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 has: a valve body including a valve chamber housing a valve body unit and having a valve seat; a can coupled to the valve body; a rotor of a rotary-driven motor; and a conversion mechanism for displacing a driving part in an axial line direction according to the rotation angle of the rotor. The valve body unit has a valve shaft coupled to the driving part, and a valve body part relatively movable to the valve shaft in the axial line direction and approaching to and separated from the valve seat. An elastic body 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 disc, but if these materials are changed to rubber, they will wear out (reduce in volume) due to heat and changes over time, which will change the gap between the valve seat and the valve disc when the valve is open, affecting the adjustment of the fluid flow rate or making flow control difficult.In addition, with motor-operated valves, the pressing force between the valve seat and the valve disc is relatively large when the valve is closed, so if either the valve seat or the valve disc is made of rubber, the rubber will deform excessively, and measures to address this will be necessary.

[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 body unit includes a valve stem connected to the drive unit, and a stopper and an elastic body connected to the valve stem, the elastic body is disposed opposite the valve seat so as to surround the periphery of the valve seat, When the valve stem moves in a direction toward the valve seat, the elastic body abuts against the valve seat, and then the stopper abuts against the engaging portion of the valve body. death, a high-pressure side pipe through which a high-pressure fluid flows and a low-pressure side pipe through which a low-pressure fluid flows are connected to the valve chamber; The valve body unit includes an inlet passage for introducing the high-pressure fluid, a back pressure chamber communicating with the inlet passage, and a supply passage communicating with the back pressure chamber for supplying the high-pressure fluid to a back surface of the elastic body facing the valve seat. It is characterized by: [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 an enlarged plan view showing the vicinity of the valve seat of the motor-operated valve according to the first embodiment. [Figure 3] FIG. 3(a) is a view similar to FIG. 2 showing the motor-operated valve in a closed state, and FIG. 3(b) is an enlarged view showing the vicinity of the valve seat 2a. [Figure 4]FIG. 4(a) is a view similar to FIG. 3(a) showing the state after the stopper has separated from the tapered outer periphery and before the valve opens, and FIG. 4(b) is an enlarged view of the vicinity of the valve seat. [Figure 5] FIG. 5(a) is a view similar to FIG. 3(a) showing the motor-operated valve in an open state, and FIG. 5(b) is an enlarged view showing the vicinity of the valve seat. [Figure 6] FIG. 6 is a graph showing flow rate characteristics in the motor-operated valve of this embodiment, with the vertical axis representing flow rate and the horizontal axis representing valve opening (the number of drive pulses corresponding to the axial position of the valve stem). [Figure 7] FIG. 7 is a vertical cross-sectional view of the motor-operated valve according to the second embodiment. [Figure 8] FIG. 8 is a view similar to FIG. 2, showing the motor-operated valve according to the second embodiment in a closed state. 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 Fig. 2 is an enlarged plan view 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 stopper 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.

[0026] In Figure 2, the stem 41 has a cylindrical recess 41c at the lower end of the large-diameter portion 41b (the surface facing the valve seat 2a). The recess 41c also has a first stem hole 41d at the center of its bottom, extending from the large-diameter portion 41b to the small-diameter portion 41a. The second stem hole 41f (first passage) is located above the first stem hole 41d. The second stem hole 41f has a smaller inner diameter than the first stem hole 41d, and the second stem hole 41f and the first stem hole 41d are connected via an upper tapered portion 41e, the diameter of which decreases as it extends upward. A communication hole 41g is located near the upper end of the second stem hole 41f and connects the outer periphery of the small-diameter portion 41a. The lower end of the thin-walled peripheral wall of the recess 41c forms a crimped portion 41h.

[0027] The substantially cylindrical stopper 42 has a first outer circumferential portion 42a having a cylindrical shape with a diameter smaller than the inner diameter of the recess 41c, a second outer circumferential portion 42c having a cylindrical diameter larger than the first outer circumferential portion 42a, and a tapered outer circumferential portion 42d whose diameter decreases downward. Between the first outer circumferential portion 42a and the second outer circumferential portion 42c, an annular flange portion 42b having an outer diameter substantially the same as the inner diameter of the recess 41c is formed. The flange portion 42b has a plurality of through-holes (supply channels) 42f penetrating vertically.

