JP2008101481A - Exhaust system structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust system structure capable of protecting an actuator for driving a valve element from exhaust heat. <P>SOLUTION: This exhaust system structure 10 for a vehicle comprises a thermostat 72 for driving a valve 50 so installed as to open and close a bypass flow passage 20 forming an exhaust path and bypassing an exhaust system heat exchanger 14 and a first protector member 82 installed between the side wall 46C of a heat exchanger rear shell 46 and the thermostat 72 in which the valve 50 is installed in the exhaust circuit. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an exhaust system structure including a valve body for opening and closing at least a part of an exhaust system path.

An engine exhaust system valve structure having a valve wall that opens and closes a muffler pipe inside the muffler according to the exhaust pressure is known (see, for example, Patent Document 1).
JP 2002-295250 A

  In the configuration in which the valve is driven using the exhaust pressure as described above, measures against heat damage to the actuator for driving the valve are not considered.

  An object of the present invention is to obtain an exhaust system structure capable of protecting an actuator for driving a valve body against exhaust heat.

  An exhaust system structure according to a first aspect of the present invention comprises an actuator for driving a valve body provided so that at least a part of an exhaust path of a vehicle can be opened and closed, and an installation portion of the valve body in the exhaust path. A heat shield provided between the outer wall and the actuator.

  In the exhaust system structure according to the first aspect, the valve body is driven by operating the actuator, and part or all of the exhaust path is opened or closed (the opening degree is adjusted). Here, since a heat shield is disposed between the outer wall constituting the valve body installation part in the exhaust path and the actuator, heat transfer from the outer wall of the exhaust path to the actuator (radiant heat, convection heat transfer, etc.) ) Is blocked by the heat shield, and the actuator is protected from the exhaust heat.

  Thus, in the exhaust system structure according to the first aspect, the actuator for driving the valve body can be protected against the exhaust heat. The heat shield may be a simple wall, for example, or may have a hollow structure in which the inside forms a heat insulating space.

  An exhaust system structure according to a second aspect of the present invention is the exhaust system structure according to the first aspect, wherein the heat shield is disposed outside the actuator and the outer wall, and the driving force of the actuator is applied to the valve body. It is arranged between the power transmission part to transmit.

  In the exhaust system structure according to the second aspect, the driving force of the actuator is transmitted to the valve body through the power transmission unit, and the exhaust path is opened or closed. Exhaust heat of the exhaust gas contacting the valve body is transmitted from the valve body to a power transmission unit located outside the outer wall (exhaust system path). Here, since the heat shield is disposed between the power transmission unit and the actuator, heat (radiant heat, convection heat, etc.) from the power transmission unit to the actuator is blocked by the heat shield, and the actuator is exhausted. Protected against heat.

  An exhaust system structure according to a third aspect of the present invention includes an actuator for driving a valve body provided to be capable of opening and closing at least a part of an exhaust path of a vehicle, and an exhaust system structure disposed outside the exhaust path. A power transmission unit that transmits a driving force to the valve body; and a heat shield provided between the power transmission unit and the actuator.

  In the exhaust system structure according to the third aspect, the driving force of the actuator is transmitted to the valve body via the power transmission unit, and a part or all of the exhaust path is opened or closed (the opening degree is adjusted). Exhaust heat of the exhaust gas contacting the valve body is transmitted from the valve body to a power transmission unit located outside the outer wall (exhaust system path). Here, since the heat shield is disposed between the power transmission unit and the actuator, the heat transfer path (radiant heat, convection heat transfer, etc.) from the power transmission unit to the actuator is blocked by the heat shield, and the actuator Is protected against exhaust heat.

  Thus, in the exhaust system structure according to the third aspect, the actuator for driving the valve body can be protected against the exhaust heat. The heat shield may be a simple wall, for example, or may have a hollow structure in which the inside forms a heat insulating space.

  An exhaust system structure according to a fourth aspect of the present invention is the exhaust system structure according to the second or third aspect, wherein the heat shield forms a heat insulating space that covers the power transmission unit.

  In the exhaust system structure according to claim 4, since the heat shield forms a heat insulating space that covers the power transmission unit, heat transfer (particularly convective heat transfer) from the power transmission unit to the actuator is effectively suppressed. The

  The exhaust system structure according to a fifth aspect of the present invention is the exhaust system structure according to any one of the first to fourth aspects, wherein the heat shield is a protrusion of the output portion of the actuator toward the valve body. And a body portion of the actuator is positioned in the through hole.

  In the exhaust system structure according to the fifth aspect, the actuator drives the valve body by projecting the output part (movable part relative to the main body part) to the valve body side (power transmission part side). Here, since the main body of the actuator enters the through hole of the heat shield, compared to the configuration in which the output part is allowed to move (slid), the through hole edge of the heat shield and the actuator The gap can be set small, and the heat shielding performance can be improved.

  An exhaust system structure according to a sixth aspect of the present invention is the exhaust system structure according to any one of the first to fifth aspects, wherein the exhaust path is a heat exchanger that performs heat exchange between the exhaust gas and the refrigerant. The actuator is a thermostat that drives the valve body in accordance with the temperature of the refrigerant.

