Motor 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 an electric valve.

Background Art

[0002] Conventionally, an electric valve is assembled, for example, in the middle of a fluid piping system and used to open and close a fluid flow path or control the flow rate. For example, in an electric valve as shown in Patent Document 1, a planetary gear reduction mechanism is used to increase the torque of a stepping motor attached to a valve body and transmit it to the valve body, thereby achieving accurate flow rate control and sealing performance when the valve is closed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the electric valve of Patent Document 1, the valve body made of metal comes into contact with and separates from the valve seat made of metal to perform the valve opening and closing operation. Therefore, if the valve is closed with foreign matter intervening between the valve seat and the valve body, the foreign matter may be bitten in, and indentations may occur on the sealing surface of the valve seat or the valve body, resulting in fluid leakage when the valve is closed.

[0005] As a countermeasure, it is also an idea to make one of the valve seat and the valve body made of rubber. However, when these materials are changed to rubber, sagging (volume reduction) etc. may occur due to heat or changes over time, and the gap between the valve seat and the valve body at the time of valve opening changes, affecting the adjustment of the fluid flow rate, or making it difficult to control the flow rate. Further, in an electric valve, since the pressing force between the valve seat and the valve body is relatively large when the valve is closed, if one of the valve seat and the valve body is made of rubber, the deformation of the rubber becomes excessive, and thus a countermeasure is required.

[0006] The present invention has been made in view of such problems, and an object thereof is to provide an electric valve capable of realizing high-precision flow control while suppressing fluid leakage during valve closing.

Means for Solving the Problems

[0007] The electric valve of the present invention includes a valve body including a valve chamber that houses a valve body unit and has a valve seat, a stem connected to the valve body, a rotor of a motor that is rotationally driven, and a conversion mechanism that displaces a drive unit in the axial direction according to the rotation angle of the rotor. The valve body unit has a valve shaft connected to the drive unit, and a stopper and an elastic body connected to the valve shaft. The elastic body is disposed to face the valve seat so as to surround the periphery of the valve seat. When the valve shaft moves in the direction toward the valve seat, after the elastic body abuts against the valve seat, the stopper abuts against a locking portion of the valve body.

Effects of the Invention

[0008] According to the present invention, it is possible to provide an electric valve capable of realizing high-precision flow control while suppressing fluid leakage during valve closing.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments of the motorized 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. It is assumed that the planetary gear reduction mechanism is a type of planetary gear reduction mechanism.

[0011] [First Embodiment] Fig. 1 is a longitudinal sectional view showing the closed state of the motorized valve 1 according to the first embodiment of the present invention, and Fig. 2 is a sectional view showing an enlarged view of the vicinity of the valve seat of the motorized valve 1 according to the first embodiment. The motorized valve 1 of the present embodiment is used, for example, to adjust the refrigerant flow rate in a refrigeration cycle. Let the axis of the motorized valve 1 be L.

[0012] The motorized valve 1 of the present embodiment includes a valve body 2 having a valve seat 2a formed inside a valve chamber VC, a toped cylindrical can 3 made of metal and fixed to the valve body 2 via an annular body 31, a stepping motor including a stator (not shown) provided outside the can 3 and a rotor 57 provided inside the can 3, a reduction mechanism 6 that reduces and transmits the rotational torque of the rotor 57, a valve body unit 40 disposed in the valve chamber VC and contacting and separating 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 a linear motion via a screw feed mechanism (conversion mechanism) 27 and drives the valve body unit 40.

[0013] In the valve body 2, a valve port 16 communicating with the valve chamber VC is formed along the axis L, and a first pipe T1 is connected to the valve port 16 side by brazing or the like. Further, a second pipe T2 is connected to an opening 18 formed on the side surface of the valve chamber VC by brazing or the like so as to communicate therewith. Let the axis of the second pipe T2 be O. The axis O is orthogonal to the axis L.

[0014] Also, on the upper part of the valve chamber VC of the valve body 2, a screw bearing member 13 having a female screw portion 13a formed on the central lower end side is fitted and fixed to the valve body 2 by press-fitting or the like.

