Blow-by gas recirculation device

Abstract

To improve ventilation efficiency of blow-by gas in a supercharged engine.SOLUTION: A blow-by gas recirculation device applied to a supercharged engine 10 includes: a first passage R1 that allows communication between an intake manifold 28 and inside of a crank case 15; a second passage R2 that allows communication between the intake manifold 28 and inside of the crank case 15; a third passage R3 that allows communication between a portion upstream of a compressor 24 in an intake passage 21 and inside of the crank case 15; a first check valve 42 that regulates a gas flowing direction in the first passage R1 only to a direction toward the intake passage 21; and a second check valve 46 that regulates a gas flowing direction in the second passage R2 only to a direction toward inside of the crank case 15.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a blow-by gas reflux device.

Background Art

[0002] As a blow-by gas treatment device for a supercharged engine, the device described in Patent Document 1 is known. This blow-by gas treatment device includes an air introduction passage that communicates a portion downstream of the compressor and upstream of the intercooler in the intake passage with the inside of the crankcase. Further, this blow-by gas treatment device includes a reflux passage that communicates a portion upstream of the compressor in the intake passage with the inside of the crankcase. And, this blow-by gas treatment device performs ventilation of blow-by gas by sending fresh air pressurized by the compressor into the inside of the crankcase through the air introduction passage during the supercharged operation of the supercharged engine.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above conventional blow-by gas reflux device, there is still room for improvement in improving the ventilation efficiency, such as being unable to perform ventilation during natural intake operation.

Means for Solving the Problems

[0005] A blow-by gas recirculation device for solving the above problems is a blow-by gas recirculation device for a supercharged engine comprising a compressor installed in the intake passage, an intercooler installed in the intake passage downstream of the compressor, and a throttle valve installed in the intake passage downstream of the intercooler, which recirculates blow-by gas from inside the crankcase to the intake passage, comprising a first passage connecting the intake passage downstream of the throttle valve to the inside of the crankcase, and the intake passage downstream of the intercooler and the... The device includes a second passage communicating with the inside of the crankcase, a third passage communicating the portion of the intake passage upstream of the compressor with the inside of the crankcase, a first check valve that allows gas to flow from the inside of the crankcase to the intake passage through the first passage, while restricting gas to flow from the intake passage to the inside of the crankcase through the first passage, and a second check valve that allows gas to flow from the intake passage to the inside of the crankcase through the second passage, while restricting gas to flow from the inside of the crankcase to the intake passage through the second passage. [Effects of the Invention]

[0006] The blow-by gas recirculation device described above has the effect of improving the ventilation efficiency of blow-by gas in a turbocharged engine. [Brief explanation of the drawing]

[0007] [Figure 1] This diagram schematically shows the configuration of one embodiment of a blow-by gas recirculation device. [Figure 2] This diagram shows the state of the blow-by gas recirculation device in the naturally aspirated range. [Figure 3] This diagram shows the state of the blow-by gas recirculation device in the supercharged range. [Figure 4] This diagram schematically shows the configuration of another embodiment of the blow-by gas recirculation device. [Modes for carrying out the invention]

[0008] Below, one embodiment of a blow-by gas recirculation device will be described in detail with reference to Figures 1 to 3. <Configuration of a supercharged engine> First, with reference to Figure 1, the configuration of the supercharged engine 10 employing the blow-by gas recirculation device of this embodiment will be described. The supercharged engine 10 shown in Figure 1 is a hydrogen engine that uses hydrogen as fuel. In a hydrogen engine, combustible hydrogen may be contained in the blow-by gas. Therefore, hydrogen engines require higher blow-by gas ventilation performance than gasoline engines or diesel engines.