  In the exhaust system structure according to claim 6, for example, in a state where the valve body opens the bypass passage, the exhaust gas mainly flows through the bypass passage, and in a state where the valve body closes the bypass passage, Heat exchange with the refrigerant is performed mainly through the heat exchanger (exhaust gas flow path). For example, when the temperature of the refrigerant becomes equal to or higher than a predetermined temperature, the thermostat operates to open the bypass flow path or increase the opening degree. The thermostat that operates according to the temperature of the refrigerant that is the low-temperature side fluid is effectively protected from the exhaust heat of the exhaust gas that is the high-temperature side fluid by the heat shield.

  The exhaust system structure according to a seventh aspect of the present invention is the exhaust system structure according to the sixth aspect, wherein the valve body is disposed in a flow direction of the exhaust gas with respect to a range where a refrigerant flow path of the heat exchanger is formed. It is arrange | positioned in the upstream or downstream, and the said heat shield includes the overhang | projection part located between the said thermostat and the range in which the refrigerant | coolant flow path in the said heat exchanger is formed.

  In the exhaust system structure according to claim 7, the valve element disposed upstream or downstream in the flow direction of the exhaust gas with respect to a range where the refrigerant flow path in the heat exchanger is formed corresponds to the temperature of the refrigerant. The main flow of the exhaust gas is switched by opening and closing the bypass passage by being driven by a thermostat that operates. That is, the thermostat is located upstream from the range in which the refrigerant flow path in the heat exchanger is formed to the position where the valve body (the power transmission portion thereof) is disposed (the upstream side in the exhaust gas flow direction with respect to the formation range of the refrigerant flow path). It extends to the vicinity of the downstream side. On the other hand, the heat shield extends from the outer wall of the valve body installation portion or the vicinity of the power transmission portion to the range where the refrigerant flow path in the heat exchanger is formed by the overhang portion. That is, the heat shield range by the heat shield extends to a portion where it is difficult to raise the temperature by the refrigerant flow path, and the thermostat for driving the valve body can be more effectively protected against the exhaust heat.

  As described above, the exhaust system structure according to the present invention has an excellent effect that the actuator for driving the valve body can be protected against the exhaust heat.

  A vehicle exhaust system structure 10 to which an exhaust system structure according to a first embodiment of the present invention is applied will be described with reference to FIGS. 1 to 8. First, a schematic overall configuration of the vehicle exhaust system structure 10 will be described, then an exhaust system heat exchanger 14 constituting the vehicle exhaust system structure 10 will be described, and then a thermostat heat shield structure which is a main part of the present invention. Will be described. In the following description, when the terms upstream and downstream are simply used, they indicate upstream and downstream in the flow direction of the exhaust gas. For convenience of explanation, directions indicated by arrows F, U, and W in the respective drawings are respectively referred to as a forward direction, an upward direction, and a width direction.

(Overall Configuration) FIG. 8 shows a schematic overall configuration of a vehicle exhaust system structure (exhaust heat recovery system) 10 in a flowchart. As shown in this figure, the vehicle exhaust system structure 10 recovers the heat of the exhaust gas of the engine 12 which is an internal combustion engine of an automobile by heat exchange with the engine cooling water, and promotes heating or warming up of the engine 12. The exhaust system heat exchanger 14 used for the above is included.

  Specifically, the engine 12 is connected to an exhaust pipe 15 that constitutes an exhaust path through which exhaust gas is derived. On the exhaust gas discharge path by the exhaust pipe 15, a catalytic converter 16, an exhaust system heat exchanger 14 as a heat exchanger, and a main muffler 18 are arranged in order from the upstream side. The catalytic converter 16 is configured to purify exhaust gas passing therethrough by a built-in catalyst 16A. The main muffler 18 as a silencer is configured to reduce (silence) the exhaust noise generated when exhaust gas is discharged into the atmosphere.

  In addition, the vehicle exhaust system structure 10 includes a bypass channel 20 for exhaust gas to bypass the exhaust system heat exchanger 14 (a heat exchange unit 14A described later), and a valve for opening and closing the bypass channel 20. A flow path switching valve 22 is provided. Thus, the vehicle exhaust system structure 10 is configured to be able to switch between an exhaust heat recovery mode in which the exhaust gas exchanges heat with the engine coolant and a normal mode in which the exhaust gas passes through the bypass flow path 20. .

  Further, the vehicle exhaust system structure 10 includes a refrigerant for circulating engine cooling water as a refrigerant for exchanging heat with exhaust gas in a heat exchanging portion 14A (an engine cooling water flow path 34 described later) of the exhaust heat exchanger 14. A cooling water circulation path 24 is provided as a flow path. In this embodiment, the cooling water circulation path 24 connects the engine 12 and the exhaust system heat exchanger 14 in series. Although not shown, a heater core as a heater heat source is disposed on the coolant circulation path 24.

  In the vehicle exhaust system structure 10 according to this embodiment, the bypass flow path 20 is provided inside the exhaust system heat exchanger 14, and the flow path switching valve 22 is heat exchange in the exhaust system heat exchanger 14. It arrange | positions downstream with respect to the part 14A.

