electric valve

Abstract

An electric valve with high durability and low power consumption is provided. The electric valve (1) includes: a valve body (10) having a valve chamber (14) and a valve port (13a); a valve core (30) for opening and closing the valve port (13a); and a support member (20) supporting the valve core (30) so that it can move forward and backward relative to the valve port (13a). The electric valve (1) includes: a drive shaft (25) having an external thread (26); a rolling bearing (23) supporting the drive shaft (25) so that it can rotate; a planetary gear mechanism (50) connected to the drive shaft (25); and an internal thread body (32) fixed to the valve core (30). The internal thread body (32) is screwed into the external thread (26). Furthermore, the support member (20) supports the internal thread body (32) to restrict the rotation of the internal thread body about the axis (L) and allow the internal thread body to move in the direction of the axis (L).

Description

Technical Field

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

[0002] Patent document 1 discloses an example of a conventional electric valve. Figure 7 The conventional electric valve 901 shown has a valve core 930. A thrust transmission component 963 is fixed to the valve core 930. The valve core 930 opens and closes a valve port 913a that opens into the valve chamber 914.

[0003] The electric valve 901 has a stepper motor consisting of a stator 942 and a rotor 943. The rotational force of the stepper motor is transmitted to a rotary lifting shaft 964 via a planetary gear mechanism 950. The rotary lifting shaft 964 is screwed onto a bearing component 922. The rotary lifting shaft 964 moves vertically via a threaded feed. When the rotary lifting shaft 964 moves downward, it presses the thrust transmission component 963 downward via a ball 967 and a ball bearing 968. When the rotary lifting shaft 964 moves upward, the spring support body 961, which is pressed upward by the valve opening spring 962, pulls the thrust transmission component 963 upward. The valve core 930 moves vertically together with the thrust transmission component 963.

[0004] In the electric valve 901, the valve core 930 is disposed in the valve core guide hole 921c of the support member 920. A sealing member 936 is disposed between the valve core 930 and the support member 920. The sealing member 936 divides the space (back pressure chamber 929) above the valve core 930 in the valve chamber 914 and the valve core guide hole 921c. When the lower end of the valve core 930 contacts the valve seat 913b and the valve port 913a is closed, the electric valve 901 is in the closed state. In the closed state, the valve port 913a and the back pressure chamber 929 are connected via a pressure equalization passage 939 formed in the valve core 930 and the thrust transmission member 963. With this configuration, the upward fluid pressure and the downward fluid pressure applied to the valve core 930 are canceled out.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2013-130271

[0008] The technical problem that the invention aims to solve

[0009] The electric valve 901 is used in systems where the pressure difference between the fluid on the inflow side and the fluid on the outflow side is large. In the electric valve 901, to prevent fluid leakage between the valve chamber 914 and the back pressure chamber 929, the sealing member 936 is pressed forcefully against the support member 920 while sliding. Therefore, the frictional force of the sealing member 936 is relatively large, requiring increased rotational force of the stepper motor and spring force of the valve opening spring 962.

[0010] In the electric valve 901, ball 967 slides relative to the rotary lifting shaft 964 (or ball bearing 968). The rotational force of the rotary lifting shaft 964 is not transmitted to the thrust transmission component 963 but only to the downward pressing force. Therefore, the force is concentrated on ball 967, causing it to wear out rapidly. The wear of ball 967 is a factor contributing to the reduced durability of the electric valve 901. Furthermore, when the rotary lifting shaft 964 moves downward, the stepper motor also outputs rotational force to compress the valve opening spring 962. Therefore, the electric valve 901 consumes a large amount of power. Summary of the Invention

[0011] Therefore, the object of the present invention is to provide an electric valve with high durability and low power consumption.

[0012] Technical means for solving technical problems

[0013] To achieve the above objectives, the electric valve of the present invention comprises: a valve body having a valve chamber and a valve port; a valve core for opening and closing the valve port; and a support member supporting the valve core so as to be able to move forward and backward relative to the valve port. The electric valve is characterized by having: a drive shaft arranged along the forward and backward direction of the valve core and having an external thread; a rolling bearing held in the support member and supporting the drive shaft for rotation; a planetary gear mechanism connected to the drive shaft; and a cylindrical internally threaded body fixed to the valve core and screwed into the external thread, the support member supporting the internally threaded body to restrict rotation about an axis and allow the internally threaded body to move axially.

[0014] In the electric valve according to the present invention, the drive shaft is rotatably supported on a rolling bearing. An internally threaded body engages with the externally threaded portion of the drive shaft. Furthermore, a support member supports the internally threaded body to restrict its rotation about the shaft and allow it to move axially. Thus, when the drive shaft, connected to the planetary gear mechanism, rotates, the internally threaded body moves axially (in the valve core's forward and backward movement direction) via a threaded feed action. Although an axial force is applied to the drive shaft along with the movement of the internally threaded body, this force is distributed among the multiple rolling elements of the rolling bearing. Therefore, the electric valve can prevent force concentration and improve durability. Additionally, the valve core moves forward and backward relative to the valve port via the threaded feed action. Therefore, compared to a structure with an opening spring, the electric valve can reduce power consumption.

