JPH0471135B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Field of Industrial Application The present invention relates to a refrigerator equipped with a refrigerant circuit that connects a compressor with switchable operating capacity, a heat source side heat exchanger, a pressure reducing device, and a user side heat exchanger. It is. (B) Prior Art As shown in FIG. 1, a refrigerator to which the present invention is applied includes a compressor 1 whose compression capacity can be switched, 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. Note that 9 and 10 are check valves for cooling, and 11 and 12 are check valves for heating. 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 line arrow during cooling, and in the direction of the broken line arrow during heating, and flows through the four-way valve 2 and the accumulator 7. and returns to the compressor 1 from the suction line 14. At this time, the heat source side heat exchanger 3 acts as a condenser during cooling and as an evaporator during heating, and the blower 15 promotes heat exchange with outside air. In addition, 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. The cold/hot water is circulated through the secondary refrigerant circuit 16 by the pump 17 and supplied to the fan coil 18, where heat exchange between the cold/hot water and indoor air is performed, thereby cooling or heating the room. In this type of refrigerator, when performing cooling operation, the refrigerant pressure on the high-pressure side of the refrigerant circuit 8 (for example, the heat source side heat exchanger 3) increases due to various reasons, resulting in an overload state, which places a burden on the compressor 1. may apply. For example, when the outside temperature is high, when the blower 15 air shoots or breaks down, when the refrigerant in the refrigerant circuit 8 becomes overfilled, when the secondary refrigerant temperature is high during initial operation, etc. is possible. Also, when performing heating operation, if there is insufficient water in the secondary refrigerant circuit 16, a mistake in the setting value of the thermo device for adjusting the compression capacity of the compressor 1, or a large heating load due to high outside temperature, the refrigerant circuit 8 The refrigerant pressure on the high-pressure side (for example, the user-side heat exchanger 6) increases, resulting in an overload condition. In conventional refrigerators, these overload conditions are detected by, for example, a pressure switch for high pressure cut provided in the discharge line 13 of the refrigerant circuit 8, and the compressor is stopped. (c) Problems to be Solved by the Invention In conventional refrigerators configured as described above, the set value is set as high as possible in order to prevent the pressure switch from frequently operating, resulting in high pressure cuts and interrupting operation. It is set and takes time to operate,
The compressor could not be adequately protected. or,
As described in Japanese Patent Publication No. 48-10334, there were some systems that switched the compressor to small capacity operation using a pressure switch, but in the case of a temporary overload condition,
Since high-capacity operation←→low-capacity operation is repeated in a short period of time, there is a risk that the capacity adjustment mechanism of the compressor may be damaged. The present invention has been made in view of the above-mentioned fact, and is designed to switch the compressor to small capacity operation when the refrigerant circuit becomes overloaded, thereby preventing high pressure cut and allowing continued operation. The present invention provides a refrigerator whose compressor is protected against loads. (d) Means for Solving the Problems The refrigerator of the present invention has a heat pump type refrigerant circuit in which a variable capacity compressor, a four-way valve, a heat exchanger on the heat source side, a pressure reducing device, a heat exchanger on the user side, etc. are connected in sequence. , a high-pressure switch that operates to stop operation when the high pressure of the refrigerant circuit exceeds a certain value; and a temperature sensor attached to the user-side heat exchanger; means for changing the capacity of the compressor according to the difference between the load temperature and the set temperature;
means for operating during heating operation when the temperature detected by the temperature sensor is between a first set temperature and a second set temperature higher than the first set temperature to maintain the capacity of the compressor at that time; and a means for reducing the capacity of the compressor, which operates when the temperature detected by the temperature sensor is equal to or higher than a second set value during heating operation. (e) Effect In the refrigerator configured as described above, based on the temperature of the heat exchanger on the user side, when this temperature is below the first set temperature, the capacity of the compressor is changed normally, and the temperature is changed to the first temperature. Each means maintains the capacity of the compressor as it is when the temperature is between the first set temperature and the second set temperature, and reduces the compressor capacity when the temperature is higher than the second set temperature. It is. This suppresses an overload condition in which the temperature of the heat exchanger on the user side rises, and suppresses the operation of the high pressure switch due to overload. (f) Embodiment Hereinafter, an embodiment of the present invention will be described based on the drawings, applying it to the refrigerator shown in FIG. In FIG. 2, l is a bus bar to which a constant DC voltage is supplied via the operation switch 19. A microcomputer 20 has a power terminal BT connected to a bus line l, and an oscillator 21 that determines the free running time of the microcomputer 20 is connected between clock terminals CL1 and CL2. 22 is a heating/cooling selection switch, one end of which is connected to the bus line I, and the other end of which is connected to the input port I1 of the microcomputer 20. 23 is a secondary refrigerant temperature measurement circuit that is supplied with a DC constant voltage from the bus l and that converts the analog signal of the temperature sensor 24, which is attached to the heat exchanger 6 on the user side and detects the secondary refrigerant inflow temperature, into a binary digital signal. and its output end is connected to input port I2. 2
5 and 26 are a temperature sensor that detects the high pressure side refrigerant temperature (temperature of the user side heat exchanger during heating) in the discharge line 13 of the refrigerant circuit 8, and a pressure switch that detects the refrigerant pressure (turns on at 24 kg/cm ² ), one end of which is connected to bus line l, and the other end connected to input ports I3 and I4, respectively. The temperature sensor 25 detects a second temperature.
