Closed-loop crankcase ventilation system and control method for gas fuel internal combustion engine

Abstract

The present invention relates to an engine crankcase, an engine control module, an oil-gas separator, an air control valve, an oil return pipeline, an air line pipe, a fuel concentration sensor, a pressure sensor, and a wiring harness; the fuel concentration sensor is installed on the engine crankcase and is electrically coupled to the engine control module through the wiring harness; the pressure sensor is installed on the engine crankcase and is electrically coupled to the engine control module through the wiring harness; the air inlet end of the air control valve is connected to the air outlet end of the oil-gas separator through the air line pipe; the air outlet end of the air control valve is connected to the air inlet end of the engine crankcase through the air line pipe; the air control valve is electrically coupled to the engine control module through the wiring harness. The present invention also relates to a control method for a closed-loop crankcase ventilation system of a gas fuel internal combustion engine. The present invention prevents the emulsification of engine oil, ensures that the negative pressure in the crankcase meets regulatory requirements, improves the safety of the engine, and realizes the recycling of exhaust fuel.

Description

Technical Field

[0001] The present invention relates to the technical field of internal combustion engines, and in particular to a closed-loop crankcase ventilation system and a control method for a gas fuel internal combustion engine. Background Art

[0002] As the earth's oil reserves are becoming less and less, and the cost of fuel is getting higher and higher, the development of gas fuel internal combustion engines is an inevitable trend. In order to ensure that the friction moving pair can be effectively lubricated, there is a certain gap between the high-speed reciprocating piston and the cylinder liner. Therefore, during the operation of the engine, the high-pressure and high-temperature mixed gas in the cylinder will continuously leak into the crankcase through this gap, causing the pressure in the crankcase to continue to increase. The components of blowby gas are mainly unburned gas fuel, water vapor and exhaust gas.

[0003] The defects of the prior art are:

[0004] In the prior art, unburned gaseous fuel, water vapor and exhaust gas blowby into the crankcase may cause excessive concentration of gaseous fuel in the crankcase to cause deflagration, deteriorate the engine oil, and accelerate the wear of the moving parts of the engine. Summary of the invention

[0005] In view of the above problems, the present invention provides a closed-loop crankcase ventilation system and control method for a gas fuel internal combustion engine, the purpose of which is to prevent oil emulsification, ensure that the negative pressure in the crankcase meets regulatory requirements, improve the safety of the engine, and realize the recycling of exhaust fuel.

[0006] To solve the above problems, the technical solution provided by the present invention is:

[0007] A closed-loop crankcase ventilation system for a gas fuel internal combustion engine, comprising an engine crankcase, an engine control module, an oil-gas separator, an air control valve, an oil return line, an air line pipe, a fuel concentration sensor, a pressure sensor, and a wiring harness, wherein:

[0008] The fuel concentration sensor is mounted on the engine crankcase and is electrically coupled to the engine control module through the wiring harness; the pressure sensor is mounted on the engine crankcase and is electrically coupled to the engine control module through the wiring harness; the air inlet end of the air control valve is connected to the air outlet end of the oil-gas separator through the air line pipe; the air outlet end of the air control valve is connected to the air inlet end of the engine crankcase through the air line pipe; the air control valve is electrically coupled to the engine control module through the wiring harness;

[0009] The air inlet end of the oil-gas separator is connected to the air outlet end of the engine crankcase through the air pipe; the oil outlet end of the oil-gas separator is connected to the engine crankcase through the oil return line; the oil-gas separator is electrically signal coupled to the engine control module through the wiring harness.

[0010] Preferably, a pre-separator for intercepting large oil droplets in the mixed gas is provided on the gas line between the gas outlet end of the engine crankcase and the gas inlet end of the oil-gas separator; the pre-separator is a pipeline structure with a baffle provided inside.

[0011] Preferably, the blades of the oil-gas separator are of a centrifugal structure; the oil-gas separator is used to separate the small oil droplets and gas in the mixed gas.

[0012] Preferably, the oil return pipeline is a one-way oil return pipeline structure installed with a one-way valve; the one-way oil return pipeline structure is used to return the oil separated by the oil-gas separator to the oil pan through the oil return pipeline and prevent the oil in the oil pan from flowing back.

[0013] Preferably, a supercharger is installed on the air pipe between the air outlet end of the oil-gas separator and the air inlet end of the air control valve, and the supercharger compresses the incoming air to increase the intake pressure.

