Valve device

Abstract

To provide a valve device capable of discharging soot and moisture intruded toward a motor to outside of the device.SOLUTION: A valve device includes: a motor 20 having a motor shaft 21; a valve stem 11 with a tip of the motor shaft 21 is inserted into the other end thereof; bushes 41, 42 that movably support the valve stem 11 in the axial direction; a through hole 31 that supports the valve stem 11 via the bushes 41, 42; a spring chamber 33 in which a spring 45 for energizing the valve stem 11 is provided; and an atmosphere open hole 34 opened on the through hole 31. The valve stem 11 includes: a fitting hole 11a to which the tip of the motor shaft 21 is fitted; an upper stage communication hole 11b disposed in the spring chamber 33 and having an opening end on a radial inner side that can be sealed by the tip of the motor shaft 21 inserted into the fitting hole 11a; and a lower stage communication hole 11 that moves between a position opposing the upper stage bush 41 and a position opposing the atmosphere open hole 34.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Conventionally, there has been provided a technology for recirculating a part of exhaust gas discharged from a vehicle engine to an intake system. In such a technology, a valve device is sometimes used to adjust the amount of exhaust gas recirculated. For example, Patent Document 1 discloses such a valve device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-285918 A Summary of the Invention [Problem to be solved by the invention]

[0004] The valve device disclosed in Patent Document 1 includes a valve stem having a valve body and a bushing that supports the valve stem so that the valve stem can move in the axial direction. If soot (carbon) and moisture contained in the exhaust gas adhere (or accumulate) to the surface of the valve stem, the valve stem may become stuck to the bushing.

[0005] Therefore, the valve device disclosed in Patent Document 1 is provided with a relief groove at the portion of the valve stem that enters and exits the bush and in the vicinity thereof, so that soot adheres to the relief groove. Therefore, the valve device disclosed in Patent Document 1 can form a gap between the valve stem and the bush even if soot adheres, and can suppress the valve stem from sticking to the bush.

[0006] However, in the valve gear disclosed in Patent Document 1, if soot adheres to the valve shaft and the bush to the extent that there is no gap between them, the valve gear will no longer function as intended. Furthermore, if soot and moisture pass through the gap between the valve shaft and the bush, they may enter the motor that moves the valve shaft. If soot and moisture enter the motor, this can cause a decrease in performance and a shortened lifespan of the valve gear.

[0007] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide a valve device that can discharge soot and moisture that has entered toward a motor to the outside of the device. [Means for solving the problem]

[0008] The valve device according to the present disclosure comprises a motor having a motor shaft which moves in an axial direction, a valve shaft having a valve body provided at one end and into which a tip of the motor shaft is inserted at the other end, first and second bushes which support the valve shaft so that it can move in the axial direction, a through hole which supports the valve shaft via the first and second bushes, a spring chamber in which the motor shaft is disposed and in which a spring is disposed which urges the valve shaft towards a valve closing side, and a first atmosphere vent hole which opens between the first and second bushes in the through hole and communicates with the atmosphere, wherein the valve shaft has a fitting hole into which the tip of the motor shaft is fitted and which is formed in the axial direction, a first communication hole which opens into an outer circumferential surface of the valve shaft and communicates with the fitting hole, which is disposed in the spring chamber and has an opening end on the radially inner side which can be sealed by the tip of the motor shaft inserted into the fitting hole, and a second communication hole which opens into the outer circumferential surface of the valve shaft and communicates with the fitting hole, and which moves between a position facing the inner circumferential surface of the first bush and a position facing the first atmosphere vent hole. Effect of the Invention

[0009] According to the present disclosure, soot and moisture that have entered the motor can be discharged to the outside of the device, thereby preventing performance degradation of the valve device and extending its lifespan. [Brief description of the drawings]