(Configuration of Exhaust System Heat Exchanger) As shown in FIG. 7, the exhaust system heat exchanger 14 includes a partition pipe 26 that separates an exhaust gas flow path and an engine cooling water flow path. In this embodiment, the partition pipe 26 has spiral grooves 26A and 26B formed in a spiral shape inside and outside the pipe wall. The spiral groove 26A and the spiral groove 26B are formed over substantially the entire length of the heat exchanging portion 14A for exchanging heat between the exhaust gas and the engine coolant, and the front and rear of the partition wall pipe 26 are front and rear with respect to the heat exchanging portion 14A. The exhaust gas introduction part 26C and the exhaust gas discharge part 26D are provided respectively.

  Inside the partition pipe 26, an inner pipe 28 as a bypass pipe portion formed in a substantially cylindrical shape is coaxially disposed. A space formed between the partition pipe 26 and the inner pipe 28 serves as an exhaust gas passage 30 of the exhaust system heat exchanger 14. The partition pipe 26 is covered from the outer peripheral side by an outer pipe 32 that is formed in a substantially cylindrical shape and is coaxially arranged. A space between the partition pipe 26 and the outer pipe 32 serves as an engine coolant flow path 34 of the exhaust system heat exchanger 14.

  In the exhaust system heat exchanger 14, as shown in FIG. 7, the formation range of the engine coolant flow path 34 in the exhaust gas flow direction (the radially outer portion of the inner pipe 28) is the heat between the exhaust gas and the engine coolant. The heat exchange part 14A is exchanged, and the inner pipe 28 protrudes upstream and downstream of the heat exchange part 14A. The space in the inner pipe 28 in the exhaust system heat exchanger 14 is the bypass channel 20 described above. That is, the bypass flow path 20 is disposed so as to be able to bypass the heat exchanging portion 14A.

  More specifically, as shown in FIG. 7, the upstream end 28A of the inner pipe 28 is connected to the downstream end of the exhaust pipe 15A on the catalytic converter 16 side, and the downstream end 28B of the inner pipe 28 is connected to the exhaust gas. The guide pipe 38 is connected to the upstream end 38A substantially coaxially. Instead of the exhaust gas guide pipe 38, the inner pipe 28 may be extended downstream. In addition, the front end of the exhaust gas introduction part 26C (upstream part from the heat exchanging part 14A) protruding upstream from the outer pipe 32 (engine coolant flow path 34) in the partition pipe 26 is the outer peripheral surface of the upstream end 28A of the inner pipe 28. Connected in an airtight manner. Further, the exhaust gas discharge part 26D (downstream part of the heat exchange part 14A) of the partition pipe 26 protruding downstream from the outer pipe 32 (engine cooling water flow path 34) in the partition pipe 26 is exhausted via the end pipe 40. The guide pipe 38 is connected in an airtight state.

  In the inner pipe 28, the portion located inside the exhaust gas introduction portion 26 </ b> C of the partition wall pipe 26 has a bypass flow path 20 that is a space in the inner pipe 28 and an exhaust gas flow path 30 of the exhaust heat exchanger 14. A through hole 42 is provided in communication with. That is, the through hole 42 constitutes a branch portion between the exhaust gas passage 30 and the bypass passage 20. On the other hand, the end pipe 40 is provided with a through hole 44 that communicates the inside and outside of the exhaust gas passage 30. The downstream opening end 38B of the through hole 44 and the exhaust gas guide pipe 38 is an exhaust gas outlet that is a space in the rear shell 46 of the heat exchanger as a shell in which the upstream opening end 46A is connected to the end pipe 40 in an airtight state. Each header 48 is opened. In this embodiment, as shown in FIGS. 2 and 3, the heat exchanger rear shell 46 has a bulging portion 46 </ b> B that bulges on one side in the width direction with respect to the outer pipe 32.

  Therefore, in the exhaust system heat exchanger 14, the exhaust gas that bypasses the heat exchanging portion 14 </ b> A and passes through the bypass flow path 20 passes through the inside of the exhaust gas guide pipe 38 and is exhausted in the heat exchanger rear shell 46. On the other hand, the exhaust gas that has reached the outlet header 48 and passed through the exhaust gas passage 30 via the through-hole 42 is located outside the exhaust gas guide pipe 38 and inside the heat exchanger rear shell 46 via the through-hole 44. The exhaust gas outlet header 48 is configured.

  Further, in the exhaust heat exchanger 14, a valve 50 as a valve body constituting the flow path switching valve 22 can open and close the downstream opening end 38 </ b> B of the exhaust gas guide pipe 38 in the heat exchanger rear shell 46. It is arranged. The valve 50 rotates around a rotation shaft 52 supported by the heat exchanger rear shell 46, thereby closing the downstream opening end 38B of the exhaust gas guide pipe 38 (see the solid line in FIG. 7). A valve 50 is provided that can take an open posture (see an imaginary line in FIG. 7) that rotates in the direction of arrow A from the closed position to open the downstream side open end 38B of the exhaust gas guide pipe 38. The valve 50 positioned in the closed posture is configured to abut a valve seat (seal) 54 provided around the downstream opening end 38 </ b> B in the exhaust gas guide pipe 38.

