JP2010203362A - Exhaust gas switching valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust gas switching valve capable of using an inexpensive seal member. <P>SOLUTION: An EGR cooler bypass valve 10 includes: a valve housing 12 formed with an EGR gas passage 13; a valve element 17 provided in the valve housing 12 freely to turn through a valve shaft 15 to switch a flow of the exhaust gas; and a seal member 64 provided in a gap 65 in the radial direction between the valve shaft 15 and the valve housing 12. An overheat restricting means is provided to restrict overheat of the seal member 64. The overheat restricting means is structured of a cooling water passage 50, a passage formed to surround the EGR gas passage 13 in the circumferential direction inside a passage wall 80 of the EGR gas passage 13 of the valve housing 12, wherein the refrigerant flows. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an exhaust gas switching valve.

  Conventionally, an EGR (exhaust gas recirculation) system has been adopted to reduce NOx in exhaust gas in diesel engines and the like. In this EGR system, when high-temperature exhaust gas is circulated as it is to the intake side, exhaust gas in a state of being expanded at high temperature is supplied to the intake passage, so that the ratio of exhaust gas in the cylinder increases. As a result, the amount of air in the cylinder decreases, combustion efficiency deteriorates, and exhaust components such as NOx also deteriorate. For this reason, in the EGR system, an EGR cooler (heat exchanger) that cools exhaust gas (EGR gas) by heat exchange with cooling water is disposed in a part of the EGR passage, and high-temperature EGR gas is supplied by the EGR cooler. An EGR system with an EGR cooler that recirculates to the intake manifold in a cooled state has been developed. In such an EGR cooler system, when the temperature of the cooling water is low such as when the engine is started or cold, the cooling of the EGR gas becomes supercooled, and conversely, the combustion efficiency in the cylinder and the exhaust component are deteriorated. The EGR gas is prevented from flowing into the EGR cooler when the cooling water temperature is lower than normal or when the engine is cold or cold. An exhaust gas switching valve is used for switching between using and not using the EGR cooler. In such an EGR system, an exhaust gas switching valve is mounted on the EGR cooler (see, for example, Patent Document 1).

WO2006 / 084867

In the exhaust gas switching valve in Patent Document 1, when exhaust gas having a high temperature (for example, about 650 ° C.) flows through the exhaust gas passage, the valve housing, the valve shaft, and the valve body become hot. For this reason, the seal member provided in the radial gap between the valve shaft and the valve housing is required to have sufficient heat resistance to withstand high temperatures. However, such a seal member that can withstand high temperatures is expensive and impractical.
The problem to be solved by the present invention is to provide an exhaust gas switching valve capable of using an inexpensive seal member.

The above-mentioned problem can be solved by an exhaust gas switching valve having the gist of the configuration described in the claims.
In other words, according to the exhaust gas switching valve described in claim 1 of the claims, the exhaust gas switching valve is provided with the overheat suppressing means for suppressing the overheating of the seal member. Therefore, it is possible to use an inexpensive seal member by suppressing overheating of the seal member by the overheat suppressing means. This is effective as an exhaust gas switching valve through which exhaust gas of high temperature (for example, about 650 ° C.) flows in the exhaust gas passage of the valve housing.

  According to the exhaust gas switching valve described in claim 2 of the claims, the overheat suppression means is formed in the passage wall of the exhaust gas passage of the valve housing so as to surround the exhaust gas passage in the circumferential direction. The passage is constituted by a refrigerant passage through which the refrigerant flows. Therefore, the valve housing can be cooled by efficiently exchanging heat between the refrigerant flowing through the refrigerant passage and the valve housing. This makes it possible to use a valve housing made of an aluminum alloy material as a valve housing through which exhaust gas at a high temperature (for example, about 650 ° C.) flows in the exhaust gas passage, thereby realizing a reduction in weight and cost of the valve housing. It is valid.

  According to the exhaust gas switching valve described in claim 3 of the claims, the refrigerant passage is adjacent to the hole wall of the valve housing in which the seal member is provided. Therefore, the hole wall of the valve housing provided with the seal member can be cooled by the refrigerant flowing through the refrigerant passage.

  According to the exhaust gas switching valve described in claim 4 of the claims, the axial direction of the refrigerant passage is formed on the joint surface of the valve housing with respect to the communication part in which the gas communication passage communicating with the exhaust gas passage is formed. One side is open. Therefore, when the communication component is communicated with the valve housing, it is possible to close the opening surface of the refrigerant passage opened at the joint surface of the valve housing with the communication component. For this reason, another component for closing the opening surface of the refrigerant passage can be omitted. When the valve housing is cast, the exhaust gas passage and the refrigerant passage can be formed entirely by removing the die.

  According to the exhaust gas switching valve described in claim 5 of the claims, when the cooler housing provided with the refrigerant passage for flowing the refrigerant in the exhaust gas cooler for cooling the exhaust gas is attached to the valve housing, The refrigerant passage of the cooler housing is configured to communicate with the refrigerant passage of the valve housing. Therefore, it is possible to continuously flow the entire amount of refrigerant through the refrigerant passage of the cooler housing and the refrigerant passage of the valve housing. Accordingly, the cooler housing and the valve housing can be efficiently cooled as compared with the case where the refrigerant is divided and flowed through the refrigerant passage of the cooler housing and the refrigerant passage of the valve housing.

  According to the exhaust gas switching valve described in claim 6 of the claims, the refrigerant is provided in the fastening portion that fastens the communication part provided in the valve housing and formed with the gas communication passage communicating with the exhaust gas passage. The passage is adjacent. Therefore, the fastening portion of the valve housing can be cooled by the refrigerant flowing through the refrigerant passage. This can prevent the screw parts from loosening due to the high temperature of the fastening portion. The screw parts correspond to bolts, nuts, screws, screws, and the like.

