JP2007132309A - Exhaust gas cooling device for exhaust gas re-circulation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inhibit increase of pressure loss of EGR gas flow passing through a cooler side communication passage always in use during operation of an engine. <P>SOLUTION: In an EGR cooler module 1 provided with an EGR cooler 2 and a change over valve device 3, the cooler side communication passages (especially cooler inlet side communication massages 42-44) always in use during operation of the engine are constructed by straight flow paths straightly extending toward an inlet part of the EGR cooler 2 from an inlet port 41 of the housing 4. Consequently, EGR gas flowing into an inside of the cooler side communication passage from the inlet port 41 flows roughly in straight along an axial line of a first straight flow path, and smoothly flows into the inlet part of the EGR cooler 2 without perpendicularly curving as it is. Consequently, increase of pressure loss of the EGR gas flow re-circulated to an intake system of the engine via the EGR cooler 2 can be inhibited. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is applied to an exhaust gas recirculation device for recirculating a part of exhaust gas flowing out from an internal combustion engine to an intake system of the internal combustion engine, and is provided with an EGR cooler for cooling the exhaust gas. In particular, an exhaust gas recirculation provided with a two-position switching valve disposed upstream of the EGR cooler in the flow direction of the exhaust gas, and a housing in which the valve of the two-position switching valve is housed so as to be openable and closable. The present invention relates to an apparatus for exhaust gas cooling.

[Conventional technology]
Conventionally, in order to optimize the temperature of exhaust gas according to the operating state of the internal combustion engine, a part of the exhaust gas flowing out from the internal combustion engine (exhaust gas recirculation gas: EGR gas) is recirculated from the exhaust passage to the intake passage. As shown in FIG. 6, an EGR cooler 101 that cools EGR gas using engine cooling water and an upstream side in the flow direction of EGR gas from this EGR cooler 101 are coupled in the middle of the exhaust gas recirculation pipe for There has been proposed an exhaust gas recirculation device in which an EGR cooler module integrated with the switching valve device 102 is arranged (see, for example, Patent Document 1). The exhaust gas recirculation pipe has a branch pipe on the upstream side in the flow direction of EGR gas from the housing 103 of the switching valve device 102, and the flow direction of EGR gas from the housing 103 of the switching valve device 102. A merging pipe is provided on the downstream side.

  The EGR cooler 101 has a U-turn shape from the cooler inlet passage 104 opened on the EGR cooler inlet side of the housing 103 of the switching valve device 102 toward the cooler outlet passage 105 opened on the EGR cooler outlet side of the housing 103. An exhaust gas cooling flow path for flowing EGR gas is formed. In addition, a bypass passage 106 is formed in the housing 103 of the switching valve device 102 in parallel with the cooler inlet passage 104 and the cooler outlet passage 105 to bypass EGR gas passing through the interior from the EGR cooler 101. .

  The housing 103 has a partition wall 107 that partitions the cooler inlet passage 104, the cooler outlet passage 105, and the bypass passage 106. Further, a valve shaft 109 disposed so as to penetrate the partition wall 107 is rotatably supported by the housing 103. The valve shaft 109 is assembled with a first butterfly valve 111 for opening and closing the cooler inlet passage 104 and a second butterfly valve 112 for opening and closing the bypass passage 106. The valve shaft 109 is drivingly connected to the rod 115 of the negative pressure actuated actuator 110 via a link plate 113 and a shaft member 114.

  The first butterfly valve 111 is assembled to the valve shaft 109 so as to have a relative angle of 90 ° with respect to the second butterfly valve 112. Therefore, in the switching valve device 102, when the first butterfly valve 111 is disposed in the cooler fully open position, the second butterfly valve 112 is disposed in the bypass fully closed position, and the first butterfly valve 111 is cooled. When disposed in the fully closed position, the second butterfly valve 112 is configured to be disposed in the bypass fully opened position.

[Conventional technical problems]
However, in the EGR cooler module described in Patent Document 1, the bypass passage 106 used when the EGR gas temperature is relatively low, such as when the engine is started, is connected from the EGR gas inlet 121 of the housing 103 to the housing. It is comprised by the linear flow path extended straight toward the EGR gas exit 122 of 103. The cooler inlet passage 104 that is always used during operation of the internal combustion engine is configured by an L-shaped flow path having a bent portion 124 bent substantially at a right angle.

  As a result, when the valve seat positions of the first and second butterfly valves 111 and 112 are at the cooler fully open position and the bypass fully closed position that are always used during the operation of the internal combustion engine, the cooler from the EGR gas inlet 123 of the housing 103. The EGR gas flow that flows into the inlet portion of the EGR cooler 101 via the inlet passage 104 is severely bent at the bent portion 124 immediately before the inlet portion of the EGR cooler 101. That is, the EGR gas flow that flows linearly in the axial direction of the EGR gas inlet 123 of the housing 103 is bent at a substantially right angle when passing through the cooler inlet passage 104 and flows into the inlet portion of the EGR cooler 101. The pressure loss of the EGR gas flow passing through the passage 104 increases.

Therefore, the pressure loss of the EGR gas flow when the EGR gas is recirculated to the intake passage of the internal combustion engine via the EGR cooler 101 bypasses the EGR cooler 101 and recirculates the EGR gas to the intake passage of the internal combustion engine. This is much larger than the pressure loss of the EGR gas flow during circulation. That is, the pressure loss of the cooler inlet passage 104 that is always used during operation of the internal combustion engine is significantly larger than the bypass passage 106 that is temporarily used only for a limited period.
European Patent No. 0987427 (pages 2-8, FIG. 1)

  An object of the present invention is to provide an exhaust gas cooling device of an exhaust gas recirculation device that can suppress an increase in pressure loss of an exhaust gas flow that passes through a cooler side communication passage that is always used during operation of an internal combustion engine. is there. Also provided is an exhaust gas cooling device for an exhaust gas recirculation device capable of suppressing an increase in pressure loss of an exhaust gas flow passing through a bypass side communication passage that is temporarily used for a limited period during operation of the internal combustion engine. There is to do.

  According to the first aspect of the present invention, the switching valve is disposed upstream of the exhaust gas cooler in the flow direction of the exhaust gas. This switching valve is housed inside a housing coupled to the inlet of the exhaust gas cooler. Inside the housing, a cooler side communication path and a bypass side communication path are formed. The cooler side communication path is configured such that exhaust gas passing through the interior of the cooler side communication path is recirculated to the intake system of the internal combustion engine via the exhaust gas cooler. Further, the bypass side communication path is configured such that the exhaust gas passing through the inside of the bypass side communication path bypasses the exhaust gas cooler and is recirculated to the intake system of the internal combustion engine. Then, the cooler side communication path is configured by a straight flow path that extends straight from the exhaust gas inlet of the housing toward the inlet portion of the exhaust gas cooler, so that the exhaust gas flowing in from the exhaust gas inlet of the housing flows linearly. It flows in a straight line along the axis of the road, and smoothly flows into the inlet portion of the exhaust gas cooler without bending at a substantially right angle. Therefore, an increase in the pressure loss of the exhaust gas flow when the exhaust gas is recirculated to the intake system of the internal combustion engine via the exhaust gas cooler can be suppressed. That is, it is possible to suppress an increase in pressure loss of the exhaust gas flow that passes through the cooler side communication path that is always used during operation of the internal combustion engine.

  According to invention of Claim 2, the cooler side communicating path is comprised by said linear flow path and the L-shaped flow path bent at substantially right angle. Then, by providing a bypass flow path that short-circuits the linear flow path and the L-shaped flow path in the bypass side communication path, the cooler inlet / outlet passage and the bypass flow path are arranged in parallel. Compared with the housing, the size of the housing can be reduced. As a result, the mounting space of the exhaust gas cooling device including the exhaust gas cooler and the housing incorporating the switching valve can be reduced, so that the overall size of the exhaust gas cooling device can be reduced and the mounting property can be improved. .

  According to invention of Claim 3, the linear flow-path pipe part in which said linear flow path was formed in the housing which accommodates a switching valve inside, and said L-shaped flow path inside You may provide the L-shaped flow-path pipe part in which this was formed. According to the fourth aspect of the present invention, the bypass communication path may be arranged in a direction substantially perpendicular to the axial direction of the linear flow path. That is, the axis line of the bypass side communication path may be arranged on a perpendicular line to the axis line of the linear flow path. In addition, you may provide the partition part which divides a linear flow path and an L-shaped flow path in a housing. In this case, the bypass side communication path is formed so as to penetrate the partition wall.

