Control device for electric valve, electric valve, and electric valve unit using the same

Abstract

To provide a control device of an electric valve which can perform proper flow rate control by changing the control of a stepping motor according to a hysteresis amount, and an electric valve unit using the electric valve.SOLUTION: A control device of an electric valve comprises: a valve body which is movable in a direction approaching a valve seat, or a direction separating therefrom; a stepping motor operated by being inputted with a drive pulse; a drive mechanism for driving the valve body by a drive force outputted from the stepping motor; a non-volatile storage unit for storing a hysteresis amount; and a control unit for driving the stepping motor according to motion indication information inputted from the outside. When moving the valve body in a direction different from a previous movement direction on the basis of the motion indication information which is inputted from the outside, the control unit inputs a drive pulse having an effective pulse number which is obtained by adding a pulse number corresponding to the hysteresis amount stored in the storage unit to a target pulse number corresponding to a target moving amount of the valve body into the stepping motor.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a control device for an electric valve, an electric valve, and an electric valve unit using the same.

Background Art

[0002] Conventionally, in a refrigeration cycle system used in an air conditioner, a refrigerating or freezing showcase, etc., for the purpose of stabilizing the cooling capacity, keeping the superheat degree constant, and operating efficiently, an electric valve that operates a valve body by a stepping motor is used to adjust the flow rate of the circulating refrigerant.

[0003] In controlling such an electric valve, usually, an initialization process (also referred to as origin positioning, reference point positioning, or initialization, etc.) is executed when the power is turned on, etc., and after positioning the valve body, the control of the opening degree is started (see, for example, Patent Document 1). Here, the initialization process is a process of rotating the stepping motor sufficiently in the valve closing direction or the valve opening direction by the number of pulses exceeding the full stroke from the fully open position to the fully closed position or from the fully closed position to the fully open position. Specifically, for example, the number of pulses when the rotor of the stepping motor surely collides with a rotation stopper called a stopper and stops rotating, and thereby the initial position of 0 pulse or maximum pulse of the electric valve can be determined.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, a general electric valve converts the rotational movement of the rotor of a stepping motor into an axial movement to drive the valve body in the axial direction. There is also an electric valve that decelerates the rotational movement of the rotor using a gear and then converts it into an axial movement to drive the valve body. In such an electric valve, when the rotational direction reverses from valve opening to valve closing or from valve closing to valve opening, there is a problem that the valve body cannot reach the target position accurately due to hysteresis caused by backlash existing in the power transmission path. In order to accurately reach the valve body to the target position, it is necessary to obtain the amount of hysteresis and correct the number of drive pulses, but there is a situation that it is difficult to obtain the amount of hysteresis with high accuracy.

[0006] An object of the present invention is to provide a control device for an electric valve, an electric valve, and an electric valve unit using the same that can perform appropriate flow rate control by changing the control of a stepping motor according to the amount of hysteresis.

Means for Solving the Problems

[0007] To achieve the above object, a control device for an electric valve according to the present invention is a valve body movable in a direction approaching or separating from a valve seat, a stepping motor that operates by inputting drive pulses, a drive mechanism that drives the valve body by a driving force output from the stepping motor, a non-volatile storage unit, and a control unit that drives the stepping motor according to operation instruction information input from the outside, and is a control device for an electric valve, the storage unit stores the amount of hysteresis, when the control unit moves the valve body in a direction different from the previous moving direction based on operation instruction information input from the outside, it inputs a drive pulse of an effective pulse number obtained by adding the number of pulses corresponding to the amount of hysteresis stored in the storage unit to the target pulse number corresponding to the target movement amount of the valve body to the stepping motor, The control unit moves the valve body in one direction and then stops the stepping motor. At this time, the flow rate of the fluid passing between the valve body and the valve seat is obtained as the initial flow rate. Then, each time the number of drive pulses input to the stepping motor is increased to move it in the other direction, the flow rate of the fluid is obtained. The number of pulses - 1 at the time when the flow rate changed with respect to the initial flow rate first becomes equal to or greater than a predetermined amount is stored in the storage unit as the hysteresis amount. This is the gist of the invention.

[0008] The electric valve according to the present invention includes a valve body movable in a direction approaching or separating from a valve seat, a stepping motor that operates by inputting drive pulses, a drive mechanism that drives the valve body by a driving force output from the stepping motor, a non-volatile storage unit, and a control unit that drives the stepping motor according to operation instruction information input from the outside. The storage unit stores a hysteresis amount. When the control unit moves the valve body in a direction different from the previous moving direction based on operation instruction information input from the outside, it inputs drive pulses of an effective number of pulses obtained by adding the number of pulses corresponding to the hysteresis amount stored in the storage unit to the target number of pulses corresponding to the target movement amount of the valve body to the stepping motor. The control unit moves the valve body in one direction and then stops the stepping motor. At this time, the flow rate of the fluid passing between the valve body and the valve seat is obtained as the initial flow rate. Then, each time the number of drive pulses input to the stepping motor is increased to move it in the other direction, the flow rate of the fluid is obtained. The number of pulses - 1 at the time when the flow rate changed with respect to the initial flow rate first becomes equal to or greater than a predetermined amount is stored in the storage unit as the hysteresis amount. This is the gist of the invention. According to the electric valve of the present invention described above, it can also be considered that the invention of the object is specified by the so-called product-by-process format. Here, it may be difficult to distinguish an electric valve that stores the amount of hysteresis from a product. Therefore, there is a situation where it is impossible to directly specify an object by its structure or characteristics, or it is approximately impractical (the "impossible / impractical situation").

Advantages of the Invention

[0009] According to the present invention, by changing the control of the stepping motor according to the amount of hysteresis, it is possible to provide a control device for an electric valve, an electric valve, and an electric valve unit using the same that can perform appropriate flow control.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Best Mode for Carrying Out the Invention

[0011] Hereinafter, with reference to the drawings, the electric valve 1, the control device 100, and the inspection device 200 according to the embodiments of the present invention will be described. The electric valve 1 of the present embodiment is installed in the circulation path of the refrigeration cycle device and controls the flow rate of the refrigerant flowing in the circulation path. The electric valve 1 and the control device 100 constitute an electric valve unit, and the control device 100 and the inspection device 200 constitute a measuring device for the electric valve 1.

