JP2021025684A - Cooling storage - Google Patents

Abstract

To provide a cooling storage capable of changing a flow rate of a liquid-phase refrigerant flowing in a liquid injection circuit according to load fluctuation while suppressing increase of the number of components.SOLUTION: In a closed showcase including a refrigeration circuit in which an invertor compressor, a condenser, an expansion valve and an evaporator are connected in a circulative manner by pipes 39, and a liquid injection circuit 40 branched from a pipe 39B for connecting the condenser and the expansion valve, and connected to the invertor compressor, the liquid injection circuit 40 has a branch pipe 60 branched from the pipe 39B for connecting the condenser and the expansion valve and raised upward, and two capillary tubes 61A, 61B connected to the branch pipe 60, and heights of connection positions of the capillary tubes 61 are different from each other.SELECTED DRAWING: Figure 4

Description

The techniques disclosed herein relate to refrigerated storage.

Conventionally, in a refrigeration circuit in which a compressor, a condenser, an expansion component and an evaporator are circulated and connected by piping, a refrigeration circuit including a liquid injection circuit for sending a refrigerant between the condenser and the expansion component to the compressor has been known. There is. Specifically, the high-temperature / high-pressure gas-phase refrigerant sent out from the compressor becomes a high-temperature / high-pressure liquid-phase refrigerant by being dissipated by the condenser. The liquid injection circuit is a circuit that cools the compressor by branching a high-temperature, high-pressure liquid-phase refrigerant from the main circuit and returning it to the compressor via a capillary tube. When the high-temperature and high-pressure liquid-phase refrigerant is returned to the compressor, the motor winding of the compressor is cooled by the latent heat of evaporation of the liquid-phase refrigerant, so that the motor winding can be prevented from being overheated above the heat-resistant temperature.

The flow rate of the liquid injection circuit is determined by verifying with each refrigeration circuit. Usually, it is often determined so that the motor winding temperature does not exceed the specification value of the operating temperature according to the condition where the load is the highest. However, if the flow rate is adjusted to the condition with the highest load, the temperature of the motor winding does not rise under the condition of low load such as low air temperature, so that the flow rate becomes excessive. In the first place, the purpose of liquid injection is to cool the motor winding, but as the flow rate of the liquid phase refrigerant increases, the efficiency of the compressor decreases and the power consumption increases, so if the flow rate is higher than necessary, it becomes an inefficient refrigeration circuit. Become. It is more efficient to change the flow rate of the liquid phase refrigerant according to the load fluctuation.

As a means for changing the flow rate of the liquid phase refrigerant according to the load fluctuation, a method of providing a solenoid valve, a relay, or the like in the liquid injection circuit and opening and closing under certain conditions is often used. For example, the temperature of the discharge pipe of the compressor or the compressor is detected by a thermostat, and when a temperature higher than a certain temperature is detected, the solenoid valve is opened to increase the flow rate (see, for example, Patent Document 1). It is also possible to have a plurality of liquid injection circuits in parallel, set conditions for each circuit, and finely change the flow rate.

Japanese Unexamined Patent Publication No. 2015-81698

However, the above-mentioned method requires a solenoid valve, a relay, a thermostat, and the like, which increases the number of parts. As the number of parts increases, the cost increases.
This specification discloses a technique capable of changing the flow rate of the liquid phase refrigerant flowing in the liquid injection circuit according to the load fluctuation while suppressing the increase in the number of parts.

(1) The cooling storage disclosed in the present specification is a refrigerating circuit in which a compressor, a condenser, an expanding component and an evaporator are circulated and connected by piping, and the condenser and the expanding component are connected to each other. The liquid injection circuit is provided with a liquid injection circuit branched from the pipe and connected to the compressor, and the liquid injection circuit branches from the pipe connecting the condenser and the expansion component and rises upward. It has a branch pipe and a plurality of capillary tubes connected to the branch pipe, and the height of the connection position of each of the capillary tubes is different.

The above liquid injection circuit operates as follows by appropriately setting the height of the connection position of each capillary tube.
(Action 1) Normally, when the load on the compressor is high, the pressure of the liquid phase refrigerant increases accordingly. When the pressure of the liquid phase refrigerant increases, the liquid phase refrigerant rises to the height of the capillary tube having a high connection position, and the liquid phase refrigerant flows from the plurality of capillary tubes to the compressor together with the capillary tube having a low connection position.
(Action 2) When the load on the compressor is low, the pressure of the liquid-phase refrigerant is low, so the liquid-phase refrigerant does not rise to the height of the capillary tube with a high connection position, and the liquid-phase refrigerant is released only from the capillary tube with a low connection position. It flows. Therefore, the flow rate of the liquid phase refrigerant is suppressed.
(Action 3) When the pressure is further lowered, the liquid phase refrigerant does not rise even at the height of the capillary tube where the connection position is low, and the flow rate of the liquid phase refrigerant becomes almost zero.

