JPH1137620A - Controller for motor expansion valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect malfunction of a motor expansion valve in the early stage and to take a countermeasure by taking a specified countermeasure against malfunction of a motor expansion valve when a decision is made the difference between a pre-state signal and a post-state signal does not exceed a specifeid threshold level otherwise taking no countermeasure. SOLUTION: After an operation signal for varying the valve opening is delivered to a motor expansion valve 6, a post-state signal outputted from current sensors 7, 8 is detected along with a pre-state signal outputted from the current sensors 7, 8 before the operation signal is outputted and a decision is made whether the difference between both signals exceeds a threshold level. If a decision is made repeatedly by specified times or more that the difference between the pre-state and post-state signals does not exceed the threshold level although the operation signal is outputted, an alarm is delivered to inform malfunction of the motor expansion valve 6. Consequently, malfunction of the motor expansion valve 6 can be detected in the early stage without requiring any unit test thereof and a countermeasure can be taken.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an electric expansion valve in a refrigeration system.

[0002]

2. Description of the Related Art When an electric expansion valve is used as a decompressor of a refrigeration system, the electric expansion valve may be clogged by sludge or the like. If clogging occurs, an optimal amount of reduced pressure cannot be obtained. In particular, HFC refrigerants and synthetic oils (ester oils,
When used in combination with ether oil or the like, sludge is likely to be generated, and clogging of the electric expansion valve is likely to occur.

If the opening of the electric expansion valve is clogged when the opening degree is adjusted by detecting the discharge pipe temperature, a delay in the rising speed until the opening degree reaches the optimum opening degree and a decrease in comfort occur. Also, without detecting the temperature of the discharge pipe,
In the case where the opening is set only by the instruction from the PU, if the clogging occurs, the overheating operation is performed. In the worst case, the system is down and the service call and the complaint are frequently generated.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a control device for an electric expansion valve which can detect a malfunction of the electric expansion valve at an early stage and cope with it.

[0005]

According to a first aspect of the present invention, there is provided a control apparatus for an electric expansion valve, comprising: a state sensor for detecting a state of a refrigerating apparatus and outputting a state signal; Before outputting the operation signal to change the valve opening degree to the valve, compare the previous state signal outputted by the state sensor with the state signal outputted by the state sensor after outputting the operation signal to the electric expansion valve. Determining means for determining whether the difference between the previous state signal and the rear state signal has exceeded a predetermined threshold value, and determining that the difference has not exceeded the predetermined threshold value. In the meantime, while performing a predetermined measure to cope with the operation failure of the electric expansion valve, when the determination means determines that the difference exceeds a predetermined threshold,
A treatment unit that does not perform the predetermined treatment.

According to the first aspect of the present invention, the state sensor detects a state of the refrigeration system.

The determination means determines that the state signal output by the state sensor after the output of the operation signal exceeds the threshold value from the previous state signal output by the state sensor before the operation signal is output. To determine whether it has changed.
When the determination means determines that the post-state signal has changed from the previous state signal by exceeding the threshold value, the treatment means does not perform a predetermined treatment. On the other hand, when the determination means determines that the post-state signal has not changed from the previous state signal by exceeding the threshold value, the treatment means performs a predetermined treatment for coping with a malfunction of the electric expansion valve.

When the difference between the post-state signal and the pre-state signal does not exceed the threshold value, it means that the valve opening of the electric expansion valve has not changed in accordance with the operation signal. This means that the electric expansion valve has malfunctioned. On the other hand, when the signal difference exceeds the threshold value, it means that the valve opening degree of the electric expansion valve has changed according to the operation signal.

Therefore, according to the present invention, the post-state signal and the pre-state signal are detected by the state sensor, and the judgment means judges whether or not the difference between the two signals exceeds the threshold value. This makes it possible to quickly detect whether or not the electric expansion valve has malfunctioned. Further, when the determining means determines that the electric expansion valve is malfunctioning, the treatment means can perform a predetermined measure for coping with the malfunction of the electric expansion valve. Therefore, according to the present invention, a malfunction of the electric expansion valve can be detected early and dealt with.

