JP2000121183A - Binary chiller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress excessive pressure rise of high pressure refrigerant while preventing compression of liquid without providing any bypath. SOLUTION: A compressor, a condenser, a expansion valve and the evaporating section of a refrigerant heat exchanger are coupled sequentially to constitute a high temperature side refrigerating circuit for circulating primary refrigerant. A compressor 31 the condensing section of the refrigerant heat exchanger 11, an expansion valve EV21 and the evaporator 5a are coupled sequentially to constitute a low temperature side refrigerating circuit 3A for circulating secondary refrigerant. When an actuation signal is inputted, only the high temperature side refrigerating circuit is actuated based on the actuation signal. The low temperature side refrigerating circuit 3A is actuated when the suction refrigerant of a compressor in the high temperature side refrigerating circuit gets to at least a specified wet state after the high temperature side refrigerating circuit is started.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a binary refrigeration system, and more particularly to a measure against starting.

[0002]

2. Description of the Related Art Conventionally, a binary refrigeration system is disclosed in
As disclosed in Japanese Patent No. 210515, a primary refrigerant circuit and a secondary refrigerant circuit that individually perform refrigeration operation are provided. This binary refrigeration apparatus is used to obtain a low temperature of minus several tens of degrees, and can be used in a high efficiency from a high compression ratio to a low compression ratio, which is advantageous in energy saving.

[0003] The primary side refrigerant circuit of the above-mentioned two-way refrigeration system is configured by connecting a compressor, a condenser, an expansion valve, and an evaporator of a refrigerant heat exchanger in this order. Also, the secondary refrigerant circuit is
The compressor, the condensing part of the refrigerant heat exchanger, the expansion valve, and the evaporator are sequentially connected. In the refrigerant heat exchanger, the heat of condensation of the secondary refrigerant circuit and the heat of evaporation of the primary refrigerant circuit are exchanged.

[0004]

Conventionally, in the above-mentioned binary refrigeration system, when an operation switch is turned on and an activation signal is inputted, the primary refrigerant circuit and the secondary refrigerant circuit are simultaneously activated. . That is, when the operation switch is turned on, the compressor of the primary refrigerant circuit is activated to circulate the primary refrigerant, and at the same time, the compressor of the secondary refrigerant circuit is activated to circulate the secondary refrigerant.

However, when the primary refrigerant circuit and the secondary refrigerant circuit are simultaneously activated, the secondary refrigerant flows into the condensing part in the evaporating part of the refrigerant heat exchanger until the preparation of the primary refrigerant is completed. Will be. As a result, there has been a problem that the secondary refrigerant cannot sufficiently radiate heat, the high-pressure refrigerant pressure in the secondary refrigerant circuit excessively increases, and the protection device operates to stop the operation.

Therefore, conventionally, in the secondary refrigerant circuit, a bypass passage for adjusting the capacity is provided, and the hot gas discharged from the compressor flows to the evaporator by bypassing the condenser and the expansion valve of the refrigerant heat exchanger. Adjust the cooling capacity. That is, when the primary side refrigerant circuit and the secondary side refrigerant circuit are started, the hot gas of the compressor in the secondary side refrigerant circuit is directly supplied to the evaporator to reduce the capacity.

However, in this structure, it is necessary to provide a bypass passage, and there are problems that the number of parts is increased, the structure is complicated, and the cost is increased.

On the other hand, it has been proposed that a timer is provided in the secondary refrigerant circuit, and after the primary refrigerant circuit is activated, the secondary refrigerant circuit is activated with a predetermined delay. However, if the delay time is short, the excessive increase in the high-pressure refrigerant pressure cannot be sufficiently suppressed. Conversely, if the delay time is too long, evaporation of the primary refrigerant in the refrigerant heat exchanger is insufficient, and the primary refrigerant circuit Refrigerant in the compressor of too much wet state,
There is a problem that the liquid may be compressed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to suppress an excessive increase in the pressure of a high-pressure refrigerant and to surely prevent liquid compression without providing a bypass passage. It is.

