Crankcase forced ventilation system and control method thereof, supercharged engine and vehicle

Abstract

The invention relates to a crankcase forced ventilation system and a control method thereof, a supercharged engine and a vehicle, and belongs to the technical field of engines. The crankcase forced ventilation system comprises an air inlet system of an engine, a first ventilation pipeline and a second ventilation pipeline, the air inlet system comprises an air filter, a supercharger, a throttle valve and an air inlet manifold which are sequentially communicated through pipelines, the air inlet system is communicated with an air cylinder of the engine through the air inlet manifold, and the first end of the first ventilation pipeline is communicated with a crankcase; the first ventilation pipeline is provided with a first crankcase forced ventilation PCV valve, the second ventilation pipeline is provided with a second crankcase forced ventilation PCV valve, the first end of the second ventilation pipeline is communicated with the crankcase, the second end of the second ventilation pipeline is communicated with a pipeline connected between the supercharger and the air filter, and the second ventilation pipeline is provided with a vacuum pump. When the engine is in various working conditions, waste gas in the crankcase can be smoothly circulated while the pressure in the crankcase is small.

Description

Technical Field

[0001] The present disclosure relates to the technical field of engines, and in particular to a crankcase forced ventilation system and a control method thereof, a supercharged engine and a vehicle. Background Art

[0002] The crankshaft of the engine is connected to the connecting rod, which converts the reciprocating motion of the piston into its own rotational motion under the drive of the connecting rod, and then performs work externally. The crankcase is the part at the bottom of the cylinder block where the crankshaft is installed.

[0003] The exhaust gas generated when the engine is working will inevitably leak into the crankcase through the gap between the piston and the cylinder, which will not only reduce the service life of the engine oil, block the oil circuit, and cause corrosion and accelerated wear of engine parts. It will also cause the pressure in the crankcase to be too high, causing the crankcase seal to be destroyed, causing oil and exhaust gas leakage, and causing pollution to the engine compartment and the atmosphere.

[0004] In supercharged engines under high-load supercharging conditions, a ventilation line connected to the crankcase is usually set after the air filter of the engine intake system. The negative pressure generated at the interface between the ventilation line and the intake system forces the exhaust gas in the crankcase to be sucked into the intake system, thus realizing the recycling of the exhaust gas in the crankcase. However, when the engine is under medium and low speed and high load conditions, the vacuum degree at the interface of the ventilation line is insufficient, resulting in the exhaust gas in the crankcase being difficult to circulate smoothly when the internal pressure of the crankcase is low. Summary of the invention

[0005] In view of this, the embodiments of the present disclosure provide a crankcase forced ventilation system and a control method thereof, a supercharged engine and a vehicle, which can make the pressure in the crankcase lower and allow the exhaust gas in the crankcase to circulate smoothly when the engine is in various working conditions. The technical solution is as follows:

[0006] In a first aspect, a crankcase forced ventilation system is provided, the crankcase forced ventilation system comprising an intake system of an engine, a first ventilation line, and a second ventilation line;

[0007] The intake system includes an air filter, a supercharger, a throttle valve and an intake manifold which are sequentially connected through pipelines, and is connected to the cylinders of the engine through the intake manifold;

[0008] The first end of the first ventilation line is in communication with the crankcase, the second end of the first ventilation line is in communication with the intake manifold, the first ventilation line has a first crankcase positive ventilation (PCV) valve, and when the first PCV valve is opened, gas flows from the first end of the first ventilation line to the second end of the first ventilation line;

[0009] A first end of the second ventilation line is communicated with the crankcase, a second end of the second ventilation line is communicated with a line connected between the supercharger and the air filter, a vacuum pump is provided in the second ventilation line, and when the vacuum pump is turned on, gas flows from the first end of the second ventilation line to the second end of the second ventilation line.

[0010] In a possible implementation, the first ventilation line further includes a first oil-gas separator, and the first oil-gas separator is located between the crankcase and the first PCV valve.

[0011] In one possible implementation, the crankcase forced ventilation system also includes an air supply branch, a first end of the air supply branch is connected to a pipeline in the intake system, a second end of the air supply branch is connected to the crankcase, a second PCV valve is provided in the air supply branch, and when the second PCV valve is opened, gas flows from the first end of the air supply branch to the second end of the air supply branch.

[0012] In a possible implementation, the first end of the air supplementation branch is in communication with a pipeline between the supercharger and the cylinder.

[0013] In a possible implementation, the second ventilation line further includes a second oil-gas separator, and the second oil-gas separator is located between the crankcase and the vacuum pump.