[0015] In this invention, preferably, the support member has a valve core guide hole for the valve core to be positioned, and the internal threaded body has a transverse hole extending from the outer circumferential surface to the inner circumferential surface. The inner space of the internal threaded body and the transverse hole form a pressure equalization passage connecting the valve port to a back pressure chamber in the valve core guide hole, which is the space on the other end side of the valve core, when the valve core is in contact with the valve seat at one end. In the fully open state, when the valve core is furthest from the valve seat, the external thread enters the internal threaded body until it closes the transverse hole. Thus, in the fully open state of the electric valve, the pressure equalization passage is closed by the external thread of the drive shaft. Therefore, it is possible to prevent foreign matter contained in the fluid from entering the back pressure chamber.

[0016] In this invention, preferably, the drive shaft has a base integrally and continuously disposed with the external thread portion and connected to the output portion of the planetary gear mechanism, the rolling bearing is a radial ball bearing, the outer ring of the rolling bearing is held in the support member, and the inner ring of the rolling bearing is held between the base and the nut that engages with the external thread portion. Thus, the drive shaft can be supported on the rolling bearing with a simple structure combining the external thread portion and the nut. Furthermore, by using the nut, pressure management of the inner ring is easier compared to a structure that presses the drive shaft into the inner ring of the rolling bearing.

[0017] In this invention, preferably, the cross-sectional shape of the internal threaded body is polygonal, and the support member has a partition that divides its inner space axially. The partition has a support hole for the internal threaded body to be disposed, and the support hole has the same shape as the cross-sectional shape of the internal threaded body. Thus, with a simple structure, the support member can support the internal threaded body to restrict its rotation about an axis while allowing it to move axially.

[0018] The effects of the invention

[0019] According to the present invention, durability can be improved and power consumption can be reduced. Attached Figure Description

[0020] Figure 1 This is a longitudinal sectional view showing the closed state of an electric valve according to an embodiment of the present invention.

[0021] Figure 2 It means Figure 1 A longitudinal sectional view of the electric valve in its fully open state.

[0022] Figure 3 It is along Figure 1 A cross-sectional view along line III-III.

[0023] Figure 4 It is along Figure 1 A cross-sectional view along line IV-IV.

[0024] Figure 5 This is a longitudinal sectional view of an electric valve (with a valve opening spring) according to other embodiments of the present invention.

[0025] Figure 6 This is a longitudinal sectional view of an electric valve (with a structure having two thrust ball bearings) according to other embodiments of the present invention.

[0026] Figure 7 This is a cross-sectional view of a conventional electric valve. Detailed Implementation

[0027] The following is for reference Figures 1-4 The structure of an electric valve according to an embodiment of the present invention will be described.

[0028] Figure 1 , Figure 2 This is a longitudinal sectional view (a sectional view along axis L) of an electric valve according to an embodiment of the present invention. Figure 1 This indicates the closed state of the electric valve. Figure 2 This indicates that the electric valve is fully open. Figure 3 It is along Figure 1 A cross-sectional view along line III-III. Figure 4 It is along Figure 1 A cross-sectional view along line IV-IV.

[0029] The electric valve 1 described in this embodiment is used as an expansion valve, for example, in a heat pump refrigeration and heating system. The electric valve 1 is a bidirectional flow type electric valve that allows for bidirectional flow of fluid (refrigerant).

[0030] The electric valve 1 has a valve body 10, a housing 18, a support component 20, a rolling bearing 23, a drive shaft 25, a valve core 30, an internal thread body 32, a sealing component 36, and a valve core drive part 40.

[0031] The valve body 10 has a cylindrical component 11, a retainer 12, and a valve seat component 13.

[0032] The cylindrical component 11 has a generally cylindrical shape. A valve chamber 14 is formed on the inner side of the cylindrical component 11.

[0033] The retainer 12 has a stepped, generally cylindrical shape with a lower outer diameter larger than the upper outer diameter. The lower part of the retainer 12 is inserted into the upper end opening 11a of the cylindrical member 11. The cylindrical member 11 and the retainer 12 are welded together. Furthermore, the length of the portion of the retainer 12 disposed inside the cylindrical member 11 in the axial direction L is set to a length that maintains the insertion relationship between the retainer 12 and the cylindrical member 11 even after welding. A downward-facing, annular planar retaining surface 12a is formed on the inner side of the retainer 12.

[0034] The valve seat component 13 has a generally cylindrical shape. The valve seat component 13 is housed within the valve chamber 14. The lower part of the valve seat component 13 is embedded in the lower end opening 11b of the cylindrical component 11. The cylindrical component 11 and the valve seat component 13 are brazed. The valve seat component 13 has a valve port 13a, which is a circular orifice. The valve port 13a opens into the valve chamber 14. An annular valve seat 13b is formed on the inner edge of the upper end of the valve seat component 13. The valve seat 13b surrounds the valve port 13a.

