Electric valve control device and electric valve device

Abstract

The present invention provides an electric valve control device and an electric valve device that can maintain a state in which the valve body is properly pressed against the valve seat after the power to the electric valve is turned off. [Solution] The electric valve 5 comprises a valve body 10 on which a valve seat 14 is provided, a valve element 40 facing the valve seat 14, a stepping motor 88 having a rotor 51 and a stator 80, and a drive mechanism 55 that moves the valve element 40 in accordance with the rotation of the rotor 51. The electric valve control device 90 controls the electric valve 5. When the electric valve control device 90 presses the valve element 40 against the valve seat 14, it rotates the rotor 51 with a torque corresponding to the difference between the valve body temperature and a reference temperature related to the temperature of the valve body 10.

Description

Technical Field

[0001] The present invention relates to an electric valve control device, and an electric valve device having the electric valve control device and an electric valve.

Background Art

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

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the electric valve is operating, the members constituting the electric valve change in size (expand / contract) according to the temperature of the fluid inside the valve body. And after the power supply of the electric valve is turned off, the temperature of these members approaches the temperature of the space (ambient temperature) where the electric valve is disposed, and these members become the size corresponding to the ambient temperature.

[0005] The lower end of the valve seat is defined as the reference position. The upper end of the threaded portion of the female screw of the guide member is defined as the first position. The upper end of the threaded portion of the male screw of the drive shaft is defined as the second position. The vertical length from the reference position to the first position is defined as the valve body length L1. The vertical length from the reference position to the second position is defined as the valve element length L2. The valve body length L1 increases with the expansion of the body member, holder, and guide member, and decreases with the contraction. The valve element length L2 increases with the expansion of the valve seat, valve element, and drive shaft, and decreases with the contraction.

[0006] Aluminum alloys and brass have relatively high coefficients of thermal expansion, while stainless steel has a relatively low coefficient of thermal expansion. Therefore, if the member contracts after the power to the electric valve is turned off while the valve body is pressed against the valve seat, the valve body length L1 becomes shorter than the valve body length L2, causing the guide member to move the drive shaft toward the valve seat. This increases the force pressing the valve body against the valve seat, which may cause the valve body to become immobile. Alternatively, if the member expands after the power to the electric valve is turned off while the valve body is pressed against the valve seat, the valve body length L1 becomes longer than the valve body length L2, causing the guide member to move the drive shaft toward the valve seat. This reduces the force pressing the valve body against the valve seat, which may create a gap between the valve body and the valve seat.

[0007] Therefore, the present invention aims to provide an electric valve control device and an electric valve device that can maintain a state in which the valve body is properly pressed against the valve seat after the power to the electric valve is turned off. [Means for solving the problem]

[0008] To achieve the above objective, an electric valve control device according to one aspect of the present invention is an electric valve control device that controls an electric valve having a valve body provided with a valve seat, a valve element facing the valve seat, a motor having a rotor and a stator, and a drive mechanism for moving the valve element in accordance with the rotation of the rotor, characterized in that when the electric valve control device presses the valve element against the valve seat, it rotates the rotor with a torque corresponding to the difference between the temperature of the valve body and a reference temperature relating to the temperature of the valve body.

[0009] In the present invention, the electric valve has a configuration in which, when the temperature of the valve body is low while the valve body is pressed against the valve seat, the force pressing the valve body against the valve seat increases, and when the temperature of the valve body is high while the valve body is pressed against the valve seat, the force pressing the valve body against the valve seat decreases. If the torque used when the temperature of the valve body is the same as the reference temperature is defined as the reference torque, it is preferable that the electric valve control device sets the torque to a first torque which is smaller than the reference torque when the temperature of the valve body is higher than the reference temperature, and sets the torque to a second torque which is larger than the reference torque when the temperature of the valve body is lower than the reference temperature.

[0010] In the present invention, the electric valve has a configuration in which, when the temperature of the valve body is low while the valve body is pressed against the valve seat, the force pressing the valve body against the valve seat decreases, and when the temperature of the valve body is high while the valve body is pressed against the valve seat, the force pressing the valve body against the valve seat increases. If the torque used when the temperature of the valve body is the same as the reference temperature is defined as the reference torque, it is preferable that the electric valve control device sets the torque to a second torque which is greater than the reference torque when the temperature of the valve body is higher than the reference temperature, and sets the torque to a first torque which is less than the reference torque when the temperature of the valve body is lower than the reference temperature.

[0011] In the present invention, it is preferable that the reference temperature is the temperature of the space in which the electric valve is located.

[0012] In the present invention, it is preferable that the reference temperature is the temperature of the valve body immediately after the power to the electric valve is turned on.

[0013] To achieve the above objective, another embodiment of the present invention provides an electric valve device comprising the electric valve control device and the electric valve. [Effects of the Invention]

[0014] According to the present invention, when the electric valve control device presses the valve body against the valve seat, it rotates the rotor with a torque corresponding to the difference between the valve body temperature and a reference temperature. The valve body temperature is related to the temperature of the fluid inside the valve body when the electric valve is operating, and approaches the temperature of the space in which the electric valve is located after the electric valve is turned off. Therefore, by setting the reference temperature to the temperature that the valve body temperature is expected to approach after the electric valve is turned off, it is possible to estimate the increase or decrease in the force pressing the valve body against the valve seat based on the difference between the valve body temperature and the reference temperature. By rotating the rotor with a torque corresponding to the difference, the valve body can be pressed against the valve seat with a force that takes into account the change in size of the components constituting the electric valve. Thus, the state in which the valve body is properly pressed against the valve seat can be maintained after the electric valve is turned off. [Brief explanation of the drawing]

