CN219888126U

CN219888126U - Crankcase ventilation system, engine and vehicle

Info

Publication number: CN219888126U
Application number: CN202320781139.9U
Authority: CN
Inventors: 李政; 李菁; 张贵强
Original assignee: Beijing Chehejia Automobile Technology Co Ltd
Current assignee: Beijing Chehejia Automobile Technology Co Ltd
Priority date: 2023-04-10
Filing date: 2023-04-10
Publication date: 2023-10-24
Anticipated expiration: 2033-04-10

Abstract

The utility model discloses a crankcase ventilation system, an engine and a vehicle, wherein the crankcase ventilation system comprises an oil-gas separator, an air inlet assembly, a venturi gas channel, a fresh air channel, a first dirty air channel, a second dirty air channel and an engine oil return channel, one end of the air inlet assembly is communicated with the external environment, the other end of the air inlet assembly is communicated with a combustion chamber, one end of the venturi gas channel is communicated with the air inlet assembly, the other end of the venturi gas channel is communicated with a venturi injection valve, one end of the fresh air channel is communicated with the air inlet assembly, the other end of the fresh air channel is communicated with a crankcase, one end of the first dirty air channel is communicated with the oil-gas separator, the other end of the first dirty air channel is communicated with the combustion chamber, one end of the second dirty air channel is communicated with the air inlet assembly, and the other end of the second dirty air channel is communicated with the oil-gas separator. The crankcase ventilation system of the embodiment of the utility model introduces fresh air according to different engine working conditions to remove blowby gas.

Description

Crankcase ventilation system, engine and vehicle

Technical Field

The utility model relates to the technical field of internal combustion engines, in particular to a crankcase ventilation system, an engine and a vehicle.

Background

The crankcase of an engine is a relatively enclosed space, and during operation, the engine may generate a small amount of blow-by gas into the crankcase, which may cause a continuous increase in crankcase pressure and deterioration of engine oil, which may cause damage to the engine.

Different kinds of breathing systems in the related art have better effects under specific working conditions, but have poorer effects under other working conditions, for example, the deep breathing system mainly pumps the crankcase through a negative pressure source of an intake manifold, so that the crankcase forms negative pressure and then fresh air is introduced into the crankcase, and the pressure in the crankcase is positive pressure under the supercharging working condition because the gas pressure of the intake manifold can only form larger negative pressure under the working condition of natural inhalation and small load, so that fresh air cannot be introduced for cleaning the crankcase. Therefore, how to ensure that fresh air with proper flow rate can be introduced to remove blowby gas in the crankcase under any working condition is a key technical problem that needs to be solved by those skilled in the art.

Disclosure of Invention

The present utility model aims to solve at least one of the technical problems in the related art to some extent.

To this end, embodiments of the present utility model provide a crankcase ventilation system that can introduce a suitable flow of fresh air under any operating condition.

The embodiment of the utility model also provides an engine with the crankcase ventilation system.

The embodiment of the utility model also provides a vehicle with the engine.

The crankcase ventilation system comprises an oil-gas separator, an air inlet component, a venturi gas channel, a fresh air channel, a first dirty air channel, a second dirty air channel and an engine oil return channel, wherein a venturi injection valve is arranged on the oil-gas separator, one end of the air inlet component is communicated with the external environment, the other end of the air inlet component is communicated with a combustion chamber, one end of the venturi gas channel is communicated with the air inlet component, the other end of the venturi gas channel is communicated with the venturi injection valve, one end of the fresh air channel is communicated with the air inlet component, the other end of the fresh air channel is communicated with a crankcase, one end of the first dirty air channel is communicated with the oil-gas separator, the other end of the first dirty air channel is communicated with the combustion chamber, one end of the second dirty air channel is communicated with the air inlet component, the other end of the second dirty air channel is communicated with the oil-gas separator, one end of the engine oil return channel is communicated with the oil-gas separator, and the other end of the engine oil return channel is communicated with an oil pan.