[0014] In one possible implementation, the vacuum pump is an electronic vacuum pump, and the vacuum pump, the supercharger and the engine are all connected to the vehicle's electronic control unit ECU signal, and the ECU is used to monitor the operating status of the supercharger and the current speed of the engine, and control the operation of the vacuum pump according to the operating status of the supercharger and the current speed of the engine.

[0015] In a possible implementation, the crankcase positive ventilation system further includes a supercharger blow-by gas passage, and the supercharger blow-by gas passage is suitable for connecting the crankcase and the supercharger.

[0016] In a second aspect, an engine is provided, comprising a cylinder, a crankcase and a crankcase forced ventilation system as described in any one of the first aspects, wherein the cylinder is connected to an intake manifold of the crankcase forced ventilation system, and a first end of a first ventilation line and a first end of a second ventilation line of the crankcase forced ventilation system are both connected to the crankcase.

[0017] In a third aspect, a vehicle is provided, comprising the engine as described in the second aspect.

[0018] In a fourth aspect, a control method for a crankcase forced ventilation system is provided, wherein the control method for a crankcase forced ventilation system is used to control the crankcase forced ventilation system as described in any one of the first aspects, and comprises:

[0019] When the engine is in a low-speed and low-load operating condition, controlling the vacuum pump of the crankcase forced ventilation system to be turned off;

[0020] When the engine is in a high-load condition, the vacuum pump is controlled to rotate at a rated speed of the vacuum pump, so that the internal pressure of the crankcase is made negative pressure through the vacuum pump's suction, wherein the rated speed of the vacuum pump is obtained according to the current speed of the engine.

[0021] In the solution shown in the present disclosure, when the engine is in a low-speed and low-load condition, the throttle opening is small, the pressure in the intake manifold is small, and the pressure in the crankcase is relatively large, so the first PCV valve can be opened. The exhaust gas in the crankcase can re-enter the cylinder for combustion via the first ventilation line and the intake manifold, while reducing the pressure in the crankcase.

[0022] When the engine is in a low-speed and high-load condition, the throttle opening is large, the pressure in the intake manifold is large, and the pressure in the crankcase is insufficient to open the first PCV valve, so the first PCV valve is closed. At this time, the vacuum pump is controlled to open, and the exhaust gas can be pumped through the second ventilation pipeline to the pipeline between the supercharger and the air filter, so that the exhaust gas in the crankcase can re-enter the cylinder for combustion through the second ventilation pipeline, the supercharger, the throttle and the intake manifold, while reducing the pressure in the crankcase.

[0023] When the engine is in high-speed and high-load conditions, due to the large intake volume of the intake system, the pressure loss of the pipeline after the air filter is large, so that the second end of the second ventilation pipeline and the pipeline interface between the supercharger and the air filter have a small pressure. Therefore, the exhaust gas in the crankcase can enter the pipeline between the supercharger and the air filter 11 through the second ventilation pipeline. Thus, the exhaust gas in the crankcase can re-enter the cylinder for combustion through the second ventilation pipeline, the supercharger, the throttle valve and the intake manifold, and at the same time reduce the pressure in the crankcase. At this time, there is no need to turn on the vacuum pump 31, which can achieve energy-saving effects.

[0024] Therefore, when the engine is in various operating conditions, the exhaust gas in the crankcase can circulate smoothly while keeping the pressure in the crankcase low. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 is a schematic diagram of a crankcase forced ventilation system provided by an embodiment of the present disclosure when it is in a low-speed and low-load operating condition;

[0027] Figure 2 is a schematic diagram of a crankcase forced ventilation system provided by an embodiment of the present disclosure when it is in a high-load working condition;

[0028] Figure 3 It is a schematic diagram of a crankcase forced ventilation system provided by an embodiment of the present disclosure having an air supplementary branch and being in a high-load working condition.

[0029] Description of Reference Numerals

[0030] 1. Intake system; 11. Air filter; 12. Supercharger; 121. Supercharger blowby passage; 13. Throttle valve; 14. Intake manifold; 2. First ventilation line; 21. First PCV valve; 22. First oil-gas separator; 3. Second ventilation line; 31. Vacuum pump; 32. Second oil-gas separator; 4. Cylinder; 41. Piston; 42. Cylinder head intake duct; 5. Crankcase; 6. Air supply branch; 61. Second PCV valve; 7. Engine; 8. ECU. DETAILED DESCRIPTION

[0031] In order to make the objectives, technical solutions and advantages of the present disclosure more clear, the embodiments of the present disclosure will be further described in detail below with reference to the accompanying drawings.