  As shown in FIG. 3, the rotation shaft 52 is disposed in the bulging portion 46 </ b> B of the heat exchanger rear shell 46 and is held by a bearing holder 57 attached to a frame 56 fixed to the exhaust gas guide pipe 38. The bearing 58 and the bearing 60 held by the bearing holder 59 attached to the frame 56 are rotatably supported with respect to the heat exchanger rear shell 46 at two locations spaced in the longitudinal direction. The valve 50 is connected to the rotating shaft 52 through an arm 62 so as to be integrally rotatable. Accordingly, the valve 50 can take the above-described closed posture and open posture by rotating around the rotation shaft 52. Further, a lever 64 is fixed to an end of the rotating shaft 52 that protrudes outside the rear shell 46 of the heat exchanger, and the lever 64 is provided with a stopper 66.

  The stopper 66 is engaged with the other end 68B of a return spring 68 as an urging member whose one end 68A is engaged with the rear shell 46 of the heat exchanger (see FIG. 3). The rotating shaft 52 is biased in a direction in which the valve 50 takes a closed posture by the biasing force of the return spring 68. In this embodiment, the rotating shaft 52 (the protruding portion of the heat exchanger rear shell 46 outside), the lever 64, and the stopper 66 (and the return spring 68) are configured so that a driving force from a thermostat 72 described later acts. These are collectively referred to as a power transmission unit 65.

  With the above configuration, in the exhaust system heat exchanger 14 (flow path switching valve 22), when the exhaust gas pressure is low, the valve 50 is connected to the exhaust gas guide pipe 38, that is, the bypass flow path 20 by the biasing force of the return spring 68. The exhaust gas flows through the exhaust gas passage 30 of the heat exchanging section 14A. On the other hand, when the pressure of the exhaust gas exceeds a predetermined value, the valve 50 takes an open posture according to the pressure of the exhaust gas against the urging force of the return spring 68. In this embodiment, the valve 50 is set to take an open posture in which the maximum opening is obtained by the pressure of the exhaust gas depending on the pressure of the exhaust gas when the internal combustion engine generates the maximum output.

  In this embodiment, the flow path switching valve 22 forcibly closes the valve 50 regardless of the pressure of the exhaust gas when the temperature of the engine cooling water that exchanges heat with the exhaust gas is equal to or higher than a predetermined temperature. It is designed to hold in a posture. Specifically, as shown in FIGS. 1 and 2, a first cooling water inlet pipe 70 whose inside communicates with the engine cooling water flow path 34 is connected to the downstream side of the outer pipe 32 in the exhaust gas flow direction. .

  A thermostat (thermoactuator) 72 as an actuator in the present invention is disposed at the end of the first cooling water inlet pipe 70, and the thermostat 72 is a main body 74 provided in the first cooling water inlet pipe 70. And a pressing rod 75 as an output part capable of moving back and forth (expanding and contracting) with respect to the main body part 74. The thermostat 72 is configured such that the pressing rod 75 protrudes from the main body portion 74 due to the thermal expansion of the wax filled in the main body portion 74. A rod sliding portion 74A that restricts (guides) the advancing and retreating direction of the pressing rod 75 with respect to the main body portion 74 in a predetermined direction while sliding with the pressing rod 75 is provided at the distal end of the main body portion 74.

  In this embodiment, the thermostat 72 projects (extends) the pressing rod 75 from the main body 74 when the engine coolant temperature in the first coolant inlet pipe 70 is equal to or higher than a predetermined temperature (for example, 80 ° C.). The lever 64 is pressed, and the valve 50 is set to a fully open posture (opened posture is maintained) having a larger opening degree than the above-described guide posture. As shown by a chain line in FIG. 7, the fully open posture is a posture rotated by approximately 90 ° in the direction of arrow A from the closed posture.

  As shown in FIG. 1 and FIG. 2, the engine cooling water is passed through the first cooling water inlet pipe 70 to the engine cooling water flow path 34 of the exhaust system heat exchanger 14 at the intermediate portion of the first cooling water inlet pipe 70. A second cooling water inlet pipe 76 for introducing water is connected. On the other hand, a cooling water outlet pipe 78 for discharging engine cooling water from the engine cooling water flow path 34 is connected to the upstream side of the outer pipe 32 in the exhaust gas flow direction. The cooling water outlet pipe 78 communicates with a substantially vertical top (uppermost portion) of the outer pipe 32, and the second cooling water inlet pipe 76 communicates with the first cooling slightly below the vertical top of the outer pipe 32. The uppermost portion of the water inlet pipe 70 communicates with a portion higher than the uppermost portion of the outer pipe 32. The second cooling water inlet pipe 76 and the cooling water outlet pipe 78 are connected to the cooling water circulation path 24 including the engine 12, the radiator, and the heater core so as to be in series with the engine 12 along the engine cooling water flow as described above. Yes.

  As described above, the exhaust system heat exchanger 14 is a countercurrent heat exchanger in which the flow direction of the exhaust gas and the flow direction of the engine cooling water are opposite to each other. In this embodiment, the exhaust system heat exchanger 14 14, the exhaust gas generates a spiral flow along the spiral groove 26A, and the engine coolant generates a spiral flow opposite to the exhaust gas along the spiral groove 26B. It has a highly efficient configuration. In the exhaust system heat exchanger 14, the exhaust gas pressure loss (back pressure) due to passing through the bypass flow path 20 is sufficiently smaller than the exhaust gas pressure loss due to passing through the exhaust gas flow path 30. When the valve 50 is in the open position, the exhaust gas mainly flows through the bypass flow path 20.

