Blow-by gas recirculation device
The blow-by gas reflux device addresses ventilation inefficiencies in conventional systems by using three passages and check valves to manage blow-by gas effectively during both naturally aspirated and supercharged engine operations, enhancing ventilation efficiency and preventing crankcase pressure increases.
Patent Information
- Application Number
- JP2023145280
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2023-09-07
- Publication Date
- 2025-03-19
- Estimated Expiration
- 2043-09-07
AI Technical Summary
Conventional blow-by gas reflux devices for supercharged engines have inefficiencies in ventilation, particularly during naturally aspirated operation, and are unable to effectively manage blow-by gas during both naturally aspirated and supercharged operations.
A blow-by gas reflux device with three passages (R1, R2, R3) and check valves that allow for bidirectional gas flow between the crankcase and the intake passage, enabling efficient ventilation during both naturally aspirated and supercharged engine operations.
The device improves ventilation efficiency of blow-by gas in supercharged engines, allowing for effective gas management during both naturally aspirated and supercharged operations, thereby preventing internal pressure increases in the crankcase.
Smart Images
Figure 2025038578000001_ABST
Abstract
Description
[Technical field]
[0001] The present invention relates to a blow-by gas recirculation device. [Background technology]
[0002] A device described in Patent Document 1 is known as a blow-by gas treatment device for a supercharged engine. This blow-by gas treatment device has an air introduction passage that connects a portion of the intake passage downstream of the compressor and upstream of the intercooler with the inside of the crankcase. This blow-by gas treatment device also has a return passage that connects a portion of the intake passage upstream of the compressor with the inside of the crankcase. This blow-by gas treatment device ventilates the blow-by gas by sending fresh air pressurized by the compressor through the air introduction passage into the inside of the crankcase during supercharged operation of the supercharged engine. [Prior art documents] [Patent documents]
[0003] [Patent Document 1] JP 2006-46244 A Summary of the Invention [Problem to be solved by the invention]
[0004] The above-mentioned conventional blow-by gas recirculation device still has room for improvement in terms of improving ventilation efficiency, for example, ventilation cannot be performed during natural aspiration operation. [Means for solving the problem]
[0005] The blow-by gas recirculation device that solves the above problem is a blow-by gas recirculation device for a supercharged engine including a compressor installed in an intake passage, an intercooler installed in a portion of the intake passage downstream of the compressor, and a throttle valve installed in a portion of the intake passage downstream of the intercooler, the blow-by gas recirculation device recirculating blow-by gas inside a crankcase of the supercharged engine to the intake passage, the blow-by gas recirculation device including a first passage that connects a portion of the intake passage downstream of the throttle valve with the inside of the crankcase, and a second passage that connects a portion of the intake passage downstream of the intercooler with the intake passage downstream of the intercooler. the intake passage includes a second passage communicating with the interior of the crankcase; a third passage communicating between a portion of the intake passage upstream of the compressor and the interior of the crankcase; a first check valve that allows gas to flow from the interior of the crankcase to the intake passage through the first passage, while restricting gas flow from the intake passage to the interior of the crankcase through the first passage; and a second check valve that allows gas to flow from the intake passage to the interior of the crankcase through the second passage, while restricting gas flow from the interior of the crankcase to the intake passage through the second passage. Effect of the Invention
[0006] The above-mentioned blow-by gas recirculation device has the effect of improving the ventilation efficiency of blow-by gas in a supercharged engine. [Brief description of the drawings]
[0007] [Figure 1] 1 is a diagram showing a schematic configuration of an embodiment of a blow-by gas recirculation device; [Diagram 2] 5A and 5B are diagrams illustrating a state of the blow-by gas recirculation device in a natural intake region. [Diagram 3] FIG. 4 is a diagram showing a state of the blow-by gas recirculation device in a supercharging region. [Figure 4] FIG. 6 is a diagram illustrating a configuration of a blow-by gas recirculation device according to another embodiment of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0008] Hereinafter, one embodiment of the blow-by gas recirculation device will be described in detail with reference to Figs. <Supercharged engine configuration> First, the configuration of a supercharged engine 10 that employs the blow-by gas recirculation device of this embodiment will be described with reference to Fig. 1. The supercharged engine 10 shown in Fig. 1 is a hydrogen engine that uses hydrogen as fuel. Note that in a hydrogen engine, combustible hydrogen may be contained in the blow-by gas. For this reason, a hydrogen engine is required to have a higher ventilation performance for the blow-by gas than a gasoline engine or a diesel engine.