[0032] In a first aspect, the present embodiment relates to a crankcase forced ventilation system, such as Figure 1 The diagram shows the crankcase forced ventilation system in low speed and low load conditions. Figure 2 The diagram shows the crankcase forced ventilation system under high load conditions. Figure 3 The diagram shows a crankcase positive ventilation system having an air supply branch 6 and under high load conditions.

[0033] refer to Figure 1As shown, the crankcase forced ventilation system includes an intake system 1, a first ventilation line 2 and a second ventilation line 3 of an engine 7. The intake system 1 includes an air filter 11, a supercharger 12, a throttle valve 13 and an intake manifold 14 which are sequentially connected through pipes, and is connected to the cylinder 4 of the engine 7 through the intake manifold 14. For example, the intake manifold 14 can be connected to the cylinder head intake passage 42 of the cylinder 4, so that the gas in the intake manifold 14 can be introduced into the combustion chamber of the cylinder 4 for combustion.

[0034] The first end of the first ventilation line 2 is connected to the crankcase 5, and the second end of the first ventilation line 2 is connected to the intake manifold 14. The first ventilation line 2 has a first PCV valve 21, and when the first PCV valve 21 is opened, the gas flows from the first end of the first ventilation line 2 to the second end of the first ventilation line 2.

[0035] The first end of the second ventilation pipeline 3 is connected to the crankcase 5, and the second end of the second ventilation pipeline 3 is connected to the pipeline connected between the supercharger 12 and the air filter 11. The second ventilation pipeline 3 has a vacuum pump 31, and when the vacuum pump 31 is turned on, the gas flows from the first end of the second ventilation pipeline 3 to the second end of the second ventilation pipeline 3.

[0036] Based on the above, continue to refer to Figure 1 As shown, when the engine 7 is in a low-speed and low-load condition, the throttle 13 is opened at a small degree, the pressure in the intake manifold 14 is small, and the pressure in the crankcase 5 is relatively large, so the first PCV valve 21 can be opened. The exhaust gas in the crankcase 5 can re-enter the cylinder 4 through the first ventilation line 2 and the intake manifold 14 for combustion, while reducing the pressure in the crankcase 5.

[0037] refer to Figure 2 As shown, when the engine 7 is in a low-speed and high-load condition, the throttle 13 is opened at a large degree, the pressure in the intake manifold 14 is large, and the pressure in the crankcase 5 is insufficient to open the first PCV valve, so the first PCV valve 21 is closed. At this time, the vacuum pump 31 is controlled to be turned on, and the exhaust gas can be pumped into the pipeline between the supercharger 12 and the air filter 11 through the second ventilation pipeline 3, so that the exhaust gas in the crankcase 5 can re-enter the cylinder 4 through the second ventilation pipeline 3, the supercharger 12, the throttle 13 and the intake manifold 14 for combustion, and at the same time, the pressure in the crankcase 5 is reduced.

[0038] Continue to refer Figure 2As shown, when the engine is in a high-speed and high-load condition, due to the large intake volume of the intake system 1, the pressure loss of the pipeline after the air filter 11 is large, so that the second end of the second ventilation pipeline 3 and the pipeline interface between the supercharger 12 and the air filter 11 have a small pressure. Therefore, the exhaust gas in the crankcase 5 can enter the pipeline between the supercharger 12 and the air filter 11 through the second ventilation pipeline 3. Therefore, the exhaust gas in the crankcase 5 can re-enter the cylinder 4 through the second ventilation pipeline 3, the supercharger 12, the throttle 13 and the intake manifold 14 to be burned, and at the same time, the pressure in the crankcase 5 is reduced. At this time, there is no need to turn on the vacuum pump 31, which can achieve the effect of energy saving.

[0039] Therefore, when the engine 7 is in various working conditions, the exhaust gas in the crankcase 5 can be circulated smoothly while the pressure in the crankcase 5 is kept low.

[0040] It should be noted that the above judgment conditions for high-speed and high-load working conditions can be set by the vehicle manufacturer according to the calibration conditions during design. For example, the calibration conditions can be set as high speed when the engine 7 speed is not less than 2800r / min, and the high load when the engine 7 working condition when the supercharger 12 is turned on. Of course, the above conditions can be adjusted during specific implementation. Correspondingly, when the engine speed is lower than 2800r / min, the engine 7 is in a low-speed working condition, and when the supercharger 12 is turned on, the engine 7 is in a small load working condition.

[0041] In one example, continue to refer to Figure 2 As shown, the first ventilation line 2 further includes a first oil-gas separator 22 , and the first oil-gas separator 22 is located between the crankcase 5 and the first PCV valve 21 .

