JP7796082B2 - Electric valve control device and electric valve control system - Google Patents

Description

The present invention relates to an electric valve control device that controls the valve opening of an electric valve such as an electronic expansion valve, and an electric valve control system equipped with the electric valve control device.

For example, electric valves such as electronic expansion valves are used in refrigerators and chillers for semiconductor manufacturing equipment. These types of electric valves can be precisely controlled to open and close by using a stepping motor.

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

JP 2011-220451 A

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

The present invention aims to make the system more compact and space-saving while maintaining compatibility with conventional systems.

The invention made to solve the above problem comprises an input unit to which an analog signal indicating the valve opening of a motor-operated valve is input, a communication unit capable of receiving valve opening information indicating the valve opening of the motor-operated valve from multiple 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 motor-operated valve based on the drive pulse, and is characterized in that the control unit converts the valve opening information input from the communication unit into the drive pulse with priority over the analog signal input from the input unit.

According to the present invention, by providing a communications unit, one-to-one connections are not required, reducing wiring and enabling systems to be made more compact and space-saving. Furthermore, by retaining the input unit for analog signals, compatibility with conventional systems can be maintained.

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; 2 is a schematic diagram of the motor-operated valve control device shown in FIG. 1; FIG. This is a diagram showing the output pattern output to an electric valve driven by a 1-2 phase excitation method, in a table and in an output waveform. 3 is a flowchart of a communication operation of the pulse converter shown in FIG. 2. 3 is a timing chart showing an example of the operation of the pulse converter shown in FIG. 2 .

This section describes an electric valve control device according to one embodiment of the present invention. Figure 1 is a schematic diagram of an electric valve control system equipped with an electric valve control device according to this embodiment. Figure 2 is a schematic diagram of the electric valve control device shown in Figure 1.

The motor-operated valve control system 1 shown in Figure 1 includes a pulse converter 10, a control device (CNT) 20, and an electronic expansion valve 30. In the example shown in Figure 1, there are three pulse converters 10, reference numerals 10a-10c, three CNTs 20, reference numerals 20a-20c, and three electronic expansion valves 30, reference numerals 30a-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.

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

In addition, pulse converter 10 and CNT20 may be connected by analog signal line AL. In FIG. 1, pulse converter 10a and CNT20a can be connected by analog signal line AL1, pulse converter 10b and CNT20b can be connected by analog signal line AL2, and pulse converter 10c and CNT20c can be connected by analog signal line AL3.

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.

The I/V conversion circuit 12 converts the signal current (valve position signal) related 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. The analog signal line AL is connected to the analog input 11, and the valve position signal current output from the CNT 20, i.e., the analog signal, is input. In other words, the analog input 11 functions as an input section that receives an analog signal indicating the valve position of the electronic expansion valve 30 (motor-operated valve).

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.

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.

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.

The CPU 36 converts the valve opening signal converted into a digital signal by the A/D conversion circuit 34 or the 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 drive circuit 24. Furthermore, the CPU 36 prioritizes the opening instruction input from the communication circuit 26, as will be described later, over the valve opening signal converted into a digital signal by the A/D conversion circuit 34.

In other words, the CPU 36 functions as a control unit that converts a valve opening signal (analog signal) or 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, giving priority to the valve opening signal (analog signal) input from the analog input 11 (input unit).

The I/O circuit 38 outputs drive pulses generated by the CPU 36 to the drive circuit 24. ROM 40 stores, for example, programs for converting valve opening signals and opening instructions into drive pulses, as well as the communication control program described above. RAM 42 is used as temporary storage required for the CPU 36 to execute programs previously written to ROM 40.

The power supply circuit 22 generates the voltage required to operate internal circuits such as the microcomputer 18 from an external power source (not shown) and outputs the power supply voltage to the microcomputer 18, etc.

The drive circuit 24 drives the electronic expansion valve 30 based on the drive pulses output from the microcomputer 18, controlling the valve opening degree.

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 with a 1-2 phase excitation method, drive pulses are output according to the excitation pattern shown in Figure 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 Figure 3 are output from the drive circuit 24, eight pulses will be output.

The communication circuit 26 communicates via the communication port 25, receiving instructions such as opening degree instructions. An opening degree instruction is instruction information for the valve opening degree 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 RS485 and RS422 mentioned above. The communication port 25 is connected to the communication line CL. In other words, the communication port 25 functions as a communication unit that can receive opening degree instructions (valve opening degree information) for the electronic expansion valve 30 (motorized valve) from the CNTs 20a, 20b, and 20c (multiple devices) using a predetermined communication protocol.

CNT20 is a control device that controls the pulse converter 10. CNT20 can be configured as a temperature regulator that outputs a control signal based on the temperature measured at a specific location in, for example, a refrigerator or a chiller for semiconductor manufacturing equipment. CNT20 can also be configured as, for example, a PLC (Programmable Logic Controller).

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

Next, the communication operation of the pulse converter 10 configured as described above will be explained with reference to the flowchart in Figure 4. The flowchart shown in Figure 4 is operated by the microcomputer 18.

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

If an opening instruction is received via communication in step S1 (step S1: YES), the microcomputer 18 resets the elapsed time and sets the communication opening priority flag to enabled (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.

The communication opening priority flag is a flag that indicates 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 enabled when an opening instruction is received. When the communication opening priority flag is set to enabled, the opening instruction takes priority, and analog signals input from the analog input 11 during the valid period are invalidated. In other words, analog signals are not accepted while the communication opening priority flag is valid.

