Crankcase ventilation system for guoqi emission
By incorporating a two-stage separation module and built-in piping within the oil-gas separator, the problems of incomplete oil separation and piping icing in the crankcase ventilation system are solved, achieving uniform gas distribution and efficient combustion.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- FAW QI NEW POWER (CHANGCHUN) TECHNOLOGY CO LTD
- Filing Date
- 2026-04-21
- Publication Date
- 2026-06-12
AI Technical Summary
The existing crankcase ventilation system has insufficient separation capacity in the oil-gas separation process, resulting in excessive oil concentration; external pipelines are prone to freezing and blockage in low-temperature environments; uneven gas distribution under low-load conditions leads to inconsistent combustion pressure in each cylinder.
It adopts a two-stage separation module (coarse separation module and fine separation module) combined with built-in pipeline design, sets up a small load channel with a one-to-many structure, uses cylinder head heat conduction to prevent icing, and evenly distributes gas to each cylinder.
This reduces the oil concentration in the output gas, prevents pipe icing, ensures consistent crankcase gas volume and concentration in each cylinder, and improves combustion efficiency.
Smart Images
Figure CN122190868A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of vehicle engine technology, and in particular to a crankcase ventilation system for China VII emission standards. Background Technology
[0002] During engine operation, some high-pressure combustion gases and oil vapors from the cylinders seep into the crankcase, forming crankcase gas. This gas needs to be separated by the crankcase ventilation system and reintroduced into the cylinders for combustion. Existing crankcase ventilation systems have structural and physical limitations in handling these gases. In the oil-gas separation stage, existing systems typically employ a single-stage mechanical separation structure, which has limited ability to capture and physically intercept small-particle oil mist. This results in the concentration of residual liquid oil in the separated crankcase gas exceeding the set emission standard limits. Regarding piping, existing crankcase gas delivery channels mostly use external rubber hoses and their associated connectors for assembly and connection. This external assembly structure not only creates mechanical gaps at each physical connection point, leading to gas leakage, but also, when the ambient temperature is below the freezing point of water, the crankcase gas flowing inside the external piping lacks thermal compensation from an external heat source. As a result, the water vapor carried in the gas condenses and undergoes a phase change, freezing, on the inner wall of the hose. The accumulation of solid ice reduces the cross-sectional area for fluid flow within the piping, leading to physical blockage of the flow channels and abnormal increases in crankcase pressure, causing the On-Board Diagnostics (OBD) system to generate fault codes. In the gas distribution stage, when the engine is under low load, existing systems typically connect their output end directly to the main intake manifold as a single physical inlet. Due to the lack of a forced fluid distribution structure, crankcase gases entering the main intake manifold cannot diffuse equally into the branch intake passages leading to each individual cylinder due to differences in the dynamic pressure distribution within the manifold. This fluid transport path results in differences in the volume of crankcase gases drawn into each individual cylinder and the oil concentration within the cylinders during the power cycle, leading to inconsistent power pressure values generated by the combustion of the air-fuel mixture in each cylinder. Summary of the Invention
[0003] The purpose of this invention is to provide a crankcase ventilation system for China VII emission standards, which solves the problems of target misjudgment, glare risk and lighting blind spots caused by insufficient perception ability and system response lag in existing adaptive high beam systems under adverse weather and high-speed dynamic scenarios.
[0004] This invention provides the following solution:
[0005] This invention provides a crankcase ventilation system for China VII emission standards, comprising:
[0006] An oil-gas separator, wherein a coarse separation module and a fine separation module are sequentially arranged along the airflow direction;
[0007] High-load passage and low-load passage, both of which are located inside the cylinder head;
[0008] The output end of the low-load channel has a one-to-many structure, and each branch channel of the one-to-many structure is respectively connected to each cylinder of the engine.
[0009] An oil return channel for an oil-gas separator, one end of which is connected to the oil drain port at the bottom of the oil-gas separator;
[0010] A return oil check valve is installed in the return oil channel of the oil-gas separator.
[0011] The engine includes a combustion chamber, and the high-load passage and the low-load passage are disposed within the cylinder head adjacent to the outer wall of the combustion chamber.
[0012] The engine is a four-cylinder engine, and the output end of the low-load channel has a one-to-many structure, which is a one-to-four structure. The one-to-four structure includes four pipe branches with the same diameter, and the four pipe branches are respectively connected to the four cylinders.
