Electric valve control device and electric valve control system

Abstract

To attain downsizing and space saving of a system, and to maintain compatibility with a conventional system.SOLUTION: A pulse converter 10 includes an analog input 11 to which an analog signal indicating a valve opening of an electronic expansion valve 30 is input, a communication port 25 which can receive an opening instruction from a plurality of devices by communication, a microcomputer 18 which converts the analog signal input to the analog input 11 or the opening instruction received by the communication port 25 into a drive pulse, and a driving circuit 24 for driving the electronic expansion valve 30 on the basis of the drive pulse. The microcomputer 18 converts the opening instruction input from the communication port 25 into the drive pulse preferentially over the analog signal input from the analog input 11.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an electric valve control device that controls the valve opening degree of an electric valve such as an electronic expansion valve, and to an electric valve control system that includes the electric valve control device. [Background technology]

[0002] For example, motor-operated valves such as electronic expansion valves are used in refrigerators and chillers for semiconductor manufacturing equipment. This type of motor-operated valve can be precisely controlled to open and close by using a stepping motor.

[0003] Such motor-operated valves are driven and controlled by converting an analog signal output from a control device such as a temperature regulator into a pulse signal using a pulse drive device (also called a pulse output unit or pulse converter) (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-220451 Summary of the Invention [Problem to be solved by the invention]

[0005] In the configuration described in Patent Document 1, one pulse driver and one control device are required for one motor-operated valve. Therefore, if multiple motor-operated valves are required, for example, because there are multiple temperature adjustment locations, multiple pulse drivers and control devices are required, which complicates the wiring process and increases the size of the system.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to achieve a system that is compact and space-saving, while maintaining compatibility with conventional systems. [Means for solving the problem]

[0007] The invention made to solve the above problem comprises an input unit to which an analog signal indicating the valve opening of an electric valve is input, a communication unit capable of receiving valve opening information indicating the valve opening of the electric valve from a plurality of devices using a predetermined communication protocol, a control unit that converts the analog signal or the valve opening information into a drive pulse, and a drive circuit that drives the electric valve based on the drive pulse, wherein the control unit converts the valve opening information input from the communication unit into the drive pulse in priority to the analog signal input from the input unit. [Effects of the Invention]

[0008] According to the present invention, since the communication unit is provided, one-to-one connection is not required, which reduces wiring and enables the system to be made smaller and more space-saving. In addition, since the input unit for inputting analog signals remains, compatibility with conventional systems can be maintained. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic configuration diagram of an electric valve control system including an electric valve control device according to an embodiment of the present invention; [Figure 2] FIG. 2 is a schematic configuration diagram of the motor-operated valve control device shown in FIG. [Figure 3] This is a diagram showing the output pattern output to a motor-operated valve driven by a 1-2 phase excitation method, in a table and in an output waveform. [Figure 4] 3 is a flowchart of a communication operation of the pulse converter shown in FIG. 2. [Figure 5] 3 is a timing chart showing an example of operation of the pulse converter shown in FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0010] An electric valve control device according to one embodiment of the present invention will be described. Fig. 1 is a schematic diagram of an electric valve control system including the electric valve control device according to this embodiment. Fig. 2 is a schematic diagram of the electric valve control device shown in Fig. 1.

[0011] The motor-operated valve control system 1 shown in Fig. 1 includes a pulse converter 10, a control device (CNT) 20, and an electronic expansion valve 30. In the example of Fig. 1, there are three pulse converters 10, denoted by reference numerals 10a to 10c, three CNTs 20, denoted by reference numerals 20a to 20c, and three electronic expansion valves 30, denoted by reference numerals 30a to 30c, but the number of each device is not limited to three. The pulse converter 10 functions as the motor-operated valve control device according to this embodiment.

[0012] The pulse converters 10a to 10c and the CNTs 20a to 20c are connected by communication lines CL. In this embodiment, a daisy chain connection is used, in which the CNTs 20a, 20b, and 20c are connected in order to the pulse converters 10c, 10b, and 10a. For the daisy chain connection, communication standards such as RS485 and RS422 can be used. A bus connection or ring connection may also be used. These connection configurations do not have a one-to-one correspondence between the pulse converters 10 and the CNTs 20, so the amount of wiring required for communication can be reduced.

