JP5002037B2 - Blowby gas recirculation system - Google Patents

Description

  The present invention relates to a blow-by gas recirculation device for an internal combustion engine, and more particularly to a structure of a regulating valve (PCV valve) for adjusting the flow rate of blow-by gas.

  2. Description of the Related Art Conventionally, in a blow-by gas recirculation device that recirculates blow-by gas of an internal combustion engine to an intake system, the blow-by gas passage formed in the engine body (cylinder block, cylinder head, cylinder head cover, etc.) of the internal combustion engine communicates with the intake system piping. There is one that detects the detachment (disconnection) of the gas recirculation hose to prevent leakage of blow-by gas (for example, Patent Document 1). In this blow-by gas recirculation device, the amount of intake air in the intake system caused by the outside air sucked through the open end of the gas recirculation hose opened when the gas recirculation hose is desorbed is detected, and the gas recirculation hose is desorbed. Detected. In such a blow-by gas recirculation device, a notch is provided at the open end of the gas recirculation hose so that when the gas recirculation hose is detached, the open end cannot be adsorbed on the outer surface of the engine body, and the intake amount is reduced. There is a blow-by gas recirculation device that increases more reliably (for example, Patent Document 2).

Japanese Patent Laid-Open No. 10-184335 JP 2002-213226 A

  Some conventional blowby gas recirculation devices are provided with an adjustment valve (PCV valve) between the blowby gas passage and the gas recirculation hose to adjust the flow rate of the blowby gas. The regulating valve opens when the internal pressure on the gas recirculation hose (intake system) side becomes lower than a predetermined value with respect to the internal pressure on the blow-by gas passage (crankcase) side, and allows passage of blow-by gas. When the regulating valve is detached from the blow-by gas passage while the connection state between the regulating valve and the gas recirculation hose is maintained, the regulating valve becomes an obstacle and an increase in the intake air amount is inhibited. Therefore, there is a possibility that it cannot be detected that the gas recirculation hose and the regulating valve are detached from the blow-by gas passage.

  The present invention has been made in view of the above background, and provides a blow-by gas recirculation device that can increase the amount of intake air in an intake system when a regulating valve is detached from a blow-by gas passage. Objective.

  In order to solve the above-described problems, the present invention provides a blow-by gas passage (55, 32) formed in an engine body (15) of an internal combustion engine (10), and a blow-by gas flow regulating valve continuous to the blow-by gas passage. (52) and a blowby gas recirculation path (53) having one end continuous to the blowby gas flow rate adjustment valve and the other end continuing to the intake system (16) of the internal combustion engine, the blowby gas flow rate adjustment valve Comprises an inlet (74) continuous to the blow-by gas passage, an outlet (91) continuous to the blow-by gas reflux path, and a valve passage (93) communicating the inlet and the outlet, A valve body (61) attached to the engine main body and a valve body that is slidably provided on a valve seat (75) formed in the valve passage and opens and closes the valve passage 62), wherein the valve housing includes a bypass passage that communicates a portion of the valve passage between the valve seat and the outlet and an outer surface of the valve housing. 89), and the opening end of the bypass passage on the outer surface side of the valve housing is closed by the engine body while the valve housing is attached to the engine body. It is opened in a state of being detached from the engine body. Here, the engine main body includes members constituting the main body of the internal combustion engine, such as a cylinder block, a cylinder head, and a cylinder head cover.

  According to this configuration, when the blow-by gas flow regulating valve is detached from the engine body, the bypass passage is opened, and the outside air flows through the bypass passage and flows into the intake system due to the negative pressure of the intake system. Therefore, the intake air amount of the intake system can be increased when the blow-by gas flow rate adjustment valve is detached from the engine body. By detecting the increase in the intake air amount, it is possible to detect the detachment of the blow-by gas flow regulating valve from the engine body.

  According to another aspect of the present invention, the engine main body portion is provided with a fitting hole (58) into which the valve housing can be fitted, and is connected to the blow-by gas passage, and the bypass passage has an outer surface side of the valve housing. The open end is closed by a hole wall of the fitting hole in a state where the valve housing is fitted in the fitting hole.

  According to this configuration, the bypass passage can be easily and reliably closed when the blowby gas flow rate adjustment valve is attached to the engine body.

