JP2000105011A - Equipment for dual refrigeration - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of times of startup of equipment for dual refrigeration and thereby to improve reliability. SOLUTION: Two refrigerant heat exchangers 11 are provided for a primary- side refrigerating circuit, and the primary-side refrigerating circuit is connected with a first circuit 3A and a second circuit 3B being a secondary-side refrigerant circuit, through the intermediary of these refrigerant heat exchangers 11. A controller 70 conducts prescribed controlling operations. In other words, it limits the number of times of restart to be conducted after an abnormality stop and prevents each refrigerant circuit (20, 3A, 3B) from being started uselessly. On the occasion of reducing cooling capacity, the second circuit 3B is stopped preferentially. When a high pressure of the first circuit 3A is boosted excessively, only the second circuit 3B is stopped. When only the state of the refrigerant in the second circuit 3B comes off from a normal state, besides, only the second circuit 3B is stopped. These operations being conducted, the operation of the first circuit 3A is made as continuous as possible. As a result, the number of times of startup of the first circuit 3A being operable for defrosting is reduced in particular.

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 having a plurality of secondary refrigerant circuits, and more particularly to a measure for improving reliability.

[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. This type of binary refrigeration apparatus is mainly used to cool the inside of a large freezer, a freezer warehouse, or a refrigerated warehouse.

[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, heat is exchanged between the primary refrigerant in the primary refrigerant circuit and the secondary refrigerant in the secondary refrigerant circuit.

Further, the above-mentioned two-way refrigeration system is provided with a sensor for detecting the refrigerant state of each refrigerant circuit, for example, the temperature and pressure of the refrigerant, and when an abnormality is detected, the operation is stopped to protect the device. On the other hand, such an abnormality in the state of the refrigerant is often temporary. Therefore, in the binary refrigeration apparatus, when an abnormality in the refrigerant state is detected, the operation is temporarily stopped, and then a retry operation of restarting is performed. In this way, the inside of the warehouse is kept cooled as much as possible to prevent the cargo in the warehouse from being damaged.

[0005]

However, conventionally,
In this type of binary refrigeration system, unlike a general building air conditioner, etc., control measures such as merely continuing the cooling operation were taken with an emphasis on cooling the cargo in the warehouse. Therefore, since no control measures were taken in response to the content of the abnormality,
As a result, there was a problem that the life of the device could not be extended and reliability was lacking.

More specifically, even when an abnormality such as a high-pressure abnormality occurs, the retry operation is repeated indefinitely. That is, even when a high pressure abnormality occurs due to a failure of the condenser fan, the retry operation is performed indefinitely without distinction from a temporary high pressure abnormality. For this reason, retry operation is repeated even though normal cooling operation can not be done unless the fan is repaired,
There has been a problem that a secondary trouble such as a compressor failure is caused by repeatedly stopping and restarting.

Further, there is a binary refrigeration system in which a plurality of secondary refrigerant circuits are connected to a primary refrigerant circuit. In this type of two-way refrigeration apparatus, the plurality of secondary-side refrigerant circuits are not necessarily configured to perform the same operation, and the operation of some of the secondary-side refrigerant circuits is different from the operation of the remaining circuits. There are cases.

Specifically, the inventors of the present application connect two primary refrigerant circuits to a primary refrigerant circuit to form a binary refrigeration apparatus, and integrate an evaporator of each secondary refrigerant circuit. To reduce the size (Japanese Patent Application No. Hei 10-1998).
99390). Also, only one secondary refrigerant circuit,
A reverse cycle defrost operation, in which the circulation direction of the refrigerant is reversed, is configured. This is because the evaporators of both the secondary refrigerant circuits are integrated, so that the entire evaporator can be defrosted even by the defrost operation by one of the secondary refrigerant circuits.

According to this, it is sufficient to add a configuration for the defrosting operation to only one of the secondary side refrigerant circuits, so that the entire apparatus can be simplified. However,
If the circuit capable of performing the defrost operation cannot be operated, the defrost operation cannot be performed. Therefore,
The secondary refrigerant circuit that performs operations that cannot be performed by other circuits, such as defrost operation, is more important than the other secondary refrigerant circuits in terms of the entire device, and such an important refrigerant circuit is particularly reliable. Security was needed.

However, conventionally, no control measures have been taken for this type of binary refrigeration system in accordance with the nature of the abnormality, resulting in a problem that the life of the system cannot be extended. Was. In other words, without distinguishing between the more important refrigerant circuit and the other refrigerant circuit as described above, if an abnormality occurs in any of the secondary refrigerant circuits, all the secondary refrigerant circuits are stopped and restarted. Was like that.

The present invention has been made in view of the above circumstances, and an object of the present invention is to improve the reliability by taking control measures corresponding to the contents of an abnormality.

[0012]

SUMMARY OF THE INVENTION The present invention provides a control measure for limiting the number of retries caused by an abnormality requiring repair, and an operation of a plurality of secondary-side refrigerant circuits that can operate differently from others. A control measure to be continued is taken, thereby improving the reliability of the apparatus.

More specifically, a first solution taken by the present invention is a compressor (21), a condenser (22), an expansion mechanism (EV)
12) and a plurality of evaporating units of a plurality of refrigerant heat exchangers (11, 11) arranged in parallel to each other are sequentially connected, and a primary refrigerant circuit (20) through which a primary refrigerant circulates, and a compressor (31) , The condensing section of each of the refrigerant heat exchangers (11, 11) and the expansion mechanism (EV21)
And the evaporator (50) are connected in order, so that the secondary refrigerant circulates and a plurality of secondary heat exchangers (11, 11) exchange heat between the primary refrigerant and the secondary refrigerant. It is premised on a binary refrigeration system including the secondary refrigerant circuits (3A, 3B). A refrigerant state detecting means (80) for detecting a refrigerant state in the primary refrigerant circuit (20) and each of the secondary refrigerant circuits (3A, 3B); and the primary refrigerant circuit (20) or the secondary refrigerant. When the refrigerant state in the circuit (3A, 3B) deviates from a predetermined normal state, the primary refrigerant circuit (20) or the secondary refrigerant circuit (3A, 3B) is temporarily stopped, and then the refrigerant circuit (20, 3A, 3B), and retry prohibiting means (78) for prohibiting the operation of the retry means (76) when the number of retries of the retry means (76) reaches a predetermined number. .

[0014] A second solution taken by the present invention is:
In the first solving means, the refrigerant state of the primary refrigerant circuit (20) and the secondary refrigerant circuit (3A, 3B) is in a normal state for a predetermined time after being restarted by the retry means (76). Is maintained, the subtraction means (77) for subtracting once from the number of retries of the retry means (76) is provided.

[0015] A third solution taken by the present invention is:
Compressor (21), condenser (22), expansion mechanism (EV12)
And a plurality of evaporators of a plurality of refrigerant heat exchangers (11, 11) arranged in parallel with each other are sequentially connected, and a primary refrigerant circuit (20) through which a primary refrigerant circulates, a compressor (31), and A condensing section of each refrigerant heat exchanger (11, 11), an expansion mechanism (EV21), and an evaporator (50) are connected in order, so that the secondary refrigerant circulates and the refrigerant heat exchangers described above. In (11, 11), a binary refrigeration apparatus including a plurality of secondary-side refrigerant circuits (3A, 3B) that exchange heat between the primary refrigerant and the secondary refrigerant is assumed. The plurality of secondary refrigerant circuits (3A, 3B)
The refrigeration capacity is adjusted by changing the number of the secondary refrigerant circuits (3A, 3B) that perform the refrigeration operation while comprising a first circuit (3A) and a second circuit (3B) having different operation operations. Priority control means (71) for performing the first circuit (3B) of the secondary-side refrigerant circuits (3A, 3B) when receiving the stop command signal of the capacity control means (71). Stopping means (7
2) is provided.