[0014] Preferably, an intercooler is installed on the air circuit pipe between the supercharger and the air inlet end of the air control valve, and the intercooler cools the compressed high-temperature gas; the outlet end of the intercooler is respectively connected to the air inlet end of the air control valve and the air inlet end of the engine crankcase.

[0015] Preferably, the air control valve is an electrically controlled ball valve switch structure.

[0016] A control method for a closed-loop crankcase ventilation system of a gas fuel internal combustion engine using the above-described method comprises the following steps:

[0017] S100. The pressure sensor monitors the crankcase pressure of the engine crankcase in real time, and transmits the crankcase pressure to the engine control module through the wiring harness; the fuel concentration sensor monitors the fuel concentration of the engine crankcase in real time, and transmits the fuel concentration to the engine control module through the wiring harness;

[0018] S200. The engine intake pressure sensor monitors the engine intake pressure in real time and transmits the engine intake pressure to the engine control module;

[0019] S300. The engine control module analyzes and processes the crankcase pressure and the fuel concentration transmitted in real time by the pressure sensor and the fuel concentration sensor in combination with the engine intake pressure data, and then generates corresponding control signals according to manually preset control rules, and transmits the control signals to the air control valve and the oil-gas separator respectively;

[0020] S400. The air control valve controls the opening of the valve ball inside the air control valve according to the control signal transmitted from the engine control module, thereby controlling the amount of air entering the engine crankcase;

[0021] S500. The oil-gas separator controls the rotation speed of the oil-gas separator according to the control signal transmitted from the engine control module, thereby controlling the crankcase pressure in the engine crankcase.

[0022] Preferably, the control rules specifically include the following contents:

[0023] When the gas fuel concentration monitored by the fuel concentration sensor is greater than or equal to a manually preset fuel concentration threshold, the engine control module sends the control signal to control the air control valve to be fully opened, thereby controlling the oil-gas separator to work at full load;

[0024] When the gas fuel concentration monitored by the fuel concentration sensor is less than the manually preset fuel concentration threshold, it is determined whether the oil-gas separator has reached the manually preset judgment standard that the pressure regulation requirement in the engine crankcase cannot be met, and then the following operations are performed according to the judgment result:

[0025] If the oil-gas separator does not meet the judgment standard that the pressure regulation requirement cannot be met, the air control valve is controlled to open; the opening of the air control valve is controlled according to the manually preset valve adjustment table, and the speed adjustment amount of the oil-gas separator is controlled according to the manually preset speed adjustment coefficient table and speed adjustment table, so as to control the current crankcase pressure to approach the manually preset target pressure;

[0026] If the oil-gas separator reaches the judgment standard that the pressure regulation requirement cannot be met, the air control valve is controlled to be closed, and then the crankcase pressure is adjusted until the oil-gas separator can meet the judgment standard that the pressure regulation requirement cannot be met.

[0027] Preferably, the judgment criterion that the pressure regulation requirement cannot be met is expressed as follows:

[0028] (N=N max )∩(ΔP>0)

[0029] Wherein: N is used to represent the current actual speed of the oil-gas separator; N max It is used to characterize the maximum rotation speed of the oil-gas separator; ΔP is used to characterize the pressure difference;

[0030] The target pressure is expressed as follows:

[0031] P2=P1-ΔP

[0032] Wherein: P2 is used to represent the target pressure; P1 is used to represent the current crankcase pressure;

[0033] The speed adjustment amount is expressed as follows:

[0034]

[0035] Wherein: ΔN is used to characterize the speed adjustment amount; N2 is used to characterize the target speed; λ is used to characterize the speed adjustment coefficient.

[0036] Compared with the prior art, the present invention has the following advantages:

[0037] 1. Since the present invention relies on sensors and electronic control modules, the blowing and suction volumes in the crankcase are controlled simultaneously through the electronic control module, and the pre-separator, oil-water separator and air switch valve are used to dilute the gas fuel concentration in the crankcase and take away the mixed gas in the crankcase, and at the same time, the mixed gas is separated from the oil and gas, so that the engine oil in the mixed gas returns to the oil pan and the gas fuel returns to the intake pipe at the front end of the supercharger, thereby preventing the engine oil from emulsifying and ensuring that the negative pressure in the crankcase meets regulatory requirements.

