JP2011256942A - Exhaust gas flow passage valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust gas flow passage valve capable of executing leakage test relating to a main seal despite having the main seal and a dust seal.SOLUTION: The exhaust gas flow passage valve has a valve housing 12 having an exhaust gas flow passage 13 through which the exhaust gas of the internal combustion engine flows, a valve shaft 17 rotatably inserted into a shaft receiving part 21 of the valve housing 12, a valve body 18 attached to the valve shaft 17 and opening/closing the exhaust gas flow passage 13 by the rotation of the valve shaft 17, a main seal 45 arranged in the annular gap between the shaft receiving part 21 and the valve shaft 17, and the dust seal 47 arranged in the annular gap in the atmospheric side from the main seal 45. The dust seal 47 has a seal lip 52 elastically contacting with the valve shaft 17. Projections 54 contacting with the valve shaft 17 are formed in the seal lip 52.

Description

  The present invention relates to an exhaust passage valve used for switching an exhaust gas passage of an internal combustion engine, adjusting a flow rate, or the like.

As a conventional example of this type of exhaust passage valve, for example, there is a valve assembly described in Patent Document 1. The valve assembly will be described. FIG. 22 is a sectional view showing the valve assembly, and FIG. 23 is a side sectional view showing the sealing device.
As shown in FIG. 22, the valve assembly includes a housing 100 having a flow path 101 that allows the exhaust manifold and the intake manifold to communicate with each other, and a butterfly valve 200 that adjusts the cross-sectional area of the flow path 101. The butterfly valve 200 includes a valve shaft 201 that is rotatably inserted into the left and right bearing portions 103 and 104 of the housing 100, and a disk-shaped disk that is disposed in the flow path 101 and attached to the valve shaft 201. And a valve body 202. Bearings 203 and 204 for rotatably supporting the valve shaft 201 are provided in both the bearing portions 103 and 104. Further, the outer end portion of the right bearing portion 104 is closed. A lever 205 is attached to the outer end of the valve shaft 201 protruding from the left bearing portion 103 to the outside of the housing 100. When the lever 205 receives the driving force from the motor, the valve body 202 is rotated via the valve shaft 201. Thereby, the channel cross-sectional area of the channel 101 is changed.

  A sealing device 310 is provided in an annular gap between the bearings 103 and 104 of the housing 100 and the valve shaft 201 on the flow channel 101 side of the bearings 203 and 204. As shown in FIG. 23, the sealing device 310 includes an outer ring 311, an inner ring 312, and a seal lip 313. The outer ring 311 is made of metal (for example, a stainless steel plate) and is press-fitted and fixed in both the bearing portions 103 and 104. The inner ring 312 is made of metal (for example, a stainless steel plate) and is fixed by caulking to the inner periphery of the outer ring 311. The outer ring 311 and the inner ring 312 are formed with inward flange portions 311a and 312a arranged in the axial direction. Further, the seal lip 3131 is formed in an annular plate shape from PTFE (polytetrafluoroethylene) which is a fluororesin excellent in heat resistance and acid resistance. The outer diameter portion 313 a of the seal lip 313 is held between the flange portion 311 a of the outer ring 311 and the flange portion 312 a of the inner ring 312. In addition, the inner diameter portion 313b of the seal lip 313 is deformed so as to face the flow channel 101 side (see the one-dot chain line in FIG. 23) when the valve shaft 201 is inserted (see FIG. 22). Thus, the valve shaft 201 is slidably in contact with the outer peripheral surface of the valve shaft 201.

JP 2010-65729 A

  According to the conventional example, external dust on the atmosphere side enters from the annular gap between the bearing portion 103 on the left side of the housing 100 and the valve shaft 201, and the dust passes through the gap between the bearing 203 and the valve shaft 201. Thus, there is a problem that the sealing performance of the seal lip 313 is impaired by reaching between the seal lip 313 and the valve shaft 201 of the sealing device (corresponding to a “main seal” in this specification) 310.

  As a countermeasure against the above-described problem, a dust seal is provided in an annular gap on the atmosphere side of the left bearing 203 between the left bearing portion 103 of the housing 100 and the valve shaft 201 to protect the sealing device 310 from external dust. It is possible. However, in this case, since a double seal structure is obtained by assembling the sealing device 310 and the dust seal, there is a problem in that the leakage inspection for the sealing device 310 cannot be performed. That is, since the dust seal can prevent air leakage, it is not possible to check the assembly failure or breakage of the sealing device (main seal) 310, making it difficult to assure the quality of the valve assembly.

