Motorized valve

Abstract

A motorized valve according to the present invention comprises an output shaft 45 that outputs rotation generated by a drive unit, and a bearing member 46 that has a through-hole 47 into which the output shaft is inserted and supports the output shaft so as to be capable of rotation, the through-hole having an enlarged diameter portion 47a that is formed at an upper end section thereof and has a large inner diameter, and a hole body portion 47b that extends downwards from the enlarged diameter portion, and the output shaft having a connection portion 45a that is connected to the drive unit, a shaft body portion 45c that is inserted into the hole body portion, and a flange portion 45b that is formed between the connection portion and the shaft body portion, projects further outwards than the shaft body portion, and is accommodated in the enlarged diameter portion, wherein: a clearance that allows the shaft body portion to rotate and slide inside the hole body portion while restricting deviation of the output shaft position in the radial direction is formed between the outer peripheral surface of the shaft body portion and the inner peripheral surface of the hole body portion; a gap 47c larger than the clearance is formed between the outer peripheral surface of the flange portion and the inner peripheral surface of the enlarged diameter portion; and a lubricating agent accumulates in the gap.

Description

Electric valve

[0001] The present invention relates to an electric valve, and particularly to the structure of an output portion that outputs the rotation of an electric motor.

[0002] Electric valves that control the opening degree of a valve using an electric motor such as a stepping motor have been conventionally used in refrigeration cycle devices equipped with a refrigerant circuit such as an air conditioner and a refrigeration or freezing device. Also, there is a gear-type electric valve as such an electric valve.

[0003] FIGS. 5 and 6 show an example of a conventional gear-type electric valve. As shown in these figures, the electric valve 61 includes a valve body 19 that controls the flow rate of refrigerant by moving forward and backward with respect to a valve port 16 formed between an inflow passage 14 and an outflow passage 15 that communicate with a valve chamber 13, a drive unit 24 that generates a rotational driving force for driving the valve body 19, and a feed screw mechanism 48 that converts the rotational driving force generated by the drive unit 24 into a linear driving force. Further, the drive unit 24 includes an electric motor 25 (for example, a stepping motor) that includes a magnet rotor 26 (which may be simply referred to as a "rotor" in the present application) and a speed reduction mechanism 33 that reduces the rotation of the rotor 26.

[0004] The speed reduction mechanism 33 is configured by, for example, a planetary gear mechanism, and an output shaft 62 is connected to an output gear 43 of the speed reduction mechanism 33. The output shaft 62 is inserted into an upper portion of a through hole 47 that penetrates a bearing member 63 in the vertical direction and is rotatably supported by the bearing member 63. An internal thread 47d is formed on the lower inner peripheral surface of the through hole 47 of the bearing member 63, and a columnar feed screw member 49 having an external thread 49b that engages with the internal thread 47d is provided so as to be screwed in from below the bearing member 63. The feed screw member 49 has a plate-like portion 49a that stands upright vertically upward at its upper end. The plate-like portion 49a is fitted into a slit-like fitting groove 45e formed on the lower surface portion of the output shaft 62 so as to be slidable in the vertical direction and capable of transmitting the rotation of the output shaft 62 to the feed screw member 49. The feed screw mechanism 48 is constituted by these feed screw member 49 (external thread 49b) and bearing member 63 (internal thread 47d).

[0005] Therefore, when the output shaft 62 rotates due to the rotation of the output gear 43 of the reduction mechanism 33, this rotation is transmitted to the lead screw member 49 via the fitting groove 45e and the plate-shaped portion 49a, and this rotation is converted into vertical movement of the lead screw member 49 by the action of the lead screw mechanism 48. This vertical movement is transmitted from the lead screw member 49 to the valve body 19 via the ball-shaped joint 50, and the opening degree of the valve port 16 is adjusted by the vertical movement of the valve body 19.

[0006] Furthermore, the following patent documents disclose such electric valves.

