Positive crankcase ventilation system and control method therefor, turbocharged engine, and vehicle

Abstract

NOT VISIBLE DUE TO STATUS OF PATENT

Description

Crankcase forced ventilation system and its control method, turbocharged engine and vehicle

[0001] This application claims priority to Chinese Patent Application No. 202510236798.8, filed on February 28, 2025, entitled "Crankcase Forced Ventilation System and Control Method Thereof, Turbocharged Engine and Vehicle", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure relates to the field of engine technology, and in particular to a crankcase forced ventilation system and its control method, a turbocharged engine, and a vehicle. Background Technology

[0003] The crankshaft of an engine is connected to the connecting rod. Driven by the connecting rod, it converts the reciprocating motion of the piston into its own rotational motion, which then performs work. The crankcase is the part at the bottom of the cylinder block where the crankshaft is mounted.

[0004] When an engine is running, the exhaust gas produced inevitably leaks into the crankcase through the gap between the piston and the cylinder. This not only causes problems such as reduced oil life, oil passage blockage, corrosion of engine parts and accelerated wear, but also causes excessive pressure in the crankcase, which can damage the crankcase seal, resulting in oil and exhaust gas leakage and pollution of the engine compartment and the atmosphere.

[0005] Turbocharged engines, under high-load turbocharging conditions, typically have a ventilation duct connected to the crankcase after the air filter in the engine's intake system. The negative pressure generated at the interface between the ventilation duct and the intake system forces exhaust gases from the crankcase into the intake system, achieving crankcase gas recirculation. However, under low-to-medium speed, high-load conditions, the vacuum at the ventilation duct interface is insufficient, leading to poor exhaust gas recirculation in the crankcase due to lower internal pressure. Summary of the Invention

[0006] Therefore, this disclosure provides a crankcase forced ventilation system and its control method, a turbocharged engine, and a vehicle, which, under various engine operating conditions, can ensure smooth circulation of exhaust gas in the crankcase while maintaining relatively low pressure. The technical solution is as follows:

[0007] In a first aspect, a crankcase forced ventilation system is provided, the crankcase forced ventilation system including an engine intake system, a first ventilation duct and a second ventilation duct;

[0008] The intake system includes an air filter, a turbocharger, a throttle valve, and an intake manifold connected in sequence through pipes, and is connected to the cylinders of the engine through the intake manifold;

[0009] The first end of the first ventilation duct is connected to the crankcase, and the second end of the first ventilation duct is connected to the intake manifold. The first ventilation duct has a first crankcase forced ventilation (PCV) valve, and when the first PCV valve is open, gas flows from the first end of the first ventilation duct to the second end of the first ventilation duct.

[0010] The first end of the second ventilation duct is connected to the crankcase, and the second end of the second ventilation duct is connected to the duct between the supercharger and the air filter. The second ventilation duct has a vacuum pump, and when the vacuum pump is turned on, gas flows from the first end of the second ventilation duct to the second end of the second ventilation duct.

[0011] In one possible implementation, the first ventilation duct also includes a first oil-gas separator located between the crankcase and the first PCV valve.

[0012] In one possible implementation, the crankcase forced ventilation system further includes a make-up air branch, the first end of which is connected to a pipe in the intake system, the second end of which is connected to the crankcase, the make-up air branch having a second PCV valve, and when the second PCV valve is open, allowing gas to flow from the first end of the make-up air branch to the second end of the make-up air branch.

[0013] In one possible implementation, the first end of the air supply branch is connected to the pipeline between the turbocharger and the cylinder.

[0014] In one possible implementation, the second ventilation duct also includes a second oil-gas separator located between the crankcase and the vacuum pump.

[0015] 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). The ECU is used to monitor the operating status of the supercharger and the current speed of the engine, and to control the operation of the vacuum pump based on the operating status of the supercharger and the current speed of the engine.

[0016] In one possible implementation, the crankcase forced ventilation system further includes a turbocharger blow-by passage adapted to connect the crankcase and the turbocharger.

[0017] In a second aspect, an engine is provided, the engine including a cylinder, a crankcase, and a crankcase forced ventilation system as described in any of the first aspects, the cylinder being connected to an intake manifold of the crankcase forced ventilation system, and a first end of a first ventilation duct and a first end of a second ventilation duct of the crankcase forced ventilation system being connected to the crankcase.