[0015] [Figure 1] This is a cross-sectional view of an electric valve device according to one embodiment of the present invention. [Figure 2] This is an enlarged cross-sectional view of the valve body, drive shaft, and surrounding area of ​​an electric valve device. [Figure 3] This diagram schematically shows the rotor and stator of an electric valve device. [Figure 4] This is a cross-sectional view illustrating the length of the valve body and the length of the valve element. [Figure 5] This is another cross-sectional view illustrating the length of the valve body and the length of the valve element. [Figure 6]It is a diagram showing the connection relationships of the rotor, stator, motor driver, first temperature sensor, second temperature sensor, and computer of the electric valve device. [Figure 7] It is a diagram showing an example of the relationship between a pulse and the signal input to the motor driver. [Figure 8] It is a diagram showing an example of the waveform of the current flowing through the stator. [Figure 9] It is a flowchart showing an example of the valve opening degree change process executed by the electric valve control device of the electric valve device. [Figure 10] It is a flowchart showing an example of the valve opening degree change process executed by the electric valve control device (continuation of FIG. 9). [Figure 11] It is a flowchart showing an example of the initialization process executed by the electric valve control device.

Embodiments for Carrying Out the Invention

[0016] Hereinafter, an electric valve device according to an embodiment of the present invention will be described with reference to FIGS. 1 to 11. The electric valve device according to this embodiment is used to control the flow rate of a refrigerant (fluid) in a refrigeration cycle system.

[0017] The electric valve device 1 according to this embodiment has an electric valve 5 and an electric valve control device (hereinafter referred to as "control device 90").

[0018] The electric valve 5 has a valve body assembly 7 and a stator unit 8.

[0019] The valve body assembly 7 has a valve body 10, a valve body support member 25, a cam 30, a connection plate 35, a valve element 40, a rotor assembly 50, and a drive mechanism 55.

[0020] The valve body 10 has a body member 11 and a holder 20.

[0021] The main body member 11 has a rectangular parallelepiped shape. The main body member 11 has a valve chamber 13. A valve seat 14 is attached to the main body member 11. The valve seat 14 has a cylindrical shape and is located inside the main body member 11. The valve seat 14 has a valve port 15 that is connected to the valve chamber 13.

[0022] The main body member 11 has a first passage 17 and a second passage 18. The first passage 17 extends from the right side surface 11a of the main body member 11 to the valve opening 15. The first passage 17 is connected to the valve chamber 13 via the valve opening 15. The second passage 18 extends from the left side surface 11b of the main body member 11 to the valve chamber 13.

[0023] The main body member 11 has a mounting hole 19. The mounting hole 19 is provided on the upper surface 11c of the main body member 11. The inner circumferential surface of the mounting hole 19 is provided with an internal thread. The mounting hole 19 is connected to the valve chamber 13. An annular retaining surface 11d facing upward is provided at the connection point between the mounting hole 19 and the valve chamber 13.

[0024] The holder 20 has a cylindrical shape. The outer surface of the holder 20 is provided with male threads. The male threads of the holder 20 are screwed into the female threads of the mounting holes 19 of the valve body 10. The holder 20 is attached to the valve body 10 by a screw structure. The inner space of the holder 20 is connected to the valve chamber 13, and the refrigerant in the valve chamber 13 is introduced through it.

[0025] The valve support member 25 has a cylindrical shape. The outer circumferential surface of the valve support member 25 is provided with a contact surface 25d, which is an annular plane facing downwards. The valve support member 25 is held by the valve body 10. Specifically, the lower part of the valve support member 25 is press-fitted into the valve chamber 13, and the contact surface 25d is in contact with the holding surface 11d of the valve body 10. The valve support member 25 separates the valve chamber 13 from the mounting hole 19. A holder 20 is positioned above the valve support member 25. The valve support member 25 supports the valve body 40 so that it can move vertically (in the direction of the axis M).

[0026] The valve body support member 25 has a support hole 26 and a spring hole 27 that is connected coaxially with the support hole 26. The support hole 26 is closer to the valve seat 14 than the spring hole 27. The spring hole 27 is provided on the upper surface of the valve body support member 25. The diameter of the spring hole 27 is larger than the diameter of the support hole 26. A spring receiving surface 25e, which is an annular plane facing upward, is provided at the connection point between the support hole 26 and the spring hole 27.

[0027] The can 30 has a cylindrical shape. The can 30 is closed at the top and open at the bottom. The connecting plate 35 has an annular shape. The upper part 20a of the holder 20 is positioned inside the connecting plate 35. The inner periphery of the connecting plate 35 is joined to the upper part 20a of the holder 20. The lower end of the can 30 is joined to the outer periphery of the connecting plate 35.

[0028] The valve body 40 has a body portion 41, a head portion 42, and a receiving member 43.

[0029] The body 41 has a stem 41a and a valve portion 41b. The stem 41a has a cylindrical shape. The diameter of the stem 41a is the same as the diameter of the support hole 26 of the valve body support member 25. The stem 41a is positioned in the support hole 26 and is supported by the valve body support member 25 so as to be movable in the vertical direction. The valve portion 41b has an annular shape. The outer diameter of the valve portion 41b is larger than the diameter of the stem 41a. The inner periphery of the valve portion 41b is integrally connected to the lower end of the stem 41a. The valve portion 41b faces the valve seat 14 in the vertical direction. When the valve body 40 moves downward, the valve portion 41b comes into contact with the upper end of the valve seat 14.

