Electric-operated valve

Abstract

[Problem] To provide an electric-operated valve capable of suppressing abnormality generated when the environmental temperature changes. [Solution] When the lower end of a valve seat 14 is designated as a reference position P0, the upper end of a threaded portion of a female screw 68t of a guide member 68 is designated as a first position P1, the upper end of a threaded portion of a male screw 72t of a drive shaft 70 is designated as a second position P2, the vertical length from the reference position P0 to the first position P1 in a body member 11, a holder 20, and the guide member 68 is designated as a valve-body-side length L1, and the vertical length from the reference position P0 to the second position P2 in the valve seat 14, a valve body 40, and the drive shaft 70 is designated as a valve-body-side length L2, the amount of change in the valve-body-side length L2 due to a temperature change is greater than the amount of change in the valve-body-side length L1 when the electric-operated valve is in a closed state.

Description

Electric valve

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

[0002] Patent Document 1 discloses an example of a conventional electric valve. The electric valve of Patent Document 1 has a valve body, a guide member, a drive shaft, and a valve element. The valve body has a body member and a holder attached to the body member. A cylindrical valve seat is attached to the body member. The guide member has a female thread and is attached to the holder. The drive shaft has a male thread that is screwed into the female thread. When the drive shaft rotates around the central axis, the drive shaft moves in the vertical direction (axial direction). The valve element is disposed between the valve seat and the drive shaft. The drive shaft is in contact with the valve element, and when the drive shaft rotates in one direction, it pushes the valve element toward the valve seat. Depending on the characteristics required for each member, the body member is made of an aluminum alloy, the guide member is made of brass, and the valve seat, holder, drive shaft, and valve element are made of stainless steel.

[0003] Japanese Patent Application Laid-Open No. 2022-190566

[0004] The temperature of the members constituting the electric valve changes according to the ambient temperature, and the members expand and contract due to the change in their temperature. The lower end of the valve seat is taken as the reference position. The upper end of the screwed portion of the female thread of the guide member is taken as the first position. The upper end of the screwed portion of the male thread of the drive shaft is taken as the second position. The vertical length from the reference position to the first position is defined as the valve body side length L1. The vertical length from the reference position to the second position is defined as the valve element side length L2. The valve body side length L1 becomes longer according to the expansion of the body member, holder, and guide member, and becomes shorter according to the contraction. The valve element side length L2 becomes longer according to the expansion of the valve seat, valve element, and drive shaft, and becomes shorter according to the contraction.

[0005] The linear expansion coefficients of aluminum alloy and brass are relatively large, and the linear expansion coefficient of stainless steel is relatively small. Therefore, when the ambient temperature drops with the valve element in contact with the valve seat, the valve body side length L1 becomes shorter than the valve element side length L2, and the guide member moves the drive shaft in the direction toward the valve seat. As a result, the valve element is strongly pressed against the valve seat, and there is a risk that the valve element will not move. Thus, there is a risk that an abnormality will occur in the electric valve when the ambient temperature changes.

[0006] Therefore, the present invention aims to provide an electric valve that can suppress abnormalities that occur when the ambient temperature changes.

[0007] To achieve the above objective, an electric valve according to one aspect of the present invention comprises a valve body, a guide member having a female thread and attached to the valve body, a drive shaft having a male thread that is screwed into the female thread, and a valve element that is in contact with or connected to the drive shaft, wherein the valve body is provided with a valve seat, the valve seat, the valve element and the drive shaft are aligned in the axial direction of the drive shaft, and when the drive shaft rotates in one direction, the valve element moves toward the valve seat and comes into contact with the valve seat, with the valve seat as the reference position, and the screw portion of the female thread The first position is defined as the end of the male screw furthest from the valve seat, the second position is defined as the screw portion of the male screw furthest from the valve seat, the axial length of the valve body and the guide member from the reference position to the first position is defined as the valve body side length, and the axial length of the valve seat, the valve element and the drive shaft from the reference position to the second position is defined as the valve element side length, wherein in the closed valve state where the valve element is in contact with the valve seat, the amount of change in the valve element side length due to temperature change is greater than the amount of change in the valve body side length.

[0008] In the present invention, it is preferable that a cylindrical valve seat is attached to the valve body, the valve element is in contact with the first end of the valve seat, and the reference position is the second end of the valve seat.

[0009] In the present invention, it is preferable that the reference position is the location on the valve seat where the valve body makes contact.

[0010] To achieve the above objective, an electric valve according to another aspect of the present invention comprises a valve body, a guide member having a female thread and attached to the valve body, a drive shaft having a male thread that is screwed into the female thread, and a valve element that is in contact with or connected to the drive shaft, wherein the valve body is provided with a valve seat, the valve seat, the valve element and the drive shaft are aligned in the axial direction of the drive shaft, the valve element has a columnar body and a head connected to the first end of the body, when the drive shaft rotates in one direction, the valve element moves toward the valve seat, the second end of the body contacts the valve seat, and the coefficient of thermal expansion of the valve body is greater than the coefficient of thermal expansion of the body, and the coefficient of thermal expansion of the head is greater than the coefficient of thermal expansion of the body.

[0011] In the present invention, it is preferable that the coefficient of linear expansion of the head is greater than the coefficient of linear expansion of the valve body.