[0028] A circumferential groove 42e is formed in the second outer peripheral portion 42c adjacent to the flange portion 42b. A ring-shaped elastic body 45 made of rubber or resin is attached to the circumferential groove 42e. The elastic body 45 elastically deforms when attached, thereby closely contacting the bottom surface of the circumferential groove 42e and the inner periphery of the recess 41c. The elastic body 45 may be made of, but is not limited to, HNBR or PTFE. Here, the upper surface of the elastic body 45 is the back side, and the lower surface of the elastic body 45 (the surface that seats on the valve seat 2a) is the front side.

[0029] The stopper 42 further has a cylindrical first inner circumferential portion 42h with the same diameter as the first stem hole 41d, and a cylindrical second inner circumferential portion (second passage) 42i with a smaller diameter than the first inner circumferential portion 42h below the first inner circumferential portion 42h. The first inner circumferential portion 42h opens to the upper end of the stopper 42 and faces the first stem hole 41d, while the second inner circumferential portion 42i opens to the lower end of the stopper 42 and communicates with the valve port 16. The first inner circumferential portion 42h and the second inner circumferential portion 42i are connected via a downward tapered portion 42j whose diameter decreases as it extends downward.

[0030] When the stopper 42 is assembled into the recess 41c, the top surface of the stopper 42 comes into close contact with the bottom surface of the recess 41c, and the first inner circumferential portion 42h and the first stem hole 41d are aligned. At this time, a sphere 43 serving as a switching valve is movably disposed in an internal space IC (also referred to as a connecting path) formed by the first inner circumferential portion 42h and the first stem hole 41d. As the sphere 43 moves downward within the internal space IC, it is engaged with the downward tapered portion 42j, sealing the upper end of the second inner circumferential portion 42i. As the sphere 43 moves upward, it is engaged with the upper tapered portion 41e, sealing the lower end of the second stem hole 41f.

[0031] When the stopper 42 is assembled to the recess 41c, an annular space is formed between the bottom surface of the recess 41c and the upper surface of the flange portion 42b, and between the inner periphery of the recess 41c and the first inner circumferential portion 42h, and this space is referred to as a back pressure chamber BC. A plurality of communication ports 42k are formed along the radial direction, connecting the vicinity of the upper end of the first inner circumferential portion 42h with the first outer circumferential portion 42a, and the back pressure chamber BC and the internal space IC are connected via the communication ports 42k.

[0032] Before the valve body unit 40 is assembled, the crimped portion 41h of the valve shaft 41 is cylindrical. During assembly, the sphere 43 is placed on the first inner peripheral portion 42h of the stopper 42, and the elastic body 45 is placed in the circumferential groove 42e, and the stopper 42 is inserted into the recess 41c of the valve shaft 41. Thereafter, the lower end of the crimped portion 41h is plastically deformed radially inward, thereby assembling the valve body unit 40.

[0033] The metal valve body 2 has a cylindrical valve sleeve 2b that extends upward around the valve port 16 at the bottom surface of the valve chamber VC. The upper end of the valve sleeve 2b forms the valve seat 2a, which can abut against the lower surface of the elastic body 45 over its entire circumference. The axial cross section of the valve seat 2a is preferably arc-shaped. The upper end of the valve port 16 forms the locking portion 2c, which can be abutted against the tapered outer periphery 42d of the stopper 42.

[0034] (Operation of the motor-operated valve) FIG. 3(a) is a view similar to FIG. 2 showing the motor-operated valve 1 in a closed state, and FIG. 3(b) is an enlarged view of the vicinity of the valve seat 2a. FIG. 4(a) is a view similar to FIG. 3(b) showing the state before the valve is opened after the stopper 42 has separated from the tapered outer periphery 42d, and FIG. 4(b) is an enlarged view of the vicinity of the valve seat 2a. FIG. 5(a) is a view similar to FIG. 3(b) showing the motor-operated valve 1 in an open state, and FIG. 5(b) is an enlarged view of the vicinity of the valve seat 2a. Although some components in FIGS. 3 to 5 are different in length from FIG. 2, they are similar. FIG. 6 is a flow rate characteristic diagram of the motor-operated valve of this embodiment, plotted on a graph with the flow rate on the vertical axis and the valve opening (the number of drive pulses corresponding to the 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 of FIG. 6 also includes a schematic diagram showing the open and closed states of the motor-operated valve 1. Here, the second pipe T2 side is the high-pressure side pipe, and the first pipe T1 side is the low-pressure side pipe.