[0015] A resin shaft support portion 81 is attached to the inner side of the upper end of the cam 3. More specifically, the shaft support portion 81 is formed by connecting a cylindrical portion 81a whose upper end surface abuts against the lower surface of the cam 3 and a flange portion 81b disposed around the cylindrical portion 81a and having an outer periphery abutting against the inner periphery of the cam 3. A through hole 81c penetrating vertically is formed coaxially with the axis L at the center of the shaft support portion 81. The inner diameter of the through hole 81c is substantially equal to the outer diameter of the support shaft 8.

[0016] The speed reduction mechanism 6 includes, on the inner peripheral side of the rotor 57, a sun gear 61 integrally formed with the rotor support member 56, a fixed ring gear 62 fixed via a thin-walled cylindrical body 66 fixed to the upper part of the valve body 2 and extending upward, a planetary gear 63 disposed between the sun gear 61 and the fixed ring gear 62 and meshing with each of them, a carrier 64 rotatably supporting the planetary gear 63, and a bottomed cylindrical output gear member 65 having teeth meshing with the planetary gear 63 on its inner periphery. These constitute a wonder planetary gear speed 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 metal support shaft 8 passes through the rotor support member 56 and the sun gear 61 and is rotatably held together with them. The upper end of the support shaft 8 is fitted into the through hole 81c of the shaft support portion 81 attached to the cam 3 and is supported so as to be movable in the rotational direction and the axis L direction.

[0018] At the center of the bottom of the output gear member 65, 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. The lower end of the support shaft 8 is press-fitted and fitted into the upper opening of the output shaft portion 29, and the output gear member 65, the support shaft 8, and the output shaft portion 29 are configured to rotate integrally.

[0019] The male screw portion 22a formed on the lower part of the screw drive member 22 is screwed into the female screw portion 13a of the screw bearing member 13. The rotational movement 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 composed of the male screw portion 22a and the female screw portion 13a.

[0020] A slit 29a is formed at the lower end of the output shaft portion 29, and a blade 22b protruding along the axis L is formed at the upper end of the screw drive member 22. The slit 29a and the blade 22b are slidably engaged with each other. Thereby, the output shaft portion 29 is integrally rotatably connected to the screw drive member 22. When the output gear member 65 (rotor 57) rotates, the output shaft portion 29 and the screw drive member 22 rotate integrally, but can linearly move relative to each other along the axis L.

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

[0022] The lower end of the ball joint 25, which consists of the ball 23 and the ball seat 24, abuts against the upper end of the hollow cylindrical spring support member 28 that is coaxially press-fitted onto the upper end of the valve shaft 41 of the valve body unit 40. The cylindrical spring case 19 disposed around the valve body unit 40 and the spring support member 28 is formed by connecting an enlarged diameter portion 19a, a reduced diameter portion 19b, and an upper end flange portion 19c that extends radially outward from the upper end of the enlarged diameter portion 19a. The upper end flange portion 19c engages with the inner peripheral stepped portion of the valve body 2 and is fixedly held by the screw bearing member 13. The reduced diameter portion 19b slidably holds the outer periphery of the valve shaft 41 of the valve body unit 40.

[0023] The compression coil spring 26 has its lower end abutted against the stepped portion between the enlarged diameter portion 19a and the reduced diameter portion 19b, and its upper end engaged with the spring support member 28, and is arranged in a compressed state, thereby constantly biasing the valve body unit 40 in the valve-opening direction.

[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. Thereby, 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 consists of a metallic valve shaft 41 and a metallic stopper 42. The valve shaft 41 has a small diameter portion 41a and a large diameter portion 41b with a larger diameter than the small diameter portion 41a coaxially. The upper end of the small diameter portion 41a is fitted into the inner periphery of the spring support member 28 by press-fitting, and the outer periphery of the small diameter portion 41a is slidably fitted to the inner periphery of the reduced diameter portion 19b.

