JP2001227823A - Refrigerating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigerating device for optimizing the discharge temperature of a compressor without decreasing efficiency and for improving COP and reliability by using a working medium containing the R32 refrigerant. SOLUTION: This refrigerating device is provided with a refrigerant circuit where a compressor 1, an indoor heat exchanger 3, a main electric motor- operated valve EV1, and an indoor heat exchanger 5 are connected annularly, and the R32 refrigerant or a mixed refrigerant containing at least 70 wt.% of R32 is used for a working medium. A supercooling heat exchanger 11 is arranged between the indoor heat exchanger 3 and the main electric valve EV1, and the gas side and the liquid side of the refrigerant circuit are bypassed via the supercooling heat exchanger 11 by bypass piping 33 and 34. An electric motor-operated valve EV2 for supercooling is arranged at the upstream side of the supercooling heat exchanger 11 of the bypass piping 33. A discharge temperature being detected by a discharge temperature sensor 21 is judged by a discharge temperature judgment part 10b, the opening of the electric valve EV2 for supercooling is controlled based on the judgment result, and the amount of refrigerant flowing to the bypass piping 33 and 34 is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a refrigeration apparatus using a working refrigerant containing R32 (chemical formula CH ₂ F ₂₎ refrigerant.

[0002]

2. Description of the Related Art Conventionally, as a refrigerating apparatus, there is a heat pump type using an HCFC-based refrigerant. This refrigerating apparatus has a refrigerant circuit in which a compressor, a condenser, a motor-operated valve, and an evaporator are connected in a ring shape, and has a supercooling heat exchanger between the condenser and the motor-operated valve. The gas refrigerant from the compressor is returned to the liquid injection of the compressor or to the suction side of the compressor. However, in the above-described refrigeration apparatus, since the refrigerant circulating amount is reduced by bypassing the refrigerant, the coefficient of performance COP (c
oefficient of performance). HCFC-based refrigerants have an ozone depletion potential and GW
There is also a problem that P (global warming potential) is large and deteriorates the global environment.

[0003] Therefore, R3 is used as a low GWP HFC-based refrigerant which can realize a high COP and does not destroy the ozone layer.
It is conceivable to use two refrigerants. However, R3
Since the refrigerant 2 has a higher discharge temperature than the HCFC-based refrigerant due to the physical properties of the refrigerant, there is a problem that the refrigerating machine oil is deteriorated and the reliability is reduced.

Accordingly, an object of the present invention is to provide a refrigeration apparatus which can optimize the discharge temperature of a compressor without lowering efficiency and improve COP and reliability by using a working medium containing R32 refrigerant. It is in.

[0005]

According to a first aspect of the present invention, there is provided a refrigeration apparatus comprising: a refrigerant circuit in which a compressor, a condenser, a main pressure reducing means, and an evaporator are connected in a ring; A supercooling heat exchanger disposed between the main pressure reducing means, a bypass pipe for bypassing a gas side and a liquid side of the refrigerant circuit via the supercooling heat exchanger, What is claimed is: 1. A refrigerating apparatus comprising: a subcooling depressurizing means disposed upstream of a subcooling heat exchanger, wherein the refrigerant uses an R32 refrigerant or a mixed refrigerant containing at least 70% by weight or more of R32 and discharges the compressor. A discharge temperature sensor for detecting a temperature, a discharge temperature determining unit for determining a discharge temperature detected by the discharge temperature sensor, and controlling the supercooling pressure reducing means based on a determination result of the discharge temperature determining unit, Above bypass piping It is characterized in that a control unit for controlling the amount of coolant flowing through.

