Valve gear

Abstract

To remove deposits.SOLUTION: A valve gear includes: a valve seat having a through hole; a valve body which may open or close relative to the valve seat; a valve stem supporting the valve body; an opening / closing device which is configured to move the valve stem in an axial direction and opens or closes the valve body relative to the valve seat by movement of the valve stem; a rotation device which is configured to be able to rotate the valve stem in a circumferential direction in conjunction with the opening / closing device moving the valve stem and rotates the valve body through rotation of the valve stem; and a brush which is fixed to the valve body so that a tip part contacts with the valve seat in a state that the valve body is closed relative to the valve seat.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a valve device. [Background technology]

[0002] For example, Patent Document 1 discloses an electromagnetically driven valve having a valve body that functions as an intake valve or an exhaust valve for an engine. In Patent Document 1, the valve body rotates around its axis as it moves toward the valve seat, and deposits are crushed between the valve body and the valve seat. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-320311 Summary of the Invention [Problem to be solved by the invention]

[0004] The technology of Patent Document 1 can crush deposits between the valve body and the valve seat, but cannot remove the deposits from the valve seat.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a valve device that is capable of removing deposits. [Means for solving the problem]

[0006] In order to solve the above problem, a valve device according to one embodiment of the present invention comprises: a valve seat having a through hole; a valve body that can be opened and closed relative to the valve seat; a valve stem supporting the valve body; an opening and closing device configured to move the valve stem in an axial direction and opening and closing the valve element relative to the valve seat by the movement of the valve stem; a rotation device configured to rotate the valve shaft in a circumferential direction in accordance with the movement of the valve shaft by the opening and closing device, and to rotate the valve body by the rotation of the valve shaft; a brush fixed to the valve body so that a tip portion thereof abuts against the valve seat when the valve body is in a closed state relative to the valve seat; Equipped with. [Effects of the Invention]

[0007] According to the present invention, it is possible to remove deposits. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing an example of the configuration of an engine system according to this embodiment. [Figure 2] FIG. 2 is a partially enlarged view showing the periphery of the brush when the valve disc is in a closed state relative to the valve seat. [Figure 3] FIG. 3 is a partially enlarged view showing the periphery of the brush when the valve disc is in an open state relative to the valve seat. [Figure 4] FIG. 4 is a plan view of the valve seat when viewed from the exhaust passage side. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Specific dimensions, materials, numerical values, etc. shown in the embodiments are merely examples for facilitating understanding of the invention and do not limit the present invention unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present invention are not shown.

[0010] 1 is a schematic diagram showing an example of the configuration of an engine system 1 according to this embodiment. The engine system 1 is mounted on, for example, a vehicle 2. The engine system 1 includes an engine 10, an intake passage 12, an exhaust passage 14, an EGR passage 16, a valve device 20, and a control device 22. EGR stands for Exhaust Gas Recirculation.

[0011] The engine 10 is, for example, a reciprocating engine, and generates driving force by burning a mixture containing fuel and air. The generated driving force is transmitted to the wheels of the vehicle 2, for example.

[0012] The intake flow path 12 is configured to allow a fluid to flow therethrough. An intake port 30 is provided at one end of the intake flow path 12. The other end of the intake flow path 12 is connected to the engine 10. Air is introduced into the intake flow path 12 through the intake port 30. The air introduced into the intake flow path 12 flows through the intake flow path 12 and is supplied to the engine 10.

[0013] The exhaust flow path 14 is configured to allow a fluid to flow through it. One end of the exhaust flow path 14 is connected to the engine 10. An exhaust port 32 is provided at the other end of the exhaust flow path 14. The engine 10 discharges gas produced by the combustion of the air-fuel mixture into the exhaust flow path 14 as exhaust gas. The exhaust gas discharged from the engine 10 into the exhaust flow path 14 flows through the exhaust flow path 14. Although not shown, a purification device that purifies the exhaust gas is provided in the exhaust flow path 14. The exhaust gas flowing through the exhaust flow path 14 is purified by the purification device. The purified exhaust gas is discharged to the outside through the exhaust port 32.