[0013] Pulse converter 10 and CNT 20 may also be connected by analog signal line AL. In Fig. 1, pulse converter 10a and CNT 20a can be connected by analog signal line AL1, pulse converter 10b and CNT 20b can be connected by analog signal line AL2, and pulse converter 10c and CNT 20c can be connected by analog signal line AL3.

[0014] As shown in FIG. 2, the pulse converter 10 includes an analog input 11, an I / V conversion circuit 12, an operational amplifier circuit 14, a microcomputer 18, a power supply circuit 22, a drive circuit 24, a communication port 25, and a communication circuit 26.

[0015] The I / V conversion circuit 12 converts the signal current (valve position signal) relating to the opening of the motor-operated valve input from the analog input 11 into a voltage and outputs it to the operational amplifier circuit 14. This valve position signal current is output from the CNT 20 as a current of, for example, 4 to 20 mA. An analog signal line AL is connected to the analog input 11, and the valve position signal current output from the CNT 20, that is, the analog signal, is input. In other words, the analog input 11 functions as an input unit that inputs an analog signal that indicates the valve position of the electronic expansion valve 30 (motor-operated valve).

[0016] The operational amplifier circuit 14 converts the valve opening signal voltage output from the I / V conversion circuit 12 into a voltage value suitable for the microcomputer 18 and outputs it to the microcomputer 18 .

[0017] The microcomputer 18 includes an A / D conversion circuit 34, a CPU (Central Processing Unit) 36, an I / O circuit 38, a ROM (Read Only Memory) 40, and a RAM (Random Access Memory) 42.

[0018] The A / D conversion circuit 34 converts the valve opening signal voltage input to the microcomputer 18 from an analog signal to a digital signal.

[0019] The CPU 36 converts the valve opening signal converted into a digital signal by the A / D conversion circuit 34 or an opening instruction input from the communication circuit 26, which will be described later, into a drive pulse for driving the electronic expansion valve 30. The CPU 36 then controls the valve opening of the electronic expansion valve 30 using the converted drive pulse via the I / O circuit 38 and the drive circuit 24. The CPU 36 also prioritizes the opening instruction input from the communication circuit 26 over the valve opening signal converted into a digital signal by the A / D conversion circuit 34, as will be described later.

[0020] That is, the CPU 36 functions as a control unit that converts a valve opening signal (analog signal) or an opening instruction (valve opening information) into a drive pulse. The CPU 36 converts the opening instruction (valve opening information) input from the communication port 25 into a drive pulse with priority over the valve opening signal (analog signal) input from the analog input 11 (input unit).

[0021] The I / O circuit 38 outputs drive pulses generated by the CPU 36 to the drive circuit 24. The ROM 40 stores, for example, a program for converting a valve opening signal or an opening instruction into a drive pulse, the above-mentioned communication control program, etc. The RAM 42 is used as temporary storage required for the CPU 36 to execute the program written in advance in the ROM 40.

[0022] The power supply circuit 22 generates a voltage required to operate the internal circuits of the microcomputer 18 and the like from an external power supply (not shown), and outputs the power supply voltage to the microcomputer 18 and the like.

[0023] The drive circuit 24 drives the electronic expansion valve 30 based on the drive pulses output from the microcomputer 18, and controls the valve opening degree.

[0024] The drive pulses output from the drive circuit 24 can be changed as appropriate depending on the type of electronic expansion valve 30. For example, if the electronic expansion valve 30 uses a stepping motor of a 1-2 phase excitation type, drive pulses are output in accordance with the excitation pattern shown in Fig. 3. In this embodiment, one pulse corresponds to one step rotation of the stepping motor of the electronic expansion valve 30. For example, if excitation patterns 1 to 8 in Fig. 3 are output from the drive circuit 24, eight pulses will be output.

