Crankcase ventilation system, control method, engine system, and vehicle

Abstract

This invention provides a crankcase ventilation system, a control method, an engine system, and a vehicle. The system includes: an intake manifold equipped with an air filter and a turbocharger; an oil-gas separator, the inlet of which is used to introduce crankcase gas mixture and to perform gas-liquid separation; a return manifold connecting the gas outlet of the oil-gas separator to the intake manifold upstream of the turbocharger, and equipped with a first check valve; and an output manifold connecting the liquid collection end of the oil-gas separator to the external environment. From the oil-gas separator to the external environment, the output manifold sequentially includes a pump and a second check valve, the pump being used to discharge condensate from the oil-gas separator into the atmosphere. This solution effectively reduces the occurrence of crankcase ventilation system blockage.

Description

Technical Field

[0001] This invention relates to the field of engine ventilation technology, and more particularly to a crankcase ventilation system, control method, engine system, and vehicle. Background Technology

[0002] In modern diesel engines, the crankcase ventilation system is an essential emission control component. Crankcase blow-by gas is rich in water vapor produced during combustion and moisture from the high-temperature evaporation of engine oil. When the engine is shut down for an extended period in low-temperature environments, the physical temperature of the ventilation ducts drops rapidly, becoming well below the dew point of water. At this point, the water vapor trapped inside the ducts quickly condenses into liquid water and freezes on the inner walls of the ducts as the temperature drops below freezing. With frequent cold starts and shutdowns, the ice layer gradually thickens, eventually causing blockage of the airflow passages. Summary of the Invention

[0003] This invention provides a crankcase ventilation system, a control method, an engine system, and a vehicle to solve the aforementioned technical problems.

[0004] The present invention provides a crankcase ventilation system, comprising: An intake pipe, wherein an air filter and a booster are installed on the intake pipe; An oil-gas separator, wherein the inlet of the oil-gas separator is used to introduce crankcase mixed gas, and the oil-gas separator is used to perform gas-liquid separation; A return pipeline is connected to the gas outlet end of the oil-gas separator and the intake pipeline upstream of the booster, and a first check valve is installed on the return pipeline; The output pipeline connects the liquid collection end of the oil-gas separator to the external environment. From the oil-gas separator to the external environment, a pump and a second check valve are sequentially installed on the output pipeline. The pump is used to discharge the condensate in the oil-gas separator into the atmosphere.

[0005] In one embodiment of the present invention, the pumping pump includes an operating state and a closed state; When the engine switches from running to stopping, and the stopping time is less than or equal to a preset value, the pumping pump switches from the closed state to the working state, the second check valve opens, the output pipeline connects the oil-gas separator and the external environment, the second check valve closes, and the oil-gas separator and the intake pipeline are blocked by the first check valve. When the operating time of the pump in the working state exceeds a preset time, the pump switches from the working state to the off state.

[0006] In one embodiment of the present invention, the return pipeline, the output pipeline, and the internal pipeline of the oil-gas separator are respectively coated with a hydrophobic coating on their inner walls.

[0007] In one embodiment of the present invention, the crankcase ventilation system further includes a temperature sensor for detecting ambient temperature.

[0008] In one embodiment of the present invention, the crankcase ventilation system further includes a control module, which is electrically connected to the temperature sensor, the first check valve, the second check valve, and the pump, respectively. The control module is used to control the operation of the first check valve, the second check valve, and the pump based on the engine status and the detection results of the temperature sensor.

[0009] The present invention also provides an engine system, including an engine body and the aforementioned crankcase ventilation system, wherein the crankcase ventilation system is mounted on the engine body.

[0010] The present invention also provides a vehicle comprising: the aforementioned engine system.

[0011] The present invention also provides a crankcase ventilation control method, comprising: Applied to the aforementioned crankcase ventilation system, the method includes: Obtain the engine status, which includes running and stopped; If the engine is running, the first check valve is opened and the second check valve is closed, allowing the gas mixture in the crankcase to pass through the oil-gas separator and the return pipe to the intake pipe, while the output pipe is blocked from the external environment. If the engine is in a stopped state, determine whether the stopping time of the engine switching from running to stopping is greater than a preset value. If the stopping time is greater than the preset value, close the first check valve and the second check valve. If the stopping time is less than or equal to the preset value, compare the ambient temperature with the preset temperature value. If the ambient temperature is less than or equal to the preset temperature value, the first check valve is closed and the second check valve and the pump are opened to pump the condensate to the external environment; if the ambient temperature is greater than the preset temperature value, the first check valve, the second check valve and the pump are closed.