[0018] Thirdly, a vehicle is provided, the vehicle including an engine as described in the second aspect.

[0019] Fourthly, a control method for a crankcase forced ventilation system is provided, the control method for controlling a crankcase forced ventilation system as described in any of the first aspects, and includes:

[0020] When the engine is under low speed and low load conditions, the vacuum pump of the crankcase forced ventilation system is shut off.

[0021] When the engine is under heavy load, the vacuum pump is controlled to rotate at its rated speed, thereby creating a negative pressure inside the crankcase by pumping air from the vacuum pump. The rated speed of the vacuum pump is obtained based on the current speed of the engine.

[0022] In the scheme disclosed herein, when the engine is under low-speed, low-load conditions, the throttle opening is small, the pressure in the intake manifold is low, while the pressure in the crankcase is relatively high. Therefore, the first PCV valve can be opened. Exhaust gas in the crankcase can re-enter the cylinder for combustion through the first ventilation pipe and the intake manifold, while simultaneously reducing the pressure in the crankcase.

[0023] When the engine is under low-speed, high-load conditions, the throttle opening is large, and the pressure in the intake manifold is high. The pressure in the crankcase is insufficient to open the first PCV valve, so the first PCV valve is closed. At this time, the control vacuum pump is activated, which draws exhaust gas through the second ventilation pipe to the pipe between the turbocharger and the air filter. This allows the exhaust gas in the crankcase to re-enter the cylinders for combustion through the second ventilation pipe, turbocharger, throttle, and intake manifold, while simultaneously reducing the pressure in the crankcase.

[0024] When the engine is under high-speed, high-load conditions, the large intake volume of the intake system results in significant pressure loss in the pipes after the air filter, leading to lower pressure at the interface between the second end of the second ventilation pipe and the pipe between the turbocharger and the air filter. Consequently, exhaust gases from the crankcase can enter the pipe between the turbocharger and air filter 11 via the second ventilation pipe. Thus, the exhaust gases from the crankcase can re-enter the cylinders for combustion via the second ventilation pipe, turbocharger, throttle body, and intake manifold, simultaneously reducing the pressure within the crankcase. At this time, there is no need to activate the vacuum pump 31, resulting in energy savings.

[0025] Therefore, under various operating conditions, the crankcase pressure is kept low while the exhaust gas in the crankcase circulates smoothly. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 is a schematic diagram of a crankcase forced ventilation system under low-speed, low-load conditions according to an embodiment of the present disclosure.

[0028] Figure 2 is a schematic diagram of a crankcase forced ventilation system under high load conditions according to an embodiment of the present disclosure.

[0029] Figure 3 is a schematic diagram of a crankcase forced ventilation system with a make-up air branch and under high load conditions provided in an embodiment of this disclosure.

[0030] Explanation of reference numerals in the attached diagram: 1. Intake system; 11. Air filter; 12. Turbocharger; 121. Turbocharger blow-by passage; 13. Throttle valve; 14. Intake manifold; 2. First ventilation pipe; 21. First PCV valve; 22. First oil-gas separator; 3. Second ventilation pipe; 31. Vacuum pump; 32. Second oil-gas separator; 4. Cylinder; 41. Piston; 42. Cylinder head intake manifold; 5. Crankcase; 6. Injection air branch; 61. Second PCV valve; 7. Engine; 8. ECU. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this disclosure clearer, the embodiments of this disclosure will be described in further detail below with reference to the accompanying drawings.

[0032] In the first aspect, this embodiment relates to a crankcase forced ventilation system. Figure 1 shows a schematic diagram of the crankcase forced ventilation system under low speed and low load conditions, Figure 2 shows a schematic diagram of the crankcase forced ventilation system under high load conditions, and Figure 3 shows a schematic diagram of the crankcase forced ventilation system having a supplementary air branch 6 under high load conditions.

[0033] Referring to Figure 1, the crankcase forced ventilation system includes an intake system 1 for the engine 7, a first ventilation pipe 2, and a second ventilation pipe 3. The intake system 1 includes an air filter 11, a turbocharger 12, a throttle valve 13, and an intake manifold 14, which are connected sequentially via pipes and are connected to the cylinders 4 of the engine 7 via the intake manifold 14. For example, the intake manifold 14 can be connected to the cylinder head intake passage 42 of the cylinder 4, thereby allowing gas from the intake manifold 14 to be introduced into the combustion chamber of the cylinder 4 for combustion.

