JPH0599516A - Freezer device - Google Patents

Abstract

PURPOSE:To reduce the number of starting or stopping operations of a compressor by a method wherein a temperature sensing signal and a reference value are compared to each other, a signal corresponding to the difference is generated, a degree of opening of a solenoid valve is controlled with the signal and the degree of opening of the solenoid valve is set to a predetermined value when the compressor is restarted. CONSTITUTION:The first temperature sensor 8 is disposed near an evaporator 4 so as to detect a surrounding air temperature of the evaporator 4. A temperature comparator 9 compares a temperature sensing signal from the first temperature sensor 8 with a reference value set in response to a predetermined set temperature and generates a signal corresponding to the difference. A degree of opening of the valve control part 10 controls a degree of opening of an electrical valve 12 in response to a signal got from the temperature comparing part 9. In addition, a degree of opening of the valve correction part 11 sets a degree of opening of the electrical valve 12 when it is restarted after stopping of the compressor 1 to have a value of (a value when the compressor 1 is stopped) + (a predetermined value). This electrical valve 12 is disposed at a piping of the evaporator at its outlet port so as to adjust a flow rate of refrigerant flowing within the evaporator 4. With such an arrangement, a response of a temperature control to a variation of the air temperature within a freezer device is made fast.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating device used in a super showcase, a refrigerator, a constant temperature bath, etc., and more particularly to a refrigerating device which requires high accuracy in temperature control in a refrigerator.

[0002]

2. Description of the Related Art Conventionally, as a refrigerating apparatus of this type, there is one described in, for example, Japanese Utility Model Publication No. 58-48987. As shown in FIG. 7, this refrigeration system comprises a compressor 1, a condenser 2, a temperature type expansion valve 3 and a cooler 4 which are connected by a pipe 5, and a blower 6 and an evaporator are provided near the evaporator 4. A temperature sensitive tube 7 is arranged in the outlet side pipe 5 of the container 4. The operation of this refrigerating device operates so that, for example, if the temperature of the liquid refrigerant in the evaporator 4 decreases, the temperature of the temperature-sensitive cylinder 7 decreases, and if it falls below a predetermined temperature, the blower 6 increases the blowing strength. The temperature inside the refrigerator is kept constant.

[0003]

However, in the above refrigerating apparatus, the temperature inside the refrigerator is controlled by detecting the temperature of the refrigerant inside the pipe 5 to control the temperature inside the refrigerator. On the other hand, it was an indirect control. Therefore, the response to changes in the refrigerant temperature and pressure is fast, but to the changes in the air temperature inside the refrigerator, the temperature of the fins of the evaporator 4 changes first, and then the temperature of the refrigerant changes, and then the feeling. There is a problem that the response is slow, such as the temperature of the warm cylinder 7 changing, and it is difficult to control the temperature inside the refrigerator within a range of ± 0.5 to 1 ° C from the set temperature with high accuracy. It was Further, when the cooling load is small at the time of restarting after the compressor is stopped, there is a problem that the temperature inside the refrigerator suddenly drops and the compressor stops, and the compressor is repeatedly operated and stopped. When restarting after the compressor is stopped, the opening of the expansion valve is small, the suction pressure of the compressor drops sharply, the compressor stops, and on the contrary, the opening of the expansion valve is large and a large amount of air flows to the compressor. There was a problem that the liquid returned and the overcurrent protector etc. actuated and the compressor stopped. Further, when the compressor is operated for a long time in a state where the pressure sucked into the compressor is low, oil accumulates in the evaporator, the oil does not return to the compressor, and the compressor is seized.