[0012] In one embodiment of the present invention, if the ambient temperature is less than or equal to the preset temperature value, the first check valve is closed, and the second check valve and the pump are opened to pump the condensate to the external environment. The method further includes: The working time of the pumping pump is compared with a preset time. If the working time of the pumping pump is greater than the preset time, the pumping pump is controlled to switch from the working state to the off state.

[0013] The beneficial effects of this invention are as follows: This invention proposes a crankcase ventilation system, control method, engine system, and vehicle. By incorporating an intake pipe to allow external air to enter the engine, an air filter to filter the air entering the engine, and a turbocharger to meet the engine's boost pressure requirements, an oil-liquid separator to separate the gas-liquid mixture in the crankcase, allowing combustible intake air to return to the intake pipe via a return pipe and then back to the engine for combustion, is the invention provides. An output pipe connects the liquid collection end of the oil-liquid separator to the external environment, facilitating the discharge of condensate. A pump provides power for condensate discharge. A first check valve acts as a one-way shut-off valve, preventing gas in the intake pipe from flowing to the oil-liquid separator via the return pipe. A second check valve also acts as a one-way shut-off valve, preventing external air from entering the oil-liquid separator via the output pipe. Attached Figure Description

[0014] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0015] In the attached diagram: Figure 1 This is a partial schematic diagram of a crankcase ventilation system provided in an embodiment of the present invention.

[0016] Figure 2 A flowchart of a crankcase ventilation control method provided in an embodiment of the present invention.

[0017] The attached figures are labeled as follows: 1. Air filter; 2. Control module; 3. Temperature sensor; 4. Second check valve; 5. Pump; 6. Oil-gas separator; 7. First check valve; 8. Intake pipe; 9. Return pipe; 10. Output pipe; 11. Detailed Implementation

[0018] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0019] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the shape, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0020] In the following description, numerous details are explored to provide a more thorough explanation of embodiments of the invention. However, it will be apparent to those skilled in the art that embodiments of the invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring embodiments of the invention.

[0021] In modern China VI diesel engines, the crankcase ventilation system is an essential emission control component. However, in cold regions such as Northeast and Northwest China, the crankcase ventilation system is highly susceptible to ice blockage failure when vehicles operate or stop in extremely cold winter conditions. The root cause of this technical defect lies in the fact that the blow-by gas in the crankcase is rich in water vapor produced by combustion and moisture generated by the high-temperature evaporation of engine oil. When the engine is stopped for an extended period in low-temperature environments, the physical temperature of the ventilation ducts drops rapidly, far below the dew point of water. At this time, the water vapor trapped inside the ducts quickly condenses into liquid water and freezes and adheres to the inner wall of the ducts when the temperature drops below freezing. With frequent alternations of cold starts and shutdowns, the ice layer gradually thickens, eventually leading to blockage of the airflow passages.

[0022] Traditional solutions often fall into a passive defense pattern, such as using electric heating wires to externally heat the pipes to prevent internal freezing and blockage. However, with traditional electric heating, on the one hand, when the engine is off and the battery power is limited, it cannot provide continuous heating power, causing the melted water to refreeze after the heating is interrupted, resulting in secondary freezing; on the other hand, simply heating does not remove the water from the system, which is only a temporary solution.

[0023] refer to Figure 1 As shown, this application provides a crankcase ventilation system, including an intake pipe 9, an oil-gas separator 6, a return pipe 10, and an output pipe 11.

[0024] The intake manifold 9 is equipped with an air filter 1 and a turbocharger 8. The air filter 1 is used to filter impurities in the outside atmosphere, providing clean intake airflow to the engine. The turbocharger 8 is used to compress the intake air, increasing the engine's intake volume.

[0025] The inlet of the oil-gas separator 6 is used to introduce the crankcase mixture. This mixture typically contains oil vapor, water vapor, and blow-by gases from the unburned mixture. The oil-gas separator 6 performs gas-liquid separation and may have an internal labyrinth or cyclone separation structure to separate large oil droplets and condensate droplets from the gas. The separated oil can flow back to the oil pan, while the separated gas continues to participate in subsequent processes.

[0026] The return line 10 connects the gas outlet of the oil-gas separator 6 to the intake line 9 upstream of the booster 8. A first check valve 7 is installed on the return line 10.