A fourth solution taken by the present invention is:
Compressor (21), condenser (22), expansion mechanism (EV12)
And a plurality of evaporators of a plurality of refrigerant heat exchangers (11, 11) arranged in parallel with each other are sequentially connected, and a primary refrigerant circuit (20) through which a primary refrigerant circulates, a compressor (31), and A condensing section of each refrigerant heat exchanger (11, 11), an expansion mechanism (EV21), and an evaporator (50) are connected in order, so that the secondary refrigerant circulates and the refrigerant heat exchangers described above. In (11, 11), a binary refrigeration apparatus including a plurality of secondary-side refrigerant circuits (3A, 3B) that exchange heat between the primary refrigerant and the secondary refrigerant is assumed. The plurality of secondary refrigerant circuits (3A, 3B)
While the first refrigerant circuit (3A) and the second circuit (3B) are different in operation, the secondary refrigerant circuit (3A, 3B)
When the refrigerant pressure on the high pressure side exceeds a predetermined value, an abnormality avoiding means (73) for stopping the second circuit (3B) is provided.

Further, a fifth solution taken by the present invention is:
Compressor (21), condenser (22), expansion mechanism (EV12)
And a plurality of evaporators of a plurality of refrigerant heat exchangers (11, 11) arranged in parallel with each other are sequentially connected, and a primary refrigerant circuit (20) through which a primary refrigerant circulates, a compressor (31), and A condensing section of each refrigerant heat exchanger (11, 11), an expansion mechanism (EV21), and an evaporator (50) are connected in order, so that the secondary refrigerant circulates and the refrigerant heat exchangers described above. In (11, 11), a binary refrigeration apparatus including a plurality of secondary-side refrigerant circuits (3A, 3B) that exchange heat between the primary refrigerant and the secondary refrigerant is assumed. The plurality of secondary refrigerant circuits (3A, 3B)
A first circuit (3A) and a second circuit (3B) having different operation behaviors, while detecting a refrigerant state in the primary refrigerant circuit (20) and each of the secondary refrigerant circuits (3A, 3B). When only the refrigerant state detecting means (80) and the refrigerant state of the second circuit (3B) deviate from the normal state, the second circuit (3B)
And a protection means (74) for stopping only the operation.

A sixth solution taken by the present invention is:
In any one of the third to fifth solving means, each of the secondary-side refrigerant circuits (3A, 3B) has an evaporating heat transfer tube (5a,
5b), and the evaporator (50) forms the heat transfer tubes for vaporization (5a, 5b) integrally and forms the first circuit (3).
A) is configured to perform a refrigeration operation and a defrost operation of the evaporator (50), and the second circuit (3B)
The refrigeration operation is performed.

In the first solution, the primary refrigerant discharged from the compressor (21) of the primary refrigerant circuit (20) is condensed by the condenser (22) to become a liquid refrigerant. After the pressure of the liquid refrigerant is reduced by the expansion mechanism (EV12), the liquid refrigerant flows to each of the refrigerant heat exchangers (11, 11). Thereafter, the primary refrigerant evaporates in each evaporating section of the refrigerant heat exchanger (11, 11), becomes a gas refrigerant, returns to the compressor (21), and repeats this circulation. In each of the secondary-side refrigerant circuits (3A, 3B), the secondary refrigerant discharged from the compressor (31) is condensed in the condensing section of the refrigerant heat exchanger (11, 11) and becomes liquid refrigerant. Become. After the pressure of the liquid refrigerant is reduced by the expansion mechanism (EV21), the liquid refrigerant evaporates in the evaporating heat transfer tubes (5a, 5b) to become a gas refrigerant, returns to the compressor (31), and repeats this circulation. In each of the refrigerant heat exchangers (11, 11), the primary refrigerant in the primary refrigerant circuit (20) exchanges heat with the secondary refrigerant in each of the secondary refrigerant circuits (3A, 3B). Heat is released from the refrigerant to the primary refrigerant, and the evaporator (5
In (0), the secondary refrigerant evaporates to generate cooling air, thereby cooling the inside of the refrigerator.

On the other hand, the refrigerant state detecting means (80) detects the refrigerant state such as the temperature and pressure of the refrigerant at predetermined locations in the primary side refrigerant circuit (20) and the secondary side refrigerant circuits (3A, 3B). . Further, when the refrigerant state detected by the refrigerant state detecting means (80) does not reach a predetermined normal state, the retry means (76) restarts the refrigerant circuit (20, 3A, 3B) after temporarily stopping it. When the number of retries reaches a predetermined number, the retry prohibiting means (78) prohibits the operation of the retry means (76) and suppresses the retry means (76) from operating excessively.

In the second solution, the refrigerant state is maintained in a normal state for a predetermined time after the retry means (76) restarts the refrigerant circuit (20, 3A, 3B). , The subtraction means (77) subtracts once from the number of retries of the retry means (76).

In the third solution, the primary refrigerant circuit (20) and the secondary refrigerant circuits (3A, 3B) are connected to the first refrigerant circuit.
Operates in the same manner as in the first aspect of the invention, and generates cooling air by evaporating the secondary refrigerant in the evaporator (50) to cool the inside of the refrigerator. At this time, the first refrigerant circuit constituting the secondary refrigerant circuit (3A, 3B)
The circuit (3A) and the second circuit (3B) perform the same refrigeration operation, but the first circuit (3A) is configured to be capable of operation other than the refrigeration operation.

On the other hand, the capacity control means (71) adjusts the refrigerating capacity by changing the number of operated secondary refrigerant circuits (3A, 3B), and outputs a stop command signal when the refrigerating capacity is reduced. I do. In response to the stop command signal, priority stop means (72)
Causes the second circuit (3B) to stop with priority. As a result, the first circuit (3A) is operated as continuously as possible.

[0024] In the fourth solution, the primary refrigerant circuit (20) and the secondary refrigerant circuits (3A, 3B) are connected to the first refrigerant circuit.
Operates in the same manner as in the first aspect of the invention, and generates cooling air by evaporating the secondary refrigerant in the evaporator (50) to cool the inside of the refrigerator. At this time, the first refrigerant circuit constituting the secondary refrigerant circuit (3A, 3B)
The circuit (3A) and the second circuit (3B) perform the same refrigeration operation, but the first circuit (3A) is configured to be capable of operation other than the refrigeration operation.

On the other hand, when the high pressure of the secondary refrigerant circuit (3A, 3B) exceeds a predetermined value, the abnormality avoiding means (73) sets the second
Stop the circuit (3B). That is, if the high pressure of the second circuit (3B) becomes too high, the second circuit (3B) is stopped,
The second circuit (3B) is prevented from operating in an abnormal operating state. Further, even if the high pressure of the first circuit (3A) becomes too high, the second circuit (3B) is stopped. As a result, the number of operated secondary refrigerant circuits (3A, 3B) is reduced, and the secondary refrigerant circuit (11, 11) that exchanges heat with the refrigerant of the primary refrigerant circuit (20) in the refrigerant heat exchangers (11, 11). 3A, 3B) The amount of refrigerant decreases. For this reason, the amount of heat released from the refrigerant in the first circuit (3A) is secured, and the high-pressure pressure in the first circuit (3A) decreases. Therefore, the operation of the first circuit (3A) in an abnormal operation state is avoided while the operation of the first circuit (3A) is continued.