  Further, according to the exhaust gas switching valve described in claim 7 of the claims, an actuator mounting portion for mounting an actuator for driving the valve shaft is provided at a portion adjacent to the refrigerant passage in the valve housing. . Therefore, the actuator mounting portion of the valve housing can be cooled by the refrigerant flowing through the refrigerant passage. Thereby, it becomes possible to attach the actuator which hates high temperature to the valve housing. An actuator that dislikes high temperatures corresponds to an electric actuator such as a DC motor. Further, by adopting a DC motor as the electric actuator, it is possible to perform precise opening / closing control of the valve body. In addition, an electromagnetic solenoid can be employed as the electric actuator.

  According to the exhaust gas switching valve described in claim 8, the overheat suppression means includes a hole wall of the valve housing in which the seal member is provided, and a shaft portion inside the seal member in the valve shaft. It is comprised with the heat-transfer member of good heat conductivity interposed by the contact state between. Therefore, the heat transfer from the valve shaft to the seal member can be suppressed by transferring the heat of the valve shaft to the valve housing by the heat transfer member. Further, by blocking the exhaust gas passing between the valve shaft and the hole wall of the valve housing by the heat transfer member, it is possible to prevent the seal member from being exposed to the exhaust gas.

  According to the exhaust gas switching valve described in claim 9, the heat transfer member is fitted in an annular groove formed on the outer peripheral surface of the shaft portion and is arranged on the inner periphery of the hole wall of the valve housing. It is a piston ring-shaped heat transfer ring that is in elastic contact with the surface. Therefore, the piston ring-shaped heat transfer ring is pressed against the groove wall surface outside the annular groove of the valve shaft by the pressure of the exhaust gas, whereby the heat of the valve shaft can be efficiently transferred to the valve housing.

  According to the exhaust gas switching valve recited in claim 10 of the claims, the overheat suppression means is configured by making the valve shaft have a hollow structure. Therefore, heat transfer from the valve plate side to the seal member side of the valve shaft can be suppressed by reducing the substantial cross-sectional area of the valve shaft as compared with the valve shaft made of a solid shaft.

  According to the exhaust gas switching valve recited in claim 11 of the claims, the heat transfer suppression means is configured by roughening the shaft portion outside the seal member in the valve shaft. Therefore, heat transfer from the valve shaft to the seal member can be suppressed by increasing the heat radiation area by roughening the valve shaft.

1 is a front sectional view showing an EGR cooler bypass valve according to Embodiment 1. FIG. It is the II-II sectional view taken on the line of FIG. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 1. It is a top view which shows an EGR cooler bypass valve. It is a bottom view which shows an EGR cooler bypass valve. It is a perspective view which shows a cooler unit. It is a right view which shows a cooler unit. It is a sectional side view which shows a cooler unit. It is a top view which shows a cooler housing. It is a perspective view which shows a valve housing. It is a front view which shows a valve housing. FIG. 12 is a cross-sectional view taken along line XII-XII in FIG. 11. It is XIII-XIII arrow sectional drawing of FIG. It is the XIV-XIV arrow directional cross-sectional view of FIG. It is sectional drawing which shows the mold open state of the shaping | molding die for valve housings. FIG. 6 is a cross-sectional view of a main part showing an EGR cooler bypass valve according to a second embodiment. 6 is a top view showing an EGR cooler bypass valve according to Embodiment 3. FIG. FIG. 6 is a cross-sectional view of a main part showing an EGR cooler bypass valve according to a fourth embodiment. FIG. 9 is a cross-sectional view of a main part showing an EGR cooler bypass valve according to a fifth embodiment.

  EMBODIMENT OF THE INVENTION Below, the form for implementing this invention is demonstrated using drawing.

[Example 1]
A first embodiment of the present invention will be described. In this embodiment, an EGR cooler bypass valve used in an EGR system with an EGR cooler in an engine (for example, a diesel engine) will be described as an exhaust gas switching valve. 1 is a front sectional view showing an EGR cooler bypass valve, FIG. 2 is a sectional view taken along the line II-II in FIG. 1, FIG. 3 is a sectional view taken along the line III-III in FIG. 1, and FIG. The top view which shows a bypass valve, FIG. 5 is a bottom view similarly.
As shown in FIG. 2, the EGR cooler bypass valve 10 includes a valve housing 12 in which an EGR gas passage 13 is formed, a valve shaft 15 that is rotatably supported by the valve housing 12, and an exhaust gas in the EGR gas passage 13. And a plate-like valve body 17 for switching the flow of the. The EGR cooler bypass valve 10 switches the flow of the EGR gas that flows through the EGR gas passage 13 when the valve body 17 is pivoted together with the valve shaft 15 by an actuator 19 (see FIG. 6) described later. Hereinafter, it demonstrates in order. For convenience of explanation, the left and right direction in the state shown in FIG.

  The valve housing 12 will be described. The valve housing 12 is formed in a block shape by die-casting an aluminum alloy material. The valve housing 12 is formed with an inflow passage 21 that opens to the upper surface, and a first passage 22 and a second passage 23 that open to the lower surface. The inflow passage 21 and the first passage 22 are adjacent to each other through the first partition wall 25. The first partition wall 25 is formed with a first communication hole 26 that allows the inflow passage 21 and the first passage 22 to communicate with each other. Further, the inflow passage 21 and the second passage 23 are adjacent to each other through the second partition wall 28. The second partition wall 28 is formed with a second communication hole 29 that allows the inflow passage 21 and the second passage 23 to communicate with each other. Further, the first passage 22 is formed on the rear side (right side in FIG. 2), the second passage 23 is formed on the front side (left side in FIG. 2), and both the passages 22, 23 are the third passage. It is partitioned by a partition wall 31. On the front side wall of the second passage 23, a hole-like outflow passage 33 that communicates the inside and the outside of the second passage 23 is formed. A piping member (not shown) communicating with the intake passage can be connected to the outflow passage 33 by fastening. Moreover, the 1st partition wall 25, the 2nd partition wall 28, and the 3rd partition wall 31 are provided in a row so that a cross-section Y-shape may mutually be made. The EGR gas passage 13 is configured by the inflow passage 21, the first passage 22, the second passage 23, the first communication hole 26, the second communication hole 29, and the outflow passage 33. The EGR gas passage 13 corresponds to an “exhaust gas passage” in the present specification. Further, in a state where the EGR cooler bypass valve 10 is mounted on the vehicle, for example, the rear side (right side in FIG. 2) of the valve housing 12 is arranged on the top side and the front side (left side in FIG. 2) is oriented on the ground side. .