  The problem to be solved by the present invention is to provide an exhaust flow path valve capable of performing a leak test on the main seal despite having the main seal and the dust seal.

The above-mentioned subject can be solved by an exhaust passage valve having the gist of the configuration described in the claims.
That is, according to the exhaust flow path valve described in claim 1, a valve housing having an exhaust flow path through which exhaust gas of the internal combustion engine flows, a valve shaft rotatably inserted into a bearing portion of the valve housing, and a valve A valve body that is attached to the shaft and opens and closes the exhaust passage by the rotation of the valve shaft, and is provided in an annular gap between the bearing portion of the valve housing and the valve shaft, and prevents the exhaust gas from leaking to the atmosphere side. A main seal and a dust seal provided in an annular gap on the atmosphere side of the main seal and protecting the main seal from external dust, and the dust seal communicates the space on the main seal side in the annular gap with the atmosphere side It is configured to ensure air permeability. Therefore, although the main seal and the dust seal are provided, it is possible to perform a leak inspection on the main seal due to the air permeability ensured by the dust seal.

  Further, according to the exhaust flow path valve described in claim 2, the dust seal includes the seal lip that elastically contacts the valve shaft, and the seal lip ensures air permeability by contacting the valve shaft. A protrusion is formed. Accordingly, the seal lip provided in the dust seal elastically contacts the valve shaft, and the protrusion formed on the seal lip contacts the valve shaft. Thereby, since the peripheral part of the protrusion in the seal lip is separated from the valve shaft, the air permeability for communicating the space part on the main seal side and the atmosphere side in the annular gap can be ensured.

  According to the exhaust flow path valve described in claim 3, the dust seal is fitted into the bearing portion of the valve housing by press fitting, and a ventilation groove for ensuring air permeability is formed on the outer peripheral surface of the dust seal. . Therefore, the ventilation groove | channel formed in the outer peripheral surface of a dust seal can ensure the air permeability for connecting the space part by the side of the main seal in an annular clearance, and the atmosphere side.

  According to the exhaust flow path valve described in claim 4, the ventilation groove of the dust seal is formed in a maze shape. Therefore, it becomes difficult for the external dust to pass through the ventilation groove of the dust seal, so that the dust resistance of the dust seal can be improved.

  According to the exhaust flow path valve described in claim 5, the dust seal is formed with a vent hole for ensuring air permeability by penetrating in the axial direction. Therefore, the air permeability for communicating the space portion on the main seal side in the annular gap and the atmosphere side can be ensured by the vent hole formed in the dust seal and penetrating in the axial direction.

  According to the exhaust flow path valve of the sixth aspect, the vent hole of the dust seal is closed with the vent plug formed of the fiber material having air permeability. Therefore, the external dust is captured by the fiber material of the vent plug, so that the dust resistance of the dust seal can be improved.

  Further, according to the exhaust flow path valve described in claim 7, the dust seal includes a seal lip formed of a fiber material having air permeability for elastically contacting the valve shaft and ensuring air permeability. Yes. Therefore, the seal lip formed by the air-permeable fiber material provided for the dust seal elastically contacts the valve shaft. Accordingly, the air permeability of the sealing lip fiber material ensures air permeability for communicating the main seal side space in the annular gap with the atmosphere side, and external dust is captured by the seal lip fiber material. As a result, the dust resistance of the dust seal can be improved.

  According to the exhaust flow path valve recited in claim 8, the dust seal includes a seal lip that elastically contacts the valve shaft, and the seal lip is formed with a concave groove for ensuring air permeability. . Therefore, the seal lip provided in the dust seal elastically contacts the valve shaft, and the concave groove formed in the seal lip provides air permeability for communicating the space portion on the main seal side and the atmosphere side in the annular gap. Can be secured.