In the fifth solution, the primary refrigerant circuit (20) and the secondary refrigerant circuits (3A, 3B) are connected to the first refrigerant circuit (3A, 3B).
Operates in the same manner as in the first aspect of the invention, and generates cooling air by evaporating the secondary refrigerant in the evaporator (50) to cool the inside of the refrigerator. At this time, the first refrigerant circuit constituting the secondary refrigerant circuit (3A, 3B)
The circuit (3A) and the second circuit (3B) perform the same refrigeration operation, but the first circuit (3A) is configured to be capable of operation other than the refrigeration operation.

On the other hand, the refrigerant state detecting means (80) detects the refrigerant state such as the temperature and pressure of the refrigerant at predetermined locations in the primary refrigerant circuit (20) and the secondary refrigerant circuits (3A, 3B). . When only the refrigerant state of the second circuit (3B) is out of the normal state among the refrigerant states detected by the refrigerant state detection means (80), the protection means (74) activates the second circuit (3).
B) to stop. This prevents the second circuit (3B) from operating in an abnormal operating state, while keeping the operation of the primary refrigerant circuit (20) and the first circuit (3A) to cool the inside of the refrigerator and the like. Do.

In the sixth solution, the first circuit (3A) performs the freezing operation and the defrost operation, and the second circuit (3B) performs the freezing operation. On the other hand, the evaporator (50) is formed by integrally assembling the heat transfer tubes (5a, 5b) for evaporation of the secondary refrigerant circuits (3A, 3B). Therefore, even when only the first circuit (3A) performs the defrost operation operation, the entire evaporator (50) is defrosted.

[0029]

Therefore, according to the first and second means, the number of retries of the retry means (76) can be limited to within a predetermined number. For this reason, if there is no expectation of recovery even after some time, and it is considered that an abnormality requiring repair has occurred, the operation of the retry means (76) is prohibited and the primary refrigerant circuit (20) and the secondary Refrigerant circuit (3
A, 3B) can be avoided. As a result, the primary refrigerant circuit (20) and the secondary refrigerant circuit (3A, 3B)
Can reduce the chances of being operated in an unstable transient state after startup, prevent secondary troubles, and improve reliability.

In particular, according to the second solving means, if the retry means (76) restarts the normal operation after the restart, the restart is useless and the operation of the retry means (76) is not effective. It can be reliably distinguished from the case where it should be prohibited. As a result, when restarting is performed, restarting is performed and refrigeration operation is continuously performed as much as possible. When restarting is not to be performed, the operation of the retry means (76) is prohibited and the primary refrigerant circuit (20) is disabled. Further, occurrence of secondary troubles in the secondary refrigerant circuits (3A, 3B) can be suppressed.

According to the third to fifth solutions, the first circuit (3B) which operates differently from the second circuit (3B).
The operation of A) can be continued as much as possible, the reliability of the first circuit (3A) can be surely improved, and the reliability of the device can be improved.

That is, in the third solution, when the secondary refrigerant circuits (3A, 3B) are stopped in order to reduce the refrigerating capacity, all the secondary refrigerant circuits (3A, 3B) are once operated. Instead, the priority stop means (72) gives priority to stopping the second circuit (3B). Further, in the fourth solution, even when the high pressure of the first circuit (3A) becomes too high, the second circuit (3B) is kept operating while the first circuit (3A) is operating.
Is stopped to reduce the high pressure of the first circuit (3A). In the fifth solution,
When the refrigerant state of only the second circuit (3B) deviates from the normal state, the protection means (74) stops only the second circuit (3B) to protect the second circuit (3B), The operation of the first circuit (3A) in the normal state is continued. Therefore, the operation of the first circuit (3A) can be continued as much as possible, and the number of times the first circuit (3A) is started can be reduced.

In the sixth solution, the evaporator (50) of each of the secondary refrigerant circuits (3A, 3B) is integrally formed. For this reason, the first of the secondary refrigerant circuits (3A, 3B)
By configuring only the circuit (3A) so that the defrost operation can be performed, the entire evaporator (50) can be defrosted, and the apparatus can be simplified. This evaporator (5
Since the defrost of 0) is an indispensable operation of the refrigeration system, higher reliability is required for the first circuit (3A). On the other hand, by applying the third to fifth solutions, the reliability of the first circuit (3A) can be reliably ensured, and the reliability of the device can be improved.

[0034]

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. Although not shown, each of the units (1A, 1B, 1C) is formed by housing a component device in a predetermined casing. The outdoor unit (1A) and a part of the cascade unit (1B) constitute a primary refrigerant circuit (20). In addition, the two secondary refrigerant circuits (3A, 3B) extend over the cascade unit (1B) and the cooling unit (1C).
Is configured. In addition, the cooling unit (1
In C), a not-shown inside temperature sensor for detecting the inside temperature is provided.

-Configuration of Refrigerant Circuit- The primary refrigerant circuit (20) is configured to be capable of reversible operation by switching the refrigerant circulation direction between a forward cycle and a reverse cycle. The primary refrigerant circuit (20) includes a compressor (21), a condenser (22), and two refrigerant heat exchangers (11, 11).
And an evaporator. This refrigerant heat exchanger (11,11)
Constitutes an evaporator of the primary refrigerant circuit (20). Although not shown, the outdoor unit (1A) is provided with an outdoor fan driven by a fan motor,
The outdoor fan sends air to the condenser (22).

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). Also,
The first gas pipe (4) between the compressor (21) and the oil separator (23)
0) is equipped with a discharge pipe temperature sensor (TDH). One end of a liquid pipe (42) is connected to the other end of the condenser (22), and the liquid pipe (42) is formed by a main pipe (4a) and two branch pipes (4b, 4c). I have. And
Each of the branch pipes (4b, 4c) has two refrigerant heat exchangers (11, 11).
Are connected to each evaporating section.

The main pipe (4a) of the liquid pipe (42) connects the condenser (22) to the electric expansion valve for defrost (EV11) and the receiver (25) in order. On the other hand, the above-mentioned branch pipes (4b, 4c) have an electric expansion valve for cooling (EV1
2) is provided.

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 evaporators of the two refrigerant heat exchangers (11, 11) are connected in parallel to each other in the primary refrigerant 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 (SV), and is configured to perform high-pressure control during a cooling operation and venting during a defrost 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 (SV) 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).

On the other hand, the first circuit (3A) is configured to be capable of reversible operation by switching the refrigerant circulation direction between a forward cycle and a reverse cycle. The first circuit (3A) includes a compressor (31), a condensing section of the first refrigerant heat exchanger (11), and a heat transfer tube for evaporation (5a). This refrigerant heat exchanger (1
The condenser section 1) constitutes the condenser of the first circuit (3A).

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. Further, a discharge pipe temperature sensor (TDL) is attached to the first gas pipe (60) between the compressor (31) and the oil separator (32). The other end of the condenser section is connected to the check valve (CV) and the receiver (3
It is connected to one end of the heat transfer tube for evaporation (5a) via 4) and a cooling expansion valve (EV21) as an expansion mechanism. The other end of the heat transfer tube for evaporation (5a) is connected to a check valve (CV), a four-way switching valve (33) and an accumulator (35) by a second gas pipe (62).
And is connected to the suction side of the compressor (31).

