JP6865111B2 - Heat pump device - Google Patents

Description

The present invention relates to a configuration of a heat pump device capable of cooling and heating the supplied circulating fluid.

Conventionally, a heat pump device that supplies cold or hot heat to an external device by adjusting the temperature of the circulating fluid using a heat exchanger and circulating the circulating fluid with an external device using piping has been known. ing.

Patent Document 1 discloses a refrigeration cycle of an air conditioner capable of cooling and heating, although it does not cool and heat the circulating fluid. This air conditioner has a receiver for storing excess refrigerant between the indoor heat exchanger and the outdoor heat exchanger. Further, the air conditioner of Patent Document 1 is provided with a check valve bridge circuit, which allows the refrigerant from the outdoor heat exchanger to flow into the receiver during cooling operation and indoors during heating operation. Refrigerant from the heat exchanger flows into the receiver.

In the air conditioner of Patent Document 1, a first throttle device is provided between the receiver and the check valve bridge circuit. In this configuration, during the cooling operation, the high-temperature and high-pressure gas refrigerant discharged from the compressor becomes a liquid refrigerant by heat exchange in the outdoor heat exchanger, but the first before the liquid refrigerant flows into the receiver. The pressure is reduced to medium pressure by the squeezing device. On the other hand, during the heating operation, the high-temperature and high-pressure gas refrigerant discharged from the compressor becomes a liquid refrigerant by heat exchange in the indoor heat exchanger, but the first throttle is used before the liquid refrigerant flows into the receiver. The device reduces the pressure to medium pressure.

JP-A-2002-277079

By the way, the heat pump device that cools and heats the circulating fluid is not only used when operating in an environment suitable for operation, but also when, for example, the flow rate of the refrigerant is small, when it is desired to perform cooling in a situation where the outside temperature is low, or circulation Even when it is desired to perform heating in a situation where the liquid temperature is low, it is desired that the pressure (high pressure) when the refrigerant is compressed by the compressor is sufficiently high.

However, in Patent Document 1, although the first throttle device is provided between the check valve bridge circuit and the receiver in the air conditioner, how to control the opening degree of this throttle according to the situation. There is no particular mention of this. Therefore, there is room for improvement from the viewpoint of improving the performance of the heat pump device.

The present invention has been made in view of the above circumstances, and an object of the present invention is to avoid a case where a high pressure pressure is difficult to increase.

Means and effects to solve problems

The problem to be solved by the present invention is as described above, and next, the means for solving this problem and its effect will be described.

According to the viewpoint of the present invention, the following configurations in a heat pump device capable of cooling and heating the supplied circulating fluid are provided. That is, this heat pump device includes a first heat exchanger, a second heat exchanger, a receiver, a bridge circuit, a throttle unit, and a control unit. The first heat exchanger exchanges heat between the outside air and the refrigerant. The second heat exchanger exchanges heat between the circulating fluid and the refrigerant. The receiver is connected to the first heat exchanger and the second heat exchanger. The bridge circuit supplies the refrigerant from the first heat exchanger to the receiver when the circulating fluid is cooled, and supplies the refrigerant from the second heat exchanger to the receiver when the circulating fluid is heated. .. The throttle portion is arranged in a refrigerant path connecting the receiver and the bridge circuit. Wherein, when the prior SL is lower than the second temperature temperature of the circulating liquid is below the lower limit temperature of the temperature setting range of the circulating fluid during the heating operation at the time of the heating of the circulating fluid, the refrigerant at the narrowed portion The ease of flow is changed according to the pressure of the refrigerant circuit.

As a result, it is possible to avoid a situation in which it is difficult to obtain a high pressure of the refrigerant in both the cooling operation and the heating operation of the circulating fluid by controlling the throttle portion, so that a good cycle can be realized. Further, when the temperature of the circulating fluid is low when the circulating fluid is heated, the throttle portion can be appropriately controlled according to the pressure of the refrigerant circuit.

In the heat pump device, when the temperature of the outside air is lower than a predetermined first temperature when the circulating fluid is cooled, the control unit determines the ease of flow of the refrigerant in the throttle unit of the refrigerant circuit. The temperature is changed according to the pressure, and the first temperature is preferably 21 ° C. or lower.

As a result, it is possible to appropriately control the throttle portion according to the pressure of the refrigerant circuit in a situation where the outside air temperature is low when the circulating fluid is cooled.

In the heat pump device, when the high pressure of the refrigerant is out of a predetermined determination range, it is preferable to change the ease of flow of the refrigerant in the throttle portion according to the pressure of the refrigerant circuit.

As a result, the pressure of the refrigerant circuit can be appropriately controlled when the high-pressure pressure is difficult to increase or when the pressure is excessively high due to overload.

The heat pump device preferably has the following configuration. That is, the control unit selectively performs the first control and the second control. In the first control, the control unit changes the ease of flow of the refrigerant in the throttle unit according to the pressure of the refrigerant circuit. In the second control, the control unit changes the strength of supercooling performed in the throttle unit according to the difference between the target supercooling degree and the current supercooling degree.