The circuit is closed when the temperature is equal to or higher than the first set value, and then the circuit is closed when the temperature is lower than the first set value (<the second set value). The pressure switch 26 closes when the detected value is approximately 24 kg/cm ² (a pressure higher than the pressure corresponding to the second set temperature). A reference pulse generator 27 generates reference pulses of a predetermined frequency using a constant DC voltage supplied from the bus line I, and its output end is connected to the input port I5. 28 is a control relay 29 for the four-way valve 2, and a blower 15
power control relay 30 for the compressor 1, power control relay 31 for the compressor 1, and capacity adjustment mechanism control relays 32 to 3.
One end of each relay is connected to bus line l, and the other end is connected to output ports P1 to P6 through drivers 35 each having a reversing mechanism.
It is connected to the. 36 is a warning lamp, one end of which is connected to the bus line l, and the other end of which is connected to the output port P7 via a driver 37 having a reversing function. FIG. 3 shows the internal system of the microcomputer 20.
0 is a cooling/heating command device 38 that issues a cooling or heating command depending on whether a low level signal "0" or a high level signal "1" is present at the input port I1, and the input port I2. Temperature storage device 39 that stores the latest temperature data sent by
, a setting value storage device 40 in which a setting value to be compared with the temperature data in the storage device 39 is stored, and a high level “1” signal (temperature sensor 25
a first alarm device 41 that operates to generate an output A that reduces the capacity of the compressor when the temperature detected by the temperature sensor 25 is equal to or higher than a second set value; and an input port. A second alarm device 42 emits output B when there is a high-level “1” signal on I4, and a program (not shown) processes signals from each device to output “1” from output ports P1 to P7.
or a control signal generator 43 that generates a control signal of "0"; a timer device 44 that counts time for 3 seconds and 10 minutes, respectively, using a reference pulse from the input port I5 according to a command from the device 43; It consists of 45. The set value storage device 38 has set values for cooling and heating, which are compared with the secondary refrigerant temperature, determined as shown in FIGS. 4 and 5, and the control signal generator 43
compares the storage contents of both storage devices 39 and 40 and issues the control signals shown in Table 1 from the output ports P3 to P6 to change the compression capacity of the compressor 1 from 0 (stop) to 100%.
Adjust to 5 levels. Therefore, when the output A of the first alarm device 41 or the output B of the second alarm device 42 is not output, that is, when the detected temperature of the temperature sensor is lower than the first set temperature, and the pressure switch 26
The compressor has means for changing the capacity of the compressor according to the difference between the secondary refrigerant temperature (load temperature) and the set temperature stored in the set value storage device 40 when the detected value is about 24 kg/cm ² or less. ing. Moreover, the control signal generator 4
3 receives a cooling command or a heating command from the cooling/heating command device 38 and outputs a "0" signal or "1" from the output port P1.
A signal is issued to control the control relay 28, and the four-way valve 2
It has means for performing switching control. Furthermore,
The control signal generator 43 operates when the first alarm device 41 outputs the output A, that is, when the temperature detected by the temperature sensor 24 exceeds the second set temperature, and has means for reducing the capacity of the compressor. Note that this means issues a set command to the timer device 44 when output A is output, and if output A is still present after 3 seconds, the capacity of the compressor is actually reduced, so a time lag of 3 seconds is provided. Therefore, the first alarm device 41
This prevents a decrease in compressor performance due to malfunction or generation of output A due to noise. Moreover, the operation of this means is from output port P3 to P6 [1, 1,
1, 0] control signals to operate compressor 1 at 75% capacity. At the same time, this means is a timer device 45.