The first refrigerant heat exchanger (11) is a cascade condenser having an evaporating part of the primary refrigerant circuit (20) and a condensing part of the first circuit (3A). It is constituted by. In the first refrigerant heat exchanger (11), the refrigerant in the first circuit (3A) exchanges heat with the refrigerant in the primary refrigerant circuit (20), and the refrigerant in the first circuit (3A) radiates heat. The refrigerant in the primary refrigerant circuit (20) absorbs heat and evaporates.

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 evaporation heat transfer tube (5a). Is provided.

Since the first circuit (3A) is configured to perform a reverse cycle defrost operation, a drain pan passage (63), a gas bypass passage (64), and a pressure reduction passage (6) are provided.
5). The drain pan passage (63) is
A drain pan heater (6a) and a check valve (CV) are provided, connected to both ends of the check valve (CV) in the gas passage (62), and refrigerant (hot gas) discharged from the compressor (31) flows. It is configured as follows.

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 includes an on-off valve (SV) and an expansion valve for defrost (EV22). It is configured to depressurize the refrigerant. The expansion valve for defrost (EV22) is a temperature-sensitive expansion valve,
A temperature sensing cylinder is provided in the second gas pipe (62) upstream of the accumulator (35).

An upper end of the receiver (34) is connected to one end of a gas vent passage (66). The gas vent passage (66) is provided with an on-off valve (SV) and a capillary tube (C
P), and the other end is connected to the second gas pipe (62) on the upstream side 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 the 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 circuit (3B) has substantially the same configuration as the first circuit (3A), but is configured to perform only the cooling operation without performing the defrost operation. The second circuit (3B) does not include the four-way switching valve (24) in the first circuit (3A), and furthermore, the drain pan passage (63), the gas bypass passage (64), and the pressure reducing passage (65) Not provided. That is, the second circuit (3B) includes a condenser (31), a condenser of the second refrigerant heat exchanger (11), a receiver (34), a cooling expansion valve (EV21), and an evaporating heat transfer tube (5b). ) And an accumulator (35) are sequentially connected by a first gas pipe (60), a liquid pipe (61), and a second gas pipe (62). The condenser of the second refrigerant heat exchanger (11) constitutes the condenser of the second circuit (3B). The second circuit (3
Similarly to the first circuit (3A), the discharge pipe temperature sensor (TDL), the high pressure sensor (SPH1), the low pressure sensor (SPL1), and the high pressure switch (HPS1) are located at predetermined positions. Is provided.

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. The second refrigerant heat exchanger (11) is a cascade condenser having an evaporator of the primary refrigerant circuit (20) and a condenser of the second circuit (3B). It is configured. The second refrigerant heat exchanger (11)
The refrigerant in the circuit (3B) exchanges heat with the refrigerant in the primary refrigerant circuit (20), and the refrigerant in the second circuit (3B) releases heat and condenses, while the refrigerant in the primary refrigerant circuit (20) absorbs heat. And evaporate.

The evaporating heat transfer tubes (5a, 5b) in the two secondary-side refrigerant circuits (3A, 3B) are constituted by one evaporator (50). The refrigerant in the side refrigerant circuit (3A, 3B) exchanges heat with the air in the refrigerator or the freezer. The evaporator (50), the cooling expansion valve (EV21) and the drain pan passage (63) are provided in the cooling unit (1C), while another compressor (31) is provided in the cascade unit (1B). Have been. Although not shown, the cooling unit (1C) is provided with an internal fan driven by a fan motor,
The in-compartment fan sends the in-compartment air to the evaporator (50).

While the heat transfer tubes for evaporation (5a, 5b), the expansion valve for cooling (EV21) and the drain pan passage (63) in the two secondary refrigerant circuits (3A, 3B) are provided in the cooling unit (1C), Another compressor (31) and the like are provided in the cascade unit (1B).

The evaporative heat transfer tubes (5a, 5b) of the two secondary-side refrigerant circuits (3A, 3B) are constituted by one evaporator (50) as shown in FIGS. Specifically, the evaporative heat transfer tubes (5a, 5b) of each of the secondary-side refrigerant circuits (3A, 3B) have n
The evaporator (50) is formed by 2n evaporating heat transfer tubes (5a, 5b), that is, is constituted by 2n paths. And each of the above secondary refrigerant circuits (3A, 3B)
The evaporating heat transfer tubes (5a, 5b) have flow inlets (51, 52)
And the outflow end is connected to the header (53, 54).

Evaporating heat transfer tube (5a) of the first circuit (3A)
And the heat transfer tubes for evaporation (5b) of the second circuit (3B) are arranged so as to be mixed with each other, and in this embodiment, are arranged so as to be alternately repeated in the vertical direction. Further, one of the evaporative heat transfer tubes (5a) of the first circuit (3A) for performing the defrost operation is arranged at the lowest stage. That is, during the defrost operation, the molten water flows downward, so that the first
The evaporative heat transfer tube (5a) of the circuit (3A) is arranged at the bottom.

In the first circuit (3A), a liquid temperature sensor (Th21) for detecting the temperature of the liquid refrigerant is provided before the flow divider (51) of the liquid pipe (61), while the evaporator is provided. (50) is provided with an evaporator temperature sensor (Th22) for detecting the temperature of the evaporator (50). The pressure sensors (SPH1, SPL1, SPH2, SPL2) and the temperature sensors (TDH, TDL,...) Provided in the primary refrigerant circuit (20) and the secondary refrigerant circuits (3A, 3B) are in a refrigerant state. It constitutes the detection means (80).

-Configuration of Controller- As shown in FIGS. 2 and 4, the binary refrigeration apparatus (10) of the present embodiment includes a controller (70) which is a feature of the present invention. The controller (70) includes a capacity control unit (71), a start / stop control unit (72), an overload avoidance unit (73),
The circuit includes a circuit protection unit (74), a restart unit (75), a retry counting unit (77), and a retry prohibition unit (78). Also,
To the controller (70), the detection values of the sensors (SPH1, SPH2,..., TDH, TDL,...) Constituting the refrigerant state detecting means (80) are input.

The internal temperature detected by the internal temperature sensor and a set internal temperature are input to the capacity control section (71). Then, the capacity control unit (71) changes the number of operated secondary-side refrigerant circuits (3A, 3B) based on the measured value of the internal temperature and the set value, and ) Is configured as capacity control means for adjusting the refrigeration capacity. Specifically, when the measured value of the internal temperature decreases and approaches the set value, a stop command signal is output in order to reduce the refrigeration capacity, while the measured value of the internal temperature rises from the set value. When the vehicle comes away, it is configured to output an operation command signal in order to increase the refrigeration capacity.

The start / stop control section (72) receives the stop command signal and the operation command signal of the capacity control section (71). The start / stop control unit (72) is configured as a priority stop unit that gives priority to stopping the second circuit (3B) when receiving the stop command signal, and enables the defrost operation when receiving the operation command signal. The first circuit (3A) is configured to operate with priority.

The overload avoiding unit (73) is configured to operate the second circuit (3H) when the detected value of the high pressure sensor (SPH2) of any of the first circuit (3A) and the second circuit (3B) exceeds a predetermined value. 3B) is configured as an abnormality avoiding means for stopping the operation.

