JP2021042881A - Cooling storage - Google Patents

Abstract

To provide a cooling storage capable of realizing an injection circuit in which a liquid-phase refrigerant flows to a compressor in overheat of the compressor and a gas-phase refrigerant flows in non-overheat of the compressor, while suppressing the number of components.SOLUTION: A closed showcase comprises: a refrigeration circuit 30 in which an invertor compressor 31, a condenser 32, an expansion valve 36 and an evaporator 37 are connected by piping 39 in a circulating manner; and an injection circuit 40 branched from the piping 39 connecting the condenser 32 and the expansion valve 36, and connected to the invertor compressor 31. The injection circuit 40 is branched from the piping 39 at a position where a refrigerant flowing from the condenser 32 to the invertor compressor 31 through the injection circuit 40, has a liquid-phase state in a high load where a rotating speed of the invertor compressor 31 is a prescribed rotating speed or more, and has a gas-phase state in a low load of less than the prescribed rotating speed, between the condenser 32 and the expansion valve 36.SELECTED DRAWING: Figure 2

Description

The techniques disclosed herein relate to refrigerated storage.

In a refrigeration circuit in which a compressor with a variable rotation speed, a condenser, an expansion component, and an evaporator are circulated and connected by piping, it is known to have an injection circuit that sends a refrigerant between the condenser and the expansion component to the compressor. Has been done. The injection circuit is a circuit that cools the motor of the compressor by sending a high-pressure liquid-phase refrigerant into the cylinder of the compressor and lowering the temperature of the discharge gas of the compressor by the latent heat of vaporization of the liquid-phase refrigerant (for example, patent). Reference 1).

Japanese Unexamined Patent Publication No. 2015-81698

The conventional injection circuit uses a capillary tube as an expansion component for injection, and controls whether or not a refrigerant flows through the injection circuit by opening and closing a solenoid valve provided in front of the capillary tube. Specifically, the temperature detected by the discharge pipe thermostat arranged in the pipe (compressor discharge pipe) connected to the outlet side of the compressor and the opening / closing of the solenoid valve are linked, and the compressor discharge pipe When the temperature rises above a certain value, the solenoid valve opens. When the solenoid valve is opened, the refrigerant flows from the injection circuit to the evaporator, and the compressor is cooled. When the temperature of the compressor discharge pipe falls below a certain value, the solenoid valve closes. When the solenoid valve is closed, the injection circuit is cut off and the compressor cooling stops.

In a refrigeration circuit that uses a compressor having a variable rotation speed as the compressor, the rotation speed per unit time of the compressor (hereinafter, simply referred to as "rotation speed") is controlled by a control unit. The control unit detects the temperature inside the refrigerator and controls the rotation speed of the compressor according to the detected temperature. When the rotation speed of the compressor is high, the cooling power for cooling the inside of the refrigerator is large, and when the rotation speed of the compressor is low, the cooling power is small. For example, when the door of the cooling storage is opened and closed, when the stored items are stored in the storage, or when the ambient temperature is high, the compressor is operated at a high speed. On the contrary, when the ambient temperature is low, the operation is performed at a low speed. Further, when the compressor is operated at a high speed, the cooling power increases, and at the same time, the temperature of the compressor tends to rise, the amount of refrigerant circulating increases, and the high-pressure pressure tends to rise. However, the high pressure may not fluctuate depending on the ambient temperature and the control of the condenser fan motor.

In a model in which the machine room in which the refrigeration circuit is housed is under the storage (for example, a closed showcase), heat is trapped in the machine room, so that the ambient temperature of the compressor rises and the temperature of the compressor tends to rise. When the temperature of the compressor rises, the temperature of the compressor discharge pipe rises. When the temperature of the compressor discharge pipe rises, the solenoid valve opens, and the refrigerant flows through the injection circuit to cool the compressor.
The refrigerant at the outlet of the condenser is a high-pressure liquid-phase refrigerant (high-pressure liquid), and the refrigerant in the compressor is a low-pressure vapor-phase refrigerant (low-pressure gas). The injection flow rate is determined by their pressure difference and the line resistance of the injection circuit. Further, if the refrigerant at the inlet of the injection circuit is in the liquid phase state, the refrigerant expands at the outlet of the injection circuit, so that the cooling effect of the compressor can be obtained. Cannot be obtained.