As a result, it is possible to cope with both a situation in which a high pressure pressure is desired to be obtained satisfactorily and a situation in which supercooling is desired to be performed with an appropriate strength for the refrigerant by using a common throttle portion.

The heat pump device preferably has the following configuration. That is, the front Symbol controller, the second controller, at the time of heating before Symbol circulating fluid, the temperature of the circulating fluid is at the second temperature or higher, and high pressure of the refrigerant is predetermined This is performed when it is within the second determination range.

As a result, appropriate control can be performed according to the situation.

The heat pump device preferably has the following configuration. That is, the control unit obtains the target supercooling degree based on the circulating flow rate of the refrigerant in the refrigerant circuit. The control unit determines the current degree of supercooling, the temperature of the refrigerant detected in the refrigerant path from the first heat exchanger or the second heat exchanger to the throttle portion, and the high pressure of the refrigerant. Use to find.

As a result, the target supercooling degree can be substantially set according to the load, and the supercooling degree of the refrigerant is not detected at the outlet of the first heat exchanger or the second heat exchanger. Can be obtained. As a result, the degree of supercooling of the refrigerant can be appropriately controlled with a simple configuration, so that a heat pump device having excellent performance can be realized.

In the heat pump device, the throttle portion preferably includes a plurality of valves connected in parallel with each other.

As a result, the ease of flow of the refrigerant in the throttle portion can be flexibly changed according to the situation.

In the heat pump device, the throttle portion preferably includes an expansion valve whose opening degree can be adjusted.

Thereby, the strength of supercooling given to the refrigerant can be adjusted by the throttle portion.

The refrigerant circuit diagram of the heat pump device which concerns on one Embodiment of this invention. A functional block diagram showing a configuration for controlling an aperture circuit. The flowchart which shows the processing of the control part at the time of cooling a circulating fluid. The flowchart which shows the processing of the control part at the time of heating a circulating liquid.

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a refrigerant circuit diagram of the heat pump device 1 according to the present embodiment.

The heat pump device 1 shown in FIG. 1 is configured as a heat pump chiller, and comprises an outside air-refrigerant heat exchanger (first heat exchanger) 31 and a circulating liquid-refrigerant heat exchanger (second heat exchanger) 32. Be prepared. The heat pump device 1 is supplied to the circulating liquid-refrigerant heat exchanger 32 by exchanging heat between the outside air-refrigerant heat exchanger 31 and the circulating liquid-refrigerant heat exchanger 32 via the refrigerant. The circulating fluid can be cooled or heated.

In the present specification, the refrigerant means a medium that carries heat, and is a concept including a case where it is used for cooling the circulating liquid introduced into the heat pump device 1 and a case where it is used for heating the circulating liquid. Is. When the circulating fluid is cooled in the heat pump device 1, cold heat is supplied to the external device 90, and when the circulating fluid is heated in the heat pump device 1, hot heat is supplied to the external device 90. As the circulating fluid, for example, water can be used, but the circulating fluid is not limited to this.

The heat pump device 1 (circulating liquid-refrigerant heat exchanger 32) and the external device 90 are connected by a pair of circulating liquid pipes 91. The circulating fluid is configured to circulate in the circulating fluid pipe 91. The circulating fluid cooled or heated by the heat pump device 1 is sent to the external device 90 to supply cold or hot heat, and then is returned to the heat pump device 1.

The heat pump device 1 includes a compressor 11. The compressor 11 is driven by an engine 12 as a drive source. In the present embodiment, the engine 12 is configured as a gas engine using gas as fuel, but fuel other than gas (heavy oil, kerosene, etc.) may be used. Further, the compressor 11 may be driven by a drive source other than the engine 12 (for example, an electric motor).

The accumulator 13 separates the refrigerant into a liquid and a gas, and supplies the refrigerant in a gaseous state to the compressor 11. This prevents liquid compression by the compressor 11. When the compressor 11 is driven, the refrigerant in a gas state is sucked from the accumulator 13. The refrigerant is adiabatically compressed by the compressor 11 to become a superheated state, and becomes a high-temperature and high-pressure gaseous. The compressor 11 discharges this gaseous refrigerant to the oil separator 15.

The oil separator 15 separates the lubricating oil for the compressor 11 from the gaseous refrigerant. The separated lubricating oil is returned to the compressor 11 by the oil return circuit (not shown). The gaseous refrigerant from which the lubricating oil is separated by the oil separator 15 is supplied to the four-way valve 17.

The four-way valve 17 is configured as a switching valve having four ports. The four-way valve 17 can be switched between a cooling operation for cooling the circulating fluid and a heating operation for heating the circulating fluid so that the supply destination of the refrigerant is different.

First, the flow of the refrigerant during the cooling operation will be described.

