Motorized valve

Abstract

This invention provides an electric valve that ensures the valve core is seated when the valve is closed without using a spring with a large force. The electric valve includes: a valve body having a valve chamber, a valve port, and a valve seat; a valve shaft inserted into the valve chamber; a valve core connected to the valve shaft; and a valve shaft drive unit that drives the valve shaft to bring the valve core closer to or further away from the valve seat. The valve body has an inner wall forming a back pressure chamber on the side opposite to the valve port and separated from the valve core. A sealing member is disposed between the valve shaft and the inner wall. The electric valve includes a force generating unit that generates an axial force transmitted from the sealing member to the valve core when the valve core is seated on the valve seat.

Description

Technical Field

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

[0002] Electric valves have long been used as devices for opening and closing fluid paths and controlling flow rates in piping systems, such as those for fluid distribution. In such electric valves, the valve core is driven by a drive source such as a stepper motor mounted on the valve body in order to achieve accurate flow control.

[0003] Patent document 1 discloses an electric valve that uses a stepper motor to drive the valve core to contact / separate relative to the valve seat.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2019-065898

[0007] In the electric valve of Patent Document 1, the valve core is inserted into a guide member while a sealing member is clamped between the valve core and the guide member. The guide member divides the valve core into a back pressure chamber and a valve chamber, and the valve chamber has a valve port with the valve seat. By keeping the back pressure chamber and the valve port in constant communication, the pressure on the upper and lower parts of the valve core is equalized, and the force acting on the valve core in the closing direction is balanced with the force acting on the valve core in the opening direction, thus ensuring accurate and efficient actuation of the valve core.

[0008] On the other hand, when the valve is closed, it is necessary to maintain the contact between the valve core and the valve seat. Therefore, a spring is provided that applies a force to the valve core in the direction towards the valve seat. Here, if the force of the spring is increased, it can be ensured that the valve core sits when the valve is closed, but countermeasures need to be implemented to prevent wear on the part that is subjected to force on one side and slides on the other. Summary of the Invention

[0009] The purpose of this invention is to provide an electric valve that can ensure the valve core is seated when the valve is closed without using a spring with a large force.

[0010] The electric valve of the present invention is characterized by having: a valve body having a valve chamber, a valve port, and a valve seat; a valve shaft inserted into the valve chamber; a valve core connected to the valve shaft; and a valve core drive unit that drives the valve shaft to bring the valve core closer to or separate it from the valve seat. The valve body has an inner wall forming a back pressure chamber on the side opposite to the valve port and separated from the valve core. A sealing member is disposed between the valve shaft and the inner wall. The electric valve has a force generating unit that generates an axial force transmitted from the sealing member to the valve core when the valve core is seated on the valve seat.

[0011] According to the electric valve of the present invention, an electric valve can be provided that ensures the valve core is seated when the valve is closed without using a spring with a large force. Attached Figure Description

[0012] Figure 1 This is a longitudinal sectional view showing the electric valve of the first embodiment.

[0013] Figure 2 This is a cross-sectional view showing an enlarged portion of the electric valve of the first embodiment.

[0014] Figure 3 This is a cross-sectional view showing an enlarged portion of the electric valve involved in a variation of the first embodiment.

[0015] Figure 4 This is a longitudinal sectional view showing the electric valve of the second embodiment.

[0016] Figure 5 This is a cross-sectional view showing an enlarged portion of the electric valve in the second embodiment.

[0017] Figure 6 This is a cross-sectional view showing an enlarged portion of the electric valve involved in a variation of the second embodiment.

