Gas separation device of internal combustion engine

Abstract

To inhibit gaseous fuel from being released into the atmosphere.SOLUTION: A gas separation device 60 of the present invention has a separation chamber 62 that is disposed above a first blow-by gas passage 50 and separates gaseous fuel from other gases in blow-by gas, a communication port 61 that is provided at an upper part of the first blow-by gas passage 50 for bringing the first blow-by gas passage 50 in communication with the separation chamber 62, and a return passage 65 that brings the separation chamber 62 in communication with the intake passage 30 to return the gaseous fuel separated by the separation chamber 62 to the intake passage 30. By providing the communication port 61 for bringing the first blow-by gas passage 50 in communication with the separation chamber 62 at the upper part of the first blow-by gas passage 50, the gaseous fuel can be collected in the separation chamber 62, and the gaseous fuel can be prevented from being released into the atmosphere.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a gas separation device for an internal combustion engine.

Background Art

[0002] Conventionally, an engine having a blow-by gas passage for refluxing the generated blow-by gas to the intake passage is known. Patent Document 1 discloses an engine configured such that blow-by gas reaches an upper chamber from a crankcase chamber through a vertical hole, and the blow-by gas in the upper chamber passes through the blow-by gas passage and returns to the intake passage upstream of the throttle. By returning the blow-by gas to the intake passage in this way, unburned gas in the blow-by gas can be reburned in the combustion chamber without being released to the atmosphere.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the technology disclosed in Patent Document 1, when a gaseous fuel lighter than air is used as the fuel, during engine operation, the blow-by gas that reaches the upper chamber is guided to the intake passage, which is at a negative pressure, and returns to the intake passage and can be reburned in the combustion chamber. On the other hand, when the engine is stopped, there is a problem that the gaseous fuel lighter than air among the blow-by gas that reaches the upper chamber is released to the atmosphere through a path connected to the intake passage, through the air cleaner and the intake port.

[0005] The present invention has been made in view of the above-described problems, and an object thereof is to suppress the release of gaseous fuel to the atmosphere even when a gaseous fuel lighter than air is used as the fuel.

Means for Solving the Problems

[0006] The present invention relates to a gas separation device for an internal combustion engine having a blow-by gas passage for refluxing generated blow-by gas into an intake passage, which is disposed above the blow-by gas passage and includes a separation chamber for separating gaseous fuel from other gases in the blow-by gas, a communication port provided at an upper portion of the blow-by gas passage for communicating the blow-by gas passage with the separation chamber, and a return passage for communicating the separation chamber with the intake passage to return the gaseous fuel separated by the separation chamber to the intake passage.

Advantages of the Invention

[0007] According to the present invention, even when gaseous fuel lighter than air is used as fuel, it is possible to suppress the gaseous fuel from being released to the atmosphere.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0009] The gas separation device 60 according to the embodiment of the present invention is disposed above the first blow-by gas passage 50, and includes a separation chamber 62 that separates gaseous fuel from other gases in the blow-by gas, a communication port 61 provided at an upper portion of the first blow-by gas passage 50 to communicate the first blow-by gas passage 50 with the separation chamber 62, and a return passage 65 that communicates the separation chamber 62 with the intake passage 30 to return the gaseous fuel separated by the separation chamber 62 to the intake passage 30. By providing the communication port 61 for communicating the first blow-by gas passage 50 with the separation chamber 62 at the upper portion of the first blow-by gas passage 50, the gaseous fuel can be collected in the separation chamber 62, and the release of the gaseous fuel to the atmosphere can be suppressed.

Example

[0010] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram showing a schematic configuration of a vehicle 1 including a gas separation device 60 (hereinafter referred to as the gas separation device 60) of an internal combustion engine according to the present embodiment. Note that FIG. 1 is simplified for convenience of explanation to describe the present embodiment, and it is assumed that the vehicle is provided with components that are not shown even though they are normally provided. In FIG. 1 and FIG. 2 described later, the upper side of the gas separation device 60 is indicated as "up" by an arrow. The vehicle 1 according to the embodiment includes an engine 10 as an internal combustion engine, a gas separation device 60, a control device 70, and the like.