[0026] In FIG. 2, the valve shaft 41 has a cylindrical recess 41c at the lower end of the large-diameter portion 41b (the surface facing the valve seat 2a), and further has a first valve shaft hole 41d extending from the large-diameter portion 41b to the small-diameter portion 41a at the center of the bottom surface of the recess 41c. It also has a second valve shaft hole (first passage) 41f formed above the first valve shaft hole 41d. The second valve shaft hole 41f has a smaller inner diameter than the first valve shaft hole 41d, and the second valve shaft hole 41f and the first valve shaft hole 41d are connected via an upward tapered portion 41e whose diameter decreases upward. A communication hole 41g is formed to communicate the vicinity of the upper end of the second valve shaft hole 41f and the outer periphery of the small-diameter portion 41a. The lower end of the thin-walled peripheral wall of the recess 41c is a caulked portion 41h.

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

[0028] A circumferential groove 42e is formed in the second outer peripheral portion 42c adjacent to the flange portion 42b. An annular elastic body 45 made of rubber or resin is attached to the circumferential groove 42e. The elastic body 45 is elastically deformed when attached, so as to be in close contact with the bottom surface of the circumferential groove 42e and the inner periphery of the recess 41c. As the material of the elastic body 45, HNBR, PTFE, etc. can be used, but it is not limited thereto. 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] Furthermore, the stopper 42 has a first inner peripheral portion 42h that is cylindrical and has the same diameter as the first valve shaft hole 41d. Below the first inner peripheral portion 42h, it has a second inner peripheral portion (second passage) 42i that is cylindrical and has a smaller diameter than the first inner peripheral portion 42h. The first inner peripheral portion 42h is open at the upper end of the stopper 42 and faces the first valve shaft hole 41d. The second inner peripheral portion 42i is open at the lower end of the stopper 42 and communicates with the valve port 16. The first inner peripheral portion 42h and the second inner peripheral portion 42i are connected via a downward tapered portion 42j that tapers in diameter downward.

[0030] When the stopper 42 is assembled into the recess 41c, the upper surface of the stopper 42 is in close contact with the bottom surface of the recess 41c, and the first inner peripheral portion 42h and the first valve shaft hole 41d are aligned. At this time, a spherical body 43 as a switching valve is movably disposed in the internal space IC (also referred to as a connection path) formed by the first inner peripheral portion 42h and the first valve shaft hole 41d. The spherical body 43 that has moved downward in the internal space IC is locked by the downward tapered portion 42j, sealing the upper end of the second inner peripheral portion 42i. Also, the spherical body 43 that has moved upward is locked by the upward tapered portion 41e, sealing the lower end of the second valve shaft hole 41f.

[0031] When the stopper 42 is assembled into 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 peripheral portion 42h. This space is defined as a back pressure chamber BC. A plurality of communication ports 42k that communicate the vicinity of the upper end of the first inner peripheral portion 42h and the first outer peripheral portion 42a are formed along the radial direction, and the back pressure chamber BC and the internal space IC communicate with each other via the communication ports 42k.

[0032] Before the valve body unit 40 is assembled, the caulking portion 41h of the valve shaft 41 is cylindrical. During assembly, the spherical body 43 is disposed in the first inner peripheral portion 42h of the stopper 42, and the elastic body 45 is disposed in the circumferential groove 42e. Then, the stopper 42 is inserted into the recess 41c of the valve shaft 41. Thereafter, the valve body unit 40 is assembled by plastically deforming the lower end of the caulking portion 41h radially inward.

[0033] The metal valve body 2 has a cylindrical valve tube portion 2b extending upward around the valve port 16 on the bottom surface of the valve chamber VC. The upper end of the valve tube portion 2b serves as a valve seat 2a that can abut against the lower surface of the elastic body 45 over the entire circumference. The axial cross-section of the valve seat 2a is preferably arcuate. Also, the upper end of the valve port 16 is a locking portion 2c. The tapered outer peripheral portion 42d of the stopper 42 can abut against the locking portion 2c.