[0027] The output pipeline 11 connects the liquid collection end of the oil-gas separator 6 to the external environment. Typically, the liquid collection end is located at the lowest point of gravity or the bottom water accumulation chamber of the oil-gas separator 6 to facilitate liquid collection. From the oil-gas separator 6 to the external environment, a pumping pump 5 and a second check valve 4 are connected in series on the output pipeline 11.

[0028] The pump 5, acting as an active power source, is used to force the condensate collected in the oil-gas separator 6 into the atmosphere under specific operating conditions. The pump 5 provides suction force, enabling the extraction and discharge of condensed liquid water into the atmosphere, reducing the amount of water that freezes and thus lowering the probability of ice blockage. The second check valve 4 and the first check valve 7 form a bidirectional physical isolation when the engine is off, cutting off the convection path between the crankcase ventilation system and external cold air, reducing the risk of secondary condensation on the inner walls of the pipes caused by cold air backflow.

[0029] To optimize the operating logic of pump 5 and avoid unnecessary idling under unnecessary conditions, the state switching of pump 5 has been meticulously designed. In extremely cold environments, the phase change of water is a thermodynamic process highly dependent on time. If the drainage timing is inappropriate, such as starting drainage after a long period of shutdown, the condensate in the pipeline will have solidified into hard ice. Pump 5 will not only be unable to drain the ice, but the impeller may also be jammed by the ice, leading to motor damage.

[0030] Specifically, the pumping pump 5 has an operating state and a shut-off state. When the engine switches from running to stopping, i.e., has just undergone a shutdown action, and the stopping time is less than or equal to a preset value, it is determined that the current period is within an optimal drainage window. This preset value is usually set to the time window during which the residual heat of the engine can still keep the water in the pipeline in a liquid state. During this window period, the pumping pump 5 quickly switches from the shut-off state to the operating state, and at the same time controls the second check valve 4 to open, so that the output pipeline 11 connects the oil-gas separator 6 and the external environment.

[0031] During this drainage process, in order to prevent external cold air from being drawn into the system through the negative pressure of the pumping pump 5 via the intake pipe 9, the oil-gas separator 6 and the intake pipe 9 are blocked by the first check valve 7. That is, the first check valve 7 is kept closed, ensuring that the suction negative pressure of the pumping pump 5 is fully applied to the water accumulation chamber at the bottom of the oil-gas separator 6, thereby improving the drainage efficiency.

[0032] When the operating time of pump 5 in the working state exceeds the preset time, pump 5 will switch from the working state to the off state. If pump 5 remains in the normally open state, it will run dry after draining the water, which will not only consume battery power but also shorten the service life of the pump body.

[0033] For example, the preset time can be set to 30 seconds.

[0034] At the moment when the pumping pump 5 stops working, due to the one-way shut-off characteristic of the second check valve 4, or by synchronously controlling its closure, the path of external cold air being drawn back into the pipeline due to the transient negative pressure generated when the pump stops can be blocked, thereby reducing the risk of secondary condensation and icing caused by cold air backflow.

[0035] In some embodiments, in order to solve the problem that condensate tends to adhere to the inner wall of the pipe and separator under the action of surface tension, the material properties of the inner wall of the pipe are optimized in this embodiment.

[0036] In practical engineering applications, water vapor in crankcase blow-by will condense when it comes into contact with the cooler inner wall of the pipe. Because the inner wall of conventional rubber or metal pipes has a high surface free energy, condensate droplets often adhere to the pipe wall due to surface tension, a phenomenon known as pipe wall adhesion.

[0037] This wall-hanging phenomenon prevents water droplets from quickly sliding down to the collection area at the bottom due to their own gravity. When pump 5 starts to pump water briefly, a large number of water droplets still remain in the upper part of the pipe and cannot be effectively discharged. Once the ambient temperature drops below freezing, these residual water films and droplets will freeze into ice crystals. With the continuous accumulation of cold and heat, this will eventually lead to gradual ice blockage and failure of the pipe.

[0038] To address the aforementioned issues, this embodiment specifies that the inner walls of the return pipeline 10, the output pipeline 11, and the internal pipelines of the oil-gas separator 6 are coated with a hydrophobic coating.

