Electronic expansion valve control device

Abstract

To provide a control device for an electronic expansion valve without using a driver that is provided by a manufacturer of the electronic expansion valve.SOLUTION: A control device (10) for an electronic expansion valve (50) comprises a regulator section (21), an arithmetic section (31) and a pulse output section (41). The regulator section (21) calculates a target aperture of the electronic expansion valve (50) based on an input value and a preset value of a control target amount. The arithmetic section (31) calculates the number of drive pulses for bringing an aperture of the electronic expansion valve (50) into the target aperture. The pulse output section (41) outputs the drive as many pulses as the number that is calculated by the arithmetic section (31). A PLC consists of the regulator section (21), the arithmetic section (31) and the pulse output section (41).SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a control device for an electronic expansion valve.

Background Art

[0002] An electronic expansion valve is provided in a refrigerant circuit of a refrigeration device and is used to control the flow of refrigerant. The electronic expansion valve includes a valve body and a stepping motor. The stepping motor includes a rotor formed integrally with the valve body and a stator having a coil. When the stepping motor rotates, the opening degree of the electronic expansion valve changes.

[0003] Patent Document 1 discloses a control device for an electronic expansion valve. This control device includes a driver for driving the stepping motor of the electronic expansion valve. The driver outputs a pulsed excitation current toward the coil of the stepping motor. The stepping motor of the electronic expansion valve rotates by receiving the excitation current output by the driver.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] To drive one electronic expansion valve, one driver is required. The driver for driving the electronic expansion valve is usually provided by the manufacturer of the electronic expansion valve. Therefore, when a plurality of electronic expansion valves are provided in a refrigeration device, it is necessary to purchase the same number of drivers as the electronic expansion valves and install them in the refrigeration device. Therefore, there is a risk of complicating the configuration and increasing the price of the control device for the electronic expansion valve.

[0006] The purpose of this disclosure is to realize a control device for an electronic expansion valve without using a driver provided by the manufacturer of the electronic expansion valve. [Means for solving the problem]

[0007] A first aspect of the present disclosure is a control device (10) that controls the opening degree of an electronic expansion valve (50) equipped with a stepping motor (52) based on a control target quantity, which is a physical quantity that changes according to the opening degree of the electronic expansion valve (50), and comprises a controller unit (21) configured by a PLC that calculates a target opening degree of the electronic expansion valve (50) based on an input value and a set value of the control target quantity; a calculation unit (31) configured by a PLC that calculates the number of drive pulses required to set the opening degree of the electronic expansion valve (50) to the target opening degree calculated by the controller unit (21); and a pulse output unit (41) configured by a PLC that outputs the number of drive pulses calculated by the calculation unit (31).

[0008] The control device (10) of the first embodiment comprises a controller unit (21), a calculation unit (31), and a pulse output unit (41). The controller unit (21), the calculation unit (31), and the pulse output unit (41) are configured by a PLC (Programmable Logic Controller). Therefore, it becomes possible to control the opening degree of the electronic expansion valve (50) without using a driver provided by the manufacturer of the electronic expansion valve (50).

[0009] A second aspect of the present disclosure, in the first aspect, includes a contactless relay (16) that operates based on a drive pulse output by the pulse output unit (41) and supplies an excitation current to the stepping motor (52) of the electronic expansion valve (50).

[0010] In the second embodiment, the contactless relay (16) operates based on the drive pulse output by the pulse output unit (41). The excitation current output by the contactless relay (16) is supplied to the coil of the stepping motor (52). The stepping motor (52) of the electronic expansion valve (50) rotates in response to the excitation current supplied from the contactless relay (16).

[0011] A third aspect of the present disclosure is configured in the first or second aspect to control the opening degree of multiple types of electronic expansion valves (50) with different pulse widths for the drive pulses of a stepping motor (52), wherein the pulse output unit (41) has a pulse output interval that is the greatest common divisor of the pulse widths of the drive pulses for each of the multiple types of electronic expansion valves (50).