[0007] Patent Document 1: Japanese Unexamined Patent Publication No. 2009-185877 Patent Document 2: Japanese Unexamined Patent Publication No. 2023-3144

[0008] Incidentally, when assembling the electric valve 61, lubricants such as lubricating oil or grease are applied to areas where components move relative to each other while in contact, for example, the rotating sliding part between the output shaft 62 and the bearing member 63 (between the inner circumferential surface of the through hole 47 of the bearing member 63 and the outer circumferential surface of the output shaft 62 fitted into the through hole 47), and the threaded part of the feed screw mechanism 48 (the meshing part between the male screw 49b and the female screw 47d) in order to reduce friction and prevent wear of the components.

[0009] However, the rotor 26, reduction gear 33, and lead screw mechanism 48 of the electric motor 61 are housed inside a can (sealed container) 21 that forms a sealed space above the valve chamber 13, and the rotating sliding parts and screwed parts described above are located inside this sealed space, so it is not possible to replenish the lubricant after assembly.

[0010] Furthermore, the inside of the can 21 is in communication with the valve chamber 13, and refrigerant enters and exits when the electric valve 61 is in use. As a result, the lubricant applied to the rotating sliding parts and threaded parts may flow into the refrigerant and be gradually lost, potentially increasing friction in the rotating sliding parts and threaded parts, or causing wear on the components.

[0011] Furthermore, these problems cannot be solved by the invention described in the aforementioned patent document.

[0012] Therefore, the objective of the present invention is to prevent lubrication shortages by storing lubricant and replenishing it in the rotating sliding parts and screwed parts, thereby improving the durability of the electric valve.

[0013] To solve the aforementioned problems and achieve the objective, the electric valve according to the present invention comprises a valve body having a valve chamber inside and an inlet passage for introducing fluid into the valve chamber and an outlet passage for introducing fluid from the valve chamber; a valve body that controls the opening of the fluid passage by moving back and forth relative to a valve seat formed between the inlet passage and the outlet passage; a drive unit including a rotor (magnetic rotor) that generates a rotational driving force to drive the valve body and a reduction mechanism for reducing the rotation of the rotor; an output shaft that outputs the rotation reduced by the reduction mechanism; and a bearing member that has a through hole into which the output shaft is fitted and rotatably supports the output shaft.

[0014] Furthermore, when the direction from the valve seat towards the drive unit is defined as "up" and the direction from the drive unit towards the valve seat is defined as "down", the through hole has an enlarged diameter portion with a larger inner diameter formed at the upper end of the through hole, and a hole body portion that extends downward following the enlarged diameter portion. The output shaft also has a connecting portion connected to the reduction mechanism, a shaft body portion that fits into the hole body portion, and a flange portion formed between the connecting portion and the shaft body portion, which protrudes outward from the shaft body portion and is housed in the enlarged diameter portion.

[0015] Furthermore, a clearance is formed between the outer circumferential surface of the shaft body and the inner circumferential surface of the bore body, which limits the radial displacement of the output shaft while simultaneously allowing the shaft body to rotate and slide within the bore body. On the other hand, a gap larger than the aforementioned clearance (hereinafter sometimes referred to as the "lubricant reservoir") is formed between the outer circumferential surface of the flange portion and the inner circumferential surface of the enlarged diameter portion.

[0016] In the electric valve of the present invention, a gap (ring-shaped space) larger than the clearance that allows rotational sliding is formed between the flange portion of the output shaft and the enlarged diameter portion of the through hole of the bearing member into which the output shaft is fitted, and a lubricant such as lubricating oil or grease is stored in this gap. This prevents a lack of lubricant in the rotational sliding portion between the output shaft and the bearing member, and in the threaded portion between the bearing member and the lead screw member (described later), thereby suppressing wear of each component constituting the rotational sliding portion and the threaded portion and improving the durability of the electric valve.

