Electric valve

Abstract

The invention provides an electric valve capable of suppressing fluid leakage when the valve is closed and realizing high-precision flow control. The electrically operated valve includes: a valve body including a valve chamber accommodating a valve body unit and having a valve seat; a housing connected to the valve body; a rotor of the motor which is driven to rotate; and a switching mechanism that displaces a drive unit in the axial direction in accordance with the rotation angle of the rotor, the valve element unit having a valve shaft connected to the drive unit and a valve element part that is movable relative to the valve shaft in the axial direction and that comes into contact with / separates from the valve seat. An elastic body is disposed on one of the valve shaft and the valve main body so as to surround the periphery of the valve seat, and a contact section that comes into contact with / separates from the elastic body is disposed on the other of the valve shaft and the valve main body.

Description

Technical Field

[0001] The present invention relates to an electric valve. Background Art

[0002] Heretofore, an electric valve has been installed, for example, in the middle of a piping system for a fluid and is used to open / close a flow path of the fluid and control the flow rate. For example, in the electric valve shown in Patent Document 1, a planetary gear reduction mechanism is used to increase the torque of a stepping motor mounted on a valve body and transmit it to a valve element, thereby achieving precise flow rate control and sealing performance when closing the valve.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2023-155785

[0006] Problems to be Solved by the Invention

[0007] However, in the electric valve of Patent Document 1, the valve opening / closing operation is performed by contact / separation of a metal valve element with respect to a metal valve seat. Therefore, if the valve is closed with a foreign object intervening between the valve seat and the valve element, the foreign object will be bitten in, and indentations will be formed on the sealing surfaces of the valve seat or the valve element, which may cause fluid leakage when closing the valve.

[0008] As a countermeasure, one solution is to make one of the valve seat and the valve element made of rubber. However, when their materials are changed to rubber, due to heat and aging, fatigue (volume reduction) occurs, etc., and thus the gap between the valve seat and the valve element when opening the valve changes, which may affect the adjustment of the fluid flow rate or make it difficult to control the flow rate. In addition, in an electric valve, the pressing force between the valve seat and the valve element when closing the valve is large. Therefore, if one of the valve seat and the valve element is made of rubber, the deformation of the rubber becomes too large, and thus countermeasures are also required. Summary of the Invention

[0009] The present invention has been made in view of such problems, and an object thereof is to provide an electric valve that suppresses fluid leakage when closing the valve and can achieve high-precision flow rate control.

[0010] Technical Means for Solving the Problems

[0011] The electric valve of the present invention includes:

[0012] A valve body that includes a valve chamber that houses a valve element unit and has a valve seat;

[0013] A housing that is connected to the valve body;

[0014] The rotor of an electric motor, the rotor of the electric motor being driven to rotate; and

[0015] A conversion mechanism that displaces a drive portion in the axial direction according to the rotation angle of the rotor. The valve element unit has a valve shaft connected to the drive portion, and a stopper and an elastic body connected to the valve shaft.

[0016] The elastic body is disposed opposite to the valve seat so as to surround the periphery of the valve seat.

[0017] 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.

[0018] Advantages of the Invention

[0019] According to the present invention, it is possible to provide an electric valve that suppresses fluid leakage during valve closing and enables highly accurate flow control. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a longitudinal sectional view showing a valve-closed state of the electric valve according to the first embodiment.

[0021] Figure 2 is a view enlargedly showing the vicinity of the valve seat of the electric valve according to the first embodiment.

[0022] Figure 3 (a) of is a view showing the same as Figure 2 the valve-closed state of the electric valve, Figure 3 (b) of is a view enlargedly showing the vicinity of its valve seat.

[0023] Figure 4 (a) of is a view showing the state before valve opening after the stopper has left the conical outer peripheral portion, the same as Figure 3 (a) of Figure 4 (b) of is a view enlargedly showing the vicinity of its valve seat.

