Blow-by gas backflow device

Abstract

The invention provides a blow-by gas backflow device. The blow-by gas backflow device comprises a first passage, a second passage, a third passage, a first check valve and a second check valve. The first to third passages allow a portion of the intake passage downstream of the throttle valve, a portion of the intake passage downstream of the intercooler, and a portion of the intake passage upstream of the compressor to communicate with the inside of the crankcase. In the first passage, the first check valve is configured so as to allow gas to flow from the inside of the crankcase to the intake passage, and so as to restrict the gas from flowing from the intake passage to the inside of the crankcase. In the second passage, a second check valve allows the gas to flow from the intake passage to the inside of the crankcase, and restricts the gas from flowing from the inside of the crankcase to the intake passage.

Description

Technical Field

[0001] The present disclosure relates to a blow-by gas reflow device. Background Art

[0002] As a blowby gas treatment device for a supercharged engine, there is a device described in Japanese Patent Publication No. 2006-46244. The blowby gas treatment device includes an air introduction passage that connects a portion of the intake passage downstream of the compressor and upstream of the intercooler with the interior of the crankcase. The blowby gas treatment device includes a reflux passage that connects a portion of the intake passage upstream of the compressor with the interior of the crankcase. During the supercharged operation of the supercharged engine, the blowby gas treatment device sends fresh air pressurized by the compressor into the interior of the crankcase through the air introduction passage, thereby performing ventilation of the blowby gas. Summary of the invention

[0003] Problems to be solved by the invention

[0004] In the blow-by gas recirculation device described in the above publication, ventilation cannot be performed during natural intake operation, and there is room for improvement in terms of improving ventilation efficiency.

[0005] Means for solving problems

[0006] A blow-by gas recirculation device according to a technical solution of the present disclosure is configured to recirculate blow-by gas in a crankcase of a supercharged engine to an intake passage. The supercharged engine includes: a compressor disposed in the intake passage; an intercooler disposed in a portion of the intake passage downstream of the compressor; and a throttle valve disposed in a portion of the intake passage downstream of the intercooler. The blow-by gas reflow device comprises: a first passage, which connects a portion of the intake passage downstream of the throttle valve with the interior of the crankcase; a second passage, which connects a portion of the intake passage downstream of the intercooler with the interior of the crankcase; a third passage, which connects a portion of the intake passage upstream of the compressor with the interior of the crankcase; a first check valve, which is configured to allow gas to flow from the interior of the crankcase through the first passage to the intake passage, and on the other hand, restrict gas from flowing from the interior of the crankcase through the first passage to the interior of the crankcase; and a second check valve, which is configured to allow gas to flow from the intake passage through the second passage to the interior of the crankcase, and on the other hand, restrict gas from flowing from the interior of the crankcase through the second passage to the intake passage. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a diagram schematically showing the structure of one embodiment of the blow-by gas recirculation device.

[0008] Figure 2 It indicates the area of ​​natural air intake. Figure 1 A diagram showing the status of the blowby gas reflow device.

[0009] Figure 3 It indicates the pressure in the boost area. Figure 1 A diagram showing the status of the blowby gas reflow device.

[0010] Figure 4 It is a diagram schematically showing the structure of another embodiment of the blow-by gas recirculation device. DETAILED DESCRIPTION

[0011] Below, refer to Figure 1~Figure 3 An embodiment of the blow-by gas recirculation device will be described in detail.

[0012] <Structure of supercharged engine>

[0013] Reference Figure 1 The structure of a supercharged engine 10 that uses the blow-by gas recirculation device of the present embodiment will be described. Figure 1 The supercharged engine 10 shown is a hydrogen engine that uses hydrogen as fuel. In a hydrogen engine, blow-by gas may contain combustible hydrogen. Therefore, a hydrogen engine is required to have a higher blow-by gas ventilation performance than a gasoline engine or a diesel engine.

[0014] The supercharged engine 10 includes a cylinder block 11. A plurality of cylinders 12 are formed inside the cylinder block 11. Figure 1 In the figure, only one of the multiple cylinders 12 is shown. A piston 13 is accommodated in each cylinder 12 so as to be reciprocatingly movable. A combustion chamber 17 for burning hydrogen is formed in a portion of the cylinder 12 above the piston 13. An oil pan 14 for storing oil is installed at the lower part of the cylinder body 11. A crankcase 15 is formed in a portion of the cylinder body 11 below the cylinder 12. A cylinder head 16 is installed at the upper part of the cylinder body 11. Inside the cylinder head 16, a separate intake port 18 and exhaust port 19 are formed for each cylinder 12. A cylinder head cover 16A is installed on the upper side of the cylinder head 16. A valve drive chamber 20 for accommodating a valve drive mechanism is formed on the inner side of the upper part of the cylinder head 16 covered by the cylinder head cover 16A.

