WO2017022101A1

WO2017022101A1 - Chilling unit

Info

Publication number: WO2017022101A1
Application number: PCT/JP2015/072254
Authority: WO
Inventors: 正紘伊藤; 航祐田中; 拓也伊藤; 靖大越
Original assignee: 三菱電機株式会社
Priority date: 2015-08-05
Filing date: 2015-08-05
Publication date: 2017-02-09
Also published as: JP6437120B2; JPWO2017022101A1

Abstract

This chilling unit is equipped with: a refrigerant circuit that is configured by a compressor, a four-way valve, an air heat exchanger, a main expansion valve, and a water heat exchanger being sequentially connected by piping and circulates a refrigerant therethrough; and a bypass circuit that is connected in parallel with the refrigerant circuit between the main expansion valve and the water heat exchanger and between the main expansion valve and the air heat exchanger. The four-way valve is capable of switching between the paths of a cooling operation mode and a heating operation mode. The bypass circuit has a solenoid valve, a pump down expansion valve, and a refrigerant tank that stores liquid refrigerant. The liquid refrigerant is stored in the refrigerant tank before at least the cooling operation mode or the heating operation mode is started.

Description

Chilling unit

The present invention relates to a chilling unit. In particular, it relates to prevention of liquid back.

For example, there is a refrigeration cycle apparatus having an accumulator for storing excess refrigerant in a refrigerant circuit. The accumulator is a container that stores excess refrigerant as a liquid refrigerant (liquid refrigerant). Here, for example, when starting the stopped refrigerant circuit, a liquid back is generated in which the liquid refrigerant accumulated in the evaporator, the suction side piping of the compressor, etc. flows into the compressor. If a large amount of liquid refrigerant flows into the compressor, it will cause a failure. Therefore, in order to suppress the liquid back, conventionally, the liquid refrigerant is accumulated in the accumulator so that the liquid refrigerant does not return to the compressor.

JP-A-63-290371 (FIG. 1)

However, if the refrigerant is stored in the accumulator to prevent liquid back, the accumulator container must be enlarged to secure the volume. For this reason, it cannot respond to the request | requirement of compactization and cost reduction.

The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain a chilling unit capable of preventing the occurrence of liquid back without using an accumulator.

A chilling unit according to the present invention includes a refrigerant circuit in which a compressor, a flow path switching device, an air heat exchanger, a first throttle device, and a heat medium heat exchanger are sequentially connected by piping, and through which a refrigerant flows, and a first throttle And a bypass circuit connected in parallel with the refrigerant circuit between the device and the heat medium heat exchanger, and between the first expansion device and the air heat exchanger. It is possible to switch between a flow path that is a cooling operation mode in which the exchanger becomes an evaporator and cools the heat medium and a flow path that becomes a heating operation mode in which the heat medium heat exchanger becomes a condenser and heats the heat medium. The bypass circuit is provided in the bypass circuit and controls the flow rate of the refrigerant flowing through the bypass circuit. The second throttle is provided in the bypass circuit and adjusts the refrigerant flowing through the bypass circuit in cooperation with the flow rate adjusting device. Equipment, and buy A refrigerant tank that is provided between the flow adjustment device of the flow circuit and the second expansion device and stores liquid refrigerant that has passed through the flow adjustment device or the second expansion device, and at least starts a cooling operation mode or performs a heating operation Before the mode starts, the liquid refrigerant is accumulated in the refrigerant tank.

According to the chilling unit of the present invention, based on the control of the operation control device, the chilling unit is in a state in which liquid refrigerant is accumulated in the refrigerant tank before at least performing the normal heating operation mode or cooling operation mode. Thus, liquid back at the start of normal operation can be prevented.