[0014] The EGR passage 16 is configured to allow a fluid to flow through it. One end of the EGR passage 16 is connected to the exhaust passage 14. The other end of the EGR passage 16 is connected to the intake passage 12. A portion of the exhaust gas discharged from the engine 10 via the exhaust passage 14 is introduced into the EGR passage 16. The exhaust gas introduced into the EGR passage 16 flows through the EGR passage 16 and is introduced into the intake passage 12. In other words, the EGR passage 16 recirculates a portion of the exhaust gas into the intake passage 12.

[0015] The valve device 20 is, for example, an EGR valve. The EGR valve is provided in the EGR flow path 16. The valve device 20 will be described in detail later.

[0016] The control device 22 has one or more processors 40 and one or more memories 42 connected to the processors 40. The memory 42 includes a ROM in which programs and the like are stored and a RAM as a work area. The processor 40 controls each part of the engine system 1 in cooperation with the programs stored in the memory 42. For example, the processor 40 functions as an engine control unit 50 and a valve control unit 52 by executing the programs.

[0017] The engine control unit 50 controls the state of the engine 10, such as starting, driving, and stopping, and the engine speed. The valve control unit 52 controls the opening and closing of an EGR valve, which is an example of the valve device 20, in accordance with the state, speed, etc. of the engine 10. The valve control unit 52 also initializes the valve device 20 when the engine 10 is started. The initialization is a process of calibrating the position of a valve element 62 of the valve device 20 by opening and closing the valve element 62, which will be described later, one or more times.

[0018] The following describes an EGR valve as an example of the valve device 20 of this embodiment. Note that the valve device 20 of this embodiment is not limited to an EGR valve, and can be applied to, for example, various valves in which deposits are expected to accumulate on a valve seat 60 (described later).

[0019] Hereinafter, for ease of explanation, the upstream side of the flow of fluid passing through a through-hole 80 (described later) with respect to the valve device 20, i.e., the upstream side of the flow of exhaust gas passing through the EGR flow path 16, may be referred to as the primary side. Also, the downstream side of the flow of fluid passing through a through-hole 80 (described later) with respect to the valve device 20, i.e., the downstream side of the flow of exhaust gas passing through the EGR flow path 16, may be referred to as the secondary side. In the EGR flow path 16, exhaust gas flows from the exhaust flow path 14 side to the intake flow path 12 side, so the exhaust flow path 14 side of the EGR flow path 16 corresponds to the primary side, and the intake flow path 12 side of the EGR flow path 16 corresponds to the secondary side.

[0020] The valve device 20 (valve) includes a valve seat 60 (valve seat), a valve body 62 (disk), a valve shaft 64 (stem), an opening / closing device 66, a rotating device 68, and a brush 70.

[0021] The valve seat 60 and the valve element 62 are provided, for example, in the EGR flow path 16. The valve seat 60 is formed, for example, in an annular shape with a through-hole 80 in the center. The valve element 62 is formed, for example, in a disk shape. The valve shaft 64 is formed, for example, in a rod shape. One end of the valve shaft 64 is connected to the center of one surface of the valve element 62. The valve shaft 64 supports the valve element 62. The valve seat 60, the valve element 62, and the valve shaft 64 are concentrically arranged so that the valve seat 60 is located on the outer periphery of the valve element 62.

[0022] The valve body 62 has a flange portion 86 at a tip end 84 opposite to a base end 82 to which the valve stem 64 is connected in the valve body 62. The flange portion 86 protrudes radially outward relative to the portion of the valve body 62 other than the flange portion 86.

[0023] The diameter of the flange portion 86 of the valve body 62 is larger than the diameter of the through-hole 80 of the valve seat 60. The diameter of the valve body 62 other than the flange portion 86 is smaller than the diameter of the through-hole 80 of the valve seat 60. The flange portion 86 of the valve body 62 abuts against the valve seat 60.

[0024] The portion of the valve seat 60 that contacts the valve element 62 faces the primary side. The flange portion 86 of the valve element 62 that contacts the valve seat 60 is located on the primary side of the valve seat 60.

[0025] The valve element 62 is capable of opening and closing a through-hole 80 in the valve seat 60. When the valve element 62 is in an open state relative to the valve seat 60, that is, when the valve element 62 is separated from the valve seat 60 and the through-hole 80 is open, exhaust gas is recirculated to the intake passage 12 through the EGR passage 16. When the valve element 62 is in a closed state relative to the valve seat 60, that is, when the flange portion 86 of the valve element 62 abuts against the valve seat 60 and the through-hole 80 is closed by the valve element 62, the recirculation of exhaust gas through the EGR passage 16 is blocked.