[0011] The engine 10 performs a series of strokes including an intake stroke, a compression stroke, a combustion stroke, and an exhaust stroke. The engine 10 of the present embodiment is a multi-cylinder engine. The engine 10 includes an engine body 11, an intake system, an exhaust system, a fuel system, and the like. The engine body 11 is configured by integrally coupling a cylinder head 13 and a cylinder head cover 14 to the upper part of a cylinder block 12 in sequence. A crank chamber 15 is formed inside the cylinder block 12. A crankshaft 16 is rotatably supported in the crank chamber 15. A piston 17 is fitted into the cylinder block 12, and as the piston 17 reciprocates, the crankshaft 16 rotates via a connecting rod 18. A combustion chamber 19 is formed between the cylinder block 12 and the cylinder head 13. An ignition plug 20 is disposed on the cylinder head 13 such that its tip is positioned inside the combustion chamber 19.

[0012] An intake port 21 communicating with the combustion chamber 19 is formed in the cylinder head 13. The intake port 21 extends obliquely upward from the combustion chamber 19 toward one side wall surface of the cylinder head 13. An intake valve 22 is arranged in the intake port 21, and when the valve is opened, an air-fuel mixture is taken into the combustion chamber 19. The air-fuel mixture in the combustion chamber 19 is ignited by the ignition plug 20 and burns, causing the piston 17 to reciprocate inside the cylinder block 12.

[0013] An exhaust port 23 communicating with the combustion chamber 19 is formed in the cylinder head 13. The exhaust port 23 extends obliquely upward from the combustion chamber 19 toward the other side wall surface of the cylinder head 13. An exhaust valve 24 is arranged in the exhaust port 23, and when the valve is opened, the exhaust gas generated by burning the air-fuel mixture in the combustion chamber 19 is discharged from the combustion chamber 19. Note that the configuration of the engine body 11 is not particularly limited, and various known engines can be applied.

[0014] The engine 10 has, as an intake system, an intake passage 30, an intake port 31, an air cleaner 32, a throttle valve 33, etc. The intake passage 30 is a passage that guides the intake air taken in from outside the vehicle 1 to the combustion chamber 19 via the intake port 21. The intake passage 30 is constituted by, for example, an intake pipe. The downstream side of the intake passage 30 from the throttle valve 33 is constituted by an intake manifold. In the intake passage 30, an air intake port 31, an air cleaner 32, and a throttle valve 33 are arranged in order from the upstream side.

[0015] The air intake port 31 is an opening for taking in intake air from the outside. The air cleaner 32 purifies the intake air by removing foreign matters such as dust and dirt contained in the intake air. The throttle valve 33 adjusts the flow rate of the intake air by opening and closing. The throttle valve 33 adjusts the flow rate of the intake air based on the control by the control device 70.

[0016] The engine 10 has, as an exhaust system, an exhaust passage 40, a catalytic converter 41, and the like. The exhaust passage 40 is a passage that exhausts the exhaust gas burned in the combustion chamber 19 to the outside of the vehicle 1 via the exhaust port 23. The exhaust passage 40 is constituted by, for example, an exhaust pipe. The upstream side of the exhaust passage 40 from the catalytic converter 41 is constituted by an exhaust manifold. In the exhaust passage 40, a catalytic converter 41, a muffler (not shown), and the like are arranged in order from the upstream side. The catalytic converter 41 purifies the toxic components contained in the exhaust gas.

[0017] Further, the engine 10 has, as a fuel system, a fuel injector 45, a fuel tank, a delivery pipe, and the like. As the fuel in this embodiment, a gaseous fuel lighter than air is used. The gaseous fuel is, for example, hydrogen fuel, compressed natural gas (CNG), or the like. The fuel injector 45 injects the gaseous fuel stored in the fuel tank into the intake passage 30. The fuel injector 45 adjusts the injection amount of the gaseous fuel based on the control by the control device 70. Note that the fuel injector 45 is not limited to injecting the gaseous fuel into the intake passage 30, and may be configured to inject it into the combustion chamber 19. The fuel tank stores gaseous fuel in a compressed state. The fuel tank supplies the fuel injector 45 for each cylinder via a delivery pipe while decompressing the gaseous fuel.

[0018] In addition, the engine 10 has a first blow-by gas passage 50 and a second blow-by gas passage 55 to reflux the blow-by gas that has leaked from the combustion chamber 19 to the crank chamber 15 to the intake passage 30 via between the piston 17 and the inner peripheral surface of the cylinder bore.