[0024] Figure 5 (a) of is a view showing the same as Figure 3 (a) of the valve-open state of the electric valve, Figure 5 (b) of is a view enlargedly showing the vicinity of its valve seat.

[0025] Figure 6 is a flow rate characteristic diagram of the electric valve of the present embodiment, represented by a curve 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) on the horizontal axis.

[0026] Figure 7 is a longitudinal sectional view of the electric valve according to the second embodiment.

[0027] Figure 8 This is the same figure showing the closed valve state of the electric valve according to the second embodiment. Figure 2 Same as above.

[0028] Symbol Explanation

[0029] 1 Electric valve

[0030] 2, 2A Valve body

[0031] 3 Housing

[0032] 40 Spool unit

[0033] 41, 41A Valve shaft

[0034] 42, 42A Stopper

[0035] 43 Sphere

[0036] 43A Shielding device

[0037] 45 Elastomer

[0038] 6 Reduction mechanism

[0039] 8 Support shaft

[0040] VC Valve chamber

[0041] T1 First pipe

[0042] T2 Second pipe. Detailed Embodiment

[0043] Hereinafter, with reference to the drawings, an embodiment of the electric valve according to the present invention will be described. In addition, in this specification, the rotor side is described as the upper side, and the spool side is described as the lower side. The singular planetary gear reduction mechanism is a type of planetary gear reduction mechanism.

[0044] [First Embodiment]

[0045] Figure 1 This is a longitudinal sectional view showing the closed valve state of the electric valve 1 according to the first embodiment of the present invention. Figure 2 This is a view showing an enlarged view of the vicinity of the valve seat of the electric valve 1 according to the first embodiment. The electric valve 1 of this embodiment is used, for example, to adjust the refrigerant flow rate in a refrigeration cycle. The axis of the electric valve 1 is set as L.

[0046] The electric valve 1 of this embodiment is composed of the following components: a valve body 2 having a valve seat 2a formed inside a valve chamber VC, a metal toped cylindrical-shaped housing 3 fixedly installed on the valve body 2 via an annular body 31, a stepping motor composed of a stator (not shown) provided outside the housing 3 and a rotor 57 provided inside the housing 3, a reduction mechanism 6 that reduces and transmits the rotational torque of the rotor 57, a valve element unit 40 disposed in the valve chamber VC and contacting / separating from the valve seat 2a to control the fluid passage amount, and a threaded drive member (drive portion) 22 that converts the rotational motion of the output gear of the reduction mechanism 6 into a linear motion via a threaded feed mechanism (conversion mechanism) 27 to drive the valve element unit 40.

[0047] In the valve body 2, a valve port 16 communicating with the valve chamber VC is formed along an axis L, and a first pipe T1 is connected to the valve port 16 side by soldering or the like. In addition, a second pipe T2 is connected to communicate with an opening 18 formed on the side surface of the valve chamber VC by soldering or the like. The axis of the second pipe T2 is set as O. The axis O is orthogonal to the axis L.

[0048] In addition, a threaded bearing member 13 having an internal thread portion 13a formed at the lower end of the center is inserted into the upper part of the valve chamber VC of the valve body 2 and fixed to the valve body 2 by press-fitting or the like.

[0049] A resin shaft support portion 81 is installed inside the upper end of the housing 3. More specifically, the shaft support portion 81 is continuously formed by a cylindrical portion 81a whose upper end surface abuts against the lower surface of the housing 3 and a flange portion 81b disposed around the cylindrical portion 81a and having an outer periphery abutting against the inner periphery of the housing 3. In the center of the shaft support portion 81, a through hole 81c penetrating vertically is formed coaxially with the axis L. The inner diameter of the through hole 81c is substantially equal to the outer diameter of the support shaft 8.