[0009] The supercharged engine 10 includes a cylinder block 11. A plurality of cylinders 12 are formed inside the cylinder block 11. FIG. 1 shows only one of the plurality of cylinders 12. A piston 13 is accommodated in each cylinder 12 so that the piston 13 can freely reciprocate. 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 attached to the lower portion of the cylinder block 11. A crankcase 15 is formed in a portion of the cylinder block 11 below the cylinder 12. A cylinder head 16 is attached to the upper portion of the cylinder block 11. An intake port 18 and an exhaust port 19 are formed in the cylinder head 16 for each cylinder 12. A head cover 16A is attached to the upper side of the cylinder head 16. A valve train chamber 20 for accommodating a valve train is formed inside the upper portion of the cylinder head 16 covered by the head cover 16A.
[0010] The supercharged engine 10 includes an intake passage 21, which is an introduction passage for air to the combustion chamber 17, and an exhaust passage 22, which is an exhaust passage for exhaust gas from the combustion chamber 17. An air cleaner 23 for filtering dust and the like in the air is provided in the intake passage 21. A compressor 24 is provided in a portion of the intake passage 21 downstream of the air cleaner 23. The compressor 24 constitutes a turbocharger together with a turbine 25 provided in the exhaust passage 22. An intercooler 26 is provided in a portion of the intake passage 21 downstream of the compressor 24. The intercooler 26 is a heat exchanger for cooling air that has become hot due to compression by the compressor 24. A throttle valve 27 is provided in a portion of 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 into intake manifolds 28 provided downstream of a throttle valve 27 for each cylinder 12. 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 regulator 31. The pressure regulator 31 regulates the pressure of hydrogen in the hydrogen tank 30 and supplies it to the injector 29. The injector 29 injects hydrogen into air that is used for combustion in the combustion chamber 17. In the case of FIG. 1, the injector 29 is installed so as to inject hydrogen into the intake port 18, but the injector 29 may also be installed so as to inject hydrogen into the combustion chamber 17.
[0012] <Configuration of the blow-by gas recirculation device> Next, the configuration of the blow-by gas recirculation device of this embodiment will be described with reference to Fig. 1. The blow-by gas recirculation device has three passages, a first passage R1, a second passage R2, and a third passage R3, which communicate between the crankcase 15 and the intake passage 21.
[0013] The first passage R1 is a passage that communicates the portion of the intake passage 21 downstream of the throttle valve 27 with the inside of the crankcase 15. The first passage R1 is composed 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 in the blow-by gas flowing through the first passage R1. The head-side separator 41 is attached to the inside of the head cover 16A. The blow-by gas passage 40 is a passage that passes through the inside of the cylinder block 11 and the cylinder head 16 and connects the inside of the crankcase 15 with the head-side separator 41. The block-side separator 44 is provided in a part 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 with the intake manifold 28. The first check valve 42 is a valve that allows gas to flow from the inside of the crankcase 15 to the intake passage 21 through the first passage R1, while restricting gas flow from the intake passage 21 to the inside of the crankcase 15 through the first passage R1. The first check valve 42 is disposed at a connection portion 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 a first separator that separates oil mist in the gas flowing through the first passage R1.