The circuit protection section (74) is connected to the second circuit (3B)
Protection means for stopping only the second circuit (3B) when the refrigerant state of the first refrigerant circuit (3B) deviates from the normal state, and when the refrigerant state of the first circuit (3A) or the primary refrigerant circuit (20) deviates from the normal state. The entire binary refrigeration system (10) is configured to be stopped. Specifically, the circuit protection unit (74) detects any one of the detected values of the high-pressure pressure sensor (SPH2), the low-pressure pressure sensor (SPL2), and the discharge pipe temperature sensor (TDL) provided in the second circuit (3B). When the value deviates from the predetermined normal range, only the second circuit (3B) is stopped. The high pressure sensor (SPH2) and the low pressure sensor (SPH) provided in the first circuit (3A)
L2) or any of the detected values of the discharge pipe temperature sensor (TDL),
Alternatively, if any of the detection values of the high-pressure pressure sensor (SPH1), the low-pressure pressure sensor (SPL1), and the discharge pipe temperature sensor (TDH) provided in the primary refrigerant circuit (20) deviates from a predetermined normal range, a binary Stop the entire refrigeration system (10).

When the refrigerant state of the refrigerant circuit (20, 3A, 3B) stopped by the circuit protection section (74) returns to the normal state, the restart section (75) restarts the refrigerant circuit (20, 3A, 3A). 3B) is configured to restart. Specifically, when the detection value of the high pressure sensor (SPH2) of the second circuit (3B) exceeds a predetermined value,
The circuit protection section (74) stops the second circuit (3B).
Thereafter, the pressure in the second circuit (3B) is equalized, and the detection value of the high pressure sensor (SPH2) also decreases. When the detection value of the high pressure sensor (SPH2) falls within the normal range, the restart unit (75) restarts the second circuit (3B). When the circuit protection unit (74) stops the entire binary refrigeration system (10), when the refrigerant state returns to the normal state, the restart unit (7
5) Restart the entire binary refrigeration system (10). The circuit protection section (74) and the restart section (75) are connected to the retry means (7
6) Make up.

The retry counting section (77) counts the number of retries restarted by the restart section (75) in the primary refrigerant circuit (20), the first circuit (3A) and the second circuit (3B). It is configured to count each of them. Further, the retry counting unit (77), when the refrigerant state of each refrigerant circuit (20, 3A, 3B) is maintained in a normal state for a predetermined time,
It is configured to subtract one from the number of retries of the refrigerant circuit (20, 3A, 3B). Therefore, the retry counting section (77) constitutes a subtraction means.

The retry prohibiting section (78) is configured as retry prohibiting means for prohibiting the operation of the restart section (75) when the number of retries counted by the retry counting section (77) reaches a predetermined number. That is, the retry prohibition unit (7
In 8), the restart unit (75) is operated a predetermined number of times.

-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 primary refrigerant circuit (20) and both the secondary refrigerant circuits (3A, 3A)
B) The two compressors (31, 31) are driven together. In this state, in the primary refrigerant circuit (20), the four-way switching valve (24) is switched to the solid line in FIG. 1, the electric expansion valve for defrost (EV11) is fully opened, and the electric expansion valve for cooling (EV1) is opened.
2) control the opening.

The compressor (21) of the primary refrigerant 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). The liquid refrigerant is divided into two branch pipes (4b, 4c), and after being decompressed by the electric cooling expansion valve (EV12), evaporates in each evaporator of the two refrigerant heat exchangers (11, 11). . Thereafter, the gas refrigerant returns to the compressor (21) from each of the evaporating sections, and repeats this circulation.

On the other hand, in the first circuit (3A), the four-way switching valve (33) is switched to the solid line in FIG. 2, the defrost expansion valve (EV22) is fully closed, and the cooling expansion valve (EV21) is overheated. Control the degree. In the second circuit (3B), the degree of superheat of the cooling expansion valve (EV21) is controlled.

In the two secondary-side refrigerant 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) and becomes a liquid refrigerant. After the pressure of the liquid refrigerant is reduced by the cooling expansion valve (EV21), the liquid refrigerant is evaporated by the evaporating heat transfer tubes (5a, 5b). Then, the gas refrigerant returns from the heat transfer tubes for evaporation (5a, 5b) to the compressor (31, 31), and repeats this circulation.

In the refrigerant heat exchangers (11, 11), the primary refrigerant and the secondary refrigerant exchange heat, and the secondary refrigerant in the secondary refrigerant circuits (3A, 3B) is cooled and condensed. I do. 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 defrosting operation is performed by stopping the operation of the second circuit (3B) and reversing the circulation direction of the refrigerant between the first circuit (3A) and the primary refrigerant circuit (20).

Specifically, in the first circuit (3A), the four-way switching valve (33) is switched to the broken line in FIG. 2, while the degree of superheat of the defrost expansion valve (EV22) is controlled and the cooling expansion valve (EV21) is controlled. )
Is fully closed.

The secondary refrigerant discharged from the compressor (31) passes through the drain pan passage (63) through the four-way switching valve (33), 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 evaporation heat transfer tube (5a) flows through the gas bypass passage (64), flows through the receiver (34), flows through the pressure reduction passage (65), and then flows through the defrost expansion valve (EV2).
Reduce the pressure in 2). Subsequently, the secondary refrigerant evaporates in the condensing section of the refrigerant heat exchanger (11), returns to the compressor (31) via the four-way switching valve (33) and the accumulator (35), and repeats this circulation. .

On the other hand, in the primary refrigerant circuit (20), the four-way switching valve (24) is switched to the dashed line in FIG. 1, while the opening of the defrost electric expansion valve (EV11) is controlled, and the cooling electric expansion valve is operated. (EV12) fully open.

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 in the first circuit (3A). Thereafter, the primary refrigerant flowing through the evaporator of the refrigerant heat exchanger (11) passes through the receiver (25) and is depressurized by the electric defrost expansion valve (EV11). Subsequently, the primary refrigerant evaporates in the condenser (22), returns to the compressor (21) via the four-way switching valve (24) and the accumulator (26), and repeats this circulation.

In the above defrost operation, the liquid temperature sensor (Th21) detects the refrigerant temperature of, for example, 10 ° C., or the evaporator temperature sensor (Th22) detects the evaporator temperature of, for example, 20 ° C. Alternatively, when the high-pressure pressure sensor (SPH2) of the first circuit (3A) detects a high-pressure refrigerant pressure of, for example, 18 kgf / cm ² , the process ends. Note that the above defrost operation ends even with a one-hour guard timer.

In the cooling operation in addition to the defrost operation, the on-off valve (SV) of the gas vent passage (66) in each of the secondary refrigerant circuits (3A, 3B) is opened, and the liquid stored in the receiver (34) is opened. The refrigerant is returned to the low-temperature side compressor (31).

Further, when the pressure of the high-pressure refrigerant detected by the high-pressure pressure sensor (SPH1) decreases during the cooling operation, the gas passageway (43) in the primary-side refrigerant circuit (20) becomes, for example, 6 kgf / cm ^2. When the pressure drops, the on-off valve (SV) is opened, high-pressure refrigerant is supplied to the receiver (25), and the high-pressure refrigerant pressure is increased. When the pressure of the high-pressure refrigerant increases, for example, to 15 kgf / cm ² , the opening of the on-off valve (SV)
finish.

During the defrost operation, the on-off valve (SV) of the gas passage (43) is opened and the receiver (25) is opened.
Is returned to the high-temperature side compressor (21) so that the liquid refrigerant accumulates in the receiver (25). That is, during the defrost operation, the liquid refrigerant is stored in the receiver (25) even when the outside air temperature is high.

Next, the control operation of the binary refrigeration system (10) by the controller (70) will be described.

The capacity control section (71) outputs a stop command signal and an operation command signal for adjusting the refrigerating capacity, and upon receiving the command signal, the start / stop control section (72) causes the primary side refrigerant circuit to operate. (20) and each of the secondary refrigerant circuits (3A, 3B) is stopped and started.