In order to solve the above problems, the present invention speeds up the response of the refrigeration system to changes in the temperature inside the refrigerator, and can control the temperature inside the refrigerator with high accuracy and little fluctuation.
The objective is to obtain a refrigeration system with few compressor starts / stops.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a refrigerating apparatus having a refrigerant flow path in which a compressor, a condenser, a pressure reducing device, and an evaporator are connected by piping, and the inside of the evaporator is provided in the refrigerant flow path. A motor-operated valve for adjusting the refrigerant flow rate is disposed, and a temperature detection unit that detects the ambient temperature of the evaporator and generates a temperature detection signal is disposed near the evaporator, and the temperature detection signal and a predetermined set temperature are set. After comparing the corresponding reference value with a temperature comparison unit that generates a signal according to the difference between them, a valve opening control unit that controls the opening of the electrically operated valve by the signal of the temperature comparison unit, and after the compressor is stopped When the valve is restarted, a valve opening correction unit that sets the opening of the electrically operated valve to [value when the compressor is stopped] + [predetermined value] is provided.

The pressure reducing device constituting the refrigerant flow path is an electronic expansion valve, and the electronic expansion valve corresponds to the temperature of the suction pipe between the motor-operated valve and the compressor and the pressure in the suction pipe. The electronic expansion valve control device that controls the difference between the saturation temperature and the saturation temperature to be a predetermined value, and when the compressor is started, the opening degree of the electronic expansion valve is a predetermined multiple that exceeds 1 with respect to the predetermined opening degree. An electronic expansion valve valve opening degree correction unit is provided which is activated at an opening degree and is controlled to reach a predetermined opening degree after a predetermined time.

Further, when the time when the compressor suction pressure is equal to or lower than a predetermined value is integrated and exceeds a predetermined time,
An oil return control unit that fully opens the motor-operated valve is provided.

[0008]

In the refrigerating apparatus according to the present invention, the temperature near the evaporator is detected by the temperature detector, the detected signal is compared with the set temperature, and the determined value of the valve opening is output based on the result. In addition, at the time of restarting after the compressor is stopped, the fixed value of the valve opening is output as [compressor stopped value] + [predetermined value],
The temperature is controlled by adjusting the opening degree of a motor-operated valve provided in the middle of the refrigerant flow path in accordance with this output.

Further, in the refrigerating apparatus according to the present invention, the decompression device is an electronic expansion valve, and the electronic expansion valve is adapted to adjust the temperature of the suction pipe between the electric valve and the compressor and the pressure in the suction pipe. An electronic expansion valve control device that controls a difference from a corresponding saturation temperature to a predetermined value, and at the time of starting the compressor, the opening degree of the electronic expansion valve is a predetermined multiple that exceeds 1 with respect to the predetermined opening degree. With the electronic expansion valve valve opening correction unit that starts at the opening of
Adjust the opening of the electronic expansion valve. Further, in the refrigerating apparatus according to the present invention, when the time when the compressor suction pressure becomes a predetermined value or less is integrated and exceeds a predetermined time, an oil return control unit that fully opens the motor-operated valve for a predetermined time causes an oil return I do.

[0010]

【Example】

Example 1. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing a refrigerating apparatus according to the present invention. In this refrigerant circuit, a compressor 1, a condenser 2, an expansion valve 3 and an evaporator 4 are connected by a pipe 5, and an outlet side of the evaporator 4 is provided. As in the conventional case, the temperature-sensitive cylinder 7 is provided, and the temperature-sensitive cylinder 7
Is connected to the expansion valve 3 to adjust the opening degree of the expansion valve 3,
Further, a blower 6 is arranged near the evaporator 4. A first temperature detector 8 is arranged near the evaporator 4 and detects the ambient temperature of the evaporator 4. 9 is a temperature comparison unit,
A comparator (not shown) for comparing the temperature detection signal from the first temperature detector 8 with a reference value set corresponding to a predetermined set temperature is built in, and the temperature detection signal and the reference value are compared with each other. A comparison is made and a signal corresponding to the difference T is generated. Reference numeral 10 denotes a valve opening control unit, which responds to a signal from the temperature comparison unit 9
The valve opening W of the motor-operated valve 12 is controlled. Reference numeral 11 denotes a valve opening correction unit, which is used when the compressor 1 is restarted after being stopped.
Valve opening W of [value when the compressor 1 is stopped] + [predetermined value]
It is what The motor-operated valve 12 is provided in the pipe on the outlet side of the evaporator 4 and adjusts the flow rate of the refrigerant flowing in the evaporator 4.

