JPH0621721B2 - Refrigeration equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a refrigerating apparatus used in a low temperature showcase, a refrigerator, an air conditioner.

(B) Prior art JP-A-57-67771 (F25D21 / 06)
, An evaporator and a fan are housed respectively in the inner and outer two-layer inner duct and amta duct formed independently between the outer and inner boxes of the case body, and both evaporators and decompression elements are connected in series to condense. A bypass circuit with a bypass valve is connected in parallel to the pressure reducing element and the downstream evaporator of the upstream evaporator of the refrigeration cycle as seen from the condensing unit, and the bypass valves are alternately switched. Thus, the downstream evaporator is off-cycle defrosted during the cooling operation of the upstream side evaporator, and the upstream side evaporator is defrosted by the sensible heat of the liquid refrigerant during the cooling operation of the downstream side evaporator. A refrigerated showcase is disclosed.

(C) Problems to be Solved by the Invention In the above conventional technique, since both the upstream side and the downstream side evaporators are connected in series, when the cooling operation is switched from the downstream side evaporator to the upstream side evaporator. However, a large amount of residual liquid refrigerant in the upstream evaporator returns to the compressor, which may cause damage to the compressor due to so-called liquid pack.

(D) Means for Solving Problems In order to solve the above problems, the present invention provides a high-pressure gas pipe connecting a refrigerant compressor and a condenser, and a low-pressure gas pipe connecting an evaporator and a refrigerant compressor. Is connected with a capacitance adjustment circuit,
This capacity adjustment circuit has a solenoid valve that is opened during both defrosting of the evaporator and pump down operation, and the opening / closing degree is adjusted by the pressure of the refrigerant in the low pressure gas pipe during both operations, and the high pressure gas is reduced when this refrigerant pressure decreases. A capacity control valve for guiding a part of the hot gas in the pipe to the low pressure gas pipe is provided.

(E) Action The solenoid valve is opened during both defrosting and pump down operation of the evaporator, and when the pressure of the refrigerant in the low pressure gas pipe drops during this defrosting operation, it automatically responds according to the pressure drop. The degree of opening and closing of the capacity control valve is adjusted so that a part of the hot gas in the high-pressure gas pipe is guided to the low-pressure gas pipe via the capacity control circuit to raise the refrigerant pressure in the low-pressure gas pipe and maintain it above a predetermined pressure. It acts to provide low voltage compensation. Also, during pump down operation, when the pressure of the refrigerant in the gas-liquid mixed state flowing through the low pressure gas pipe drops, the capacity adjustment valve automatically opens in response to this pressure drop and hot gas is supplied to the low pressure gas pipe. The refrigerant pressure in the low-pressure gas pipe is increased and the liquid phase in the gas-liquid mixed refrigerant is evaporated to make it difficult for the liquid refrigerant to return to the refrigerant compressor.

(F) Example (1) shown in Fig. 9 has an opening on the front for storing and taking out products.
An open type low temperature showcase in which a main body is composed of a heat insulating wall (2) forming (3), and a first damper (4A) which opens to an inner layer side described later with an appropriate distance from the inner wall of the heat insulating wall. ), A second damper (4B) that opens to the outer layer side, which will be described later, and first and second windows (4C) and (4D) that are closed on both dampers, respectively. The outer layer in which the plate fin type outer layer evaporator (5) and the axial flow type outer layer blower (6) are arranged
(7), and the outer layer outlet located along the upper edge of the opening
(8) and an outer-layer suction port (9) located along the lower edge of the opening and facing the outer-layer air outlet, and having an appropriate distance from the inner wall of the first partition plate. Then, a second partition plate (10) made of metal is provided and a plate fin type inner layer evaporator (1
Inner layer (13) that arranges 1) and axial flow type inner layer blower (12)
An inner layer outlet (14) arranged in parallel at the upper edge of the opening and inside the outer layer outlet (8), and at the lower edge of the opening inside the outer layer inlet (9). An inner layer suction port (15), which is arranged in parallel and faces the inner layer outlet, and a storage chamber (17) in which a plurality of shelves (16) are arranged are formed. The first and second dampers are plate-shaped ones made of a heat insulating material such as resin, and the first damper (4A) is provided on the upstream side in the flow direction of the circulating air when viewed from the second damper (4B). It is preferable that the tip of the second damper (4B) contacts the outer wall of the second partition plate (10) when opened, and the tip of the second damper (4B) contacts or approaches the inner wall of the heat insulating wall (2) when opened. It is preferable. The outer layer evaporator is arranged in the outer layer (5) so as to be located between the first and second dampers (4A) and (4B), and the inner layer evaporator (11) is arranged in the first damper (4A). ) As seen from the above, it is arranged at a position which is an upstream handle in the flow direction of the circulating air. Both the first and second dampers are simultaneously opened and closed by a single drive unit (M) using a gear motor, a cylinder and the like.