According to the refrigerating apparatus of the first aspect, the R32 refrigerant (or the mixed refrigerant containing at least 70% by weight of R32) discharged from the compressor is condensed in a condenser and then the main decompression means. The refrigerant decompressed in step evaporates in the evaporator and returns to the suction side of the compressor. At this time, the refrigerant depressurized by the subcooling decompression means is bypassed from the gas side of the refrigerant circuit to the liquid side downstream of the evaporator via the subcooling heat exchanger by the bypass pipe, and the subcooling heat exchanger Supercools the refrigerant flowing from the condenser to the main pressure reducing means. Then, the discharge temperature detected by the discharge temperature sensor is determined by the discharge temperature determining unit, and the control unit controls the supercooling decompression unit based on the determination result. By controlling the amount of refrigerant flowing through the pipe to be large or small, when the discharge temperature is high, the amount of bypass refrigerant can be increased to lower the discharge temperature. Therefore, even if an R32 refrigerant (or a mixed refrigerant containing at least 70% by weight or more of R32) having a discharge temperature higher than that of the HCFC-based refrigerant is used in terms of refrigerant physical properties, the optimum discharge temperature can be obtained without lowering the efficiency. And reliability can be improved. In addition, an electric valve may be used as the supercooling pressure reducing means, the opening degree of the electric valve may be controlled to control the amount of the bypass refrigerant, or an electromagnetic valve and a capillary may be combined as the supercooling pressure reducing means, The amount of the bypass refrigerant may be controlled by opening and closing the valve.

According to a second aspect of the present invention, in the refrigerating apparatus according to the first aspect, the control section flows to the bypass pipe when the discharge temperature determining section determines that the discharge temperature has exceeded an upper limit set value. While controlling the supercooling pressure reducing means so that the refrigerant amount increases, if the discharge temperature determination unit determines that the discharge temperature is less than the lower limit set value, the refrigerant amount flowing through the bypass pipe is reduced. It is characterized in that the supercooling pressure reducing means is controlled.

According to the refrigerating apparatus of the second aspect, when the discharge temperature determining section determines that the discharge temperature has exceeded the upper limit set value, the control section controls the excess temperature so as to increase the amount of refrigerant flowing through the bypass pipe. The cooling pressure reducing means is controlled.
On the other hand, when the discharge temperature determination section determines that the discharge temperature is lower than the lower limit set value, the control section controls the supercooling pressure reducing means so that the amount of refrigerant flowing through the bypass pipe is reduced. By doing so, more optimal discharge temperature control can be performed without lowering the efficiency.

The refrigeration apparatus according to claim 3 is the refrigeration apparatus according to claim 1 or 2, wherein the subcooling decompression means comprises:
A motor valve for supercooling, a condensing temperature sensor for detecting a condensing temperature of the condenser, an evaporating temperature sensor for detecting an evaporating temperature of the evaporator, a condensing temperature detected by the condensing temperature sensor, A target discharge temperature calculating section for calculating a target discharge temperature based on an evaporating temperature detected by an evaporating temperature sensor and an opening of the electric motor valve for supercooling, wherein the control section controls a discharge temperature of the compressor. Is characterized in that the main pressure reducing means is controlled so as to reach the target discharge temperature.

According to the refrigeration apparatus of the third aspect, the condensation temperature of the condenser detected by the condensation temperature sensor, the evaporation temperature of the evaporator detected by the evaporation temperature sensor, and the Based on the opening degree of the motor-operated valve, the target discharge temperature calculating section calculates a target discharge temperature suitable for an operating condition (cooling / heating and operating frequency of the compressor, etc.). On the basis of the target discharge temperature calculated by the target discharge temperature calculation unit, the control unit controls the main pressure reducing unit to control the amount of refrigerant flowing in the refrigerant circuit, thereby setting the discharge temperature of the compressor to a target value. The discharge temperature is set. Therefore, it is possible to control the discharge temperature to an optimum value according to the amount of refrigerant flowing through the bypass pipe, that is, the degree of supercooling.

The refrigerating apparatus according to a fourth aspect of the present invention is the refrigerating apparatus according to the third aspect, further comprising an evaporator outlet temperature sensor for detecting an evaporator outlet temperature of the evaporator, and the control unit calculates the target discharge temperature. The main pressure reducing means and the supercooling electric valve are controlled based on the target discharge temperature calculated by the section and the evaporator outlet temperature detected by the evaporator outlet temperature sensor.

According to the refrigeration apparatus of the fourth aspect, the evaporator outlet temperature sensor detects the evaporator outlet temperature of the evaporator, and the target discharge temperature calculated by the target discharge temperature calculator and the evaporator outlet temperature. Based on the evaporator outlet temperature detected by the temperature sensor, the control unit controls the main decompression unit and the subcooling decompression unit. By using the evaporator outlet temperature for controlling the discharge temperature of the compressor,
The controllability of the amount of refrigerant flowing through the bypass pipe, that is, the degree of supercooling, can be improved.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The refrigeration system of the present invention will be described below in detail with reference to the embodiments shown in the drawings.