[0039] Hydrophobic coatings reduce the surface free energy of the pipe's inner wall, increasing the contact angle at the solid-liquid interface. For example, fluorocarbon polymer coatings modified with nano-silica or polytetrafluoroethylene coatings can be used. The hydrophobic coating weakens the adhesion of condensate droplets to the inner wall. Once water vapor condenses into tiny droplets, they cannot remain stably on the wall surface. Instead, under the influence of gravity or airflow disturbance, they rapidly aggregate into larger droplets and slide quickly down the pipe wall, converging at the liquid collection end at the bottom of the oil-gas separator 6.

[0040] In other embodiments, to address the problem that the system cannot sense external climate conditions, leading to the blind activation of the active drainage procedure in normal or high-temperature environments where there is no risk of icing, the crankcase ventilation system also includes a temperature sensor and a control module for detecting ambient temperature.

[0041] For example, the ambient temperature sensor 3 can be installed in a suitable location that reflects the real atmospheric temperature, such as behind the front grille of the vehicle, below the rearview mirror, or at the inlet of the air intake pipe 9.

[0042] For example, the control module 2 is electrically connected to the ambient temperature sensor 3, the first check valve 7, the second check valve 4, and the pump 5, respectively.

[0043] The ambient temperature sensor 3 collects temperature data of the external environment in real time and converts it into an electrical signal, which is then transmitted to the control module (Electronic Control Unit, or ECU). Only when the ambient temperature sensor 3 detects that the current ambient temperature is lower than the set critical freezing point threshold, such as 0 degrees Celsius, will the system determine that there is a real risk of ice blockage and trigger the subsequent active drainage procedure.

[0044] Based on the aforementioned crankcase ventilation system, this application also provides an engine system. This engine system includes an engine body and the crankcase ventilation system described in any of the above embodiments, the crankcase ventilation system being mounted on the engine body.

[0045] In traditional diesel engine systems, the lack of effective anti-icing design in cold weather means that if the ventilation pipes freeze in winter, the rapidly increasing pressure in the crankcase will trigger a series of chain reactions. First, excessive pressure increases the resistance to piston movement, leading to reduced engine mechanical efficiency, which manifests as decreased vehicle power output and poor fuel economy. Second, the inability to expel blow-by gases causes oil contamination by combustion products, accelerating oil degradation and exacerbating wear on cylinder liners and bearings. Furthermore, if sulfides and oil vapors in the blow-by gases are forced into the aftertreatment system, such as the particulate filter, it will increase the burden on the aftertreatment system, damaging the catalyst and causing emissions to exceed standards.

[0046] The crankcase ventilation system, which features active drainage and physical isolation to prevent ice blockage, is deeply integrated into the engine block, resulting in excellent synergistic effects. On one hand, this ventilation system maintains a balanced pressure within the engine crankcase at a slightly negative or normal level, reducing the risk of oil leakage and power loss due to pressure buildup, thus ensuring the mechanical health and lubrication efficiency of the engine block. On the other hand, by ensuring that blow-by gases are smoothly introduced into the intake manifold for secondary combustion even in harsh weather conditions, it reduces the pathways for pollutant leakage, thereby ensuring the overall emission compliance of the engine system.

[0047] In one embodiment of this application, a vehicle is also provided. The vehicle includes the engine system described above.

[0048] like Figure 2 As shown, this application also provides a crankcase ventilation control method. This method is applied to the aforementioned crankcase ventilation system and includes: Step S1: Obtain the engine status, which includes running and stopped.

[0049] In this embodiment, the engine can switch between a running state and a stopped state.

[0050] Step S2: If the engine is running, open the first check valve 7 and close the second check valve 4, so that the mixed gas in the crankcase can pass through the oil-gas separator 6 and the return pipe 10 to the intake pipe 9, and the output pipe 11 is blocked from the external environment.

[0051] In this embodiment, if the engine is running, the first check valve 7 needs to be opened so that the gas mixture in the crankcase (i.e. blow-by gas) can be separated into gas and liquid by the oil-gas separator 6. The gas can then flow through the return pipe to the intake pipe and then return to the engine for combustion.

[0052] Step S3: If the engine status is stopped, determine whether the stopping time of the engine switching from running to stopping is greater than a preset value. If the stopping time is greater than the preset value, close the first check valve 7 and the second check valve 4. If the stopping time is less than or equal to the preset value, compare the ambient temperature with the preset temperature value.

[0053] It should be noted that if the ambient temperature is lower than the freezing temperature of water and the engine stops for a longer than the preset value, the water in the pipeline will freeze, causing pipeline blockage. Therefore, the working conditions of the pump 5 are that the engine stops and the ambient temperature is lower than the preset temperature value.

