Electric valve

Abstract

The invention provides an electric valve which is relatively low in cost and can be stably used for a long time. An electrically operated valve is provided with: a valve body having a valve seat, a valve chamber, and an orifice passage; a valve shaft which is driven by the motor to rotate and is displaced in the axial direction; a valve holder which is held by the valve shaft; a first valve body which is fixed to the valve holder and has a through hole; a second valve body disposed between the valve shaft and the first valve body; an elastic body that biases the first valve body in a direction in which the second valve body is separated from the first valve body; and a seal holder having a holder base portion disposed within the valve body, the space between the outer periphery of the holder base portion and the inner periphery of the valve body being sealed, and an annular seal body disposed between the inner periphery of the holder base portion and the outer periphery of the valve holder. In a state in which the first valve body is seated in the valve seat in the valve chamber, the orifice passage and the internal space of the valve body can communicate with each other via the through hole, and the through hole is closed when the second valve body is in contact with the first valve body.

Description

Technical Field

[0001] This invention relates to an electric valve. Background Technology

[0002] Electric valves driven by electric motors have a threaded mechanism that engages the external thread of a valve shaft, which is rotated by a stepper motor, with an internal threaded hole in the valve body. This threaded mechanism allows the valve shaft to rotate about its axis while simultaneously displacing it along the axial direction, thereby increasing or decreasing the gap between the valve core and the valve seat to control the flow rate.

[0003] For example, Patent Document 1 discloses an electric valve with a large inner diameter valve seat to ensure flow rate when the valve is opened. In such an electric valve, when the valve is closed, fluid leakage from the valve chamber to the low-pressure side piping needs to be suppressed at two points: between the valve core seated on the valve seat and the valve seat, and between the O-ring that seals the base component fixed to the valve body and the valve core.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2019-65898

[0007] The technical problem that the invention aims to solve

[0008] To improve the sealing between the base component and the valve core, it is necessary to increase the clamping force of the O-ring. However, this can lead to problems such as reduced sliding performance or increased load on the motor. In addition, it is best to select O-rings made of materials that are less susceptible to heat-induced degradation, for example, for long-term use. However, this also limits the freedom of material selection. Summary of the Invention

[0009] Therefore, the purpose of this invention is to provide an electric valve that is relatively inexpensive and can be used stably for a long period of time.

[0010] Technical means for solving technical problems

[0011] The electric valve of the present invention is characterized by having:

[0012] The valve body has a valve seat, a valve chamber, and a throttling orifice passage.

[0013] The valve shaft is driven by an electric motor to rotate and displace along its axial direction;

[0014] A valve retainer that is held to the valve shaft;

[0015] A first valve core, which is fixed to the valve holder and has a through hole;

[0016] A second valve core is disposed between the valve shaft and the first valve core;

[0017] An elastomer, which applies a force to the first valve core in a direction that moves the second valve core away from the first valve core; and

[0018] A sealing retainer having a retainer base disposed within the valve body.

[0019] The outer periphery of the cage base is sealed to the inner periphery of the valve body.

[0020] An annular seal is disposed between the inner circumference of the base of the retainer and the outer circumference of the valve retainer.

[0021] With the first valve core seated in the valve chamber, the throttling orifice passage and the internal space of the valve body can be connected via the through hole.

[0022] When the second valve core abuts against the first valve core, the through hole is closed.

[0023] Invention Effects

[0024] According to the present invention, an electric valve that is relatively inexpensive and can be used stably for a long period of time can be provided. Attached Figure Description

[0025] Figure 1 This is a longitudinal sectional view of the electric valve according to an embodiment of the present invention, shown in the closed state.

[0026] Figure 2 This is a longitudinal sectional view of the electric valve according to an embodiment of the present invention, shown in the middle open state.

[0027] Figure 3 This is a longitudinal sectional view of the electric valve according to an embodiment of the present invention, shown in the fully open state.