[0012] In the present invention, it is preferable that the coefficient of linear expansion of the drive shaft is greater than the coefficient of linear expansion of the body.

[0013] In the present invention, it is preferable that the valve body comprises a main body member on which the valve seat is arranged and a holder attached to the main body member, the guide member is attached to the holder, the coefficient of thermal expansion of the main body member is greater than the coefficient of thermal expansion of the body, the coefficient of thermal expansion of the holder is the same as the coefficient of thermal expansion of the body, and the coefficient of thermal expansion of the head is greater than or equal to the coefficient of thermal expansion of the main body member.

[0014] In the present invention, it is preferable that the valve body comprises a main body member on which the valve seat is arranged and a holder attached to the main body member, the guide member is attached to the holder, the valve seat has a cylindrical shape and is attached to the main body member, and the coefficient of linear expansion of the valve seat is greater than the coefficient of linear expansion of the body.

[0015] In the present invention, it is preferable that the valve body has a receiving member attached to the head and in contact with the drive shaft, and that the material of the receiving member is the same as the material of the drive shaft, or a material with higher wear resistance than the drive shaft.

[0016] In the present invention, it is preferable that the electric valve further comprises a valve body support member held by the valve body, the valve body support member having a support hole for movably supporting the body portion and a relief hole coaxially connected to the support hole, the diameter of the relief hole being larger than the diameter of the support hole, the body portion being positioned in the support hole when the valve body is in contact with the valve seat, and the connection point between the body portion and the head portion being positioned in the relief hole.

[0017] According to the present invention, if the valve seat is defined as the reference position, the end of the guide member furthest from the valve seat in the threaded portion of the female screw is defined as the first position, the end of the drive shaft furthest from the valve seat in the threaded portion of the male screw is defined as the second position, the axial length from the reference position to the first position in the valve body and guide member is defined as the valve body side length, and the axial length from the reference position to the second position in the valve seat, valve element, and drive shaft is defined as the valve element side length, then in the closed valve state where the valve element is in contact with the valve seat, the amount of change in the valve element side length due to temperature change is greater than the amount of change in the valve body side length. As a result, when the ambient temperature drops in the closed valve state where the valve element is in contact with the valve seat, the valve element side length becomes shorter than the valve body side length. This suppresses the valve element from being pressed too hard against the valve seat.

[0018] Furthermore, according to the present invention, the coefficient of linear expansion of the valve body is greater than that of the casing, and the coefficient of linear expansion of the head is greater than that of the casing. As a result, compared to a configuration in which the coefficient of linear expansion of the head is the same as that of the casing, when the ambient temperature drops in the closed state with the valve body in contact with the valve seat, the difference between the amount of contraction of the valve body and the amount of contraction of the valve body becomes smaller. This suppresses the valve body from being pressed too hard against the valve seat.

[0019] Therefore, electric valves can suppress malfunctions that occur when the ambient temperature changes.

[0020] This is a cross-sectional view of an electric valve according to one embodiment of the present invention. This is an enlarged cross-sectional view of the valve body, drive shaft and its vicinity of the electric valve. This is a cross-sectional view illustrating the length on the valve body side and the length on the valve body side. This is another cross-sectional view illustrating the length on the valve body side and the length on the valve body side. This is a plan view of a valve device according to another embodiment of the present invention.

[0021] Hereinafter, an electric valve according to one embodiment of the present invention will be described with reference to Figures 1 to 4. The electric valve according to this embodiment is used to control the refrigerant flow rate in a refrigeration cycle system.

[0022] The electric valve 1 according to this embodiment includes a valve body assembly 7 and a stator unit 8.

[0023] The valve body assembly 7 includes a valve body 10, a valve body support member 25, a can 30, a connecting member 35, a valve body 40, and a drive mechanism 50.

[0024] The valve body 10 comprises a main body member 11 and a holder 20.

[0025] The main body member 11 has a rectangular parallelepiped shape. The main body member 11 has a valve chamber 13. A valve seat 14 is attached to the main body member 11. The valve seat 14 has a cylindrical shape and is located inside the main body member 11. The valve seat 14 has a valve port 15 connected to the valve chamber 13.

[0026] The main body member 11 has a first passage 17 and a second passage 18. The first passage 17 extends from the right side surface 11a of the main body member 11 to the valve opening 15. The first passage 17 is connected to the valve chamber 13 via the valve opening 15. The second passage 18 extends from the left side surface 11b of the main body member 11 to the valve chamber 13.

[0027] The main body member 11 has a mounting hole 19. The mounting hole 19 is provided on the upper surface 11c of the main body member 11. The inner circumferential surface of the mounting hole 19 is provided with a female thread. The mounting hole 19 is connected to the valve chamber 13. A retaining surface 11d, which is an annular plane facing upward, is provided at the connection point between the mounting hole 19 and the valve chamber 13.

[0028] The holder 20 has a cylindrical shape. The outer surface of the holder 20 is provided with male threads. The male threads of the holder 20 are screwed into the female threads of the mounting holes 19 of the valve body 10. The holder 20 is attached to the valve body 10 by a screw structure.