(Thermal insulation structure of thermostat) FIGS. 1 to 3 show a thermal insulation structure 80 of a thermostat applied to the exhaust system heat exchanger 14 in a side view, a plan view, and a front view (cross-sectional view perpendicular to the axis). 4 and 5 are a perspective view and an exploded perspective view of the heat shield structure 80. FIG.

  As shown in these drawings, the heat shield structure 80 is disposed between the side wall 46C (outer wall in the present invention) of the heat exchanger rear shell 46 housing the valve 50 and the power transmission portion 65, and the thermostat 72. A first protector member 82 is provided as a provided heat shield. The first protector member 82 is configured to block the heat transfer (radiation, convection heat transfer) path from the side wall 46C of the heat exchanger rear shell 46 and the power transmission unit 65 to the thermostat 72. In this embodiment, the first protector member 82 includes a heat shield wall (partition wall) 84 positioned between the side wall 46C and the power transmission portion 65 and the thermostat 72, and a flange portion 86 protruding from the periphery of the heat shield wall 84. have.

  The heat shield wall 84 has a flat plate portion 84B in front of the flat plate portion 84A between the flat plate portion 84A far from the side wall 46C of the heat exchanger rear shell 46 and the flat plate portion 84B closer to the side wall 46C. The inclined plate portion 84C is connected so as to be positioned on the upstream side. The flat plate portion 84A of the heat shield wall 84 is formed in a substantially semicircular shape when viewed from the front, and as shown in FIG. 3, it penetrates through the pressing rod 75 so as to protrude toward the power transmission portion 65 (side wall 46C). A hole 85 is provided. The heat shield wall 84, that is, the end portion 84D on the side wall 46C side of the flat plate portion 84B substantially coincides with the position of the front end 46D of the heat exchanger rear shell 46 as shown in FIGS.

  As shown in FIG. 6 (A), a cylindrical portion 88 projects from the periphery of the through hole 85 in the heat shield wall 84 and allows the rod sliding portion 74A of the main body portion 74 constituting the thermostat 72 to enter. ing. In addition, instead of the structure of FIG. 6A, as shown in FIG. 6B, a through-hole 85 and a cylindrical portion 88 for entering the main body portion 74 are provided, and the rod sliding portion 74A is attached to the heat shield wall 84. It is also possible to arrange the power transmission unit 65 (side wall 46C). The configuration of FIG. 6A is applied to, for example, a thermostat 72 in which a rubber bush G that seals the peripheral portion of the pressing rod 75 is disposed at the root of the rod sliding portion 74A, and the configuration of FIG. For example, the present invention is applied to a thermostat 72 that does not incorporate a rubber bush G.

  The heat shield structure 80 includes a second protector member 90 as a heat shield. The second protector member 90 is surrounded (substantially hermetically sealed) by the side wall 46C of the rear shell 46 of the heat exchanger 46 and the first protector member 82 (heat shield wall 84), and the heat input / output by air, that is, convection is suppressed ( A heat-insulating space R that is prevented) is formed. In the heat insulating structure 80, the power transmission unit 65, that is, the lever 64, the stopper 66, and the return spring 68 are disposed in the heat insulating space R.

  Specifically, as shown in FIGS. 4 and 5, the second protector member 90 includes a front opening 90 </ b> A formed in a substantially U shape corresponding to the outer edge of the heat shield wall 84 in a front view, and a plan view. A U-shaped wall 92 having a side opening 90B facing the side wall 46C, which is formed in a substantially rectangular shape, a rear wall 94 for closing the rear portion of the U-shaped wall 92, and a side opening in the U-shaped wall 92 And a flange 96 protruding from the opening edge of 90B. In the second protector member 90, the flange portion 86 of the first protector member 82 is joined to the inner surface of the U-shaped wall 92, the front opening 90A is closed, and the flange 96 is joined to the heat exchanger rear shell 46. By closing the side opening 90 </ b> B, the first protector member 82 and the heat exchanger rear shell 46 form the heat insulating space R as described above. In this embodiment, a downward flange 96A extending from the upper edge of the U-shaped wall 92 of the flange 96 is joined to the upper wall 46E of the heat exchanger rear shell 46, and the remaining portion of the flange 96 is a lateral flange. 96B and joined to the side wall 46C.

  Next, the operation of the first embodiment will be described.

  In the vehicle exhaust system structure 10 configured as described above, when the engine coolant temperature is low, the valve 50 is free with respect to the thermostat 72, and the flow path switching valve 22 functions as a self-pressure valve. For this reason, under operating conditions where the pressure of the exhaust gas is low, the exhaust gas guide pipe 38, that is, the bypass flow path 20, is closed by the urging force of the return spring 68, and the exhaust gas flows through the exhaust gas flow path 30 of the heat exchanging portion 14A. The heat exchange with the engine cooling water flowing through the engine cooling water flow path 34 is performed. Thereby, warming-up promotion of an internal combustion engine and maintenance of heating at low temperature start are achieved.

