Electric valve

Abstract

The utility model provides an electric valve which is easy to assemble and can restrain fluid leakage and the like. The electric valve comprises a valve main body provided with a valve seat; the valve shaft is provided with an external thread part and is driven by the motor to rotate; a guide sleeve attached to the valve body, the guide sleeve being provided with a cylindrical fitting part and a female thread part to which the male thread part is screwed; a valve holder held by the valve shaft; a valve body fixed to the valve holder and capable of being brought into contact with and separated from the valve seat; the valve body is provided with a cylindrical embedded part into which the embedding part is embedded and a cylindrical holder base part, the holder base part is arranged in a sealing member holder in the valve body, and the valve body is provided with a through hole which is communicated with a valve shaft side space and a reverse valve shaft side space which are separated by the holder base part and can be opened and closed. The space between the outer periphery of the holder base and the inner periphery of the valve body is sealed, an annular sealing body is disposed between the inner periphery of the holder base and the outer periphery of the valve holder, and the gap between the fitting portion and the fitted portion in the radial direction is smaller than the gap between the outer periphery of the holder base and the inner periphery of the valve body.

Description

Technical Field

[0001] The utility model relates to an electric valve. Background Art

[0002] The motor-driven electric valve has a threaded mechanism in which an external threaded portion of a valve shaft rotated by a stepping motor is screwed into an internal threaded hole provided in a valve body. Through this threaded mechanism, the valve shaft is displaced in the axial direction while rotating around the axis, so that the gap between the valve element and the valve seat can be increased or decreased to control the flow rate.

[0003] For example, Patent Document 1 discloses an electric valve having a valve seat with a relatively large inner diameter in order to ensure the flow rate at the time of valve opening. In this electric valve, the valve element is slidably fitted inside a cylindrical holding member, and a sealing member disposed on the valve element seals between the cylindrical holding member and the valve element.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2013-130271.

[0007] Technical Problem to be Solved by the Utility Model

[0008] Here, the valve seat and the valve element disposed in the valve body have corresponding conical surfaces, and when the valve element is seated, the conical surfaces are in close contact with each other to perform the valve closing operation. Therefore, if the coaxiality between the cylindrical holding member and the valve seat is not ensured, eccentricity will occur between the valve element and the cylindrical holding member when the valve element is seated on the valve seat, and thus fluid leakage may occur from the sealing member. Therefore, in the assembly, the process of ensuring the coaxiality between the cylindrical holding member and the valve seat is important, but this results in time-consuming assembly. Summary of the Utility Model

[0009] Therefore, an object of the present utility model is to provide an electric valve that can suppress fluid leakage and the like even when it is relatively easily assembled.

[0010] Technical Means for Solving the Technical Problem

[0011] The electric valve of the present utility model has:

[0012] A valve body having a valve seat;

[0013] A valve shaft having an external threaded portion and rotated by a motor;

[0014] A guide sleeve having an internal threaded portion for screwing the external threaded portion and a cylindrical fitting portion, and being installed on the valve body;

[0015] A valve cage, which is held by the valve shaft;

[0016] A valve element, which is fixed to the valve cage and can contact / separate relative to the valve seat; and

[0017] A seal cage, which has a cylindrical part to be fitted for fitting the fitting part and a cylindrical cage base, and the cage base is disposed within the valve body,

[0018] The valve element has a through hole that can be opened and closed, and the through hole can communicate the space on the valve shaft side and the space on the side opposite to the valve shaft across the cage base,

[0019] The outer periphery between the cage base and the inner periphery of the valve body is sealed,

[0020] An annular seal is disposed between the inner periphery of the cage base and the outer periphery of the valve cage,

[0021] The radial clearance A between the fitting part and the part to be fitted is smaller than the clearance B between the outer periphery of the cage base and the inner periphery of the valve body.

[0022] Effects of the utility model

[0023] According to the present utility model, an electric valve can be provided that can suppress fluid leakage even when it is relatively easy to assemble. Description of the drawings

[0024] Figure 1 It is a longitudinal sectional view showing the electric valve according to the embodiment of the present utility model, shown in the closed valve state.

