Motor-operated valve

Abstract

To provide a motor operated value having a short switching time for changing the state of the motor operated valve while having the power required for moving a valve body.SOLUTION: A motor operated valve 1 comprises: a drive shaft 70 having male threads 72c; a guide member 68 having female threads 68c with which the male threads 72c engage; and a planetary gear mechanism 60 that reduces the speed of rotation of a rotor 51 and transmits the speed to the drive shaft 70. The motor operated valve 1 satisfies formula (1) and formula (2), where L is the lead of the male threads 72c and K is the reduction ratio of the planetary gear mechanism 60. (1) 0.04K≤L≤0.10K and (2) 30≤K≤100.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a motor-operated valve. [Background technology]

[0002] Patent Document 1 discloses an example of a conventional motor-operated valve. The motor-operated valve in Patent Document 1 has a valve body, a valve element, a drive shaft, a guide member, a gear mechanism, and a stepping motor. The valve body has a valve port. The valve element is pushed away from the valve port by a valve-opening spring. The drive shaft has a male thread. The valve port, valve element, and drive shaft are arranged on a straight line. The guide member has a female thread that engages with the male thread of the drive shaft. The stepping motor has a rotor and a stator. The rotation of the rotor is reduced in speed by the gear mechanism and transmitted to the drive shaft. When the drive shaft rotates, it moves axially by a screw feed action.

[0003] When the rotor rotates in the first direction, the drive shaft pushes the valve disc, causing it to move closer to the valve orifice. When the rotor rotates in the second direction, the drive shaft moves away from the valve orifice, causing the valve opening spring to move the valve disc away from the valve orifice. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-173102 Summary of the Invention [Problem to be solved by the invention]

[0005] Motor-operated valves are used, for example, to control the flow rate of refrigerant in the refrigeration cycle system of an automobile air conditioner. Depending on the operating mode of the air conditioner, the motor-operated valve may switch from a fully open state to a fully closed state, or vice versa. Because the rotation of the rotor is slowed by a gear mechanism, it takes time for the motor-operated valve to switch states. By reducing the gear mechanism's reduction ratio, the valve disc's movement speed increases, shortening the switching time. However, reducing the gear mechanism's reduction ratio also reduces the force required by the drive shaft to move the valve disc. This limits the size of the valve orifice, lowering the motor-operated valve's Cv value.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a motor-operated valve that has the force required to move the valve element and that has a short time required to switch the state of the motor-operated valve. [Means for solving the problem]

[0007] The inventors have thoroughly investigated the relationship between the time it takes to switch from a fully open state to a fully closed state (switching time) and the force (axial force) applied by the drive shaft to move the valve body for multiple electric valves with different gear mechanism reduction ratios and drive shaft male thread pitches.

[0008] In Figure 5, line A1 schematically shows the relationship between the reduction ratio, switching time, and axial force. The thickness of line A1 represents the magnitude of the reduction ratio. In Figure 5, line A2 schematically shows the relationship between the pitch, switching time, and axial force. The thickness of line A2 represents the magnitude of the pitch. In Figure 5, the reduction ratio and pitch at the intersection of line A1 and line A2 are the reduction ratio and pitch of a standard motor-operated valve.

[0009] Line A1 shows the switching time and axial force when only the reduction ratio is changed without changing the pitch for a standard motor-operated valve. The switching time and axial force increase as the reduction ratio increases.

[0010] Line A2 shows the changeover time and axial force when only the pitch is changed without changing the reduction ratio for the standard motor-operated valve. The changeover time and axial force decrease as the pitch increases.

[0011] In Figure 5, line A3 shows the changeover time and axial force when the number of threads on the male screw is changed without changing the reduction ratio or pitch for a standard motor-operated valve. The greater the number of threads, the smaller the changeover time and axial force. When the number of threads on the male screw is n, the lead of the male screw is n times the pitch.

[0012] The inventors investigated the switching time and axial force for multiple combinations of reduction ratio and lead, and discovered a relationship between reduction ratio and lead that allows for obtaining an appropriate switching time and axial force, thereby arriving at the present invention.