[0012] (Electric valve) FIG. 1 is a longitudinal sectional view showing the closed valve state of the electric valve 1 according to the present embodiment, with the schematic configurations of the control device 100 and the inspection device 200 added. FIG. 2 is a plan view of the speed reduction part 20 of the electric valve 1. The electric valve 1 and the control device 100 are incorporated into the refrigeration cycle device in a unique combination. Referring to FIG. 1, the electric valve 1 will be described.

[0013] (Configuration of electric valve) The electric valve 1 has a drive part 10, a speed reduction part 20, and a valve mechanism part 30. Let the axis of the valve mechanism part 30 be L. Also, the motor side will be described as being upward and the valve body side as being downward.

[0014] First, the drive part 10 will be described. In the figure, the drive part 10 has a drive part case 11, a stator 12 attached inside the drive part case 11, a rotor 13 arranged radially inside the stator 12, and a drive shaft 14 fixed to the rotor 13. The stator 12 and the rotor 13 constitute a stepping motor. Note that a stepping motor is a device that rotates the rotor by a precise rotation angle according to the input drive pulse when a drive pulse is input.

[0015] The drive unit case 11 is formed in a toped cylindrical shape, and a bearing 15 is fixedly held on the lower surface at the center of the top. The bearing 15 rotatably holds the drive shaft 14. Below the stator 12 and the rotor 13, a toped cylindrical support cylinder 16 is disposed so as to fit into the inner circumference of the drive unit case 11. The lower end of the support cylinder 16 abuts on the upper surface of an annular member 17 that closes the drive unit case 11, and the lower end of the drive unit case 11 and the outer circumference of the annular member 17 are fixed by caulking.

[0016] The support cylinder 16 has a hollow cylindrical portion 16a formed on the lower surface at the center of the top and a through hole (not shown). The lower end of the drive shaft 14 penetrates through the through hole of the support cylinder 16 and is rotatably supported by the through hole.

[0017] Next, the reduction unit 20 will be described. The reduction unit 20 includes a first shaft 21 and a second shaft 22 whose both ends are respectively held on the lower surface of the top of the support cylinder 16 and the upper surface of the annular member 17, a drive gear 23 fixed to the lower end of the drive shaft 14 that penetrates through the through hole of the support cylinder 16, a first transmission gear 24 rotatably held with respect to the first shaft 21, a second transmission gear 25 rotatably held with respect to the second shaft 22, a final gear 26, a male screw shaft 27, and a female screw cylinder 28. The male screw shaft 27 is press-fitted and fixed to the final gear 26 and is integrated therewith.

[0018] The first shaft 21 and the second shaft 22 are disposed in parallel with the drive shaft 14. The first transmission gear 24 coaxially connects a first input gear portion 24a that meshes with the drive gear 23 and a first output gear portion 24b. The second transmission gear 25 coaxially connects a second input gear portion 25a that meshes with the first output gear portion 24b and a second output gear portion 25b that meshes with the final gear 26. Each shaft can be made of metal and each gear can be made of resin. The drive gear 23, the first transmission gear 24, the second transmission gear 25, and the final gear 26 constitute a gear train. The reduction unit 20 is not limited to the above configuration as long as it is configured to decelerate the driving force input to the drive shaft 14 (or the input shaft) and output it to the final gear 26 (or the male screw shaft 27, or the output shaft). For example, a reduction device having a planetary gear may be used.

[0019] Referring to FIG. 2, the final gear 26 is provided with an arc groove 26a so as to surround a male screw shaft 27 on its lower surface. One circumferential end of the arc groove 26a is defined as an end 26b, and the other end is defined as an end 26c. The angle from the end 26b to the end 26c is a given value.

[0020] In FIGS. 1 and 2, a hole 17a is formed in the upper surface of the annular member 17, and the lower end of the pin 29 is fitted and fixed in the hole 17a. Further, the upper end of the pin 29 is disposed so as to be located within the arc groove 26a.

[0021] The upper end of the male screw shaft 27 is fitted to the inner circumference of the hollow cylindrical portion 16a of the support cylinder 16, and is disposed so as to be relatively rotatable and displaceable in the axial direction within the hollow cylindrical portion 16a. Further, the final gear 26 is fitted and fixed at an intermediate position of the male screw shaft 27, and a male screw 27a is formed on the outer circumference of the lower end side thereof.

[0022] The female screw cylinder 28, which is hollow cylindrical, is fitted and fixed to the inner circumference of the annular member 17 on the upper end side with a reduced diameter, and is provided with a through hole 28a penetrating along the axis L. A female screw 28b that screws with the male screw 27a is formed on the lower end side of the through hole 28a. Since the female screw cylinder 28 is fixed to the annular member 17, when the male screw shaft 27 rotates, the male screw 27a screws with the female screw 28b, and thereby an axial force is applied from the female screw cylinder 28. For this reason, the male screw shaft 27 is displaced in the axial direction by an amount corresponding to its rotation angle. The male screw shaft 27 and the female screw cylinder 28 constitute a conversion mechanism. The gear train and the conversion mechanism constitute a drive mechanism.

[0023] The female screw cylinder 28 is provided with a thin-walled cylindrical portion 28c having an enlarged diameter at its lower end. Further, a cylindrical connecting member 34 is disposed on the outer circumference of the female screw cylinder 28. The connecting member 34 includes a reduced-diameter upper end portion 34a that fits on the outer circumference of the female screw cylinder 28 and an internal thread portion 34b on the inner circumference of the lower end.

[0024] Next, the valve mechanism portion 30 will be described. The valve mechanism section 30 includes a valve body 31, a valve shaft 32, and a valve element 33.