[0010]

Means for Solving the Problems-Summary of the Invention-The present invention is to directly detect the wet state of the refrigerant of the compressor in the secondary side refrigerant circuit and activate the secondary side refrigerant circuit. It is.

-Solution Means- Specifically, as shown in FIG. 2, a first solution means is a compressor (21), a condenser (22), an expansion mechanism (EV11), a refrigerant heat exchanger, The primary refrigerant circuit (20) in which the evaporating section of (11) is connected in order and the primary refrigerant circulates, the compressor (31), the condenser section of the refrigerant heat exchanger (11), and the expansion section The mechanism (EV21) and the evaporator (5a) are connected in order, and the secondary refrigerant circulates, and the secondary heat is exchanged between the primary refrigerant and the secondary refrigerant in the refrigerant heat exchanger (11). It is premised on a binary refrigeration system having a side refrigerant circuit (3A).

When a start signal is inputted, a primary start means (73) for starting only the primary refrigerant circuit (20) based on the start signal is provided. In addition, after the primary side refrigerant circuit (20) is activated by the primary side activation means (73), the refrigerant sucked into the compressor (21) in the primary side refrigerant circuit (20) becomes at least a predetermined wet state. In this case, a secondary starting means (74) for starting the secondary refrigerant circuit (3A) is provided.

[0013] The second solution is the first solution, wherein the secondary-side starting means (74) starts after the primary-side starting means (73) starts the primary-side refrigerant circuit (20). The first predetermined time has elapsed, and the refrigerant sucked into the compressor (21) in the primary refrigerant circuit (20) is in a predetermined wet state, or the second predetermined time longer than the first predetermined time is set. When the time elapses, the secondary-side refrigerant circuit (3A) is activated.

[0014] The third solution is the first or second embodiment.
And a plurality of refrigerant heat exchangers (11, 11) are provided. And each of the refrigerant heat exchangers (11,
The evaporating sections of 11) are connected in parallel to each other to form a primary refrigerant circuit (20). Further, secondary refrigerant circuits (3A, 3B) are connected to the refrigerant heat exchangers (11, 11), respectively, and the evaporators (5a, 5b) of the secondary refrigerant circuits (3A, 3B) are connected. ) Are integrally formed.

According to the above-mentioned specific matter, in the present solution, for example, when an operation switch is turned on and a start signal is inputted, first,
Primary-side activation means (73) activates the primary-side refrigerant circuit (20). As a result, the cooling operation of the primary refrigerant circuit (20) starts, and the primary refrigerant circulates. In this state, the operation of the secondary-side refrigerant circuit (3A) has not been started, and is kept stopped.

Then, after waiting for the primary refrigerant circuit (20) to reach a predetermined wet state, the secondary-side starting means (74)
Starts the secondary refrigerant circuit (3A).

That is, when the primary refrigerant circuit (20) is started, the primary refrigerant is condensed in the condenser (22), evaporates in the evaporator of the refrigerant heat exchanger (11), and returns to the compressor (21). That is, since the secondary refrigerant circuit (3A) has not been started yet, the secondary refrigerant is not supplied to the refrigerant heat exchanger (11). Therefore, in the refrigerant heat exchanger (11), even when the primary refrigerant can be evaporated, the amount of heat of evaporation is insufficient, and the refrigerant sucked into the compressor (21) is in a wet state.

Therefore, when the primary refrigerant circuit (20) is in a predetermined wet state, the secondary refrigerant circuit (3A) is started, and the cooling operation is completely started.

In particular, according to the second solution, after the primary-side refrigerant circuit (20) is started, even if the refrigerant sucked into the compressor (21) does not reach the predetermined wet state, the predetermined time has elapsed. Then, the secondary-side refrigerant circuit (3A) is activated, and the operation shifts to the normal cooling operation.

In the third solution, when a plurality of secondary refrigerant circuits (3A, 3B) are provided, for example, each of the secondary refrigerant circuits (3A, 3B) is sequentially activated at predetermined time intervals. .

