JP6324582B2 - Low pressure loop exhaust recirculation system for engine - Google Patents

Description

  The present invention relates to a low-pressure loop exhaust gas recirculation device for an engine, which is provided in an engine with a supercharger and causes a part of exhaust gas discharged from the engine to an exhaust passage to flow into an intake passage as exhaust gas recirculation gas and return to the engine.

  Conventionally, it is well known that an exhaust gas recirculation (EGR) device is also provided in an engine equipped with a supercharger. The following Patent Document 1 describes an engine equipped with this type of supercharger and a low-pressure loop EGR device provided on the engine. The supercharger includes a turbine provided in the exhaust passage and a compressor provided in the intake passage and driven by the turbine. In the EGR device, an EGR passage is provided between an exhaust passage downstream of the turbine and an intake passage upstream of the compressor, and an EGR valve is provided in the EGR passage. In this EGR device, the EGR gas recirculation amount is limited by closing the EGR valve as necessary in order to prevent corrosion due to condensed water generated in the EGR passage while responding to strict NOx reduction requirements. It is like that.

  Here, if the pressure difference between the inlet and the outlet of the compressor becomes too large, the air flow may become unstable on the blade surface of the compressor, and surging may occur that causes self-excited vibration in the air flow. Therefore, in order to prevent this surging, an intake bypass passage that bypasses between the intake passage upstream of the compressor and the intake passage downstream of the compressor is provided, and an intake bypass valve is provided in the intake bypass passage. Open the bypass valve as needed. Thereby, the pressure difference between the inlet and outlet of the compressor can be reduced, and surging can be prevented. It is conceivable to provide a low-pressure loop EGR device even in an engine with a supercharger equipped with this type of intake bypass passage and intake bypass valve.

  An example of this type of intake bypass valve is described in Patent Document 2 below. The intake bypass valve includes a movable body having a valve member that opens and closes a valve seat provided between the inflow path and the outflow path of the intake bypass path on the outflow path side, and an elastic member that biases the movable body in the closing direction. , An electromagnetic device that moves the movable body in the opening direction by electromagnetic force against the biasing force of the elastic member, and a pressure that is provided between the stationary member of the electromagnetic device and the movable body and is partitioned with respect to the outflow path A pressure responsive member that forms an equilibrium chamber, and a pressure introduction path that is formed in the movable body and communicates with the inflow path and the pressure equilibrium chamber. In this intake bypass valve, the pressure of the air applied to the inflow path side and the pressure balance chamber side of the valve member is balanced in a closed state where the valve member is seated on the valve seat. The pressure introduction passage is provided with a dynamic pressure reducing member that reduces the dynamic pressure of air acting on the pressure equilibrium chamber. With this configuration, the dynamic pressure reducing member provided in the pressure introduction passage reduces the dynamic pressure of air acting on the pressure equilibrium chamber at the start of the valve opening, shortens the valve opening time, and improves the valve opening response. be able to.

JP 2012-229679 A JP 2013-83339 A

  By the way, in the engine system with a supercharger provided with the low pressure loop type EGR device, it is assumed that an intake bypass valve is provided in the intake bypass passage as described in Patent Document 2. In this case, when the EGR valve is opened and EGR gas is allowed to flow from the EGR passage to the intake passage in the supercharging region where the supercharger operates, the outlet pressure of the compressor changes from low pressure to high pressure. Due to this pressure change, EGR gas may flow into the pressure equilibrium chamber of the intake bypass valve, and the flowed EGR gas may remain in the pressure equilibrium chamber. When the remaining EGR gas is cooled after the engine is stopped or the like, condensed water is generated by the moisture in the EGR gas. Therefore, the condensed water may corrode the drive part inside the intake bypass valve, or the condensed part may freeze and the drive part may stick, which may hinder the normal operation of the intake bypass valve. It was.

  The present invention has been made in view of the above circumstances, and an object thereof is to prevent condensed water from being generated by the residual exhaust gas in the intake bypass valve into which the exhaust gas flows. It is an object to provide a low-pressure loop exhaust recirculation device for an engine.

  In order to achieve the above object, an invention according to claim 1 is provided between an intake passage and an exhaust passage of an engine, and a supercharger for boosting intake air in the intake passage, and a supercharger, A compressor disposed in the intake passage, a turbine disposed in the exhaust passage, a rotating shaft that connects the compressor and the turbine so as to be integrally rotatable, and an exhaust gas discharged from the combustion chamber of the engine to the exhaust passage. The exhaust recirculation passage that flows into the intake passage as the exhaust recirculation gas and recirculates to the combustion chamber, and the exhaust recirculation passage are connected to the exhaust passage downstream of the turbine and the outlet connected to the intake passage upstream of the compressor An exhaust gas recirculation valve for adjusting the flow of the exhaust gas recirculation gas in the exhaust gas recirculation passage, and a portion upstream of the compressor and a downstream of the compressor An intake bypass passage that bypasses the intake bypass passage, an intake bypass valve that opens and closes the intake bypass passage, and an intake bypass valve that is provided on the intake bypass passage. , A movable body having a valve member provided so as to be seated on the valve seat, a driving means for driving the movable body, and a pressure balancing chamber provided and partitioned between the driving means and the movable body And a pressure introduction passage formed in the movable body and communicating with the intake bypass passage and the pressure equilibrium chamber, and electronic control for controlling at least the exhaust gas recirculation valve and the intake bypass valve according to the operating state of the engine In the low-pressure loop exhaust recirculation device for an engine equipped with the device, the electronic control unit is configured to control the exhaust recirculation gas remaining in the pressure equilibrium chamber of the intake bypass valve when the exhaust recirculation valve is closed. To reduce the degree, and the spirit that performs control so as to repeatedly open and close the intake air bypass valve.

  According to the configuration of the above invention, when the intake bypass valve opens from the closed state, the movable body moves so that the exhaust gas recirculation gas remaining in the pressure equilibrium chamber passes through the pressure introduction passage. It is discharged into the passage. Thereafter, when the intake bypass valve is closed from the open state, the movable body moves, so that new air in the intake bypass passage flows into the pressure equilibrium chamber through the pressure introduction passage.

  In order to achieve the above object, according to a second aspect of the present invention, in the first aspect of the present invention, the electronic control unit estimates the concentration of the exhaust gas recirculation gas remaining in the pressure equilibrium chamber, and the estimation is performed. The purpose is to control the number of times the intake bypass valve is repeatedly opened and closed in accordance with the concentration.

  According to the configuration of the invention described above, in addition to the operation of the invention described in claim 1, the concentration of the exhaust gas recirculation gas remaining in the pressure equilibrium chamber is estimated, and the opening and closing of the intake bypass valve is repeated according to the estimated concentration. The number of times is increased or decreased.

  In order to achieve the above object, according to a third aspect of the present invention, in the first or second aspect of the present invention, the electronic control unit performs control to repeatedly open and close the intake bypass valve in an engine operating state. It is intended to be implemented only when is in a non-supercharged area.

  According to the first or third aspect of the invention, the concentration of the exhaust gas recirculation gas remaining in the pressure equilibrium chamber of the intake bypass valve can be reduced, and the generation of condensed water can be prevented.

  According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, the concentration of the exhaust gas recirculation gas remaining in the pressure equilibrium chamber of the intake bypass valve can be efficiently reduced, and the intake bypass The durability of the intake bypass valve can be improved without causing the valve to perform unnecessary opening and closing operations.

The schematic block diagram which shows the gasoline engine system with a supercharger which concerns on 1st Embodiment and contains a low pressure loop type EGR apparatus. Sectional drawing which concerns on 1st Embodiment and shows the structure of ABV. The flowchart which shows an example of the processing content of scavenging control (residual gas removal control) concerning 1st Embodiment. The flowchart which shows an example of the processing content of scavenging control (residual gas removal control) concerning 2nd Embodiment. The schematic block diagram which shows the gasoline engine system with a supercharger which concerns on 3rd Embodiment and contains a low-pressure loop type EGR apparatus. Sectional drawing which concerns on 3rd Embodiment and shows the structure of ABV. The schematic block diagram which shows the gasoline engine system with a supercharger which concerns on 4th Embodiment and contains a low pressure loop type EGR apparatus. Sectional drawing which concerns on 4th Embodiment and shows the structure of ABV. The flowchart which shows an example of the control content of VSV concerning 4th Embodiment. The schematic block diagram which shows the gasoline engine system with a supercharger which concerns on 5th Embodiment and contains a low pressure loop type EGR apparatus. The schematic block diagram which shows the gasoline engine system with a supercharger which concerns on 6th Embodiment (7th Embodiment) and contains a low voltage | pressure loop type EGR apparatus. The flowchart which concerns on 6th Embodiment and shows an example of the control content of a pressure pump. The schematic block diagram which shows the gasoline engine system with a supercharger which concerns on 8th Embodiment and contains a low pressure loop type EGR apparatus. Sectional drawing which concerns on 8th Embodiment and shows the structure of ABV. The flowchart which shows an example of the control content of ABV concerning 8th Embodiment. The flowchart which shows an example of the control content of ABV concerning 9th Embodiment. The schematic block diagram which shows the gasoline engine system with a supercharger which concerns on 10th Embodiment and contains a low pressure loop type EGR apparatus and a blow-by gas reduction apparatus. The schematic block diagram which shows the gasoline engine system with a supercharger which concerns on 11th Embodiment and contains a low pressure loop type EGR apparatus and a blow-by gas reduction apparatus. The schematic block diagram which shows the gasoline engine system with a supercharger which concerns on 12th Embodiment and contains a low pressure loop type EGR apparatus and a blow-by gas reduction apparatus.