[0010] [Figure 1] 1 is a vertical sectional view of a valve device according to a first embodiment. [Diagram 2] 1 is a vertical sectional view of a valve device according to a first embodiment. [Diagram 3] 1 is a vertical sectional view of a valve device according to a first embodiment. [Figure 4] 1 is a vertical sectional view of a valve device according to a first embodiment. [Diagram 5] 5 is an operation explanatory diagram illustrating the operation of the valve device according to the first embodiment. FIG. [Figure 6] 6 is an operation explanatory diagram illustrating the operation of the valve device, following FIG. 5. [Figure 7] 7 is an operation explanatory diagram illustrating the operation of the valve device, following FIG. 6. [Figure 8] 8 is an operation explanatory diagram illustrating the operation of the valve device, following FIG. 7. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0012] Embodiment 1 A valve device according to a first embodiment will be described with reference to FIGS. 1 to 8. FIG.

[0013] First, the configuration of the valve device according to the first embodiment will be described with reference to Fig. 1 to Fig. 4. Fig. 1 to Fig. 4 are vertical cross-sectional views of the valve device according to the first embodiment.

[0014] Specifically, Fig. 1 shows a closed valve state in which the valve bodies 12a and 12b are seated on the valve seats 43a and 43b. Fig. 2 shows an open valve state in which the valve bodies 12a and 12b are separated from the valve seats 43a and 43b. Fig. 3 shows a closed valve state in which the motor shaft 21 retracts the valve stem 11, causing the valve bodies 12a and 12b to be seated on the valve seats 43a and 43b. Fig. 4 shows a closed valve state in which only the motor shaft 21 is further retracted from the closed valve state shown in Fig. 3. Arrow G in Figs. 1 to 4 indicates the flow direction of EGR gas.

[0015] The valve device according to the first embodiment shown in FIG. 1 is applied to, for example, an EGR valve device of an exhaust gas recirculation (hereinafter referred to as EGR) system mounted on a vehicle. The EGR system is provided with an exhaust gas recirculation passage (hereinafter referred to as EGR passage) for recirculating (returning) a part of the exhaust gas (hereinafter referred to as EGR gas) from the exhaust system to the intake system for the purpose of reducing harmful substances contained in the exhaust gas discharged from the combustion chamber of the engine of the vehicle. This EGR system is provided with an EGR valve device in the middle of the EGR passage in order to control the flow rate of the EGR gas. The EGR valve device controls the flow rate of the EGR gas by adjusting the valve opening.

[0016] As shown in FIGS. 1 to 4, the valve device according to the first embodiment includes a valve member 10, a motor 20, and a housing 30, for example.

[0017] A lower portion of the motor 20 is fixed to an upper portion of the housing 30 using, for example, bolts or the like. The motor 20 includes a motor shaft 21. The motor 20 is capable of moving the motor shaft 21 back and forth in its axial direction. The stepped motor shaft 21 has a small diameter shaft portion 21a. The small diameter shaft portion 21a is formed at the tip of the motor shaft 21. The diameter of the small diameter shaft portion 21a is smaller than the diameter of the motor shaft 21 other than the small diameter shaft portion 21a.

[0018] As shown in Figures 1 to 4, the valve member 10 is slidably connected to the tip of the motor shaft 21. The valve member 10 includes, for example, one valve shaft 11 and two valve bodies 12a, 12b. The two valve bodies 12a, 12b are provided side by side in the axial direction on one end side of the valve shaft 11. The number of stages of the valve bodies can be adjusted as appropriate.

[0019] The valve shaft 11 has a fitting hole 11a, an upper stage communication hole 11b, and a lower stage communication hole 11c. The fitting hole 11a, the upper stage communication hole 11b, and the lower stage communication hole 11c are formed on the other end side of the valve shaft 11.

[0020] The fitting hole 11a is a hole that opens to the other end of the valve shaft 11 and extends in the axial direction of the valve shaft 11. A small diameter shaft portion 21a of a motor shaft 21 can be fitted into this fitting hole 11a.