[0012] In the third embodiment, the pulse width of the drive pulses for all electronic expansion valves (50) controlled by the control device (10) is an integer multiple of the pulse output interval in the pulse output unit (41). Therefore, the pulse output unit (41) can output drive pulses with pulse widths required by each of the multiple types of electronic expansion valves (50). Accordingly, the control device (10) in this embodiment can control the opening degree of multiple types of electronic expansion valves (50) with different pulse widths for the drive pulses of the stepping motor (52). [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a perspective view of an electronic expansion valve controlled by a control device. [Figure 2] Figure 2 is a block diagram showing the configuration of the control device. [Figure 3] Figure 3 shows the drive pulses output by the control device. [Modes for carrying out the invention]

[0014] Embodiments will now be described. The control device (10) of this embodiment is configured to individually control the opening degree of a plurality of electronic expansion valves (50). Furthermore, the control device (10) of this embodiment is configured to control the opening degree of multiple types of electronic expansion valves (50) with different pulse widths of drive pulses.

[0015] -Electronic expansion valve- The electronic expansion valve (50) controlled by the control device (10) of this embodiment will be described with reference to Figure 1.

[0016] The electronic expansion valve (50) comprises a main body (51) and a stepping motor (52). The main body (51) houses a valve body and a valve seat. The stepping motor (52) comprises a stator (52a) and a rotor. The stator (52a) houses a coil and is provided to surround the upper part of the main body (51). The coil housed in the stator (52a) is four-phase. The rotor is formed integrally with the valve body and is housed in the main body (51). When the rotor of the stepping motor (52) rotates, the valve body, which is integrated with the rotor, moves, and the opening degree of the electronic expansion valve (50) changes.

[0017] The main body (51) of the electronic expansion valve (50) is connected to a first connecting pipe section (53) and a second connecting pipe section (54). The first connecting pipe section (53) extends laterally from the main body section (51). The second connecting pipe section (54) extends downward from the main body section (51).

[0018] The plurality of electronic expansion valves (50) controlled by the control device (10) of this embodiment include a first electronic expansion valve (50a) and a second electronic expansion valve (50b). The stepping motor (52) of the first electronic expansion valve (50a) is driven in a two-phase excitation manner. The drive pulse of the stepping motor (52) of the first electronic expansion valve (50a) has a pulse width PW1 of 10 ms. The stepping motor (52) of the second electronic expansion valve (50b) is driven in a one-to-two-phase excitation manner. The drive pulse of the stepping motor (52) of the second electronic expansion valve (50b) has a pulse width PW2 of 20 ms.

[0019] -Control device- The control device (10) of this embodiment will be described with reference to Figure 2.

[0020] The control device (10) of this embodiment can individually control the opening degree of up to eight electronic expansion valves (50). Figure 2 shows the case in which the control device (10) of this embodiment controls the first electronic expansion valve (50a) and the second electronic expansion valve (50b). Note that the number of electronic expansion valves (50) that the control device (10) can control is merely an example.

[0021] The control device (10) includes one PLC (15) and a plurality of non-contact relays (16). PLC is an abbreviation for "Programmable Logic Controller". The PLC (15) is a device for realizing a relay control circuit by software. In the control device (10) of the present embodiment, the PLC (15) includes a PID unit (20), a CPU unit (30), and an output unit (40).

[0022] 〈PID Unit〉 The PID unit (20) forms a plurality (eight in this embodiment) of regulators (21). The plurality of regulators (21) each correspond to one electronic expansion valve (50). In the control device (10) shown in FIG. 2, the first regulator (21a) corresponds to the first electronic expansion valve (50a), and the second regulator (21b) corresponds to the second electronic expansion valve (50b).

[0023] Input values PV and a set value SV of a controlled variable related to the corresponding electronic expansion valve (50) are input to the regulator (21). The controlled variable is a physical quantity that changes according to the opening degree of the electronic expansion valve (50). Examples of the controlled variable include the superheat degree of the refrigerant at the outlet of the evaporator, the evaporation pressure of the refrigerant in the evaporator, and the temperature of the air cooled in the evaporator. The input value PV is a measured value of a sensor provided in a refrigerant circuit or the like, or a value calculated using the measured value of the sensor. The set value SV is a value set by a user or administrator of the refrigeration device.