Reference numeral (18) shown in FIG. 1 is a refrigerating device for cooling the low temperature showcase, which includes a refrigerant compressor (19) and an air-cooled heat exchanger.
(20), liquid receiver (21), pressure reducing valve (22) such as expansion valve equipped with temperature sensing part (22A), inner layer evaporator (11), gas-liquid separator (23) through high pressure gas pipe ( 24), high pressure liquid pipe (25), low pressure liquid pipe (26) and low pressure gas pipe
(27) A closed circuit is formed by connecting them in a ring shape. (2
8) is a check valve connected in parallel to the pressure reducing valve (22), and (29) is a receiver
The first solenoid valve arranged in the high pressure liquid pipe (25) between the (21) and the pressure reducing valve (22), (30) is between the inner layer evaporator (11) and the gas-liquid separator (23) Second electromagnetic valve disposed in the low-pressure gas pipe (27), (31) has one end between the liquid receiver and the first electromagnetic valve (29), and the other end at the inner layer evaporator and the second electromagnetic valve. It is a bypass circuit with a third solenoid valve (32) that is connected to the valve (30) and is opened when the inner layer evaporator (11) is defrosted.

Further, the outer layer evaporator (5) is arranged in parallel with the inner layer evaporator (11), by a high pressure liquid branch pipe (33), a low pressure liquid branch pipe (34) and a low pressure gas branch pipe (35). High pressure liquid pipe (25) and low pressure liquid pipe (27)
Connected to. (36) is a motor-operated valve arranged in the high-pressure liquid branch pipe (33), which has a decompression function for decompressing the liquid refrigerant and an opening / closing function for supplying and stopping the liquid refrigerant to the outer layer evaporator (5). It has and. (37) is a fourth solenoid valve connected in parallel to the motor-operated valve and is opened during a pump down operation described later. (38) is a capacity adjusting circuit having one end connected to the high pressure gas pipe (24) and the other end connected to the low pressure gas pipe (27). The fifth solenoid valve (39) is opened during defrosting operation and pump down operation. )When,
The low pressure gas pipe (27) is provided with a capacity adjusting valve (40) that is automatically opened and closed by the pressure of the refrigerant in the low pressure gas pipe (27) and the degree of opening and closing is adjusted.

The refrigeration system (18) shown in FIG. 1 is a low temperature showcase (1).
In an embodiment in which one or two units are adapted, a water-cooled condenser
When (20) is used, the embodiment shown in FIG. 2 is obtained. In this case, since the temperature of the water with which the hot gas is heat-exchanged does not change as much as the temperature of the outside air throughout the four seasons, the liquid receiver (21) can be eliminated.

FIG. 3 shows an embodiment in which three or more low temperature showcases (1) are equipped with an air-cooled refrigeration system (18). In this case, the high pressure liquid pipe (25) is opened during cooling operation and during defrosting operation. And a sixth solenoid valve (41) that is closed when the pump is down, and a high pressure liquid pipe (2) between the sixth solenoid valve (41) and each first solenoid valve (29).
A hot gas pipe (43) having a seventh solenoid valve (42) opened at the time of defrosting operation is provided, one end of which is connected to 5) and the other end of which is connected to the high pressure gas pipe (24). FIG. 4 shows an embodiment in which a water-cooled refrigeration system (18) is used in three or more low temperature showcases (1). Also in this case, the liquid receiver (21) is deleted as in the case of FIG. When performing cooling, defrosting, and pump-down operations in parallel with multiple low-temperature showcases (1), it is important to synchronize the operations of the low-temperature showcases (1) with each other. It is preferable from the relationship.