[0018] Symbol Explanation

[0019] 10, 10B electric valve

[0020] 20, 20B valve body

[0021] 24, 24B valve shaft

[0022] 25 Fixed thread section (male thread section)

[0023] 26 guide bushing

[0024] 27 Lower stop body

[0025] 30 rotors

[0026] 31. Moving thread section (female thread section)

[0027] 32 Valve Shaft Cage

[0028] 33 Push Nut

[0029] 34 Compression Coil Spring

[0030] 35 return spring

[0031] 36 support rings

[0032] 37 Upper stop body

[0033] 40 housing

[0034] 41 Ring plate

[0035] 50 stator

[0036] 60 Valve seat component

[0037] 70 valve core

[0038] BC back pressure chamber

[0039] VC valve chamber Detailed Implementation

[0040] Hereinafter, embodiments of the electric valve according to the present invention will be described with reference to the accompanying drawings. Furthermore, in this specification, the direction from the rotor toward the valve seat is defined as downward, and the opposite direction is defined as upward.

[0041] [First Implementation Method]

[0042] Figure 1 This is a longitudinal sectional view showing the electric valve 10 according to the first embodiment. The electric valve 10, which controls the flow rate of refrigerant (fluid) in a refrigeration cycle such as that of an automobile, includes: a valve shaft 24; a valve core 70 connected to the valve shaft 24; a valve seat member 60 capable of contacting and separating from the valve core 70; a valve body 20 on which the valve seat member 60 is mounted; a housing 40 mounted on the valve body 20 and housing a rotor 30 that drives the valve shaft 24; and a stator 50 externally embedded in the housing 40 and driving the rotor 30 to rotate. The axis of the electric valve 10 is defined as L.

[0043] A pair of winding frames 52 and stator coils 53, along with a magnetic yoke 51 surrounding them, are respectively arranged on the outer periphery of the cylindrical portion of the housing 40. A resin molding cover 56 covers the outer periphery of the magnetic yoke 51, thereby forming the stator 50. In this embodiment, the resin molding cover 56 includes the upper part of the housing 40, but it may also only cover the area around the magnetic yoke 51. A stepper motor is constructed using the rotor 30 and the stator 50.

[0044] The stator coil 53 is connected to an external power supply circuit (not shown) via the substrate CB and connector CN.

[0045] The housing 40 is made of a non-magnetic metal such as stainless steel and is in the shape of a bottomed cylinder. The open lower end of the housing 40 is pressed into the upper end of the valve body 20 and fixed by welding, as described later.

[0046] The generally cylindrical valve shaft 24 is made of stainless steel or brass, and is formed by coaxially connecting a first shaft portion 24a on the upper side, a second shaft portion 24b with a diameter larger than that of the first shaft portion 24a, a circular flange portion 24c formed at the lower end of the second shaft portion 24b, a third shaft portion 24d connected to the lower surface of the flange portion 24c, and a fourth shaft portion 24e with a diameter smaller than that of the third shaft portion 24d.

[0047] The valve core 70 is formed by coaxially connecting the cylindrical portion 71, the flange portion 72, and the valve portion 73. A circular opening 74, resembling a pouch, is formed from the center of the upper end of the cylindrical portion 71 downwards. With an O-ring OR, a sealing member for preventing refrigerant leakage, embedded in the outer periphery of the third shaft portion 24d, the fourth shaft portion 24e of the valve shaft 24 is pressed into the circular opening 74. Furthermore, a communication hole 75 is formed connecting the lower end of the circular opening 74 to the outer periphery of the cylindrical portion 71. The communication hole 75, by communicating between the interior of the circular opening 74 and the exterior of the cylindrical portion 71, has the effect of suppressing abnormal noise. The valve portion 73, with a tapered lower end, has a seat surface 73a for the valve core 70, described later, to sit on.

[0048] A generally cylindrical valve shaft retainer 32 is configured within the housing 40 to accommodate the upper end of the valve shaft 24. The upper end of the valve shaft retainer 32 is engaged by a push nut 33 that is pressed into and fixes the upper end of the first shaft portion 24a of the valve shaft 24.