  Another aspect of the present invention is characterized in that the valve housing includes a fastening portion (85) that is fastened to the engine body in a state where the valve housing is fitted in the fitting hole.

  According to this configuration, the bypass passage can be easily and reliably closed when the blowby gas flow rate adjustment valve is attached to the engine body.

  Another aspect of the present invention is characterized in that the blow-by gas recirculation path is detachably connected to the outlet of the valve housing.

  According to this configuration, the blow-by gas flow rate adjustment valve and the blow-by gas recirculation path are always maintained in a connected state, and when desorbing from the blow-by gas path, the blow-by gas path and the blow-by gas flow rate adjustment valve Separate from connection. Therefore, outside air surely flows into the intake system through the bypass passage. In addition, the inflow of outside air from the connection portion between the blow-by gas flow rate adjusting valve and the blow-by gas recirculation path can be reliably prevented, and a reduction in the amount of the re-circulating blow-by gas can be prevented.

  In another aspect of the present invention, the blow-by gas flow regulating valve is configured such that when the outlet side has a predetermined negative pressure and the outside of the inlet and the bypass path has a predetermined positive pressure, When the valve body is closed and the valve body is arranged at the maximum opening position, the inlet is closed and the bypass passage is opened rather than the flow rate of the fluid flowing from the inlet to the outlet. The flow passage cross-sectional area of the bypass passage is set so that the flow rate of the fluid flowing from the bypass passage to the outlet is increased.

  According to this configuration, when the blow-by gas flow rate adjustment valve is detached from the blow-by gas passage, the amount of intake air flowing into the intake system can be reliably increased.

  According to the above configuration, the blow-by gas recirculation device can increase the intake air amount when the regulating valve is detached from the blow-by gas passage.

Schematic diagram of internal combustion engine PCV valve perspective view III-III sectional view of FIG. Sectional view showing the mounting structure of the PCV valve to the head cover

  Hereinafter, an embodiment in which the blow-by gas recirculation device of the present invention is applied to an automobile gasoline engine will be described in detail with reference to the drawings.

<Overall configuration of internal combustion engine>
As shown in FIG. 1, an automobile gasoline engine (internal combustion engine) 10 includes an engine body 15 including a cylinder block 11, a cylinder head 12, a cylinder head cover 13, and an oil pan 14, and an intake system 16 connected to the cylinder head 12. And an exhaust system 17 as main components.

  A cylinder 20 in which a piston 19 is slidably accommodated is formed in the upper part of the cylinder block 11, and a crankcase 21 is formed in the lower part. A crankshaft 23 connected by a piston 19 and a connecting rod 22 is rotatably supported on the crankcase 21. An oil pan 14 in which engine oil is stored is attached to the lower part of the crankcase 21.

  The cylinder head 12 is formed with a combustion chamber 25 and an intake passage 26 and an exhaust passage 27 communicating with the combustion chamber 25. Between the combustion chamber 25 and the intake passage 26 and the exhaust passage 27, an intake valve 30 and an exhaust valve 31 that are opened and closed by camshafts 28 and 29 are provided. A cylinder head cover 13 is attached to the upper part of the cylinder head 12, and a chamber 32 is defined by the cylinder head 12 and the cylinder head cover 13.

  The intake system 16 includes an air inlet 35, an air filter 36, an intake pipe 37, a throttle valve 38, a surge tank 39, and an intake manifold 40 from the upstream side, and the intake manifold 40 is connected to the cylinder head 12. The intake pipe 37 is provided with an idle bypass passage 41 that bypasses the throttle valve 38 and continues directly to the surge tank 39. The idle bypass passage 41 is provided with an ISC (Idle Speed control) valve 42 for controlling the engine speed during idling to a predetermined speed. A ventilation passage 44 communicating with the chamber 32 is provided in a portion of the intake pipe 37 that is located immediately downstream of the air filter 36.

  The exhaust system 17 is connected to the cylinder head 12 and includes an exhaust manifold 47 that is continuous with the exhaust passage 27. A three-way catalytic converter, a muffler, and the like (not shown) are connected downstream thereof.

