Electric valve

Abstract

The invention provides an electrically operated valve which is provided with a force required for moving a valve body and has a short switching time of the state of the electrically operated valve. An electric valve (1) is provided with: a drive shaft (70) having a male thread (72c); a guide member (68) having a female thread (68c) into which the male thread (72c) is screwed; and a planetary gear mechanism (60) that decelerates the rotation of the rotor (51) and transmits the rotation to the drive shaft (70). When the lead of the male thread (72c) is set as L and the reduction ratio of the planetary gear mechanism (60) is set as K, the electrically operated valve (1) satisfies the following formulae (1) and (2): (1) 0.04 K < = L < = 0.10 K (2) 30 < = K < = 100.

Description

Technical Field

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

[0002] Patent document 1 discloses an example of a conventional electric valve. The electric valve of Patent document 1 includes a valve body, a valve core, a drive shaft, a guide member, a gear mechanism, and a stepping motor. The valve body includes a valve port. The valve core is pressed in a direction away from the valve port by a valve opening spring. The drive shaft includes an external thread. The valve port, the valve core, and the drive shaft are arranged on a straight line. The guide member includes an internal thread for screwing into the external thread of the drive shaft. The stepping motor includes a rotor and a stator. The rotation of the rotor is decelerated by the gear mechanism and transmitted to the drive shaft. When the drive shaft rotates, the drive shaft moves axially due to the action of the feed screw.

[0003] When the rotor rotates in a first direction, the drive shaft presses the valve core, causing the drive shaft to move the valve core toward the valve port. When the rotor rotates in a second direction, the drive shaft moves away from the valve port, causing the valve opening spring to move the valve core away from the valve port.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2018-173102

[0007] Electric valves are used, for example, to control the refrigerant flow rate in the refrigeration cycle system of an automotive air conditioner. Depending on the switching of the air conditioner's operating mode, the electric valve sometimes switches from a fully open state to a fully closed state, and from a fully closed state to a fully open state. Because the rotation of the rotor is decelerated by the gear mechanism, switching the state of the electric valve takes time. By reducing the reduction ratio of the gear mechanism, the movement speed of the valve core increases, and the switching time of the electric valve state can be shortened. However, when the reduction ratio of the gear mechanism is reduced, the force of the drive shaft used to move the valve core becomes smaller. As a result, the size of the valve opening is limited, and the Cv value of the electric valve decreases. Summary of the Invention

[0008] Problems to be solved by the invention

[0009] Therefore, an object of the present invention is to provide an electric valve that has a force required for moving a valve element and has a short switching time between states of the electric valve.

[0010] Means for solving problems

[0011] The inventors used multiple electric valves with different combinations of gear mechanism reduction ratios and drive shaft external thread pitches to conduct in-depth research on the relationship between the time to switch from a fully open state to a fully closed state (switching time) and the force (axial force) of the drive shaft used to move the valve core.

[0012] exist Figure 5 In the diagram, line A1 schematically shows the relationship between the reduction ratio, switching time, and axial force. The thickness of line A1 indicates the size of the reduction ratio. The larger the reduction ratio, the thicker the line A1. Figure 5 In the figure, line A2 schematically illustrates the relationship between pitch, switching time, and axial force. The thickness of line A2 indicates the pitch. The larger the pitch, the thicker line A2. The reduction ratio and pitch at the intersection of lines A1 and A2 represent the reduction ratio and pitch of the reference electric valve.

[0013] Line A1 shows the relationship between the switching time and the axial force when the reduction ratio is changed without changing the pitch in the standard electric valve. The larger the reduction ratio, the larger the switching time and the axial force.

[0014] Line A2 shows the relationship between the switching time and the axial force when only the pitch is changed without changing the reduction ratio in the standard electric valve. The larger the pitch, the smaller the switching time and the axial force.

[0015] exist Figure 5 In the figure, line A3 shows the relationship between switching time and axial force when the number of threads is changed without changing the reduction ratio or pitch in a standard electric valve. The greater the number of threads, the smaller the switching time and axial force. When the number of threads is n, the lead of the thread is n times the pitch.