[0049] A return spring 35, consisting of a compression helical spring, is installed along the outer periphery of the push nut 33. The return spring 35 functions to apply force by abutting against the top inner surface of the housing 40 when the fixed thread 25 of the guide bushing 26 (described later in detail) disengages from the moving thread 31 of the valve shaft holder 32, thereby restoring the engagement between the fixed thread 25 and the moving thread 31.

[0050] The rotor 30, which is disposed with an open gap relative to the housing 40, is joined to the valve shaft retainer 32 via a support ring 36. More specifically, the support ring 36 is made of a brass metal ring that is embedded during the forming of the rotor 30. The upper protrusion of the valve shaft retainer 32 is fitted into the inner circumferential hole of the support ring 36, and the outer circumference of the upper protrusion is riveted to fix it, thereby joining the rotor 30, the support ring 36, and the valve shaft retainer 32.

[0051] An upper stop body 37, constituting one of the stopping mechanisms, is fixed to the outer periphery of the valve shaft retainer 32. The upper stop body 37 is made of annular resin and has a plate-shaped upper stop piece 37a protruding downwards.

[0052] A cylindrical guide bushing 26 is disposed between the valve shaft retainer 32 and the valve shaft 24. The lower end of the guide bushing 26 is pressed into the inner periphery of the retainer 220, which will be described in detail later. A lower stop body 27, constituting the other part of the stopping mechanism, is fixed to the outer periphery of the guide bushing 26. The lower stop body 27 is made of annular resin and has a plate-shaped lower stop piece 27a protruding from its upper part, which can engage with the aforementioned upper stop piece 37a.

[0053] The lower stop 27 is fixed to the spiral groove portion 26a formed on the outer periphery of the guide bushing 26 by injection molding, and the upper stop 37 is fixed to the spiral groove portion 32b formed on the outer periphery of the valve shaft retainer 32 by injection molding.

[0054] A movable threaded portion 31 is formed on the inner surface of the valve shaft retainer 32, which engages with a fixed threaded portion 25 formed on the outer periphery of the guide bushing 26.

[0055] The valve core drive unit of this embodiment includes a rotor 30, a valve shaft retainer 32 (moving threaded portion 31), a guide bushing 26 (fixed threaded portion 25), and a compression coil spring 34.

[0056] The valve shaft 24 is inserted in such a way that it can move up and down along the axis L of the valve shaft holder 32, and the compression coil spring 34, which is compressed and installed in the valve shaft holder 32, applies downward force.

[0057] The valve body 20 includes: a cylindrical body 210 formed of a straight tube of metal (e.g., stainless steel) with uniform wall thickness and outer diameter; a stainless steel retainer 220 pressed into the inner circumference of the upper end side of the cylindrical body 210; and a valve seat component 60. The retainer 220 is formed by connecting an annular portion 221 and a circular tube portion 222 with a diameter smaller than that of the annular portion 221 and extending downward from the annular portion 221.

[0058] The lower end of the housing 40 is pressed into the upper outer periphery of the annular portion 221 and fixed by welding. Near the lower outer periphery of the annular portion 221, the upper end of the cylindrical body 210 is coaxially connected by welding.

[0059] In the annular portion 221, a first through hole 223 extending parallel to the axis L is formed on the outer side of the joint with the circular tube portion 222. In addition, in the circular tube portion 222, a second through hole 224 extending radially is formed near the joint with the annular portion 221.

[0060] In this embodiment, the circular tube portion 222 forms the inner wall. In addition, the interior of the circular tube portion 222 and the upper part of the flange portion 24c of the valve shaft 24 form the back pressure chamber BC.

[0061] The guide bushing 26 is pressed into the inner circumference of the annular portion 221, configured such that its lower end abuts against the partition wall 225 formed on the lower end side of the annular portion 221. A circular hole 226 is formed in the center of the partition wall 225, and a valve shaft 24 is inserted through the circular hole 226.