On the other hand, if no opening instruction is received via communication in step S1 (step S1: NO), the microcomputer 18 advances the elapsed time and proceeds to step S4 (described below) (step S3).

Next, the microcomputer 18 determines whether a predetermined elapsed 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 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 acceptable.

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 does not execute step S5 and proceeds to step S6, which will be described later.

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). In other words, the microcomputer 18 generates a number of pulses based on the opening received by the communication circuit 26 and outputs them to the drive circuit 24.

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

Next, an example of the operation of the pulse converter 10 described above will be described with reference to Figure 5. Figure 5 is a timing chart showing an example of the operation of the pulse converter 10. Figure 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).

First, assume that the expansion valve opening is initially 0%, and the communication opening priority flag is at low level (analog priority). 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%.

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%.

Next, at time C, a communication instruction to change the opening to 100% is input. This changes the communication opening priority flag to High (communication priority). When the opening instruction 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 instruction received via communication as valid. Therefore, the pulse converter 10 outputs the number of pulses based on the instruction for 100% opening, and the expansion valve opening changes to 100%.

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 (it is ignored).

Next, at time E, assuming that a predetermined time has elapsed since time D, the communication opening priority flag changes to Low (analog input priority). Therefore, the flowchart in 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, and outputs the number of pulses based on the 25% opening indicated by the analog input 11 at time E, changing the expansion valve opening to 25%.

In other words, the microcomputer 18 (controller) waits to receive an opening instruction (valve opening information) for a predetermined period of time after the opening instruction is input, and does not accept analog input 11 (analog signal). Furthermore, the microcomputer 18 (controller) accepts analog input 11 (analog signal) after the predetermined period of time has elapsed.

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%.

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

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 system is switched to accept analog signal input.

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 50% opening instruction of the analog input at time H, and the expansion valve opening changes to 50%. In other words, the microcomputer 18 (controller) switches to accepting input of the analog input 11 (analog signal) even within the specified time period in response to the priority cancellation instruction (switching information) received by the communication circuit 26 (communication unit).

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 via communication from multiple devices, 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.

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, because the analog input 11, which accepts analog signals, remains, compatibility with conventional systems is maintained.

In addition, after receiving an opening instruction, the microcomputer 18 waits for a predetermined period of time to receive subsequent opening instructions and does not accept analog signals input from the analog input 11. This allows communication to be unconditionally prioritized for a certain period of time even if no communication is being sent or received. By setting a certain period of time to wait for communication reception, the load on the communication processing capacity of the microcomputer 18 and external control devices caused by frequent switching between the analog input 11 and the communication port 25 can be reduced.

In addition, 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, if control via communication is temporarily interrupted, it is possible to prevent forgetting to switch back to the analog input 11.

In addition, the microcomputer 18 is configured to switch to accepting analog signals 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 specified time period. This allows the analog input to be enabled at any time. Therefore, control by analog input is possible at any time.

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

By configuring the motor-operated valve control system 1 as described above, the pulse converter 10 and CNT 20 are connected in a daisy chain, minimizing the amount of wiring required for communication.

In the above-described embodiment, the communication port 25 and communication circuit 26 were primarily used to input instructions and the like 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 setting 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.

In addition, while in the above-described embodiment the CNT 20 was a temperature regulator or the like, a terminal device or the like may be inserted into the communication line CL to temporarily add a device for maintenance work such as starting up the device or verifying malfunctions. 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 a single terminal device. This enables centralized control from external devices, allowing motor-operated valves to be controlled as desired, and increasing the flexibility of the system and control.

Furthermore, as in the configuration shown in Figure 1 where CNTs 20b and 20c are removed, 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 converters 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 only communicate. Furthermore, for pulse converters connected via both analog input 11 and communication port 25, connecting the communication port 25 also makes it easier to perform the maintenance work described above.

Furthermore, if only the communication port 25 is connected, it is meaningless for the analog input 11 to become valid after a certain time has passed. If the analog input 11 is not connected, it is impossible to distinguish between an analog signal of "0" or an open terminal. As a result, there is a risk of the input becoming "0" after a certain time has passed, resulting in a malfunction. There is also a risk of malfunction due to input fluctuations. Therefore, it is possible to set in advance whether or not to use the analog input 11 using a switching device such as a switch.

As a specific example, a dip switch can be provided on the pulse converter 10 to enable or disable the use of the analog input 11. For example, the analog input 11 is set to be used when shipped from the factory, and if the user does not want to use the analog input 11, the dip switch can be switched to disable it.

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 specified time has elapsed (standby for communication indefinitely). In other words, the DIP switch switches to 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.

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

Furthermore, the communication connection is not limited to wired connections such as daisy chain connections or bus connections, but can also be wireless. Wireless connections eliminate the need for communication lines CL, allowing for further miniaturization, etc.

Furthermore, the present invention is not limited to the above-described embodiments. In other words, those 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 within the scope of the present invention.

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 unit)
30 Electronic expansion valve (motorized valve)

Claims (7)

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: The electric valve control device described in claim 1, characterized in that the control unit waits to receive the valve opening information for a predetermined period of time after the valve opening information is input, and does not accept the analog signal. The motor-operated valve control device described in claim 2, characterized in that the control unit accepts the analog signal after the predetermined time has elapsed. The motor-operated valve control device described in claim 2, characterized in that the control unit switches to accept input of the analog signal based on switching information received by the communication unit even during the predetermined time period. The motor-operated valve control device described in claim 1, characterized in that the communication unit is capable of transmitting the control status of the control unit to an external device. 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. The motor-operated valve control system described in claim 6, characterized in that the input section of one of the motor-operated valve control devices is connected to the control device.