[0028] Figure 4 It is Figure 3 The diagram shows an enlarged view of the vicinity of the valve chamber of the electric valve. Detailed Implementation

[0029] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0030] Figures 1-3 This is a longitudinal sectional view showing the electric valve 1 according to an embodiment of the present invention. Figure 4 It is Figure 3The diagram shows an enlarged view of the vicinity of the valve chamber of the electric valve 1. Here, "above" refers to the rotor side relative to the valve seat, and "below" refers to the valve seat side relative to the rotor.

[0031] (Structure of an electric valve)

[0032] The electric valve 1 comprises: a bottomed cylindrical valve body 10 with an open top; a topped cylindrical housing 45 sealed to the upper end face of the valve body 10 by welding or the like; a guide rod 15 fixed to the inner side of the valve body 10; a valve shaft 21 disposed on the inner side of the guide rod 15; a rotor 30 connected and fixed to the valve shaft 21 in a manner that allows it to rotate integrally with the valve shaft 21; and a stator 50 externally embedded in the outer periphery of the housing 45. The axis of the electric valve 1 is defined as L.

[0033] The valve body 10 is formed by continuously providing 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 approximately equal. The inner side of the hollow cylindrical portion 10a forms the valve chamber VC.

[0034] In the bottom wall portion 10b, a circular opening 10d is formed in the center. A valve seat component 11 is fixed to the opening 10d by brazing or the like. Here, the valve seat component 11 constitutes part of the valve body 10.

[0035] The valve seat component 11 is formed by continuously arranging a hollow, reduced-diameter cylindrical portion 11a and an expanded-diameter cylindrical portion 11b along the axis L. The reduced-diameter cylindrical portion 11a is fitted into the opening 10d and brazed. The end of the first piping T1 is inserted into the inner circumference of the expanded-diameter cylindrical portion 11b and connected by brazing or the like.

[0036] exist Figure 4 In this design, the valve seat component 11 has: an upper opening 11c that is cylindrical from the upper end; a conical middle opening 11f that narrows towards the lower end; and a cylindrical throttling orifice passage 11d with a diameter smaller than that of the upper opening 11c. The first pipe T1 is configured to abut against a stepped portion directly below the throttling orifice passage 11d, and its inner diameter is larger than that of the throttling orifice passage 11d. A conical valve seat 11e that widens towards the upper end of the upper opening 11c is formed on the inner circumference of the upper end.

[0037] exist Figures 1-3 In the valve body 10, an inlet opening 10e is formed in the hollow cylindrical portion 10a. The end of the second piping 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.

[0038] The lower end of the housing 45 abuts against the upper end of the valve body 10, and they are joined by welding, thereby integrating the valve body 10 and the housing 45 in a sealed state. Furthermore, a flange-shaped disc 18 is disposed on the inner side of the lower end of the housing 45 at the upper end of the valve body 10. Preferably, the flange-shaped disc 18 is welded around its entire circumference simultaneously during the welding of the valve body 10 and the housing 45.

[0039] On the outside of the housing 45, a yoke 51, a winding frame 52, and a stator coil 53 are arranged to form a stator 50, the outer periphery of which is covered by a resin molding cover 58. In this embodiment, the resin molding cover 58 includes the upper part of the housing 45 and covers the entire stator 50, but it may also only cover the area around the yoke 51. The rotor 30 and the stator 50 constitute a stepper motor.

[0040] The stator coil 53 is connected to an external power supply circuit (not shown) via a substrate CB, a connector CN, and wiring HN. The substrate CB and connector CN are covered by a separate resin cover 57. By energizing the stator coil 53, the rotor 30 disposed within the housing 45 can rotate about the axis L. The interior of the resin cover 57 is filled with molding resin MR.