A cooler unit 35 is configured by unitizing an EGR cooler 52 (described later) into the EGR cooler bypass valve 10. 6 is a perspective view showing the cooler unit, FIG. 7 is a right side view, and FIG. 8 is a side sectional view.
Moreover, as shown in FIG. 8, the upper surface of the valve housing 12 of the EGR cooler bypass valve 10 is a joint surface joined to the joint pipe 37 communicated with the upstream side thereof. The joint pipe 37 is formed in a hemispherical shape having an open lower surface, and the inside of the pipe is an expansion chamber 38. The open end surface of the expansion chamber 38 corresponds to the joint surface of the valve housing 12. In addition, the joint pipe 37 is formed with an introduction port 39 that opens the upper end portion of the expansion chamber 38 to the upper surface. Further, a connection flange 43 is formed at the upper end portion of the joint pipe 37 so as to project to the outer periphery. A connection flange 44 is formed at the lower end of the joint pipe 37 so as to project to the outer periphery.

  Fastening bosses 41 projecting to the outer periphery are formed at the four corners of the upper end of the valve housing 12 (see FIG. 4). A connection flange 44 (see FIG. 8) on the lower side, that is, the downstream side of the joint pipe 37 can be fastened to the fastening boss portion 41 of the valve housing 12 by a bolt (not shown). A catalyst device provided in an exhaust system of an engine (not shown) can be fastened to a connection flange 43 (see FIG. 8) on the upstream side of the joint pipe 37 by a bolt (not shown). Therefore, the EGR gas introduced into the inlet 39 of the joint pipe 37 through the catalyst device can smoothly flow into the inflow passage 21 of the valve housing 12 after being expanded in the expansion chamber 38. A gasket (not shown) is interposed between the joint surfaces of the valve housing 12 and the joint pipe 37. The joint pipe 37 corresponds to a “communication part” in this specification. The fastening boss portion 41 corresponds to a “fastening portion” in this specification.

  As shown in FIG. 1, a pair of left and right bearing boss portions 48 are formed on the left and right sides of the valve housing 12. A shaft insertion hole 49 is formed in the bearing boss portion 48 to insert the valve shaft 15 that crosses the lower end portion of the inflow passage 21 in the left-right direction. The shaft insertion hole 49 is a multi-stepped hole whose diameter increases from the inflow passage 21 side toward the outside. Further, the valve housing 12 is provided with a cooling water passage 50 (described later) through which engine cooling water (hereinafter referred to as “cooling water”) flows (see FIG. 2).

  The lower surface of the valve housing 12 is a joint surface joined to an EGR cooler 52 (see FIGS. 6 to 8) for cooling EGR gas (see FIG. 5). As shown in FIG. 6, a mounting flange 53 is formed on the lower end portion of the valve housing 12 so as to project to the outer periphery. At the four corners of the mounting flange 53, mounting flanges 55 of the cooler housing 54 of the EGR cooler 52 can be fastened by bolts 56. A gasket (not shown) is interposed between the joint surfaces of the valve housing 12 and the cooler housing 54. Although not shown, the EGR cooler 52 has an EGR passage through which EGR gas flows and a cooler cooling water passage through which cooling water flows, and cools the EGR gas by heat exchange with the cooling water. is there. FIG. 9 is a top view showing the cooler housing.

  As shown in FIG. 9, on the upper surface of the cooler housing 54 of the EGR cooler 52 (that is, the joint surface of the cooler housing 54 with respect to the valve housing 12), a gas inlet 57, a gas outlet 58, and cooler cooling water of the EGR passage are provided. A cooling water inlet 59 of the passage is opened. The gas inlet 57 communicates with the first passage 22 of the valve housing 12, and the gas outlet 58 communicates with the second passage 23 of the valve housing 12 (see FIG. 8). Further, the cooling water inlet 59 is communicated with the cooling water passage 50 of the valve housing 12 (see FIG. 5). Further, as shown in FIG. 5, the cooling water inlet 59 corresponds to the left end portion of the opening surface of the cooling water passage 50 of the valve housing 12, and the remaining opening surface is blocked by the joint surface of the cooler housing 54. It has a configuration. As shown in FIG. 6, an outlet pipe 60 that forms a cooling water outlet of the cooler cooling water passage is provided at the lower end portion of the cooler housing 54. The outlet pipe 60 is connected to a piping member (not shown) communicating with the downstream passage of the engine coolant circuit. The EGR cooler 52 corresponds to the “exhaust gas cooler” in this specification. The cooler housing 54 corresponds to a “communication part” in the present specification. The four corners of the mounting flange 53 correspond to “fastening portions” in the present specification. Further, the EGR passage corresponds to a “gas communication passage” in this specification.

  Next, the valve shaft 15 will be described. As shown in FIG. 1, the valve shaft 15 is a solid shaft, and enters the shaft insertion hole 49 of the both bearing boss portions 48 in a state where the lower end portion of the inflow passage 21 in the EGR gas passage 13 crosses in the left-right direction. It is inserted. Bush-type bearings 62 are respectively press-fitted in the hole portions near the outer ends of the shaft insertion holes 49 of the bearing boss portions 48. The valve shaft 15 is rotatably supported by both bearings 62. In addition, one end portion (right end portion) of the valve shaft 15 protrudes outward from the bearing boss portion 48. The valve shaft 15 is made of a material harder than the material of the valve housing 12, for example, a metal material such as stainless steel.