[0035] A first conduit 15 is brazed onto the cylindrical component 11. The first conduit 15 extends through the cylindrical component 11 laterally (in a direction orthogonal to the axis L) and is connected to the valve chamber 14. A second conduit 16 is brazed onto the valve seat component 13. The second conduit 16 is connected to the valve port 13a. Furthermore, the length of the portion of the first conduit 15 disposed inside the cylindrical component 11 is preferably a length to which molten brazing filler metal (solder lead) will not flow into the first conduit 15 from the valve chamber 14 side.

[0036] The housing 18 has a cylindrical shape that is closed at the top. The lower end of the housing 18 is welded to the upper part of the retainer 12.

[0037] The support component 20 has a valve core support portion 21 and a drive shaft support portion 22.

[0038] The valve core support portion 21 has a cylindrical shape. The upper part of the valve core support portion 21 is pressed into the inside of the retainer 12. The lower part of the valve core support portion 21 is spaced apart from the valve seat component 13 in the vertical direction (axis L direction). The lower part of the valve core support portion 21 and the valve seat component 13 are opposite each other in the vertical direction. The valve core support portion 21 has a partition wall 21a. The partition wall 21a divides the inner space of the valve core support portion 21 vertically. The space above the partition wall 21a is the spring chamber 21b. The space below the partition wall 21a is the valve core guide hole 21c. A square support hole 21d is formed in the partition wall 21a.

[0039] The upper part 22a of the drive shaft support 22 has a cylindrical shape. The lower part 22b of the drive shaft support 22 has a cylindrical shape. A valve hole 22c extending vertically is formed in the upper part 22a of the drive shaft support 22. An annular protrusion 22d protruding radially outward is formed at the lower end of the lower part 22b of the drive shaft support 22. The protrusion 22d is held between the retaining surface 12a of the retainer 12 and the upper part of the valve core support 21, which is pressed into the inside of the retainer 12. The lower part 22b of the drive shaft support 22, together with the valve core support 21, defines a spring chamber 21b. An annular planar receiving surface 22e facing downward is formed on the inner side of the lower part 22b of the drive shaft support 22.

[0040] Rolling bearing 23 is a radial ball bearing. A plurality of balls 23c, serving as rolling elements, are arranged between the outer ring 23a and the inner ring 23b of rolling bearing 23. Rolling bearing 23 is located inside the lower part 22b of drive shaft support 22. The upper end of the outer ring 23a contacts the bearing surface 22e of the lower part 22b of drive shaft support 22. A retaining spring 24 in a compressed state is arranged between the lower end of the outer ring 23a and the partition wall 21a. The outer ring 23a is pressed against the bearing surface 22e by the retaining spring 24. The retaining spring 24 applies pressure to the outer ring 23a. Alternatively, a thrust bearing may be used as rolling bearing 23.

[0041] The drive shaft 25 is arranged in the vertical direction. The drive shaft 25 integrally has an external thread portion 26 and a base portion 27. The drive shaft 25 is formed, for example, by machining a single piece of metal material such as stainless steel. The external thread portion 26 has a cylindrical shape. An external thread 26c is formed on the outer peripheral surface of the external thread portion 26. The base portion 27 has a first shaft portion 27a, a second shaft portion 27b, and a connecting portion 27c.

[0042] The first shaft portion 27a has a cylindrical shape. The first shaft portion 27a is continuously disposed at the upper end of the external thread portion 26. The diameter of the first shaft portion 27a is larger than the diameter of the external thread portion 26 and is the same as the inner diameter of the inner ring 23b of the rolling bearing 23. The first shaft portion 27a is inserted into the inner ring 23b. The first shaft portion 27a is disposed inside the inner ring 23b. The first shaft portion 27a is rotatably supported on the rolling bearing 23 about the axis L.

[0043] The second shaft portion 27b has a cylindrical shape. The second shaft portion 27b is continuously disposed at the upper end of the first shaft portion 27a. The diameter of the second shaft portion 27b is larger than that of the first shaft portion 27a and is the same as the inner diameter of the shaft hole 22c of the drive shaft support portion 22. The second shaft portion 27b is inserted into the shaft hole 22c. The second shaft portion 27b is disposed in the shaft hole 22c. The second shaft portion 27b is rotatably supported on the drive shaft support portion 22 about the axis L. The inner ring 23b of the rolling bearing 23 is held between the second shaft portion 27b and the nut 28 that engages with the external thread portion 26. The pressure applied to the inner ring 23b is adjusted by the degree of tightening of the nut 28.

[0044] The connecting portion 27c protrudes from the upper surface of the second shaft portion 27b. The connecting portion 27c has a cylindrical or prismatic shape. The connecting portion 27c is connected to the planetary gear mechanism 50 of the valve core drive portion 40.