[0016] The present inventors investigated the switching time and axial force in a plurality of combinations of reduction ratios and leads, and found a relationship between reduction ratios and leads that can provide appropriate switching time and axial force, thereby completing the present invention.

[0017] In order to achieve the above-mentioned purpose, the electric valve of the present invention comprises: a valve body, which has a valve port; a valve core, which is opposite to the valve port; a motor, which has a rotor; a drive shaft, which has an external thread; a guide member, which has an internal thread for screwing the external thread; and a gear mechanism, which reduces the speed of the rotation of the rotor and transmits it to the drive shaft. The electric valve is characterized in that when the drive shaft rotates, the drive shaft moves in a direction close to or away from the valve port, and the valve core moves relative to the valve port. When the lead of the external thread is set to L and the reduction ratio of the gear mechanism is set to K, the following equations (1) and (2) are satisfied:

[0018] (1)0.04K≤L≤0.10K

[0019] (2)30≤K≤100.

[0020] In the present invention, it is preferred that when the outer diameter of the external thread is set to d, the bottom diameter of the external thread is set to d1, and the pitch of the external thread is set to p, the following formulas (3) and (4) are satisfied:

[0021] (3) (When d≤35 / 8)

[0022] (4) (where d≥35 / 8).

[0023] In the present invention, preferably, the external thread and the internal thread are multi-start threads.

[0024] Effects of the Invention

[0025] According to the present invention, when the lead of the external thread of the drive shaft is L and the reduction ratio of the gear mechanism is K, the electric valve satisfies the above equations (1) and (2). This provides the electric valve with the force required to move the valve core and further shortens the switching time of the electric valve. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a cross-sectional view of an electric valve according to an embodiment of the present invention.

[0027] Figure 2 This is an enlarged cross-sectional view of a portion of the electric valve.

[0028] Figure 3 This is a graph showing the relationship between the time for switching the state of the electric valve (switching time) and the force (axial force) of the drive shaft of the electric valve for moving the valve element.

[0029] Figure 4 This is a graph showing the relationship between the outer diameter of the drive shaft and the pitch of the drive shaft.

[0030] Figure 5 The diagram schematically shows the relationship among the reduction ratio, switching time, and axial force of the gear mechanism, and the relationship among the pitch of the external thread of the drive shaft, switching time, and axial force. DETAILED DESCRIPTION

[0031] Below, refer to Figures 1 to 4 An electric valve according to one embodiment of the present invention will be described. The electric valve according to this embodiment is used to control the flow rate of refrigerant in a refrigeration cycle system of an automobile air conditioner.

[0032] Figure 1 It is a cross-sectional view of an electric valve according to an embodiment of the present invention. Figure 2 This is a cross-sectional view of a part of the electric valve (mainly the valve core and the drive mechanism). Figure 2 In the figure, the description of the stator unit is omitted. Figure 3 This is a graph showing the relationship between the time for switching the state of the electric valve (switching time) and the force (axial force) of the drive shaft of the electric valve for moving the valve element. Figure 4This is a graph showing the relationship between the outer diameter of the drive shaft and the pitch of the drive shaft.

[0033] like Figure 1 、 Figure 2 As shown, the electric valve 1 of this embodiment includes a valve body 10 , a holder 20 , a valve element support member 25 , a container 30 , a valve element 40 , a drive mechanism 50 , and a stator unit 80 .

[0034] The valve body 10 has a rectangular parallelepiped shape. The valve body 10 has a valve chamber 13 and a valve port 14 connected to the valve chamber 13. The valve port 14 is surrounded by a valve seat 15 in the valve chamber 13. The valve body 10 has a first passage 17 and a second passage 18. The first passage 17 extends from the right side 10a of the valve body 10 to the valve port 14. The first passage 17 is connected to the valve chamber 13 via the valve port 14. The second passage 18 extends from the left side 10b of the valve body 10 to the valve chamber 13. The valve body 10 has a mounting hole 19. The mounting hole 19 is arranged on the upper surface 10c of the valve body 10. An internal thread is provided on the inner circumferential surface of the mounting hole 19. The mounting hole 19 is connected to the valve chamber 13. An upward-facing annular plane 19a is provided at the connection portion between the mounting hole 19 and the valve chamber 13.