[0024] The controller unit (21) calculates the target opening degree of the corresponding electronic expansion valve (50) based on the input value PV and set value SV of the controlled quantity. In this embodiment, the controller unit (21) calculates the target opening degree of the corresponding electronic expansion valve (50) by PID control using the input value PV and set value SV of the controlled quantity. The controller unit (21) calculates an opening degree such that the input value PV of the input controlled quantity approaches the set value SV, or an opening degree such that the input value PV is maintained at the set value SV, and sets the calculated opening degree as the target opening degree of the electronic expansion valve (50). The opening degree of the electronic expansion valve (50) is expressed as a percentage, for example, with the fully closed state being 0% and the fully open state being 100%.

[0025] In the control device (10) shown in Figure 2, the first controller unit (21a) receives input values ​​PV and SV of a control target quantity that change according to the opening degree of the first electronic expansion valve (50a). The first controller unit (21a) calculates the target opening degree of the first electronic expansion valve (50a) by PID control using the input values ​​PV and SV of the control target quantity that have been input. The second controller unit (21b) receives input values ​​PV and SV of a control target quantity that change according to the opening degree of the second electronic expansion valve (50b). The second controller unit (21b) calculates the target opening degree of the second electronic expansion valve (50b) by PID control using the input values ​​PV and SV of the control target quantity that have been input.

[0026] <CPU Unit> The CPU unit (30) forms a plurality (eight in this embodiment) of calculation units (31). Each of the plurality of calculation units (31) corresponds to one electronic expansion valve (50). In the control device (10) shown in Figure 2, the first calculation unit (31a) corresponds to the first electronic expansion valve (50a), and the second calculation unit (31b) corresponds to the second electronic expansion valve (50b).

[0027] The calculation unit (31) reads the target opening degree calculated by the controller unit (21) corresponding to the same electronic expansion valve (50) from the controller unit (21). The calculation unit (31) also stores the current opening degree of the corresponding electronic expansion valve (50). The calculation unit (31) calculates the number of drive pulses required to bring the opening degree of the corresponding electronic expansion valve (50) to the target opening degree.

[0028] Specifically, the calculation unit (31) calculates the difference (opening difference) between the current opening degree of the corresponding electronic expansion valve (50) and the target opening degree read from the corresponding controller unit (21), and calculates the number of drive pulses corresponding to the calculated opening difference. For example, if the current opening degree of the corresponding electronic expansion valve (50) is 50% and the target opening degree read from the corresponding controller unit (21) is 70%, the calculation unit (31) calculates the number of drive pulses required to increase the opening degree of the electronic expansion valve (50) by the difference between the two, which is 20% (=70%-50%).

[0029] In the control device (10) shown in Figure 2, the first calculation unit (31a) calculates the difference (opening difference) between the current opening degree of the first electronic expansion valve (50a) and the target opening degree read from the first controller unit (21a), and calculates the number of drive pulses corresponding to the calculated opening difference. The second calculation unit (31b) also calculates the difference (opening difference) between the current opening degree of the second electronic expansion valve (50b) and the target opening degree read from the second controller unit (21b), and calculates the number of drive pulses corresponding to the calculated opening difference.

[0030] <Output Unit> The output unit (40) forms a plurality (eight in this embodiment) of pulse output sections (41). Each of the plurality of pulse output sections (41) corresponds to one electronic expansion valve (50). In the control device (10) shown in Figure 2, the first pulse output section (41a) corresponds to the first electronic expansion valve (50a), and the second pulse output section (41b) corresponds to the second electronic expansion valve (50b).

[0031] The pulse output unit (41) receives the "number of drive pulses" output by the calculation unit (31) corresponding to the same electronic expansion valve (50). The pulse output unit (41) outputs the same number of drive pulses as the input "number of drive pulses" by executing the pulse output function program.