[0045] The valve core 30 opens and closes the valve port 13a. The valve core 30 has a generally cylindrical shape. The outer diameter of the valve core 30 is the same as the diameter of the valve core guide hole 21c of the support member 20. The valve core 30 is inserted into the valve core guide hole 21c. The valve core 30 is disposed in the valve core guide hole 21c. The space above the valve core 30 in the valve core guide hole 21c is a back pressure chamber 29. The valve core 30 can slide in the vertical direction within the valve core guide hole 21c. The valve core 30 is vertically opposite the valve seat member 13. The vertical movement of the valve core 30 is guided by the support member 20. The support member 20 supports the valve core 30 so that it can move forward and backward relative to the valve port 13a.

[0046] The internally threaded body 32 has a generally square cylindrical shape. The internally threaded body 32 has a main body 33 made of synthetic resin and a press-fit frame 34 made of metal. The main body 33 and the press-fit frame 34 are integrated by insert molding.

[0047] The main body 33 has a generally square cylindrical shape. In this embodiment, the cross-sectional shape of the main body 33 is square. The shape of the support hole 21d of the support member 20 is also square, with the same cross-sectional shape as the main body 33. The main body 33 is inserted into the support hole 21d. The main body 33 is disposed in the support hole 21d. In this specification, the shapes (diameter, shape) of structures in an insertion relationship, such as "valve core 30 and valve core guide hole 21c", "main body 33 and support hole 21d", and "second shaft portion 27b of drive shaft 25 and shaft hole 22c of drive shaft support portion 22", are "the same", including the same degree of similarity in that one is only slightly smaller than the other and can move in the insertion direction. Furthermore, the cross-sectional shape of the main body 33 and the shape of the support hole 21d may also be, for example, a regular hexagon or other polygonal shapes. The rotation of the main body 33 disposed in the support hole 21d about the axis L is restricted, but it can move in the direction of the axis L. That is, the support member 20 supports the main body 33 to restrict the rotation of the main body 33 about the axis L and to enable the main body 33 to move in the direction of the axis L.

[0048] The upper part of the main body 33 is an internally threaded portion 33a. An internal thread 33c is formed on the inner circumferential surface of the internally threaded portion 33a. The internal thread 33c engages with the external thread 26c of the drive shaft 25. The engagement portion of the internal thread 33c of the synthetic resin main body 33 and the external thread 26c of the metal drive shaft 25 can omit lubricant. A transverse hole 33b is formed below the internal thread 33a in the main body 33. The transverse hole 33b extends from the outer circumferential surface of the main body 33 to the inner circumferential surface. The transverse hole 33b connects to the inner space 33d of the main body 33. The inner space 30d of the valve core 30, the inner space 33d of the main body 33, and the transverse hole 33b constitute a pressure equalization passage 39. The pressure equalization passage 39 connects the valve port 13a and the back pressure chamber 29 in the closed state.

[0049] The press-fit frame portion 34 has a cylindrical portion 34a and a flange portion 34b. The cylindrical portion 34a has a square cross-section. The cylindrical portion 34a is embedded in the lower part of the main body portion 33. The cylindrical portion 34a is pressed into a square hole 30c in the upper surface 30a of the valve core 30. The internally threaded body 32 is fixed to the valve core 30. The flange portion 34b has an annular plate shape. The flange portion 34b protrudes radially outward from the upper end of the cylindrical portion 34a. The flange portion 34b is disposed on the upper surface 30a of the valve core 30. The flange portion 34b, together with the cut-step portion disposed on the periphery of the upper surface 30a of the valve core 30, forms an annular groove 35. The annular groove 35 maintains the annular sealing member 36.

[0050] The sealing member 36 is configured in a radially compressed state between the valve core 30 and the support member 20. The sealing member 36 seals the space between the valve core 30 and the support member 20. The sealing member 36 divides the valve chamber 14 and the back pressure chamber 29.

[0051] The sealing component 36 has a sealing portion and an outer cover portion. The sealing portion is a ring-shaped component made of a rubber-like elastic material (rubber material or synthetic resin material with rubber-like elasticity, etc.). The sealing portion is, for example, an O-ring. The outer cover portion is a ring-shaped strip component made of a synthetic resin such as polytetrafluoroethylene (PTFE) with smaller elastic deformation than the sealing portion. The outer cover portion covers the outer periphery of the sealing portion. The outer peripheral surface of the outer cover portion contacts the inner peripheral surface of the valve core guide hole 21c. When the valve core 30 moves in the up and down direction, the outer peripheral surface of the outer cover portion slides on the inner peripheral surface of the valve core guide hole 21c. The material of the outer cover portion is selected considering sliding performance, resistance to foreign object deformation, and wear resistance. Alternatively, the sealing component 36 may also have only a sealing portion and no outer cover portion.

[0052] The valve core drive unit 40 moves the valve core 30 in the vertical direction, causing the valve core 30 to come into contact with and separate from the valve seat 13b of the valve seat component 13.

[0053] The valve core drive unit 40 includes a stator 42, a rotor 43, a rotor shaft 44, a connecting member 45, and a planetary gear mechanism 50. The stator 42 is disposed on the outside of the housing 18. The rotor 43 is rotatably disposed on the inside of the housing 18. The rotor 43 is connected to the rotor shaft 44 via a circular plate-shaped connecting member 45. The stator 42 and the rotor 43 constitute an electric motor. The planetary gear mechanism 50 reduces the rotational speed of the rotor 43.