[0021] The upper stage communication hole 11b and the lower stage communication hole 11c are holes that open to the outer peripheral surface of the valve shaft 11 and extend in the radial direction of the valve shaft 11. The fitting hole 11a, the upper stage communication hole 11b and the lower stage communication hole 11c are arranged so that their axes are perpendicular to each other. The upper stage communication hole 11b is arranged above the lower stage communication hole 11c. In other words, the upper stage communication hole 11b is arranged closer to the other end of the valve shaft 11 than the lower stage communication hole 11c. The upper stage communication hole 11b constitutes a first communication hole, and the lower stage communication hole 11c constitutes a second communication hole.

[0022] When the small diameter shaft portion 21a of the motor shaft 21 is inserted most deeply into the fitting hole 11a, the small diameter shaft portion 21a completely seals the upper stage communication hole 11b and opens at least a portion of the lower stage communication hole 11c. When the small diameter shaft portion 21a of the motor shaft 21 is inserted most shallowly into the fitting hole 11a, in other words, when it is pulled out most, the small diameter shaft portion 21a opens at least a portion of the upper stage communication hole 11b and completely opens the lower stage communication hole 11c.

[0023] As shown in FIGS. 1 to 4, the housing 30 includes a through hole 31, an exhaust gas passage 32, a spring chamber 33, and atmospheric opening holes 34 and 35.

[0024] The through hole 31 is a hole that passes vertically through a portion formed inside the housing 30. In the housing 30, a spring chamber 33 is formed above the through hole 31, while an exhaust gas passage 32 is formed below the through hole 31. The exhaust gas passage 32 and the spring chamber 33 are in communication with each other via the through hole 31.

[0025] The exhaust gas passage 32 forms a part of the EGR passage. EGR gas, which is a fluid, flows through the exhaust gas passage 32. The exhaust gas passage 32 is composed of an inflow passage 32a and outflow passages 32b and 32c.

[0026] The inflow passage 32a forms the upstream side of the exhaust gas passage 32, through which the EGR gas flows. The outflow passages 32b, 32c form the downstream side of the exhaust gas passage 32, through which the EGR gas flows. The inflow passage 32a branches into outflow passages 32b, 32c at its downstream end. The upper valve body 12a corresponds to the outflow passage 32b, and the lower valve body 12b corresponds to the outflow passage 32c.

[0027] The spring chamber 33 faces the motor 20. That is, the spring chamber 33 has the motor shaft 21 disposed therein.

[0028] The atmosphere vent hole 34 is provided in a side wall that forms the through hole 31 in the housing 30. This atmosphere vent hole 34 communicates between the inside of the through hole 31 and the outside of the housing 30. Therefore, the atmosphere vent hole 34 can open the inside of the through hole 31 to the atmosphere. The atmosphere vent hole 34 constitutes a first atmosphere vent hole.

[0029] The atmosphere vent hole 35 is provided in a side wall of the housing 30 that forms the spring chamber 33. This atmosphere vent hole 35 communicates between the inside of the spring chamber 33 and the outside of the housing 30. Therefore, the atmosphere vent hole 35 can open the inside of the spring chamber 33 to the atmosphere. The atmosphere vent hole 35 constitutes a second atmosphere vent hole.

[0030] As shown in FIGS. 1 to 4, the housing 30 is provided with an upper bush 41, a lower bush 42, valve seats 43a and 43b, a spring holder 44, a spring 45, and a cover member 46.

[0031] The upper bush 41 and the lower bush 42 support the valve shaft 11 so that it can reciprocate in its axial direction. The upper bush 41 and the lower bush 42 are provided in the through hole 31. The upper bush 41 is disposed above the lower bush 42. The upper bush 41 and the lower bush 42 are disposed at a predetermined interval in the axial direction of the valve shaft 11. That is, the valve shaft 11 is supported in the through hole 31 via the bushes 41, 42 so that it can reciprocate. The upper bush 41 constitutes a first bush, and the lower bush 42 constitutes a second bush.