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

[0035] The first end of the second ventilation duct 3 is connected to the crankcase 5, and the second end of the second ventilation duct 3 is connected to the duct between the turbocharger 12 and the air filter 11. The second ventilation duct 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 duct 3 to the second end of the second ventilation duct 3.

[0036] As described above, referring to Figure 1, when the engine 7 is under low speed and low load conditions, the throttle valve 13 has a smaller opening, the pressure in the intake manifold 14 is lower, while the pressure in the crankcase 5 is relatively higher. Therefore, the first PCV valve 21 can be opened. The exhaust gas in the crankcase 5 can re-enter the cylinder 4 for combustion through the first ventilation pipe 2 and the intake manifold 14, while simultaneously reducing the pressure in the crankcase 5.

[0037] Referring to Figure 2, when the engine 7 is under low-speed, high-load conditions, the throttle valve 13 is open more, the pressure in the intake manifold 14 is higher, and the pressure in the crankcase 5 is insufficient to open the first PCV valve, thus the first PCV valve 21 is closed. At this time, the control vacuum pump 31 is turned on, which can draw exhaust gas through the second ventilation pipe 3 into the pipe between the turbocharger 12 and the air filter 11, so that the exhaust gas in the crankcase 5 can re-enter the cylinder 4 for combustion through the second ventilation pipe 3, the turbocharger 12, the throttle valve 13, and the intake manifold 14, while reducing the pressure in the crankcase 5.

[0038] Referring again to Figure 2, when the engine is under high-speed, high-load conditions, due to the large intake volume of the intake system 1, the pressure loss in the pipe after the air filter 11 is significant, resulting in lower pressure at the interface between the second end of the second ventilation pipe 3 and the pipe between the turbocharger 12 and the air filter 11. Therefore, exhaust gas in the crankcase 5 can enter the pipe between the turbocharger 12 and the air filter 11 via the second ventilation pipe 3. Consequently, the exhaust gas in the crankcase 5 can re-enter the cylinder 4 for combustion via the second ventilation pipe 3, the turbocharger 12, the throttle valve 13, and the intake manifold 14, while simultaneously reducing the pressure within the crankcase 5. At this time, there is no need to activate the vacuum pump 31, achieving an energy-saving effect.

[0039] Therefore, under various operating conditions, the engine 7 can ensure that the pressure in the crankcase 5 is low while allowing the exhaust gas in the crankcase 5 to circulate smoothly.

[0040] It should be noted that the criteria for determining the above high-speed, high-load operating conditions can be set by the vehicle manufacturer during the design phase based on calibration conditions. For example, the calibration conditions can be set as high speed when the engine speed of engine 7 is not lower than 2800 r / min, and high load when the turbocharger 12 is engaged. Of course, the above conditions can be adjusted in actual implementation. Correspondingly, when the engine speed is lower than 2800 r / min, engine 7 is in a low-speed operating condition, and when the turbocharger 12 is engaged, engine 7 is in a low-load operating condition.

[0041] In one example, continuing to refer to Figure 2, the first ventilation duct 2 also has a first oil-gas separator 22, which 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 pipe 2, the first oil-gas separator 22 can separate the engine oil from the exhaust gas and guide the engine oil into the oil pan of the crankcase 5, thereby reducing oil consumption. At the same time, it can also reduce the possibility of blockage of the first PCV valve 21, thus facilitating the smooth circulation of exhaust gas in the crankcase 5 when the engine 7 is under low speed and low load conditions.

[0043] In one example, continuing to refer to Figure 3, the crankcase forced ventilation system further includes a make-up air branch 6, the first end of which is connected to a pipe in the intake system 1. For example, in Figure 3, the first end of the make-up air branch 6 is connected to the intake manifold 14, but the first end of the make-up air branch 6 may also be connected to a pipe between the turbocharger 12 and the throttle valve 13, or alternatively, the first end of the make-up air branch 6 may also be connected to a pipe between the air filter 11 and the turbocharger 12.

[0044] Furthermore, 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 it can be indirectly connected to the crankcase 5 through other components connected to the crankcase 8. The air supply branch 6 has a second PCV valve 61, and when the second PCV valve 61 is open, gas flows from the first end of the air supply branch 6 to the second end of the air supply branch 6.