[0025] Figure 2 It is a longitudinal sectional view showing the electric valve according to the embodiment of the present utility model, shown in the intermediate valve opening state.

[0026] Figure 3 It is a longitudinal sectional view showing the electric valve according to the embodiment of the present utility model, shown in the fully open valve state.

[0027] Figure 4 It is an enlarged view showing Figure 3 the vicinity of the valve chamber of the electric valve shown.

[0028] Reference signs

[0029] 1 Electric valve

[0030] 10 Valve body

[0031] 11 Valve seat member

[0032] 11e Valve seat

[0033] 15 Guide Sleeve

[0034] 21 Valve Shaft

[0035] 23 Valve Cage

[0036] 24 First Valve Core

[0037] 25 Second Valve Core

[0038] 26 Helical Spring

[0039] 27 Thrust Bearing

[0040] 28 Washer

[0041] 29 Seal Cage

[0042] 30 Rotor

[0043] 35 Movable Stopper for Valve Closing Direction

[0044] 36 Movable Stopper for Valve Opening Direction

[0045] 50 Stator

[0046] 53 Stator Coil

[0047] 55 Fixed Stopper for Valve Closing Direction

[0048] 56 Fixed Stopper for Valve Opening Direction

[0049] BC Back Pressure Chamber

[0050] MC Intermediate Chamber

[0051] VC Valve Chamber

[0052] OR O - Ring

[0053] SD Sliding Part Detailed Embodiment

[0054] Hereinafter, with reference to the drawings, the embodiments of the present utility model will be described.

[0055] Figures 1 to 3 FIG. is a longitudinal sectional view showing the electric valve 1 according to the embodiment of the present utility model. Figure 4 It is an enlarged view showing Figure 3 the vicinity of the valve chamber of the electric valve 1 shown. Here, the upper side refers to the rotor side with respect to the valve seat, and the lower side refers to the valve seat side with respect to the rotor.

[0056] (Structure of Electric Valve)

[0057] The electric valve 1 includes: a bottomed cylindrical valve body 10 with an upper opening, a toped cylindrical housing 45 whose lower end is hermetically joined to the upper end face of the valve body 10 by welding or the like, a guide sleeve 15 fixed inside the valve body 10, a valve shaft 21 disposed inside the guide sleeve 15, a rotor 30 that is integrally rotatably connected and fixed to the valve shaft 21, and a stator 50 externally fitted to the outer periphery of the housing 45. The axis of the electric valve 1 is set as L.

[0058] The valve body 10 is continuously formed by a hollow cylindrical portion 10a and a bottom wall portion 10b. The wall thicknesses of the hollow cylindrical portion 10a and the bottom wall portion 10b are substantially equal. The inside of the hollow cylindrical portion 10a constitutes a valve chamber VC.

[0059] In the bottom wall portion 10b, a circular opening 10d is formed at its center, and a valve seat member 11 is fixed to the opening 10d by brazing or the like. Here, the valve seat member 11 constitutes a part of the valve body 10.

[0060] The valve seat member 11 is continuously formed by a reduced-diameter cylindrical portion 11a and an enlarged-diameter cylindrical portion 11b that are both hollow in the axial direction of the axis L. The reduced-diameter cylindrical portion 11a is fitted and brazed to the opening 10d. The end of the first pipe T1 is inserted into the inner periphery of the enlarged-diameter cylindrical portion 11b and connected by brazing or the like.

[0061] In Figure 4 the valve seat member 11 has: a cylindrical upper opening portion 11c near the upper end side, a conical intermediate opening portion 11f that tapers downward, and a cylindrical throttle passage 11d with a diameter smaller than that of the upper opening portion 11c. The first pipe T1 is arranged to abut against a stepped portion directly below the throttle passage 11d, and its inner diameter is larger than that of the throttle passage 11d. A conical valve seat 11e that expands upward is formed on the inner periphery of the upper end of the upper opening portion 11c.

[0062] In Figures 1 to 3 the hollow cylindrical portion 10a of the valve body 10, an inlet opening 10e is formed, and the end of the second pipe T2 is inserted into the inlet opening 10e and connected by brazing or the like. The axis of the inlet opening 10e is set as O. The axis O is orthogonal to the axis L.