[0035] The retainer 20 has a cylindrical shape. An external thread is provided on the lower portion of the outer peripheral surface of the retainer 20. The external thread of the retainer 20 is screwed into the internal thread of the mounting hole 19 of the valve body 10. The retainer 20 is mounted on the valve body 10 by the threaded structure.

[0036] The valve core support member 25 has a cylindrical shape. The valve core support member 25 is arranged between the valve body 10 and the retaining member 20 in the mounting hole 19. The lower portion of the valve core support member 25 is pressed into the valve chamber 13. An annular plane 25a facing downward is provided on the outer peripheral surface of the valve core support member 25. The annular plane 25a is in contact with the annular plane 19a of the valve body 10. The valve core support member 25 has a support hole 26 extending in the up-down direction. The valve core 40 is inserted into the support hole 26. The valve core support member 25 supports the valve core 40 so that it can move in the up-down direction (direction of the axis M).

[0037] The container 30 has a cylindrical shape. The upper end of the container 30 is closed, and the lower end is open. The lower end of the container 30 is joined to the outer periphery of a connecting member 35 in the shape of a circular ring. The upper portion 20a of the retainer 20 is disposed inside the connecting member 35. The inner periphery of the connecting member 35 is joined to the retainer 20. The container 30 is fixed to the valve body 10 via the connecting member 35 and the retainer 20.

[0038] The valve element 40 includes a valve stem 41 , a valve portion 42 , a spring receiving portion 43 , and a ball receiving portion 44 .

[0039] The valve stem 41 has a cylindrical shape and is disposed in the support hole 26 of the valve element support member 25. The valve stem 41 is supported by the valve element support member 25 so as to be movable in the vertical direction.

[0040] The valve portion 42 has an annular shape. The valve portion 42 is formed integrally with the valve stem 41 and is disposed at the lower end of the valve stem 41. The valve portion 42 protrudes radially outward from the outer peripheral surface of the valve stem 41. The valve portion 42 and the valve port 14 face each other in the vertical direction.

[0041] The spring receiving portion 43 includes a main body 43a and a flange 43b. The main body 43a has a cylindrical shape. The outer diameter of the main body 43a is the same as the outer diameter of the valve stem 41. The main body 43a includes a first hole 43a1 and a second hole 43a2. The first hole 43a1 is arranged on the lower end surface of the main body 43a. The upper end of the valve stem 41 is arranged in the first hole 43a1. The main body 43a is coaxially engaged with the valve stem 41. The second hole 43a2 is arranged on the upper end surface of the main body 43a. The flange 43b has a circular ring shape. The flange 43b is formed integrally with the main body 43a and is arranged on the upper end of the main body 43a. The flange 43b protrudes radially outward from the outer circumferential surface of the main body 43a.

[0042] The ball receiving portion 44 includes a circular flat portion 44a and a protrusion 44b connected to the lower surface of the flat portion 44a. A conical recess is provided on the upper surface of the flat portion 44a. The protrusion 44b engages with the second hole 43a2 of the main body 43a of the spring receiving portion 43. The protrusion 44b is fixed to the main body 43a of the spring receiving portion 43.

[0043] By advancing and retracting the valve portion 42 relative to the valve port 14, the valve element 40 changes the opening area of ​​the valve port 14 steplessly (including substantially steplessly). The minimum opening area of ​​the valve port 14 is 0. Alternatively, the minimum opening area may be greater than 0. When the opening area of ​​the valve port 14 is at its minimum value, the electric valve 1 is fully closed.