  According to the fifth aspect of the present invention, in the exhaust gas cooling device provided with the exhaust gas cooler, two first and second exhaust gas passages corresponding to the cooler side communication passage and the first of these are provided. A housing in which a bypass channel (a part of the bypass side communication channel) that communicates by short-circuiting the second exhaust gas channel may be provided. An exhaust gas outlet for introducing exhaust gas into at least the first and second exhaust gas flow paths (and bypass flow paths) may be opened at the upstream side of the exhaust gas flow direction of the housing. Further, an exhaust gas outlet for allowing the exhaust gas to flow out from at least the first and second exhaust gas passages (and the bypass passage) to the outside may be opened on the downstream side of the exhaust gas flow direction of the housing. good. Here, the first exhaust gas passage is a cooler inlet passage communicating with the inlet portion of the exhaust gas cooler, and constitutes a straight passage that guides the exhaust gas flowing from the exhaust gas inlet of the housing to the inlet portion of the exhaust gas cooler. To do. The second exhaust gas passage is a cooler outlet passage communicating with the outlet portion of the exhaust gas cooler, and the L-shaped passage (or the exhaust gas passage that guides the exhaust gas flowing in from the outlet portion of the exhaust gas cooler to the exhaust gas outlet of the housing) A straight flow path).

  According to the sixth aspect of the present invention, the valve body (valve) of the switching valve arranged on the upstream side in the exhaust gas flow direction with respect to the exhaust gas cooler is configured so that at least the bypass side communication passage is opened and closed. The linear flow path (first exhaust gas flow path) is accommodated in an openable and closable manner. According to the invention of claim 7, the valve of the switching valve is a valve when the bypass side communication path is fully opened from the bypass fully closed position which is a valve seat position when the bypass side communication path is fully closed. The valve operating angle to the bypass fully open position, which is the seat position, is an acute angle of less than 90 °. The valve operating angle may be an acute angle excluding a right angle (greater than 0 ° and less than 90 °), preferably in the range of 20 to 70 °, more preferably in the range of 30 to 60 °. The preferred range is most desirably in the range of 40-50 °.

  According to the eighth aspect of the present invention, when the bypass side communication passage is fully opened, the normal line of the valve end surface facing the exhaust gas inlet of the housing is set to be perpendicular to the perpendicular line to the axis of the linear flow path of the housing. It is inclined toward the bypass side communication path (by a predetermined inclination angle). That is, when the bypass side communication path is fully opened, the switching valve has a normal inclination of the valve end surface facing the exhaust gas inlet of the housing toward the exhaust gas inlet of the housing (by a predetermined inclination angle). Is held to be. As a result, when the bypass side communication passage is fully opened, the exhaust gas flowing into the linear flow path from the exhaust gas inlet of the housing first flows straight along the axis of the linear flow path, and the angled switching valve Collides with the valve end face, changes flow in a substantially right angle direction, and smoothly flows into the bypass side communication path.

  Therefore, when the bypass side communication passage is fully opened, the normal line of the valve end surface facing the exhaust gas inlet of the housing is arranged on a perpendicular line to the axis of the linear flow path of the housing, so that the exhaust gas of the housing Compared with the case where the exhaust gas flowing into the straight flow path from the inlet bends sharply at right angles just before the bypass side communication path and flows into the bypass side communication path, the exhaust gas flow is improved and bypasses the exhaust gas cooler. Thus, an increase in the pressure loss of the exhaust gas flow when the exhaust gas is recirculated to the intake system of the internal combustion engine can be suppressed. That is, it is possible to suppress an increase in the pressure loss of the exhaust gas flow passing through the bypass side communication passage that is temporarily used only for a limited period during the operation of the internal combustion engine. In addition, you may form the valve | bulb of a switching valve in flat form with a metal material.

  According to the ninth aspect of the present invention, the first flow path hole which is seated on the first valve seat of the housing and forms at least a part of the bypass side communication path is closed inside the linear flow path of the housing. And a bypass fully closed position (cooler fully open position) that opens at least a second flow path hole that forms part of the cooler side communication path, and a seat on the second valve seat of the housing to open the first flow path hole. And the valve body (valve) of the 2 position switching valve which switches the bypass fully open position (cooler fully closed position) which closes the 2nd channel hole in 2 positions is stored so that opening and closing is possible. Thereby, for example, the first and second flow path holes can be selectively opened and closed by one valve.

  According to the invention of claim 10, the valve of the two-position switching valve has an acute angle with a valve operating angle from the bypass fully closed position (cooler fully open position) to the bypass fully open position (cooler fully closed position) of less than 90 °. It has become. The valve operating angle may be an acute angle excluding a right angle (greater than 0 ° and less than 90 °), preferably in the range of 20 to 70 °, more preferably in the range of 30 to 60 °. The preferred range is most desirably in the range of 40-50 °. According to the eleventh aspect of the present invention, there may be provided a valve drive device that drives the valve of the two-position switching valve to the two positions of the bypass fully closed position and the bypass fully open position.

  The best mode for carrying out the present invention is to suppress the increase in the pressure loss of the exhaust gas flow passing through the cooler side communication passage that is always used during operation of the internal combustion engine. This was realized by a straight flow path extending straight from the exhaust gas inlet toward the inlet of the exhaust gas cooler. Another object of the present invention is to suppress an increase in pressure loss of the exhaust gas flow passing through the bypass side communication passage that is temporarily used only for a limited period during the operation of the internal combustion engine. This was realized by inclining the normal line of the valve end surface facing the gas inlet toward the bypass side communication path (by a predetermined inclination angle) rather than the perpendicular perpendicular to the axis of the linear flow path of the housing.

[Configuration of Example 1]
FIGS. 1 to 5 show Embodiment 1 of the present invention, FIG. 1 is a diagram showing the overall structure of an EGR cooler module, and FIG. 2 is a diagram showing the overall configuration of an exhaust gas recirculation device. FIG. 3 is a diagram showing the overall structure of the switching valve device.

  As shown in FIG. 2, the EGR cooler module 1 of the present embodiment is an exhaust gas cooling device that cools exhaust gas by using an EGR cooler 2 as an exhaust gas cooler, for example, an internal combustion engine such as a diesel engine ( The engine is incorporated in an exhaust gas recirculation device that guides and recirculates part of the exhaust gas flowing out from the combustion chamber of E) to the intake system. This exhaust gas recirculation device is connected to an exhaust pipe (hereinafter referred to as engine exhaust pipe) 14 of engine E, and a part of exhaust gas flowing out from the combustion chamber of engine E (exhaust recirculation gas: hereinafter referred to as EGR gas) The exhaust gas recirculation pipes 16 and 17 for recirculation in the intake pipe (hereinafter referred to as the engine intake pipe) 15 of the engine E, and the exhaust gas formed in these exhaust gas recirculation pipes 16 and 17 An exhaust gas recirculation amount control valve (hereinafter referred to as an EGR control valve) 19 that continuously or stepwise adjusts the recirculation amount (EGR amount) of the EGR gas passing through the recirculation path is provided.

  Here, an exhaust passage through which exhaust gas flowing out from the combustion chamber of the engine E flows is formed inside the engine exhaust pipe 14. An intake passage is formed inside the engine intake pipe 15 through which intake air filtered by the air cleaner 20 and drawn into the combustion chamber of the engine E flows. Further, the EGR cooler module 1 is directly coupled in series between the exhaust gas recirculation pipes 16 and 17. The exhaust gas recirculation pipe 16 is connected to the exhaust manifold of the engine exhaust pipe 14. Further, the exhaust gas recirculation pipe 17 is connected to an intake manifold or a surge tank of the engine intake pipe 15. Further, the engine E is provided with an engine cooling water circuit (cooling water circulation path) for circulating and supplying engine cooling water to the EGR cooler module 1.

  The engine cooling water circuit includes a cooling water pipe 22 for circulating and supplying engine cooling water from a water jacket (not shown) of the engine E to a cooling water inlet pipe (hot water pipe) 21 of the EGR cooler module 1, and an EGR cooler module. A cooling water pipe 24 for circulating and supplying (returning) engine cooling water from a cooling water outlet pipe (hot water pipe) 23 to a water jacket of the engine E through a radiator (not shown), and an engine cooling water circuit A water pump (not shown) for generating a circulating flow of engine cooling water. In this embodiment, the engine coolant in the predetermined temperature range (for example, 75 to 80 ° C.) is returned to the water jacket of the engine E by exchanging heat between the engine coolant and the outdoor air (outside air) by the radiator. It is configured.