[0025] The valve body 31 made of metal is a hollow cylinder with a relatively thick wall. It has a reduced-diameter portion 31a on the outer periphery of the upper end and an external thread portion 31b on the outer periphery below the reduced-diameter portion 31a. A thin-walled cylindrical portion 28c is fitted onto the outer periphery of the reduced-diameter portion 31a. By screwing the internal thread portion 34b of the connecting member 34 fitted onto the outer periphery of the female screw cylinder 28 onto the external thread portion 31b and screwing in the connecting member 34, the lower surface of the reduced-diameter upper end portion 34a abuts and engages with the upper end step portion of the thin-walled cylindrical portion 28c. Thereby, the female screw cylinder 28 can be connected and fixed to the valve body 31.

[0026] A spacer 35 is disposed between the lower surface of the female screw cylinder 28 and the upper end of the valve body 31 on the inner periphery of the thin-walled cylindrical portion 28c so that the distance between the valve body 31 and the female screw cylinder 28 during connection and fixation can be adjusted.

[0027] A first pipe 51 forming a first flow path is connected to an opening 31c formed on the outer periphery near the lower end of the valve body 31 so as to be orthogonal to the axis L. Let the axis of the first pipe 51 be O.

[0028] Also, an opening formed coaxially with the axis L at the lower end of the valve body 31 constitutes an orifice 31d. Also, the upper end of the orifice 31d constitutes a valve seat 31e. A second pipe 52 is connected to the valve body 31 so as to communicate with the orifice 31d.

[0029] The valve shaft 32 is disposed inside the valve body 31. The valve shaft 32 is formed by coaxially connecting a small-diameter portion 32a, a large-diameter portion 32b, a flange portion 32c, and a small-diameter convex portion 32d. A ball holding portion 32e, which is separate from the valve shaft 32, is attached to the upper end of the small-diameter portion 32a facing the lower end of the male screw shaft 27. A metal ball 37 is disposed between the concave portion at the center of the lower end of the male screw shaft 27 and the concave portion at the center of the upper end of the ball holding portion 32e.

[0030] An annular plate 36 is caulked and fixed to the inner periphery of the upper end of the valve body 31. A metal bellows 38 connects the lower surface of the annular plate 36 and the outer periphery of the upper end of the large-diameter portion 32b of the valve shaft 32 so as to surround the small-diameter portion 32a of the valve shaft 32. Therefore, when the electric valve 1 is in use, inside the valve body 31, the outside of the bellows 38 is in contact with the refrigerant, but the inside of the bellows 38 is in contact with the atmosphere. The outside of the bellows 38 inside the valve body 31 constitutes the valve chamber C.

[0031] Below the valve shaft 32, a bottomed cylindrical valve body 33 is arranged. The valve body 33 is formed by connecting a large cylindrical portion 33a on the upper end side that is slidable with respect to the inner periphery of the valve body 31, a small cylindrical portion 33b on the lower end side, and a bottom portion 33c. On the lower surface side of the bottom portion 33c, a tapered surface 33d that is axisymmetric with respect to the axis L is formed. The upper end of the large cylindrical portion 33a is caulked and fixed to the outer periphery of an annular slide plate 40. The slide plate 40 is fitted slidably along the direction of the axis L to the large-diameter portion 32b of the valve shaft 32, but by abutting against the flange portion 32c, it does not move further downward along the valve shaft 32. The valve shaft 32 and the valve body 33 can be relatively displaced by a predetermined distance in the axial direction.

[0032] Inside the inner periphery of the small cylindrical portion 33b of the valve body 33, a coil spring 39, which is a biasing member, is disposed. The upper end of the coil spring 39 abuts against the lower end of the valve shaft 32 around the small-diameter convex portion 32d, and the lower end of the coil spring 39 abuts against the upper surface of the bottom portion 33c of the valve body 33. Therefore, due to the coil spring 39, the valve body 33 is always biased downward with respect to the valve shaft 32.

[0033] Next, the control device 100 will be described. By attaching the control device 100 to the electric valve 1, an electric valve unit suitable for use in a refrigeration cycle is formed together with the electric valve 1, and it is used, for example, as an electric valve (expansion valve) for an in-vehicle air conditioner or the like. When the electric valve unit is used in an in-vehicle air conditioner, the control unit 100 of the electric valve unit is connected to a communication cable that controls the in-vehicle air conditioner, and performs drive control of the electric valve 1 according to an instruction from a control device (air conditioner ECU) of the air conditioning system.

[0034] Also, when determining the opening pulse and the amount of hysteresis as described later, the control device 100 is connected to the inspection device 200 and constitutes the measuring device of the electric valve 1. In the inspection (shipment inspection) when the electric valve 1 is shipped from the factory after completion, the control device 100 is connected to the inspection device 200 and inputs various measurement data into the non-volatile memory (EEPROM 111e). In this case, the drive control of the electric valve 1 is performed according to the instruction of the control device (ECU) of the inspection device 200.

[0035] A power supply is connected to the control device 100, and a communication line of a refrigeration cycle such as the factory inspection device 200 or a vehicle is connected. When constituting the measuring device of the electric valve 1, for example, the control device 100 is connected to a communication line such as a network such as a LAN in the factory or a communication cable with the inspection device. Also, when constituting the electric valve unit, the control device 100 is connected to a communication line (for example, a communication bus of the LIN bus (or CAN bus or FlexRay bus) 114) that controls the air conditioning system of a vehicle or the like. The control device 100 operates as a slave node as viewed from the inspection device 200 or the air conditioner. When connected to the inspection device 200, the control device 100 receives commands such as the number of pulses of the stepping motor of the electric valve 1 and a signal for an initialization operation instruction via a communication signal transmitted from the ECU 116 that constitutes a part of the inspection device 200, and controls the opening degree (valve opening degree) of the electric valve 1. In the following description, the LIN bus is taken as an example for the communication bus, but it goes without saying that a communication bus other than LIN may also be used.

