Motor-operated valve

Abstract

To provide a motor valve capable of controlling a flow rate at high accuracy while restraining leakage of fluid at the time of closing a valve.SOLUTION: A motor valve 1 has: a valve body 2 including a valve chamber VC housing a valve body unit 40 and having a valve seat; a can 3 coupled to the valve body; a rotor 57 of a rotary-driven motor; and a conversion mechanism 27 for displacing a driving part 22 in an axial line direction according to the rotation angle of the rotor. The valve body unit has a valve shaft 41 coupled to the driving part, and a valve body part 42 relatively movable to the valve shaft in the axial line direction and approaching to and separated from the valve seat. An elastic body 45 is arranged on one of the valve shaft and the valve body to surround the periphery of the valve seat, and a contact part approaching to and separated from the elastic body is arranged on the other of the valve shaft and the valve body.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a motor-operated valve. [Background technology]

[0002] Conventionally, motor-operated valves have been installed, for example, midway through a fluid piping system and used to open and close the fluid flow path and control the flow rate. For example, the motor-operated valve shown in Patent Document 1 uses a planetary gear reduction mechanism to increase the torque of a stepping motor attached to the valve body and transmit it to the valve element, thereby achieving precise flow rate control and sealing when the valve is closed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-155785 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, the motor-operated valve of Patent Document 1 is configured to open and close by moving a metal valve element toward and away from a metal valve seat. Therefore, if the valve is closed with a foreign object between the valve seat and the valve element, the foreign object may become caught and leave an indentation on the sealing surface of the valve seat or the valve element, which may result in fluid leakage when the valve is closed.

[0005] One solution to this problem is to use rubber for either the valve seat or the valve body, but if these materials are changed to rubber, they may become worn (reduced in volume) due to heat or changes over time, which could change the gap between the valve seat and the valve body when the valve is open, affecting the adjustment of the fluid flow rate or making flow rate control difficult.

[0006] The present invention has been made in view of the above-mentioned problems, and has an object to provide an electrically operated valve that can achieve highly accurate flow rate control while suppressing fluid leakage when the valve is closed. [Means for solving the problem]

[0007] The motor-operated valve of the present invention comprises: a valve body including a valve chamber that houses a valve disc unit and has a valve seat; a can coupled to the valve body; a rotor of a motor that is driven to rotate; a conversion mechanism that displaces the drive unit in the axial direction in accordance with the rotation angle of the rotor, the valve element unit includes a valve stem connected to the drive unit, and a valve element portion that is movable relative to the valve stem in an axial direction and moves toward and away from the valve seat, An elastic body is disposed on one of the valve stem and the valve body so as to surround the periphery of the valve seat, and an abutment portion that comes into contact with and separates from the elastic body is disposed on the other of the valve stem and the valve body. 、 When the valve stem abuts against the valve body portion seated on the valve seat, the valve stem is positioned closest to the valve seat, When the valve body portion is separated from the valve seat, a fluid can flow from the valve seat toward the abutment portion. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a motor-operated valve that can achieve highly accurate flow rate control while suppressing fluid leakage when the valve is closed. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a vertical cross-sectional view showing a closed state of a motor-operated valve according to a first embodiment. [Figure 2] FIG. 2 is a diagram showing the vicinity of the valve seat of the motor-operated valve in the fully closed region. [Figure 3] FIG. 3 is a diagram showing the vicinity of the valve seat of the motor-operated valve in the boundary region. [Figure 4] FIG. 4 is a diagram showing the vicinity of the valve seat of the motor-operated valve in the flow rate control region. [Figure 5] FIG. 5 is a flow rate characteristic diagram of the motor-operated valve of the first embodiment. [Figure 6] FIG. 6 is a view showing the periphery of the valve seat of the motor-operated valve of the second embodiment in the fully closed valve region. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the motor-operated valve according to the present invention will be described with reference to the drawings. In this specification, the rotor side will be described as the upper side, and the valve body side will be described as the lower side. The paradox planetary gear reduction mechanism is a type of planetary gear reduction mechanism.

[0011] [First embodiment] Fig. 1 is a longitudinal cross-sectional view showing a motor-operated valve 1 according to a first embodiment of the present invention in a closed state, and Figs. 2 to 4 are enlarged plan views showing the vicinity of the valve seat of the motor-operated valve 1 according to the first embodiment. The motor-operated valve 1 of this embodiment is used, for example, to adjust the flow rate of refrigerant in a refrigeration cycle. The axis of the motor-operated valve 1 is designated as L.