[0034] (Operation of the electric valve) FIG. 3(a) is a view similar to FIG. 2 showing the closed state of the electric valve 1, and FIG. 3(b) is an enlarged view showing the vicinity of the valve seat 2a. FIG. 4(a) is a view similar to FIG. 3(b) showing the state before valve opening after the stopper 42 is separated from the tapered outer peripheral portion 42d, and FIG. 4(b) is an enlarged view showing the vicinity of the valve seat 2a. FIG. 5(a) is a view similar to FIG. 3(b) showing the open state of the electric valve 1, and FIG. 5(b) is an enlarged view showing the vicinity of the valve seat 2a. FIGS. 3 to 5 and FIG. 2 have different lengths of some components, but they are similar. FIG. 6 is a flow rate characteristic diagram of the electric valve in the present embodiment, which is shown as a graph with the flow rate on the vertical axis and the valve opening degree (the number of drive pulses corresponding to the axial position of the valve shaft 41) on the horizontal axis, but the scale of the vertical axis may be different from the actual one. Also, in the flow rate characteristic diagram of FIG. 6, a schematic diagram showing the open / closed state of the electric valve 1 is shown together. Here, it is assumed that the second pipe T2 side is the high-pressure side pipe and the first pipe T1 side is the low-pressure side pipe.

[0035] In the states shown in FIGS. 2 and 3, the valve shaft 41 of the valve body unit 40 is at the lowermost position (position P1 in FIG. 6). At this time, 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 being elastically deformed. Therefore, the fluid cannot move from the valve chamber VC beyond the valve seat 2a to the valve port 16 side, and a fully closed valve state is ensured.

[0036] If the elastic body 45 were not present, the metal valve shaft 41 would seat on the valve seat 2a, but there might be a slight gap between the two, which could cause fluid leakage. According to the present embodiment, as the elastic body 45 abuts against the valve seat 2a while elastically deforming, fluid does not flow from the valve chamber VC side to the valve seat 2a side. Therefore, the movement of fluid between the second pipe T2 and the first pipe T1 is restricted. Further, even if so-called jamming occurs where foreign matter in the fluid is caught between the elastic body 45 and the valve seat 2a, the elastic body 45 and the valve seat 2a separate, and the foreign matter is washed away by the fluid. Also, since the elastic body 45 elastically returns, this suppresses the inhibition of valve closing.

[0037] In FIGS. 2 and 3, the high-pressure fluid in the valve chamber VC flows into the internal space IC through the gap between the inner circumference of the reduced-diameter portion 19b of the spring case 19 and the outer circumference of the small-diameter portion 41a, the communication hole 41g, and the second valve shaft hole 41f. That is, the gap between the inner circumference of the reduced-diameter portion 19b and the outer circumference of the small-diameter portion 41a, the communication hole 41g, and the second valve shaft 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 spherical body 43, and the flow of fluid from the internal space IC to the valve port 16 side is suppressed (the connection between the communication port and the second passage is blocked). Also, the spherical body 43 is biased toward the lower tapered portion 42j by the differential pressure between the internal pressure of the internal space IC and the internal pressure of the second inner peripheral portion 42i and stays in that position.

[0039] Since the spherical body 43 stays at the lower tapered portion 42j, the second valve shaft hole 41f and the internal space IC communicate with each other. Therefore, the high-pressure fluid (pressure Pr1) in the internal space IC flows into the back pressure chamber BC through the communication port 42k. The back pressure chamber BC communicates with the lower surface side of the flange portion 42b through the through hole 42f. For this reason, as shown in FIG. 3(b), the pressure Pr1 in the back pressure chamber BC is received on the upper surface of the elastic body 45.

[0040] On the one hand, the lower surface of the elastic body 45 is exposed to the high-pressure fluid in the valve chamber VC radially outward of the valve seat 2a, receives the pressure Pr1, and is also exposed to the low-pressure fluid on the valve port 16 side radially inward of the valve seat 2a, so it receives 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 radially outward of 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). Expressing 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 from the preconditions, F > 0, and 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 is not lost.

[0041] However, if the entire lower surface of the elastic body 45 receives the pressure Pr2, the force acting on the elastic body 45 is F = (Pr1 - Pr2)A, and the force received on the upper surface side of the elastic body 45 becomes 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 to rotate the rotor 57 of the stepping motor from the fully closed valve state, 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 portion 29 is converted into linear motion by the screw feed mechanism 27, and thereby the output shaft portion 29 rises in the axial direction together with the valve shaft 41 of the valve body unit 40. Here, when the valve shaft 41 rises, as shown in FIG. 4, the stopper 42 separates from the locking portion 2c (position P2 in FIG. 6), but the elastic body 45 remains in contact with the valve seat 2a. While the state where the elastic body 45 is in contact with the valve seat 2a is maintained (positions P1 to P2 in FIG. 6), the flow of fluid from the valve chamber VC to the valve port 16 is blocked.