When cooling the circulating fluid, the four-way valve 17 supplies gaseous refrigerant to the two outside air-refrigerant heat exchangers 31 by connecting the ports as shown by the solid line in FIG. As the outside air-refrigerant heat exchanger 31, for example, a plate fin tube type heat exchanger can be used. In the outside air-refrigerant heat exchanger 31, heat exchange is performed between the outside air and the high-temperature refrigerant, which causes the refrigerant to condense and change into a high-pressure liquid. That is, at this time, the outside air-refrigerant heat exchanger 31 functions as a condenser. The refrigerant that has been heat-exchanged by the outside air-refrigerant heat exchanger 31 and becomes liquid passes through a known bridge circuit 18 composed of a plurality of check valves, and then passes through a throttle circuit (throttle portion) 19. It is supplied to the receiver 23. The throttle circuit 19 can apply supercooling to the refrigerant at the outlet of the outside air-refrigerant heat exchanger 31 by the throttle effect, and the details thereof will be described later.

The high-pressure liquid refrigerant emitted from the receiver 23 is supercooled by passing through the supercooling heat exchanger 24, and then is depressurized by passing through the expansion valve 26, and is in the form of a low-temperature, low-pressure mist. Gas-liquid mixed state). After that, the refrigerant is supplied to the circulating liquid-refrigerant heat exchanger 32 via the bridge circuit 18. As the circulating liquid-refrigerant heat exchanger 32, for example, a plate type heat exchanger can be used. In the circulating liquid-refrigerant heat exchanger 32, heat exchange is performed between the circulating liquid and the low-temperature refrigerant, whereby the circulating liquid can be cooled. Along with this heat exchange, the mist-like portion of the refrigerant evaporates and changes to a low-temperature, low-pressure gaseous state. That is, at this time, the circulating liquid-refrigerant heat exchanger 32 functions as an evaporator. After that, the refrigerant is returned to the accumulator 13 via the four-way valve 17.

Next, the flow of the refrigerant during the heating operation will be described.

When heating the circulating fluid, the four-way valve 17 supplies a gaseous refrigerant to the circulating fluid-refrigerant heat exchanger 32 by connecting the ports as shown by the broken line in FIG. In the circulating liquid-refrigerant heat exchanger 32, heat exchange is performed between the circulating liquid and the high-temperature refrigerant, whereby the circulating liquid can be heated. As a result, the refrigerant condenses and changes to a low-temperature, high-pressure liquid. That is, at this time, the circulating liquid-refrigerant heat exchanger 32 functions as a condenser. The refrigerant that has been liquefied by heat exchange in the circulating liquid-refrigerant heat exchanger 32 is supplied to the receiver 23 via the bridge circuit 18 and the throttle circuit 19.

The low-temperature, high-pressure liquid refrigerant emitted from the receiver 23 is decompressed by passing through the expansion valve 26 after being supercooled by passing through the supercooling heat exchanger 24, and is a low-temperature, low-pressure mist. It becomes a state (gas-liquid mixed state). After that, the refrigerant is supplied to the outside air-refrigerant heat exchanger 31 via the bridge circuit 18. In the outside air-refrigerant heat exchanger 31, heat exchange is performed between the outside air and the low-temperature refrigerant. Along with this heat exchange, the mist-like portion of the refrigerant evaporates and changes to a low-temperature, low-pressure gaseous state. That is, at this time, the outside air-refrigerant heat exchanger 31 functions as an evaporator. After that, the refrigerant is returned to the accumulator 13 via the four-way valve 17.

Next, the throttle circuit 19 capable of applying supercooling to the refrigerant and adjusting the degree of supercooling will be described in detail.

The throttle circuit 19 is arranged in a refrigerant path connecting the bridge circuit 18 and the receiver 23. The throttle circuit 19 exchanges heat with the upstream heat exchanger (outside air-refrigerant heat exchanger 31 or circulating liquid-refrigerant heat exchange) by, for example, performing throttle expansion with respect to the low-temperature and high-pressure liquid refrigerant flowing in from the bridge circuit 18. Overcooling can be applied to the refrigerant at the outlet of the vessel 32).

The diaphragm circuit 19 includes a first road 41, a second road 42, a third road 43, and a fourth road 44, which are connected in parallel to each other.

A first on-off valve 51 is arranged on the first road 41. The first on-off valve 51 is configured as a solenoid valve, and can switch between a state in which the flow of the refrigerant in the first path 41 is allowed and a state in which the flow of the refrigerant is blocked based on an electric signal.

A second on-off valve 52 is arranged on the second road 42. The second on-off valve 52 is configured as an electromagnetic valve like the first on-off valve 51, and can open and close the second road 42 based on an electric signal.

An expansion valve 53 is arranged on the third road 43. The expansion valve 53 can reduce the pressure of the refrigerant flowing through the third path 43. Further, the expansion valve 53 is configured so that its opening degree can be adjusted in order to change the degree of depressurization of the refrigerant.

The fourth road 44 is configured as a thin pipe such as a capillary pipe, and is configured as a fixed throttle so that the flow rate of the refrigerant can be limited.

With the above configuration, the ease of flow of the refrigerant in the throttle circuit 19 can be changed in a plurality of steps by the combination of opening and closing the first on-off valve 51 and the second on-off valve 52. Further, by changing the opening degree of the expansion valve 53, the ratio of the refrigerant that is depressurized and flows into the receiver 23 can be changed.

Next, the supercooling heat exchanger 24 that applies supercooling to the refrigerant exiting the receiver 23 will be described.