[0013] The engine includes an oil pan, and the oil return check valve is oriented from the oil-gas separator toward the oil pan.
[0014] The crankcase ventilation system also includes a turbocharger and an intake passage;
[0015] The air inlet of the high-load channel is connected to the air outlet of the oil-gas separator, and the air outlet of the high-load channel is connected to the turbocharger.
[0016] The air inlet of the low-load channel is connected to the air outlet of the oil-gas separator, and the output of the low-load channel is connected to the air inlet channel through the branch channels of the multi-branch structure. The air inlet channel is connected to the cylinder.
[0017] The coarse separation module is equipped with multiple staggered baffles, which form a tortuous airflow channel inside the coarse separation module.
[0018] The fine separation module is located on the downstream exhaust side of the coarse separation module, and the exhaust port of the coarse separation module is positioned directly opposite the intake end of the fine separation module.
[0019] The oil return channel of the oil-gas separator extends vertically along the side wall of the engine toward the ground, and the return check valve is fixedly installed at the end outlet position at the bottom of the oil return channel of the oil-gas separator.
[0020] The oil-gas separator includes a sealed housing, and the coarse separation module and the fine separation module are fixedly installed inside the sealed housing.
[0021] The above solution achieves the following beneficial technical effects:
[0022] This invention solves the problem of high oil content at the outlet caused by a single separation structure by sequentially arranging a coarse separation module and a fine separation module along the airflow direction in the oil-gas separator. The coarse separation module uses a physical collision mechanism in the flow channel to intercept large oil droplets, while the fine separation module performs secondary capture of residual tiny oil mists that have passed through the coarse separation module. The two-stage series physical separation structure reduces the concentration of liquid oil in the output crankcase gas, ensuring that the amount of oil entering the engine cylinder for combustion is lower than the set emission limit.
[0023] This invention solves the problems of external piping sealing failure and water vapor icing blockage in extremely cold environments by placing the high-load and low-load channels inside the engine cylinder head, adjacent to the outer wall of the combustion chamber. The heat generated by the combustion chamber is conducted through the solid metal cylinder head wall to the walls of the high-load and low-load channels, maintaining the surface temperature of the pipe walls above the freezing point of water and preventing the physical phase change process of gaseous water condensing into solid ice. Simultaneously, the built-in cast structure eliminates the need for external rubber hoses and their joints, eliminating leakage gaps at physical connection points.
[0024] This invention solves the problem of inconsistent crankcase gas concentration in each cylinder caused by a single-inlet intake manifold by setting a multi-branch structure at the output end of the low-load channel, allowing each branch channel to be independently connected to each cylinder of the engine. The separated crankcase gas enters each branch channel with equal internal flow cross-sectional area at the split node, and is physically divided into multiple independent airflows with equal flow rates, which are then introduced into the corresponding cylinders. This makes the difference in the volume and concentration of crankcase gas drawn into each cylinder in the same working cycle approach zero, reducing the combustion pressure deviation caused by differences in the air-fuel mixture composition in each cylinder. Attached Figure Description
[0025] Figure 1 This is a schematic diagram of the internal cross-section of the present invention.
[0026] Figure 2 This is a schematic diagram of the external structure of the present invention.
[0027] The components include: 1. turbocharger; 2. high-load channel; 3. oil-gas separator; 4. oil-gas separator return channel; 5. return check valve; 6. low-load channel; 7. intake channel; 8. fine separation module; and 9. coarse separation module. Detailed Implementation
[0028] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0029] See attached document Figure 1 and attached Figure 2 The present invention provides a crankcase ventilation system for China VII emission standards, comprising: an oil-gas separator 3, wherein a coarse separation module 9 and a fine separation module 8 are sequentially arranged in the oil-gas separator 3 along the airflow direction;
[0030] The high-load channel 2 and the low-load channel 6 are both located inside the cylinder head. The output end of the low-load channel 6 has a multi-branch structure, with each branch channel corresponding to a cylinder of the engine. The oil-gas separator return channel 4 has one end connected to the oil drain port at the bottom of the oil-gas separator 3. The return check valve 5 is located inside the oil-gas separator return channel 4.