Therefore, according to the above-mentioned cooling storage, the flow rate of the liquid phase refrigerant flowing in the liquid injection circuit can be changed according to the load fluctuation while suppressing the increase in the number of parts, even if the solenoid valve, the relay, the thermostat, etc. are not provided. Can be done. As a result, the cost can be suppressed and the efficiency can be improved.

(2) The cooling storage disclosed in the present specification is a refrigerating circuit in which a compressor, a condenser, an expanding component and an evaporator are circulated and connected by piping, and the condenser and the expanding component are connected to each other. The liquid injection circuit is provided with a liquid injection circuit branched from the pipe and connected to the compressor, and the liquid injection circuit branches from the pipe connecting the condenser and the expansion component and rises upward. The upper pipe, the lower pipe branching from the pipe and extending downward, the first capillary tube connected to the upper pipe, and the second capillary connected to the lower pipe. Has a tube.

The above liquid injection circuit operates as follows by appropriately setting the height of the connection position of the first capillary tube.
(Action 1) Normally, when the load on the compressor is high, the pressure of the liquid phase refrigerant increases accordingly. When the pressure of the liquid phase refrigerant increases, the liquid phase refrigerant rises to the height of the first capillary tube connected to the upper pipe, and both capillary tubes together with the second capillary tube connected to the lower pipe. Liquid phase refrigerant flows from the compressor.
(Action 2) When the load on the compressor is low, the pressure of the liquid phase refrigerant is low, so the liquid phase refrigerant does not rise to the height of the first capillary tube connected to the upper pipe and is connected to the lower pipe. It flows only from the second capillary tube. Therefore, the flow rate of the liquid phase refrigerant is suppressed.

Therefore, according to the above-mentioned cooling storage, the flow rate of the liquid phase refrigerant flowing in the liquid injection circuit can be changed according to the load fluctuation while suppressing the increase in the number of parts, even if the solenoid valve, the relay, the thermostat, etc. are not provided. Can be done. As a result, the cost can be suppressed and the efficiency can be improved.

(3) The cooling storage disclosed in the present specification is a refrigerating circuit in which a compressor, a condenser, an expanding component and an evaporator are circulated and connected by piping, and the condenser and the expanding component are connected to each other. The liquid injection circuit is provided with a liquid injection circuit branched from the pipe and connected to the compressor, and the liquid injection circuit branches from the pipe connecting the condenser and the expansion component and rises upward. It has a plurality of branch pipes provided apart from each other in the flow direction of the refrigerant, and a capillary tube connected to each of the branch pipes.

The above liquid injection circuit operates as follows by appropriately setting the position of each branch pipe in the flow direction of the refrigerant.
(Action 1) Since the liquid-phase refrigerant flowing between the condenser and the expanding component gradually changes to a gas-phase refrigerant depending on the outside air temperature transmitted through the piping, the pressure of the liquid-phase refrigerant increases toward the downstream side in the flow direction of the refrigerant. descend. However, when the load on the compressor is high, the pressure of the liquid phase refrigerant increases accordingly, so even if a part of the liquid phase refrigerant changes to the gas phase refrigerant and the pressure drops, it is provided on the downstream side. The liquid-phase refrigerant rises to the height of the capillary tube connected to the branch pipe, and the liquid-phase refrigerant flows from the plurality of capillary tubes to the compressor together with the upstream side.
(Action 2) When the load on the compressor is low, the pressure of the liquid phase refrigerant is low, so the liquid phase refrigerant does not rise to the height of the capillary tube connected to the branch pipe on the downstream side, and the liquid phase refrigerant does not rise to the branch pipe on the upstream side. The liquid phase refrigerant flows only from the connected capillary tube. Therefore, the flow rate of the liquid phase refrigerant is suppressed.

Therefore, according to the above-mentioned cooling storage, the flow rate of the liquid phase refrigerant flowing in the liquid injection circuit can be changed according to the load fluctuation while suppressing the increase in the number of parts, even if the solenoid valve, the relay, the thermostat, etc. are not provided. Can be done. As a result, the cost can be suppressed and the efficiency can be improved.

(4) It may be connected to the branch pipe at a position as low as the capillary tube connected to the branch pipe on the downstream side in the flow direction of the refrigerant.

Since the pressure of the liquid phase refrigerant decreases toward the downstream side, if the height of the capillary tube on the upstream side and the capillary tube on the downstream side are the same, the liquid phase refrigerant is provided on the downstream side even if the pressure of the liquid phase refrigerant is high. The liquid-phase refrigerant may not rise to the height of the capillary tube connected to the branch pipe.
According to the above-mentioned cooling storage, the capillary tube connected to the branch pipe on the downstream side is connected to the branch pipe at a lower position, so that the height of the capillary tube connected to the branch pipe provided on the downstream side is high. The liquid phase refrigerant tends to rise. Therefore, when the pressure of the liquid phase refrigerant is high, the liquid phase refrigerant can be surely flowed by the capillary tube connected to the branch pipe provided on the downstream side.