[0030] The head portion 42 is connected to the upper end of the stem 41a. The head portion 42 has a cylindrical portion 42a and a flange portion 42b. The diameter of the cylindrical portion 42a is the same as the diameter of the stem 41a. The cylindrical portion 42a has a first hole 42a1 and a second hole 42a2. The first hole 42a1 is provided on the lower end surface of the cylindrical portion 42a. The upper end of the stem 41a is positioned in the first hole 42a1. The cylindrical portion 42a is coaxially joined to the upper end of the stem 41a. The second hole 42a2 is provided on the upper end surface of the cylindrical portion 42a. The flange portion 42b has an annular shape. The outer diameter of the flange portion 42b is larger than the diameter of the cylindrical portion 42a. The inner periphery of the flange portion 42b is integrally connected to the upper end of the cylindrical portion 42a.

[0031] The receiving member 43 has a circular flat plate portion and a protrusion integrally connected to the lower surface of the flat plate portion. A conical recess is provided on the upper surface of the flat plate portion. The protrusion is fitted into the second hole 42a2 of the head portion 42. The receiving member 43 is attached to the head portion 42.

[0032] When the valve portion 41b of the valve body 40 contacts the valve seat 14, the valve opening 15 closes, and the opening degree of the valve opening 15 becomes 0 (closed state). When the valve body 40 moves away from the valve seat 14, the valve opening 15 opens. When the valve body 40 is furthest away from the valve seat 14, the opening degree of the valve opening 15 becomes maximum (fully open state).

[0033] The rotor assembly 50 includes a rotor 51, a connecting plate 52, and a rotor shaft 53.

[0034] The rotor 51 has a cylindrical shape. The outer diameter of the rotor 51 is smaller than the inner diameter of the can 30. The rotor 51 is rotatably positioned inside the can 30. A circular connecting plate 52 is joined to the upper end of the rotor 51. The connecting plate 52 closes the upper end of the rotor 51. The rotor shaft 53 passes through the center of the connecting plate 52. The rotor 51 is connected to the rotor shaft 53 via the connecting plate 52. The connecting plate 52 and the rotor shaft 53 rotate together with the rotor 51. The rotor 51 is a magnetic rotor.

[0035] The rotor 51 has multiple north poles and multiple south poles. The multiple north poles and multiple south poles are arranged alternately in the circumferential direction on the outer surface of the rotor 51. The multiple north poles and multiple south poles extend in the vertical direction.

[0036] The drive mechanism 55 moves the valve body 40 vertically in accordance with the rotation of the rotor 51. The drive mechanism 55 includes a planetary gear mechanism 60, a guide member 68, a drive shaft 70, and a valve opening spring 77.

[0037] The planetary gear mechanism 60 is a 3K type planetary gear mechanism. The planetary gear mechanism 60 may also be, for example, a 2K-H type planetary gear mechanism. The electric valve 5 may use a gear mechanism that functions as a reduction gear instead of the planetary gear mechanism 60. The planetary gear mechanism 60 is located inside the rotor 51. The planetary gear mechanism 60 has a gear case 61, a fixed ring gear 62, a sun gear 63, a plurality of planetary gears 64, a carrier 65, an output gear 66, and an output shaft 67. The planetary gear mechanism 60 has the same configuration as that of the electric valve in Patent Document 1. The planetary gear mechanism 60 is a reduction gear that reduces the rotation of the rotor 51.

[0038] The sun gear 63 is integrally formed with the connecting plate 52 and is coaxially positioned on the lower surface of the connecting plate 52. The sun gear 63 rotates together with the rotor 51 and the connecting plate 52. The rotation of the sun gear 63 is reduced by a fixed ring gear 62, a plurality of planetary gears 64, a carrier 65, and an output gear 66, and transmitted to the output shaft 67. The output shaft 67 has a cylindrical shape. The upper part of the output shaft 67 is press-fitted into a hole provided in the output gear 66. The lower part of the output shaft 67 is provided with a slit 67a that extends in the vertical direction. The output shaft 67 rotates together with the output gear 66.

[0039] The guide member 68 has a cylindrical shape. The guide member 68 is located inside the upper part 20a of the holder 20. The guide member 68 is fixed to the valve body 10. The guide member 68 has a female thread 68t. The female thread 68t is located at the lower part of the inner circumferential surface of the guide member 68. The output shaft 67 is located inside the guide member 68. The guide member 68 rotatably supports the output shaft 67.

[0040] The drive shaft 70 has a first part 71, a second part 72, and a ball 73. The drive shaft 70 is rotated around its central axis by the output shaft 67.

[0041] The first part 71 has a rectangular flat plate shape. The thickness of the first part 71 is the same as the width of the slit 67a of the output shaft 67. The first part 71 is positioned to be vertically movable inside the slit 67a of the output shaft 67. The slit 67a and the first part 71 transmit the rotation of the output shaft 67 to the drive shaft 70, while also allowing the drive shaft 70 to move vertically relative to the output shaft 67.

[0042] The second part 72 has a cylindrical shape. The second part 72 is integrally connected to the lower end of the first part 71. The first part 71 and the second part 72 are integrally formed, for example, by machining a cylindrical metal rod. The second part 72 has a male thread 72t. The male thread 72t is located on the outer circumferential surface of the second part 72. The male thread 72t is screwed into the female thread 68t of the guide member 68.

[0043] The ball 73 is joined to the lower end surface of the second portion 72. The ball 73 slidably contacts the recess in the flat portion of the receiving member 43. That is, the drive shaft 70 is in contact with the valve body 40. The drive shaft 70 may be integrally connected to the head 42 of the valve body 40. Alternatively, the drive shaft 70 may be connected to the head 42 of the valve body 40 so that the valve body 40 moves vertically together with the drive shaft 70.