<Blowby gas recirculation device>
The blow-by gas recirculation device 50 includes a blow-by gas passage 51, a PCV valve (blow-by gas flow rate adjustment valve) 52, and a blow-by hose (blow-by gas recirculation passage) 53 as main components. The blow-by gas passage 51 is formed in the cylinder block 11 and the cylinder head 12, and includes a communication passage 55 that connects the crankcase 21 and the chamber 32, and the chamber 32.

  The PCV valve 52 is a differential pressure drive type flow rate adjustment valve, and is fitted into a fitting hole 58 formed in the upper part of the cylinder head cover 13, and one end thereof enters the chamber 32. The blow-by hose 53 has one end continuous to the other end of the PCV valve 52 and the other end continuous to the surge tank 39. In this way, the blow-by gas leaked into the crankcase 21 passes through the communication path 55, the chamber 32, the PCV valve 52, and the blow-by hose 53 in order and is returned to the surge tank 39 of the intake system 16.

<PCV valve>
As shown in FIGS. 2 and 3, the PCV valve 52 includes a hollow cylindrical valve housing 61, a valve body 62 held in the valve housing 61, and a compression coil spring 63. A known material such as a metal material or a resin material can be applied to the valve housing 61 and the valve body 62. In this embodiment, in order to reduce a collision sound between the valve housing 61 and the valve body 62, a resin material is used. Is formed.

  The valve housing 61 is formed by combining a first housing 64 and a second housing 65. The first housing 64 is a stepped cylindrical member in which a large diameter cylindrical portion 67 and a small diameter cylindrical portion 68 having different outer diameters and inner diameters are coaxially continuous. An outer peripheral step portion 69 having a surface inclined with respect to the axial direction is formed in a continuous portion in the outer peripheral portion of the large diameter cylindrical portion 67 and the small diameter cylindrical portion 68. An inner peripheral step portion 70 having a surface orthogonal to the axial direction is formed in a continuous portion in the inner peripheral portion. The first housing 64 has a bottomed cylindrical shape in which an end on the small diameter cylindrical portion 68 side is closed by an end wall 71 and an opening 72 is provided on the end on the large diameter cylindrical portion 67 side.

  An inflow hole (inflow port) 74 penetrating along the axial direction of the first housing 64 is formed at the center of the end wall 71 of the first housing 64. A valve seat 75 on which the valve body 62 can be seated is recessed in the peripheral portion of the inflow hole 74 on the inner surface side of the end wall 71.

  Four first housing side through holes 77 extending in the radial direction and communicating the inner surface and the outer surface are formed in the large diameter cylindrical portion 67 of the first housing 64 at intervals of 90 ° on the same circumference. . In addition, two annular grooves 78 extending along the circumferential direction are formed on the outer peripheral portion of the large diameter cylindrical portion 67. The two annular grooves 78 are provided so as to sandwich the first housing side through-hole 77 in the axial direction. An O-ring 79 as a seal member is fitted in each of the two annular concave grooves 78. Further, an annular groove 80 along the opening 72 is formed on the end surface of the large-diameter cylindrical portion 67 on the opening 72 side so as to increase the diameter of the opening 72. An annular groove 80 is fitted with an O-ring 81 as a seal member.

  The second housing 65 includes an end wall 83 at one end and a cylindrical portion 84 having a bottomed cylindrical shape with the other end opened, and a flange portion (fastening portion) 85 formed on the outer peripheral surface of the cylinder portion 84. Yes. The flange portion 85 has a plate shape and is provided at an intermediate portion in the axial direction of the cylindrical portion 84 so as to be orthogonal to the axial direction. Further, the flange portion 85 has an extending portion 86 extending to one side in the radial direction of the cylindrical portion 84, and the extending portion 86 penetrates substantially parallel to the axial direction of the cylindrical portion 84. A hole 87 is formed.