[0032] When the valve stem 11 is supported in the through hole 31 via the bushes 41 and 42 in this manner, a space 31a is formed inside the through hole 31. This space 31a is an annular space defined by the outer circumferential surface of the valve stem 11, the lower surface of the upper bush 41, the upper surface of the lower bush 42, and the circumferential surface of the through hole 31. In addition, an atmosphere vent hole 34 communicates with the space 31a.

[0033] The valve seats 43a, 43b are provided in the exhaust gas passage 32. Specifically, the valve seat 43a is provided at the upstream end of the outflow passage 32b. The upper valve body 12a can be seated on this valve seat 43a. The valve seat 43b is provided at the upstream end of the outflow passage 32c. The lower valve body 12b can be seated on this valve seat 43b.

[0034] Therefore, when the valve bodies 12a and 12b move away from the valve seats 43a and 43b, i.e., when the valve bodies 12a and 12b open, the EGR gas that has flowed into the inflow passage 32a is branched into the outflow passages 32b and 32c. At this time, the flow rate of the EGR gas passing through the exhaust gas passage 32 can be adjusted by controlling the opening degree of the valve bodies 12a and 12b relative to the valve seats 43a and 43b. On the other hand, when the valve bodies 12a and 12b seat on the valve seats 43a and 43b, i.e., when the valve bodies 12a and 12b close, the flow of the EGR gas that has flowed into the inflow passage 32a to the outflow passages 32b and 32c is blocked by the valve bodies 12a and 12b.

[0035] The spring retainer 44 and the spring 45 are provided in the spring chamber 33. The spring retainer 44 has a circular shape. This spring retainer 44 is fixed to the outer circumferential surface of the other end side of the valve shaft 11. In contrast, the spring 45 is provided in a compressed state between the spring retainer 44 attached to the valve shaft 11 and the bottom surface of the spring chamber 33. Therefore, the spring 45 biases the valve shaft 11 upward via the spring retainer 44. In other words, the valve member 10 is always biased in the valve closing direction.

[0036] 4, the cover member 46 is intended to prevent foreign matter such as dust and dirt from entering the atmosphere vent holes 34, 35 from outside the housing 30. This cover member 46 is provided on the outer wall surface of the housing 30 so as to cover the atmosphere vent holes 34, 35 from the outside. The cover member 46 constitutes a foreign matter intrusion prevention member.

[0037] The cover member 46 may be flat, or may have a labyrinth structure. The cover member 46 having a labyrinth structure can make it difficult for foreign matter to reach the atmosphere vent holes 34, 35. The valve device may also be provided with a check valve instead of the cover member 46 as a foreign matter intrusion prevention member. This check valve only allows flow from the atmosphere vent holes 34, 35 toward the outside of the housing 30.

[0038] When the valve shaft 11 reciprocates in the axial direction, the lower stage communication hole 11c reciprocates between a position facing the inner circumferential surface of the upper stage bush 41 and a position facing the space 31a. The lower stage communication hole 11c faces the inner circumferential surface of the upper stage bush 41, and is thereby sealed by the upper stage bush 41. On the other hand, the lower stage communication hole 11c faces the space 31a, and is thereby communicated with the atmosphere via the atmosphere vent hole 34.

[0039] In contrast, when the valve shaft 11 reciprocates in the axial direction, the upper stage communication hole 11b is always disposed inside the spring chamber 33 and never faces the inner circumferential surface of the upper stage bush 41. In other words, the upper stage communication hole 11b reciprocates above the upper stage bush 41.

[0040] Therefore, when driving power is supplied to the motor 20, the motor shaft 21 is pushed from the axially inner side to the axially outer side of the motor 20. Therefore, the tip of the motor shaft 21 presses the other end of the valve shaft 11 that fits thereto, and the motor shaft 21 moves downward together with the valve shaft 11. Furthermore, the motor shaft 21 moves the valve shaft 11 downward against the biasing force of the spring 45. As a result, the valve bodies 12a and 12b of the valve shaft 11 are separated from the valve seats 43a and 43b, opening the outflow passages 32b and 32c. Therefore, the EGR gas is diverted from the inflow passage 32a to the outflow passages 32b and 32c, and is returned to the intake system of the engine. At this time, the flow rate of the EGR gas is controlled according to the valve opening degree of the valve bodies 12a and 12b relative to the valve seats 43a and 43b.