Next, the operation of the low temperature showcase (1) will be described based on the refrigeration system (18) shown in FIG.

Now, the first damper (4A) and the second damper (4B) are closed as shown by the solid line in FIG. 9, and the inner layer (13) and the outer layer (7) are independent of each other. At this time, the first and second solenoid valves (29) and (30) are opened, and the third, fourth and fifth solenoid valves (32) (37) (39) and the motor operated valve (36) are closed. When the refrigerant compressor (19) is operated in such a state, the refrigerant is compressed as shown by the arrow in Fig. 5: compressor (19) -condenser (20) -receiver (21) -solenoid valve (29) -pressure reducing valve (22) -evaporator for inner layer (11) -solenoid valve (30) -gas-liquid separator (23) -compressor (1
A well-known first cycle that flows with 9) is formed, during which the condenser (20) is condensed and liquefied, the pressure reducing valve (22) is depressurized, and the inner layer evaporator is vaporized. In this cooling operation (for example, 4 hours), the circulating air passing through the inner layer (13) with the blower (12) for the inner layer is a low-pressure liquid refrigerant (for example, at -10 ° C.) passing through the evaporator (11) for the inner layer. The temperature of the storage chamber (17) is -2 ° C by forming a cold air curtain (CA) at the opening (3) as shown by the arrow in Fig. 9 by exchanging heat with the (evaporation temperature).
Aim for cooling maintained at. During this time, the first and second solenoid valves (2
9) (30) repeats opening and closing simultaneously by the temperature detector of the storage room (17) to maintain the temperature of the storage room (17) at an appropriate temperature. on the other hand,
The circulating air passing through the outer layer (7) by the outer layer blower (6) flows along the outside of the cold air curtain (CA) at the opening (3) as shown by the arrow in FIG. In response to this, the temperature becomes gradually lower than the temperature of the outside air surrounding the low temperature showcase (1), and it acts as a protective air curtain (GA) that prevents contact between the cold air curtain (CA) and the outside air.

When the frost on the inner layer evaporator (11) increases with the progress of the cooling operation, the motor-operated valve (36) opens, and a part of the liquid refrigerant from the first solenoid valve (29) is connected to the high pressure liquid branch pipe ( It is divided into 33). The divided liquid refrigerant is decompressed by the electric valve (36), and the outer layer evaporator is decompressed.
(5) Evaporates and vaporizes in (5), passes through the low pressure gas branch pipe (35), flows into the low pressure gas pipe (27), merges with the low pressure gas refrigerant that has passed through the inner layer evaporator (11), and flows into the compressor (19). The second cycle shown by the arrow in FIG. 6 is formed. This second cycle is performed for several tens of seconds to several minutes before the cooling operation is completed, that is, immediately before switching from the cooling operation to the defrosting operation.
Like the inner layer evaporator (11), the outer layer evaporator (5) also has a low temperature, and the circulating air passing through the outer layer (7) is a low-pressure liquid refrigerant (e.g., −) passing through the outer layer evaporator (5). (Evaporation temperature of 17 ° C.), and is maintained at a temperature of, for example, −2 ° C. which is substantially the same as or slightly higher than the temperature of the cooling air circulating in the inner layer (13). In this cooling operation, the operation of the outer layer blower (6) may be stopped.