[0035] 2 and 3, the valve stem 41 of the valve disc unit 40 is in the lowest position (position P1 in Figure 6), at which point the stopper 42 abuts against the locking portion 2c, and the lower surface of the elastic body 45 abuts against the valve seat 2a while elastically deforming. As a result, the fluid cannot move from the valve chamber VC beyond the valve seat 2a toward the valve port 16, and the valve is kept in a fully closed state.

[0036] Without the elastic body 45, the metal valve stem 41 would seat on the valve seat 2a, but a small gap would be formed between them, potentially resulting in fluid leakage. According to this embodiment, the elastic body 45 elastically deforms while abutting against the valve seat 2a, preventing fluid from flowing from the valve chamber VC toward the valve seat 2a. This limits fluid movement between the second pipe T2 and the first pipe T1. Even if a foreign object in the fluid becomes trapped between the elastic body 45 and the valve seat 2a, or is otherwise jammed, the fluid sweeps the foreign object away as the elastic body 45 separates from the valve seat 2a, and the elastic body 45 elastically returns to its original position, preventing valve closure from being obstructed.

[0037] 2 and 3, the high-pressure fluid in the valve chamber VC flows into the internal space IC through the gap between the inner periphery of the reduced diameter portion 19b of the spring case 19 and the outer periphery of the small diameter portion 41a, the communication hole 41g, and the second stem hole 41f. In other words, the gap between the inner periphery of the reduced diameter portion 19b and the outer periphery of the small diameter portion 41a, the communication hole 41g, and the second stem hole 41f serve as an introduction path for introducing the high-pressure fluid.

[0038] However, the lower end of the internal space IC (the end of the second passage) is sealed by the sphere 43, which prevents fluid from flowing from the internal space IC toward the valve port 16 (blocking the connection between the communication port and the second passage). In addition, the sphere 43 is urged toward the downward tapered portion 42j by the pressure difference between the internal pressure of the internal space IC and the internal pressure of the second inner circumferential portion 42i, and remains in that position.

[0039] When the sphere 43 remains in the downward tapered portion 42j, the second valve stem hole 41f communicates with the internal space IC, and the high-pressure fluid (pressure Pr1) in the internal space IC flows through the communication port 42k into the back pressure chamber BC. The back pressure chamber BC communicates with the lower surface of the flange portion 42b via the through-port 42f. Therefore, as shown in FIG. 3(b), the pressure Pr1 in the back pressure chamber BC is received by the upper surface of the elastic body 45.

[0040] On one hand, the lower surface of the elastic body 45 is exposed to the high-pressure fluid in the valve chamber VC outside the radial direction of the valve seat 2a, receives the pressure Pr1, and is also exposed to the low-pressure fluid on the valve port 16 side inside the radial direction of the valve seat 2a, thus receiving the pressure Pr2 (<Pr1). Here, assuming that the areas A of the upper and lower surfaces of the elastic body 45 are equal, and the lower surface area of the elastic body 45 outside the radial direction from the contact portion of the valve seat 2a is B, the force received by the upper surface of the elastic body 45 can be expressed as Pr1×A, while the force received by the lower surface of the elastic body 45 can be expressed as Pr1×B + Pr2(A - B). Representing the vertical force F acting on the elastic body 45 with the downward direction as positive, we get F = Pr1×A - (Pr1×B + Pr2(A - B)) = Pr1(A - B) - Pr2(A - B). Here, since Pr2 < Pr1 based on the prerequisite conditions, F > 0, meaning that the force received by the upper surface of the elastic body 45 is greater. Therefore, due to the pressure difference between the upper and lower surfaces of the elastic body 45, the elastic body 45 is pressed against the valve seat 2a, so it is suppressed from separating from the valve seat 2a, and even if sagging occurs in the elastic body 45 due to heat or the like, the sealing performance will not be lost.