[0021]

Therefore, according to the present invention, after the primary refrigerant circuit (20) is started, the primary refrigerant circuit (2) is activated.
When the refrigerant sucked into the compressor (21) of (0) reaches a predetermined wet state, the secondary refrigerant circuit (3A) is started, so that the preparation of the primary refrigerant in the refrigerant heat exchanger (11) is ready. After completion, the circulation of the secondary refrigerant can be started. As a result, an excessive increase in the high-pressure refrigerant pressure in the secondary-side refrigerant circuit (3A) can be reliably prevented, and unnecessary operation stoppage can be suppressed.

Further, since it is not necessary to provide a bypass path for adjusting the capacity as in the prior art, the number of parts can be reduced, and the structure can be simplified, so that the cost can be reduced. .

Further, since the secondary side refrigerant circuit (3A) can be prevented from being excessively delayed, an excessively wet state can be avoided, and liquid compression can be prevented beforehand and reliably. it can.

According to the second solution, the secondary refrigerant circuit (3A) is started according to the wet state and time of the refrigerant sucked into the compressor (21). An excessive rise in the high-pressure refrigerant pressure in the refrigerant circuit (3A) and the wet state of the refrigerant sucked into the compressor (21) in the primary-side refrigerant circuit (20) can be suppressed in a well-balanced manner.

[0025]

Embodiments of the present invention will be described below in detail with reference to the drawings.

As shown in FIGS. 1 and 2, the binary refrigeration system (10) cools a refrigerator or a freezer.
An outdoor unit (1A), a cascade unit (1B), and a cooling unit (1C) are provided. The outdoor unit (1A) and a part of the cascade unit (1B) constitute a high-temperature refrigeration circuit (20). on the other hand,
Two low-temperature side refrigeration circuits (3A, 3B) are constituted by the cascade unit (1B) and the cooling unit (1C).

The high temperature side refrigeration circuit (20) constitutes a primary side refrigerant circuit capable of reversible operation by switching the refrigerant circulation direction between a forward cycle and a reverse cycle. The high temperature side refrigeration circuit (20) includes a compressor (21), a condenser (22),
And an evaporator of two refrigerant heat exchangers (11, 11).

A first gas pipe (40) is connected to the discharge side of the compressor (21), and a second gas pipe (41) is connected to the suction side. The first gas pipe (40) includes a compressor (21)
, An oil separator (23) and a four-way switching valve (24) are connected in order, and connected to one end of the condenser (22). One end of a liquid pipe (42) is connected to the other end of the condenser (22). The liquid pipe (42) has a main pipe (4a) and two branch pipes (4b,
4c). Each branch pipe (4b, 4c) is connected to each evaporator of the two refrigerant heat exchangers (11, 11).

The main pipe (4a) of the liquid pipe (42) is connected to the branch pipe (4b, 4) from the condenser (22) via the receiver (25).
c) is connected to. On the other hand, the branch pipe (4b, 4c)
Is provided with a cooling electric expansion valve (EV11) as an expansion mechanism.

The second gas pipe (41) is a main pipe (4d)
And two branch pipes (4e, 4f). The main pipe (4d) of the second gas pipe (41) connects the accumulator (26) and the four-way switching valve (24) in order from the compressor (21), while the branch pipes (4e, 4f) Is connected to the evaporator of each refrigerant heat exchanger (11, 11). That is, the evaporating sections of the two refrigerant heat exchangers (11, 11) are connected in parallel in the high-temperature side refrigeration circuit (20).

The branch pipes (4b, 4c, 4e, 4f) of the liquid pipe (42) and the second gas pipe (41) are provided in the cascade unit (1B).

The first gas pipe (40) and the receiver (25)
A gas passage (43) is connected between the two. One end of the gas passage (43) is connected between the four-way switching valve (24) and the condenser (22) in the first gas pipe (40), and the other end is connected to the upper part of the receiver (25). Have been. And
The gas passage (43) is provided with an on-off valve (SVGH), and is configured to perform high-pressure control during a cooling operation.