[0042] In this way, when the exhaust gas passes through the first ventilation line 2, the first oil-gas separator 22 can separate the engine oil in the exhaust gas and guide the engine oil into the oil pan of the crankcase 5, thereby reducing the engine oil loss. At the same time, the possibility of clogging of the first PCV valve 21 can be reduced, thereby facilitating the smooth circulation of the exhaust gas in the crankcase 5 when the engine 7 is in a low-speed and low-load working condition.

[0043] In one example, continue to refer to Figure 3 As shown, the crankcase forced ventilation system further includes an air supply branch 6, the first end of which is connected to a pipeline in the intake system 1. Figure 3 In the figure, the first end of the air supply branch 6 is connected to the intake manifold 14, but the first end of the air supply branch 6 can also be connected to the pipeline between the supercharger 12 and the throttle valve 13, or the first end of the air supply branch 6 can also be connected to the pipeline between the air filter 11 and the supercharger 12.

[0044] In addition, the second end of the air supply branch 6 is connected to the crankcase 5. For example, the second end of the air supply branch 6 can be directly connected to the crankcase 5, or can be connected through other components connected to the crankcase 8 to achieve indirect connection between the air supply branch 6 and the crankcase 5. The air supply branch 6 has a second PCV valve 61, and when the second PCV valve 61 is opened, the gas flows from the first end of the air supply branch 6 to the second end of the air supply branch 6.

[0045] So, continue to refer to Figure 1 As shown, when the engine 7 is in a low-speed and low-load operating condition, since the pressure in the intake manifold 14 is relatively small, the first PCV valve 21 is opened, and the second PCV valve 61 is closed, so that the exhaust gas in the crankcase 5 enters the intake manifold 14 through the first ventilation line 2, and the pressure in the crankcase 5 is reduced. At the same time, since the second ventilation line 3 is in a normally open state when the vacuum pump 31 is turned off, fresh air can pass through the air filter 11 and the second ventilation line 3 into the crankcase 5 to replenish air in the crankcase 5.

[0046] Continue to refer Figure 3 As shown, when the engine 7 is in a low-speed and high-load condition, the vacuum pump 31 is turned on, so that the pressure inside the crankcase 5 is reduced, and the intake manifold 14 has a relatively high pressure, so that the first PCV valve 21 is closed and the second PCV valve 61 is opened. In this way, a large amount of fresh air entering the intake manifold 14 from the outside through the air filter 11, the supercharger 12 and the throttle valve 13 can enter the crankcase 5 through the air supply branch 6 to supply air to the crankcase 5.

[0047] When the engine 7 is in a high-speed and high-load condition, due to the large intake volume of the intake system 1 and the large pressure loss of the pipeline after the air filter 11, the pressure at the second end of the second ventilation pipeline 3 and the pipeline interface between the supercharger 12 and the air filter 11 may be lower than the pressure in the crankcase 5, so that the exhaust gas in the crankcase 5 can be discharged from the second ventilation pipeline 3. At the same time, due to the high pressure in the intake manifold 14, the first PCV valve 21 is closed, and the second PCV valve 61 is opened, so that the gas in the intake manifold 14 can enter the crankcase 5 for air replenishment.

[0048] However, at this time, since the speed at which the exhaust gas in the crankcase 5 is discharged from the second ventilation pipeline 3 may be not much different from the speed at which the gas in the intake manifold 14 enters the crankcase 5, or even lower than the speed at which the gas in the intake manifold 14 enters the crankcase 5, the pressure inside the crankcase 5 is difficult to reduce or even increases. Therefore, when the engine 7 is in a high-speed and high-load condition, the vacuum pump 31 may be controlled to be turned on, which can reduce the pressure inside the crankcase 5 on the one hand, and increase the speed at which fresh air enters the crankcase 5 for replenishing gas on the other hand.

[0049] As described above, when the engine 7 is in various working conditions, the crankcase can be replenished with fresh air, thereby accelerating the speed at which the exhaust gas in the crankcase 5 is swept out, which is beneficial to extending the service life of the engine oil, avoiding oil circuit blockage, reducing condensation of condensed water, and avoiding corrosion and accelerated wear of engine parts.

[0050] Among them, a small amount of exhaust gas passing through the first ventilation pipeline 2 and filtered by the first oil-gas separator 22 may enter the crankcase 5 along with fresh air, but since the amount of this part of exhaust gas is far less than the amount of fresh air, it will not affect the discharge of exhaust gas inside the crankcase 5.

[0051] In one example, the first end of the supplementary air branch line 6 is in communication with a pipeline between the supercharger 12 and the cylinder 4 .

