JPH01163564A - Controller for refrigerator - Google Patents

Abstract

PURPOSE: To quickly protect a compressor from overload operation by reducing the operational capacity of the compressor when the current value of a motor for driving the compressor exceeds a first set value and increasing the capacity when the current value becomes smaller than a second set value which is smaller than the first value. CONSTITUTION: When the operating current of a motor CM for driving a compressor 1 exceeds a first set value 265A while the compressor is operated at a 100% compression capacity, a current comparator 52 outputs a setting command to a timer device 53 and again confirms three seconds later that whether or not the operating current exceeds 265A. When the operating current exceeds 265A, the comparator 52 causes the compressor 1 to be operated at a 75% compression capacity by issuing an output A to a control signal generator 50 and, at the same time, finds a restored current value three seconds later on the basis of the operating current value by resetting the timer device 53. Ten minutes later, another timer device 54 issues a timer-up command and, when the operating current is lower than the restored current, the compressor 1 is returned to the 100% capacity operation. The same control is performed when the operating current exceeds a second set value of 295A while the operational capacity is reduced to the 75% from the 100%.

Description

Detailed Description of the Invention (a) Industrial Application Field The present invention provides a refrigerant circuit that connects a compressor with variable operating capacity, a heat source side heat exchanger, a pressure reduction device, and a user side heat exchanger. The present invention relates to a control device for a refrigerator equipped with a refrigerator.

(b) Prior art As for the conventional technology regarding such a control device, ■ Japanese Utility Model Publication No. 53-16995, ■ Japanese Unexamined Patent Publication No. 54-5965
There was something like the one described in Publication No. 2. Publication No. 1 states that the drive motor for a refrigerator is provided with a detection element for detecting its load capacity, and the adjustment range of the refrigeration capacity adjustment mechanism is limited by a command from the detection element. The bulletin (■) states that ``the motor load is detected by current.'' These ■publications and ■
As a conventional technique that combines the above publication, the load capacity of the refrigerator is detected from the current flowing through the compressor motor, and if this current value is within the normal value, the refrigeration capacity is adjusted based on this current value, Only a control method has been disclosed that adds a limit to the adjustment range of the refrigerating capacity when the current value reaches an overcurrent (overload).

(C) Problems to be Solved by the Invention In the conventional technology such as 2, the refrigerating capacity is adjusted based on the current value, so temperature fluctuations in the load can be calculated based on the amount of evaporation of the refrigerant in the heat exchanger. In other words, there is a problem in that the adjustment of the refrigeration capacity in response to load temperature changes is delayed and the load temperature fluctuation range becomes large. There is no fixed correlation between the increase and decrease of the value, and the current does not always follow the temperature change of the load, and the range of temperature fluctuation of the load may become large.In view of this problem, the present invention has been developed. It is an object of the present invention to provide a control device that can optimally change the refrigerating capacity in accordance with temperature fluctuations of the load, and at the same time, can quickly avoid an overload state in the event of an overload.

(d) Means for Solving the Problems The control device of the present invention includes an electric compressor whose operating capacity can be changed, a heat source side heat exchanger, a pressure reducing device, and a user side heat exchanger provided on the load side. The refrigerator includes a capacity control unit that changes the operating capacity of the compressor based on the temperature of the load, and the value of the current flowing through the drive motor is set to a first setting. a capacity reduction control section that outputs a signal to the capacity control section without reducing the operating capacity of the compressor when the current value once exceeds the first setting value; and a capacity increase control unit that outputs a signal to the capacity control unit to increase the operating capacity of the compressor when the operating capacity of the compressor is once lower than a set value.

(E) Function The control device configured in this manner not only appropriately sets the operating capacity of the compressor based on the temperature of the load, but also detects compressor overload from an increase in current and adjusts the operating capacity of the compressor. After that, when the current value decreases to the second set value, the operating capacity of the compressor is increased again.

