Recirculation device of internal combustion engine

Abstract

To prevent blow-by gas from flowing back through an intake path and contaminating an air cleaner.SOLUTION: A recirculation device 60 of an internal combustion engine of the present invention has a first blow-by gas passage 61 that recirculates blow-by gas generated in the internal combustion engine to an intake passage 30 upstream of a compressor wheel 52, and a blow-by valve 62 that is provided in the first blow-by gas passage 61 and closes when a bypass valve 36 opens. It is possible to prevent the blow-by gas recirculated to the intake side from flowing back into an air cleaner 31 when a pressure on the upstream side of the compressor wheel 52 increasing rapidly, and contaminating the air cleaner 31.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Conventionally, an engine equipped with a supercharger has been known. The supercharger of the engine system disclosed in Patent Document 1 includes a turbine provided in an exhaust passage, a compressor provided in an intake passage, and a turbine shaft that rotatably connects the turbine and the compressor integrally. Further, the engine system of Patent Document 1 includes a cam chamber and a blow-by gas flow path (second blow-by gas flow path) that communicates between an air cleaner and a compressor in an intake flow path. When the supercharger is supercharging, blow-by gas is sucked from the blow-by gas flow path by the compressor and refluxed to the intake flow path. In this way, by refluxing the blow-by gas to the intake passage, the unburned gas of 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 an engine equipped with a supercharger, in order to suppress the pressure rise on the downstream side of the supercharger, it has a bypass passage that bypasses the front and rear of the supercharger and a bypass valve. For example, when the intake air is restricted by a throttle valve to rapidly reduce the engine output, since the compressor of the supercharger continues to rotate due to inertia, the pressure between the compressor of the supercharger and the throttle valve rapidly rises. At this time, the bypass valve is opened to release the pressure. However, when the bypass valve is opened, the pressure on the upstream side of the compressor of the supercharger rapidly increases, and the blow-by gas refluxed to the upstream side of the compressor of the supercharger may further flow backward upstream in the intake passage, contaminating the air cleaner.

[0005] The present invention has been made in view of the above-described problems, and an object thereof is to prevent blow-by gas from flowing backward in the intake path and contaminating the air cleaner.

Means for Solving the Problems

[0006] The present invention relates to a reflux device for an internal combustion engine, which includes an intake passage through which intake air flows, a compressor wheel of a supercharger provided in the intake passage, a throttle valve provided on the downstream side of the compressor wheel in the intake passage, a bypass passage that communicates the front and rear of the compressor wheel in the intake passage, and a bypass valve provided in the bypass passage that opens when the pressure between the compressor wheel and the throttle valve rises. The reflux device is characterized by having a first blow-by gas passage that refluxes the blow-by gas generated in the internal combustion engine to the upstream side of the compressor wheel in the intake passage, and a blow-by valve provided in the first blow-by gas passage that closes when the bypass valve opens.

Effects of the Invention

[0007] According to the present invention, it is possible to prevent blow-by gas from flowing backward in the intake path and contaminating the air cleaner.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0009] An embodiment according to the present invention includes an intake passage 30 through which intake air flows, a compressor wheel 52 of a supercharger 50 provided in the intake passage 30, a throttle valve 32 provided on the downstream side of the compressor wheel 52 in the intake passage 30, a bypass passage 35 that communicates the front and rear of the compressor wheel 52 in the intake passage 30, and a bypass valve 36 provided in the bypass passage 35 that opens when the pressure between the compressor wheel 52 and the throttle valve 32 rises. The reflux device 60 of the internal combustion engine has a first blow-by gas passage 61 that refluxes the blow-by gas generated in the internal combustion engine to the upstream side of the compressor wheel 52 in the intake passage 30, and a blow-by valve 62 provided in the first blow-by gas passage 61 that closes when the bypass valve 36 opens. By closing the blow-by valve 62 and blocking the first blow-by gas passage 61 when the bypass valve 36 is opened, it is possible to prevent the blow-by gas from flowing backward through the intake passage 30 and contaminating the air cleaner 31.

Examples

[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 equipped with a reflux device 60 (hereinafter referred to as the reflux device 60) for an internal combustion engine according to this embodiment. Note that FIG. 1 is simplified for the convenience of explanation to describe this embodiment, and it is assumed that the vehicle is equipped with components that are not shown even though they are normally provided. The vehicle 1 according to the embodiment includes an engine 10 as an internal combustion engine, a reflux device 60, a control device 70, and the like.