Since the injection circuit uses a part of the liquid phase refrigerant for cooling the compressor itself, the efficiency and cooling power of the compressor are reduced. Further, if injection is performed when the compressor is not overheated, the refrigerant does not evaporate in the compressor, so that there is a possibility of liquid compression. Liquid compression may cause the compressor to break down.

For these reasons, conventionally, as the control of the injection circuit, the control of opening and closing the solenoid valve according to the temperature detected by the discharge pipe thermostat described above has been performed. However, there is a problem that the number of parts increases when the solenoid valve and the discharge pipe thermostat are provided.

This specification discloses a technique for realizing an injection circuit in which a liquid phase refrigerant flows through the compressor when the compressor is overheated and a gas phase refrigerant flows when the compressor is not overheated, while suppressing the number of parts.

(1) The cooling storage disclosed in the present specification includes a refrigerating circuit in which a compressor, a condenser, an expansion component, and an evaporator having a variable rotation speed are circulated and connected by a pipe, and the condenser and the expansion component. An injection circuit branched from the connected pipe and connected to the compressor is provided, and the injection circuit has a predetermined number of revolutions of the compressor between the condenser and the expansion component. When the load is high, which is equal to or higher than the predetermined rotation speed, the refrigerant flowing from the condenser to the compressor via the injection circuit is in the liquid phase state, and when the load is lower than the predetermined rotation speed, the refrigerant is in the vapor phase state. A cooling storage that branches off from the pipe.

The inventor of the present application has found that there is a position between the condenser and the expanding component where the refrigerant is in the liquid phase state when the compressor is under heavy load and is in the gas phase state when the load is low.

According to the above cooling storage, the branch position of the branch pipe is the position between the condenser and the expansion component where the refrigerant is in the liquid phase state when the compressor is under heavy load and the refrigerant is in the gas phase state when the load is low. is there. In this way, when the load is high, the liquid phase refrigerant easily flows through the injection circuit, and when the load is low, the vapor phase refrigerant easily flows through the injection circuit. Therefore, when injection is required when the compressor is overheated, the liquid-phase refrigerant flows to cool the compressor, and when injection is not required when the compressor is not overheated, the vapor-phase refrigerant flows to prevent the compressor from being cooled. , It can be realized without using a solenoid valve or a discharge pipe thermostat that controls the opening and closing of the solenoid valve.
Therefore, according to the cooling storage, an injection circuit in which the liquid phase refrigerant flows through the compressor when the compressor is overheated and the vapor phase refrigerant flows when the compressor is not overheated can be realized while suppressing the number of parts.

(2) The injection circuit has a branch pipe branched from between the condenser and the expansion component, and an injection expansion component connected to the branch pipe, and the branch pipe is the branch pipe. The gas-liquid refrigerant may rise upward from the pipe connecting the condenser and the expansion component at an angle capable of separating the gas-liquid refrigerant.

According to the above-mentioned cooling storage, the branch pipe rises upward at an angle that allows the gas-liquid refrigerant to be separated, so that the liquid-phase refrigerant flows more easily into the injection circuit when the load is high, and the gas phase in the injection circuit when the load is low. Refrigerant flows more easily.

(3) The injection circuit has a branch pipe branched from between the condenser and the expansion component, and an injection expansion component connected to the branch pipe, and the condenser and the expansion component are connected to the branch pipe. At the branch position where the branch pipe branches between the parts and the pipe length of the branch pipe, the refrigerant flowing from the condenser to the compressor via the injection circuit is in a liquid phase state at the time of the high load. , The branch position and the pipe length may be in a gas phase state at the time of the low load.

In the case of the configuration (1) described above, the branch position of the branch pipe is limited. However, due to the layout of the components constituting the refrigeration circuit, it may not be possible to branch the injection circuit from a position where the injection circuit is in the liquid phase state when the load is high and the gas phase state is when the load is low.
The inventor of the present application who examined this is a pipe in which the refrigerant flowing from the condenser to the compressor via the injection circuit is in a liquid phase state when the load is high, and is in a gas phase state when the load is low. I found that there was a chief.
According to the above-mentioned cooling storage, the selection range of the branch position is widened by the combination of the branch position of the branch pipe and the pipe length, so that the degree of freedom in designing the injection circuit is improved.