  For example, when the exhaust gas pressure rises under operating conditions where the output of the internal combustion engine increases, such as acceleration or climbing, the valve 50 that has received the exhaust gas pressure resists the urging force of the return spring 68 in the direction of arrow A. Rotates and reaches an open position. As a result, the exhaust gas mainly flows through the bypass flow path 20, and the back pressure is reduced as compared with the case of flowing through the exhaust gas flow path 30. That is, in the vehicle exhaust system structure 10 provided with the flow path switching valve 22 that functions as a self-pressure valve, the reduction of the back pressure for securing output is prioritized over the exhaust heat recovery for warming up the internal combustion engine. In this case, the exhaust gas bypasses the heat exchanging portion 14A and flows through the bypass flow path 20, so that the back pressure is automatically reduced. When the internal combustion engine generates the maximum output, the valve 50 assumes the guidance posture (maximum opening degree due to the pressure of the exhaust gas) indicated by an imaginary line in FIG. 1 with the pressure of the exhaust gas.

  Further, in the vehicle exhaust system structure 10, when the engine cooling water temperature becomes 80 ° C. or higher, the pressing rod 75 of the thermostat 72 presses the lever 64 of the rotating shaft 52 to forcibly move the valve 50 to the fully open position. At the same time, it is held in the fully open position. As a result, the exhaust gas mainly flows through the bypass passage 20 and is discharged from the exhaust pipe 15 via the exhaust gas guide pipe 38 and the exhaust gas outlet header 48 of the heat exchanger rear shell 46. That is, the exhaust gas flow path is automatically switched to the bypass flow path 20 in an operation state where exhaust heat recovery is unnecessary.

  Here, since the vehicle exhaust system structure 10 includes the heat shield structure 80, the thermostat 72 is protected against exhaust heat radiated from the heat exchanger rear shell 46. More specifically, the heat transfer (radiation, convection heat transfer) path from the side wall 46C of the heat exchanger rear shell 46 to the thermostat 72 is blocked by the first protector member 82 (heat shield wall 84). Further, since the heat shield structure 80 of the vehicle exhaust system structure 10 includes the second protector member 90, the power transmission portion 65 (the lever 64, the stopper 66, the return spring) that is a portion (part) having a large amount of heat transfer and heat dissipation. 68 etc.) is enclosed in the heat insulating space R, and the convective heat transfer from the power transmission portion 65 is remarkably suppressed. Further, since the heat insulating space R and the outside air are formed between the side wall 46C and the thermostat 72, heat transfer from the side wall 46C to the thermostat 72 is effectively suppressed.

  In particular, in the heat shield structure 80, the cylinder portion 88 (through hole 85) of the heat shield wall 84 is a structure that allows the main body portion 74 (rod sliding portion 74A) of the thermostat 72 to enter. , And heat transfer (convection) through the gap is suppressed. Supplementally, for example, in the configuration in which the pressing rod 75 that is a movable portion is inserted, the inner diameter of the cylindrical portion 88 is set in consideration of the assembly error (variation) of each component and the positional deviation (variation) accompanying the operation of the pressing rod 75. However, in the configuration in which the main body portion 74 is inserted into the cylindrical portion 88, it is sufficient to consider only the assembly error. Therefore, the gap between the cylindrical portion 88 and the main body portion 74 can be reduced as described above.

  Thus, since the vehicle exhaust system structure 10 includes the flow path switching valve 22 that acts as a self-pressure valve, the heat exchanger rear shell 46 that houses the valve 50 is downstream of the heat exchanging portion 14A (outer pipe 32). The thermostat 72 provided in the low temperature side system of the exhaust system heat exchanger 14 in order to forcibly open the flow path switching valve 22 is provided in the configuration including the exhaust system heat exchanger 14 disposed in the heat exchanger. It is possible to protect against exhaust heat flowing through the rear shell 46 (particularly, exhaust heat under an operating condition in which the valve 50 is held in the fully open position by the thermostat 72).

  Thereby, in the exhaust system structure 10 for a vehicle, the thermostat 72 can be disposed close to the exhaust system heat exchanger 14 (the heat exchanger rear shell 46) on the high temperature side, thereby achieving compactness and space saving. It was realized.

Second Embodiment Next, a vehicle exhaust system structure 100 according to a second embodiment of the present invention will be described. Note that components / portions that are basically the same as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and description thereof may be omitted, and illustration may be omitted.

  9 to 12, the exhaust system heat exchanger 102 constituting the exhaust system structure 100 for a vehicle is shown in a side view, a partially enlarged plan view, a cross-sectional view perpendicular to the axis (front view), and a side cross-sectional view, respectively. It is shown. As shown in these drawings, the exhaust system heat exchanger 102 is provided with a heat shield structure 104 in place of the heat shield structure 80, and thus the exhaust system constituting the vehicle exhaust system structure 10 according to the first embodiment. Different from the heat exchanger 14. This will be specifically described below.