<First Embodiment>
Hereinafter, a first embodiment of a low-pressure loop exhaust gas recirculation apparatus for an engine according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic configuration diagram showing a supercharged gasoline engine system including a low-pressure loop exhaust gas recirculation device (low-pressure loop EGR device) in this embodiment. This engine system includes a reciprocating engine 1. An intake passage 3 is connected to the intake port 2 of the engine 1, and an exhaust passage 5 is connected to the exhaust port 4. An air cleaner 6 is provided at the inlet of the intake passage 3. A supercharger 7 for boosting the intake air in the intake passage 3 is provided in the intake passage 3 downstream of the air cleaner 6 between the exhaust passage 5 and the intake passage 3.

  The supercharger 7 includes a compressor 8 disposed in the intake passage 3, a turbine 9 disposed in the exhaust passage 5, and a rotating shaft 10 that connects the compressor 8 and the turbine 9 so as to be integrally rotatable. The supercharger 7 rotates the turbine 9 by the exhaust gas flowing through the exhaust passage 5 and integrally rotates the compressor 8 via the rotary shaft 10 to boost the intake air in the intake passage 3, that is, perform supercharging. It is like that.

  An exhaust bypass passage 11 that bypasses the turbine 9 is provided in the exhaust passage 5 adjacent to the supercharger 7. A waste gate valve 12 is provided in the exhaust bypass passage 11. By adjusting the exhaust gas flowing through the exhaust bypass passage 11 by the waste gate valve 12, the exhaust gas flow rate supplied to the turbine 9 is adjusted, the rotational speeds of the turbine 9 and the compressor 8 are adjusted, and supercharging by the supercharger 7 is performed. The pressure is adjusted.

  Adjacent to the supercharger 7, the intake passage 3 is provided with an intake bypass passage 41 that bypasses a portion upstream from the compressor 8 and a portion downstream from the compressor 8. The intake bypass passage 41 is provided with an intake bypass valve (hereinafter referred to as “ABV”) 42 for opening and closing the passage 41. By adjusting the amount of intake air flowing through the intake air bypass passage 41 by the ABV 42, the pressure difference between the inlet and the outlet of the compressor 8 is reduced, and surging is prevented. The other end of the residual gas removal passage 43 communicating with the inside of the ABV 42 is connected to the ABV 42 in order to discharge (remove) the EGR gas remaining inside the ABV 42. One end of the residual gas removal passage 43 is connected to the intake passage 3 upstream from the compressor 8 and upstream from the outlet 17 a of the EGR passage 17.

  In the intake passage 3, an intercooler 13 is provided between the compressor 8 and the engine 1. The intercooler 13 cools intake air that has been pressurized by the compressor 8 to a high temperature to an appropriate temperature. A surge tank 3 a is provided in the intake passage 3 between the intercooler 13 and the engine 1. An electronic throttle device 14 which is an electric throttle valve is provided in the intake passage 3 downstream from the intercooler 13 and upstream from the surge tank 3a. The electronic throttle device 14 detects a butterfly throttle valve 21 disposed in the intake passage 3, a DC motor 22 for opening and closing the throttle valve 21, and an opening degree (throttle opening degree) TA of the throttle valve 21. And a throttle sensor 23 for performing the operation. The electronic throttle device 14 is configured such that the opening degree of the throttle valve 21 is adjusted by the throttle valve 21 being opened and closed by the DC motor 22 in accordance with the operation of the accelerator pedal 26 by the driver. In this embodiment, the electronic throttle device 14 corresponds to an example of an intake air amount adjustment valve of the present invention. The exhaust passage 5 downstream from the turbine 9 is provided with a catalytic converter 15 as an exhaust catalyst for purifying exhaust.

  The engine 1 is provided with an injector 25 for injecting and supplying fuel to the combustion chamber 16. Fuel is supplied to the injector 25 from a fuel tank (not shown). The engine 1 is provided with a spark plug 29 corresponding to each cylinder. Each spark plug 29 is ignited by receiving a high voltage output from the igniter 30. The ignition timing of each spark plug 29 is determined by the high voltage output timing from the igniter 30. The spark plug 29 and the igniter 30 constitute an ignition device.

  In this embodiment, the engine 1 is provided with a low-pressure loop EGR device. The EGR device includes an exhaust gas recirculation passage (EGR passage) 17 for flowing a part of the exhaust gas discharged from the combustion chamber 16 of the engine 1 into the exhaust passage 5 as EGR gas to the intake passage 3 and returning it to the combustion chamber 16; An exhaust gas recirculation valve (EGR valve) 18 for adjusting the flow of EGR gas in the passage 17 is provided. In this embodiment, the EGR passage 17 is provided between the exhaust passage 5 downstream from the catalytic converter 15 and the intake passage 3 upstream from the compressor 8. That is, the EGR passage 17 has an inlet 17 b connected to the exhaust passage 5 downstream from the turbine 9 and the catalytic converter 15, and an outlet 17 a connected to the intake passage 3 upstream from the compressor 8. The EGR passage 17 is provided with an EGR cooler 20 for cooling the EGR gas flowing through the passage 17. In this embodiment, the EGR valve 18 is disposed in the EGR passage 17 downstream of the EGR cooler 20.

  As shown in FIG. 1, the EGR valve 18 is configured as a poppet valve and as an electric valve. That is, the EGR valve 18 includes a valve body 32 that is driven by the motor 31. The valve body 32 has a substantially conical shape, and is provided so as to be seated on a valve seat 33 provided in the EGR passage 17. The motor 31 includes an output shaft 34 configured to be capable of reciprocating (stroke) in a straight line, and a valve body 32 is fixed to the tip of the output shaft 34. The output shaft 34 is supported by a housing constituting the EGR passage 17 via a bearing 35. The opening degree of the valve body 32 with respect to the valve seat 33 is adjusted by moving the output shaft 34 of the motor 31 with a stroke. The output shaft 34 of the EGR valve 18 is provided so as to be able to perform a stroke movement by a predetermined stroke from a fully closed state in which the valve body 32 is seated on the valve seat 33 to a fully open state in which the valve body 32 contacts the bearing 35. In this embodiment, in order to realize a large amount of EGR, the opening area of the valve seat 33 is enlarged as compared with the conventional technique. Accordingly, the valve body 32 is enlarged.

  According to the low-pressure loop EGR device described above, negative pressure is generated in the intake passage 3 upstream of the compressor 8 when the engine 1 is in operation and the supercharger 7 operates. At this time, when the EGR valve 18 is opened, a part of the exhaust discharged from the combustion chamber 16 to the exhaust passage 5 flows as EGR gas to the intake passage 3 upstream of the compressor 8 via the EGR passage 17. 8 and the intake passage 3 further flow back to the combustion chamber 16.

  In this embodiment, in order to execute fuel injection control, ignition timing control, intake air amount control, EGR control, supercharging control, and the like according to the operating state of the engine 1, the injector 25, the igniter 30, and the electronic throttle device 14 are controlled. The DC motor 22, the motor 31 of the EGR valve 18, and the ABV 42 are controlled by an electronic control unit (ECU) 50 in accordance with the operating state of the engine 1. The ECU 50 stores in advance a central processing unit (CPU), a predetermined control program and the like, various memories for temporarily storing a calculation result of the CPU, and the like, an external input circuit connected to these parts, and an external And an output circuit. An igniter 30, an injector 25, a DC motor 22, a motor 31, and an ABV 42 are connected to the external output circuit. The external input circuit is connected to various sensors 27 and 51 to 55 corresponding to an example of an operation state detection means for detecting the operation state of the engine 1 including the throttle sensor 23 so that various engine signals are input. It has become.

  Here, in addition to the throttle sensor 23, an accelerator sensor 27, an intake pressure sensor 51, a rotation speed sensor 52, a water temperature sensor 53, an air flow meter 54, and an air-fuel ratio sensor 55 are provided as various sensors. The accelerator sensor 27 detects an accelerator opening ACC that is an operation amount of the accelerator pedal 26. The intake pressure sensor 51 detects the intake pressure PM in the surge tank 3a downstream from the throttle valve 21. The rotational speed sensor 52 detects the rotational angle (crank angle) of the crankshaft 1a of the engine 1 and detects the change in the crank angle as the rotational speed (engine rotational speed) NE of the engine 1. The water temperature sensor 53 detects the cooling water temperature THW of the engine 1. The air flow meter 54 is provided in the intake passage 3 immediately downstream of the air cleaner 6 and detects an intake air amount Ga flowing therethrough. The air-fuel ratio sensor 55 is provided in the exhaust passage 5 immediately upstream of the catalytic converter 15, and detects the air-fuel ratio A / F in the exhaust flowing therethrough.