  A seal member 64 made of a rubber-like elastic material is provided in a hole portion adjacent to the inside of the bearing 62 in the shaft insertion hole 49 of each bearing boss portion 48. As shown in FIG. 3, the seal member 64 includes an annular ring portion 64 a that is press-fitted into the hole portion of the bearing boss portion 48, a protrusion along the inner peripheral surface of the ring portion 64 a, and an outer peripheral surface on the valve shaft 15. And a lip portion 64b that elastically contacts the lip portion. The seal member 64 is formed of a synthetic resin material such as a tetrafluoroethylene resin. Further, the seal member 64 prevents the exhaust gas from leaking through the radial gap 65 between the valve shaft 15 and the bearing boss portion 48 of the valve housing 12. The inner peripheral wall that forms the shaft insertion hole 49 in the bearing boss portion 48 is referred to as a “hole wall”.

  An annular groove 67 is formed on the outer peripheral surface of the shaft portion inside (valve plate side) of the valve shaft 15 from the seal member 64. A heat transfer ring 68 is fitted in the annular groove 67. The heat transfer ring 68 is formed in a piston ring shape, that is, a C ring shape from a metal material having a good heat transfer property such as copper or an aluminum alloy. The outer peripheral surface of the heat transfer ring 68 is in contact with the inner peripheral surface of the hole wall of the bearing boss portion 48 of the valve housing 12 in an elastic and slidable manner. The groove width 67W of the annular groove 67 is set to be larger than the plate thickness 68t of the heat transfer ring 68. Therefore, the heat transfer ring 68 is provided in the annular groove 67 so as to be movable in the axial direction. The heat transfer ring 68 is moved in the axial direction (mainly on the seal member 64 side) in the annular groove 67 by the pressure of the exhaust gas. Therefore, the inner peripheral portion of the heat transfer ring 68 is pressed against the groove wall surface on the outside (right side in FIG. 3) of the annular groove 67 of the valve shaft 15 by the pressure of the exhaust gas. The inner peripheral portion of the heat transfer ring 68 abuts against the groove wall surface outside the annular groove 67 of the valve shaft 15 so as to be slidable in the circumferential direction. The heat transfer ring 68 corresponds to a “heat transfer member” in this specification.

  Next, the valve body 17 will be described. As shown in FIG. 2, the valve body 17 is also called a swing valve, and is fixed in a cantilever manner by a screw 70 to a shaft portion in the inflow passage 21 in the valve shaft 15. The valve element 17 swings in the inflow passage 21 by rotating the valve shaft 15. When the valve body 17 selectively comes into surface contact with the wall surface on the inflow path 21 side of the first partition wall 25 or the second partition wall 28, the communication holes 26 and 29 of the partition walls 25 and 28 are selected. Open and close. That is, when the first communication hole 26 is closed by the valve body 17 (see the solid line 17 in FIG. 2), the second communication hole 29 is opened, and the valve body 17 (the two-dot chain line in FIG. 2). 17), when the second communication hole 29 is closed, the first communication hole 26 is opened. The valve body 17 is made of a material harder than the material of the valve housing 12, for example, a metal material such as stainless steel.

  Next, an actuator 19 for driving, that is, turning the valve shaft 15 will be described. As shown in FIG. 6, in this embodiment, a diaphragm type actuator is used as the actuator 19. A bracket 72 provided on a housing 71 (referred to as an “actuator housing”) 71 of the actuator 19 is provided on the right side of the stay 73 fixed to the lower side of the right end portion of the mounting flange 55 of the cooler housing 54 of the EGR cooler 52. (See FIG. 7). Although not shown, the actuator 19 has a diaphragm chamber in which a diaphragm is provided in the actuator housing 71, and a negative pressure is applied to the diaphragm chamber through a negative pressure pipe 75.

  As shown in FIG. 7, one end of a lever 77 is pivotally connected by a pin 78 to the tip (upper end) of the output shaft 76 that moves forward and backward in the axial direction in conjunction with the diaphragm of the actuator 19. ing. The other end of the lever 77 is fitted to the protruding end of the valve shaft 15 so as to prevent rotation. Therefore, when a negative pressure is applied to the actuator 19, the output shaft 76 is retracted, and when the negative pressure is purged, the output shaft 76 is advanced. As a result, the valve shaft 15 is driven, that is, rotated, and the first communication hole 26 and the second communication hole 29 of the valve housing 12 are selectively opened and closed.

Next, the cooling water passage 50 of the valve housing 12 will be described. 10 is a perspective view showing the valve housing, FIG. 11 is also a front view, FIG. 12 is a cross-sectional view taken along line XII-XII in FIG. 11, and FIG. 13 is a cross-sectional view taken along line XIII-XIII in FIG. 14 is a cross-sectional view taken along line XIV-XIV in FIG.
As shown in FIG. 12, the cooling water passage 50 is formed in the passage wall 80 of the EGR gas passage 13 of the valve housing 12 so as to surround the EGR gas passage 13 in the circumferential direction (see FIG. 13). In the present embodiment, the cooling water passage 50 is provided in a passage wall 80 that surrounds the right side, the rear side, and the left side of the inflow passage 21 and the first passage 22 that are particularly susceptible to the high temperature of the exhaust gas in the EGR gas passage 13. It is formed in a U-shape in a plan view and is formed in a semi-cylindrical shape extending in the axial direction (vertical direction) (see FIGS. 12 and 13).