[0011] The engine 10 performs a series of processes including an intake stroke, a compression stroke, a combustion stroke, and an exhaust stroke. The engine 10 of this 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 in sequence on the upper part of a cylinder block 12. 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 inside 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 the 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 disposed in the intake port 21, and by opening the valve, 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 disposed in the exhaust port 23, and by opening the valve, 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 air cleaner 31, a throttle valve 32, a surge tank 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 surge tank 33 is constituted by an intake manifold. In the intake passage 30, the air cleaner 31, the throttle valve 32, and the surge tank 33 are arranged in order from the upstream side.

[0015] The air cleaner 31 purifies the intake air by removing foreign matters such as dust and dirt contained in the intake air. The throttle valve 32 adjusts the flow rate of the intake air by opening and closing. The throttle valve 32 adjusts the flow rate of the intake air based on the control by the control device 70. The surge tank 33 temporarily stores the intake air and then guides it to the combustion chamber 19 after rectifying it. Note that an intake pressure sensor 34 for detecting the pressure of the intake passage 30 between the throttle valve 32 and the compressor wheel 52 of the supercharger 50 described later is provided in the intake passage 30. The intake pressure sensor 34 transmits the detected information to the control device 70.

[0016] The engine 10 has, as an exhaust system, an exhaust passage 40, a catalytic converter 41, etc. 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, the catalytic converter 41, a muffler (not shown), etc. 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, etc. The fuel injector 45 injects the fuel pumped from the fuel tank into the intake passage 30. The fuel injector 45 adjusts the fuel injection amount based on the control by the control device 70. Note that the fuel injector 45 is not limited to injecting fuel into the intake passage 30, and may be configured to inject fuel into the intake port 21 or the combustion chamber 19. The fuel stored in the fuel tank is supplied to the fuel injector 45 for each cylinder via the delivery pipe while being pumped.

[0018] Further, the engine 10 has a supercharger 50. The supercharger 50 of the present embodiment uses a turbocharger that compresses intake air using the exhaust pressure as a power source. The supercharger 50 includes a turbine wheel 51, a compressor wheel 52, and a shaft 53 that integrally and rotatably connects the turbine wheel 51 and the compressor wheel 52. The turbine wheel 51 is disposed between the exhaust port 23 and the catalytic converter 41 in the exhaust passage 40. The turbine wheel 51 rotates by the exhaust gas discharged from the exhaust port 23. On the other hand, the compressor wheel 52 is disposed between the air cleaner 31 and the throttle valve 32 in the intake passage 30. The compressor wheel 52 rotates in conjunction with the rotation of the turbine wheel 51 to compress the intake air and supply it to the downstream side of the intake passage 30.

[0019] In addition, a bypass passage 35 is formed in the intake passage 30 to communicate the front and rear of the compressor wheel 52 of the supercharger 50. The bypass passage 35 is constituted by, for example, a hose or a pipe. One end of the bypass passage 35 is connected to a position between the compressor wheel 52 and the throttle valve 32 in the intake passage 30, and the other end is connected to a position between the air cleaner 31 and the compressor wheel 52 in the intake passage 30. Further, a bypass valve 36 is provided in the bypass passage 35. The bypass valve 36 is normally closed and opens when the pressure between the compressor wheel 52 and the throttle valve 32 rises. That is, when the intake air is restricted by the throttle valve 32 to rapidly reduce the output of the engine body 11, the compressor wheel 52 of the supercharger 50 continues to rotate due to inertia, so that the pressure between the compressor wheel 52 and the throttle valve 32 rises rapidly. At this time, the pressure is released by opening the bypass valve 36. The bypass valve 36 opens and closes based on the control by the control device 70.

[0020] Further, the engine 10 has a reflux device 60 for refluxing the blow-by gas leaking from the combustion chamber 19 to the crank chamber 15 via between the piston 17 and the inner peripheral surface of the cylinder bore into the intake passage 30. The reflux device 60 has a first blow-by gas passage 61 and a second blow-by gas passage 63.

[0021] The first blow-by gas passage 61 is a passage that connects the cylinder head cover 14 and the intake passage 30. The first blow-by gas passage 61 is constituted by, for example, a blow-by hose or a blow-by pipe. Further, one end of the first blow-by gas passage 61 is connected to the cylinder head cover 14, and the other end is connected to a position between the air cleaner 31 and the compressor wheel 52 in the intake passage 30. Note that the other end of the first blow-by gas passage 61 is connected to a position upstream of the other end of the bypass passage 35 in the intake passage 30. Further, a blow-by valve 62 is provided in the first blow-by gas passage 61 of the present embodiment. The blow-by valve 62 opens and closes based on control by the control device 70.