[0063] The lower end of the housing 45 abuts against the upper end of the valve body 10 and is joined by welding, whereby the valve body 10 and the housing 45 are integrated in a sealed state. In addition, a flange-shaped disk 18 is disposed inside the upper end of the valve body 10 and the lower end of the housing 45. The flange-shaped disk 18 is preferably welded simultaneously over the entire circumference when the valve body 10 and the housing 45 are welded.

[0064] On the outer side of the housing 45, a yoke 51, a bobbin 52, and a stator coil 53 are arranged to form a stator 50, and its outer periphery is covered with a resin molding cover 58. In the present embodiment, the resin molding cover 58 covers the entire stator 50 including the upper part of the housing 45, but it may also cover only the periphery of the yoke 51. A stepping motor is constituted by a rotor 30 and a stator 50.

[0065] The stator coil 53 is connected to an external power supply circuit (not shown) via a substrate CB, a connector CN, and a wiring HN. The substrate CB and the connector CN are covered with another resin cover 57. By energizing and exciting the stator coil 53, the rotor 30 disposed in the housing 45 can rotate about the axis L. A molding resin MR is filled inside the resin cover 57.

[0066] The guide sleeve 15 disposed inside the rotor 30 is formed by continuously providing a solid cylindrical main body 15a and a hollow cylindrical portion 15b. An internal threaded hole (internal threaded portion) 15c is formed in the main body 15a so as to penetrate through the center thereof in the direction of the axis L. A flange-shaped disk 18 is fixed to the outer peripheral groove of the diameter-expanded portion 15e on the lower end side of the hollow cylindrical portion 15b. As described above, the flange-shaped disk 18 is welded to the upper end of the valve body 10, so that the guide sleeve 15 is fixed relative to the valve body 10. Pressure equalizing holes 15d are formed through the inner and outer circumferences of the hollow cylindrical portion 15b.

[0067] In addition, in order to set the control origin position of the rotor 30 and the valve shaft 21, a closing valve direction fixed stopper 55 having a rectangular cross-section is protruded upward on the upper surface of the main body 15a of the guide sleeve 15, and an opening valve direction fixed stopper 56 having a rectangular cross-section is protruded downward on the lower surface of the main body 15a of the guide sleeve 15. Here, the control origin position of the rotor 30 and the valve shaft 21 refers to the position when the closing valve direction movable stopper 35 abuts against the closing valve direction fixed stopper 55 and is locked, so that the rotor 30 and the valve shaft 21 reach the lowest descending position.

[0068] The valve shaft 21 is continuously provided with a small diameter portion 21a in which a ring-shaped connecting body 32 mounted on the rotor 30 is externally fitted, an external threaded portion 21b screwed into the internal threaded hole 15c of the guide sleeve 15, a valve shaft cylindrical portion 21c formed on the lower side compared with the external threaded portion 21b, an outer flange portion 21d extending radially outward from the lower end of the valve shaft cylindrical portion 21c, and a small cylindrical portion 21e protruding downward from the lower end of the valve shaft cylindrical portion 21c. The outer diameter of the small cylindrical portion 21e is smaller than the outer diameter of the valve shaft cylindrical portion 21c.

[0069] The closing valve direction movable stopper 35 is screwed onto the upper end portion of the external threaded portion 21b in the valve shaft 21 and is locked to the lower surface of the upper wall of the rotor 30. A stopper portion 35a having a rectangular cross-section is formed on the lower surface of the closing valve direction movable stopper 35.

[0070] In addition, in the valve opening direction, the movable stopper 36 is screwed onto the lower end portion of the external thread portion 21b of the valve shaft 21 and is engaged with the upper surface of the valve cage 23. A stopper portion 36a having a rectangular cross section is formed on the upper surface of the movable stopper 36 in the valve opening direction.