Specifically, as shown in FIG. 5, the set temperature in the refrigerator is Ts, and the temperature detected in the refrigerator by the temperature sensor in the refrigerator is Ts +
Description will be made from a state higher than a1. In this state, all the refrigerant circuits of the binary refrigeration system (10), that is, the primary refrigerant circuit (20), the first circuit (3A) and the second circuit (3B) are operated. Thereafter, when the internal temperature gradually decreases to Ts + a1, the capacity control unit (71) outputs a stop command signal, and in response thereto, the start / stop control unit (72) gives priority to the second circuit (3B). To stop. Then, when the temperature in the refrigerator further decreases and the temperature in the refrigerator reaches the set temperature Ts, the capacity control unit (71) outputs a stop command signal again, and in response thereto, the start / stop control unit (7
2) stops the first circuit (3A) and the primary refrigerant circuit (20).

Subsequently, when the temperature inside the refrigerator gradually rises and the temperature detected by the refrigerator inside the refrigerator reaches Ts + a2, the capacity control unit (71) outputs an operation command signal. The part (72) is the first circuit (3A) and the primary refrigerant circuit (20)
Is started with priority. Thereafter, when the internal temperature further rises to Ts + a3, the capacity control unit (71) outputs an operation command signal again, and in response thereto, the start / stop control unit (72) activates the second circuit (3B). .

When the refrigerant state detected by each of the sensors (SPH1, SPH2,..., TDH, TDL,...) Of the refrigerant state detection means (80) is out of the normal range, the overload avoiding section (73) Circuit protection part (74), restart part (75), retry counting part (7
7) and the retry prohibition unit (78) perform a predetermined operation to protect the binary refrigeration system (10). This operation will be described as an example when the refrigerant state of the primary refrigerant circuit (20) is out of the normal range.

The operation of controlling the high pressure of the primary refrigerant circuit (20) will be described with reference to the flowchart of FIG. When the operation is started in step ST1a, in steps ST2a and ST3a, the circuit protection unit (74) determines whether the high pressure of the primary refrigerant circuit (20) is in a normal range. Specifically, in step ST2a, it is determined whether the detected value of the high pressure sensor (SPH1) is higher than 25 kgf / cm ² , that is, whether the condensing temperature of the primary refrigerant is higher than 62 ° C. If higher, the process proceeds to step ST3a. In step ST3a, it is further determined whether or not the detected value of the high pressure sensor (SPH1) is higher than 26.5 kgf / cm ² , that is, whether or not the condensation temperature of the primary refrigerant is higher than 65 ° C. If it is, the process moves to step ST4a.

In step ST4a, it is determined whether or not the compressor (21) is unloaded and the outdoor fan has a maximum air flow.
If none of the above states is satisfied, then step ST5a
Then, the on-off valve (SV) of the unload circuit (45) is opened to unload the compressor (21), and the airflow of the outdoor fan is maximized. After that, the process proceeds to step ST6a to perform normal operation control.

In step ST3a, the condensation temperature of the primary refrigerant is 65
If it is higher than ° C, or already in step ST4a, the compressor (21)
Moves to step ST7a when is not unloaded and the airflow of the outdoor fan is the maximum. In step ST7a,
The retry counting section (77) adds one to the number of retries of the primary refrigerant circuit (20).

Next, the process proceeds to step ST8a. If the number of retries has not reached 5, the circuit protection section (74) switches the primary refrigerant circuit (20) and the secondary refrigerant circuit (3A, 3B). Stop and enter the standby state. Thereafter, when the pressure in the primary refrigerant circuit (20) is equalized and the detection value of the high-pressure pressure sensor (SPH1) returns to the normal range, the restart unit (75) restarts the primary refrigerant circuit (20) and the secondary refrigerant. Restart the circuit (3A, 3B).
If the number of retries has reached 5 in step ST8a, the process proceeds to step ST9a, where the retry prohibition unit (78)
Prohibits the operation of the restart unit (75), and the circuit protection unit (74) stops the primary-side refrigerant circuit (20) and the secondary-side refrigerant circuits (3A, 3B).

On the other hand, if the condensing temperature of the primary refrigerant is 62 ° C. or lower in step ST2a, the process moves to step ST10a, and every time this operation state continues for 30 minutes, the retry counting section (77) sets the primary refrigerant circuit ( Subtract once from the number of retries in step 20). If the number of retries is zero, no subtraction is performed. After that, the process proceeds to step ST6a to perform normal operation control.

The operation of controlling the temperature of the discharge pipe of the compressor (21) of the primary refrigerant circuit (20) will be described with reference to the flowchart of FIG. When the operation starts in step ST1b,
In step ST2b, the circuit protection unit (74) determines whether the discharge pipe temperature is within a normal range. Specifically, in step ST2b, the detection value of the discharge pipe temperature sensor (TDH) is 1
It is determined whether it is higher than 30 ° C., and if it is higher than 130 ° C., the process proceeds to step ST3b.

In step ST3b, it is determined whether or not the compressor (21) is unloaded and the air flow of the outdoor fan is maximum.
If none of the above states is satisfied, then step ST4b
Then, the on-off valve (SV) of the unload circuit (45) is opened to unload the compressor (21), and the airflow of the outdoor fan is maximized. Thereafter, the process proceeds to step ST5b to perform normal operation control.

If the compressor (21) is unloaded and the air flow rate of the outdoor fan is the maximum in step ST3b, the process proceeds to step ST6b. In step ST6b, the retry counting section (77) adds one to the number of retries of the primary refrigerant circuit (20).

Next, the process proceeds to step ST7b. If the number of retries has not reached five, the circuit protection section (74) switches the primary refrigerant circuit (20) and the secondary refrigerant circuit (3A, 3B). Stop and enter the standby state. Thereafter, when the discharge pipe temperature decreases and the detection value of the discharge pipe temperature sensor (TDH) returns to the normal range, the restart unit (75) restarts the primary-side refrigerant circuit (20) and the secondary-side refrigerant circuit (3A, 3B) Restart. If the number of retries has reached 5 in step ST7b, the process proceeds to step ST8b, where the retry prohibition unit (78) prohibits the operation of the restart unit (75) and the circuit protection unit (74).
Is the primary refrigerant circuit (20) and the secondary refrigerant circuit (3A, 3B)
To stop.

On the other hand, in step ST2b, the discharge pipe temperature becomes 1
If the temperature is 30 ° C. or lower, the process proceeds to step ST9b, and every time this operation state continues for 30 minutes, the retry counting unit (7
7) subtracts once from the number of retries of the primary refrigerant circuit (20). If the number of retries is zero, no subtraction is performed. Thereafter, the process proceeds to step ST5b to perform normal operation control.

The operation for controlling the low pressure of the primary refrigerant circuit (20) will be described with reference to the flowchart of FIG. When the operation is started in step ST1c, in step ST2c and step ST3c, the circuit protection unit (74) determines whether the low pressure of the primary refrigerant circuit (20) is in a normal range. Specifically, in step ST2c, it is determined whether or not the detected value of the low-pressure pressure sensor (SPL1) is lower than 0.5 kgf / cm ² , that is, whether or not the primary refrigerant evaporation temperature is lower than −32 ° C. If it is lower than 32 ° C., the process moves to step ST3c. In step ST3c,
Further, it is determined whether or not the detection value of the high pressure sensor (SPH1) is lower than 12 kgf / cm ² , that is, whether or not the condensing temperature of the primary refrigerant is lower than 33 ° C.
Then, normal operation control is performed.

