RU2191910C2 - Internal combustion engine - Google Patents

Abstract

FIELD: mechanical engineering; engines. SUBSTANCE: invention relates to control systems of internal combustion engines. According to invention, proposed engine has valve actuating gear providing possibility of closing of intake valves during second half of piston travel to top dead center after intake stroke and device to control engine power output which is furnished with charge pressure- connected with intake manifold, cooler connected in cut of intake manifold after charger, and device to adjust charger speed with ratio changer connected with engine power controls. EFFECT: increased efficiency of engine. 3 cl, 2 dwg

Description

 The invention relates to piston internal combustion engines with continued expansion in the main cylinders and power control by changing the amount of mixture entering the cylinders, and can be used where the engines operate mainly at partial loads, for example, as automobile engines.

 In gasoline engines, the power is usually regulated by throttling the charge by the throttle and at 20 ÷ 30% of the power developed by the engine at these revolutions, the pressure in the intake pipe will reach 0.05 ÷ 0.07 MPa and 10 ÷ 20% of the generated energy will be spent to create this vacuum engine of energy.

 In addition, at light loads, the pressure and temperature of the mixture at the end of compression are small, and the rate of combustion of the mixture decreases and becomes insufficient for the combustion of fuel near TDC, and the mixture burns during a stroke and even exhaust. To ensure the necessary combustion rate, it is necessary to re-enrich the mixture, the fuel does not burn completely and its consumption increases.

 In conventional engines, the compression ratio is equal to the expansion ratio. The higher the degree of expansion, the more work the gases produce during the stroke. In gasoline engines, the compression ratio is limited due to the possibility of detonation, which depends mainly on the temperature of the mixture at the end of compression. The compression ratio and, accordingly, the expansion ratio of a gasoline engine is 1.5–3 times lower than that of a diesel engine, and therefore the fuel energy is used less fully and its efficiency is less than that of a diesel engine. In addition, the efficiency of a gasoline engine decreases sharply at low loads due to losses associated with throttling and the need to re-enrich the mixture.

 The gas pressure at the beginning of the release from the cylinder is several times higher than atmospheric pressure, that is, gases have significant energy and this energy is not used in conventional engines.

 Known engine schemes in which ways were sought to increase the degree of expansion and eliminate losses from throttling. In modern engine building, it is customary to continue to expand beyond the main cylinders, for example, in gas turbines.

 Known piston engine with a turbocharger of high pressure with an air cooler included after the supercharger, for example a turbocharger of a racing car "Williams-Honda 11" (L. Shugurov. Formula number one. // Science and life. - 1989. - 11. - P. 140 . - paragraph 3).

 The supercharger provides pressurization up to 0.5 MPa and, by adjusting the frequency of rotation of the supercharger shaft, it is possible to change the supercharging pressure and, accordingly, engine power in a wide range without throttling the mixture at the cylinder inlet. Two-stage compression and cooling of the injected air in the cooler will increase the overall degree of compression, but increasing the charge density will increase the propensity of the engine to detonate.

 In an engine, the compression ratio in the cylinder is equal to the expansion ratio in the cylinder. To eliminate detonation, the compression ratio in the engine cylinders is reduced, which means that the expansion ratio in the cylinder will decrease and the gases will have a high pressure at the beginning of the release. Directly in cylinders, fuel energy will be used worse.

 Continued expansion takes place in a gas turbine, i.e. engine exhaust is used to drive a gas turbine. But gas turbines of low power have an efficiency of 50-60%.

 In addition, the pressure at the inlet to the gas turbine is usually approximately equal to the pressure of the compressed air at the pressure head of the supercharger, which is several times less than the gas pressure in the cylinder at the beginning of the outlet. That is, most of the pressure is lost during exhaust and is not used in the turbine. Therefore, the overall efficiency of an engine with a turbocharger of increased pressure will be lower than that of a naturally aspirated engine.

 A known internal combustion engine containing cylinders, closed by covers and equipped with inlet and outlet valves, pistons connected by connecting rods to the crankshaft, a fuel supply device, a valve control mechanism that allows the intake valves to be closed in the second half of the piston stroke to top dead center after the intake stroke, engine power control device (J. Matskerle. Modern economical car. - M.: Mechanical Engineering, 1987. - 110 p.).

 This engine is the closest to the proposed and works as follows. After the intake stroke, the piston goes to the TDC, pushing the mixture from the cylinder back into the intake manifold, in the middle of the piston stroke to the TDC, the inlet valve closes, and the mixture begins to compress. The remaining processes are as in a conventional four-stroke engine. The compression ratio in the cylinder is the same as in conventional gasoline engines, and the expansion ratio in the cylinder is 2 times greater.