The supercooling heat exchanger 24 is arranged between the receiver 23 and the expansion valve 26, and can cool the liquid refrigerant flowing from the receiver 23 to the expansion valve 26. Specifically, a part of the liquid refrigerant leaving the supercooling heat exchanger 24 is decompressed by the expansion valve 27 to be atomized and flows to the supercooling heat exchanger 24 from the receiver 23. Heat exchange takes place with the flowing liquid refrigerant. As a result, a lower temperature liquid refrigerant can be supplied to the expansion valve 26.

Next, the electrical configuration included in the heat pump device 1 for controlling the throttle circuit 19 will be described. FIG. 2 is a functional block diagram showing a configuration for controlling the diaphragm circuit 19.

As shown in FIG. 2, the heat pump device 1 includes a control unit 80 for controlling the throttle circuit 19.

Specifically, the control unit 80 is configured as a known computer and includes a CPU, a ROM, a RAM, and the like. Then, the ROM stores a program for adjusting the diaphragm circuit 19 as appropriate. By the cooperation of the hardware and software, this computer can be operated as a control unit 80 for controlling the diaphragm circuit 19.

Next, various sensors for acquiring information for control performed by the control unit 80 will be described.

The heat pump device 1 includes a high pressure sensor 71, a circulating fluid temperature sensor 73, a first temperature sensor 76, a second temperature sensor 77, and an outside air temperature sensor 74. All of these sensors are electrically connected to the control unit 80.

As shown in FIG. 1, the high pressure sensor 71 is arranged in the refrigerant path between the compressor 11 and the oil separator 15, and can detect the pressure of the refrigerant. The detection result by the high pressure sensor 71 is used to estimate the condensation temperature of the refrigerant.

The first temperature sensor 76 is arranged in the refrigerant path from the outside air-refrigerant heat exchanger 31 to the bridge circuit 18, and can detect the temperature of the refrigerant. The temperature detected by the first temperature sensor 76 is used to calculate the degree of supercooling during the cooling operation.

The second temperature sensor 77 also has the same configuration as the first temperature sensor 76, and is arranged in the refrigerant path from the circulating liquid-refrigerant heat exchanger 32 to the bridge circuit 18. The temperature detected by the second temperature sensor 77 is used to calculate the degree of supercooling during the heating operation.

The circulating fluid temperature sensor 73 can detect the temperature of the circulating fluid supplied to the heat pump device 1. The circulating fluid temperature sensor 73 is arranged in the vicinity of the inlet to which the circulating fluid is supplied in the circulating fluid-refrigerant heat exchanger 32.

The outside air temperature sensor 74 can detect the temperature of the outside air. The outside air temperature sensor 74 can be arranged, for example, at a ventilation port of an engine room (not shown) formed in the heat pump device 1 for arranging the engine 12, but is not limited thereto.

The control unit 80 is electrically connected to each of the first on-off valve 51, the second on-off valve 52, and the expansion valve 53. The control unit 80 outputs an electric signal to the first on-off valve 51, the second on-off valve 52, and the expansion valve 53 to control the first on-off valve 51, the second on-off valve 52, and the expansion valve 53 based on the information input from the sensor.

There are various situations in which the heat pump device 1 having this configuration is used. For example, when the flow rate of the refrigerant is small, when it is desired to cool the circulating fluid in a situation where the outside air temperature is low, or when the circulating fluid temperature is low, the circulation fluid is circulated. It is also assumed that you want to heat the liquid. Generally, in these cases, the refrigerant pressure in the circuit becomes low, so that it tends to be difficult to obtain a sufficient high pressure.

In this respect, the heat pump device 1 of the present embodiment is configured to realize a good cycle by appropriately controlling the flowability of the throttle circuit 19 by the control unit 80 as follows.

First, the flow during the cooling operation will be described with reference to FIG. FIG. 3 is a flowchart showing the processing of the control unit 80 when cooling the circulating fluid.

When the process of FIG. 3 is started, the control unit 80 determines whether or not the temperature of the outside air is lower than a predetermined threshold value (first temperature) based on the detection result of the outside air temperature sensor 74 (step S101). The first temperature can be appropriately determined, but is preferably 20 ° C. or lower, more preferably 15 ° C. or lower. From another point of view, regarding the cooling test of the water chilling unit specified in B8613 of Japanese Industrial Standards, the dry-bulb temperature defined as the freezing condition when the heat source is an air-cooled type is 21 ° C., so that the first temperature is It is desirable that the temperature is 21 ° C. or lower. In this embodiment, the first temperature is set to 10 ° C.

When the outside air temperature is lower than the above-mentioned first temperature, it is considered that it is difficult to realize a sufficiently high high pressure because the pressure in the refrigerant circuit decreases. Therefore, in this case, the control unit 80 opens / closes at least one of the first on-off valve 51, the second on-off valve 52, and the expansion valve 53 so that the pressure of the refrigerant on the upstream side of the throttle circuit 19 becomes appropriate. Is controlled (step S102). A specific example of the control in step S102 will be described later. After that, the process returns to step S101.