During this cooling operation, the defrosting start signal is output, the first and second solenoid valves (29) (30) are closed, and the third and fifth solenoid valves (32) (3)
When 9) opens and both the first and second dampers (4A) and (4B) open as shown by the chain line in Fig. 9, the defrosting operation is switched to, and the liquid refrigerant from the receiver (21) is bypassed. (31) -Evaporator for inner layer (11) -Check valve (28) -Fourth solenoid valve (37) -Motor operated valve (36) -Evaporator for outer layer
(5) -Gas-liquid separator (23) -Compressor (19) and a part of the hot gas discharged from the refrigerant compressor (19) is discharged from the capacity adjusting circuit (38) to the low pressure gas pipe ( The third cycle shown by the arrow in FIG. 1 flowing in 27) is formed. This third cycle is, for example, a defrosting operation cycle of the inner layer evaporator (11) that is performed for 10 to 20 minutes, and the liquid refrigerant from the bypass pipe (31) is heat-exchanged in the inner layer evaporator (11). As a result, it becomes supercooled liquid and its sensible heat gradually defrosts the frost on the inner layer evaporator (11). Also, in this defrost cycle, the low pressure gas pipe (27)
When the pressure of the inside refrigerant drops below a predetermined pressure, the capacity adjustment valve (40) opens and guides hot gas to the low-pressure gas pipe (27) to raise the low-pressure pressure to the predetermined pressure to perform low-pressure compensation and low-pressure compensation. The liquid phase contained in the refrigerant is evaporated by the sensible heat of the hot gas. On the other hand, the circulating air that has passed through the inner layer evaporator is interrupted by the first damper (4A) in the inner layer (13) and flows from the first window (4C) to the outer layer (7), and the outer layer evaporator is then discharged.
It is cooled by exchanging heat with the low-pressure liquid refrigerant passing through (5).
This cooled circulating air is directed by the second damper (4B), returns from the second window (4D) to the inner layer (13), and is blown out to the inner layer outlet (1
It is blown out from 4) toward the opening (3), forming a cold air curtain (CA) as in the cooling operation, and the suction port for the inner layer
The circulation of the chain line arrow in FIG. 9 returning from (15) to the inner layer (13) is repeated.

When the frost on the inner layer evaporator (11) is thawed as the defrosting operation progresses, the third solenoid valve (29) is kept closed until the first and second solenoid valves (29) (30) remain closed. 32) closes and the 4th solenoid valve (37)
When the open, the liquid refrigerant is not supplied to the inner layer evaporator (11), and the so-called pump that collects the residual liquid refrigerant (including a part of saturated gas) of the inner layer evaporator (11) into the liquid receiver (21) The operation is down, and the liquid refrigerant inside the evaporator (11) for the inner layer is a check valve (28) -fourth solenoid valve (37) -evaporator (5) -outer layer vapor-liquid separator as shown by the arrow in FIG. (23) -Compressor (19) -Condenser (20) -Liquid receiver (21), and it is stored in this liquid receiver (21) as a high pressure liquid refrigerant.
On the other hand, when the refrigerant pressure in the low-pressure gas pipe (27) is low, the capacity adjustment valve (40) is opened in the same manner as in the defrosting operation, and the low-pressure force is increased to a predetermined pressure. The liquid phase is evaporated with hot gas to prevent liquid back. This pump-down operation is performed for several minutes to several tens of minutes with the completion of the defrosting operation of the inner layer evaporator (11), and the inner layer evaporator (1
1) Saturated gas and liquid refrigerant among the refrigerant in
By being sucked into (5), a part of the inner layer evaporator (11) is vaporized and evaporated, and the inner layer evaporator is heated by the latent heat of vaporization.
The refrigerant that gives a cooling effect to (11) and evaporates while the liquid refrigerant is flowing in the outer layer evaporator (5) while passing through the outer layer evaporator and evaporates and vaporizes to the outer layer due to this latent heat of vaporization. Evaporator
A cooling effect will be added to (5). This pump down operation is also the time for draining dew attached to the inner layer evaporator (11). With the end of pump down operation,
The fifth solenoid valves (37) and (39) are closed, the first and second solenoid valves (29) and (30) are opened, and the cooling operation shown in FIG. 5 is restored.

The first, second, and third cycles, that is, the cooling operation of only the inner layer evaporator (11), the inner layer and outer layer evaporators (11)
The four cooling modes A, B, C and D are the second cooling operation (5), the defrosting operation of the inner layer evaporator (11) {cooling operation of the outer layer evaporator (5)} and the pump down operation The refrigeration system (18) shown in FIGS. 4 to 4 can be similarly operated.