[0036] In addition, as the communication method between the ECU 116 and the control device 100, there are input / output to the serial interface as described above (LIN communication, CAN communication, FlexRay communication, etc.: hereinafter referred to as "LIN communication etc."), input / output to the I / O port by digital signals (such as ON-OFF signals), input / output by wireless (Wi-Fi (registered trademark), Bluetooth (registered trademark), etc.), etc., and it is not limited to LIN communication etc. However, in FIG. 1, reception of the power-off signal, reception of the sleep mode transition signal, transmission of the power-off enable signal, and transmission of the sleep mode transition permission signal, etc., which are used for the control of the control device 100, are performed by LIN communication. By using an existing in-vehicle LAN such as LIN communication in this way, it becomes unnecessary to install new signal lines for transmission and reception.

[0037] The control device 100 mainly includes a regulator 111a that generates a power supply +Vc (e.g., +5Vdc) used by the circuits inside the control device 100 from a power source, a ROM that stores a program for controlling the rotation of the stepping motor of the electric valve 1 based on a LIN communication signal transmitted from the ECU 116 through the LIN bus 114, a CPU that executes the program stored in the ROM and performs arithmetic processing, a RAM that temporarily stores data necessary for executing the program such as the status of the initialization operation and communication data, an I / O circuit that performs input / output with peripheral circuits, a timer that measures time for interrupt processing, etc., an A / D converter that converts an analog signal into a digital value, etc. A microcomputer (control unit) 111b as an arithmetic unit, a LIN transceiver 111c connected to the LIN bus 114, which converts the voltage level of the LIN bus 114 into the circuit voltage level inside the control device 100 and enables LIN communication with the microcomputer 111b, a stepping motor driver 111d that outputs drive pulses to control the rotation of the stepping motor of the electric valve 1 based on a control signal from the microcomputer 111b, and an EEPROM (non-volatile storage unit) 111e, which is a non-volatile memory serving as a storage unit connected to the microcomputer 111b and stores data (e.g., valve opening information regarding the current valve opening of the electric valve 1, its rotation direction, an abnormal end flag described later, etc.) that needs to be retained even when the power supply is cut off, are mounted on a substrate (not shown) to be configured.

[0038] Note that an IC integrally configured with two or more of the regulator 111a, the LIN transceiver 111c, the stepping motor driver 111d, the EEPROM 111e, and the microcomputer 111b may be used. In this case, further miniaturization of the device becomes possible.

[0039] The specific configuration of the control device 100 is not limited to the above configuration, and any configuration may be used as long as the present invention can be implemented.

[0040] (Inspection device) In addition to the ECU 116, the inspection device 200 includes a compressor 201, a pressure reducing valve 202, a pressure sensor 203, a flow meter 204, and a programmable logic controller (PLC) 205 for controlling these components. These are connected to the ECU 116 via a communication bus (such as CAN or RS232C). Note that the inspection device 200 will be described below as an inspection device for the inspection process that is shipped from the factory after the completion of the electric valve 1. However, if there is a refrigeration cycle device equipped with an electric valve unit and capable of measuring flow rate, the same inspection process may be performed in a state where it is assembled to the refrigeration cycle device.

[0041] The compressor 201 compresses air, and the compressed air is decompressed to a constant pressure by the pressure reducing valve 202 operating under the control of the PLC 205 and supplied to the pipe 51 of the electric valve 1. At this time, the air pressure supplied to the pipe 51 is measured by the pressure sensor 203, and the measurement signal is input to the PLC 205 to check whether it has reached a certain pressure. If it is not at a certain pressure, the PLC 205 controls the pressure reducing valve 202 so that it reaches a certain pressure.

[0042] On the other hand, the flow meter 204 is connected to the pipe 52, measures the amount of air passing between the valve seat 31e and the valve body 33, and outputs the measurement signal to the control device 100 via the ECU 116. Here, air is used for flow measurement, but flow measurement may also be performed using a refrigerant.

[0043] It is necessary to determine, for example, 0 pulses as the initial position of the electric valve 1. When the control device 100 is connected to the inspection device 200, the ECU 116 can transmit a command (initialization instruction signal) for executing an initialization operation of rotating the stepping motor of the electric valve 1, for example, in the valve closing direction by more than the maximum number of pulses, to the control device 100 as a LIN communication signal via the LIN bus 114.

[0044] Also, if the valve opening degree of the electric valve 1 (i.e., the current position (number of pulses) of the stepping motor of the electric valve 1) and the rotation direction of the stepping motor are transmitted from the control device 100 via the LIN bus 114, the valve opening degree and the rotation direction can also be transmitted (known) to the ECU 116 via the LIN bus 114.

[0045] Here, the valve opening degree information is information related to the valve opening degree of the electric valve 1, and includes, for example, information such as the rotation position of the stepping motor of the electric valve 1, the number of pulses, and the valve body position of the electric valve 1. The maximum number of pulses is the number of pulses applied to the stepping motor of the electric valve 1 while the valve body moves from the lower limit position (the limit position where the valve body can move downward) to the upper limit position (the limit position where the valve body can move upward), or the number of pulses applied to the stepping motor of the electric valve 1 while the valve body moves from the upper limit position to the lower limit position. For example, the lower limit position of the valve body is the fully closed position, and the upper limit position is the fully open position. The current position of the valve body is the number of pulses applied (increased or decreased) in the valve opening or closing direction to move the valve body between the fully closed position and the fully open position with the lower limit position of the valve body as 0 pulses. Of course, the number of pulses applied with the upper limit position of the valve body as 0 pulses may be counted.

[0046] (In-vehicle air conditioner) As an example of a refrigeration cycle in which the electric valve unit is mounted, the case where the electric valve (electric valve unit) after the shipment inspection is assembled as an expansion valve in an in-vehicle air conditioner will be described. The control unit 100 controls the opening and closing of the electric valve 1 according to an instruction from the air conditioner ECU while transmitting and receiving signals to and from a control device (air conditioner ECU) that controls the in-vehicle air conditioner, thereby controlling the flow rate of the refrigerant passing through the orifice 31d. At this time, at least the amount of hysteresis (or the corresponding number of pulses) measured in the inspection process is stored in the non-volatile memory (EEPROM 111e) of the control device 100, and it is desirable that the valve opening pulses are also stored.