When the determination in step S101 is that the outside air temperature is equal to or higher than the first temperature, the control unit 80 determines that the pressure of the refrigerant in the heat pump device 1 is within a predetermined range (first determination) based on the detection result of the high pressure sensor 71. It is determined whether or not it is within the range) (step S103). This first determination range is determined based on an appropriate pressure range defined in the specifications of the compressor 11, for example, a pressure range for protecting the compressor. In other words, the first determination range in step S103 can be set in various ways depending on the performance of the compressor 11 and the like.

If the pressure of the refrigerant is not within the above-mentioned first determination range in the determination of step S103, the control unit 80 determines that the refrigerant on the upstream side of the throttle circuit 19 is the same as when the outside air temperature is lower than the first temperature. At least one of the first on-off valve 51, the second on-off valve 52, and the expansion valve 53 is controlled so that the pressure of the above is appropriate (step S102). After that, the process returns to step S101.

Various processes can be considered as the process of step S102, and for example, it can be controlled as follows.

In step S101, when the value of the outside air temperature obtained by the outside air temperature sensor 74 is lower than the threshold value, or in step S103, when the value of the high pressure pressure obtained by the high pressure sensor 71 deviates from the first determination range to the lower side. In step S102, the control unit 80 closes the first on-off valve 51 and closes the second on-off valve 52. Next, when the pressure detected by the high pressure sensor 71 is out of the predetermined range (first pressure control range), the control unit 80 reduces the opening degree of the expansion valve 53 from the present and increases the pressure. If it deviates from the current value, the control for increasing the opening degree of the expansion valve 53 from the current level is repeated at a constant cycle. The first pressure control range used in this control is different from the first determination range used in the determination in step S103, but it is needless to say that the first determination range is determined in consideration of the first determination range.

As a result, for example, when the high-pressure pressure is unfavorably low for maintaining the performance of the compressor 11, the first on-off valve 51, the second on-off valve 52, and the expansion valve 53 are closed to promote an increase in the high-pressure pressure. Therefore, the compressor 11 can be well protected. Further, even when the outside air temperature is low, the high-pressure pressure can be easily increased by controlling the throttle circuit 19 to make it difficult for the refrigerant to flow. On the other hand, since the opening degree of the expansion valve 53 is controlled to increase as the high pressure pressure rises, it is possible to prevent the control of the high pressure pressure from overshooting and rising too much.

On the other hand, in step S103, when the value of the high pressure pressure obtained from the high pressure sensor 71 deviates from the first determination range to the higher side, in step S102, the control unit 80 presses the first on-off valve 51 and the second on-off valve 52. Control to open. However, only one of the first on-off valve 51 and the second on-off valve 52 may be opened. As a result, since the throttle circuit 19 is substantially not throttled, it is possible to avoid an excessive increase in the high pressure pressure, for example, when an overload occurs for some reason.

As a result, an appropriate high-pressure pressure can be obtained on the upstream side of the throttle circuit 19, and a good cycle can be realized in the heat pump device 1.

In the determination of step S103, when the pressure of the refrigerant is within the above-mentioned first determination range, the control unit 80 estimates the circulation amount of the refrigerant and makes the optimum supercooling degree corresponding to the estimation. , At least one of the first on-off valve 51, the second on-off valve 52, and the expansion valve 53 is controlled (step S104).

Hereinafter, this supercooling adjustment control will be described in detail. First, the control unit 80 obtains a circulating flow rate in which the refrigerant circulates in the heat pump device 1. The circulating flow rate of the refrigerant can be obtained based on the number of revolutions of the compressor 11 (for example, based on the number of revolutions of the engine) and the number of revolutions and the amount of refrigerant discharged from the compressor 11. In general, the circulating flow rate of the refrigerant decreases during low-load operation, while the circulating flow rate increases during high-load operation. Therefore, it can be said that the circulating flow rate of the refrigerant substantially indicates the load of the heat pump device 1.

Then, the control unit 80 calculates the target supercooling degree in the case of the circulating flow rate based on the circulating flow rate of the obtained refrigerant. The calculation of the target supercooling degree is performed by creating a function representing the relationship between the circulating flow rate of the refrigerant and the target supercooling degree intended by the designer in advance, storing it in the control unit 80, and using this function. be able to. However, the above relationship is not limited to the function, and can be expressed by, for example, a map.

Next, the control unit 80 acquires the saturated liquid temperature at the outlet of the outside air-refrigerant heat exchanger 31.

Originally, the pressure of the refrigerant is required to obtain the saturated liquid temperature. However, in the present embodiment, as shown in FIG. 1, the pressure sensor is not provided at the outlet of the outside air-refrigerant heat exchanger 31.

Therefore, the control unit 80 obtains a result obtained by an experiment or the like in advance regarding the relationship between the circulating flow rate of the refrigerant and the pressure loss generated in the outside air-refrigerant heat exchanger 31 or the like in the circulating flow rate, as a function or a map or the like. I remember it in the form of. The control unit 80 obtains the pressure loss by substituting the circulating flow rate obtained by the calculation into the function. Then, the control unit 80 can estimate the pressure at the outlet of the outside air-refrigerant heat exchanger 31 by using the obtained pressure loss and the pressure detected by the high pressure sensor 71.