  The EGR cooler module 1 of the present embodiment includes an EGR cooler 2 that cools the EGR gas by exchanging heat between the high-temperature EGR gas and engine cooling water, and a switching valve device 3 that is coupled to an inlet portion and an outlet portion of the EGR cooler 2. And constitute part of the exhaust gas recirculation pipes 16 and 17 of the exhaust gas recirculation device and part of the cooling water pipes 22 and 24 of the engine cooling water circuit. Here, the switching valve device 3 includes a housing 4 in which two first and second exhaust gas passages and a bypass passage for short-circuiting (shortcut) the first and second exhaust gas passages are formed. A two-position three-way switching valve that is housed in the housing 4 so as to be freely opened and closed and is driven to two positions, a bypass fully closed position and a cooler fully closed position, and a valve body of the two-position three-way switching valve There are provided two first and second valve seats (first and second cylindrical bodies) 11 and 12 on which (valve: flap type valve 5) is seated. The two first and second exhaust gas passages constitute a cooler-side communication path that recirculates EGR gas to the intake system of the engine E via the EGR cooler 2. The bypass flow path constitutes a bypass side communication path that bypasses the EGR cooler 2 and recirculates EGR gas to the intake system of the engine E.

  The EGR cooler 2 cools the EGR gas below a desired exhaust temperature by exchanging heat between the high-temperature EGR gas introduced from the housing 4 of the switching valve device 3 and the low-temperature engine cooling water flowing from the cooling water pipe 22. It is a water-cooled exhaust gas cooler. The EGR cooler 2 accommodates a plurality of heat exchange tubes (not shown) inside, and has a cooling water passage (not shown) through which engine cooling water circulates around these heat exchange tubes. Yes. Here, the engine coolant flowing from the coolant pipe 22 into the hot water pipe 21 connected to the housing 4 of the switching valve device 3 is a coolant passage formed inside the housing 4 (for example, around the valve shaft 6). (Not shown) is led to the outlet of the cooling water passage. Then, the engine cooling water is led to the cooling water pipe 24 from the hot water pipe 23 provided in the housing 4 of the switching valve device 3.

  Each of the plurality of heat exchange tubes is formed into a U-shaped tube so that EGR gas flows in a U-shape from the inlet portion to the outlet portion of the EGR cooler 2, for example. Inside the EGR cooler 2, a partition wall 25 is provided that partitions a first exhaust gas flow path group into which the EGR gas flows from the housing 4 and a second exhaust gas flow path group from which the EGR gas flows into the housing 4. It has been.

  As shown in FIGS. 1 and 2, the housing 4 is coupled to an inlet portion (EGR gas inlet side) and an outlet portion (EGR gas outlet side) of the EGR cooler 2. The housing 4 is integrally formed in a predetermined shape by a metal material (for example, iron-based casting (cast iron), aluminum casting, aluminum die casting, or the like). Further, as shown in FIGS. 3 to 5, the housing 4 uses a fastener such as a screw for a flange portion (not shown) provided at the downstream end of the exhaust gas recirculation pipe 16 in the EGR gas flow direction. The flange portion 26 (not shown) provided at the upstream end in the EGR gas flow direction of the exhaust gas recirculation pipe 17 is fastened and fixed using a fastener such as a screw. An outlet port side flange portion 27 is provided. Further, the housing 4 is provided with an EGR cooler side flange portion 29 that is fastened and fixed to a flange portion (not shown) provided at an inlet portion and an outlet portion of the EGR cooler 2 using a fastener such as a screw. .

  The housing 4 includes a linear flow channel tube portion 31 and an L-shaped flow channel tube portion 32 bent at a substantially right angle (for example, 90 °). The internal space of the linear flow path pipe portion 31 of the housing 4 is for introducing EGR gas from the outside (exhaust gas recirculation pipe 16) into the EGR cooler 2 via the inlet port 41 of the EGR cooler module 1. Is used as the first exhaust gas flow path (first straight flow path). Further, the internal space of the L-shaped flow path pipe portion 32 of the housing 4 allows the EGR gas to flow out from the inside of the EGR cooler 2 to the outside (exhaust gas recirculation pipe 17) via the outlet port 55 of the EGR cooler module 1. The second exhaust gas flow path (L-shaped flow path) is used.

  In addition, a partition wall 33 that hermetically partitions the first exhaust gas flow path and the second exhaust gas flow path is integrated between the straight flow path pipe section 31 and the L-shaped flow path pipe section 32. Is formed. The partition wall 33 is formed with bypass channels 34 and 35 that shortcut the two first and second exhaust gas channels. The partition wall 33 of the housing 4 is provided with a first communication hole (opening) that communicates the linear flow channel tube 31 and the L-shaped flow channel tube 32. Further, the linear flow channel pipe part 31 has a second communication hole (opening) that communicates the upstream side and the downstream side of the straight flow channel pipe part 31. In addition, between the cooler outlet side communication path 52 and the outlet port 55, a junction (cooler outlet side communication path 53) between the second exhaust gas flow path and the bypass flow paths 34 and 35 is provided.

  The partition wall 33 is provided with a cylindrical valve bearing 36 that supports the valve shaft 6 of the two-position / three-way switching valve in the rotational direction via a bearing component (not shown). Inside the bearing part, there is provided a shaft sliding hole in which the outer peripheral surface of the valve shaft 6 of the two-position / three-way switching valve is in sliding contact. The housing 4 is open at one end side in the axial direction of the valve bearing portion 36. A plug 37 for closing the opening of the valve bearing 36 is press-fitted and fixed to the housing 4 in an airtight manner. In addition, a bracket 65 for attaching a negative pressure actuated actuator 9 to be described later is fastened and fixed to the housing 4 using a fastener such as a screw 39. Further, hot water pipes 21 and 23 are press-fitted and fixed in a liquid-tight manner at the inlet and outlet of the cooling water passage of the housing 4.

  The first exhaust gas flow path is opened from the inlet port (first inlet port of the housing 4, exhaust gas inlet) 41 opened at the upstream end of the exhaust gas flow direction of the housing 4 at the inlet portion of the EGR cooler 2. This is a first straight channel extending straight (straight) in a direction perpendicular to the axial direction of the bypass channels 34 and 35 toward the first outlet port 45. The inlet port 41 constitutes an inlet port of the EGR cooler module 1. The first outlet port 45 communicates with the inlet side end portions of the plurality of heat exchange tubes of the EGR cooler 2. Further, a cooler inlet communicating with the inlet portion of the EGR cooler 2 is provided in the first exhaust gas flow path, that is, between the inlet port 41 and the first outlet port 45 provided on the same axis as the inlet port 41. Side communication paths 42 to 44 are provided. Here, the cooler inlet side communication passage 42 includes a valve chamber that accommodates the flap valve 5 of the two-position / three-way switching valve in an openable / closable manner, and a branch portion (bypass passage) connected to the bypass passage 34 in a T-shaped cross section. 34 and a branch portion between the cooler inlet side communication passage 42).

  The second exhaust gas passage is connected to an outlet port (second outlet port of the housing 4) that opens from the second inlet port 51 that opens at the outlet of the EGR cooler 2 to the downstream end in the exhaust gas flow direction of the housing 4. , An L-shaped flow path bent substantially at a right angle toward the exhaust gas outlet) 55. The second inlet port 51 communicates with the outlet side end portions of the plurality of heat exchange tubes of the EGR cooler 2. Further, the outlet port 55 constitutes an outlet port of the EGR cooler module 1. Further, in the second exhaust gas flow path, that is, between the second inlet port 51 and the outlet port 55 having a relative angle of 90 ° with respect to the second inlet port 51, the outlet portion of the EGR cooler 2 is provided. Cooler outlet side communication passages 52 and 53 that communicate with each other are provided.

  Here, the cooler outlet side communication passage 53 flows in from the bypass passage 35 and a joining portion (a joining portion of the bypass passage 35 and the cooler outlet side communication passage 53) connected to the bypass passage 35 in a T-shaped cross section. And a bypass outlet passage through which the high-temperature EGR gas flows. The two bypass flow paths 34 and 35 are not via the EGR cooler 2, but are joined to the first exhaust gas flow path (cooler inlet side communication path 42) and the second exhaust gas flow path (cooler outlet). This is a bypass flow path that directly communicates with the side communication passage 53) and bypasses the EGR gas passing through the inside from the EGR cooler 2. These bypass flow paths 34 and 35 are arranged in a direction substantially perpendicular to the axial direction of the first exhaust gas flow path (first straight flow path).