[0050] The reduction mechanism 6 has, on the inner peripheral side of the rotor 57: a sun gear 61 integrally formed with a rotor support member 56, a fixed ring gear 62 fixed via a thin-walled cylindrical body 66 fixedly installed on 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 them respectively, a planetary gear carrier 64 that rotatably supports the planetary gear 63, and a bottomed cylindrical output gear member 65 having teeth meshing with the planetary gear 63 on its inner periphery, and a differential planetary gear reduction mechanism is constituted by them. 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.

[0051] A metal support shaft 8 penetrates the rotor support member 56 and the sun gear 61 and is held so as to be able to rotate together with them. The upper end of the support shaft 8 is fitted into the through hole 81c of the shaft support portion 81 installed in the housing 3, and thus is supported so as to be able to move in the rotational direction and the direction of the axis L.

[0052] 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 fitted into the upper opening of the output shaft portion 29 by press-fitting, so that the output gear member 65, the support shaft 8, and the output shaft portion 29 are configured to rotate integrally.

[0053] The external thread portion 22a formed on the lower part of the screw drive member 22 is screwed into the internal thread 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 a linear movement along the axis L by the screw feed mechanism (conversion mechanism) 27 composed of the external thread portion 22a and the internal thread portion 13a.

[0054] A slit 29a is formed at the lower end of the output shaft portion 29, and a plate 22b protruding along the axis L is formed at the upper end of the screw drive member 22. The slit 29a and the plate 22b are slidably engaged with each other. Thus, the output shaft portion 29 and the screw drive member 22 can be rotatably connected integrally. 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.

[0055] 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 relative to the valve body 2. According to the lifting of the output gear member 65, the planet gear carrier 64 and the planet gears 63 placed on the bottom surface of the output gear member 65 also lift integrally with the support shaft 8.

[0056] The lower end of the spherical joint 25 composed of the ball 23 and the ball seat 24 abuts against the upper end of the hollow cylindrical spring support member 28 coaxially press-fitted into the upper end of the valve shaft 41 of the valve element unit 40. The cylindrical spring housing 19 disposed around the valve element unit 40 and the spring support member 28 is continuously provided with an enlarged diameter portion 19a, a reduced diameter portion 19b, and an upper end flange portion 19c extending radially outward from the upper end of the enlarged diameter portion 19a. The upper end flange portion 19c is engaged 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 holds the outer periphery of the valve shaft 41 of the valve element unit 40 so as to be slidable.

[0057] The lower end of the compression coil spring 26 abuts against the stepped portion between the enlarged diameter portion 19a and the reduced diameter portion 19b, and the upper end is engaged with the spring support member 28, so that it is arranged in a compressed state. Thus, a force is always applied to the valve element unit 40 in the valve opening direction.

[0058] The linear motion of the threaded drive member 22 is transmitted to the shaft-like valve element unit 40 via the spherical joint 25 and the spring support member 28. Thus, the valve element unit 40 is guided by the spring housing 19 and moves in the direction of the axis L.

[0059] The valve element unit 40 is composed of a metal valve shaft 41 and a metal stopper 42. The valve shaft 41 coaxially has a small-diameter portion 41a and a large-diameter portion 41b with a diameter larger than that of the small-diameter portion 41a. The upper end of the small-diameter portion 41a is fitted into the inner circumference of the spring support member 28 by press-fitting, and the outer circumference of the small-diameter portion 41a is slidably fitted into the inner circumference of the reduced-diameter portion 19b.

[0060] In Figure 2 it, 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 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. Additionally, it also has a second valve shaft hole (first passage) 41f formed above the first valve shaft hole 41d. The inner diameter of the second valve shaft hole 41f is smaller than that of the first valve shaft hole 41d, and the second valve shaft hole 41f and the first valve shaft hole 41d are connected via an upper tapered surface portion 41e that tapers upward. A communication hole 41g is formed to communicate the vicinity of the upper end of the second valve shaft hole 41f with the outer circumference of the small-diameter portion 41a. The lower end of the thin-walled peripheral wall of the recess 41c becomes a riveting portion 41h.