[0054] In step S4, if the ambient temperature is less than or equal to the preset temperature value, the first check valve 7 is closed and the second check valve 4 and the pump 5 are opened to pump the condensate to the external environment; if the ambient temperature is greater than the preset temperature value, the first check valve 7, the second check valve 4 and the pump 5 are closed.

[0055] In this embodiment, the condensate needs to be extracted before it freezes to prevent it from clogging the pipes.

[0056] In an exemplary embodiment, if the ambient temperature is less than or equal to a preset temperature value, the first check valve 7 is closed, and the second check valve 4 and the pump 5 are opened to pump the condensate to the external environment. The method further includes: The working time of pumping pump 5 is compared with the preset time. If the working time of pumping pump 5 is longer than the preset time, pumping pump 5 is controlled to switch from working state to off state.

[0057] In this embodiment, the pumping pump 5 automatically stops after working for a certain period of time, which can be 30 seconds, to avoid the pumping pump 5 from working ineffectively for an extended period of time.

[0058] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A crankcase ventilation system, characterized in that, include: An intake pipe is provided, which is equipped with an air filter and a booster; An oil-gas separator, the inlet of which is used to introduce crankcase mixed gas; A return pipeline is connected to the gas outlet end of the oil-gas separator and the intake pipeline upstream of the booster, and a first check valve is installed on the return pipeline; The output pipeline connects the liquid collection end of the oil-gas separator to the external environment. From the oil-gas separator to the external environment, a pump and a second check valve are sequentially installed on the output pipeline. The pump is used to discharge the condensate in the oil-gas separator into the atmosphere.

2. The crankcase ventilation system according to claim 1, characterized in that, The pumping pump includes an operating state and a shut-off state; When the engine switches from running to stopping, and the stopping time is less than or equal to a preset value, the pumping pump switches from the closed state to the working state, the second check valve opens, the output pipeline connects the oil-gas separator and the external environment, the second check valve closes, and the oil-gas separator and the intake pipeline are blocked by the first check valve. When the operating time of the pump in the working state exceeds a preset time, the pump switches from the working state to the off state.

3. The crankcase ventilation system according to claim 1, characterized in that, The inner walls of the return pipeline, the output pipeline, and the internal pipeline of the oil-gas separator are coated with a hydrophobic coating.

4. The crankcase ventilation system according to claim 1, characterized in that, The crankcase ventilation system also includes a temperature sensor for detecting ambient temperature.

5. The crankcase ventilation system according to claim 4, characterized in that, The crankcase ventilation system also includes a control module, which is electrically connected to the temperature sensor, the first check valve, the second check valve, and the pump, respectively. The control module is used to control the operation of the first check valve, the second check valve, and the pump based on the engine status and the detection results of the temperature sensor.

6. An engine system, characterized in that, It includes an engine body and a crankcase ventilation system as described in any one of claims 1 to 5, wherein the crankcase ventilation system is mounted on the engine body.

7. A vehicle, characterized in that, Includes the engine system as described in claim 6.

8. A crankcase ventilation control method, characterized in that, Applied to the crankcase ventilation system as described in any one of claims 1 to 5, the method comprises: Obtain the engine status, which includes running and stopped; If the engine is running, the first check valve is opened and the second check valve is closed, allowing the gas mixture in the crankcase to pass through the oil-gas separator and the return pipe to the intake pipe, while the output pipe is blocked from the external environment. If the engine is in a stopped state, determine whether the stopping time of the engine switching from running to stopping is greater than a preset value. If the stopping time is greater than the preset value, close the first check valve and the second check valve. If the stopping time is less than or equal to the preset value, compare the ambient temperature with the preset temperature value. If the ambient temperature is less than or equal to the preset temperature value, the first check valve is closed and the second check valve and the pump are opened to pump the condensate to the external environment; if the ambient temperature is greater than the preset temperature value, the first check valve, the second check valve and the pump are closed.

9. The crankcase ventilation control method according to claim 8, characterized in that, If the ambient temperature is less than or equal to the preset temperature value, the first check valve is closed, and the second check valve and the pump are opened to extract the condensate to the external environment. The method further includes: The working time of the pumping pump is compared with a preset time. If the working time of the pumping pump is greater than the preset time, the pumping pump is controlled to switch from the working state to the off state.

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