According to the crankcase ventilation system provided by the embodiment of the utility model, through the combination of the Venturi gas channel, the fresh air channel, the first dirty air channel and the second dirty air channel, under a natural air suction working condition, fresh air can be introduced by utilizing negative pressure of an air inlet manifold, under a general supercharging working condition, fresh air can be introduced by utilizing negative pressure of a front supercharger generated by a Venturi injection valve, and under a high-speed supercharging working condition, fresh air is introduced by utilizing negative pressure generated by pressure difference of the front supercharger and the rear supercharger in an oil-gas separator, so that the negative pressure and forced full ventilation in a crankcase under all working conditions are realized, and therefore, proper fresh air is introduced into the crankcase, evaporation emission and engine oil leakage are reduced, and engine oil is kept clean under any conditions by utilizing fresh clean air, so that engine oil maintenance period is prolonged, and sludge and varnish deposition in the crankcase and a cover are reduced.

In some embodiments, the oil separator includes:

the first shell is provided with a coarse separation cavity, a fine separation cavity and a negative pressure cavity, the coarse separation cavity is internally provided with a coarse separation piece, the coarse separation cavity is communicated with the crankcase, the fine separation piece is arranged in the fine separation cavity, the fine separation cavity is communicated with the coarse separation cavity and the engine oil return channel, the fine separation cavity is also provided with a first throttling hole communicated with the first dirty air channel and a second throttling hole communicated with the negative pressure cavity, the negative pressure cavity is communicated with the second dirty air channel, and the venturi jet valve is arranged on the first shell;

a first check valve disposed at the first orifice and a second check valve disposed at the second orifice;

in some embodiments, the first orifice is one, and the diameter of the first orifice is 1.5-4 mm;

the number of the second orifices is multiple, the multiple second orifices are annularly arranged, and the diameter of each second orifice is 2-5 mm.

In some embodiments, the coarse separator comprises a plurality of corrugated baffles, the plurality of corrugated baffles being arranged within the coarse separator chamber to form a labyrinth structure;

the fine separation piece comprises a filter plate and a filter element which are mutually attached, and a filter hole is formed in the filter plate.

In some embodiments, the venturi injection valve comprises:

the second shell is provided with a nozzle, and the inner cavity of the second shell is communicated with the Venturi gas channel;

the valve core is movably arranged in the second shell;

one end of the pressure regulating spring is propped against the second shell, and the other end of the pressure regulating spring is propped against the valve core;

the external shrinkage tube, the one end of external shrinkage tube with negative pressure chamber intercommunication, the other end of external shrinkage tube with the dirty air passage intercommunication of second.

In some embodiments, the valve core comprises a small diameter section, a variable diameter section, a large diameter section and a tip which are connected in sequence, the cross sectional area of the variable diameter section gradually increases in the direction from the small diameter section to the large diameter section, the cross sectional areas of the small diameter section and the large diameter section are kept unchanged in the length direction, the small diameter section is positioned at one side adjacent to the nozzle, and the pressure regulating spring is propped against the tip.

In some embodiments, the air intake assembly comprises an air intake pipe and an air intake manifold, wherein the air intake pipe is provided with a filter, a supercharger, an intercooler and a throttle valve in sequence along the air intake direction, and the air intake manifold is communicated with the combustion chamber.

In some embodiments, the supercharger comprises a third housing and a vane rotatably disposed within the third housing, the second dirty air channel is connected to the third housing by a joint, and a distance between the joint and the vane is 50mm or less.

An engine according to a second aspect of the present utility model includes a crankcase ventilation system according to any of the above embodiments.

A vehicle according to an embodiment of a third aspect of the present utility model includes the engine according to the above embodiment.

Drawings

Fig. 1 is a schematic diagram of a crankcase ventilation system according to an embodiment of the utility model.

Fig. 2 is a schematic diagram of an oil separator of a crankcase ventilation system according to an embodiment of the utility model.

FIG. 3 is a schematic illustration of a venturi injection valve of a crankcase ventilation system according to an embodiment of the utility model.

Reference numerals:

1. an oil-gas separator; 11. a first housing; 12. a coarse separator; 13. a fine separator; 14. a first orifice; 15. a second orifice; 16. a first one-way valve; 17. a second one-way valve; 18. a venturi jet valve; 181. a second housing; 182. a valve core; 1821. a small diameter section; 1822. a reducing section; 1823. a large diameter section; 1824. an end head; 183. a pressure regulating spring; 184. an external shrinkage tube; 185. a nozzle; 21. an air inlet pipe; 22. an intake manifold; 23. a filter; 24. a supercharger; 25. an intercooler; 26. a throttle valve; 3. a venturi gas passage; 4. a fresh air channel; 5. a first dirty air channel; 6. a second dirty air duct; 7. an oil return passage; 8. a combustion chamber; 9. and a crankcase.