(First Embodiment) FIG. 1 is a circuit diagram showing a schematic configuration of a heat pump type air conditioner as a refrigeration apparatus according to a first embodiment of the present invention, wherein 1 is a compressor, and 2 is the compressor. 1 is a four-way switching valve connected to the discharge side, 3 is an outdoor heat exchanger having one end connected to the four-way switching valve 2, 4 is a bridge circuit as rectifying means, 5 is the indoor heat exchanger 5 is An accumulator connected to the indoor heat exchanger 5 via the four-way switching valve 2.

The bridge circuit 4 has check valves 4A, 4B, 4C and 4D that allow the flow of the refrigerant only in one direction, and has two input / output ports, one input port and one output port. are doing. The outdoor heat exchanger 3 is connected to one input / output port of the bridge circuit 4, and the indoor heat exchanger 5 is connected to the other input / output port. The check valve 4A is connected to one of the input / output ports in a direction allowing the flow of the refrigerant from the outdoor heat exchanger 3, and the check valve is connected in a direction allowing the flow of the refrigerant from the indoor heat exchanger 5. 4B is connected to the other input / output port, and the check valves 4A and 4B are connected to the output port in contact with each other. On the other hand, the check valve 4C is connected to the input / output port to which the check valve 4B is connected in a direction allowing the flow of the refrigerant to the indoor heat exchanger 5, and the flow of the refrigerant to the outdoor heat exchanger 3 Check valve 4
D is connected to the input / output port to which the check valve 4A is connected, and the check valves 4C and 4D are connected to the input port in contact with each other.

Then, one end of a pipe 31 is connected to the output port of the bridge circuit 4, and the other end of the pipe 31 is connected to one end of an outer pipe 11 a of the subcooling heat exchanger 11. on the other hand,
One end of the pipe 32 is connected to the input port of the bridge circuit 4, and the other end of the pipe 32 is connected to the outer pipe 11 of the subcooling heat exchanger 11.
Connected to the other end of a. A main motor-operated valve EV1 as main pressure reducing means is provided in the pipe 32. The pipe 31 is provided with a bypass electric valve EV as a subcooling pressure reducing means.
2 is connected to one end of an inner pipe 11b of the subcooling heat exchanger 11 via a bypass pipe 33 provided. On the other hand, the other end of the inner pipe 11b of the supercooling heat exchanger 11 is connected to the four-way switching valve 2
And the accumulator 6 via a bypass pipe 34. In this way, the bridge circuit 4 switches the main motor from the subcooling heat exchanger 11 regardless of the direction in which the refrigerant flows between the outdoor heat exchanger 3 and the indoor heat exchanger 5 by switching between the cooling operation and the heating operation. Refrigerant flows only in the direction of the valve EV1.

The compressor 1, the four-way switching valve 2, the outdoor heat exchanger 3, the main motor-operated valve EV1, the indoor heat exchanger 5, and the accumulator 6 constitute a refrigerant circuit and use R32 refrigerant as a working medium. .

The air conditioner is provided with a discharge temperature sensor 21 for detecting the discharge temperature on the discharge side of the compressor 1 and the outdoor heat exchanger 3, and detects the refrigerant temperature of the outdoor heat exchanger 3. A temperature sensor 22 as a condensation temperature sensor or an evaporation temperature sensor; a temperature sensor 23 provided in the indoor heat exchanger 5 and detecting a refrigerant temperature of the indoor heat exchanger 5 as an evaporation temperature sensor or a condensation temperature sensor; Sensor 2
And a control unit 10 that receives signals from the control units 2, 23, and 24 and controls the cooling and heating operations. The control unit 10 includes a microcomputer, an input / output circuit, and the like. The control unit 10a controls the compressor 1, the main electric valve EV1, the bypass electric valve EV2, and the like, and the temperature sensor 2
And a target discharge temperature calculator 10c for calculating a target discharge temperature based on the discharge temperature, condensation temperature and evaporation temperature detected by the temperature sensors 21 to 23. And