[0061] The substantially cylindrical stopper 42 has: a cylindrical first outer peripheral portion 42a with a diameter smaller than the inner diameter of the recess 41c, a cylindrical second outer peripheral portion 42c with a diameter larger than that of the first outer peripheral portion 42a, and a tapered outer peripheral portion 42d that tapers downward. A ring-shaped flange portion 42b is provided between the first outer peripheral portion 42a and the second outer peripheral portion 42c, and the flange portion 42b has an outer diameter almost the same as the inner diameter of the recess 41c. The flange portion 42b has a plurality of through-holes (supply paths) 42f that penetrate vertically.

[0062] A peripheral groove 42e adjacent to the flange portion 42b is formed in the second outer peripheral portion 42c. A ring-shaped elastic body 45 made of rubber or resin is installed in the peripheral groove 42e. The elastic body 45 is in close contact with the bottom surface of the peripheral groove 42e and the inner circumference of the recess 41c by elastic deformation when installed. 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 taken as the back side, and the lower surface of the elastic body 45 (the surface seated on the valve seat 2a) is taken as the front side.

[0063] Further, the stopper 42 has a first inner peripheral portion 42h in the shape of a cylinder having substantially the same diameter as the first valve shaft hole 41d, and a second inner peripheral portion (second passage) 42i in the shape of a cylinder having a diameter smaller than that of the first inner peripheral portion 42h is provided below 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, and 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 lower tapered surface portion 42j that tapers downward.

[0064] When the stopper 42 is assembled to 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 integrated. At this time, a sphere 43 serving as a switching valve is movably disposed in an 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 sphere 43 that has moved downward in the internal space IC is caught by the lower tapered surface portion 42j, closing the upper end of the second inner peripheral portion 42i. Further, the sphere 43 that has moved upward is caught by the upper tapered surface portion 41e, closing the lower end of the second valve shaft hole 41f.

[0065] 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 peripheral portion 42h, and this space is defined as a back pressure chamber BC. A plurality of communication ports 42k are formed along the radial direction to communicate the vicinity of the upper end of the first inner peripheral portion 42h with the first outer peripheral portion 42a, and the back pressure chamber BC is communicated with the internal space IC via the communication ports 42k.

[0066] Before the spool unit 40 is assembled, the riveted portion 41h of the valve shaft 41 is in the shape of a cylinder. At the time of assembly, the sphere 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, and the stopper 42 is inserted into the recess 41c of the valve shaft 41. Thereafter, the spool unit 40 is assembled by plastically deforming the lower end of the riveted portion 41h radially inward.

[0067] The metal valve body 2 has a cylindrical valve cylinder portion 2b extending upward around the valve port 16 on the bottom surface of the valve chamber VC. The upper end of the valve cylinder 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 in the shape of an arc. Further, the upper end of the valve port 16 is defined as a locking portion 2c. The tapered outer peripheral portion 42d of the stopper 42 can abut against the locking portion 2c.

[0068] (Operation of the electric valve)

[0069] Figure 3(a) shows the closed valve state of the electric valve 1 and is the same as Figure 2 the same figure, Figure 3 (b) is an enlarged view showing the vicinity of the valve seat 2a. Figure 4 (a) shows the state before valve opening after the stopper 42 has left the conical outer peripheral portion 42d and is the same as Figure 3 the same figure as (b), Figure 4 (b) is an enlarged view showing the vicinity of the valve seat 2a. Figure 5 (a) shows the open valve state of the electric valve 1 and is the same as Figure 3 the same figure as (b), Figure 5 (b) is an enlarged view showing the vicinity of the valve seat 2a. Figures 3 - 5 and Figure 2 Although the lengths of some structures are different, they are the same. Figure 6 is a flow rate characteristic diagram of the electric valve in the present embodiment, which is represented by a curve graph with the flow rate on the vertical axis and the valve opening degree (the number of drive pulses corresponding to the axial direction position of the valve shaft 41) on the horizontal axis. The scale of the vertical axis may be different from the actual situation. In addition, in Figure 6 the flow rate characteristic diagram, it is shown together with a schematic Figure 1 showing the opening and closing valve states of the electric valve 1. 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.