[0017] Furthermore, the electric valve according to the present invention may be provided with a lead screw member connected to the output shaft within the through hole so as to be relatively movable in the vertical direction and so as to transmit the rotation of the output shaft. In this case, a female thread is formed at the bottom of the through hole, and a male thread is formed on the outer surface of the lead screw member to screw into the female thread, so that the lead screw is formed by these female and male threads. With such a structure, the rotational motion of the output shaft can be converted into the vertical motion of the lead screw member and transmitted to the valve body.

[0018] According to the present invention, the durability of the electric valve can be improved by storing lubricant and replenishing it in the rotating sliding parts and screwed parts.

[0019] Other objects, features, and advantages of the present invention will be made clearer by the following description of embodiments of the invention based on the drawings. It should be noted that the present invention is not limited to the embodiments described below, and it will be apparent to those skilled in the art that various modifications can be made within the scope of the claims. Furthermore, in each figure, the same reference numerals indicate the same or corresponding parts.

[0020] Figure 1 is a longitudinal cross-sectional view showing the closed state of an electric valve according to one embodiment of the present invention. Figure 2 is a longitudinal cross-sectional view showing the open state of the electric valve according to the embodiment. Figure 3 is a longitudinal cross-sectional view showing an enlarged view of the output shaft portion (part B in Figure 1) of the electric valve according to the embodiment. Figure 4 is a front view showing an enlarged view of the output shaft of the electric valve according to the embodiment. Figure 5 is a longitudinal cross-sectional view showing the closed state of a conventional electric valve. Figure 6 is a longitudinal cross-sectional view showing an enlarged view of the output shaft portion (part B1 in Figure 5) of the conventional electric valve.

[0021] [First Embodiment] An electric valve 11 according to the first embodiment of the present invention will be described with reference to Figures 1 to 4. In the following description, the top of each figure (i.e., the direction from the valve seat 18 toward the drive unit 24) will be referred to as "up", the bottom of each figure (i.e., the direction from the drive unit 24 toward the valve seat 18) will be referred to as "down", the up and down directions in each figure will be referred to as the vertical direction, and the direction perpendicular to the vertical direction will be referred to as the horizontal direction. However, since the electric valve of the present invention and this embodiment can be used in various orientations (for example, lying on its side or at an angle), "down" is not necessarily the direction of gravity and "up" is not necessarily the opposite direction of gravity (the same applies to the vertical and horizontal directions).

[0022] As shown in Figures 1 to 4, an electric valve 11 according to one embodiment of the present invention can be incorporated into a refrigeration cycle device such as a heat pump type heating and cooling system to control the flow rate of a fluid such as a refrigerant. It comprises a valve body 12 having a valve chamber 13 inside, an inlet passage 14 for introducing fluid into the valve chamber 13, and an outlet passage 15 for releasing fluid from the valve chamber 13; a valve opening 16 formed at the valve chamber 13 side end of the inlet passage 14; a valve element 19 that controls the opening degree of the valve opening 16 by moving back and forth relative to a valve seat 18 formed at the upper end of the valve opening 16; and a rotary drive for driving the valve element 19. The valve comprises a drive unit 24 including an electric motor 25 that generates force and a reduction mechanism 33 that reduces the rotation of the electric motor 25; an output shaft 45 that outputs the rotation reduced by the reduction mechanism 33; a bearing member 46 that has a through hole 47 into which the output shaft 45 is fitted and rotatably supports the output shaft 45; a lead screw mechanism 48 that converts the rotation of the output shaft 45 into linear motion; a connecting member 23 that supports the bearing member 46 and connects the drive unit 24 and the valve body 12; a valve body guide member 20 that supports the valve body 19 so that it can slide up and down; and a can (sealed container) 21 that forms a sealed space on the upper part of the valve body 12.

[0023] The valve body 12 is a block-shaped metal member with a vertical hole drilled in the center of its upper surface, extending vertically downward, and the lower part of this vertical hole forms the valve chamber 13. An inlet passage 14 is opened at the bottom of the valve chamber 13, and the valve opening 16 is formed by installing a ring-shaped valve seat member 17 in this opening. A valve body guide member 20 is also provided in the middle of the vertical hole (upper side of the valve chamber 13). The upper end of the vertical hole is a connecting opening into which the connecting member 23 is screwed and fixed.