  A portion of the cylindrical portion 84 on the side where the end wall 83 is provided is fitted to the inner peripheral portion of the large-diameter cylindrical portion 67 through the opening 72. The insertion depth of the cylindrical portion 84 into the large diameter cylindrical portion 67 is regulated by the flange portion 85 coming into contact with the opening end surface of the large diameter cylindrical portion 67. The cylindrical portion 84 is fixed to the large diameter cylindrical portion 67 by press-fitting the cylindrical portion 84 into the large diameter cylindrical portion 67. In other embodiments, a male screw may be formed on the outer peripheral surface of the cylindrical portion 84 and a female screw may be formed on the inner peripheral surface of the large-diameter cylindrical portion 67 so that both screws are screwed together. You may couple | bond the diameter cylindrical part 67 with an adhesive agent. Further, the flange portion 85 and the opening end surface of the large-diameter cylindrical portion 67 may be welded by vibration welding or the like. In a state where the cylindrical portion 84 is fitted to the large diameter cylindrical portion 67, the O-ring 81 is in close contact with the large diameter cylindrical portion 67, the cylindrical portion 84, and the flange portion 85, and the first housing 64 and the second housing 65 are connected. Seal the gap.

  The second housing side through-holes 88 extending in the radial direction and communicating the inner surface and the outer surface are provided at intervals of 90 ° on the same circumference at the outer peripheral portion on the side where the end wall 83 of the cylindrical portion 84 is provided. One is formed. In a state where the cylindrical portion 84 is fitted to the large-diameter cylindrical portion 67, each first housing side through hole 77 and each second housing side through hole 88 are continuous, and the inside of the second housing 65 and the first housing 64 are connected. A bypass hole (bypass passage) 89 that communicates with the outside is formed.

  A communication hole 90 penetrating along the axial direction of the cylindrical portion 84 is formed at the center of the end wall 83 of the cylindrical portion 84. In a state where the cylindrical portion 84 is fitted to the large diameter cylindrical portion 67, the inside of the first housing 64 and the inside of the second housing 65 communicate with each other through the communication hole 90.

  The opening at the end opposite to the side on which the end wall 83 of the cylindrical portion 84 is provided becomes an outflow hole (outlet) 91 of the valve housing 61. A passage from the inflow hole 74 to the outflow hole 91 through the inside of the first housing 64, the communication hole 90, and the inside of the second housing 65 is referred to as a valve passage 93. An annular locking claw 92 projects from the outer peripheral portion of the end portion on the outflow hole 91 side of the cylindrical portion 84 over the circumferential direction.

  The valve body 62 is disposed in a space defined by the first housing 64 and the end wall 83 of the second housing 65, and is disposed so as to be seated on the valve seat 75. A columnar valve shaft 94 that projects into the communication hole 90 in a state of being seated on the valve seat 75 projects from the valve body 62. The valve shaft 94 has an outer diameter smaller than the inner diameter of the communication hole 90 and is loosely fitted in the communication hole 90. Since the valve shaft 94 is loosely fitted and guided in the communication hole 90, the valve body 62 can reciprocate substantially along the axial direction of the first housing 64. A compression coil spring 63 is interposed between the valve body 62 and the end wall 83, and the valve body 62 is urged in a direction to be seated on the valve seat 75.

<Attachment structure of PCV valve to cylinder head cover>
As shown in FIG. 4, the fitting hole 58 formed in the cylinder head cover 13 is a through hole that communicates the inner surface and the outer surface of the cylinder head cover 13 (that is, the outside of the chamber 32 and the cylinder head cover 13). Is formed in a size that allows the large-diameter cylindrical portion 67 of the first housing 64 to be fitted with almost no gap. In another embodiment, the fitting hole 58 may be a stepped hole, and may be in contact with the outer peripheral surfaces of the large diameter cylindrical portion 67 and the small diameter cylindrical portion 68 of the first housing 64.

  A screw hole 105 having an axis substantially parallel to the axis of the fitting hole 58 is formed in the vicinity of the fitting hole 58 of the cylinder head cover 13.

  The PCV valve 52 is fastened to the cylinder head cover 13 by fitting the first housing 64 into the fitting hole 58 and screwing the bolt 107 into the screw hole 105 through the through hole 87. The insertion depth of the first housing 64 with respect to the fitting hole 58 is determined by the flange portion 85 and the extension portion 86 coming into contact with the outer surface of the cylinder head cover 13. In a state where the first housing 64 is fitted in the fitting hole 58, the end portion provided with the end wall 71 of the first housing 64 passes through the fitting hole 58 and enters the chamber 32. The first housing 64 is fitted in the fitting hole 58 with almost no gap. Further, two O-rings 79 are in close contact with the outer peripheral portion of the first housing 64 and the inner peripheral portion of the fitting hole 58 to seal a minute gap between the first housing 64 and the fitting hole 58. . The outer end of the bypass hole 89 (the outer peripheral side opening end of the first housing side through hole 77) is closed by the inner wall of the fitting hole 58.