According to a second aspect of the present invention, in the electric expansion valve control device according to the first aspect, when the judgment by the judgment means is negative, the operation signal is output to the electric expansion valve again. A repetition means for causing the judgment means to make a judgment again, and a repetition number counting means for causing the treatment means to perform the predetermined treatment only when the number of repetitions by the repetition means reaches a predetermined number. And

According to a second aspect of the present invention, the repetition means causes the determination means to repeatedly determine whether or not the difference between the previous state signal and the rear state signal exceeds a threshold value, and the number of repetitions is a predetermined number. When the number of times has been reached, the repetition number counting means causes the treatment means to perform a predetermined treatment for dealing with a malfunction of the electric expansion valve.

Therefore, according to the second aspect of the present invention, when it is repeated a predetermined number of times that the post-state signal does not change beyond the threshold value even if the operation signal is output to the electric expansion valve, A predetermined measure is taken to cope with the malfunction of the electric expansion valve. Therefore, the detection of the operation failure of the electric expansion valve can be made highly reliable.

According to a third aspect of the present invention, in the electric expansion valve control device according to the first aspect, the treatment means performs a measure for avoiding an overload of the refrigeration circuit as the predetermined measure. It is characterized by being.

According to a third aspect of the present invention, when the judging means judges that the signal difference does not exceed the threshold value and the electric expansion valve has malfunctioned, the treating means sets the refrigeration circuit. Take measures to avoid overload. Therefore, the malfunction of the refrigeration circuit can be avoided in advance.

According to a fourth aspect of the present invention, in the control device for an electric expansion valve according to the first aspect, the treatment means is an alarm means for issuing an alarm as the predetermined treatment.

According to a fourth aspect of the present invention, when the determination means determines that the signal difference does not exceed the threshold value and the motor-operated expansion valve malfunctions, the treatment means controls the motor-operated expansion valve. An alarm is issued to warn of a malfunction. Accordingly, countermeasures such as parts replacement and repair can be performed so that the failure situation does not spread due to the failure of the electric expansion valve.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

FIG. 1 shows a refrigeration circuit of a refrigeration apparatus including an embodiment of a motor expansion valve control device according to the present invention. This refrigeration circuit includes a first heat exchanger 1, a second heat exchanger 2, a compressor 3
And a four-way switching valve 5 and an electric expansion valve 6.

The control device for the motor-operated expansion valve of this embodiment includes a discharge pipe temperature sensor 7 for detecting the temperature of the discharge pipe 3a of the compressor 3, a current sensor 8 for detecting the drive current of the compressor 3, Control device 10 to which a temperature signal from discharge pipe temperature sensor 7 and a current signal from current sensor 8 are input.
Having. The control device 10 controls the opening degree of the electric expansion valve 6 based on the temperature signal and the current signal. The discharge pipe temperature sensor 7 and the current sensor 8 constitute a state sensor for detecting the state of the refrigeration system.

FIG. 2 shows the structure of the electric expansion valve 6.
The electric expansion valve 6 has a step motor formed by a rotor 11 and a stator 12, and has a screw valve 13 fixed to the rotor 11 and having a rotation axis of the rotor 11 as a center axis. The stator 12 is fixed to the main body 15. The screw valve 13 is screwed into a screw hole 16 formed in the main body 15. The main body 15
Has a valve hole 17 having a tapered surface 17a facing the tip tapered surface 13a of the screw valve 13 at a position facing the screw hole 16. A joint pipe 20 is fixed to the valve hole 17, and another joint pipe 22 is fixed to a hole 21 formed in the main body 15 in a direction perpendicular to the rotation axis.

In the electric expansion valve 6 having the above configuration, the amount of rotation of the rotor 11 is determined by the number of pulses input to the stator 12, and the amount of rotation determines the tapered surface 17a facing the tip tapered surface 13a of the screw valve 13. Is controlled, and the valve opening is controlled.