[0062] The valve seat component 60 is formed by connecting an enlarged diameter portion 61 and a hollow cylindrical portion 62 extending upward from the enlarged diameter portion 61. A cylindrical body 210 is press-fitted or clearance-fitted into the outer circumference of the enlarged diameter portion 61 and brazed together. A gap is formed between the cylindrical body 210 and the hollow cylindrical portion 62. In addition, the outer circumference of the circular tube portion 222 is pressed into the inner circumference of the hollow cylindrical portion 62 to ensure sealing and to position the retainer 220 and the valve seat component 60 in a direction orthogonal to the axis L.

[0063] A valve chamber VC is formed inside the hollow cylindrical portion 62, and a valve core 70 is inserted into the valve chamber VC. A central opening (valve port) 63 is formed in the enlarged diameter portion 61 to communicate with the valve chamber VC, and an annular valve seat 64 is formed at the intersection of the central opening 63 and the inner circumference of the hollow cylindrical portion 62. In addition, a straight groove 65 is formed on the outer circumference of the enlarged diameter portion 61, extending along the axis L and opening at the upper end of the hollow cylindrical portion 62. Furthermore, a bypass hole 66 communicating between the central opening 63 and the straight groove 65 is formed in the enlarged diameter portion 61.

[0064] In the valve seat component 60, the central opening 63 is connected to the lower end side opening 67, which has a larger diameter than the central opening 63. The discharge side circular pipe T2 is inserted into the lower end side opening 67 and fixed to the valve seat component 60 by brazing.

[0065] A circular hole 211 is formed on the outer periphery of the cylindrical body 210. A supply-side circular tube T1 is inserted through the circular hole 211 and fixed by brazing. The axis of the supply-side circular tube T1 is set to O. Furthermore, the supply-side circular tube T1 is inserted through a transverse hole 68 in the valve seat component 60, which communicates with the valve chamber VC, and is fixed in a state of contact with the inner end of the transverse hole 68.

[0066] Figure 2 This is a cross-sectional view showing an enlarged portion of the electric valve of the first embodiment, indicating the valve in the closed state. Figure 2 In the middle, the third shaft portion 24d, in which the O-ring OR is embedded, has a tapered shape that expands in diameter as it faces downward. More specifically, in Figure 2 In the cross-section, the outer peripheral conical surface of the third shaft portion 24d is inclined at an angle θ1 relative to the axis L. The third shaft portion 24d constitutes the force generating part.

[0067] In addition, a thin-walled sleeve SL made of PTFE (polytetrafluoroethylene) or similar material is disposed between the O-ring OR and the inner circumference of the circular tube portion 222 of the cage 220. The sleeve SL has the function of reducing the friction between the O-ring OR and the circular tube portion 222.

[0068] An outer conical surface 222a is formed on the outer periphery of the lower end of the circular tube portion 222 of the retainer 220, and an inner conical surface 222b is formed on the inner periphery of the lower end of the circular tube portion 222.

[0069] (Action of the electric valve)

[0070] The operation of the electric valve 10 according to this embodiment will be explained. Figure 1 When the stator coil 53 of the stator 50 is energized by power supply from the outside via connector CN and substrate CB, the generated magnetic force produces a rotational force in the rotor 30, thus driving the rotor 30 and valve shaft retainer 32 to rotate relative to the guide bushing 26 fixed to the valve body 20.

[0071] Thus, the valve shaft retainer 32 is displaced in the direction of its axis L by the threaded feed mechanism of the fixed threaded portion 25 of the guide bushing 26 and the moving threaded portion 31 of the valve shaft retainer 32. When the valve shaft retainer 32 is displaced downward by energizing the stator coil 53, the valve shaft 24 and the valve core 70 are displaced downward. As a result, the seat surface 73a of the valve core 70 sits on the valve seat 64 of the valve seat component 60.

[0072] With seat 73a seated on valve seat 64, the refrigerant supplied from supply-side circular pipe T1 to valve chamber VC cannot flow out through central opening 63 to discharge-side circular pipe T2.