[0047] When an electric valve unit is used as the expansion valve of an in-vehicle air conditioner, upon receiving an initialization instruction signal, the control device 100 rotates the stepping motor of the electric valve 1 in the valve closing direction by a number of pulses (for example, 700 pulses or more) obtained by adding a sufficient number of pulses for the rotor to surely collide with the stopper (anti-rotation) to the maximum number of pulses (for example, 500 pulses) that the electric valve 1 can control, to perform an initialization process (initialization operation of the electric valve 1) (finding the initial position of 0 pulses). In the case of an electric valve without a stopper, the position where the valve body is seated on the valve seat and stationary is regarded as the position where it collides with the stopper.

[0048] Note that, instead of the initialization process of rotating the stepping motor of the electric valve 1 in the valve closing direction, an initialization process of rotating it in the valve opening direction may be performed. Also, when the current position (number of pulses) etc. of the stepping motor of the electric valve 1 are stored in the EEPROM 111e, the information can be read from the EEPROM 111e and used. When the control device 100 does not know the current position (number of pulses) of the stepping motor of the electric valve 1, initialization may be executed by receiving support for changing the valve opening degree from a higher-level control device such as an air conditioner ECU.

[0049] Normally, the microcomputer 111b of the control device 100 controls the valve opening degree of the electric valve 1 based on a control signal transmitted from an air conditioner ECU (hereinafter sometimes simply referred to as the ECU) via a communication bus (for example, a LIN bus) which is a signal transmission and reception line. However, when receiving a power-off signal or a sleep mode transition signal from the ECU, for example, it can stop the operation of the electric valve 1 that is operating and store the valve opening degree information of the electric valve 1 at that time (current) and the rotation direction (of the stepping motor of the electric valve 1) in the EEPROM 111e. Also, an abnormal end flag for notifying the end state of the control device 100 such as a sudden power-off due to a short circuit or disconnection of a lead wire etc. is prepared in advance in the microcomputer 111b, and the microcomputer 111b can also store the state of the abnormal end flag in the EEPROM 111e.

[0050] Also, if the valve opening degree of the electric valve 1 (i.e., the current position (pulse number) of the stepping motor of the electric valve 1) and the rotation direction of the stepping motor are transmitted from the control device 100 via the LIN bus, the valve opening degree and the rotation direction can also be transmitted (known) to the ECU 116 via the LIN bus.

[0051] (Measurement of valve opening pulses and hysteresis amount by the measuring device) Next, the measurement of the hysteresis amount using a measuring device composed of the control device 100 and the inspection device 200 will be described. The measurement of the hysteresis amount by the measuring device is carried out before shipment in combination with the corresponding control device 100 after the electric valve 1 is completed. The electric valve 1 and the control device 100 used for the measurement are shipped in association with each other.

[0052] FIG. 3 is a flowchart showing a flow for measuring the hysteresis amount. FIGS. 4 and 5 are hysteresis diagrams showing the relationship between the drive pulses input to the stepping motor of the electric valve 1 and the flow rate. Since there are individual differences in the hysteresis amount due to, for example, the backlash of the gear train or the conversion mechanism of the electric valve 1, the measurement of the hysteresis amount is performed for each electric valve 1.

[0053] First, the ECU 116, which is a measurement control unit, determines in step S101 of FIG. 3 whether the hysteresis amount has been measured for the electric valve 1 to be measured. Since the information indicating that the hysteresis amount has been measured is described in the EEPROM 111e in the control device 100 of the electric valve 1 to be measured, the ECU 116 can confirm whether the hysteresis amount has been measured for the electric valve 1 to be measured by reading this information. If the hysteresis amount has been measured for the electric valve 1 to be measured (judgment Yes), the flow immediately ends. On the other hand, if the hysteresis amount has not been measured for the electric valve 1 to be measured (judgment No), the flow proceeds to step S102.

[0054] The ECU 116 determines whether the valve opening operation after initialization has been executed in step S102. If the valve opening operation after initialization has not been executed (judgment No), the process immediately ends. On the other hand, if the valve opening operation after initialization has been executed (judgment Yes), the process proceeds to step S103.

[0055] The valve opening operation after initialization will be described. When the ECU 116 outputs an initialization instruction to the electric valve 1 via the control device 100, from the valve open state, a drive pulse of a predetermined number of pulses is input to the stepping motor, causing the valve body 33 to move in the valve closing direction (arrow A in Fig. 4). At this time, the flow meter 204 of the control device 100 measures the amount of air flowing through the electric valve 1 (step S103). When the amount of air measured by the flow meter 204 is zero, the valve is in the closed state. At this time, the valve body 33 remains stationary at the position where it stopped at this closed valve position (initialization), which is the initial position (0 pulses) of the electric valve 1.

[0056] From the closed valve state, in order to open the valve, the ECU 116 increases the number of pulses by 1 pulse each time and inputs a drive pulse to the stepping motor of the electric valve 1 via the control device 100 (arrow B in Fig. 4), and each time the flow meter 204 measures the amount of air flowing through the electric valve 1.

[0057] In step S104, the ECU 116 determines whether the flow rate measured by the flow meter 204 has reached a predetermined value or more. Here, when the number of pulses exceeds a certain value (when the number of pulses reaches 9 pulses along arrow C in Fig. 4), it is assumed that the flow meter 204 of the control device 100 measures a flow rate exceeding zero. If the ECU 116 determines that the flow rate is less than the predetermined value, the process returns to step S102.

[0058] On the contrary, if the ECU 116 determines that the flow rate measured by the flow meter 204 has reached a predetermined value or more (when the number of pulses reaches 10 pulses in Fig. 4), in step S105, the number of pulses - 1 when the flow rate reaches a predetermined value or more is determined as the valve opening pulse (here 9 pulses), and it is stored in the EEPROM 111e of the control device 100. The above is the valve opening operation after initialization.

[0059] The number of pulses from the initial position to the valve opening point in this embodiment includes backlash of a gear train, a conversion mechanism, etc., relative displacement between the valve shaft 32 and the valve body 33 as described later, and the number of pulses corresponding to the operation from the start of the operation of the valve body to the predetermined flow rate.

