Control device for electronic expansion valve

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 integrally formed 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 in response to 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 and install the same number of drivers as the number of electronic expansion valves in the refrigeration device. This may lead to a complication in the configuration and an increase in the price of the control device for the electronic expansion valve.

[0006] An object of the present disclosure is to realize a control device for an electronic expansion valve without using a driver provided by a manufacturer of the electronic expansion valve.

Means for Solving the Problems

[0007] A first aspect of the present disclosure is a control device (10) that controls the opening degree of an electronic expansion valve (50) provided with a stepping motor (52) based on a control target quantity that is a physical quantity that changes according to the opening degree of the electronic expansion valve (50). The control device is configured by a PLC, and includes an adjustment meter unit (21) 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, an arithmetic unit (31) configured by a PLC that calculates the number of drive pulses for setting the opening degree of the electronic expansion valve (50) to the target opening degree calculated by the adjustment meter unit (21), and a pulse output unit (41) configured by a PLC that outputs the number of drive pulses calculated by the arithmetic unit (31).

[0008] The control device (10) of the first aspect includes an adjustment meter unit (21), an arithmetic unit (31), and a pulse output unit (41). The adjustment meter unit (21), the arithmetic unit (31), and the pulse output unit (41) are configured by a PLC (Programmable Logic Controller). Therefore, it is 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 is, in the first aspect, a non-contact relay (16) that operates based on the drive pulses output by the pulse output unit (41) and supplies an exciting current to the stepping motor (52) of the electronic expansion valve (50).

[0010] In the second aspect, the non-contact relay (16) operates based on the drive pulses output by the pulse output unit (41). The exciting current output by the non-contact relay (16) is supplied to the coil of the stepping motor (52). The stepping motor (52) of the electronic expansion valve (50) rotates by receiving the exciting current supplied from the non-contact relay (16).

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

[0012] In the third aspect, the pulse widths of the drive pulses of all the electronic expansion valves (50) controlled by the control device (10) are integer multiples of the output interval of the pulses in the pulse output unit (41). Therefore, the pulse output unit (41) can output drive pulses having pulse widths required by each of the plurality of types of electronic expansion valves (50). Accordingly, the control device (10) of this aspect can control the opening degrees of a plurality of types of electronic expansion valves (50) having different pulse widths of drive pulses of the stepping motor (52).

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0014] Embodiments will be described. The control device (10) of the present embodiment is configured to individually control the opening degrees of a plurality of electronic expansion valves (50). Further, the control device (10) of the present embodiment is configured to control the opening degrees of a plurality of types of electronic expansion valves (50) having different pulse widths of drive pulses.

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

[0016] The electronic expansion valve (50) includes a main body portion (51) and a stepping motor (52). A valve element and a valve seat are incorporated in the main body portion (51). The stepping motor (52) includes a stator (52a) and a rotor. The stator (52a) incorporates a coil and is provided so as to surround the upper portion of the main body portion (51). The coil incorporated in the stator (52a) has four phases. The rotor is formed integrally with the valve element and is incorporated in the main body portion (51). When the rotor of the stepping motor (52) rotates, the valve element integrated with the rotor moves, and the opening degree of the electronic expansion valve (50) changes.

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

[0018] The plurality of electronic expansion valves (50) controlled by the control device (10) of the present embodiment includes 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 method. 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 1-2 phase excitation method. 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 the present embodiment will be described with reference to FIG. 2.

[0020] The control device (10) of the present embodiment can individually control the opening degrees of up to eight electronic expansion valves (50). FIG. 2 shows the case where the control device (10) of the present 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 of "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). Each of the plurality of regulators (21) corresponds 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] An input value 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 adjustment meter unit (21) calculates the target opening degree of the corresponding electronic expansion valve (50) based on the input value PV of the controlled quantity and the set value SV. The adjustment meter unit (21) of the present embodiment calculates the target opening degree of the corresponding electronic expansion valve (50) by PID control using the input value PV of the controlled quantity and the set value SV. The adjustment meter 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, for example, as a percentage with the fully closed state being 0% and the fully open state being 100%.

[0025] In the control device (10) shown in FIG. 2, the input value PV of the controlled quantity and the set value SV that change according to the opening degree of the first electronic expansion valve (50a) are input to the first adjustment meter unit (21a). The first adjustment meter unit (21a) calculates the target opening degree of the first electronic expansion valve (50a) by PID control using the input value PV of the input controlled quantity and the set value SV. Also, the input value PV of the controlled quantity and the set value SV that change according to the opening degree of the second electronic expansion valve (50b) are input to the second adjustment meter unit (21b). The second adjustment meter unit (21b) calculates the target opening degree of the second electronic expansion valve (50b) by PID control using the input value PV of the input controlled quantity and the set value SV.