[0052] For example Figure 3 As shown, the first end of the air supplementary branch 6 may be in communication with the intake manifold 14 , or the first end of the air supplementary branch 6 may also be in communication with the intake manifold 14 , and the pipeline between the supercharger 12 and the throttle valve 13 is in communication.

[0053] In this way, since the pipeline pressure between the supercharger 12 and the cylinder 4 is relatively high, the pressure of the air supply branch 6 can also be relatively high, which is conducive to fresh air entering the crankcase 5 from the air supply branch 6 when the engine is under high load conditions.

[0054] In one example, reference Figure 2 and Figure 3 As shown, the second ventilation line 3 further includes a second oil-gas separator 32 , and the second oil-gas separator 32 is located between the crankcase 5 and the vacuum pump 31 .

[0055] Thus, when the exhaust gas passes through the second ventilation line 3, the second oil-gas separator 32 can separate the oil in the exhaust gas and introduce the oil into the oil pan of the crankcase 5, thereby reducing the oil loss. At the same time, it can also avoid or reduce the possible loss of the vacuum pump 31 caused by the oil.

[0056] In one example, the vacuum pump 31 is an electronic vacuum pump. The vacuum pump 31, the supercharger 12 and the engine 7 are all signal-connected to the vehicle's electronic control unit ECU8. The ECU8 is used to monitor the operating status of the supercharger 12 and the current speed of the engine 7, and control the operation of the vacuum pump 31 according to the operating status of the supercharger 12 and the current speed of the engine 7.

[0057] For example, when the supercharger 12 is turned on, it can be experimentally measured that when the vacuum pump 3 is turned off and the crankcase 5 is under negative pressure, the current speed of the engine 7 is the first operating speed, and when the crankcase 5 is under positive pressure, the current speed of the engine 7 is the second operating speed. When the current speed of the engine 7 is the second operating speed, it is experimentally measured that when the crankcase 5 can be maintained in the working negative pressure range, the speed of the vacuum pump 3 is the calibrated speed. The working negative pressure range can be -5.1kpa to -0.25kpa.

[0058] In this way, when the ECU 8 detects that the supercharger 12 is turned off, the ECU 8 can control the vacuum pump 31 to be turned off. When the ECU 8 detects that the supercharger 12 is turned on and the current speed of the engine 7 is the first operating speed, the ECU 8 can control the vacuum pump 31 to be turned off. When the ECU 8 detects that the supercharger 12 is turned on and the current speed of the engine 7 is the second operating speed, the vacuum pump 3 is started and runs at the calibrated speed.

[0059] Therefore, the operation of the vacuum pump 3 can be conveniently and instantly controlled by the ECU 8 , and energy saving can be achieved while maintaining the negative pressure inside the crankcase 5 .

[0060] In one example, since the supercharger 12 may generate polluting exhaust gas during operation, in order to prevent the exhaust gas from polluting the engine compartment and the atmosphere, the crankcase forced ventilation system also includes a supercharger blowby gas passage 121, which is suitable for connecting the crankcase 5 and the supercharger 12. Thus, the intermediate blowby gas of the supercharger 12 can be introduced into the crankcase 5 through the supercharger blowby gas passage 121, and enters the engine intake system 1 with the exhaust gas in the crankcase 5 for recycling.

[0061] In the disclosed embodiment, when the engine 7 is in a low-speed and low-load condition, the throttle 13 is opened at a small degree, the pressure in the intake manifold 14 is small, and the pressure in the crankcase 5 is relatively large, so the first PCV valve 21 can be opened. The exhaust gas in the crankcase 5 can re-enter the cylinder 4 through the first ventilation line 2 and the intake manifold 14 for combustion, while reducing the pressure in the crankcase 5.

[0062] When the engine 7 is in a low-speed and high-load condition, the throttle 13 is opened at a large degree, the pressure in the intake manifold 14 is large, and the pressure in the crankcase 5 is insufficient to open the first PCV valve, so the first PCV valve 21 is closed. At this time, the vacuum pump 31 is controlled to be turned on, and the exhaust gas can be pumped through the second ventilation pipeline 3 to the pipeline between the supercharger 12 and the air filter 11, so that the exhaust gas in the crankcase 5 can re-enter the cylinder 4 through the second ventilation pipeline 3, the supercharger 12, the throttle 13 and the intake manifold 14 for combustion, and the pressure in the crankcase 5 is reduced at the same time.