[0071] In Figure 4 this, a valve cage 23 is installed at the lower end of the valve shaft 21. The valve cage 23 is continuously provided with an outer wall portion 23a and an inner flange portion 23b extending radially inward from the upper end of the outer wall portion 23a. The outer wall portion 23a has an inner circumference with a diameter larger than that of the outer flange portion 21d, and the inner flange portion 23b has an inner circumference with a diameter smaller than that of the outer flange portion 21d. A circular opening 23c that can slidably fit with the valve shaft cylindrical portion 21c is formed at the center of the inner flange portion 23b. The outer circumference of the outer wall portion 23a is slidably fitted with the inner circumference of the hollow cylindrical portion 15b of the guide sleeve 15. In addition, a plurality of communication holes 23d that are arranged along the circumferential direction and penetrate in the radial direction are formed near the upper end of the outer wall portion 23a.

[0072] The lower end of the outer wall portion 23a is connected to the first valve element (also simply referred to as the valve element) 24. The first valve element 24 is continuously provided with an upper cylindrical portion 24a and a lower cylindrical portion 24b that are fixed to the upper portion of the outer wall portion 23a by fitting and pressing or welding. A tapered portion 24c that tapers downward is formed at the lower end of the lower cylindrical portion 24b. In addition, a through hole 24d that penetrates vertically along the axis L is formed in the first valve element 24. The through hole 24d communicates the space on the valve shaft side (the intermediate chamber MC above the first valve element 24) with the space on the side opposite to the valve shaft (the space below the first valve element 24 connected to the throttle passage 11d) with a seal cage 29 described later interposed therebetween.

[0073] A second valve element 25 is disposed inside the valve cage 23. The second valve element 25 is made of metal (for example, SUS), and has a substantially cylindrical valve element base portion 25a, a valve element flange portion 25b that extends radially outward from the upper end of the valve element base portion 25a, and a hemispherical portion 25c that is formed at the lower end of the valve element base portion 25a and has a spherical surface.

[0074] The upper end of the helical spring (elastic body) 26 abuts against the lower end of the valve element flange portion 25b, and its lower end abuts against the upper surface of the first valve element 24, thereby applying a force to the first valve element 24 in a direction to separate the second valve element 25 from the first valve element 24.

[0075] An annular thrust bearing 27 is disposed between the second valve element 25 and the valve shaft 21. The thrust bearing 27 is disposed around the small cylindrical portion 21e of the valve shaft 21 and abuts against the upper surface of the second valve element 25 and the lower surface of the outer flange portion 21d, thereby enabling the second valve element 25 and the valve shaft 21 to relatively rotate with low friction.

[0076] Further, a washer 28 as an annular plate is disposed between the outer flange portion 21d of the valve shaft 21 and the inner flange portion 23b of the valve cage 23. The washer 28 also enables the outer flange portion 21d and the inner flange portion 23b to relatively rotate with low friction.

[0077] A seal cage 29 is disposed between the valve cage 23 and the hollow cylindrical portion 10a of the valve body 10. The seal cage 29 is continuously formed by an annular cage base portion 29a, an annular cage flange portion 29b extending radially outward from the upper end of the cage base portion 29a, and a circular bottom wall portion 29c extending radially inward while being offset (and connected via a small cylindrical portion) from the lower end of the cage base portion 29a. An annular recess 29e is coaxially formed at the upper end of the cage base portion 29a (radially inside the cage flange portion 29b). The outer wall portion 23a of the valve cage 23, which protrudes downward from the valve cage 23, is slidably fitted into the cage opening 29d penetrating the bottom wall portion 29c.

[0078] The cage flange portion 29b is clamped with a gap from the inner periphery of the end portion of the housing 45 and is placed between the upper end of the hollow cylindrical portion 10a and the lower surface of the flange-shaped disk 18, and is welded as will be described later. The outer periphery of the lower end side enlarged diameter portion 15e of the guide sleeve 15 is disposed opposite to the inner periphery of the cage flange portion 29b. Further, the top end of the second pipe T2 is disposed in contact with the outer periphery of the bottom wall portion 29c, whereby the insertion positioning of the second pipe T2 can be performed.

[0079] An O-ring OR and a sliding member SD are disposed on the inner periphery of the cage base portion 29a sandwiched between the lower end of the guide sleeve 15 and the bottom wall portion 29c. An annular seal body is constituted by the O-ring OR and the sliding member SD. The sliding member SD is a soft cylindrical body made of a low-friction material such as PTFE having a friction coefficient lower than that of the O-ring OR, and is disposed between the O-ring OR and the outer wall portion 23a. Therefore, the cage base portion 29a and the outer wall portion 23a can relatively displace in the axial direction of the axis L, and at the same time, the fluid can be sealed by the O-ring OR and the sliding member SD. The sliding member SD may not be provided and only the O-ring OR may be disposed.