(4) The injection circuit has a branch pipe branched from between the condenser and the expansion component, and an injection expansion component connected to the branch pipe, and the condenser and the expansion component are connected to the branch pipe. At the branch position where the branch pipe branches between the parts and the pipe diameter of the branch pipe, the refrigerant flowing from the condenser to the compressor via the injection circuit is in a liquid phase state at the time of the high load. , The branch position and the pipe diameter may be in a gas phase state at the time of the low load.

In the case of the configuration (1) described above, the branch position of the branch pipe is limited. However, due to the layout of the components constituting the refrigeration circuit, it may not be possible to branch the injection circuit from a position where the injection circuit is in the liquid phase state when the load is high and the gas phase state is when the load is low.
The inventor of the present application who examined this has set the diameter of the branch pipe (in other words, the thickness of the branch pipe) to be low because the refrigerant flowing from the condenser to the compressor via the injection circuit is in a liquid phase state when the load is high. It was found that there is a pipe diameter that is in a gas phase state under load.
According to the above-mentioned cooling storage, the selection range of the branch position is widened by the combination of the branch position of the branch pipe and the pipe diameter, so that the degree of freedom in designing the injection circuit is improved.

(5) The injection circuit has a non-linear branch pipe branched from between the condenser and the expansion component, and an injection expansion component connected to the branch pipe, and has the condensation. The branch position where the branch pipe is branched between the vessel and the expansion component and the shape of the branch pipe are such that when the load is high, the refrigerant flowing from the condenser to the compressor via the injection circuit is a liquid. The branch position and shape may be in the phase state and in the gas phase state at the time of the low load.

In the case of the configuration (1) described above, the branch position of the branch pipe is limited. However, due to the layout of the components constituting the refrigeration circuit, it may not be possible to branch the injection circuit from a position where the injection circuit is in the liquid phase state when the load is high and the gas phase state is when the load is low.
The inventor of the present application who examined this has a shape in which the refrigerant flowing from the condenser to the compressor via the injection circuit is in a liquid phase state when the load is high, and is in a gas phase state when the load is low. I found that there is.
According to the above-mentioned cooling storage, the selection range of the branch position is widened by the combination of the branch position and the shape of the branch pipe, so that the degree of freedom in designing the injection circuit is improved.

The invention disclosed herein can be realized in various aspects such as devices, methods, computer programs for realizing the functions of these devices or methods, recording media on which the computer programs are recorded, and the like.

Perspective view of the closed showcase according to the first embodiment Block diagram of refrigeration circuit Side view showing a part of the pipe connecting the condenser and the expansion component and a part of the injection circuit. Block diagram showing the electrical configuration of a closed showcase Cross-sectional view of thick branch pipe and thin branch pipe A side view showing a part of the pipe connecting the condenser and the expansion component according to the third embodiment and a part of the injection circuit. A side view showing a part of the pipe connecting the condenser and the expansion component according to the fourth embodiment and a part of the injection circuit.

<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 body 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 main 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. 4), 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, a sight glass 35, and an expansion valve. 36 (an example of an expansion component), an evaporator 37 and an accumulator 38 are provided, and these are circulated and connected by pipes 39 (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 34 is provided for the purpose of preventing the return of the flash gas or the low-pressure refrigerant. The sight glass 35 is installed in the middle of the pipe 39B, and is an instrument for observing the state of the refrigerant by directly visually observing the refrigerant passing through the pipe 39. You don't have to have sight glasses.

Further, the refrigerating circuit 30 includes an injection circuit 40 for cooling the inverter compressor 31 when the load of the inverter compressor 31 is high, and an internal fan 18 for circulating the air cooled by the evaporator 37 (see FIG. 4). , A condenser fan 41 (see FIG. 4) for cooling the condenser 32 and the like are also provided.