[0013] In order to achieve the above object, the motor-operated valve of the present invention is an electric valve comprising: a valve body having a valve port; a valve element facing the valve port; a motor having a rotor; a drive shaft having an external thread; a guide member having an internal thread into which the external thread is threaded; and a gear mechanism that decelerates the rotation of the rotor and transmits it to the drive shaft, wherein when the drive shaft rotates, the drive shaft moves in a direction toward or away from the valve port, and the valve element moves relative to the valve port, and when the lead of the external thread is L and the reduction ratio of the gear mechanism is K, the motor-operated valve satisfies the following equations (1) and (2): (1) 0.04K≦L≦0.10K (2) 30≦K≦100

[0014] In the present invention, when the outer diameter of the male thread is d, the root diameter of the male thread is d1, and the pitch of the male thread is p, it is preferable that the following formulas (3) and (4) are satisfied. (3) p≦{4×(2×d-5)} / (5×√3) (when d≦35 / 8) (4) p≦(24×d) / (35×√3) (when d≧35 / 8)

[0015] In the present invention, it is preferable that the male thread and the female thread are multiple-start threads. [Effects of the Invention]

[0016] According to the present invention, when the lead of the male screw of the drive shaft is L and the reduction ratio of the gear mechanism is K, the motor-operated valve satisfies the above formulas (1) and (2). As a result, the motor-operated valve has the force necessary to move the valve disc while shortening the time it takes to switch the state of the motor-operated valve. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a cross-sectional view of a motor-operated valve according to an embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged cross-sectional view of a portion of the motor-operated valve. [Figure 3] 1 is a graph showing the relationship between the time (switching time) for switching the state of the motor-operated valve and the force (axial force) for the drive shaft of the motor-operated valve to move the valve element. [Figure 4] 10 is a graph showing the relationship between the outer diameter of a drive shaft and the pitch of the drive shaft. [Figure 5] 10 is a diagram schematically illustrating the relationship between the reduction ratio of the gear mechanism, the switching time, and the axial force, and the relationship between the pitch of the male screw of the drive shaft, the switching time, and the axial force. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0018] An electric valve according to one embodiment of the present invention will now be described with reference to Figures 1 to 4. The electric valve according to this embodiment is used to control the flow rate of refrigerant in a refrigeration cycle system of an automotive air conditioner.

[0019] Fig. 1 is a cross-sectional view of a motor-operated valve according to an embodiment of the present invention. Fig. 2 is an enlarged cross-sectional view of a portion of the motor-operated valve (mainly the valve body and drive mechanism). The stator unit is not shown in Fig. 2. Fig. 3 is a graph showing the relationship between the time it takes for the state of the motor-operated valve to switch (switching time) and the force (axial force) applied by the drive shaft of the motor-operated valve to move the valve body. Fig. 4 is a graph showing the relationship between the outer diameter of the drive shaft and the pitch of the drive shaft.

[0020] As shown in Figures 1 and 2, the electric valve 1 of this embodiment has a valve body 10, a holder 20, a valve body support member 25, a can 30, a valve body 40, a drive mechanism 50, and a stator unit 80.

[0021] 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 surface 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 surface 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 located on the top 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 flat surface 19a is provided at the connection point between the mounting hole 19 and the valve chamber 13.

[0022] The holder 20 has a cylindrical shape. A male thread is provided on the lower part of the outer circumferential surface of the holder 20. The male thread of the holder 20 is screwed into the female thread of the mounting hole 19 of the valve body 10. The holder 20 is attached to the valve body 10 with a screw structure.

[0023] The valve element support member 25 has a cylindrical shape. The valve element support member 25 is disposed between the valve body 10 and the holder 20 in the mounting hole 19. The lower part of the valve element support member 25 is press-fitted into the valve chamber 13. The outer peripheral surface of the valve element support member 25 is provided with an annular flat surface 25a facing downward. . ring The shaped flat surface 25a is in contact with the annular flat surface 19a of the valve body 10. The valve element support member 25 has a support hole 26 extending in the vertical direction. The valve element 40 is inserted into the support hole 26. The valve element support member 25 supports the valve element 40 so that it can move in the vertical direction (direction of the axis M).

[0024] The can 30 has a cylindrical shape. The upper end of the can 30 is closed and the lower end is open. The lower end of the can 30 is joined to the outer periphery of a connecting member 35 in the shape of an annular disk. The upper part 20a of the holder 20 is disposed inside the connecting member 35. The inner periphery of the connecting member 35 is joined to the holder 20. The can 30 is fixed to the valve body 10 via the connecting member 35 and the holder 20.

