JPS6222062B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a cooling device, and an object of the present invention is to appropriately control the operation of an air conditioner that cools the interior of a goods storage or house equipped with a cooling device.

The cooling device includes a well-known refrigeration cycle that includes an electric compressor that compresses refrigerant, but repeatedly starting and stopping the electric compressor in a short period of time has a negative impact on the durability of the electric compressor and the electric compressor. This is unfavorable in terms of durability of compressor control parts.

For example, in a storage facility having a digital temperature display, changing the indoor cooling device, ie, the set temperature, to various settings can be achieved by operating the temperature setting device while looking at the temperature display. For example, if the indoor temperature is 5°C and it is desired to change it to 2°C, the average temperature inside the refrigerator is set to 2°C by setting the temperature setting device to 2°C while looking at the display on the temperature display. However, repeating this operation many times for various set temperatures causes the electric compressor to start and stop repeatedly, which is undesirable.

When changing the set temperature, the present invention maintains the state of the electric compressor before the change, thereby preventing repeated operation and stopping following the operation of changing the set temperature. It is.

Next, embodiments of the present invention will be described in detail based on the drawings. 1
1 is an electric compressor, and the refrigerant compressed here is returned to the electric compressor 1 through a condenser, a pressure reducing device, and an evaporator (not shown) to form a refrigeration cycle, which is incorporated into the storage as a cooling device. 2 is an electric blower that sends air to the condenser, 3 is an electric blower that circulates the air cooled by the evaporator into the refrigerator, and 4 is a defrosting heater for the evaporator, which is connected to an AC power source 5. ing. 6 is a relay included in a switching circuit which will be described later. 7 and 8 are stabilized DC power lines, 9 is a temperature detection circuit including an indoor temperature detection sensor 9A whose resistance value changes in response to the temperature at a predetermined location in the storage, and 10 is a variable resistor for setting the temperature inside the storage. This is an internal temperature setting circuit including the container 10A. Reference numeral 11 denotes an operational amplifier which inputs the reference input set by the refrigerator temperature setting circuit 10 and the measurement input by the refrigerator temperature detection circuit and performs an arithmetic operation to generate an output as a comparison of these inputs. It is a circuit. 12 is a temperature display device;
An analog-to-digital conversion circuit 13, a display 14 in which a four-digit one-digit display section with seven segments arranged in a figure-eight pattern, a digit control circuit 15 of the display 14, and a light emitting element of the display 14. and a segment driver circuit 28 that controls non-emission. Reference numeral 16 denotes a selection switch for selecting whether to display on the temperature display device 12 either the temperature set by the internal temperature setting circuit 10 or the internal temperature detected by the sensor 9A. A switching circuit 17 has a circuit configuration including a relay 6, a level detection circuit 18 having a Schmitt circuit configuration, and a driving transistor 19 for the relay 6. 25 is a holding circuit for maintaining the state of the switching circuit 17 in the state before switching when the selection switch 16 switches from the state of selecting the internal temperature to the state of selecting the set temperature; It consists of a voltage follower circuit 20 for increasing input impedance and an input circuit 21 of the voltage follower 20. The input circuit 21 includes resistors 22 and 2 connected in series between the power lines 7 and 8.
3 and 24, and inputs the terminal voltage of the resistor 23, which is the voltage generated by this voltage divider circuit, to the voltage follower 20,
A contact a, which closes the switch piece 16B of the selection switch 16, is connected between the resistors 22 and 23. The output of the voltage follower 20 is input to the Schmitt circuit 18, and when the selection switch 16 is in the state of selecting the set temperature, the holding circuit 25 switches the Schmitt circuit 18 based on the voltage created by the voltage dividing circuit. performs an action to maintain the state before the change.

Next, the operation will be explained. When the selection switch 16 is currently selecting the internal temperature display side, the contact a is closed. In this state, the analog voltage change of the sensor 9A is transmitted through the switch piece 16A of the selection switch 16 to the comparator circuit 11 which is an operational amplifier.
A comparison is made with the reference input set by the internal temperature setting variable resistor 10A, and the output is input to the holding circuit 25 via the switch piece 16B of the selection switch 16. If the temperature inside the refrigerator is above a predetermined temperature, the output of the comparison circuit 11 becomes high level, and the output of the voltage follower 20 becomes high level, exceeding the reference voltage (threshold voltage) of the Schmitt circuit 18, so that the transistor 19
ON, relay 6 is energized and the switch is connected to contact a.
The electric compressor 1 and electric blower 2, which had been stopped until now, are operated to cool the inside of the refrigerator. When the cooling inside the refrigerator progresses and the temperature drops to a predetermined temperature, comparison circuit 1
1 becomes a low level, the output of the voltage follower 20 becomes a low level, the output of the Schmitt circuit 18 becomes a low level, and the output of the transistor 19 becomes a low level.
is turned OFF, the relay 6 is de-energized, the switch is switched to contact b, the electric compressor 1 and the electric blower 2 are stopped, and the heater 4 is energized. When the temperature inside the refrigerator rises again and the output of the comparison circuit 11 becomes a high level, the relay 6 is energized again as described above and the electric compressor 1 is activated.
and operates the electric blower 2.

On the other hand, the internal temperature at that time is displayed on the display 14 in the next operation. That is, the signal based on the temperature sensed by the sensor 9A is sent to the analog/digital conversion circuit 1.
3, the segment signal is input from the segment driver circuit 28 to the display 14, and the digit signal from the digit control circuit 15 is input to the display 14.
Display control is performed for each digit, and the temperature inside the refrigerator at that time measured by the sensor 9A is digitally displayed on the display 14.