[0045] Thus, continuing to refer to Figure 1, when the engine 7 is under low speed and low load conditions, due to the low pressure in the intake manifold 14, the first PCV valve 21 opens while the second PCV valve 61 closes, allowing the exhaust gas in the crankcase 5 to enter the intake manifold 14 through the first ventilation pipe 2, reducing the pressure in the crankcase 5. At the same time, since the second ventilation pipe 3 is normally open when the vacuum pump 31 is off, fresh air can enter the crankcase 5 through the air filter 11 and the second ventilation pipe 3 to replenish the air inside the crankcase 5.

[0046] Referring again to Figure 3, when the engine 7 is under low-speed, high-load conditions, the vacuum pump 31 is activated, causing a decrease in pressure inside the crankcase 5, while the intake manifold 14 has a higher pressure. Therefore, the first PCV valve 21 is shut off, 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 via the air filter 11, turbocharger 12, and throttle valve 13 can enter the crankcase 5 through the air supply branch 6, replenishing the air supply inside the crankcase 5.

[0047] When engine 7 is under high-speed, high-load conditions, due to the large intake volume of intake system 1, the pressure loss in the pipe after air filter 11 is large. This results in the pressure at the pipe interface between the second end of the second ventilation pipe 3 and the turbocharger 12 and air filter 11 being lower than the pressure inside crankcase 5, allowing exhaust gas in crankcase 5 to be discharged through the second ventilation pipe 3. Simultaneously, due to the high pressure in intake manifold 14, the first PCV valve 21 is closed, while the second PCV valve 61 is open, allowing gas in intake manifold 14 to enter crankcase 5 for replenishment.

[0048] However, at this time, the speed at which the exhaust gas in crankcase 5 exits from the second ventilation pipe 3 may be similar to, or even less than, the speed at which the gas in intake manifold 14 enters crankcase 5. This makes it difficult to reduce or even increase the pressure inside crankcase 5. Therefore, when engine 7 is under high-speed, high-load conditions, vacuum pump 31 can be activated. This can reduce the pressure inside crankcase 5 on the one hand, and increase the speed at which fresh air enters crankcase 5 for replenishment on the other.

[0049] As described above, the crankcase can be replenished with fresh air under various operating conditions, thereby accelerating the removal of exhaust gas from the crankcase 5. This helps extend the service life of the engine oil, prevents oil circuit blockage, reduces condensation, and avoids problems such as corrosion and accelerated wear of engine parts.

[0050] Among them, a small amount of exhaust gas passing through the first ventilation duct 2 and filtered by the first oil-gas separator 22 may enter the crankcase 5 along with fresh air. However, since the amount of this exhaust gas is much 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 supplemental air branch 6 is connected to the pipeline between the turbocharger 12 and the cylinder 4.

[0052] For example, as shown in Figure 3, the first end of the supplemental air branch 6 can be connected to the intake manifold 14, or the first end of the supplemental air branch 6 can also be connected to the intake manifold 14, and the pipeline between the turbocharger 12 and the throttle valve 13 is connected.

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

[0054] In one example, referring to Figures 2 and 3, the second ventilation duct 3 also has a second oil-gas separator 32, which is located between the crankcase 5 and the vacuum pump 31.

[0055] In this way, when the exhaust gas passes through the second ventilation duct 3, the second oil-gas separator 32 can separate the engine oil from the exhaust gas and guide the engine oil into the oil pan of the crankcase 5, thereby reducing engine oil consumption. At the same time, it can also avoid or reduce the potential wear and tear on the vacuum pump 31 caused by engine oil.

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

[0057] For example, with the turbocharger 12 on, experiments can be conducted to determine the first operating speed of the engine 7 when the vacuum pump 3 is off and the crankcase 5 is under negative pressure, and the second operating speed when the crankcase 5 is under positive pressure. Then, with the engine 7 operating at the second speed, experiments can be conducted to determine the calibrated speed of the vacuum pump 3 when the crankcase 5 is maintained within the working negative pressure range. The working negative pressure range can be from -5.1 kPa to -0.25 kPa.