(5) The cooling storage disclosed in the present specification is a refrigerating circuit in which a compressor, a condenser, an expansion component and an evaporator are circulated and connected by piping, and the condenser and the expansion component are connected to each other. A liquid injection circuit that is branched from a pipe and is connected to the compressor, and includes a liquid injection circuit having a capillary tube, a heating unit that heats the capillary tube, and a control unit. , The energization to the heating unit is controlled according to the load of the compressor.

When the capillary tube is overheated, the liquid-phase refrigerant expands in the capillary tube and changes to a gas-phase refrigerant, so that the flow rate of the liquid-phase refrigerant is suppressed.
According to the above-mentioned cooling storage, the energization of the heating part is controlled according to the load of the compressor, so the flow rate of the liquid-phase refrigerant flowing in the liquid injection circuit can be adjusted without providing a solenoid valve, relay, thermostat, etc. It can be changed according to the load fluctuation while suppressing the increase in the score. As a result, the cost can be suppressed and the efficiency can be improved.

(6) The compressor is a compressor having a variable rotation speed, and the control unit may control energization of the heating unit according to the rotation speed of the compressor.

In a compressor with a variable rotation speed, the rotation speed (rotation speed per unit time) is controlled according to the temperature inside the refrigerator. The compressor has a high load when the rotation speed is high, and a low load when the rotation speed is low. Therefore, by controlling the energization of the heating unit according to the rotation speed of the compressor, the flow rate of the liquid phase refrigerant can be changed according to the load fluctuation. As a result, the cost can be suppressed and the efficiency can be improved.

(7) The refrigerator is provided with an internal temperature sensor for detecting the internal temperature, the compressor is a compressor having a constant rotation speed, and the control unit stops the compressor when the internal temperature drops to the lower limit temperature. After that, when the temperature inside the refrigerator rises to the upper limit temperature, the operation of the compressor is restarted to execute a cooling operation for maintaining the temperature inside the refrigerator between the upper limit temperature and the lower limit temperature. The heating unit may be energized during the period from the decrease to the lower limit temperature to the increase to the upper limit temperature.

Since the compressor is stopped during the period from when the internal temperature drops to the lower limit temperature to when it rises to the upper limit temperature, the load on the compressor is low. Therefore, it is desirable to suppress the flow rate of the liquid phase refrigerant during this period. According to the above-mentioned cooling storage, since the heating unit is energized during the period from when the internal temperature drops to the lower limit temperature to when it rises to the upper limit temperature, the flow rate of the liquid phase refrigerant can be suppressed. On the other hand, since the compressor is operated during the period from when the temperature inside the refrigerator rises to the upper limit temperature to when it falls to the lower limit temperature, the load on the compressor increases. Therefore, it is desirable not to suppress the flow rate of the liquid phase refrigerant during this period. According to the above-mentioned cooling storage, the heating unit is not energized during the period from when the temperature inside the storage rises to the upper limit temperature to when it falls to the lower limit temperature, so that the flow rate of the liquid phase refrigerant can be prevented from being suppressed. As described above, according to the above-mentioned cooling storage, the flow rate of the liquid phase refrigerant can be changed according to the load fluctuation.

(8) An outside air temperature sensor for detecting the outside air temperature may be provided, and the control unit may control energization of the heating unit according to the outside air temperature.

When the outside air temperature is high, the temperature inside the refrigerator also rises, so the load on the compressor increases. On the other hand, when the outside air temperature is low, the load on the compressor is low. According to the above-mentioned cooling storage, since the energization of the heating unit is controlled according to the outside air temperature, the flow rate can be changed according to the load fluctuation. In general, the cooling storage is often equipped with an outside air temperature sensor that detects the outside air temperature. In the case of a cooling storage equipped with an outside air temperature sensor, the flow rate can be changed according to load fluctuations by using the outside air temperature sensor without providing a solenoid valve, a relay, a thermostat, or the like. As a result, the cost can be suppressed and the efficiency can be improved.

The invention disclosed herein can be realized in various aspects such as a device, a method, a computer program for realizing the function of these devices or methods, a recording medium on which the computer program is recorded, and the like.

Sectional drawing of the closed showcase according to Embodiment 1. Block diagram of refrigeration circuit Block diagram showing the electrical configuration of a closed showcase Schematic diagram of liquid injection circuit Schematic diagram of the liquid injection circuit according to the second embodiment Schematic diagram of the liquid injection circuit according to the third embodiment Block diagram of the refrigeration circuit according to the second embodiment

<Embodiment 1>
The first embodiment will be described with reference to FIGS. 1 to 4. In the following description, the reference numerals of the drawings may be omitted for the same components except for some parts.