[0041] The guide rod 15, disposed inside the rotor 30, is formed by continuously assembling a solid cylindrical body 15a and a hollow cylindrical portion 15b. An internally threaded hole (internal thread portion) 15c is formed on the body 15a, penetrating the center of the body 15a along the axis L. A flange-shaped disk 18 is fixed to the outer peripheral groove of the lower end expansion portion 15e of the hollow cylindrical portion 15b. The flange-shaped disk 18 is welded to the upper end of the valve body 10 as described above, thereby fixing the guide rod 15 relative to the valve body 10. A pressure equalization hole 15d is formed in the hollow cylindrical portion 15b, penetrating both its inner and outer circumferences.

[0042] Furthermore, to set the control origin position of the rotor 30 and valve shaft 21, a rectangular-section fixed stop 55 for the valve closing direction is provided protruding upward on the upper surface of the main body 15a of the guide rod 15. Conversely, a rectangular-section fixed stop 56 for the valve opening direction is provided protruding downward on the lower surface of the main body 15a of the guide rod 15. Here, the control origin position of the rotor 30 and valve shaft 21 refers to the position where the movable stop 35 for the valve closing direction abuts against the fixed stop 55 for the valve closing direction and is locked, and the rotor 30 and valve shaft 21 reach their lowest descending position.

[0043] The valve shaft 21 is formed by continuously assembling a small-diameter portion 21a with an annular connecting body 32 installed on the rotor 30, an externally threaded portion 21b that screws into the internally threaded hole 15c of the guide rod 15, a valve shaft cylindrical portion 21c formed on the lower side of the externally threaded portion 21b, an externally protruding 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.

[0044] A movable stop 35 for closing the valve is screwed onto the upper end of the external threaded portion 21b in the valve shaft 21 and is locked onto the lower surface of the upper wall of the rotor 30. A stop portion 35a with a rectangular cross-section is formed on the lower surface of the movable stop 35 for closing the valve.

[0045] Additionally, a movable stop 36 for the valve opening direction is screwed onto the lower end of the external thread portion 21b of the valve shaft 21 and is locked to the upper surface of the valve retainer 23. A stop portion 36a with a rectangular cross-section is formed on the upper surface of the movable stop 36 for the valve opening direction.

[0046] exist Figure 4 In this design, a valve retainer 23 is mounted at the lower end of the valve shaft 21. The valve retainer 23 is continuously formed by 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 is formed in the center of the inner flange portion 23b, which can slide and fit into the cylindrical portion 21c of the valve shaft. The outer circumference of the outer wall portion 23a slides freely into the inner circumference of the hollow cylindrical portion 15b of the guide rod 15. In addition, a plurality of connecting holes 23d are formed near the upper end of the outer wall portion 23a, arranged circumferentially and extending radially.

[0047] The lower end of the outer wall portion 23a is connected to the first valve core (also simply referred to as the valve core) 24. The first valve core 24 is formed by continuously providing an upper cylindrical portion 24a and a lower cylindrical portion 24b that are fixed to the outer wall portion 23a by fitting, pressing, or welding with it. A tapered portion 24c that narrows downwards is formed at the lower end of the lower cylindrical portion 24b. In addition, a through hole 24d is formed in the first valve core 24, extending vertically along the axis L. The through hole 24d connects the space on the valve shaft side (the intermediate chamber MC above the first valve core 24) and the space on the opposite side of the valve shaft (the space below the first valve core 24 connected to the throttle orifice passage 11d) through the sealing retainer 29 described later.

[0048] A second valve core 25 is disposed inside the valve holder 23. The second valve core 25 is made of metal (e.g., SUS) and has: a generally cylindrical valve core base 25a; a valve core flange 25b extending radially outward from the upper end of the valve core base 25a; and a hemispherical portion 25c formed at the lower end of the valve core base 25a and having a spherical surface.

[0049] The helical spring (elastic body) 26 abuts its upper end against the lower end of the valve core flange 25b and its lower end against the upper surface of the first valve core 24, applying force to the first valve core 24 in a direction that moves the second valve core 25 away from the first valve core 24.