[0015] The supercharged engine 10 includes an intake passage 21 for introducing air into the combustion chamber 17 and an exhaust passage 22 for discharging exhaust gas from the combustion chamber 17. An air filter 23 for filtering dust and the like in the air is provided in the intake passage 21. A compressor 24 is provided in the portion of the intake passage 21 on the downstream side of the air filter 23. The compressor 24 constitutes a turbocharger together with a turbine 25 provided in the exhaust passage 22. An intercooler 26 is provided in the portion of the intake passage 21 on the downstream side of the compressor 24. The intercooler 26 is a heat exchanger for cooling the air that has become high temperature due to compression by the compressor 24. A throttle valve 27 is provided in the portion of the intake passage 21 on the downstream side of the intercooler 26. The throttle valve 27 adjusts the flow rate of air delivered to the combustion chamber 17 through the intake passage 21. The intake passage 21 is branched for each cylinder 12 in an intake manifold 28 provided in the portion on the downstream side of the throttle valve 27. The intake manifold 28 is connected to the combustion chamber 17 via the intake port 18 .

[0016] The supercharged engine 10 includes an injector 29, a hydrogen tank 30, and a pressure regulating device 31. The pressure regulating device 31 regulates the pressure of hydrogen in the hydrogen tank 30 and supplies the hydrogen to the injector 29. The injector 29 injects hydrogen into the air used for combustion in the combustion chamber 17. Figure 1 In this case, the injector 29 is provided so as to inject hydrogen into the intake port 18 , but the injector 29 may be provided so as to inject hydrogen into the combustion chamber 17 .

[0017] <Structure of the blowby gas reflow device>

[0018] Next, refer to Figure 1 The structure of the blow-by gas recirculation device of the present embodiment will be described. The blow-by gas recirculation device includes three passages, namely, a first passage R1 , a second passage R2 , and a third passage R3 , as passages for connecting the interior of the crankcase 15 with the intake passage 21 .

[0019] The first passage R1 connects a portion of the intake passage 21 downstream of the throttle valve 27 to the interior of the crankcase 15. The first passage R1 is composed of a blow-by gas passage 40, a cylinder head side separator 41, a first check valve 42, a first PCV hose 43, and a cylinder block side separator 44. The cylinder head side separator 41 and the cylinder block side separator 44 separate the oil mist in the blow-by gas flowing in the first passage R1. The cylinder head side separator 41 is mounted on the inner side of the cylinder head cover 16A. The blow-by gas passage 40 passes through the inside of the cylinder block 11 and the cylinder head 16, connecting the inside of the crankcase 15 to the cylinder head side separator 41. The cylinder block side separator 44 is provided in a portion midway in the blow-by gas passage 40 in the cylinder block 11. The first PCV hose 43 connects the cylinder head side separator 41 to the intake manifold 28. The first check valve 42 allows gas to flow from the inside of the crankcase 15 through the first passage R1 to the intake passage 21, and restricts gas from flowing from the intake passage 21 through the first passage R1 to the inside of the crankcase 15. The first check valve 42 is provided at a connection portion of the first PCV hose 43 connected to the cylinder head side separator 41. In the present embodiment, the cylinder head side separator 41 and the cylinder block side separator 44 correspond to a first separator that separates oil mist from gas flowing in the first passage R1.

[0020] The second passage R2 allows a portion of the intake passage 21 that is downstream of the intercooler 26 to communicate with the interior of the crankcase 15. The second passage R2 has an intake-side end portion connected to the intake passage 21. The second passage R2 is composed of a second PCV hose 45 and a second check valve 46. The second PCV hose 45 connects the crankcase 15 to the intake manifold 28. The second check valve 46 allows gas to flow from the intake passage 21 to the interior of the crankcase 15 through the second passage R2, and on the other hand, restricts gas from flowing from the interior of the crankcase 15 to the intake passage 21 through the second passage R2. The second check valve 46 is provided at a connection portion of the second PCV hose 45 that is connected to the crankcase 15.