[0022] Here, the inside of the cylinder head cover 14 and the inside of the crank chamber 15 communicate with each other through a cam chain chamber or an engine oil hole. Therefore, since the blow-by gas in the crank chamber 15 stays in the cylinder head cover 14 through the cam chain chamber or the engine oil hole, when the blow-by valve 62 is open, it is refluxed from the inside of the cylinder head cover 14 to the intake passage 30 via the first blow-by gas passage 61.

[0023] The second blow-by gas passage 63 is a passage that connects the cylinder block 12 and the intake passage 30. The second blow-by gas passage 63 is constituted by, for example, a blow-by hose or a blow-by pipe. Further, one end of the second blow-by gas passage 63 is connected to the crank chamber 15 of the cylinder block 12, and the other end is connected to a position downstream of the throttle valve 32 in the intake passage 30, here, a position between the throttle valve 32 and the surge tank 33. Further, a PCV (Positive Crankcase Ventilation) valve 64 is disposed at one end of the second blow-by gas passage 63. The PCV valve 64 opens and closes according to the pressure in the intake passage 30 or the pressure in the crank chamber 15.

[0024] Here, when the pressure in the intake passage 30 (downstream of the throttle valve 32) is low or the pressure in the crank chamber 15 is high, the PCV valve 64 opens, and the blow-by gas in the crank chamber 15 is refluxed from the crank chamber 15 to the intake passage 30 via the second blow-by gas passage 63.

[0025] 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 and 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 reflux device 60, etc. are controlled.

[0026] In the engine 10 configured as described above, when the pressure between the compressor wheel 52 and the throttle valve 32 rises rapidly, the bypass valve 36 opens to release the pressure. At this time, the control device 70 controls the reflux device 60 so that the pressure upstream of the compressor wheel 52 of the supercharger 50 rises rapidly, and the blow-by gas refluxed upstream of the compressor wheel 52 of the supercharger 50 does not flow back upstream through the intake passage 30 to contaminate the air cleaner 31.

[0027] Next, an example of specific processing by the control device 70 will be described with reference to the flowchart of FIG. 2. The flowchart of FIG. 2 is realized, for example, when the ECU, which is the control device 70, executes a program. Also, the flowchart of FIG. 2 starts when the engine 10 is started. Here, the supercharger 50 is driving, and the compressor wheel 52 rotates in conjunction with the rotation of the turbine wheel 51 to compress the intake air and supply it to the downstream side of the intake passage 30. Also, the bypass valve 36 of the bypass passage 35 is closed, and the blow-by valve 62 of the first blow-by gas passage 61 is open. Therefore, the blow-by gas mainly flows back to the upstream side of the compressor wheel 52 in the intake passage 30 via the first blow-by gas passage 61.

[0028] In S1, the control device 70 determines whether the pressure in the intake passage 30 has reached a predetermined value (first threshold) or more. Specifically, the control device 70 determines whether the pressure in the intake passage 30 has reached a predetermined value or more based on the information from the intake pressure sensor 34 that detects the pressure in the intake passage 30 between the compressor wheel 52 of the supercharger 50 and the throttle valve 32. If it has reached the predetermined value (first threshold) or more, it proceeds to S2. If it is less than the predetermined value, it makes a determination in S1 until it reaches the predetermined value or more. The predetermined value (first threshold) is set to the value when the pressure in the intake passage 30 rises because the control device 70 restricts the intake air with the throttle valve 32 while the compressor wheel 52 of the supercharger 50 continues to rotate due to inertia.

[0029] In S2, the control device 70 controls to open the bypass valve 36 of the bypass passage 35. By opening the bypass valve 36, the pressure between the compressor wheel 52 of the supercharger 50 and the throttle valve 32 in the intake passage 30 is released. On the other hand, by opening the bypass valve 36, the pressure on the upstream side of the compressor wheel 52 in the intake passage 30 rises.

[0030] In S3, the control device 70 controls to close the blow-by valve 62 of the first blow-by gas passage 61 in conjunction with the opening of the bypass valve 36 in S2. By closing the blow-by valve 62 to block the first blow-by gas passage 61, blow-by gas is not refluxed to the upstream side of the compressor wheel 52 in the intake passage 30. Therefore, since it is possible to prevent the blow-by gas from flowing backward through the intake passage 30, it is possible to prevent the air cleaner 31 from being contaminated.

[0031] Note that although the blow-by gas will fill the crank chamber 15 while the first blow-by gas passage 61 is blocked, the PCV valve 64 of the second blow-by gas passage 63 opens due to the increase in the pressure in the crank chamber 15. Therefore, even while the first blow-by gas passage 61 is blocked, the blow-by gas in the crank chamber 15 can be refluxed to the downstream side of the throttle valve 32 in the intake passage 30 via the second blow-by gas passage 63.