[0073] At this time, the central opening 63 connects to the back pressure chamber BC via the bypass hole 66, the straight groove 65, and the space of the cylindrical body 210, and then via multiple second through holes 224. Furthermore, since the cross-sectional area of ​​the back pressure chamber BC, which is orthogonal to the axis L, is approximately equal to the cross-sectional area of ​​the central opening 63, the downward thrust (force acting in the valve-closing direction) and the upward thrust (force acting in the valve-opening direction) acting on the valve core 70 are balanced (differential pressure is eliminated).

[0074] Furthermore, the back pressure chamber BC is connected to the interior of the chamber 40 via the first through hole 223. Therefore, suppressing the pressure change inside the chamber 40 that accompanies the vertical movement of the valve shaft 24 will not hinder the operation of the valve shaft 24.

[0075] Furthermore, in the closed state with the seat 73a resting on the valve seat 64, the upper stop 37 is not yet in contact with the lower stop 27, and the rotor 30 and valve shaft retainer 32 rotate and descend further together with the valve shaft 24 and valve core 70. At this time, the relative downward displacement of the valve shaft retainer 32 relative to the valve shaft 24 is absorbed by compressing the compression coil spring 34.

[0076] Then, the rotor 30 rotates further and the valve shaft retainer 32 descends, with the upper stop plate 37a of the upper stop body 37 abutting against the lower stop plate 27a of the lower stop body 27. Through the contact between these stop plates 27a and 37a, the descent of the valve shaft retainer 32 is forcibly stopped even if energization to the stator 50 continues.

[0077] The stop mechanism, consisting of the upper stop body 37 and the lower stop body 27, is arranged along the entire axial length of the rotor 30. Therefore, even when the stop mechanism is functioning, there is less chance of the rotor 30 and the valve shaft holder 32 tilting significantly, resulting in stable operation. This also allows for smooth reversal of the rotor 30.

[0078] Next, when the stator 50 is energized in the reverse direction, the rotor 30 and the valve shaft retainer 32 rotate relative to the guide bushing 26 in the opposite direction. Through the aforementioned threaded feed mechanism, the valve shaft retainer 32 is displaced upward. As a result, the seat surface 73a of the valve core 70 leaves the valve seat 64 of the valve seat component 60, and a large amount of refrigerant flows out from the valve chamber VC through the central opening 63 to the discharge side circular pipe T2.

[0079] Here, if the power supply to the stator 50 is cut off when the valve is closed, the valve core 70 is forced against the valve seat assembly 60 due to the pressure difference between the valve chamber VC and the central opening 63, maintaining the seat surface 73a in place on the valve seat 64. However, if the pressure difference decreases due to operating conditions of the refrigeration cycle, the force holding the valve seat surface 73a tightly against the valve seat 64 weakens, potentially leading to refrigerant leakage. Therefore, a compression coil spring 34 is provided to ensure that the valve core 70 is always forced against the valve seat assembly 60 via the valve shaft 24.

[0080] If the force of the compression coil spring 34 is increased, the force that keeps the seat surface 73a and the valve seat 64 in close contact will be increased. However, due to the increased force transmitted to each part, competition may occur, which may lead to wear. Therefore, the valve is configured so that valve leakage will not occur even if the force of the compression coil spring 34 is not increased.

[0081] That is, in this embodiment, the following effect occurs. Figure 2In this process, when the refrigerant pressure in the valve chamber VC and the back pressure chamber BC is applied to the O-ring OR, the O-ring OR is compressed in the vertical direction, and expands in a direction orthogonal to the axis L. Its inner circumference presses against the third shaft portion 24d (refer to arrow A1), and its outer circumference presses against the inner circumference of the circular tube portion 222 via the sleeve SL (refer to arrow A2). Here, since the third shaft portion 24d has a conical surface, the pressing force shown by arrow A1 has a downward component along the axis L. This axial component of the pressing force can be used to apply force to the valve shaft 24 and the valve core 70 toward the valve seat component 60, thus allowing the use of a compression coil spring 34 with reduced force.