[0031] Specifically, this embodiment provides a crankcase ventilation system designed for China VII emission standards. The basic physical architecture of the crankcase ventilation system includes an oil-gas separator 3, a high-load channel 2, a low-load channel 6, an oil return channel 4, and a return check valve 5. Crankcase gas containing liquid engine oil and oil mist enters the oil-gas separator 3 through the inlet. Inside the oil-gas separator 3, along a predetermined airflow direction, the crankcase gas sequentially passes through a coarse separation module 9 and a fine separation module 8 fixed inside. The coarse separation module 9 separates large oil droplets, while the fine separation module 8 separates the tiny oil mist particles that were not intercepted by the coarse separation module 9. This two-stage physical separation structure reduces the liquid engine oil content in the crankcase gas at the outlet. The crankcase gas, after being separated from the liquid engine oil, is output to the high-load channel 2 and the low-load channel 6. The high-load channel 2 and the low-load channel 6 are integrally formed inside the cylinder head using a cylinder head casting process, eliminating external rubber hoses and their connectors and reducing the probability of leakage at pipe connections. The crankcase gas entering the low-load channel 6 enters a multi-branch structure at its output end. This multi-branch structure consists of a main pipe section that branches into multiple independent physical branch channels. The end of each branch channel is fixedly connected to the intake end of the corresponding cylinder of the engine, physically dividing the crankcase gas into multiple independent airflows and introducing them into the corresponding cylinders. The liquid engine oil intercepted by the coarse separation module 9 and the fine separation module 8 collects at the bottom of the oil-gas separator 3 under gravity and flows into the oil return channel 4 of the oil-gas separator through the bottom drain port. The return oil check valve 5 is fixedly installed on the flow interface inside the oil return channel 4 of the oil-gas separator to control the flow state of the liquid engine oil in one direction.
[0032] The engine includes a combustion chamber, a high-load passage 2 and a low-load passage 6 located inside the cylinder head near the outer wall of the combustion chamber.
[0033] Specifically, this embodiment sets the spatial layout of the high-load passage 2 and the low-load passage 6 within the cylinder head. The thickness of the solid wall between the pipe walls of the high-load passage 2 and the low-load passage 6 and the outer wall of the engine combustion chamber is set within the effective heat conduction range. When fuel combustion occurs inside the combustion chamber, the generated high-temperature heat energy is transferred to the pipe walls of the high-load passage 2 and the low-load passage 6 through the solid wall of the metal cylinder head via heat conduction. This heat conduction process keeps the wall temperature inside the high-load passage 2 and the low-load passage 6 above 0 degrees Celsius. When crankcase gas containing water vapor flows through the high-load passage 2 and the low-load passage 6, the wall temperature is higher than the freezing point of water, thereby blocking the physical phase change process of gaseous water turning into solid ice and maintaining the flow cross-sectional area of the high-load passage 2 and the low-load passage 6 from being reduced by the ice layer.
[0034] The engine is a four-cylinder engine. The output end of the low-load channel 6 has a one-to-many structure, which is a one-to-four structure. The one-to-four structure includes four pipe branches with the same diameter, and the four pipe branches are connected to the four cylinders respectively.
[0035] Specifically, in the implementation of a four-cylinder engine, the multi-port structure at the output end of the low-load channel 6 is configured as a four-port structure. The main pipe of this four-port structure connects to four branch pipes at the branching node. The internal flow cross-sectional area of the four branch pipes is exactly equal, i.e., the pipe diameter is the same, and the inner wall roughness and bending angle of each branch pipe are consistent, thereby ensuring that the fluid resistance generated by the four branch pipes to the internal airflow is equal. When the crankcase gas separated by the oil-gas separator 3 reaches the branching node, it is divided into four airflows of equal volume under the action of equal fluid resistance. These four airflows enter the four independent cylinders through the four branch pipes respectively. This structure makes the difference in the volume of crankcase gas and the oil vapor concentration drawn into the four cylinders in the same working cycle approach zero, thereby reducing the combustion pressure deviation caused by the difference in the mixture composition of the four cylinders.
[0036] The engine includes an oil pan, and the oil return check valve 5 is oriented from the oil-gas separator 3 toward the oil pan.