It is a figure which shows the structure of the chilling unit 100 which concerns on Embodiment 1 of this invention. It is a figure which shows the structure of the refrigerant | coolant tank 83 in the chilling unit 100 which concerns on Embodiment 1 of this invention. It is a figure explaining the operation | movement etc. in the pump down driving | operation before cooling which concerns on Embodiment 1 of this invention. It is a figure explaining the operation | movement in the pump down driving | operation etc. before a heating which concerns on Embodiment 1 of this invention. It is a figure for performing the description which concerns on the determination of the pump down driving | operation before a driving | operation which concerns on Embodiment 2 of this invention. It is a figure which shows the structure of the refrigerant | coolant tank 83 in the chilling unit 100 which concerns on Embodiment 3 of this invention.

Hereinafter, a chilling unit according to an embodiment of the present invention will be described with reference to the drawings. In the following drawings, the same reference numerals denote the same or corresponding parts, and are common to the whole text of the embodiments described below. And the form of the component represented to the whole text of specification is an illustration to the last, Comprising: It does not limit to the form described in the specification. In particular, the combination of the components is not limited to the combination in each embodiment, and the components described in the other embodiments can be applied to another embodiment. In addition, when there is no need to particularly distinguish or specify a plurality of similar devices that are distinguished by subscripts, the subscripts may be omitted. In the drawings, the relationship between the sizes of the constituent members may be different from the actual one. The level of temperature, pressure, etc. is not particularly determined in relation to absolute values, but is relatively determined in terms of the state and operation of each system and each device.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration of a chilling unit 100 according to Embodiment 1 of the present invention. Based on FIG. 1, the configuration and operation of the chilling unit 100 will be described. The chilling unit 100 in the present embodiment constitutes a refrigerant circuit that circulates refrigerant, and uses a refrigeration cycle (heat pump cycle) as an operation for cooling and heating a heat medium serving as a medium for transferring heat as a normal operation. Do. Here, it demonstrates as what uses water as a thermal medium. Moreover, in this Embodiment, the object space shall be air-conditioned by the heat which water conveys. For this reason, the heating operation of the chilling unit 100 will be described as a heating operation, and the cooling operation will be described as a cooling operation. As will be described later, the cooling operation is an operation that satisfies at least one of a case where the discharge side of the compressor 10 and the air heat exchanger 30 are connected via the four-way valve 20 and a case where the temperature of the water decreases. It is. Further, the heating operation satisfies at least one of a case where the discharge side of the compressor 10 and the water heat exchanger 60 are connected via the four-way valve 20 and a case where the temperature of the water rises, as will be described later. Driving.

As shown in FIG. 1, the chilling unit 100 of this embodiment includes a compressor 10, a four-way valve 20, an air heat exchanger 30, a distribution capillary 40, a main expansion valve 50, a water heat exchanger 60, and an accumulator 70. And has a main refrigerant circuit. Moreover, it has the control apparatus 200 which controls the component apparatus of a refrigerant circuit.

Compressor 10 compresses and discharges the sucked refrigerant. Here, the compressor 10 may have, for example, an inverter drive device. The capacity of the compressor 10 (the amount of refrigerant sent out per unit time) can be finely changed by arbitrarily changing the drive frequency based on an instruction from the control device 200. Further, the four-way valve 20 serving as the flow path switching device switches the refrigerant flow by the operation to be executed based on the instruction from the control device 200. For example, during cooling operation, the four-way valve 20 allows the refrigerant to flow so that the high-temperature and high-pressure refrigerant discharged from the compressor 10 flows into the air heat exchanger 30. Further, at the time of heating operation or the like, the refrigerant flows so that the high-temperature and high-pressure refrigerant discharged from the compressor 10 flows into the water heat exchanger 60.

The air heat exchanger 30 has a plurality of heat transfer tubes, and performs heat exchange between the refrigerant passing through the heat transfer tubes and air (for example, outside air). The air heat exchanger 30 functions as an evaporator during heating operation, performs heat exchange between the low-pressure refrigerant flowing from the main expansion valve 50 (distribution capillary 40) side and air, and evaporates and vaporizes the refrigerant. . Further, during the cooling operation, it functions as a condenser, performs heat exchange between the low-pressure refrigerant flowing from the compressor 10 side and air, and condenses and liquefies the refrigerant. The distribution capillary 40 serving as a distributor has, for example, a capillary tube. The distribution capillary 40 distributes the refrigerant flowing from the main expansion valve 50 side to the plurality of heat transfer tubes of the air heat exchanger 30.