[0025] The valve body 40 has a stem 41, a valve portion 42, a spring receiving portion 43, and a ball receiving portion 44.

[0026] The stem 41 has a cylindrical shape and is disposed in the support hole 26 of the valve body support member 25. The stem 41 is supported by the valve body support member 25 so as to be movable in the up and down direction.

[0027] The valve portion 42 has an annular shape. The valve portion 42 is formed integrally with the stem 41 and is disposed at the lower end of the stem 41. The valve portion 42 protrudes radially outward from the outer circumferential surface of the stem 41. The valve portion 42 faces the valve port 14 in the up-down direction.

[0028] The spring bearing portion 43 has a main body portion 43a and a flange portion 43b. The main body portion 43a has a cylindrical shape. The outer diameter of the main body portion 43a is the same as the outer diameter of the stem 41. The main body portion 43a has a first hole 43a1 and a second hole 43a2. The first hole 43a1 is located on the lower end surface of the main body portion 43a. The upper end of the stem 41 is located in the first hole 43a1. The main body portion 43a is coaxially joined to the stem 41. The second hole 43a2 is located on the upper end surface of the main body portion 43a. The flange portion 43b has an annular shape. The flange portion 43b is formed integrally with the main body portion 43a and is located at the upper end of the main body portion 43a. The flange portion 43b protrudes radially outward from the outer circumferential surface of the main body portion 43a.

[0029] The ball receiving portion 44 has a circular flat plate portion 44a and a protruding portion 44b connected to the lower surface of the flat plate portion 44a. A conical recess is provided on the upper surface of the flat plate portion 44a. The protruding portion 44b is fitted into a second hole 43a2 of the main body portion 43a of the spring receiving portion 43. The protruding portion 44b is fixed to the main body portion 43a of the spring receiving portion 43.

[0030] The valve element 40 changes the opening area of ​​the valve orifice 14 in a stepless manner (including substantially stepless manner) as the valve portion 42 moves forward and backward relative to the valve orifice 14. The minimum value of the opening area of ​​the valve orifice 14 is 0. However, the minimum value may be greater than 0. When the opening area of ​​the valve orifice 14 is at its minimum value, the motor-operated valve 1 is in a fully closed state.

[0031] The drive mechanism 50 moves the valve element 40 in the vertical direction. The drive mechanism 50 has 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.

[0032] 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 disposed 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. 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.

[0033] The rotor 51 has a plurality of north poles and a plurality of south poles that extend in the vertical direction and are arranged alternately in the circumferential direction on the outer circumferential surface of the rotor 51.

[0034] The permanent magnet 55 is disposed above the rotor 51 inside the can 30. The permanent magnet 55 has a disk shape. The permanent magnet 55 is fixed to the upper end of the rotor shaft 53. The permanent magnet 55 is disposed coaxially with the rotor 51 and rotates together with the rotor 51.

[0035] The permanent magnet 55 has one N pole and one S pole. One N pole is located on one portion of the permanent magnet 55 defined by a diameter, and one S pole is located on the other portion.

[0036] The magnetic shielding member 56 has a disk shape. The magnetic shielding member 56 is disposed between the rotor 51 and the permanent magnet 55. The magnetic shielding member 56 is made of a soft magnetic material with a relatively high magnetic permeability, such as silicon iron. The magnetic shielding member 56 is fixed to the rotor shaft 53. The magnetic shielding member 56 absorbs the magnetic flux generated by the rotor 51. The magnetic shielding member 56 prevents the magnetic field generated by the rotor 51 from distorting the magnetic field generated by the permanent magnet 55.

[0037] The planetary gear mechanism 60 is a 3K type planetary gear mechanism. The planetary gear mechanism 60 may be, for example, a 2K-H type planetary gear mechanism. The motor-operated valve 1 may employ a gear mechanism that functions as a reducer instead of the planetary gear mechanism 60. The planetary gear mechanism 60 is disposed 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.

[0038] The gear case 61 has a cylindrical shape. The lower end of the gear case 61 is coaxially joined to the upper part 20a of the holder 20. The fixed ring gear 62 is an internal gear. The fixed ring gear 62 is fixed to the upper end of the gear case 61.