[0070] In Figure 2 , 3 the state shown, the valve shaft 41 of the valve core unit 40 is located at the lowermost position ( Figure 6 position P1 in the figure), at this time, the stopper 42 abuts against the locking portion 2c, and the lower surface of the elastic body 45 is elastically deformed and abuts against the valve seat 2a. Therefore, the fluid cannot move from the valve chamber VC beyond the valve seat 2a to the valve port 16 side, thus ensuring a fully closed valve state.

[0071] In the case where the elastic body 45 is not provided, the metal valve shaft 41 will seat on the valve seat 2a, but a small gap will be generated between the two, and thus fluid leakage may occur. According to the present embodiment, the elastic body 45 is elastically deformed and abuts against the valve seat 2a, so the fluid does not flow from the valve chamber VC toward the valve seat 2a side. Therefore, the movement of the fluid between the second pipe T2 and the first pipe T1 is restricted. In addition, even if a foreign object in the fluid, that is, so-called biting, is caught between the elastic body 45 and the valve seat 2a, since the elastic body 45 is separated from the valve seat 2a, the foreign object is washed away by the fluid, or the elastic body 45 elastically returns, thus suppressing the hindrance of valve closing.

[0072] In Figure 2 , 3In this case, 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 housing 19 and the outer periphery of the small-diameter portion 41a, the communication hole 41g, and the second valve shaft hole 41f. That is, 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 valve shaft hole 41f form an introduction path for introducing the high-pressure fluid.

[0073] However, the lower end of the internal space IC (the end of the second passage) is closed by the sphere 43, suppressing the flow of the fluid from the internal space IC toward the valve port 16 side (the connection between the communication port and the second passage is cut off). In addition, the sphere 43 is urged downward against the lower tapered surface portion 42j by the pressure difference between the internal pressure of the internal space IC and the internal pressure of the second inner peripheral portion 42i, and stays at this position.

[0074] Since the sphere 43 stays at the lower tapered surface portion 42j, the second valve shaft hole 41f communicates with the internal space IC, and thus 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. Therefore, as shown in (b) of Figure 3 , the pressure Pr1 in the back pressure chamber BC is borne by the upper surface of the elastic body 45.

[0075] On the other hand, the lower surface of the elastic body 45 is exposed to the high-pressure fluid in the valve chamber VC on the radially outer side of the valve seat 2a and bears its pressure Pr1, and is exposed to the low-pressure fluid on the valve port 16 side in the radially inner direction of the valve seat 2a and bears its pressure Pr2 (< Pr1). Here, it is assumed that the areas A of the upper and lower surfaces of the elastic body 45 are equal, and the area B of the lower surface of the elastic body 45 at a position radially outside compared with the contact portion with the valve seat 2a is set. Then, the force received by the upper surface of the elastic body 45 is represented by Pr1 × A. In contrast, the force received by the lower surface of the elastic body 45 is represented by Pr1 × B + Pr2(A - B). If the force F acting in the vertical direction of the elastic body 45 is represented with the downward direction being positive, then F = Pr1 × A - (Pr1 × B + Pr2(A - B)) = Pr1(A - B) - Pr2(A - B). Here, since Pr2 < Pr1 according to the premise, F > 0, and the force received by the upper surface of the elastic body 45 becomes larger. Therefore, the elastic body 45 is pressed against the valve seat 2a by the pressure difference between the upper and lower surfaces of the elastic body 45, and thus the separation of the elastic body 45 from the valve seat 2a is suppressed, and the sealing performance is not lost even if the elastic body 45 is fatigued due to heat or the like.