[0029] The valve support member 25 has a cylindrical shape. The outer circumferential surface of the valve support member 25 is provided with a contact surface 25d, which is an annular plane facing downwards. The valve support member 25 is held by the valve body 10. Specifically, the lower part of the valve support member 25 is press-fitted into the valve chamber 13, and the contact surface 25d is in contact with the holding surface 11d of the valve body 10. The valve support member 25 separates the valve chamber 13 from the mounting hole 19. A holder 20 is positioned above the valve support member 25. The valve support member 25 supports the valve body 40 so that it can move vertically (in the direction of the axis M).

[0030] The valve support member 25 has a support hole 26 and a relief hole 27 connected coaxially with the support hole 26. The support hole 26 is closer to the valve seat 14 than the relief hole 27. The relief hole 27 is provided on the upper surface of the valve support member 25. The diameter of the relief hole 27 is larger than the diameter of the support hole 26. A spring receiving surface 25e, which is an annular plane facing upward, is provided at the connection point between the support hole 26 and the relief hole 27.

[0031] The can 30 has a cylindrical shape. The can 30 is closed at the top and open at the bottom. The connecting member 35 has an annular plate shape. The upper part 20a of the holder 20 is positioned inside the connecting member 35. The inner periphery of the connecting member 35 is joined to the upper part 20a of the holder 20. The lower end of the can 30 is joined to the outer periphery of the connecting member 35.

[0032] The valve body 40 has a body portion 41, a head portion 42, and a receiving member 43.

[0033] The body portion 41 has a stem 41a and a valve portion 41b. The stem 41a has a cylindrical shape. The diameter of the stem 41a is the same as (or substantially the same as) the diameter of the support hole 26 of the valve body support member 25. The stem 41a is positioned in the support hole 26 and is supported by the valve body support member 25 so as to be movable in the vertical direction. The lower end of the stem 41a (the second end of the body portion 41) faces the valve seat 14 in the vertical direction. The valve portion 41b has an annular shape. The outer diameter of the valve portion 41b is larger than the diameter of the stem 41a. The inner periphery of the valve portion 41b is integrally connected to the lower end of the stem 41a. When the valve body 40 moves downward, the valve portion 41b contacts the upper end of the valve seat 14.

[0034] The head portion 42 is connected to the upper end of the stem 41a (the first end of the body portion 41). The head portion 42 has a cylindrical portion 42a and a flange portion 42b. The diameter of the cylindrical portion 42a is the same as (including substantially the same as) the diameter of the stem 41a. The cylindrical portion 42a has a first hole 42a1 and a second hole 42a2. The first hole 42a1 is provided on the lower end surface of the cylindrical portion 42a. The upper end of the stem 41a is positioned in the first hole 42a1. A gap is provided between the bottom surface of the first hole 42a1 and the upper end surface of the portion of the stem 41a that is positioned in the first hole 42a1, and the lower end surface of the cylindrical portion 42a is in contact with the stem 41a. The cylindrical portion 42a is coaxially joined to the upper end of the stem 41a. The second hole 42a2 is provided on the upper end surface of the cylindrical portion 42a. The flange portion 42b has an annular shape. The outer diameter of the flange portion 42b is larger than the diameter of the cylindrical portion 42a. The inner periphery of the flange portion 42b is integrally connected to the upper end of the cylindrical portion 42a.

[0035] The receiving member 43 has a circular flat plate portion and a protrusion integrally connected to the lower surface of the flat plate portion. A conical recess is provided on the upper surface of the flat plate portion. The protrusion is fitted into the second hole 42a2 of the head portion 42. The receiving member 43 is attached to the head portion 42.

[0036] When the valve body 40 (valve portion 41b) touches the valve seat 14, the valve opening 15 closes, and the opening of the valve opening 15 becomes 0 (closed state). When the valve body 40 moves away from the valve seat 14, the valve opening 15 opens. When the valve body 40 is furthest away from the valve seat 14, the opening of the valve opening 15 becomes maximum (fully open state).

[0037] The drive mechanism 50 moves the valve body 40 in the vertical direction. The drive mechanism 50 includes a rotor 51, a connecting plate 52, a rotor shaft 53, a planetary gear mechanism 60, a guide member 68, a drive shaft 70, and a valve opening spring 77.

[0038] The rotor 51 has a cylindrical shape. The outer diameter of the rotor 51 is smaller than the inner diameter of the can 30. The rotor 51 is rotatably positioned inside the can 30. A circular connecting plate 52 is joined to the upper end of the rotor 51. The connecting plate 52 closes the upper end of the rotor 51. The rotor shaft 53 passes through the center of the connecting plate 52. The rotor 51 is connected to the rotor shaft 53 via the connecting plate 52. The connecting plate 52 and the rotor shaft 53 rotate together with the rotor 51.

[0039] The rotor 51 has multiple north poles and multiple south poles. The multiple north poles and multiple south poles are arranged alternately in the circumferential direction on the outer surface of the rotor 51. The multiple north poles and multiple south poles extend in the vertical direction.