Detailed Description

Reference will now be made in detail to embodiments of the present utility model, examples of which are illustrated in the accompanying drawings. The embodiments described below by referring to the drawings are illustrative and intended to explain the present utility model and should not be construed as limiting the utility model.

As shown in fig. 1 to 3, the crankcase ventilation system according to the embodiment of the utility model includes an oil-gas separator 1, an air intake assembly, a venturi gas passage 3, a fresh air passage 4, a first dirty air passage 5, a second dirty air passage 6, and an oil return passage 7, wherein the fresh air passage 4, the first dirty air passage 5, and the oil return passage 7 may be directly formed on an engine, the fresh air passage 4 is used for circulating filtered clean air, the oil-gas separator 1 is used for oil-gas separation of blow-by gas in the crankcase 9, the venturi injection valve 18 is integrated on the oil-gas separator 1, the first dirty air passage 5 and the second dirty air passage 6 are used for circulating dirty air separated by the oil-gas separator 1, and the oil return passage is used for circulating engine oil separated by the oil-gas separator 1.

The air inlet assembly is used for providing air for the engine, the input end of the air inlet assembly is communicated with the external environment, the output end of the air inlet assembly is communicated with the combustion chamber 8, one end of the venturi gas channel 3 is communicated with the venturi injection valve 18, the other end of the venturi gas channel 3 is communicated with the air inlet assembly, one end of the fresh air channel 4 is communicated with the air inlet assembly, the other end of the fresh air channel 4 is communicated with the crankcase 9, one end of the first dirty air channel 5 is communicated with the oil-gas separator 1, the other end of the first dirty air channel 5 is communicated with the combustion chamber 8, one end of the second dirty air channel 6 is communicated with the air inlet assembly, the other end of the second dirty air channel 6 is communicated with the oil-gas separator 1, one end of the oil return channel 7 is communicated with the oil sump, check valves are arranged on the fresh air channel 4 and the oil return channel 7, and the check valves of the fresh air channel 4 can be integrated on the cover. It should be noted that the second dirty air duct 6 should be connected to the front end of the supercharger 24 of the intake assembly in the intake direction.

The crankcase ventilation system provided by the embodiment of the utility model can realize that proper fresh air is introduced into the crankcase 9 under negative pressure and forced full ventilation under all working conditions according to different engine working conditions, so that evaporation emission and engine oil leakage are reduced, and the working processes of the crankcase ventilation system of an engine under natural working conditions, general supercharging working conditions and high-speed supercharging working conditions are respectively described below.

Under the natural air suction working condition, the negative pressure of the air inlet manifold 22 in the air inlet assembly is larger, after the blowby gas in the crankcase 9 is separated by the oil-gas separator 1, the blowby gas enters the combustion chamber 8 through the first dirty air channel 5, fresh air is introduced into the crankcase 9 through the fresh air channel 4 to clean the blowby gas, the proportion of the fresh air and the blowby gas (generally designed value is 1:1-2:1) can be controlled by arranging an orifice and a throttle valve, and meanwhile, the pressure of the crankcase 9 can be controlled in a lower negative pressure range.

Under a general supercharging working condition, after the blowby gas in the crankcase 9 is separated through the oil-gas separator 1, a negative pressure source generated by the Venturi injection valve 18 is utilized, fresh air enters the air inlet assembly through the second dirty air channel 6, fresh air is introduced into the crankcase 9 through the fresh air channel 4 to clean the blowby gas, the flow rate of the fresh air is regulated through the valve core 182 specially designed for the Venturi injection valve 18, the ratio (general design value 1:1) of the fresh air to the blowby gas can be regulated through the setting of an orifice, and meanwhile, the pressure of the crankcase 9 can be controlled in a lower negative pressure range.

In the high-speed high-pressurization working condition, the venturi injection valve 18 is closed, the negative pressure source at the front end of the supercharger 24 is utilized, after the blowby gas in the crankcase 9 is separated through the oil-gas separator 1, the blowby gas enters the air inlet assembly through the second dirty air channel 6, fresh air is introduced into the crankcase 9 through the fresh air channel 4 to clean the blowby gas, a better fresh air and blowby gas proportion can be realized through the arrangement of the throttle hole, and meanwhile, the pressure of the crankcase 9 can be controlled in a lower negative pressure range.