At step ST3c, the condensation temperature of the primary refrigerant is 33
If it is not less than ° C, the process moves to step ST5c. Steps
In ST5c, it is determined whether the compressor (21) is at full load. When the compressor (21) is unloaded, the process proceeds to step ST6c, where the on-off valve (SV) of the unload circuit (45) is closed to load the compressor (21) at full load. After that, the process proceeds to step ST4c to perform normal operation control.

If the compressor (21) is at full load in step ST5c, the process moves to step ST7c. Steps
In ST7c, the retry counting section (77) adds one to the number of retries of the primary refrigerant circuit (20).

Next, the process proceeds to step ST8c. If the number of retries has not reached 5, the circuit protection section (74) switches the primary refrigerant circuit (20) and the secondary refrigerant circuit (3A, 3B). Stop and enter the standby state. Thereafter, when the pressure in the primary refrigerant circuit (20) is equalized and the detection value of the low-pressure pressure sensor (SPL1) returns to the normal range, the restart unit (75) restarts the primary refrigerant circuit (20) and the secondary refrigerant. Restart the circuit (3A, 3B).
If the number of retries has reached 5 in step ST8c, the process proceeds to step ST9c, where the retry prohibiting unit (78)
Prohibits the operation of the restart unit (75), and the circuit protection unit (74) stops the primary-side refrigerant circuit (20) and the secondary-side refrigerant circuits (3A, 3B).

On the other hand, if the evaporation temperature of the primary refrigerant is equal to or higher than -32 ° C. in step ST2c, the operation proceeds to step ST10c, and every time this operation state continues for 30 minutes, the retry counting section (77) sets the primary refrigerant circuit 1 from the number of retries in (20)
Subtract twice. If the number of retries is zero, no subtraction is performed. After that, the process proceeds to step ST4c to perform normal operation control.

The operation of controlling the high pressure of the first circuit (3A) as the secondary refrigerant circuit will be described with reference to the flowchart of FIG. When the operation starts in step ST1d, in steps ST2d and ST3d, the circuit protection unit (7
4) determines whether the high voltage of the first circuit (3A) is within a normal range. Specifically, in step ST2d, it is determined whether or not the detection value of the high pressure sensor (SPL1) of the first circuit (3A) is higher than 24 kgf / cm ² , that is, the condensation temperature in the first circuit (3A) is 61 ° C.
It is determined whether the temperature is higher or not. If the temperature is lower than 61 ° C., the process proceeds to step ST3d.

In step ST3d, it is further determined whether or not the detected value of the high pressure sensor (SPL1) is higher than 22 kgf / cm ² , that is, whether or not the condensation temperature in the first circuit (3A) is higher than 57 ° C. If the temperature lower than 57 ° C. continues for one second, the process proceeds to step ST4d. In step ST4d, the overload avoiding unit (73) stops the second circuit (3B), and then proceeds to step ST5d to perform normal operation control.

In step ST2d, the condensation temperature of the primary refrigerant is set to 61
If the temperature higher than ℃ continues for 1 second, step ST
Move to 9d. In step ST9d, the retry counting unit (7
7) adds once to the number of retries of the first circuit (3A).

Next, the process shifts to step ST10d. If the number of retries does not reach five, the circuit protection unit (74)
Is the primary refrigerant circuit (20) and the secondary refrigerant circuit (3A, 3B)
Is stopped to enter a standby state. Then, the first circuit (3A)
When the internal pressure is equalized and the detection value of the high pressure sensor (SPL1) returns to the normal range, the restart unit (75) starts the primary refrigerant circuit (20).
And restart the secondary refrigerant circuit (3A, 3B). Also,
If the number of retries has reached 5 in step ST10d, the process proceeds to step ST11d, where the retry prohibition unit (78) prohibits the operation of the restart unit (75), and the circuit protection unit (74) operates on the primary side. The refrigerant circuit (20) and the secondary refrigerant circuits (3A, 3B) are stopped.

If the condensation temperature in the first circuit (3A) is 57 ° C. or lower in step ST3d, the process proceeds to step ST6d.
In step ST6d, it is determined whether or not the detected value of the high pressure sensor (SPL1) is lower than 10 kgf / cm ² , that is, the first circuit (3A)
It is determined whether the condensation temperature is lower than 26 ° C.
If it is equal to or higher than 6 ° C., the process proceeds to step ST5d to perform normal operation control. On the other hand, when the condensation temperature in the first circuit (3A) is 26
If the state of lower than ° C. continues for one second, the process moves to step ST6d. In step ST6d, the second circuit (3B) is restarted. Thereafter, the process proceeds to step ST8d, where
The retry counting unit (77) subtracts one from the number of retries of the first circuit (3A) every time the repetition continues for one minute. If the number of retries is zero, no subtraction is performed. After that, the process proceeds to step ST5d to perform normal operation control.

As described above, the first control by the controller (70)
The operation at the time of controlling the high pressure of the circuit (3A) has been described, but the controller (70)
Similarly to the case of the first circuit (3A), the first circuit (3A) controls the discharge pipe temperature of the compressor (31) or controls the first circuit (3A).
A) The operation of controlling the low pressure is performed. The operation at that time conforms to the operation shown in the flowchart of FIG.

Further, the controller (70) performs an operation for controlling the high voltage and the like of the second circuit (3B) also for the second circuit (3B) as in the case of the first circuit (3A). The operation at that time also follows the operation shown in the flowchart of FIG.
They differ in the following points. That is, the primary refrigerant circuit (20)
When the refrigerant state of the first circuit (3A) deviates from the normal state, the circuit protection unit (74) stops the entire binary refrigeration system (10), whereas the refrigerant state of the second circuit (3B) In the case where the signal is out of the normal state, the circuit protection section (74) stops only the second circuit (3B).

According to the present embodiment, the restart unit (75) restarts the primary refrigerant circuit (20) and the secondary refrigerant circuit (3A, 3B), that is, the number of retries. The number of times can be limited. For this reason, if there is no expectation of recovery even after some time, and it is considered that a trouble requiring repair has occurred, the operation of the restart unit (75) is prohibited and the primary refrigerant circuit (20) and the secondary Unnecessary activation of the side refrigerant circuits (3A, 3B) can be avoided. As a result, it is possible to reduce the chances of the primary refrigerant circuit (20) and the secondary refrigerant circuits (3A, 3B) being operated in an unstable transient state after startup, and to reduce the occurrence of secondary trouble. Therefore, reliability can be improved. In other words, the compressor (21, 31, 3
It is possible to reduce the possibility of causing a secondary trouble which is difficult and costly to repair such as the trouble of 1), and it is possible to improve the reliability.

Further, a retry counting section (77) is provided so that once a certain condition is satisfied, the number of retries is subtracted once. If the primary-side refrigerant circuit (20) or the secondary-side refrigerant circuit (3A, 3B) is restarted by the restart unit (75), it can operate normally thereafter. The case where the operation of (75) should be prohibited can be reliably distinguished. As a result, the reliability can be further improved.

Further, the first circuit (3A) for performing the defrost operation which is an essential operation for the binary refrigeration system (10).
Can be reduced, and the reliability of the more important first circuit (3A) can be reliably improved. As a result, the reliability of the entire binary refrigeration system (10) can be improved.