[0076] However, assuming that the entire lower surface of the elastic body 45 is subjected to 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 excessive, which may cause excessive fatigue of the elastic body 45 or the like. According to the present 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 are offset, and excessive fatigue of the elastic body 45 can be suppressed.

[0077] When the rotor 57 of the stepping motor is rotated by supplying power to the stator from the fully closed valve state, 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.

[0078] The rotational motion of the output shaft portion 29 is converted into a linear motion by the screw feed mechanism 27. As a result, the output shaft portion 29 and the valve shaft 41 of the valve element unit 40 rise together in the axial direction. Here, as Figure 4 shown, since the valve shaft 41 rises, the stopper 42 separates from the locking portion 2c ( Figure 6 position P2), but the elastic body 45 remains in contact with the valve seat 2a. During the period in which the state of contact between the elastic body 45 and the valve seat 2a is maintained ( Figure 6 positions P1 to P2), the fluid is prevented from flowing from the valve chamber VC toward the valve port 16.

[0079] By further raising the valve shaft 41, the elastic body 45 separates from the valve seat 2a. Therefore, the 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 Figure 6 position P2 to position P3, in the flow path from the valve chamber VC toward the valve port 16, the cross-sectional area of the gap between the elastic body 45 and the valve seat 2a is the smallest. Therefore, the flow rate of the fluid increases according to the gap between the elastic body 45 and the valve seat 2a.

[0080] However, as Figure 5 shown in (b), after the valve shaft 41 reaches the position P3, in the flow path from the valve chamber VC toward the valve port 16, the cross-sectional area of the gap between the inner periphery 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. Therefore, the flow rate of the fluid from the valve chamber VC toward the valve port 16 becomes substantially constant.

[0081] When the valve shaft 41 reaches the position P4, the conical outer peripheral portion 42d is located radially inside the valve cylinder portion 2b. Therefore, as the valve shaft 41 rises, the gap between the valve cylinder portion 2b and the conical outer peripheral portion 42d changes, so that until the position P5 as the maximum valve opening position, the fluid flows from the valve chamber VC toward the valve port 16 at a flow rate corresponding to the gap between the conical outer peripheral portion 42d of the stopper 42 determined by the axial position of the valve shaft 41 and the valve cylinder portion 2b. Therefore, the movement of the fluid with a specified flow rate between the second pipe T2 and the first pipe T1 is allowed. Therefore, according to the present embodiment, the electric valve 1 that can suppress fluid leakage during valve closing and can achieve high-precision flow control can be provided.

[0082] By supplying power with the opposite characteristics to the stator from the valve open state, the rotor 57 rotates in the reverse direction. Therefore, the valve shaft 41 can be lowered with the opposite operation to the above. After the lower surface of the elastomer 45 abuts against the valve seat 2a, the stopper 42 is seated on the engaging portion 2c. Thus, the downward acting force from the valve shaft 41 can be supported by the stopper 42, so that excessive deformation of the elastomer 45 can be suppressed.

[0083] This embodiment can also be applied to the case where the first pipe T1 side is the high-pressure side pipe and the second pipe T2 side is the low-pressure side pipe (the case where the valve chamber VC is filled with the low-pressure fluid). In this case, the high-pressure fluid introduced from the valve port 16 via the second inner peripheral portion 42i as the first passage pushes up the sphere 43 (connects the first passage to the internal space IC), and thus the high-pressure fluid enters the internal space IC. The sphere 43 pushed up by the high-pressure fluid is caught by the upper conical surface portion 41e as shown by the dashed line in Figure 2 and closes 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).