The water heat exchanger 60 serving as a heat medium heat exchanger performs heat exchange between the refrigerant and water. The water heat exchanger 60 functions as a condenser during heating operation, for example, and performs heat exchange between the refrigerant flowing in from the compressor 10 side and water, condensing the refrigerant and liquefying (or gas-liquid two-phase). And heat the water. On the other hand, during the cooling operation, it functions as an evaporator, performs heat exchange between the refrigerant flowing in from the main expansion valve 50 side and water, evaporates and vaporizes the refrigerant, and cools the water. The main expansion valve 50 serving as the first expansion device adjusts the pressure of the refrigerant in the water heat exchanger 60, for example, by changing the opening degree. The main expansion valve 50 may be a temperature-sensitive expansion valve that changes its opening degree based on the temperature of the refrigerant, but in this embodiment, the opening degree is changed based on an instruction from the control device 200. It consists of an electronic expansion valve. The accumulator 70 is provided on the suction side of the compressor 10 and stores excess refrigerant in the refrigerant circuit.

Further, the chilling unit 100 of the present embodiment has a pump-down flow path 80 connected in parallel with the main expansion valve 50. The pump-down flow path 80 includes a first branch pipe 81, a second branch pipe 82, a refrigerant tank 83, an electromagnetic valve 84, and a pump-down expansion valve 85.

1st branch piping 81 used as 1st piping is branch piping which connects the piping between the main expansion valve 50 and the water heat exchanger 60, and the refrigerant | coolant tank 83 (tank main body 91 mentioned later). An electromagnetic valve 84 serving as a flow rate adjusting device is installed in the first branch pipe 81. The electromagnetic valve 84 opens or closes the valve based on an instruction from the control device 200 and controls whether or not the refrigerant passes through the pump-down flow path 80. Here, the flow rate adjusting device is configured by the electromagnetic valve 84. However, for example, an expansion valve or the like may be used as the flow rate adjusting device as long as it is possible to control whether the refrigerant is allowed to pass by opening and closing the flow path.

The second branch pipe 82 serving as the second pipe is a branch connecting the pipe between the main expansion valve 50 and the distribution capillary 40 (air heat exchanger 30) and the refrigerant tank 83 (tank body 91 described later). It is piping. The pump-down expansion valve 85 serving as the second expansion device can change the opening degree based on an instruction from the control device 200 and adjusts the amount of refrigerant flowing into and out of the refrigerant tank 83.

FIG. 2 is a diagram showing the configuration of the refrigerant tank 83 in the chilling unit 100 according to Embodiment 1 of the present invention. The refrigerant tank 83 of the present embodiment has a tank body 91, a first pipe connection part 92, a second pipe connection part 93, an extension pipe 94 and an oil return hole 95. The tank body 91 is a container for storing a liquid refrigerant. The first pipe connection part 92 is installed on the upper part of the tank main body 91. A first branch pipe 81 is connected to the first pipe connection portion 92. The second pipe connection part 93 is installed at the lower part of the tank body 91. A second branch pipe 82 is connected to the second pipe connection portion 93.

The extension pipe 94 protrudes into the tank body 91 and has an opening at the top. The extension pipe 94 extends through the second branch pipe 82 into the tank body 91 by communicating with the second branch pipe 82 through the second pipe connection portion 93. The oil return hole 95 is formed in the lower part of the extension pipe 94 and returns the refrigeration oil accumulated in the tank body 91 together with the refrigerant to the refrigerant circuit. The refrigerating machine oil is oil that prevents the compressor 10 from being seized. For example, refrigerating machine oil that has a higher density than liquid refrigerant and is incompatible (oil that does not dissolve in the refrigerant) separates from the liquid refrigerant and accumulates below the liquid refrigerant in the tank body 91. Therefore, it is desirable to provide the oil return hole 95 at a position as low as possible in the tank body 91 (desirably, a boundary portion with the bottom surface).