An oil return passage (44) having a capillary tube (CP) is connected between the oil separator (23) and the suction side of the compressor (21). An unload passage (45) of a compressor (21) including a capillary tube (CP) and an on-off valve (SVRH) is connected between a discharge side and a suction side of the compressor (21). The middle of the unload passage (45) is connected to the compressor (21).

The first gas pipe (40) on the discharge side of the compressor (21) has a high-pressure pressure sensor (SPH1) for detecting high-pressure refrigerant pressure and a predetermined high-pressure High pressure switch (HPS1) that outputs an off signal when it reaches the value
Are provided. Further, a low-pressure pressure sensor (SPL1) for detecting a low-pressure refrigerant pressure is provided in the second gas pipe (41) on the suction side of the compressor (21).

Further, in the second gas pipe (41) on the suction side of the compressor (21), a suction temperature sensor (Th11) for detecting a suction side refrigerant temperature is provided with a four-way switching valve (24) and an accumulator (26). ).

On the other hand, the first low temperature side refrigeration circuit (3A)
A secondary-side refrigerant circuit capable of reversible operation by switching the refrigerant circulation direction between a forward cycle and a reverse cycle is configured. The first low-temperature refrigeration circuit (3A) includes a compressor (31), a condensing section of a first refrigerant heat exchanger (11), and an evaporating heat transfer tube (5a).
And

The discharge side of the compressor (31) is connected to a first refrigerant heat exchanger (11) via a first gas pipe (60) via an oil separator (32) and a four-way switching valve (33). Is connected to one end of the condenser section. The other end of the condenser is connected to a liquid pipe (61)
Evaporating heat transfer tube (5a) via check valve (CV), receiver (34) and cooling expansion valve (EV21) as an expansion mechanism
Is connected to one end. The other end of the evaporating heat transfer tube (5a) is connected to a compressor (31) via a check valve (CV), a four-way switching valve (33) and an accumulator (35) by a second gas pipe (62). Connected to the suction side.

Then, the first refrigerant heat exchanger (11)
Is a cascade condenser, which is mainly configured to exchange heat between evaporation heat of the high-temperature side refrigeration circuit (20) and condensation heat of the first low-temperature side refrigeration circuit (3A).

The cooling expansion valve (EV21) is a temperature-sensitive expansion valve, and the temperature-sensitive cylinder (TS) is connected to the second gas pipe (62) on the outlet side of the heat transfer tube (5a) for evaporation. Is provided.

Since the first low-temperature side refrigeration circuit (3A) is configured to perform a reverse cycle defrost operation, it is provided with a drain pan passage (63), a gas bypass passage (64), and a pressure reduction passage (65). I have. The drain pan passage (63) is connected to both ends of the check valve (CV) in the second gas passage (62), and is provided with a drain pan heater (6a) and a check valve (CV). ) Is configured to flow.

The gas bypass passage (64) is connected to both ends of the cooling expansion valve (EV21) in the liquid pipe (61) and is provided with a check valve (CV). (EV21).

The pressure reducing passage (65) is connected to both ends of the check valve (CV) in the liquid pipe (61) and has an on-off valve (SVDL). The on-off valve (SVDL) is set to be slightly smaller than the diameter of the pressure reducing passage (65), and is configured to reduce the pressure of the liquid refrigerant during the defrost operation.

An upper end of the receiver (34) is connected to one end of a gas vent passage (66). The gas vent passage (66) includes an on-off valve (SVGL) and a capillary tube (CP), and the other end is connected to the second gas pipe (62) upstream of the accumulator (35).

An oil return passage (67) having a capillary tube (CP) is connected between the oil separator (32) and the suction side of the compressor (31).

The first gas pipe (60) on the discharge side of the compressor (31) has a high-pressure pressure sensor (SPH2) for detecting high-pressure refrigerant pressure and a predetermined high-pressure High pressure switch (HPS2) that outputs an off signal when the value reaches
Are provided. The second gas pipe (62) on the suction side of the compressor (31) is provided with a low pressure sensor (SPL2) for detecting a low pressure refrigerant pressure.