[0014] The second passage R2 is a passage that communicates a portion of the intake passage 21 downstream of the intercooler 26 with 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 and the intake manifold 28. The second check valve 46 is a valve that allows gas to flow from the intake passage 21 to the inside of the crankcase 15 through the second passage R2, while restricting gas flow 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 a connection portion 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 is composed 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 to the crankcase 15 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, and also functions as a passage for distributing gas between the valve train chamber 20 and the crankcase 15. The second separator 48 is a separator that separates oil mist in 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 a portion of the intake passage 21 downstream of the air cleaner 23 and upstream of the compressor 24 to the second separator 48.
[0016] The second passage R2 in the blow-by gas recirculation device of this embodiment 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 flow area of the gas is smallest. This relationship of minimum flow areas can be realized, for example, by using a hose with a smaller diameter than the third PCV hose 49 as the second PCV hose 45. Alternatively, the above relationship can be realized by providing a throttle in the middle of the second passage R2, for example.
[0017] <Actions and Effects of the Embodiment> The operation and effect of this embodiment will be described with reference to Figures 2 and 3. The outline arrows shown in Figures 2 and 3 indicate the direction of air flow in the blow-by gas recirculation device. The hatched arrows shown in Figure 2 and Figure 3, which will be described later, indicate the direction of blow-by gas flow in the blow-by gas recirculation device.
[0018] FIG. 2 shows the state of the blow-by gas recirculation device during natural aspirated operation. During natural aspirated operation, the inside of the intake manifold 28 is at negative pressure, that is, at a pressure lower than atmospheric pressure. The inside of the crankcase 15 is connected to the intake manifold 28 through the first passage R1. Furthermore, the first check valve 42 installed in the first passage R1 is configured to allow gas to flow from the inside of the crankcase 15 to the intake passage 21 through the first passage R1. On the other hand, the inside of the crankcase 15 is connected to a portion of the intake passage 21 upstream of the compressor 24 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] FIG. 3 shows the state of the blow-by gas recirculation device during supercharging operation. During supercharging operation, the portion of the intake passage 21 downstream of the compressor 24 is under positive pressure, i.e., under pressure higher than atmospheric pressure. The second passage R2 is provided to communicate the inside of the crankcase 15 with the intake manifold 28, which is the portion of the intake passage 21 that is under positive pressure. The second check valve 46 provided in the second passage R2 is configured to allow gas to flow from the intake passage 21 through the second passage R2 toward the inside of the crankcase 15. Therefore, air is introduced into the crankcase 15 through the second passage R2. The introduced positive pressure air sends the blow-by gas in the crankcase 15 to the intake passage 21 through the third passage R3.
[0020] In addition, if the amount of gas flowing into the crankcase 15 through the second passage R2 is greater than the amount of gas sent to the intake passage 21 through the third passage R3, the gas will accumulate in the crankcase 15, causing the internal pressure to rise. When the internal pressure of the crankcase 15 increases, oil flow and leakage of blow-by gas to the outside are likely to occur. Oil flow 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 blow-by gas recirculation device of this embodiment, the minimum flow area of the second passage R2 is smaller than the minimum flow 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, the internal pressure of the crankcase 15 is less likely to increase due to the accumulation of gas as described above.
[0021] According to the blow-by gas recirculation device of the present embodiment described above, the following effects can be achieved. (1) The blow-by gas recirculation device of this 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 connects a portion of the intake passage 21 downstream of the throttle valve 27 with the inside of the crankcase 15. The second passage R2 is a passage that connects a portion of the intake passage 21 downstream of the intercooler 26 with the inside of the crankcase 15. The third passage R3 is a passage that connects a portion of the intake passage 21 upstream of the compressor 24 with the inside of the crankcase 15. The first check valve 42 is a valve that allows gas to flow from the inside of the crankcase 15 to the intake passage 21 through the first passage R1, while restricting gas flow from the intake passage 21 to the inside of the crankcase 15 through the first passage R1. The second check valve 46 is a valve that allows gas to flow from the intake passage 21 to the inside of the crankcase 15 through the second passage R2, while restricting gas flow from the inside of the crankcase 15 to the intake passage 21 through the second passage R2. Such a blow-by gas recirculation device can ventilate the blow-by gas in the crankcase 15 whether the supercharged engine 10 is operating in a naturally aspirated state or in a supercharged state.