[0026] The opening and closing device 66 is provided at the end of the valve shaft 64 opposite to the valve element 62. The opening and closing device 66 is configured to be able to move the valve shaft 64 in the axial direction. The opening and closing device 66 is able to open and close the valve element 62 relative to the valve seat 60 by moving the valve shaft 64.

[0027] The opening and closing device 66 may include, for example, a spring and an electromagnetic coil. The spring exerts a biasing force to move the valve stem 64 in the axial direction away from the opening and closing device 66. When a current flows through the electromagnetic coil, it functions as an electromagnet and attracts the valve stem 64 against the biasing force of the spring, moving the valve stem 64 in the axial direction toward the opening and closing device 66. Note that the opening and closing device 66 is not limited to the configuration shown as an example, and may have various configurations that are capable of moving the valve stem 64 in the axial direction.

[0028] The rotation device 68 is provided, for example, between the opening / closing device 66 and the valve element 62 on the valve shaft 64. The rotation device 68 is configured to be able to rotate the valve shaft 64 in the circumferential direction as the valve shaft 64 is moved by the opening / closing device 66. In FIG. 1, the dashed-dotted line C10 indicates the central axis of the valve shaft 64. The rotation device 68 rotates the valve shaft 64 around the central axis of the valve shaft 64. The rotation device 68 is able to rotate the valve element 62 by the rotation of the valve shaft 64.

[0029] The rotation device 68 may include, for example, a screw portion 90 and a bushing 92. The screw portion 90 is formed as a helical protrusion on the outer periphery of the valve stem 64. The bushing 92 is formed, for example, in a cylindrical shape, and the valve stem 64 is inserted therethrough. A helical recess 94 is formed on the inner surface of the bushing 92. The recess 94 of the bushing 92 is engaged with the screw portion 90 of the valve stem 64.

[0030] When the valve shaft 64 is moved in a direction away from the opening / closing device 66 by the opening / closing device 66, the spiral screw portion 90 of the rotation device 68 slides along the spiral recessed portion 94. As a result, the valve shaft 64 rotates in a first rotation direction around the central axis while moving in a direction away from the opening / closing device 66. That is, the valve body 62 moves away from the valve seat 60 while rotating in the first rotation direction.

[0031] Furthermore, even when the valve shaft 64 is moved in a direction approaching the opening / closing device 66 by the opening / closing device 66, the spiral screw portion 90 of the rotation device 68 slides along the spiral recessed portion 94. As a result, the valve shaft 64 rotates in a second rotation direction around the central axis while moving in a direction approaching the opening / closing device 66. The second rotation direction is the opposite direction to the first rotation direction. That is, the valve disc 62 abuts against the valve seat 60 while rotating in the second rotation direction.

[0032] The rotation device 68 is not limited to the configuration shown in the example. For example, the rotation device 68 may have a so-called ball screw configuration in which a spiral groove is formed in the valve shaft 64 and a ball that is housed in the groove of the valve shaft 64 and circulates is disposed on the inner surface of the bushing 92. In other words, the rotation device 68 may have various configurations that can rotate the valve shaft 64 in the circumferential direction in accordance with the movement of the valve shaft 64 by the opening / closing device 66.

[0033] Here, deposits may accumulate on the valve seat 60 due to components of the exhaust gas passing through the valve device 20. For example, deposits tend to accumulate easily on the primary side of the valve seat 60. If deposits accumulate excessively, for example, the EGR flow rate, which is the flow rate of exhaust gas passing through the valve device 20, may decrease.

[0034] Therefore, the valve device 20 of this embodiment is provided with a brush 70. As will be described later, in the valve device 20 of this embodiment, even if deposits accumulate on the valve seat 60, the brush 70 can remove the deposits.

[0035] The brush 70 is provided, for example, in the EGR flow path 16. The brush 70 is fixed to the tip portion 84 of the valve body 62. The brush 70 is located on the primary side relative to the valve body 62.

[0036] Fig. 2 is a partially enlarged view showing the periphery of the brush 70 when the valve body 62 is in a closed state relative to the valve seat 60. Fig. 3 is a partially enlarged view showing the periphery of the brush 70 when the valve body 62 is in an open state relative to the valve seat 60. Fig. 4 is a plan view of the valve seat 60 when viewed from the exhaust flow path 14 side.