[0032] In the control device (10) shown in Figure 2, the first pulse output unit (41a) outputs the same number of drive pulses as the number of drive pulses output by the first calculation unit (31a). As shown in Figure 3, the first pulse output unit (41a) outputs drive pulses to the stepping motor (52) of the first electronic expansion valve (50a) (specifically, to the coil of the stator (52a)). As described above, the stepping motor (52) of the first electronic expansion valve (50a) is driven by a two-phase excitation method. Therefore, the first pulse output unit (41a) outputs drive pulses corresponding to the two-phase excitation method. The stepping motor (52) of the first electronic expansion valve (50a) rotates once with eight drive pulses.

[0033] Furthermore, the second pulse output unit (41b) outputs the same number of drive pulses as the number of drive pulses output by the second calculation unit (31b). As shown in Figure 3, the second pulse output unit (41b) outputs drive pulses to the stepping motor (52) of the second electronic expansion valve (50b) (specifically, to the coil of the stator (52a)). As described above, the stepping motor (52) of the second electronic expansion valve (50b) is driven by a 1-2 phase excitation method. Therefore, the second pulse output unit (41b) outputs drive pulses corresponding to the 1-2 phase excitation method. The stepping motor (52) of the second electronic expansion valve (50b) rotates once with eight drive pulses.

[0034] In the pulse output unit (41) of this embodiment, the pulse output interval PW is the greatest common divisor of the pulse widths of the drive pulses in each of the multiple types of electronic expansion valves (50) controlled by the control device (10). The pulse output interval PW is the execution period time of the pulse output function program in the pulse output unit (41).

[0035] As described above, the drive pulse for the stepping motor (52) of the first electronic expansion valve (50a) has a pulse width PW1 of 10ms, and the drive pulse for the stepping motor (52) of the second electronic expansion valve (50b) has a pulse width PW2 of 20ms. Therefore, in the pulse output unit (41) of this embodiment, the pulse output interval PW is set to "10ms", which is the greatest common divisor of the pulse widths PW1 (=10ms) and PW2 (=20ms).

[0036] As shown in Figure 3, the pulse width PW1 of the drive pulse for driving the stepping motor (52) of the first electronic expansion valve (50a) is "1" times the pulse output interval PW of the first pulse output unit (41a). Therefore, the first pulse output unit (41a) generates one drive pulse by executing the pulse output function program once.

[0037] On the other hand, the pulse width PW2 of the drive pulse for driving the stepping motor (52) of the second electronic expansion valve (50b) is "twice" the pulse output interval PW of the second pulse output unit (41b). Therefore, the second pulse output unit (41b) generates one drive pulse by executing the pulse output function program twice.

[0038] <Contactless relay> As shown in Figure 2, one contactless relay (16) is provided for each phase of the coils constituting the stator (52a) of the stepping motor (52) of the electronic expansion valve (50). The first electronic expansion valve (50a) and the second electronic expansion valve (50b), each controlled by the control device (10) of this embodiment, have four phases of coils constituting the stator (52a) of the stepping motor (52). Therefore, in the control device (10) of this embodiment, four contactless relays (16) are provided for each of the first electronic expansion valve (50a) and the second electronic expansion valve (50b).

[0039] The contactless relay (16) operates based on a drive pulse input from the corresponding pulse output unit (41). The contactless relay (16) intermittently supplies excitation current to the stator (52a) of the stepping motor (52) of the corresponding electronic expansion valve (50) in conjunction with the drive pulse. The four contactless relays (16) corresponding to the first electronic expansion valve (50a) each operate based on a drive pulse input from the first pulse output unit (41a). The four contactless relays (16) corresponding to the second electronic expansion valve (50b) each operate based on a drive pulse input from the second pulse output unit (41b).

[0040] -Control device operation- In the control device (10) shown in Figure 2, the first controller unit (21a), the first calculation unit (31a), and the first pulse output unit (41a) correspond to the first electronic expansion valve (50a). The stepping motor (52) of the first electronic expansion valve (50a) rotates by an angle corresponding to the number of drive pulses output by the first pulse output unit (41a). As a result, the opening degree of the first electronic expansion valve (50a) becomes the target opening degree calculated by the first controller unit (21a).