[0044] Furthermore, as the valve shaft 41 further rises, the elastic body 45 separates from the valve seat 2a, so that fluid flows from the valve chamber VC to the valve port 16 through the gap between the elastic body 45 and the valve seat 2a. From position P2 to position P3 in FIG. 6, in the flow path from the valve chamber VC to the valve port 16, the cross-sectional area of the gap between the elastic body 45 and the valve seat 2a is the smallest, so 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 shaft 41 reaches position P3, as shown in FIG. 5(b), in the flow path from the valve chamber VC to the valve port 16, the cross-sectional area of the gap between the inner circumference of the valve cylinder portion 2b and the second outer peripheral portion 42c of the stopper 42 becomes the smallest. Since both are cylindrical, even if the valve shaft 41 rises, the gap between the valve cylinder portion 2b and the second outer peripheral portion 42c hardly changes. For this reason, the flow rate of the fluid from the valve chamber VC to the valve port 16 becomes substantially constant.

[0046] When the valve shaft 41 reaches position P4, the tapered outer peripheral portion 42d is positioned radially inside the valve cylinder portion 2b. For this reason, as the valve shaft 41 rises, the gap between the valve cylinder portion 2b and the tapered outer peripheral portion 42d changes. Therefore, up to position P5, which is the maximum valve opening position, fluid flows from the valve chamber VC to the valve port 16 at a flow rate corresponding to the gap between the tapered outer peripheral portion 42d of the stopper 42 and the valve cylinder portion 2b determined by the axial position of the valve shaft 41. For this reason, the movement of a predetermined flow rate of fluid between the second pipe T2 and the first pipe T1 is allowed. Therefore, according to the present embodiment, it is possible to provide the electric valve 1 that can achieve high-precision flow rate control while suppressing fluid leakage during valve closure.

[0047] From the open valve state, by supplying power to the stator with reverse characteristics, the rotor 57 rotates in the reverse direction. Therefore, the valve shaft 41 is lowered by the operation opposite to the above, and after the lower surface of the elastic body 45 abuts against the valve seat 2a, the stopper 42 can be seated on the locking portion 2c. As a result, the downward biasing force from the valve shaft 41 can be supported by the stopper 42, so that excessive deformation of the elastic body 45 can be suppressed.

[0048] This embodiment can also be applied when the first pipe T1 side is the high-pressure side pipe and the second pipe T2 side is the low-pressure side pipe (when the valve chamber VC is filled with a low-pressure fluid). In such a case, the high-pressure fluid introduced from the valve port 16 through the second inner peripheral portion 42i as the first passage pushes up the spherical body 43 (communicates the first passage and the internal space IC), so that the high-pressure fluid enters the internal space IC. The spherical body 43 pushed up by the high-pressure fluid is locked to the upper tapered portion 41e as shown by the dashed-dotted line in FIG. 2, and seals the lower end of the second valve shaft hole 41f which is the second passage (cuts off the connection between the communication port and the second passage).

[0049] For this reason, the high-pressure fluid introduced into the internal space IC through the second inner peripheral portion 42i flows into the back pressure chamber BC through the communication port 42k and applies pressure to the upper surface of the elastic body 45. Also, the lower surface of the elastic body 45 is exposed to the low-pressure fluid in the valve chamber VC outside the radial direction of the valve seat 2a, and is also exposed to the high-pressure fluid on the valve port 16 side inside the radial direction of the valve seat 2a. For this reason, similarly to the above, the pressure difference between the upper and lower surfaces of the elastic body 45 can be kept low, and excessive sagging etc. of the elastic body 45 can be suppressed.

[0050] (Second Embodiment) FIG. 7 is a longitudinal sectional view of the electric valve 1A according to the second embodiment. FIG. 8 is a view similar to FIG. 2 showing the closed valve state of the electric valve according to the second embodiment. In the present embodiment, in the valve body unit 40A, a shielding device 43A that functions as a switching valve is provided instead of the spherical body, and accordingly, the shapes of the valve shaft 41A and the stopper 42A are different. For other configurations, since they are the same as those of the above-described embodiment, duplicate explanations are omitted.