(1) Configuration of Closed Showcase As shown in FIG. 1, the closed showcase 1 as a cooling storage according to the first embodiment has a storage main body 11 and a storage main body 11 composed of a heat insulating box whose front side is open. It is provided with a pair of left and right double-door glass doors 13 that open and close the opening on the front side of the door, and a machine room 12 provided below the storage body 11. The machine room 12 houses a refrigerating circuit 30 (see FIG. 2) for cooling the inside of the storage main body 11, a control unit 50 (see FIG. 3), a power supply unit (not shown), and the like. An operation unit 51 is provided on the front surface of the machine room 12.

(2) Refrigeration circuit As shown in FIG. 2, the refrigeration circuit 30 includes an inverter compressor 31 (an example of a compressor having a variable rotation speed), a condenser 32, a dryer 33, a heat exchange section 34, and an expansion valve 36 (expansion parts). (Example), an evaporator 37 and an accumulator 38 are provided, and these are circulated and connected by pipes 39 (pipes 39A to 39D) in this order. The evaporator 37 is arranged not in the machine room 12 but in the storage main body 11. The refrigeration circuit 30 may include a capillary tube instead of the expansion valve 36.

The heat exchange section 34 is adjacent to a part of the pipe 39B connecting the condenser 32 and the expansion valve 36 and a part of the pipe 39D connecting the evaporator 37 and the inverter compressor 31. It is a section that extends in parallel. The heat exchange section is provided for the purpose of preventing the return of flash gas and low-pressure refrigerant.

Further, the refrigerating circuit 30 includes a liquid injection circuit 40 for cooling the inverter compressor 31 when the load of the inverter compressor 31 is high, and an internal fan 18 (see FIG. 3) that circulates the air cooled by the evaporator 37 in the refrigerator. ), A condenser fan 41 (see FIG. 3) for cooling the condenser 32, and the like are also provided. The liquid injection circuit 40 will be described later.

(2) Electrical Configuration of Closed Showcase As shown in FIG. 3, the closed showcase 1 includes a control unit 50, an operation unit 51, and the like.
The control unit 50 includes a microcomputer 50A, a ROM 50B, and the like in which a CPU, RAM, and the like are integrated into a single chip. The ROM 50B stores a control program and various data for controlling the closed showcase 1. An operation unit 51, an inverter compressor 31, an internal fan 18, a condenser fan 41, an internal temperature sensor 20, an outside air temperature sensor 42 for detecting the outside air temperature, and the like are connected to the control unit 50. The control unit 50 controls each unit of the closed showcase 1 by executing a control program stored in the ROM 50B.

The operation unit 51 includes a display unit for displaying the temperature inside the refrigerator, various operation buttons, and the like. The user of the closed showcase 1 can perform various operations such as setting the target temperature in the refrigerator by operating the operation buttons. In the following description, the set target temperature is referred to as the set temperature.

(3) Cooling Operation The cooling operation executed by the control unit 50 will be schematically described. Here, a temperature higher than the set temperature by a predetermined temperature (for example, 1.7 K [Kelvin]) is referred to as an upper limit temperature, and a temperature lower than the set temperature by a predetermined temperature (for example, 2.0 K) is referred to as a lower limit temperature. The temperature range higher than the upper limit temperature is called the pull-down area, and the temperature range from the upper limit temperature to the lower limit temperature is called the control area.

Normally, when the power of the closed showcase 1 is turned on, the temperature inside the refrigerator is higher than the upper limit temperature. The control unit 50 controls the rotation speed of the inverter compressor 31 so that when the temperature inside the refrigerator is higher than the upper limit temperature, the temperature inside the refrigerator drops along the target temperature curve in the pull-down region. Specifically, the control unit 50 increases the rotation speed of the inverter compressor 31 when the internal temperature is higher than the target temperature curve, and increases the rotation speed of the inverter compressor 31 when the internal temperature is lower than the target temperature curve. To lower. When the rotation speed of the inverter compressor 31 is increased, the load of the inverter compressor 31 becomes high, and when the rotation speed is decreased, the load of the inverter compressor 31 becomes low.

The control unit 50 controls the rotation speed of the inverter compressor 31 so that when the temperature inside the refrigerator drops to the upper limit temperature, the temperature drops along the target temperature curve in the control region. The target temperature curve in the control region is a curve that is gentler than the target temperature curve in the pull-down region, and is set as a curve that extends parallel to the time axis after the temperature inside the refrigerator drops to the set temperature.

(4) Liquid injection circuit As shown in FIG. 4, the liquid injection circuit 40 branches from between the condenser 32 and the heat exchange section 34 in the pipe 39B connecting the condenser 32 and the expansion valve 36. It has a branch pipe 60 and two capillary tubes 61 (first capillary tube 61A and second capillary tube 61B) connected to the branch pipe 60.

The branch pipe 60 consists of a vertical portion 60A rising vertically upward from the pipe 39B and two horizontal portions (first horizontal portion 60B and second horizontal portion 60C) vertically separated from the vertical portion 60A and extending in the horizontal direction. ) And.