It is a front view which shows the EGR cooler bypass valve concerning one Embodiment. It is a side view which shows a partially broken EGR cooler bypass valve. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 1. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 1. FIG. 5 is a cross-sectional view taken along line VV in FIG. 1. It is sectional drawing which shows the VI section of FIG. It is a sectional side view which shows a dust seal. It is sectional drawing which shows an air passage. It is a sectional side view which shows the example 1 of a change of a dust seal. It is a sectional side view which shows the modification 2 of a dust seal. It is a sectional side view which shows the modification 3 of a dust seal. It is a front view which shows a dust seal. It is a front view which shows partially another example of the ventilation groove | channel of a dust seal. It is a side view which shows the modification 4 of a dust seal. It is the side view which looked at the dust seal from the paper surface back side of FIG. It is a side view which shows the modification 5 of a dust seal. It is the side view which looked at the dust seal from the paper back side of FIG. It is a sectional side view which shows the modification 6 of a dust seal. It is a sectional side view which shows the modification 7 of a dust seal. It is a sectional side view which shows the modification 8 of a dust seal. It is a sectional side view which shows the modification 9 of a dust seal. It is sectional drawing which shows the valve assembly concerning a prior art example. It is a sectional side view which shows a sealing device.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  An embodiment of the present invention will be described. In the present embodiment, an EGR cooler bypass valve used in an EGR device with an EGR cooler of an EGR device (exhaust gas recirculation device) provided in an internal combustion engine is exemplified as the exhaust flow path valve. The EGR cooler bypass valve is for switching between a state in which exhaust gas (EGR gas) flows to the EGR cooler and a state in which the EGR cooler is bypassed. 1 is a front view showing an EGR cooler bypass valve, FIG. 2 is a partially cutaway side view, FIG. 3 is a sectional view taken along line III-III in FIG. 1, and FIG. 4 is a line IV-IV in FIG. 5 is a cross-sectional view taken along the line V-V in FIG. 1, and FIG. 6 is a cross-sectional view showing a VI portion in FIG. 3. In the present specification, the left and right and up and down directions of the EGR cooler bypass valve are determined with reference to the front view of FIG.

  As shown in FIG. 1, the EGR cooler bypass valve 10 includes a valve housing 12. The valve housing 12 is formed with a first exhaust passage 13 and a second exhaust passage 14 arranged side by side (see FIG. 3). Both exhaust passages 13 and 14 pass through the valve housing 12 in the front-rear direction (the front and back direction in FIG. 1 and the vertical direction in FIG. 3). Further, the valve housing 12 is formed with a series of valve shaft insertion holes (reference numerals omitted) penetrating in a direction orthogonal to the center line of both the exhaust passages 13 and 14, that is, in the left-right direction. The valve shaft 17 is inserted through the valve shaft insertion hole in a state of crossing both the exhaust passages 13 and 14. A plate-like first valve body 18 that opens and closes the first exhaust passage 13 and a plate-like second valve body 19 that opens and closes the second exhaust passage 14 are attached to the valve shaft 17 by screwing. Yes. A butterfly valve 16 is constituted by the valve shaft 17 and the valve bodies 18 and 19.

  The valve bodies 18 and 19 open and close the exhaust passages 13 and 14 in a reciprocal manner by the rotation of the valve shaft 17. That is, when the first valve body 18 is closed (see the solid line 18 in FIG. 4), the second valve body 19 is opened (see the solid line 19 in FIG. 5). Conversely, when the first valve body 18 is opened (see the two-dot chain line 18 in FIG. 4), the second valve body 19 is closed (see the two-dot chain line 19 in FIG. 5).

  As shown in FIG. 3, in the valve housing 12, wall portions forming valve shaft insertion holes corresponding to both end portions of the valve shaft 17 are bearing portions 21 and 22, respectively. A valve shaft 17 is rotatably supported in both bearing portions 21 and 22 via left and right bearings 24 and 25. For example, sliding bearings (bushings) are used as the bearings 24 and 25. The opening end of the right bearing 22 is closed by a plug 26. Further, the left end portion of the valve shaft 17 penetrates the left bearing portion 21 and protrudes to the outside of the valve housing 12. Further, one end of a lever 28 is fixedly attached to the protruding end of the left end of the valve shaft 17 (see FIG. 2). Further, a positioning member 30 is engaged with an annular groove 29 formed on the outer peripheral surface of the valve shaft 17 so as to be relatively rotatable in a state of being positioned in the axial direction (see FIG. 6). The positioning member 30 is attached to the outer end portion of the left bearing portion 21. Thereby, the movement of the valve shaft 17 in the thrust direction (axial direction) is restricted. A seal structure provided between the valve housing 12 and the valve shaft 17 will be described later.

  As shown in FIG. 1, a diaphragm type actuator 32 for driving, that is, rotating the valve shaft 17 is disposed on the left side of the valve housing 12. An actuator body 33 of the actuator 32 is supported on the left side surface of the valve housing 12 via a bracket 34. As shown in FIG. 2, the actuator body 33 is partitioned into two front and rear chambers by a diaphragm 35. The front chamber is open to the atmosphere as an air chamber 36. The rear chamber is a negative pressure chamber 37 to which a negative pressure is applied via a negative pressure pipe 38 of the actuator body 33. The diaphragm 35 is always urged forward by a spring 39.