Then, the control unit 80 is configured to obtain the saturated liquid temperature based on the estimated value of this pressure.

The degree of supercooling is expressed by the difference between the saturated liquid temperature and the actual refrigerant temperature. Therefore, the control unit 80 obtains the degree of supercooling by subtracting the detected value of the first temperature sensor 76 from the saturated liquid temperature obtained by the above calculation.

Based on the above results, the first on-off valve 51, the second on-off valve 52, and the expansion valve 53 are controlled. Specifically, the control unit 80 opens the first on-off valve 51 and closes the second on-off valve 52, and then obtains a supercooling degree (current supercooling degree) and a target supercooling degree. Compare with degree. When the current supercooling degree is smaller than the target supercooling degree, the control unit 80 controls so as to reduce the opening degree of the expansion valve 53. As a result, the supercooling applied to the refrigerant by the expansion valve 53 can be strengthened. On the other hand, when the current supercooling degree is larger than the target supercooling degree, the control unit 80 controls so as to increase the opening degree of the expansion valve 53. As a result, the supercooling applied to the refrigerant by the expansion valve 53 can be weakened.

The control unit 80 recalculates the current supercooling degree and the target supercooling degree at regular intervals, and controls the opening degree of the expansion valve 53 based on the new result. By repeating this process, an appropriate degree of supercooling according to the circulating flow rate of the refrigerant can be stably realized, and a high-performance heat pump device 1 can be obtained.

Next, the flow during the heating operation in this embodiment will be described with reference to FIG.

When the process of FIG. 4 is started, the control unit 80 determines whether or not the temperature of the circulating fluid obtained from the circulating fluid temperature sensor 73 is lower than a predetermined threshold value (second temperature) (step S201). ). The second temperature can be appropriately determined, but is preferably 30 ° C. or lower, more preferably 25 ° C. or lower. From another point of view, it is desirable that the second temperature is equal to or lower than the lower limit of the temperature setting range (in this embodiment, the range from 35 ° C. to 55 ° C.) when the chiller is heated and operated. In this embodiment, the second temperature is set to 20 ° C.

If the temperature of the circulating fluid is lower than the above-mentioned second temperature according to the determination in step S201, the first on-off valve 51 and the second on-off valve so that the pressure of the refrigerant on the upstream side of the throttle circuit 19 becomes appropriate. At least one of 52 and the expansion valve 53 is controlled (step S202). A specific example of the control in step S202 will be described later. After that, the process returns to step S201.

If the temperature of the circulating fluid is equal to or higher than the second temperature in the determination of step S201, the control unit 80 determines that the pressure of the refrigerant in the heat pump device 1 is within a predetermined range (first) based on the detection result of the high pressure sensor 71. 2 It is determined whether or not it is within the determination range) (step S203). The determination in step S203 is the same as in step S103 in the flow during the cooling operation described above. If the judgment in step S203 indicates that the pressure of the refrigerant is not within the second determination range, the control unit 80 performs the process in step S202. After that, the process returns to step S201.

Various processes can be considered as the process of step S202, and for example, it can be controlled as follows.

That is, when the value of the high pressure obtained by the high pressure sensor 71 is lower than the predetermined pressure P1, the control unit 80 closes the first on-off valve 51, closes the second on-off valve 52, and fully closes the expansion valve 53. Closed.

When the value of the high pressure pressure obtained by the high pressure sensor 71 exceeds the above pressure P1, the control unit 80 closes the first on-off valve 51 and opens the second on-off valve 52. Then, when the pressure detected by the high pressure sensor 71 is out of the predetermined range (second pressure control range), the control unit 80 reduces the opening degree of the expansion valve 53 from the present and moves it to the higher side. If the pressure is off, the control for increasing the opening degree of the expansion valve 53 from the current level is repeated at regular intervals. The second pressure control range used in this control is different from the second determination range used in the determination in step S203, but it is needless to say that the second pressure control range is determined in consideration of the second determination range.

If the pressure of the refrigerant is within the above-mentioned second determination range in the determination of step S203, the control unit 80 estimates the circulation amount of the refrigerant and makes the optimum supercooling degree corresponding to the estimation. In addition, at least one of the first on-off valve 51, the second on-off valve 52, and the expansion valve 53 is controlled (step S204).

Since the process of step S204 is almost the same as the process of step S104 in the flow during the cooling operation described above, detailed description thereof will be omitted. However, in the process of step S204, the opening degree of the expansion valve 53 is controlled with both the first on-off valve 51 and the second on-off valve 52 open. Further, when the saturated liquid temperature is obtained in step S204, the pressure loss generated in the circulating liquid-refrigerant heat exchanger 32 instead of the outside air-refrigerant heat exchanger 31 is used as the pressure loss. The degree of supercooling is obtained by subtracting the detected value of the second temperature sensor 77 from the saturated liquid temperature.

As a result, even when the temperature of the circulating fluid is low during the heating operation, an appropriate high-pressure pressure can be obtained on the upstream side of the throttle circuit 19, and a good cycle can be realized in the heat pump device 1. Further, since an appropriate degree of supercooling according to the circulating flow rate of the refrigerant can be realized, the performance of the heat pump device 1 can be improved.