  In this embodiment, the ECU 50 controls the EGR valve 18 in order to execute the EGR control in accordance with the operation state of the engine 1 in the entire operation region of the engine 1. Further, the ECU 50 normally controls the opening of the EGR valve 18 based on the operating state detected during the acceleration operation or the steady operation of the engine 1, and the EGR valve 18 when the engine 1 is stopped, idle operation, or deceleration operation. Is controlled to be fully closed.

  In this embodiment, the ECU 50 controls the electronic throttle device 14 based on the accelerator opening ACC in order to drive the engine 1 in response to a driver's request. Further, the ECU 50 controls to open the electronic throttle device 14 based on the accelerator opening ACC during acceleration operation or steady operation of the engine 1 and closes the electronic throttle device 14 when the engine 1 is stopped or decelerated. It has become. Thereby, the throttle valve 21 is opened during the acceleration operation or the steady operation of the engine 1 and is fully closed when the engine 1 is stopped or decelerated.

  Next, the configuration of the ABV 42 will be described in detail. FIG. 2 is a sectional view showing the configuration of the ABV 42 in this embodiment. As shown in FIG. 2, the ABV 42 is installed in the casing 61 of the supercharger 7. The ABV 42 is arranged vertically so that the opening / closing direction of a valve member 62 described later is the vertical direction (vertical direction). An intake bypass passage 41 is formed in the casing 61. The intake bypass passage 41 has an inflow passage 63 and an outflow passage 64. A valve seat 65 is formed between the inflow path 63 and the outflow path 64. A mounting hole 66 is formed in the casing 61 at a concentric position above the valve seat 65. The inner diameter of the mounting hole 66 is larger than the inner diameter of the valve seat 65.

  The ABV 42 includes an electromagnetic device 67 corresponding to an example of the driving unit of the present invention. The electromagnetic device 67 includes a housing 68, a coil 69, a fixed core 70, an end plate 71, and the like. The housing 68 is formed in a cylindrical shape. The coil 69 is accommodated in the housing 68 while being wound around the bobbin 72. The fixed core 70 is formed in a cylindrical shape and is disposed in the hollow portion of the bobbin 72. The end plate 71 is formed in an annular plate shape, and is provided concentrically on the lower end surface of the bobbin 72. The housing 68 as a stator, the fixed core 70 and the end plate 71 are each formed of a magnetic material such as iron, and form a fixed magnetic circuit. A mounting flange 68 a that protrudes outward in the radial direction is formed at the lower end of the housing 68. An inner flange 68b is formed inside the mounting flange 68a. The outer peripheral portion of the end plate 71 is sandwiched between the inner flange 68b and the bobbin 72.

  A guide shaft 73 protruding downward is concentrically attached to the lower end portion of the fixed core 70. A cylindrical movable core 74 is fitted to the guide shaft 73 through a resin guide sleeve 75 so as to be reciprocally movable in the vertical direction. The movable core 74 is loosely fitted in the hollow portion of the end plate 71. The movable core 74 is formed of a magnetic material such as iron. The guide sleeve 75 is fixed to the movable core 74 by press fitting or the like. A coil spring 76 fitted to the guide shaft 73 is interposed between the guide sleeve 75 and the fixed core 70. A coil spring 76 corresponding to an example of an elastic member biases the movable core 74 away from the fixed core 70, that is, downward.

  When the coil 69 of the electromagnetic device 67 is not excited, the biasing force of the coil spring 76 biases the movable core 74 away from the fixed core 70, that is, downward. When the coil 69 of the electromagnetic device 67 is excited, the movable core 74 is attracted to the fixed core 70 side, that is, upward, against the urging force of the coil spring 76 by the electromagnetic force.

  At the lower end of the movable core 74, an attachment cylinder portion 74a having a reduced outer diameter is formed. A circular dish-shaped stopper plate 77, an annular diaphragm 78, a reverse cup-shaped cylindrical member 79, and a retaining ring 80 are sequentially and concentrically fitted to the mounting cylindrical portion 74a, and the mounting cylindrical portion 74a It is fixed by caulking all around the lower end. The outer peripheral portion of the stopper plate 77 abuts on the end plate 71 when the movable core 74 moves upward, and restricts further upward movement of the movable core 74. The diaphragm 78 is formed from a resinous rubber-like elastic material. The inner peripheral portion of the diaphragm 78 is sandwiched between the stopper plate 77 and the cylindrical member 79.

  An annular diaphragm guide 81 made of resin is concentrically connected to the lower surface side of the inner flange 68 b of the housing 68. Between the inner flange 68b and the diaphragm guide 81, the outer peripheral portion of the diaphragm 78 is sandwiched. Thereby, the pressure equilibrium chamber 82 provided between the various fixed-side members of the electromagnetic device 67 and the movable core 74 and partitioned in a sealed manner is formed.

  In the movable core 74, a plurality of lateral holes 74b that are adjacent to the upper side of the stopper plate 77 and penetrate in the radial direction are formed at equal intervals in the circumferential direction. The lateral hole 74 b communicates the hollow portion 74 c of the movable core 74 and the pressure equilibrium chamber 82. The total opening area of the plurality of horizontal holes 74 b is set to be approximately the same as the opening area of the hollow portion 74 c of the movable core 74. A series of pressure introduction passages 83 are formed by the internal space 79a of the cylindrical member 79, the hollow portion 74c of the movable core 74, and the lateral hole 74b.

  A resin shielding plate 84 is provided at the lower end of the cylindrical member 79. The shielding plate 84 is formed in a disc shape. On the lower surface of the shielding plate 84, a valve portion 84a made of an annular protrusion is formed concentrically. The shielding plate 84 is formed with a plurality of ventilation holes 84b penetrating in the thickness direction at equal intervals in the circumferential direction. Each vent hole 84b has a circular shape and is disposed on the inner peripheral side of the valve portion 84a. The total opening area of the plurality of vent holes 84 b is set to be approximately the same as the opening area of the hollow portion 74 c of the movable core 74. A pressure receiving wall portion that receives air pressure is formed by a plate-like portion excluding the vent hole 84b on the inner peripheral side of the valve portion 84a of the shielding plate 84.

  The shielding plate 84 is fitted into the lower end opening of the cylindrical member 79 so as to close the opening. The shielding plate 84 is fixed to the cylindrical member 79 in a concentric and vertically positioned state. The caulking portion of the cylindrical member 79 is referred to as a caulking portion. The pressure receiving wall portion of the shielding plate 84 is disposed with a positional relationship overlapping the hollow portion 74 c of the movable core 74 in a projected view as viewed from the axial direction of the movable core 74. The ventilation hole 84b of the shielding plate 84 is disposed with a positional relationship that does not overlap the hollow portion 74c of the movable core 74 in a projected view as viewed from the axial direction of the movable core 74. The valve member 62 is configured by the shielding plate 84 having the valve portion 84 a and the tubular member 79. The movable core 85, the stopper plate 77, the inner periphery of the diaphragm 78, the retaining ring 80, the valve member 62, and the like constitute a movable body 85 that can reciprocate in the vertical direction. The housing 68, the coil 69, the fixed core 70, the end plate 71, the guide shaft 73, and the outer periphery of the diaphragm 78 constitute a fixed side member 86.

  The ABV 42 is installed on the casing 61. Specifically, the housing 68 is disposed on the casing 61 so as to be concentric with the mounting hole 66 and close the mounting hole 66. The mounting flange 68a of the housing 68 is fixed to the casing 61 by fastening or the like. The cylindrical member 79 is disposed in the outflow path 64 from the mounting hole 66 of the casing 61. The valve portion 84 a of the shielding plate 84 corresponds to the valve seat 65. An O-ring 87 for sealing is provided between the casing 61 and the mounting flange 68a.

  An escape chamber 88 that allows the movable core 74 to move up and down is formed between the fixed core 70 and the upper end of the movable core 74. The fixed core 70 and the housing 68 are formed with a communication passage 89 that allows the escape chamber 88 to communicate with the outside. The communication path 89 communicates with the pressure balance chamber 82 through a clearance chamber 88 and a gap between the movable core 74 and the end plate 71. In this embodiment, the pressure balance chamber 82 corresponds to an example of a specific portion in the present invention. The EGR gas flows or flows into the pressure balance chamber 82 together with the intake air flowing through the intake bypass passage 41. Here, when the supercharger 7 is stopped together with the engine 1, EGR gas may remain in the pressure equilibrium chamber 82. The communication passage 89 is formed for discharging the EGR gas remaining in the pressure balance chamber 82 to the outside of the housing 68. A pipe joint 90 is fixed to the upper portion of the housing 68 corresponding to the outlet of the communication passage 89. The other end of the residual gas removal passage 43 is connected to the pipe joint 90. A check valve 44 composed of a reed valve is provided inside the pipe joint 90. The check valve 44 stops the flow of air from the communication passage 89 toward the residual gas removal passage 43 and allows the air flow in the opposite direction.