[0058] Thus, when ECU8 detects that the turbocharger 12 is off, ECU8 can control the vacuum pump 31 to shut down. When ECU8 detects that the turbocharger 12 is on and the current speed of engine 7 is the first operating speed, ECU8 can control the vacuum pump 31 to shut down. When ECU8 detects that the turbocharger 12 is on and the current speed of engine 7 is the second operating speed, the vacuum pump 31 starts and operates at the calibrated speed.

[0059] Therefore, the operation of the vacuum pump 3 can be conveniently and instantly controlled through the ECU8, and energy saving can be achieved while maintaining a negative pressure state inside the crankcase 5.

[0060] In one example, since the turbocharger 12 may generate polluting exhaust gases during operation, to prevent these exhaust gases from polluting the engine compartment and the atmosphere, the crankcase forced ventilation system also includes a turbocharger blow-by passage 121, which is adapted to connect the crankcase 5 and the turbocharger 12. Thus, blow-by gases from the turbocharger 12 can be introduced into the crankcase 5 through the turbocharger blow-by passage 121 and recycled into the engine intake system 1 along with the exhaust gases in the crankcase 5.

[0061] In a second aspect, the present disclosure also provides an engine, which includes a cylinder 4, a crankcase 5, and a crankcase forced ventilation system as described in any of the first aspects. The cylinder 4 is connected to the intake manifold 14 of the crankcase forced ventilation system, and the first end of the first ventilation pipe 2 and the first end of the second ventilation pipe 3 of the crankcase forced ventilation system are both connected to the crankcase 5.

[0062] The engine in this embodiment uses the crankcase forced ventilation system of this application, and has all the beneficial technical effects of the embodiments of the first aspect of this application.

[0063] Thirdly, embodiments of this disclosure also provide a vehicle, which includes an engine 7 as described in the second aspect.

[0064] The vehicle in this embodiment uses the engine of this application and has all the beneficial technical effects of the embodiments of the second aspect of this application.

[0065] Fourthly, embodiments of this disclosure also provide a control method for a crankcase forced ventilation system. This control method is used to control a crankcase forced ventilation system as described in any of the first aspects, and includes:

[0066] When the engine 7 is operating at low speed and low load, the vacuum pump 31 of the crankcase forced ventilation system is shut off.

[0067] When the engine 7 is under heavy load, the vacuum pump 31 is controlled to rotate at its rated speed, thereby making the internal pressure of the crankcase 5 negative by the vacuum pump 31. The rated speed of the vacuum pump 31 is obtained based on the current speed of the engine 7.

[0068] For example, with the turbocharger 12 on, experiments can be conducted to determine the first operating speed of the engine 7 when the vacuum pump 3 is off and the crankcase 5 is under negative pressure, and the second operating speed when the crankcase 5 is under positive pressure. Then, with the engine 7 operating at the second speed, experiments can be conducted to determine the calibrated speed of the vacuum pump 3 when the crankcase 5 is maintained within the working negative pressure range. The working negative pressure range can be from -5.1 kPa to -0.25 kPa.

[0069] Thus, when ECU8 detects that the turbocharger 12 is off, ECU8 can control the vacuum pump 31 to shut down. When ECU8 detects that the turbocharger 12 is on and the current speed of engine 7 is the first operating speed, ECU8 can control the vacuum pump 31 to shut down, i.e., the rated speed of vacuum pump 31 is zero. When ECU8 detects that the turbocharger 12 is on and the current speed of engine 7 is the second operating speed, vacuum pump 31 starts and operates at a rated speed greater than zero.

[0070] Therefore, the operation of the vacuum pump 3 can be conveniently and instantly controlled through the ECU8, and energy saving can be achieved while maintaining a negative pressure state inside the crankcase 5.

[0071] In this embodiment, when the engine 7 is operating at low speed and low load, the throttle valve 13 has a smaller opening, the pressure in the intake manifold 14 is lower, while the pressure in the crankcase 5 is relatively higher. Therefore, the first PCV valve 21 can be opened. The exhaust gas in the crankcase 5 can re-enter the cylinder 4 for combustion via the first ventilation pipe 2 and the intake manifold 14, while simultaneously reducing the pressure in the crankcase 5.

[0072] When engine 7 is under low-speed, high-load conditions, the throttle valve 13 is open more, and the pressure in the intake manifold 14 is higher. 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 control vacuum pump 31 is turned on, which can draw exhaust gas through the second ventilation pipe 3 to the pipe between the turbocharger 12 and the air filter 11. This allows the exhaust gas in the crankcase 5 to re-enter the cylinder 4 for combustion through the second ventilation pipe 3, the turbocharger 12, the throttle valve 13, and the intake manifold 14, while simultaneously reducing the pressure in the crankcase 5.