According to the crankcase ventilation system provided by the embodiment of the utility model, according to different engine working conditions, negative pressure of the intake manifold 22, negative pressure before the supercharger 24 and pressure difference before and after the supercharger 24 are respectively utilized to generate negative pressure in the oil-gas separator 1, negative pressure and forced full ventilation in the crankcase 9 under all working conditions are realized, proper fresh air is introduced, evaporation emission and engine oil leakage are reduced, blowby gas, fuel oil steam, water vapor and oil mist are removed by utilizing fresh clean air, engine oil is kept clean under any condition, engine oil maintenance period is prolonged, and sludge and varnish deposition in the crankcase 9 and a cover are reduced.

As shown in fig. 2, in some embodiments, the oil separator 1 includes a first housing 11, a first check valve 16, a second check valve 17, and a venturi injection valve 18, the first housing 11 has a rough separation chamber, a fine separation chamber, and a negative pressure chamber, the rough separation chamber is provided with the rough separation member 12 therein, the rough separation chamber communicates with the crankcase 9, the fine separation chamber is provided with the fine separation member 13 therein, the fine separation chamber communicates with the rough separation chamber and the oil return passage 7, the fine separation chamber further has a first orifice 15 communicating with the first dirty air passage 5 and a second orifice 15 communicating with the negative pressure chamber, the negative pressure chamber communicates with the second dirty air passage 6, the first check valve 16 is provided at the first orifice 14, the second check valve 17 is provided at the second orifice 15, the venturi injection valve 18 is provided on the first housing 11, and the venturi injection valve 18 communicates with the venturi gas passage 3.

The blowby gas in the crankcase 9 is first subjected to rough separation in the rough separating member 12, then subjected to fine separation by the fine separator, the separated engine oil enters the oil pan through the engine oil return passage 7, and the gas can enter the first dirty air passage through the first throttle hole or enter the second dirty air passage 6 through the second throttle hole 15.

In some embodiments, the first check valve 16 and the second check valve 17 are both diaphragm rubber check valves, the air flow can only flow outwards from the oil-gas separator 1, the first throttle holes 14 are one, the diameter of the first throttle holes 14 is 1.5-4 mm, the second throttle holes 15 are a plurality of, the plurality of second throttle holes 15 are annularly arranged, and the diameter of the second throttle holes 15 is 2-5 mm, so that the flow requirement of the air can be met.

The first dirty air channel 5 is provided in the engine, and the separated gas passing through the first check valve 16 and the first orifice 14 in the gas-oil separator 1 enters the four combustion chambers 8 of the engine through the machined channels designed in the cover and the cylinder head, respectively. The first dirty air channel 5 is machined in the metal part in a built-in mode, the temperature of the engine is high during operation, and the problem of ventilation and icing can be effectively avoided. The diameters of the four channels designed on the cylinder cover are respectively adjusted and designed according to the flow requirements, so that the uniform flow resistance and uniform gas distribution are realized.

The fresh air channel 4 is likewise provided on the engine and the non-return valve of the fresh air channel 4 can be fitted to the cover, the fresh air channel 4 being integrated directly inside the cylinder head and the cylinder block. The joint of the check valve assembly is directly machined on the cover, and the machined hole on the cover can be designed into an orifice of 3-8 mm according to the system requirement.

The engine oil return channel 7 can be built-in on the cover, the cylinder cover and the cylinder body and reaches the oil pan after passing through the one-way valve, the engine oil return channel 7 can be arranged at the middle position of the engine, and the one-way valve on the engine oil return channel 7 can be arranged on the lower cylinder body so that the height of the oil return channel can achieve the highest designed height. The engine oil return device has the advantages that the engine can realize continuous engine oil return under different inclination angles and maximum ventilation flow, and the engine oil accumulation failure is avoided.

In some embodiments, the coarse separator 12 includes a plurality of corrugated baffles arranged in the coarse separator chamber to form a labyrinth structure, optionally, the height of the corrugated backflow plate is 3mm, and the corrugated baffles of the labyrinth structure can efficiently catch the impinging oil droplets and guide the oil droplets into the oil return chamber.

The fine separation piece 13 comprises a filter plate and a filter element which are mutually attached, wherein the filter plate is provided with filter holes, the diameter of the filter holes can be 2-4 mm, the number of the filter holes can be 6-12, the filter element can be made of felt, and the oil-gas separation effect is good.