[0050] An annular thrust bearing 27 is disposed between the second valve core 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 core 25 and the lower surface of the outer flange portion 21d, which allows the second valve core 25 and the valve shaft 21 to rotate relative to each other with low friction.

[0051] Furthermore, a washer 28, which serves 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 retainer 23. The washer 28 also allows the outer flange portion 21d and the inner flange portion 23b to rotate relative to each other with low friction.

[0052] A sealing retainer 29 is disposed between the valve retainer 23 and the hollow cylindrical portion 10a of the valve body 10. The sealing retainer 29 is continuously formed by an annular retainer base 29a, an annular retainer flange portion 29b extending radially outward from the upper end of the retainer base 29a, and a circular bottom wall portion 29c offset from the lower end of the retainer base 29a (connected via a small cylindrical portion) and extending radially outward. An annular recess 29e is coaxially formed at the upper end of the retainer base 29a (radially inward from the retainer flange portion 29b). The outer wall portion 23a of the valve retainer 23 is slidably fitted into the retainer opening 29d that passes through the bottom wall portion 29c, and the outer wall portion 23a protrudes downward from the valve retainer 23.

[0053] The retainer flange 29b is held between the upper end of the hollow cylindrical portion 10a and the lower surface of the flange-shaped disk 18, spaced further radially inward than the inner circumference of the end of the housing 45, and is welded as described later. The outer circumference of the lower end side expansion portion 15e of the guide rod 15 is arranged opposite to the inner circumference of the retainer flange 29b. Furthermore, the top end of the second pipe T2 is positioned to abut against the outer circumference of the bottom wall portion 29c, thereby enabling the insertion and positioning of the second pipe T2.

[0054] An O-ring OR and a sliding member SD are disposed on the inner circumference of the cage base 29a, which is sandwiched between the lower end of the guide rod 15 and the bottom wall portion 29c. The O-ring OR and the sliding member SD form an annular seal. The sliding member SD is a flexible cylindrical body made of a low-friction material such as PTFE, which has a lower coefficient of friction than the O-ring OR, and is disposed between the O-ring OR and the outer wall portion 23a. Therefore, the cage base 29a and the outer wall portion 23a can be displaced relative to each other in the axial direction L, and the fluid can be sealed using the O-ring OR and the sliding member SD. Alternatively, the sliding member SD may be omitted, and only the O-ring OR may be provided.

[0055] The internal space of the electric valve 1 (the space surrounded by the housing 45 and the valve body 10) is divided into a high-pressure valve chamber VC, an intermediate chamber MC within the valve retainer 23, and a back pressure chamber BC within the housing 45. An O-ring OR and a sliding component SD seal the space between the valve chamber VC and the intermediate chamber MC.

[0056] Here, when the gap between the outer periphery of the lower end side expansion portion (cylindrical fitting portion) 15e and the inner periphery of the annular recess (cylindrical fitted portion) 29e is set as A, and the gap between the outer periphery of the retainer base portion 29a and the inner periphery of the hollow cylindrical portion 10a of the valve body 10 is set as B, B > A is true.

[0057] In this embodiment, such as Figures 1-3 As shown, the rotor 30, valve shaft 21, movable stop 36 for valve opening direction, valve retainer 23, washer 28, thrust bearing 27, second valve core 25, coil spring 26, and first valve core 24 are capable of relative displacement in the L-axis direction relative to the guide rod 15 and sealing retainer 29 fixed to the valve body 10. Furthermore, the valve retainer 23 and first valve core 24 are capable of relative displacement in the L-axis direction relative to the valve shaft 21. Moreover, the second valve core 25 is capable of relative displacement in the L-axis direction relative to the valve shaft 21 and the first valve core 24.