In the above refrigerating apparatus, the refrigerant flowing in the evaporator 4 is adjusted depending on whether the temperature inside the refrigerator is higher or lower than a predetermined temperature and the degree of the temperature change. By controlling the flow rate, it is possible to respond quickly to changes in the temperature inside the refrigerator.

FIG. 2 is a flowchart showing the control operation procedure of the valve opening control unit 10 and the valve opening correction unit 11 of the refrigeration system.
The fixed value output from the valve opening control unit 10 for adjusting the opening of the electric valve 12 is based on the signal from the temperature comparison unit 9. That is, when the compressor 1 is not restarted in step S21 in FIG. 2, the process proceeds to step S23. In step S23, if a signal indicating that the internal cold storage temperature is higher than a predetermined temperature is input from the temperature comparison unit 9, the process proceeds to step S24, and the valve opening control unit 10 causes the motor-operated valve 12 to operate.
The motor-operated valve 12 so as to increase the valve opening W of the
Is output to. On the contrary, in step S23, when a signal that the internal cold storage temperature is lower than the predetermined temperature is input from the temperature comparison unit 9, the process proceeds to step S25, and the motor-operated valve is operated.
The motorized valve is designed to reduce the valve opening W of 12 by a fixed amount ΔW.
Output to 12.

Further, in FIG. 2, when the compressor 1 is restarted in step S21, the process proceeds to step S22, in which the valve opening correction unit 11 operates so that the valve opening of the motor-operated valve 12 is [compressor]. 1 value when stopped] + [predetermined value].

Although the present invention has been described with respect to the case where the temperature sensing cylinder 7 is connected to the expansion valve 3, the same effect can be obtained with an electronic expansion valve.

Example 2. FIG. 3 is a diagram showing a circuit configuration of a refrigerating apparatus according to Embodiment 2 of the present invention. As shown in the figure, an electronic expansion valve 19 is provided instead of the expansion valve 3 of the first embodiment in FIG. Reference numeral 17 is a suction pipe that communicates between the motor-operated valve 12 and the compressor 1, 13 is a second temperature detector that detects the temperature of the suction pipe 17, and 18 is a suction pipe from the inlet liquid pipe of the electronic expansion valve 19. A throttling device communicating with the pipe 17 and a third temperature detector 14 for detecting the temperature immediately after exiting the throttling device 18 (saturation temperature corresponding to the pressure of the suction pipe 17). 15 is
Electronic expansion for controlling the electronic expansion valve 19 so that the difference between the temperature detected by the second temperature detector 13 and the temperature detected by the third temperature detector 14 becomes a predetermined value. It is a valve control device. Further, the reference numeral 16 indicates that when the compressor 1 is started, the opening degree of the electronic expansion valve 19 is started by a predetermined multiple of more than 1 with respect to a predetermined opening degree, and becomes a predetermined opening degree after a predetermined time. It is an electronic expansion valve valve opening degree correction unit that controls.

In the above refrigeration system, the opening of the motor-operated valve 12 is adjusted to control the flow rate of the refrigerant flowing in the evaporator 4 depending on whether the temperature inside the refrigerator is higher or lower than a predetermined temperature. It quickly responds to internal temperature changes.

FIG. 4 shows an electronic expansion valve control device 1 for a refrigeration system.
5 is a flowchart showing a control operation procedure of the electronic expansion valve valve opening degree correction unit 16. The definite value output from the electronic expansion valve control device 15 for adjusting the opening degree of the electronic expansion valve 19 is the temperature detected by the second temperature detector 13 and the third temperature detector 14 It is based on the difference (SH1) from the temperature detected in. That is, when the compressor 1 is not restarted in step S41 in FIG. 4, the process proceeds to step S43. In step S43, when a signal that the difference (SH1) between the temperature detected by the second temperature detector and the temperature detected by the third temperature detector 14 is higher than a predetermined value is input, In step S44, the electronic expansion valve control device 15 controls the valve opening degree G of the electronic expansion valve 19 by a predetermined amount ΔG.
It is output to the electronic expansion valve 19 so as to increase. On the contrary, in step S43, a signal that the difference (SH1) between the temperature detected by the second temperature detector 13 and the temperature detected by the third temperature detector 14 is lower than a predetermined value is input. If so, the process proceeds to step S45, and the electronic expansion valve control device 15 outputs to the electronic expansion valve 19 so as to decrease the valve opening degree G of the electronic expansion valve 19 by a fixed amount ΔG.