[0025] The communication circuit 26 performs communication such as receiving instructions such as an opening instruction via the communication port 25. An opening instruction is instruction information for valve opening information of the electronic expansion valve 30, and is transmitted from the control device 20. The communication circuit 26 communicates with the CNT 20 and the like using a communication protocol based on communication standards such as the above-mentioned RS485 and RS422. A communication line CL is connected to the communication port 25. In other words, the communication port 25 functions as a communication unit that can receive an opening instruction (valve opening information) for the electronic expansion valve 30 (motorized valve) from the CNTs 20a, 20b, and 20c (multiple devices) using a predetermined communication protocol.

[0026] The CNT 20 is a control device that controls the pulse converter 10. The CNT 20 can be configured as a temperature regulator that outputs a control signal based on a temperature measured at a predetermined location in, for example, a refrigerator or a chiller for semiconductor manufacturing equipment. The CNT 20 can also be configured as, for example, a PLC (Programmable Logic Controller).

[0027] The electronic expansion valve 30 is one form of the motor-operated valve in this embodiment. The electronic expansion valve 30 is installed in a refrigerator, a chiller for semiconductor manufacturing equipment, etc. As described above, the electronic expansion valve 30 has a stepping motor, and its opening and closing is controlled by the pulse converter 10.

[0028] Next, the communication operation in the pulse converter 10 configured as described above will be described with reference to the flowchart of Fig. 4. The flowchart shown in Fig. 4 is executed by the microcomputer 18.

[0029] First, the microcomputer 18 determines whether an opening degree instruction has been received through communication (step S1). Receipt of an opening degree instruction through communication can be determined by whether an opening degree instruction has been input from the communication line CL via the communication port 25 and the communication circuit 26. As described above, this opening degree instruction is communication data indicating valve opening degree information of the electronic expansion valve 30.

[0030] If an opening instruction is received by communication in step S1 (step S1: YES), the microcomputer 18 resets the elapsed time and sets the communication opening priority flag to valid (step S2). The elapsed time indicates the time that has elapsed since the opening instruction was received. In step S2, the elapsed time is reset because the opening instruction was received in step S1. In this embodiment, the elapsed time is set to, for example, 1 to 3 minutes so that control does not immediately shift to analog.

[0031] The communication opening priority flag is a flag indicating that the opening instruction received from the communication port 25 takes priority over the analog signal input from the analog input 11, and is set to valid when an opening instruction is received. When the communication opening priority flag is set to valid, the opening instruction takes priority, and the analog signal input from the analog input 11 during the valid period is invalidated. In other words, no analog signal is accepted during the valid period of the communication opening priority flag.

[0032] On the other hand, if an opening instruction is not received through communication in step S1 (step S1: NO), the microcomputer 18 advances the elapsed time and proceeds to step S4 (step S3), which will be described later.

[0033] Next, the microcomputer 18 determines whether a predetermined time has elapsed or whether a command to reset the communication opening priority flag to invalid has been received (step S4). The command to reset the communication opening priority flag to invalid is a type of command input from the communication line CL via the communication port 25 and the communication circuit 26. When this command is received, the communication opening priority flag is reset, and the analog signal input from the analog input 11 becomes valid. In other words, the command to reset the communication opening priority flag to invalid functions as switching information that switches the input of the analog signal to be accepted.

[0034] In step S4, if a predetermined time has elapsed or if a command to set the communication opening priority flag to invalid has been received (step S4: YES), the microcomputer 18 resets the communication opening priority flag to invalid (step S5). On the other hand, if none of the conditions in step S4 are met (step S4: NO), the microcomputer 18 proceeds to step S6, which will be described later, without executing step S5.

[0035] Next, the microcomputer 18 determines whether the communication opening priority flag is enabled (step S6). If the communication opening priority flag is enabled (step S6: YES), the microcomputer 18 operates at the opening (communication instruction opening) included in the opening instruction received by the communication circuit 26 (step S7). That is, the microcomputer 18 generates pulses the number of which is based on the opening received by the communication circuit 26, and outputs them to the drive circuit 24.

[0036] On the other hand, if the communication opening priority flag is invalid (step S6: NO), the microcomputer 18 operates with the analog signal input from the analog input 11 (step S8). That is, the microcomputer 18 generates pulses the number of which is based on the digital value converted from the analog signal by the A / D conversion circuit 34, and outputs the pulses to the drive circuit 24.