[0084] Therefore, the high-pressure fluid introduced into the internal space IC via the second inner peripheral portion 42i flows into the back pressure chamber BC through the communication port 42k, and pressure is applied to the upper surface of the elastomer 45. In addition, the lower surface of the elastomer 45 is exposed to the low-pressure fluid in the valve chamber VC on the radial outside of the valve seat 2a and to the high-pressure fluid on the valve port 16 side on the radial inside of the valve seat 2a. Therefore, similarly to the above, the pressure difference between the upper and lower surfaces of the elastomer 45 can be suppressed to be low, and excessive fatigue of the elastomer 45 can be suppressed.

[0085] (Second Embodiment)

[0086] Figure 7 is a longitudinal sectional view of the electric valve 1A according to the second embodiment. Figure 8 is a view showing the valve closed state of the electric valve according to the second embodiment and Figure 2Same figure. In the present embodiment, in the valve spool unit 40A, instead of the sphere, a shielding device 43A that functions as a switching valve is provided, and accordingly, the shapes of the valve shaft 41A and the stopper 42A are different. The other structures are the same as those in the above-described embodiment, and thus redundant descriptions are omitted.

[0087] The shielding device 43A has: an upper shielding plate 43Aa, a lower shielding plate 43Ab, and a helical spring 43Ac disposed between the upper shielding plate 43Aa and the lower shielding plate 43Ab, and the shielding device 43A is disposed in the internal space IC.

[0088] The valve shaft 41A does not have an upper tapered surface 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. In addition, the first inner peripheral portion 42h and the second inner peripheral portion 42i of the stopper 42A are directly connected, and a lower stepped portion 42Aj orthogonal to the axis L is formed at their intersection.

[0089] 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 of the first passage as the introduction path causes the upper shielding plate 43Aa to be pushed downward against the force of the helical spring 43Ac, so as to move away from the upper stepped portion 41Ae, and the second valve shaft hole 41f communicates with the internal space IC. Therefore, the 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.

[0090] When the high-pressure fluid is introduced from the valve chamber VC into the internal space IC, a pressure difference 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 close the upper end of the second inner peripheral portion 42i serving as the second passage (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 elastomer 45 can be adjusted in the same manner as in the first embodiment.

[0091] On the contrary, when the first pipe T1 is the high-pressure side pipe and the second pipe T2 is the low-pressure side pipe, the high-pressure fluid introduced into the second inner peripheral portion 42i of the first passage as the introduction path causes the lower shielding plate 43Ab to be pushed upward against the force of the helical spring 43Ac, so as to move away from the lower stepped portion 42Aj, and the second inner peripheral portion 42i communicates with the internal space IC. 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 stepped portion 42Aj and the lower shielding plate 43Ab.

[0092] By introducing high-pressure fluid from the valve chamber VC into the internal space IC, a pressure difference is generated between the internal pressure of the internal space IC and the internal pressure of the second valve shaft hole 41f. As a result, the upper shutter 43Aa abuts against the upper stepped portion 41Ae to close the lower end of the second valve shaft hole 41f serving as the second passage (cut off the connection between the communication port and the second passage). Thus, 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.

[0093] In addition, 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. Further, in the above-described embodiments, any component can be added or omitted. For example, a reduction mechanism composed of a pair of gears can be provided instead of the planetary gear reduction mechanism. Alternatively, the present invention can also be applied to an electric valve that does not have a reduction mechanism.

[0094] This specification includes the disclosure of the following inventions.

[0095] (First mode)

[0096] An electric valve having:

[0097] A valve body including a valve chamber that houses a valve element unit and has a valve seat;

[0098] A housing connected to the valve body;

[0099] A rotor of a motor that is driven to rotate; and

[0100] A conversion mechanism that displaces a drive portion in the axial direction according to the rotation angle of the rotor, wherein the valve element unit has a valve shaft connected to the drive portion and a stopper and an elastic body connected to the valve shaft,

[0101] The elastic body is disposed opposite to the valve seat so as to surround the periphery of the valve seat,

[0102] 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.

[0103] (Second mode)

[0104] In the electric valve of the first mode,

[0105] 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.