[0021] The third passage R3 allows a portion of the intake passage 21 on the upstream side of the compressor 24 to communicate with the interior of the crankcase 15. The third passage R3 includes an oil return passage 47, a valve chamber 20, a second separator 48, and a third PCV hose 49. The oil return passage 47 allows the valve chamber 20 to communicate with the interior of the crankcase 15 through the interior 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 chamber 20 to the oil pan 14, and on the other hand, it also functions as a passage for allowing gas to flow between the valve chamber 20 and the interior of the crankcase 15. The second separator 48 is a separator that separates oil mist in the blowby gas flowing in the third passage R3. The second separator 48 is provided on the inner side of the cylinder head cover 16A. The third PCV hose 49 connects a portion of the intake passage 21 on the downstream side of the air filter 23 and on the upstream side of the compressor 24 to the second separator 48.

[0022] The second passage R2 in the blow-by gas recirculation device of the present embodiment is configured to have a minimum flow path area that is smaller than the minimum flow path area of ​​the third passage R3. The minimum flow path area refers to the flow path area of ​​the portion where the flow path area of ​​the gas is the smallest in the passage. The above relationship of the minimum flow path area can be achieved, for example, by using a hose having a smaller diameter than the third PCV hose 49 for the second PCV hose 45. The above relationship can also be achieved by providing a throttle portion in the middle of the second passage R2.

[0023] <Functions and Effects of Implementation Methods>

[0024] Reference Figure 2 and Figure 3 The operation and effects of this embodiment will be described. Figure 2 and Figure 3 The hollow arrows shown indicate the flow direction of the air in the blow-by gas recirculation device. Figure 2 and Figure 3 The black arrows shown indicate the flow direction of the blow-by gas within the blow-by gas recirculation device.

[0025] Figure 2 Indicates the state of the blow-by gas reflow device during natural intake operation. During natural intake operation, the interior of the intake manifold 28 becomes a negative pressure, that is, a pressure lower than the atmospheric pressure. The interior of the crankcase 15 is connected to the intake manifold 28 through the first passage R1. The first check valve 42 provided in the first passage R1 is configured to allow gas to flow from the interior of the crankcase 15 through the first passage R1 toward the intake passage 21. The interior of the crankcase 15 is connected to a portion of the intake passage 21 that is upstream of the compressor 24 through the third passage R3. Therefore, during natural intake operation, air is introduced into the interior 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.

[0026] Figure 3 Indicates the state of the blow-by gas reflow device during supercharging operation. During supercharging operation, the portion of the intake passage 21 that is downstream of the compressor 24 becomes positive pressure, that is, a pressure higher than atmospheric pressure. The second passage R2 is provided so that the interior of the crankcase 15 is connected to a part of the portion of the intake passage 21 that becomes positive pressure, that is, the intake manifold 28. The second check valve 46 provided in the second passage R2 is configured to allow gas to flow from the intake passage 21 to the interior of the crankcase 15 through the second passage R2. Therefore, air is introduced into the interior of the crankcase 15 during supercharging operation through the second passage R2. The blow-by gas in the crankcase 15 is sent to the intake passage 21 through the third passage R3 by the introduced positive pressure air.

[0027] If a gas having a larger flow rate than the gas delivered to the intake passage 21 through the third passage R3 flows into the crankcase 15 through the second passage R2, the gas is retained in the crankcase 15 and the internal pressure rises. When the internal pressure of the crankcase 15 rises, oil rise and leakage of blowby gas to the outside are likely to occur. Oil rise is a phenomenon in which oil flows into the combustion chamber 17 through the gap between the piston 13 and the cylinder 12. In contrast, in the blowby gas recirculation device of the present embodiment, the minimum flow path area of ​​the second passage R2 is smaller than the minimum flow path 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 to generate a rise in the internal pressure of the crankcase 15 caused by the retention of gas as described above.

[0028] According to the blow-by gas recirculation device of the present embodiment described above, the following effects can be achieved.

[0029] (1) The blow-by gas recirculation 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 allows a portion of the intake passage 21 downstream of the throttle valve 27 to communicate with the interior of the crankcase 15. The second passage R2 allows a portion of the intake passage 21 downstream of the intercooler 26 to communicate with the interior of the crankcase 15. The third passage R3 allows a portion of the intake passage 21 upstream of the compressor 24 to communicate with the interior of the crankcase 15. The first check valve 42 allows gas to flow from the interior of the crankcase 15 to the intake passage 21 through the first passage R1, while restricting gas from flowing from the intake passage 21 to the interior of the crankcase 15 through the first passage R1. The second check valve 46 allows gas to flow from the intake passage 21 to the interior of the crankcase 15 through the second passage R2, while restricting gas from flowing from the interior of the crankcase 15 to the intake passage 21 through the second passage R2. Such a blow-by gas recirculation device can perform ventilation of the blow-by gas in the crankcase 15 both during the naturally aspirated operation and the supercharged operation of the supercharged engine 10 .