[0024] In this embodiment, a stepping motor is used as the electric motor 25 provided in the drive unit 24. This stepping motor 25 has a stator 28 installed on the outside (outer circumference) of the can 21 and a rotor (magnetic rotor) 26 rotatably installed on the inside (inner circumference) of the can 21. The can 21 is a cylindrical member with no bottom and a lid (open on the bottom and closed on the top), and is joined to the upper outer circumference of the connecting member 23 via a ring-shaped base plate 22.

[0025] The stator 28 includes a yoke 29, a coil 31 with windings wound on a bobbin 30, and a resin molded cover 32 that covers the yoke 29 and the coil 31.

[0026] On the other hand, the rotor 26 is constructed by integrally connecting a cylindrical rotor member 27 made of a magnetic material (permanent magnet) and a sun gear member 34 made of a resin material. A rotor shaft 36 is inserted into the center of the sun gear member 34, and the upper part of the rotor shaft 36 is rotatably supported by a support member 37 positioned inside the top of the can 21.

[0027] The sun gear 35 of the sun gear member 34 meshes with a plurality of planetary gears 40 that are rotatably supported by a gear shaft 39 provided on a carrier 38 mounted on the bottom surface of the output gear 43. The upper part of the planetary gears 40 meshes with an annular ring gear (internal fixed gear) 42 attached to the upper part of a gear case 44 fixed to the upper part of the connecting member 23, and the lower part of the planetary gears 40 meshes with an internal gear 41 of the annular output gear 43. The number of teeth of the ring gear 42 and the number of teeth of the internal gear 41 of the output gear 43 are slightly different, so that the rotational speed of the sun gear 35 is reduced by a large reduction ratio and transmitted to the output gear 43. These gear mechanisms (sun gear 35, planetary gears 40, ring gear 42, and output gear 43) form a unique planetary gear mechanism and constitute the reduction mechanism 33 described above. The reduction mechanism referred to in this invention may be other planetary gear mechanisms or reduction mechanisms other than planetary gear mechanisms.

[0028] A connecting portion 45a, which will be the upper end of the output shaft 45, is press-fitted into the bottom central hole of the output gear 43, thereby connecting the output gear 43 and the output shaft 45. The output shaft 45 has the connecting portion 45a, a shaft body portion 45c that fits into the through hole 47 of the bearing member 46, and a disc-shaped flange portion 45b formed between the connecting portion 45a and the shaft body portion 45c, which protrudes outward from the connecting portion 45a and the shaft body portion 45c (away from the central axis A).

[0029] The connecting portion 45a has a plurality of protrusions 45f extending vertically and arranged circumferentially along the outer surface of the connecting portion on its outer surface (see Figure 4). Each protrusion 45f has a roughly triangular horizontal cross-sectional shape with its vertex pointing outward. The output shaft 45 is connected to the output gear 43 by pushing the connecting portion 45a into the bottom central hole of the output gear 43, while crushing each vertex (edge ​​of each protrusion 45f) until the flange portion 45b contacts the lower surface of the output gear 43.

[0030] A support hole 45d is formed in the upper center of the output shaft 45 (the center of the connecting portion 45a and the center of the flange portion 45b), extending vertically downward from the upper surface of the connecting portion 45a. This support hole 45d supports the lower end of the rotor shaft 36, and the lower end of the rotor shaft 36 is rotatably fitted into the support hole 45d. In addition, a slit-shaped fitting groove 45e is formed in the shaft body portion 45c, into which the plate-shaped portion 49a (described later) of the feed screw member 49 can be fitted from below.