The second low-temperature refrigeration circuit (3B) has substantially the same configuration as the first low-temperature refrigeration circuit (3A), but has a secondary refrigerant circuit that performs only a cooling operation without performing a defrost operation. Make up. The second low-temperature refrigeration circuit (3B)
The four-way switching valve (24) in the low temperature side refrigeration circuit (3A) is not provided, and further, the drain pan passage (63), the gas bypass passage (64), and the pressure reducing passage (65) are not provided. That is, the second low-temperature side refrigeration circuit (3B) includes the compressor (31), the condensing part of the second refrigerant heat exchanger (11), the receiver (34), the cooling expansion valve (EV21), and the evaporating transmission. The heat pipe (5b) and the accumulator (35) are sequentially connected by a first gas pipe (60), a liquid pipe (61), and a second gas pipe (62).

The cooling expansion valve (EV21) is a temperature-sensitive expansion valve, and a temperature-sensitive cylinder is provided in the second gas pipe (62) on the outlet side of the heat transfer tube (5b) for evaporation. I have. The second
The refrigerant heat exchanger (11) is a cascade condenser and is configured to exchange heat between the evaporation heat of the high-temperature refrigeration circuit (20) and the condensation heat of the second low-temperature refrigeration circuit (3B). .

The cooling heat transfer tubes (5a, 5b), the cooling expansion valve (EV21) and the drain pan passage (63) in the two low-temperature side refrigeration circuits (3A, 3B) are provided in the cooling unit (1C). Are provided in the cascade unit (1B).

The heat transfer tubes (5a, 5b) for evaporation of the two low-temperature side refrigeration circuits (3A, 3B) respectively constitute evaporators as shown in FIG. 2, but in this embodiment, they are integrated. One evaporator (50) is formed. Specifically, each of the low-temperature side refrigeration circuits (3A, 3B) includes n heat transfer tubes (5a, 5b), and the evaporator (50) has 2n heat transfer tubes (5a, 5B).
a, 5b), that is, 2n passes are formed.

A liquid temperature sensor (Th21) for detecting the temperature of the liquid refrigerant is provided in the first low-temperature side refrigeration circuit (3A) in front of the evaporative heat transfer pipe (5a) of the liquid pipe (61). On the other hand, the evaporator (50) is provided with an evaporator temperature sensor (Th22) for detecting the temperature of the evaporator (50).

The high-temperature side refrigeration circuit (20) and both low-temperature side refrigeration circuits (3A, 3B) are controlled by a controller (70). The controller (70) includes a high-pressure pressure sensor (SP
H1 and SPH2), while the compressor (2
1, 31). The controller (70) includes, in addition to the cooling means (71) and the defrost means (72) for controlling the cooling operation, a primary-side activation means (73) and a secondary-side activation means (74) for controlling activation. Is provided.

The defrost means (72) is configured to perform a defrost operation at predetermined time intervals, and stops the operation of the second low-temperature side refrigeration circuit (3B) while maintaining the defrosting operation with the first low-temperature side refrigeration circuit (3A). Four-way switching valve (24,
33) is switched to the dashed line in FIGS. 1 and 2, and the refrigerant is circulated in the reverse cycle of the refrigerant circulation direction.

The primary side starting means (73) is configured to start only the high temperature side refrigeration circuit (20) based on the starting signal when a starting signal is inputted by turning on an operation switch or the like. .

The secondary-side start-up means (74) starts the suction of the compressor (21) in the primary-side refrigerant circuit (20) after the primary-side start-up means (73) starts the primary-side refrigerant circuit (20). It is configured to activate the secondary-side refrigerant circuit (3A) when the refrigerant reaches at least a predetermined wet state.

Specifically, the secondary-side starting means (74)
After the primary-side activation means (73) activates the primary-side refrigerant circuit (20), a predetermined time (10 seconds) by the first timer has elapsed, and the refrigerant sucked into the compressor (21) in the primary-side refrigerant circuit (20). Is configured to start the secondary refrigerant circuit (3A) when a predetermined wet state is reached or when a predetermined time (1 minute) by a second timer longer than the first timer elapses.