[0039] The sun gear 63 is formed integrally with the connecting plate 52 and is arranged coaxially on the lower surface of the connecting plate 52. The rotor shaft 53 passes through the sun gear 63. The sun gear 63 rotates together with the rotor 51 and connecting plate 52.

[0040] The carrier 65 has a disk shape. The rotor shaft 53 passes through the center of the carrier 65. The carrier 65 is rotatable around the rotor shaft 53. The carrier 65 rotatably supports a plurality of planetary gears 64. The plurality of planetary gears 64 are disposed between the fixed ring gear 62 and the sun gear 63.

[0041] The output gear 66 has a cylindrical shape with a bottom. The output gear 66 is an internal gear. A plurality of planetary gears 64 are arranged between the output gear 66 and the sun gear 63. 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 bottom part of the output gear 66. The lower part of the output shaft 67 has a slit 67a extending in the vertical direction. The output shaft 67 rotates together with the output gear 66.

[0042] The rotation of the sun gear 63 is reduced by the fixed ring gear 62, multiple planetary gears 64, carrier 65, and output gear 66, and is then transmitted to the output shaft 67. The planetary gear mechanism 60 is a reducer that reduces the rotation of the rotor 51. The reduction ratio is the value 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.

[0043] 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 via the holder 20. The guide member 68 has a female thread 68c. The female thread 68c is disposed on the lower portion of the inner circumferential surface of the guide member 68. The output shaft 67 is disposed inside the guide member 68. The guide member 68 rotatably supports the output shaft 67.

[0044] The drive shaft 70 is formed, for example, by cutting a cylindrical metal rod. The drive shaft 70 has a first portion 71 and a second portion 72.

[0045] 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 inside the slit 67a of the output shaft 67 so as to be movable up and down. The slit 67a and the first portion 71 transmit the rotation of the output shaft 67 to the drive shaft 70 while allowing the drive shaft 70 to move up and down relative to the output shaft 67.

[0046] The second portion 72 has a cylindrical shape. The second portion 72 is formed integrally with the first portion 71 and is connected to the lower end of the first portion 71. The second portion 72 has a male thread 72c. The male thread 72c is disposed on the outer peripheral surface of the second portion 72. The male thread 72c is threadedly engaged with the female thread 68c of the guide member 68. A conical recess is provided on the lower end surface of the second portion 72, and a ball 76 is joined to the recess. The ball 76 slidably contacts the recess in the flat plate portion 44a of the ball receiving portion 44.

[0047] The female thread 68c of the guide member 68 and the male thread 72c of the drive shaft 70 are single-start threads. The female thread 68c and the male thread 72c may be multiple-start threads. By making the female thread 68c and the male thread 72c multiple-start threads, the lead can be increased without changing the pitch.

[0048] The valve-opening spring 77 is disposed between the valve body support member 25 and the flange portion 43b 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 (in the direction away from the valve port 14).

[0049] The stator unit 80 has a case 81, a stator 82, and a substrate 83. The case 81 is made of synthetic resin. The case 81 has a box shape. The case 81 houses the stator 82 and the substrate 83. The stator 82 and the substrate 83 are fixed to the case 81 with screws.

[0050] The stator 82 has a cylindrical shape. The can 30 is disposed inside the stator 82. The stator 82 and the rotor 51 constitute a stepping motor 88. Note that the motor-operated valve 1 may have another type of motor instead of the stepping motor 88.

[0051] The substrate 83 is mounted with electronic components including an angle sensor 84. The angle sensor 84 is a magnetic angle sensor. The angle sensor 84 is mounted on the underside of the substrate 83. The angle sensor 84 is disposed above the can 30. The angle sensor 84 faces the permanent magnet 55 in the vertical direction across the can 30. The angle sensor 84 detects the direction and magnitude of the magnetic field passing through the angle sensor 84. The rotation angle of the permanent magnet 55 can be obtained based on the electrical signal output by the angle sensor 84.

[0052] In the electric valve 1, the valve port 14, holder 20, valve body support member 25 (support hole 26), can 30, valve body 40, rotor 51, connecting plate 52, rotor shaft 53, permanent magnet 55, output shaft 67, guide member 68, drive shaft 70, ball 76, and stator 82 each have a central axis that coincides with the axis M.

[0053] Next, the operation of the motor-operated valve 1 will be described.