Also, it has an outside air temperature sensor 211, a water temperature sensor 212, and a liquid level detector 213. The outside air temperature sensor 211 detects the temperature of outside air to be heat exchanged with the refrigerant in the air heat exchanger 30. A water temperature sensor 212 serving as a heat medium temperature sensor detects the temperature of water to be heat exchanged with the refrigerant in the water heat exchanger 60. The liquid level detector 213 detects the liquid level of the liquid refrigerant accumulated in the refrigerant tank 83. For example, it is detected whether or not the liquid refrigerant in the refrigerant tank 83 is in a state (for example, a full state). Here, in the present embodiment, the liquid level detector 213 detects whether or not the refrigerant tank 83 is full, but the present invention is not limited to this. For example, you may have a sensor etc. which detect the amount of liquid refrigerant in a refrigerant tank.

The control device 200 controls the chilling unit 100. The control device 200 according to the present embodiment includes at least an operation control device 210 and a determination device 220. The operation control device 210 performs operation control of the entire chilling unit 100. The operation control device 210 according to the present embodiment is a pre-operation pump-down operation in which liquid refrigerant is stored in the refrigerant tank 83, particularly in a stage before performing a normal operation (including a case where the operation is performed by switching between a cooling operation and a heating operation). I do. When performing the pump-down operation before operation, not only the devices such as the compressor 10 and the main expansion valve 50 as in the normal operation, but also the electromagnetic valve 84 and the pump-down expansion valve 85 are controlled. The determination device 220 performs various determinations such as operation stop based on, for example, temperatures detected by the outside air temperature sensor 211 and the water temperature sensor 212, detection by the liquid level detector 213, and the like.

Here, for example, the operation control device 210 and the determination device 220 of the control device 200 in the present embodiment can be configured by different hardware, for example. In addition, the processing procedure may be preprogrammed and configured by software, firmware, or the like while being configured by arithmetic control means (computer) such as a CPU (Central Processing Unit). The arithmetic control means executes the program, performs processing based on the program, and realizes processing performed by each of the above devices. The data of these programs may be stored in a storage device (not shown), for example.

The chilling unit 100 of the present embodiment performs a pre-operation pump down operation as a previous step at least when starting a normal operation. Here, the pump-down operation before operation is divided into a pump-down operation before cooling performed before the cooling operation and a pump-down operation before heating performed before the heating operation.

FIG. 3 is a diagram for explaining the operation in the pre-cooling pump down operation according to the first embodiment of the present invention. In the cooling operation, the refrigerant flows from the water heat exchanger 60 side to the accumulator 70 (compressor 10). For this reason, at the start of the cooling operation, it is desired to reduce the amount of liquid refrigerant that has fallen into the water heat exchanger 60 to the accumulator 70 (compressor 10) side as much as possible. Therefore, before the cooling operation, liquid refrigerant such as the water heat exchanger 60 is accumulated in the refrigerant tank 83 to suppress the amount of liquid refrigerant flowing to the accumulator 70 side.

When performing the pump-down operation before cooling, the operation control device 210 sets the flow path in the four-way valve 20 so that the refrigerant flow is the same as in the heating operation. And before starting the compressor 10, the solenoid valve 84 is closed. The pump down expansion valve 85 is opened. The main expansion valve 50 is closed (FIG. 3 (a)).

Then, the solenoid valve 84 is opened. Further, the pump-down expansion valve 85 is slightly opened (slightly opened). Further, the main expansion valve 50 is opened (FIG. 3B). Then, the compressor 10 is started. In the state where the main expansion valve 50 is closed, the pre-operation pump-down operation tends to accumulate liquid refrigerant in the refrigerant tank 83, but the operation is not stable. Therefore, in order to perform the pump-down operation before operation while stabilizing the refrigerant circuit, it is performed while controlling the opening degree of the main expansion valve 50.