[0012] The motor-operated valve 1 of this embodiment is composed of a valve body 2 having a valve seat 2a formed inside a valve chamber VC, a metallic cylindrical can 3 with a top that is fixed to the valve body 2 via an annular body 31, a stepping motor consisting of a stator (not shown) mounted outside the can 3 and a rotor 57 mounted inside the can 3, a reduction mechanism 6 that reduces the speed of the rotational torque of the rotor 57 and transmits it, a valve element unit 40 that is placed inside the valve chamber VC and moves toward and away from the valve seat 2a to control the amount of fluid passing through, and a screw drive member (drive unit) 22 that converts the rotational motion of the output gear of the reduction mechanism 6 into linear motion via a screw feed mechanism (conversion mechanism) 27 to drive the valve element unit 40.

[0013] A valve port 16 communicating with the valve chest VC is formed in the valve body 2 along the axis L, and a first pipe T1 is connected to the valve port 16 side by brazing or the like, and a second pipe T2 is also connected by brazing or the like so as to communicate with an opening 18 formed in the side surface of the valve chest VC. The axis of the second pipe T2 is designated O. The axis O is perpendicular to the axis L.

[0014] A threaded bearing member 13 having a female thread portion 13a formed at the central lower end side is inserted into the upper portion of the valve chamber VC of the valve body 2 and fixed to the valve body 2 by press-fitting or the like.

[0015] A resin shaft support portion 81 is attached to the inside of the upper end of the can 3. More specifically, the shaft support portion 81 is composed of a cylindrical portion 81a whose upper end surface abuts against the underside of the can 3 and a flange portion 81b that is arranged around the cylindrical portion 81a and whose outer periphery abuts against the inner periphery of the can 3. A through hole 81c that passes through vertically is formed in the center of the shaft support portion 81 coaxially with the axis L. The inner diameter of the through hole 81c is approximately equal to the outer diameter of the support shaft 8.

[0016] The reduction mechanism 6 comprises a sun gear 61 formed integrally with the rotor support member 56 on the inner peripheral side of the rotor 57, a fixed ring gear 62 fixed via a thin-walled cylindrical body 66 fixed to the top of the valve body 2 and extending upward, a planetary gear 63 arranged between the sun gear 61 and the fixed ring gear 62 and meshing with them, a carrier 64 that rotatably supports the planetary gear 63, and a cylindrical output gear member 65 with a bottom and provided with teeth on its inner peripheral that mesh with the planetary gear 63, and these together form a paradox planetary gear reduction mechanism. The number of teeth of the fixed ring gear 62 is set to be different from the number of teeth of the output gear member 65.

[0017] The metallic support shaft 8 passes through the rotor support member 56 and the sun gear 61 and is held rotatably together with them. The upper end of the support shaft 8 is fitted into a through-hole 81c of a shaft support part 81 attached to the can 3, and is supported so as to be movable in the rotational direction and the direction of the axis L.

[0018] The upper part of the stepped cylindrical output shaft portion 29 formed on the upper part of the screw drive member 22 is press-fitted into the center of the bottom of the output gear member 65. The lower end of the support shaft 8 is press-fitted into the upper opening of this output shaft portion 29, and the output gear member 65, support shaft 8, and output shaft portion 29 are configured to rotate integrally.

[0019] A male threaded portion 22a formed on the lower part of the screw driving member 22 is threadedly engaged with the female threaded portion 13a of the screw bearing member 13. The rotational motion of the output gear member 65 (i.e., the rotor 57) is converted into linear motion along the axis L by a screw feed mechanism (conversion mechanism) 27 consisting of the male threaded portion 22a and the female threaded portion 13a.

[0020] A slit 29a is formed at the lower end of the output shaft 29, and a blade 22b protruding along the axis L is formed at the upper end of the screw drive member 22, with the slit 29a and the blade 22b slidably engaging with each other. As a result, the output shaft 29 is connected to the screw drive member 22 so as to be rotatable together with it, and when the output gear member 65 (rotor 57) rotates, the output shaft 29 and the screw drive member 22 rotate together with it, but are also capable of linear movement along the axis L relative to each other.

[0021] When the output gear member 65 (rotor 57) rotates, the output gear member 65 and the screw drive member 22 rotate together and move linearly along the axis L relative to the valve body 2. As the output gear member 65 moves up and down, the carrier 64 and the planetary gear 63 mounted on the bottom surface of the output gear member 65 also move up and down together with the support shaft 8.