Next, when the selection switch 16 is switched to select the set temperature side, the switch pieces 16A and 16B each close to the contact point b. Therefore, the signal from the refrigerator temperature setting circuit 10 is input to the analog/digital conversion circuit 13, the segment signal is input to the display 14 through the segment driver circuit 28, and the digit signal is input to the display 14 through the digit control circuit 15. to display the set temperature.

The operation level of the circuit in the above operation will be explained. Now, the voltage when the output of the comparator circuit 11 is high level is V _OH , and the voltage when it is low level is V _OL ,
Let V _IH be the upper limit of the input threshold voltage of the Schmitt circuit 18, and V _IL be the lower limit. The Schmitt circuit 18 has hysteresis due to a resistor 27 and a positive feedback resistor 26 connected to the output of the voltage follower 20.
The output of the voltage follower 20 becomes higher than V _IH and becomes a high level, and the output of the voltage follower 20 becomes higher than V _IL
becomes lower, making the output a low level. Furthermore, when the switch pieces 16A, 16B of the selection switch 16 are closed to the contact point b, that is, the resistors 22, 23, 2
If the output voltage of the voltage follower 20 when the terminal voltage of the resistor 23 is input to the voltage follower 20 when the voltage is divided between the power supply lines 7 and 8 in step 4 is V _OS , then V _OH >V _IH > V _OS > V _IL >
Set so that the relationship is _VOL . In this relationship, the switch pieces 16A and 16B of the selection switch 16
If the input to the Schmitt circuit 18 is higher than the threshold voltage in a state where the contact a is closed, the Schmitt circuit 18 is inverted and produces a high level output, and the electric compressor 1 is in an operating state. In this state, the switch piece 16 of the selection switch 16
When A and 16B are switched to contact b, the input applied to the Schmitt circuit 18 through the voltage follower 20 decreases to V _OS , but since it does not reach the lower limit level V _IL at which the Schmitt circuit 18 is inverted again, the Schmitt circuit 18 is switched to the selection switch 16. switch piece 1
The electric compressor 1 continues to operate while maintaining the state in which contacts 6A and 16B were closed at contact a. Therefore, in this state, even if the internal temperature setting variable resistor 10A is operated to change the temperature display displayed on the display 14, the state of the Schmitt circuit 18 does not change, and the electric compressor 1 repeatedly starts and stops. Never. By switching the switch pieces 16A and 16B of the selection switch 16 again to contact a, the comparator circuit 11 generates an output when comparing the set temperature and the measured temperature, and the high and low levels of the output cause electric compression. The operation and stop of machine 1 is controlled.

In the present invention, if the electric compressor 1 is configured to maintain the state before switching when the selection switch 16 is switched to the set temperature display side, the connection location of the selection switch 16 and the configuration of the holding circuit 25 are as described above. The present invention is not limited to this example, and it is also possible to achieve the present invention by using a microcomputer-controlled circuit configuration. The present invention can also be effectively applied to an air conditioner that cools a living space.

In the above circuit, resistors 22 and 23 are several tens of kilohms
The resistance of the resistor 24 is several tens of ohms, and V _OS is approximately 1/2 of the voltage between the power supply lines 7 and 8. Further, V _OH is approximately the voltage of the power supply line 7, and V _OL is approximately the voltage of the ground power supply line 8. Therefore, the set temperature set by the variable resistor 10A for setting the internal temperature is changed between the ON point and the OFF point of the electric compressor 1, and the temperature displayed on the display 14 is The average temperature inside the refrigerator can be displayed as the set temperature.

As described above, in the present invention, when the selection switch is used to select between displaying the set temperature and displaying the indoor temperature, and each temperature is displayed on the display, the indoor temperature When you change the setting temperature from a state where the indoor cooling operation is performed with the refrigeration system displaying, the setting temperature may be changed and reset, and the Even if the temperature reaches such a point that the electric compressor cannot be operated or stopped, the operating state of the electric compressor can be maintained in the same state as when the selection switch was in the indoor temperature display state. Therefore, after operating the selection switch, the electric compressor does not repeatedly turn on and off as the set temperature changes, so the electric compressor and its related parts can be protected and the occurrence of failures can be reduced. Furthermore, when the electric compressor is temporarily stopped during operation and immediately restarted, the load on the electric compressor of the refrigeration cycle is large, causing an excessive starting current to flow and causing the power breaker to shut off. There is no such thing and stable restart can be performed.

[Brief explanation of the drawing]

The drawings are electrical circuit diagrams showing embodiments of the present invention. DESCRIPTION OF SYMBOLS 1... Electric compressor, 9A... Indoor temperature detection sensor, 10A... Temperature setting variable resistor, 11... Comparison circuit, 12... Display device, 14... Display device, 1
7... Switching circuit, 25... Holding circuit.

Claims (1)

[Claims] 1 Comparison circuit that generates an output by comparing the reference input set by the indoor temperature setting circuit and the measurement input based on the temperature detection circuit that includes a sensor that responds to the temperature at an appropriate location in the room, and displays the temperature according to the input signal a selection switch for selecting whether the reference input or the measurement input is input to the temperature display device; a state in which the selection switch causes the temperature display device to input the measurement input; a switching circuit that controls operation and stop of the cooling device based on the output of the comparison circuit when the temperature display device is in a state where the selection switch inputs the measurement input to the temperature display device and changes the state of inputting the reference input to the temperature display device; A control device for a cooling device, comprising: a holding circuit that maintains a control state of the cooling device by the switching circuit in a state before the switching operation when a switching operation is performed.