[0009] The supercharged engine 10 includes a cylinder block 11. Inside the cylinder block 11 are multiple cylinders 12. Figure 1 shows only one of the multiple cylinders 12. Each cylinder 12 houses a piston 13 that is reciprocally movable. Above the piston 13 in the cylinder 12 is a combustion chamber 17 for burning hydrogen. An oil pan 14 for storing oil is attached to the lower part of the cylinder block 11. Below the cylinders 12 inside the cylinder block 11 is a crankcase 15. A cylinder head 16 is attached to the upper part of the cylinder block 11. Inside the cylinder head 16, each cylinder 12 has its own individual intake port 18 and exhaust port 19. A head cover 16A is attached to the upper part of the cylinder head 16. Inside the upper part of the cylinder head 16, covered by the head cover 16A, is a valve train chamber 20 housing the valve train mechanism.

[0010] The supercharged engine 10 includes an intake passage 21, which is the passage for introducing air into the combustion chamber 17, and an exhaust passage 22, which is the passage for discharging exhaust from the combustion chamber 17. The intake passage 21 is equipped with an air cleaner 23 for filtering dust and other particles from the air. A compressor 24 is installed in the intake passage 21 downstream of the air cleaner 23. The compressor 24, together with a turbine 25 installed in the exhaust passage 22, constitutes a turbocharger. An intercooler 26 is installed in the intake passage 21 downstream of the compressor 24. The intercooler 26 is a heat exchanger for cooling the air that has become hot due to compression by the compressor 24. A throttle valve 27 is installed in the intake passage 21 downstream of the intercooler 26. The throttle valve 27 is a valve for adjusting the flow rate of air sent to the combustion chamber 17 through the intake passage 21. The intake passage 21 is branched separately for each cylinder 12 in the intake manifold 28, which is located downstream of the throttle valve 27. The intake manifold 28 is connected to the combustion chamber 17 through the intake port 18.

[0011] Furthermore, the supercharged engine 10 is equipped with an injector 29, a hydrogen tank 30, and a pressure regulating device 31. The pressure regulating device 31 regulates the pressure of the hydrogen in the hydrogen tank 30 and supplies it to the injector 29. The injector 29 injects hydrogen into the air used for combustion in the combustion chamber 17. In the case of Figure 1, the injector 29 is installed to inject hydrogen into the intake port 18, but the injector 29 may also be installed to inject hydrogen into the combustion chamber 17.

[0012] <Regarding the configuration of the blow-by gas recirculation system> Next, with reference to Figure 1, the configuration of the blow-by gas recirculation device of this embodiment will be described. The blow-by gas recirculation device has three passages, a first passage R1, a second passage R2, and a third passage R3, which connect the crankcase 15 and the intake passage 21.

[0013] The first passage R1 is a passage that connects the portion of the intake passage 21 downstream of the throttle valve 27 to the inside of the crankcase 15. The first passage R1 consists of a blow-by gas passage 40, a head-side separator 41, a first check valve 42, a first PCV hose 43, and a block-side separator 44. The head-side separator 41 and the block-side separator 44 are separators that separate oil mist from the blow-by gas flowing through the first passage R1. The head-side separator 41 is mounted inside the head cover 16A. The blow-by gas passage 40 is a passage that passes through the inside of the cylinder block 11 and cylinder head 16 and connects the inside of the crankcase 15 to the head-side separator 41. The block-side separator 44 is provided in the middle of the blow-by gas passage 40 in the cylinder block 11. The first PCV hose 43 is a hose that connects the head-side separator 41 to the intake manifold 28. The first check valve 42 is a valve that allows gas to flow from the inside of the crankcase 15 through the first passage R1 to the intake passage 21, while restricting gas flow from the intake passage 21 through the first passage R1 to the inside of the crankcase 15. The first check valve 42 is installed at the connection point of the first PCV hose 43 to the head-side separator 41. In this embodiment, the head-side separator 41 and the block-side separator 44 correspond to the first separator that separates oil mist from the gas flowing through the first passage R1.