[0058] (Assembly process of electric valve)

[0059] The assembly process of the electric valve 1 will be described. First, the guide rod 15, on which the flange-shaped disc 18 is mounted, is joined with the sealing retainer 29, on which the O-ring OR and the sliding component SD are mounted, thus creating the first assembly. The sealing retainer 29 can be welded to the flange-shaped disc 18 at this time, or it can be welded simultaneously with the flange-shaped disc 18 being welded to the valve body 10. Thus, a seal is formed between the sealing retainer 29 and the valve body 10 (i.e., the outer periphery of the retainer base 29a and the inner periphery of the valve body 10).

[0060] Furthermore, after installing the washer 28 and the valve retainer 23 from the external thread portion 21b of the valve shaft 21, the valve opening direction is achieved by screwing the movable stop 36 into the external thread portion 21b. Then, based on the arrangement of the thrust bearing 27, the second valve core 25, and the coil spring 26 within the valve retainer 23, the first valve core 24 is welded to the lower end of the valve retainer 23, thereby creating the second assembly.

[0061] The rotor 30 is installed on the basis of screwing the internal threaded hole 15c of the first component into the external threaded portion 21b of the second component thus formed, and screwing the movable stop 35 for the valve closing direction into the external threaded portion 21b protruding from the guide rod 15, thereby producing the third component.

[0062] Furthermore, a valve seat component 11 is brazed onto the valve body 10. A clamp or similar device is used to coaxially position the valve shaft 21 of the third component and the valve seat component 11. The third component is then housed within the housing 45, and the valve body 10, housing 45, and flange-shaped disc 18 are fixed by welding. Afterward, piping T1 and T2 are brazed, and the stator 50 is mounted onto the housing 45, thus completing the electric valve 1.

[0063] According to this embodiment, such as Figure 4 As shown, the gap A (preferably an interference fit) between the outer periphery of the lower end side expansion portion 15e and the inner periphery of the annular recess 29e is smaller than the gap B between the outer periphery of the valve retainer 23 and the inner periphery of the hollow cylindrical portion 10a of the valve body 10. Using this gap B, the valve retainer 23 and the first valve core 24, together with the sealing retainer 29, are adjusted along the orthogonal direction of the axis, thereby enabling the centering of the valve shaft 21 and the valve seat component 11. Since the coaxiality of the guide rod 15 and the sealing retainer 29 is ensured with machining precision, if the sealing retainer 29 and the axis L of the valve body 10 (valve seat component 11) are coaxially arranged, the coaxiality of the valve seat 11e and the first valve core 24 can be easily ensured, thus suppressing fluid leakage.

[0064] (Action of the electric valve)

[0065] Next, the operation of electric valve 1 will be explained in detail.

[0066] First, assume that the fluid (refrigerant) enters the valve chamber VC from the second pipe T2, and assume that the electric valve 1 is in the position... Figure 1 The valve is in the closed state as shown. At this time, because the lower end of the descending valve shaft 21 presses against the upper end of the second valve core 25, the second valve core 25 descends against the force of the coil spring 26, maintaining the state in which the hemispherical portion 25c closes the upper end of the through hole 24d. Even when the second valve core 25 is tilted, the hemispherical portion 25c can still properly close the upper end of the through hole 24d.

[0067] In addition, since the upper end of the first valve core 24 is pressed by the second valve core 25, the hemispherical part 25c sits on the valve seat 11e.

[0068] In the closed state, the cone-shaped portion 24c sits on the valve seat 11e, thereby preventing fluid from flowing out of the valve chamber VC into the first piping T1. Furthermore, even if fluid moves from the valve chamber VC to the intermediate chamber MC, causing an increase in pressure within the intermediate chamber MC, the flow of fluid from the intermediate chamber MC into the first piping T1 is also suppressed by the hemispherical portion 25c sealing the upper end of the through hole 24d. In this state, the pressure of the valve chamber VC acts above the first valve core 24, and the pressure of the first piping T1 acts below the first valve core 24, thus ensuring that the first valve core 24 is stably seated on the valve seat 11e.