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

[0027] The arithmetic unit (31) reads out the target opening degree calculated by the adjustment meter unit (21) corresponding to the same electronic expansion valve (50) from that adjustment meter unit (21). Also, the arithmetic unit (31) stores the current opening degree of the corresponding electronic expansion valve (50). The arithmetic unit (31) calculates the number of drive pulses for making the opening degree of the corresponding electronic expansion valve (50) the target opening degree.

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

[0029] In the control device (10) shown in FIG. 2, the first arithmetic 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 regulator unit (21a), and calculates the number of drive pulses corresponding to the calculated opening difference. Further, the second arithmetic unit (31b) 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 regulator 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 units (41). Each of the plurality of pulse output units (41) corresponds to one electronic expansion valve (50). In the control device (10) shown in FIG. 2, the first pulse output unit (41a) corresponds to the first electronic expansion valve (50a), and the second pulse output unit (41b) corresponds to the second electronic expansion valve (50b).

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

[0032] In the control device (10) shown in FIG. 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 FIG. 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) makes one revolution with eight drive pulses.

[0033] Also, 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 FIG. 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) makes one revolution with eight drive pulses.

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

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

[0036] As shown in FIG. 3, the pulse width PW1 of the drive pulse for driving the stepping motor (52) of the first electronic expansion valve (50a) is "1 time" the output interval PW of the pulse 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 "2 times" the output interval PW of the pulse 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] 〈Non-contact relay〉 As shown in FIG. 2, the non-contact relays (16) are provided one by one corresponding to each phase of the coil constituting the stator (52a) of the stepping motor (52) of the electronic expansion valve (50). Each of the first electronic expansion valve (50a) and the second electronic expansion valve (50b) controlled by the control device (10) of the present embodiment has a 4-phase coil constituting the stator (52a) of the stepping motor (52). Therefore, in the control device (10) of the present embodiment, four non-contact relays (16) are provided corresponding to each of the first electronic expansion valve (50a) and the second electronic expansion valve (50b).

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

[0040] -Operation of the control device- In the control device (10) shown in FIG. 2, the first regulator 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 regulator unit (21a).

[0041] Also, in the control device (10) shown in FIG. 2, the second regulator 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 regulator unit (21b).

[0042] -Features of the embodiment- The control device (10) of this embodiment includes a regulator unit (21), a calculation unit (31), and a pulse output unit (41). The regulator 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 the driver provided by the manufacturer of the electronic expansion valve (50).

[0043] Also, in the control device (10) of the present embodiment, the non-contact relay (16) operates based on the drive pulse output by the pulse output unit (41), and an exciting 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 exciting current of a 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) corresponding to the drive pulse output by the pulse output unit (41).

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

[0045] Although the embodiments have been described above, it will be understood that various changes in form and detail can be made without departing from the spirit and scope of the claims. Also, the descriptions "first", "second",... in the specification and claims are used to distinguish the clauses to which these descriptions are attached, and do not limit even the number and order of those clauses.

Industrial Applicability

[0046] As described above, the present disclosure is useful for a control device for an electronic expansion valve.

Explanation of Signs

[0047] 10 Control device 16 Non-contact relay 21 Regulator unit 31 Arithmetic unit 41 Pulse output section 50 Electronic expansion valve 52 Stepping motor

Claims

1. A control device (10) for controlling the opening degree of an electronic expansion valve (50) provided with a stepping motor (52) based on a controlled variable which is a physical quantity that changes according to the opening degree of the electronic expansion valve (50), composed of a PLC, an adjustment meter unit (21) for calculating a target opening degree of the electronic expansion valve (50) based on an input value and a set value of the controlled variable, composed of a PLC, a calculation unit (31) for calculating the number of drive pulses for making the opening degree of the electronic expansion valve (50) the target opening degree calculated by the adjustment meter unit (21), and a pulse output unit (41) composed of a PLC for outputting the number of drive pulses calculated by the calculation unit (31). The control device.

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

3. Configured to control the opening degrees of a plurality of types of electronic expansion valves (50) having different pulse widths of drive pulses of the stepping motor (52), in the pulse output unit (41), the output interval of the pulses is the greatest common divisor of the pulse widths of the drive pulses in each of the plurality of types of electronic expansion valves (50). The control device according to claim 1 or 2.

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