  That is, in this embodiment, the axes of the bypass channels 34 and 35 are arranged on a perpendicular line to the axis of the first exhaust gas channel (first linear channel). Further, the two bypass flow paths 34 and 35 including the cooler outlet side communication path 53 are directed from the branch portion (cooler inlet side communication path 42) to the first exhaust gas flow path toward the outlet port 55 of the housing 4. This is a second straight channel extending straight (straight) in the axial direction of the bypass channels 34 and 35. Here, in the present embodiment, the cooler inlet side communication passages 42 to 44 and the first outlet port 45 constitute a cooler inlet side communication passage. Further, the second inlet port 51 and the cooler outlet side communication paths 52 and 53 constitute a cooler outlet side communication path. Further, the cooler inlet side communication path 42, the two bypass flow paths 34 and 35, and the cooler outlet side communication path 53 constitute a bypass side communication path.

  Here, the internal space (cooler outlet) of the L-shaped channel tube portion 32 of the housing 4 is provided in the inner space (particularly the cooler outlet side communication channel 52) of the L-shaped channel tube portion 32 of the housing 4 of the present embodiment. Throttle section having an opening cross-sectional area that can satisfy the required flow rate of the side communication passages 52, 53), that is, a passage cross-sectional area (channel cross-sectional area) smaller than the opening cross-sectional area of the cooler outlet side communication passage 52 on the second inlet port side. 56 is provided. The throttle portion 56 is configured by a protrusion 57 or the like formed integrally with the partition wall portion 33. The projection 57 partially projects the wall surface of the partition wall 33 toward the side of the cooler outlet side communication passage 52 where the cross-sectional area of the cooler outlet side communication passage 52 is reduced (an area sufficient to ensure the required flow rate). The structure has a structure in which soot (deposit) contained in the exhaust gas does not easily enter.

  Here, the housing 4 of the present embodiment includes a first valve seat 11 in which a first flow path hole (corresponding to the bypass flow path 34) is formed, and a second flow path hole (cooler inlet side connection). A second valve seat 12 having a passage 43). The two first and second valve seats 11 and 12 are arranged with a predetermined gap therebetween (with the cooler inlet side communication passage 42 therebetween), and the axial direction of the first valve seat 11 is the second direction. It arrange | positions so that it may become perpendicular | vertical with respect to the axial direction of the valve seat 12. FIG.

  The first valve seat 11 is composed of a first cylindrical body (first cylindrical body) integrally formed in a cylindrical shape by a metal material having excellent heat resistance and corrosion resistance (for example, stainless steel such as SUS303). After the first valve seat 11 is manufactured separately from the housing 4, the first valve seat 11 is formed between the linear flow path pipe portion 31 and the L-shaped flow path pipe portion 32 of the housing 4 (the cooler inlet side communication path 42 and the cooler 4. It is press-fitted into the hole wall surface of the first communication hole provided between the outlet side communication passage 53 and the first communication hole. The first valve seat 11 is an annular first valve on the annular end surface of the cooler inlet side communication passage in the axial direction, on which the back portion of the valve body (flap type valve 5) of the two-position three-way switching valve is seated. A seat 61 is provided.

  The first valve seat portion 61 is used as a restricting portion that restricts the rotational operation range of the flap valve 5, and is disposed on a perpendicular line to the axis of the first valve seat 11. Thereby, when the back surface part of the flap type valve 5 is seated on the first valve seat part 61 of the first valve seat 11, one side in the further rotational direction of the flap type valve 5 (bypass channels 34 and 35 are closed). Side) is restricted. Here, the first valve seat portion 61 of the first valve seat 11 has a seat contact area with the back surface portion of the flap type valve 5 so as to reduce the contact surface of the flap type valve 5 and the contact surface of the first valve seat 11. An annular convex portion may be provided for improving the seal surface pressure.

  The second valve seat 12 is made of a second cylindrical body (second cylindrical body) integrally formed in a cylindrical shape with a metal material (for example, stainless steel such as SUS303) having excellent heat resistance and corrosion resistance. After the second valve seat 12 is manufactured separately from the housing 4, the second valve seat 12 is press-fitted into the hole wall surface of the second communication hole provided in the linear flow path pipe portion 31 of the housing 4. An annular second valve seat 62 on which the abdominal surface of the flap valve 5 is seated is provided on the annular end surface of the second valve seat 12 on the inlet port side in the axial direction.

  The second valve seat portion 62 is used as a restricting portion that restricts the rotational operation range of the flap type valve 5, and has a predetermined inclination toward the inlet port side from a perpendicular perpendicular to the axis of the second valve seat 12. It arrange | positions so that only an angle (for example, about 40-50 degrees) may incline. Thereby, when the abdominal surface portion of the flap type valve 5 is seated on the second valve seat portion 62 of the second valve seat 12, the other side of the flap type valve 5 in the further rotational direction (the cooler inlet side communication passage 43 is closed). Side) is restricted.

  The two-position three-way switching valve of the switching valve device 3 is housed in the housing 4 (cooler inlet side communication passage 42) so as to be freely openable and closable (rotatable), and is connected to the cooler inlet side communication passages 43 and 44 and the bypass flow passage 34. , 35 that selectively open and close, a cylindrical valve shaft 6 that is rotatably supported (supported) by a valve bearing portion 36 of the housing 4, a flap valve 5 and a valve shaft 6 and a flat valve lever 7 that connects the two.

  The flap type valve 5 is integrally formed in a disc shape (circular flat plate shape) with a metal material having excellent heat resistance and corrosion resistance (for example, stainless steel such as SUS304). One end surface of the flap type valve 5 in the plate thickness direction is provided with a back surface portion that is seated on and detached from the first valve seat 11 of the housing 4 to close and open the bypass flow paths 34 and 35. Further, the other end surface in the plate thickness direction of the flap type valve 5 is provided with an abdominal surface portion that is seated and detached from the second valve seat 12 of the housing 4 to close and open the cooler inlet side communication passages 43 and 44. ing.

  Here, the two-position / three-way selector valve of the present embodiment has a bypass fully closed position (cooler fully open position, default position: see FIGS. 1 and 4) and a cooler fully closed position (bypass fully open position, full lift position: see FIG. 5). ) And the second position. The bypass fully closed position means that when the bypass is fully closed (when the cooler is fully opened), the back portion of the flap valve 5 is seated (closely attached) to the first valve seat 11 to open the cooler inlet side communication passages 43 and 44 ( This is the valve seat position of the two-position / three-way switching valve that fully opens) and closes (fully closes) the bypass flow paths 34, 35. The cooler fully closed position means that when the bypass is fully opened (when the cooler is fully closed), the abdominal surface of the flap type valve 5 is seated (closely attached) to the second valve seat 12 so that the cooler inlet side communication passages 43 and 44 are opened. This is the valve seat position of the two-position three-way switching valve that closes (fully closes) and opens (fully opens) the bypass flow paths 34 and 35.

  Therefore, the flap type valve 5 which is the valve body of the 2-position 3-way switching valve is held (arranged) in the bypass fully closed position when the bypass is fully closed, and is held (arranged) in the cooler fully closed position when the cooler is fully closed. The Further, the 2-position 3-way switching valve has an acute angle with a valve operating angle (valve allowable rotation angle) from the bypass fully closed position of the flap type valve 5 to the cooler fully closed position of the flap type valve 5 being less than 90 °. Yes. The valve operating angle may be an acute angle excluding a right angle (greater than 0 ° and less than 90 °), preferably in the range of 20 to 70 °, more preferably in the range of 30 to 60 °. The preferred range is most desirably in the range of 40-50 °. The valve operating angle of the flap type valve 5 shown in FIG. 1 is about 49 °.

  When the flap type valve 5 is fully closed, the normal line of the valve end surface (the abdominal surface portion of the flap type valve 5) is the same as that of the first exhaust gas flow path (cooler inlet side communication paths 42 to 44) of the housing 4. The first valve seat portion 61 of the first valve seat 11 that defines the bypass fully closed position (cooler fully open position) of the flap valve 5 so as to be arranged in a direction parallel to the axis (the left-right direction in FIG. 1). Sitting on.