As shown in FIG. 3, the injection circuit 40 is branched from the branch pipe 40A branching 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 capillary tube 40B (an example of an injection expansion component) connected to the pipe 40A. One end of the capillary tube 40B is connected to the branch pipe 40A, and the other end is connected to the inverter compressor 31. The expansion component for injection is not limited to the capillary tube 40B, and may be, for example, an expansion valve 36.
The branch pipe 40A extends upward from the pipe 39B at an angle capable of separating the gas-liquid refrigerant. Specifically, the branch pipe 40A according to the first embodiment extends vertically upward.

(3) Electrical Configuration of Closed Showcase As shown in FIG. 4, 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 for controlling the closed showcase 1 and various data. An operation unit 51, an inverter compressor 31, an internal fan 18, a condenser fan 41, an internal temperature sensor 20, 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.

(4) Characteristics of the refrigeration circuit and branch position of the branch pipe First, the characteristics of the refrigeration circuit 30 will be described.
(Characteristic 1) The inverter compressor 31 does not overheat when the load is low, but overheats when it operates at high speed with a large amount of work.
(Characteristic 2) The refrigerant becomes a liquid-phase refrigerant at the outlet of the condenser 32, and re-evaporates to become a gas-liquid mixed refrigerant in front of the heat exchange section 34 because it is affected by the ambient temperature in the pipe 39B in the middle. From the outlet of the condenser 32 to the heat exchange section 34, the closer to the heat exchange section 34, the larger the proportion of the vapor phase refrigerant.
(Characteristic 3) When the load of the inverter compressor 31 is low, the operation is low speed and the amount of refrigerant circulation is reduced. When the amount of refrigerant circulation decreases, the speed of the refrigerant in the pipe 39 slows down, so that the heat exchange time with the ambient temperature becomes long. Therefore, the proportion of the vapor phase refrigerant becomes higher in front of the heat exchange section 34.
(Characteristic 4) When the refrigerant speed is slow, the refrigerant in the pipe 39 is in a laminar flow state, the liquid-phase refrigerant is located on the lower side in the pipe 39 due to gravity, and the vapor-phase refrigerant is located on the upper side in the pipe 39.
(Characteristic 5) When the load of the inverter compressor 31 is high, the operation becomes high speed and the amount of refrigerant circulation increases. As the amount of refrigerant circulation increases, the speed of the refrigerant in the pipe 39 increases, so that the heat exchange time with the ambient temperature becomes shorter. Therefore, the proportion of the vapor phase refrigerant becomes lower in front of the heat exchange section 34.
(Characteristic 6) When the refrigerant speed is high, the refrigerant in the pipe 39 is in a turbulent flow state, and the liquid phase refrigerant is located on the pipe wall surface side and the vapor phase refrigerant is located on the pipe center side due to friction with the pipe wall surface.

Next, the branch position of the branch pipe 40A of the injection circuit 40 will be described. From the characteristics of the refrigeration circuit 30 described above, the injection circuit from the condenser 32 between the outlet of the condenser 32 and the heat exchange section 34 when the rotation speed of the inverter compressor 31 is higher than the predetermined rotation speed at high load. There is a position where the refrigerant flowing to the inverter compressor 31 via the 40 is in the liquid phase state and is in the gas phase state at a low load of less than a predetermined rotation speed. The predetermined rotation speed can be appropriately determined according to the heat resistance of the inverter compressor 31 and the like.

Therefore, the branch position of the branch pipe 40A is set so that the refrigerant flowing from the condenser 32 to the inverter compressor 31 via the injection circuit 40 is in a liquid phase state when the load is high, and is in a gas phase state when the load is low. Has been done. Such a branch position differs depending on the cooling capacity of the refrigeration circuit 30, the predetermined rotation speed described above, and the like, but such a branch position can be specified by conducting an experiment for each refrigeration circuit 30.