[0054] A planetary gear mechanism 50 is disposed inside the rotor 43. The planetary gear mechanism 50 includes a gearbox 51, a sun gear 52, a fixed ring gear 53, multiple planetary gears 54, a planetary gear carrier 55, and an output gear 56 as an output section. The gearbox 51 has a cylindrical shape. The gearbox 51 is fitted to the upper part of the support member 20. The sun gear 52 is integrated with the connecting member 45. The rotor shaft 44 is inserted into the inside of the sun gear 52. The fixed ring gear 53 is an internal gear and is fixed to the upper end of the gearbox 51. Multiple planetary gears 54 surround the sun gear 52. The planetary gears 54 mesh with the sun gear 52 and the fixed ring gear 53. The planetary gear carrier 55 supports the planetary gear 43 so that it can rotate. The output gear 56 is an internal gear with a bottom cylindrical shape. The output gear 56 meshes with the planetary gears 54. The connecting portion 27c of the drive shaft 25 is pressed into a through hole at the bottom of the output gear 56. The drive shaft 25 rotates together with the output gear 56.

[0055] The electric valve 1 has a 3K type planetary gear mechanism 50 as a reduction mechanism. The electric valve 1 can also use other types of reduction mechanisms. For example, the electric valve 1 can use a 2K-H type planetary gear mechanism with two or more stages, or a reduction mechanism with a worm gear device (worm and worm wheel).

[0056] In this embodiment, the cylindrical component 11, retainer 12, valve seat component 13 (valve port 13a, valve seat 13b), support component 20 (valve core guide hole 21c, support hole 21d, shaft hole 22c), rolling bearing 23, drive shaft 25, valve core 30, rotor shaft 44, and output gear 56 all have their axes aligned with axis L. The direction of axis L is also the forward and backward direction of valve core 30.

[0057] Next, an example of the operation of the electric valve 1 involved in this embodiment will be described.

[0058] The electric valve 1 generates rotational force in the rotor 43 by causing current to flow in the stator 42. The rotational force of the rotor 43 is reduced by the planetary gear mechanism 50 and transmitted from the output gear 56 to the drive shaft 25. When the drive shaft 25 rotates, the internal thread body 32 moves up and down according to the direction of rotation through thread feed. The valve core 30 also moves up and down together with the internal thread body 32.

[0059] When the internal thread body 32 moves downward, the valve core 30 also moves downward. The lower end 30b of the valve core 30 contacts the valve seat 13b, closing the valve port 13a (closed valve state). In the closed valve state, the valve port 13a and the back pressure chamber 29 are connected through the pressure equalization passage 39. Therefore, the upward fluid pressure and the downward fluid pressure applied to the valve core 30 are canceled out.

[0060] In the closed state, when the internal thread body 32 moves upward, the valve core 30 also moves upward. The lower end 30b of the valve core 30 separates from the valve seat 13b, opening the valve port 13a (open state). Furthermore, as... Figure 2 As shown, when the valve core 30 moves to its uppermost position furthest from the valve seat 13b, the electric valve 1 becomes fully open. In the fully open state, the external thread 26 of the drive shaft 25 enters the inner space 33d of the internal thread body 32 until it closes the transverse hole 33b of the internal thread body 32. Thus, the pressure equalization passage 39 is closed by the external thread 26.

[0061] As described above, in the electric valve 1 of this embodiment, the drive shaft 25 is rotatably supported on the rolling bearing 23. The internally threaded body 32, fixed to the valve core 30, engages with the externally threaded portion 26 of the drive shaft 25. Furthermore, the support member 20 supports the internally threaded body 32 to restrict its rotation about the axis L and allow it to move in the direction of the axis L. Thus, when the drive shaft 25, connected to the planetary gear mechanism 50, rotates, the internally threaded body 32 moves in the direction of the axis L through threaded feed. Although a force in the direction of the axis L is applied to the drive shaft 25 along with the movement of the internally threaded body 32, this force is dispersed to the plurality of balls 23c of the rolling bearing 23. Therefore, the electric valve 1 can prevent force concentration and improve durability. Additionally, the valve core 30 moves forward and backward relative to the valve port 13a through threaded feed. Therefore, the electric valve 1 can reduce power consumption compared to a structure with an opening spring.

[0062] Additionally, the support member 20 has a valve core guide hole 21c for arranging the valve core 30. The internally threaded body 32 has a transverse hole 33b extending from the outer peripheral surface to the inner peripheral surface. The inner space 30d of the valve core 30, the inner space 33d of the internally threaded body 32, and the transverse hole 33b constitute a pressure equalization passage 39 connecting the valve port 13a and the back pressure chamber 29 in the closed state. In the fully open state, with the valve core 30 furthest from the valve seat 13b, the external thread 26 of the drive shaft 25 enters the internally threaded body 32 until it closes the transverse hole 33b. Thus, in the fully open state, the pressure equalization passage 39 is closed by the external thread 26 of the drive shaft 25. Therefore, it is possible to prevent foreign matter contained in the fluid from entering the back pressure chamber 29.