  The actuator 32 includes an output shaft 40 that moves forward and backward in the axial direction in conjunction with the diaphragm 35. The output shaft 40 protrudes forward from the actuator body 33. A tip end portion of the lever 28 is rotatably connected to a tip end portion (front end portion) of the output shaft 40 via a pin 42. Therefore, when a negative pressure is applied to the negative pressure chamber 37, the output shaft 40 is retracted to the backward retracted position against the biasing force of the spring 39, and when the negative pressure is purged, the output shaft 40 is moved to the spring. The urging force of 39 advances to the forward advance position. As the output shaft 40 moves, the valve shaft 17 is rotated via the lever 28. As a result, the first exhaust passage 13 and the second exhaust passage 14 of the valve housing 12 are selectively opened and closed. The actuator 32 is not limited to a diaphragm actuator, and an electric actuator such as an electric motor or an electromagnetic solenoid can be used.

  In the EGR cooler bypass valve 10, the first exhaust passage 13 communicates with a bypass passage through which exhaust gas (EGR gas) in an EGR device with an EGR cooler (not shown) bypasses the EGR cooler. The second exhaust flow path 14 is communicated with a cooler flow path through which exhaust gas (EGR gas) in the EGR device flows to the EGR cooler. The negative pressure acting on the negative pressure chamber 37 of the actuator 32 is controlled by a negative pressure control device (not shown). The negative pressure control device applies a negative pressure to the negative pressure chamber 37 of the actuator 32 at the time of engine start or cold, for example, when the cooling water temperature of the internal combustion engine is low, and the cooling water temperature has risen above a predetermined temperature. Sometimes, the negative pressure chamber 37 of the actuator 32 is opened to the atmosphere.

  Accordingly, when the engine is started or cold, a negative pressure is applied to the negative pressure chamber 37 of the actuator 32, whereby the output shaft 40 is retracted to the retracted position against the urging force of the spring 39. Accordingly, the valve shaft 17 is rotated in the forward direction (clockwise direction in FIGS. 4 and 5) via the lever 28, so that the first valve body 18 is opened (in FIG. The second valve element 19 is closed (see the two-dot chain line 19 in FIG. 5) at the dotted line 18). In this state, the exhaust gas (EGR gas) of the internal combustion engine is recirculated to the intake passage through the bypass passage.

  When the cooling water temperature of the internal combustion engine rises above a predetermined temperature, the negative pressure chamber 37 of the actuator 32 is opened to the atmosphere, so that the output shaft 40 advances to the advanced position by the biasing force of the spring 39. Is done. Accordingly, the valve shaft 17 is rotated in the reverse direction (counterclockwise in FIGS. 4 and 5) via the lever 28, so that the first valve body 18 is closed (the solid line in FIG. 4). 18), the second valve body 19 is opened (see the solid line 19 in FIG. 4). In this state, the exhaust gas (EGR gas) of the internal combustion engine passes through the cooler passage so that it is cooled by the EGR cooler and then recirculated to the intake passage.

Next, a seal structure provided between the valve housing 12 and the valve shaft 17 will be described.
As shown in FIG. 3, between the bearings 21 and 22 of the valve housing 12 and both ends of the valve shaft 17, the annular clearances on the exhaust passages 13 and 14 side of the bearings 24 and 25 are in the main gap. A seal 45 is provided. Since the main seal 45 has the same configuration as the sealing device 310 (see FIG. 23) described in the prior art, the description thereof is omitted. Further, since the opening end portion of the right bearing portion 22 is closed by the plug 26, the external dust on the atmosphere side does not enter the annular gap between the bearing portion 22 and the valve shaft 17, The sealing performance of the seal lip 313 by external dust is not impaired.

  By the way, the main seal 45 provided in the annular clearance between the left bearing portion 21 and the valve shaft 17 is exhaust gas (EGR gas), particularly soot, condensed water, unburned matter contained in the exhaust gas. Etc.) is prevented from leaking to the atmosphere side. Further, external dust on the atmosphere side enters the annular gap between the left bearing portion 21 and the valve shaft 17, and the external dust reaches between the seal lip 313 of the main seal 45 and the valve shaft 17, The sealing performance of the seal lip 313 may be impaired. Therefore, a dust seal 47 is provided in the annular gap on the atmosphere side of the bearing 24 between the left bearing portion 21 and the valve shaft 17 in order to protect the main seal 45 from external dust (see FIG. 6). .