[0041] When driving power is supplied to the motor 20, the motor shaft 21 is retracted from the axially outer side to the axially inner side of the motor 20. Therefore, the tip of the motor shaft 21 retracts the other end of the valve shaft 11 that fits thereto, and the motor shaft 21 moves upward together with the valve shaft 11 by utilizing the biasing force of the spring 45. As a result, the valve bodies 12a and 12b of the valve shaft 11 seat on the valve seats 43a and 43b, closing the outflow passages 32b and 32c. Therefore, the flow of EGR gas from the inflow passage 32a to the outflow passages 32b and 32c is blocked. That is, the EGR gas is not recirculated to the intake system of the engine.

[0042] Here, the EGR gas flowing through the exhaust gas passage 32 often contains soot (carbon) and moisture. Such soot and moisture may pass between the outer circumferential surface of the valve shaft 11 and the inner circumferential surfaces of the bushes 41, 42 due to the reciprocating movement of the valve shaft 11 and the negative pressure on the motor 20 side, and may enter the inside of the motor 20 through the spring chamber 33. If soot and moisture enter the inside of the motor 20 in this way, the motor 20 will not operate correctly. This will result in a decrease in performance and a shortened life of the valve device.

[0043] To solve this problem, it is conceivable to provide a seal portion near where the bushes 41 and 42 are installed. However, even if a seal portion is used, it is very difficult to completely prevent the intrusion of soot and moisture. To solve the above problem, it is conceivable to narrow the gap between the outer circumferential surface of the valve shaft 11 and the inner circumferential surfaces of the bushes 41 and 42. However, narrowing the gap increases the sliding resistance to the valve shaft 11. Even in this case, it is very difficult to completely prevent the intrusion of soot and moisture.

[0044] Therefore, the valve device according to the first embodiment employs a structure that can discharge the invading soot and moisture to the outside of the device.

[0045] Next, the operation of the valve device according to the first embodiment to discharge the invading soot and moisture to the outside of the device will be described with reference to Figs. 2 to 8. Figs. 5 to 8 are operation explanatory diagrams sequentially explaining the operation of the valve device according to the first embodiment. Figs. 5 and 8 correspond to Fig. 2 and are enlarged views of the main parts of Fig. 2. Fig. 6 corresponds to Fig. 3 and is an enlarged view of the main parts of Fig. 3. Fig. 7 corresponds to Fig. 4 and is an enlarged view of the main parts of Fig. 7. The arrows in Figs. 7 and 8 indicate the flow directions of the soot and moisture.

[0046] First, as shown in Figures 2 and 5, when the valve bodies 12a, 12b are opened, the upper stage communication hole 11b is disposed inside the spring chamber 33, and the lower stage communication hole 11c is disposed inside the space 31a. At this time, the small diameter shaft portion 21a is inserted most deeply into the fitting hole 11a. The small diameter shaft portion 21a fitted into this fitting hole 11a seals the radially inner open end of the upper stage communication hole 11b.

[0047] Next, as shown in Fig. 3 and Fig. 6, when the valve bodies 12a, 12b are closed, the upper stage communication hole 11b is disposed inside the spring chamber 33, and the lower stage communication hole 11c faces the inner peripheral surface of the upper stage bush 41. At this time, the small diameter shaft portion 21a is pulled toward the motor 20 side, and the insertion amount into the fitting hole 11a is reduced accordingly. The small diameter shaft portion 21a fitted into the fitting hole 11a seals the radially inner opening end of the upper stage communication hole 11b. In addition, the radially inner opening end of the lower stage communication hole 11c is sealed by the small diameter shaft portion 21a via the fitting hole 11a, and the radially outer opening end of the lower stage communication hole 11c is sealed by the upper stage bush 41.