[0082] [Variation Example]

[0083] Figure 3 It is represented by an enlarged portion of the electric valve involved in the modified example of the first embodiment, and... Figure 2 The same sectional view. In Figure 3 In this embodiment, the circular tube portion 222A forming the inner wall has a narrowed inner circumferential surface 222c formed near its lower end and an expanded inner circumferential surface 222d disposed above the narrowed inner circumferential surface 222c, with a diameter larger than that of the narrowed inner circumferential surface 222c. The cylindrical narrowed inner circumferential surface 222c and the expanded inner circumferential surface 222d are connected by a tapered inner circumferential surface 222e. All other structures identical to those in the first embodiment are labeled with the same reference numerals, and repeated descriptions are omitted.

[0084] According to this modified example, when the valve is closed, the O-ring OR and the sleeve SL are located radially inside the reduced-diameter inner circumferential surface 222c, thus performing the same function as in the embodiment described above. On the other hand, when the valve is opened, the valve shaft 24 and the valve core 70 move upward relative to the circular tube portion 222A. Therefore, as shown by the dashed line, the O-ring OR and the sleeve SL move towards the expanded-diameter inner circumferential surface 222d, which has a larger diameter than the reduced-diameter inner circumferential surface 222c. As a result, the compression amount (the compressed size) of the O-ring OR is reduced, thus suppressing the collapse of the O-ring OR and suppressing wear by reducing sliding resistance.

[0085] [Second Implementation]

[0086] Figure 4 This is a longitudinal sectional view showing the electric valve 10B according to the second embodiment. Figure 5 This is an enlarged cross-sectional view of a portion of the electric valve 10B of the second embodiment, showing the state when the valve is closed. In this embodiment, the shapes of the valve shaft and the cage are different from those of the first embodiment. Other structures that are the same as those in the first embodiment are labeled with the same symbols and repeated descriptions are omitted.

[0087] like Figure 5As shown, the third shaft portion 24Bd of the valve shaft 24B, in which the O-ring OR is embedded, is cylindrical. However, the inner conical surface 222B of the circular tube portion 222B constituting the valve body 20B expands upward and contacts the sleeve SL when the valve is closed. The outer circumferential surface of the inner conical surface 222Bb... Figure 2 The cross-section is inclined at an angle θ2 relative to the axis L. The inner conical surface 222Bb constitutes the force-generating part.

[0088] According to this embodiment, in Figure 5 In this process, when the refrigerant pressure in the valve chamber VC and the back pressure chamber BC is applied to the O-ring OR, the O-ring OR is compressed in the vertical direction, and expands in the direction orthogonal to the axis L. Its inner circumference presses against the third shaft portion 24Bd (refer to arrow A3), and its outer circumference presses against the inner conical surface 222Bb of the circular tube portion 222B (refer to arrow A4) via the sleeve SL. Here, by pressing the inner conical surface 222Bb, its reaction force is applied to the O-ring OR as shown by arrow A5, but the reaction force shown by arrow A5 has a component in the downward direction along the axis L. This axial component of the pressing force can be used to apply force to the valve shaft 24 and the valve core 70 toward the valve seat component 60, so a compression coil spring 34 with reduced force can be used. Furthermore, when the retainer 220B is formed of thermoplastic resin, the inner conical surface 222Bb of the circular tube portion 222B can be used as a demolding draft angle during demolding.