[0073] When the engine is under high-speed, high-load conditions, due to the large intake volume of the intake system 1, the pressure loss in the pipe after the air filter 11 is significant, resulting in lower pressure at the interface between the second end of the second ventilation pipe 3 and the pipe between the turbocharger 12 and the air filter 11. Therefore, exhaust gas from the crankcase 5 may enter the pipe between the turbocharger 12 and the air filter 11 via the second ventilation pipe 3. Consequently, the exhaust gas from the crankcase 5 can re-enter the cylinder 4 for combustion via the second ventilation pipe 3, the turbocharger 12, the throttle valve 13, and the intake manifold 14, simultaneously reducing the pressure within the crankcase 5. At this time, there is no need to activate the vacuum pump 31, thus achieving energy savings.

[0074] Therefore, under various operating conditions, the engine 7 can ensure that the pressure in the crankcase 5 is low while allowing the exhaust gas in the crankcase 5 to circulate smoothly.

[0075] It should be noted that the terms "first," "second," etc., used in the specification and claims of this disclosure are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this disclosure can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class, and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0076] The above are merely preferred embodiments of this disclosure and are not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A crankcase forced ventilation system, wherein, The crankcase forced ventilation system includes an intake system (1) of the engine (7), a first ventilation duct (2) and a second ventilation duct (3); The intake system (1) includes an air filter (11), a turbocharger (12), a throttle valve (13) and an intake manifold (14) connected in sequence through a pipeline, and is connected to the cylinder (4) of the engine (7) through the intake manifold (14); The first end of the first ventilation duct (2) is connected to the crankcase (5), and the second end of the first ventilation duct (2) is connected to the intake manifold (14). The first ventilation duct (2) has a first crankcase forced ventilation PCV valve (21), and when the first PCV valve (21) is open, gas flows from the first end of the first ventilation duct (2) to the second end of the first ventilation duct (2). The first end of the second ventilation duct (3) is connected to the crankcase (5), and the second end of the second ventilation duct (3) is connected to the duct between the supercharger (12) and the air filter (11). The second ventilation duct (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 duct (3) to the second end of the second ventilation duct (3).

2. The crankcase forced ventilation system according to claim 1, wherein, The first ventilation duct (2) also includes a first oil-gas separator (22), which is located between the crankcase (5) and the first PCV valve (21).

3. The crankcase forced ventilation system according to claim 2, wherein, The crankcase forced ventilation system also includes a make-up air branch (6), the first end of which is connected to the pipeline in the intake system (1), the second end of which is connected to the crankcase (5), the make-up air branch (6) has a second PCV valve (61), and when the second PCV valve (61) is open, gas flows from the first end of the make-up air branch (6) to the second end of the make-up air branch (6).

4. The crankcase forced ventilation system according to claim 3, wherein, The first end of the supplementary air branch (6) is connected to the pipeline between the booster (12) and the cylinder (4).

5. The crankcase forced ventilation system according to claim 1, wherein, The second ventilation duct (3) also includes a second oil-gas separator (32), which is located between the crankcase (5) and the vacuum pump (31).

6. The crankcase forced ventilation system according to claim 1, wherein, 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). The ECU (8) is used to monitor the operating status 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 status of the supercharger (12) and the current speed of the engine (7).

7. The crankcase forced ventilation system according to claim 1, wherein, The crankcase forced ventilation system also includes a turbocharger blow-by passage (121), which is adapted to connect the crankcase (5) and the turbocharger (12).

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

9. A vehicle, wherein, The vehicle includes the engine (7) as described in claim 8.

10. A control method for a crankcase forced ventilation system, wherein, The control method for the crankcase forced ventilation system is used to control the crankcase forced ventilation system as described in any one of claims 1 to 7, and includes: When the engine (7) is in a low-speed, low-load condition, the vacuum pump (31) of the crankcase forced ventilation system is turned off. When the engine (7) is under heavy load, the vacuum pump (31) is controlled to rotate at the rated speed of the vacuum pump (31), so that the internal pressure of the crankcase (5) is negative by the pumping 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).