[0022] (2) Here, consider connecting the intake passage 21 side of the second passage R2 to a portion of the intake passage 21 upstream of the intercooler 26 and downstream of the compressor 24. In this case, air can 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 this embodiment, the second passage R2 is configured to communicate 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. Since low-temperature, high-density air is introduced, the blow-by gas in the crankcase 15 can be ventilated more efficiently than in the case of introducing high-temperature, low-density air.
[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 often used as a blow-by gas recirculation device for a naturally aspirated engine. In this case, the third passage R3 is used only as an air introduction path to the inside of the crankcase 15. In contrast, the blow-by gas recirculation device of this embodiment has the second passage R2 that communicates the part of the intake passage 21 downstream of the intercooler 26 with the inside of the crankcase 15. Furthermore, the blow-by gas recirculation device of this embodiment has the second check valve 46 that opens during supercharging operation to use the second passage R2 as an air introduction path, and closes during natural aspirating operation to close 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 path during natural aspirating operation and as a blow-by gas discharge path during supercharging operation. Therefore, it is possible to realize a blow-by gas recirculation device that can perform ventilation during both natural aspirated operation and supercharged operation with a relatively simple configuration.
[0024] (4) In the blow-by gas recirculation device of this embodiment, air is introduced into the crankcase 15 through the second passage R2 during supercharging operation, and the blow-by gas in the crankcase 15 is discharged to the intake passage 21 through the third passage R3. At this time, if the amount of blow-by gas discharged from the crankcase 15 is smaller than the amount of air introduced into the crankcase 15, the internal pressure of the crankcase 15 increases. 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. This makes it easier for gas to flow through the third passage R3 than the second passage R2. Therefore, it is possible to suppress the internal pressure of the crankcase 15 from increasing due to the gas remaining in the crankcase 15 during supercharging operation.
[0025] (5) In the blow-by gas recirculation device of this embodiment, a separator for separating oil mist is provided in the first passage R1 and the third passage R3, which function as the discharge passages for the blow-by gas during the natural aspirated operation and the supercharged operation, respectively. This makes it possible to suppress the mixing of oil into the intake air due to the recirculation of the blow-by gas.
[0026] (6) In the blow-by gas recirculation device of this embodiment, the second check valve 46 is provided at the connection portion 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 by the second PCV hose 45 being torn or coming off the connector, the blow-by gas inside the crankcase 15 is less likely to be released to the outside air. Furthermore, 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, the installation of the second check valve 46 at the connection portion to the crankcase 15 leads to the realization of easy and prompt detection of damage to the second passage R2.
[0027] (7) The function of the first check valve 42 is the same as that of a PCV valve used in a blow-by gas recirculation system for 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 gas flow that is allowed and restricted. Therefore, it is possible to use the first check valve 42 and the second check valve 46 as common parts, and to reuse much of the design of the first check valve 42 for the design of the second check valve 46.
[0028] <Other embodiments> This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that there is no technical contradiction.
[0029] In the above embodiment, the intake side of the second passage R2 is connected to the intake manifold 28. The intake side of the second passage R2 may be connected to a portion of the intake passage 21 downstream of the intercooler 26 other than the intake manifold 28. For example, the intake side 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.
[0030] The third passage R3 may be configured as a passage that communicates between the inside of the crankcase 15 and the intake passage 21 without passing through the valve train chamber 20. For example, FIG. 4 shows the third passage R3 configured by a third PCV hose 52 that connects 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 a portion of the intake passage 21 between the air cleaner 23 and the compressor 24. In the case of FIG. 4, a second separator 53 that separates oil mist is installed midway along the third PCV hose 52. This second separator 53 is fixed to the outer wall of the cylinder block 11.