  Next, the operation of the ABV 42 will be described. When the electromagnetic device 67 is not energized (non-excited), the movable body 85 including the movable core 74 is urged away from the fixed core 70 by the urging force of the coil spring 76. As a result, the valve portion 84a of the shielding plate 84 of the valve member 62 is seated on the valve seat 65, and the valve is closed. On the other hand, when the electromagnetic device 67 is energized (excited), the movable body 85 moves in the opening direction against the urging force of the coil spring 76 by the electromagnetic force. As a result, the valve portion 84a is separated from the valve seat 65 and is opened.

  In the valve closed state of the ABV 42, the diaphragm 78 defines the pressure equilibrium chamber 82 corresponding to the outflow path 64. The inflow passage 63 acts on the pressure equilibrium chamber 82 via the vent hole 84 b of the shielding plate 84 and the pressure introduction passage 83. For this reason, the pressure of the air applied before and after the valve member 62, that is, the inflow path 63 side and the pressure equilibrium chamber 82 side is balanced. Thereby, the urging force of the coil spring 76 and the electromagnetic force of the electromagnetic device 67 are reduced.

  By the way, when the ABV 42 is opened, particularly when the valve is opened, most of the high-pressure air flowing out from the inflow path 63 through the hollow portion of the valve seat 65 to the outflow path 64 collides with the pressure receiving wall portion of the shielding plate 84. . At the same time, most of the air flows into the outflow passage 64, but a part of the air flows into the pressure equilibrium chamber 82 from the vent hole 84 b of the shielding plate 84 through the pressure introduction passage 83. At this time, the dynamic pressure of the air acting on the pressure equilibrium chamber 82 through the vent hole 84b of the shielding plate 84 is the movement of the air acting on the pressure equilibrium chamber 82 through the hollow portion 74c of the movable core 74 when the shielding plate 84 is omitted. Lower than pressure. Therefore, the dynamic pressure of air acting on the pressure equilibrium chamber 82 at the start of valve opening is reduced. Thereby, compared with the conventional example, the pressure of the air in the pressure equilibrium chamber 82 is easily lowered, and the valve opening time required from the start to the end of the valve opening is shortened. Further, the internal space of the valve member 62 by the cylindrical member 79 and the shielding plate 84 has a passage cross-sectional area larger than the opening area (passage area) of the hollow portion 74c of the movable core 74 and the vent hole 84b of the shielding plate 84. Therefore, it functions as a buffer chamber for the dynamic pressure of air acting on the pressure equilibrium chamber 82 (same as the internal space 79a of the cylindrical member 79). The buffer chamber corresponds to the inlet side passage of the pressure introduction passage 83.

  Here, in the ABV 42 of this embodiment, the EGR gas that has flowed into the pressure equilibrium chamber 82 may remain in the pressure equilibrium chamber 82. Thus, when the EGR gas remaining in the ABV 42 is cooled after the engine is stopped or the like, condensed water is generated by the water in the EGR gas, and the normal operation of the ABV 42 may be hindered by the condensed water. is there. Therefore, in this embodiment, the ECU 50 executes the following scavenging control (residual gas removal control) in order to prevent the condensed water from being generated by the residual EGR gas in the ABV 42, particularly in the pressure equilibrium chamber 82. It is supposed to be.

  FIG. 3 is a flowchart showing an example of processing contents of this scavenging control (residual gas removal control). When the process proceeds to this routine, in step 100, the ECU 50 determines whether or not the EGR is switched from on to off. If this determination is negative, the ECU 50 returns the process to step 100. If the determination result is affirmative, the ECU 50 proceeds to step 110.

  In step 110, the ECU 50 determines whether or not the operating state of the engine 1 is in a non-supercharging region. If the determination result is negative, the ECU 50 proceeds to step 230. If the determination result is affirmative, the ECU 50 proceeds to step 120.

  In step 230, the ECU 50 resets the scavenging completion determination flag XABVOC to “0”. The flag XABVOC is set to “1” when the scavenging of the pressure equilibrium chamber 82 is completed by removing the residual EGR gas from the pressure equilibrium chamber 82 of the ABV 42, and “0” when the scavenging is not completed. To be reset.

  Next, in step 240, the ECU 50 resets the ABV valve opening control flag XABVO to “0”. The flag XABVO is set to “1” when the ABV 42 is opened, and is reset to “0” when the valve is closed.

  Next, in step 250, the ECU 50 resets the ABV scavenging number ABVOC described later to “0”. In step 260, the ECU 50 controls the valve closing of the ABV 42, and then returns the process to step 100.

  On the other hand, in step 120, the ECU 50 determines whether or not the scavenging completion determination flag XABVOC is “0”. If this determination result is negative, the ECU 50 moves the process to step 240, and subsequently executes the processes of step 250 and step 260. If the determination result is affirmative, the ECU 50 proceeds to step 130.

  In step 130, the ECU 50 determines whether or not the ABV valve opening control flag XABVO is “0”. If this determination result is negative, the ECU 50 proceeds to step 170. If the determination result is affirmative, the ECU 50 proceeds to step 140.

  In step 140, the ECU 50 controls the valve opening of the ABV 42. Next, in step 150, the ECU 50 waits for a predetermined time to elapse after the valve opening, and then proceeds to step 160. In step 160, the ECU 50 sets the ABV valve opening control flag XABVO to “1” and returns the process to step 100.

  On the other hand, in step 170, the ECU 50 controls the ABV 42 to be closed. Next, in step 180, the ECU 50 waits for a predetermined time to elapse after the valve is closed and proceeds to step 190. In step 190, the ECU 50 calculates the current ABV scavenging number ABVOC (i) by adding “1” to the ABV scavenging number ABVOC (i−1) up to the previous time.

  Next, at step 200, the ECU 50 determines whether or not the ABV scavenging frequency ABVOC is greater than a predetermined value C1. If the determination result is affirmative, the ECU 50 proceeds to step 210. If the determination result is negative, the ECU 50 proceeds to step 220.

  In step 210, the ECU 50 sets the scavenging completion determination flag XABVOC to “1”, assuming that scavenging has been completed, and returns the process to step 100.

  In step 220, since the ABV 42 is closed, the ECU 50 resets the ABV valve opening control flag XABVO to “0” and returns the process to step 100.

  In this embodiment, the communication passage 89, the pipe joint 90, and the residual gas removal passage 43 correspond to an example of the residual gas removal means of the present invention. According to the above control, the ECU 50 alternately repeats the opening and closing of the ABV 42 a predetermined number of times when the EGR is switched from on to off and the operating state of the engine 1 is in the non-supercharging range. It has become.

  According to the low-pressure loop EGR device for an engine according to this embodiment described above, the ABV 42 has the pressure equilibrium chamber 82 as a specific portion through which the EGR gas flows or flows, and the EGR gas remaining in the pressure equilibrium chamber 82 is removed. As a means for removing residual gas, a communication passage 89, a pipe joint 90, and a residual gas removal passage 43 are provided. Thereby, the EGR gas remaining in the pressure equilibrium chamber 82 of the ABV 42 can be reliably removed. For this reason, it is possible to prevent EGR gas from remaining in the pressure equilibrium chamber 82 after the engine 1 is stopped and the like, and even if the ABV 42 is cooled, it is possible to prevent generation of condensed water due to moisture in the EGR gas. I can do it. That is, it is possible to prevent the condensed water from being generated by the residual EGR gas in the pressure equilibrium chamber 82 where the EGR gas flows or flows. As a result, there is no possibility that the condensed water corrodes the driving unit (electromagnetic device 67 or the like) inside the ABV 42, or the condensed driving water freezes to fix the driving unit, thereby hindering the normal operation of the ABV 42. .

  In this embodiment, when the ABV 42 is changed from the open state to the closed state, the check valve 44 is opened and external air is sucked into the pressure balance chamber 82 from the residual gas removal passage 43. This air reduces the concentration of EGR gas remaining in the pressure equilibrium chamber 82. Thereafter, when the ABV 42 changes from the closed state to the open state, the check valve 44 is closed, and the EGR gas whose concentration is reduced in the pressure equilibrium chamber 82 is discharged to the inflow path 63. By repeating this, the concentration of the EGR gas remaining in the pressure equilibrium chamber 82 can be reduced to a predetermined value or less. Here, even if the residual EGR gas cannot be completely removed (removed) from the pressure equilibrium chamber 82, if the residual EGR gas has a concentration equal to or lower than a predetermined value, the engine 1 is stopped and the ABV 42 is cooled. No water is generated and there is no problem.