[0031] The bearing member 46, which rotatably supports the output shaft 45, is fitted into and fixed to the connecting member 23 so as to be positioned at the bottom of the rotor 26. The connecting member 23 is a cylindrical member having a large-diameter hole 23a and a small-diameter hole 23b, which are through holes communicating with each other. The large-diameter hole 23a is a hole with a large diameter that penetrates the upper center of the connecting member 23, and the bearing member 46 is fitted into this large-diameter hole 23a from above. The small-diameter hole 23b is a hole with a small diameter that penetrates the lower center of the connecting member 23, and the lower end of the lead screw member 49, the ball-shaped joint 50 and spring-receiving member 53 (described later), and the upper end of the valve stem portion 19b are arranged to move up and down inside the small-diameter hole 23b.

[0032] As described above, the bearing member 46 has a through hole 47, which consists of an enlarged diameter portion 47a formed at the upper end of the through hole 47 and a hole body portion 47b extending downward from the enlarged diameter portion 47a. The shaft body portion 45c of the output shaft 45 is fitted into the hole body portion 47b, and the flange portion 45b of the output shaft 45 is housed in the enlarged diameter portion 47a. A shelf-like step is formed between the enlarged diameter portion 47a and the hole body portion 47b, and in this embodiment, the output shaft 45 is positioned so that the flange portion 45b rests on this step, allowing the bearing member 46 to support the output shaft 45 from below. Furthermore, as shown in Figure 3, the contact surfaces between the flange portion 45b and the bearing member 46, that is, the lower surface of the flange portion 45b and the upper surface of the step (the mounting surface on which the flange portion 45b rests), are rotational sliding surfaces on which the flange portion 45b rotates while in contact. On the other hand, when the flange portion 45b is placed on the bearing member 46 (the stepped portion), a gap is formed between the output gear 43 and the bearing member 46 in the vertical direction (the direction in which the central axis A extends) (see Figure 3).

[0033] Here, a certain small gap (clearance / not shown) is formed between the inner circumferential surface of the hole body portion 47b and the outer circumferential surface of the shaft body portion 45c. This is to prevent the output shaft 45 from moving (shifting) in the radial direction (horizontal direction) while allowing the output shaft 45 to rotate (rotate).

[0034] On the other hand, a gap 47c larger than the above clearance is formed between the inner circumferential surface of the enlarged diameter portion 47a and the outer circumferential surface of the flange portion 45b. This gap 47c is a ring-shaped space that serves as a lubricant reservoir for storing lubricant (see Figure 3). During the manufacture of the electric valve 11, lubricant (for example, lubricating oil or grease) is applied to the rotating sliding parts (such as the inner circumferential surface of the bore body portion 47b and the outer circumferential surface of the shaft body portion 45c) and the threaded parts (such as the male threaded portion 49b of the feed screw member 49 and the female threaded portion 47d of the bearing member 46, which will be described later), and also filled into the lubricant reservoir 47c. As a result, lubricating oil is replenished from the lubricant reservoir 47c to the rotating sliding parts and threaded parts, preventing (or suppressing) increased friction and wear of these movable parts (rotating sliding parts and threaded parts, etc.) due to a lack of lubricant.

[0035] The lead screw mechanism 48 is formed in the lower part of the through hole 47 of the bearing member 46. Specifically, a female thread (female thread portion) 47d is formed on the lower inner circumferential surface of the through hole 47 of the bearing member 46. A lead screw member 49 is also provided within the through hole 47. The lead screw member 49 has a male thread (male thread portion) 49b on its outer circumferential surface that screws into the female thread 47d. The lead screw member 49 also has a plate-like portion 49a that rises vertically upward at its upper end. This plate-like portion 49a is inserted from below into a fitting groove 45e formed in the output shaft 45 so as to be able to slide up and down.

[0036] Here, the output gear 43 and the output shaft 45 connected to the output gear 43 rotate without moving up or down at a fixed position in the vertical direction. This rotation is transmitted to the plate-shaped portion 49a inserted into the fitting groove 45e, causing the lead screw member 49 to rotate. When the lead screw member 49 rotates, it moves linearly in the vertical direction due to the action of the lead screw (because the male thread 49b formed on the outer circumferential surface of the lead screw member 49 meshes with the female thread 47d formed on the inner circumferential surface of the through hole 47 of the bearing member 46).