[0080] The internal space of the electric valve 1 (the space surrounded by the housing 45 and the valve body 10) is partitioned into a high-pressure valve chamber VC, an intermediate chamber MC inside the valve cage 23, and a back pressure chamber BC inside the housing 45. The O-ring OR and the sliding member SD seal between the valve chamber VC and the intermediate chamber MC.

[0081] Here, when the clearance between the outer periphery of the lower end side enlarged diameter portion (cylindrical fitting portion) 15e and the inner periphery of the annular concave portion (cylindrical fitted portion) 29e is set as A, and the clearance between the outer periphery of the cage base portion 29a and the inner periphery of the hollow cylindrical portion 10a of the valve body 10 is set as B, B > A holds.

[0082] In the present embodiment, as Figures 1 to 3 shown, the rotor 30, the valve shaft 21, the opening direction movable stopper 36, the valve cage 23, the washer 28, the thrust bearing 27, the second valve element 25, the helical spring 26, and the first valve element 24 can relatively displace in the axial direction of the axis L with respect to the guide sleeve 15 and the seal cage 29 fixed to the valve body 10. In addition, the valve cage 23 and the first valve element 24 can relatively displace in the axial direction of the axis L with respect to the valve shaft 21. Moreover, the second valve element 25 can relatively displace in the axial direction of the axis L with respect to the valve shaft 21 and the first valve element 24.

[0083] (Assembly process of the electric valve)

[0084] The assembly process of the electric valve 1 will be described. First, the guide sleeve 15 assembled with the flange-shaped disk 18 is joined to the seal cage 29 assembled with the O-ring OR and the sliding member SD to produce the first assembly. The seal cage 29 can be welded to the flange-shaped disk 18 at this moment, or can be welded simultaneously when the flange-shaped disk 18 is welded to the valve body 10. Thereby, the seal is made between the seal cage 29 and the valve body 10 (that is, between the outer periphery of the cage base portion 29a and the inner periphery of the valve body 10).

[0085] In addition, after installing the washer 28 and the valve cage 23 from the side of the external thread portion 21b of the valve shaft 21, the opening direction movable stopper 36 is screwed and installed on the external thread portion 21b. After that, after arranging the thrust bearing 27, the second valve element 25, and the helical spring 26 inside the valve cage 23, the first valve element 24 is welded to the lower end of the valve cage 23 to produce the second assembly.

[0086] The internal thread hole 15c of the first assembly is screwed to the external thread portion 21b of the second assembly formed in this way, and the closing direction movable stopper 35 is screwed to the external thread portion 21b protruding from the guide sleeve 15, and then the rotor 30 is assembled to produce the third assembly.

[0087] Furthermore, the valve seat member 11 is brazed to the valve body 10, and the valve shaft 21 of the third assembly and the valve seat member 11 are positioned coaxially using a jig or the like, and the third assembly is housed in the housing 45, and the valve body 10, the housing 45, and the flange-shaped disk 18 are fixed by welding. After that, the first pipe T1 and the second pipe T2 are brazed, and the stator 50 is installed on the housing 45, thereby completing the electric valve 1.

[0088] According to this embodiment, Figure 4 As shown in FIG. 1 , the gap A (preferably an interference fit) between the outer periphery of the lower end side enlarged diameter portion 15e and the inner periphery of the annular recessed portion 29e is smaller than the gap B between the outer periphery of the valve holder 23 and the inner periphery of the hollow cylindrical portion 10a of the valve body 10. By using this gap B, the valve holder 23 and the first valve element 24 are adjusted in the axis-orthogonal direction for each seal holder 29, so that the valve shaft 21 and the valve seat member 11 can be centered. The coaxiality of the guide sleeve 15 and the seal holder 29 is ensured by the accuracy of machining, so as long as the seal holder 29 is provided coaxially with the axis L of the valve body 10 (valve seat member 11), the coaxiality of the valve seat 11e and the first valve element 24 can be easily ensured, and fluid leakage can be suppressed.