Second Embodiment
Next, a second embodiment of the low-pressure loop EGR device for an engine according to the present invention will be described in detail with reference to the drawings.

  In each embodiment described below, the description of the same configuration as in the first embodiment will be omitted, and different points will be mainly described.

  The second embodiment is different from the first embodiment in terms of processing contents of scavenging control (residual gas removal control). FIG. 4 is a flowchart showing an example of processing contents of scavenging control (residual gas removal control). This flowchart differs from the flowchart of FIG. 3 in that step 100 is changed to step 101 and that steps 110 and 230 are not present.

  In the first embodiment, the scavenging condition (remaining EGR gas removal condition) is EGR cut and the non-supercharging region. In the second embodiment, the engine stop condition is the scavenging condition (residual EGR gas Condition to be removed). That is, in step 101, when the ignition key (IG) is switched from on to off, scavenging is performed (residual EGR gas is removed).

  According to this embodiment, in addition to the effects of the first embodiment, after the engine 1 is stopped, the EGR gas remaining in the pressure equilibrium chamber 82 of the ABV 42 can be removed from the pressure equilibrium chamber 82 regardless of the operation of the vehicle. Therefore, the operation of the engine 1 is not affected.

<Third Embodiment>
Next, a third embodiment of the low-pressure loop EGR device for an engine according to the present invention will be described in detail with reference to the drawings.

  FIG. 5 shows a schematic configuration diagram of a gasoline engine system with a supercharger including a low-pressure loop EGR device in this embodiment. This gasoline engine system is different from the gasoline engine system of FIG. 1 in that a residual gas removal passage 91 is provided instead of the residual gas removal passage 43. That is, the other end 91b of the residual gas removal passage 91 is connected to and communicates with the pipe joint 90 provided in the ABV 42. One end 91 a of the residual gas removal passage 91 is connected to and communicates with the intake passage 3 downstream from the electronic throttle device 14.

  FIG. 6 is a sectional view showing the configuration of the ABV 42 of this embodiment. 6 differs in that a check valve 92 is provided instead of the check valve 44 in the ABV 42 of FIG. The check valve 92 is attached to the outlet surface of the communication passage 89 in the housing 68, allows a gas flow from the communication passage 89 toward the residual gas removal passage 91, and flows toward the communication passage 89 from the residual gas removal passage 91. It is designed to prevent the flow. In this embodiment, the communication passage 89, the pipe joint 90, and the residual gas removal passage 91 correspond to an example of the residual gas removal means of the present invention.

  According to this embodiment, the negative pressure generated in the intake passage 3 downstream from the throttle valve 21 during the operation of the engine 1 acts on the pressure equilibrium chamber 82 of the ABV 42 via the residual gas removal passage 91 and the like, so that the pressure is increased. The EGR gas remaining in the balance 82 is sucked and removed to the intake passage 3 downstream from the throttle valve 21 through the residual gas removal passage 91 and the like. For this reason, it is possible to prevent the condensed water from being generated by the residual EGR gas in the pressure equilibrium chamber 82 where the EGR gas flows or flows. Further, the EGR gas remaining in the pressure balancing chamber 82 of the ABV 42 can be removed using the negative pressure generated in the intake passage 3 downstream from the throttle valve 21 and discharged to the intake passage 3 downstream from the throttle valve 21. .

  According to this embodiment, since the engine light load (idle, deceleration) region is EGR cut, the inflow path 63 and the outflow path 64 are fresh. The fresh air flows into the pressure equilibrium chamber 82 through the vent hole 84b, whereby the pressure equilibrium chamber 82 is scavenged. That is, the EGR gas remaining in the pressure equilibrium chamber 82 is removed (discharged) to the surge tank 3a through the communication passage 89, the check valve 92, the pipe joint 90, and the residual gas removal passage 91. At this time, the surge tank 3a is in a negative pressure state because the engine 1 is operated at a light load and the throttle valve 21 is closed, and the EGR gas remaining in the pressure equilibrium chamber 82 due to the negative pressure acts. It can be sucked and discharged (removed). On the other hand, when the surge tank 3a is in the positive pressure state, the check valve 92 is closed, so that the EGR gas discharged to the surge tank 3a does not return from the residual gas removal passage 91 to the communication passage 89. Then, by repeating this, the concentration of EGR gas remaining in the pressure equilibrium chamber 82 can be set to a predetermined value or less. Even if the residual EGR gas cannot be completely removed from the pressure equilibrium chamber 82, if the concentration falls below a predetermined value, even if the engine 1 is stopped and the intake bypass valve 42 is cooled, the condensed water is removed from the residual EGR gas. It does not occur and there is no problem.

  Further, in this embodiment, when the engine 1 is decelerated, the negative pressure in the intake passage 3 can be guided to the escape chamber 88 of the ABV 42 through the residual gas removal passage 91 and the like, so that the ABV 42 is changed from the closed state to the open state. Responsiveness can be improved.

  In this embodiment, the check valve 92 allows a gas flow from the pressure balance chamber 82 to the residual gas removal passage 91, and the gas from the residual gas removal passage 91 to the pressure balance chamber 82 when the engine 1 is supercharged. Is prevented by the check valve 92. For this reason, the pressure balance chamber 82 can be protected from the backflow of gas when the engine 1 is supercharged.

<Fourth embodiment>
Next, a fourth embodiment embodying a low-pressure loop EGR device for an engine according to the present invention will be described in detail with reference to the drawings.

  FIG. 7 shows a schematic configuration diagram of a gasoline engine system with a supercharger including a low-pressure loop EGR device in this embodiment. This gasoline engine system is different from the gasoline engine system of FIG. 5 in that the residual gas removal passage 91 is provided with a throttle 93 and a VSV 94 as an on-off valve. The VSV 94 is a solenoid valve and is controlled to be opened and closed by the ECU 50. In this embodiment, the ECU 50 corresponds to an example of the on-off valve control means of the present invention. FIG. 8 is a sectional view showing the configuration of the ABV 42 of this embodiment. The ABV 42 in FIG. 8 differs in that the check valves 44 and 92 in the ABV 42 in FIGS. 2 and 6 are not provided.

  FIG. 9 is a flowchart showing an example of the control contents of the VSV 94. In step 300, ECU 50 determines whether or not EGR is off (EGR cut). If the determination result is affirmative, the ECU 50 proceeds to step 310. If the determination result is negative, the ECU 50 proceeds to step 350.

  In step 350, the ECU 50 resets the VSV on flag XVSVON to “0”. Thereafter, in step 360, the ECU 50 controls the VSV 94 to be turned off, and then returns the process to step 300.

  On the other hand, in step 310, the ECU 50 determines whether or not the VSV on flag XVSVON is “0”. If the determination result is negative, the ECU 50 proceeds to step 360. If the determination result is affirmative, the ECU 50 proceeds to step 320.

  In step 320, the ECU 50 turns on the VSV 94. Thereafter, the ECU 50 waits for a predetermined time to elapse in step 330, sets a VSV on flag XVSVON to “1” in step 340, and then returns the process to step 300.

  According to the control described above, the ECU 50 opens the valve by turning on the VSV 94 only when the EGR cut (EGR off) condition is satisfied. Therefore, in this embodiment, in addition to the effects of the third embodiment, the EGR cut condition for closing the EGR valve 18 is to remove the residual EGR gas from the pressure equilibrium chamber 82 of the ABV 42 and scavenge the chamber 82. It can be limited to. For this reason, the amount of residual EGR gas flowing to the surge tank 3a can be suppressed. This is because the EGR gas contains exhaust particulates, and therefore suppresses the flow into the surge tank 3a as much as possible.

  In this embodiment, the gas flowing through the residual gas removal passage 91 is limited to a small amount by the restriction 93. For this reason, it is possible to prevent the intake air including the EGR gas from being excessively discharged from the pressure equilibrium chamber 82 of the ABV 42 to the intake passage 3 that is the discharge destination.

  In this embodiment, the VSV 94 is controlled to open by the ECU 50 when the EGR valve 18 is closed, so that the gas flow from the pressure equilibrium chamber 82 toward the residual gas removal passage 91 is allowed. On the other hand, the VSV 94 is controlled to be closed by the ECU 50 when the EGR valve 18 is opened, thereby preventing the backflow of gas from the residual gas removal passage 91 to the pressure equilibrium chamber 82. For this reason, the pressure balance chamber 82 can be protected from the backflow of gas when the engine 1 is supercharged.

<Fifth Embodiment>
Next, a fifth embodiment of the low-pressure loop EGR device for an engine according to the present invention will be described in detail with reference to the drawings.

  FIG. 10 is a schematic configuration diagram illustrating a gasoline engine system with a supercharger including a low-pressure loop EGR device in this embodiment. This gasoline engine system is different from the gasoline engine system of FIG. 7 in that only the throttle 93 is provided in the residual gas removal passage 91 and the VSV 94 is omitted.