(5) Effect of the Embodiment According to the closed showcase 1, the branch position of the branch pipe 40A is in a liquid phase state between the condenser 32 and the heat exchange section 34 when the load of the inverter compressor 31 is high, and is low. This is the position where the gas phase is reached when loaded. In this way, when the load is high, the liquid phase refrigerant easily flows through the injection circuit 40, and when the load is low, the vapor phase refrigerant easily flows through the injection circuit 40. Therefore, when the injection when the compressor is overheated is required, the liquid phase refrigerant flows to cool the inverter compressor 31, and when the injection when the compressor is not overheated is not required, the vapor phase refrigerant flows to cool the inverter compressor 31. The injection circuit 40 that does not operate can be realized without using an electromagnetic valve or a discharge pipe thermostat that controls the opening and closing of the electromagnetic valve. Therefore, according to the closed showcase 1, the injection circuit 40 in which the liquid phase refrigerant flows through the inverter compressor 31 when the compressor is overheated and the vapor phase refrigerant flows when the compressor is not overheated can be realized while suppressing the number of parts.
By reducing the number of parts, it is possible to reduce parts costs, assembly man-hours, parts installation space, and the like. Furthermore, the risk of failure of the component itself, refrigerant leakage from the connection point of the component, electric leakage, etc. can be reduced.

According to the closed showcase 1, the injection circuit 40 extends vertically upward. In this way, when the load is high, the liquid-phase refrigerant is more likely to flow into the injection circuit 40, and when the load is low, the gas-phase refrigerant is more likely to flow into the injection circuit 40.

<Embodiment 2>
The second embodiment is a modification of the first embodiment. In the second embodiment, when the rotation speed of the inverter compressor 31 is higher than the predetermined rotation speed, the refrigerant flowing from the condenser 32 to the inverter compressor 31 via the injection circuit 40 is in a liquid phase state and rotates at a predetermined speed. The branch position and the pipe length of the branch pipe 40A are set so as to be in a gas phase state when the load is low, which is less than the number.

First, with reference to FIG. 3, the characteristics of the pipe length H of the branch pipe 40A will be described.
(Characteristic 1) If the pipe length H of the branch pipe 40A is long, the refrigerant in the branch pipe 40A takes a long time to exchange heat with the outside air. Therefore, when the pipe length H (heat exchange) exceeds a certain level, the refrigerant re-evaporates and the gas phase. It becomes a state and the cooling effect of the injection becomes small.
(Characteristic 2) When the pipe length H of the branch pipe 40A is long, pressure loss occurs due to contact resistance with the pipe wall surface, the pressure difference between the inlet and outlet of the injection circuit 40 becomes small, and the injection flow rate decreases. Further, when the pressure loss becomes large, the gas phase state is reached, and the cooling effect of the injection becomes small.
(Characteristic 3) When the branch pipe 40A is arranged vertically, if the pipe length H is long, the pressure difference between the inlet and outlet of the injection circuit 40 becomes small due to gravity (potential energy), and the injection flow rate decreases. Further, when the pressure loss becomes large, the gas phase state is reached, and the cooling effect of the injection becomes small.

Due to the characteristics of the pipe length H described above, the branch pipe 40A flows from the condenser 32 to the inverter compressor 31 via the injection circuit 40 at a high load when the rotation speed of the inverter compressor 31 is equal to or higher than a predetermined rotation speed. There is a pipe length H in which the refrigerant is in the liquid phase state and is in the gas phase state when the load is low, which is less than a predetermined rotation speed.

Therefore, in the branch pipe 40A according to the second embodiment, the refrigerant flowing from the condenser 32 to the inverter compressor 31 via the injection circuit 40 at a high load when the rotation speed of the inverter compressor 31 is equal to or higher than a predetermined rotation speed. The branch position and the pipe length H are set so as to be in the liquid phase state and to be in the gas phase state when the load is low, which is less than the predetermined rotation speed. Such a branch position and a pipe length H differ depending on the cooling capacity of the refrigeration circuit 30 and the predetermined rotation speed described above, but such a branch position and the pipe length H can be specified by conducting an experiment for each refrigeration circuit 30. ..

According to the closed showcase 1 according to the second embodiment, the selection range of the branch position is widened by the combination of the branch position of the branch pipe 40A and the pipe length H, so that the degree of freedom in designing the injection circuit 40 is improved.

<Embodiment 3>
The third embodiment is a modification of the first embodiment. In the third embodiment, when the rotation speed of the inverter compressor 31 is higher than the predetermined rotation speed, the refrigerant flowing from the condenser 32 to the inverter compressor 31 via the injection circuit 40 is in a liquid phase state and rotates at a predetermined speed. The branch position and the pipe diameter (thickness) of the branch pipe 40A are set so as to be in a gas phase state when the load is low, which is less than the number.