The above four operation modes can be represented by the time chart shown in FIG.

Therefore, according to such a refrigeration system (18), the solenoid valve (39) of the capacity adjusting circuit (38) is opened during the defrosting operation and the pump down operation, so that the low pressure gas pipe (27) is passing through. When the pressure of the low-pressure refrigerant such as the low-pressure gas refrigerant or the low-pressure gas-liquid mixed refrigerant is lower than the predetermined pressure, the capacity control valve (40) is opened due to the pressure loss of the low-pressure refrigerant and the hot gas pipe (24) One part can be guided to the low-pressure gas pipe (27) through the capacity adjusting circuit (38), and as a result, the low-pressure refrigerant returned from the low-pressure gas pipe (27) to the refrigerant compressor (19) by hot gas up to a predetermined pressure. It is possible to maintain the operation of the refrigerant compressor (19) in a good state by raising it, and when there is a liquid phase in the low-pressure refrigerant, it is evaporated to a gas phase, so liquid back to the refrigerant compressor (19) is performed. It can be prevented.

(G) Effects of the Invention According to the present invention described above, the following effects are produced.

When the pressure of the refrigerant in the low-pressure gas pipe decreases, the capacity adjustment valve is automatically opened with this pressure decrease, and a part of the hot gas in the high-pressure gas pipe is guided to the low-pressure gas pipe through the capacity adjustment circuit to reduce the low-pressure pressure. Since the low pressure compensation can be performed to raise the pressure to a predetermined level, it is possible to avoid the refrigerant compressor from stopping due to the low pressure drop, and to operate the refrigerant compressor continuously following the load fluctuation. Both stable defrosting and pump down operation can be performed.

When the low-pressure refrigerant in the low-pressure gas pipe has a liquid phase, it is vaporized by hot gas into a gas phase, so that liquid back to the refrigerant compressor can be prevented.

[Brief description of drawings]

Each of the drawings shows an embodiment of the refrigerating apparatus of the present invention, FIG. 1 is a defrost cycle diagram in an air-cooling type refrigerating apparatus, and FIG. 2 is a main circuit when the refrigerating apparatus of FIG. 1 is changed to a water-cooling type. Figure,
FIG. 3 is a refrigerant circuit diagram of a multi-system air-cooled refrigerating apparatus, FIG. 4 is a circuit diagram of essential parts when the refrigerating apparatus of FIG. 3 is changed to a water-cooled type, and FIGS. 5 to 7 are FIG. Fig. 8 is a time chart showing each operation of the refrigeration system, Fig. 9 is a vertical cross section of a low temperature showcase incorporating the refrigeration system. It is a figure. (11) …… Evaporator, (19) …… Refrigerant compressor, (20) …… Condenser, (24) …… High pressure gas pipe, (27) …… Low pressure gas pipe, (38)…
… Volume adjustment circuit, (39) …… solenoid valve, (40) …… Volume adjustment valve.

Claims (1)

[Claims] 1. A refrigerant compressor, a condenser, a pressure reducing valve, and an evaporator, wherein the refrigerant compressor and the condenser are high-pressure gas pipes, and the condenser and the pressure reducing valve are high-pressure liquid pipes. The pressure reducing valve and the evaporator are formed by a low pressure liquid pipe, and the evaporator and the refrigerant compressor are connected by a low pressure gas pipe to form a refrigeration circuit capable of a cooling operation, and frost is formed on the evaporator by the cooling operation. When adhered, a defrosting operation that guides the refrigerant in the high-pressure liquid pipe to the evaporator, and a refrigerating apparatus that can perform a pump down operation to remove the refrigerant in the evaporator after the defrosting operation ends, The high-pressure gas pipe and the low-pressure gas pipe are connected by a capacity adjusting circuit, and in the capacity adjusting circuit, a solenoid valve that is opened during both the defrosting and pump down operations, and the inside of the low-pressure gas tube during both operations. The opening and closing degree is adjusted by the pressure of the refrigerant. Refrigeration apparatus being characterized in that a capacity control valve for guiding during lowering of the pressure part of the hot gas in the high-pressure gas pipe into the low pressure gas pipe.