  In addition, when the bypass valve is fully opened, the flap type valve 5 has a normal line of a valve end face (the back part of the flap type valve 5) opposed to the inlet port 41 of the housing 4 so that the first exhaust gas flow path (cooler) of the housing 4 is aligned. The cooler fully closed position (bypass) of the flap type valve 5 so as to be inclined by a predetermined inclination angle (for example, about 40 to 50 °) to the inlet port side with respect to the vertical line perpendicular to the axis of the inlet side communication passages 42 to 44). It is seated on the second valve seat 62 of the second valve seat 12 that defines the fully open position). That is, when the bypass valve is fully opened, the flap valve 5 has a normal line of the valve end face (the back surface portion of the flap valve 5) opposed to the inlet port 41 of the housing 4 in a predetermined direction toward the inlet port 41 of the housing 4. It is held so as to be in a forward inclined posture by an inclination angle (for example, about 40 to 50 °).

  The valve shaft 6 is supported by a valve bearing portion 36 provided in the partition wall portion 33 of the housing 4 so as to be slidable in the rotational direction via a bearing component, and is a metal material having excellent heat resistance and corrosion resistance (for example, Stainless steel such as SUS304). The valve shaft 6 has a valve holding portion that holds and fixes a fixed end of a valve lever 7 that connects the flap type valve 5 and the valve shaft 6. Further, in this embodiment, a gas such as a seal rubber is used to prevent the soot (deposit) contained in the exhaust gas from entering the clearance portion between the bearing component configured in the valve bearing portion 36 and the valve shaft 6. A seal (not shown) is mounted between the inner periphery of the valve bearing portion 36 of the housing 4 and the outer periphery of the valve shaft 6.

  The valve lever 7 is integrally formed in a predetermined shape (for example, a V shape) with a metal material (for example, stainless steel such as SUS304) having excellent heat resistance and corrosion resistance. The valve lever 7 has a fixed end that is fixed to the outer periphery of the valve shaft 6 at one end, and a free end that fixes the back surface portion (lower end surface in the drawing) of the flap type valve 5 at the other end side. . The fixed end of the valve lever 7 is formed in an arc shape (or a cylindrical shape) corresponding to the cylindrical shape of the valve holding portion of the valve shaft 6, and a part of the outer peripheral surface of the valve holding portion of the valve shaft 6 in the circumferential direction. For example, it is held and fixed using fixing means such as welding. The free end of the valve lever 7 is formed in a fitting groove shape of the flap type valve 5, and the central part of the back surface part of the flap type valve 5 is held and fixed using a fixing means such as welding.

  As described above, the flap type valve 5 integrally connected to the valve shaft 6 via the valve lever 7 is cooled on the free end side of the valve lever 7 by the rotation operation starting from the fixed end side of the valve lever 7. One valve body (a valve body of a two-position three-way switching valve) that selectively opens and closes the inlet side communication passages 43 and 44 and the bypass flow paths 34 and 35 is configured. Here, the valve driving device for driving the two-position three-way switching valve (the flap type valve 5, the valve shaft 6, the valve lever 7, etc.) to the two positions of the bypass fully closed position and the cooler fully closed position is shown in FIG. As shown in FIG. 3, it has a negative pressure actuated actuator 9 that generates a driving force when a negative pressure lower than the atmospheric pressure is introduced. The flap type valve 5 of the position three-way switching valve is configured to be driven to two positions of a bypass fully closed position and a cooler fully closed position.

  The negative pressure actuated actuator 9 includes a thin-film diaphragm (not shown), a rod 63 interlocking with the diaphragm, a link plate 64 that forms a link mechanism together with the valve shaft 6 and the rod 63, and a shelf shape of a bracket 65. And a plurality of casings 66 and 67 assembled to the seat portion. The diaphragm hermetically partitions the internal space of the plurality of casings 66 and 67 into a negative pressure chamber (not shown) into which negative pressure is introduced and an atmospheric pressure chamber (not shown) opened to the atmosphere. It is a rubber-based elastic body.

  The rod 63 is an axis that linearly moves integrally with the diaphragm in response to the displacement of the diaphragm. The upper end portion in the axial direction of the rod 63 is coupled to a diaphragm sandwiched between the plurality of casings 66 and 67, and the lower end portion (tip portion) in the axial direction of the rod 63 is coupled to the link plate 64. Yes. The link plate 64 constitutes a motion direction conversion mechanism that converts the linear motion of the rod 63 of the negative pressure actuated actuator 9 into the rotational motion of the valve shaft 6. Note that the distal end portion of the rod 63 of the negative pressure actuated actuator 9 is engaged with the fitting hole on the input side of the link plate 64. Further, one end portion of the valve shaft 6 in the axial direction protruding outside from the plug 37 is fixed to the fitting hole on the output side of the link plate 64.

  A spring force (biasing force) is generated in the interior space (especially the negative pressure chamber) of the plurality of casings 66 and 67 to urge the diaphragm downward in the figure (bypass fully closed position of the flap type valve 5). A valve biasing means (not shown) such as a coil spring is accommodated. The casing 66 is connected to a negative pressure introduction pipe 69 for introducing negative pressure from the electric vacuum pump into the negative pressure chamber via an electromagnetic or electric negative pressure control valve (not shown).

  Then, the negative pressure actuated actuator 9 introduces a negative pressure into the negative pressure chamber from the electric vacuum pump via a negative pressure control valve, and uses the pressure difference between the negative pressure chamber and the atmospheric pressure chamber to convert the diaphragm into the negative pressure chamber. By displacing in the plate thickness direction, the rod 63 interlocked with the diaphragm is displaced in the axial direction. When the displacement of the rod 63 in the axial direction is transmitted to the valve shaft 6 via the link plate 64, the valve shaft 6 rotates by a predetermined rotation angle. Accordingly, the two-position three-way switching valve is driven to two positions, that is, a bypass fully closed position of the flap type valve 5 and a cooler fully closed position of the flap type valve 5. That is, the valve seat position of the flap type valve 5 is changed.

  Here, the negative pressure control valve and the electric vacuum pump that supply negative pressure, which is the power source of the negative pressure actuator 9, to the negative pressure chamber are controlled to be energized by an engine control unit (hereinafter referred to as ECU) 10. It is configured. The negative pressure control valve switches the amount of negative pressure supplied to the inside of the negative pressure chamber.

  Here, the ECU 10 is configured to include functions of a CPU that performs control processing and arithmetic processing, a storage device (memory such as ROM and RAM) that stores various programs and data, an input circuit, an output circuit, and the like. A microcomputer having a structure is provided. The ECU 10 is configured to electronically control the valve opening degree of the flap valve 5 based on a control program and a map 70 stored in the memory when an ignition switch (not shown) is turned on (IG / ON). Yes. The ECU 10 is configured to forcibly terminate the above-described control based on the control program stored in the memory when the ignition switch is turned off (IG / OFF).

  The sensor signals from the various sensors are A / D converted by an A / D converter and then input to a microcomputer built in the ECU 10. The microcomputer includes a crank angle sensor, an accelerator opening sensor, a coolant temperature sensor, an airflow sensor that indirectly detects the amount of EGR flowing through the exhaust gas recirculation pipes 16 and 17, and a combustion chamber of the engine E. An intake air temperature sensor (intake air temperature detection means) 71 for detecting the temperature of intake air to be taken in (intake air temperature), an exhaust gas temperature sensor (exhaust temperature detection means) 72 for detecting an exhaust gas temperature, and the like are connected. ing.

[Operation of Example 1]
Next, the operation of the exhaust gas recirculation device of the present embodiment will be briefly described with reference to FIGS.

  For example, when the engine E such as a diesel engine is started and the intake valve of the intake port formed in the cylinder head of the engine E is opened, the intake air filtered by the air cleaner 20 is changed into the engine intake pipe 15, the throttle body, It is distributed to the intake manifold of each cylinder through the surge tank, and is sucked into the combustion chamber of each cylinder of the engine E. In the engine E, air is compressed until it reaches a temperature higher than the temperature at which the fuel burns, and high pressure fuel is sprayed from the injector there, and combustion is performed.