Next, the operation of the electric expansion valve control device of this embodiment will be described with reference to the flowchart of FIG.

First, when the control of the electric expansion valve 6 is started, the process proceeds to step S1, and the control device 10 stores the temperature signal from the discharge pipe temperature sensor 7 and the current signal from the current sensor 8. The temperature signal and the current signal are the previous state signals. From the previous state signal, the temperature of the discharge pipe 3a and the drive current for driving the compressor 3 can be known. Next, proceeding to step S2, the control device 10 outputs a predetermined number of pulse signals to the electric expansion valve 6 based on the discharge pipe temperature and the drive current. This pulse signal is the operation signal.

Next, proceeding to step S3, the control device 10 obtains the temperature signal from the discharge pipe temperature sensor 7 and the current signal from the current sensor 8 again. The temperature signal and the current signal obtained at this time are post-state signals.
The control device 10 determines whether the signal difference between the rear state signal and the previous state signal exceeds a predetermined threshold, and determines that the signal difference has exceeded the predetermined threshold. Then, the process proceeds to step S4, and if it is determined that the signal difference does not exceed the predetermined threshold, the process proceeds to step S5.

The fact that the post-state signal has changed beyond the threshold value means that the electric expansion valve 6 has normally operated according to the input operation signal and the valve opening has changed. . Therefore, in this case, the process proceeds to step S4 and proceeds to the next control.

On the other hand, the fact that the change of the post-state signal from the pre-state signal did not exceed the threshold value means that the motor-operated expansion valve 6 did not operate normally in accordance with the input operation signal. That is, the change in the opening was insufficient. Therefore, in this case, the process proceeds to step S5, and the operation signal output operation in step S2 and the post-state signal in step S3 and the previous state signal in It is determined whether or not the determination that the difference from the status signal is equal to or less than the threshold value is repeated five times or more.

If it is determined in step S5 that the operation has been repeated five times or more, the flow advances to step S6 to output a failure warning signal for warning that a malfunction has occurred in the operation of the electric expansion valve 6.

On the other hand, if it is determined in step S5 that the output of the operation signal and the determination that the value is equal to or less than the threshold value are not repeated five times or more, the process returns to step S2.
An operation signal is output to the electric expansion valve 6 again.

As described above, according to this embodiment, the post-state signal and the pre-state signal are detected by the temperature sensor 7 and the current sensor 8 as the state sensors, and the operation signal is output. Regardless, if the determination that the difference between the previous and the subsequent state signals does not exceed the threshold value is repeated five times or more, an alarm is issued to warn of a problem with the electric expansion valve 6.

Therefore, according to this embodiment, the electric expansion valve 6 can be operated without performing the unit test of the electric expansion valve 6.
It is possible to easily and early detect the malfunction of the device and to deal with the malfunction. In other words, it is possible to take early action such as replacing parts or repairing so that the situation of the failure does not spread due to the failure of the electric expansion valve 6.

Since the alarm is issued only when the determination that the threshold value is not exceeded is repeated five times or more, the detection of the operation failure of the electric expansion valve 6 can be made highly reliable.

In the above embodiment, a failure alarm was issued in step S6.
Therefore, the frequency of the inverter that drives the compressor 3 may be reduced, or the airflow of the blower fan to the heat exchanger may be reduced, so that the load may be reduced to take measures to avoid overloading the refrigeration circuit. Good. In this case, the malfunction of the refrigeration circuit can be avoided in advance.

In the above embodiment, step S5
Although the reference number of times for judging the malfunction in the above is set to five times, it may be set to a desired number that matches the judgment of the malfunction of the electric expansion valve 6.

In the above embodiment, the temperature of the discharge pipe 3a is used as the temperature sensor 7, but the temperature sensor for detecting the temperature of the refrigerant pipe connected to the electric expansion valve 6 may be used as the state sensor. .