Issue a set command to. In addition, the control signal generator 43 has a compressor capacity of 75
% and the temperature detected by the temperature sensor is between the first set value and the second set value, the capacity of the compressor 1 is not increased and the capacity is maintained at 75%. There is. The period in which the capacity of the compressor 1 is not increased by this means is continued by the timer device 45 at least until the timer device 45 times out. Thereafter, as shown in FIG. 6, when the temperature detected by the temperature sensor 24 falls below the first set temperature, the capacity of the compressor is returned to 100%. Further, the control signal generator 43 is a means for stopping the compressor 1 by emitting a [0, 0, 0, 0] signal when receiving an output from the second alarm device 42, even if any compression capacity operation command is in progress. This means emits a "1" signal from the output port P7 to light up the alarm lamp 36. Note that the control relay 30 is excited by a "1" signal supplied from the output port P2 while the compressor 1 is in operation, and causes the blower 15 to operate.

[Table] During the heating period when the cooling/heating selection switch 22 is closed, the control signal generator 43 emits a “1” signal from the output port P1 to excite the control relay 29 in response to the heating command from the cooling/heating command device 38, and the four-way valve 2 Switch to the broken line state. The control signal generator 43 then compares the secondary refrigerant temperature stored in the storage device 39 with the setting value for heating in the storage device 40, and determines the compression capacity of the compressor 1 as shown in the characteristics in FIG. The heating of the secondary refrigerant in the user-side heat exchanger is adjusted so that the fan coil 18 performs an appropriate heating operation. For example, when the secondary refrigerant inflow temperature is 38°C, as is clear from the characteristics shown in FIG. The control relays 31 to 34 are all energized via the driver 35. For this reason, compressor 1
is operated at 100% compression capacity, and the secondary refrigerant heated by the user-side heat exchanger 6 is supplied to the fan coil 18 to perform indoor heating operation.
Furthermore, a “1” signal is also supplied from output port P2,
The control relay 30 is energized and the blower 15 operates. During this operation, when the secondary refrigerant inflow temperature of the user-side heat exchanger 6 exceeds 42°C, the control signal generator 43 starts to generate control signals [1, 1, 1, 0], and the compressor 1 As a result, when the secondary refrigerant inflow temperature starts to fall and exceeds 40°C, the compressor 1 is returned to 100% operation. Conversely, when the secondary refrigerant inflow temperature further increases and exceeds 43°C, the control signal generator 43 changes to [1, 1, 0, 0].
A control signal is issued to operate compressor 1 at 50% capacity. In this way, the control signal generator 43
The secondary refrigerant inflow temperature is compared with a set value according to the characteristics shown in the figure, and the compressor 1 is automatically controlled in five stages from 0 (stop) to 100% so that the compression capacity matches the load. During 100% capacity operation of the compressor 1, when the refrigerant pressure on the high-pressure side of the refrigerant circuit 8 increases due to a drop in outside temperature, etc., and the refrigerant temperature on the high-pressure side increases, the temperature sensor 25 provided in the discharge line 13 detects this. Temperature is the 6th
As shown in the figure, when the second set value is exceeded, the first alarm device 41 outputs an output A to the control signal generator 43. Accordingly, the control signal generator 43 issues a set command to the timer device 44. Three seconds later, when the timer device 44 times up and this signal is present, the control signal generator 43 generates [1,
1, 1, 0] control signal to reduce compressor 1 to 75%.
The compression capacity operation is started and the timer device 45 is activated.
Issue a set command to Compressor 1 starts from 100% operation
By switching to 75% operation, the high pressure side temperature drops as shown. At this time, the compressor 1 is prevented from returning to 100% operation unless the high pressure side temperature falls below the first set value (output A disappears).