[0037] Specifically, this embodiment clarifies the installation orientation and working logic of the return oil check valve 5. The end of the oil return channel 4 of the oil-gas separator is connected to the oil pan of the engine. The return oil check valve 5 contains a valve core and an elastic reset element, which determines the one-way passage of airflow or liquid. The conduction direction of the return oil check valve 5 is fixed to point from the oil-gas separator 3 to the oil pan. When the downward hydrostatic pressure generated by the liquid oil accumulated in the return oil channel 4 of the oil-gas separator is greater than the sum of the gas pressure in the oil pan and the opening pressure of the check valve, the return oil check valve 5 opens, and the liquid oil flows into the oil pan. When the engine operating conditions change drastically, causing the pressure inside the oil pan to rise instantaneously and exceed the pressure inside the return oil channel 4 of the oil-gas separator, this reverse pressure difference pushes the valve core of the return oil check valve 5 to close, physically cutting off the path of the liquid oil and unseparated gas in the oil pan to flow upwards and back into the oil-gas separator 3 along the return oil channel 4 of the oil-gas separator.
[0038] The crankcase ventilation system also includes a turbocharger 1 and an intake passage 7; the intake end of the high-load passage 2 is connected to the outlet end of the oil-gas separator 3, and the outlet end of the high-load passage 2 is connected to the turbocharger 1.
[0039] Specifically, the system configuration includes a turbocharger 1 and an intake passage 7. A high-load passage 2 is located between the oil-gas separator 3 and the turbocharger 1. The intake port of the high-load passage 2 is in fluid communication with the outlet port on the housing of the oil-gas separator 3, and the outlet port of the high-load passage 2 is in fluid communication with the intake port of the turbocharger 1. When the engine is in a high-load operating state, the compressor impeller of the turbocharger 1 rotates at high speed, generating a negative pressure area at its intake port. This negative pressure is transmitted to the outlet port of the oil-gas separator 3 through the high-load passage 2, forming a pressure difference that drives the flow of crankcase gas. Under the action of this pressure difference, the crankcase gas that has separated the engine oil passes through the oil-gas separator 3 and the high-load passage 2 in sequence, and finally enters the turbocharger 1, where it is mixed with fresh air and forced into the cylinder.
[0040] The intake end of the low-load channel 6 is connected to the outlet end of the oil-gas separator 3. The output end of the low-load channel 6 is connected to the intake channel 7 through various branch channels of the one-to-many structure. The intake channel 7 is connected to the cylinder.
[0041] Specifically, the intake port of the low-load channel 6 is also fluidly connected to the outlet port of the oil-gas separator 3, forming a parallel gas output pipeline with the high-load channel 2. The ends of each branch channel in the multi-branch structure at the output end of the low-load channel 6 are connected to the intake channel 7. The end of the intake channel 7 is directly connected to the intake valve of the cylinder. When the engine is in a low-load operating state, the throttle opening is small, and a high vacuum, i.e., negative pressure, is generated in the intake channel 7. This vacuum is transmitted to the low-load channel 6 through each branch channel, forming suction. Under the action of this suction, the separated crankcase gas enters the low-load channel 6 from the oil-gas separator 3, and after being diverted by the multi-branch structure, it enters the intake channel 7. Then, it is directly sucked into the corresponding cylinder through the intake valve to participate in the next power cycle.
[0042] The coarse separation module 9 has multiple staggered baffles inside, which form a tortuous airflow channel inside the coarse separation module 9.
[0043] Specifically, the coarse separation module 9 has multiple rigid baffles fixedly welded or integrally formed inside its cavity. These baffles extend alternately along the airflow direction within the cavity, with fluid gaps between the ends of the baffles and the inner wall of the cavity. Adjacent baffles form a continuously changing geometric space, constituting a tortuous airflow channel. When crankcase gas containing oil droplets of various sizes enters this airflow channel at a certain initial velocity, the gas is physically blocked by the baffles and forced to change its flow direction. Due to the large mass of the large oil droplets, their inertial force is greater than the fluid drag force, preventing them from following the gas trajectory to make a sharp turn. Instead, they impact the solid surface of the baffles along a straight line. After the impact, the kinetic energy of the large oil droplets decays to zero, adhering to the baffle surface and accumulating into an oil film. Finally, under the action of gravity, they drip down along the baffle surface, thus completing the first stage of the large oil droplet separation process.
[0044] The fine separation module 8 is located on the downstream exhaust side of the coarse separation module 9, and the exhaust port of the coarse separation module 9 is positioned directly opposite the intake end of the fine separation module 8.