[0037] The linear vertical motion of the lead screw member 49 is transmitted to the valve body 19 via a ball-shaped joint 50 consisting of a ball 51 and a ball seat 52, and a spring-receiving member 53. The valve body 19 consists of a disc-shaped valve body portion 19a that moves toward and away from the valve seat 18, and a stepped cylindrical valve stem portion 19b that rises vertically upward from the center of the upper surface of the valve body portion 19a. The spring-receiving member 53 and the valve body 19 (valve stem portion 19b) are connected by inserting the upper end of the valve stem portion 19b into a fitting hole (lower fitting hole) 53a formed in the center of the lower surface of the spring-receiving member 53. In addition, a fitting hole (upper fitting hole) 53b is also provided in the center of the upper surface of the spring-receiving member 53, and the ball seat 52 is fitted into this upper fitting hole 53b.

[0038] Furthermore, the valve body guide member 20 and the connecting member 23 are fixed to the vertical hole in the valve body 12 by screwing them in sequentially, thereby closing the upper surface of the valve chamber 13. The valve shaft portion 19b passes through the center of the valve body guide member 20, which is fixed to the upper part of the valve chamber 13, so as to be able to slide up and down. A compression coil spring (a coil spring installed in a compressed state) 54 is provided between the valve body guide member 20 and the spring receiving member 53. This compression coil spring 54 constantly biases the valve body 19 upward (in the valve opening direction) via the spring receiving member 53, so that even when the lead screw member 49 moves upward, the lead screw member 49 and the valve body 19, which are in contact via the ball joint 50, do not separate, and the lead screw member 49 and the valve body 19 are integrated in the vertical direction. Furthermore, when the valve is opened, the biasing force of the compression coil spring 54 is applied to the valve body 19 in addition to the driving force of the electric motor 25, making it possible to open the valve more reliably.

[0039] Furthermore, the lead screw member 49 on the drive unit side rotates and slides relative to the valve body 19 around the central axis A via the ball 51, and the rotation of the lead screw member 49 is not transmitted to the valve body 19. In this embodiment, the valve port 16, valve seat 18, valve body 19 (valve body main body 19a and valve stem 19b), ball-shaped coupling 50 (ball 51 and ball seat 52), lead screw member 49, connecting member 23, bearing member 46, output shaft 45, and output gear 43 are arranged coaxially, and their central axis A coincides with the rotation axis of the rotor 26.

[0040] The operation of the electric valve according to this embodiment is as follows.

[0041] When current is supplied to the stator 28 (coil 31) so that the rotor 26 rotates in one direction from the closed valve state shown in Figure 1, the rotation of the rotor 26 is converted into linear motion by the lead screw mechanism 48, and the lead screw member 49 is pulled upward. Accordingly, the valve body 19, which is pressed against the lower surface of the lead screw member 49 via the spring support member 53 and the ball joint 50 by the biasing force of the compression coil spring 54, is pulled upward, and the valve body 19 (valve body main part 19a) separates from the valve seat 18, and the valve port 16 is opened. Then, the fluid that has flowed in through the inlet passage 14 flows out through the valve chamber 13 and out through the outlet passage 15 (see arrow F in Figure 2). The amount of fluid passing through (flow rate) in this open valve state can be adjusted by the amount of rotation of the rotor 26 (distance between the valve seat 18 and the valve body main part 19a).

[0042] On the other hand, when current is supplied to the stator 28 (coil 31) so that the rotor 26 rotates in the opposite direction to the above-mentioned one direction from this open valve state, the rotation of the rotor 26 is converted into linear motion by the lead screw mechanism 48, and the lead screw member 49 moves downward. Along with this downward movement, the valve body 19 moves downward, and when the valve body 19 (valve body main portion 19a) comes into contact with the valve seat 18, the flow path between the inlet passage 14 and the outlet passage 15 is blocked, resulting in a closed valve state (see Figure 1).