Further, in FIG. 4, when the compressor 1 is restarted in step S41, the process proceeds to step S42, in which the electronic expansion valve valve opening correction section 16 acts to cause the valve of the electronic expansion valve 19 to operate. The opening is started at a predetermined multiple of more than 1 with respect to the predetermined opening, and is operated so as to reach the predetermined opening after a predetermined time.

The present invention is provided with a throttling device 18 communicating from the inlet liquid pipe of the electronic expansion valve 8 to the suction pipe 17, and the temperature immediately after the throttling device 18 is discharged (corresponding to the pressure of the suction pipe 17). (Saturation temperature) is detected by the third temperature detector 14,
A pressure sensor is provided in the suction pipe 17 to detect pressure,
The pressure value may be converted into temperature.

Example 3. FIG. 5 is a diagram showing a circuit configuration of a refrigerating apparatus according to Embodiment 3 of the present invention. As shown in the figure, in addition to the constituent elements of the first embodiment in FIG. 1, a pressure sensor 21 for detecting the compressor suction pressure is added. Further, 20 is an oil return control unit, and when the time when the output of the pressure sensor 21 becomes a predetermined value or less is integrated and exceeds a predetermined time, the electric valve 12 is fully opened for a certain time. ..

In the above refrigeration system, the opening of the motor-operated valve 12 is adjusted to control the flow rate of the refrigerant flowing in the evaporator 4 depending on whether the temperature inside the refrigerator is higher or lower than a predetermined temperature. It quickly responds to changes in temperature.

FIG. 6 shows a control operation procedure of the valve opening control unit 10 and the oil return control unit 20 of the refrigeration system. The fixed value output from the valve opening control unit 10 for adjusting the opening of the electric valve 12 is based on the signal from the temperature comparison unit 9. That is,
In FIG. 6, in step S61, if the integrated time for which the compressor suction pressure is less than or equal to the predetermined value is less than or equal to the predetermined value, the process proceeds to step S63. In step S63, the temperature comparison unit 9
If a signal indicating that the internal temperature is higher than the predetermined temperature is input, the process proceeds to step S64, where the valve opening control unit 10 causes
It is output to the motor-operated valve 12 so as to increase the valve opening degree W of the motor-operated valve 12 by a fixed amount ΔW. On the contrary, when a signal that the internal cold storage temperature is lower than the predetermined temperature is input from the temperature comparison unit 9 in step S63, the process proceeds to step S65.
It is output to the motor-operated valve 12 so as to reduce the valve opening degree W of the motor-operated valve 12 by a predetermined amount ΔW.

Further, in FIG. 6, when the integrated time for which the compressor suction pressure is less than or equal to the predetermined value exceeds the predetermined value in step S61, the process proceeds to step S62 and the operation of the oil return control unit 20 causes the motor-operated valve 12 to operate. The valve opening is operated at full opening for a certain period of time.

[0024]

Since the present invention is constituted as described above, the temperature around the evaporator is directly detected by the temperature detector, the temperature is compared with the set temperature based on this detection signal, and the result is compared. Based on this output, a fixed value of the valve opening is output, and when restarting after the compressor is stopped, the fixed value of the valve opening is output as [compressor stopped value] + [predetermined value]. As a result, the opening degree of the motor-operated valve provided in the middle of the refrigerant flow path is adjusted. Therefore, the response of the temperature control to the change of the air temperature in the freezer or the like is accelerated, and the temperature in the freezer or the like is controlled with high accuracy with little fluctuation.