[0014] The second passage R2 is a passage that connects the portion of the intake passage 21 downstream of the intercooler 26 to the inside of the crankcase 15. The second passage R2 is composed of a second PCV hose 45 and a second check valve 46. The second PCV hose 45 is a hose that connects the crankcase 15 to the intake manifold 28. The second check valve 46 is a valve that allows the flow of gas from the intake passage 21 to the inside of the crankcase 15 through the second passage R2, while restricting the flow of gas from the inside of the crankcase 15 to the intake passage 21 through the second passage R2. The second check valve 46 is installed at the connection point of the second PCV hose 45 to the crankcase 15.

[0015] The third passage R3 is a passage that connects the portion of the intake passage 21 upstream of the compressor 24 to the inside of the crankcase 15. The third passage R3 consists of an oil return passage 47, a valve train chamber 20, a second separator 48, and a third PCV hose 49. The oil return passage 47 is a passage that connects the valve train chamber 20 and the crankcase 15 by passing through the inside of the cylinder block 11 and the cylinder head 16. The oil return passage 47 functions as a passage for returning oil from the valve train chamber 20 to the oil pan 14, while also functioning as a passage for circulating gas between the valve train chamber 20 and the crankcase 15. The second separator 48 is a separator that separates oil mist from the blow-by gas flowing through the third passage R3. The second separator 48 is installed inside the head cover 16A. The third PCV hose 49 is a hose that connects the portion of the intake passage 21 downstream of the air cleaner 23 and upstream of the compressor 24 to the second separator 48.

[0016] In the blow-by gas recirculation device of this embodiment, the second passage R2 is configured to have a minimum flow area smaller than the minimum flow area of ​​the third passage R3. The minimum flow area represents the flow area of ​​the portion of the passage where the gas flow area is minimized. This relationship of minimum flow area can be achieved, for example, by using a hose with a smaller diameter than the third PCV hose 49 for the second PCV hose 45. Alternatively, this relationship can also be achieved by providing a constriction in the middle of the second passage R2.

[0017] <Effects and Effects of the Embodiment> The operation and effects of this embodiment will be explained with reference to Figures 2 and 3. The white arrows shown in Figures 2 and 3 indicate the direction of airflow within the blow-by gas recirculation device. Additionally, the hatched arrows shown in Figure 2 and Figure 3 (described later) indicate the direction of blow-by gas flow within the blow-by gas recirculation device.

[0018] Figure 2 shows the state of the blow-by gas reflux device during natural aspiration operation. During natural aspiration operation, the inside of the intake manifold 28 is under negative pressure, that is, a pressure lower than atmospheric pressure. The inside of the crankcase 15 is connected to the intake manifold 28 through the first passage R1. Further, the first check valve 42 installed in the first passage R1 is configured to allow the flow of gas from the inside of the crankcase 15 through the first passage R1 toward the intake passage 21. On the other hand, the inside of the crankcase 15 is connected to a portion upstream of the compressor 24 in the intake passage 21 through the third passage R3. Therefore, at this time, air is introduced into the inside of the crankcase 15 through the third passage R3, and the blow-by gas in the crankcase 15 is sucked into the intake manifold 28 through the first passage R1.

[0019] Figure 3 shows the state of the blow-by gas reflux device during supercharging operation. During supercharging operation, a portion downstream of the compressor 24 in the intake passage 21 is under positive pressure, that is, a pressure higher than atmospheric pressure. The second passage R2 is provided so as to communicate the inside of the crankcase 15 and the intake manifold 28, which is a portion under positive pressure in the intake passage 21. Also, the second check valve 46 installed in the second passage R2 is configured to allow the flow of gas from the intake passage 21 through the second passage R2 toward the inside of the crankcase 15. Therefore, air is introduced into the inside of the crankcase 15 through the second passage R2 at this time. Then, due to the introduced positive-pressure air, the blow-by gas in the crankcase 15 is sent out to the intake passage 21 through the third passage R3.