[0044] The drive mechanism 50 moves the valve element 40 in the vertical direction and includes a rotor 51 , a permanent magnet 55 , a magnetic shielding member 56 , a planetary gear mechanism 60 , a guide member 68 , a drive shaft 70 , a ball 76 , and a valve opening spring 77 .

[0045] The rotor 51 has a cylindrical shape. The outer diameter of the rotor 51 is smaller than the inner diameter of the container 30. The rotor 51 is rotatably disposed inside the container 30. A circular connecting plate 52 is attached to the upper end of the rotor 51. The connecting plate 52 blocks the upper end of the rotor 51. A 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 rotor shaft 53 rotates together with the rotor 51.

[0046] The rotor 51 has a plurality of north poles and a plurality of south poles. The plurality of north poles and the plurality of south poles extend in the vertical direction and are alternately arranged along the circumferential direction on the outer peripheral surface of the rotor 51.

[0047] The permanent magnet 55 is disposed above the rotor 51 inside the container 30. The permanent magnet 55 has a disk shape and is fixed to the upper end of the rotor shaft 53. The permanent magnet 55 is coaxially disposed with the rotor 51 and rotates together with the rotor 51.

[0048] The permanent magnet 55 has one north pole and one south pole. One north pole is arranged on one portion of the permanent magnet 55 divided by the diameter, and one south pole is arranged on the other portion.

[0049] The magnetic shield 56 has a disc shape. It is positioned between the rotor 51 and the permanent magnets 55. It is made of a soft magnetic material with relatively high magnetic permeability, such as ferrosilicon. It is fixed to the rotor shaft 53. It absorbs the magnetic flux generated by the rotor 51. It also prevents the magnetic field generated by the permanent magnets 55 from being deformed by the magnetic field generated by the rotor 51.

[0050] The planetary gear mechanism 60 is a 3K-type planetary gear mechanism. Alternatively, the planetary gear mechanism 60 may be a 2K-H-type planetary gear mechanism. The electric valve 1 may employ a gear mechanism that functions as a speed reducer instead of the planetary gear mechanism 60. The planetary gear mechanism 60 is disposed inside the rotor 51. It includes 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.

[0051] The gear box 61 has a cylindrical shape. The lower end portion of the gear box 61 is coaxially engaged with the upper portion 20 a of the holder 20 . The fixed ring gear 62 is an internal gear. The fixed ring gear 62 is fixed to the upper end portion of the gear box 61 .

[0052] The sun gear 63 is formed integrally with the coupling plate 52 and is arranged coaxially with the lower surface of the coupling plate 52. The rotor shaft 53 passes through the sun gear 63. The sun gear 63 rotates together with the rotor 51 and the coupling plate 52.

[0053] The gear carrier 65 has a disc shape. The rotor shaft 53 passes through the center of the gear carrier 65. The gear carrier 65 is rotatable about the rotor shaft 53. The gear carrier 65 rotatably supports the plurality of planetary gears 64. The plurality of planetary gears 64 are arranged between the fixed ring gear 62 and the sun gear 63.

[0054] The output gear 66 has a bottomed cylindrical shape. It is an internal gear. A plurality of planetary gears 64 are positioned between the output gear 66 and the sun gear 63. The output shaft 67 has a cylindrical shape. The upper portion of the output shaft 67 is press-fitted into a hole provided in the bottom of the output gear 66. A slit 67a extending vertically is provided in the lower portion of the output shaft 67. The output shaft 67 rotates together with the output gear 66.

[0055] The rotation of the sun gear 63 is decelerated by the fixed ring gear 62, the plurality of planetary gears 64, the carrier 65, and the output gear 66, and then transmitted to the output shaft 67. The planetary gear mechanism 60 is a speed reducer that decelerates the rotation of the rotor 51. The reduction ratio is obtained by dividing the angular velocity of the sun gear 63 by the angular velocity of the output shaft 67. The angular velocity of the sun gear 63 is the angular velocity of the rotor 51.