[0040] The planetary gear mechanism 60 is a 3K type planetary gear mechanism. The planetary gear mechanism 60 may also be, for example, a 2K-H type planetary gear mechanism. The electric valve 1 may use a gear mechanism that functions as a reduction gear instead of the planetary gear mechanism 60. The planetary gear mechanism 60 is located inside the rotor 51. The planetary gear mechanism 60 has a gear case 61, a fixed ring gear 62, a sun gear 63, a plurality of planetary gears 64, a carrier 65, an output gear 66, and an output shaft 67. The planetary gear mechanism 60 has the same configuration (including substantially the same configuration) as the electric valve of Patent Document 1. The planetary gear mechanism 60 is a reduction gear that reduces the rotation of the rotor 51.

[0041] The sun gear 63 is integrally formed with the connecting plate 52 and is coaxially positioned on the lower surface of the connecting plate 52. The sun gear 63 rotates together with the rotor 51 and the connecting plate 52. The rotation of the sun gear 63 is reduced by the fixed ring gear 62, a plurality of planetary gears 64, a carrier 65, and an output gear 66, and transmitted to the output shaft 67. The output shaft 67 has a cylindrical shape. The upper part of the output shaft 67 is press-fitted into a hole provided in the output gear 66. The lower part of the output shaft 67 is provided with a slit 67a that extends in the vertical direction. The output shaft 67 rotates together with the output gear 66.

[0042] The guide member 68 has a cylindrical shape. The guide member 68 is disposed inside the upper portion 20a of the holder 20. The guide member 68 is fixed to the valve body 10. The guide member 68 has an internal thread 68t. The internal thread 68t is disposed at the lower part of the inner peripheral surface of the guide member 68. Inside the guide member 68, an output shaft 67 is disposed. The guide member 68 rotatably supports the output shaft 67.

[0043] The drive shaft 70 has a first portion 71, a second portion 72, and a ball 73. The drive shaft 70 is rotated around the central axis by the output shaft 67.

[0044] The first portion 71 has a rectangular flat plate shape. The thickness of the first portion 71 is the same as (including substantially the same) the width of the slit 67a of the output shaft 67. The first portion 71 is disposed inside the slit 67a of the output shaft 67 so as to be movable in the vertical direction. The slit 67a and the first portion 71 enable the vertical movement of the drive shaft 70 with respect to the output shaft 67 while transmitting the rotation of the output shaft 67 to the drive shaft 70.

[0045] The second portion 72 has a cylindrical shape. The second portion 72 is integrally connected to the lower end of the first portion 71. The first portion 71 and the second portion 72 are integrally formed, for example, by cutting a cylindrical metal bar. The second portion 72 has an external thread 72t. The external thread 72t is disposed on the outer peripheral surface of the second portion 72. The external thread 72t is screwed into the internal thread 68t of the guide member 68.

[0046] The ball 73 is joined to the lower end surface of the second portion 72. The ball 73 slidably contacts the concave portion of the flat plate portion of the receiving member 43. That is, the drive shaft 70 contacts the valve body 40. Note that the drive shaft 70 may be integrally connected to the head 42 of the valve body 40. Or, the drive shaft 70 may be connected to the head 42 of the valve body 40 so that the valve body 40 moves in the vertical direction together with the drive shaft 70.

[0047] The valve opening spring 77 is positioned between the spring receiving surface 25e of the valve body support member 25 and the flange portion 42b of the valve body 40. The valve opening spring 77 is a compression coil spring. The valve opening spring 77 pushes the valve body 40 upward (away from the valve seat 14).

[0048] The stator unit 8 includes a housing 81 and a stator 82.

[0049] The housing 81 is made of synthetic resin. The stator 82 has a cylindrical shape. The stator 82 is housed in the housing 81. A can 30 is positioned inside the stator 82, and the rotor 51 and the stator 82 face each other radially with the can 30 in between. The stator 82 and the rotor 51 constitute a stepping motor 88. Note that the electric valve 1 may have another type of motor instead of the stepping motor 88.

[0050] In the electric valve 1, the valve seat 14, holder 20, valve body support member 25 (support hole 26, relief hole 27), can 30, valve body 40 (body 41, head 42, receiving member 43), rotor 51, connecting plate 52, rotor shaft 53, output shaft 67, guide member 68, drive shaft 70, and stator 82 each have their central axes coincide with axis M. The direction of axis M is the axial direction. The valve seat 14, valve body 40, and drive shaft 70 are arranged in this order along axis M.

[0051] Next, the operation of the electric valve 1 will be explained.

[0052] In the electric valve 1, current is supplied to the stator 82 to rotate the rotor 51 in the first direction. The rotation of the rotor 51 is reduced by the planetary gear mechanism 60 and transmitted to the drive shaft 70. As the drive shaft 70 rotates in one direction, the drive shaft 70 moves downward due to the feed screw action between the male screw 72t of the drive shaft 70 and the female screw 68t of the guide member 68, approaching the valve seat 14. The valve body 40 is pushed downward by the drive shaft 70, and the valve body 40 moves downward. When the valve body 40 contacts the valve seat 14 and the valve opening 15 closes, the electric valve 1 enters a closed state.