Next, the dust seal 47 will be described. FIG. 7 is a side sectional view showing the dust seal.
As shown in FIG. 7, the dust seal 47 integrally includes a reinforcing ring 48 and a seal body 50. The reinforcing ring 48 is a metal annular member. The reinforcing ring 48 is formed in an L-shaped cross section having a cylindrical cylindrical portion 48a and a flange portion 48b bent radially inward from one end portion (right end portion in FIG. 7) of the cylindrical portion 48a. . The seal body 50 is made of a rubber-like elastic material, and has an annular mounting portion 51 that entirely covers the reinforcing ring 48, and a seal lip 52 that is integrally formed on the inner peripheral portion of the mounting portion 51. Yes.

  The seal lip 52 has a conical cylindrical shape extending obliquely inward in the radial direction from the flange portion 48b side of the reinforcing ring 48 toward the other end portion side (left side in FIG. 7) in the inner peripheral portion of the mounting portion 51. Is formed. For example, six (54 are shown in FIG. 7) protrusions 54 are formed at equal intervals in the circumferential direction on the inner peripheral surface of the seal lip 52, specifically, the slope on the atmosphere side facing the valve shaft 17. The protrusion 54 has a right-angled triangular cross section in the circumferential direction of the seal lip 52. The long side of the protrusion 54 is arranged on the base side of the seal lip 52, and the short side is arranged on the tip side. Note that the number of the protrusions 54 is not limited to six, and at least one protrusion may be formed, and a plurality of protrusions 54 are formed at equal intervals in the circumferential direction of the seal lip 52 in consideration of balance as in the present embodiment. It is desirable. Further, the shape, size, protrusion amount, and arrangement position of the protrusion 54 are not particularly limited and can be set as appropriate.

  As shown in FIG. 6, when the dust seal 47 is mounted in the annular gap between the left bearing portion 21 of the valve housing 12 and the valve shaft 17, the outer peripheral portion of the mounting portion 51 of the seal body 50 is The bearing portion 21 is elastically pressed into the inner peripheral surface of the bearing portion 21 with a predetermined tightening allowance. Further, the seal lip 52 is brought into contact with the outer peripheral surface of the valve shaft 17 so as to be elastically slidable with a predetermined tightening margin and relatively slidable in the circumferential direction. As a result, the top of the protrusion 54 comes into slidable contact with the outer peripheral surface of the valve shaft 17. As a result, as shown in FIG. 8, the peripheral portion of the protrusion 54 in the seal lip 52 is separated from the valve shaft 17, so that a clearance 55 having a triangular cross section surrounded by the seal lip 52, the valve shaft 17, and the protrusion 54. Is formed. The clearance 55 can ensure air permeability that communicates the space portion on the main seal side and the atmosphere side in the annular clearance.

  According to the EGR cooler bypass valve 10 described above, a main seal 45 provided in an annular gap between the bearing portion 21 of the valve housing 12 and the valve shaft 17 and preventing leakage of exhaust gas to the atmosphere, and the main seal 45 The dust seal 47 is provided in an annular gap on the atmosphere side and protects the main seal 45 from external dust, and the dust seal 47 is air permeable to communicate the space portion on the main seal side in the annular gap and the atmosphere side. It is set as the structure which ensures. Therefore, although the main seal 45 and the dust seal 47 are provided, the leak inspection on the main seal 45 can be performed by the air permeability ensured by the dust seal 47.

  The leak inspection of the main seal 45 is performed by applying air to the exhaust passages 13 and 14 with the open end faces of the exhaust passages 13 and 14 closed, for example, and leaking air from the left bearing portion 21. This is done by judging whether or not there is. At this time, if the air does not leak, it can be confirmed that the main seal 45 is not properly assembled and damaged, and the main seal 45 is in a properly mounted state. In addition, when air leaks, it is found that the main seal 45 is in a state of poor assembly, breakage, or the like.

  The dust seal 47 includes a seal lip 52 that elastically contacts the valve shaft 17, and a protrusion 54 is formed on the seal lip 52 to ensure air permeability by contacting the valve shaft 17 (see FIG. 7). Accordingly, the seal lip 52 provided in the dust seal 47 elastically contacts the valve shaft 17 and the protrusion 54 formed on the seal lip 52 contacts the valve shaft 17 (see FIG. 8). Thereby, since the peripheral part of the protrusion 54 in the seal lip 52 is separated from the valve shaft 17, the air permeability, that is, the gap 55 for communicating the space portion on the main seal side and the atmosphere side in the annular gap can be secured. .