The wet state depends on the suction side refrigerant temperature TSH detected by the suction temperature sensor (Th11) and the equivalent saturation temperature TeH of the low pressure refrigerant pressure detected by the low pressure pressure sensor (SPL2).
Is derived from the superheat degree (TSH-TeH), and when the superheat degree falls below 5 ° C., a wet state is established.

-Operation of Binary Refrigeration Unit- Next, the operation of the binary refrigeration unit (10) will be described.

First, when performing the cooling operation, the compressor (21) of the high-temperature side refrigeration circuit (20) and both low-temperature side refrigeration circuits (3A, 3A)
B) The two compressors (31, 31) are driven together. In this state, in the high-temperature side refrigeration circuit (20), the four-way switching valve (24) is switched to the solid line in FIG. 1, and the opening degree of the electric expansion valve for cooling (EV11) is controlled.

The compressor (21) of the high-temperature side refrigeration circuit (20)
The primary refrigerant discharged from the condenser is condensed in the condenser (22) to become a liquid refrigerant and flows to the cascade unit (1B). Then, the liquid refrigerant is divided into two branch pipes (4b, 4c), and the pressure is reduced by the electric cooling expansion valve (EV11). Thereafter, the liquid refrigerant evaporates in each evaporating section of the two refrigerant heat exchangers (11, 11) to become gas refrigerant and returns to the compressor (21). This cycle is repeated.

On the other hand, in the first low-temperature side refrigeration circuit (3A), the four-way switching valve (33) is switched to the solid line in FIG. 2, while the on-off valve (SVDL) of the pressure reducing passage (65) is fully closed to provide cooling. Controls the degree of superheating of the expansion valve (EV21). In the second low-temperature refrigeration circuit (3B), the degree of superheat of the cooling expansion valve (EV21) is controlled.

In the two low-temperature side refrigeration circuits (3A, 3B), the secondary refrigerant discharged from the compressors (31, 31) is condensed in the condensing section of the refrigerant heat exchanger (11, 11) to become a liquid refrigerant. The pressure of the liquid refrigerant is reduced by the expansion valves for cooling (EV21, EV21).
Thereafter, the liquid refrigerant evaporates in the evaporating heat transfer tubes (5a, 5b) to become gas refrigerant and returns to the compressors (31, 31). This cycle is repeated.

In each of the refrigerant heat exchangers (11, 11), the heat of evaporation of the high-temperature side refrigeration circuit (20) and the heat of condensation of each of the low-temperature side refrigeration circuits (3A, 3B) exchange heat. The secondary refrigerant in the side refrigeration circuits (3A, 3B) is cooled and condensed. on the other hand,
In the evaporator (50), the secondary refrigerant evaporates to generate cooling air, thereby cooling the inside of the refrigerator.

The binary refrigeration system (10) performs a defrost operation. This defrost operation is performed every 6 hours during the refrigeration operation and every 12 hours during the freezing operation. The defrost operation is performed by the second low-temperature refrigeration circuit (3B)
Is stopped, while the refrigerant circulation direction of the first low-temperature refrigeration circuit (3A) and the high-temperature refrigeration circuit (20) is reversed.

Specifically, in the first low-temperature refrigeration circuit (3A), the four-way switching valve (33) is switched to the broken line in FIG.
Fully open the on-off valve (SVDL) and fully close the cooling expansion valve (EV21) of the pressure reducing passage (65).

The secondary refrigerant discharged from the compressor (31) passes through the four-way switching valve (33), passes through the drain pan passage (63), and heats the drain pan with the drain pan heater (6a).
Subsequently, the secondary refrigerant flows through the evaporator heat transfer tube (5a) to heat the evaporator (50), thereby melting the frost on the evaporator (50). Thereafter, the secondary refrigerant flowing through the heat transfer tube for evaporation (5a) flows through the gas bypass passage (64), flows through the pressure reducing passage (65) via the receiver (34), and is depressurized by the on-off valve (SVDL). Subsequently, the secondary refrigerant evaporates in the condensing section of the refrigerant heat exchanger (11), and returns to the compressor (31) via the four-way switching valve (33) and the accumulator (35). This cycle is repeated.