[0053] In the electric valve 1, current is supplied to the stator 82 to rotate the rotor 51 in a second direction. The rotation of the rotor 51 is reduced by the planetary gear mechanism 60 and transmitted to the drive shaft 70. As the drive shaft 70 rotates in the other direction, the drive shaft 70 moves upward and away from the valve seat 14 due to the feed screw action between the male screw 72t of the drive shaft 70 and the female screw 68t of the guide member 68. The valve body 40 is pushed upward by the valve opening spring 77, causing the valve body 40 to move upward and the valve port 15 to open. When the valve body 40 is furthest away from the valve seat 14, the electric valve 1 is fully open.

[0054] Next, we will explain the materials of the components that make up the electric valve 1.

[0055] In this embodiment, the main body member 11 is made of aluminum alloy, and the guide member 68 is made of brass. The valve seat 14, holder 20, body 41, receiving member 43, and drive shaft 70 are made of stainless steel. The head 42 is made of zinc alloy. The head 42 may also be made of aluminum alloy.

[0056] The coefficient of linear thermal expansion of aluminum alloy (22 × 10⁻⁶) －６ The coefficient of linear expansion of brass (20 × 10°C) is given by the coefficient of linear expansion of brass (20 × 10°C). －６ The coefficient of thermal expansion of brass is greater than that of stainless steel (16 × 10). －６ It is greater than ( / °C). The coefficient of linear expansion of zinc alloy is (27 × 10). －６ The coefficient of thermal expansion (°C) is greater than that of aluminum alloys.

[0057] In this specification, the coefficient of linear expansion of a composite component including members of different materials (for example, a valve body 10 including a main body member 11 and a holder 20) is the rate at which the vertical length of the composite component changes in response to the temperature rise. The coefficient of linear expansion of the valve body 10 including an aluminum alloy member is greater than that of the stainless steel body 41.

[0058] The temperature of the components constituting the electric valve 1 changes according to the ambient temperature, and these components expand and contract due to the change in temperature. That is, the components constituting the electric valve 1 expand when the ambient temperature rises and contract when the ambient temperature falls. The lower end of the valve seat 14 is defined as the reference position P0. The upper end of the threaded portion of the female thread 68t of the guide member 68 (the end furthest from the valve seat 14) is defined as the first position P1. The upper end of the threaded portion of the male thread 72t of the drive shaft 70 (the end furthest from the valve seat 14) is defined as the second position P2. The vertical length from the reference position P0 to the first position P1 is defined as the valve body side length L1. The vertical length from the reference position P0 to the second position P2 is defined as the valve body side length L2. The valve body side length L1 increases according to the expansion of the main body component 11, the holder 20, and the guide member 68, and decreases according to their contraction. The valve body length L2 increases in accordance with the expansion of the valve seat 14, body 41, head 42, receiving member 43, and drive shaft 70, and decreases in accordance with the contraction.

[0059] In Figure 3, the lengths of the main body member 11, holder 20, and guide member 68 related to the valve body length L1 are indicated by symbols A, B, and C, and the lengths of the valve seat 14, body 41, head 42, receiving member 43, and drive shaft 70 related to the valve body length L2 are indicated by symbols V, W, X, Y, and Z. In this embodiment, each length is when the electric valve 1 is in the closed state and has the following relationships: (1) L1 = A + B + C (2) L2 = V + W + X + Y + Z (3) A > B > C (4) W > Z > X > V > Y (5) A > W (6) W + X > A

[0060] The electric valve 1 may also have a valve body assembly 7A having a valve seat 14A made of the same material (aluminum alloy) as the main body member 11. In the valve body assembly 7A, the valve seat 14A expands and contracts vertically in the same way as the main body member 11, so as shown in Figure 4, the upper end of the valve seat 14A, where the valve body 40 makes contact, is set as the reference position P0. The valve body side length L1 is related to the main body member 11, the holder 20 and the guide member 68, and the valve body side length L2 is related to the body 41, the head 42, the receiving member 43 and the drive shaft 70. The valve body assembly 7A may have a valve seat formed integrally with the main body member 11.

[0061] This embodiment compares the electric valve 1 with a conventional electric valve. The conventional electric valve has the same configuration as the electric valve 1, except that the head 42 is made of stainless steel. That is, the conventional electric valve has a valve body 40 made of a single material (stainless steel) with a low coefficient of linear expansion.

[0062] In conventional electric valves, the components related to the valve body length L1 include aluminum alloy and brass components, while the components related to the valve element length L2 include only stainless steel components. Therefore, when the ambient temperature rises, the valve body length L1 becomes longer than the valve element length L2, and when the ambient temperature falls, the valve body length L1 becomes shorter than the valve element length L2.

[0063] In the electric valve 1 according to this embodiment, the components related to the valve body length L1 include components made of aluminum alloy and brass, and the components related to the valve element length L2 include components made of zinc alloy. Therefore, when the ambient temperature rises, the valve body length L1 becomes longer than the valve element length L2, and when the ambient temperature falls, the valve body length L1 becomes shorter than the valve element length L2, but the difference between the valve body length L1 and the valve element length L2 is smaller than that of conventional electric valves. In addition, in the electric valve 1, when the ambient temperature falls, the valve element length L2 may become shorter than the valve body length L1.

[0064] When the ambient temperature rises while the valve body 40 is in contact with the valve seat 14, the length L1 on the valve body side becomes longer than the length L2 on the valve body side, causing the guide member 68 to move the drive shaft 70 away from the valve seat 14. However, in the electric valve 1, the difference between the length L1 on the valve body side and the length L2 on the valve body side is smaller than in conventional electric valves, which suppresses the valve body 40 from moving away from the valve seat 14.