[0063] Furthermore, the drive shaft 25 has a base 27, which is integrally and continuously provided with the external thread portion 26 and connected to the output gear 56 of the planetary gear mechanism 50. The rolling bearing 23 is a radial ball bearing. The outer ring 23a of the rolling bearing 23 is held in the support member 20. The inner ring 23b is held between the second shaft portion 27b of the base 27 and the nut 28 that engages with the external thread portion 26. Thus, the drive shaft 25 can be supported on the rolling bearing 23 with a simple structure that combines the external thread portion 26 and the nut 28. In addition, by using the nut 28, it is easier to manage the pressure on the inner ring 23b compared to a structure that presses the drive shaft 25 into the inner ring 23b of the rolling bearing 23.

[0064] Furthermore, the internal thread body 32 has a square cross-sectional shape. The valve core support portion 21 of the support member 20 has a partition wall 21a that divides its inner space in the direction of the axis L. The partition wall 21a has a support hole 21d for arranging the internal thread body 32. The support hole 21d has a square shape with the same cross-sectional shape as the internal thread body 32. Thus, with a relatively simple structure, the support member 20 supports the internal thread body 32 to restrict the rotation of the internal thread body 32 about the axis L and allow the internal thread body 32 to move in the direction of the axis L.

[0065] like Figure 1 As shown, the electric valve 1 involved in this embodiment has a distance D1 between the nut 28 and the internal thread body 32 and a distance D2 between the partition wall 21a of the support member 20 and the internal thread body 32. The maximum movement of the valve core 30 is limited to the smallest of the distances D1 and D2 when the valve is closed.

[0066] On the other hand, in the conventional electric valve 901, such as Figure 7 As shown, the following are provided: a gap E1 within the slit 957a of the output shaft 957 of the planetary gear mechanism 950; a gap E2 between the output shaft 957 and the rotary lifting shaft 964; a gap E2 between the bearing component 922 and the spring support body 961; a gap E4 between the bearing component 922 and the thrust transmission component 963; and a gap E5 between the valve core 930 and the partition wall 921a. The maximum movement of the valve core 930 is limited to the smallest of the gaps E1 to E5 when the valve is closed.

[0067] When the maximum movement of the valve core is set to α, in the electric valve 1 of this embodiment, two intervals (intervals D1 and D2) only need to be α or greater. However, in the conventional electric valve 901, all five intervals (intervals E1 to E5) need to be α or greater. Therefore, the electric valve 1 of this embodiment, with the same size as the conventional electric valve 901, can achieve a greater maximum movement of the valve core 30 than the electric valve 901.

[0068] Next, refer to Figure 5 , Figure 6 Other embodiments of the present invention will be described with respect to electric valves 1A and 1B. In the following description, structures different from those of electric valve 1 will be mainly described, while structures identical to those of electric valve 1 (including those having substantially the same function) will be marked with the same symbols as those of electric valve 1 and detailed descriptions will be omitted.

[0069] Figure 5 The electric valve 1A shown has a support component 20A, a valve core 30A, and an internally threaded body 32A.

[0070] The support member 20A has a valve core support portion 21A and a drive shaft support portion 22.

[0071] The valve core support portion 21A has a first component 211 and a second component 212.

[0072] The first component 211 has a generally cylindrical shape. The upper part of the first component 211 is pressed into the inside of the retainer 12. The lower part of the first component 211 is disposed at a distance from the valve seat component 13 in the vertical direction. The lower part of the first component 211 and the valve seat component 13 are opposite each other in the vertical direction. The inner space of the first component 211 is a valve core guide hole 21c for the valve core 30A to be disposed. An upward-facing annular planar spring support surface 211a is formed on the inner peripheral surface of the first component 211.

[0073] The second component 212 has a cylindrical portion 212a and a flange portion 212b. The cylindrical portion 212a is disposed inside the first component 211. The cylindrical portion 212a has a circular outer cross-section and a square inner cross-section. The inner space of the cylindrical portion 212a is a support hole 21d for the internal thread body 32A. The flange portion 212b has an annular shape. The flange portion 212b protrudes radially outward from the upper end of the cylindrical portion 212a. The outer periphery of the flange portion 212b engages with the upper end of the first component 211. The second component 212 restricts the rotation of the internal thread body 32A about the axis L.

[0074] The inner ring 23b of the rolling bearing 23 is held between the second shaft portion 27b of the drive shaft 25 and the fixed wheel 28A that fits into the groove of the first shaft portion 27a.

[0075] The valve core 30A opens and closes the valve port 13a. The valve core 30A has a generally cylindrical shape. The outer diameter of the valve core 30A is the same as the diameter of the valve core guide hole 21c of the support member 20A. The valve core 30A is inserted into the valve core guide hole 21c. The valve core 30A is positioned within the valve core guide hole 21c. The valve core 30A can slide vertically within the valve core guide hole 21c. The valve core 30A is vertically opposite the valve seat member 13. The vertical movement of the valve core 30A is guided by the support member 20A. The support member 20A supports the valve core 30A so that it can move forward and backward relative to the valve port 13a.