[0022] The lower end of a ball joint 25 consisting of a ball 23 and a ball seat 24 abuts against the upper end of a hollow cylindrical spring support member 28, which is coaxially press-fitted onto the upper end of a valve stem 41 of a valve body unit 40. A cylindrical spring case 19, arranged around the valve body unit 40 and the spring support member 28, comprises an enlarged diameter portion 19a, a reduced diameter portion 19b, and an upper end flange portion 19c, which extends radially outward from the upper end of the enlarged diameter portion 19a. The upper end flange portion 19c engages with an inner circumferential step of the valve body 2 and is fixed and held by a threaded bearing member 13. The reduced diameter portion 19b slidably holds the outer periphery of the valve stem 41 of the valve body unit 40.

[0023] The compression coil spring 26 is positioned in a compressed state with its lower end abutting against the step between the enlarged diameter portion 19a and the reduced diameter portion 19b and its upper end engaging with the spring support member 28, thereby biasing the valve body unit 40 in the direction of constantly opening the valve.

[0024] The linear motion of the screw drive member 22 is transmitted to the axial valve body unit 40 via the ball joint 25 and the spring support member 28, whereby the valve body unit 40 is guided by the spring case 19 and moves in the direction of the axis L.

[0025] The valve body unit 40 comprises a metal valve stem 41 and a metal valve body portion 42. The valve stem 41 has a small diameter portion 41a and a large diameter portion 41b that is larger than the small diameter portion 41a, and these portions are arranged coaxially. The upper end of the small diameter portion 41a is press-fitted into the inner periphery of the spring support member 28, and the outer periphery of the small diameter portion 41a is slidably fitted into the inner periphery of the reduced diameter portion 19b. A cylindrical recess 41c is formed in the lower end of the large diameter portion 41b (the surface facing the valve seat 2a).

[0026] In Figures 2 to 4, the lower end of the recess 41c is formed with a first inner peripheral portion 41d having an expanded diameter and a second inner peripheral portion 41e having a larger diameter than the first inner peripheral portion 41d, and the thin-walled peripheral wall of the second inner peripheral portion 41e forms a crimped portion 41f.

[0027] The approximately cylindrical valve body portion 42 has a first cylindrical portion 42a with an outer diameter smaller than the inner diameter of the recess 41c, a flange portion 42b with an outer diameter approximately the same as the inner diameter of the recess 41c, a second cylindrical portion 42c with an outer diameter larger than the outer diameter of the first cylindrical portion 42a, and a truncated conical tapered portion 42d whose diameter decreases as it extends downward, all of which are arranged coaxially.

[0028] A coil spring 44 is disposed between the inner periphery of the recess 41c and the first cylindrical portion 42a, with its upper end abutting against the bottom surface of the recess 41c and its lower end abutting against the upper surface of the flange portion 42b. The coil spring 44 biases the valve body portion 42 downward against the bottom surface of the recess 41c.

[0029] A thin-walled cylindrical retaining member 43 is press-fitted into the first inner peripheral portion 41d. A gap is formed between the inner periphery of the retaining member 43 and the second cylindrical portion 42c of the valve body portion 42.

[0030] With the upper end of the retaining member 43 abutting against the step between the first inner circumferential portion 41d and the second inner circumferential portion 41e, an annular space is formed between the outer periphery of the retaining member 43 and the inner periphery of the second inner circumferential portion 41e, and an annular elastic body 45 made of rubber or resin is attached to this space. When attached to this space, the elastic body 45 elastically deforms, thereby closely adhering to the outer periphery of the retaining member 43 and the inner periphery of the second inner circumferential portion 41e. The material of the elastic body 45 can be, but is not limited to, HNBR or PTFE.

[0031] Before the valve disc unit 40 is assembled, the crimped portion 41f of the valve shaft 41 is cylindrical. During assembly, the coil spring 44 is placed around the first tubular portion 42a of the valve disc portion 42, and while maintaining this state, the valve disc portion 42 is pressed toward the recess 41c of the valve shaft 41. Furthermore, the retaining member 43 is press-fitted into the first inner circumferential portion 41d. The elastic body 45 is then placed between the outer periphery of the retaining member 43 and the inner periphery of the second inner circumferential portion 41e, and the lower end of the crimped portion 41f is plastically deformed radially inward to assemble the valve disc unit 40. The elastic body 45 may be attached to the valve shaft 41 using an adhesive.

[0032] The metal valve body 2 has an edge-shaped valve seat 2a at the intersection of the bottom surface of the valve chamber VC and the valve port 16. The tapered portion 42d of the valve body 42 can be seated on the valve seat 2a around its entire periphery.