[0054] In the motor-operated valve 1, current is supplied to the stator 82, causing the rotor 51 to rotate in a first direction. The rotation of the rotor 51 is reduced in speed by the planetary gear mechanism 60 and transmitted to the drive shaft 70. When the drive shaft 70 rotates, the screw feed action between the male thread 72c of the drive shaft 70 and the female thread 68c of the guide member 68 causes the drive shaft 70 to move downward and approach the valve orifice 14. The drive shaft 70 presses the valve disc 40 downward, causing the valve disc 40 to move downward and reducing the opening area of ​​the valve orifice 14. When the valve disc 40 comes into contact with the valve seat 15 and closes the valve orifice 14, the motor-operated valve 1 is in a fully closed state.

[0055] In the motor-operated 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 reduced in speed by the planetary gear mechanism 60 and transmitted to the drive shaft 70. When the drive shaft 70 rotates, the screw feed action between the male thread 72c of the drive shaft 70 and the female thread 68c of the guide member 68 causes the drive shaft 70 to move upward and away from the valve orifice 14. The valve disc 40 is pushed upward by the valve-opening spring 77, causing the valve disc 40 to move upward and increasing the opening area of ​​the valve orifice 14. When the valve disc 40 is farthest from the valve orifice 14, the motor-operated valve 1 is in a fully open state. When the motor-operated valve 1 is in a fully open state, the opening area of ​​the valve orifice 14 is at its largest.

[0056] We will consider the switching time, which is the time it takes for the motor-operated valve 1 to switch from a fully open state to a fully closed state (or from a fully closed state to a fully open state), and the axial force, which is the force used by the drive shaft 70 to move the valve element 40.

[0057] In the electric valve 1, when the movement amount of the valve body 40 from the fully open state to the fully closed state is Z, the number of poles of the stepping motor is N, the speed of the pulse signal of the stepping motor is V, the excitation method of the stepping motor is γ, the reduction ratio of the planetary gear mechanism 60 is K, and the lead of the male thread 72c of the drive shaft 70 is L, the switching time T is expressed by the following equation (a). (a) T = {(Z × N) / (γ × V)} × (K / L)

[0058] In the motor-operated valve 1, the axial force is related to the torque input to the drive shaft 70 and the lead angle of the male thread 72c. The torque is related to the reduction ratio K, and the lead angle is related to the lead L.

[0059] Therefore, the switching time and the axial force are related to the reduction ratio K and the lead L.

[0060] The inventors measured the switching time and axial force for a number of motor-operated valves 1 with different reduction ratios K of the planetary gear mechanism 60 and different leads L of the male thread 72c of the drive shaft 70. The measurement results are shown in Figure 3. Because the male thread 72c is a single-start thread, the lead is the same as the pitch.

[0061] Figure 3 is a graph showing the relationship between the switching time and the axial force. The unit of the switching time is "s" and the unit of the axial force is "N".

[0062] Point a1 is the measured value of the motor-operated valve 1 in which the reduction ratio K is 30 and the lead L of the male thread 72c is 0.12K. Point a2 is the measured value of the motor-operated valve 1 in which the reduction ratio K is 30 and the lead L of the male thread 72c is 0.10K. Point a3 is the measured value of the motor-operated valve 1 in which the reduction ratio K is 30 and the lead L of the male thread 72c is 0.067K. Point a4 is the measured value of the motor-operated valve 1 in which the reduction ratio K is 30 and the lead L of the male thread 72c is 0.05K. Point a5 is the measured value of the motor-operated valve 1 in which the reduction ratio K is 30 and the lead L of the male thread 72c is 0.04K. Point a6 is the measured value of the motor-operated valve 1 in which the reduction ratio K is 30 and the lead L of the male thread 72c is 0.03K. Line K30 is a line that passes through points a1 to a6, and shows the relationship between the switching time and the axial force when the lead L is changed in the motor-operated valve 1 with a reduction ratio K of 30.