  As shown in FIGS. 9 to 11, the heat shield structure 104 includes a first protector member 106 and a second protector member 90 as heat shields as main parts. As shown in FIG. 13, the first protector member 106 includes a flat plate portion 108A having a shape corresponding to the flat plate portion 84A of the heat shield wall 84, and an inclined plate portion 108B inclined in the same direction as the inclined plate portion 84C of the heat shield wall 84. A heat shield wall 108 having A flange portion 86 is provided on the peripheral edge portion of the heat shield wall 108. Then, a substantially rectangular projecting heat shield wall 110 is projected (extended) from the front edge of the heat shield wall 108, that is, the inclined plate portion 108B, toward the front.

  The first protector member 106 described above has its flange portion 86 joined to the inner surface of the U-shaped wall 92, so that the heat exchanger rear shell 46 (exhaust system heat exchanger 14) is interposed via the second protector member 90. It is supported by. In this state, the heat shield wall 108 of the first protector member 106 is disposed between the side wall 46C and the power transmission unit 65 of the heat exchanger rear shell 46 and the thermostat 72, and the side wall 46C and the power transmission unit 65 are disposed. The heat transfer path from the thermostat 72 to the thermostat 72 is blocked.

  In this state, the overhanging heat shield wall 110 of the first protector member 106 extends in the exhaust gas flow direction of the heat exchanging portion 14A (engine cooling water flow path 34) in the exhaust heat exchanger 14, as shown in FIG. It includes a portion disposed between a portion immediately downstream of the downstream end (particularly, the exhaust gas discharge portion 26D of the single-walled partition wall pipe 26) and the main body portion 74 of the thermostat 72. In other words, the portion of the overhanging heat shield wall 110 that includes the front edge 110A overlaps the engine coolant flow path 34 in the exhaust gas flow direction. As a result, the overhanging heat shield wall 110 blocks the heat transfer path from the downstream side portion (exhaust gas discharge portion 26D) of the exhaust heat exchanger 14 to the heat exchange portion 14A to the thermostat 72.

  The other configuration of the exhaust system heat exchanger 102 is basically the same as the corresponding configuration of the exhaust system heat exchanger 14, and the other configuration of the vehicle exhaust system structure 100 is the same as that of the vehicle exhaust system structure 10. The configuration is basically the same. Therefore, in the vehicle exhaust system structure 100, the vehicle exhaust according to the first embodiment for switching from the exhaust heat recovery mode by the exhaust pressure to the normal mode, maintaining the switched state to the normal mode by the operation of the thermostat 72, etc. It operates in the same manner as the system structure 10.

  Here, since the vehicle exhaust system structure 100 includes the heat shield structure 104, the thermostat 72 is protected against the exhaust heat radiated from the heat exchanger rear shell 46. More specifically, the heat transfer (radiation, convection heat transfer) path from the side wall 46C of the heat exchanger rear shell 46 to the thermostat 72 is blocked by the first protector member 106 (heat shield wall 108). Further, since the heat shield structure 80 of the vehicle exhaust system structure 10 includes the second protector member 90, the power transmission portion 65 (the lever 64, the stopper 66, the return spring) that is a portion (part) having a large amount of heat transfer and heat dissipation. 68 etc.) is effectively suppressed.

  Further, in the vehicle exhaust system structure 100, since the overhanging heat shield wall 110 extends from the first protector member 106, the heat exchange part 14A and the heat exchanger rear shell 46 (valve in the exhaust system heat exchanger 14) Also in the portion (exhaust gas discharge portion 26D of the partition pipe 26) between the housing portion), the heat transfer (radiation, convection heat transfer) path to the thermostat 72 is blocked by the first protector member 106 (heat shield wall 108). It is done. Further, in this overhanging heat shield wall 110, air exhausted from the space surrounded by the second protector member 90, the first protector member 106, and the heat exchanger rear shell 46, that is, exhaust heat flows toward the thermostat 72. To prevent that. For this reason, even in the heat insulating structure 104 in which the heat insulating space R is not formed, it is possible to ensure the heat insulating performance equivalent to the heat insulating structure 80 according to the first embodiment.

  As described above, since the vehicle exhaust system structure 100 includes the flow path switching valve 22 that functions as a self-pressure valve, the heat exchanger rear shell 46 that accommodates the valve 50 is located downstream of the heat exchange portion 14A (outer pipe 32). In the configuration including the exhaust system heat exchanger 14 disposed, a thermostat 72 provided in the low temperature side system of the exhaust system heat exchanger 14 for forcibly opening the flow path switching valve 22 is provided at the rear of the heat exchanger. It is possible to protect against exhaust heat flowing through the shell 46 (particularly, exhaust heat under an operating condition in which the valve 50 is held in the fully open position by the thermostat 72).

  Thereby, in the exhaust system structure 10 for a vehicle, the thermostat 72 can be disposed in the vicinity of the exhaust system heat exchanger 14 (the heat exchanger rear shell 46), so that a reduction in size and space can be achieved. It was.

  Further, in the heat shield structure 104 of the exhaust system heat exchanger 102, the cylindrical portion 88 of the first protector member 106 is a structure in which the main body portion 74 of the thermostat 72 is inserted, so the heat shield structure 80 according to the first embodiment. In the same manner as described above, the gap between the cylinder portion 88 and the main body portion 74 can be reduced, and heat transfer (convection) through the gap is suppressed.