  Then, the combustion gas burned in the combustion chamber of each cylinder of the engine E is discharged from an exhaust port formed in the cylinder head of the engine E, and is discharged through the exhaust manifold and the engine exhaust pipe 14. Here, when the negative pressure control valve and the electric vacuum pump are not energized, the diaphragm is displaced by the urging force of the coil spring provided in the casings 66 and 67 of the negative pressure actuator 9. Therefore, the rod 63 of the negative pressure actuated actuator 9 is positioned below the figure (see FIG. 3). In this case, as shown in FIG. 4, the back surface portion of the flap type valve 5 is maintained at the valve seat position where it is seated on the first valve seat portion 61 of the first valve seat 11. That is, the valve seat position of the flap type valve 5 is maintained at the bypass fully closed position where the bypass flow paths 34 and 35 are closed (fully closed).

  Therefore, the high-temperature EGR gas (for example, the exhaust temperature of 450 to 600 ° C.) flowing into the cooler inlet side communication passages 42 to 44 of the housing 4 via the inlet port 41 from the exhaust gas recirculation pipe 16 is shown in FIGS. As shown in FIG. 5, the first exhaust gas flow path of the housing 4 flows straight in the axial direction of the linear flow path pipe portion 31 and flows into the EGR cooler 2 from the first outlet port 45 of the housing 4. The high-temperature EGR gas that has flowed into the plurality of heat exchange tubes of the EGR cooler 2 exchanges heat with engine cooling water (for example, a cooling water temperature of about 80 to 90 ° C.) when passing through the plurality of heat exchange tubes. It is cooled and becomes low-temperature EGR gas (for example, exhaust temperature of about 100 ° C.). Then, the low temperature EGR gas flows again into the inside of the housing 4 (cooler outlet side communication path 52) from the second inlet port 51, and after the flow direction is bent by 90 ° in the cooler outlet side communication path 53, the outlet port 55 And flows out of the housing 4. The low-temperature EGR gas that has flowed out of the housing 4 is recirculated (refluxed) to the engine intake pipe 15 via the exhaust gas recirculation pipe 17.

  On the other hand, the valve seat position of the flap type valve 5 of the switching valve device 3 is set to the cooler fully closed position where the valve seat position of the second valve seat 12 is seated and the cooler inlet side communication passage 43 is closed. When the negative pressure control valve and the electric vacuum pump are energized, negative pressure is introduced into the negative pressure chamber formed inside the casings 66 and 67 of the negative pressure actuator 9. When the diaphragm is displaced according to the pressure difference between the negative pressure chamber and the atmospheric pressure chamber, the rod 63 moves upward in the drawing. The link plate 64 rotates about the axis of the valve shaft 6 as the rod 63 moves linearly upward in the figure, and the valve shaft 6 fixed to the link plate 64 moves as the link plate 64 rotates. Rotate around the center axis of rotation.

  As a result, the flap type valve 5 rotates around the axis of the valve shaft 6, so that it is separated from the first valve seat portion 61 of the first valve seat 11 and the second valve seat portion of the second valve seat 12. Sitting on 62. Therefore, the valve seat position of the flap-type valve 5 is the cooler fully closed position disposed opposite to the inlet port 41. In the present embodiment, the flap type valve 5 is held at a rotation angle of, for example, about 40 to 50 °, the cooler inlet side communication passage 43 is closed (fully closed), and the bypass passage 34 is opened (fully opened).

  Accordingly, the high-temperature EGR gas that has flowed from the exhaust gas recirculation pipe 16 through the inlet port 41 into the cooler inlet side communication passage 42 of the housing 4, as shown in FIG. 1 and FIG. Flows straight in the axial direction of the straight flow pipe portion 31 and collides with the back surface portion of the flap type valve 5 seated on the second valve seat portion 62 of the second valve seat 12. At this time, the back surface portion of the flap type valve 5 is inclined at a predetermined inclination angle (for example, about 40 to 50 °) with respect to the axial direction of the linear flow path pipe portion 31. The flow direction of the high-temperature EGR gas that collided with is changed to the axial direction of the bypass flow paths 34 and 35. The high temperature EGR gas that has passed through the bypass passages 34 and 35 flows straight in the axial direction of the bypass passages 34 and 35, flows into the cooler outlet side communication passage 53 of the housing 4, and passes through the outlet port 55 to the housing 4. Leaks out of the water. The high-temperature EGR gas that has flowed out of the housing 4 is recirculated (refluxed) to the engine intake pipe 15 via the exhaust gas recirculation pipe 17.

  Here, when the engine E is in the normal operating range (for example, when a predetermined time or more has passed since the engine E was started), the valve seat position of the flap valve 5 is changed to the rear surface of the flap valve 5. The EGR cooler module 1 is connected to the EGR cooler module 1 from the exhaust gas recirculation pipe 16 by setting the bypass seat 34 to the first valve seat 61 of the first valve seat 11 and closing the bypass passages 34 and 35 (completely closed). When the total flow rate of the EGR gas introduced into the interior passes through the EGR cooler 2 and is recirculated (refluxed) to the engine intake pipe 15 as shown in FIGS. Is sufficiently cooled inside the EGR cooler 2. As a result, the low temperature EGR gas having a low temperature and a low density is mixed with the intake air in the intake passage of the engine intake pipe 15, so that the output of the engine E is not reduced and each cylinder of the engine E is reduced. The generation of pollutants (emissions such as NOx) in the exhaust gas discharged from the engine E due to a decrease in the combustion temperature of the fuel in the combustion chamber can be effectively reduced.

  In addition, immediately after the engine E is started, the valve seat position of the flap type valve 5 is set to the value of the flap type valve 5 when the EGR gas temperature (exhaust gas temperature) is below a predetermined value or when the outside air temperature is cold, for example, 5 ° C. or below. An abdominal surface is seated on the second valve seat 62 of the second valve seat 12 and is set to a cooler fully closed position where the cooler inlet side communication passages 43 and 44 are closed (fully closed). When the total flow rate of the EGR gas introduced into the module 1 is recirculated (refluxed) to the engine intake pipe 15 through the bypass passages 34 and 35 as shown in FIGS. The EGR gas is recirculated while the temperature is relatively high. As a result, a sufficient warming effect on the intake air can be obtained, the combustibility in the engine E can be improved, and the generation of hydrocarbons (hydrocarbon: HC) and white smoke can be prevented.

  In addition, when the temperature of the intake air is lowered by cooling the EGR gas, the NOx emission amount tends to decrease. However, under relatively low engine speed and low load operating conditions, the EGR gas is reduced. Cooling increases HC emissions. For this reason, by controlling the flap type valve 5 to an appropriate valve opening (rotation angle) according to the operating state of the engine E, the temperature of the EGR gas is changed to an optimum temperature, and NOx is discharged. The amount and the discharge amount of HC can be reduced at the same time.

[Effect of Example 1]
As described above, in the EGR cooler module 1 incorporated in the exhaust gas recirculation device of the present embodiment, the inside is connected to the inlet and outlet portions of the U-turn flow type EGR cooler 2 in which the EGR gas flows in a U shape. Two first and second exhaust gas passages for recirculating EGR gas in the intake passage of the engine E through the EGR cooler 2 are formed in the housing 4 to be formed. Here, the first exhaust gas flow path is a first straight flow path (cooler inlet side communication paths 42 to 44 and a first outlet port) that extends straight from the inlet port 41 of the housing 4 toward the inlet portion of the EGR cooler 2. 45). In addition, the second exhaust gas flow path is an L-shaped flow path (second inlet port 51 and cooler outlet side link) that is bent at a substantially right angle from the outlet portion of the EGR cooler 2 toward the outlet port 55 of the housing 4. It is constituted by passages 52 and 53).

  As a result, a bent portion that is bent at a substantially right angle from the first exhaust gas flow path that is always used during operation of the engine E is eliminated, and the first exhaust gas flow path is connected to the EGR cooler 2 from the inlet port 41 of the housing 4. By configuring the first linear flow path extending straight toward the inlet portion, the EGR gas flowing into the cooler inlet side communication path 42 from the inlet port 41 flows along the axis of the first linear flow path. It flows substantially linearly and flows smoothly into the inlet portion of the EGR cooler 2 via the cooler inlet side communication passages 42 to 44 and the first outlet port 45 without bending at right angles. Therefore, an increase in the pressure loss of the EGR gas flow when the EGR gas is recirculated through the intake passage of the engine E via the EGR cooler 2 can be suppressed.