[0063] Point b1 is a measurement value of the motor-operated valve 1 in which the reduction ratio K is 100 and the lead L of the male thread 72c is 0.12K. Point b2 is the measured value of the motor-operated valve 1 in which the reduction ratio K is 100 and the lead L of the male thread 72c is 0.10K. Point b3 is the measured value of the motor-operated valve 1 in which the reduction ratio K is 100 and the lead L of the male thread 72c is 0.067K. Point b4 is the measured value of the motor-operated valve 1 in which the reduction ratio K is 100 and the lead L of the male thread 72c is 0.05K. Point b5 is the measured value of the motor-operated valve 1 in which the reduction ratio K is 100 and the lead L of the male thread 72c is 0.04K. Point b6 is the measured value of the motor-operated valve 1 in which the reduction ratio K is 100 and the lead L of the male thread 72c is 0.03K. Line K100 is a line that passes through points b1 to b6, and shows the relationship between the switching time and the axial force when the lead L is changed in the motor-operated valve 1 with a reduction ratio K of 100.

[0064] There is a demand for faster switching of operating modes in automotive air conditioners. To achieve this, motor-operated valves 1 are required to have a short switching time while maintaining the necessary axial force. In FIG. 3, line D1 corresponds to the switching time of 8 seconds, and line D2 corresponds to the lower limit of the axial force (140 N). In FIG. 3, motor-operated valves 1 having measured values ​​(points a2 to a5, points b1 to b5) included in the area to the left of line D1 and above line D2 can achieve a short switching time while maintaining the necessary axial force.

[0065] Therefore, by satisfying the following formulas (1) and (2), the motor-operated valve 1 can shorten the switching time while providing the necessary axial force. (1) 0.04K≦L≦0.10K (2) 30≦K≦100

[0066] Furthermore, it is preferable that the motor-operated valve 1 satisfy the following formulas (1A) and (2). In Figure 3, line D3 corresponds to the switching time of 5 seconds. In Figure 3, the motor-operated valve 1 having measurement values ​​included in the area to the left of line D3 and above line D2 (points a2, a3, points b1 to b3) can further shorten the switching time while maintaining the necessary axial force. (1A) 0.067K≦L≦0.10K (2) 30≦K≦100

[0067] 4 is a graph showing the relationship between the outer diameter and the pitch of the male thread 72c of the drive shaft 70. The unit of the outer diameter is "mm", and the unit of the pitch is "mm".

[0068] The outer diameter of the male thread 72c (standard dimension of the outer diameter of a male thread: JIS B0205-4) is d, the root diameter of the male thread 72c (standard dimension of the root diameter of a male thread: JIS B0205-4) is d1, the pitch of the male thread 72c is p, and the height of the crest of the male thread 72c is H.

[0069] The relationship between the peak height H and the pitch p, and the relationship between the peak height H, the outer diameter d, and the root diameter d1 are shown in the following formulas (i) and (ii). (i) H=(√3×p) / 2 (ii) d1=d-2×(5 / 8)×H

[0070] From these equations, we obtain the following equation (iii) which shows the pitch p. (iii) p = {8 × (d - d1)} / (5 × √3)

[0071] Increasing the pitch p of the male thread 72c of the drive shaft 70 reduces the root diameter d1. A smaller root diameter d1 reduces the rigidity of the drive shaft 70. To ensure that the drive shaft 70 has the required rigidity, the root diameter d1 is defined by the following formulas (iv) and (v) based on past performance. (iv) d1≧2.5 (when d≦35 / 8) (v) d / d1≦1.75 (when d≧35 / 8)

[0072] From equations (iii) and (iv), the following equation (3) is obtained: (3) p≦{4×(2×d-5)} / (5×√3) (when d≦35 / 8)

[0073] From equations (iii) and (v), the following equation (4) is obtained. (4) p≦(24×d) / (35×√3) (when d≧35 / 8)

[0074] 4, line J3 corresponds to equation (3), 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 male thread 72c is 35 / 8 mm or less, pitch p is set to be equal to or less than line J3, and when the outer diameter of the male thread 72c is 35 / 8 mm or more, pitch p is set to be equal to or less than line J4, thereby providing the drive shaft 70 with the required rigidity.

[0075] As described above, the motor-operated valve 1 includes the valve body 10 having the valve port 14, the valve element 40 facing the valve port 14, the stepping motor 88 having the rotor 51, the drive shaft 70 having the male thread 72c, the guide member 68 having the female thread 68c into which the male thread 72c is threaded, and the planetary gear mechanism 60 that decelerates the rotation of the rotor 51 and transmits it to the drive shaft 70. When the drive shaft 70 rotates, the drive shaft 70 moves toward or away from the valve port 14, thereby moving the valve element 40 relative to the valve port 14. When the lead of the male thread 72c is L and the reduction ratio of the planetary gear mechanism 60 is K, the above formulas (1) and (2) are satisfied. As a result, the motor-operated valve 1 can provide the necessary axial force while shortening the time it takes to switch the state of the motor-operated valve 1.