[0045] Specifically, the fine separation module 8 is located downstream of the coarse separation module 9 in terms of fluid dynamics. The center axis of the exhaust port of the coarse separation module 9 is aligned with the center of the effective flow section of the air inlet of the fine separation module 8. After being intercepted by the baffle of the coarse separation module 9, most of the large droplets in the airflow have been removed, but there are still oil mists with extremely small particle sizes suspended in the airflow. The airflow is injected horizontally or vertically into the interior of the fine separation module 8 from the exhaust port of the coarse separation module 9. The interior of the fine separation module 8 is equipped with porous media or fiber filter material with a porosity lower than the flow channel gap. It is used to capture tiny oil mists with a particle size smaller than the lower limit of the interception of the coarse separation module 9 through physical mechanisms such as interception and Brownian diffusion, thus completing the second stage of fine separation.
[0046] The oil return channel 4 of the oil-gas separator extends vertically along the side wall of the engine toward the ground, and the return check valve 5 is fixedly installed at the end outlet position at the bottom of the oil return channel 4 of the oil-gas separator.
[0047] Specifically, the oil return channel 4 of the oil-gas separator has a tubular structure, with its overall axis parallel to the direction of gravity, extending vertically downwards close to the side wall of the engine cylinder block. The return check valve 5 is mechanically fixed to the bottom end outlet position of the oil return channel 4 of the oil-gas separator by threads or flanges. The function of this vertically extending structure is that the separated liquid oil continuously accumulates inside the pipeline and forms a liquid column of a certain height. According to the principle of fluid statics, the height of the liquid column is proportional to the hydrostatic pressure generated at its bottom. By setting the return check valve 5 at the bottom end outlet position, the valve core can directly bear the maximum hydrostatic pressure accumulated by the entire liquid column. When the hydrostatic pressure reaches and exceeds the opening threshold of the return check valve 5, the valve is physically pushed open to perform the oil discharge operation.
[0048] The oil-gas separator 3 includes a sealed housing, and the coarse separation module 9 and the fine separation module 8 are fixedly installed inside the sealed housing.
[0049] Specifically, the outer perimeter of the oil-gas separator 3 is formed by a sealed shell. This sealed shell is airtightly connected by fastening bolts and sealing gaskets to prevent crankcase gas from leaking into the external environment of the engine. The coarse separation module 9 and the fine separation module 8 are both placed in the internal cavity of the sealed shell and are fixed to the inner wall of the shell at a set coordinate position by mechanical means such as snaps, slide rails or welding. By integrating the two-stage separation modules into the same physical shell, the transition connection pipes and fastening clamps originally required between the two-stage modules are eliminated. After the crankcase gas containing engine oil flows in from the inlet of the sealed shell, it flows continuously and in a closed manner through the flow channel formed by the coarse separation module 9 and the fine separation module 8 inside the shell. After separation, it flows out from the outlet of the sealed shell. This integrated structure reduces the external three-dimensional space volume occupied by the system.
[0050] Working principle: The crankcase gas generated by the engine first enters the sealed housing of the oil-gas separator 3 of the crankcase ventilation system. The crankcase gas first enters the coarse separation module 9, which is fixedly installed inside the sealed housing, along the airflow direction. Inside the coarse separation module 9, the crankcase gas flows through the tortuous airflow channel formed by multiple staggered baffles. The crankcase gas collides with the baffles, and large oil droplets in the crankcase gas are intercepted and separated from the gas by the baffles. The crankcase gas separated by the coarse separation module 9 flows out from the exhaust port of the coarse separation module 9 and directly enters the intake end of the fine separation module 8, which is located on the downstream exhaust side.
[0051] Inside the fine separation module 8, residual oil mist droplets in the crankcase gas are separated. The liquid engine oil separated by the coarse separation module 9 and the fine separation module 8 settles to the bottom of the oil-gas separator 3 under gravity and flows into the oil return channel 4 of the oil-gas separator through the oil drain port at the bottom of the oil-gas separator 3. The liquid engine oil flows vertically downward along the side wall of the engine towards the ground along the oil return channel 4. After passing through the return oil check valve 5, which is fixedly installed at the bottom end of the oil return channel 4, it finally flows into the oil pan of the engine. The conduction direction of the return oil check valve 5 is limited to the direction from the oil-gas separator 3 towards the oil pan. The return oil check valve 5 prevents the engine oil in the oil pan from flowing back into the oil-gas separator 3 along the oil return channel 4.