In the air conditioner having the above configuration, when performing the cooling operation, when the four-way switching valve 2 is set to the switching position shown by the solid line and the compressor 1 is started, the high-temperature, high-pressure discharge refrigerant from the compressor 1 is discharged. , The four-way switching valve 2, the outdoor heat exchanger 3, the check valve 4A of the bridge circuit 4, the supercooling heat exchanger 11, and the electric valve 13. The refrigerant decompressed by the electric valve 13 is supplied to the check valve 4D of the bridge circuit 4, the indoor heat exchanger 5,
It flows with the four-way switching valve 2 and returns to the accumulator 6 from the four-way switching valve 2. At this time, in the supercooling heat exchanger 11, the refrigerant flowing into the electric valve 13 is supercooled. In the indoor heat exchanger 5 functioning as an evaporator, the low-temperature and low-pressure liquid refrigerant evaporates, and the evaporated gas refrigerant is discharged from the outlet side.

When performing the heating operation, the four-way switching valve 2
When the compressor 1 is started up with the switch position indicated by a dotted line, the high-temperature, high-pressure discharge refrigerant from the compressor 1 is supplied to the four-way switching valve 2, the indoor heat exchanger 6, the check valve 5B, and the supercooling heat exchange. Vessel 1
1. Flow with the electric valve 13. The refrigerant decompressed by the electric valve 13 flows through the check valve 4C of the bridge circuit 4, the outdoor heat exchanger 3, and the four-way switching valve 2, and returns to the accumulator 6 from the four-way switching valve 2. At this time, the supercooling heat exchanger 1
The high-temperature, high-pressure liquid refrigerant on the upstream side of 1 is supplied to the bypass electric valve E
The refrigerant is expanded by V2 to become a low-temperature, low-pressure gas refrigerant, flows through the subcooling heat exchanger 11, and subcools the refrigerant flowing into the electric valve 13.

As described above, the supercooling heat exchanger 11 is always arranged on the upstream side of the motor-operated valve 13 in the cooling and heating operations by the bridge circuit 4. The operation efficiency is improved by increasing the supercooling of the flowing refrigerant.

Hereinafter, the operation of the control unit 10 will be described with reference to the flowchart of FIG. Although the cooling operation is described with reference to FIG. 2, during the heating operation, the condenser and the evaporator are switched, and condensing temperature Tc and evaporating temperature Te are accordingly changed.
The same processing is performed only by exchanging the temperature sensors 22 and 23 for detecting the temperature.

In FIG. 2, when the cooling operation is started, a discharge temperature Td, a condensing temperature Tc, and an evaporation temperature Te are detected in step S1. That is, the discharge temperature Td on the discharge side of the compressor 1 is detected by the temperature sensor 21 and the temperature sensor 2
2, the condensation temperature Tc of the outdoor heat exchanger 3 as a condenser
Is detected, and the evaporation temperature T of the indoor heat exchanger 5 as the evaporator is detected.
It detects e.

Next, the process proceeds to step S2, where the control device 10
It is determined whether or not the discharge temperature Td exceeds the upper limit set value by the discharge temperature determination unit 10b. If it is determined that the discharge temperature Td exceeds the upper limit set value, the process proceeds to step S3.
Open the bypass motor-operated valve EV2 by a predetermined opening degree, and execute Step S4.
Proceed to.

On the other hand, if it is determined in step S2 that the discharge temperature Td is equal to or lower than the upper limit set value, the process proceeds to step S11,
The discharge temperature determination unit 10b determines whether or not the discharge temperature Td is lower than the lower limit set value. If it is determined that the discharge temperature Td is lower than the lower limit set value, the process proceeds to step S12, while the discharge temperature Td is equal to or higher than the lower limit set value. If it is determined that
Proceed to 4.

Then, in step S12, it is determined whether or not the bypass operation is being performed. If it is determined that the bypass operation is being performed, the process proceeds to step S13, where the bypass motor-operated valve EV2 is closed by a predetermined opening from the current opening. On the other hand, if it is determined in step S12 that the bypass operation is not being performed, the process proceeds to step S4.

Next, in step S4, the target discharge temperature Tk is calculated by the target discharge temperature calculator 10c. The target discharge temperature Tk is calculated based on the condensation temperature Tc, the evaporation temperature Te, and the opening of the bypass electric valve EV2 detected in step S1.