  An end portion of the blow-by hose 53 formed of a flexible material is covered with an end portion of the cylindrical portion 84 of the PCV valve 52 on the outflow hole 91 side, and is prevented from being detached by a hose band 108. As a result, the blow-by hose 53 cannot be detached from the PCV valve 52, and gas (outside air, blow-by gas) cannot pass through the joint between the blow-by hose 53 and the PCV valve 52.

  As described above, when the internal pressure of the surge tank 39 of the intake system 16 drops below a predetermined value with respect to the internal pressure of the chamber 32, the PCV valve 52 attached to the cylinder head cover 13 is attached to the compression coil spring 63. The valve seat 75 is separated from the force. Thereby, the blow-by gas in the chamber 32 flows through the valve passage 93 and the blow-by hose 53 of the PCV valve 52 to the surge tank 39. At the same time, the internal pressure in the chamber 32 decreases, and the outside air that has passed through the air filter 36 flows from the intake pipe 37 into the chamber 32 through the ventilation passage 44.

  When the PCV valve 52 is disengaged from the fitting hole 58 due to forgetting to tighten the bolt 107 or due to poor fastening, the outer end of the bypass hole 89 is disengaged from the inner wall of the fitting hole 58 and the bypass hole 89 is opened. . In this case, when the internal pressure of the surge tank 39 of the intake system 16 is lower than the external pressure, the external air passes through the bypass hole 89 and flows into the PCV valve 52, passes through the blow-by hose 53, and enters the surge tank 39. Flows into.

  When the PCV valve 52 is detached from the fitting hole 58, the outflow hole 91 side is set to a predetermined negative pressure, and the outside of the inflow hole 74 and each bypass hole 89 is set to a predetermined positive pressure, all the bypass holes 89 are opened. When the valve body 62 is closed and has the maximum opening (the opening when the flow rate of the outside air flowing through the inflow hole 74 is maximized), the valve body 62 passes through the inflow hole 74 and the communication hole 90 and flows out. When the inflow hole 74 is closed and each bypass hole 89 is opened, the total value of the flow rate of the external air that passes through each bypass hole 89 and flows into the outflow hole 91 becomes larger than the flow rate of the outside air flowing to 91. In addition, the channel cross-sectional area of each bypass hole 89 is set sufficiently large. Thereby, when the PCV valve 52 is detached from the fitting hole 58, the PCV valve 52 flows into the surge tank 39 through the PCV valve 52 and the blow-by hose 53 rather than when the PCV valve 52 is fitted into the fitting hole 58. The amount of intake increases.

<PCV valve desorption detection device>
The PCV valve desorption detecting device is constituted by an ECU (electronic control unit) 120. The ECU 120 includes a CPU, a ROM, a RAM, a memory, and the like to constitute a microcomputer. The ECU 120 outputs a drive signal for opening and closing the throttle valve 38 based on a depression amount of an accelerator pedal (not shown), and outputs a drive signal for opening and closing the ISC valve 42 based on a predetermined calculation.

  The ECU 120 determines whether or not the engine 10 is in an idle state based on the opening degree of the throttle valve 38, and determines that the opening degree of the ISC valve 42 is equal to or less than a predetermined value when it is determined that the engine 10 is in an idle state. It is determined that the PCV valve 52 is detached from the fitting hole 58 when the opening of the ISC valve 42 is equal to or less than a predetermined value. The opening of the throttle valve 38 and the ISC valve 42 here may be a target opening set by the ECU 120, or may be an opening actually measured by a rotation sensor or the like. The ECU 120 normally determines that the ISC valve 42 has a certain degree of opening (for example, 20 to 30%) when the PCV valve 52 is properly fitted in the fitting hole 58 in the idle state. When the PCV valve 52 is detached from the fitting hole 58, the outside air is supplied to the surge tank 39 through the bypass hole 89 of the PCV valve 52, and the opening degree of the ISC valve 42 becomes extremely low. .