[0060] The backlash of the gear train, the conversion mechanism, etc. corresponds to the hysteresis amount α described later, and the relative displacement between the valve shaft 32 and the valve body 33 corresponds to the valve closing pressing amount δ. The valve closing pressing amount δ is mostly the sliding distance between the slide plate 40 and the outer periphery of the large-diameter portion 32b of the valve shaft 32, but also includes elastic deformation of metal materials such as the valve shaft, the valve body, and the valve seat portion. Therefore, the valve opening pulse is the number of pulses corresponding to (hysteresis amount α + valve closing pressing amount δ). Hereinafter, α (and α1, α2 described later) will be described as the number of pulses corresponding to the hysteresis amount, and δ will be described as the number of pulses corresponding to the valve closing pressing amount.

[0061] In other words, when the motor is rotated in the valve opening direction from the position (initial position) where it stopped at initialization, after driving the backlash and the relative displacement, the valve body operates in the valve opening direction, and then reaches the valve opening point.

[0062] Note that the backlash of the gear train, the conversion mechanism, etc. includes the backlash of the gears and the screw play of the conversion mechanism, and as described later, the backlash of the gear train, the conversion mechanism, etc. may change over time due to wear or the like.

[0063] Next, the ECU 116 determines whether or not the valve closing operation was executed in step S106. If the valve closing operation has not been executed, it waits for the valve closing operation to start. On the other hand, when the valve closing operation has been executed (that is, when the valve body 33 is driven in the valve opening direction and then the stepping motor stops, and subsequently the valve body 33 is driven in the valve closing direction: see FIG. 5), the flow proceeds to step S107.

[0064] The closing operation will be described. Referring to FIG. 5, when the ECU 116 outputs a closing operation instruction to the electric valve 1 via the control device 100, drive pulses are input to the stepping motor, and the valve body 33 moves in the closing direction from the current valve opening position. At this time, the flow meter 204 of the control device 100 measures the amount of air flowing through the electric valve 1 (initial flow rate) (step S107).

[0065] The ECU 116 increases the number of drive pulses input to the electric valve 1 via the control device 100 by one pulse at a time in the closing direction (arrow D in FIG. 5), and each time the flow meter 204 measures the amount of air flowing through the electric valve 1.

[0066] In this embodiment, the graph in FIG. 5 continues from the graph in FIG. 4, and the pulse number 0 in FIG. 5 corresponds to the pulse number 10 (i.e., the valve opening pulse) in FIG. 4, but the pulse number 0 in FIG. 5 may be the valve opening pulse +1.

[0067] In step S108, the ECU 116 determines whether the flow rate measured by the flow meter 204 is less than a predetermined value (a flow rate that has changed by a predetermined amount relative to the initial flow rate). If the flow rate measured by the flow meter 204 is not less than the predetermined value, the flow returns to step S106.

[0068] Here, when the flow rate measured by the flow meter 204 is less than the predetermined value (when the pulse number becomes 6 pulses in FIG. 5), in step S109, the ECU 116 sets the pulse number -1 when the flow rate becomes less than the predetermined value as the hysteresis amount α (here, 5 pulses) and stores it in the EEPROM 111e of the control device 100. The above is the closing operation. Then, the flow ends.

[0069] When an electric valve unit is used as the expansion valve of an in-vehicle air conditioner, by using the above-described valve opening pulse and hysteresis amount α for the valve opening amount control of the electric valve unit, highly accurate flow rate control can be achieved.

[0070] (Operation of the electric valve) The operation of the motor-operated valve 1 according to this embodiment in a state connected to the refrigeration cycle will be described. Assume that the first pipe 51 and the second pipe 52 are connected to the refrigeration cycle, and the first pipe 51 is the inlet-side pipe and the second pipe 52 is the outlet-side pipe. Also, the valve opening direction refers to the direction in which the valve body 33 separates from the valve seat 31e, and the valve closing direction refers to the direction in which the valve body 33 approaches the valve seat 31e.

[0071] When the control device 100 receives an instruction from the ECU of the refrigeration cycle or the like to adjust the refrigerant flow rate to achieve the set temperature (that is, when the operation instruction information is input so that the valve body 33 moves by the target movement amount), the control device 100 outputs drive pulses to the stepping motor of the motor-operated valve 1. Here, considering the reduction ratio of the drive mechanism from the target movement amount of the valve body 33 determined according to the adjusted refrigerant flow rate, the target rotation angle of the rotor 13 of the stepping motor is determined. The number of drive pulses for realizing this target rotation angle is referred to as the target pulse number. The calculation of the target pulse number is performed by the microcomputer 111b.

[0072] Here, when the valve body 33 moves in the valve closing direction and then further moves in the valve closing direction (the same direction), or when the valve body 33 moves in the valve opening direction and then further moves in the valve opening direction (the same direction), since it is not necessary to consider hysteresis, the control device 100 outputs drive pulses corresponding to the target pulse number to the stepping motor of the motor-operated valve 1. As a result, the rotor 13 of the stepping motor rotates by the target rotation angle.

[0073] On the other hand, when the valve body 33 moves in the closing direction and then stops, and moves in the opening direction (reverse direction), or when the valve body 33 moves in the opening direction and then stops, and moves in the closing direction (reverse direction), it is necessary to consider the hysteresis of the drive mechanism. In such a case, the microcomputer 111b adds the hysteresis amount α (5 pulses) stored in the EEPROM 111e to the target pulse number β to obtain the effective pulse number γ, and the control device 100 outputs a drive pulse of the effective pulse number γ to the stepping motor of the electric valve 1 instead of the target pulse number. As a result, the rotor 13 of the stepping motor rotates beyond the target rotation angle considering the hysteresis, but the valve body 33 accurately reaches the target position.

[0074] Specifically, the control device 100 inputs a drive pulse of the effective pulse number γ, which is obtained by adding the hysteresis amount α (5 pulses) stored in the EEPROM 111e and the target pulse number β required for the valve body 33 to move from the position of point F to point G, to the stepping motor according to the hysteresis diagram shown in FIG. 6. Thereby, the valve body 33 can accurately reach the target position (point H), and the fluid with the target flow rate can pass through the electric valve 1. Note that when the stepping motor is driven in the opening direction and then moves in the closing direction, the effective pulse number γ can be obtained in the same way by adding the obtained hysteresis amount α to the target pulse number.