[0076] Furthermore, when the outer diameter of the male thread 72c is d, the root diameter of the male thread 72c is d1, and the pitch of the male thread 72c is p, the above formulas (3) and (4) are satisfied. In this way, the drive shaft 70 can be provided with the required rigidity.

[0077] In this specification, terms indicating shapes such as "cylinder," "column," and "rectangular parallelepiped" are also used to refer to members or portions of members that substantially have the shape of the term. For example, a "cylindrical member" includes both cylindrical members and substantially cylindrical members.

[0078] Although the embodiments of the present invention have been described above, the present invention is not limited to the configurations of the embodiments. Those skilled in the art may appropriately add, delete, or modify components of the above-described embodiments, or appropriately combine features of the embodiments, as long as they do not deviate from the spirit of the present invention. [Explanation of symbols]

[0079] 1...motor-operated valve, 10...valve body, 10a...right side surface, 10b...left side surface, 10c...upper surface, 13...valve chamber, 14...valve port, 15...valve seat, 17...first passage, 18...second passage, 19...mounting hole, 19a...annular flat surface, 20...holder, 20a...upper portion, 25...valve body support member, 25a...annular flat surface, 26...support hole, 30...can, 35...connecting member, 40...valve body, 41...stem, 42...valve portion, 43...spring receiving portion, 43a...main body portion, 43a1...first hole, 43a2...second hole, 43b...flange portion, 44...ball receiving portion, 44a...flat plate portion, 44b...convex portion, 50...drive mechanism, 51... Rotor, 52...connecting plate, 53...rotor shaft, 55...permanent magnet, 56...magnetic shielding member, 60...planetary gear mechanism, 61...gear case, 62...fixed ring gear, 63...sun gear, 64...planetary gear, 65...carrier, 66...output gear, 67...output shaft, 67a...slit, 68...guiding member, 68c...female thread, 70...drive shaft, 71...first part, 72...second part, 72c...male thread, 76...ball, 77...valve opening spring, 80...stator unit, 81...case, 82...stator, 83...board, 84...angle sensor, 88...stepping motor, M...axis

Claims

1. An electrically operated valve comprising: a valve body having a valve port; a valve element facing the valve port; a motor having a rotor; a drive shaft having a male screw; a guide member having a female screw into which the male screw is screwed; and a gear mechanism that reduces the speed of rotation of the rotor and transmits it to the drive shaft, When the drive shaft is rotated, the drive shaft moves in a direction toward or away from the valve orifice, and the valve element moves relative to the valve orifice. The male thread and the female thread are multiple-start threads, An electrically operated valve characterized in that, when the lead of the male screw 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. An electrically operated valve comprising: a valve body having a valve port; a valve element facing the valve port; a stepping motor having a rotor; a drive shaft having a male screw; a guide member having a female screw into which the male screw is screwed; and a gear mechanism that reduces the speed of rotation of the rotor and transmits it to the drive shaft, When the drive shaft is rotated, the drive shaft moves in a direction toward or away from the valve orifice, and the valve element moves relative to the valve orifice. An electric valve characterized by satisfying the following formulas (1A), (2A), and (a2), where L is the lead of the male screw, K is the reduction ratio of the gear mechanism, Z is the amount of movement of the valve disc from a fully open state in which the valve disc is farthest from the valve port to a fully closed state in which the valve port is closed, N is the number of poles of the stepping motor, V is the speed of a pulse signal of the stepping motor, and γ is the excitation method of the stepping motor. (1A) 0.067K≦L≦0.10K (2A) K=30 (a2) {(Z×N) / (γ×V)}×(K / L)<5

3. 3. The motor-operated valve according to claim 1, wherein the following formulas (3) and (4) are satisfied, where d is the outer diameter of the male thread and p is the pitch of the male thread. (3) p≦{4×(2×d−5)} / (5×√3) (when d≦35 / 8) (4) p≦(24×d) / (35×√3) (when d≧35 / 8)

4. 3. The motor-operated valve according to claim 2, wherein the external thread and the internal thread are single-start threads.

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