[0020] In addition, when more gas flows into the crankcase 15 through the second passage R2 than the flow rate of the gas sent to the intake passage 21 through the third passage R3, the gas accumulates in the crankcase 15 and the internal pressure rises. When the internal pressure of the crankcase 15 increases, oil leakage and leakage of blow-by gas to the outside are likely to occur. Oil leakage is a phenomenon in which oil flows into the combustion chamber 17 through the gap between the piston 13 and the cylinder 12. On the other hand, in the blow-by gas reflux device of the present embodiment, the minimum flow passage area of the second passage R2 is smaller than the minimum flow passage area of the third passage R3. That is, the third passage R3 is configured to allow more gas to flow than the second passage R2. Therefore, it is difficult for the internal pressure of the crankcase 15 to increase due to the accumulation of gas as described above.

[0021] According to the blow-by gas reflux device of the present embodiment described above, the following effects can be obtained. (1) The blow-by gas reflux device of the present embodiment includes a first passage R1, a second passage R2, a third passage R3, a first check valve 42, and a second check valve 46. The first passage R1 is a passage that communicates a portion downstream of the throttle valve 27 in the intake passage 21 with the inside of the crankcase 15. The second passage R2 is a passage that communicates a portion downstream of the intercooler 26 in the intake passage 21 with the inside of the crankcase 15. The third passage R3 is a passage that communicates a portion upstream of the compressor 24 in the intake passage 21 with the inside of the crankcase 15. The first check valve 42 is a valve that allows the flow of gas from the inside of the crankcase 15 through the first passage R1 to the intake passage 21, while restricting the flow of gas from the intake passage 21 through the first passage R1 to the inside of the crankcase 15. The second check valve 46 is a valve that allows the flow of gas from the intake passage 21 through the second passage R2 to the inside of the crankcase 15, while restricting the flow of gas from the inside of the crankcase 15 through the second passage R2 to the intake passage 21. Such a blow-by gas reflux device can ventilate the blow-by gas in the crankcase 15 during both the natural intake operation and the supercharging operation of the supercharged engine 10.

[0022] (2) Now, consider connecting the intake passage 21 side of the second passage R2 to the portion of the intake passage 21 upstream of the intercooler 26 and downstream of the compressor 24. In this case as well, air can be introduced into the crankcase 15 through the second passage R2 during supercharging operation. However, in this case, high-temperature air that has not been cooled by the intercooler 26 is introduced into the crankcase 15. In contrast, in the blow-by gas recirculation device of this embodiment, the second passage R2 is configured to connect the portion of the intake passage 21 downstream of the intercooler 26 with the inside of the crankcase 15. Therefore, in the blow-by gas recirculation device of this embodiment, air cooled by the intercooler 26 can be introduced into the crankcase 15 during supercharging operation. Because low-temperature, high-density air is introduced, the blow-by gas inside the crankcase 15 can be ventilated more efficiently than when high-temperature, low-density air is introduced.

[0023] (3) Consider a configuration in which the second passage R2 and the second check valve 46 are omitted from the blow-by gas recirculation device of this embodiment. This configuration is commonly used as a blow-by gas recirculation device for naturally aspirated engines. In this case, the third passage R3 is used only as an air introduction passage into the crankcase 15. In contrast, the blow-by gas recirculation device of this embodiment is equipped with a second passage R2 that connects the portion of the intake passage 21 downstream of the intercooler 26 to the inside of the crankcase 15. Furthermore, the blow-by gas recirculation device of this embodiment is equipped with a second check valve 46 that opens during supercharged operation to allow the second passage R2 to be used as an air introduction passage, while closing during naturally aspirated operation to close the second passage R2. By installing these second passage R2 and second check valve 46, the third passage R3 is assigned the functions of an air introduction passage during naturally aspirated operation and a blow-by gas discharge passage during supercharged operation. Therefore, a blow-by gas recirculation system can be realized with a relatively simple configuration that can perform ventilation during both naturally aspirated and turbocharged operation.