[0048] Next, as shown in Figures 4 and 7, even when the valve bodies 12a, 12b are closed, the motor shaft 21 is further retracted. In contrast, the valve shaft 11 does not move upward because the spring 45 does not expand any further even if the motor shaft 21 is further retracted. Therefore, the lower stage communication hole 11c continues to face the inner peripheral surface of the upper stage bush 41, but the upper stage communication hole 11b is released from the sealing of the radially inner opening end by the small diameter shaft portion 21a. As a result, the soot and moisture that have entered the spring chamber 33 and have not been discharged from the atmosphere vent hole 35 flow from the upper stage communication hole 11b toward the inside of the fitting hole 11a.

[0049] 2 and 8, when the valve bodies 12a, 12b are opened, the soot and moisture taken into the fitting hole 11a is discharged without leaving anything behind from the lower-stage communication hole 11c through the space 31a to the atmosphere vent hole 34 by the small diameter shaft portion 21a being inserted to the deepest depth into the fitting hole 11a. Therefore, the soot and moisture that has entered the spring chamber 33 is discharged from the space 31a through the atmosphere vent hole 34 to the atmosphere by the cooperation of the fitting hole 11a, the upper-stage communication hole 11b, the lower-stage communication hole 11c, and the small diameter shaft portion 21a.

[0050] As described above, the valve device according to embodiment 1 comprises a motor 20 having a motor shaft 21 which moves in the axial direction, a valve shaft 11 having valve bodies 12a, 12b provided at one end and into which the tip of the motor shaft 21 is inserted at the other end, an upper bush 41 and a lower bush 42 which support the valve shaft 11 so as to be movable in the axial direction, a through hole 31 which supports the valve shaft 11 via the upper bush 41 and the lower bush 42, a spring chamber 33 in which the motor shaft 21 is disposed and in which a spring 45 is provided which urges the valve shaft 11 towards the valve closing side, and an atmosphere vent hole 34 which opens between the upper bush 41 and the lower bush 42 in the through hole 31 and which communicates with the atmosphere. The valve shaft 11 also has a fitting hole 11a formed in the axial direction and into which the tip of the motor shaft 21 fits, an upper stage communication hole 11b that opens on the outer circumferential surface of the valve shaft 11 and communicates with the fitting hole 11a, is disposed in the spring chamber 33, and has an opening end on the inner side in the radial direction that can be sealed by the tip of the motor shaft 21 inserted into the fitting hole 11a, and a lower stage communication hole 11c that opens on the outer circumferential surface of the valve shaft 11 and communicates with the fitting hole 11a, and moves between a position facing the inner circumferential surface of the upper stage bush 41 and a position facing the atmosphere vent hole 34. Therefore, the valve device can discharge soot and moisture that have invaded toward the motor 20 to the outside of the device. As a result, the valve device can suppress performance degradation and extend its life.

[0051] In addition, in the present disclosure, any of the components of the embodiments may be modified or omitted within the scope of the disclosure.

[0052] Various aspects of the present disclosure are summarized below as appendices.

[0053] (Appendix 1) a motor having a motor shaft moving axially; a valve shaft having a valve body provided at one end thereof and a tip end of the motor shaft inserted into the other end thereof; a first bush and a second bush that support the valve shaft axially movably; a through hole that supports the valve shaft via the first bush and the second bush; a spring chamber in which the motor shaft is disposed and in which a spring is provided to bias the valve shaft toward a valve closing side; a first atmosphere vent hole that opens between the first bush and the second bush in the through hole and communicates with the atmosphere, The valve stem is a fitting hole formed in the axial direction and into which the tip of the motor shaft is fitted; a first communication hole that opens onto an outer circumferential surface of the valve shaft and communicates with the fitting hole, the first communication hole being disposed in the spring chamber and having an opening end on a radially inner side that can be sealed by a tip of the motor shaft inserted into the fitting hole; a second communication hole that opens to an outer circumferential surface of the valve shaft, communicates with the fitting hole, and moves between a position facing the inner circumferential surface of the first bush and a position facing the first atmosphere vent hole; A valve device comprising:

[0054] (Appendix 2) The second communication hole is The radially inner open end is not sealed by the tip of the motor shaft inserted into the fitting hole. 2. The valve device according to claim 1.