Next, a modified example of the dust seal 47 will be described. In addition, since each modified example adds the change to the dust seal 47 in the said embodiment, the changed part is demonstrated and the overlapping description is abbreviate | omitted.
[Modification 1]
A first modification of the dust seal 47 will be described. FIG. 9 is a side sectional view showing the dust seal.
As shown in FIG. 9, in this modified example, a seal lip 58 is formed on the inner peripheral portion of the mounting portion 51 of the seal body 50. The seal lip 58 is formed in a conical cylindrical shape extending obliquely inward in the radial direction from the flange portion 48b side of the reinforcing ring 48 in the inner peripheral portion of the mounting portion 51 toward the side opposite to the atmosphere side (right side in FIG. 9). ing. On the inner peripheral surface of the seal lip 58 (specifically, the surface facing the valve shaft 17), for example, twelve (three are shown in FIG. 9) projections 54 (the same reference numerals as those in the above embodiment) are provided. They are formed at predetermined intervals in the circumferential direction. An annular recess 59 that is continuous in the circumferential direction is formed on the end surface (the right end surface in FIG. 9) opposite to the atmosphere side of the mounting portion 51.

  The seal lip 58 is brought into contact with the outer peripheral surface of the valve shaft 17 so as to be elastically slidable in a circumferential direction with a predetermined allowance. Accordingly, the top of the projection 54 of the seal lip 58 is slidably in contact with the outer peripheral surface of the valve shaft 17, so that the peripheral portion of the projection 54 of the seal lip 58 is the valve as in the above-described embodiment. Since it is separated from the shaft 17, air permeability for communicating the space portion on the main seal side and the atmosphere side in the annular gap can be ensured.

[Modification 2]
A second modification of the dust seal 47 will be described. In this modified example, the dust seal 47 in the modified example 1 (see FIG. 9) is modified. FIG. 10 is a side sectional view showing the dust seal.
As shown in FIG. 10, in this modified example, the seal lip 58 in the modified example 1 (see FIG. 9) is omitted, and a seal lip 60 is formed on the inner peripheral portion of the mounting portion 51 of the seal body 50. . The seal lip 60 is formed in a cylindrical shape extending from the flange portion 48b side of the reinforcing ring 48 toward the other end portion side (left side in FIG. 10) in the inner peripheral portion of the mounting portion 51. Then, on the inner peripheral surface of the seal lip 60, a slope 61 on the tip side (left side in FIG. 10) facing the valve shaft 17 and a base end side (FIG. 10) symmetrical with respect to the slope 61 in the axial direction. The right slope surface 62 is formed to have a mountain shape in cross section. For example, twelve (three are shown in FIG. 9) projections 54 (the same reference numerals as those in the above embodiment) are formed on the tip-side inclined surface 61 at predetermined intervals in the circumferential direction.

  The tops of the both inclined surfaces 61 and 62 of the seal lip 60 are brought into contact with the outer peripheral surface of the valve shaft 17 so as to be elastically slidable in the circumferential direction with a predetermined allowance. Accordingly, the top of the projection 54 of the seal lip 60 is slidably in contact with the outer peripheral surface of the valve shaft 17, so that the peripheral portion of the projection 54 of the seal lip 60 is the valve as in the above embodiment. Since it is separated from the shaft 17, air permeability for communicating the space portion on the main seal side and the atmosphere side in the annular gap can be ensured.

[Modification 3]
Modification 3 of the dust seal 47 will be described. In this modified example, the dust seal 47 in the modified example 2 (see FIG. 10) is modified. FIG. 11 is a side sectional view showing the dust seal, and FIG. 12 is a front view of the same (viewed from the right side of FIG. 11).
As shown in FIGS. 11 and 12, in this modified example, the protrusion 54 on the seal lip 60 in the modified example 2 (see FIG. 10) is omitted. In addition, a seal lip 58 (same as that in the first modification) is formed on the inner peripheral portion of the mounting portion 51 of the seal body 50 in the same manner as the seal lip 58 in the first modification (see FIG. 9). . In addition, the protrusion 54 in the seal lip 58 in the modified example 1 (see FIG. 9) is omitted.

  Two ventilation grooves 64 penetrating in the axial direction are formed at equal intervals in the circumferential direction on the outer peripheral surface of the mounting portion 51 of the seal body 50. The ventilation groove 64 has a quadrangular cross section. Therefore, the ventilation groove 64 formed on the outer peripheral surface of the mounting portion 51 of the seal body 50 of the dust seal 47 can ensure the air permeability for communicating the space portion on the main seal side and the atmosphere side in the annular gap. .