[0038] 2. Since the present invention prevents abnormal combustion of gas fuel in the crankcase, the safety of the engine is improved and the recycling of exhaust fuel is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a structural schematic diagram of a closed-loop crankcase ventilation system of a gas fuel internal combustion engine according to a specific embodiment of the present invention;

[0040] Figure 2 A schematic diagram of a system control flow chart of a specific embodiment of the present invention;

[0041] Figure 3 A schematic diagram of the speed regulation of a specific embodiment of the present invention;

[0042] Figure 4 It is a schematic diagram of the speed adjustment coefficient of a specific embodiment of the present invention;

[0043] Figure 5 A schematic diagram of a valve adjustment diagram of a specific embodiment of the present invention is shown.

[0044] Among them: 1. Engine crankcase, 2. Engine control module, 3. Oil-gas separator, 4. Air control valve, 5. Oil return line, 6. Air line pipe, 7. Fuel concentration sensor, 8. Pressure sensor, 9. Wiring harness, 10. Pre-separator, 11. Check valve, 12. Supercharger, 13. Intercooler DETAILED DESCRIPTION

[0045] The present invention is further explained below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

[0046] like Figure 1 As shown, the closed-loop crankcase ventilation system of the gas fuel internal combustion engine includes an engine crankcase 1, an engine control module 2, an oil-gas separator 3, an air control valve 4, an oil return line 5, an air line pipe 6, a fuel concentration sensor 7, a pressure sensor 8, and a wiring harness 9, wherein:

[0047] The fuel concentration sensor 7 is installed on the engine crankcase 1 and is electrically coupled to the engine control module 2 through the wiring harness 9; the pressure sensor 8 is installed on the engine crankcase 1 and is electrically coupled to the engine control module 2 through the wiring harness 9; the air inlet end of the air control valve 4 is connected to the air outlet end of the oil-gas separator 3 through the air line pipe 6; the air outlet end of the air control valve 4 is connected to the air inlet end of the engine crankcase 1 through the air line pipe 6; the air control valve 4 is electrically coupled to the engine control module 2 through the wiring harness 9.

[0048] The air inlet end of the oil-gas separator 3 is connected to the air outlet end of the engine crankcase 1 through the air pipe 6; the oil outlet end of the oil-gas separator 3 is connected to the engine crankcase 1 through the oil return line 5; the oil-gas separator 3 is electrically coupled to the engine control module 2 through the wiring harness 9.

[0049] It should be noted that a pre-separator 10 for intercepting large oil droplets in the mixed gas is provided on the gas line pipe 6 between the gas outlet of the engine crankcase 1 and the gas inlet of the oil-gas separator 3; the pre-separator 10 is a pipeline structure with a baffle inside.

[0050] It should be further explained that the blades of the oil-gas separator 3 are of a centrifugal structure; the oil-gas separator 3 is used to separate the small oil droplets and gas in the mixed gas.

[0051] It should be noted that the oil return line 5 is a one-way oil return line structure equipped with a one-way valve 11; the one-way oil return line structure is used to return the oil separated by the oil-gas separator 3 to the oil pan through the oil return line 5 and prevent the oil in the oil pan from flowing back.

[0052] It should be noted that a supercharger 12 is installed on the air pipe 6 between the air outlet end of the oil-gas separator 3 and the air inlet end of the air control valve 4, and the supercharger compresses the incoming air to increase the intake pressure.

[0053] It should be further explained that the air pipe 6 between the outlet end of the oil-gas separator 3 and the inlet end of the air control valve 4 introduces the gas separated by the oil-gas separator 3 into the inlet of the supercharger 12 through the pipeline, thereby realizing exhaust gas recirculation and improving economy.

[0054] It should be further explained that an intercooler 13 is installed on the air circuit pipe 6 between the supercharger 12 and the air inlet end of the air control valve 4; the intercooler cools the compressed high-temperature gas; the outlet end of the intercooler 13 is connected to the air inlet end of the air control valve 4 and the air inlet end of the engine crankcase 1 respectively.

[0055] It should be further explained that the air control valve 4 is an electronically controlled ball valve switch structure. The control instruction of the engine control module 2 controls the ball valve opening of the air control valve 4, thereby controlling the ventilation volume of fresh air blown into the engine crankcase 1.