[0056] The guide member 68 has a cylindrical shape. It is positioned inside the upper portion 20a of the retainer 20. The guide member 68 is fixed to the valve body 10 via the retainer 20. The guide member 68 has an internal thread 68c. The internal thread 68c is located at the lower portion of the inner circumference of the guide member 68. The output shaft 67 is positioned inside the guide member 68. The guide member 68 rotatably supports the output shaft 67.

[0057] The drive shaft 70 is formed by, for example, cutting a cylindrical metal rod and includes a first portion 71 and a second portion 72 .

[0058] The first portion 71 has a rectangular, flat plate shape. The thickness of the first portion 71 is slightly smaller than the width of the slit 67a of the output shaft 67. The first portion 71 is disposed vertically and movably inside the slit 67a of the output shaft 67. The slit 67a and the first portion 71 transmit the rotation of the output shaft 67 to the drive shaft 70, and the drive shaft 70 can be moved vertically relative to the output shaft 67.

[0059] The second portion 72 has a cylindrical shape. It is integrally formed with the first portion 71 and connected to the lower end of the first portion 71. The second portion 72 has an external thread 72c. The external thread 72c is disposed on the outer circumferential surface of the second portion 72. The external thread 72c screws into the internal thread 68c of the guide member 68. A conical recess is provided on the lower end surface of the second portion 72, and the ball 76 engages with the recess. The ball 76 slidably contacts the recess of the flat plate portion 44a of the ball receiving portion 44.

[0060] The internal thread 68c of the guide member 68 and the external thread 72c of the drive shaft 70 are single-start threads. The internal thread 68c and the external thread 72c may also be multi-start threads. By making the internal thread 68c and the external thread 72c multi-start threads, the lead can be increased without changing the pitch.

[0061] The valve opening spring 77 is disposed between the valve element support member 25 and the flange portion 43b of the valve element 40. The valve opening spring 77 is a compression coil spring and presses the valve element 40 upward (in a direction away from the valve port 14).

[0062] The stator unit 80 includes a housing 81, a stator 82, and a base plate 83. The housing 81 is made of synthetic resin and has a box shape. The housing 81 houses the stator 82 and the base plate 83. The stator 82 and the base plate 83 are screwed to the housing 81.

[0063] The stator 82 has a cylindrical shape. The container 30 is arranged inside the stator 82. The stator 82 and the rotor 51 constitute a stepping motor 88. In addition, the electric valve 1 may include another type of motor instead of the stepping motor 88.

[0064] Electronic components, including an angle sensor 84, are mounted on the substrate 83. Angle sensor 84 is a magnetic angle sensor. Angle sensor 84 is mounted on the lower surface of substrate 83. Angle sensor 84 is positioned above container 30. Angle sensor 84 faces the permanent magnet 55 in the vertical direction, with container 30 interposed between them. Angle sensor 84 detects the direction and magnitude of the magnetic field passing through it. The electrical signal output by angle sensor 84 can be used to determine the rotational angle of the permanent magnet 55.

[0065] In the electric valve 1, the center axes of the valve port 14, the retaining member 20, the valve core support member 25 (support hole 26), the container 30, the valve core 40, the rotor 51, the connecting plate 52, the rotor shaft 53, the permanent magnet 55, the output shaft 67, the guide member 68, the drive shaft 70, the ball 76, and the stator 82 are consistent with the axis M.

[0066] Next, the operation of the electric valve 1 will be described.

[0067] In the electric valve 1, current is supplied to the stator 82, causing the rotor 51 to rotate 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, the feed screw, formed by the external thread 72c of the drive shaft 70 and the internal thread 68c of the guide member 68, moves the drive shaft 70 downward, approaching the valve port 14. The drive shaft 70 presses the valve core 40 downward, causing it to move downward and reducing the opening area of ​​the valve port 14. When the valve core 40 contacts the valve seat 15, closing the valve port 14, the electric valve 1 is fully closed.