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

[0052] The valve shaft 41A does not have an upper tapered portion, the first valve shaft hole 41d and the second valve shaft hole 41f are directly connected, and an upper stepped portion 41Ae orthogonal to the axis L is formed at their intersection. Further, the stopper 42A has a first inner peripheral portion 42h and a second inner peripheral portion 42i directly connected, and a lower stepped portion 42Aj orthogonal to the axis L is formed at their intersection.

[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 valve shaft hole 41f as the first passage of the introduction path presses the upper shielding plate 43Aa downward against the biasing force of the coil spring 43Ac, causing it to separate from the upper stepped portion 41Ae, and the second valve shaft hole 41f and the internal space IC communicate with each other. For this reason, high-pressure fluid is introduced into the internal space IC from the second valve shaft hole 41f through the gap between the upper stepped portion 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 differential pressure is generated between the internal pressure of the internal space IC and the internal pressure of the second inner peripheral portion 42i. Therefore, the lower shielding plate 43Ab abuts against the lower stepped portion 42Aj to seal the upper end of the second inner peripheral portion 42i, which is the second passage (to cut off the connection between the communication port and the second passage). As a result, the internal pressure of the back pressure chamber BC becomes equal to the internal pressures of the valve chamber VC and the internal space IC, and the pressure applied to the elastic body 45 can be adjusted in the same manner as in the first embodiment.

[0055] On the other hand, when the first pipe T1 is a high-pressure side pipe and the second pipe T2 is a low-pressure side pipe, the high-pressure fluid introduced into the second inner peripheral portion 42i as the first passage of the introduction path pushes the lower shielding plate 43Ab upward against the biasing force of the coil spring 43Ac and separates it from the lower step portion 42Aj, and the second inner peripheral portion 42i and the internal space IC communicate with each other. Therefore, the high-pressure fluid is introduced into the internal space IC from the second inner peripheral 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 differential pressure is generated between the internal pressure of the internal space IC and the internal pressure of the second valve shaft hole 41f. Therefore, the upper shielding plate 43Aa abuts against the upper step portion 41Ae and seals the lower end of the second valve shaft hole 41f as the second passage (cuts off the connection between the communication port and the second passage). As a result, the internal pressure of the back pressure chamber BC becomes 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 in the same manner as in the first embodiment.

[0057] Note that the present invention is not limited to the above-described embodiments. Within the scope of the present invention, any component of the above-described embodiments can be modified. Also, any component can be added or omitted in the above-described embodiments. For example, instead of the planetary gear reduction mechanism, a reduction mechanism composed of a gear pair may be provided. Or, an electric valve having no reduction mechanism is also applicable to the present invention.

[0058] This specification includes the following disclosure of the invention. (First aspect) A valve body including a valve chamber that houses a valve body unit and has a valve seat, a stem connected to the valve body, a rotor of a motor that is rotationally driven, and a conversion mechanism that displaces a drive unit in the axial direction according to the rotation angle of the rotor. The valve body unit has a valve shaft connected to the drive unit, and a stopper and an elastic body connected to the valve shaft. The elastic body is disposed to face the valve seat so as to surround the periphery of the valve seat. When the valve shaft moves in the direction toward the valve seat, after the elastic body abuts against the valve seat, the stopper abuts against the locking portion of the valve body. An electric valve characterized by the above.

[0059] (Second aspect) When the valve shaft moves in the direction away from the valve seat, after the stopper separates from the locking portion, the elastic body separates from the valve seat. The electric valve according to the first aspect, characterized by the above.

[0060] (Third aspect) The stopper has a tapered outer peripheral portion that abuts against the locking portion. After the elastic body separates from the valve seat, depending on the axial position of the valve shaft, the flow of the fluid flowing through the gap between the tapered outer peripheral portion and the locking portion is controlled. The electric valve according to the first aspect or the second aspect, characterized by the above.