[0044] The valve opening spring 77 is positioned between the spring receiving surface 25e of the valve body support member 25 and the flange portion 42b of the valve body 40. The valve opening spring 77 is a compression coil spring. The valve opening spring 77 pushes the valve body 40 upward (away from the valve seat 14).

[0045] The stator unit 8 comprises a stator 80 and a housing 85.

[0046] The stator 80 has a cylindrical shape. The stator 80 includes an A-phase stack 81 and a B-phase stack 82.

[0047] The A-phase stack 81 has a plurality of claw-pole type pole teeth 81a, 81b and an A-phase coil 81c. The pole teeth 81a and 81b are arranged alternately at equal angular intervals in the circumferential direction. When current is supplied to the A-phase coil 81c, the pole teeth 81a and 81b become magnetic poles of opposite polarity to each other.

[0048] The B-phase stack 82 has multiple claw-pole type pole teeth 82a, 82b and a B-phase coil 82c. The pole teeth 82a and 82b are arranged alternately at equal angular intervals in the circumferential direction. When current is supplied to the B-phase coil 82c, the pole teeth 82a and 82b become magnetic poles of opposite polarity. The B-phase stack 82 has the same configuration as the A-phase stack 81. The A-phase stack 81 is placed on top of the B-phase stack 82.

[0049] A cann 30 is positioned inside the stator 80. A rotor 51 is positioned inside the cann 30. The magnetic poles of the rotor 51 and the pole teeth 81a, 81b, 82a, and 82b of the stator 80 face each other radially, with the cann 30 in between. The rotor 51 and stator 80 are a stepping motor 88. Note that the electric valve 5 may have a different type of motor instead of the stepping motor 88.

[0050] The housing 85 is made of synthetic resin. The housing 85 houses the stator 80.

[0051] In the electric valve 5, the valve seat 14, holder 20, valve body support member 25, can 30, valve body 40, rotor 51, connecting plate 52, rotor shaft 53, output shaft 67, guide member 68, drive shaft 70, and stator 80 each have their central axes coincide with axis M. The direction of axis M is the axial direction.

[0052] In this embodiment, the main body member 11 is made of aluminum alloy, and the guide member 68 is made of brass. The valve seat 14, holder 20, body 41, head 42, receiving member 43, and drive shaft 70 are made of stainless steel. The head 42 may be made of zinc alloy or aluminum alloy.

[0053] Coefficient of linear thermal expansion of aluminum alloy (22 × 10 -6 The coefficient of linear thermal expansion of brass (20 × 10) is given by the coefficient of linear thermal expansion of brass (20 × 10) / °C. -6 The coefficient of thermal expansion of brass is greater than that of stainless steel (16 × 10). -6 The coefficient of linear expansion of zinc alloy is greater than (27 × 10°C). -6 The coefficient of thermal expansion ( / °C) is greater than that of the aluminum alloy.

[0054] The main body component 11, valve seat 14, holder 20, valve body 40 (body 41, head 42, receiving component 43), guide member 68, and drive shaft 70 are in contact with the refrigerant inside the valve body 10, and the temperature of these components becomes the same as the temperature of the refrigerant. Therefore, when the electric valve device 1 (electric valve 5) is operating, these components change size (expand / contract) according to the temperature of the refrigerant inside the valve body 10. After the power to the electric valve device 1 is turned off, the flow of refrigerant stops, and the temperature of the refrigerant and these components approaches the temperature of the space SP in which the electric valve device 1 is located, and eventually becomes the same as the temperature of space SP. Therefore, these components become the size corresponding to the temperature of space SP.

[0055] The lower end of the valve seat 14 is defined as the reference position P0. The upper end of the threaded portion of the female thread 68t of the guide member 68 (the end furthest from the valve seat 14) is defined as the first position P1. The upper end of the threaded portion of the male thread 72t of the drive shaft 70 (the end furthest from the valve seat 14) is defined as the second position P2. The vertical length from the reference position P0 to the first position P1 is defined as the valve body side length L1. The vertical length from the reference position P0 to the second position P2 is defined as the valve element side length L2. The valve body side length L1 increases in accordance with the expansion of the main body member 11, holder 20, and guide member 68, and decreases in accordance with the contraction. The valve element side length L2 increases in accordance with the expansion of the valve seat 14, body 41, head 42, receiving member 43, and drive shaft 70, and decreases in accordance with the contraction.

[0056] In Figure 4, the lengths of the main body member 11, holder 20, and guide member 68 related to the valve body length L1 are indicated by symbols A, B, and C, and the lengths of the valve seat 14, body 41, head 42, receiving member 43, and drive shaft 70 related to the valve body length L2 are indicated by symbols V, W, X, Y, and Z. In this embodiment, each length is for when the electric valve 5 is in the closed state.

[0057] The electric valve 5 may also have a valve body assembly 7A having a valve seat 14A made of the same material (aluminum alloy) as the main body member 11. In the valve body assembly 7A, the valve seat 14A expands and contracts vertically in the same way as the main body member 11, so as shown in Figure 5, the upper end of the valve seat 14A, where the valve body 40 makes contact, is set as the reference position P0. The valve body side length L1 is related to the main body member 11, the holder 20, and the guide member 68, and the valve body side length L2 is related to the body 41, the head 42, the receiving member 43, and the drive shaft 70. The valve body assembly 7A may have a valve seat formed integrally with the main body member 11.