[0089] (Electric valve operation)

[0090] Next, the operation of the electric valve 1 will be described in detail.

[0091] First, assume that the fluid (refrigerant) enters the valve chamber VC from the second pipe T2 and that the electric valve 1 is in Figure 1 At this time, the lower end of the descending valve shaft 21 presses the upper end of the second valve core 25, so the second valve core 25 overcomes the force of the coil spring 26 and descends, and the hemispherical portion 25c is maintained to close the upper end of the through hole 24d. Even if the second valve core 25 is tilted, the hemispherical portion 25c can properly close the upper end of the through hole 24d.

[0092] Furthermore, since the upper end of the first valve element 24 is pressed by the second valve element 25 , the semi-spherical portion 25 c is seated on the valve seat 11 e .

[0093] In the closed valve state, the tapered portion 24c is seated on the valve seat 11e, preventing the fluid from flowing out from the valve chamber VC into the first pipe T1. In addition, even if the fluid moves from the valve chamber VC to the intermediate chamber MC and the pressure in the intermediate chamber MC increases, the hemispherical portion 25c closes the upper end of the through hole 24d, which can prevent the fluid from flowing out from the intermediate chamber MC into the first pipe T1. In this state, the pressure of the valve chamber VC acts on the upper side of the first valve core 24, and the pressure of the first pipe T1 acts on the lower side of the first valve core 24, so the first valve core 24 is stably seated on the valve seat 11e.

[0094] If pulse power is supplied to the stator 50 through an external power circuit from the valve closed state, the rotor 30 and the valve shaft 21 are driven to rotate in one direction, and accordingly, the valve shaft 21 and the valve retainer 23 rotate and rise via a thread feed mechanism composed of the internal thread hole 15c and the external thread portion 21b.

[0095] As the valve shaft 21 rises, the pressing force that presses the second valve element 25 downward disappears. Therefore, as shown in Figure 2 , the second valve element 25 separates from the first valve element 24 due to the acting force of the coil spring 26. Then, the fluid in the intermediate chamber MC flows out toward the first pipe T1 through the through hole 24d and the throttle passage 11d. Therefore, the pressure in the intermediate chamber MC decreases and approaches the pressure in the first pipe T1. As a result, the pressures above and below the valve seat 11e cancel each other out (because the pressure difference above and below is canceled), so the first valve element 24 becomes easier to rise.

[0096] In addition, as the valve shaft 21 rises, the outer flange portion 21d also rises together, and upward force is applied to the inner flange portion 23b via the washer 28. Thus, the valve cage 23 rises in a pulled-up manner, so that the first valve element 24 separates from the valve seat 11e and becomes the fully open valve state as shown in Figure 3 . At this time, the valve cage 23 slides and rises relative to the sliding member SD that is radially inwardly pressed by the elastic force of the O-ring OR, so long-term wear resistance and sealing performance are ensured. In addition, when the outer flange portion 21d and the inner flange portion 23b rotate relative to each other, the washer 28 slides relative to them to ensure a low-friction state.

[0097] When the valve shaft 21 rises to a specified position, the movable stopper 36 for the valve opening direction abuts against the fixed stopper 56 for the valve opening direction and is locked. Thus, the rotation and rise of the rotor 30, the valve shaft 21, and the valve cage 23 are forcibly stopped.

[0098] Since the first valve element 24 separates from the valve seat 11e, the fluid flowing into the valve chamber VC from the second pipe T2 flows out toward the first pipe T1 via the valve seat 11e and the throttle passage 11d. The flow rate of the outflowing fluid is determined by the gap between the conical portion 24c and the valve seat 11e.

[0099] At this time, the intermediate chamber MC communicates with the valve chamber VC through the through hole 24d, so the pressure in the intermediate chamber MC is almost equal to the pressure in the valve chamber VC. In addition, the intermediate chamber MC communicates with the back pressure chamber BC through the communication hole 23d of the valve cage 23 and the pressure equalizing hole 15d of the guide sleeve 15, so the pressure in the intermediate chamber MC is almost equal to the pressure in the back pressure chamber BC.