[0041] However, if the entire lower surface of the elastic body 45 received the pressure Pr2, the force acting on the elastic body 45 would be F = (Pr1 - Pr2)A, and the force received on the upper surface side of the elastic body 45 would become too large, which may cause excessive sagging or the like of the elastic body 45. According to this embodiment, by exposing a part of the lower surface of the elastic body 45 to the high-pressure fluid on the valve chamber VC side, the pressures applied to the upper and lower surfaces of the elastic body 45 can be canceled, and excessive sagging or the like of the elastic body 45 can be suppressed.

[0042] When power is supplied to the stator from the fully closed valve state to rotationally drive the rotor 57 of the stepping motor, the rotational torque of the rotor 57 is transmitted to the sun gear 61 of the speed 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.

[0043] 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 stopper 42 moves away from the engaging portion 2c (position P2 in FIG. 6), as shown in FIG. 4, but the elastic body 45 remains in contact with the valve seat 2a. While the state in which the elastic body 45 is in contact with the valve seat 2a is maintained (positions P1 to P2 in FIG. 6), the fluid is prevented from flowing from the valve chamber VC toward the valve port 16.

[0044] As the valve stem 41 rises further, the elastic body 45 moves away from the valve seat 2a, and the fluid begins to flow from the valve chest VC to the valve orifice 16 through the gap between the elastic body 45 and the valve seat 2a. From position P2 to position P3 in Figure 6, the cross-sectional area of ​​the gap between the elastic body 45 and the valve seat 2a is the smallest in the flow path from the valve chest VC to the valve orifice 16, and therefore the flow rate of the fluid increases according to the gap between the elastic body 45 and the valve seat 2a.

[0045] However, after the valve stem 41 reaches position P3, as shown in Figure 5(b), the cross-sectional area of ​​the gap between the inner periphery of the valve cylinder portion 2b and the second outer periphery 42c of the stopper 42 becomes the smallest in the flow path from the valve chest VC to the valve port 16, and because both are cylindrical, the gap between the valve cylinder portion 2b and the second outer periphery 42c changes very little even when the valve stem 41 rises. Therefore, the flow rate of the fluid from the valve chest VC to the valve port 16 remains approximately constant.

[0046] When the valve stem 41 reaches position P4, the tapered outer periphery 42d is positioned radially inward of the valve cylinder portion 2b. Therefore, as the valve stem 41 rises, the gap between the valve cylinder portion 2b and the tapered outer periphery 42d changes. Fluid flows from the valve chamber VC toward the valve port 16 at a flow rate determined by the gap between the valve cylinder portion 2b and the tapered outer periphery 42d of the stopper 42, which is determined by the axial position of the valve stem 41, up to position P5, the maximum valve open position. This allows a predetermined flow rate of fluid to move between the second pipe T2 and the first pipe T1. Therefore, this embodiment provides a motor-operated valve 1 that can achieve highly accurate flow rate control while suppressing fluid leakage when the valve is closed.

[0047] When the stator is supplied with reverse current from the open valve state, the rotor 57 rotates in the opposite direction, which moves the valve stem 41 downward in the opposite direction to the above, causing the lower surface of the elastic body 45 to abut against the valve seat 2a, and then seating the stopper 42 on the engaging portion 2c. This allows the downward biasing force from the valve stem 41 to be supported by the stopper 42, thereby preventing excessive deformation of the elastic body 45.

[0048] This embodiment can also be applied to a case where the first pipe T1 side is the high-pressure pipe and the second pipe T2 side is the low-pressure pipe (a case where the valve chest VC is filled with a low-pressure fluid). In this case, the high-pressure fluid introduced from the valve port 16 through the second inner peripheral portion 42i serving as the first passage pushes up the sphere 43 (connecting the first passage and the internal space IC), thereby allowing the high-pressure fluid to enter the internal space IC. The sphere 43 pushed up by the high-pressure fluid is engaged with the upper tapered portion 41e, as shown by the dashed line in FIG. 2, and seals the lower end of the second valve stem hole 41f serving as the second passage (disconnecting the communication port and the second passage).

[0049] Therefore, the high-pressure fluid introduced into the internal space IC via the second inner peripheral portion 42i flows through the communication port 42k into the back pressure chamber BC and applies pressure to the upper surface of the elastic body 45. Furthermore, the lower surface of the elastic body 45 is exposed to the low-pressure fluid in the valve chamber VC radially outward from the valve seat 2a, and is exposed to the high-pressure fluid on the valve orifice 16 side radially inward from the valve seat 2a. Therefore, as described above, the pressure difference between the upper and lower surfaces of the elastic body 45 is kept low, and excessive sagging of the elastic body 45 can be suppressed.