[0052] After the liquid engine oil is separated by the fine separation module 8, the crankcase gas flows out from the outlet of the oil-gas separator 3 and enters either the high-load passage 2 or the low-load passage 6 depending on the engine load. Both high-load passage 2 and low-load passage 6 are located inside the cylinder head and near the outer wall of the engine combustion chamber. The heat generated during combustion chamber operation is transferred through the cylinder head to the walls of high-load passage 2 and low-load passage 6, physically heating the crankcase gas flowing within them and maintaining the temperature above the freezing point of water. When the engine is under high load, the separated crankcase gas flows out from the high-load passage... The gas flows into the turbocharger 1 through the intake end of the high-load passage 2 and into the turbocharger 1 through the outlet end of the high-load passage 2. When the engine is under low load, the separated crankcase gas flows into the intake end of the low-load passage 6 and into the multi-part structure at the output end of the low-load passage 6. When the engine is a four-cylinder engine, the multi-part structure is a four-part structure. The separated crankcase gas flows into four pipe branches with the same diameter. In the four pipe branches, it is divided into four equal parts of airflow, which are output from each pipe branch and connected to the intake passage 7. Finally, it flows into the four cylinders of the engine through the intake passage 7 to participate in combustion. The volume of crankcase gas received by each cylinder is consistent.
[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A crankcase ventilation system designed for China VII emission standards, characterized in that, include: Oil-gas separator (3), wherein a coarse separation module (9) and a fine separation module (8) are arranged sequentially along the airflow direction inside the oil-gas separator (3); High-load passage (2) and low-load passage (6), both of which are located inside the cylinder head; The output end of the low-load channel (6) has a multi-branch structure, and each branch channel of the multi-branch structure is respectively connected to each cylinder of the engine. Oil-gas separator return oil channel (4), one end of which is connected to the oil outlet at the bottom of the oil-gas separator (3); Oil return check valve (5) is installed in the oil return channel (4) of the oil-gas separator.
2. The crankcase ventilation system for China VII emission standards according to claim 1, characterized in that, The engine includes a combustion chamber, and the high-load passage (2) and the low-load passage (6) are located in the cylinder head near the outer wall of the combustion chamber.
3. A crankcase ventilation system for China VII emission standards according to claim 1, characterized in that, The engine is a four-cylinder engine, and the output end of the low-load channel (6) is a one-to-many structure, which is a one-to-four structure. The one-to-four structure includes four pipe branches with the same diameter, and the four pipe branches are respectively connected to the four cylinders.
4. A crankcase ventilation system for China VII emission standards according to claim 1, characterized in that, The engine includes an oil pan, and the oil return check valve (5) is directed from the oil-gas separator (3) toward the oil pan.
5. A crankcase ventilation system for China VII emission standards according to claim 1, characterized in that, The crankcase ventilation system also includes a turbocharger (1) and an intake passage (7); The air inlet of the high-load channel (2) is connected to the air outlet of the oil-gas separator (3), and the air outlet of the high-load channel (2) is connected to the booster (1).
6. A crankcase ventilation system for China VII emission standards according to claim 5, characterized in that, The air inlet of the small load channel (6) is connected to the air outlet of the oil-gas separator (3), and the output of the small load channel (6) is connected to the air inlet channel (7) through the branch channels of the one-to-many structure. The air inlet channel (7) is connected to the cylinder.
7. A crankcase ventilation system for China VII emission standards according to claim 1, characterized in that, The coarse separation module (9) is equipped with multiple staggered baffles, which form a tortuous airflow channel inside the coarse separation module (9).
8. A crankcase ventilation system for China VII emission standards according to claim 7, characterized in that, The fine separation module (8) is located on the downstream exhaust side of the coarse separation module (9), and the exhaust port of the coarse separation module (9) is located directly opposite the air inlet of the fine separation module (8).
9. A crankcase ventilation system for China VII emission standards according to claim 1, characterized in that, The oil return channel (4) of the oil-gas separator extends vertically along the side wall of the engine toward the ground, and the oil return check valve (5) is fixedly installed at the end outlet position at the bottom of the oil return channel (4) of the oil-gas separator.
10. A crankcase ventilation system for China VII emission standards according to claim 1, characterized in that, The oil-gas separator (3) includes a sealed housing, and the coarse separation module (9) and the fine separation module (8) are fixedly installed inside the sealed housing.