(f) Example Embodiments of the present invention will be described below based on the drawings.

First, as shown in FIG. 1, a refrigerator to which the present invention is applied includes a compressor (1), a four-way valve (2), a heat source side heat exchanger <3), and a liquid receiver <4>. , a pressure reducing device (5>), a user-side heat exchanger (6), and an accumulator (7) are connected to form a refrigerant circuit (8).In addition, (9),
(10) is a check valve for cooling, and (11) and (12) are check valves for heating.

This compressor (1) has a variable operating capacity (compression capacity). Mechanisms for changing the operating capacity include those that control the compressor with multiple unloader valves, those that change the number of drive cylinders of a reciprocating compressor, and those that control the capacity of a screw compressor. Various mechanisms are conceivable, such as one that controls a valve or one that changes the rotation speed of the compressor drive motor, but in this example, the compressor simply has multiple stages (it may be stepless). The following explanation will be given assuming that the compression capacity can be controlled. The refrigerant discharged from the compressor (1) flows from the discharge line (13) through the four-way valve (2) in the direction of the solid arrow during cooling, and in the direction of the dashed arrow during heating. ) and return to the compressor (1) from the suction line (14) via the accumulator (7). At this time, the heat source side heat exchanger (3) acts as a condenser during cooling and as an evaporator during heating, and heat exchange with outside air is promoted by the blower (15). Further, the user-side heat exchanger (6) acts as an evaporator during cooling and as a condenser during heating to cool or heat the secondary refrigerant (for example, water) in the secondary refrigerant circuit (16). This cold and hot water is then circulated through the secondary refrigerant circuit (16) by the pump (17) and supplied to the fan coil (18), where heat exchange between the cold and hot water and the indoor air takes place. Cooling or heating is performed. In addition, the compressor (1) is connected to the user side heat exchanger (6
) The compression capacity is adjusted according to the secondary refrigerant inflow temperature, so that the secondary refrigerant outflow temperature is at an appropriate temperature.

In FIG. 2, (ρ) is a bus bar to which constant DC voltage is not supplied through the operation switch (19). (20> is a microcomputer, the power supply terminal (BI) is connected to the bus bar (20), the clock terminal (CLI), (CL2)
An oscillator (21) that determines the free running time of the microcomputer (20) (having the functions of the capacity control unit and capacity increase/decrease control unit of the present invention) is connected between them. 22) is a cooling/heating selection switch, one end of which is connected to the bus (I2), and the other end of which is connected to the input capo of the microcomputer (20), 1-(I
I). (23) is supplied with a constant DC voltage from the bus bar (ρ), and converts the analog signal of the temperature sensor (24) that detects the inflow temperature of the secondary refrigerant into the heat exchanger (6) on the user side into a binary digital signal. This is a secondary refrigerant temperature measuring circuit, and the output end is connected to the input port (I2).

(25) is an operating current measuring circuit that is supplied with a constant DC voltage from the bus (f2) and measures the operating current of the drive motor (CM) of the compressor (1) shown in Fig. 3 as a binary digital value. The output end is connected to the input port (13). The circuit (25) converts the current flowing through the secondary winding (262) of the current transformer (26) whose negative winding (261) is connected in series to the drive motor (CM) into a voltage, and further rectifies and smoothes the current. After that, calculate the voltage difference between the reference voltage and the voltage difference between A and D.
(analog-digital) conversion and drive motor (CM
) to measure the operating current. (27) is a reference pulse generator that generates a reference pulse of a predetermined frequency using the DC constant voltage supplied from the bus, and its output end is connected to the input capo-1-(I4>).

(28) is a control relay circuit consisting of control relays (29) to 34), and one end of each relay is connected to the bus line (p,
The other end is connected to the output port (circle) or P6) via a driver (35) each having a reversing mechanism. (36) is a warning lamp, one end of which is connected to the bus bar (I2), and the other end of which is connected to the output port (P7) via a driver (37) having a reversing mechanism.