[0089] [Variation Example]

[0090] Figure 6 It is represented by an enlarged portion of the electric valve involved in the modified example of the second embodiment, and... Figure 5 The same sectional view. In Figure 6 In this embodiment, the circular tube portion 222C forming the inner wall has an inner conical surface 222Cb and an expanded inner circumferential surface 222Cd. The inner conical surface 222Cb is formed near the lower end and has a conical shape. The expanded inner circumferential surface 222Cd is positioned above the inner conical surface 222Cb and has a larger diameter than the inner circumference of the upper end of the inner conical surface 222Cb. The inner conical surface 222Cb and the expanded inner circumferential surface 222Cd are connected by a conical inner circumferential surface 222Ce. The sleeve SL, like in the above embodiment, is cylindrical in its free state, but becomes conical in shape by assembly, mimicking the inner conical surface 222Cb. All other structures identical to those in the second embodiment are labeled with the same reference numerals, and repeated descriptions are omitted.

[0091] According to this modified example, when the valve is closed, the O-ring OR and the sleeve SL are located radially inside the inner conical surface 222Cb, thus performing the same function as in the embodiment described above. On the other hand, when the valve is opened, the valve shaft 24 and the valve core 70 move upward relative to the circular tube portion 222C. Therefore, as shown by the dashed line, the O-ring OR and the sleeve SL move towards the expanded inner circumferential surface 222Cd, whose diameter is larger than the diameter of the upper inner circumference of the inner conical surface 222Cb. As a result, the compression of the O-ring OR is reduced, thus suppressing the collapse of the O-ring OR and suppressing wear by reducing sliding resistance.

[0092] Furthermore, the present invention is not limited to the embodiments described above. Within the scope of the present invention, any modifications to the constituent elements of the above embodiments are possible. Additionally, any constituent elements may be added or omitted in the above embodiments.

Claims

1. An electric valve, characterized in that... ,have: The valve body includes a valve chamber, a valve port, and a valve seat. A valve shaft, which is inserted into the valve chamber; Valve core, which is connected to the valve shaft; and The valve core drive unit drives the valve shaft to bring the valve core closer to or further away from the valve seat. The valve body has an inner wall forming a back pressure chamber on the side opposite to the valve port and separated from the valve core. A sealing member is disposed between the valve shaft and the inner wall. The electric valve includes a force-generating section. When the valve core is seated on the valve seat, the sealing member expands towards the force-generating section due to the pressure of the fluid in the valve chamber and the back pressure chamber. This force-generating section then generates an axial force transmitted from the sealing member to the valve core. The force-generating part is the valve shaft having a conical surface. The inner wall has a cylindrical inner circumferential surface with a reduced diameter, a cylindrical inner circumferential surface with an expanded diameter, and a conical inner circumferential surface. When the valve is closed, the sealing component is located radially inside the inner circumferential surface with a reduced diameter. When the valve is open, the sealing component is located radially inside the inner circumferential surface with an expanded diameter. The conical inner circumferential surface connects the inner circumferential surface with a reduced diameter and the inner circumferential surface with an expanded diameter.

2. An electric valve, characterized in that... ,have: The valve body includes a valve chamber, a valve port, and a valve seat. A valve shaft, which is inserted into the valve chamber; Valve core, which is connected to the valve shaft; and The valve core drive unit drives the valve shaft to bring the valve core closer to or further away from the valve seat. The valve body has an inner wall forming a back pressure chamber on the side opposite to the valve port and separated from the valve core. A sealing member is disposed between the valve shaft and the inner wall. The electric valve includes a force-generating section. When the valve core is seated on the valve seat, the sealing member expands towards the force-generating section due to the pressure of the fluid in the valve chamber and the back pressure chamber. This force-generating section then generates an axial force transmitted from the sealing member to the valve core. The force-generating part has an inner wall with a conical surface. The inner wall has an inner conical surface, a cylindrical expanded inner circumferential surface, and a conical inner circumferential surface. When the valve is closed, the sealing component is located radially inside the inner conical surface. When the valve is open, the sealing component is located radially inside the expanded inner circumferential surface. The conical inner circumferential surface connects the inner conical surface and the expanded inner circumferential surface and is inclined to the side opposite to the inner conical surface.

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