[0037] Next, an example of operation of the pulse converter 10 will be described with reference to Fig. 5. Fig. 5 is a timing chart showing an example of operation of the pulse converter 10. Fig. 5 shows the opening of the electronic expansion valve 30 (expansion valve opening), the analog signal input from the analog input 11, the opening instruction (communication instruction) input from the communication port 25, and the communication opening priority flag (High: communication priority, Low: analog input priority).

[0038] First, assume that the expansion valve opening is 0% and the communication opening priority flag is at a low level (analog priority) in the initial state. Then, at time A, an instruction to change the opening to 100% is input via analog input 11. At this time, the communication opening priority flag is set to analog input priority, so the pulse converter 10 treats the analog signal input from analog input 11 as valid, outputs the number of pulses based on the instruction for 100% opening, and changes the expansion valve opening to 100%.

[0039] Next, at time B, when an instruction to change the opening to 50% is input via analog input 11, the communication opening priority flag is set to analog input priority, so the pulse converter 10 treats the analog signal input from analog input 11 as valid. Therefore, the pulse converter 10 outputs the number of pulses based on the instruction for 50% opening, and the expansion valve opening changes to 50%.

[0040] Next, at time C, a command to change the opening to 100% is input via communication. Then, the communication opening priority flag changes to High (communication priority). When the opening command is received via communication, as described in the flowchart of FIG. 4, steps S1: YES, S2, S4: NO, S6: YES, and S7 are executed, and the pulse converter 10 treats the opening commanded by the communication as valid. Therefore, the pulse converter 10 outputs the number of pulses based on the command to open 100%, and the expansion valve opening changes to 100%.

[0041] Next, at time D, when a communication instruction to change the opening to 75% is input, the pulse converter 10 treats the received communication instruction as valid because the communication opening priority flag is set to communication priority. Therefore, the pulse converter 10 outputs the number of pulses based on the instruction for 75% opening, and the expansion valve opening changes to 75%. Note that from time C to time E (described later) the communication opening priority flag is set to communication priority, so the analog signal input from the analog input 11 is not accepted (is ignored).

[0042] Next, at time E, if a predetermined time has elapsed since time D, the communication opening priority flag changes to Low (analog input priority). Therefore, the flowchart of Fig. 4 is executed in the order of step S1: NO, step S3, step S4: YES, step S5, step S6: NO, and step S8. Therefore, the pulse converter 10 accepts the analog signal input from the analog input 11 at time E, treats it as valid, outputs the number of pulses based on the instruction for 25% opening indicated by the analog input 11 at time E, and changes the expansion valve opening to 25%.

[0043] That is, the microcomputer 18 (controller) waits for a predetermined time period after input of the opening instruction (valve opening information) to receive the opening instruction (the information) and does not accept the analog input 11 (analog signal). After the predetermined time period has elapsed, the microcomputer 18 (controller) accepts the analog input 11 (analog signal).

[0044] Next, at time F, when an instruction to change the opening to 50% is input via analog input 11, the communication opening priority flag is set to analog input priority, so the pulse converter 10 treats the analog signal input from analog input 11 as valid. Therefore, the pulse converter 10 outputs the number of pulses based on the instruction for 50% opening, and the expansion valve opening changes to 50%.

[0045] Next, at time G, a communication instruction to change the opening to 0% is input. Then, the communication opening priority flag changes to High. Therefore, the flowchart is executed in the same manner as at time C, and the pulse converter 10 treats the received communication instruction as valid, outputs pulses in the number based on the instruction to change the opening to 0%, and the expansion valve opening changes to 0%.

[0046] Next, at time H, when a priority cancellation instruction (disable communication opening priority) is received via communication, the communication opening priority flag changes to Low. In other words, the priority cancellation instruction functions as switching information, and the input of an analog signal can be switched to be accepted.