 Power control in it is performed by throttling the mixture at the inlet to the cylinders.

 The efficiency of this engine at maximum load will be 1.1 times higher than the efficiency of a conventional engine with the same compression ratio, but its efficiency will sharply decrease at partial loads. Moreover, the reduction in efficiency will be two times faster than in a conventional engine, because the mechanical loss of the engine is mainly determined by the size of the engine and the speed of rotation of the engine shaft and little depends on the gas pressure in the cylinders. Therefore, per unit mass of gas, the losses will be almost two times greater, since the engine runs at half the mass of gas compared to a conventional engine of the same size.

 In addition, as in a conventional engine, the efficiency will decrease at partial loads due to the energy consumption for creating a vacuum in the cylinders at the inlet.

 The efficiency is also reduced due to over-enrichment of the mixture at partial loads to ensure a sufficient rate of combustion of the mixture at low pressure at the end of compression.

 Therefore, at loads of about 50 ÷ 60%, the efficiency of the engine of this engine will be comparable to the efficiency of a conventional engine at the same loads, and at a lower load it will be lower than the efficiency of a conventional engine.

 In addition, an engine with continued expansion will have twice the mass and volume of cylinders than a conventional gasoline engine of the same power.

 The technical result of the invention is to increase engine efficiency and maintain efficiency at partial loads when using low-octane fuel due to pressurization by boosting the pressure with cooling of compressed air, increasing the overall compression ratio in the engine by two to three times while reducing the compression ratio in the cylinders , increase in one and a half to two times the degree of expansion in the cylinders, the implementation of economical power regulation by changing the discharge pressure.

 To achieve this technical result, the internal combustion engine comprises cylinders closed by caps, equipped with inlet valves and exhaust valves, pistons reciprocating between the lower and upper dead points located in the cylinders and connected by a movement conversion mechanism with a shaft, a fuel supply device, the inlet pipe connected to the chambers of the intake valves, a valve control mechanism for closing the intake valves in the second half of the stroke the piston towards the upper dead point after the intake stroke, the engine power control device.

 Distinctive features of the proposed engine from the one closest to it is that the engine power control device comprises a supercharger connected in pressure to the inlet pipe, a cooler included in the inlet pipe cut after the supercharger, a supercharger speed control device, for example a variator, mechanically connecting the engine shaft with a supercharger shaft, a mechanism for changing the gear ratio of a supercharger speed control device connected to control units ION engine power.

 Distinctive features is that the control mechanism ensures that the intake valves are closed when the piston passes 70–80% of the stroke when moving toward the TDC after the intake stroke, and the engine has a compression ratio in the cylinders of 4-8 and an expansion ratio in the cylinders of 12 ÷ 35 during the piston stroke from TDC to BDC.

 Distinctive features is that the supercharger has a maximum compression ratio of 2 ÷ 6, and the engine has a maximum total compression ratio of 10 ÷ 25.

 In the engine cylinder, the mixture is compressed, filling 20–30% of the cylinder volume, and the entire cylinder volume is used to expand the gases, so when the compression ratio in the cylinder is 4–8, the expansion ratio in the engine cylinder will be 12–35.

 Regulation of engine power is carried out by changing the pressure at the head of the supercharger by changing the speed of rotation of its shaft by a variator. Regulation of engine power by throttling the air at the inlet of the supercharger will be carried out only at idle. In the main operating modes of the throttle motor, there will be no losses associated with throttling.

 The supercharger increases engine power to about the level that a conventional engine would have the same cylinder volume without boost. Such a sharp decrease in mechanical efficiency while reducing the load, as in the prototype, will not be, since high-pressure boosting will increase the mass of gas running in the engine by 2–6 times and reduce mechanical losses by 2–6 times per unit mass of gas.

 In the supercharger and engine cylinders, two-stage compression is performed with intermediate cooling in the cooler. Two-stage compression with intermediate cooling will increase the total compression ratio in the engine by 2–3 times in comparison with the prototype, and a further increase in the total compression ratio is limited by the mechanical strength of the engine. Accordingly, the compression ratio at partial loads will increase by 2–3 times, which will allow us to have a sufficient rate of combustion of the mixture in most engine operating modes without re-enrichment of the mixture. Therefore, the efficiency of the proposed engine at partial loads will be higher than the efficiency of the prototype.

 Increasing the maximum compression ratio in the supercharger to 4–6 will reduce the compression ratio in the engine cylinders by 1.5–2 times while increasing the total compression ratio by 2–3 times.