[0050] (Second embodiment) Fig. 7 is a longitudinal cross-sectional view of a motor-operated valve 1A according to a second embodiment. Fig. 8 is a view similar to Fig. 2, showing the motor-operated valve according to the second embodiment in a closed state. In this embodiment, a valve body unit 40A is provided with a shielding device 43A that functions as a switching valve instead of a sphere, and the shapes of the valve stem 41A and the stopper 42A are different accordingly. The rest of the configuration is the same as in the above-mentioned embodiment, so repeated explanation will be omitted.

[0051] The shielding device 43A has an upper shielding plate 43Aa, a lower shielding plate 43Ab, and a coil spring 43Ac arranged between the upper shielding plate 43Aa and the lower shielding plate 43Ab, and is arranged in the internal space IC.

[0052] The stem 41A does not have an upper tapered portion, and the first stem hole 41d and the second stem hole 41f are directly connected, with an upper step 41Ae formed at their intersection perpendicular to the axis L. Moreover, the stopper 42A has a first inner circumferential portion 42h and a second inner circumferential portion 42i directly connected, with a lower step 42Aj formed at their intersection perpendicular to the axis L.

[0053] When the second pipe T2 side is the high-pressure side and the first pipe T1 is the low-pressure side pipe, the high-pressure fluid introduced into the second stem hole 41f, which serves as the first passage of the introduction path, presses the upper shielding plate 43Aa downward against the biasing force of the coil spring 43Ac and separates it from the upper step 41Ae, connecting the second stem hole 41f to the internal space IC. As a result, the high-pressure fluid is introduced into the internal space IC from the second stem hole 41f through the gap between the upper step 41Ae and the upper shielding plate 43Aa.

[0054] When high-pressure fluid is introduced from the valve chamber VC into the internal space IC, a pressure difference occurs between the internal pressure of the internal space IC and the internal pressure of the second inner circumferential portion 42i, so that the lower shielding plate 43Ab abuts against the lower step portion 42Aj, sealing the upper end of the second inner circumferential portion 42i, which is the second passage (blocking the connection between the communication port and the second passage). This makes the internal pressure of the back pressure chamber BC equal to the internal pressure of the valve chamber VC and the internal space IC, and makes it possible to adjust the pressure applied to the elastic body 45, as in the first embodiment.

[0055] In contrast, when the first pipe T1 is the high-pressure pipe and the second pipe T2 is the low-pressure pipe, the high-pressure fluid introduced into the second inner circumferential portion 42i serving as the first passage of the introduction path presses the lower shielding plate 43Ab upward against the biasing force of the coil spring 43Ac and separates from the lower step portion 42Aj, thereby connecting the second inner circumferential portion 42i to the internal space IC. As a result, the high-pressure fluid is introduced into the internal space IC from the second inner circumferential portion 42i through the gap between the lower step portion 42Aj and the lower shielding plate 43Ab.

[0056] When high-pressure fluid is introduced from the valve chamber VC into the internal space IC, a pressure difference occurs between the internal pressure of the internal space IC and the internal pressure of the second stem hole 41f, so that the upper shielding plate 43Aa abuts against the upper step 41Ae, sealing the lower end of the second stem hole 41f serving as the second passage (blocking the connection between the communication port and the second passage). This makes the internal pressure of the back pressure chamber BC equal to the internal pressures of the valve chamber VC and the internal space IC, and the force applied to the elastic body 45 can be adjusted as in the first embodiment.

[0057] 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 may 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.