[0075] (Closing operation) When the drive shaft 14 rotates in the closing direction when the valve body 33 is at an arbitrary position (excluding the closed position), it is decelerated through the gear train of the speed reduction unit 20 and transmitted to the male screw shaft 27. The rotational motion transmitted to the male screw shaft 27 is converted into an axial motion through the conversion mechanism of the speed reduction unit 20, whereby the male screw shaft 27 is displaced downward together with the final gear 26. Even when the final gear 26 is displaced in the axial direction, the meshing with the second transmission gear 25 does not come off.

[0076] When the male screw shaft 27 is displaced downward, the valve shaft 32 moves downward by being pushed through the ball 37. When the valve shaft 32 moves downward, the bellows 38 expands, and the valve body 33 moves downward while being pushed by the coil spring 39, and the tapered surface 33d seats on the valve seat 31e. At this time, the coil spring 39 exerts a buffering effect to weaken the impact during seating.

[0077] Furthermore, when the valve shaft 32 rotates, the valve shaft 32 descends and the coil spring 39 is compressed, and the tapered surface 33d is pressed against the valve seat 31e with a predetermined biasing force. At this time, since the slide plate 40 slides along the outer periphery of the large-diameter portion 32b of the valve shaft 32, the relative displacement between the valve shaft 32 and the valve body 33 is allowed against the biasing force of the coil spring 39. As described above, since a predetermined preload is applied to ensure the closed valve state, the flow of the refrigerant from the first pipe 51 through the valve chamber C to the second pipe 52 is blocked. The electric valve 1 in FIG. 1 is in such a state (i.e., the closed valve state).

[0078] Also, during this period, since the fluid pressure in the valve chamber C acts on the outer surface of the bellows 38, if a fluid pressure equal to or higher than a predetermined value acts, the bellows 38 can be made to act in the contracting / expanding direction, and the valve body 33 can be moved in the opening direction together with the valve shaft 32.

[0079] (Opening valve operation) When the valve body 33 is at an arbitrary position (excluding the fully open valve position), when a drive pulse is output from the control device 100 to the stepping motor and the drive shaft 14 rotates in the opening valve direction, it is decelerated through the gear train of the speed reduction unit 20 and transmitted to the male screw shaft 27.

[0080] The rotational motion transmitted to the male screw shaft 27 is converted into an axial motion through the conversion mechanism of the speed reduction unit 20, whereby the male screw shaft 27 is displaced upward together with the final gear 26.

[0081] When the male screw shaft 27 is displaced upward, the force pressing the valve shaft 32 in the valve closing direction disappears. Therefore, while the bellows 38 receiving the refrigerant pressure in the valve chamber C contracts and extends, the valve shaft 32 also rises. When the valve shaft 32 rises, the slide plate 40 is locked to the flange portion 32c of the valve shaft 32, and thereafter, since the valve body 33 also rises together with the valve shaft 32, the tapered surface 33d separates from the valve seat 31e.

[0082] At this time, the refrigerant that has entered the valve chamber C from the first pipe 51 passes through the gap between the tapered surface 33d and the valve seat 31e and flows out to the second pipe 52 through the orifice 31d. Since the gap between the tapered surface 33d and the valve seat 31e changes according to the rotation angle of the drive shaft 14, by adjusting the rotation angle of the drive shaft 14, the amount of refrigerant flowing from the first pipe 51 to the second pipe 52 can be adjusted.

[0083] (Time-dependent change of the electric valve) By the way, the backlash of the gear train, conversion mechanism, etc. of the electric valve 1 changes over time due to wear or the like, and generally increases. Therefore, it is assumed that the amount of hysteresis obtained initially changes as the electric valve 1 is used. In contrast, the control device of the present embodiment can cope with the change in the amount of hysteresis over time.

[0084] More specifically, through experiments and simulations, for example, the change in the amount of hysteresis with respect to the integrated value of the drive pulses input to the stepping motor is obtained in advance, a table or correlation formula associating the integrated value with the change in the amount of hysteresis is determined, and it is stored in the EEPROM 111e.

[0085] FIG. 7 is a graph showing the association between the integrated value of the drive pulses and the amount of hysteresis. Each time the control device 100 of the electric valve 1 outputs a drive pulse to the stepping motor, it counts the number of pulses, collates the integrated value of the number of pulses with the table or correlation formula stored in the EEPROM 111e, and determines the amount of hysteresis.

[0086] Specifically, in the example of FIG. 7, when the integrated value of the number of pulses is between 0 and PN1, the amount of hysteresis is set to α1. Also, when the integrated value of the number of pulses is between PN2 and PN3, the amount of hysteresis is set to α2. The same applies hereinafter. Note that the amount of hysteresis may be linearly increased as the integrated value increases. Further, in addition to the integrated value of the number of pulses, the amount of lubricating oil supplied to the motor-operated valve 1, the load at the time of valve closing, etc. may be measured to adjust the amount of hysteresis.

[0087] By thus determining the amount of hysteresis according to the integrated value of the number of pulses, even if a change over time occurs in the motor-operated valve 1, the valve body can be controlled with high precision.

[0088] (Modification example) FIGS. 8 and 9 are hysteresis diagrams according to a modification example of the present embodiment. According to the movable range of the valve body 33 of the motor-operated valve 1, the minimum number of pulses PMN and the maximum number of pulses PMX that can be input to the stepping motor are determined as prescribed values. Here, when drive pulses having a number of pulses below the minimum number of pulses PMN or above the maximum number of pulses PMX are input to the stepping motor, a detuning phenomenon may occur and control may become impossible. This modification example can address such a problem.