  Note that the number of ventilation grooves 64 is not limited to two, and it is sufficient that at least one ventilation groove 64 is formed. In consideration of balance as in the present embodiment, the circumferential direction of the mounting portion 51 of the seal body 50 is equally spaced. It is desirable to form a plurality. Further, the shape, size, protrusion amount, and arrangement position of the ventilation groove 64 are not particularly limited, and can be set as appropriate. Further, the ventilation groove 64 can be changed to a V-shaped ventilation groove 65 as shown in FIG.

[Modification 4]
Modification 4 of the dust seal 47 will be described. This modified example is obtained by modifying the dust seal 47 in the modified example 3 (see FIGS. 11 and 12). 14 is a side view showing the dust seal, and FIG. 15 is a side view of the dust seal as viewed from the back side of the paper of FIG.
As shown in FIG. 14, the present modification example includes an atmosphere side groove portion 64 a that opens to the atmosphere side by dividing the ventilation groove 64 of the modification example 3 (see FIGS. 11 and 12) in the axial direction of the dust seal 47. A main seal side groove 64b that is open on the opposite side to the atmosphere side is formed. Opposing end portions of the atmosphere side groove portion 64a and the main seal side groove portion 64b communicate with each other through a circumferential groove portion 64c (see FIG. 15) formed in a C-shape in the circumferential direction along the outer peripheral surface. That is, the ventilation groove 64 of the dust seal 47 is formed in a labyrinth shape having an atmosphere side groove 64a, a main seal side groove 64b, and a circumferential groove 64c. Accordingly, the dust resistance of the dust seal 47 can be improved by making it difficult for external dust to pass through the ventilation groove 64 of the dust seal 47.

[Modification 5]
Modification 5 of the dust seal 47 will be described. In this modification, the dust seal 47 in Modification 4 (see FIGS. 14 and 15) is modified. 16 is a side view showing the dust seal, and FIG. 17 is a side view of the dust seal as viewed from the back side of the paper of FIG.
As shown in FIGS. 16 and 17, this modified example is one in which the circumferential groove portion (reference numeral 64 d) in the ventilation groove 64 of the modified example 4 (see FIGS. 14 and 15) is formed in a square wave shape. is there. Therefore, the external dust is more difficult to pass through the circumferential groove portion 64d in the ventilation groove 64 of the dust seal 47, so that the dust resistance of the dust seal 47 can be improved. The circumferential groove 64d can be appropriately changed to a triangular wave shape, a sine wave shape or the like in addition to a square wave shape.

[Modification 6]
Modification 6 of the dust seal 47 will be described. This modified example is obtained by modifying the dust seal 47 in the modified example 3 (see FIGS. 11 and 12). FIG. 18 is a side sectional view showing the dust seal.
As shown in FIG. 18, in this modified example, the ventilation groove 64 in the mounting portion 51 of the seal body 50 of the modified example 3 (see FIG. 11) is omitted. Further, a vent hole 66 penetrating in the axial direction (left-right direction in FIG. 18) is formed in the mounting portion 51 of the seal body 50. The vent 66 passes through the flange portion 48 b of the reinforcing ring 48 and is opened in the annular recess 59. Therefore, the ventilation hole 66 which penetrates in the axial direction formed in the dust seal 47 can ensure air permeability for communicating the space portion on the main seal side and the atmosphere side in the annular gap.

[Modification 7]
Modification Example 7 of the dust seal 47 will be described. In this modified example, the dust seal 47 in the modified example 6 (see FIG. 18) is modified. FIG. 19 is a side sectional view showing the dust seal.
As shown in FIG. 19, in this modified example, the vent hole 66 of the modified example 6 (see FIG. 18) is closed with a vent plug 68. The vent plug 68 is made of a fiber material having air permeability. Accordingly, the external dust is captured by the fiber material of the vent plug 68, whereby the dust resistance of the dust seal 47 can be improved. In addition, as a fiber material of the vent plug 68, for example, a columnar felt-like material formed by compressing fibers can be used.

[Modification 8]
Modification 8 of the dust seal 47 will be described. In this modified example, the dust seal 47 in the modified example 1 (see FIG. 9) is modified. FIG. 20 is a side sectional view showing the dust seal.
As shown in FIG. 20, in this modified example, the seal lip 58 in the modified example 1 (see FIG. 9) is omitted. Further, an outer periphery of an annular plate-like seal lip 70 formed of a breathable fiber material is provided on the end surface of the inner peripheral portion of the mounting portion 51 of the seal body 50 opposite to the atmosphere side (right side in FIG. 20). The part is installed. The inner peripheral portion of the seal lip 70 is in elastic contact with the outer peripheral surface of the valve shaft 17. The air permeability of the fiber material of the seal lip 70 ensures air permeability for communication between the space portion on the main seal side in the annular gap and the atmosphere side, and external dust is captured by the fiber material of the seal lip 70. Thus, the dust resistance of the dust seal 47 can be improved. In addition, as the fiber material of the seal lip 70, for example, a felt-like material formed by compressing fibers can be used.