[0061] (Fourth aspect) A high-pressure side pipe through which high-pressure fluid flows and a low-pressure side pipe through which low-pressure fluid flows are connected to the valve chamber. The valve body unit has an introduction path for introducing the high-pressure fluid, a back pressure chamber communicating with the introduction path, and a supply path communicating with the back pressure chamber and supplying the high-pressure fluid to the back surface of the elastic body facing the valve seat. The electric valve according to any one of the first aspect to the third aspect, characterized by the above.

[0062] (Fifth aspect) A part of the front surface on the valve seat side of the elastic body is exposed to the high-pressure fluid. The electric valve according to the fourth aspect, characterized by the above.

[0063] (Sixth aspect) It has a first passage connected to the high-pressure side pipe, a second passage connected to the low-pressure side pipe, a connecting passage connected to the first passage and the second passage, and a communication port connecting the connecting passage and the back pressure chamber. A switching valve is provided in the connection path to communicate the first passage with the communication port and cut off the connection between the second passage and the communication port. The electric valve according to the fourth aspect or the fifth aspect, characterized in that.

[0064] (Seventh aspect) The switching valve has a spherical body that moves in the connection path between the end of the first passage and the end of the second passage according to the differential pressure between the high-pressure fluid and the low-pressure fluid. The electric valve according to the sixth aspect, characterized in that.

[0065] (Eighth aspect) The switching valve has a pair of shielding plates and a spring that biases the shielding plates away from each other. According to the differential pressure between the high-pressure fluid and the low-pressure fluid, one of the shielding plates opens the first passage and the other shielding plate shields the second passage. The electric valve according to the sixth aspect, characterized in that.

Explanation of reference numerals

[0066] 1 Electric valve 2, 2A Valve body 3 Cam 40 Valve body unit 41, 41A Valve shaft 42, 42A Stopper 43 Sphere 43A Shielding device 45 Elastic body 6 Reduction mechanism 8 Support shaft VC Valve chamber T1 First pipe T2 Second pipe

Claims

1. A valve body including a valve chamber that houses a valve body unit and has a valve seat, a cam connected to the valve body, a rotor of a motor that is rotationally driven, and a conversion mechanism that displaces a drive unit in the axial direction according to the rotation angle of the rotor, wherein the valve body unit has a valve shaft connected to the drive unit, and a stopper and an elastic body connected to the valve shaft, the elastic body is disposed to face the valve seat so as to surround the periphery of the valve seat, when the valve shaft moves in the direction toward the valve seat, after the elastic body abuts against the valve seat, the stopper abuts against a locking portion of the valve body, characterized in that it is an electric valve.

2. When the valve shaft moves in the direction away from the valve seat, after the stopper separates from the locking portion, the elastic body separates from the valve seat, characterized in that it is the electric valve according to claim 1.

3. The stopper has a tapered outer peripheral portion that abuts against the locking portion, after the elastic body separates from the valve seat, control of the fluid flowing through the gap between the tapered outer peripheral portion and the locking portion is performed according to the axial position of the valve shaft, characterized in that it is the electric valve according to claim 1.

4. A high-pressure side pipe through which high-pressure fluid flows and a low-pressure side pipe through which low-pressure fluid flows are connected to the valve chamber, the valve body unit has an introduction path for introducing the high-pressure fluid, a back pressure chamber communicating with the introduction path, and a supply path communicating with the back pressure chamber and supplying the high-pressure fluid to the back surface of the elastic body facing the valve seat, characterized in that it is the electric valve according to claim 1.

5. A part of the front surface of the elastic body on the valve seat side is exposed to the high-pressure fluid, characterized in that it is the electric valve according to claim 4.

6. It has 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 and the back pressure chamber, a switching valve that communicates the first passage and the communication port and disconnects the connection between the second passage and the communication port is provided in the connection passage, characterized in that it is the electric valve according to claim 4.

7. The switching valve has a sphere that moves in the connection passage between the end of the first passage and the end of the second passage according to the differential pressure between the high-pressure fluid and the low-pressure fluid, characterized in that it is the electric valve according to claim 6.

8. The switching valve has a pair of shielding plates and a spring that biases the shielding plates away from each other. According to the differential pressure between the high-pressure fluid and the low-pressure fluid, one of the shielding plates opens the first passage, and the other shielding plate shields the second passage. The electric valve according to claim 6, characterized by the above.

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