In Figure 3, (38) is an AC power supply, and a four-way valve (
2> excitation relay (39), power supply relay (40) for the drive motor (FM) of the blower (15), and compressor (1)
The power supply relay (41) of the drive motor (CM>) and the capacity adjustment relay (42), (43> and (44) of the compressor 1) are connected to the control relay (29> or 34), respectively.
) is connected to an AC power source (38) via a normally open switch (291) to 341). In addition, the drive motor (FM) is connected to the normally open switch (401) of the power relay (40).
), the drive motor (CM) is connected to the power relay (41
) are each connected to an AC power source (38) via a normally open switch (411).

Figure 4 shows the internal system of the microcomputer (20), and the microcomputer (20) receives either a low-level "0" signal or a high-level "1" signal at the input port (11). A heating and cooling command device (45) that issues cooling or heating commands depending on the situation, a temperature storage device (46) that stores the latest temperature data sent via the input boat (I2), and a storage device (46). A set value storage device (47) that stores the set value to be compared with the temperature data, and a current storage device (48) that stores the latest current data sent through the input capo-1-(I3>).
), a setting value storage device (49) that stores a setting value to be compared with the current data in the storage device (48), and both storage devices (
46) and (47), and adjust the control signal generator of the next stage so that the characteristics shown in FIGS. 5 and 6 are obtained.
0) to issue the control signals shown in Table 1, and both storage devices (48) and (49).
) are compared and the outputs A and B are sent to the control signal generator (
50) and a current comparator (52) that emits to both comparators (
51), <52) is programmed to process the output from the output port (Pl) or P7) to "1" or "0".
” control signal generator (50) that issues a control signal, and the input port (I4
) for 3 seconds and 1, respectively, using the reference pulse from
It is composed of a timer device (53) and (54) that count the time of 0 minutes.

Table 1 It is assumed that the cooling/heating selection switch (22) is open during the current cooling season. When the operation switch (19) is closed, the microcomputer (20) uses the "0" signal from the input capo-1-(II) to cause the cooling/heating command device (45) to issue a cooling command to the control signal generator (50). With Kapo-1-(
The secondary refrigerant inflow temperature data of the user-side heat exchanger (6) entering from I2) is stored in the storage device (46). -And when the secondary refrigerant inflow temperature is 14°C, as is clear from the characteristics shown in Fig. 5, the temperature comparator (51) does not output capo-1-(P3) to the control signal generator (50). Shikuku P6
) to issue a control signal (1, 1, 1, 1), the control relay (31
) to 34) are all energized. Therefore, the power relay (41) is energized, the drive motor (CM) operates, and the capacity adjustment relay (42) or 44)
is excited, the compressor (1) operates at 100% compression capacity, and the secondary refrigerant completely cooled by the user-side heat exchanger (6) is supplied to the fan coil (18) to cool the room. Driving takes place. In addition, “1” is also output from output capo-1-(P2).
'' signal is supplied, the control relay (P2) is energized and the power relay (40) is energized, so the drive motor (
FM) is operated, the blower (15) is operated, and the output port (circle) is supplied with a “0” signal and the control relay (2
9) is not energized and the four-way valve excitation relay (39) is also not energized, so the four-way valve <2) is in the solid line state.