[0035]

As is apparent from the above description, the control device for the electric expansion valve according to the first aspect of the present invention outputs the operation signal for changing the valve opening to the electric expansion valve, and then outputs the state signal from the state sensor. Before outputting the operation signal, the state sensor detects the previous state signal output by the state sensor, and determines whether or not the difference between the two signals exceeds the threshold value by the determination means. With this determination, it is possible to quickly detect whether the electric expansion valve has malfunctioned. Further, when the determining means determines that the electric expansion valve is malfunctioning, the treatment means can perform a predetermined measure for coping with the malfunction of the electric expansion valve. Therefore, according to the present invention, a malfunction of the electric expansion valve can be detected early and dealt with.

According to a second aspect of the present invention, in the control device for an electric expansion valve according to the first aspect, even if an operation signal is output to the electric expansion valve, the post-state signal does not exceed the threshold value and does not change. Is repeated a predetermined number of times, a predetermined measure for dealing with the malfunction of the electric expansion valve is performed. Therefore, the detection of the operation failure of the electric expansion valve can be made highly reliable.

[0037] In the invention according to claim 3, when the judging means judges that the signal difference does not exceed the threshold value and the motor-operated expansion valve has malfunctioned, the refrigeration circuit is operated. Take measures to avoid overloading. Therefore, the malfunction of the refrigeration circuit can be avoided in advance.

Further, when the determining means determines that the signal difference does not exceed the threshold value and the motor-operated expansion valve has malfunctioned, the treatment means determines whether or not the motor-operated expansion valve has malfunctioned. An alarm is issued to warn of a problem. Accordingly, countermeasures such as parts replacement and repair can be performed so that the failure situation does not spread due to the failure of the electric expansion valve.

[Brief description of the drawings]

FIG. 1 is a refrigeration circuit diagram of a refrigeration apparatus including an embodiment of a control device for an electric expansion valve of the present invention.

FIG. 2 is a structural view of the electric expansion valve of the embodiment.

FIG. 3 is a flowchart illustrating a control operation according to the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... 1st heat exchanger, 2 ... 2nd heat exchanger, 3 ... Compressor, 5
... four-way switching valve, 6 ... electric expansion valve, 7 ... discharge pipe temperature sensor, 8 ... current sensor, 10 ... control device, 11 ... rotor,
12 ... stator, 13 ... screw valve, 15 ... body, 16 ... screw hole, 17 ... valve hole, 20, 22 ... joint pipe.

Claims (4)

[Claims] A state sensor for detecting a state of the refrigerating apparatus and outputting a state signal; and a state sensor for outputting an operation signal for changing a valve opening to an electric expansion valve. The pre-state signal and the post-state signal are compared by comparing the pre-state signal output by (7, 8) with the post-state signal output by the state sensor after outputting the operation signal to the electric expansion valve (6). Determining means (S3) for determining whether or not the difference from the predetermined value exceeds a predetermined threshold value; and determining whether the difference does not exceed the predetermined threshold value by the determining means (S3). While performing a predetermined measure to cope with the malfunction of the electric expansion valve (6), when the determination means (S3) determines that the difference exceeds a predetermined threshold value, a measure not to perform the predetermined measure. Means (S
6) A control device for an electric expansion valve, comprising: 2. The control device for an electric expansion valve according to claim 1, wherein when the judgment by the judgment means (S3) is negative, an operation signal is output to the electric expansion valve (6) again. Repeating means (S5) for causing the determining means (S3) to make a determination again
Only when the number of repetitions by the repetition means (S5) reaches a predetermined number, the repetition number counting means (S6) causes the treatment means (S6) to perform the predetermined treatment.
5) A control device for an electric expansion valve, comprising: 3. The control device for an electric expansion valve according to claim 1, wherein said treatment means is avoidance means for performing a measure for avoiding an overload of the refrigeration circuit as said predetermined measure. Control device for electric expansion valve. 4. The electric expansion valve control device according to claim 1, wherein said treatment means (S6) is alarm means (S6) for giving an alarm as said predetermined treatment. Valve control device.