[0063] When the engine is in high-speed and high-load conditions, due to the large intake volume of the intake system 1, the pressure loss of the pipeline after the air filter 11 is large, so that the second end of the second ventilation pipeline 3 and the pipeline interface between the supercharger 12 and the air filter 11 have a small pressure. Therefore, the exhaust gas in the crankcase 5 may be able to enter the pipeline between the supercharger 12 and the air filter 11 through the second ventilation pipeline 3. Therefore, the exhaust gas in the crankcase 5 can re-enter the cylinder 4 through the second ventilation pipeline 3, the supercharger 12, the throttle 13 and the intake manifold 14 to be burned, and at the same time, the pressure in the crankcase 5 is reduced. At this time, there is no need to turn on the vacuum pump 31, which can achieve the effect of energy saving.

[0064] Therefore, when the engine 7 is in various working conditions, the exhaust gas in the crankcase 5 can be circulated smoothly while the pressure in the crankcase 5 is kept low.

[0065] In the second aspect, the embodiment of the present disclosure also provides an engine, which includes a cylinder 4, a crankcase 5 and a crankcase forced ventilation system as any of the first aspect, the cylinder 4 is connected to the intake manifold 14 of the crankcase forced ventilation system, and the first end of the first ventilation line 2 and the first end of the second ventilation line 3 of the crankcase forced ventilation system are both connected to the crankcase 5.

[0066] In the disclosed embodiment, when the engine 7 is in a low-speed and low-load condition, the throttle 13 is opened at a small degree, the pressure in the intake manifold 14 is small, and the pressure in the crankcase 5 is relatively large, so the first PCV valve 21 can be opened. The exhaust gas in the crankcase 5 can re-enter the cylinder 4 through the first ventilation line 2 and the intake manifold 14 for combustion, while reducing the pressure in the crankcase 5.

[0067] When the engine 7 is in a low-speed and high-load condition, the throttle 13 is opened at a large degree, the pressure in the intake manifold 14 is large, and the pressure in the crankcase 5 is insufficient to open the first PCV valve, so the first PCV valve 21 is closed. At this time, the vacuum pump 31 is controlled to be turned on, and the exhaust gas can be pumped through the second ventilation pipeline 3 to the pipeline between the supercharger 12 and the air filter 11, so that the exhaust gas in the crankcase 5 can re-enter the cylinder 4 through the second ventilation pipeline 3, the supercharger 12, the throttle 13 and the intake manifold 14 for combustion, and the pressure in the crankcase 5 is reduced at the same time.

[0068] When the engine is in high-speed and high-load conditions, due to the large intake volume of the intake system 1, the pressure loss of the pipeline after the air filter 11 is large, so that the second end of the second ventilation pipeline 3 and the pipeline interface between the supercharger 12 and the air filter 11 have a small pressure. Therefore, the exhaust gas in the crankcase 5 may be able to enter the pipeline between the supercharger 12 and the air filter 11 through the second ventilation pipeline 3. Therefore, the exhaust gas in the crankcase 5 can re-enter the cylinder 4 through the second ventilation pipeline 3, the supercharger 12, the throttle 13 and the intake manifold 14 to be burned, and at the same time, the pressure in the crankcase 5 is reduced. At this time, there is no need to turn on the vacuum pump 31, which can achieve the effect of energy saving.

[0069] Therefore, when the engine 7 is in various working conditions, the exhaust gas in the crankcase 5 can be circulated smoothly while the pressure in the crankcase 5 is kept low.

[0070] In a third aspect, the embodiment of the present disclosure further provides a vehicle, the vehicle comprising the engine 7 as in the second aspect.

[0071] In the disclosed embodiment, when the engine 7 is in a low-speed and low-load condition, the throttle 13 is opened at a small degree, the pressure in the intake manifold 14 is small, and the pressure in the crankcase 5 is relatively large, so the first PCV valve 21 can be opened. The exhaust gas in the crankcase 5 can re-enter the cylinder 4 through the first ventilation line 2 and the intake manifold 14 for combustion, while reducing the pressure in the crankcase 5.

[0072] When the engine 7 is in a low-speed and high-load condition, the throttle 13 is opened at a large degree, the pressure in the intake manifold 14 is large, and the pressure in the crankcase 5 is insufficient to open the first PCV valve, so the first PCV valve 21 is closed. At this time, the vacuum pump 31 is controlled to be turned on, and the exhaust gas can be pumped through the second ventilation pipeline 3 to the pipeline between the supercharger 12 and the air filter 11, so that the exhaust gas in the crankcase 5 can re-enter the cylinder 4 through the second ventilation pipeline 3, the supercharger 12, the throttle 13 and the intake manifold 14 for combustion, and the pressure in the crankcase 5 is reduced at the same time.