  Further, the right end portion in the circumferential direction of the cooling water passage 50 is adjacent to the rear side portion of the hole wall around the seal member 64 and the bearing 62 in the bearing boss portion 48 on the right side of the valve housing 12 (FIGS. 13 and FIG. 13). 14). Further, the left end portion in the circumferential direction of the cooling water passage 50 is adjacent to the rear side portion of the hole wall in the left bearing boss portion 48 of the valve housing 12 (see FIG. 13). In addition, an extension passage portion 50a extending forward is formed in the lower side portion of the left end portion in the circumferential direction of the cooling water passage 50 so as to sink under the bearing boss portion 48 on the left side of the valve housing 12 ( (See FIGS. 13 and 14). The overhang passage portion 50 a is adjacent to the lower side portion of the hole wall around the seal member 64 and the bearing 62 in the bearing boss portion 48 on the left side of the valve housing 12. Further, the front end portion of the overhang passage portion 50 a is adjacent to the left front corner portion of the mounting flange 53 of the valve housing 12.

  One side portion, ie, the lower side portion, of the cooling water passage 50 in the axial direction is opened on the lower surface, that is, the joint surface of the valve housing 12 (see FIGS. 5, 12, and 14). As described above, the lower surface opening of the cooling water passage 50 is closed by the joint surface (see FIG. 9) of the cooler housing 54 and communicated with the cooling water inlet 59 of the cooler housing 54. Yes. The cooling water inlet 59 of the cooler housing 54 corresponds to the central portion in the overhanging passage portion 50 a of the cooling water passage 50.

  As shown in FIG. 14, a connecting hole 82 is formed in the upper end portion of the bearing boss portion 48 on the right side of the valve housing 12 by opening a right end portion in the circumferential direction of the cooling water passage 50 forward. . An inlet pipe 83 that forms a cooling water inlet 59 is connected to the connection hole 82. The connection hole 82 is adjacent to the upper portion of the hole wall around the seal member 64 and the bearing 62 in the bearing boss 48 on the right side of the valve housing 12. The inlet pipe 83 is connected to a piping member (not shown) communicating with the upstream passage of the engine coolant circuit. Further, the left rear portion and the right rear portion at the upper end portion in the axial direction of the cooling water passage 50 are adjacent to the fastening boss portions 41 at the left rear portion and the right rear portion on the upper end side of the valve housing 12. Further, the left rear portion and the right rear portion at the lower end portion in the axial direction of the cooling water passage 50 are adjacent to the left rear corner portion and the right rear corner portion of the mounting flange 53 of the valve housing 12. The cooling water passage 50 corresponds to “refrigerant passage” and “overheat suppression means” in this specification. Further, the cooling water corresponds to a “refrigerant” in the present specification.

Next, a method for forming the valve housing 12 including the EGR gas passage 13 and the cooling water passage 50 will be described. FIG. 15 is a side sectional view showing the open state of the mold for the valve housing.
As shown in FIG. 15, the valve housing 12 is molded by a die casting method in which a molten aluminum alloy material is cast into a molding die 85. The mold 85 includes a first mold 86 as an upper mold that forms a cavity for molding the valve housing 12, a second mold 87 as a lower part, and a plurality of side molds (two on the left and right in FIG. 15). A third mold 88 is shown. The first mold 86 is closed downward in FIG. 15 and forms the upper surface portion of the valve housing 12 mainly including the inflow passage 21. On the mold surface of the first mold 86, hole forming portions 86a and 86b for forming both communication holes 26 and 29 are formed. Further, the second mold 87 is closed upward in FIG. 15 and forms a lower surface portion of the valve housing 12 mainly including both the passages 22 and 23 and the cooling water passage 50. . Further, the plurality of third molds 88 are closed toward the side surface of the valve housing 12 in FIG. 15, and include the outflow passage 33 of the valve housing 12 and the bearing boss portions 48 (see FIG. 13). The side part is formed. Although not shown, any metal mold is provided with a gate that communicates with the cavity.

  The first to third molds 86, 87, 88 are clamped by a mold clamping device (not shown), and molten metal is poured from a gate (not shown) into a cavity formed by the molds. As a result, the valve housing 12 is molded. And after hardening of the valve housing 12, the valve housing 12 is taken out by opening the 1st-3rd metal mold | die 86,87,88 mold closing device (not shown). The EGR cooler bypass valve 10 is completed by assembling the valve shaft 15, the valve body 17, the inlet pipe 83 and the like to the valve housing 12 manufactured as described above.

  The inflow passage 21 including both the communication holes 26 and 29 is set so as to be parallel to the axial direction of the valve housing 12 (vertical direction in FIG. 15), and is formed by punching out the first mold 86. Has been. Further, both the passages 22 and 23 and the cooling water passage 50 are set so as to be parallel to the axial direction (vertical direction in FIG. 15) of the valve housing 12, and are formed by punching out the second mold 87. ing. Thereby, the cooling water passage 50 can be easily formed in the valve housing 12 together with the inflow passage 21 including both the communication holes 26 and 29 and the both passages 22 and 23 by die cutting.

  In the EGR cooler bypass valve 10 described above, the joint pipe 37 is disposed on the upstream side of the valve housing 12, and the fastening boss portion 41 of the valve housing 12 and the connection flange 44 of the joint pipe 37 are fastened by bolts (not shown). The As a result, the expansion chamber 38 of the joint pipe 37 communicates with the inflow path 21 of the valve housing 12 (see FIG. 8). An EGR cooler 52 is disposed on the downstream side of the valve housing 12, and the mounting flange 53 of the valve housing 12 and the mounting flange 55 of the cooler housing 54 are fastened by bolts 56. Thereby, the gas inlet 57 of the EGR passage of the cooler housing 54 communicates with the first passage 22 of the valve housing 12, and the gas outlet 58 of the EGR passage of the cooler housing 54 communicates with the second passage 23 of the valve housing 12. Communication is made (see FIG. 8). Further, the cooling water inlet 59 of the cooling water passage 50 of the cooler housing 54 communicates with the opening surface of the cooling water passage 50 of the valve housing 12, and the remaining opening surface is a joint surface of the cooler housing 54 (see FIG. 9). It is blocked by. Further, as described above, the bracket 72 of the actuator housing 71 of the actuator 19 is fastened to the stay 73 of the mounting flange 55 of the cooler housing 54 of the EGR cooler 52 by the screw 74 (see FIGS. 6 and 7). . Further, the lever 77 is connected to the protruding end of the valve shaft 15 in a non-rotating state, and the lever 77 and the output shaft 76 of the actuator 19 are rotatably connected by a pin 78 (see FIG. 7).