[0055] (Appendix 3) A second atmosphere vent hole is provided which opens into the spring chamber and communicates with the atmosphere. 3. The valve device according to claim 1 or 2.

[0056] (Appendix 4) a foreign object intrusion prevention member that prevents foreign objects from intruding into the first atmospheric vent hole and the second atmospheric vent hole from the outside; 4. The valve device according to claim 3.

[0057] (Appendix 5) The foreign object intrusion prevention member is a cover member that covers the first atmospheric vent hole and the second atmospheric vent hole from the outside. 5. The valve device according to claim 4.

[0058] (Appendix 6) The cover member has a labyrinth structure. 6. The valve device according to claim 5.

[0059] (Appendix 7) The foreign object intrusion prevention member is a check valve that allows only outward flow from the first atmosphere vent hole and the second atmosphere vent hole 5. The valve device according to claim 4. [Explanation of symbols]

[0060] 10 valve member, 11 valve shaft, 11a fitting hole, 11b upper stage communication hole, 11c lower stage communication hole, 12a, 12b valve body, 20 motor, 21 motor shaft, 21a small diameter shaft portion, 30 housing, 31 through hole, 31a space, 32 exhaust gas passage, 32a inlet passage, 32b, 32c outlet passage, 33 spring chamber, 34, 35 atmosphere vent hole, 41 upper stage bush, 42 lower stage bush, 43a, 43b valve seat, 44 spring retainer, 45 spring, 46 cover member.

Claims

1. a motor having a motor shaft moving axially; a valve shaft having a valve body provided at one end thereof and a tip end of the motor shaft inserted into the other end thereof; a first bush and a second bush supporting the valve shaft so as to be axially movable; a through hole that supports the valve shaft via the first bush and the second bush; a spring chamber in which the motor shaft is disposed and in which a spring is provided to bias the valve shaft toward a valve closing side; a first atmosphere vent hole that opens between the first bush and the second bush in the through hole and communicates with the atmosphere, The valve stem is a fitting hole formed in the axial direction and into which the tip of the motor shaft is fitted; a first communication hole that opens onto an outer circumferential surface of the valve shaft, communicates with the fitting hole, is disposed in the spring chamber, and has an opening end on a radially inner side that can be sealed by a tip of the motor shaft inserted into the fitting hole; a second communication hole that opens to an outer circumferential surface of the valve shaft, communicates with the fitting hole, and moves between a position facing the inner circumferential surface of the first bush and a position facing the first atmosphere vent hole; A valve device comprising:

2. The second communication hole is The radially inner open end is not sealed by the tip of the motor shaft inserted into the fitting hole.

2. The valve device according to claim 1.

3. A second atmosphere vent hole is provided which opens into the spring chamber and communicates with the atmosphere.

2. The valve device according to claim 1.

4. a foreign object intrusion prevention member that prevents foreign objects from intruding into the first atmospheric vent hole and the second atmospheric vent hole from the outside; 4. The valve device according to claim 3.

5. The foreign object intrusion prevention member is a cover member that covers the first atmospheric vent hole and the second atmospheric vent hole from the outside; 5. The valve device according to claim 4.

6. The cover member has a labyrinth structure.

6. The valve device according to claim 5.

7. The foreign object intrusion prevention member is a check valve that allows only outward flow from the first atmosphere vent hole and the second atmosphere vent hole.

5. The valve device according to claim 4.

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