[0073] When the engine is in high-speed and high-load conditions, due to the large intake volume of the intake system 1, the pressure loss of the pipeline after the air filter 11 is large, so that the second end of the second ventilation pipeline 3 and the pipeline interface between the supercharger 12 and the air filter 11 have a small pressure. Therefore, the exhaust gas in the crankcase 5 may be able to enter the pipeline between the supercharger 12 and the air filter 11 through the second ventilation pipeline 3. Therefore, the exhaust gas in the crankcase 5 can re-enter the cylinder 4 through the second ventilation pipeline 3, the supercharger 12, the throttle 13 and the intake manifold 14 to be burned, and at the same time, the pressure in the crankcase 5 is reduced. At this time, there is no need to turn on the vacuum pump 31, which can achieve the effect of energy saving.

[0074] Therefore, when the engine 7 is in various working conditions, the exhaust gas in the crankcase 5 can be circulated smoothly while the pressure in the crankcase 5 is kept low.

[0075] In a fourth aspect, an embodiment of the present disclosure further provides a method for controlling a crankcase forced ventilation system, the method for controlling a crankcase forced ventilation system is used to control any crankcase forced ventilation system according to the first aspect, and includes:

[0076] When the engine 7 is in a low-speed and low-load operating condition, the vacuum pump 31 of the crankcase positive ventilation system is controlled to be turned off.

[0077] When the engine 7 is in a high-load condition, the vacuum pump 31 is controlled to rotate according to the rated speed of the vacuum pump 31 , so that the internal pressure of the crankcase 5 is made negative pressure through the suction of the vacuum pump 31 , wherein the rated speed of the vacuum pump 31 is obtained according to the current speed of the engine 7 .

[0078] For example, when the supercharger 12 is turned on, it can be experimentally measured that when the vacuum pump 3 is turned off and the crankcase 5 is under negative pressure, the current speed of the engine 7 is the first operating speed, and when the crankcase 5 is under positive pressure, the current speed of the engine 7 is the second operating speed. When the current speed of the engine 7 is the second operating speed, it is experimentally measured that when the crankcase 5 can be maintained in the working negative pressure range, the speed of the vacuum pump 3 is the calibrated speed. The working negative pressure range can be -5.1kpa to -0.25kpa.

[0079] In this way, when ECU8 detects that the supercharger 12 is turned off, ECU8 can control the vacuum pump 31 to be turned off. When ECU8 detects that the supercharger 12 is turned on and the current speed of the engine 7 is the first operating speed, ECU8 can control the vacuum pump 31 to be turned off, that is, the calibrated speed of the vacuum pump 31 is zero. When ECU8 detects that the supercharger 12 is turned on and the current speed of the engine 7 is the second operating speed, the vacuum pump 3 is started and runs at a calibrated speed greater than zero.

[0080] Therefore, the operation of the vacuum pump 3 can be conveniently and instantly controlled by the ECU 8 , and energy saving can be achieved while maintaining the negative pressure inside the crankcase 5 .

[0081] In the disclosed embodiment, when the engine 7 is in a low-speed and low-load condition, the throttle 13 is opened at a small degree, the pressure in the intake manifold 14 is small, and the pressure in the crankcase 5 is relatively large, so the first PCV valve 21 can be opened. The exhaust gas in the crankcase 5 can re-enter the cylinder 4 through the first ventilation line 2 and the intake manifold 14 for combustion, while reducing the pressure in the crankcase 5.

[0082] When the engine 7 is in a low-speed and high-load condition, the throttle 13 is opened at a large degree, the pressure in the intake manifold 14 is large, and the pressure in the crankcase 5 is insufficient to open the first PCV valve, so the first PCV valve 21 is closed. At this time, the vacuum pump 31 is controlled to be turned on, and the exhaust gas can be pumped through the second ventilation pipeline 3 to the pipeline between the supercharger 12 and the air filter 11, so that the exhaust gas in the crankcase 5 can re-enter the cylinder 4 through the second ventilation pipeline 3, the supercharger 12, the throttle 13 and the intake manifold 14 for combustion, and the pressure in the crankcase 5 is reduced at the same time.

[0083] When the engine is in high-speed and high-load conditions, due to the large intake volume of the intake system 1, the pressure loss of the pipeline after the air filter 11 is large, so that the second end of the second ventilation pipeline 3 and the pipeline interface between the supercharger 12 and the air filter 11 have a small pressure. Therefore, the exhaust gas in the crankcase 5 may be able to enter the pipeline between the supercharger 12 and the air filter 11 through the second ventilation pipeline 3. Therefore, the exhaust gas in the crankcase 5 can re-enter the cylinder 4 through the second ventilation pipeline 3, the supercharger 12, the throttle 13 and the intake manifold 14 to be burned, and at the same time, the pressure in the crankcase 5 is reduced. At this time, there is no need to turn on the vacuum pump 31, thereby achieving an energy-saving effect.