[0068] In the electric valve 1, current is supplied to the stator 82, causing the rotor 51 to rotate in the second direction. The rotation of the rotor 51 is decelerated by the planetary gear mechanism 60 and transmitted to the drive shaft 70. As the drive shaft 70 rotates, the feed screw, formed by the external thread 72c of the drive shaft 70 and the internal thread 68c of the guide member 68, moves the drive shaft 70 upward, away from the valve port 14. The valve opening spring 77 presses the valve core 40 upward, causing the valve core 40 to move upward, increasing the opening area of ​​the valve port 14. When the valve core 40 is furthest away from the valve port 14, the electric valve 1 is fully open. When the electric valve 1 is fully open, the opening area of ​​the valve port 14 is at its maximum.

[0069] Next, the switching time, which is the time required to switch the electric valve 1 from the fully open state to the fully closed state (or vice versa), and the axial force, which is the force of the drive shaft 70 for moving the valve element 40 , will be examined.

[0070] In the electric valve 1, when the movement amount of the valve core 40 from the fully open state to the fully closed state is set to Z, the number of poles of the stepping motor is set to N, the speed of the pulse signal of the stepping motor is set to V, the excitation method (number of divisions) of the stepping motor is set to γ, the reduction ratio of the planetary gear mechanism 60 is set to K, and the lead of the external thread 72c of the drive shaft 70 is set to L, the switching time T is expressed by the following formula (a).

[0071] (a)T={(Z×N) / (γ×V)}×(K / L)

[0072] In the electric valve 1, the axial force is related to the torque input to the drive shaft 70 and the lead angle of the external thread 72c. The torque is related to the reduction ratio K, and the lead angle is related to the lead L. The number of divisions is 1 for a full step and 1 / 2 for a half step.

[0073] Therefore, the switching time and the axial force are related to the reduction ratio K and the lead L.

[0074] The present inventors measured the switching time and axial force in a plurality of electric valves 1 having different reduction ratios K of the planetary gear mechanism 60 and lead L of the external thread 72c of the drive shaft 70. Figure 3 The external thread 72c is a single-start thread, so the lead and pitch are the same.

[0075] Figure 3 Graph showing the relationship between switching time and axial force. The unit of switching time is "s" and the unit of axial force is "N".

[0076] Point a1 corresponds to the measured value of the electric valve 1 in which the reduction ratio K is 30 and the lead L of the external thread 72 c is 0.12K.

[0077] Point a2 corresponds to the measured value of the electric valve 1 in which the reduction ratio K is 30 and the lead L of the external thread 72 c is 0.10K.

[0078] Point a3 corresponds to the measured value of the electric valve 1 in which the reduction ratio K is 30 and the lead L of the external thread 72 c is 0.067K.

[0079] Point a4 corresponds to the measured value of the electric valve 1 in which the reduction ratio K is 30 and the lead L of the external thread 72 c is 0.05K.

[0080] Point a5 corresponds to the measured value of the electric valve 1 in which the reduction ratio K is 30 and the lead L of the external thread 72 c is 0.04K.

[0081] Point a6 corresponds to the measured value of the electric valve 1 in which the reduction ratio K is 30 and the lead L of the external thread 72 c is 0.03K.

[0082] A line K30 passes through points a1 to a6 and indicates the relationship between the switching time and the axial force when the lead L is changed in the electric valve 1 having a reduction ratio K of 30.

[0083] Point b1 corresponds to the measured value of the electric valve 1 in which the reduction ratio K is 100 and the lead L of the external thread 72 c is 0.12K.

[0084] Point b2 corresponds to the measured value of the electric valve 1 in which the reduction ratio K is 100 and the lead L of the external thread 72 c is 0.10K.

[0085] Point b3 corresponds to the measured value of the electric valve 1 in which the reduction ratio K is 100 and the lead L of the external thread 72 c is 0.067K.

[0086] Point b4 corresponds to the measured value of the electric valve 1 in which the reduction ratio K is 100 and the lead L of the external thread 72 c is 0.05K.