[0047] Therefore, the flowchart is executed in the same manner as at time E, and the pulse converter 10 treats the opening indicated by the analog input 11 at time H as valid. Therefore, the pulse converter 10 outputs the number of pulses based on the instruction for 50% opening of the analog input at time H, and the expansion valve opening changes to 50%. In other words, the microcomputer 18 (controller) switches to accept input of the analog input 11 (analog signal) in response to the priority cancellation instruction (switching information) received by the communication circuit 26 (communicator) even within the predetermined time period.

[0048] According to this embodiment, the pulse converter 10 includes an analog input 11 to which an analog signal indicating the valve opening degree of the electronic expansion valve 30 is input, a communication port 25 capable of receiving opening degree instructions from a plurality of devices via communication, a microcomputer 18 that converts the analog signal input to the analog input 11 or the opening degree instruction received by the communication port 25 into a drive pulse, and a drive circuit 24 for driving the electronic expansion valve 30 based on the drive pulse. The microcomputer 18 converts the opening degree instruction input from the communication port 25 into a drive pulse, giving priority to the analog signal input from the analog input 11.

[0049] By configuring the pulse converter 10 as described above, one-to-one connections are not required, and multiple wiring can be consolidated into a dedicated communication line CL for communication connections. This allows for a more compact and space-saving system. Furthermore, since the analog input 11 for inputting an analog signal remains, compatibility with conventional systems can be maintained.

[0050] Furthermore, after receiving an opening instruction, the microcomputer 18 waits for a predetermined period of time to receive a subsequent opening instruction, and does not accept an analog signal input from the analog input 11. By doing so, communication can be unconditionally given priority for a certain period of time even if no communication is being sent or received. By providing a certain period of time to wait for communication reception, the load on the communication processing capacity of the microcomputer 18 and the external control device caused by frequent switching between the analog input 11 and the communication port 25 can be reduced.

[0051] Furthermore, the microcomputer 18 can accept an analog signal input from the analog input 11 after a predetermined time has elapsed. This makes it easy to automatically enable the analog input without manually switching it over. Therefore, for example, when communication-based control is temporarily interrupted, it is possible to prevent forgetting to switch back to the analog input 11.

[0052] Furthermore, the microcomputer 18 is configured to switch to accept an analog signal input from the analog input 11 in response to a priority cancellation instruction (disabling communication opening priority) received by the communication circuit 26 even within a predetermined time period. This allows the analog input to be validated at any time. Therefore, control by analog input can be performed at any time.

[0053] The motor-operated valve control system 1 also includes a pulse converter 10 and a CNT 20 that outputs a valve opening to the pulse converter 10. The system includes a plurality of pulse converters 10 and at least one CNT 20. The communication port 25 of the pulse converter 10 is daisy-chain connected to the communication ports 25 or CNT 20 of other pulse converters 10.

[0054] By configuring the motor-operated valve control system 1 as described above, the pulse converters 10 and the CNTs 20 are connected in a daisy chain, so that the amount of wiring required for communication can be minimized.

[0055] In the above-described embodiment, the communication port 25 and communication circuit 26 are primarily used to input instructions to the pulse converter 10, but they can also be used for output from the pulse converter 10. For example, the control status, such as the current valve opening value and various set values, may be read and output. In this case, for example, the pulse converter 10 may receive a read command, and in response, transmit the control status from the communication port 25 to the party that sent the read command. In other words, the communication port 25 (communication unit) can transmit the control status controlled by the microcomputer 18 (control unit) to the outside.

[0056] Furthermore, in the above-described embodiment, the CNT 20 was a temperature controller or the like, but a terminal device or the like that is temporarily added for maintenance work such as starting up the device or verifying malfunctions may also be inserted into the communication line CL. In this embodiment, a daisy chain connection (or bus connection) is used, making it easy to temporarily insert such a terminal device, and it is also possible to control multiple pulse converters 10 from one terminal device. This enables centralized control from an external device, allowing motor-operated valves to be controlled as desired, and increasing the flexibility of the system and control.

[0057] 1 , it is also possible to mix pulse converter 10a connected to analog input 11 with pulse converters 10b and 10c connected only via communication port 25. In this way, pulse converter 10 corresponding to important electronic expansion valves 30 can be connected via both analog input 11 and communication port 25 for redundancy, while other electronic expansion valves 30 can be configured for communication only. Furthermore, for pulse converters connected via both analog input 11 and communication port 25, connecting communication port 25 also makes it easier to perform the maintenance work described above.