[0019] The first blow-by gas passage 50 is a passage that communicates the cylinder head cover 14 and the intake passage 30. The first blow-by gas passage 50 is constituted by, for example, a blow-by hose or a blow-by pipe. One end of the first blow-by gas passage 50 of the present embodiment is connected to a gas-liquid separation chamber 51 provided in the cylinder head cover 14, and the other end is connected at a position between the air cleaner 32 and the throttle valve 33 in the intake passage 30. Further, the first blow-by gas passage 50 extends obliquely upward from the gas-liquid separation chamber 51 side toward the intake passage 30 side. Further, the other end of the first blow-by gas passage 50, that is, the connection position between the first blow-by gas passage 50 and the intake passage 30 is located below the air cleaner 32.

[0020] The gas-liquid separation chamber 51 is located in the upper part of the cylinder head cover 14, and the space in the cylinder head cover 14 and the space in the gas-liquid separation chamber 51 communicate with each other. Here, the blow-by gas that has leaked into the crank chamber 15 stays in the cylinder head cover 14 by rising through the cam chain chamber or the engine oil hole. Therefore, the blow-by gas also stays in the gas-liquid separation chamber 51 that communicates with the cylinder head cover 14.

[0021] In the gas-liquid separation chamber 51, since the gas among the components contained in the blow-by gas is located above and the water vapor is located below due to its own weight, the gas and the liquid can be separated. The blow-by gas separated upward in the gas-liquid separation chamber 51 contains gaseous fuel as unburned gas and other gases. The blow-by gas separated in the gas-liquid separation chamber 51 can be refluxed to the intake passage 30 via the first blow-by gas passage 50.

[0022] On the other hand, the second blow-by gas passage 55 is a passage that connects the cylinder block 12 and the intake passage 30. The second blow-by gas passage 55 is composed of, for example, a blow-by hose or a blow-by pipe. One end of the second blow-by gas passage 55 of the present embodiment is connected to the crank chamber 15 of the cylinder block 12, and the other end is connected to a position on the downstream side of the throttle valve 33 in the intake passage 30, here, the intake manifold. Further, the second blow-by gas passage 55 extends upward as it goes from the crank chamber 15 side toward the intake passage 30 side. A PCV (Positive Crankcase Ventilation) valve 56 is disposed at one end of the second blow-by gas passage 55. The PCV valve 56 adjusts the flow rate of the blow-by gas refluxed from the crank chamber 15 to the intake passage 30 by opening in response to the negative pressure in the intake passage 30.

[0023] During idling rotation when the generation of blow-by gas is small, the PCV valve 56 of the second blow-by gas passage 55 opens due to the negative pressure in the intake passage 30, and the blow-by gas mainly refluxes to the intake passage 30 via the second blow-by gas passage 55. On the other hand, during acceleration or high load when the generation of blow-by gas increases, the blow-by gas refluxes to the intake passage 30 via the first blow-by gas passage 50 in addition to the second blow-by gas passage 55.

[0024] FIG. 2 is an enlarged view showing an enlarged configuration around the gas separation device 60 in the engine 10 shown in FIG. 1. When the engine stops and the intake passage 30 does not become negative pressure, the blow-by gas containing gaseous fuel lighter than air in the fuel is configured not to be released to the atmosphere from the intake port 31 through the air cleaner 32 disposed above the first blow-by gas passage 50 via the first blow-by gas passage 50 in the gas separation device 60.

[0025] The gas separation device 60 includes a communication port 61, a separation chamber 62, a return passage 65, and an on-off valve 66. The communication port 61 communicates the first blow-by gas passage 50 with the separation chamber 62. Specifically, the communication port 61 is provided at an intermediate position and at the upper part of the first blow-by gas passage 50.

[0026] The separation chamber 62 is disposed above the first blow-by gas passage 50 and communicates with the first blow-by gas passage 50 via the communication port 61. Among the blow-by gas, the gaseous fuel lighter than air stays in the upper part of the first blow-by gas passage 50 and flows while flowing from the gas-liquid separation chamber 51 to the first blow-by gas passage 50 when the engine stops. Therefore, when the blow-by gas reaches the communication port 61, mainly the gaseous fuel flows into the communication port 61, and the other gases mainly flow through the first blow-by gas passage 50 as it is. In this way, in the separation chamber 62, the gaseous fuel and the other gases can be separated, and the separated gaseous fuel can be collected on the upper side of the space.

[0027] Further, the separation chamber 62 has an occlusion material 63 inside. The occlusion material 63 adsorbs the gaseous fuel collected in the separation chamber 62. By the occlusion material 63 adsorbing the gaseous fuel, it is possible to prevent the gaseous fuel from leaking unintentionally from the separation chamber 62. When the gaseous fuel is hydrogen fuel, for example, a hydrogen storage alloy can be used as the occlusion material 63.