When the compressor 10 is started, the refrigerant in the water heat exchanger 60 and the like flows out from the water heat exchanger 60 side, flows through the main expansion valve 50 side, and part of the refrigerant flows into the pump down flow path 80 side. The refrigerant that has flowed to the pump-down flow path 80 side passes through the first branch pipe 81 (electromagnetic valve 84) and flows into the refrigerant tank 83. At this time, the gaseous refrigerant (gas refrigerant) in the refrigerant tank 83 (tank main body 91) flows out from the refrigerant tank 83 through the opening of the extension pipe 94 in an extruded form, and then enters the second branch pipe 82 ( It passes through the pump-down expansion valve 85) and joins the main refrigerant circuit.

Among the refrigerant flowing into the refrigerant tank 83, the liquid refrigerant is stored in the tank body 91. At this time, the refrigeration oil that flows in together with the refrigerant stays in the lower portion of the tank body 91, but flows out of the refrigerant tank 83 together with the gas refrigerant through the oil return hole 95, passes through the second branch pipe 82, It merges into the refrigerant circuit.

If the determination device 220 determines that the refrigerant tank 83 is full based on the signal from the liquid level detector 213, the operation control device 210 ends the pre-cooling pump down operation. The operation control device 210 closes the electromagnetic valve 84 and the main expansion valve 50 (FIG. 3C). Then, the compressor 10 is stopped, and the pre-cooling pump down operation is ended. And the operation control apparatus 210 transfers to control of air_conditionaing | cooling operation.

FIG. 4 is a diagram for explaining the operation in the pump-down operation before heating according to Embodiment 1 of the present invention. In the heating operation, the refrigerant flows from the air heat exchanger 30 side to the accumulator 70 (compressor 10). For this reason, at the start of the heating operation, it is desired to reduce the amount of liquid refrigerant that has fallen into the air heat exchanger 30 to the accumulator 70 (compressor 10) side as much as possible. Therefore, before the heating operation, liquid refrigerant such as the air heat exchanger 30 is accumulated in the refrigerant tank 83 to suppress the amount of liquid refrigerant flowing to the accumulator 70 side.

When performing the pump-down operation before heating, the operation control device 210 sets the flow path in the four-way valve 20 so that the refrigerant flow is the same as in the cooling operation. And before starting the compressor 10, the electromagnetic valve 84 is opened. The pump down expansion valve 85 is closed. The main expansion valve 50 is closed (FIG. 4 (a)).

Then, the solenoid valve 84 is opened. Further, the pump-down expansion valve 85 is slightly opened (slightly opened). Further, the main expansion valve 50 is opened (FIG. 4B). Then, the compressor 10 is started.

When the compressor 10 is started, the refrigerant in the air heat exchanger 30 or the like flows out from the air heat exchanger 30 side, flows through the main expansion valve 50 side, and part of the refrigerant flows into the pump down flow path 80 side. The refrigerant that has flowed to the pump-down flow path 80 side passes through the second branch pipe 82 (pump-down expansion valve 85) and flows into the refrigerant tank 83. At this time, the gaseous refrigerant (gas refrigerant) in the refrigerant tank 83 (tank main body 91) flows out from the refrigerant tank 83 via the first pipe connection portion 92 in an extruded form, and the first branch pipe 81. It passes through the (electromagnetic valve 84) and joins the main refrigerant circuit. Of the refrigerant that has flowed into the refrigerant tank 83, the liquid refrigerant is stored in the tank body 91.

If the determination device 220 determines that the refrigerant tank 83 is full based on the signal from the liquid level detector 213, the operation control device 210 ends the pre-heating pump-down operation. The operation control device 210 closes the pump down expansion valve 85 and the main expansion valve 50 (FIG. 4C). Then, the compressor 10 is stopped, and the pre-heating pump down operation is terminated. And the operation control apparatus 210 transfers to control of heating operation.
Here, with respect to the refrigerating machine oil, the refrigerating machine oil mixed with the liquid refrigerant flows out of the refrigerating tank 83 when the refrigerating tank 83 becomes full.