[0058] 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 body unit includes a valve stem connected to the drive unit, and a stopper and an elastic body connected to the valve stem, the elastic body is disposed opposite the valve seat so as to surround the periphery of the valve seat, When the valve stem moves in a direction toward the valve seat, the elastic body abuts against the valve seat, and then the stopper abuts against a locking portion of the valve body. A motor-operated valve characterized by:

[0059] (Second aspect) When the valve stem moves in a direction away from the valve seat, the stopper moves away from the engaging portion, and then the elastic body moves away from the valve seat. The motor-operated valve according to the first aspect,

[0060] (Third aspect) the stopper has a tapered outer periphery that abuts against the locking portion, After the elastic body separates from the valve seat, the fluid flowing through the gap between the tapered outer periphery and the locking portion is controlled in accordance with the axial position of the valve stem. The motor-operated valve according to the first or second aspect,

[0061] (Fourth aspect) a high-pressure side pipe through which a high-pressure fluid flows and a low-pressure side pipe through which a low-pressure fluid flows are connected to the valve chamber; The valve body unit includes an inlet passage for introducing the high-pressure fluid, a back pressure chamber communicating with the inlet passage, and a supply passage communicating with the back pressure chamber for supplying the high-pressure fluid to a back surface of the elastic body facing the valve seat. The motor-operated valve according to any one of the first to third aspects, characterized in that:

[0062] (Fifth aspect) a part of a front surface of the elastic body on the valve seat side is exposed to the high-pressure fluid; A fourth aspect of the motor-operated valve is characterized in that:

[0063] (Sixth aspect) a first passage connected to the high-pressure side pipe, a second passage connected to the low-pressure side pipe, a connection passage connected to the first passage and the second passage, and a communication port connecting the connection passage to the back pressure chamber, a switching valve is provided in the connection path to connect the first passage to the communication port and to disconnect the second passage to the communication port; The motor-operated valve according to the fourth or fifth aspect,

[0064] (Seventh aspect) The switching valve has a sphere that moves within the connecting passage between an end of the first passage and an end of the second passage in response to a pressure difference between the high-pressure fluid and the low-pressure fluid. A sixth aspect of the motor-operated valve is characterized in that:

[0065] (Eighth aspect) The switching valve includes a pair of shielding plates and a spring that biases the shielding plates in a direction away from each other, one of the shielding plates opens the first passage and the other shielding plate blocks the second passage in response to a pressure difference between the high-pressure fluid and the low-pressure fluid; A sixth aspect of the motor-operated valve is characterized in that: [Explanation of symbols]

[0066] 1. Motor-operated valve 2, 2A valve body 3 Can 40 Valve unit 41, 41A valve stem 42, 42A stopper 43 Sphere 43A Shielding device 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 stopper and an elastic body connected to the valve stem, the elastic body is disposed opposite the valve seat so as to surround the periphery of the valve seat, When the valve stem moves in a direction toward the valve seat, the elastic body abuts against the valve seat, and then the stopper abuts against a locking portion of the valve body, a high-pressure side pipe through which a high-pressure fluid flows and a low-pressure side pipe through which a low-pressure fluid flows are connected to the valve chamber; The valve body unit includes an inlet passage for introducing the high-pressure fluid, a back pressure chamber communicating with the inlet passage, and a supply passage communicating with the back pressure chamber for supplying the high-pressure fluid to a back surface of the elastic body facing the valve seat. A motor-operated valve characterized by:

2. When the valve stem moves in a direction away from the valve seat, the stopper moves away from the engaging portion, and then the elastic body moves away from the valve seat.

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

3. the stopper has a tapered outer periphery that abuts against the locking portion, After the elastic body separates from the valve seat, the fluid flowing through the gap between the tapered outer periphery and the locking portion is controlled in accordance with the axial position of the valve stem.

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

4. a part of a front surface of the elastic body on the valve seat side is exposed to the high-pressure fluid; 2. The motor-operated valve according to claim 1.

5. a first passage connected to the high-pressure side pipe, a second passage connected to the low-pressure side pipe, a connection passage connected to the first passage and the second passage, and a communication port connecting the connection passage to the back pressure chamber, a switching valve is provided in the connection path to connect the first passage to the communication port and to disconnect the second passage to the communication port; 5. The motor-operated valve according to claim 4.

6. the switching valve has a sphere that moves within the connecting passage between an end of the first passage and an end of the second passage in response to a pressure difference between the high-pressure fluid and the low-pressure fluid.

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

7. The switching valve includes a pair of shielding plates and a spring that biases the shielding plates in a direction away from each other, one of the shielding plates opens the first passage and the other shielding plate blocks the second passage in response to a pressure difference between the high-pressure fluid and the low-pressure fluid; 6. The motor-operated valve according to claim 5.

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