First, the characteristics of the pipe diameter Q of the branch pipe 40A will be described with reference to FIGS. 5 and 6.
(Characteristic 1) FIG. 5 shows two branch pipes 40A (40B_1, 40B_2) having different pipe diameters Q. As shown in FIG. 5, when the pipe diameter Q becomes smaller than a certain level, the liquid refrigerant 60 in the branch pipe 40A is pulled up to the upper part by the surface tension with the inner wall of the pipe. FIG. 6 shows an injection circuit 340 according to the third embodiment. As shown in FIG. 6, when the pipe diameter Q is 39B or more, which is the main pipe, the liquid level position rise due to surface tension cannot be expected.
(Characteristic 2) When the pipe diameter Q becomes large, the flow velocity of the refrigerant becomes slow and a laminar flow state occurs. When the refrigerant is in a laminar flow state, the liquid phase refrigerant and the gas phase refrigerant are separated.

Due to the characteristics of the pipe diameter Q described above, the branch pipe 40A flows from the condenser 32 to the inverter compressor 31 via the injection circuit 340 at a high load when the rotation speed of the inverter compressor 31 is equal to or higher than a predetermined rotation speed. There is a pipe diameter Q in which the refrigerant is in the liquid phase state and is in the gas phase state when the load is low, which is less than a predetermined rotation speed.

Therefore, in the branch pipe 340A according to the third embodiment, the refrigerant flowing from the condenser 32 to the inverter compressor 31 via the injection circuit 340 at a high load when the rotation speed of the inverter compressor 31 is equal to or higher than a predetermined rotation speed. The branch position and the pipe diameter Q are set so as to be in the liquid phase state and to be in the gas phase state when the load is low, which is less than the predetermined rotation speed. Specifically, as shown in FIG. 6, the pipe diameter Q of the branch pipe 340A according to the third embodiment is larger than the pipe diameter R of the pipe 39 connecting the condenser 32 and the expansion valve 36. (In other words, it's getting thicker).
Such a branch position and the pipe diameter Q differ depending on the cooling capacity of the refrigeration circuit 30 and the predetermined rotation speed described above, but such a branch position and the pipe diameter Q can be specified by conducting an experiment for each refrigeration circuit 30. ..

According to the closed showcase 1 according to the third embodiment, the selection range of the branch position is widened by the combination of the branch position of the branch pipe 340A and the pipe diameter Q, so that the degree of freedom in designing the injection circuit 340 is improved.

<Embodiment 4>
The fourth embodiment is a modification of the first embodiment. As shown in FIG. 7, in the fourth embodiment, the shape of the branch pipe 440A is S-shaped (an example of a non-linear shape). The non-linear shape is not limited to the S shape, and may be, for example, a bend shape, an elbow shape, or a hook shape.

First, with reference to FIG. 7, the characteristics of the non-linear branch pipe will be described.
(Characteristic 1) When resistance is given to the flow of the refrigerant by forming the branch pipe 440A in a non-linear shape, the pressure value of the refrigerant decreases and a gas-liquid mixed state is established. If the resistance is further increased, the gas phase state is reached and the cooling effect of the injection becomes smaller.

Due to the characteristics of the pipe shape described above, the branch pipe 440A has a refrigerant that flows from the condenser 32 to the inverter compressor 31 via the injection circuit 40 at a high load when the rotation speed of the inverter compressor 31 is equal to or higher than a predetermined rotation speed. Is in the liquid phase state, and there is a pipe shape that is in the gas phase state when the load is low, which is less than the predetermined rotation speed.
Therefore, in the branch pipe 440A according to the fourth embodiment, the refrigerant flowing from the condenser 32 to the inverter compressor 31 via the injection circuit 440 at a high load when the rotation speed of the inverter compressor 31 is equal to or higher than a predetermined rotation speed. The branch position and shape are set so as to be in the liquid phase state and to be in the gas phase state when the load is low, which is less than a predetermined rotation speed. Such a branch position and a pipe shape differ depending on the cooling capacity of the refrigeration circuit 30 and the predetermined rotation speed described above, but such a branch position and shape can be specified by conducting an experiment for each refrigeration circuit 30.