[0043] In the above description of operation, fluid was introduced into the valve chamber 13 through the inlet passage 14 and discharged from the valve chamber 13 through the outlet passage 15. However, it is also possible to use the electric valve 11 in the reverse manner, introducing fluid into the valve chamber 13 through the outlet passage 15 and discharging fluid from the valve chamber 13 through the inlet passage 14.

[0044] A. Central axis (rotor rotation axis) F. Fluid flow 11, 61. Motorized valve 12. Valve body 13. Valve chamber 14. Inlet passage 15. Outlet passage 16. Valve port 17. Valve seat member 18. Valve seat 19. Valve body 19a. Valve body main part 19b. Valve stem part 20. Valve body guide member 21. Can 22. Base plate 23. Connecting member 23a. Large diameter hole 23b. Small diameter hole 24. Drive unit 25. Electric motor (stepping motor) 26. Magnet rotor 27. Rotor member 28. Stator 29. Yoke 30. Bobbin 31. Coil 32. Resin molded cover 33. Reduction mechanism (mysterious planetary gear mechanism) 34. Sun gear member 35. Sun gear 36. Rotor shaft 37. Support member 38. Carrier 39. Gear shaft 40. Planetary gear 41 Internal gear 42 Ring gear 43 Output gear 44 Gear case 45, 62 Output shaft 45a Connecting part 45b Flange part 45c Shaft body part 45d Support hole 45e Fitting groove 45f Protrusion 46, 63 Bearing member 47 Through hole 47a Enlarged diameter part 47b Hole body part 47c Lubricant reservoir part 47d Female screw (female screw part) 48 Lead screw mechanism 49 Lead screw member 49a Plate-shaped part 49b Male screw (male screw part) 50 Ball joint 51 Ball 52 Ball seat 53 Spring seat member 53a Bottom fitting hole 53b Top fitting hole 54 Compression coil spring

Claims

1. A valve body having a valve chamber inside and an inlet passage for introducing fluid into the valve chamber and an outlet passage for releasing the fluid from the valve chamber; a valve element that controls the opening of the fluid flow path by moving back and forth relative to a valve seat formed between the inlet passage and the outlet passage; a drive unit including a magnet rotor that generates a rotational driving force to drive the valve element and a reduction mechanism that reduces the rotation of the magnet rotor; an output shaft that outputs the rotation reduced by the reduction mechanism; a bearing member having a through hole into which the output shaft is fitted and which rotatably supports the output shaft; and when the direction from the valve seat toward the drive unit is defined as "up" and the direction from the drive unit toward the valve seat is defined as "down", the through hole has a larger diameter enlarged portion formed at the upper end of the through hole, and a hole body portion extending downward following the enlarged portion; and the output shaft has a connecting portion connected to the reduction mechanism, and a shaft body portion fitted into the hole body portion. An electric valve having a flange portion formed between the connecting portion and the shaft body portion, protruding outward from the shaft body portion and housed in the enlarged diameter portion, wherein a clearance is formed between the outer circumferential surface of the shaft body portion and the inner circumferential surface of the bore body portion to limit the radial displacement of the output shaft and at the same time to allow the shaft body portion to rotate and slide within the bore body portion, while a larger gap is formed between the outer circumferential surface of the flange portion and the inner circumferential surface of the enlarged diameter portion.

2. The electric valve according to claim 1, comprising a feed screw member connected to the output shaft within the through hole so as to be relatively movable in the vertical direction and so as to transmit the rotation of the output shaft, wherein a female thread is formed in the lower part of the through hole, and a male thread is formed on the outer circumferential surface of the feed screw member that screws into the female thread, and the rotational motion of the output shaft is converted into vertical motion of the feed screw member by the female thread and the male thread forming a feed screw.

3. The electric valve according to claim 1 or 2, wherein a lubricant is stored in the gap.

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