[0100] On the other hand, if reverse characteristic pulse power supply is applied to the stator 50 from this fully open valve state through an external power supply circuit, the rotor 30 and the valve shaft 21 are driven to rotate in the other direction, and the valve shaft 21 and the valve cage 23 rotate and descend via the screw feed mechanism composed of the internal thread hole 15c and the external thread portion 21b.

[0101] As the valve shaft 21 descends, the outer flange portion 21d also descends together, so that the valve cage 23 also descends. Thus, the first valve element 24 seats on the valve seat 11e. Thereby, the fluid is prevented from passing through between the first valve element 24 and the valve seat 11e from the valve chamber VC.

[0102] In addition, after the first valve element 24 seats on the valve seat 11e, the second valve element 25 is pressed downward by the lower end of the valve shaft 21 and thus displaced against the force of the coil spring 26, and the lower end of the second valve element 25 abuts against the upper end of the first valve element 24. By the lower end of the second valve element 25 abutting against the upper end of the first valve element 24, a frictional force is generated between the two, so that the rotation of the second valve element 25 is forcibly stopped. In contrast, the rotation of the valve shaft 21 continues. At this time, when the valve shaft 21 and the second valve element 25 rotate relative to each other, the thrust bearing 27 slides relative to them to ensure a low-friction state.

[0103] By the second valve element 25 closing the upper end of the through hole 24d, the fluid is prevented from flowing out from the intermediate chamber MC toward the first pipe T1.

[0104] When the valve shaft 21 descends to a specified position, the movable stopper 35 in the valve closing direction abuts against the fixed stopper 55 in the valve closing direction and is locked, and the rotor 30 and the valve shaft 21 reach the lowest descending position. Even if pulse power supply is continued to the stator 50, the descent of the rotor 30 and the valve shaft 21 is forcibly stopped.

[0105] According to the present embodiment, when closing the valve, the first valve element 24 seats on the valve seat 11e, and the second valve element 25 closes the through hole 24d of the first valve element 24. Therefore, regardless of the tightening force of the O-ring OR, the influence of deterioration due to heat, etc., it is possible to suppress the leakage of fluid from the valve chamber VC to the throttle passage 11d when closing the valve. Thereby, an O-ring OR with a lower tightening force can be used, and thereby the sliding resistance of the O-ring OR can be reduced. Therefore, the motor load during the displacement of the valve shaft 21 can be reduced, and in addition, the degree of freedom in the selection of the O-ring OR becomes higher.

[0106] Assume that in the case of fluid leakage from the O-ring OR or the sliding member SD when closing the valve, the fluid in the valve chamber VC moves from the communication hole 23d to the intermediate chamber MC, so that the pressure in the intermediate chamber MC becomes equal to the pressure in the valve chamber VC. Therefore, the pressure difference caused by the pressure (low pressure) in the through hole 24d and the pressure (high pressure) in the intermediate chamber MC acts on the second valve element 25. However, when opening the valve, since the through hole 24d is first opened by the second valve element 25, the fluid in the intermediate chamber MC moves toward the throttle passage 11d side in the valve seat member 11 via the through hole 24d. Therefore, the fluid pressures above and below the first valve element 24 cancel each other out, so that there will be no obstacle when the first valve element 24 opens the valve next.

[0107] In the present embodiment, an O-ring OR and a sliding member SD are arranged on the radially outer side of the valve cage 23 via a seal cage 29 fixed to the valve body 10. Therefore, their diameters can be set relatively large. As a result, the deviation of the tightening force of the O-ring OR can be suppressed, and even when an excessive pressure difference is applied to the O-ring OR and the sliding member SD, it is difficult to cause damage or the like.

[0108] The present utility model is not limited to the above embodiments. For example, although the second valve core is constituted by a cylindrical member having a hemispherical portion formed at its end, the second valve core may also be constituted by fixing a spherical body to the end of the cylindrical member.

[0109] This specification includes the following disclosed content.