The first capillary tube 61A is connected to the first horizontal portion 60B, and the second capillary tube 61B is connected to the second horizontal portion 60C. As shown in FIG. 2, the first capillary tube 61A and the second capillary tube 61B merge on the opposite side to the side connected to the branch pipe 60 to form one capillary tube. The first capillary tube 61A and the second capillary tube 61C do not necessarily have to merge.

As shown in FIG. 4, the height of the connection position connected to the branch pipe 60 is different between the first capillary tube 61A and the second capillary tube 61B. Specifically, the first capillary tube 61A is connected to the branch pipe 60 at a position higher than that of the second capillary tube 61B. The height of the connection position of the first capillary tube 61A and the second capillary tube 61B is set so as to act as follows.

(Action 1) Normally, when the load of the inverter compressor 31 is high, the pressure of the liquid phase refrigerant increases accordingly. When the pressure of the liquid phase refrigerant increases, the liquid phase refrigerant rises to the height of the first capillary tube 61A, which is a capillary tube having a high connection position, and both together with the second capillary tube 61B, which is a capillary tube having a low connection position. The liquid-phase refrigerant flows from the capillary tube 61 of the above to the inverter compressor 31.
(Action 2) When the load of the inverter compressor 31 is low, the pressure of the liquid phase refrigerant is low, so that the liquid phase refrigerant does not rise to the height of the first capillary tube 61A, and the liquid phase starts only from the second capillary tube 61B. Refrigerant flows. Therefore, the flow rate of the liquid phase refrigerant is suppressed.
(Action 3) When the pressure is further lowered, the liquid phase refrigerant does not rise to the height of the second capillary tube 61B, and the flow rate of the liquid phase refrigerant becomes almost zero.

The height of the connection position of the first capillary tube 61A and the second capillary tube 61B that operate as described above can be experimentally determined for each refrigeration circuit 30.

(5) Effect of the Embodiment According to the closed showcase 1, the flow rate of the liquid phase refrigerant flowing through the liquid injection circuit 40 can be changed according to the load fluctuation even if the solenoid valve, the relay, the thermostat, or the like is not provided. As a result, the cost can be suppressed and the cooling efficiency can be improved.

<Embodiment 2>
As shown in FIG. 5, the liquid injection circuit 240 according to the second embodiment has an L-shaped upper pipe 260A that branches from between the condenser 32 and the heat exchange section 34 and rises upward in the vertical direction, and a vertical pipe 260A. An L-shaped lower pipe 260B extending downward in the direction, a first capillary tube 261A connected to the upper pipe 260A, and a second capillary tube 261B connected to the lower pipe 260B. I have.

The first capillary tube 261A and the second capillary tube 261B merge on the opposite side to the side connected to the branch pipe 60 to form one capillary tube. The first capillary tube 261A and the second capillary tube 261B do not necessarily have to merge.

The height of the connection position of the first capillary tube 261A is set so as to operate as follows.
(Action 1) Normally, when the load of the inverter compressor 31 is high, the pressure of the liquid phase refrigerant increases accordingly. When the pressure of the liquid phase refrigerant increases, the liquid phase refrigerant rises to the height of the first capillary tube 261A connected to the upper pipe 260A, and together with the second capillary tube 261B connected to the lower pipe 260B. The liquid phase refrigerant flows from both capillary tubes 261 to the inverter compressor 31.
(Action 2) When the load of the inverter compressor 31 is low, the pressure of the liquid phase refrigerant is low, so that the liquid phase refrigerant does not rise to the height of the first capillary tube 261A connected to the upper pipe 260A, and the liquid phase refrigerant does not rise to the lower side. It flows only from the second capillary tube 261B connected to the pipe 260B. Therefore, the flow rate of the liquid phase refrigerant is suppressed.

The height of the connection position of the first capillary tube 261A that operates as described above can be experimentally determined for each refrigeration circuit 30.

According to the closed showcase 1 according to the second embodiment, the flow rate of the liquid phase refrigerant flowing through the liquid injection circuit 240 can be changed according to the load fluctuation even if the solenoid valve, the relay, the thermostat, and the like are not provided. As a result, the cost can be suppressed and the efficiency can be improved.

<Embodiment 3>
As shown in FIG. 6, the liquid injection circuit 340 according to the third embodiment has two L-shaped branch pipes 360 (upstream side) that branch from between the condenser 32 and the heat exchange section 34 and rise upward. (Branch pipe 360A and downstream branch pipe 360B), two branch pipes 360 provided apart from each other in the flow direction of the refrigerant, and capillary tubes 361 connected to the respective branch pipes 360A and 360B. (Upstream side capillary tube 361A and upstream side capillary tube 361B) are provided.

The upstream side capillary tube 361A and the downstream side capillary tube 361B are connected to the branch pipe 360 at a position lower than the capillary tube connected to the downstream side branch pipe 360 in the refrigerant flow direction. Specifically, the capillary tube 361B on the downstream side is connected to the branch pipe 360B at a position lower than the capillary tube 361A on the upstream side.
The upstream side capillary tube 361A and the downstream side capillary tube 361B are combined into one capillary tube on the side opposite to the side connected to the branch pipe 360. These capillary tubes 361 do not necessarily have to merge.