[0065] When the ambient temperature drops while the valve body 40 is in contact with the valve seat 14, the length L1 on the valve body side becomes shorter than the length L2 on the valve body side, causing the guide member 68 to move the drive shaft 70 toward the valve seat 14. However, in the electric valve 1, the difference between the length L1 on the valve body side and the length L2 on the valve body side is smaller compared to conventional electric valves, which suppresses the valve body 40 from being pressed too hard against the valve seat 14.

[0066] As described above, the electric valve 1 comprises a valve body 10, a guide member 68 having an internal thread 68t and attached to the valve body 10, a drive shaft 70 having an internal thread 72t that is screwed into the internal thread 68t, and a valve body 40 that contacts the drive shaft 70. The valve body 40 has a cylindrical body portion 41 and a head portion 42 connected to the upper end of the body portion 41. When the drive shaft 70 rotates in one direction, the valve body 40 moves toward the valve seat 14, and the lower end of the body portion 41 contacts the valve seat 14. The coefficient of thermal expansion of the valve body 10 is greater than that of the body portion 41. The coefficient of thermal expansion of the head portion 42 is greater than that of the body portion 41.

[0067] When the ambient temperature changes, the valve body length L1 increases in accordance with the expansion of the valve body 10 and the guide member 68, and decreases in accordance with their contraction. When the ambient temperature changes, the valve element length L2 increases in accordance with the expansion of the valve seat 14, the body 41, the head 42, and the drive shaft 70, and decreases in accordance with their contraction. In the electric valve 1, the difference between the valve body length L1 and the valve element length L2 when the ambient temperature changes is smaller compared to a configuration in which the valve element 40 is made of a single material with a low coefficient of linear expansion. Therefore, the electric valve 1 can suppress abnormalities that occur when the ambient temperature changes.

[0068] Furthermore, the coefficient of linear expansion of the head 42 is greater than that of the valve body 10. In this way, the difference between the valve body length L1 and the valve element length L2 when the ambient temperature changes is reduced in the electric valve 1. Therefore, the electric valve 1 can further suppress abnormalities that occur when the ambient temperature changes.

[0069] Furthermore, for example, the drive shaft 70 may be made of engineering plastic. The coefficient of thermal expansion of engineering plastic is greater than that of stainless steel. That is, the coefficient of thermal expansion of the drive shaft 70 may be greater than that of the body 41. By doing so, the difference between the valve body length L1 and the valve element length L2 when the ambient temperature changes becomes smaller in the electric valve 1. Therefore, the electric valve 1 can further suppress abnormalities that occur when the ambient temperature changes.

[0070] Furthermore, the valve body 10 includes a main body member 11 on which the valve seat 14 is arranged, and a holder 20 attached to the main body member 11. A guide member 68 is attached to the holder 20. The coefficient of thermal expansion of the main body member 11 is greater than that of the body portion 41. The coefficient of thermal expansion of the holder 20 is the same as that of the body portion 41. The coefficient of thermal expansion of the head portion 42 is greater than that of the main body member 11. The coefficient of thermal expansion of the head portion 42 may be the same as that of the main body member 11. In this way, the difference between the valve body length L1 and the valve element length L2 when the ambient temperature changes is smaller in the electric valve 1 compared to a configuration in which the valve body 10 is made of a single material with a large coefficient of thermal expansion (for example, an aluminum alloy). Therefore, the electric valve 1 can further suppress abnormalities that occur when the ambient temperature changes. Note that the main body member 11 and the holder 20 may be made of aluminum alloy and formed integrally.

[0071] Furthermore, the valve seat 14 has a cylindrical shape and is attached to the main body member 11. The coefficient of linear expansion of the valve seat 14 may be greater than the coefficient of linear expansion of the body 41. In this way, the difference between the valve body length L1 and the valve element length L2 when the ambient temperature changes becomes smaller in the electric valve 1. Therefore, the electric valve 1 can further suppress abnormalities that occur when the ambient temperature changes.

[0072] Furthermore, the valve body 40 is attached to the head 42 and has a receiving member 43 in contact with the drive shaft 70. The material of the receiving member 43 is the same as that of the drive shaft 70. The material of the receiving member 43 may be a material with higher wear resistance than that of the drive shaft 70. In this way, wear of the drive shaft 70 and the receiving member 43, or of the receiving member 43, can be suppressed.

[0073] Furthermore, as shown in Figure 2, a gap is provided between the bottom surface of the first hole 42a1 of the head 42 and the upper end surface of the portion of the stem 41a of the body 41 that is positioned in the first hole 42a1, and at the connection point 40c, the lower end surface of the cylindrical portion 42a of the head 42 is in contact with the stem 41a. In this way, the amount of change in the vertical length of the valve body 40 when the ambient temperature changes is greater compared to a configuration in which the lower end surface of the cylindrical portion 42a of the head 42 is separated from the stem 41a. As a result, the difference between the valve body length L1 and the valve body length L2 when the ambient temperature changes becomes smaller.