That is, when the capacity control section (71) adjusts the refrigerating capacity, the start / stop control section (72) stops the second circuit (3B) with priority. Further, even when the high pressure of the first circuit (3A) becomes too high, the overload avoiding unit (73) stops the second circuit (3B) while continuing the operation of the first circuit (3A). The high pressure of the first circuit (3A) is reduced. When only the refrigerant state of the second circuit (3B) deviates from the normal state, the circuit protection unit (74) stops only the second circuit (3B), and stops the first circuit (3A) and the primary refrigerant. The cooling operation is continued only with the circuit (20). For this reason, the operation of the first circuit (3A) can be continued as much as possible, and the number of times the first circuit (3A) is started can be reduced.

The evaporator (50) of each of the secondary refrigerant circuits (3A, 3B) is formed integrally. Therefore, by configuring only the first circuit (3A) of the secondary refrigerant circuits (3A, 3B) so that the defrost operation can be performed, the entire evaporator (50) can be defrosted, and simplification can be achieved. Can be.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram illustrating a main part of a primary-side refrigerant circuit according to an embodiment.

FIG. 2 is a refrigerant circuit diagram showing a secondary refrigerant circuit according to the embodiment.

FIG. 3 is a schematic configuration diagram illustrating a configuration of an evaporator of a secondary-side refrigerant circuit according to the embodiment.

FIG. 4 is a block diagram illustrating a configuration of a controller according to the embodiment.

FIG. 5 is a conceptual diagram illustrating operations of a capability control unit and a start / stop control unit of the controller according to the embodiment.

FIG. 6 is a flowchart showing the operation of the controller when controlling the high pressure of the primary refrigerant circuit.

FIG. 7 is a flowchart showing the operation of the controller when controlling the discharge pipe temperature of the primary refrigerant circuit.

FIG. 8 is a flowchart showing the operation of the controller when controlling the low pressure of the primary refrigerant circuit.

FIG. 9 is a flowchart showing the operation of the controller when controlling the high voltage of the first circuit.

[Explanation of symbols]

 (3A) First circuit (secondary refrigerant circuit) (3B) Second circuit (secondary refrigerant circuit) (5a) Heat transfer tube for evaporation (5b) Heat transfer tube for evaporation (11) Refrigerant heat exchanger (20) Primary refrigerant circuit (21) Compressor (22) Condenser (31) Compressor (50) Evaporator (71) Capacity control unit (capacity control means) (72) Start / stop control unit (priority stop means) (73) Overload avoidance section (abnormality avoidance means) (74) Circuit protection section (protection means) (76) Retry means (77) Retry counting section (subtraction means) (78) Retry inhibition section (retry inhibition means) (80) Refrigerant state Detection means (EV12) Electric expansion valve for cooling (expansion mechanism) (EV21) Expansion valve for cooling (expansion mechanism)

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takeo Ueno 1304 Kanaokacho, Sakai City, Osaka Daikin Industries, Ltd. Sakai Plant Kanaoka Plant

Claims (6)

[Claims] 1. A compressor (21), a condenser (22), an expansion mechanism (EV12), and a plurality of refrigerant heat exchangers (1) in parallel with each other.
The primary refrigerant circuit (20) through which the primary refrigerant circulates, the compressor (31), and the condensation of the refrigerant heat exchangers (11, 11). Section, an expansion mechanism (EV21), and an evaporator (50) are connected in order, and the secondary refrigerant circulates, and the primary refrigerant and the secondary refrigerant in each of the refrigerant heat exchangers (11, 11). And a plurality of secondary refrigerant circuits (3A, 3B) that exchange heat with the primary refrigerant circuit (20) and the secondary refrigerant circuits (3A, 3B).
Refrigerant state detecting means (8) for detecting the refrigerant state in B)
0) and the primary refrigerant circuit (20) or the secondary refrigerant circuit (3A, 3
When the refrigerant state in B) deviates from a predetermined normal state, the primary refrigerant circuit (20) or the secondary refrigerant circuit (3A, 3B)
And the retry means (76) for restarting the refrigerant circuit (20, 3A, 3B) after the operation of the retry means (76) is stopped. A binary refrigerating apparatus comprising retry prohibiting means (78) for prohibiting retry. 2. The refrigeration apparatus according to claim 1, wherein the primary refrigerant circuit (20) and the secondary refrigerant circuit (3A, 3B) are restarted by the retry means (76) for a predetermined time. A binary refrigerating apparatus comprising a subtraction means (77) for subtracting one from the number of retries of the retry means (76) when the refrigerant state is maintained in a normal state. 3. A compressor (21), a condenser (22), an expansion mechanism (EV12), and a plurality of refrigerant heat exchangers (1) in parallel with each other.
The primary refrigerant circuit (20) through which the primary refrigerant circulates, the compressor (31), and the condensation of the refrigerant heat exchangers (11, 11). , The expansion mechanism (EV21), and the evaporator (50) are connected in order, and the secondary refrigerant circulates, and the primary refrigerant and the secondary refrigerant in each of the refrigerant heat exchangers (11, 11). And a plurality of secondary refrigerant circuits (3A, 3B) that exchange heat with the first refrigerant circuit (3A, 3B). ) And a second circuit (3B), while controlling the refrigeration capacity by changing the number of secondary refrigerant circuits (3A, 3B) performing refrigeration operation; Upon receiving the stop command signal from the capacity control means (71), the second refrigerant circuit (3A, 3B) of the secondary refrigerant circuits (3A, 3B) is preferentially stopped by the second circuit (3B). A binary refrigeration apparatus comprising a first stop means (72). 4. A compressor (21), a condenser (22), an expansion mechanism (EV12), and a plurality of refrigerant heat exchangers (1) in parallel with each other.
The primary refrigerant circuit (20) through which the primary refrigerant circulates, the compressor (31), and the condensation of the refrigerant heat exchangers (11, 11). Section, an expansion mechanism (EV21), and an evaporator (50) are connected in order, and the secondary refrigerant circulates, and the primary refrigerant and the secondary refrigerant in each of the refrigerant heat exchangers (11, 11). And a plurality of secondary refrigerant circuits (3A, 3B) that exchange heat with the first refrigerant circuit (3A, 3B). ) And the second circuit (3B), when the refrigerant pressure on the high pressure side of the secondary refrigerant circuit (3A, 3B) exceeds a predetermined value, an abnormality that stops the second circuit (3B). A binary refrigeration apparatus comprising an avoiding means (73). 5. A compressor (21), a condenser (22), an expansion mechanism (EV12), and a plurality of refrigerant heat exchangers (1) in parallel with each other.
The primary refrigerant circuit (20) through which the primary refrigerant circulates, the compressor (31), and the condensation of the refrigerant heat exchangers (11, 11). Section, an expansion mechanism (EV21), and an evaporator (50) are connected in order, and the secondary refrigerant circulates, and the primary refrigerant and the secondary refrigerant in each of the refrigerant heat exchangers (11, 11). And a plurality of secondary refrigerant circuits (3A, 3B) that exchange heat with the first refrigerant circuit (3A, 3B). ) And a second circuit (3B), while the primary refrigerant circuit (20) and each secondary refrigerant circuit (3A, 3B)
Refrigerant state detecting means (8) for detecting the refrigerant state in B)
0), and when only the refrigerant state of the second circuit (3B) deviates from the normal state, the protection means (7) stops only the second circuit (3B).
4) A binary refrigeration system comprising: 6. The refrigeration apparatus according to claim 3, wherein each of the secondary refrigerant circuits (3A, 3B) is connected to a heat transfer tube for evaporation (5a, 5b), respectively. (50) is formed by integrally assembling the evaporating heat transfer tubes (5a, 5b), while the first circuit (3A) is provided with a refrigerating operation and the evaporator (50).
And the second circuit (3B) is configured to perform a refrigeration operation.