Next, proceeding to step S5, it is determined whether or not the discharge temperature Td detected in step S1 exceeds the target discharge temperature Tk. If it is determined that the discharge temperature Td exceeds the target discharge temperature Tk, step S6 is performed. To open the main motor-operated valve EV1. On the other hand, if it is determined in step S5 that the discharge temperature Td is equal to or lower than the target discharge temperature Tk, the process proceeds to step S7, and the main electric valve EV1 is closed.

FIG. 3 is a Mollier diagram of the above air conditioner, with the vertical axis representing pressure P and the horizontal axis representing enthalpy I. In FIG. 3, for comparison, the case where there is no supercooling heat exchanger (no bypass) and the case where there is a supercooling heat exchanger 11
(With bypass) will be described.

First, the normal cycle without the supercooling heat exchanger changes as shown by the solid line in FIG. On the other hand, the cycle with the heat exchanger when the supercooling heat exchanger 11 is provided changes as shown by the solid line (and the thick solid line) in FIG. That is, the state A on the input side of the compressor 1
The refrigerant at the (evaporator outlet) is changed to a high-pressure state B by the compressor 1, and the refrigerant in the state B is changed to a state C (branch) having a small enthalpy by condensation in the outdoor heat exchanger 3.
Further, the refrigerant on the outlet side of the outdoor heat exchanger 3 is supercooled by the supercooling heat exchanger 11 to be in the state Di.

Then, the refrigerant supercooled by the supercooling heat exchanger 11 is changed to a state E in which the pressure is reduced by expansion of the electric valve EV1, and the refrigerant in that state is changed by the indoor heat exchanger 5. The state is changed to the state A in which the enthalpy is increased by the absorption of heat from the outside air while the pressure is kept substantially constant due to the evaporation. Further, the outlet side of the indoor heat exchanger 5 and the outlet side of the bypass pipe of the subcooling heat exchanger 11 are joined,
By changing from the state A to the state Y, the discharge temperature of the compressor 1 decreases.

As described above, the discharge temperature Td detected by the discharge temperature sensor 21 is determined by the discharge temperature determining section 10d, and the supercooling electric valve EV2 is determined based on the determination result.
To control the bypass pipe 3 according to the level of the discharge temperature.
By controlling the amount of the refrigerant flowing to 3, 34, the discharge temperature can be reduced by increasing the bypass refrigerant amount when the discharge temperature is high. Therefore, even when the R32 refrigerant having a higher discharge temperature than the HCFC-based refrigerant is used in terms of refrigerant physical properties, the discharge temperature of the compressor 1 can be optimized without lowering the efficiency, and the COP and reliability can be improved.

The supercooling electric valve EV2 is controlled by the control unit 10a in accordance with the result of comparison between the discharge temperature and the upper limit set value and the lower limit set value by the discharge temperature determination unit 10b, and flows to the bypass pipes 33 and 34. By appropriately controlling the amount of the refrigerant, more optimal discharge temperature control can be performed.

Further, based on the condensing temperature Tc, the evaporating temperature Te, and the opening of the supercooling electric valve EV2, the target discharge temperature calculating section 10c is suitable for the operating conditions (cooling / heating and operating frequency of the compressor, etc.). Since the target discharge temperature Tk is calculated and the opening of the main electric valve EV1 is controlled by the control unit 10a based on the target discharge temperature Tk, the subcooling electric valve EV2
The control of the discharge temperature of the compressor 1 can be performed more accurately in conjunction with the control of the above.

(Second Embodiment) FIG. 4 is a circuit diagram showing a schematic configuration of a heat pump type air conditioner as a refrigeration apparatus according to a second embodiment of the present invention.
The configuration is the same as that of the air conditioner of the first embodiment except for the operation of the control device 10, and the same components are denoted by the same reference numerals and description thereof is omitted.

As shown in FIG. 4, the air conditioner is provided in the outdoor heat exchanger 3 and is provided in the indoor heat exchanger 5 as a temperature sensor 24 as an evaporator outlet temperature sensor. And a temperature sensor 25 as a sensor. The temperature sensors 24 and 25 are connected to each of the outdoor heat exchanger 3 and the indoor heat exchanger 5 from the respective gas sides by 1 / of the entire heat exchanger.
Attached to a position within 3

The control unit 10 includes a microcomputer, an input / output circuit, and the like. The control unit 10a controls the compressor 1, the main electric valve EV1, the bypass electric valve EV2, and the like. The target discharge temperature is calculated based on the discharge temperature, the condensation temperature, and the evaporation temperature detected by the discharge temperature determination unit 10b that compares the detected discharge temperature with the upper limit set value and the lower limit set value, and the temperature sensors 21 to 23. It has a target discharge temperature calculating section 10c and a target evaporator outlet temperature calculating section 10d based on the evaporation temperature detected by the temperature sensor 22 or 23.

