of rotation of the rotors, which negatively affects the service life of the supercharger, or to create several stages of discharge, which is why the device becomes very complex in design.

Lysholm

The Lysholm-type supercharging engine is structurally similar to the Roots, but instead of rotors it uses spiral-shaped augers (like a meat grinder). In this design, pressure is created in the supercharger itself, and not at the outlet. The idea is simple - air is captured by the augers, compressed during transportation by the augers from the inlet to the outlet, and then pushed out. Due to the spiral shape, the air supply process is continuous, so there is no pulsation. This supercharger creates more pressure than the Roots design, operates silently and in all engine modes.

Lysholm type supercharger, another name is screw.

The main disadvantage of this supercharging is the high manufacturing cost.

Centrifugal type

Centrifugal blowers are the most common type of device today. It is structurally simpler than the first two types, since it has one working element - a compression wheel (ordinary impeller). Installed in the housing, this impeller captures air from the inlet channel and pushes it out into the outlet channel.

Centrifugal blower with gas turbine drive

The peculiarity of the operation of this supercharger is that in order to create the required pressure it is necessary for the turbine wheel to rotate at a very high speed. And this in turn affects the resource.

Drive types, their advantages and disadvantages

The second problem is the supercharger drive, and it can be:

Mechanical
Gas turbine
Electric

In a mechanical drive, the supercharger is driven from the crankshaft through a belt, or less often a chain, transmission. This type of drive is good because the boost starts working immediately after the power plant starts.

But it has a significant drawback - this type of drive “takes away” part of the motor power. The result is a vicious circle - the supercharger increases power, but immediately takes it away. A mechanical drive can be used with all types of supercharging.

The gas turbine drive is currently the most optimal. In it, the supercharger is driven by the energy of burnt gases. This type of drive is used only with centrifugal charging. A supercharger with this type of drive is called turbocharging.

To harness the energy of exhaust gases, the designers essentially simply took two centrifugal superchargers and connected their impellers to a single axis. Next, one supercharger was connected to the exhaust manifold. Exhaust gases leaving the cylinders move at high speed, enter the supercharger and spin the impeller (it is called a turbine wheel). And since it is connected to the impeller (compressor wheel) of the second supercharger, it begins to perform the required task - pumping air.

Turbocharging is good because it does not affect engine power. But it has a drawback, and a significant one - at low engine speeds, due to the small amount of exhaust gases, it is not able to effectively pump air; it is effective only at high speeds. In addition, in turbocharging there is such an effect as “turbo lag”.

The essence of this effect comes down to the fact that turbocharging does not provide an instant response to the driver’s actions. If there is a sudden change in the operating mode of the engine, for example, during acceleration, at the first stage the energy of the exhaust gases is not enough for the boost to pump in the required amount of air; it takes time for processes to take place in the cylinders and the amount of exhaust gases to increase. As a result, when you sharply press the pedal, the car “stumbles” and does not accelerate, but as soon as the boost picks up speed, the car begins to actively accelerate – it “shoots”.

There is another not very pleasant effect - “turbo lag”. Its essence is approximately the same as that of “turbo lag”, but its nature is somewhat different. It boils down to the fact that supercharging has a delayed reaction to the driver’s actions. This is due to the fact that the supercharger takes time to capture, pump air and deliver it to the cylinders.

Indicative graphs of the effects of “turbojam” and “turbolag” depending on power

“Turbojam” appears only in superchargers powered by exhaust gas energy, but in devices with mechanical drives it does not exist, since the charging performance is proportional to engine speed. But “turbo lag” is present in all types of superchargers.

IN modern cars electric supercharging drives are beginning to be introduced, but they are just in their infancy. For now they are used as an additional mechanism to eliminate “turbo lag” in the operation of turbocharging. It is possible that soon a development will appear that will replace the superchargers we are used to.

Electric supercharger from Valeo

For them to work effectively, they need more high voltage, so a second network with its own 48-volt battery is used. The Audi concern generally plans to transfer all equipment to increased voltage– 48 volts, as the number of electronic systems increases and, accordingly, the load on the vehicle network increases. Perhaps in the future all automakers will switch to higher voltage on-board networks.