[0106] (Third mode)

[0107] In the electric valve in the first mode or the second mode,

[0108] The stopper has a conical outer peripheral portion that abuts against the locking portion.

[0109] After the elastic body separates from the valve seat, the fluid flowing through the gap between the conical outer peripheral portion and the locking portion is controlled according to the axial direction position of the valve shaft.

[0110] (Fourth mode)

[0111] In the electric valve in any one of the first mode to the third mode,

[0112] 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.

[0113] The valve core unit has: an introduction path that introduces the high-pressure fluid; a back pressure chamber that communicates with the introduction path; and a supply path that communicates with the back pressure chamber and supplies the high-pressure fluid to the back surface of the elastic body opposite to the valve seat.

[0114] (Fifth mode)

[0115] In the electric valve in the fourth mode,

[0116] A part of the front surface of the elastic body on the valve seat side is exposed to the high-pressure fluid.

[0117] (Sixth mode)

[0118] In the electric valve in the fourth mode or the fifth mode,

[0119] It has: a first passage that is connected to the high-pressure side pipe; a second passage that is connected to the low-pressure side pipe; a connection path that is connected to the first passage and the second passage; and a communication port that connects the connection path and the back pressure chamber.

[0120] A switching valve is provided in the connection path, and the switching valve communicates the first passage with the communication port and cuts off the connection between the second passage and the communication port.

[0121] (Seventh mode)

[0122] In the electric valve in the sixth mode,

[0123] The switching valve has a sphere that moves within the connection path between the end of the first passage and the end of the second passage according to the pressure difference between the high-pressure fluid and the low-pressure fluid.

[0124] (Eighth mode)

[0125] In the electric valve of the sixth mode,

[0126] The switching valve has: a spring and a pair of shutter plates, and the spring applies a force to the shutter plates in a direction separating them from each other.

[0127] According to the pressure difference between the high-pressure fluid and the low-pressure fluid, one of the shutter plates opens the first passage, and the other shutter plate blocks the second passage.

Claims

1. An electric valve, characterized in that: have: A valve body, the valve body including a valve chamber, the valve chamber accommodating the valve core unit and having a valve seat; a housing connected to the valve body; a rotor of an electric motor, the rotor of the electric motor being driven to rotate; as well as a conversion mechanism that displaces the driving portion in the axial direction according to the rotation angle of the rotor, The valve core unit includes a valve shaft connected to the driving portion, and a stopper and an elastic body connected to the valve shaft. The elastic body is arranged opposite to the valve seat so as to surround the periphery of the valve seat. When the valve shaft moves in a direction toward the valve seat, the elastic body comes into contact with the valve seat, and then the stopper comes into contact with the locking portion of the valve body.

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

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

4. The electric valve according to claim 1, characterized in that: The valve chamber is connected to 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. The valve core unit comprises: 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.

5. The electric valve according to claim 4, characterized in that: A portion of the front surface of the elastic body, which is the valve seat side, is exposed to the high-pressure fluid.

6. The electric valve according to claim 4, characterized in that: The invention comprises: a first passage connected to the high-pressure side pipe; a second passage connected to the low-pressure side pipe; and a connecting passage connected to the first passage and the second passage; and a communication port connecting the connection path and the back pressure chamber, The connection passage includes a switching valve that connects the first passage with the communication port and disconnects the second passage from the communication port.

7. The electric valve according to claim 6, characterized in that: The switching valve includes a ball that moves in the connecting passage between an end of the first passage and an end of the second passage according to a pressure difference between the high-pressure fluid and the low-pressure fluid.

8. The electric valve according to claim 6, characterized in that: The switching valve includes a spring and a pair of baffles, wherein the spring applies force to the baffles to separate from each other. According to the pressure difference between the high-pressure fluid and the low-pressure fluid, one of the shielding plates opens the first passage, and the other of the shielding plates blocks the second passage.

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