 A decrease in the compression ratio in the engine cylinders by about one and a half to two times and cooling of the air compressed by the supercharger in the cooler will allow a rather low mixture temperature at the end of compression in the cylinder. This will ensure engine operation without detonation on gasoline with a low octane rating. At the same time, the increased combustion rate of the mixture due to its high pressure when the engine load is close to maximum can be reduced by leaning the mixture, or compensate by reducing the ignition timing.

 The degree of expansion in the proposed engine is 3 ÷ 4 times greater than that of conventional gasoline engines, and the unit mass of the working gas will produce 1.5 times more work when expanding, therefore, to obtain the same power, you can reduce the working consumption by 1.5 times gas. With the same cylinder volume, the degree of expansion in the engine cylinders can be increased by 1.5 times. The degree of expansion in the cylinders will be 1.5 times greater than the maximum total degree of compression in the engine and may be 1.5 ÷ 2 times more than that of the prototype. This will make better use of fuel energy.

 The proposed engine is illustrated by the drawings shown in FIG. 1 ÷ 5.

 In FIG. 1 shows a diagram of an engine during the intake of a mixture into a cylinder.

 In FIG. Figure 2 shows the engine cylinder while pushing the mixture back into the intake pipe through the intake valve.

 In FIG. 3 shows an engine cylinder during compression of a mixture.

 In FIG. 4 shows an engine cylinder during a stroke.

 In FIG. 5 shows the engine cylinder at the time of exhaustion.

 The internal combustion engine (Fig. 1) contains a cylinder 1, closed by a cover 2, equipped with an inlet valve 3 and an exhaust valve 4, a piston 5, reciprocating and connected by a connecting rod 6 to the shaft 7, a fuel supply device 8, a valve control mechanism 9 3, 4, providing the possibility of closing the intake valve 3 in the second half of the piston 5 to TDC after the intake stroke, the intake pipe 10 connected to the chamber of the intake valve 3, an engine power control device comprising a supercharger 11, pressure-controlled with the intake pipe 10, a cooler 12 included in the cut-off of the intake pipe 10 after the blower 11, a variator 13, mechanically connecting the engine shaft 7 to the blower shaft 11, the gear ratio change mechanism 14 of the variator 13, the throttle valve 15 mounted on the compressor inlet 11. There is a spark plug 16 installed in the cover 2. The mechanism 14 for changing the gear ratio of the variator 13 is controlled by the accelerator pedal through a gear servo (not shown). To control the engine, it is possible to use microprocessors with systems for influencing the mechanism 14 for changing the gear ratio of the variator 13, the fuel supply device 8, the spark plug 16 and other engine systems.

 The operation of the engine is as follows. First, the piston 5 moves to the BDC, the inlet valve 3 is open, the mixture enters the cylinder 1 and the inlet occurs (shown in Fig. 1). After the passage of the BDC, the piston 5 moves to the TDC and the mixture from the cylinder 1 is pushed through the inlet valve 3 back into the inlet pipe 10 (shown in Fig. 2). After the piston 5 passes 70–80% of the stroke, the inlet valve 3 closes, and with the further movement of the piston 5 to TDC, the mixture is compressed in cylinder 1 (shown in Fig. 3). When the piston 5 approaches TDC, the spark plug 16 ignites the mixture and fuel is burned. The temperature and pressure of the gas in the cylinder 1 increase, the piston 5 passes through the BDC and, under the action of expanding gases, moves to the BDC, that is, a stroke occurs (shown in Fig. 4). When the piston 5 approaches the BDC, the exhaust valve 4 opens, and when the piston 5 moves to the TDC, the exhaust gases are displaced into the atmosphere, that is, release occurs (shown in Fig. 5). Then everything repeats.

 Regulation of engine power is as follows. To increase engine power, the speed of rotation of the shaft of the supercharger 11 relative to the shaft 7 is increased by changing the gear ratio of the variator 13 by the mechanism 14, while the pressure on the pressure of the supercharger 11 increases and the amount of mixture entering the cylinder 1 per cycle increases. To reduce engine power, the rotational speed of the shaft of the supercharger 11 is reduced relative to the motor shaft 7, while the pressure at the pressure head of the supercharger 11 is reduced and the amount of mixture entering the cylinder 1 per cycle is reduced. Thus, the pressure at the pressure of the supercharger 11 is reduced to almost atmospheric pressure. A further decrease in pressure at the pressure head of the supercharger 11 and, accordingly, a decrease in engine power is performed by covering the throttle valve 15, but this is used only at idle speeds.