[0030] (2) Here, consider a case where the intake-side end of the second passage R2 is connected to a portion of the intake passage 21 that is upstream of the intercooler 26 and downstream of the compressor 24. In this case, air can also be introduced into the crankcase 15 through the second passage R2 during supercharging operation. However, in this case, high-temperature air before being cooled by the intercooler 26 is introduced into the crankcase 15. In contrast, in the case of the blow-by gas recirculation device of the present embodiment, the second passage R2 is configured so that a portion of the intake passage 21 that is downstream of the intercooler 26 communicates with the crankcase 15. Therefore, in the blow-by gas recirculation device of the present embodiment, air cooled by the intercooler 26 can be introduced into the crankcase 15 during supercharging operation. Therefore, since high-density air is introduced at a low temperature, the blow-by gas in the crankcase 15 can be ventilated more efficiently than in the case of introducing low-density air at a high temperature.

[0031] (3) Consider a configuration in which the second passage R2 and the second check valve 46 are omitted from the blow-by gas reflow device of the present embodiment. In this case, the third passage R3 is used only as a passage for introducing air into the crankcase 15. In contrast, the blow-by gas reflow device of the present embodiment includes the second passage R2 that communicates the portion of the intake passage 21 downstream of the intercooler 26 with the interior of the crankcase 15. Furthermore, the blow-by gas reflow device of the present embodiment includes the second check valve 46 that opens during supercharging operation to use the second passage R2 as an air introduction passage, and closes during natural intake operation to block the second passage R2. By providing the second passage R2 and the second check valve 46, the third passage R3 functions as an air introduction passage during natural intake operation and as a blow-by gas discharge passage during supercharging operation. Therefore, a blow-by gas reflow device that can perform ventilation of the blow-by gas in the crankcase 15 both during natural intake operation and supercharging operation can be realized with a relatively simple structure.

[0032] (4) In the blow-by gas recirculation device of the present embodiment, during supercharging operation, air is introduced into the interior of the crankcase 15 through the second passage R2, and the blow-by gas inside the crankcase 15 is released into the intake passage 21 through the third passage R3. At this time, when the amount of blow-by gas released from the interior of the crankcase 15 is smaller than the amount of air introduced into the interior of the crankcase 15, the internal pressure of the crankcase 15 rises. In the blow-by gas recirculation device of the present embodiment, the second passage R2 has a minimum flow path area smaller than the minimum flow path area of ​​the third passage R3. As a result, the third passage R3 makes it easier for gas to flow than the second passage R2. Therefore, it is possible to suppress the internal pressure of the crankcase 15 from rising due to gas stagnation in the crankcase 15 during supercharging operation.

[0033] (5) In the blow-by gas recirculation device of the present embodiment, separators for separating oil mist are provided in the first passage R1 and the third passage R3, which function as blow-by gas release passages during natural intake operation and supercharged operation, respectively. This can suppress the mixing of oil into the intake air caused by the recirculation of blow-by gas.

[0034] (6) In the blow-by gas reflow device of the present embodiment, a second check valve 46 is provided at the connection portion of the second passage R2 connected to the crankcase 15. The second check valve 46 is configured to restrict the flow of gas from the inside of the crankcase 15 to the second PCV hose 45. Therefore, even if the second PCV hose 45 is broken or detached from the connector and the second passage R2 is damaged, the blow-by gas inside the crankcase 15 is difficult to be released to the outside. In addition, when the second passage R2 is damaged, the intake manifold 28 is opened to the outside air. When the intake manifold 28 is opened to the outside air, the intake pressure and the intake flow rate change immediately. Therefore, by providing the second check valve 46 at the connection portion of the second passage R2 connected to the crankcase 15, damage to the second passage R2 can be easily and quickly detected.

[0035] (7) The function of the first check valve 42 is common to that of the PCV valve used in the blow-by gas recirculation device of the naturally aspirated engine. Therefore, the first check valve 42 can adopt an existing PCV valve. In addition, the functions of the first check valve 42 and the second check valve 46 are common except for the direction of the flow of the gas allowed or restricted. Therefore, the first check valve 42 and the second check valve 46 can be made into a common component, or most of the design of the first check valve 42 can also be used for the design of the second check valve 46.

[0036] <Other Implementation Methods>

[0037] This embodiment can be implemented by being modified as follows. This embodiment and the following modified examples can be implemented in combination with each other within the range that there is no technical contradiction.

[0038] In the above embodiment, the intake side end of the second passage R2 is connected to the intake manifold 28. The intake side end of the second passage R2 may be connected to a portion of the intake passage 21 downstream of the intercooler 26, or may be connected to a portion other than the intake manifold 28. For example, the intake side end of the second passage R2 may be connected to a portion of the intake passage 21 between the intercooler 26 and the throttle valve 27.