[0032] In S4, the control device 70 determines whether or not the pressure in the intake passage 30 has become less than a predetermined value (second threshold value). Specifically, the control device 70 determines whether or not the pressure in the intake passage 30 has become less than the predetermined value based on the information from the intake pressure sensor 34. If it has become less than the predetermined value (second threshold value), the process proceeds to S5, and if it is equal to or greater than the predetermined value, the determination is made in S4 until it becomes less than the predetermined value. Note that, for example, a value smaller than the first threshold value is used as the second threshold value.

[0033] In S5, the control device 70 controls to close the bypass valve 36 of the bypass passage 35. In S6, the control device 70 controls to open the blow-by valve 62 of the first blow-by gas passage 61 in conjunction with the closing of the bypass valve 36 in S5. Therefore, the blow-by gas can be refluxed again to the upstream side of the compressor wheel 52 in the intake passage 30 via the first blow-by gas passage 61.

[0034] As described above, the recirculation device 60 of the present embodiment includes a first blow-by gas passage 61 that recirculates the blow-by gas generated by the engine 10 to the upstream side of the compressor wheel 52 in the intake passage 30, and a blow-by valve 62 that is provided in the first blow-by gas passage 61 and closes when the bypass valve 36 opens. Therefore, it is possible to prevent the pressure on the upstream side of the compressor wheel 52 from rising rapidly and the blow-by gas recirculated to the intake side from flowing back into the air cleaner 31, and it is possible to prevent the air cleaner 31 from being contaminated by the blow-by gas. On the other hand, the blow-by valve 62 opens when the bypass valve 36 closes. Therefore, even when the pressure in the crankcase 15 is high and the blow-by gas cannot flow back from the second blow-by gas passage 63 to the intake passage 30, it is possible to prevent the blow-by gas from being released to the atmosphere from the joint between the components of the engine body 11 by flowing back from the first blow-by gas passage 61 to the intake passage 30.

[0035] Further, the recirculation device 60 of the present embodiment includes a second blow-by gas passage 63 that recirculates the blow-by gas generated by the engine 10 to the downstream side of the throttle valve 32 in the intake passage 30. Therefore, even while the first blow-by gas passage 61 is blocked, the blow-by gas in the crankcase 15 can be recirculated to the downstream side of the throttle valve 32 in the intake passage 30 via the second blow-by gas passage 63.

[0036] 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.

[0037] In the above-described embodiment, the case where the blow-by valve 62 in S3 is closed after the bypass valve 36 in S2 is opened in the flowchart of FIG. 2 has been described. However, the processes of S2 and S3 may be at substantially the same timing and are not particularly limited. For example, the order of S2 and S3 may be reversed, and the closing of the blow-by valve 62 in S3 may be slightly earlier than the opening of the bypass valve 36 in S2.

[0038] In the above-described embodiment, the case where the control device 70 opens and closes the blow-by valve 62 has been described, but the present invention is not limited to this case. For example, the blow-by valve 62 may be configured to be mechanically interlocked with the bypass valve 36. That is, the blow-by valve 62 may be configured to close when the bypass valve 36 opens and to open when the bypass valve 36 closes.

Explanation of Reference Numerals

[0039] 1: Vehicle 10: Engine 12: Cylinder Block 13: Cylinder Head 14: Cylinder Head Cover 30: Intake Passage 31: Air Cleaner 32: Throttle Valve 35: Bypass Passage 36: Bypass Valve 40: Exhaust Passage 45: Fuel Injector 50: Supercharger 51: Turbine Wheel 52: Compressor Wheel 60: Recirculation Device 61: First Blow-By Gas Passage 62: Blow-By Valve 63: Second Blow-By Gas Passage 70: Control Device

Claims

1. An intake passage through which intake air flows, a compressor wheel of a supercharger provided in the intake passage, a throttle valve provided downstream of the compressor wheel in the intake passage, a bypass passage that communicates the front and rear of the compressor wheel in the intake passage, a bypass valve provided in the bypass passage that opens when the pressure between the compressor wheel and the throttle valve rises, and is a reflux device for an internal combustion engine having: a first blow-by gas passage that refluxes the blow-by gas generated in the internal combustion engine upstream of the compressor wheel in the intake passage, A reflux device for an internal combustion engine, comprising: a blow-by valve provided in the first blow-by gas passage that closes when the bypass valve opens.

2. The reflux device for an internal combustion engine according to claim 1, further comprising a second blow-by gas passage that refluxes the blow-by gas generated in the internal combustion engine downstream of the throttle valve in the intake passage.

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