 In the proposed engine as a supercharger 11 it is possible to use any type of compressor: centrifugal, rotary, reciprocating and others.

 As a device for controlling the speed of the supercharger 11, various devices can be used: variators, gearboxes, adjustable hydrostatic gears, torque converters and other devices.

 As a cooler 12 it is possible to use regenerative or regenerative heat exchangers.

 As a fuel supply device 8, carburetors and devices with fuel injection into the intake pipe can be used. But the greatest efficiency will be provided by fuel injection devices with fuel injection into the cylinders, and multi-stage fuel injection is possible to reduce the maximum pressure in the cylinders.

 In the proposed engine, a known device, that is, an engine with continued expansion, is supplemented by a known part, that is, a high pressure supercharger with a cooler and a variator. A similar connection for engine specialists is unusual. Moreover, pressurization and continued expansion in the main cylinders are considered incompatible, mutually exclusive, since instead of compression in the engine cylinders, air is compressed in a separate supercharger with lower efficiency than in the cylinders, and the mixture is pushed back from the cylinders into the inlet pipeline with energy costs for pushing the mixture and moving the pistons.

 It is unusual for specialists to use the overpressure associated with the motor shaft of the engine, not to increase the specific power of the engine, but to control the engine power in all operating modes, except for idling.

 But, in addition to reducing the size and weight of the engine to values characteristic of conventional gasoline engines, providing more economical than throttling, regulating engine power, the connection of high boost with continued expansion in the main cylinders provides new technical results.

 Firstly, the proposed engine in comparison with the prototype has a 2–3 times greater overall compression ratio due to the implementation of two-stage compression with intermediate cooling, therefore, the compression ratio at partial loads will increase by 2–3 times. This will increase engine efficiency over the entire load range, since it will not be necessary to re-enrich the mixture at low loads.

 Secondly, a decrease in the compression ratio in the engine cylinder by 1.5 ÷ 2 times during cooling of the air compressed by the supercharger in the cooler will allow a sufficiently low mixture temperature at the end of compression in the cylinders and ensure the operation of the proposed engine on fuel with a low octane number, i.e., more cheap fuel.

 Thirdly, the degree of expansion in the engine cylinders will be approximately 1.5 times greater than the maximum total compression ratio in the engine and may be 1.5–2 times greater than that of the prototype, and this will allow more complete use of fuel energy.

 Fourth, the efficiency of the proposed engine remains approximately constant over a wide range of load changes. With a decrease in engine load, the discharge pressure decreases and the energy consumption for the compressor compresses a unit mass of gas decreases, but the mechanical losses per unit mass of gas operating in the engine increase by almost the same amount.

 Calculations show that the proposed engine can have a maximum total compression ratio of 10 ÷ 25, expansion ratio in the cylinders 12 ÷ 35, compression ratio in the cylinders 4 ÷ 8, compression ratio in the supercharger 2 ÷ 6. The prototype has a compression ratio of 8 and an expansion ratio of 16.

 In all operating modes, the efficiency of the proposed engine will be higher than the efficiency of the prototype, and with a decrease in load, the difference increases. And since automobile engines operate at partial loads up to 90% of the time, the proposed engine will provide some fuel economy.

Claims (3)

 1. An internal combustion engine comprising cylinders closed by caps, equipped with inlet valves and exhaust valves, pistons located in the cylinders, reciprocating between the upper and lower dead points and connected by a movement conversion mechanism with a shaft, a fuel supply device, an intake pipe connected to the chambers of the intake valves, a valve control mechanism that allows the intake valves to close in the second half of the stroke to the top dead center ke after the intake stroke, an engine power control device, characterized in that the engine power control device comprises a supercharger connected in pressure to the intake manifold, a cooler included in the cut of the intake manifold after the supercharger, a supercharger speed control device, for example a variator, mechanically connecting the shaft engine with a supercharger shaft, a mechanism for changing the gear ratio of a supercharger speed control device connected to controls ia engine power.  2. The internal combustion engine according to claim 1, characterized in that the valve control mechanism is configured to close the intake valves during the piston stroke to top dead center, after the intake stroke, after the piston passes 70-80% of the stroke, and the cylinders, pistons and the mechanism for converting the movement of the pistons with the shaft is configured to provide a compression ratio in the cylinders of 4-8 after closing the intake valves and an expansion ratio of 12-35 when the pistons move from TDC to BDC.  3. The internal combustion engine according to claim 1, characterized in that the engine has a total total compression ratio of 10-25, ensured by performing a supercharger with a maximum compression ratio of 2-6, a compression ratio in the engine cylinders of 4- 8 and the presence of a compressed air cooler.

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