[0076] The internal thread body 32A has a main body 33A and a press-fit frame 34A.

[0077] The main body 33A has a generally square cylindrical shape. In this embodiment, the cross-sectional shape of the main body 33A is square. The support hole 21d of the support member 20A is also square, with the same cross-sectional shape as the main body 33A. The main body 33A is inserted into the support hole 21d. The main body 33A is disposed in the support hole 21d. The support member 20A (second member 212) supports the main body 33A to restrict the rotation of the main body 33A about the axis L and to allow the main body 33A to move in the direction of the axis L.

[0078] The upper part of the main body 33A is an internally threaded part 33a. An internal thread 33c is formed on the inner circumferential surface of the internally threaded part 33a. The internal thread 33c engages with the external thread 26c of the drive shaft 25. A transverse hole 33b is formed below the internal thread 33a in the main body 33A. The transverse hole 33b extends from the outer circumferential surface of the main body 33A to the inner circumferential surface. The transverse hole 33b is connected to the inner space 33d of the main body 33A. The inner space 30d of the valve core 30A, the inner space 33d of the main body 33A, and the transverse hole 33b constitute a pressure equalization passage 39. The pressure equalization passage 39 connects the valve port 13a and the back pressure chamber 29 in the closed state.

[0079] The press-fit frame portion 34A has a cylindrical portion 34c and a flange portion 34d. The lower part of the main body portion 33A is disposed inside the lower part of the cylindrical portion 34c. The lower part of the cylindrical portion 34c is pressed into a hole 30c in the upper surface 30a of the valve core 30A. Thus, the internally threaded body 32A (the main body portion 33A and the press-fit frame portion 34A) is fixed to the valve core 30A. A filter 37A is disposed inside the hole 30c of the valve core 30A, between the valve core 30A and the main body portion 33A. The filter 37A captures foreign matter contained in the fluid flowing in the equalizing passage 39. The flange portion 34d has an annular plate shape. The flange portion 34d protrudes radially outward from the upper end of the cylindrical portion 34c. The flange portion 34d is disposed at a distance from the spring support surface 211a of the first step 211 in the vertical direction. A valve-opening spring 38A in a compressed state is disposed between the flange portion 34d and the spring support surface 211a. The flange portion 34d (i.e., the valve core 30A) is pressed upward by the valve-opening spring 38A.

[0080] The space within the valve core guide hole 21c, where the press-fit frame portion 34A is disposed, is a back pressure chamber 29. A sealing member 36 is held in an annular groove 35A formed by the valve core 30A and the internal threaded body 32A. The sealing member 36 is disposed in a radially compressed state between the internal threaded body 32A (press-fit frame portion 34A) and the support member 20A (first member 211). The sealing member 36 seals the space between the valve core 30A and the support member 20A. The sealing member 36 divides the valve chamber 14 and the back pressure chamber 29.

[0081] Figure 6 The electric valve 1B shown has a support component 20B, a valve core 30A, an internal thread body 32A, two rolling bearings 23B, and a drive shaft 25B.

[0082] The support component 20B has a valve core support portion 21A and a drive shaft support portion 22B.

[0083] The drive shaft support portion 22B has a generally cylindrical shape. An annular protrusion 22f protruding radially inward is formed at the upper end of the drive shaft support portion 22B. An annular planar bearing surface 22g facing downward is formed on the protrusion 22f.

[0084] The drive shaft 25B integrally has an external threaded portion 26 and a base 27B. The base 27B has a first shaft portion 27a, a second shaft portion 27b, a connecting portion 27c, and a flange portion 27d. The flange portion 27d has an annular plate shape. The inner peripheral edge of the flange portion 27d is connected to the outer peripheral surface of the second shaft portion 27b.

[0085] The two rolling bearings 23 are thrust ball bearings. Multiple balls 23f, serving as rolling elements, are arranged between the upper track plate 23d and the lower track plate 23e of the rolling bearing 23B. The two rolling bearings 23B are arranged vertically (in the direction of axis L) inside the drive shaft support portion 22B. The flange portion 27d of the drive shaft 25B is arranged between the two rolling bearings 23B. The upper track plate 23d of the upper rolling bearing 23B contacts the bearing surface 22g at the upper end of the drive shaft support portion 22B. A retaining spring 24 in a compressed state is arranged between the lower track plate 23e of the lower rolling bearing 23B and the second component 212 of the support component 20B. The lower rolling bearing 23B is pressed upwards by the retaining spring 24. The upper track plate 23d of the upper rolling bearing 23B is pressed against the bearing surface 22g. The second shaft portion 27b of the drive shaft 25B is arranged inside the two rolling bearings 23B. Two rolling bearings 23B support the drive shaft 25B for rotation. The upper rolling bearing 23B primarily bears the upward force applied to the valve core 30A. The lower rolling bearing 23B primarily bears the downward force applied to the valve core 30A.