[0087] Point b5 corresponds to the measured value of the electric valve 1 in which the reduction ratio K is 100 and the lead L of the external thread 72 c is 0.04K.

[0088] Point b6 corresponds to the measured value of the electric valve 1 in which the reduction ratio K is 100 and the lead L of the external thread 72 c is 0.03K.

[0089] A line K100 passes through points b1 to b6 and indicates the relationship between the switching time and the axial force when the lead L is changed in the electric valve 1 having a reduction ratio K of 100.

[0090] In automobile air conditioners, it is required to switch the operating mode faster. Therefore, the electric valve 1 is required to have the required axial force and shorten the switching time. Figure 3 In the figure, line D1 corresponds to the switching time of 8s, and line D2 corresponds to the lower limit of the axial force (140N). Figure 3The electric valve 1 having the measured values ​​(points a2 to a5 and points b1 to b5) included in the region to the left of the line D1 and above the line D2 has the required axial force and can further shorten the switching time.

[0091] Therefore, the electric valve 1 can have a required axial force and further shorten the switching time by satisfying the following equations (1) and (2).

[0092] (1)0.04K≤L≤0.10K

[0093] (2)30≤K≤100

[0094] In addition, the electric valve 1 preferably satisfies the following equations (1A) and (2). Figure 3 In the figure, line D3 corresponds to the switching time 5s. Figure 3 The electric valve 1 having the measured values ​​(points a2, a3, and points b1 to b3) included in the region to the left of the line D3 and above the line D2 has the required axial force and can further shorten the switching time.

[0095] (1A)0.067K≤L≤0.10K

[0096] (2)30≤K≤100

[0097] Figure 4 Graph showing the relationship between the outer diameter and the pitch of the external thread 72c of the drive shaft 70. The unit of the outer diameter is "mm", and the unit of the pitch is "mm".

[0098] The outer diameter of the external thread 72c (standard dimension of the external thread outer diameter: JIS B0205-4) is set to d, the bottom diameter of the external thread 72c (standard dimension of the diameter of the external thread bottom: JIS B0205-4) is set to d1, the pitch of the external thread 72c is set to p, and the height of the top angle of the external thread 72c is set to H.

[0099] The relationship between the height H of the apex angle and the pitch p, and the relationship between the height H of the apex angle, the outer diameter d, and the bottom diameter d1 are expressed by the following formulas (i) and (ii).

[0100] (i)

[0101] (ii) d1 = d - 2 × (5 / 8) × H

[0102] From these equations, the following equation (iii) representing the pitch p is obtained.

[0103] (iii)

[0104] In the drive shaft 70, increasing the pitch p of the external thread 72c reduces the base diameter d1. As base diameter d1 decreases, the rigidity of the drive shaft 70 decreases. To ensure the required rigidity of the drive shaft 70, the base diameter d1 is determined by the following equations (iv) and (v) based on practical conditions.

[0105] (iv) d1 ≥ 2.5 (where d ≤ 35 / 8)

[0106] (v) d / d1 ≤ 1.75 (where d ≥ 35 / 8)

[0107] The following formula (3) is obtained from formula (iii) and formula (iv).

[0108] (3) (When d≤35 / 8)

[0109] The following formula (4) is obtained from formula (iii) and formula (v).

[0110] (4) (When d≥35 / 8)

[0111] exist Figure 4 In the equation (3), line J3 corresponds to equation (4), line J4 corresponds to equation (4), and line D4 corresponds to an outer diameter of 35 / 8 (4.375) mm. When the outer diameter of the external thread 72c is 35 / 8 mm or less, the pitch p is set to be less than line J3. When the outer diameter of the external thread 72c is 35 / 8 mm or greater, the pitch p is set to be less than line J4. This allows the drive shaft 70 to have the required rigidity.