[0074] Furthermore, the electric valve 1 has a valve body support member 25 held by the valve body 10. The valve body support member 25 has a support hole 26 that supports the body portion 41 so as to be movable in the vertical direction, and a relief hole 27 that is coaxially connected to the support hole 26. The diameter of the relief hole 27 is larger than the diameter of the support hole 26. When the valve body 40 is in contact with the valve seat 14, the body portion 41 is positioned in the support hole 26, and the connection point 40c between the body portion 41 and the head portion 42 is positioned in the relief hole 27. For example, due to tolerances, the outer circumferential surface of the stem 41a of the body portion 41 and the outer circumferential surface of the cylindrical portion 42a of the head portion 42 may be misaligned in the radial direction. If the connection point 40c enters the support hole 26, the vertical movement of the valve body 40 may be hindered. The relief hole 27 can prevent the connection point 40c from entering the support hole 26. Furthermore, the escape hole 27 allows the vertical length (length X) of the head 42 to be made longer.

[0075] Furthermore, the valve support member 25 may be made of stainless steel or brass. In particular, when the body portion 41 of the valve body 40 is made of stainless steel, it is preferable to make the valve support member 25 out of brass. By doing so, when the ambient temperature drops, the gap between the body portion 41 and the valve support member 25 in the support hole 26 of the valve support member 25 increases. As a result, the sliding resistance between the body portion 41 and the valve support member 25 decreases.

[0076] Furthermore, the electric valve 1 may be configured such that, when the electric valve 1 is in the closed state, the amount of change in the valve body length L2 due to temperature changes is greater than the amount of change in the valve body length L1, by adjusting the material and vertical length of the components related to the valve body length L1 and the valve element length L2. In particular, the electric valve 1 may be configured such that the amount of change (contraction) in the valve element length L2 due to temperature decrease is greater than the amount of change in the valve body length L1. By doing so, when the ambient temperature drops while the valve element 40 is in contact with the valve seat 14, the valve element length L2 becomes shorter than the valve body length L1. This suppresses the valve element 40 from being pressed too hard against the valve seat 14.

[0077] While the electric valve 1 had a reduction gear to reduce the rotation of the rotor 51, the present invention can also be applied to a direct-acting electric valve that does not reduce the rotation of the rotor.

[0078] The holder 20, can 30, connecting member 35, valve body 40, drive mechanism 50, and stator unit 8 of the electric valve 1 constitute one valve unit, and multiple valve units may be attached to one main body member. For example, the valve device 2B schematically shown in Figure 5 has one main body member 11B and two valve units 5B. The main body member 11B is made of aluminum alloy and has a valve chamber 13, valve seat 14, valve port 15, first passage 17, second passage 18, mounting hole 19, and valve body support member 25 corresponding to each of the two valve units 5B. The two valve units 5B together with the main body member 11B constitute two electric valves 1B. The two electric valves 1B have substantially the same configuration as the electric valve 1, except that they share the main body member 11B. The valve device 2B is incorporated into the refrigeration cycle system of an air conditioner, and an evaporator 90 is connected downstream of each of the two electric valves 1B. The two electric valves 1B are the first electric valve 1B and the second electric valve 1B.

[0079] For example, when the refrigeration cycle system is stopped, the first electric valve 1B and the second electric valve 1B are in a closed state. When the refrigeration cycle system starts cooling operation and the first electric valve 1B remains closed, allowing only the second electric valve 1B to operate as an expansion valve, the temperature of the main body component 11B decreases due to the refrigerant flowing through the second electric valve 1B. If the first electric valve 1B has the same configuration as a conventional electric valve, the valve body 40 may be strongly pressed against the valve seat 14, potentially causing the valve body 40 to become immobile. However, the electric valve 1B has the same configuration as the electric valve 1, and the difference between the valve body length L1 and the valve element length L2 when the ambient temperature changes is smaller compared to a conventional electric valve. Therefore, the electric valve 1B can suppress abnormalities that occur when the ambient temperature changes. The ambient temperature refers to the temperature of anything that affects the temperature of the electric valve 1B, and includes, for example, the ambient temperature of the space in which the valve device 2B having the first electric valve 1B and the second electric valve 1B is located, and the temperature of the refrigerant flowing through the second electric valve 1B that affects the first electric valve 1B.

[0080] The valve device 2B comprises one main body member 11B and a plurality of valve units 5B. Each of the plurality of valve units 5B comprises a holder 20 attached to the main body member 11B, a guide member 68 having a female thread 68t and attached to the holder 20, a drive shaft 70 having a male thread 72t that is screwed into the female thread 68t, and a valve body 40 that contacts or is connected to the drive shaft 70. The main body member 11B is provided with a valve seat 14 corresponding to each of the plurality of valve units 5B. The plurality of valve units 5B and the main body member 11B constitute a plurality of electric valves 1B. In each of the plurality of electric valves 1B, the valve seat 14, the valve body 40, and the drive shaft 70 are aligned in the axial direction of the drive shaft 70, and when the drive shaft 70 rotates in one direction, the valve body 40 moves toward the valve seat 14 and contacts the valve seat 14. In each of the multiple electric valves 1B, the valve seat 14 is defined as the reference position, the end of the female thread 68t furthest from the valve seat 14 is defined as the first position, and the end of the male thread 72t furthest from the valve seat 14 is defined as the second position. The axial length from the reference position to the first position in the main body member 11B, holder 20, and guide member 68 is defined as the valve body side length, and the axial length from the reference position to the second position in the valve seat 14, valve element 40, and drive shaft 70 is defined as the valve element side length. In the closed valve state where the valve element 40 is in contact with the valve seat 14, the amount of change in the valve element side length due to temperature change is greater than the amount of change in the valve body side length.