[0037] 2 and 3, the brush 70 includes a base portion 100 and a fiber assembly portion 102. The base portion 100 is formed, for example, in a disk shape. The base portion 100 is disposed concentrically with the valve body 62 and is fixed to the tip portion 84 of the valve body 62.

[0038] The fiber assembly portion 102 is formed, for example, by assembling a plurality of fibrous members. The fiber assembly portion 102 is formed in a circular ring shape concentric with the base portion 100. The fiber assembly portion 102 is located on the outer periphery of the base portion 100 and is connected to the base portion 100. The fiber assembly portion 102 is provided around the entire circumferential circumference of the base portion 100, but is not limited to this example, and may be omitted from a portion of the base portion 100 in the circumferential direction.

[0039] The multiple fibrous members that make up the fiber assembly portion 102 generally extend radially outward from the outer peripheral surface of the base portion 100, but may include portions that extend in random directions.

[0040] The plurality of fibrous members constituting the fiber assembly portion 102 may be made of materials such as metal materials, natural fibers, synthetic fibers, synthetic resins, etc. For example, the brush 70 may be a metal brush having a fiber assembly portion 102 in which a plurality of fibrous members made of metal materials are assembled.

[0041] 2 and 3, the flange portion 86 of the valve body 62 is formed in a disk shape. The flange portion 86 of the valve body 62 protrudes radially outward relative to the remaining portion of the valve body 62. The secondary side of the protruding flange portion 86 has a flat surface that extends in a direction that intersects the axial direction of the valve body 62 at a right angle.

[0042] 2 to 4, the valve seat 60 includes a first portion 110 and a second portion 112. The first portion 110 is a portion that contacts the valve body 62. The second portion 112 is located radially outward of the first portion 110 from the valve seat 60, and is a portion that contacts the tip of the fiber assembly portion 102 of the brush 70. Both the first portion 110 and the second portion 112 face the primary side.

[0043] In the valve seat 60, the first portion 110 and the second portion 112 have different shapes. More specifically, the first portion 110 has a flat surface that extends in a direction that intersects approximately perpendicularly with the axial direction of the valve body 62. On the other hand, the second portion 112 has a slope whose radial width increases with increasing distance from the first portion 110 in the axial direction of the valve body 62. In the example shown in FIGS. 2 and 3 , the inclination angle of the slope of the second portion 112 is approximately 45 degrees with respect to the flat surface of the first portion 110, but may be set to any value.

[0044] The secondary flat surface of the protruding flange portion 86 of the valve body 62 abuts against the flat surface of the first portion 110 of the valve seat 60. Therefore, in the valve device 20, the airtightness can be improved when the valve body 62 is in the closed state relative to the valve seat 60.

[0045] The valve seat 60 also has a step 120 recessed from the second portion 112 toward the first portion 110 at the boundary between the first portion 110 and the second portion 112. The diameter of the step 120, i.e., the diameter of the outer periphery of the first portion 110 of the valve seat 60, may be set to a value substantially equal to the diameter of the flange portion 86 of the valve body 62. The recess depth of the step 120 may be set to a value substantially equal to the axial thickness of the flange portion 86 of the valve body 62.

[0046] By providing such a step 120, the protruding flange portion 86 of the valve element 62 is housed in the first portion 110 of the valve seat 60. This also improves the airtightness of the valve device 20 when the valve element 62 is in the closed state relative to the valve seat 60.

[0047] As described above, the second portion 112 of the valve seat 60 has a slope. When the valve body 62 is in the open state, exhaust gas passing through the valve seat 60 hits the slope of the second portion 112, rectifying the flow. In other words, the exhaust gas is more likely to hit the second portion 112. On the other hand, the first portion 110 is located inside the second portion 112 and has the step 120, so the exhaust gas is less likely to hit the first portion 110 than the second portion 112.

[0048] In other words, the valve device 20 makes it difficult for deposits to accumulate on the first portion 110 of the valve seat 60, and even if deposits do accumulate, the location of accumulation can be guided to the second portion 112 of the valve seat 60.

[0049] The brush 70 is fixed to the valve body 62 so that the radial tip of the fiber assembly portion 102 abuts against the second portion 112 of the valve seat 60 when the valve body 62 is in a closed state relative to the valve seat 60 .