According to the closed showcase 1 according to the fourth embodiment, the selection range of the branch position is widened depending on the combination of the branch position and the shape of the branch pipe 440A, so that the degree of freedom in designing the injection circuit 440 is improved.

<Other Embodiments>
The techniques disclosed herein are 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, the case where the branch pipe 40A of the injection circuit 40 extends upward from the pipe 39 has been described as an example. On the other hand, the branch pipe 40A does not necessarily have to extend upward as long as the gas-liquid refrigerant can be separated.

(2) In the first embodiment, the case where the branch pipe 40A of the injection circuit 40 extends vertically upward has been described as an example. However, the branch pipe 40A does not necessarily have to extend vertically as long as it extends upward at an angle capable of separating the gas-liquid refrigerant.

(3) In the above-described second to fourth embodiments, a case where any one of the configurations of the second and fourth embodiments is combined with the configuration of the first embodiment has been described as an example. On the other hand, the configuration of the first embodiment may be combined with any two or more configurations of the second to fourth embodiments. In this way, the degree of freedom in designing the injection circuit 40 is further improved.

(4) 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.

(5) 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 (example of cooling storage), 30 ... Refrigeration circuit, 31 ... Inverter compressor (example of compressor with variable rotation speed), 32 ... Condenser, 34 ... Heat exchange section, 36 ... Expansion valve ( Example of expansion component), 37 ... Evaporator, 39 ... Piping, 40 ... Injection circuit, 40A ... Branch piping, 40B ... Capillary tube (Example of expansion component for injection), 340 ... Injection circuit, 340A ... Branch piping, 440 ... Injection circuit, 440A ... Branch pipe, H ... Pipe length, Q ... Pipe diameter

Claims (5)

It ’s a cooling storage,
A refrigeration circuit in which compressors, condensers, expansion parts and evaporators with variable rotation speeds are circulated and connected by piping.
An injection circuit branched from the pipe connecting the condenser and the expansion component and connected to the compressor.
With
The injection circuit flows from the condenser to the compressor via the injection circuit at a high load where the rotation speed of the compressor is equal to or higher than a predetermined rotation speed between the condenser and the expansion component. A cooling storage that branches from the pipe at a position where the refrigerant is in a liquid phase state and is in a gas phase state when the load is low, which is less than the predetermined rotation speed. The cooling storage according to claim 1.
The injection circuit has a branch pipe branched from between the condenser and the expansion component, and an injection expansion component connected to the branch pipe.
A cooling storage in which the branch pipe rises upward from the pipe connecting the condenser and the expansion component at an angle capable of separating gas-liquid refrigerant. The cooling storage according to claim 1.
The injection circuit has a branch pipe branched from between the condenser and the expansion component, and an injection expansion component connected to the branch pipe.
The branch position where the branch pipe branches between the condenser and the expansion component and the pipe length of the branch pipe flow from the condenser to the compressor via the injection circuit at the time of high load. A cooling storage that has a branch position and a pipe length in which the refrigerant is in a liquid phase state and is in a gas phase state when the load is low. The cooling storage according to claim 1.
The injection circuit has a branch pipe branched from between the condenser and the expansion component, and an injection expansion component connected to the branch pipe.
The branch position where the branch pipe branches between the condenser and the expansion component and the pipe diameter of the branch pipe flow from the condenser to the compressor via the injection circuit at the time of high load. A cooling storage that has a branch position and a pipe diameter in which the refrigerant is in a liquid phase state and is in a gas phase state when the load is low. The cooling storage according to claim 1.
The injection circuit has a non-linear branch pipe branched from between the condenser and the expansion component, and an injection expansion component connected to the branch pipe.
The branch position where the branch pipe branches between the condenser and the expansion component and the shape of the branch pipe are such that the refrigerant flowing from the condenser to the compressor via the injection circuit under the high load. Is a cooling storage which has a branching position and shape in which is in a liquid phase state and is in a gas phase state at the time of low load.

Images