  As described above, the EGR cooler 52 is unitized as the cooler unit 35 and the EGR joint pipe 37 is connected to the EGR cooler bypass valve 10. The cooler unit 35 is installed between a catalyst device (not shown) and an intake passage in the exhaust system of the engine. That is, the joint pipe 37 and the catalyst device (not shown) are connected by fastening, and the outflow passage 33 of the valve housing 12 and a piping member (not shown) communicating with the intake passage are connected by fastening. Further, a piping member (not shown) communicating with the downstream passage of the engine coolant circuit is connected to the outlet pipe 60 (see FIG. 6) of the cooler housing 54 of the EGR cooler 52. An EGR system with an EGR cooler is configured as described above.

  The operation of the EGR cooler bypass valve 10 will be described. First, when the coolant temperature of the engine is equal to or lower than a predetermined temperature (when the engine is cold such as at the time of start-up), the valve element 17 is brought into the first communication by the operation by applying the negative pressure of the actuator 19 (retraction of the output shaft 76). The hole 26 is closed and the second communication hole 29 is opened (see the solid line 17 in FIG. 8). As a result, the inflow passage 21 is blocked from the first communication hole 26 communicating with the first passage 22 and communicated with the second passage 23 via the second communication hole 29. Therefore, the EGR gas that has flowed into the inflow passage 21 through the joint pipe 37 passes through the second communication hole 29, the second passage 23, and the outflow passage 33, and flows out to the intake passage through the piping member.

  Further, when the cooling water temperature of the engine is equal to or higher than a predetermined temperature (after warming up), the valve element 17 opens the first communication hole 26 by the operation by the negative pressure purge of the actuator 19 (advance of the output shaft 76). At the same time, the second communication hole 29 is closed (see the two-dot chain line 17 in FIG. 8). As a result, the inflow passage 21 is blocked from the second communication hole 29 communicating with the second passage 23 and communicated with the first passage 22 via the first communication hole 26. Therefore, the EGR gas that has flowed into the inflow passage 21 through the joint pipe 37 passes through the first communication hole 26 and the first passage 22 and is introduced from the gas inlet 57 of the EGR cooler 52 into the EGR passage. Then, the EGR gas cooled by flowing through the EGR passage of the EGR cooler 52 passes through the second passage 23 and the outflow passage 33 from the gas outlet 58 and then flows out to the intake passage through the piping member.

  In addition, after warming up, the cooling water from the engine cooling water circuit flows into the cooling water passage 50 from the inlet pipe 83 of the valve housing 12, and passes through the cooling water passage 50 in the circumferential direction, that is, counterclockwise in plan view. A passage wall that surrounds the right side, the rear side, and the left side of the inflow passage 21 and the first passage 22 that are susceptible to high temperature (for example, 650 ° C.) of the exhaust gas in the EGR gas passage 13 of the valve housing 12 by being circulated. 80 is cooled. Along with this, the rear side portion of the hole wall around the seal member 64 and the bearing 62 in the both bearing boss portions 48 adjacent to the cooling water passage 50 (including the overhang passage portion 50a and the connection hole 82), the right side bearing boss portion. 48, the lower side portion of the hole wall around the seal member 64 and the bearing 62, the right front fastening boss portion 41, the upper side portion of the hole wall around the seal member 64 and the bearing 62 in the right bearing boss portion 48, and the upper end side. The left rear portion and the right rear portion of the fastening boss portion 41 and the left rear portion and the right rear portion of the mounting flange 53 are also locally cooled. The shortest distance between the cooling water passage 50 and a portion adjacent to the cooling water passage 50 is preferably set to 30 mm or less.

  Further, the total amount of cooling water flowing to the left end portion of the cooling water passage 50 flows from the cooling water inlet 59 (see FIG. 9) of the cooler housing 54 of the EGR cooler 52 to the outlet pipe 60 (see FIG. 9). 6) to return to the engine coolant circuit. Further, when cold, the supply of the cooling water into the cooling water passage 50 of the valve housing 12 is stopped, so that the warm-up efficiency is improved.

  According to the EGR cooler bypass valve 10 described above, the overheat suppressing means (the cooling water passage 50 of the valve housing 12 and the heat transfer ring 68) for suppressing overheating of the seal member 64 is provided. Accordingly, the overheating of the sealing member 64 is suppressed by the overheating suppressing means, so that the inexpensive sealing member 64 can be used. This is effective as an EGR gas switching valve through which high-temperature (for example, about 650 ° C.) exhaust gas flows through the EGR gas passage 13 of the valve housing 12.

  The overheat suppression means is a passage formed in the passage wall 80 of the EGR gas passage 13 of the valve housing 12 so as to surround the EGR gas passage 13 in the circumferential direction, and the cooling water passage through which the cooling water flows. 50. Therefore, the valve housing 12 can be cooled by efficiently exchanging heat between the cooling water flowing through the cooling water passage 50 and the valve housing 12. This makes it possible to use the valve housing 12 made of an aluminum alloy material as the valve housing 12 through which the exhaust gas having a high temperature (for example, about 650 ° C.) flows in the EGR gas passage 13, thereby reducing the weight and the cost of the valve housing 12. It is effective for realizing the system.