[Modification 9]
Modification 9 of the dust seal 47 will be described. FIG. 21 is a side sectional view showing the dust seal.
As shown in FIG. 21, in this modified example, the protrusion 54 on the seal lip 52 of the embodiment (see FIG. 7) is omitted. Further, for example, four (two are shown in FIG. 21) concave grooves 72 are formed in the distal end portion of the seal lip 52 at predetermined intervals in the circumferential direction. The concave groove 72 has, for example, a square groove shape. Therefore, the concave groove 72 formed in the seal lip 52 can ensure air permeability for communicating the space portion on the main seal side in the annular gap with the atmosphere side. Note that the number of the concave grooves 72 is not limited to four, and at least one concave groove 72 may be formed, and a plurality of concave grooves 72 are desirably formed at equal intervals in the circumferential direction of the seal lip 52 in consideration of balance. Further, the shape, size, and arrangement position of the groove 72 are not particularly limited, and can be set as appropriate.

  The present invention is not limited to the embodiment described above, and can be modified without departing from the gist of the present invention. For example, the exhaust passage valve of the present invention is not limited to the EGR cooler bypass valve 10 but can be applied to an exhaust system valve of an internal combustion engine, for example, an exhaust brake valve of an automobile. Further, the technical elements described in the embodiment and the modification examples can be combined. Further, the main seal 45 is not limited to the one in the above embodiment, and can be changed as appropriate. Further, the atmosphere side and the main seal side opposite to the atmosphere side in the dust seal 47 described in the embodiment and the modified example are not limited to the downward direction, and can be arranged in the opposite direction. It is.

10 ... EGR cooler bypass valve (exhaust flow path valve)
DESCRIPTION OF SYMBOLS 12 ... Valve housing 13, 14 ... Exhaust flow path 17 ... Valve shaft 18, 19 ... Valve body 21,22 ... Bearing part 45 ... Main seal 47 ... Dust seal 50 ... Seal main body 51 ... Mounting part 52 ... Seal lip 54 ... Projection 64 ... ventilation groove 66 ... ventilation hole 68 ... vent plug 70 ... seal lip 72 ... concave groove

Claims (8)

A valve housing having an exhaust passage through which exhaust gas of the internal combustion engine flows;
A valve shaft rotatably inserted into the bearing portion of the valve housing;
A valve body attached to the valve shaft and opening and closing the exhaust passage by rotation of the valve shaft;
A main seal provided in an annular gap between the bearing portion of the valve housing and the valve shaft and preventing leakage of the exhaust gas to the atmosphere;
A dust seal provided in the annular gap on the atmosphere side of the main seal and protecting the main seal from external dust,
The exhaust seal valve according to claim 1, wherein the dust seal is configured to ensure air permeability for communicating the space portion on the main seal side and the atmosphere side in the annular gap. The exhaust passage valve according to claim 1,
The dust seal includes a seal lip that elastically contacts the valve shaft,
An exhaust flow path valve characterized in that a protrusion for ensuring the air permeability is formed on the seal lip by contacting the valve shaft. The exhaust passage valve according to claim 1,
The dust seal is mounted by press-fitting into the bearing portion of the valve housing,
An exhaust passage valve characterized in that a ventilation groove for ensuring the air permeability is formed on the outer peripheral surface of the dust seal. The exhaust passage valve according to claim 3,
The exhaust passage valve according to claim 1, wherein the ventilation groove of the dust seal is formed in a maze shape. The exhaust passage valve according to claim 1,
An exhaust passage valve characterized in that a vent hole is formed in the dust seal to ensure the air permeability by penetrating in an axial direction. The exhaust passage valve according to claim 5,
An exhaust passage valve characterized in that a vent hole of the dust seal is closed with a vent plug formed of a fiber material having air permeability. The exhaust passage valve according to claim 1,
2. The exhaust flow path valve according to claim 1, wherein the dust seal includes a seal lip formed of a fiber material having air permeability for elastically contacting the valve shaft and ensuring the air permeability. The exhaust passage valve according to claim 1,
The dust seal includes a seal lip that elastically contacts the valve shaft,
An exhaust passage valve characterized in that a concave groove for ensuring the air permeability is formed in the seal lip.

Images