[0024] (4) In the blow-by gas recirculation device of this embodiment, during supercharging operation, air is introduced into the crankcase 15 through the second passage R2, and blow-by gas inside the crankcase 15 is released into the intake passage 21 through the third passage R3. At this time, if the amount of blow-by gas released from the crankcase 15 is less than the amount of air introduced into the crankcase 15, the internal pressure of the crankcase 15 will rise. In the blow-by gas recirculation device of this embodiment, the second passage R2 is configured as a passage having a minimum flow area smaller than the minimum flow area of ​​the third passage R3. As a result, gas flows more easily through the third passage R3 than through the second passage R2. Therefore, it is possible to suppress the accumulation of gas in the crankcase 15 and the rise in its internal pressure during supercharging operation.

[0025] (5) In the blow-by gas recirculation device of this embodiment, separators for separating oil mist are installed in the first passage R1 and the third passage R3, which function as blow-by gas discharge passages during natural intake operation and supercharging operation, respectively. This makes it possible to suppress the mixing of oil into the intake air in accordance with the recirculation of blow-by gas.

[0026] (6) In the blow-by gas recirculation device of this embodiment, a second check valve 46 is installed at the connection point of the second passage R2 to the crankcase 15. The second check valve 46 is configured to restrict the flow of gas from inside the crankcase 15 to the second PCV hose 45. Therefore, even if the second passage R2 is damaged due to the second PCV hose 45 rupturing or coming off the connector, blow-by gas inside the crankcase 15 will not be easily released into the outside air. Also, if the second passage R2 is damaged, the intake manifold 28 will be opened to the outside air. When the intake manifold 28 is opened to the outside air, the intake pressure and intake airflow rate will change immediately. Therefore, installing the second check valve 46 at the connection point to the crankcase 15 will enable easy and rapid detection of damage to the second passage R2.

[0027] (7) The function of the first check valve 42 is the same as that of the PCV valve used in the blow-by gas recirculation system of a naturally aspirated engine. Therefore, an existing PCV valve can be used as the first check valve 42. In addition, the functions of the first check valve 42 and the second check valve 46 are the same except for the direction of the gas flow that is allowed or restricted. Therefore, it is possible to use the first check valve 42 and the second check valve 46 as common parts, or to reuse much of the design of the first check valve 42 in the design of the second check valve 46.

[0028] <Other Embodiments> This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0029] In the above embodiment, the intake side of the second passage R2 was connected to the intake manifold 28. The intake side of the second passage R2 may be connected to a part of the intake passage 21 other than the intake manifold 28, as long as it is downstream of the intercooler 26. For example, the intake side of the second passage R2 may be connected to the part of the intake passage 21 between the intercooler 26 and the throttle valve 27.

[0030] A third passage R3 may be configured as a passage connecting the inside of the crankcase 15 and the intake passage 21 without passing through the valve chamber 20. For example, Figure 4 shows a third passage R3 configured by a third PCV hose 52 connecting the crankcase 15 and the intake passage 21. The crankcase 15 side of the third PCV hose 52 is connected to the cylinder block 11, and the intake side is connected to the portion of the intake passage 21 between the air cleaner 23 and the compressor 24. In Figure 4, a second separator 53 for separating oil mist is installed in the middle of the third PCV hose 52. This second separator 53 is fixed to the outer wall of the cylinder block 11.

[0031] The second check valve 46 may be installed at the connection point between the second passage R2 and the intake passage 21, or in the middle of the second passage R2. A second passage R2 may be configured as a passage connecting the inside of the crankcase 15 and the intake passage 21 via the valve train chamber 20. Figure 4 shows an example of such a configuration of the second passage R2. In Figure 4, the second passage R2 is configured as a passage connecting the inside of the crankcase 15 and the intake manifold 28 via the oil return passage 47, the valve train chamber 20, the second PCV hose 50, and the second check valve 46. Both ends of the second PCV hose 50 in Figure 4 are connected to the head cover 16A and the intake manifold 28, respectively. In the case of Figure 4, the second check valve 46 is installed at the connection point of the second PCV hose 50 to the intake manifold 28.