  That is, an increase in the pressure loss of the EGR gas flow that passes through the first exhaust gas passages (cooler inlet side communication passages 42 to 44 and the first outlet port 45) that are always used during operation of the engine E can be suppressed. Therefore, the amount of EGR (filling efficiency) flowing into the combustion chamber of each cylinder of the engine E can be increased. For this reason, since the combustion temperature of the fuel in the combustion chamber of each cylinder of the engine E can be effectively lowered, the deterioration of pollutants (emissions such as NOx) in the exhaust gas discharged from the engine E (generation of NOx and the like) Increase in amount) can be effectively suppressed.

  Further, in the EGR cooler module 1 of the present embodiment, two first and second exhaust gas flow paths are shortcut in the housing 4 connected to the inlet and outlet of the U-turn flow type EGR cooler 2. By doing so, the bypass passages 34 and 35 for recirculating the EGR gas in the intake passage of the engine E by bypassing the EGR cooler 2 are formed. Here, the bypass flow paths 34 and 35 are arranged in a direction substantially perpendicular to the axial direction of the first exhaust gas flow path (first straight flow path). Accordingly, the switching valve device is compared with the housing 103 (see FIG. 6) of the switching valve device 102 described in Patent Document 1 in which the cooler inlet passage 104, the cooler outlet passage 105, and the bypass passage 106 are arranged in parallel. The size of the housing 4 can be dramatically reduced. Accordingly, the space for mounting the EGR cooler module 1 including the EGR cooler 2 and the switching valve device 3 can be reduced, so that the size of the EGR cooler module 1 can be reduced and the mountability in the engine room of a vehicle such as an automobile can be improved. Can be achieved.

  Further, in the EGR cooler module 1 of the present embodiment, the flap type valve 5 of the two-position three-way switching valve is such that the normal line on the back surface of the flap type valve 5 is the first linear flow of the housing 4 when the bypass is fully opened. Fully close the cooler of the flap valve 5 so that it is inclined by a predetermined inclination angle (for example, about 40 to 50 °) to the inlet port side from the perpendicular line to the axis of the passage (cooler inlet side communication passages 42 to 44) It is seated on the second valve seat 12 that defines the position (bypass fully open position). That is, when the bypass valve is fully opened, the flap type valve 5 has the normal line of the back surface portion of the flap type valve 5 inclined forward by a predetermined inclination angle (for example, about 40 to 50 °) toward the inlet port 41 of the housing 4. Is held to be.

  Thus, the housing 4 including the bypass passages 34 and 35 that are temporarily used only for a limited period during operation of the engine E (for example, a period in which the EGR gas temperature (exhaust gas temperature immediately after engine startup) is equal to or less than a predetermined value). By eliminating the bent portion where the EGR gas flow is intensely bent substantially at right angles from the internal space of the air conditioner (cooler inlet side communication passage 42, bypass flow passages 34 and 35, cooler outlet side communication passage 53 and outlet port 55), The EGR gas that has flowed into the cooler inlet side communication passage 42 from the port 41 flows substantially linearly along the axis of the first linear flow path, and the valve end surface of the angled two-position three-way switching valve It collides with (the back surface portion of the flap type valve 5), changes the flow in a substantially right angle direction, and smoothly flows into the bypass channels 34 and 35.

  Further, the two bypass flow paths 34 and 35 including the cooler outlet side communication path 53 are straightened from the branch portion (cooler inlet side communication path 42) with the first exhaust gas flow path toward the outlet port 55 of the housing 4. By comprising the extended second linear flow path, the EGR gas that has flowed into the cooler outlet side communication path 53 from the bypass flow paths 34 and 35 is substantially linear along the axis of the second linear flow path. It flows smoothly and flows out from the outlet port 55 without bending at a right angle. Therefore, the exhaust gas flowing into the first linear flow path from the inlet port 41 is bent at a right angle immediately before the bypass flow paths 34 and 35 and flows into the bypass flow paths 34 and 35, compared with the case where the EGR gas flows. The flowability can be improved, and an increase in the pressure loss of the EGR gas flow when the EGR cooler 2 is bypassed and the EGR gas is recirculated in the intake passage of the engine E can be suppressed.

  That is, since it is possible to suppress an increase in the pressure loss of the exhaust gas flow passing through the bypass passages 34 and 35 that are temporarily used only for a limited period during the operation of the engine E, the combustion chamber of each cylinder of the engine E can be suppressed. Thus, the warming effect on the intake air sucked into the engine increases, and the combustion state in the combustion chamber of each cylinder of the internal combustion engine can be improved. For this reason, it is possible to effectively suppress deterioration of pollutants (emissions of HC, etc.) in the exhaust gas discharged from the engine E (increase in the amount of generation of HC, etc.).

[Modification]
In this embodiment, a valve driving device that opens (or closes) the flap type valve 5 of the two-position / three-way switching valve of the switching valve device 3 is connected to a negative pressure from an electric vacuum pump via a negative pressure control valve. The valve driving device configured to open or close the valve body (valve) of the two-position / three-way switching valve of the switching valve device is constituted by an electric motor and power. You may comprise by the electric actuator comprised including a transmission mechanism (for example, gear reduction mechanism etc.), and an electromagnetic actuator. Further, a valve urging means such as a coil spring for urging the flap type valve 5 of the two-position three-way switching valve of the switching valve device 3 in the valve closing direction (the side where the bypass passages 34 and 35 are closed) is provided. 3 may be installed inside the housing 4.

  In the present embodiment, the example in which the flap type valve 5 rotating around the axis of the valve shaft 6 is applied as the valve body of the two-position / three-way switching valve has been described. As another example, other valves such as a plate type valve and a rotary type valve may be used. Further, the switching valve device controls the valve operating angle between the bypass fully closed position and the cooler fully closed position continuously or stepwise so that the flow rate of exhaust gas passing through the EGR cooler 2 (low temperature EGR gas amount). For adjusting the EGR gas temperature (exhaust gas temperature) recirculated to the intake system of the engine E by adjusting the mixing ratio between the exhaust gas flow rate (high temperature EGR gas amount) passing through the bypass passages 34 and 35 It may be used as a gas temperature control valve. The switching valve may be a passage opening / closing valve that only opens and closes the bypass flow path 34. Further, the valve end face of the two-position / three-way switching valve (the back face portion of the flap type valve 5) may be curved into a spherical shape (or an arc shape) so that the flow direction of EGR gas gently changes when the bypass is fully opened. .

  In this embodiment, the switching valve device 3 of the exhaust gas recirculation device according to the present invention has an exhaust gas provided with a U-turn flow type EGR cooler (exhaust gas cooler) 2 through which EGR gas (exhaust gas) flows in a U shape. Although applied to the gas cooling device (EGR cooler module 1), the switching valve device 3 of the exhaust gas recirculation device of the present invention is of the type in which EGR gas (exhaust gas) flows in an S shape or I shape inside. You may apply to the exhaust-gas cooling device (EGR cooler module) provided with the gas cooler. In this case, the outlet tank portion of the exhaust gas cooler and the second inlet port 51 of the housing 4 are connected by an exhaust gas pipe having no heat exchange function.

  In the present embodiment, the first valve seat portion 61 on which the back portion of the valve body (flap type valve 5) of the two-position three-way switching valve is seated is a cylindrical first member that is press-fitted into the partition wall portion 33 of the housing 4. 1 provided on the annular end surface of the valve seat 11, but the first valve seat portion on which the valve body (valve) of the two-position / three-way switching valve is seated is the opening of the first communication hole provided in the partition wall portion 33 of the housing 4. You may provide directly in a peripheral edge. In this case, the first valve seat portion is formed integrally with the housing 4. A second valve seat portion 62 on which the abdominal surface portion of the valve body (flap type valve 5) of the two-position three-way switching valve is seated is a cylindrical shape that is press-fitted into the linear flow path pipe portion 31 of the housing 4. Although the second valve seat 12 is provided on the annular end surface, the second valve seat portion on which the valve body (valve) of the two-position / three-way switching valve is seated is provided in the linear flow channel pipe portion 31 of the housing 4. You may provide directly in the opening peripheral edge of 2 communicating holes. In this case, the second valve seat portion is formed integrally with the housing 4.

  In the present embodiment, by arranging the axes of the bypass channels 34 and 35 on a perpendicular line to the axis of the first exhaust gas channel (first linear channel), the first linear channel ( Although the inlet port 41 and the cooler inlet side communication passages 42 to 44) and the second linear flow passage (bypass flow passages 34 and 35, the cooler outlet side communication passage 53 and the outlet port 55) are connected in a T shape. The crossing angle between the axis of the bypass channels 34 and 35 and the perpendicular perpendicular to the axis of the first exhaust gas channel (first linear channel) is an acute angle, and the first linear channel and the second The straight channel may be connected in a substantially square shape. Further, the bypass channel is connected to the first exhaust gas channel (first linear channel) (the cooler inlet side communication channel 42) and the second exhaust gas channel (the cooler outlet side communication channel). 53), it may be a bent flow path that curves smoothly in an arc shape.