During this operation, when the secondary refrigerant inflow temperature of the user-side heat exchanger (6) falls below 10°C, the control signal generator (50) is activated by a command from the temperature comparator (51). .0]
The control relay (34) and capacity adjustment relay (44) are de-energized and the compressor (1) starts emitting a control signal.
As a result, when the secondary refrigerant inflow temperature started to rise and exceeded 12°C, the compressor was turned off again to 12°C.
Return to 00% operation. Conversely, when the secondary refrigerant inflow temperature further decreases and becomes less than 9°C, the control signal generator (50) issues a control signal of [:1,1,0°0], and then the control relay (33) and turn off the power to the capacity adjustment relay (43),
The compressor (1) is operated at 50% capacity. In this way, the control signal generating device (50) is configured as a temperature comparing device (50) that compares the secondary refrigerant inflow temperature and the set value according to the characteristics shown in FIG.
In response to the command 1), the compressor (1) is automatically controlled in five stages from 0 (stop) to 100% so that the compression capacity matches the load. Note that the current comparator (52) is connected to the storage device (48).
), the operating current of the drive motor (CM), the first setting value 265A and the second setting value 2 of the storage device (49).
A comparison is made with 95A. The second set value is set close to the maximum allowable current of the drive motor (CM) of the compressor (1), and the first set value is set to approximately 90% of the second set value.

When the compressor (1) is operating at 100% compression capacity, the outside temperature rises and the refrigerant pressure on the high pressure side of the refrigerant circuit (8) increases, causing an overload on the compressor (1). When there is a voltage fluctuation in the AC power supply (38) and the power supply voltage drops by about 10%, the operating current of the drive motor (CM) increases. As shown in Fig. 7, when the operating current of the drive motor (CM) of the compressor (1) exceeds 265A,
The current comparison device (52) first issues a set command to the timer device (53). When the timer device (53) finishes counting for 3 seconds and times up, the current comparator (53)
2) Check again whether the operating type flow exceeds 265A.

The reason for reconfirming after 3 seconds is to exclude cases where the operating current of the drive motor (CM) increases instantaneously, such as when switching the compression capacity of compressor (1). . In this case, since the operating current continues to exceed 265A, the current comparator (52)
The control signal generator (50) outputs an output A to the output port (P3) regardless of the output of the temperature comparator (51).
or P6) to issue a control signal [:1,1,1°0] to cause the compressor (1) to operate at 75% compression capacity and issue a reset command to the timer device (53). It also issues a set command to the timer device (54).

By switching the compressor (1) from 100% operation to 75% operation, the load on the compressor (1) and drive motor (CM) is reduced, and the operating current of the drive motor (CM) is reduced as shown in the figure. Declines rapidly. When the timer device (53) times up after 3 seconds, the current comparator (52)
) calculates the return current value based on the operating current value at this point. That is, if the operating current value is 212A, the return current value will be 207A, which is 5A less. As a result, the current comparator (52) issues a time-up command after the timer device <54) finishes counting for 10 minutes, and outputs A until the operating current falls below the return current.
), and the compressor (1) continues to operate at 75% compression capacity. Therefore, if the cause of the increase in the operating current of the drive motor (CM) is a temporary increase in high pressure in the refrigerant circuit (8) or a fluctuation in the power supply voltage, the operating current may increase during time counting by the timer device (54). Even if the current falls below the return current, 75% operation continues until the timer device (54) times out.

In addition, if the cause of the increase in operating current does not go away for a long time, the timer device (54)
% operation continues, and the outside temperature drops and the high pressure in the refrigerant circuit (8) decreases, or the power supply voltage returns to a steady value, the cause of the increase in the operating current disappears, and the operating current falls below the recovery current. 75% operation is completed and returns to 100% operation.

When the compressor (1) is operating at a small capacity of 75% or less, the above-mentioned capacity change control is not performed even if the operating current exceeds 265A. If the operating current of the drive motor (CM) exceeds 265A while the compressor (1) is operating at a small capacity, it may be due to a failure of the blower (15) or a failure of the drive motor (CM).
This is because extremely abnormal conditions such as being restrained are possible.

Therefore, the current comparator (52) issues an output B to the control signal generator (50) when the operating current exceeds 295A, and the control signal generator (50) issues a "0" signal from the output port (P2). to stop the blower (15) and to output [0,0,0
, 0) is issued to stop the compressor (1), and a 41'' signal is issued from the output port (P7>) to enable the alarm lamp (36) to light up to indicate an abnormal condition. The same control is performed when the operating current exceeds 295 A during the small capacity operation changeover from % to 75%.This state is canceled when the abnormality is repaired and a reset key (not shown) is pressed.