[0084] Therefore, when the engine 7 is in various working conditions, the exhaust gas in the crankcase 5 can be circulated smoothly while the pressure in the crankcase 5 is kept low.

[0085] It should be noted that the terms "first", "second", etc. in the specification and claims of the present disclosure are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present disclosure can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are generally of the same type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0086] The above are only preferred embodiments of the present disclosure and are not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure should be included in the protection scope of the present disclosure.

Claims

1. A crankcase forced ventilation system, characterized in that: The crankcase forced ventilation system comprises an intake system (1) of an engine (7), a first ventilation pipeline (2) and a second ventilation pipeline (3); The air intake system (1) comprises an air filter (11), a supercharger (12), a throttle valve (13) and an intake manifold (14) which are sequentially connected through pipelines, and is connected to the cylinder (4) of the engine (7) through the intake manifold (14); The first end of the first ventilation line (2) is in communication with the crankcase (5), the second end of the first ventilation line (2) is in communication with the intake manifold (14), the first ventilation line (2) has a first crankcase forced ventilation (PCV) valve (21), and when the first PCV valve (21) is opened, gas flows from the first end of the first ventilation line (2) to the second end of the first ventilation line (2); The first end of the second ventilation pipeline (3) is in communication with the crankcase (5), and the second end of the second ventilation pipeline (3) is in communication with a pipeline connected between the supercharger (12) and the air filter (11). The second ventilation pipeline (3) has a vacuum pump (31), and when the vacuum pump (31) is turned on, gas flows from the first end of the second ventilation pipeline (3) to the second end of the second ventilation pipeline (3).

2. The crankcase positive ventilation system according to claim 1, characterized in that: The first ventilation pipeline (2) also has a first oil-gas separator (22), and the first oil-gas separator (22) is located between the crankcase (5) and the first PCV valve (21).

3. The crankcase positive ventilation system according to claim 2, characterized in that: The crankcase forced ventilation system further comprises an air supply branch (6), a first end of the air supply branch (6) being in communication with a pipeline in the intake system (1), a second end of the air supply branch (6) being in communication with the crankcase (5), a second PCV valve (61) being provided in the air supply branch (6), and when the second PCV valve (61) is opened, gas flows from the first end of the air supply branch (6) to the second end of the air supply branch (6).

4. The crankcase positive ventilation system according to claim 3, characterized in that: The first end of the air supplement branch (6) is in communication with a pipeline between the supercharger (12) and the cylinder (4).

5. The crankcase positive ventilation system according to claim 1, characterized in that: The second ventilation pipeline (3) also has a second oil-gas separator (32), and the second oil-gas separator (32) is located between the crankcase (5) and the vacuum pump (31).

6. The crankcase positive ventilation system according to claim 1, characterized in that: The vacuum pump (31) is an electronic vacuum pump. The vacuum pump (31), the supercharger (12) and the engine (7) are all connected to the vehicle's electronic control unit ECU (8) by signal. The ECU (8) is used to monitor the operating state of the supercharger (12) and the current speed of the engine (7), and to control the operation of the vacuum pump (31) according to the operating state of the supercharger (12) and the current speed of the engine (7).

7. The positive crankcase ventilation system according to claim 1, characterized in that: The crankcase forced ventilation system further comprises a supercharger blow-by gas passage (121), wherein the supercharger blow-by gas passage (121) is suitable for connecting the crankcase (5) and the supercharger (12).

8. An engine, characterized in that: The engine comprises a cylinder (4), a crankcase (5) and a crankcase forced ventilation system as described in any one of claims 1 to 7, wherein the cylinder (4) is connected to an intake manifold (14) of the crankcase forced ventilation system, and the first end of the first ventilation line (2) and the first end of the second ventilation line (3) of the crankcase forced ventilation system are both connected to the crankcase (5).

9. A vehicle, characterized in that: The vehicle comprises an engine (7) as claimed in claim 8.

10. A method for controlling a crankcase forced ventilation system, characterized in that: The control method of the crankcase positive ventilation system is used to control the crankcase positive ventilation system according to any one of claims 1 to 7, and comprises: When the engine (7) is in a low-speed and low-load operating condition, the vacuum pump (31) of the crankcase forced ventilation system is controlled to be turned off; When the engine (7) is in a high-load condition, the vacuum pump (31) is controlled to rotate at a rated speed of the vacuum pump (31), so that the internal pressure of the crankcase (5) becomes a negative pressure through the suction of the vacuum pump (31), wherein the rated speed of the vacuum pump (31) is obtained according to the current speed of the engine (7).

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