[0033] The valve body 2 is disposed so as to surround the periphery of the valve seat 2a and has an annular protrusion (contact portion) 2b that protrudes upward from the bottom surface of the valve chamber VC. The protrusion 2b has a tapered inner circumferential surface 2c that increases in diameter as it extends upward, and a cylindrical outer circumferential surface 2d, with its upper end 2e, which has a narrower radial width, being able to contact an elastic body 45 around its entire periphery radially outward of the valve seat 2a (on the valve chamber VC side).

[0034] (Operation of the motor-operated valve) Fig. 5 is a flow rate characteristic diagram for the motor-operated valve of this embodiment, and is shown in a graph with the flow rate on the vertical axis and the valve opening (axial position of the valve stem 41) on the horizontal axis, although the scale of the vertical axis may differ from the actual scale. The flow rate characteristic diagram in Fig. 5 also shows a schematic diagram showing the relative positional relationship between the valve body portion 42 and the valve seat 2a. Here, the second pipe T2 side is the high-pressure side, and the first pipe T1 side is the low-pressure side, but the second pipe T2 side may be the low-pressure side, and the first pipe T1 side may be the high-pressure side.

[0035] 2, the valve stem 41 of the valve body unit 40 is in the lowest position, and with the coil spring 44 compressed, the bottom surface of the recess 41c abuts against the upper end of the valve body portion 42. As a result, the downward pressing force applied by the valve stem 41 causes the outer peripheral surface of the tapered portion 42d to seat on the valve seat 2a, and the upper end 2e of the protrusion portion 2b abuts against the lower surface of the elastic body 45. There is a gap between the lower surface of the flange portion 42b of the valve body portion 42 and the upper end of the retaining member 43.

[0036] At this time, the lower surface of the elastic body 45 elastically deforms to an appropriate degree, so that the outer surface of the tapered portion 42d can be seated on the valve seat 2a and the upper end 2e of the protrusion portion 2b can be maintained in contact with the lower surface of the elastic body 45, regardless of the part precision.

[0037] When the metal valve element 42 seats on the metal valve seat 2a, a small gap may form between them, which may result in fluid leakage. According to this embodiment, even if a small gap forms between the valve element 42 and the valve seat 2a in the closed state, the upper end 2e of the protrusion 2b remains in contact with the lower surface of the elastic body 45, preventing fluid from flowing from the valve chamber VC toward the valve seat 2a. This state is called the fully closed region A shown in FIG. 5.

[0038] In the fully closed valve region A, the fluid is prevented from flowing from the valve chest VC toward the valve port 16. This restricts the movement of the fluid between the second pipe T2 and the first pipe T1.

[0039] When the rotor 57 of the stepping motor is rotationally driven by supplying power to the stator in the fully closed valve region A, the rotational torque of the rotor 57 is transmitted to the sun gear 61 of the reduction mechanism 6 via the rotor support member 56, and the rotational torque reduced at a predetermined reduction ratio is output from the output gear member 65. The rotational torque of the output gear member 65 is transmitted to the output shaft portion 29.

[0040] The rotational motion of the output shaft 29 is converted into linear motion by the screw feed mechanism 27, causing the output shaft 29 to rise axially together with the valve stem 41 of the valve disc unit 40. As the valve stem 41 rises, the elastic body 45 also rises, but as the elastic body 45 rises, the abutting portion of the upper end 2e of the protrusion 2b returns from elastic deformation. However, as long as the abutting state with the upper end 2e is maintained, fluid is prevented from flowing from the valve chamber VC toward the valve port 16.

[0041] As the valve shaft 41 rises, the upper end of the valve body portion 42 moves away from the bottom surface of the recess 41c, but because the valve body portion 42 is pressed downward against the valve shaft 41 by the coil spring 44, the valve body portion 42 remains seated against the valve seat 2a.

[0042] 3, when the valve stem 41 rises to the first position P1, the lower surface of the elastic body 45 moves away from the upper end 2e of the protrusion 2b, ending the fully closed valve region A. This allows the fluid in the valve chamber VC to move over the protrusion 2b toward the valve seat 2a, but the pressing force of the coil spring 44 keeps the valve body 42 seated on the valve seat 2a.

[0043] At this time, if there is a small gap between the valve body 42 and the valve seat 2a, fluid will flow from the valve chamber VC to the valve port 16 through the gap, but the amount of fluid will be small. This state is called boundary region B.