[0069] If pulse power is supplied to the stator 50 from the external power circuit from the closed valve state, the rotor 30 and the valve shaft 21 are driven to rotate in one direction, and correspondingly the valve shaft 21 and the valve holder 23 rise while rotating via the threaded feed mechanism consisting of the internal threaded hole 15c and the external threaded portion 21b.

[0070] As the valve shaft 21 rises, the downward pressing force on the second valve core 25 disappears, therefore, as Figure 2 As shown, the second valve core 25 separates from the first valve core 24 under the force of the helical spring 26. Consequently, the fluid in the intermediate chamber MC flows out to the first piping T1 side through the through hole 24d and the throttling orifice passage 11d, thus reducing the pressure in the intermediate chamber MC to a level close to the pressure in the first piping T1. Therefore, due to the pressure balance across the valve seat 11e (the pressure difference is eliminated), the first valve core 24 easily rises.

[0071] Furthermore, as the valve shaft 21 rises, the outer flange 21d also rises, and the inner flange 23b is exerted upward force via the washer 28. This causes the valve retainer 23 to rise in a suspended manner, thereby allowing the first valve core 24 to separate from the valve seat 11e and become... Figure 3 The valve is fully open as shown. In this state, the valve retainer 23 rises while sliding relative to the sliding member SD, which is forced radially inward by the elasticity of the O-ring OR, thus ensuring long-term wear resistance and sealing. Furthermore, the gasket 28 slides relative to the outer flange 21d and the inner flange 23b as they rotate relative to each other, ensuring a low-friction condition.

[0072] As the valve shaft 21 rises to the specified position, the movable stop 36 in the valve opening direction abuts against the fixed stop 56 in the valve opening direction and is thus stopped, thereby forcibly stopping the rotation and rising of the rotor 30, the valve shaft 21, and the valve holder 23.

[0073] As the first valve core 24 moves away from the valve seat 11e, the fluid flowing into the valve chamber VC from the second pipe T2 flows out through the valve seat 11e and the throttling orifice passage 11d towards the first pipe T1. The flow rate of the outflowing fluid is determined by the gap between the cone portion 24c and the valve seat 11e.

[0074] At this time, the intermediate chamber MC is connected to the valve chamber VC through the through hole 24d, so the pressure in the intermediate chamber MC is approximately equal to the pressure in the valve chamber VC. In addition, since the intermediate chamber MC is connected to the back pressure chamber BC through the through hole 23d of the valve retainer 23 and the pressure equalization hole 15d of the guide rod 15, the pressure in the intermediate chamber MC is approximately equal to the pressure in the back pressure chamber BC.

[0075] On the other hand, if the stator 50 is supplied with a pulse power supply with reverse characteristics from the external power circuit from the fully open valve state, the rotor 30 and the valve shaft 21 are driven to rotate in the other direction, and the valve shaft 21 and the valve holder 23 rotate and descend simultaneously via the threaded feed mechanism consisting of the internal threaded hole 15c and the external threaded portion 21b.

[0076] As the valve shaft 21 descends, the outer flange 21d also descends, thereby causing the valve retainer 23 to descend as well, and the first valve core 24 to settle into the valve seat 11e. This prevents fluid from flowing from the valve chamber VC between the first valve core 24 and the valve seat 11e.

[0077] Furthermore, after the first valve core 24 is seated in the valve seat 11e, the second valve core 25 is pressed downward by the lower end of the valve shaft 21, overcoming the force of the coil spring 26 and displacing itself. The lower end of the second valve core 25 abuts against the upper end of the first valve core 24. Because the lower end of the second valve core 25 abuts against the upper end of the first valve core 24, friction is generated between them, thus forcibly stopping the rotation of the second valve core 25. Conversely, the rotation of the valve shaft 21 continues. At this time, the thrust bearing 27 slides relative to the valve shaft 21 and the second valve core 25 as they rotate relative to each other, ensuring a low-friction state.