As described above, the heat pump device 1 of the present embodiment is configured to be able to cool and heat the supplied circulating liquid. The heat pump device 1 includes an outside air-refrigerant heat exchanger 31, a circulating fluid-refrigerant heat exchanger 32, a receiver 23, a bridge circuit 18, a throttle circuit 19, and a control unit 80. The outside air-refrigerant heat exchanger 31 exchanges heat between the outside air and the refrigerant. The circulating liquid-refrigerant heat exchanger 32 exchanges heat between the circulating liquid and the refrigerant. The receiver 23 is connected to the outside air-refrigerant heat exchanger 31 and the circulating liquid-refrigerant heat exchanger 32. The bridge circuit 18 supplies the refrigerant from the outside air-refrigerant heat exchanger 31 to the receiver 23 when the circulating fluid is cooled, and supplies the refrigerant from the circulating fluid-refrigerant heat exchanger 32 to the receiver 23 when the circulating fluid is heated. The throttle circuit 19 is arranged in the refrigerant path connecting the receiver 23 and the bridge circuit 18. In the control unit 80, when the temperature of the outside air is lower than a predetermined threshold value (first temperature) when the circulating fluid is cooled, or when the circulating fluid is heated, the temperature of the circulating fluid is a predetermined threshold value (first temperature). When the temperature is lower than 2), the ease of flow of the refrigerant in the throttle circuit 19 is changed according to the pressure of the refrigerant circuit (step S101, step S102, step S201, step S202).

As a result, a situation in which it is difficult to obtain a high-pressure pressure of the refrigerant can be avoided by controlling the throttle circuit 19 in both the cooling operation and the heating operation of the circulating fluid, so that a good cycle can be realized. ..

Further, in the heat pump device 1 of the present embodiment, the first temperature is a temperature of 21 ° C. or lower, specifically 10 ° C.

As a result, the throttle circuit 19 can be appropriately controlled according to the pressure of the refrigerant circuit in a situation where the outside air temperature is low when the circulating fluid is cooled.

Further, in the heat pump device 1 of the present embodiment, the second temperature is a temperature below the lower limit (35 ° C. or less) of the temperature setting range of the circulating fluid during the heating operation, specifically, 15 ° C.

As a result, the throttle circuit 19 can be appropriately controlled according to the pressure of the refrigerant circuit in a situation where the temperature of the circulating fluid is low when the circulating fluid is heated.

Further, in the heat pump device 1 of the present embodiment, the control unit 80 determines that the refrigerant in the throttle circuit 19 when the high pressure of the refrigerant is out of a predetermined determination range (first determination range or second determination range). The flowability of the above is changed according to the pressure of the refrigerant circuit (step S102, step S103, step S202, step S203).

As a result, the pressure of the refrigerant circuit can be appropriately controlled when the high-pressure pressure is difficult to increase or when the pressure is excessively high due to overload.

Further, in the heat pump device 1 of the present embodiment, the control unit 80 selectively performs the first control and the second control. In the first control, the control unit 80 changes the ease of flow of the refrigerant in the throttle circuit 19 according to the pressure of the refrigerant circuit (step S102 in FIG. 3 and step S202 in FIG. 4). In the second control, the control unit 80 changes the strength of supercooling performed in the throttle circuit 19 according to the difference between the target supercooling degree and the current supercooling degree (step S104 in FIG. 3, FIG. Step 4 S204).

Thereby, it is possible to cope with both the situation where the high pressure pressure is desired to be obtained satisfactorily and the situation where the refrigerant is desired to be supercooled with an appropriate strength by using the common throttle circuit 19.

Further, in the heat pump device 1 of the present embodiment, the control unit 80 performs the second control, and when the circulating liquid is cooled, the temperature of the outside air is equal to or higher than the first temperature, and the high pressure of the refrigerant is previously set. It is performed when it is within the defined first determination range (step S101, step S103, step S104 in FIG. 3). When the circulating liquid is heated, the control unit 80 controls the second control so that the temperature of the circulating liquid is equal to or higher than the second temperature and the high pressure of the refrigerant is within a predetermined second determination range. Occasionally (step S201, step S203, step S204 in FIG. 4).

As a result, appropriate control can be performed according to the situation.

Further, in the heat pump device 1 of the present embodiment, the control unit 80 obtains the target supercooling degree based on the circulating flow rate of the refrigerant in the refrigerant circuit. The control unit 80 determines the current degree of supercooling of the refrigerant temperature (first temperature sensor 76) detected in the refrigerant path from the outside air-refrigerant heat exchanger 31 or the circulating fluid-refrigerant heat exchanger 32 to the throttle circuit 19. Alternatively, it is obtained by using the detection temperature of the second temperature sensor 77) and the high pressure of the refrigerant (detection pressure of the high pressure sensor 71).

As a result, the target supercooling degree can be substantially determined according to the load, and the pressure of the refrigerant is not detected at the outlet of the outside air-refrigerant heat exchanger 31 or the circulating fluid-refrigerant heat exchanger 32. The degree of supercooling of the refrigerant can be obtained. As a result, the degree of supercooling of the refrigerant can be appropriately controlled with a simple configuration, so that the heat pump device 1 having excellent performance can be realized.