[0044] The valve stem 41 further rises, and after the lower surface of the flange portion 42b of the valve disc portion 42 comes into contact with the upper end of the retaining member 43, the valve disc portion 42 rises together with the valve stem 41. When the valve stem 41 rises to the second position P2, the valve disc portion 42 separates from the valve seat 2a, ending the boundary region B and starting the flow rate control region C. In the flow rate control region C shown in Figure 4, the fluid flows from the valve chest VC toward the valve port 16 at a flow rate according to the gap between the valve disc portion 42 and the valve seat 2a, which is determined by the axial position of the valve stem 41. This allows the movement of a predetermined flow rate of fluid between the second pipe T2 and the first pipe T1.

[0045] When the stator is energized with reverse characteristics from the open valve state, the rotor 57 rotates in the opposite direction, so that the valve stem 41 is lowered in the reverse operation to that described above, causing the valve body portion 42 to seat on the valve seat 2a, and then the upper end 2e of the protrusion portion 2b to abut against the underside of the elastic body 45, thereby returning the valve to the fully closed region A.

[0046] According to this embodiment, after the valve body 42 is seated on the valve seat 2a, the bottom surface of the recess 41c abuts against the upper end of the valve body 42, which prevents excessive deformation of the elastic body 45 against which the upper end 2e of the protrusion 2b abuts, thereby preventing the elastic body 45 from becoming worn, and ensuring a stable, long-term, fully closed valve region A. Even if the elastic body 45 deforms due to changes over time, for example, the flow of fluid can be blocked as long as the elastic body 45 is elastically deformed by the abutment of the protrusion 2b.

[0047] Furthermore, if foreign matter is mixed in the fluid, it is highly likely that it will become caught between the upper end 2e of the protrusion 2b and the elastic body 45. In such a case, the elastic body 45 will elastically deform, preventing fluid leakage even if the foreign matter becomes caught between the upper end 2e and the elastic body 45. Furthermore, when the upper end 2e and the elastic body 45 separate, the foreign matter is swept away by the fluid, preventing the foreign matter from remaining in the same place. Therefore, it is possible to provide an electrically operated valve 1 that can achieve high-precision flow rate control while suppressing fluid leakage when the valve is closed.

[0048] (Second embodiment) Fig. 6 is a view similar to Fig. 2, showing a closed state of a motor-operated valve according to a modified example of the second embodiment. In this embodiment, the configurations of the valve shaft 41A of the valve body unit 40A and the valve body 2A are different, and the other configurations are the same as those of the above-described embodiment, so duplicated explanations will be omitted.

[0049] The valve stem 41A of this embodiment has an annular protrusion 41Ag at its lower end. The inner circumferential surface of the protrusion 41Ag is formed by a first inner circumferential portion 41d into which the retaining member 43 is press-fitted, extending to the lower end. The outer circumferential surface of the protrusion 41Ag is a tapered outer circumferential surface 41Ah whose diameter decreases downward from near the lower end. The protrusion 41Ag further has an annular lower end 41Af.

[0050] The valve body 2A has an annular groove 2Af in the bottom surface of the valve chamber VC around the valve seat 2a. An elastic body 45 is disposed in the annular groove 2Af.

[0051] In this embodiment as well, in the fully closed valve region A, the outer peripheral surface of the tapered portion 42d is seated on the valve seat 2a, and the lower end 41Af of the protruding portion 41Ag abuts on the upper surface of the elastic body 45.

[0052] On the other hand, the valve stem 41 A When the protrusion 41Ag rises to the first position P1 (see FIG. 5), the lower end 41Af of the protrusion 41Ag separates from the upper surface of the elastic body 45, the fully closed valve region A ends, and the boundary region B begins. In the boundary region B, the fluid in the valve chamber VC can move beyond the protrusion 41Ag toward the valve seat 2a, but the pressure of the coil spring 44 prevents the valve body 41Af from closing. 42 The seating state between the valve seat 2a and the valve valve 2 is maintained.

[0053] When the valve stem 41A further rises and reaches the second position P2 (see FIG. 5), the valve body 42 separates from the valve seat 2a, ending the boundary region B and starting the flow rate control region C. In the flow rate control region C, the fluid flows from the valve chamber VC toward the valve port 16 at a flow rate that corresponds to the gap between the valve body 42 and the valve seat 2a. This allows the movement of a predetermined flow rate of the fluid between the second pipe T2 and the first pipe T1.