[0031] A second check valve 46 may be provided at the connection portion of the second passage R2 to the intake passage 21 or midway through the second passage R2. The second passage R2 may be configured as a passage that communicates the inside of the crankcase 15 with the intake passage 21 via the valve train chamber 20. FIG. 4 shows an example of such a configuration of the second passage R2. The second passage R2 in FIG. 4 is configured as a passage that communicates the inside of the crankcase 15 with the intake manifold 28 via an 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 FIG. 4 are connected to the head cover 16A and the intake manifold 28, respectively. The second check valve 46 in the case of FIG. 4 is installed at a connection portion of the second PCV hose 50 to the intake manifold 28.
[0032] In the case of the blow-by gas recirculation device of the above embodiment, two separators, the head side separator 41 and the block side separator 44, are provided as the first separator for separating the oil mist in the gas flowing through the first passage R1. The number of separators constituting the first separator may be changed as appropriate. Also, the second separators 48, 53 for separating the oil mist in the gas flowing through the third passage R3 may be composed of multiple separators. When it is only necessary to treat the oil mist in the blow-by gas by burning it in the combustion chamber 17, those 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 may be configured as a passage having a minimum flow area larger than the minimum flow area of the third passage R3. Even in such a case, by separately providing a mechanism for suppressing an increase in the internal pressure of the crankcase 15 in the supercharged engine 10, it is possible to suppress an increase in the oil flow and a leakage of blow-by gas in response to an increase in the internal pressure.
[0034] A part or all of the first PCV hose 43, the second PCV hose 45, 50, and the third PCV hose 49, 52 may be replaced with metal piping. The blow-by gas recirculation device of the above embodiment can also be applied to supercharged engines other than hydrogen engines, such as gasoline engines and diesel engines.
[0035] In the case of an engine having a plurality of banks and compressors, such as a V-type engine, the blow-by gas recirculation device of the above embodiment may be provided for each bank. [Explanation of symbols]
[0036] 10. Supercharged Engine 11 Cylinder block 12 cylinders 13 Piston 14 Oil pan 15 Crankcase 16 Cylinder head 16A Head Cover 17 Combustion chamber 18 Intake port 19 Exhaust port 20 Valve chamber 21 Intake passage 22 Exhaust passage 23 Air cleaner 24 Compressor 25 Turbine 26 Intercooler 27 Throttle valve 28 Intake manifold 29 Injector 30 Hydrogen Tank 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 3rd PCV hose R1 1st aisle R2 2nd aisle R3 3rd aisle
Claims
1. A blow-by gas recirculation device for a supercharged engine including: a compressor disposed in an 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 recirculation device recirculating blow-by gas inside a crankcase of the supercharged engine to the intake passage, a first passage communicating a portion of the intake passage downstream of the throttle valve with the inside of the crankcase; a second passage communicating a portion of the intake passage downstream of the intercooler with the inside of the crankcase; a third passage communicating a 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; a second check valve that allows gas to flow from the intake passage to the inside of the crankcase through the second passage and restricts gas to flow from the inside of the crankcase to the intake passage through the second passage; A blow-by gas recirculation device comprising:
2. 2. The blow-by gas recirculation device according to claim 1, wherein a minimum flow passage area of the second passage is smaller than a minimum flow passage area of the third passage.
3. 2. The blow-by gas recirculation device according to claim 1, further comprising: a first separator that separates oil mist in the gas flowing through the first passage; and a second separator that separates oil mist in the gas flowing through the third passage.
4. 2. The blow-by gas recirculation device according to claim 1, wherein the second check valve is disposed at a connection portion of the second passage to the crankcase.
5. 2. The blow-by gas recirculation device according to claim 1, wherein the fuel for said supercharged engine is hydrogen.
6. 2. The blow-by gas recirculation device according to claim 1, wherein the second passage connects a portion of the intake passage downstream of the throttle valve with the inside of the crankcase.
Citation Information
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