[0056] It should be noted that the working principle of the closed-loop crankcase ventilation system of the gas fuel internal combustion engine of the present invention is as follows: because there is a certain gap between the piston ring and the cylinder wall of the gas fuel engine, when the engine is started, a small amount of gas fuel and engine oil will inevitably leak from the gap between the piston ring and the cylinder wall to the engine crankcase 1; at the same time, because the crankshaft in the engine crankcase 1 rotates at high speed, it will throw out engine oil particles, etc.; so there will be gas fuel, small engine oil particles and aerosol mixed with the two in the engine crankcase 1. Therefore, when the engine is ignited, the pressure sensor 8 and the fuel concentration sensor 7 installed on the engine crankcase 1 of the engine will transmit the pressure value and gas concentration value of the engine crankcase 1 to the engine control module 2; after the engine control module 2 receives the pressure value and gas concentration value, it controls the opening of the air control valve 4 and the speed of the oil-gas separator 3, thereby controlling the air intake and air output of the engine crankcase 1, and then maintaining the low concentration and low negative pressure of the gas fuel in the crankcase, ensuring the safety of the engine and the emulsification of the engine oil.

[0057] like Figure 2 As shown, a control method for a closed-loop crankcase ventilation system of a gas fuel internal combustion engine comprises the following steps:

[0058] S100. The pressure sensor 8 monitors the crankcase pressure of the engine crankcase 1 in real time, and transmits the crankcase pressure to the engine control module 2 through the wiring harness 9; the fuel concentration sensor 7 monitors the fuel concentration of the engine crankcase 1 in real time, and transmits the fuel concentration to the engine control module 2 through the wiring harness 9.

[0059] S200. The engine intake pressure sensor monitors the engine intake pressure in real time and transmits the engine intake pressure to the engine control module 2.

[0060] S300. The engine control module 2 analyzes and processes the crankcase pressure and fuel concentration transmitted in real time by the pressure sensor 8 and the fuel concentration sensor 7 in combination with the engine intake pressure data, and then generates a corresponding control signal according to a manually preset control rule, and transmits the control signal to the air control valve 4 and the oil-gas separator 3 respectively.

[0061] S400. The air control valve 4 controls the opening of the valve ball inside the air control valve 4 according to the control signal transmitted from the engine control module 2, thereby controlling the amount of air entering the engine crankcase 1.

[0062] S500. The oil-gas separator 3 controls the speed of the oil-gas separator according to the control signal transmitted from the engine control module 2, thereby controlling the crankcase pressure in the engine crankcase 1.

[0063] It should be noted that the control rules specifically include the following:

[0064] When the gas fuel concentration monitored by the fuel concentration sensor 7 is greater than or equal to the manually preset fuel concentration threshold, the engine control module 2 sends a control signal to control the air control valve 4 to be fully opened, and controls the oil-gas separator 3 to work at full load, thereby ensuring that the gas concentration is quickly reduced to a normal level.

[0065] When the gas fuel concentration detected by the fuel concentration sensor 7 is less than the manually preset fuel concentration threshold, it is determined whether the oil-gas separator 3 has reached the manually preset judgment standard that the pressure regulation requirement in the engine crankcase 1 cannot be met, and then the following operations are performed according to the judgment result:

[0066] If the oil-gas separator 3 does not meet the judgment standard that the pressure regulation demand cannot be met, the air control valve 4 is controlled to open; the opening of the air control valve 4 is controlled according to the manually preset valve adjustment table, and the speed adjustment amount of the oil-gas separator 3 is controlled according to the manually preset speed adjustment coefficient table and speed adjustment table, so as to control the current crankcase pressure to approach the manually preset target pressure.

[0067] If the oil-gas separator 3 reaches the judgment standard that the pressure regulation demand cannot be met, the air control valve 4 is controlled to close, and then the crankcase pressure is adjusted until the oil-gas separator 3 can meet the judgment standard that the pressure regulation demand cannot be met.

[0068] It should be further explained that the judgment standard for the failure to meet the pressure regulation requirement is expressed as follows:

[0069] (N=Nmax )∩(ΔP>0) (1)

[0070] Wherein: N is used to represent the current actual speed of the oil-gas separator 3; N max It is used to characterize the maximum rotation speed of the oil-gas separator 3; ΔP is used to characterize the pressure difference.

[0071] The target pressure is expressed as follows:

[0072] P2=P1-ΔP (2)

[0073] Among them: P2 is used to represent the target pressure and is a fixed value; P1 is used to represent the current crankcase pressure.