As described above, according to the chilling unit 100 of the first embodiment, for example, in a stage before performing a normal operation (heating operation or cooling operation), a liquid refrigerant that performs a pump-down operation before operation and has a risk of liquid back. Is stored in the refrigerant tank 83 and the normal operation is performed, so that the volume of the accumulator 70 can be reduced. For this reason, the chilling unit 100 can be reduced in size. For example, the volume of the accumulator 70 can be expected to be about 1/3.

Embodiment 2. FIG.
FIG. 5 is a diagram for explaining the determination of the pre-operation pump down operation according to Embodiment 2 of the present invention. Although not specifically defined in the above-described first embodiment, for example, it is determined whether or not the pre-operation pump down operation is performed at the timing of performing the pre-operation pump down operation shown in the first embodiment. Good. The determination in the present embodiment is performed by the determination device 220 of the control device 200.

As shown in FIG. 5, in the present embodiment, the determination is made based on the state of the chilling unit 100, the temperature relationship, and the state of the refrigerant tank 83. The determination device 220 determines the state of the chilling unit 100 based on whether it is a stop state before the cooling operation or a stop state before the heating operation. Further, regarding the temperature relationship, the determination device 220 has an air temperature (a temperature related to detection by the outside air temperature sensor 211) equal to or higher than a water temperature (a temperature related to detection by the water temperature sensor 212) (the air temperature is lower than the water temperature). ) Or not. The determination device 220 determines the state of the refrigerant tank 83 based on whether it is full or not. In the present embodiment, the determination device 220 performs the determination in the order of the state of the chilling unit 100, the temperature relationship, and the state of the refrigerant tank 83, but the order is not limited.

The determination device 220 determines whether it is a stop state before the cooling operation or a stop state before the heating operation. If it is determined that the vehicle is stopped before the cooling operation, NO. 01-NO. Either of 08. If it is determined that the vehicle is stopped before the cooling operation, NO. 09-NO. 16 either.

First, the case where it is determined that the vehicle is stopped before the cooling operation will be described. The determination device 220 determines whether the air temperature is equal to or higher than the water temperature. For example, if it is determined that the air temperature is lower than the water temperature (NO.05 to NO.08), liquid refrigerant accumulates on the air heat exchanger 30 side. At this time, the refrigerant in the water heat exchanger 60 moves. I fall asleep. Therefore, even if the chilling unit 100 starts the cooling operation in a state where the air temperature is lower than the water temperature, the liquid refrigerant in the air heat exchanger 30 is evaporated in the water heat exchanger 60. There is little risk to occur. Therefore, the determination device 220 determines that it is not necessary to perform the pump-down operation before cooling. The operation control device 210 does not perform the pump-down operation before cooling based on the determination of the determination device 220.

On the other hand, when the determination device 220 determines that the air temperature is equal to or higher than the water temperature (NO.01 to NO.04), the determination device 220 further determines whether the liquid level is full or not based on the detection of the liquid level detector 213. To do. If the determination device 220 determines that the liquid is full (NO.01, NO.03), it is assumed that most of the liquid refrigerant is stored in the refrigerant tank 83 and that there is little risk of liquid back. Therefore, the determination device 220 determines that it is not necessary to perform the pump-down operation before cooling.

If the determination device 220 determines that the liquid is not full (NO.02, NO.04), a large amount of liquid refrigerant accumulates due to the refrigerant sleeping in the water heat exchanger 60, and liquid back may occur. Suppose there is sex. Therefore, the determination device 220 determines that it is necessary to perform the pump-down operation before operation. The operation control device 210 performs a pump-down operation before cooling based on the determination of the determination device 220.