  In the third embodiment, when the engine 1 is decelerating and idling, the amount of gas flowing from the ABV 42 to the intake passage 3 via the residual gas removal passage 91 and the like is mainly the clearance of the sliding portion inside the ABV 42. Affected by the size of If the clearance of the sliding portion becomes large due to variation due to tolerance of each product of the ABV 42 or aged wear, there is a possibility that problems such as deterioration of the deceleration of the engine 1 and increase in idle rotation may occur. According to this embodiment, since the restriction 93 is provided in the residual gas removal passage 91, it is possible to prevent excessive gas from flowing into the surge tank 3a through the residual gas removal passage 91. In addition, in this embodiment, the same effect as the third embodiment can be obtained.

<Sixth Embodiment>
Next, a sixth embodiment of the low-pressure loop EGR device for an engine according to the present invention will be described in detail with reference to the drawings.

  FIG. 11 is a schematic configuration diagram illustrating a gasoline engine system with a supercharger including a low-pressure loop EGR device according to this embodiment. This gasoline engine system is different from the gasoline engine system of FIG. 1 in that a residual gas removal passage 95 is provided in place of the residual gas removal passage 43, and a pressure pump 96 is provided in the residual gas removal passage 95. is there. That is, the other end 95 b of the residual gas removal passage 95 is connected to the pipe joint 90 provided in the ABV 42. One end 95 a of the residual gas removal passage 95 is connected to the discharge port of the pressurizing pump 96. The pressurizing pump 96 is an electric pump, and is driven and controlled by the ECU 50. In this embodiment, the ECU 50 corresponds to an example of a pressurizing pump control unit for controlling the pressurizing pump 96. In this embodiment, the residual gas removal passage 95, the pressure pump 96, and the ECU 50 correspond to an example constituting the residual gas removal means of the present invention.

  FIG. 12 is a flowchart showing an example of the control content of the pressurizing pump 96. In step 400, the ECU 50 determines whether or not EGR is off (EGR cut). If the determination result is affirmative, the ECU 50 proceeds to step 410. If the determination result is negative, the ECU 50 proceeds to step 450.

  In step 450, the ECU 50 resets the pump-on flag XPUMPON to “0”. Thereafter, in step 460, the ECU 50 controls the pressurization pump 96 to turn off, and then returns the process to step 400.

  On the other hand, in step 410, the ECU 50 determines whether or not the pump-on flag XPUMPON is “0”. If the determination result is negative, the ECU 50 proceeds to step 460. If the determination result is affirmative, the ECU 50 proceeds to step 420.

  In step 420, the ECU 50 controls the pressurization pump 96 to be on. Thereafter, the ECU 50 waits for a predetermined time to elapse in step 430, sets the pump-on flag XPUMPON to “1” in step 440, and then returns the process to step 400.

  According to the above control, the ECU 50 is driven by turning on the pressurization pump 96 only when the EGR valve 18 is closed, that is, when the EGR cut (EGR off) condition is satisfied, and the ECU 50 moves to the residual gas removal passage 95. Compressed air is supplied. Therefore, according to this embodiment, it is possible to prevent the condensed water from being generated by the residual EGR gas in the pressure equilibrium chamber 82 where the EGR gas flows or flows. Further, since compressed air can be directly supplied to the pressure equilibrium chamber 82 of the ABV 42 through the residual gas removal passage 95 or the like, the EGR gas remaining in the pressure equilibrium chamber 82 is pressurized so that the horizontal holes 74b of the movable core 74, And the hollow portion 74c, the internal space 79a of the cylindrical member 79, and the vent hole 84b of the shielding plate 84, and can be reliably removed from the pressure equilibrium chamber 82 by being pushed out to the inflow passage 63 and the like. It is possible to surely scavenge. For this reason, by operating the pressurizing pump 96 at an arbitrary timing, the EGR gas remaining in the pressure equilibrium chamber 82 can be removed at an arbitrary timing.

<Seventh embodiment>
Next, a seventh embodiment of the low-pressure loop EGR device for an engine according to the present invention will be described in detail with reference to the drawings.

  In this embodiment, the gasoline engine system shown in FIG. 11 is different from the sixth embodiment in that a negative pressure pump 97 is provided in the residual gas removal passage 95 instead of the pressurizing pump 96. Further, the control content of the negative pressure pump 97 conforms to the flowchart of FIG. In this embodiment, the ECU 50 corresponds to an example of a negative pressure pump control unit for controlling the negative pressure pump 97. In this embodiment, the residual gas removal passage 95, the negative pressure pump 97, and the ECU 50 correspond to an example constituting the residual gas removal means of the present invention.

  According to this embodiment, the ECU 50 is driven by turning on the negative pressure pump 97 only when the EGR valve 18 is closed, that is, in an EGR cut (EGR off) condition, and the residual gas removal passage 95 is driven. It is designed to supply negative pressure. Therefore, according to this embodiment, it is possible to prevent the condensed water from being generated by the residual EGR gas in the pressure equilibrium chamber 82 where the EGR gas flows or flows. Further, a negative pressure acts on the pressure equilibrium chamber 82 through the residual gas removal passage 95 and the like, and the EGR gas remaining in the pressure equilibrium chamber 82 is sucked by this negative pressure and the residual gas removal passage 95 and the like are discharged from the pressure equilibrium chamber 82. Thus, the pressure equilibrium chamber 82 can be surely scavenged. For this reason, the EGR gas remaining in the pressure equilibrium chamber 82 can be removed at an arbitrary timing by operating the negative pressure pump 97 at an arbitrary timing.

<Eighth Embodiment>
Next, an eighth embodiment of the engine low-pressure loop EGR device according to the present invention will be described in detail with reference to the drawings.

  FIG. 13 is a schematic configuration diagram showing a supercharged gasoline engine system including a low-pressure loop EGR device in this embodiment. This gasoline engine system is different from the gasoline engine system of FIG. 1 in that the residual gas removal passage 43 is not provided in the ABV 42. FIG. 14 is a sectional view showing the configuration of the ABV 42 of this embodiment. The ABV 42 is different from the ABV 42 in FIG. 2 in that the communication passage 89, the pipe joint 90, and the check valve 44 are not provided.

  This embodiment is characterized by the control content of the ABV 42. That is, when the ABV 42 shifts from the closed state to the open state, the movable body 85 moves upward, and the air in the escape chamber 88 moves to the pressure equilibrium chamber 82 through the gap on the outer periphery of the movable body 85. As a result, the EGR gas remaining in the pressure equilibrium chamber 82 is discharged from the vent hole 84b of the shielding plate 84 to the intake bypass passage 41.

  Thereafter, when the ABV 42 shifts from the valve opening state to the valve closing state, the movable body 85 moves downward, and new air in the intake bypass passage 41 flows into the pressure equilibrium chamber 82. Further, the air that has flowed into the pressure equilibrium chamber 82 moves to the escape chamber 88 through a gap on the outer periphery of the movable body 85. As a result, new air flows into the escape chamber 88 and the pressure equilibrium chamber 82. As a result, the concentration of EGR gas remaining in the escape chamber 88 and the pressure equilibrium chamber 82 is lowered.

  By repeatedly opening and closing the ABV 42 in this manner, the concentration of EGR gas remaining in the pressure equilibrium chamber 82 can be reduced. Even if the EGR gas cannot be completely eliminated, if the concentration is equal to or lower than the predetermined value, even if the engine 1 is stopped and the ABV 42 is cooled, condensed water is not generated from the EGR gas, and there is no problem.

  If the ABV 42 is repeatedly opened and closed in this manner, the concentration of EGR gas remaining in the pressure equilibrium chamber 82 of the ABV 42 can be reduced. However, if the same number of times of opening and closing is always performed, the life of the ABV 42 may be shortened. . Therefore, in this embodiment, the concentration of EGR gas remaining in the pressure equilibrium chamber 82 of the ABV 42 is estimated. If the concentration is estimated to be high, the number of repetitions of opening and closing the ABV 42 is increased, and the concentration is low. When estimated, the number of repetitions of opening and closing the ABV 42 is reduced.

  FIG. 15 is a flowchart showing an example of the control contents of the ABV 42. In step 500, the ECU 50 determines whether or not EGR is off (EGR cut). If this determination is negative, the ECU 50 returns the process to step 510. If the determination result is affirmative, the ECU 50 proceeds to step 580.

  In step 580, the ECU 50 determines whether or not the operating state of the engine 1 is in a non-supercharging region. If the determination result is negative, the ECU 50 proceeds to step 710. If this determination is affirmative, the ECU 50 proceeds to step 590.

  In step 710, the ECU 50 resets the scavenging completion determination flag XABVOC to “0”. The flag XABVOC is set to “1” when the scavenging of the pressure equilibrium chamber 82 is completed by removing the residual EGR gas from the pressure equilibrium chamber 82 of the ABV 42, and “0” when the scavenging is not completed. To be reset.