[0081] In this specification, terms indicating shapes such as "cylinder," "rod," and "cuboid" are also used to refer to members or parts of members that substantially have the shape of those terms. For example, "cylindrical member" includes both cylindrical members and substantially cylindrical members.

[0082] Although embodiments of the present invention have been described above, the present invention is not limited to the configurations of these embodiments. Additions, deletions, design modifications, and combinations of features of the embodiments, as appropriate by those skilled in the art, are also included within the scope of the present invention, as long as they do not contradict the spirit of the invention.

[0083] 1...Electric valve, 7...Valve body assembly, 10...Valve body, 11...Body member, 13...Valve chamber, 14...Valve seat, 15...Valve port, 20...Holder, 25...Valve body support member, 26...Support hole, 27...Relief hole, 40...Valve body, 40c...Connection point, 41...Body, 42...Head, 43...Receiving member, 50...Drive mechanism, 51...Rotor, 67...Output shaft, 67a...Slit, 68...Guide member, 68t...Female thread, 70...Drive shaft, 71...First part, 72...Second part, 72t...Male thread, 73...Ball, 8...Stator unit, 81...Housing, 82...Stator, 88...Stepping motor

Claims

1. An electric valve comprising a valve body, a guide member having an internal thread and attached to the valve body, a drive shaft having a external thread that is screwed into the internal thread, and a valve element that is in contact with or connected to the drive shaft, wherein the valve body is provided with a valve seat, the valve seat, the valve element, and the drive shaft are aligned in the axial direction of the drive shaft, and when the drive shaft rotates in one direction, the valve element moves toward the valve seat and makes contact with it, the valve seat is defined as the reference position, the end of the internal thread furthest from the valve seat is defined as the first position, the end of the internal thread furthest from the valve seat is defined as the second position, the axial length from the reference position to the first position in the valve body and the guide member is defined as the valve body side length, and the axial length from the reference position to the second position in the valve seat, the valve element, and the drive shaft is defined as the valve element side length. An electric valve characterized in that, in a closed valve state where the valve body is in contact with the valve seat, the amount of change in the length of the valve body due to temperature changes is greater than the amount of change in the length of the valve body.

2. The electric valve according to claim 1, wherein a cylindrical valve seat is attached to the valve body, the valve element is in contact with the first end of the valve seat, and the reference position is the second end of the valve seat.

3. The electric valve according to claim 1, wherein the reference position is the point on the valve seat where the valve body makes contact.

4. An electric valve comprising a valve body, a guide member having a female thread and attached to the valve body, a drive shaft having a male thread that is screwed into the female thread, and a valve element that is in contact with or connected to the drive shaft, wherein the valve body is provided with a valve seat, the valve seat, the valve element, and the drive shaft are aligned in the axial direction of the drive shaft, the valve element has a columnar body and a head connected to the first end of the body, when the drive shaft rotates in one direction, the valve element moves toward the valve seat and the second end of the body contacts the valve seat, the coefficient of thermal expansion of the valve body is greater than the coefficient of thermal expansion of the body, and the coefficient of thermal expansion of the head is greater than the coefficient of thermal expansion of the body.

5. The electric valve according to claim 4, wherein the coefficient of linear expansion of the head is greater than the coefficient of linear expansion of the valve body.

6. The electric valve according to claim 4, wherein the coefficient of linear expansion of the drive shaft is greater than the coefficient of linear expansion of the body.

7. The electric valve according to claim 4, wherein the valve body comprises a main body member on which the valve seat is arranged, and a holder attached to the main body member, the guide member is attached to the holder, the coefficient of thermal expansion of the main body member is greater than the coefficient of thermal expansion of the body, the coefficient of thermal expansion of the holder is the same as the coefficient of thermal expansion of the body, and the coefficient of thermal expansion of the head is greater than or equal to the coefficient of thermal expansion of the main body member.

8. The electric valve according to claim 4, wherein the valve body comprises a main body member on which the valve seat is disposed, and a holder attached to the main body member, the guide member is attached to the holder, the valve seat has a cylindrical shape and is attached to the main body member, and the coefficient of linear expansion of the valve seat is greater than the coefficient of linear expansion of the body.

9. The electric valve according to claim 4, wherein the valve body has a receiving member attached to the head and in contact with the drive shaft, and the material of the receiving member is the same material as the drive shaft, or a material with higher wear resistance than the drive shaft.

10. The electric valve according to claim 4, further comprising a valve body support member held by the valve body, wherein the valve body support member has a support hole for movably supporting the body and a relief hole coaxially connected to the support hole, the diameter of the relief hole being larger than the diameter of the support hole, and when the valve body is in contact with the valve seat, the body is positioned in the support hole and the connection point between the body and the head is positioned in the relief hole.

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