On the other hand, in the high temperature side refrigeration circuit (20), the four-way switching valve (24) is switched to the dashed line in FIG. 1, and the cooling electric expansion valve (EV11) is fully opened.

The primary refrigerant discharged from the compressor (21) passes through the four-way switching valve (24) to the first refrigerant heat exchanger (11).
And heats the secondary refrigerant of the first low-temperature side refrigeration circuit (3A). Thereafter, the primary refrigerant flowing through the evaporating section of the refrigerant heat exchanger (11) passes through the receiver (25), and then enters the condenser (2).
Evaporated in 2), the four-way switching valve (24) and the accumulator (2
After 6), return to the compressor (21). This cycle is repeated.

Next, the starting operation of the high-temperature side refrigeration circuit (20) and the first low-temperature side refrigeration circuit (3A), which is a feature of the present invention, will be described with reference to FIG.

First, as shown in FIG. 3, after starting the high-temperature side refrigeration circuit (20), it is determined in step ST1 whether or not the second timer has counted one minute. That is, when an operation switch or the like is turned on and a start signal is input, first,
Primary side starting means (73) starts the high temperature side refrigeration circuit (20). As a result, the above-described cooling operation starts, and the primary refrigerant circulates. In this state, both low-temperature side refrigeration circuits (3
A, 3B) has not started operation and remains stopped.

Thereafter, in step ST1, the second
Until the timer counts 1 minute, the determination is NO, and the process proceeds to step ST2 where the first timer counts 10 seconds and determines whether the high-temperature side refrigeration circuit (20) is in a predetermined wet state. The above steps are performed until the predetermined wet state is reached.
If the determination in ST2 is NO, the process moves to step ST1, and the above operation is repeated. The wet state of the high-temperature side refrigeration circuit (20) depends on the compressor (2) in the high-temperature side refrigeration circuit (20).
The determination is made based on whether or not the superheat degree of the suction-side refrigerant of 1) has dropped below 5 ° C. (TSH−TeH <5).

That is, when the high-temperature side refrigeration circuit (20) is started, the primary refrigerant is condensed in the condenser (22), evaporates in each evaporator of the refrigerant heat exchanger (11, 11) and evaporates in the compressor (21). ), But since the low-temperature side refrigeration circuits (3A, 3B) have not been started yet, the secondary refrigerant is not supplied to the refrigerant heat exchangers (11, 11). Therefore, in the refrigerant heat exchangers (11, 11), even when the primary refrigerant can be evaporated, the amount of heat of evaporation is insufficient, and the refrigerant sucked into the compressor (21) becomes wet.

Thereafter, when the refrigerant sucked into the compressor (21) becomes wet and the first timer counts 10 seconds, the determination in step ST2 becomes YES, and the secondary side starting means (74) sets the low-temperature The side refrigeration circuits (3A, 3B) are activated and the operation shifts to the normal cooling operation.

Even if the refrigerant sucked into the compressor (21) does not reach the predetermined wet state, the second timer counts one minute from the activation of the high-temperature side refrigeration circuit (20), and the process proceeds to step ST1. Is YES and the low-temperature side refrigeration circuit (3
A, 3B) to start up and shift to normal cooling operation.

The low-temperature side refrigeration circuits (3A, 3B) are activated, for example, after the first low-temperature side refrigeration circuit (3A) is activated.
Three minutes later, the second low-temperature refrigeration circuit (3B) is started.

-Effects of Embodiment- As described above, according to the present embodiment, after the high-temperature side refrigeration circuit (20) is started, the suction refrigerant of the compressor (21) of the high-temperature side refrigeration circuit (20). Since the first low-temperature side refrigeration circuit (3A) is started when a predetermined wet state is reached,
After the preparation of the primary refrigerant in the refrigerant heat exchanger (11, 11) is completed, the circulation of the secondary refrigerant can be started. As a result, an excessive increase in the high-pressure refrigerant pressure of the first low-temperature side refrigeration circuit (3A) can be reliably prevented, and unnecessary operation stoppage can be suppressed.