[0078] The second valve core 25 closes the upper end of the through hole 24d, thereby preventing fluid from flowing out of the intermediate chamber MC toward the first pipe T1.

[0079] When the valve shaft 21 descends to the specified position, the movable stop 35 in the valve closing direction abuts against the fixed stop 55 in the valve closing direction and is blocked. The rotor 30 and the valve shaft 21 reach the lowest position. Even if the stator 50 continues to be pulsed with power, the descent of the rotor 30 and the valve shaft 21 is forcibly stopped.

[0080] According to this embodiment, when the valve is closed, the first valve core 24 sits on the valve seat 11e, and the second valve core 25 seals the through hole 24d of the first valve core 24. Therefore, regardless of the clamping force of the O-ring OR or the effects of heat-induced deterioration, leakage of fluid from the valve chamber VC to the throttling orifice passage 11d during valve closure can be suppressed. Consequently, an O-ring OR with a lower clamping force can be used, thereby reducing the sliding resistance of the O-ring OR, thus reducing the motor load during valve shaft 21 displacement, and increasing the freedom of choice in selecting the O-ring OR.

[0081] Assuming fluid leakage occurs from the O-ring OR or sliding component SD when the valve is closed, the fluid in valve chamber VC moves from the connecting hole 23d to the intermediate chamber MC, thereby equalizing the pressure in the intermediate chamber MC with the pressure in valve chamber VC. Therefore, a pressure difference exists on the second valve core 25 caused by the pressure in the through hole 24d (low pressure) and the pressure in the intermediate chamber MC (high pressure). However, when the valve is opened, the second valve core 25 first opens the through hole 24d, allowing the fluid in the intermediate chamber MC to move through the through hole 24d towards the throttling orifice passage 11d in the valve seat component 11. Thus, the fluid pressure above and below the first valve core 24 is balanced, and therefore, no obstruction occurs when the first valve core 24 opens the valve.

[0082] In this embodiment, an O-ring OR and a sliding member SD are arranged radially outside the valve retainer 23 via a sealing retainer 29 fixed to the valve body 10, allowing for a relatively large diameter. This suppresses deviations in the clamping force of the O-ring OR, and even when excessive differential pressure is applied to the O-ring OR and the sliding member SD, breakage is less likely.

[0083] The present invention is not limited to the embodiments described above. Although the second valve core may be constituted, for example, by a cylindrical component with a hemispherical portion formed at the end, it may also be constituted by fixing a spherical body to the end of the cylindrical component. In addition, the sealing retainer 29, the O-ring OR, and the sliding component SD may not necessarily be provided.

[0084] This specification includes the disclosure of the following inventions.

[0085] (First aspect)

[0086] An electric valve, characterized in that,

[0087] have:

[0088] The valve body has a valve seat, a valve chamber, and a throttling orifice passage.

[0089] The valve shaft is driven by an electric motor to rotate and displace along its axial direction;

[0090] A valve retainer that is held to the valve shaft;

[0091] A first valve core, which is fixed to the valve holder and has a through hole;

[0092] A second valve core is disposed between the valve shaft and the first valve core;

[0093] An elastomer, which applies a force to the first valve core in a direction that moves the second valve core away from the first valve core; and

[0094] A sealing retainer having a retainer base disposed within the valve body.

[0095] The outer periphery of the cage base is sealed to the inner periphery of the valve body.

[0096] An annular seal is disposed between the inner circumference of the base of the retainer and the outer circumference of the valve retainer.

[0097] With the first valve core seated in the valve chamber, the throttling orifice passage and the internal space of the valve body can be connected via the through hole.

[0098] When the second valve core abuts against the first valve core, the through hole is closed.