  The cooling water passage 50 is adjacent to the hole wall of the valve housing 12 in which the seal member 64 is provided. Therefore, the hole wall of the valve housing 12 in which the seal member 64 is provided can be cooled by the cooling water flowing through the cooling water passage 50.

  In addition, one axial side (lower side) of the cooling water passage 50 is opened at the joint surface of the valve housing 12 to the cooler housing 54 in which the EGR passage communicating with the EGR gas passage 13 is formed. Therefore, when the cooler housing 54 is communicated with the valve housing 12, it is possible to close the opening surface of the cooling water passage 50 opened at the joint surface of the valve housing 12 with the cooler housing 54. For this reason, another component for closing the opening surface of the cooling water passage 50 can be omitted. Further, when the valve housing 12 is cast (die casting), the EGR gas passage 13 and the cooling water passage 50 can be formed as a whole by die cutting. This is effective in realizing cost reduction by reducing the number of holes drilled in the valve housing 12.

  Further, when the cooler housing 54 provided with the cooler cooling water passage for flowing the cooling water in the EGR cooler 52 for cooling the EGR gas is attached to the valve housing 12, the cooler cooling water passage of the cooler housing 54 is connected to the valve housing 12. In this configuration, the cooling water passage 50 is communicated. Accordingly, it is possible to continuously flow the entire amount of cooling water through the cooler cooling water passage of the cooler housing 54 and the cooling water passage 50 of the valve housing 12. As a result, the cooler housing 54 and the valve housing 12 can be efficiently cooled as compared with the case where the cooling water is divided and supplied to the cooler cooling water passage of the cooler housing 54 and the cooling water passage 50 of the valve housing 12.

  Further, at the right front corner, the left rear corner, and the right rear corner of the mounting flange 53 for fastening the cooler housing 54 provided in the valve housing 12 and formed with the EGR passage communicating with the EGR gas passage 13, A cooling water passage 50 is adjacent. Therefore, the right front corner, the left rear corner, and the right rear corner of the mounting flange 53 of the valve housing 12 can be cooled by the cooling water flowing through the cooling water passage 50. This can prevent the screw parts from loosening due to high temperatures in the right front corner, left rear corner, and right rear corner of the mounting flange 53. In addition to the bolt, the screw component corresponds to a nut, a screw, a screw, or the like.

  Further, the overheat suppressing means has a good heat transfer property interposed between the hole wall of the valve housing 12 in which the seal member 64 is provided and the shaft portion inside the seal member 64 in the valve shaft 15 in a contact state. It is comprised by the heat ring 68 (refer FIG. 3). Therefore, heat transfer from the valve shaft 15 to the seal member 64 can be suppressed by transferring the heat of the valve shaft 15 to the valve housing 12 by the heat transfer ring 68. Further, by blocking the EGR gas passing between the valve shaft 15 and the hole wall of the valve housing 12 by the heat transfer ring 68, the seal member 64 can be prevented from being exposed to the EGR gas.

  The heat transfer ring 68 is a piston ring-shaped heat transfer ring that is fitted in an annular groove 67 formed on the outer peripheral surface of the shaft portion and elastically contacts the inner peripheral surface of the hole wall of the valve housing 12. 68. Therefore, the piston ring-shaped heat transfer ring 68 is pressed against the groove wall surface outside the annular groove 67 of the valve shaft 15 by the pressure of the EGR gas, thereby efficiently transferring the heat of the valve shaft 15 to the valve housing 12. be able to.

[Example 2]
A second embodiment of the present invention will be described. Since the present embodiment is a modification of the first embodiment, the changed portion will be described and redundant description will be omitted. Also, in the following embodiments, the changed parts will be described, and redundant description will be omitted. In addition, FIG. 16 is a principal part sectional view showing an EGR cooler bypass valve.
In the present embodiment, as shown in FIG. 16, the heat transfer ring 68 (see FIG. 3) in the first embodiment has a U-shaped cross section having an inner plate portion and an outer plate portion that can be elastically deformed in the radial direction. This is a change to an annular heat transfer ring 92. Accordingly, the annular groove 67 (see FIG. 3) of the valve shaft 15 is omitted. The inner plate portion of the heat transfer ring 92 is in elastic surface contact with the outer peripheral surface of the valve shaft 15. Further, the outer plate portion of the heat transfer ring 92 is in elastic surface contact with the inner peripheral surface of the hole wall of the bearing boss portion 48 of the valve housing 12. The outer peripheral surface of the valve shaft 15 slides and rotates with respect to the inner peripheral surface of the inner plate portion of the heat transfer ring 92. The heat transfer ring 92 corresponds to a “heat transfer member” in this specification.

[Example 3]
A third embodiment of the present invention will be described. This embodiment is a modification of the first embodiment. FIG. 17 is a top view showing the EGR cooler bypass valve.
In the present embodiment, as shown in FIG. 17, the diaphragm actuator 19 (see FIG. 6) in the first embodiment is changed to an electric motor (for example, DC motor) 94 as an electric actuator, and the valve housing 12 It is attached to. That is, a motor mounting portion 96 is formed on the rear side surface of the valve housing 12 that is adjacent to the cooling water passage 50. A mounting piece 95 a of a motor housing 95 of an electric motor 94 that can rotate forward and backward is fastened to the motor mounting portion 96 by a bolt 97. An output shaft 98 of the electric motor 94 is parallel to the valve shaft 15. The output shaft 98 of the electric motor 94 and the protruding end portion of the valve shaft 15 are connected via a gear mechanism 99 so that power can be transmitted. Therefore, the valve shaft 15 is rotated by forward and reverse rotation of the electric motor 94. According to this configuration, the motor mounting portion 96 of the valve housing 12 can be cooled by the cooling water flowing through the cooling water passage 50. Thereby, the electric motor 94 that dislikes high temperature can be attached to the valve housing 12. Further, by adopting a DC motor as the electric motor, it is possible to perform precise opening / closing control of the valve body 17. The motor mounting portion 96 corresponds to an “actuator mounting portion” in this specification.