[0054] The present invention is not limited to the above-described embodiments. Any of the components of the above-described embodiments can be modified within the scope of the present invention. Furthermore, any of the components can be added or omitted from the above-described embodiments. For example, a reduction mechanism consisting of a gear pair can be provided instead of the planetary gear reduction mechanism. Alternatively, the present invention can also be applied to an electrically operated valve that does not have a reduction mechanism.

[0055] This specification includes the disclosure of the following inventions. (First aspect) a valve body including a valve chamber that houses a valve disc unit and has a valve seat; a can coupled to the valve body; a rotor of a motor that is driven to rotate; a conversion mechanism that displaces the drive unit in the axial direction in accordance with the rotation angle of the rotor, the valve element unit includes a valve stem connected to the drive unit, and a valve element portion that is movable relative to the valve stem in an axial direction and moves toward and away from the valve seat, an elastic body is disposed on one of the valve stem and the valve body so as to surround the periphery of the valve seat, and an abutment portion that comes into contact with and moves away from the elastic body is disposed on the other of the valve stem and the valve body; A motor-operated valve characterized by:

[0056] (Second aspect) an elastic body is disposed on the valve stem, and an annular protrusion is formed on the valve body as the abutment portion; The motor-operated valve according to the first aspect,

[0057] (Third aspect) an elastic body is disposed in the valve body, and an annular protrusion is formed on the valve stem as the abutment portion; The motor-operated valve according to the first aspect,

[0058] (Fourth aspect) a coil spring that biases the valve body portion in a direction toward the valve seat relative to the valve stem; The motor-operated valve according to any one of the first to third aspects, characterized in that:

[0059] (Fifth aspect) the valve body portion is disposed in a recess of the valve stem facing the valve seat, A retaining member is disposed in the recess to prevent the valve body from being removed from the recess. A fourth aspect of the motor-operated valve is characterized in that:

[0060] (Sixth aspect) When the valve stem moves in a direction away from the valve seat, the elastic body moves away from the abutment portion, and then the valve body moves away from the valve seat. The motor-operated valve according to any one of the first to fifth aspects, characterized in that:

[0061] (Seventh aspect) After the valve body portion is separated from the valve seat, the fluid flowing through the gap between the valve body portion and the valve seat is controlled in accordance with the axial position of the valve stem. The motor-operated valve according to any one of the first to sixth aspects, characterized in that: [Explanation of symbols]

[0062] 1. Motor-operated valve 2, 2A valve body 3 Can 40 Valve unit 41, 41A valve stem 42 Valve body 43 Stopper member 44 Coil spring 45 Elastic Body 6 Reduction mechanism 8 Support shaft VC valve chamber T1 First piping T2 Second piping

Claims

1. a valve body including a valve chamber that houses a valve disc unit and has a valve seat; a can coupled to the valve body; a rotor of a motor that is driven to rotate; a conversion mechanism that displaces the drive unit in the axial direction in accordance with the rotation angle of the rotor, the valve body unit includes a valve stem connected to the drive unit, and a valve body portion that is movable relative to the valve stem in an axial direction and moves toward and away from the valve seat, an elastic body is disposed on one of the valve stem and the valve body so as to surround the periphery of the valve seat, and an abutment portion that moves toward and away from the elastic body is disposed on the other of the valve stem and the valve body; When the valve stem abuts against the valve body portion seated on the valve seat, the valve stem is positioned closest to the valve seat, When the valve body portion is separated from the valve seat, a fluid can flow from the valve seat toward the abutment portion. A motor-operated valve characterized by:

2. An elastic body is disposed on the valve stem, and an annular protrusion is formed on the valve body as the abutment portion.

2. The motor-operated valve according to claim 1.

3. an elastic body is disposed in the valve body, and an annular protrusion is formed on the valve stem as the abutment portion; 2. The motor-operated valve according to claim 1.

4. a coil spring that biases the valve body portion in a direction toward the valve seat relative to the valve stem; 2. The motor-operated valve according to claim 1.

5. the valve body portion is disposed in a recess of the valve stem facing the valve seat, A retaining member is disposed in the recess to prevent the valve body from being removed from the recess.

5. The motor-operated valve according to claim 4.

6. When the valve stem moves in a direction away from the valve seat, the elastic body moves away from the abutment portion, and then the valve body moves away from the valve seat.

2. The motor-operated valve according to claim 1.

7. After the valve body portion is separated from the valve seat, the fluid flowing through the gap between the valve body portion and the valve seat is controlled in accordance with the axial position of the valve stem.

7. The motor-operated valve according to claim 6.

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