[0099] (Second aspect)

[0100] According to the electric valve of the first aspect, it is characterized in that,

[0101] When the valve axis is displaced towards the valve seat, after the first valve core is seated on the valve seat, the second valve core closes the through hole of the first valve core.

[0102] When the valve axis is displaced in the direction opposite to the valve seat side, the first valve core leaves the valve seat after the second valve core leaves the first valve core.

[0103] (Third aspect)

[0104] The electric valve according to the first or second aspect is characterized in that,

[0105] The annular seal is composed of an O-ring disposed on the side of the seal holder and a sliding component disposed on the side of the valve holder, which has a smaller coefficient of friction than the O-ring.

[0106] (Fourth aspect)

[0107] The electric valve according to any one of the first to third aspects is characterized in that,

[0108] With the first valve core seated on the valve seat, the throttling orifice passage can communicate with the intermediate chamber inside the valve holder via the through hole, and the annular seal seals the valve chamber and the intermediate chamber.

[0109] (Fifth aspect)

[0110] According to the electric valve of the fourth aspect, the intermediate chamber is in communication with the back pressure chamber inside the housing housing the rotor of the electric motor.

[0111] (Sixth aspect)

[0112] The electric valve according to any one of the first to fifth aspects is characterized in that,

[0113] The second valve core has a spherical surface that shields the through hole.

[0114] Symbol Explanation

[0115] 1 Electric valve

[0116] 10 Valve Body

[0117] 11 Valve seat components

[0118] 11e valve seat

[0119] 15 guide rods

[0120] 21 valve shaft

[0121] 23 Valve Cage

[0122] 24 First valve core

[0123] 25 Second valve core

[0124] 26 coil spring

[0125] 27 Thrust Bearing

[0126] 28 Washer

[0127] 29 Sealing Retainer

[0128] 30 rotors

[0129] 35. Movable stop for valve closing direction

[0130] 36. Movable stop for valve opening direction

[0131] 50 stator

[0132] 53 stator coil

[0133] 55. Fixed stop for valve closing direction

[0134] 56. Fixed stop for valve opening direction

[0135] BC back pressure chamber

[0136] MC Intermediate Room

[0137] VC valve chamber

[0138] OR O-ring

[0139] SD sliding component.

Claims

1. An electric valve, characterized in that, have: The valve body has a valve seat, a valve chamber, and a throttling orifice passage. The valve shaft is driven by an electric motor to rotate and displace along its axial direction; A valve retainer that is held to the valve shaft; A first valve core, which is fixed to the valve holder and has a through hole; A second valve core is disposed between the valve shaft and the first valve core; An elastomer that applies a force to the first valve core in a direction that moves the second valve core away from the first valve core; as well as A sealing retainer having a retainer base disposed within the valve body. The outer periphery of the cage base is sealed to the inner periphery of the valve body. An annular seal is disposed between the inner circumference of the base of the retainer and the outer circumference of the valve retainer. With the first valve core seated in the valve chamber, the throttling orifice passage and the internal space of the valve body can be connected via the through hole. When the second valve core abuts against the first valve core, the through hole is closed.

2. The electric valve according to claim 1, characterized in that, When the valve axis is displaced towards the valve seat, after the first valve core is seated on the valve seat, the second valve core closes the through hole of the first valve core. When the valve axis is displaced in the direction opposite to the valve seat side, the first valve core leaves the valve seat after the second valve core leaves the first valve core.

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

4. The electric valve according to claim 1, characterized in that, With the first valve core seated on the valve seat, the throttling orifice passage can communicate with the intermediate chamber inside the valve holder via the through hole, and the annular seal seals the valve chamber and the intermediate chamber.

5. The electric valve according to claim 4, characterized in that, The intermediate chamber is connected to the back pressure chamber inside the housing containing the rotor of the electric motor.

6. The electric valve according to claim 1, characterized in that, The second valve core has a spherical surface that shields the through hole.

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