[0086] Electric valves 1A and 1B have the same function as electric valve 1 mentioned above.

[0087] In particular, since the valve core 30A of the electric valve 1A is pressed upward by the valve opening spring 38A, the hysteresis characteristics of the valve core 30A during vertical movement can be reduced. Furthermore, since the electric valve 1B receives the pressure applied to the valve core 30A and the drive shaft 25B through two rolling bearings 23B, high durability can be achieved in systems where the difference between the fluid pressure on the inflow side and the fluid pressure on the outflow side is large.

[0088] While embodiments of the present invention have been described above, the present invention is not limited to the structures of the embodiments. Structures obtained by adding, deleting, or modifying structural elements of the above embodiments, or by appropriately combining features of the embodiments, without departing from the spirit of the present invention, are also included within the scope of the present invention.

[0089] Symbol Explanation

[0090] 1…Electric valve, 10…Valve body, 11…Cylindrical component, 11a…Upper opening, 11b…Lower opening, 12…Retainer, 12a…Retaining surface, 13…Valve seat component, 13a…Valve port, 13b…Valve seat, 14…Valve chamber, 15…First conduit, 16…Second conduit, 18…Housing, 20…Support component, 21…Valve core support, 21a…Blocking wall, 21b…Spring chamber, 21c…Valve core guide hole, 21d…Support hole, 22…Drive shaft support, 22a…Upper part, 22b…Lower part, 22c…Shaft hole, 22d…Protrusion, 22e…Receiving surface, 23…Rolling bearing, 24…Retaining spring, 25…Drive shaft, 26…External thread, 26c…External thread, 27…Base, 27a…First shaft, 27… b…Second shaft, 27c…Connecting part, 28…Nut, 29…Back pressure chamber, 30…Valve core, 30a…Upper surface, 30b…Lower end, 30c…Hole, 30d…Inner space, 32…Internal thread body, 33…Main body, 33a…Internal thread, 33b…Horizontal hole, 33c…Internal thread, 33d…Inner space, 34…Press-in frame, 34a…Cylinder, 34b…Flange, 35…Annular groove, 36…Sealing material, 39…Pressure equalization passage, 40…Valve core drive part, 42…Stator, 43…Rotor, 44…Rotor shaft, 45…Connecting component, 50…Planetary gear mechanism, 51…Gearbox, 52…Sun gear, 53…Fixed gear ring, 54…Planetary gear, 55…Planetary gear carrier, 56…Output gear, L…Axis;

[0091] 1A, 1B… Electric valve, 20A, 20B… Supporting component, 21A… Valve core support, 211… First component, 211a… Spring support surface, 212… Second component, 212a… Cylindrical part, 212b… Flange part, 22B… Drive shaft support, 22f… Protrusion, 22g… Bearing surface, 23B… Rolling bearing, 23d… Upper track plate, 23e… Lower track plate, 23f… Ball, 25B… Drive shaft, 27B… Base, 27d… Flange part, 28A… Fixed wheel, 30A… Valve core, 32A… Internal thread body, 33A… Main body, 34A… Press-in frame, 34c… Cylindrical part, 34d… Flange part, 35A… Annular groove, 37A… Filter, 38A… Valve opening spring.

Claims

1. An electric valve comprising: a valve body having a valve chamber and a valve port; a valve core for opening and closing the valve port; and a support member supporting the valve core so as to be movable relative to the valve port, characterized in that, have: A drive shaft, which is configured along the forward and backward direction of the valve core, and has an external thread; A rolling bearing, which is held in the support member and supports the drive shaft so that it can rotate; A planetary gear mechanism, which is connected to the drive shaft; and A cylindrical internally threaded body, which is fixed to the valve core and screwed into the externally threaded portion. The support member supports the internally threaded body to restrict its rotation about an axis and to allow it to move axially. The support component has a valve core guide hole for the valve core to be configured. The internally threaded body has a transverse hole extending from the outer circumferential surface to the inner circumferential surface. The inner space of the internally threaded body and the transverse hole form a pressure equalization passage connecting the valve port to the back pressure chamber in the valve core guide hole, which serves as the space on the other end side of the valve core, when one end of the valve core is in contact with the valve seat of the valve port in the closed valve state. When the valve core is in the fully open state, furthest from the valve seat, the external thread portion enters the internal thread body until it closes the transverse hole.

2. The electric valve according to claim 1, characterized in that, The drive shaft has a base that is integrally and continuously disposed with the external threaded portion and connected to the output portion of the planetary gear mechanism. The rolling bearing is a radial ball bearing. The outer ring of the rolling bearing is held in place by the support member. The inner ring of the rolling bearing is held between the base and the nut that engages with the external thread.

3. The electric valve according to claim 1 or 2, characterized in that, The cross-section of the internally threaded body is polygonal. The support member has a partition that divides its inner space in the axial direction. The partition wall has a support hole for the internal threaded body to be fitted. The support hole has the same shape as the cross-section of the internal thread body.

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