That is, when the high pressure side temperature is between the first set temperature and the second set temperature, the compressor 1 is maintained at 75% operation. Furthermore, the control signal generator 43 continues the 75% compression capacity operation regardless of the presence or absence of the output A while the timer device 45 is counting the 10 minutes. If the refrigerant pressure increase on the high pressure side of the refrigerant circuit 8 is due to a primary cause such as a short air shot or a high secondary refrigerant temperature at startup, the pressure switch 25 will open before 10 minutes have passed. In this case, as shown in FIG. 6, when the timer device 45 times up, the compressor 1 is turned off to 100%
Return to capacity operation. On the other hand, if the cause of the increase in refrigerant pressure is a drop in outside temperature and it continues for a long time, the outside temperature will continue to rise even after the timer device 45 times up, causing the high-pressure side refrigerant temperature to fall below the first set temperature, causing the temperature sensor 25 to rise. Operation at 75% compression capacity will continue until the circuit is opened. Furthermore, when the high-pressure side refrigerant pressure exceeds 24 kg/cm ² and the pressure switch 26 is closed, the output B of the second alarm device 42 enters the control signal generator 43, so that the control signal generator 43 outputs the signal from the output port P3 or A [0, 0, 0, 0] signal is emitted from P6 to stop the compressor 1, a "1" signal is emitted from the output port P2 to stop the blower 15, and a "1" signal is emitted from the output port P7. Warning lamp 36
lights up to indicate an abnormal condition. In addition, when the cooling/heating selection switch 22 is closed during the cooling period, the four-way valve 2 is switched to the state shown by the solid line, and the refrigerant flows in the direction of the solid line arrow, thereby performing the operation for the cooling period. FIG. 4 is an explanatory diagram showing the secondary refrigerant temperature and compressor capacity ratio during the cooling period. (G) Effects of the Invention The present invention provides a heat pump type refrigerant circuit in which a variable capacity compressor, a four-way valve, a heat exchanger on the heat source side, a pressure reducing device, a heat exchanger on the user side, etc. are connected in sequence, and the high pressure of this refrigerant circuit. a high-pressure switch that operates to stop the operation when the temperature exceeds a certain value, a temperature sensor attached to the user-side heat exchanger, and a temperature sensor attached to the user-side heat exchanger; means for operating and changing the capacity of the compressor according to the difference between the load temperature and the set temperature; and during heating operation, the temperature detected by the temperature sensor is higher than the first set temperature. a means for operating the compressor when the temperature is between a second set temperature and maintaining the current capacity of the compressor; and means to reduce the ability of
When the temperature of the user-side heat exchanger exceeds the second set value, the operating capacity of the compressor is reduced to prevent the temperature of the user-side heat exchanger from rising any further. That is, when the temperature of the heat exchanger on the user side rises, the high pressure in the refrigerant circuit, which is rising at the same time, can be suppressed from exceeding a certain value, and frequent activation of the high pressure switch can be prevented. Furthermore, since the means for maintaining the capacity of the compressor suppresses an increase in the capacity of the compressor and reduces energy consumption, it is possible to provide a refrigerator that also provides an energy-saving effect.

[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, FIG. 2 is an electric circuit diagram showing an embodiment of the refrigerator of the present invention, and FIG. 3 is a diagram of the microcomputer shown in FIG. A block diagram showing an example of the internal system, and FIGS. 4 to 6 are explanatory diagrams for explaining the operation of this embodiment. 1...Compressor, 3...Heat source side heat exchanger, 5...
Pressure reducing device, 6... User side heat exchanger, 8... Refrigerant circuit, 20... Microcomputer, 25... Temperature sensor, 31 to 34... Control relay, 43
...Control signal generator.

Claims (1)

[Claims] 1 variable capacity compressor, four-way valve, heat source side heat exchanger,
In a refrigerator that has a pressure reducing device, a heat pump refrigerant circuit connecting a user-side heat exchanger with refrigerant piping, and a control device that controls the operation of a variable capacity compressor,
The control device includes a high pressure switch that stops the operation of the variable capacity compressor when the high pressure of the heat pump refrigerant circuit exceeds a certain pressure during air conditioning operation, and a high pressure switch that stops the operation of the variable capacity compressor when the high pressure of the heat pump refrigerant circuit exceeds a certain pressure during air conditioning operation, and a high pressure switch that stops the operation of the variable capacity compressor when the high pressure of the heat pump refrigerant circuit exceeds a certain pressure during air conditioning operation, and a high pressure switch that stops the operation of the variable capacity compressor when the high pressure of the heat pump type refrigerant circuit exceeds a certain pressure during air conditioning operation. When the temperature is below the set pressure, means for changing the operating capacity of the variable capacity compressor based on the load temperature and the set temperature, and a means for changing the operating capacity of the variable capacity compressor based on the temperature of the load and the set temperature, and a means for changing the operating capacity of the variable capacity compressor based on the temperature of the user side heat exchanger are lower than the temperature corresponding to the constant pressure. A refrigerator comprising means for reducing the operating capacity of the variable capacity compressor when the temperature is higher than a second set temperature, which is higher than the set temperature.