[0041] Furthermore, in the control device (10) shown in Figure 2, the second controller unit (21b), the second calculation unit (31b), and the second pulse output unit (41b) correspond to the second electronic expansion valve (50b). The stepping motor (52) of the second electronic expansion valve (50b) rotates by an angle corresponding to the number of drive pulses output by the second pulse output unit (41b). As a result, the opening degree of the second electronic expansion valve (50b) becomes the target opening degree calculated by the second controller unit (21b).

[0042] -Features of the Embodiment- The control device (10) of this embodiment comprises a controller unit (21), a calculation unit (31), and a pulse output unit (41). The controller unit (21), the calculation unit (31), and the pulse output unit (41) are all composed of a PLC (Programmable Logic Controller). Therefore, it becomes possible to control the opening degree of the electronic expansion valve (50) without using a driver provided by the manufacturer of the electronic expansion valve (50).

[0043] Furthermore, in the control device (10) of this embodiment, the non-contact relay (16) operates based on the drive pulse output by the pulse output unit (41), and an excitation current is supplied from the non-contact relay (16) to the stator (52a) of the stepping motor (52) of the electronic expansion valve (50). Therefore, an excitation current of the magnitude necessary to rotate the stepping motor (52) of the electronic expansion valve (50) can be supplied to the stator (52a) of the stepping motor (52) of the electronic expansion valve (50) in accordance with the drive pulse output by the pulse output unit (41).

[0044] Furthermore, in the control device (10) of this embodiment, the pulse widths PW1 and PW2 of the drive pulses of all electronic expansion valves (50) controlled by the control device (10) are integer multiples of the pulse output interval PW in the pulse output unit (41). Therefore, the pulse output unit (41) can output drive pulses with pulse widths required by each of the multiple types of electronic expansion valves (50). Accordingly, the control device (10) of this embodiment can control the opening degree of multiple types of electronic expansion valves (50) with different pulse widths of drive pulses for the stepping motor (52).

[0045] Although embodiments have been described above, it should be understood that various modifications to the form and details are possible without departing from the spirit and scope of the claims. Furthermore, the designations "First," "Second," etc., in the specification and claims are used to distinguish the phrases to which these designations are attached, and do not limit the number or order of such phrases. [Industrial applicability]

[0046] As described above, this disclosure is useful for control devices for electronic expansion valves. [Explanation of Symbols]

[0047] 10 Control device 16 Contactless relay 21 Controller section 31 Arithmetic section 41. Pulse output section 50 Electronic expansion valve 52 Stepping motors

Claims

1. A control device (10) that controls the opening degree of an electronic expansion valve (50) equipped with a stepping motor (52) based on a control target quantity which is a physical quantity that changes according to the opening degree of the electronic expansion valve (50), A controller unit (21) is configured by a PLC and calculates the target opening degree of the electronic expansion valve (50) based on the input value and set value of the controlled quantity, A calculation unit (31) is configured by a PLC and calculates the number of drive pulses required to set the opening degree of the electronic expansion valve (50) to the target opening degree calculated by the controller unit (21), It comprises a PLC and a pulse output unit (41) that outputs a number of drive pulses calculated by the calculation unit (31), It is configured to control the opening degree of multiple types of electronic expansion valves (50) with different pulse widths for the drive pulses of the stepping motor (52), In the pulse output unit (41) described above, the pulse output interval is the greatest common divisor of the pulse widths of the drive pulses in each of the multiple types of electronic expansion valves (50), The pulse output unit (41) outputs the drive pulse by executing the pulse output function program. In the pulse output unit (41) described above, the pulse output interval is the execution period time of the pulse output function program. In the pulse output unit (41) described above, the number of times the pulse output function program is executed to output one of the drive pulses is set according to the pulse width of the drive pulse of the stepping motor (52) of the electronic expansion valve (50) which is the target of the drive pulse output. Control device.

2. The electronic expansion valve (50) is equipped with a non-contact relay (16) that operates based on the drive pulse output by the pulse output unit (41) and supplies an excitation current to the stepping motor (52) of the electronic expansion valve (50). The control device according to claim 1.

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