[0039] The third passage R3 may be configured to allow the interior of the crankcase 15 to communicate with the intake passage 21 without passing through the valve operating chamber 20. For example, Figure 4The third passage R3 is shown as a third PCV hose 52 connecting the crankcase 15 and the intake passage 21. One end of the third PCV hose 52 is connected to the cylinder block 11, and the other end is connected to the portion between the air filter 23 and the compressor 24 in the intake passage 21. Figure 4 In the supercharged engine 10, a second separator 53 for separating oil mist is provided in the middle of the third PCV hose 52. The second separator 53 is fixed to the outer wall of the cylinder block 11.

[0040] A second check valve 46 may be provided at a portion of the second passage R2 connected to the intake passage 21 or in the middle of the second passage R2.

[0041] The second passage R2 may be configured so that the interior of the crankcase 15 communicates with the intake passage 21 via the valve operating chamber 20. Figure 4 2 shows a structural example of such a second passage R2. Figure 4 The second passage R2 allows the interior of the crankcase 15 to communicate with the intake manifold 28 via the oil return passage 47 , the valve operating chamber 20 , the second PCV hose 50 , and the second check valve 46 . Figure 4 Both ends of the second PCV hose 50 are connected to the cylinder head cover 16A and the intake manifold 28, respectively. Figure 4 The second check valve 46 in the case of FIG. 4 is provided at a connection portion of the second PCV hose 50 to the intake manifold 28 .

[0042] In the case of the blow-by gas reflow device of the above-mentioned embodiment, two separators, namely the cylinder head side separator 41 and the cylinder block side separator 44, are provided as the first separator for separating the oil mist in the gas flowing in 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 the oil mist in the gas flowing in the third passage R3 may be constituted by a plurality of separators. In the case where the oil mist in the blow-by gas is merely combusted in the combustion chamber 17 for treatment, these separators may be omitted.

[0043] The second passage R2 may have the same minimum passage area as the minimum passage area of ​​the third passage R3, or may have a minimum passage area larger than the minimum passage area of ​​the third passage R3. In this case, by separately providing a mechanism for suppressing the increase in the internal pressure of the crankcase 15 in the supercharged engine 10, it is also possible to suppress an increase in oil rise corresponding to the increase in internal pressure, leakage of blowby gas, and the like.

[0044] The first PCV hose 43 , the second PCV hoses 45 , 50 , and the third PCV hoses 49 , 52 may be partially or entirely replaced with metal pipes.

[0045] The blow-by gas recirculation device of the above-described embodiment can also be applied to supercharged engines other than hydrogen engines, such as gasoline engines and diesel engines.

[0046] In an engine including a plurality of cylinder groups and compressors such as a V-type engine, the blow-by gas recirculation device of the above embodiment may be provided individually for each cylinder group.

Claims

1. A blow-by gas recirculation device, configured to recirculate blow-by gas in a crankcase of a supercharged engine to an intake passage, wherein: The supercharged engine comprises: A compressor, disposed in the air intake passage; an intercooler provided in a portion of the intake passage downstream of the compressor; and a throttle valve provided in a portion of the intake passage downstream of the intercooler, The blow-by gas reflow device comprises: a first passage that allows a portion of the intake passage that is downstream of the throttle valve to communicate with the interior of the crankcase; a second passage that allows a portion of the intake passage that is downstream of the intercooler to communicate with the interior of the crankcase; a third passage that allows a portion of the intake passage upstream of the compressor to communicate with the interior of the crankcase; a first check valve configured to allow gas to flow from the interior of the crankcase through the first passage to the intake passage, and to restrict gas from flowing from the intake passage through the first passage to the interior of the crankcase; and The second check valve is configured to allow gas to flow from the intake passage through the second passage into the crankcase, while restricting gas from flowing from the crankcase through the second passage into the intake passage.

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

3. The blow-by gas reflow device according to claim 1, wherein: The blow-by gas recirculation device includes: a first separator configured to separate oil mist in the gas flowing through the first passage; and a second separator configured to separate oil mist in the gas flowing through the third passage.

4. The blow-by gas reflow device according to claim 1, wherein: The second check valve is provided at a connection portion of the second passage connected to the crankcase.

5. The blow-by gas reflow device according to claim 1, wherein: The fuel for the supercharged engine is hydrogen.

6. The blow-by gas reflow device according to claim 1, wherein: The second passage allows a portion of the intake passage downstream of the throttle valve to communicate with the interior of the crankcase.

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