  Next, in step 720, the ECU 50 resets the ABV valve opening control flag XABVO to “0”. The flag XABVO is set to “1” when the ABV 42 is opened, and is reset to “0” when the valve is closed.

  Next, in step 730, the ECU 50 resets the ABV scavenging number ABVOC described later to “0”. In step 740, the ECU 50 controls the valve closing of the ABV 42 and then returns the process to step 500.

  On the other hand, in step 590, the ECU 50 determines whether or not the scavenging completion determination flag XABVOC is “0”. If the determination result is negative, the ECU 50 proceeds to step 700. If the determination result is affirmative, the ECU 50 proceeds to step 600.

  In step 700, the ECU 50 resets the supercharging determination flag XPMP to “0”, and then proceeds to step 720. The flag XPMP is set to “1” when supercharging is performed, and is reset to “0” when supercharging is not performed.

  In step 600, the ECU 50 determines whether or not the ABV valve opening control flag XABVO is “0”. If this determination is negative, the ECU 50 proceeds to step 640. If the determination result is affirmative, the ECU 50 proceeds to step 610.

  In step 610, the ECU 50 controls the opening of the ABV 42. Next, in step 620, the ECU 50 waits for a predetermined time As to elapse after the valve opening, and then proceeds to step 630. In step 630, the ECU 50 sets the ABV valve opening control flag XABVO to “1” and returns the process to step 500.

  On the other hand, in step 640, the ECU 50 controls the ABV 42 to be closed. Next, in step 650, the ECU 50 waits for a predetermined time Bs to elapse after the valve is closed, and then proceeds to step 660. In step 660, the ECU 50 calculates the current ABV scavenging count ABVOC (i) by subtracting the predetermined value β from the ABV scavenging count ABVOC (i−1) up to the previous time.

  Next, in step 670, the ECU 50 determines whether or not the ABV scavenging frequency ABVOC is 0 or less. If this determination is affirmative, the ECU 50 proceeds to step 690. If this determination is negative, the ECU 50 proceeds to step 680.

  In step 690, the ECU 50 sets the scavenging completion determination flag XABVOC to “1”, assuming that scavenging has been completed, and returns the process to step 500.

  In step 680, since the ABV 42 is closed, the ECU 50 resets the ABV valve closing control flag XABVO to “0” and returns the process to step 500.

  On the other hand, in step 510, the ECU 50 determines whether or not the operating state of the engine 1 is in a supercharging region, that is, whether or not supercharging is being performed. If the determination result is negative, the ECU 50 proceeds to step 511. If the determination result is affirmative, the ECU 50 proceeds to step 520.

  In step 511, the ECU 50 resets the supercharging determination flag XPMP to “0” because the operating state of the engine 1 is not in the supercharging region, and then returns the process to step 500.

  In step 520, the ECU 50 resets the scavenging completion determination flag XABVOC to “0”.

  Next, in step 530, the ECU 50 determines whether or not the supercharging determination flag XPMP is “0”. If this determination is negative, the ECU 50 returns the process to step 500 as it is. If the determination result is affirmative, the ECU 50 proceeds to step 540.

  In step 540, the ECU 50 calculates the current ABV scavenging number ABVOC (i) by adding a predetermined value α to the ABV scavenging number ABVOC (i-1) up to the previous time.

  Next, at step 550, the ECU 50 determines whether or not the number of ABV scavenging times ABVOC (i) is less than a predetermined value E. If the determination result is negative, the ECU 50 proceeds to step 560. If the determination result is affirmative, the ECU 50 proceeds to step 570.

  In step 560, the ECU 50 subtracts the predetermined value E from the ABV scavenging number ABVOC (i), and then proceeds to step 570.

  In step 570 after the transition from step 550 or step 560, the ECU 50 sets the supercharging determination flag XPMP to “1” because the operating state of the engine 1 is the supercharging region, and returns the processing to step 500.

  According to the above control, the number of times of opening and closing the ABV 42 for scavenging the pressure equilibrium chamber 82 is increased in accordance with the number of process conditions changing from the non-supercharging region to the supercharging region. Therefore, when it is estimated that the concentration of EGR gas remaining in the pressure equilibrium chamber 82 is high, the ABV scavenging frequency ABVOC is increased, so that the concentration of EGR gas remaining in the pressure equilibrium chamber 82 can be efficiently reduced. it can. At the same time, since the ABV 42 is not subjected to useless opening / closing operations, the durability of the ABV 42 can be improved.

  In this embodiment, when the ABV 42 is changed from the closed state to the open state and the movable body 85 is moved upward, it is necessary to move the movable body 85 as slowly as possible. This is because if the moving speed of the movable body 85 is fast, the air in the escape chamber 88 is only compressed, and does not flow from the gap on the outer periphery of the movable body 85 to the pressure equilibrium chamber 82.

  Therefore, it is necessary to reduce the attractive force of the coil 69 so that the electric power applied to the coil 69 is close to the minimum amount of power that the movable body 85 can move. For this purpose, the amount of power may be controlled by voltage control or current control.

<Ninth Embodiment>
Next, a ninth embodiment of the low-pressure loop EGR device for an engine according to the present invention will be described in detail with reference to the drawings.

  This embodiment differs from the eighth embodiment in terms of the control content of the ABV 42. FIG. 16 is a flowchart showing an example of the control contents of the ABV 42 in this embodiment. This flowchart is different from the flowchart of FIG. 15 in that step 800 and step 810 are provided between step 650, step 660, and step 670.

  That is, in the flowchart of FIG. 16, the process proceeds from step 650, and in step 800, it is determined whether or not the engine 1 is being operated. If the determination result is affirmative, the ECU 50 proceeds to step 660. If the determination result is negative, the ECU 50 proceeds to step 810.

  In step 810, the ECU 50 calculates the current ABV scavenging number ABVOC (i) by subtracting a predetermined value γ from the ABV scavenging number ABVOC (i-1) until the previous time. Thereafter, the ECU 50 moves the process to step 670. Here, since the concentration of EGR gas remaining in the pressure equilibrium chamber 82 of the ABV 42 decreases when the ABV 42 is opened and closed when the EGR cut and the engine stop are performed simultaneously, the predetermined value γ is ABV scavenging times ABVOC. Is a value for decreasing the required number of times. Here, the predetermined value β and the predetermined value γ have a relationship of “β> γ”. This is because, when the engine 1 is stopped, there is no flow of fresh air on the inflow path 63 side in the ABV 42, so compared with the opening / closing operation of the ABV 42 when the EGR cut and the engine operation are performed simultaneously. This is because the amount of residual EGR gas that can be removed from the pressure equilibrium chamber 82 of the ABV 42 is small. Therefore, it is necessary to increase the number of ABV scavenging times ABVOC when the engine is stopped.

<Tenth Embodiment>
Next, a tenth embodiment embodying a low-pressure loop EGR device for an engine according to the present invention will be described in detail with reference to the drawings.

  In each of the above-described embodiments, in the low-pressure loop EGR device provided in the engine 1 provided with the supercharger 7, the pressure balance chamber 82 of the ABV 42 provided in the intake bypass passage 41 is used as a specific part, and the pressure balance chamber 82 The residual gas removing means for removing the remaining EGR gas has been described. In contrast, this embodiment relates to a low-pressure loop EGR device provided in a gasoline engine system including a supercharger 7 and a blow-by gas reduction device. In this embodiment, a residual gas removing means for removing EGR gas remaining in the ejector with the inside of the ejector provided in the intake bypass passage 41 as a specific portion will be described.

  FIG. 17 is a schematic configuration diagram showing a supercharged gasoline engine system including a low-pressure loop EGR device and a blow-by gas reduction device in this embodiment. In the engine system shown in FIG. 17, the residual gas removal means includes a residual gas removal passage 91 for flowing EGR gas remaining inside the ejector 37. One end 91 a of the residual gas removal passage 91 is connected to the intake passage 3 downstream from the throttle valve 21, and the other end 91 b of the residual gas removal passage 91 is connected to the intake bypass passage 41 in the vicinity of the ejector 37. The residual gas removal passage 91 is provided with a throttle 93 for limiting the flow rate of gas flowing through the passage 91 to a small amount. In order to remove EGR gas remaining in the ejector 37, negative pressure generated in the intake passage 3 downstream of the throttle valve 21 is applied to the intake bypass passage 41 via the residual gas removal passage 91. ing.