In the air conditioner having the above configuration, the operation of the control unit 10 is the same as that of steps S1 to S4 and S11 to S13 in the flowchart of FIG. Only S7 is different. FIG. 5 shows a flowchart of this different operation.

After calculating the target discharge temperature Tk in step S4 of FIG. 2, the evaporator outlet temperature Ts is calculated in step S21 of FIG.
Is detected. In this case, in the cooling operation, the refrigerant temperature on the outlet side of the indoor heat exchanger 5 serving as an evaporator is detected by the temperature sensor 25, while in the heating operation, the refrigerant temperature on the outlet side of the outdoor heat exchanger 3 serving as an evaporator is detected. Is detected by the temperature sensor 24.

Next, in step S22, the target evaporator outlet temperature Tj is calculated by the target evaporator outlet temperature calculator 10d. The target evaporator outlet temperature Tj is obtained from Tj = evaporation temperature Te + A (A is determined by a table created according to the cooling / heating operating conditions and the compressor operating frequency).

Next, at step S23, it is determined whether or not the discharge temperature Td exceeds the target discharge temperature Tk.
Is determined to have exceeded the target discharge temperature Tk, step S
On the other hand, if it is determined that the discharge temperature Td is equal to or lower than the target discharge temperature Tk, the process proceeds to step S28.

Then, in step S24, it is determined whether or not the evaporator outlet temperature Ts exceeds the target evaporator outlet temperature Tj. If it is determined that the evaporator outlet temperature Ts has exceeded the target evaporator outlet temperature Tj, step S25 is performed. To control section 10a
Thereby, the main motor-operated valve EV1 is further opened by a predetermined opening from the current opening. On the other hand, if it is determined in step S24 that the evaporator outlet temperature Ts is equal to or lower than the target evaporator outlet temperature Tj, the process proceeds to step S26, in which the control unit 10a closes the main motor-operated valve EV1 from the current opening by a predetermined opening, and proceeds to step S27. To open the bypass motor-operated valve EV2 by a predetermined opening from the current opening. Hereinafter, the process returns to step S1 of FIG.

On the other hand, in step S28, the evaporator outlet temperature T
It is determined whether or not s exceeds the target evaporator outlet temperature Tj, and
If it is determined that the evaporator outlet temperature Ts is equal to or lower than the target evaporator outlet temperature Tj, the process proceeds to step S29, and the main motor-operated valve EV1 is closed by a predetermined opening from the current opening by the control unit 10a. On the other hand, if it is determined in step S28 that the evaporator outlet temperature Ts has exceeded the target evaporator outlet temperature Tj, the process proceeds to step S30, and the control unit 10a further opens the main motor-operated valve EV1 by a predetermined opening from the current opening, and proceeds to step S31. To close the bypass motor-operated valve EV2 by a predetermined opening from the current opening. Hereinafter, the process returns to step S1 of FIG.

As described above, the air conditioner has the same effects as the air conditioner of the first embodiment, and also uses the evaporator outlet temperature Ts for controlling the discharge temperature of the compressor 1 so that it can be connected to the bypass pipe. The controllability of the flowing refrigerant amount, that is, the degree of supercooling, can be improved.

In the first and second embodiments, the air conditioner has been described as the refrigerating device, but the present invention may be applied to other refrigerating devices.

In the first and second embodiments, R3
Although the air conditioner as the refrigeration apparatus using the two refrigerants has been described, the refrigerant used in the refrigeration apparatus is not limited to this.
A mixed refrigerant containing at least 70% by weight or more of R32 may be used. For example, a mixed refrigerant of R32 refrigerant and CO ₂ , wherein the R32 refrigerant is 70% by weight or more based on CO ₂ and 9% by weight.
0% by weight or less of the mixed refrigerant may be used.
A refrigerant mixed with a refrigerant, wherein R32 refrigerant is mixed with R32
The refrigerant may be a mixed refrigerant of 70% by weight or more and 90% by weight or less.