During the heating period when the cooling/heating changeover switch (22) is closed, the control signal generator (50) emits a "1" signal from the output port (Pl) in response to the heating command from the cooling/heating command device (45), and the control relay (29) energize the four-way valve excitation relay (3
9) is energized, and the four-way valve (2) is switched to the broken line state. The temperature comparison device (51) compares the secondary refrigerant temperature stored in the storage device (46) with the storage device 47).
A command is issued to the control signal generator (50) to control the compression capacity of the compressor (1) so that the characteristics shown in FIG. The degree of heating of the secondary refrigerant in the exchanger (6) is fully adjusted, and the fan coil (18) performs an appropriate heating operation. In this case as well, while the compressor (1) is operating at 100% compression capacity, the operating current of the drive motor (CM) is set to the first set value (265A).
When the temperature exceeds 1, the compressor is controlled in the same manner as during cooling, and the load on the compressor (1) and drive motor <CM) is reduced to allow continued operation. Furthermore, the same applies when the operating current exceeds the second set value (295A) during small capacity operation of 75% or less.

Note that each of the above-mentioned setting values is appropriately selected depending on the model used, and is not limited to the numerical values shown in the figure.

(G) Effects of the Invention The control device of the present invention adjusts the operating capacity of the compressor whose operating capacity can be changed based on the load temperature. It is possible to keep the range of temperature fluctuations small, and it is possible to save energy by not using excess operating capacity.

In addition, since the current flowing through the compressor drive motor is detected, if the current increases rapidly during overload and this current value exceeds the first set value, the operating capacity of the compressor is reduced and the current does not increase any further. This prevents burnout of the drive motor.

In addition, if the current value falls below the second set value, the operating capacity of the compressor is increased again, and if the cause of the overload has been resolved, the operating capacity is changed again based on the load temperature and the load is increased. Reduce the temperature fluctuation range of the load and stabilize the load temperature.

Therefore, by using the control device of the present invention, the operating capacity of the compressor can be controlled from two sides: the temperature of the load and the current flowing to the drive motor of the compressor. In both cases, it is possible to always suppress the load temperature fluctuation range to the minimum. That is, stable temperature control of the load and prompt protection against overload operation can be performed reliably.

[Brief explanation of the drawing]

FIG. 1 is a refrigerant circuit diagram showing an example of a refrigerator to which the present invention can be applied, FIGS. 2 and 3 are electric circuit diagrams showing an example of using the method of the present invention, and FIG. A block diagram showing an example of the internal system of the microcomputer shown in the figure, and FIGS. 5 to 7 are explanatory diagrams for explaining the operation of the apparatus using the present invention. (1)...Compressor, (3)...Heat source side heat exchanger,
(5)...Pressure reduction device, (6)...Using side heat exchanger, (8)...Refrigerant circuit, (20)...Microcomputer, (25)...Operating current measurement circuit, (
50)...Control signal generator, (52)...Current comparator, (CM)...Compressor drive motor.

Claims (1)

[Claims] (1) In a refrigerator equipped with a refrigerant circuit that connects an electric compressor whose operating capacity can be changed, a heat source side heat exchanger, a pressure reducing device, and a user side heat exchanger provided on the load side, A capacity control unit that changes the operating capacity of the compressor based on the temperature of the load, and reduces the operating capacity of the compressor when the value of the current flowing through the drive motor once exceeds a first set value. a capacity reduction control unit that outputs a signal to the capacity control unit, and increases the operating capacity of the compressor when the value of the current once falls below a second set value that is lower than the first set value after outputting the signal; and a capacity increase control unit that outputs a signal to the capacity control unit to increase the capacity.