  In the second embodiment, the first protector member 106 and the second protector member 90 do not form the heat insulation space R that is a substantially sealed space (open between the first protector member 106 and the side wall 46C). However, the present invention is not limited to this example. For example, the first protector member 106 may be provided with a flat plate portion 84B, or the first protector member 106 and the overhanging heat shield wall 110. Alternatively, the heat insulating space R may be formed by the first protector member 106 and the second protector member 90 (and the heat exchanger rear shell 46) by providing a substantially U-shaped curved portion.

  In each of the above-described embodiments, the exhaust system structures 10 and 100 for the vehicle are provided with the exhaust system heat exchanger 14 and the exhaust system heat exchanger 102, and the flow path switching valve 22 (valve 50) is the exhaust system heat exchanger. Although an example of opening and closing the bypass flow path 20 for bypassing the 14 heat exchanging portions 14A has been shown, the present invention is not limited to this. For example, a part or all of the muffler and the exhaust pipe are opened and closed (fully closed). The present invention can be applied to an actuator of a valve device for switching fully open or adjusting an opening degree (including a case where there is no full close).

It is a side view of the exhaust system heat exchanger which comprises the exhaust system structure for vehicles which concerns on the 1st Embodiment of this invention. It is a top view which expands and shows the principal part of the exhaust system heat exchanger which comprises the exhaust system structure for vehicles which concerns on the 1st Embodiment of this invention. FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. 1. It is a perspective view which expands and shows the principal part of the exhaust system heat exchanger which comprises the exhaust system structure for vehicles which concerns on the 1st Embodiment of this invention. 1 is an exploded perspective plan view showing an enlarged main part of an exhaust system heat exchanger constituting an exhaust system structure for a vehicle according to a first embodiment of the present invention. (A) is a sectional side view schematically showing the relationship between the heat shield wall 84 and the thermostat 72 constituting the vehicle exhaust system structure according to the first embodiment of the present invention, and (B) is a modification thereof. It is a sectional side view which shows an example. It is a sectional side view of the exhaust system heat exchanger which comprises the exhaust system structure for vehicles which concerns on the 1st Embodiment of this invention. 1 is a flowchart showing a schematic overall configuration of a vehicle exhaust system structure according to a first embodiment of the present invention. It is a side view of the exhaust system heat exchanger which comprises the exhaust system structure for vehicles which concerns on the 2nd Embodiment of this invention. It is a top view which expands and shows the principal part of the exhaust system heat exchanger which comprises the exhaust system structure for vehicles which concerns on the 2nd Embodiment of this invention. FIG. 10 is a cross-sectional view taken along line 11-11 in FIG. It is a sectional side view of the exhaust system heat exchanger which comprises the exhaust system structure for vehicles which concerns on the 2nd Embodiment of this invention. It is a perspective view of the 1st protector which comprises the exhaust system structure for vehicles which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

10 Exhaust system structure for vehicles 14 Exhaust system heat exchanger (heat exchanger)
20 Bypass flow path (exhaust path)
22 Channel switching valve 34 Engine cooling water channel (refrigerant channel)
46 Heat exchanger rear shell (outer wall)
50 Valve (Valve)
65 Power transmission part 72 Thermostat (actuator)
74 Body 75 Pressing rod (Output unit)
82 Protector member (heat shield)
90 Protector member (heat shield)
100 Exhaust system structure for vehicle 102 Exhaust system heat exchanger (heat exchanger)
106 Protector member (heat shield)
110 Overhanging heat shield wall (overhang)
R Insulation space

Claims (7)

An actuator for driving a valve body provided to be able to open and close at least a part of the exhaust path of the vehicle;
A heat shield provided between the outer wall and the actuator, which constitutes the installation part of the valve body in the exhaust path;
Exhaust system structure with   The exhaust system structure according to claim 1, wherein the heat shield is disposed between the actuator and a power transmission unit that is disposed outside the outer wall and transmits a driving force of the actuator to the valve body. An actuator for driving a valve body provided to be able to open and close at least a part of the exhaust path of the vehicle;
A power transmission unit disposed outside the exhaust path and transmitting the driving force of the actuator to the valve body;
A heat shield provided between the power transmission unit and the actuator;
Exhaust system structure with   The exhaust system structure according to claim 2 or 3, wherein the heat shield forms a heat insulating space that covers the power transmission unit.   5. The heat shield includes a through hole that allows the output portion of the actuator to protrude toward the valve body, and the main body of the actuator is located in the through hole. The exhaust system structure according to any one of the above. The exhaust path is a bypass flow path for bypassing a heat exchanger that performs heat exchange between the exhaust gas and the refrigerant,
The exhaust system structure according to any one of claims 1 to 5, wherein the actuator is a thermostat that drives the valve body in accordance with a temperature of the refrigerant. The valve body is disposed on the upstream side or the downstream side in the flow direction of the exhaust gas with respect to the range where the refrigerant flow path of the heat exchanger is formed,
The exhaust system structure according to claim 6, wherein the heat shield includes an overhang portion positioned between the thermostat and a range where a refrigerant flow path is formed in the heat exchanger.

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