[0032] In the blow-by gas recirculation device of the above embodiment, two separators, a head-side separator 41 and a block-side separator 44, were provided as the first separator for separating oil mist from the gas flowing through the first passage R1. The number of separators constituting the first separator may be changed as appropriate. In addition, the second separators 48 and 53 for separating oil mist from the gas flowing through the third passage R3 may be composed of multiple separators. If it is sufficient to treat the oil mist in the blow-by gas by burning it in the combustion chamber 17, these separators may be omitted.

[0033] The second passage R2 may be configured as a passage having the same minimum flow area as the third passage R3, or as a passage having a minimum flow area larger than the third passage R3. In such cases, by separately providing a mechanism in the supercharged engine 10 to suppress the rise in internal pressure of the crankcase 15, it is possible to suppress the increase in oil rise and blow-by gas leakage that occur in response to the rise in internal pressure.

[0034] • Parts or all of the first PCV hose 43, the second PCV hoses 45 and 50, and the third PCV hoses 49 and 52 may be replaced with metal piping. The blow-by gas recirculation device of the above embodiment can also be applied to turbocharged engines other than hydrogen engines, such as gasoline engines and diesel engines.

[0035] In the case of an engine with multiple banks, such as a V-type engine, and a compressor, the blow-by gas recirculation device of the above embodiment may be provided individually for each bank. [Explanation of symbols]

[0036] 10 Supercharged engine 11 Cylinder block 12 cylinders 13 pistons 14 Oil pan 15 Crankcase 16 Cylinder head 16A Headcover 17 Combustion chamber 18 intake ports 19 Exhaust Ports 20 Valve chamber 21 Intake passage 22 Exhaust passage 23 Air Cleaner 24 Compressors 25 Turbine 26 Intercooler 27 Throttle valve 28 Intake Manifold 29 Injectors 30 hydrogen tanks 31 Pressure Regulating Device 40 Blow-by gas passage 41 Head-side separator 42 First check valve 43. First PCV hose 44 Block-side separator 45, 50 Second PCV hose 46. ​​Second check valve 47 Oil return passage 48, 53 Second separator 49, 52 Third PCV hose R1 1st aisle R2 2nd aisle R3 3rd aisle

Claims

1. A blow-by gas recirculation device for a hydrogen-fueled supercharged engine, comprising a compressor installed in the intake passage, an intercooler installed in the intake passage downstream of the compressor, and a throttle valve installed in the intake passage downstream of the intercooler, which recirculates blow-by gas from inside the crankcase of the engine into the intake passage, A first passage connects the portion of the intake passage downstream of the throttle valve to the inside of the crankcase, A second passage connects the portion of the intake passage downstream of the intercooler with the inside of the crankcase, A third passage connects the portion of the intake passage upstream of the compressor with the inside of the crankcase, A first check valve that allows the flow of gas from the inside of the crankcase through the first passage to the intake passage, while restricting the flow of gas from the intake passage through the first passage to the inside of the crankcase, A second check valve that allows gas to flow from the intake passage to the inside of the crankcase through the second passage, while restricting gas flow from the inside of the crankcase to the intake passage through the second passage, A blow-by gas recirculation device equipped with the following features.

2. The blow-by gas recirculation device according to claim 1, wherein the minimum flow area of ​​the second passage is smaller than the minimum flow area of ​​the third passage.

3. A blow-by gas recirculation device according to claim 1, comprising: a first separator for separating oil mist from the gas flowing through the first passage; and a second separator for separating oil mist from the gas flowing through the third passage.

4. The blow-by gas recirculation device according to claim 1, wherein the second check valve is installed in the portion of the second passage that connects to the crankcase.

5. The blow-by gas recirculation device according to claim 1, wherein the second passage connects the portion of the intake passage downstream of the throttle valve to the inside of the crankcase.

Images