[0028] In addition, cooling pipes for cooling the engine body 11 with cooling water may be arranged in the separation chamber 62. Specifically, the cooling pipes may be branched from the engine body 11 and arranged on the outer wall of the separation chamber 62, or may be arranged to penetrate through the inside of the separation chamber 62 (or inside the occlusion material 63). Since heat can be applied to the occlusion material 63 by flowing the cooling water after warm-up through the cooling pipes, the hydrogen fuel adsorbed on the occlusion material 63 can be separated. The control device 70 can flow the cooling water after warm-up through the cooling pipes arranged in the separation chamber 62 by switching the path of the cooling water using a valve (not shown). That is, the control device 70 can separate the hydrogen fuel by flowing the cooling water after warm-up into the separation chamber 62 at the timing when it is desired to separate the hydrogen fuel, so that it is possible to prevent the hydrogen fuel from leaking unintentionally.

[0029] In addition, the separation chamber 62 is provided with a gaseous fuel detection sensor 64 for detecting gaseous fuel. The gaseous fuel detection sensor 64 detects the gaseous fuel collected in the separation chamber 62 and transmits the detected information to the control device 70.

[0030] The return passage 65 is a passage that communicates the separation chamber 62 and the intake passage 30. The return passage 65 is constituted by, for example, a hose or a pipe. One end of the return passage 65 is connected to the upper part of the separation chamber 62, and the other end is connected at a position downstream of the throttle valve 33 in the intake passage 30. The return passage 65 can return the gaseous fuel collected in the separation chamber 62 to the intake passage 30.

[0031] The on-off valve 66 is provided in the return passage 65. When the on-off valve 66 is opened, the gaseous fuel collected in the separation chamber 62 is returned to the intake passage 30 through the return passage 65. On the other hand, when the on-off valve 66 is closed, it regulates so that the gaseous fuel collected in the separation chamber 62 is not unintentionally returned to the intake passage 30. The on-off valve 66 can use, for example, a solenoid valve. The opening and closing of the on-off valve 66 is controlled based on the control by the control device 70.

[0032] The control device 70 controls the entire vehicle 1. The control device 70 can use, for example, an ECU (Electronic Control Unit). As a hardware configuration, the control device 70 has a CPU, a ROM, a RAM, etc. Programs and predetermined information for controlling the vehicle 1, the engine 10, etc. are stored in advance in the ROM. The RAM is a work memory that temporarily stores programs and data. By the CPU reading out the programs stored in the ROM, expanding them in the RAM, and executing them, the vehicle 1, the engine 10, the gas separation device 60, etc. are controlled.

[0033] In the gas separation device 60 configured as described above, although the blow-by gas flows toward the air cleaner 32 via the first blow-by gas passage 50 when the engine is stopped, the gaseous fuel that is lighter than air among the blow-by gas flows into the separation chamber 62 from the communication port 61 and is collected by the separation chamber 62. Therefore, even when a gaseous fuel that is lighter than air is used as the fuel, it is possible to suppress the gaseous fuel from being released to the atmosphere when the engine is stopped. On the other hand, in the gas separation device 60, when the engine is running, based on the control by the control device 70, the gaseous fuel collected in the separation chamber 62 is returned to the intake passage 30, so that the gaseous fuel can be reburned.

[0034] Here, an example of the process in which the control device 70 returns the gaseous fuel collected in the separation chamber 62 to the intake passage 30 when the engine is running will be described with reference to the flowchart of FIG. 3. The flowchart of FIG. 3 is realized, for example, by the ECU, which is the control device 70, executing a program. Also, the flowchart of FIG. 3 starts when the engine 10 is started. Here, it is assumed that the gaseous fuel that is lighter than air among the blow-by gas flows into the separation chamber 62 from the communication port 61 and is collected in the separation chamber 62 when the engine is stopped.

[0035] In S1, the control device 70 determines whether or not a predetermined amount or more of gaseous fuel is collected in the separation chamber 62 based on information from the gaseous fuel detection sensor 64 provided in the separation chamber 62. If it is determined that a predetermined amount or more of gaseous fuel is collected, the process proceeds to S2. On the other hand, if it is determined that a predetermined amount or more of gaseous fuel is not collected, since there is no need to return the gaseous fuel to the intake passage 30, the process proceeds to S4.