[0058] Furthermore, if only the communication port 25 is connected, it is meaningless even if the analog input 11 becomes valid after a certain time has elapsed. If the analog input 11 is not connected, it is impossible to distinguish between an analog signal of "0" and an open terminal. Therefore, there is a risk of malfunction as the input becomes "0" after a certain time has elapsed. There is also a risk of malfunction due to fluctuations in the input. Therefore, it is possible to set in advance whether or not to use the analog input 11 using a switching means such as a switch.

[0059] As a specific example, a dip switch is provided in the pulse converter 10 to enable switching between use and non-use of the analog input 11. For example, the analog input 11 is set to be used when shipped from the factory, and when the user does not want to use the analog input 11, the dip switch is switched to be set to be non-use.

[0060] If the analog input 11 is set to unused with the DIP switch, the microcomputer 18 will not enable the analog input 11 even after a predetermined time has elapsed (indefinite communication standby). In other words, the DIP switch switches to a communication priority mode, and the microcomputer operates according to opening instructions sent via communication at all times without referencing the communication priority flag. Even if an instruction to disable the communication priority flag is given, the DIP switch setting takes priority, so operation will continue according to opening instructions sent via communication.

[0061] That is, a switching means for switching between using and not using the analog input 11 may be provided, and the microcomputer 18 may convert the drive pulse based only on the valve opening information when the analog input 11 is switched to not being used. In this way, malfunctions due to the analog input 11 not being connected can be prevented.

[0062] Furthermore, the communication connection is not limited to a wired connection such as a daisy chain connection or a bus connection, but may be wireless. If it is wireless, the communication line CL is not required, which allows for further miniaturization.

[0063] Furthermore, the present invention is not limited to the above-described embodiments. That is, a person skilled in the art can implement various modifications in accordance with conventional knowledge without departing from the gist of the present invention. As long as such modifications still comprise the configuration of the motor-operated valve control device and motor-operated valve control system of the present invention, they are of course included in the scope of the present invention. [Explanation of symbols]

[0064] 1. Electric valve control system 10 Pulse converter (electric valve control device) 11 Analog input (input section) 18 Microcomputer (control unit) 20 Control device 24 Drive circuit 25 Communication port (communication section) 30 Electronic expansion valve (motorized valve)

Claims

1. an input unit to which an analog signal indicating an instruction to change the valve opening of the motor-operated valve is input; a communication unit capable of receiving valve opening information including an opening instruction, which is an instruction to change the valve opening of the motor-operated valve, from a plurality of control devices that transmit the valve opening information using a predetermined communication protocol; a control unit that converts the analog signal or the valve opening information into a drive pulse; a drive circuit that drives the motor-operated valve based on the drive pulse, the control unit converts the valve opening information input from the communication unit into the drive pulse in priority to the analog signal input from the input unit. An electric valve control device characterized by:

2. 2. The electrically operated valve control device according to claim 1, wherein the control unit waits for reception of the valve opening information for a predetermined period of time after the valve opening information is input, and does not accept the analog signal.

3. The electrically operated valve control device according to claim 2, wherein the control unit receives the analog signal after the predetermined time has elapsed.

4. 3. The electrically operated valve control device according to claim 2, wherein the control unit switches to accept the input of the analog signal according to the switching information received by the communication unit even during the predetermined time period.

5. The electrically operated valve control device according to claim 1, wherein the communication unit is capable of transmitting a control state of the control unit to an external device.

6. The motor-operated valve control device according to any one of claims 1 to 5; a control device that outputs the analog signal to the motor-operated valve control device and transmits the valve opening degree information to the motor-operated valve control device, A plurality of the electrically operated valve control devices are provided, and at least one of the control devices is provided; The communication unit of the electric valve control device is connected to the communication unit of another electric valve control device or the control device by a daisy chain connection or a bus connection. An electric valve control system.

7. 7. The motor-operated valve control system according to claim 6, wherein an input section of one of the plurality of motor-operated valve control devices is connected to the control device.

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