Next, a case where it is determined that the vehicle is stopped before the heating operation will be described. The determination device 220 determines whether the air temperature is equal to or higher than the water temperature. For example, if it is determined that the air temperature is equal to or higher than the water temperature (NO. 09 to NO. 12), liquid refrigerant is accumulated on the water heat exchanger 60 side. At this time, the refrigerant in the air heat exchanger 30 moves. I fall asleep. Therefore, even if the chilling unit 100 starts the heating operation in the state where the air temperature is equal to or higher than the water temperature, the liquid refrigerant in the water heat exchanger 60 is evaporated in the air heat exchanger 30, so the liquid back There is little risk to occur. Therefore, the determination apparatus 220 determines that it is not necessary to perform the pump-down operation before heating. The operation control device 210 does not perform the pre-heating pump down operation based on the determination of the determination device 220.

On the other hand, when determining that the air temperature is lower than the water temperature (NO.13 to NO.16), determination device 220 further determines whether the liquid level is full or not based on the detection of liquid level detector 213. To do. If the determination device 220 determines that the liquid is full (NO.13, NO.15), it is assumed that most of the liquid refrigerant is stored in the refrigerant tank 83 and that the risk of liquid back is small. Therefore, the determination apparatus 220 determines that it is not necessary to perform the pump-down operation before heating.

If the determination device 220 determines that the liquid is not full (NO.14, NO.16), the refrigerant stagnates in the air heat exchanger 30, so that a large amount of liquid refrigerant accumulates and liquid back may occur. Suppose there is sex. Therefore, the determination apparatus 220 determines that it is necessary to perform the pump-down operation before heating. The operation control device 210 performs the pre-heating pump down operation based on the determination by the determination device 220.

As described above, according to the chilling unit 100 of the second embodiment, since the determination device 220 determines whether to perform the pre-operation pump down operation, it is not necessary to perform an unnecessary pre-operation pump down operation. .

Embodiment 3 FIG.
FIG. 6 is a diagram showing a configuration of the refrigerant tank 83 in the chilling unit 100 according to Embodiment 3 of the present invention. The present embodiment shows a refrigerant tank 83 having a configuration example different from the refrigerant tank 83 described with reference to FIG. 2 in the first embodiment.

In FIG. 6, the description will focus on parts different from the refrigerant tank 83 described in Embodiment 1 with reference to FIG. 2. The second pipe connection portion 93 in FIG. 2 is installed in the lower portion of the tank main body 91. However, in the refrigerant tank 83 of the present embodiment, the lower portion of the tank main body 91 is provided in the same manner as the first pipe connection portion 92. is set up.

Further, the refrigerant tank 83 of the present embodiment has a third pipe connection portion 96, an oil return pipe 97, and an oil return capillary 98 that serves as an oil return adjustment device. The third pipe connection part 96 is installed in the lower part of the tank main body 91. The oil return pipe 97 has one end connected to the third pipe connection 96 and the other connected to the second branch pipe 82. The oil return pipe 97 is a pipe through which the refrigerating machine oil accumulated in the lower part of the tank main body 91 flows to the second branch pipe 82. The oil return capillary 98 adjusts the amount of refrigerating machine oil flowing through the oil return pipe 97.

Embodiment 4 FIG.
In the chilling unit 100 of the first to third embodiments described above, the pre-operation pump down operation is performed in the stage before performing the normal operation, but there is no particular limitation. For example, in addition to the normal operation, the pre-operation pump down operation may be performed periodically (periodically). Further, if the determination device 220 periodically performs the determination described in the second embodiment and determines that the pre-operation pump down operation is necessary, the operation control device 210 controls the pre-operation pump down operation. It may be.