[0036] In S2, the control device 70 prohibits fuel learning. Here, the control device 70 detects the oxygen concentration in the exhaust gas and performs feedback control to inject gaseous fuel with a fuel injection amount such that the air-fuel ratio becomes near, for example, the stoichiometric air-fuel ratio, based on the detected information. The control device 70 stores the difference between the target air-fuel ratio and the actual air-fuel ratio as a fuel learning value and performs fuel learning to correct the fuel injection amount. On the other hand, in the next S3, there is a possibility of mislearning because fuel learning is performed due to the gaseous fuel temporarily becoming highly concentrated by returning the gaseous fuel collected in the separation chamber 62 to the intake passage 30. Therefore, the control device 70 prohibits fuel learning before returning the gaseous fuel to the intake passage 30.

[0037] In S3, the control device 70 controls to open the on-off valve 66 of the return passage 65. Therefore, the gaseous fuel collected in the separation chamber 62 can be returned to the intake passage 30 through the return passage 65 and can be reburned in the combustion chamber 19. Note that the control device 70 may separate the hydrogen fuel adsorbed on the storage material 63 of the separation chamber 62 by switching the path of the cooling water using a valve (not shown) in advance before opening the on-off valve 66.

[0038] In S4, the control device 70 determines whether or not to stop the driving of the engine 10. If the driving of the engine 10 is to be stopped according to an instruction from the driver, the process proceeds to S5. On the other hand, if the driving of the engine 10 is not to be stopped, the control device waits in S4 until the driving of the engine 10 is stopped according to an instruction from the driver.

[0039] In S5, when the opening / closing valve 66 is open, the control device 70 controls to close the opening / closing valve 66 and then stops the driving of the engine 10. When stopping the driving of the engine 10 in this way, by closing the opening / closing valve 66, it is possible to regulate so that the gaseous fuel collected in the separation chamber 62 at the time of engine stop does not flow into the intake passage 30 through the return passage 65 unintentionally. Therefore, it is possible to prevent the gaseous fuel collected in the separation chamber 62 from being released to the atmosphere.

[0040] As described above, the gas separation device 60 of the present embodiment is provided with a communication port 61 for communicating the first blow-by gas passage 50 and the separation chamber 62 above the first blow-by gas passage 50, so that the gaseous fuel can be collected in the separation chamber 62, and it is possible to suppress the gaseous fuel from being released to the atmosphere. Further, after the engine is started, the gaseous fuel collected in the separation chamber 62 can be returned from the return passage 65 to the intake passage 30 to cause the gaseous fuel to be re-burned.

[0041] In addition, an opening / closing valve 66 is provided in the return passage 65 of the gas separation device 60 of the present embodiment. By closing the opening / closing valve 66 when the engine stops, it is possible to prevent the gaseous fuel collected in the separation chamber 62 from flowing into the return passage 65 and being released to the atmosphere from the intake passage 30.

[0042] As described above, the embodiments according to the present invention have been described, but the present invention is not limited to the above-described embodiments, and changes and the like are possible within the scope of the present invention.

[0043] In the above-described embodiment, the case where the engine 10 is a naturally aspirated engine (normal aspiration) has been described, but the present invention is not limited to this case, and an engine equipped with a supercharger may also be used. In the case of an engine equipped with a supercharger, it is preferable that the other end of the return passage 65 is connected at a position upstream of the compressor wheel 34 of the supercharger indicated by the two-dot chain line shown in FIG. 2 in the intake passage 30.

Description of Reference Numerals

[0044] 1: Vehicle 10: Engine 12: Cylinder block 13: Cylinder head 14: Cylinder head cover 30: Intake passage 31: Intake port 32: Air cleaner 33: Throttle valve 45: Fuel injector 50: First blow-by gas passage 51: Gas-liquid separation chamber 60: Gas separation device 61: Communication port 62: Separation chamber 63: Storage material 64: Gas fuel detection sensor 65: Return passage 66: On-off valve 70: Control device

Claims

1. A gas separation device for an internal combustion engine having a blow-by gas passage for refluxing the generated blow-by gas to an intake passage, a separation chamber disposed above the blow-by gas passage for separating gaseous fuel from other gases in the blow-by gas, a communication port provided at an upper portion of the blow-by gas passage for communicating the blow-by gas passage with the separation chamber, and a return passage for communicating the separation chamber with the intake passage to return the gaseous fuel separated by the separation chamber to the intake passage. A gas separation device for an internal combustion engine, characterized by comprising the above.

2. An opening / closing valve is provided in the return passage, The gas separation device for an internal combustion engine according to claim 1, wherein the opening / closing valve closes when the internal combustion engine stops.

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