The position of the branch pipe 360A on the upstream side and the branch pipe 360B on the downstream side in the flow direction of the refrigerant is set so as to operate as follows.
(Action 1) Since the liquid-phase refrigerant flowing between the condenser 32 and the heat exchange section 34 gradually changes to a gas-phase refrigerant depending on the outside temperature transmitted through the pipe 39, the liquid phase is closer to the downstream side in the flow direction of the refrigerant. Refrigerant pressure drops. However, normally, when the load of the inverter compressor 31 is high, the pressure of the liquid phase refrigerant increases accordingly, so that a part of the liquid phase refrigerant flowing between the condenser 32 and the heat exchange section 34 is a vapor phase refrigerant. Even if the pressure drops, the liquid-phase refrigerant rises to the height of the capillary tube 361B on the downstream side, and the refrigerant flows from the two capillary tubes 361 together with the capillary tube 361A on the upstream side to the inverter compressor 31. ..
(Action 2) When the load of the inverter compressor 31 is low, the pressure of the liquid phase refrigerant is low, so that the liquid phase refrigerant does not rise to the height of the capillary tube 361B on the downstream side, and the liquid phase starts only from the capillary tube 361A on the upstream side. Refrigerant flows. Therefore, the flow rate of the liquid phase refrigerant is suppressed.

The longer the distance between the branch pipe 360A on the upstream side and the branch pipe 360B on the downstream side, the more likely it is that a pressure difference will occur. Therefore, by setting this distance according to the refrigeration circuit 30, a highly efficient circuit should be designed. Can be done.

According to the closed showcase 1 according to the third embodiment, the flow rate of the liquid phase refrigerant flowing through the liquid injection circuit 340 can be changed according to the load fluctuation even if the solenoid valve, the relay, the thermostat, and the like are not provided. As a result, the cost can be suppressed and the efficiency can be improved.

According to the closed showcase 1 according to the third embodiment, since the downstream capillary tube 361B is connected to the branch pipe 360B at a position lower than the upstream capillary tube 361A, the liquid phase reaches the height of the downstream capillary tube 361B. The refrigerant tends to rise. Therefore, when the pressure of the liquid phase refrigerant is high, the liquid phase refrigerant can be surely flowed by the capillary tube 361B on the downstream side.

<Embodiment 4>
The refrigeration circuit 430 according to the fourth embodiment will be described with reference to FIG. 7. As shown in FIG. 7, the liquid injection circuit 440 of the refrigeration circuit 430 according to the fourth embodiment has only one capillary tube 461, and a heater 80 (an example of a heating unit) is provided along the capillary tube 461. The heater 80 is attached directly to the capillary tube 461 or from above the capillary tube 461 covered with another component.

The compressor 431 according to the fourth embodiment may be an inverter compressor or a compressor having a constant rotation speed. Since the cooling operation in the case of the inverter compressor has been described in the first embodiment, the description is omitted here, and the cooling operation in the case of the compressor having a constant rotation speed will be described.

When the power of the closed showcase 1 is turned on, the control unit 50 rotates the compressor 431. When the compressor 431 is rotated, the temperature inside the refrigerator drops. The control unit 50 stops the compressor 431 when the temperature inside the refrigerator drops to the lower limit temperature. When the compressor 431 is stopped, the temperature inside the refrigerator rises. After stopping the compressor 431, the control unit 50 restarts the operation of the compressor 431 when the temperature inside the refrigerator rises to the upper limit temperature. By repeating this, the temperature inside the refrigerator is generally maintained within the control region. In the following description, the period from when the temperature inside the refrigerator drops to the lower limit temperature to when it rises to the upper limit temperature is referred to as a shutdown period of the compressor 431.

When the capillary tube 461 is overheated by the heater 80, the liquid phase refrigerant returning to the compressor 431 evaporates, so that the flow rate of the liquid phase refrigerant returning to the compressor 431 is suppressed. Therefore, the control unit 50 controls the energization of the heater 80 as follows.

(Control 1) When the load of the compressor 431 is high, it is necessary to return a larger amount of the liquid phase refrigerant to the compressor 431 for cooling. Therefore, the control unit 50 does not energize the heater 80 when the load of the compressor 431 is high. Therefore, the flow rate of the liquid phase refrigerant increases as compared with the case where the heater 80 is energized.

(Control 2) If the liquid phase refrigerant is returned when the load of the compressor 431 is low, the cooling efficiency is lowered. Therefore, the control unit 50 energizes the heater 80 when the load of the compressor 431 is low. Therefore, the flow rate of the liquid phase refrigerant is suppressed as compared with the case where the heater 80 is not energized, and the deterioration of the cooling efficiency is suppressed.