[Example 4]
Embodiment 4 of the present invention will be described. This embodiment is a modification of the first embodiment. FIG. 18 is a cross-sectional view of the main part showing the EGR cooler bypass valve.
In the present embodiment, as shown in FIG. 18, the valve shaft 15 (see FIG. 3) in the first embodiment has a hollow structure. That is, the valve shaft (reference numeral 100) is formed of a hollow shaft and has a hollow portion 101 penetrating in the axial direction. Therefore, compared with the valve shaft 15 made of a solid shaft, the substantial cross-sectional area of the valve shaft 100 made of a hollow shaft is reduced, thereby suppressing heat transfer from the valve plate side of the valve shaft 100 to the seal member 64 side. be able to. It should be noted that the valve shaft 100 having a hollow structure corresponds to “overheating suppression means” in the present specification.

[Example 5]
A fifth embodiment of the present invention will be described. This embodiment is a modification of the first embodiment. In addition, FIG. 19 is principal part sectional drawing which shows an EGR cooler bypass valve.
In this embodiment, as shown in FIG. 19, the shaft portion outside the seal member 64 in the valve shaft 15 (see FIG. 3) of the first embodiment, that is, the shaft portion between the seal member 64 and the bearing 62 is screwed. It is roughened by forming on the shaft portion 103. Therefore, the heat transfer area from the valve shaft 15 to the seal member 64 can be suppressed by increasing the heat radiation area by the screw shaft portion 103 of the valve shaft 15. It should be noted that roughening the valve shaft 15 corresponds to “overheating suppression means” in this specification.

  The present invention is not limited to the above-described embodiments, and modifications can be made without departing from the gist of the present invention. For example, in the above embodiment, the valve housing 12 is formed of an aluminum alloy material, but the valve housing 12 may be formed of a cast iron material, a synthetic resin material, or the like. Further, not only the catalyst device (not shown) but also an exhaust pipe, an EGR pipe, or the like may be connected to the upstream side of the joint pipe 37. In addition, the technical elements described in the above embodiments can exhibit technical usefulness alone or in various combinations.

10 ... EGR cooler bypass valve (exhaust gas switching valve)
12 ... Valve housing 13 ... EGR gas passage (exhaust gas passage)
15 ... Valve shaft (solid shaft)
17 ... Valve 19 ... Actuator 37 ... Joint pipe (communication part)
41 ... Fastening boss part (fastening part)
50. Cooling water passage (refrigerant passage, overheat suppression means)
52 ... EGR cooler (exhaust gas cooler)
53 ... Mounting flange 54 ... Cooler housing (communication parts)
64 ... Seal member 65 ... Gap 67 ... Annular groove 68 ... Heat transfer ring (heat transfer member)
80 ... passage wall 92 ... heat transfer ring (heat transfer member)
94: Electric motor (actuator)
96 ... Motor mounting part (actuator mounting part)
100 ... Valve shaft (hollow shaft)

Claims (11)

A valve housing in which an exhaust gas passage is formed;
A valve body that is rotatably provided to the valve housing via a valve shaft, and switches a flow of exhaust gas;
An exhaust gas switching valve comprising: a seal member provided in a radial gap between the valve shaft and the valve housing;
An exhaust gas switching valve comprising overheat suppression means for suppressing overheating of the seal member. The exhaust gas switching valve according to claim 1,
The overheat suppression means is a passage formed in the passage wall of the exhaust gas passage of the valve housing so as to surround the exhaust gas passage in the circumferential direction, and is constituted by a refrigerant passage through which refrigerant flows. An exhaust gas switching valve characterized by that. The exhaust gas switching valve according to claim 2,
The exhaust gas switching valve, wherein the refrigerant passage is adjacent to a hole wall of the valve housing in which the seal member is provided. The exhaust gas switching valve according to claim 2 or 3,
An exhaust gas switching valve characterized in that one side in the axial direction of the refrigerant passage is opened at a joint surface of the valve housing with respect to a communicating part in which a gas communication passage communicating with the exhaust gas passage is formed. The exhaust gas switching valve according to any one of claims 2 to 4,
When the cooler housing provided with the refrigerant passage for flowing the refrigerant in the exhaust gas cooler for cooling the exhaust gas is attached to the valve housing, the refrigerant passage of the cooler housing communicates with the refrigerant passage of the valve housing. Features an exhaust gas switching valve. The exhaust gas switching valve according to any one of claims 2 to 5,
The exhaust gas switching valve, wherein the refrigerant passage is adjacent to a fastening portion that fastens a communication part provided in the valve housing and formed with a gas communication passage communicating with the exhaust gas passage. The exhaust gas switching valve according to any one of claims 2 to 6,
An exhaust gas switching valve, wherein an actuator mounting portion for mounting an actuator for driving the valve shaft is provided at a portion adjacent to the refrigerant passage in the valve housing. The exhaust gas switching valve according to any one of claims 1 to 7,
The overheat suppression means is a heat transfer material with good heat conductivity interposed in contact between a hole wall of the valve housing in which the seal member is provided and a shaft portion inside the seal member in the valve shaft. An exhaust gas switching valve comprising a member. The exhaust gas switching valve according to claim 8,
The heat transfer member is a piston ring-shaped heat transfer ring that is fitted in an annular groove formed on the outer peripheral surface of the shaft portion and elastically contacts the inner peripheral surface of the hole wall of the valve housing. An exhaust gas switching valve characterized by that. The exhaust gas switching valve according to any one of claims 1 to 9,
The exhaust gas switching valve, wherein the overheat suppression means is configured by making the valve shaft into a hollow structure. The exhaust gas switching valve according to any one of claims 1 to 10,
The exhaust gas switching valve is characterized in that the heat transfer suppression means is formed by roughening a shaft portion outside the seal member in the valve shaft.

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