In the first and second embodiments, FIG.
Although the air conditioner as the refrigerating apparatus including the refrigerant circuit and the supercooling circuit shown in FIG. 4 has been described, the configuration of the refrigerating apparatus is not limited to this. For example, as shown in FIG. 6, a refrigeration apparatus having a configuration in which a bridge circuit is removed from the configuration of FIG. 1 may be used. In this case, the supercooling electric valve EV2 is opened only during the heating operation to bypass the refrigerant. FIG.
As shown in FIG. 1, a refrigerating apparatus having a configuration using an electromagnetic valve 61 and a capillary 62 as a subcooling depressurizing means instead of the supercooling electric valve of FIG. 1 may be used. As shown in FIG. 8, an injection circuit for injecting the gas refrigerant from the subcooling heat exchanger 11 into the intermediate pressure portion of the compressor 71 via the bypass pipe 35 may be provided. 6 to 8, the same components as those of the refrigeration apparatus of FIG. 1 are denoted by the same reference numerals.

[0048]

As is apparent from the above description, the refrigeration apparatus according to the first aspect of the present invention comprises a refrigerant circuit in which a compressor, a condenser, a main decompression means and an evaporator are connected in a ring, a condenser and a main decompression means. And a bypass pipe that bypasses the gas side and the liquid side of the refrigerant circuit via the subcooling heat exchanger, and an upstream side of the subcooling heat exchanger of the bypass pipe. Refrigeration apparatus provided with a supercooling depressurizing means disposed in the compressor, wherein R32 refrigerant or a mixed refrigerant containing at least 70% by weight or more of R32 is used, and the discharge temperature of the compressor detected by the discharge temperature sensor is used. The amount of refrigerant flowing through the bypass pipe is controlled by making a determination by the discharge temperature determining section and controlling the supercooling decompression means by the control section based on the determination result of the discharge temperature determining section.

Therefore, according to the refrigeration apparatus of the first aspect of the present invention, the control unit controls the supercooling pressure reducing means based on the determination result of the discharge temperature determination unit, and the bypass is controlled according to the level of the discharge temperature. By controlling the amount of refrigerant flowing through the pipe to be large or small, when the discharge temperature is high, it is possible to increase the bypass refrigerant amount and lower the discharge temperature,
Due to the physical properties of the refrigerant, the discharge temperature is higher than that of the HCFC refrigerant.
Even if 32 refrigerant (or a mixed refrigerant containing at least 70% by weight of R32) is used, the optimum discharge temperature can be achieved without lowering the efficiency, and the COP and reliability can be improved.

According to the refrigeration apparatus of the second aspect of the present invention, when the discharge temperature determination section determines that the discharge temperature has exceeded the upper limit set value, the control section increases the amount of refrigerant flowing through the bypass pipe. On the other hand, when the discharge temperature determination unit determines that the discharge temperature is less than the lower limit set value, the control unit controls the supercooling pressure reducing unit to reduce the amount of refrigerant flowing through the bypass pipe. By controlling the pressure reducing means, more optimal discharge temperature control can be performed without lowering the efficiency.

According to the refrigeration apparatus of the third aspect of the present invention, the condensation temperature of the condenser detected by the condensation temperature sensor, the evaporation temperature of the evaporator detected by the evaporation temperature sensor, and the supercooling decompression means Based on the opening degree of the electric motor valve for supercooling, the target discharge temperature calculation unit calculates a target discharge temperature suitable for an operating condition (cooling / heating and operating frequency of the compressor, etc.), and calculates the calculated target discharge temperature. Based on the temperature, the main controller controls the main pressure reducing means to control the amount of refrigerant flowing in the refrigerant circuit so that the discharge temperature of the compressor becomes the target discharge temperature, thereby flowing to the bypass pipe. The optimum discharge temperature can be controlled in accordance with the amount of refrigerant, that is, the degree of supercooling.