As shown in fig. 3, in some embodiments, the venturi injection valve 18 includes a second housing 181, a valve core 182, a pressure regulating spring 183, and an external contraction tube 184, where a nozzle 185 is disposed on the second housing 181, an inner cavity of the second housing 181 is communicated with the venturi gas channel 3, the valve core 182 is slidably and movably disposed in the second housing 181 along an axial direction of the second housing 181, one end of the pressure regulating spring 183 abuts against the second housing 181, the other end of the pressure regulating spring 183 abuts against the valve core 182, one end of the external contraction tube 184 is communicated with the negative pressure cavity, and the other end of the external contraction tube 184 is communicated with the second dirty air channel 6.

The valve core 182 is made of solid plastic, and two end surfaces of the valve core 182 are respectively vulcanized by rubber, so that sealing can be realized when the valve core 182 moves to two ends of the second shell 181, and the valve core 182 pushes the pressure regulating spring 183 to regulate the flow according to the pressure difference and the flow of one side of the Venturi gas channel 3 and the side of the second dirty air pipe.

In some embodiments, the valve core 182 includes a small diameter section 1821, a variable diameter section 1822, a large diameter section 1823, and a tip 1824 connected in sequence, the cross-sectional area of the variable diameter section 1822 increases gradually in the direction of the small diameter section 1821 toward the large diameter section 1823, the cross-sectional areas of the small diameter section 1821 and the large diameter section 1823 remain unchanged in the length direction thereof, the small diameter section 1821 is located at a side adjacent to the nozzle 185, and the pressure regulating spring 183 abuts against the tip 1824.

So set up, the case 182 receives the pressure that the booster 24 applys, and when pressure is greater than the elasticity of pressure regulating spring 183, can move towards nozzle 185 one end, along with the gradual increase of pressure, the flow that passes through nozzle 185 remains unchanged earlier, then reduces gradually, when the case 182 is pushed to nozzle 185 one end by the completion, relies on vulcanized rubber to compress tightly with the sealing rib and realizes sealedly and closure.

As shown in fig. 1, in some embodiments, the air intake assembly includes an air intake pipe 21 and an air intake manifold 22, where a filter 23, a supercharger 24 and an intercooler 25 are sequentially arranged on the air intake pipe 21 along the air intake direction, the air intake manifold 22 is communicated with a plurality of combustion chambers 8 of the engine, the venturi air channel 3 is communicated with the intercooler 25, after the external air enters the air intake pipe 21, the external air is filtered by the filter 23, the filtered fresh air can enter the crankcase 9, or can be supercharged by the supercharger 24 to enter the intercooler 25, and finally enters the air intake manifold 22 through a throttle 26, and finally enters the combustion chambers 8 through an air passage.

In some embodiments, the supercharger 24 includes a third housing and vanes rotatably disposed within the third housing, the second dirty air channel 6 being connected to the third housing by a joint, and the distance between the joint and the vanes being 50mm or less. It should be noted that the joint should be provided at the front end of the third housing in the air flow direction, and the joint may be adjusted in angle by rotation, whereby the high temperature of the supercharger 24 can be utilized to effectively avoid the freezing of the ventilation air of the second dirty air channel 6. In addition, because the supercharger 24 can generate higher negative pressure (0 to minus 10 kPa) when the rotating speed is higher, the supercharger can be used as a negative pressure source of a crankcase ventilation system for helping to introduce fresh air when the high speed and the high load are carried out.

Technical advantages of the engine according to the second aspect of the present utility model and the vehicle according to the third aspect of the present utility model are the same as those of the crankcase ventilation system according to the above-described embodiments, and will not be described here again.

In the description of the present utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present utility model and simplifying the description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present utility model.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present utility model, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.

In the present utility model, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; may be mechanically connected, may be electrically connected or may be in communication with each other; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present utility model can be understood by those of ordinary skill in the art according to the specific circumstances.

In the present utility model, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.

For purposes of this disclosure, the terms "one embodiment," "some embodiments," "example," "a particular example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the utility model. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.

While the above embodiments have been shown and described, it should be understood that the above embodiments are illustrative and not to be construed as limiting the utility model, and that variations, modifications, alternatives, and variations of the above embodiments may be made by those of ordinary skill in the art without departing from the scope of the utility model.

Claims

1. A crankcase ventilation system, comprising:

the oil-gas separator (1), wherein a Venturi injection valve (18) is arranged on the oil-gas separator (1);

one end of the air inlet component is communicated with the external environment, and the other end of the air inlet component is communicated with the combustion chamber (8);

a venturi gas passage (3), one end of the venturi gas passage (3) is communicated with the air inlet assembly, and the other end of the venturi gas passage (3) is communicated with the venturi jet valve (18);

-a fresh air channel (4), one end of the fresh air channel (4) being in communication with the air intake assembly, the other end of the fresh air channel (4) being in communication with a crankcase (9);

a first dirty air channel (5), one end of the first dirty air channel (5) is communicated with the oil-gas separator (1), and the other end of the first dirty air channel (5) is communicated with a combustion chamber (8);

a second dirty air channel (6), wherein one end of the second dirty air channel (6) is communicated with the air inlet assembly, and the other end of the second dirty air channel (6) is communicated with the oil-gas separator (1);

and one end of the engine oil return channel (7) is communicated with the oil-gas separator (1), and the other end of the engine oil return channel (7) is communicated with the oil pan.

2. Crankcase ventilation system according to claim 1, characterized in that the oil separator (1) comprises:

a first housing (11), the first housing (11) having a coarse separation chamber, a fine separation chamber and a negative pressure chamber, the coarse separation chamber being provided with a coarse separation member (12) and communicating with the crankcase (9), the fine separation chamber being provided with a fine separation member (13) and communicating with the coarse separation chamber and the oil return passage (7), the fine separation chamber further having a first orifice (14) communicating with the first dirty air passage (5) and a second orifice (15) communicating with the negative pressure chamber and communicating with the second dirty air passage (6), the venturi jet valve (18) being provided on the first housing (11);

a first check valve (16) and a second check valve (17), the first check valve (16) being disposed at the first orifice (14), the second check valve (17) being disposed at the second orifice (15).

3. The crankcase ventilation system according to claim 2, wherein the first orifice (14) is one, and the diameter of the first orifice (14) is 1.5-4 mm;

the number of the second orifices (15) is multiple, the second orifices (15) are annularly arranged, and the diameter of the second orifices (15) is 2-5 mm.

4. The crankcase ventilation system according to claim 2, wherein the coarse separator (12) comprises a plurality of corrugated baffles arranged in the coarse separator chamber to form a labyrinth structure;

the fine separation piece (13) comprises a filter plate and a filter element which are mutually attached, and a filter hole is formed in the filter plate.

5. The crankcase ventilation system according to claim 2, wherein the venturi injection valve (18) comprises:

a second shell (181), wherein a nozzle (185) is arranged on the second shell (181), and the inner cavity of the second shell (181) is communicated with the Venturi gas channel (3);

a valve core (182), wherein the valve core (182) is movably arranged in the second shell (181);

a pressure regulating spring (183), wherein one end of the pressure regulating spring (183) is propped against the second shell (181), and the other end of the pressure regulating spring (183) is propped against the valve core (182);

an external shrinkage tube (184), one end of the external shrinkage tube (184) is communicated with the negative pressure cavity, and the other end of the external shrinkage tube (184) is communicated with the second dirty air channel (6).

6. The crankcase ventilation system of claim 5, wherein the spool (182) includes a small diameter section (1821), a variable diameter section (1822), a large diameter section (1823), and a tip (1824) connected in this order, a cross-sectional area of the variable diameter section (1822) gradually increases in a direction from the small diameter section (1821) to the large diameter section (1823), cross-sectional areas of the small diameter section (1821) and the large diameter section (1823) remain unchanged in a length direction thereof, the small diameter section (1821) is located on a side adjacent to the nozzle (185), and the pressure regulating spring (183) abuts against the tip (1824).

7. Crankcase ventilation system according to claim 1, characterized in that the intake assembly comprises an intake pipe (21) and an intake manifold (22) connected, a filter (23), a supercharger (24), an intercooler (25) and a throttle valve (26) being arranged in the intake direction in sequence on the intake pipe (21), the intake manifold (22) being in communication with the combustion chamber (8).

8. The crankcase ventilation system according to claim 7, wherein the supercharger (24) includes a third housing and a vane rotatably disposed in the third housing, the second dirty air channel (6) is connected to the third housing by a joint, and a distance between the joint and the vane is 50mm or less.

9. An engine comprising a crankcase ventilation system according to any of claims 1-8.

10. A vehicle comprising the engine according to claim 9.