[0089] For example, in FIG. 8, when attempting to input a drive pulse with a target number of pulses PA to the stepping motor to drive the valve body 33 that has been driven in the valve closing direction in the valve opening direction, the control device 100 inputs an operation instruction pulse with an effective number of pulses obtained by adding the amount of hysteresis α to the target number of pulses PA to the stepping motor in a manner of adding from the current position (current pulse value). However, when PA + α > PMX, there is a risk of a detuning phenomenon occurring by inputting the drive pulse with the calculated effective number of pulses to the stepping motor.

[0090] Similarly, in FIG. 9, when attempting to input drive pulses of the target pulse number PB to drive the valve body 33 that was being driven in the valve opening direction in the valve closing direction, the control device 100 inputs drive pulses of the effective pulse number (PB + α) obtained by adding the hysteresis amount α to the target pulse number PB to the stepping motor in a manner of subtracting from the current position (current pulse value). However, when the current position - (PB + α) < PMN, there is a risk of a detuning phenomenon occurring by inputting drive pulses of the effective pulse number to the stepping motor.

[0091] Therefore, when the control device 100 calculates the effective pulse numbers (PA + α) and (PB + α), if PA + α > PMX, it inputs drive pulses of the pulse number (PA' + α) that becomes the pulse number PMX to the stepping motor, and if the current position - (PB + α) < PMN, it inputs drive pulses of the pulse number (PB' + α) that becomes the pulse number PMN to the stepping motor. Thereby, the detuning phenomenon of the stepping motor can be suppressed.

[0092] (Modification 2) The number of pulses from the valve closed state to the valve opening point includes the hysteresis amount α (5 pulses in the above-described embodiment) and the valve closing pressing amount δ (4 pulses in the above-described embodiment). Since the flow rate of the fluid passing through the motorized valve between the pulse numbers PMN and (PMN + δ) is below a predetermined flow rate (substantially zero flow rate), it is not necessary to strictly adhere to PMN = 0 for the drive pulses input to the stepping motor. Also, since the pulse number PMN corresponds to the position (initial position) where initialization stopped, inputting the pulse number PMN to the stepping motor causes a load on the gear and screw parts. Therefore, in the above-described control, when attempting to input drive pulses of the target pulse number PB (or PB + α) {that is, when (the current position - (PB + α) becomes less than or equal to the pulse number PMN)}, drive pulses that exceed the pulse number PMN and are less than or equal to PMN + δ can be input to the stepping motor. For example, when the valve closing pressing amount δ is 1 pulse or more, the pulse number may be input so as to become PMN + 1. By performing such control, the load on the gear and screw parts can be reduced, and power consumption and wear can be reduced.

[0093] Regardless of the above embodiments, various embodiments or modifications can be applied to the present invention.

Description of Reference Numerals

[0094] 1 Electric valve 10 Driving unit 20 Reduction unit 30 Valve mechanism unit 31 Valve body 32 Valve shaft 33 Valve element 100 Control device 200 Inspection device

Claims

1. A control device for an electric valve, comprising: a valve body that is movable in a direction toward or away from a valve seat; a stepping motor that operates by inputting a drive pulse; a drive mechanism that drives the valve body by a drive force output from the stepping motor; a non-volatile storage unit; and a control unit that drives the stepping motor in response to operation instruction information input from an external device, The storage unit stores a hysteresis amount, when the control unit moves the valve body in a direction different from the previous moving direction based on operation instruction information input from the outside, the control unit inputs to the stepping motor a drive pulse having an effective pulse number obtained by adding a pulse number corresponding to the hysteresis amount stored in the storage unit to a target pulse number corresponding to a target movement amount of the valve body, the control unit stops the stepping motor after moving the valve disc in one direction, determines the flow rate of the fluid passing between the valve disc and the valve seat at that time as an initial flow rate, and thereafter determines the flow rate of the fluid each time the number of drive pulses input to the stepping motor to move the valve disc in the other direction is increased, and stores in the storage unit, as the amount of hysteresis, the number of pulses minus 1 at which the flow rate that has changed from the initial flow rate first becomes equal to or greater than a predetermined amount. A control device for an electric valve.

2. When the control unit is to move the valve body in the same direction as the immediately preceding moving direction based on operation instruction information input from the outside, the control unit inputs drive pulses of the target pulse number to the stepping motor.

2. The control device for an electric valve according to claim 1.

3. The hysteresis amount is changed in response to an integrated value of the number of drive pulses input to the motor-operated valve. The control device for an electric valve according to claim 1 .

4. when a value obtained by adding the effective number of pulses to the current value exceeds a specified value, or when a value obtained by subtracting the effective number of pulses from the current value falls below a specified value, a drive pulse of the specified value is input to the stepping motor. The control device for an electric valve according to claim 1 .

5. when a value obtained by subtracting the effective number of pulses from the current value falls below a specified value, a drive pulse exceeding the specified value and equal to or less than a value obtained by adding a number of pulses corresponding to a valve-closing pressure to the specified value is input to the stepping motor.

2. The control device for an electric valve according to claim 1.

6. a valve body that is movable in a direction toward or away from a valve seat, a stepping motor that operates by inputting a drive pulse, a drive mechanism that drives the valve body by a drive force output from the stepping motor, a non-volatile storage unit, and a control unit that drives the stepping motor in response to operation instruction information input from an external device, The storage unit stores a hysteresis amount, when the control unit moves the valve body in a direction different from the previous moving direction based on operation instruction information input from the outside, the control unit inputs to the stepping motor a drive pulse having an effective pulse number obtained by adding a pulse number corresponding to the hysteresis amount stored in the storage unit to a target pulse number corresponding to a target movement amount of the valve body, the control unit stops the stepping motor after moving the valve disc in one direction, determines the flow rate of the fluid passing between the valve disc and the valve seat at that time as an initial flow rate, and thereafter determines the flow rate of the fluid each time the number of drive pulses input to the stepping motor to move the valve disc in the other direction is increased, and stores in the storage unit, as the amount of hysteresis, the number of pulses minus 1 at which the flow rate that has changed from the initial flow rate first becomes equal to or greater than a predetermined amount. A motor-operated valve.

7. A control device according to any one of claims 1 to 5, and an electric valve. The motor-operated valve unit is characterized by the above.

Images