[0110] (First mode)

[0111] An electric valve, comprising:

[0112] A valve body having a valve seat;

[0113] A valve shaft having an external thread portion and being driven by a motor to rotate;

[0114] A guide sleeve having an internal thread portion for screwing with the external thread portion and a cylindrical fitting portion, and being mounted on the valve body;

[0115] A valve cage held by the valve shaft;

[0116] A valve core fixed to the valve cage and capable of contacting / separating from the valve seat; and

[0117] A seal cage having a cylindrical fitted portion for fitting with the fitting portion and a cylindrical cage base portion, and the cage base portion is arranged inside the valve body,

[0118] The valve core has a through hole that can be opened and closed, and the through hole can communicate the space on the valve shaft side and the space on the anti-valve shaft side across the cage base portion,

[0119] The outer periphery of the cage base portion is sealed with the inner periphery of the valve body,

[0120] A ring-shaped seal is arranged between the inner periphery of the cage base portion and the outer periphery of the valve cage,

[0121] The clearance A in the radial direction between the fitting portion and the fitted portion is smaller than the clearance B between the outer periphery of the cage base portion and the inner periphery of the valve body.

[0122] (Second mode)

[0123] In the electric valve of the first mode, the annular seal is composed of an O-ring and a sliding member. The O-ring is disposed on the side of the seal holder, the sliding member is disposed on the side of the valve holder, and the coefficient of friction is smaller than that of the O-ring.

[0124] (Third mode)

[0125] In the electric valve of the first mode or the second mode, the seal holder has a holder flange portion that extends radially outward from the holder base portion, and the holder flange portion is fixed to the end portion of the valve body.

[0126] (Fourth mode)

[0127] In the electric valve of the third mode, the end portion of the housing is fixed to the end portion of the valve body. The housing houses the rotor of the motor, and the outer edge of the holder flange portion is fixed with a gap relative to the housing.

[0128] (Fifth mode)

[0129] In the electric valve of the third mode or the fourth mode, the engaged portion is formed on the radially inner side of the holder flange portion.

[0130] (Sixth mode)

[0131] In the electric valve of any one of the first mode to the fifth mode, the top end of the pipe inserted into the valve body in a direction intersecting the axis of the valve body abuts against the seal holder.

[0132] (Seventh mode)

[0133] In the electric valve of any one of the first mode to the sixth mode, the engaging portion and the engaged portion are engaged in an interference fit relationship.

Claims

1. An electric valve, characterized in that: have: a valve body having a valve seat; A valve shaft having an external threaded portion and driven to rotate by a motor; a guide sleeve including an internal threaded portion for threading the external threaded portion and a cylindrical fitting portion, and mounted on the valve body; a valve holder, the valve holder being held by the valve shaft; a valve core, which is fixed to the valve holder and can contact and separate relative to the valve seat; as well as a seal holder including a cylindrical engaged portion into which the engaging portion engages and a cylindrical holder base, wherein the holder base is arranged in the valve body, The valve core has an openable and closable through hole, and the through hole can connect the space on the valve shaft side and the space on the anti-valve shaft side through the retainer base. The outer periphery of the retainer base and the inner periphery of the valve body are sealed. An annular sealing body is arranged between the inner periphery of the retainer base and the outer periphery of the valve retainer. A radial gap (A) between the fitting portion and the fitted portion is smaller than a gap (B) between an outer periphery of the retainer base and an inner periphery of the valve body.

2. The electric valve according to claim 1, characterized in that: The annular seal body is composed of an O-ring and a sliding component. The O-ring is arranged on the seal holder side, and the sliding component is arranged on the valve holder side and has a smaller friction coefficient than the O-ring.

3. The electric valve according to claim 1, characterized in that: The seal holder has a holder flange portion extending radially outward from the holder base portion, and the holder flange portion is fixed to an end portion of the valve body.

4. The electric valve according to claim 3, characterized in that: An end of a housing is fixed to an end of the valve body, and the housing accommodates a rotor of the motor. An outer edge of the retainer flange portion is fixed to the housing with a gap therebetween.

5. The electric valve according to claim 3, characterized in that: The fitted portion is formed radially inward of the retainer flange portion.

6. The electric valve according to claim 1, characterized in that: The tip of a pipe inserted into the valve body in a direction intersecting the axis of the valve body abuts against the seal holder.

7. The electric valve according to claim 1, characterized in that: The engaging portion and the engaged portion engage with each other in an interference fit relationship.

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