[0112] As described above, the electric valve 1 includes: a valve body 10 having a valve port 14; a valve core 40 facing the valve port 14; a stepping motor 88 having a rotor 51; a drive shaft 70 having an external thread 72c; a guide member 68 having an internal thread 68c into which the external thread 72c is threaded; and a planetary gear mechanism 60 that reduces the speed of the rotor 51 and transmits the speed to the drive shaft 70. When the drive shaft 70 rotates, it moves toward or away from the valve port 14, causing the valve core 40 to move relative to the valve port 14. Furthermore, when the lead of the external thread 72c is L and the reduction ratio of the planetary gear mechanism 60 is K, the above equations (1) and (2) are satisfied. Thus, the electric valve 1 has the required axial force and can further shorten the switching time of the electric valve 1.

[0113] When the outer diameter of the external thread 72c is d, the bottom diameter of the external thread 72c is d1, and the pitch of the external thread 72c is p, the above equations (3) and (4) are satisfied.

[0114] In this specification, terms indicating shapes such as "cylindrical," "column," and "rectangular parallelepiped" are also used to refer to components or parts of components that substantially have the shape of the term. For example, "a cylindrical component" includes both a cylindrical component and a substantially cylindrical component.

[0115] While the embodiments of the present invention have been described above, the present invention is not limited to the structures of the embodiments. Embodiments in which those skilled in the art appropriately add, delete, or design changes components to the aforementioned embodiments, or embodiments in which the features of the embodiments are appropriately combined, are encompassed within the scope of the present invention as long as they do not violate the gist of the present invention.

[0116] Description of Reference Numerals

[0117] 1…Electric Valve, 10…Valve Body, 10a…Right Side, 10b…Left Side, 10c…Top Surface, 13…Valve Chamber, 14…Valve Port, 15…Valve Seat, 17…First Passage, 18…Second Passage, 19…Mounting Hole, 19a…Annular Plane, 20…Retainer, 20a…Top, 25…Valve Support Member, 25a…Annular Plane, 26…Support Hole, 30…Container, 35…Connecting Member, 40…Valve Body, 41…Valve Stem, 42…Valve Portion, 43…Spring Receiver, 43a…Main Body, 43a1…First Hole, 43a2…Second Hole, 43b…Flange, 44…Ball Receiver, 44a…Flat Plate, 44b…Convex Part, 50…Drive mechanism, 51…Rotor, 52…Connecting plate, 53…Rotor shaft, 55…Permanent magnet, 56…Magnetic shielding member, 60…Planetary gear mechanism, 61…Gear box, 62…Stationary ring gear, 63…Sun gear, 64…Planetary gear, 65…Gear carrier, 66…Output gear, 67…Output shaft, 67a…Slit, 68…Guide member, 68c…Internal thread, 70…Drive shaft, 71…First part, 72…Second part, 72c…External thread, 76…Ball, 77…Valve opening spring, 80…Stator unit, 81…Casing, 82…Stator, 83…Substrate, 84…Angle sensor, 88…Stepping motor, M…Axis.

Claims

1. An electric valve comprising: a valve body having a valve port; a valve core facing the valve port; a motor having a rotor; a drive shaft having an external thread; a guide member having an internal thread for threading with the external thread; and a gear mechanism for reducing the speed of rotation of the rotor and transmitting the speed of rotation to the drive shaft, wherein: When the drive shaft rotates, the drive shaft moves in a direction close to or away from the valve port, and the valve core moves relative to the valve port. When the lead of the external thread is L and the reduction ratio of the gear mechanism is K, the following equations (1) and (2) are satisfied: (1)0.04K≤L≤0.10K (2)30≤K≤100。 2. The electric valve according to claim 1, characterized in that When the outer diameter of the external thread is set to d, the bottom diameter of the external thread is set to d1, and the pitch of the external thread is set to p, the following equations (3) and (4) are satisfied: (3) When d ≤ 35 / 8, p ≤ {4 × (2 × d - 5)} / (5 × √3) (4) When d ≥ 35 / 8, p ≤ (24 × d) / (35 × √3).

3. The electric valve according to claim 1 or 2, characterized in that: The external thread and the internal thread are multi-start threads.

Images