  Therefore, in this embodiment, when the engine 1 is operating and supercharging, the EGR gas flows into the intake bypass passage 41 and the ejector 37 together with the intake air. Thereafter, EGR gas may remain inside the ejector 37. Here, according to this embodiment, negative pressure is generated in the intake passage 3 downstream of the throttle valve 21 during light load operation of the engine 1 in which the supercharger 7 is not operating. When this negative pressure acts on the intake bypass passage 41 via the residual gas removal passage 91, the EGR gas remaining inside the ejector 37 is sucked and removed to the intake passage 3 via the residual gas removal passage 91. . At the same time, as fresh air flows into the ejector 37, the inside of the ejector 37 is scavenged. Therefore, the EGR gas remaining in the ejector 37 provided in the intake bypass passage 41 can be removed as a specific portion. Further, it is possible to prevent the condensed water from being generated by the residual EGR gas inside the ejector 37 through which the EGR gas flows.

  In this embodiment, the amount of EGR gas remaining in the ejector 37 is very small, and the restriction 93 is provided in the residual gas removal passage 91. Therefore, the flow rate of gas flowing through the residual gas removal passage 91 is limited to a small amount. As a result, intake air (fresh air) containing EGR gas can be prevented from being excessively discharged from the ejector 37 to the intake passage 3 as a discharge destination, and fluctuations in the operation of the engine 1 can be suppressed.

<Eleventh embodiment>
Next, an eleventh embodiment that embodies a low-pressure loop EGR device for an engine according to the present invention will be described in detail with reference to the drawings.

  FIG. 18 is a schematic diagram showing a supercharged gasoline engine system including a low-pressure loop EGR device and a blow-by gas reduction device in this embodiment. In the low-pressure loop EGR device, EGR gas may remain in the EGR passage 17 downstream of the closed EGR valve 18 after the engine 1 is stopped. Therefore, in this embodiment, in addition to the configuration of the tenth embodiment, a residual gas removing means for removing EGR gas remaining in the EGR passage 17 with the EGR passage 17 downstream from the EGR valve 18 as a specific portion is further provided. Prepare. In this embodiment, the residual gas removal passage 91 upstream from the throttle 93 is bifurcated, the other end 91b of one branch passage 91A communicates with the intake bypass passage 41, and the other end 91c of the other branch passage 91B. Communicates with the EGR passage 17 downstream of the EGR valve 18. In this embodiment, a check valve 98 is provided in the residual gas removal passage 91 downstream from the throttle 93. The check valve 98 allows a gas flow toward the intake passage 3 and restricts the reverse flow. In these points, this embodiment is different in configuration from the tenth embodiment.

  Therefore, according to this embodiment, in addition to the effect of 10th Embodiment, it has the following effects. That is, the negative pressure generated in the intake passage 3 acts on the EGR passage 17 downstream from the EGR valve 18 via the residual gas removal passage 91 and the branch passage 91B, so that the EGR gas remaining in the EGR passage 17 branches. The air is sucked into the intake passage 3 through the passage 91B and the residual gas removal passage 91 and removed. At the same time, fresh air flows into the EGR passage 17 in that portion, so that the portion of the EGR passage 17 is scavenged. For this reason, EGR gas 17 remaining downstream from the EGR valve 18 can be removed as a specific portion. In addition, it is possible to prevent the condensed water from being generated by the residual EGR gas in the EGR passage 17 (portion downstream from the EGR valve 18) through which the EGR gas flows.

  In this embodiment, since the check valve 98 is provided in the residual gas removal passage 91, the backflow of gas from the intake passage 3 toward the residual gas removal passage 91 is prevented during supercharging when the supercharger 7 operates. The For this reason, when the engine 1 is supercharged, the EGR passage 17 which is a specific portion can be protected from the backflow of gas, and an appropriate function of the EGR passage 17 can be ensured.

<Twelfth embodiment>
Next, a twelfth embodiment embodying the low-pressure loop EGR device for an engine according to the present invention will be described in detail with reference to the drawings.

  FIG. 19 is a schematic configuration diagram showing a supercharged gasoline engine system including a low-pressure loop EGR device and a blow-by gas reduction device in this embodiment. In this embodiment, the residual gas removal passage 91 is bifurcated between the check valve 98 and the throttle 93, the other end 91b of one branch passage 91A communicates with the intake bypass passage 41, and the other side. The other end 91c of the branch passage 91B communicates with the EGR passage 17 downstream from the EGR valve 18. A restriction 99 is provided in the branch passage 91B. This embodiment is different from the eleventh embodiment in these points.

  Therefore, according to this embodiment, in addition to the effect of 11th Embodiment, it has the following effects. That is, in this embodiment, the amount of EGR gas remaining in the EGR passage 17 downstream from the EGR valve 18 is small, and the restriction 99 is provided in the branch passage 91B of the residual gas removal passage 91, so that the gas flowing through the branch passage 91B Is limited to a small amount by the aperture 99. For this reason, it is possible to prevent intake air (fresh air) containing residual EGR gas from being excessively discharged from the EGR passage 17 which is a specific portion to the intake passage 3 which is a discharge destination, and to suppress fluctuations in the operation of the engine 1. be able to.

  In addition, each said embodiment can also be implemented as follows.

  (1) In each of the above embodiments, the EGR gas remaining in the pressure balancing chamber 82 of the ABV 42, the inside of the ejector 37, and the EGR passage 17 downstream from the EGR valve 18 are respectively defined as specific portions. A specific part is not restricted to these, What is necessary is just a part into which EGR gas flows or flows in. For example, the inside of the intercooler 13 provided in the intake passage 3 can also be assumed as the specific portion.

  (2) In the fourth embodiment, the residual gas removal passage 91 is provided with the VSV 94 as an opening / closing valve, and the opening / closing control is performed. However, in the tenth to twelfth embodiments, the VSV is supplied to the residual gas removal passage 91. It may be provided to control opening and closing.

  (3) In the eleventh embodiment and the twelfth embodiment, in the gasoline engine system with a supercharger including the blow-by gas reduction device, the inside of the ejector 37 and the EGR passage 17 downstream from the EGR valve 18 are respectively specified portions. As described above, the EGR gas remaining there is removed. However, the EGR gas remaining there may be removed using only the EGR passage downstream from the EGR valve as a specific portion.

  The present invention can be used, for example, as an exhaust gas recirculation device for a gasoline engine with a supercharger or a diesel engine.

1 Engine 3 Intake Passage 3a Surge Tank 5 Exhaust Passage 7 Supercharger 8 Compressor 9 Turbine 10 Rotating Shaft 14 Electronic Throttle Device (Intake Amount Control Valve)
16 Combustion chamber 17 EGR passage (exhaust gas recirculation passage)
17a outlet 17b inlet 18 EGR valve (exhaust gas recirculation valve)
21 Throttle valve 41 Intake bypass passage 41a Outlet 42 ABV (intake bypass valve)
50 ECU (electronic control unit)
62 Valve member 65 Valve seat 67 Electromagnetic device (drive means)
82 Pressure equilibrium chamber (specific part)
83 Pressure introduction passage 85 Movable body

Claims (3)

A turbocharger provided between an intake passage and an exhaust passage of the engine for boosting intake air in the intake passage;
The supercharger includes a compressor disposed in the intake passage, a turbine disposed in the exhaust passage, and a rotation shaft that connects the compressor and the turbine so as to be integrally rotatable.
An exhaust gas recirculation passage that causes a part of the exhaust gas discharged from the combustion chamber of the engine to flow into the intake passage as exhaust gas recirculation gas and recirculates to the combustion chamber;
The exhaust gas recirculation passage has an inlet connected to the exhaust passage downstream of the turbine and an outlet connected to the intake passage upstream of the compressor;
An exhaust gas recirculation valve for adjusting the flow of exhaust gas recirculation gas in the exhaust gas recirculation passage;
The intake passage is provided with an intake bypass passage that bypasses between a portion upstream from the compressor and a portion downstream from the compressor;
The intake bypass passage is provided with an intake bypass valve for opening and closing the intake bypass passage;
The intake bypass valve includes a valve seat provided on the intake bypass passage, a movable body having a valve member provided so as to be seatable on the valve seat, drive means for driving the movable body, and the drive means And a pressure equilibrium chamber provided and partitioned between the movable body, and a pressure introduction path formed in the movable body and communicating with the intake bypass passage and the pressure equilibrium chamber;
In the low-pressure loop exhaust recirculation device for an engine, comprising at least an electronic control device for controlling the exhaust recirculation valve and the intake bypass valve according to the operating state of the engine,
When the exhaust gas recirculation valve is closed, the electronic control unit repeatedly opens and closes the intake air bypass valve to reduce the concentration of the exhaust gas recirculation gas remaining in the pressure equilibrium chamber of the intake air bypass valve. A low-pressure loop exhaust gas recirculation device for an engine characterized by   The electronic control unit estimates the concentration of the exhaust gas recirculation gas remaining in the pressure equilibrium chamber, and controls the number of repetitions of opening and closing of the intake bypass valve according to the estimated concentration. The low-pressure loop exhaust recirculation device for an engine according to 1.   3. The electronic control unit according to claim 1, wherein the electronic control unit performs control for repeatedly opening and closing the intake bypass valve only when the engine operating state is in a non-supercharging range. 4. Low-pressure loop exhaust recirculation system for engines.

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