[0050] The radial tip of the fiber assembly portion 102 is formed into a shape that matches the slope of the second portion 112 of the valve seat 60. In other words, the radial tip of the fiber assembly portion 102 is arranged along a tapered slope whose radial width increases as it moves away from the valve body 62 in the axial direction of the valve body 62. The inclination angle of the slope may be set to substantially the same value as the inclination angle of the slope of the second portion 112 of the valve seat 60.

[0051] In the valve device 20, when the valve body 62 is in the closed state, the fiber assembly portion 102 of the brush 70 abuts against the second portion 112 of the valve seat 60, thereby preventing deposits from accumulating on the second portion 112 of the valve seat 60 when the valve body 62 is in the closed state.

[0052] 2, when the valve stem 64 is moved to the primary side in the closed state, the valve element 62 moves toward the primary side while rotating in a first rotation direction as shown by arrow A10 due to the action of the opening / closing device 66 and the rotation device 68, and moves away from the first portion 110 of the valve seat 60. At this time, the brush 70 also moves toward the primary side while rotating in the first rotation direction together with the valve element 62, and moves away from the second portion 112 of the valve seat 60.

[0053] As a result, the fiber assembly portion 102 abutting against the second portion 112 of the valve seat 60 rotates spirally, scratching the surface of the second portion 112 and gradually moving away from the second portion 112. When the fiber assembly portion 102 scratches the surface of the second portion 112, the fiber assembly portion 102 scratches the deposits accumulated on the second portion 112, and the deposits are peeled off from the second portion 112 by the fiber assembly portion 102.

[0054] 3, when the valve stem 64 is moved to the secondary side in the open state, the valve element 62 moves toward the secondary side while rotating in the second rotation direction as shown by arrow A20 due to the action of the opening / closing device 66 and the rotation device 68, and approaches and abuts against the first portion of the valve seat 60. At this time, the brush 70 also moves toward the secondary side while rotating in the second rotation direction together with the valve element 62, and approaches and abuts against the second portion 112 of the valve seat 60.

[0055] As a result, when the fiber assembly portion 102 approaches and comes into contact with the second portion 112 of the valve seat 60, it rotates spirally and comes into contact with the second portion 112 in a manner that scrapes the surface of the second portion 112. When the fiber assembly portion 102 scratches the surface of the second portion 112, the fiber assembly portion 102 scrapes the deposits that have accumulated on the second portion 112, and the deposits are peeled off from the second portion 112 by the fiber assembly portion 102.

[0056] In this way, in the valve device 20, even if deposits have accumulated on the second portion 112, the deposits can be removed by the spiral rotation of the fiber assembly portion 102 of the brush 70 when the valve body 62 performs opening and closing operations.

[0057] For example, as described above, the valve control unit 52 initializes the valve device 20 when the engine 10 is started, and opens and closes the valve device 20 one or more times. Therefore, the valve device 20 can remove deposits at the timing when initialization is executed. Furthermore, the valve control unit 52 opens and closes the valve device 20 when changing the EGR flow rate in accordance with the state, speed, etc. of the engine 10. Therefore, the valve device 20 can remove deposits at the timing when the opening and closing operation of the valve device 20 in accordance with the state, speed, etc. of the engine 10 is executed.

[0058] As described above, the valve device 20 of this embodiment has the opening / closing device 66 that opens and closes the valve element 62 relative to the valve seat 60, and the rotation device 68 that rotates the valve element 62. The valve device 20 of this embodiment also has a brush 70 that is fixed to the valve element 62 so that its tip abuts against the valve seat 60 when the valve element 62 is in the closed state relative to the valve seat 60.

[0059] As a result, in the valve device 20 of this embodiment, when the valve element 62 performs an opening operation relative to the valve seat 60 and an closing operation relative to the valve seat 60, the brush 70 rotates and removes deposits that have accumulated on the valve seat 60. Therefore, the valve device 20 of this embodiment makes it possible to remove deposits.

[0060] Furthermore, in the valve device 20 of this embodiment, a step 120 is provided between the first portion 110 and the second portion 112 of the valve seat 60. As a result, in the valve device 20, the flange portion 86 of the valve element 62 is housed in the first portion 110 of the valve seat 60, thereby improving airtightness when the valve element 62 is in the closed state. Furthermore, in the valve device 20, the first portion 110 is shifted toward the secondary side relative to the second portion 112, so that when the valve element 62 is in the open state, exhaust gas is less likely to hit the first portion 110, making it possible to suppress the accumulation of deposits on the first portion 110.