[0074] The speed adjustment is expressed as follows:

[0075]

[0076] Among them: ΔN is used to represent the speed adjustment amount; N2 is used to represent the target speed; λ is used to represent the speed adjustment coefficient.

[0077] like Figure 3 As shown, it should be noted that the speed adjustment table is the speed adjustment amount of the oil-gas separator 3 under different pressure differences; the data is obtained by bench test calibration. The first column is the pressure difference, and the second column represents the speed adjustment amount of the oil-gas separator 3.

[0078] like Figure 4 As shown, it should be noted that the speed adjustment coefficient table contains the speed adjustment coefficient λ of the oil-gas separator 3 at different speeds; the data is obtained from the bench test. The first column represents the current actual speed, and the second column represents the speed adjustment coefficient.

[0079] like Figure 5 As shown, it should be noted that the valve adjustment table includes the required opening of the air control valve 4 corresponding to the pressure difference.

[0080] In the above detailed description, various features are grouped together in a single embodiment to simplify the disclosure. This method of disclosure should not be interpreted as reflecting an intention that the embodiments of the claimed subject matter require more features than are clearly stated in each claim. On the contrary, as reflected in the appended claims, the invention is in a state of having less than all the features of the disclosed individual embodiments. Therefore, the appended claims are hereby expressly incorporated into the detailed description, with each claim standing on its own as a separate preferred embodiment of the invention.

[0081] The disclosed embodiments are described above to enable any person skilled in the art to implement or use the present invention. Various modifications of these embodiments are obvious to those skilled in the art, and the general principles defined herein may also be applied to other embodiments without departing from the spirit and scope of the present disclosure. Therefore, the present disclosure is not limited to the embodiments given herein, but is consistent with the broadest scope of the principles and novel features disclosed in this application.

[0082] The above description includes examples of one or more embodiments. Of course, it is not possible to describe all possible combinations of components or methods for the purpose of describing the above embodiments, but it should be recognized by those skilled in the art that the various embodiments may be further combined and arranged. Therefore, the embodiments described herein are intended to cover all such changes, modifications and variations that fall within the scope of protection of the appended claims. In addition, with respect to the term "comprising" used in the specification or claims, the word is covered in a manner similar to the term "including", just as "including," is explained as a transitional word in the claims. In addition, any term "or" used in the specification of the claims is intended to mean "non-exclusive or".

[0083] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A closed-loop crankcase ventilation system for a gas fuel internal combustion engine, characterized in that: It comprises an engine crankcase (1), an engine control module (2), an oil-gas separator (3), an air control valve (4), an oil return pipeline (5), an air pipeline (6), a fuel concentration sensor (7), a pressure sensor (8), and a wiring harness (9), wherein: The fuel concentration sensor (7) is mounted on the engine crankcase (1) and is electrically signal coupled to the engine control module (2) through the wiring harness (9); the pressure sensor (8) is mounted on the engine crankcase (1) and is electrically signal coupled to the engine control module (2) through the wiring harness (9); the air inlet end of the air control valve (4) is connected to the air outlet end of the oil-gas separator (3) through the air line pipe (6); the air outlet end of the air control valve (4) is connected to the air inlet end of the engine crankcase (1) through the air line pipe (6); the air control valve (4) is electrically signal coupled to the engine control module (2) through the wiring harness (9); The air inlet end of the oil-gas separator (3) is connected to the air outlet end of the engine crankcase (1) through the air pipe (6); the oil outlet end of the oil-gas separator (3) is connected to the engine crankcase (1) through the oil return pipe (5); and the oil-gas separator (3) is electrically signal coupled to the engine control module (2) through the wiring harness (9).

2. The closed-loop crankcase ventilation system for a gas fuel internal combustion engine according to claim 1, characterized in that: A pre-separator (10) for intercepting large oil droplets in the mixed gas is provided on the gas line pipe (6) between the gas outlet end of the engine crankcase (1) and the gas inlet end of the oil-gas separator (3); the pre-separator (10) is a pipeline structure with a baffle plate inside.

3. The closed-loop crankcase ventilation system for a gas fuel internal combustion engine according to claim 2, characterized in that: The blades of the oil-gas separator (3) are of a centrifugal structure; the oil-gas separator (3) is used to separate small oil droplets and gas in the mixed gas.