Further, since the present invention is configured as described above, the difference between the temperature of the suction pipe between the electronic expansion valve and the compressor and the saturation temperature corresponding to the pressure in the suction pipe is set. When the compressor is started and the electronic expansion valve control device for controlling the valve to be a predetermined value, the opening degree of the electronic expansion valve is started at a predetermined multiple of more than 1 with respect to the predetermined opening, The opening degree of the electronic expansion valve is adjusted by the electronic expansion valve valve opening degree correction unit that controls the opening degree to reach the predetermined opening degree after the elapse of time. Therefore, even when the compressor is restarted after it is stopped, the suction pressure of the compressor drops sharply and the compressor stops, or conversely a large amount of liquid returns to the compressor and the overcurrent protector etc. operates. Then
The compressor never stops.

Further, since the present invention is constituted as described above, the time during which the compressor suction pressure becomes equal to or lower than the predetermined value is
When the accumulated value exceeds the predetermined time, the oil return control unit, which fully opens the motor-operated valve for a certain period of time, returns the oil, and the oil accumulates in the evaporator, the oil does not return to the compressor, and the compressor does not seize. The problem of causing it does not occur.

[Brief description of drawings]

FIG. 1 is a refrigerant circuit diagram of a refrigeration system showing Embodiment 1 of the present invention.

FIG. 2 is a flowchart showing a control operation procedure of a valve opening control unit and a valve opening correction unit of the refrigeration system shown in FIG.

FIG. 3 is a refrigerant circuit diagram of a refrigeration system showing Embodiment 2 of the present invention.

4 is an electronic expansion valve control device for the refrigeration system shown in FIG. 3,
It is a flow chart which shows a control operation procedure of an electronic expansion valve valve opening amendment part.

FIG. 5 is a refrigerant circuit diagram of a refrigeration system showing Embodiment 3 of the present invention.

6 is a flowchart showing a control operation procedure of a valve opening control unit and an oil return control unit of the refrigeration system shown in FIG.

FIG. 7 is a refrigerant circuit diagram of a refrigeration apparatus showing a conventional example.

[Explanation of symbols]

 1 Compressor 2 Condenser 3 Decompressor 4 Evaporator 5 Piping 8 Temperature detection part 9 Temperature comparison part 10 Valve opening control part 11 Valve opening correction part 12 Motorized valve 13 Second temperature detector 14 Third temperature detection 15 Electronic expansion valve control device 16 Electronic expansion valve valve opening correction unit 17 Suction pipe 18 Throttle device 19 Electronic expansion valve 20 Oil return control unit 21 Pressure sensor

Claims (3)

[Claims] 1. A refrigeration system having a refrigerant flow path in which a compressor, a condenser, a pressure reducing device, and an evaporator are connected by piping,
A motor-operated valve provided in the middle of the refrigerant flow path for adjusting the refrigerant flow rate in the evaporator, a temperature detection unit arranged in the vicinity of the evaporator to detect an ambient temperature of the evaporator and generate a temperature detection signal,
A temperature comparison unit that compares the temperature detection signal with a reference value corresponding to a predetermined set temperature and generates a signal according to the difference between the two.
A valve opening control unit that controls the opening degree of the electric valve according to a signal from the temperature comparison unit, and the opening degree of the electric valve when the compressor is restarted after the stoppage of [the value when the compressor is stopped] +
A refrigeration apparatus comprising a valve opening correction unit that sets a [predetermined value]. 2. A pressure reducing device is an electronic expansion valve, and the electronic expansion valve is a difference between a temperature of a suction pipe between the motor-operated valve and the compressor and a saturation temperature corresponding to a pressure in the suction pipe. Is controlled to a predetermined value, and when the compressor is started, the opening degree of the electronic expansion valve is started at a predetermined multiple of more than 1 with respect to the predetermined opening. The refrigeration apparatus according to claim 1, further comprising an electronic expansion valve valve opening degree correction unit that controls the opening degree to a predetermined opening degree after a predetermined time. 3. An oil return control unit for fully opening the motor-operated valve for a fixed time when the time when the suction pressure of the compressor is equal to or lower than a predetermined value is integrated and exceeds a predetermined time. The refrigeration system according to claim 1.