Further, in the heat pump device 1 of the present embodiment, the throttle circuit 19 includes a plurality of valves (first on-off valve 51, second on-off valve 52, and expansion valve 53) connected in parallel to each other.

As a result, the ease of flow of the refrigerant in the throttle circuit 19 can be flexibly changed according to the situation.

Further, in the heat pump device 1 of the present embodiment, the throttle circuit 19 includes an expansion valve 53 whose opening degree can be adjusted.

Thereby, the strength of supercooling given to the refrigerant can be adjusted by the throttle circuit 19.

Although the preferred embodiment of the present invention has been described above, the above configuration can be changed as follows, for example.

The circulating flow rate of the refrigerant is obtained from the rotation speed of the compressor 11 in the same manner as described above, and when the refrigerant flow rate is small, the first on-off valve 51, the second on-off valve 52, and expansion are made so that the refrigerant does not easily flow through the throttle circuit 19. The valve 53 may be controlled.

When the pressure detected by the high pressure sensor 71 becomes equal to or higher than a predetermined value, the control unit 80 may control the first on-off valve 51, the second on-off valve 52, and the expansion valve 53 to be fully opened. .. Thereby, the pressure increase due to the overload can be effectively alleviated.

The throttle circuit 19 may be configured to include only one on-off valve instead of the configuration including the first on-off valve 51 and the second on-off valve 52. Further, three or more on-off valves may be provided. Further, a plurality of expansion valves may be arranged in parallel.

The number of outside air-refrigerant heat exchangers 31 can be changed to one or three or more. Further, the number of circulating liquid-refrigerant heat exchangers 32 can be changed to two or more.

The supercooling heat exchanger 24 that applies supercooling to the refrigerant emitted from the receiver 23 may be omitted.

The present invention can also be applied to a hybrid heat pump device including a compressor driven by an engine and a compressor driven by an electric motor.

1 Heat pump device 18 Bridge circuit 19 Aperture circuit (aperture section)
23 Receiver 31 Outside air-refrigerant heat exchanger (first heat exchanger)
32 Circulating liquid-refrigerant heat exchanger (second heat exchanger)
80 Control unit

Claims (8)

A heat pump device capable of cooling and heating the supplied circulating fluid.
The first heat exchanger that exchanges heat between the outside air and the refrigerant,
A second heat exchanger that exchanges heat between the circulating fluid and the refrigerant,
The first heat exchanger and the receiver connected to the second heat exchanger,
A bridge circuit that supplies the refrigerant from the first heat exchanger to the receiver when the circulating fluid is cooled, and supplies the refrigerant from the second heat exchanger to the receiver when the circulating fluid is heated.
A throttle portion arranged in a refrigerant path connecting the receiver and the bridge circuit, and
If prior SL temperature of the circulating liquid at the time of the heating of the circulating fluid is lower than the second temperature which is below the lower limit temperature of the temperature setting range of the circulating fluid during the heating operation, the flowability of the refrigerant in the narrowed portion A control unit that changes according to the pressure of the refrigerant circuit,
A heat pump device characterized by being provided with. The heat pump device according to claim 1.
When the temperature of the outside air is lower than the predetermined first temperature when the circulating fluid is cooled, the control unit changes the ease of flow of the refrigerant in the throttle unit according to the pressure of the refrigerant circuit.
A heat pump device characterized in that the first temperature is 21 ° C. or lower. The heat pump device according to claim 1 or 2.
A heat pump device characterized in that when the high-pressure pressure of the refrigerant is out of a predetermined determination range, the ease of flow of the refrigerant in the throttle portion is changed according to the pressure of the refrigerant circuit. The heat pump device according to any one of claims 1 to 3.
The control unit
The first control that changes the ease of flow of the refrigerant in the throttle portion according to the pressure of the refrigerant circuit, and
A second control that changes the strength of supercooling performed in the throttle section according to the difference between the target supercooling degree and the current supercooling degree.
A heat pump device characterized by selectively performing. The heat pump device according to claim 4.
Wherein the control unit, the second control, at the time of heating before Symbol circulating liquid, wherein it is the temperature of the circulating fluid is the second temperature or more, and, the second determination high pressure of the refrigerant is predetermined A heat pump device characterized in that it is performed when it is within range. The heat pump device according to claim 4 or 5.
The control unit obtains the target supercooling degree based on the circulating flow rate of the refrigerant in the refrigerant circuit.
The control unit determines the current degree of supercooling, the temperature of the refrigerant detected in the refrigerant path from the first heat exchanger or the second heat exchanger to the throttle portion, and the high-pressure pressure of the refrigerant. A heat pump device characterized in that it is obtained by using it. The heat pump device according to any one of claims 1 to 6.
The throttle portion is a heat pump device including a plurality of valves connected in parallel to each other. The heat pump device according to any one of claims 1 to 7.
The throttle portion is a heat pump device including an expansion valve whose opening degree can be adjusted.

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