[0058] In the electric valve 5, the components related to the valve body length L1 include components made of aluminum alloy and brass, while the components related to the valve element length L2 include only components made of stainless steel. Therefore, when the temperature of these components rises, the valve body length L1 becomes longer than the valve element length L2, and when the temperature of these components falls, the valve body length L1 becomes shorter than the valve element length L2.

[0059] The control device 90 is connected to an external control device that controls the refrigeration cycle system. The control device 90 controls the electric valve 5 based on commands received from the external control device. The control device 90 is housed in a housing 85.

[0060] As shown in Figure 6, the control device 90 includes a first temperature sensor 91, a second temperature sensor 92, a motor driver 94, and a computer 95.

[0061] The first temperature sensor 91 is positioned, for example, in a recess provided on the outer surface of the valve body 10 (body member 11 or holder 20). The temperature sensing portion of the first temperature sensor 91 is in contact with the valve body 10. The first temperature sensor 91 outputs a signal corresponding to the temperature of the valve body 10.

[0062] The second temperature sensor 92 is embedded, for example, in the housing 85. The temperature sensing portion of the second temperature sensor 92 faces the space SP. The second temperature sensor 92 outputs a signal corresponding to the temperature of the space SP.

[0063] The motor driver 94 is connected to terminals A1 and A2 of the A-phase coil 81c and terminals B1 and B2 of the B-phase coil 82c. The motor driver 94 supplies A-phase current to the A-phase coil 81c and B-phase current to the B-phase coil 82c.

[0064] Computer 95 is a microcontroller that integrates a CPU, memory, input / output interface, and analog-to-digital converter into a single package. Computer 95 may also include a motor driver 94.

[0065] Computer 95 obtains the valve body temperature Tb, which relates to the temperature of the valve body 10, based on the signal output by the first temperature sensor 91. Computer 95 obtains the ambient temperature Ta, which relates to the temperature of the space SP, based on the signal output by the second temperature sensor 92. The ambient temperature Ta is the reference temperature.

[0066] The control device 90 controls the stepping motor 88 using a two-phase excitation method. When the control device 90 inputs pulses P (P[1] to P[4]) to the stepping motor 88, the rotor 51 rotates. Specifically, the computer 95 inputs pulses P (pulse signals) to the motor driver 94, and the motor driver 94 supplies a current corresponding to pulses P to the stator 80, causing the rotor 51 to rotate. In this specification, "inputting pulses P to the stepping motor 88" is synonymous with "supplying a current corresponding to pulses P to the stator 80". The stepping motor 88 may also be controlled using a one-phase excitation method, a one-to-two-phase excitation method, a W1-to-two-phase excitation method, a 2W1-to-two-phase excitation method, or a 4W1-to-two-phase excitation method.

[0067] Computer 95 inputs a step signal (STEP) and a direction signal (DIR) to the motor driver 94. The step signal is a pulse signal. When the motor driver 94 is receiving a direction signal corresponding to the closing direction (e.g., an H-level signal), inputting the step signal corresponds to inputting pulses P to the stepping motor 88 in ascending order (P[1] to P[4]). When the motor driver 94 is receiving a direction signal corresponding to the opening direction (e.g., an L-level signal), inputting the step signal corresponds to inputting pulses P to the stepping motor 88 in descending order (P[4] to P[1]). Figure 7 schematically shows an example of the relationship between the pulses P input to the stepping motor 88 and the step signal and direction signal input to the motor driver 94.

[0068] The computer 95 inputs a current control signal (CTRL) to the motor driver 94. The current control signal is used to set the magnitude of the current supplied to the stator 80 in the motor driver 94.

[0069] Figure 8 shows examples of waveforms for the A-phase current flowing through the A-phase coil 81c and the B-phase current flowing through the B-phase coil 82c. In Figure 8, +Ir represents the A-phase current flowing from terminal A1 to terminal A2, or the B-phase current flowing from terminal B1 to terminal B2, and -Ir represents the A-phase current flowing from terminal A2 to terminal A1, or the B-phase current flowing from terminal B2 to terminal B1. The A-phase and B-phase currents are rectangular waves that alternate between "-Ir" and "+Ir".

[0070] When the magnitudes of the A-phase current and B-phase current are Ir and the input speed of pulse P is Vr, the torque Q generated by the stepping motor 88 (the torque that rotates the rotor 51) is defined as the reference torque Qr.

[0071] When the control device 90 inputs pulses P to the stepping motor 88 in ascending order and cyclically, the rotor 51 rotates in the closing direction (clockwise in Figure 3). The rotation of the rotor 51 is transmitted to the drive shaft 70 by the planetary gear mechanism 60. As the drive shaft 70 rotates, it moves downward due to the lead screw action. The drive shaft 70 pushes the valve body 40 downward. As the valve body 40 moves downward, the valve portion 41b approaches the valve seat 14. When the valve portion 41b contacts the valve seat 14, the valve opening 15 closes, restricting the downward movement of the valve body 40. As the rotor 51 rotates further in the closing direction, the valve body 40 is pressed against the valve seat 14, restricting the rotation of the rotor 51 in the closing direction. At this time, the position of the rotor 51 is the reference position Rx.

[0072] When the control device 90 inputs pulses P to the stepping motor 88 in a descending, cyclical manner, the rotor 51 rotates in the opening direction (counterclockwise in Figure 3). The rotation of the rotor 51 is transmitted to the drive shaft 70 by the planetary gear mechanism 60. As the drive shaft 70 rotates, it moves upward due to the lead screw action. The valve body 40, pushed by the valve opening spring 77, moves upward, the valve portion 41b separates from the valve seat 14, and the valve port 15 opens. When the rotor 51 rotates further in the opening direction to the fully open position Rz, the valve portion 41b is furthest away from the valve seat 14. The number of pulses required to rotate the rotor 51 from the fully open position Rz to the reference position Rx is called the full stroke number. The full stroke number is, for example, 1500.

[0073] The memory of computer 95 stores a valve opening data table. In the valve opening data table, the position of the rotor 51 is associated with the valve opening of the electric valve 5. The position of the rotor 51 is indicated by the number of pulses input to the stepping motor 88. When the number of pulses input to the stepping motor 88 is 0, the rotor 51 is at the reference position Rx. When the number of pulses input to the stepping motor 88 is 1500, the rotor 51 is at the fully open position Rz. There is a proportional relationship between the number of pulses and the valve opening. When the number of pulses is 0 (when the rotor 51 is at the reference position Rx), the valve opening is 0%. When the number of pulses is 150, the valve opening is 10%. When the number of pulses is 750, the valve opening is 50%. When the number of pulses is 1500 (when the rotor 51 is at the fully open position Rz), the valve opening is 100%.

[0074] Next, the valve opening change process executed when the control device 90 (computer 95) receives a valve opening change command from an external control device will be explained with reference to Figures 9 and 10. The valve opening change command includes a target valve opening.

[0075] The control device 90 receives a valve opening change command from an external device (S110). The control device 90 obtains the number of pulses (target number Nt) corresponding to the target valve opening included in the valve opening change command from the valve opening data table (S120). The control device 90 obtains the number of pulses (current number Np) corresponding to the current valve opening from the valve opening data table (S130). The control device 90 obtains the difference value (absolute value) between the target number Nt and the current number Np as the control number Nc (S140).

[0076] When the target valve opening is not 0% (N in S150), the control device 90 sets the reference torque Qr as the torque Q generated by the stepping motor 88 (S160).

[0077] When the target valve opening is 0% (Y in S150), the control device 90 obtains the valve body temperature Tb based on the signal output by the first temperature sensor 91 and the ambient temperature Ta based on the signal output by the second temperature sensor 92 (S220).

[0078] The control device 90 sets a first torque Qq as the torque Q generated by the stepping motor 88 (S250) when the difference (absolute value) between the valve body temperature Tb and the ambient temperature Ta is greater than a predetermined judgment value Th and the valve body temperature Tb is higher than the ambient temperature Ta (Y in S230, Y in S240). The judgment value Th is greater than 0, for example, 10°C. The first torque Qq is less than the reference torque Qr.

[0079] The control device 90 sets a second torque Qs as the torque Q generated by the stepping motor 88 when the difference between the valve body temperature Tb and the ambient temperature Ta is greater than the determination value Th and the valve body temperature Tb is lower than the ambient temperature Ta (Y in S230, N in S240) (S260). The second torque Qs is greater than the reference torque Qr.

[0080] The control device 90 sets a reference torque Qr as the torque Q generated by the stepping motor 88 when the difference between the valve body temperature Tb and the ambient temperature Ta is less than or equal to the determination value Th (N in S230) (S160). The reference torque Qr is used when the valve body temperature Tb and the ambient temperature Ta are the same or the difference is relatively small.

[0081] The control device 90 sets a reference torque Qr as the torque Q generated by the stepping motor 88 by setting the magnitudes of the A-phase current and B-phase current to Ir and the input speed of the pulse P to Vr.

[0082] The control device 90 sets the first torque Qq as torque Q by making the magnitudes of the A-phase current and B-phase current smaller than Ir (for example, Ir × 0.5 to Ir × 0.9), and sets the second torque Qs as torque Q by making the magnitudes of the A-phase current and B-phase current larger than Ir (for example, Ir × 1.1 to Ir × 1.5).

[0083] Alternatively, the control device 90 may set the first torque Qq as torque Q by making the input speed of pulse P faster than Vr (for example, Vr × 1.2 to Vr × 1.5), or it may set the second torque Qs as torque Q by making the input speed of pulse P slower than Vr (for example, Vr × 0.5 to Vr × 0.8).

[0084] When the target number Nt is less than the current number Np (Y in S170), the control device 90 inputs pulses P of control number Nc in ascending order to the stepping motor 88 to rotate the rotor 51 in the closing direction (S180). When the target number Nt is greater than the current number Np (N in S170, Y in S190), the control device 90 inputs pulses P of control number Nc in descending order to the stepping motor 88 to rotate the rotor 51 in the opening direction (S200). When the target number Nt is the same as the current number Np (N in S170, N in S190), the control device 90 does not input pulses P to the stepping motor 88 and does not rotate the rotor 51. Then, the control device 90 sets the target valve opening as the current valve opening and ends the valve opening change process.

[0085] In the valve opening change process, when the target valve opening is 0%, the rotor 51 is rotated in the closing direction with a torque Q (reference torque Qr, first torque Qq, or second torque Qs) set according to the difference between the valve body temperature Tb and the ambient temperature Ta, and the valve body 40 is pressed against the valve seat 14. At this time, the force pressing the valve body 40 against the valve seat 14 is of a magnitude corresponding to the torque Q.

[0086] In the valve opening degree change process, the control device 90 may set the control number Nc to be greater than the difference between the target number Nt and the current number Np when the target valve opening degree is 0%. For example, the control device 90 sets the control number Nc to a number obtained by adding a predetermined number (50 to 200) to the difference value. By doing so, the rotor 51 can be positioned to the reference position Rx more reliably.

[0087] Next, the initialization process performed by the control device 90 will be explained with reference to Figure 11.

[0088] The control device 90 starts an initialization process (S310) when it detects, for example, a stepping motor 88 losing step or an unexpected power loss. The control device 90 also starts an initialization process when it receives an initialization command from an external control device.

[0089] The control device 90 acquires the valve body temperature Tb based on the signal output by the first temperature sensor 91 and the ambient temperature Ta based on the signal output by the second temperature sensor 92 (S320).

[0090] The control device 90 sets the first torque Qq as the torque Q generated by the stepping motor 88 when the difference between the valve body temperature Tb and the ambient temperature Ta is greater than the determination value Th and the valve body temperature Tb is higher than the ambient temperature Ta (Y in S330, Y in S340) (S350).

[0091] The control device 90 sets the second torque Qs as the torque Q generated by the stepping motor 88 when the difference between the valve body temperature Tb and the ambient temperature Ta is greater than the determination value Th and the valve body temperature Tb is lower than the ambient temperature Ta (Y in S330, N in S340) (S360).

[0092] The control device 90 sets the reference torque Qr as the torque Q generated by the stepping motor 88 when the difference between the valve body temperature Tb and the ambient temperature Ta is less than or equal to the determination value Th (N in S330) (S370).

[0093] The control device 90 inputs X pulses P in ascending order to the stepping motor 88 to rotate the rotor 51 in the closing direction (S380). X is a number sufficient to rotate the rotor 51 from the fully open position Rz to the reference position Rx, and is set to a number obtained by adding a predetermined number (50 to 200) to the full stroke number. When the control device 90 has finished inputting X pulses P to the stepping motor 88, the rotor 51 is positioned at the reference position Rx. The control device 90 resets the position of the rotor 51 (i.e., sets the current valve opening to 0%) and ends the initialization process.

[0094] During the initialization process, the rotor 51 is rotated in the closing direction with a torque Q (reference torque Qr, first torque Qq, or second torque Qs) set according to the difference between the valve body temperature Tb and the ambient temperature Ta, and the valve body 40 is pressed against the valve seat 14. At this time, the force pressing the valve body 40 against the valve seat 14 is in magnitude corresponding to the torque Q.

[0095] As described above, the electric valve device 1 includes an electric valve 5 and a control device 90. The electric valve 5 includes a valve body 10 on which a valve seat 14 is provided, a valve element 40 facing the valve seat 14, a stepping motor 88 having a rotor 51 and a stator 80, and a drive mechanism 55 that moves the valve element 40 in accordance with the rotation of the rotor 51. The control device 90 controls the electric valve 5. When the control device 90 presses the valve element 40 against the valve seat 14, it rotates the rotor 51 with a torque Q corresponding to the difference between the valve body temperature Tb and the ambient temperature Ta.

[0096] The valve body temperature Tb is related to the temperature of the refrigerant inside the valve body 10 when the electric valve device 1 (electric valve 5) is operating, and approaches the ambient temperature SP after the electric valve device 1 is turned off. Therefore, by setting the ambient temperature SP (ambient temperature Ta) as the temperature to which the valve body temperature Tb is expected to approach after the electric valve device 1 is turned off, the increase or decrease in the force pressing the valve body 40 against the valve seat 14 can be estimated based on the difference between the valve body temperature Tb and the ambient temperature Ta. By rotating the rotor 51 with a torque Q corresponding to the difference, the valve body 40 can be pressed against the valve seat 14 with a force that takes into account the change in size of the components constituting the electric valve 5. Thus, the state in which the valve body 40 is properly pressed against the valve seat 14 can be maintained after the electric valve device 1 is turned off.

[0097] The electric valve 5 has a configuration in which, when the valve body temperature Tb decreases, the length L1 on the valve body side becomes shorter than the length L2 on the valve element side, and when the valve body temperature Tb increases, the length L1 on the valve body side becomes longer than the length L2 on the valve element side. In other words, the electric valve 5 has a configuration in which, when the valve body temperature Tb decreases while the valve element 40 is pressed against the valve seat 14, the force pressing the valve element 40 against the valve seat 14 increases, and when the valve body temperature Tb increases while the valve element 40 is pressed against the valve seat 14, the force pressing the valve element 40 against the valve seat 14 decreases. If the torque Q used to rotate the rotor 51 when the valve body temperature Tb is the same as the ambient temperature Ta is defined as the reference torque Qr, then the control device 90 sets the torque Q to a first torque Qq which is smaller than the reference torque Qr when the valve body temperature Tb is higher than the ambient temperature Ta, and sets the torque Q to a second torque Qs which is larger than the reference torque Qr when the valve body temperature Tb is lower than the ambient temperature Ta. In this way, the control device 90 reduces the torque Q that rotates the rotor 51 when it is estimated that the force pressing the valve body 40 against the valve seat 14 will increase (first torque Qq), and increases it when it is estimated that the force will decrease (second torque Qs). Therefore, the valve body 40 can be kept properly pressed against the valve seat 14 even after the power to the electric valve device 1 is turned off. The torque Q may be a reference torque Qr when the valve body temperature Tb and the ambient temperature Ta (reference temperature) are the same, and a torque proportional to the difference between the valve body temperature Tb and the ambient temperature Ta when the valve body temperature Tb and the ambient temperature Ta are different (for example, Q = k × (Tb - Ta) + Qr, where k is a coefficient).

[0098] Furthermore, the electric valve 5 may have a configuration in which, by adjusting the material and vertical length of the respective components related to the valve body length L1 and the valve element length L2, when the valve body temperature Tb decreases, the valve body length L1 becomes longer than the valve element length L2, and when the valve body temperature Tb increases, the valve body length L1 becomes shorter than the valve element length L2. In other words, the electric valve 5 may have a configuration in which, when the valve body temperature Tb decreases while the valve element 40 is pressed against the valve seat 14, the force pressing the valve element 40 against the valve seat 14 decreases, and when the valve body temperature Tb increases while the valve element 40 is pressed against the valve seat 14, the force pressing the valve element 40 against the valve seat 14 increases. In this configuration, if the torque Q used to rotate the rotor 51 when the valve body temperature Tb is the same as the ambient temperature Ta is defined as the reference torque Qr, then the control device 90 sets the torque Q to a second torque Qs, which is greater than the reference torque Qr, when the valve body temperature Tb is higher than the ambient temperature Ta, and to a first torque Qq, which is smaller than the reference torque Qr, when the valve body temperature Tb is lower than the ambient temperature Ta. In this way, the control device 90 reduces the torque Q used to rotate the rotor 51 when it is estimated that the force pressing the valve body 40 against the valve seat 14 will be greater (first torque Qq), and increases it when it is estimated that the force will be less (second torque Qs). Therefore, the state in which the valve body 40 is properly pressed against the valve seat 14 can be maintained even after the power to the electric valve device 1 is turned off.

[0099] In this embodiment, the ambient temperature Ta, which is the temperature of the space SP in which the electric valve device 1 (electric valve 5) is located, is used as the temperature (reference temperature) that the valve body temperature Tb is expected to approach after the power supply of the electric valve device 1 is turned off. By doing so, the change in the force pressing the valve body 40 against the valve seat 14 after the power supply of the electric valve device 1 is turned off can be estimated more accurately.

[0100] For example, if the time from the power-off time to the power-on time of the electric valve device 1 is greater than or equal to a predetermined determination time, the control device 90 may use the valve body temperature Tb acquired immediately after the power of the electric valve device 1 is turned on as the reference temperature. The determination time is sufficient time for the temperature of the components constituting the electric valve 5 to become equal to the temperature of the space SP after the power of the electric valve device 1 is turned off. The determination time is, for example, 1 hour to 24 hours. Alternatively, the control device 90 has a date function and may set a temperature corresponding to the current season as the reference temperature. For example, the reference temperature may be set to 25°C in summer and 10°C in winter.

[0101] The control device 90 may also have a configuration in which the first temperature sensor 91 and the second temperature sensor 92 are omitted. In this configuration, the control device 90 obtains the temperature of the space in which the refrigeration cycle system is located and the temperature of the refrigerant from an external control device as the ambient temperature Ta (reference temperature) and the valve body temperature Tb.

[0102] In this specification, terms indicating shapes such as "cylinder," "rod," and "cuboid" are also used to refer to members or parts of members that substantially have the shape of those terms. For example, "cylindrical member" includes both cylindrical members and substantially cylindrical members. Also, in this specification, "the same" includes substantially the same thing.

[0103] Although embodiments of the present invention have been described above, the present invention is not limited to the configurations of these embodiments. Additions, deletions, design modifications, and combinations of features of the embodiments, as appropriate by those skilled in the art, are also included within the scope of the present invention, as long as they do not contradict the spirit of the invention. [Explanation of Symbols]

[0104] 1...Electric valve device, 5...Electric valve, 7, 7A...Valve body assembly, 8...Stator unit, 10... Valve body, 11... Body component, 14, 14A... Valve seat, 15... Valve opening 20...Holder, 30...Can, 40...Valve body 50...Rotor assembly, 51...Rotor, 55...Drive mechanism 68... Guide member, 70... Drive shaft, 80... Stator, 88... Stepping motor 90...Electric valve control device, 91...First temperature sensor, 92...Second temperature sensor, 94...Motor driver, 95...Computer

Claims

1. An electric valve control device for controlling an electric valve having a valve body provided with a valve seat, a valve element facing the valve seat, a motor having a rotor and a stator, and a drive mechanism for moving the valve element in accordance with the rotation of the rotor, The electric valve control device is characterized in that, when the electric valve control device presses the valve body against the valve seat, it rotates the rotor with a torque corresponding to the difference between the temperature of the valve body and a reference temperature.

2. The electric valve has a configuration in which, when the temperature of the valve body is low while the valve body is pressed against the valve seat, the force pressing the valve body against the valve seat increases, and when the temperature of the valve body is high while the valve body is pressed against the valve seat, the force pressing the valve body against the valve seat decreases. The electric valve control device according to claim 1, wherein, with respect to the torque used when the valve body temperature is the same as the reference temperature, the electric valve control device sets the torque to a first torque which is smaller than the reference torque when the valve body temperature is higher than the reference temperature, and sets the torque to a second torque which is larger than the reference torque when the valve body temperature is lower than the reference temperature.

3. The electric valve has a configuration in which, when the temperature of the valve body is low while the valve body is pressed against the valve seat, the force pressing the valve body against the valve seat decreases, and when the temperature of the valve body is high while the valve body is pressed against the valve seat, the force pressing the valve body against the valve seat increases. The electric valve control device according to claim 1, wherein, when the valve body temperature is the same as the reference temperature, the torque used is defined as the reference torque, and when the valve body temperature is higher than the reference temperature, the electric valve control device sets the torque to a second torque which is greater than the reference torque, and when the valve body temperature is lower than the reference temperature, the torque to a first torque which is less than the reference torque.

4. The electric valve control device according to claim 1, wherein the reference temperature is the temperature of the space in which the electric valve is located.

5. The electric valve control device according to claim 1, wherein the reference temperature is the temperature of the valve body immediately after the power to the electric valve is turned on.

6. An electric valve device comprising the electric valve control device described in claim 1 and the electric valve.

Images