4. The closed-loop crankcase ventilation system for a gas fuel internal combustion engine according to claim 3, characterized in that: The oil return pipeline (5) is a one-way oil return pipeline structure equipped with a one-way valve (11); the one-way oil return pipeline structure is used to return the engine oil separated by the oil-gas separator (3) to the oil pan through the oil return pipeline (5) and prevent the engine oil in the oil pan from flowing back.

5. The closed-loop crankcase ventilation system for a gas fuel internal combustion engine according to claim 4, characterized in that: A supercharger (12) is installed on the air circuit pipe (6) between the air outlet end of the oil-gas separator (3) and the air inlet end of the air control valve (4).

6. The closed-loop crankcase ventilation system for a gas fuel internal combustion engine according to claim 5, characterized in that: An intercooler (13) is installed on the air circuit pipe (6) between the supercharger (12) and the air inlet end of the air control valve (4); the air outlet end of the intercooler (13) is respectively connected to the air inlet end of the air control valve (4) and the air inlet end of the engine crankcase (1).

7. The closed-loop crankcase ventilation system for a gas fuel internal combustion engine according to claim 6, characterized in that: The air control valve (4) is an electrically controlled ball valve switch structure.

8. A method for controlling a closed-loop crankcase ventilation system of a gas fuel internal combustion engine using the method of claim 7, characterized in that: The following steps are involved: S100. The pressure sensor (8) monitors the crankcase pressure of the engine crankcase (1) in real time, and transmits the crankcase pressure to the engine control module (2) through the wiring harness (9); the fuel concentration sensor (7) monitors the fuel concentration of the engine crankcase (1) in real time, and transmits the fuel concentration to the engine control module (2) through the wiring harness (9); S200. The engine intake pressure sensor monitors the engine intake pressure in real time and transmits the engine intake pressure to the engine control module (2); S300. The engine control module (2) analyzes and processes the crankcase pressure and the fuel concentration transmitted in real time by the pressure sensor (8) and the fuel concentration sensor (7) in combination with the engine intake pressure data, and then generates a corresponding control signal according to a manually preset control rule, and transmits the control signal to the air control valve (4) and the oil-gas separator (3) respectively; S400. The air control valve (4) controls the opening of the valve ball inside the air control valve (4) according to the control signal transmitted by the engine control module (2), thereby controlling the amount of air entering the engine crankcase (1); S500. The oil-gas separator (3) controls the rotation speed of the oil-gas separator according to the control signal transmitted from the engine control module (2), thereby controlling the crankcase pressure in the engine crankcase (1).

9. The control method according to claim 8, characterized in that: The control rules specifically include the following contents: When the gas fuel concentration monitored by the fuel concentration sensor (7) is greater than or equal to a manually preset fuel concentration threshold, the engine control module (2) sends the control signal to control the air control valve (4) to be fully opened, thereby controlling the oil-gas separator (3) to work at full load; When the gas fuel concentration monitored by the fuel concentration sensor (7) is less than the manually preset fuel concentration threshold, it is determined whether the oil-gas separator (3) has reached a manually preset judgment standard that the pressure regulation requirement in the engine crankcase (1) cannot be met, and then the following operations are performed according to the judgment result: If the oil-gas separator (3) does not reach the judgment standard that the pressure regulation requirement cannot be met, the air control valve (4) is controlled to open; the opening of the air control valve (4) is controlled according to a manually preset valve adjustment table, and the speed adjustment amount of the oil-gas separator (3) is controlled according to a manually preset speed adjustment coefficient table and a speed adjustment table, thereby controlling the current crankcase pressure to approach the manually preset target pressure; If the oil-gas separator (3) reaches the judgment standard that the pressure regulation requirement cannot be met, the air control valve (4) is controlled to be closed, and the crankcase pressure is further adjusted until the oil-gas separator (3) can meet the judgment standard that the pressure regulation requirement cannot be met.

10. The control method according to claim 9, characterized in that: The judgment standard that the pressure regulation requirement cannot be met is expressed as follows: (N=N max )∩(ΔP>0) Wherein: N is used to represent the current actual rotation speed of the oil-gas separator (3); N max is used to characterize the maximum rotation speed of the oil-gas separator (3); ΔP is used to characterize the pressure difference; The target pressure is expressed as follows: P2=P1-ΔP Wherein: P2 is used to represent the target pressure; P1 is used to represent the current crankcase pressure; The speed adjustment amount is expressed as follows: Wherein: ΔN is used to characterize the speed adjustment amount; N2 is used to characterize the target speed; λ is used to characterize the speed adjustment coefficient.

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