  When the PCV valve 52 configured as described above is detached from the fitting hole 58, the bypass hole 89 is opened, and the outside air can be circulated to the outflow hole 91 without passing through the inflow hole 74. In addition, the flow rate of outside air that can flow through the bypass hole 89 is larger than the flow rate of blow-by gas that can flow through the inflow hole 74 with the PCV valve 52 properly attached to the fitting hole 58. Therefore, when the PCV valve 52 is detached from the fitting hole 58, the amount of intake air flowing into the surge tank 39 can be increased. Thereby, the ECU 120 can detect the detachment of the PCV valve 52 from the fitting hole 58.

  Although the description of the specific embodiment is finished as described above, the present invention is not limited to the above embodiment and can be widely modified. For example, the fitting hole into which the PCV valve 52 is fitted may be formed in the cylinder block 11 or the cylinder head 12 so as to communicate the communication path 55 and the outside of the engine 10.

  DESCRIPTION OF SYMBOLS 10 ... Engine (internal combustion engine), 11 ... Cylinder block, 12 ... Cylinder head, 13 ... Cylinder head cover, 15 ... Engine main body, 16 ... Intake system, 21 ... Crankcase, 32 ... Chamber, 39 ... Surge tank, 44 ... Ventilation 50 ... Blow-by gas recirculation device, 51 ... Blow-by gas passage, 52 ... PCV valve (blow-by gas flow rate adjusting valve), 53 ... Blow-by hose (blow-by gas recirculation passage), 55 ... Communication passage, 58 ... Fitting hole, 61 DESCRIPTION OF SYMBOLS ... Valve housing, 62 ... Valve body, 63 ... Compression coil spring, 64 ... 1st housing, 65 ... 2nd housing, 74 ... Inflow hole (inflow port), 75 ... Valve seat, 77 ... 1st housing side through-hole, 84 ... Cylinder part, 85 ... Flange part (fastening part), 88 ... Second housing side through-hole, 89 ... Bypass hole (bypass passage), 90 ... Continuous Hole, 91 ... outlet hole (outlet), 93 ... valve passage 107 ... bolts, 108 ... hose band

Claims (5)

A blow-by gas passage formed in the engine body of the internal combustion engine;
A blow-by gas flow rate adjusting valve continuous to the blow-by gas passage;
A blow-by gas recirculation path having one end continuous with the blow-by gas flow rate adjustment valve and the other end continuing to the intake system of the internal combustion engine;
The blow-by gas flow adjustment valve is
A valve housing attached to the engine main body, comprising an inlet continuous with the blow-by gas passage, an outlet continuous with the blow-by gas recirculation path, and a valve passage communicating the inlet and the outlet;
A blow-by gas recirculation device provided so as to be seated on a valve seat formed in the valve passage, and having a valve body for opening and closing the valve passage;
The valve housing includes a bypass passage that communicates a portion of the valve passage between the valve seat and the outlet and an outer surface of the valve housing;
The opening end of the bypass passage on the outer surface side of the valve housing is closed by the engine body while the valve housing is attached to the engine body, while the valve housing is detached from the engine body. A blow-by gas recirculation device which is opened in a separated state. The engine body includes a fitting hole that communicates with the blow-by gas passage and into which the valve housing can be fitted.
The open end of the bypass passage on the outer surface side of the valve housing is closed by a hole wall of the fitting hole in a state where the valve housing is fitted into the fitting hole. The blow-by gas recirculation apparatus according to 1.   The blow-by gas recirculation device according to claim 2, wherein the valve housing includes a fastening portion that is fastened to the engine main body in a state where the valve housing is fitted in the fitting hole.   The blowby gas recirculation apparatus according to any one of claims 1 to 3, wherein the blowby gas recirculation path is detachably connected to the outlet of the valve housing.   The blow-by gas flow regulating valve closes the bypass passage when the outlet side is set to a predetermined negative pressure, and the outside of the inlet and the bypass passage is set to a predetermined positive pressure. When arranged at the maximum opening position, when the inlet is closed and the bypass passage is opened rather than the flow rate of the fluid flowing from the inlet to the outlet, the outlet from the bypass passage The blow-by gas recirculation device according to any one of claims 1 to 4, wherein a flow passage cross-sectional area of the bypass passage is set so that a flow rate of the fluid flowing into the flow passage increases.

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