[0061] Furthermore, in the valve device 20 of this embodiment, the first portion 110 and the second portion 112 of the valve seat 60 have different shapes. This allows the valve device 20 to have the first portion 110 shaped to correspond to the valve body 62 that abuts against the first portion 110, and the second portion 112 shaped to correspond to the brush 70 that abuts against the second portion 112. As a result, the valve device 20 can both improve airtightness when the valve body 62 is in the closed state and remove deposits with the brush 70.

[0062] Furthermore, in the valve device 20 of this embodiment, the second portion 112 of the valve seat 60 has a slope, and the tip of the brush 70 is formed in a shape that matches the slope of the second portion. As a result, in the valve device 20, when the valve body 62 is in the open state, the exhaust gas hits the slope of the second portion 112 and is rectified before flowing, making it easier for the exhaust gas to hit the second portion 112 and enabling the position where deposits accumulate to be guided to the slope of the second portion 112. Furthermore, in the valve device 20, the tip of the brush 70 is formed in a shape that matches the slope of the second portion 112, so that when the brush 70 rotates in a spiral pattern, the brush 70 can evenly scrape the entire slope of the second portion 112, making it possible to properly remove deposits accumulated on the slope.

[0063] While the present invention has been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such embodiments. It is clear that those skilled in the art can conceive of various modifications and alterations within the scope of the claims, and it is understood that such modifications and alterations also fall within the technical scope of the present invention.

[0064] For example, in the above embodiment, the step 120 is provided between the first portion 110 and the second portion 112 of the valve seat 60. However, the step 120 may be omitted, and the first portion 110 and the second portion 112 may be continuously connected.

[0065] In the above embodiment, the first portion 110 and the second portion 112 of the valve seat 60 have different shapes. However, the first portion 110 and the second portion 112 may have the same shape. For example, the first portion 110 may have the same slope as the second portion 112.

[0066] In the above embodiment, the second portion 112 of the valve seat 60 has a slope. However, the second portion 112 does not have to have a slope. For example, the second portion 112 may have a wall surface in which the radial width of the second portion 112 is constant as it moves away from the first portion 110 in the axial direction of the valve body 62. In this case, the circumferential tip of the brush 70 may also be formed in a shape that matches the wall surface of the second portion 112. [Explanation of symbols]

[0067] 10 Engine 12 Intake passage 16 EGR passage 20 Valve gear 60 Valve seat 62 Valve body 64 Valve stem 66 Switchgear 68 Rotating Device 70 brushes 80 through holes 110 Part 1 112 Part 2 120 steps

Claims

1. a valve seat having a through hole; a valve body that can open and close the through hole of the valve seat; a valve stem supporting the valve body; an opening and closing device configured to move the valve stem in an axial direction and opening and closing the valve element relative to the valve seat by the movement of the valve stem; a rotation device configured to rotate the valve shaft in a circumferential direction in accordance with the movement of the valve shaft by the opening and closing device, and to rotate the valve body by the rotation of the valve shaft; a brush fixed to the valve body so that a tip portion thereof abuts against the valve seat when the valve body is in a closed state relative to the valve seat; A valve device comprising:

2. The valve seat is a first portion that the valve body abuts against; a second portion located radially outward of the valve seat relative to the first portion and against which the tip end of the brush abuts; a step recessed from the second portion toward the first portion at a boundary between the first portion and the second portion; The valve device of claim 1 , wherein:

3. The valve seat is a first portion that the valve body abuts against; a second portion located radially outward of the valve seat relative to the first portion and against which the tip end of the brush abuts; and The valve device of claim 1 , wherein the first portion and the second portion have different shapes.

4. The valve seat is a first portion that the valve body abuts against; a second portion located radially outward of the valve seat relative to the first portion and against which the tip end of the brush abuts; and the second portion has a slope whose radial width increases as it moves away from the first portion, The valve device according to claim 1 , wherein the tip of the brush is formed into a shape that matches the slope of the second portion.

5. 2. The valve device according to claim 1, wherein the valve seat, the valve body, and the brush are provided in an EGR passage that recirculates a portion of exhaust gas discharged from the engine to an intake passage that supplies air to the engine.

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