The above-mentioned control will be described more specifically. First, a case where the compressor 431 is a compressor having a constant rotation speed will be described. As the outside air temperature of the closed showcase 1 becomes lower, the inside of the closed showcase 1 becomes colder, so that the above-mentioned stop period becomes longer. When the stop period is long, the load on the compressor 431 is low. On the contrary, when the stop period is short, the load of the compressor 431 is high. Therefore, the control unit 50 sets the stop period of the compressor 431 as the heating time of the capillary tube 461 by the heater 80. That is, the heater 80 is energized during the stop period, and the heater 80 is de-energized during the period other than the stop period (in other words, the operating period of the compressor 431). Since the stop period fluctuates according to the load, the flow rate of the liquid phase refrigerant can be changed according to the load fluctuation in this way.

Next, a case where the compressor 431 is an inverter compressor will be described. When the compressor 431 is an inverter compressor, the control unit 50 controls energization of the heater according to the rotation speed of the compressor 431. Specifically, the control unit 50 energizes the heater 80 when the rotation speed of the inverter compressor is lower than the predetermined rotation speed (that is, when the load is low), and when the rotation speed is higher than the predetermined rotation speed (that is, the load is high). When) is not energized. The predetermined rotation speed can be appropriately determined. As a result, the flow rate of the liquid phase refrigerant can be changed according to the load fluctuation.

According to the closed showcase 1 according to the fourth embodiment, the flow rate of the liquid phase refrigerant flowing through the liquid injection circuit 440 can be changed according to the load fluctuation even if the solenoid valve, the relay, the thermostat, and the like are not provided. As a result, the cost can be suppressed and the efficiency can be improved.

According to the closed showcase 1 according to the fourth embodiment, in the case of the inverter compressor 31 (compressor having a variable rotation speed), the energization of the heater 80 is controlled according to the rotation speed of the inverter compressor 31, so that the load is applied. The flow rate can be changed according to the fluctuation. As a result, the cost can be suppressed and the efficiency can be improved.

According to the closed showcase 1 according to the fourth embodiment, in the case of a compressor having a constant rotation speed, the heater 80 is energized during a stop period from when the internal temperature drops to the lower limit temperature to when it rises to the upper limit temperature. When the stop period is long, the load of the compressor is low, and when the stop period is short, the load of the compressor is high. Therefore, if the heater 80 is energized during the stop period, the flow rate can be changed according to the load fluctuation. As a result, the cost can be suppressed and the efficiency can be improved.

<Other embodiments>
The technology disclosed herein is not limited to the embodiments described above and in the drawings, and for example, the following embodiments are also included in the technical scope disclosed herein.

(1) In the first embodiment, two capillary tubes 61 have been described as an example as a plurality of expansion parts connected to the branch pipe, but the number of the capillary tubes 61 is not limited to two, and three. It may be the above.

(2) In the second embodiment, the case where the upper pipe 260A rises upward from the pipe 39B and the position where the lower pipe 260B extends downward from the pipe 39B are the same. These do not necessarily have to be the same. For example, the lower pipe 260B may extend downward from a position on the upstream side as compared with the upper pipe 260A, or may extend downward from a position on the downstream side.

(3) Although two branch pipes have been described as an example of the plurality of branch pipes in the third embodiment, the number of branch pipes is not limited to two, and may be three or more.

(4) In the third embodiment, the case where the capillary tube is connected to the branch pipe at a lower position than the capillary tube connected to the branch pipe on the downstream side in the flow direction of the refrigerant has been described as an example, but all the capillary tubes are the same. It may be connected to the branch pipe at height.

(5) In the above-described first to third embodiments, the case where the branch pipe stands up vertically has been described as an example, but the branch pipe does not necessarily have to stand up vertically, for example, even if the branch pipe stands up diagonally. Good. Further, the branch pipe extending to the lower side of the second embodiment does not necessarily have to extend vertically downward, and may extend diagonally downward, for example.

(6) In the fourth embodiment, in the case of the inverter compressor, the energization of the heater 80 is controlled according to the rotation speed, and in the case of the compressor having a constant rotation speed, the heater 80 is energized during the stop period. The flow rate of the liquid phase refrigerant is controlled according to the load fluctuation. On the other hand, when the outside air temperature is high, the temperature inside the refrigerator is high, so that the load on the compressor is high. Therefore, the energization of the heater 80 may be controlled according to the outside air temperature detected by the outside air temperature sensor 42. In this way, the flow rate can be changed according to the load fluctuation. Further, in general, the closed showcase 1 is often provided with an outside air temperature sensor 42 for detecting the outside air temperature. In the case of the closed showcase 1 provided with the outside air temperature sensor 42, by using the outside air temperature sensor 42, the flow rate can be changed according to the load fluctuation without providing an electromagnetic valve, a relay, a thermostat, or the like. As a result, the cost can be suppressed and the efficiency can be improved.