Further, since there is no need to provide a bypass passage for adjusting the capacity as in the conventional case, the number of parts can be reduced, and the structure can be simplified, so that the cost can be reduced. .

Further, since the first low-temperature side refrigeration circuit (3A) can be prevented from being excessively delayed, an excessively wet state can be avoided, and the liquid compression can be prevented beforehand and surely. Can be.

The first low-temperature refrigeration circuit (3A) is activated according to the wet state and time of the refrigerant sucked into the compressor (21) of the high-temperature refrigeration circuit (20). An excessive increase in the high-pressure refrigerant pressure in the low-temperature side refrigeration circuit (3A) and the wet state of the refrigerant sucked into the compressor (21) in the high-temperature side refrigeration circuit (20) can be suppressed in a well-balanced manner.

[0079]

In another embodiment of the present invention,
Although the low temperature side refrigeration circuit (3A, 3B) was provided, the present invention
It may have one low-temperature refrigeration circuit (3A), and conversely, three or more first low-temperature refrigeration circuits (3A, 3B,
...).

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram showing a main part of a high temperature side refrigeration circuit of the present invention.

FIG. 2 is a refrigerant circuit diagram showing a low-temperature side refrigeration circuit of the present invention.

FIG. 3 is a control flowchart showing a starting operation.

[Explanation of symbols]

 10 Binary refrigeration unit 11 Refrigerant heat exchanger 20 High temperature side refrigeration circuit (primary side refrigerant circuit) 21 Compressor 22 Condenser EV11 Expansion valve (expansion mechanism) 3A, 3B Low temperature side refrigeration circuit (secondary side refrigerant circuit) 31 Compression EV21 Expansion valve (expansion mechanism) 50 Evaporator 70 Controller 73 Primary start-up means 74 Secondary start-up means

Claims (3)

[Claims] 1. A compressor (21), a condenser (22), an expansion mechanism (EV11), and an evaporator of a refrigerant heat exchanger (11) are connected in order, and a primary refrigerant circulates. A primary refrigerant circuit (20), a compressor (31), and a condensing part of the refrigerant heat exchanger (11);
The expansion mechanism (EV21) and the evaporator (5a) are connected in order, so that the secondary refrigerant circulates and the primary and secondary refrigerants exchange heat in the refrigerant heat exchanger (11). In a binary refrigeration system provided with a secondary refrigerant circuit (3A), when a start signal is input, primary start means (73) for starting only the primary refrigerant circuit (20) based on the start signal.
And a primary-side refrigerant circuit (20) by the primary-side starting means (73).
Is activated, the secondary-side refrigerant circuit (3A) is activated when the refrigerant sucked into the compressor (21) in the primary-side refrigerant circuit (20) at least reaches a predetermined wet state. Means (74). 2. The two-way refrigeration system according to claim 1, wherein the secondary-side starting means (74) is configured to perform the first predetermined operation after the primary-side starting means (73) starts the primary-side refrigerant circuit (20). When the time has elapsed and the refrigerant sucked into the compressor (21) in the primary refrigerant circuit (20) has reached a predetermined wet state or a second predetermined time longer than the first predetermined time has elapsed, A binary refrigeration apparatus characterized by being configured to activate a secondary refrigerant circuit (3A). 3. The binary refrigeration system according to claim 1, wherein a plurality of refrigerant heat exchangers (11, 11) are provided, and the evaporating sections of each of the refrigerant heat exchangers (11, 11) are arranged in parallel with each other. The refrigerant heat exchangers (11, 11) are connected to secondary refrigerant circuits (3A, 3B), respectively, while being connected to form the primary refrigerant circuit (20). A binary refrigeration system, wherein an evaporator (5a, 5b) of a refrigerant circuit (3A, 3B) is integrally formed.