  In the present embodiment, the second exhaust gas flow path is an L-shaped flow path that is bent at a substantially right angle in the middle, and the L-shaped flow path and the bypass flow paths 34 and 35 are connected in a T-shape. The second exhaust gas passage extends straight (straight) from the outlet portion of the EGR cooler 2 toward the exhaust gas outlet (outlet port) of the housing 4 in a direction perpendicular to the axis of the bypass passages 34 and 35. A straight flow path may be used, and the straight flow path and the bypass flow paths 34 and 35 may be connected in a T shape. In this case, the internal space (first and second exhaust gas flow paths and bypass flow path) of the housing 4 is an H-shaped flow path. Further, the linear flow path and the bypass flow paths 34 and 35 may be connected in a Y shape. Further, the second exhaust gas flow path may be a curved flow path that smoothly curves in an arc shape from the outlet portion of the EGR cooler 2 toward the exhaust gas outlet (outlet port) of the housing 4. In these cases, the pressure of the EGR gas flow that passes through the second exhaust gas flow path (second inlet port 51, cooler outlet side communication passages 52, 53 and outlet port 55) that is always used during operation of the engine E. The increase in loss can be suppressed as compared with the first embodiment.

It is sectional drawing which showed the whole structure of the EGR cooler module (Example 1). 1 is a configuration diagram showing the overall configuration of an exhaust gas recirculation device (Example 1). FIG. It is the perspective view which showed the whole structure of the switching valve apparatus (Example 1). (Example 1) which is the explanatory view which showed the bypass fully closed position of the 2 position 3 direction switching valve. (Example 1) which is the explanatory view which showed the cooler fully closed position of a 2 position 3 direction switching valve. It is sectional drawing which showed the whole structure of the EGR cooler module (conventional technique).

Explanation of symbols

E engine (internal combustion engine)
1 EGR cooler module (exhaust gas cooling device)
2 EGR cooler (exhaust gas cooler)
3 Switching valve device 4 Housing 5 Flap type valve (Valve body of 2 position 3 direction switching valve)
9 Negative pressure actuator (valve drive)
DESCRIPTION OF SYMBOLS 11 1st valve seat 12 2nd valve seat 31 Linear flow-path pipe part 32 L-shaped flow-path pipe part 33 Partition part of housing 34 Bypass flow path (1st flow-path hole, bypass side communication path) of 1st valve seat )
35 Bypass passage of housing (Bypass side communication passage)
41 Inlet port (exhaust gas inlet)
42 Cooler inlet side communication path of housing (cooler side communication path, bypass side communication path, linear flow path)
43 Cooler inlet side communication path of second valve seat (cooler side communication path, linear flow path, second flow path hole)
44 Cooler inlet side communication path of housing (cooler side communication path, linear flow path)
52 Cooler outlet side communication path of housing (cooler side communication path, L-shaped flow path)
53 Cooler outlet side communication path of housing (cooler side communication path, bypass side communication path, L-shaped flow path)
55 Outlet port (exhaust gas outlet)

Claims (11)

(A) an exhaust gas cooler for cooling the exhaust gas flowing out from the internal combustion engine and recirculated to the intake system of the internal combustion engine;
(B) an exhaust valve provided with a switching valve disposed upstream of the exhaust gas cooler in the flow direction of the exhaust gas, and (c) a housing coupled to the inlet of the exhaust gas cooler and incorporating the switching valve. In the exhaust gas cooling device of the gas recirculation device,
Inside the housing, a cooler-side communication path for recirculating exhaust gas to the intake system of the internal combustion engine via the exhaust gas cooler, and exhaust gas to the intake system of the internal combustion engine by bypassing the exhaust gas cooler A bypass-side communication path for recirculation is formed,
The housing has an exhaust gas inlet for introducing exhaust gas into at least the cooler side communication path,
The exhaust gas cooling device for an exhaust gas recirculation device, wherein the cooler side communication passage has a straight flow path extending straight from the exhaust gas inlet toward the inlet of the exhaust gas cooler. The exhaust gas cooling device of the exhaust gas recirculation device according to claim 1,
The cooler-side communication path has an L-shaped channel that is connected to the linear channel through the exhaust gas cooler and is bent at a substantially right angle,
In the exhaust gas recirculation apparatus, the bypass side communication path includes a bypass flow path that short-circuits the linear flow path and the L-shaped flow path in the housing. Exhaust gas cooling device. The exhaust gas cooling device of the exhaust gas recirculation device according to claim 2,
The housing has a linear flow channel tube portion in which the linear flow channel is formed, and an L-shaped flow channel tube portion in which the L-shaped flow channel is formed. Exhaust gas cooling device for exhaust gas recirculation device. The exhaust gas cooling device of the exhaust gas recirculation device according to claim 2 or 3,
The exhaust-gas cooling device for an exhaust-gas recirculation device, wherein the bypass-side communication passage is disposed in a direction substantially perpendicular to the axial direction of the linear flow path. The exhaust gas cooling device of the exhaust gas recirculation device according to any one of claims 2 to 4,
The housing has an exhaust gas outlet for causing exhaust gas to flow out from at least the cooler side communication path toward the outside,
The linear flow path constitutes a linear first exhaust gas flow path that communicates with the inlet portion of the exhaust gas cooler and guides the exhaust gas flowing from the exhaust gas inlet to the inlet portion of the exhaust gas cooler,
The L-shaped flow path constitutes a substantially L-shaped second exhaust gas flow path that communicates with the outlet portion of the exhaust gas cooler and guides the exhaust gas flowing in from the outlet portion of the exhaust gas cooler to the exhaust gas outlet. And
The exhaust gas cooling device of the exhaust gas recirculation device, wherein the bypass flow channel connects the first exhaust gas flow channel and the second exhaust gas flow channel in a short circuit inside the housing. In the exhaust gas cooling device of the exhaust gas recirculation device according to any one of claims 1 to 5,
The switching valve is housed in the linear flow path so as to be openable and closable, and has a valve that opens and closes at least the bypass side communication path. . The exhaust gas cooling device of the exhaust gas recirculation device according to claim 6,
The valve has a valve operating angle from a bypass fully closed position that is a valve seat position when the bypass side communication path is fully closed to a bypass fully open position that is a valve seat position when the bypass side communication path is fully opened. An exhaust gas cooling device for an exhaust gas recirculation device, characterized by an acute angle. The exhaust gas cooling device of the exhaust gas recirculation device according to claim 6 or 7,
In the valve, when the bypass side communication path is fully opened, the normal line of the valve end surface facing the exhaust gas inlet is inclined toward the bypass side communication path side with respect to a perpendicular perpendicular to the axis of the linear flow path. An exhaust gas cooling device for an exhaust gas recirculation device. In the exhaust gas cooling device of the exhaust gas recirculation device according to any one of claims 1 to 8,
The housing has a first valve seat having a first flow passage hole formed therein, and a second valve seat having a second flow passage hole formed therein,
The switching valve is housed in the linear flow path so as to be openable and closable, sits on the first valve seat, closes the first flow path hole, and opens the second flow path hole. A two-position switching valve that switches between a closed position and a bypass fully open position that sits on the second valve seat to open the first flow path hole and closes the second flow path hole;
The two-position switching valve has one valve that selectively opens and closes the first and second flow path holes, and the first flow path hole constitutes at least a part of the bypass side communication path. ,
The exhaust gas cooling device of the exhaust gas recirculation device, wherein the second flow path hole constitutes at least a part of the cooler side communication passage. The exhaust gas cooling device of the exhaust gas recirculation device according to claim 9,
The exhaust gas cooling device of the exhaust gas recirculation device, wherein the valve of the two-position switching valve has an acute valve operating angle from the bypass fully closed position to the bypass fully open position. The exhaust gas cooling device of the exhaust gas recirculation device according to claim 9 or 10, wherein the valve of the two-position switching valve is driven to two positions of the bypass fully closed position and the bypass fully open position. An exhaust gas cooling device for an exhaust gas recirculation device comprising the device.

Images