10 compressor, 20 four-way valve, 30 air heat exchanger, 40 distribution capillary, 50 main expansion valve, 60 water heat exchanger, 70 accumulator, 80 pump-down flow path, 81 first branch pipe, 82 second Branch piping, 83 refrigerant tank, 84 solenoid valve, 85 pump down expansion valve, 91 tank body, 92 1st piping connection, 93 2nd piping connection, 94 extension piping, 95 oil return hole, 96 3rd Pipe connection part, 97 oil return pipe, 98 oil return capillary, 100 chilling unit, 200 control device, 210 operation control device, 211 outside air temperature sensor, 212 water temperature sensor, 213 liquid level detector, 220 determination device.

Claims

A refrigerant circuit in which a compressor, a flow path switching device, an air heat exchanger, a first expansion device, and a heat medium heat exchanger are sequentially connected by piping, and a refrigerant flows;
A bypass circuit connected in parallel with the refrigerant circuit between the first expansion device and the heat medium heat exchanger and between the first expansion device and the air heat exchanger;
In the flow path switching device, the heat medium heat exchanger serves as an evaporator, and the heat medium heat exchanger serves as a condenser and the heat medium heat exchanger serves as a condenser to heat the heat medium. It can be switched to the flow path that becomes the heating operation mode,
The bypass circuit is:
A flow rate adjusting device provided in the bypass circuit for controlling the flow rate of the refrigerant flowing through the bypass circuit, and a second throttle provided in the bypass circuit for adjusting the refrigerant flowing through the bypass circuit in cooperation with the flow rate adjusting device. And a refrigerant tank that is provided between the flow rate adjusting device and the second throttling device of the bypass circuit and stores liquid refrigerant that has passed through the flow rate adjusting device or the second throttling device,
The chilling unit in which the liquid refrigerant is accumulated in the refrigerant tank at least before the start of the cooling operation mode or the heating operation mode.
A heat medium temperature sensor for detecting the temperature of the heat medium;
An outside temperature sensor that detects the temperature of the outside air,
A refrigerant amount detection sensor for detecting the amount of the liquid refrigerant in the refrigerant tank;
2. The determination device according to claim 1, further comprising: a determination device that determines whether to store the liquid refrigerant in the refrigerant tank from the temperature of the heat medium, the temperature of the outside air, and the amount of the liquid refrigerant in the refrigerant tank. Chilling unit.
Before starting the heating operation mode, the liquid refrigerant flowing from the air heat exchanger side is changed by switching the flow path switching device so that the refrigerant flows from the air heat exchanger side to the first expansion device side. Store in the refrigerant tank,
Before starting the cooling operation mode, the liquid that flows from the heat medium heat exchanger side by switching the flow path switching device so that the refrigerant flows from the heat medium heat exchanger side to the first expansion device side The chilling unit according to claim 1 or 2, wherein an operation for storing the refrigerant in the refrigerant tank is performed.
The refrigerant tank is
The tank body,
A first pipe connection part installed at an upper part of the tank main body, to which a pipe between the first expansion device and the heat medium heat exchanger and a first pipe connecting the tank main body are connected; ,
A second pipe connecting portion installed at a lower part of the tank body, to which a pipe between the first expansion device and the air heat exchanger and a second pipe connecting the tank body are connected;
An extension pipe that is installed in the tank body, communicates with the second pipe connection portion, and extends the second pipe toward the upper portion of the tank body;
The chilling unit according to any one of claims 1 to 3, further comprising an oil return hole formed at a lower portion of the extension pipe and configured to return the refrigeration oil accumulated in the tank body to the refrigerant circuit.
The refrigerant tank is
The tank body,
A first pipe connection part installed at an upper part of the tank main body, to which a pipe between the first expansion device and the heat medium heat exchanger and a first pipe connecting the tank main body are connected; ,
A second pipe connecting portion installed at an upper part of the tank body, to which a pipe between the first expansion device and the air heat exchanger and a second pipe connecting the tank body are connected;
An oil return pipe for connecting the lower part of the tank body and the second pipe to return the refrigeration oil accumulated in the tank body to the refrigerant circuit;
The chilling unit according to any one of claims 1 to 3, further comprising an oil adjusting device that adjusts an amount of the refrigerating machine oil flowing through the oil return pipe.