(7) In the fourth embodiment, the case where the energization time of the heater 80 is longer when the rotation speed of the inverter compressor is low than when the rotation speed is high has been described as an example. On the other hand, when the rotation speed of the inverter compressor is low, the energization rate of the heater 80 (the ratio of the time for energizing the heater 80 per unit time) may be higher than when the rotation speed is high.

(8) In the fourth embodiment, in the case of a compressor having a constant rotation speed, the heater 80 is always energized during the stop period, but the heater 80 is energized only during a part of the stop period. You may.

(9) In the above embodiment, the case where the refrigeration circuit 30 includes the heat exchange section 34 has been described as an example, but the refrigeration circuit 30 does not necessarily have to include the heat exchange section 34.

(10) In the above embodiment, the closed showcase has been described as an example of the cooling storage, but the cooling storage is not limited to the closed showcase, and may be an open showcase, a refrigerator, a freezer, or the like.

1 ... Closed showcase (an example of cooling storage), 20 ... Internal temperature sensor, 30 ... Refrigeration circuit, 31 ... Inverter compressor (example of compressor), 32 ... Condenser, 34 ... Heat exchange section, 36 ... Expansion Valve (an example of expansion component), 37 ... Evaporator, 39 ... Piping, 40 ... Liquid injection circuit, 42 ... Outside temperature sensor, 50 ... Control unit, 60 ... Branch piping, 61 ... Capillary tube, 80 ... Heater (Heating part) Example), 240 ... liquid injection circuit, 260A ... upper pipe, 260B ... lower pipe, 261A ... first capillary tube, 261B ... second capillary tube, 340 ... liquid injection circuit, 360 ... branch pipe, 361 ... Capillary tube, 430 ... Refrigeration circuit, 431 ... Compressor (an example of a compressor with a constant rotation speed and a compressor with a variable rotation speed), 440 ... Liquid injection circuit, 461 ... Capillary tube

Claims (8)

It ’s a cooling storage,
A refrigeration circuit in which compressors, condensers, expansion parts and evaporators are circulated and connected by piping.
A liquid injection circuit branched from the pipe connecting the condenser and the expansion component and connected to the compressor.
With
The liquid injection circuit has a branch pipe that branches from the pipe that connects the condenser and the expansion component and rises upward, and a plurality of capillary tubes that are connected to the branch pipe. , Cooling storage, where the height of the connection position of each of the capillary tubes is different. It ’s a cooling storage,
A refrigeration circuit in which compressors, condensers, expansion parts and evaporators are circulated and connected by piping.
A liquid injection circuit branched from the pipe connecting the condenser and the expansion component and connected to the compressor.
With
The liquid injection circuit includes an upper pipe that branches from the pipe connecting the condenser and the expansion component and rises upward, and a lower pipe that branches from the pipe and extends downward. A cooling storage having a first capillary tube connected to the upper pipe and a second capillary tube connected to the lower pipe. It ’s a cooling storage,
A refrigeration circuit in which compressors, condensers, expansion parts and evaporators are circulated and connected by piping.
A liquid injection circuit branched from the pipe connecting the condenser and the expansion component and connected to the compressor.
With
The liquid injection circuit is a plurality of branch pipes that branch from the pipe connecting the condenser and the expansion component and rise upward, and are provided apart from each other in the flow direction of the refrigerant. A cooling storage having a plurality of branch pipes and a capillary tube connected to each of the branch pipes. The cooling storage according to claim 3.
A cooling storage that is connected to the branch pipe at a position as low as the capillary tube connected to the branch pipe on the downstream side in the flow direction of the refrigerant. It ’s a cooling storage,
A refrigeration circuit in which compressors, condensers, expansion parts and evaporators are circulated and connected by piping.
A liquid injection circuit branched from the pipe connecting the condenser and the expansion component and connected to the compressor, and a liquid injection circuit having a capillary tube.
The heating part that overheats the capillary tube and
Control unit and
With
The control unit is a cooling storage that controls energization of the heating unit according to the load of the compressor. The cooling storage according to claim 5.
The compressor is a compressor having a variable rotation speed.
The control unit is a cooling storage that controls energization of the heating unit according to the rotation speed of the compressor. The cooling storage according to claim 5.
Equipped with an internal temperature sensor that detects the internal temperature
The compressor is a compressor having a constant rotation speed.
The control unit stops the compressor when the temperature inside the refrigerator drops to the lower limit temperature, and then restarts the operation of the compressor when the temperature inside the refrigerator rises to the upper limit temperature, thereby setting the temperature inside the refrigerator as the upper limit temperature. A cooling storage that carries out a cooling operation that is maintained between the lower limit temperature and energizes the heating unit during the period from when the temperature inside the refrigerator drops to the lower limit temperature to when it rises to the upper limit temperature. The cooling storage according to claim 5.
Equipped with an outside air temperature sensor that detects the outside air temperature
The control unit is a cooling storage that controls energization of the heating unit according to the outside air temperature.

Images