Further, according to the refrigerating apparatus of the present invention, the evaporator outlet temperature of the evaporator is detected by the evaporator outlet temperature sensor, and the target discharge temperature calculated by the target discharge temperature calculating section and the evaporation temperature are calculated. The controller controls the main pressure reducing means and the supercooling pressure reducing means based on the outlet temperature of the compressor, and uses the outlet temperature of the evaporator for controlling the discharge temperature of the compressor. The controllability of the degree can be improved.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a heat pump type air conditioner as a refrigeration apparatus according to a first embodiment of the present invention.

FIG. 2 is a flowchart illustrating an operation of the control device of the air conditioner.

FIG. 3 is a Mollier diagram of the air conditioner.

FIG. 4 is a circuit diagram of an air conditioner according to a second embodiment of the present invention.

FIG. 5 is a flowchart illustrating an operation of the control device for the air conditioner.

FIG. 6 is a circuit diagram of an air conditioner having no bridge circuit.

FIG. 7 is a circuit diagram of an air conditioner using a solenoid valve and a capillary as a subcooling decompression means.

FIG. 8 is a circuit diagram of an air conditioner using an injection circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Compressor, 2 ... Four way switching valve, 3 ... Outdoor heat exchanger, 4 ... Bridge circuit, 4A-4D ... Check valve, 5 ... Indoor heat exchanger, 6 ... Accumulator, EV1 ... Main motorized valve, EV2 ... Electric valve for supercooling, 10 ... Control device, 10a ... Control unit, 10b ... Discharge temperature judgment unit, 10c ... Target discharge temperature calculation unit, 10d ... Target evaporator outlet temperature calculation unit, 21 ... Discharge temperature sensor, 22- 25: temperature sensor, 33, 34: bypass piping, 61: solenoid valve, 62: capillary.

Claims (4)

[Claims] 1. Compressor (1), condenser (3, 5), main pressure reducing means
(EV1) and a refrigerant circuit in which the evaporators (5, 3) are connected in a ring shape, the condenser (3, 5) and the main pressure reducing means (EV1).
And a bypass pipe (33, 34) for bypassing the gas side and the liquid side of the refrigerant circuit via the supercooling heat exchanger (11). A refrigerating apparatus comprising: a subcooling depressurizing means disposed upstream of the subcooling heat exchanger (11) in the bypass pipe (33, 34); A discharge temperature sensor for detecting the discharge temperature of the compressor (1) while using a mixed refrigerant containing at least
(21), a discharge temperature determination unit (10b) for determining a discharge temperature detected by the discharge temperature sensor (21), and the supercooling pressure reducing unit based on a determination result of the discharge temperature determination unit (10b). And a controller (10a) for controlling the amount of the refrigerant flowing through the bypass pipe by controlling the refrigerant flow. 2. The refrigeration system according to claim 1, wherein the control unit (10a) determines that the discharge temperature has exceeded the upper limit set value by the discharge temperature determination unit (10b). , 34) while controlling the supercooling decompression means so that the amount of refrigerant flowing through the bypass pipe increases when the discharge temperature determination unit (10b) determines that the discharge temperature is lower than the lower limit set value. A refrigeration system characterized by controlling the supercooling pressure reducing means so that the amount of flowing refrigerant is reduced. 3. The refrigerating apparatus according to claim 1, wherein the subcooling pressure reducing means is a subcooling electric valve (EV2), and detects a condensing temperature of the condenser (3, 5). Condensing temperature sensors (22, 23), evaporating temperature sensors (23, 22) for detecting evaporating temperatures of the evaporators (5, 3), and condensing temperatures detected by the condensing temperature sensors (22, 23). A target discharge temperature calculating section for calculating a target discharge temperature based on the evaporating temperature detected by the evaporating temperature sensors (23, 22) and the opening degree of the supercooling electric valve (EV2).
(10c), wherein the control unit (10a) controls the main pressure reducing means (EV1) so that the discharge temperature of the compressor (1) becomes the target discharge temperature.
A refrigeration apparatus characterized by controlling the temperature. 4. The refrigerating apparatus according to claim 3, further comprising an evaporator outlet temperature sensor (24, 25) for detecting an evaporator outlet temperature of the evaporator (3, 5), wherein the controller (10). Is the target discharge temperature calculator (10c)
The main pressure reducing means (EV1) and the supercooling electric valve (EV2) are controlled based on the target discharge temperature calculated by the above and the evaporator outlet temperature detected by the evaporator outlet temperature sensor (24, 25). A refrigeration device characterized by performing: