JP3092602B2 - Refrigeration equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a refrigeration system,
In particular, the present invention relates to a binary refrigeration system including a low-stage refrigerant circuit and a high-stage refrigerant circuit.

[0002]

2. Description of the Related Art Conventionally, binary refrigeration systems have been used as refrigeration systems for low-temperature warehouses. As disclosed in, for example, Japanese Patent Application Laid-Open No. 9-210515, a binary refrigeration system is configured by connecting a low-stage refrigerant circuit and a high-stage refrigerant circuit via a cascade condenser.

[0003] A conventional binary refrigeration system (200) will be described with reference to FIG. The low-stage refrigerant circuit (202) includes a low-stage compressor (207), a cascade condenser (206), a low-stage receiver (208), a low-stage expansion valve (204), and an evaporator (209) in order. The high-stage refrigerant circuit (203) includes a high-stage compressor (210), a condenser (212), a high-stage receiver (211), a high-stage expansion valve (205), and a cascade condenser. (206) are connected in order. The evaporator (209) of the low-stage refrigerant circuit (202) is installed inside the warehouse (201) and cools the air in the warehouse. The condenser (212) is installed outside the warehouse (201), and the blower (213)
To supply the outside air.
Outside the warehouse (201), a temperature sensor (214) for detecting the temperature of the outside air is provided. The blower (213) and the temperature sensor (214) are connected to the controller (215).

In the binary refrigeration system (200), while controlling the operation state of the low-stage refrigerant circuit (202) and the high-stage refrigerant circuit (203), control of both refrigerant circuits (202) and (203) is performed. Need to do. However, since the configuration of the device is complicated, it is preferable that the control of each of the refrigerant circuits (202) and (203) is performed independently. Therefore, as one control of the high-stage refrigerant circuit (203), in order to maintain a high-pressure side pressure of the high-stage refrigerant circuit (203) at a predetermined value by processing an appropriate amount of heat in the condenser (212), In some cases, the air volume of the blower (213) is controlled. Conventional air volume control has been performed based on the outside air temperature detected by the temperature sensor (214).

[0005]

The condenser (21)
The amount of heat to be processed in 2), that is, the load of the condenser (212) changes according to the refrigeration load of the evaporator (209) of the low-stage refrigerant circuit (202). However, since the air volume control based on the outside air temperature is a uniform control, it cannot be said that the air volume control flexibly responds to the load of the condenser (212). Therefore, only control based on the outside air temperature, for example, when the warehouse (201) is frequently opened and closed, e.g., the evaporator of the low-stage refrigerant circuit (202)
When the refrigeration load of (209) fluctuates greatly, it has been difficult to perform appropriate operation.

In a so-called multi-system in which the low-stage refrigerant circuit (202) is composed of a plurality of refrigerant circuits, the number of operating refrigerant circuits varies depending on the situation. Therefore, the load of the condenser (212) fluctuates greatly, and it has been difficult to perform an appropriate operation according to the operation state of the low-stage refrigerant circuit (202).

The present invention has been made in view of the above point, and an object thereof is to appropriately control a high-stage refrigerant circuit according to a low-stage refrigerant circuit.

[0008]

In order to achieve the above object, according to the present invention, the high-pressure side pressure of the high-stage refrigerant circuit is adjusted based on the parameters of the high-stage refrigerant circuit.

Specifically, in the first invention, the high-stage refrigerant circuit (120) and the low-stage refrigerant circuit (103A, 103B) are provided with a refrigerant heat exchanger.
(111A, 111B), connected to each other via the high-stage refrigerant circuit (120), the compressor (121), air heat exchanger (122), expansion mechanism (EVL1, EVL2 ) And the refrigerant heat exchanger (111A, 111B) is connected to a main circuit (120a),
A receiver (125) provided between the air heat exchanger (122) and the expansion mechanism (EVL1, EVL2); a high pressure side pipe (40) of the high stage refrigerant circuit (120); and the receiver (125) and a pressurizing on-off valve provided in the pressurizing passage (3).
(5), a gas vent passage (4) for communicating the receiver (125) and the low pressure side pipe (41) of the high stage refrigerant circuit (120), and a gas vent passage (4). A blower (1, 1) for supplying air to the air heat exchanger (122).
2), discharge pressure detecting means (11) for detecting the pressure of the refrigerant discharged from the compressor (121), and discharge temperature detecting means (13) for detecting the temperature of the refrigerant discharged from the compressor (121) And the blower (1) based on the detection values of the discharge pressure detecting means (11) and the discharge temperature detecting means (13) so that the high-pressure side pressure of the high-stage refrigerant circuit (120) becomes a predetermined value. , 2), a control means (7) for controlling the pressurizing on-off valve (5) and the degassing on-off valve (6).

According to the above, when the high-pressure side pressure of the high-stage refrigerant circuit (120) is lower than a predetermined value, the pressurizing on-off valve
Open (5) and close the vent valve (6), apply high pressure from the pressurized passage (3) to the receiver (125), and
Increase the pressure in (125). As a result, the receiver (125)
The liquid refrigerant in the air heat exchanger (122) decreases, and the liquid refrigerant in the air heat exchanger (122) increases. As a result, the effective heat transfer area of the air heat exchanger (122) decreases, and the high-pressure side pressure of the high-stage refrigerant circuit (120) increases. On the other hand, when the high-pressure side pressure of the high-stage refrigerant circuit (120) is higher than a predetermined value, the degassing on-off valve (6) is opened and the pressurizing on-off valve (5) is closed, and the degassing on-off valve is opened. Relieve the pressure of the receiver (125) from the valve (6)
5) Reduce the pressure inside. As a result, the liquid refrigerant in the receiver (125) increases, and the liquid refrigerant in the air heat exchanger (122) decreases. Thereby, the high pressure side pressure of the high stage side refrigerant circuit (120) decreases.

The control means (7) includes a high-stage refrigerant circuit.
Blower (1, 2) so that the high pressure side pressure of (120) becomes a predetermined value.
The control of the pressurizing on-off valve (5) and the degassing on-off valve (6) is also performed together with the control of (1). As a result, appropriate control corresponding to a wider range of load fluctuation of the air heat exchanger (122) is executed.

According to a second aspect of the present invention, the high-stage refrigerant circuit (120) and the low-stage refrigerant circuit (103A, 103B) include a refrigerant heat exchanger (111A, 111B).
Wherein the high-stage refrigerant circuit (120) is a compressor capable of unloading operation.
(121), an air heat exchanger (122), an expansion mechanism (EVL1, EVL2), and a main circuit formed by connecting the refrigerant heat exchangers (111A, 111B).
(120a), the air heat exchanger (122) and the expansion mechanism (EVL1, EVL
2), a receiver (125), and a pressurized passage (3) communicating the high-pressure side pipe (40) of the high-stage refrigerant circuit (120) with the receiver (125). The pressurizing on-off valve (5) provided in the pressurizing passage (3), the receiver (125) and the high-stage refrigerant circuit (1
Degassing passage (4) communicating with low pressure side pipe (41) of (20)
And an on-off valve for degassing provided in the degassing passageway (4).
(6), a blower (1, 2) for supplying air to the air heat exchanger (122), and a discharge pressure detecting means (11) for detecting the pressure of the refrigerant discharged from the compressor (121) And the compressor (121)
Discharge temperature detecting means (13) for detecting the temperature of refrigerant discharged from
Suction pressure detection means (12) for detecting the pressure of the refrigerant sucked into the compressor (121), and the discharge pressure detection means (11)
And a second parameter (ΔFN1) based on the detected value of the discharge temperature detecting means (13).
N2) and three or more parameters including a third parameter (ΔFN3) representing the load state of the compressor (121) based on the detection values of the discharge pressure detecting means (11) and the suction pressure detecting means (12). Thus, the blower (1, 2), the pressurizing on-off valve (5), and the degassing on-off valve (6) so that the high-pressure side pressure of the high-stage refrigerant circuit (120) becomes a predetermined value. And a control means (7) for controlling.

According to the above, since the compressor (121) is configured to be capable of unloading operation, the compressor (121)
The high-pressure side pressure of the high-stage side refrigerant circuit (120) can be freely adjusted also by the operation switching. The control means (7) includes a first parameter based on the discharged refrigerant pressure and a second parameter based on the discharged refrigerant temperature.
Control is performed based on a third parameter based on the load state of the compressor (121) in addition to the parameter. Therefore, the high-pressure side pressure of the high-stage refrigerant circuit (120) will be adjusted flexibly in response to a large load change of the air heat exchanger (122), the low-stage refrigerant circuit (103A, 103B) Will respond appropriately to large load fluctuations.

According to a third aspect of the present invention, in any one of the first and second aspects of the present invention, the low stage side refrigerant circuit comprises a refrigerant heat exchanger.
(111A, 111B) each comprising a plurality of refrigerant circuits (103A, 103
B), and the high-stage refrigerant circuit (120) is connected to the refrigerant circuits (103A, 103B) via the refrigerant heat exchangers (111A, 111B).

[0015] By the above, a so-called multi-system refrigeration apparatus is constituted, and the load fluctuation of the air heat exchanger (122) of the high-stage refrigerant circuit (120) increases. Therefore, the effects of the first and second inventions are more remarkably exhibited.

[0016]

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

-Configuration of Refrigeration Unit (110)-As shown in FIGS. 1 and 2, the refrigeration unit (110) is a binary refrigeration unit that cools the inside of a refrigerator or a freezer, and has an outdoor unit (101A). ), A cascade unit (101B) and a cooling unit (101C). The cooling unit (101C) is installed in the storage. Although not shown, each of the units (101A), (101B), and (101C) is formed by housing constituent devices in a predetermined casing. And the outdoor unit (101A) and the cascade unit
A part of (101B) forms a high-stage refrigerant circuit (120). Further, the two low-stage refrigerant circuits (1) extend over the cascade unit (101B) and the cooling unit (101C).
03A) and (103B).

-Configuration of the high-stage refrigerant circuit (120)-The high-stage refrigerant circuit (120) is configured to be capable of reversible operation for switching the refrigerant circulation direction between a forward cycle and a reverse cycle,
High-stage compressor (121) and air heat exchanger (122) forming a condenser
And two refrigerant heat exchangers (111A) and (111B). The high-stage refrigerant circuit (120) includes a high-stage compressor (121), an air heat exchanger (122), an electric expansion valve (EVL1),
2) and a main circuit (120a) formed by connecting the refrigerant heat exchangers (111A) and (111B), a pressurizing passage (3), and a degassing passage (4).

The high-stage compressor (121) is a compressor that can be freely unloaded. That is, it is a compressor whose capacity can be freely controlled.

A first gas pipe (40) is connected to the discharge side of the high-stage compressor (121), and a second gas pipe (41) is connected to the suction side. The first gas pipe (40) is a high-stage compressor (121)
From the oil separator (123) and the four-way switching valve (124) in order,
It is connected to one end of the air heat exchanger (122). One end of a liquid pipe (42) is connected to the other end of the air heat exchanger (122), and the liquid pipe (42) is a main pipe (104a) and two branch pipes (104b), (10
4c). And each branch pipe (10
4b) and (104c) are connected to the respective evaporators of the two refrigerant heat exchangers (111A) and (111B).

The main pipe (104a) of the liquid pipe (42) is connected to a bypass pipe (104h) connected to the second gas pipe (41). The bypass pipe (104h) is provided with a solenoid valve (SV) and a temperature-sensitive expansion valve (EV). The above branch piping (104b), (10
4c) is provided with first and second electric cooling expansion valves (EVL1) and (EVL2), respectively.

The second gas pipe (41) is formed by a main pipe (104d) and two branch pipes (104e) and (104f).
The main pipe (104d) of the second gas pipe (41) is connected to the high-stage compressor (12
While the accumulator (126) and the four-way switching valve (124) are connected in order from 1), the branch pipes (104e) and (104f) are connected to the evaporating sections of the refrigerant heat exchangers (111A) and (111B). It is connected. That is, the evaporators of the two refrigerant heat exchangers (111A) and (111B) are connected in parallel to each other in the high-stage refrigerant circuit (120).

The liquid pipe (42) and the second gas pipe (41)
Branch pipes (104b), (104c), (104e), and (104f) are provided in the cascade unit (101B).

Between the first gas pipe (40) and the receiver (125), a pressurizing passage (3) formed of a pipe is connected. One end of the pressurizing passage (3) is connected between the oil separator (123) and the four-way switching valve (124) in the first gas pipe (40), and the other end is connected to the upper part of the receiver (125). Have been. That is, the pressurizing passage (3) communicates the high pressure side pipe of the high stage refrigerant circuit (120) with the receiver (125). In the pressurized passage (3),
A pressurizing on-off valve (5) composed of a solenoid valve is provided.

The pressurizing passage (3) is connected to a gas venting passage (4) composed of a pipe connected to the second gas pipe (41). In other words, one end of the gas vent passage (4) is connected between the pressurizing on-off valve (5) and the receiver (125) in the pressurizing passage (3), and the other end is connected to the low pressure refrigerant of the high-stage refrigerant circuit (120). Connected to the side piping. The gas vent passage (4) is provided with a gas vent opening / closing valve (6) composed of an electromagnetic valve and a capillary tube (CP).

The pressurizing passage (3) is for applying high pressure to the receiver (125) by high-pressure refrigerant by opening the on-off valve (5) for pressurizing. On the other hand, the degassing passage (4)
The opening of the degassing on-off valve (6) releases the pressure of the receiver (125) and reduces the pressure in the receiver (125). When the pressure of the receiver (125) increases, the liquid refrigerant in the receiver (125) decreases, and the air heat exchanger (122)
The liquid refrigerant inside increases. On the other hand, when the pressure of the receiver (125) decreases, the liquid refrigerant in the receiver (125) increases, and the liquid refrigerant in the air heat exchanger (122) decreases.

An oil return passage (44) having a capillary tube (CP) is connected between the oil separator (123) and the suction side of the high-stage compressor (121). An unload passage (45) including a capillary tube (CP) and an on-off valve (SV) is connected between the discharge side and the suction side of the high-stage compressor (121), and the unload passage ( The middle part of 45) is connected to the high-stage compressor (121).

The first compressor on the discharge side of the high-stage compressor (121) is also provided.
The gas pipe (40) has a high-pressure sensor (11) for detecting the pressure of the discharged refrigerant and a discharge temperature sensor (1) for detecting the temperature of the discharged refrigerant.
3) and a high-pressure switch (HPS1) that outputs an off signal when the pressure of the discharged refrigerant excessively increases and reaches a predetermined pressure. Also, the second gas pipe on the suction side of the high-stage compressor (121)
(41) is provided with a low pressure sensor (12) for detecting the pressure of the suction refrigerant. This high pressure sensor (11), discharge temperature sensor
(13) The low pressure sensor (12) corresponds to “discharge pressure detecting means”, “discharge temperature detecting means”, and “suction pressure detecting means”, respectively.

The outdoor unit (101A) has an air heat exchanger (1
First and second blowers (1) and (2) for supplying outdoor air to 22)
Is provided.

A first blower (1), a second blower (2), an on-off valve for pressurizing (5), an on-off valve for degassing (6), a high pressure sensor (11), a low pressure sensor (12), and a discharge temperature sensor (13) is `` control means ''
Connected to the controller (7).

-Structure of Low-Stage Refrigerant Circuit- On the other hand, the first low-stage refrigerant circuit (103A) is configured to be capable of reversible operation by switching the refrigerant circulation direction between a forward cycle and a reverse cycle. And the first low-stage refrigerant circuit (103A)
The heat exchanger includes first and second low-stage compressors (31A) and (131A), a condensing portion of a first refrigerant heat exchanger (111A), and an evaporating heat transfer tube (105a). The condenser of the refrigerant heat exchanger (111A) forms a condenser of the first low-stage refrigerant circuit (103A). The first low-stage compressor (31A) and the second low-stage compressor (131A) are connected in parallel with each other.

On the discharge side of each of the compressors (31A) and (131A),
Oil separators (32) and (132) are provided, respectively. The downstream side of the oil separators (32) and (132) is connected to one end of a condensing part in the first refrigerant heat exchanger (111A) via the four-way switching valve (33) and the first gas pipe (60). It is connected. The other end of the condenser is connected to one end of an evaporative heat transfer tube (105a) via a check valve (CV), a receiver (34), and a cooling expansion valve (EV21) by a liquid pipe (61). I have. The other end of the heat transfer tube for evaporation (105a) is connected to the two low-stage compressors (2) via a check valve (CV), a four-way switching valve (33), and an accumulator (35) by a second gas pipe (62). 31A) and (131A) are connected to the suction side.

The first refrigerant heat exchanger (111A) is a refrigerant heat exchanger having an evaporating section of the high-stage refrigerant circuit (120) and a condensing section of the first low-stage refrigerant circuit (103A). And a plate heat exchanger. The first refrigerant heat exchanger (111A) performs heat exchange between the refrigerant in the first low-stage refrigerant circuit (103A) and the refrigerant in the high-stage refrigerant circuit (120).
While the refrigerant in the low-stage refrigerant circuit (103A) radiates heat and condenses,
The refrigerant in the high-stage refrigerant circuit (120) 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 heat transfer tube (105a) for evaporation. Is provided.

Since the first low-stage refrigerant circuit (103A) is configured to perform a reverse cycle defrost operation, a drain pan passage (63), a gas bypass passage (64), and a pressure reduction passage (65) are provided. It has. The drain pan passage (63) is
Connected to both ends of the check valve (CV) in the gas passage (62),
A drain pan heater (106a) and a check valve (CV) are provided so that refrigerant (hot gas) discharged from the compressor (31) flows.

The gas bypass passage (64) is connected to both ends of the cooling expansion valve (EV21) in the liquid pipe (61), and is connected to the check valve (CV).
The liquid refrigerant is supplied to the cooling expansion valve (EV2
It is configured to bypass 1).

The pressure reducing passage (65) is connected to both ends of the check valve (CV) in the liquid pipe (61). This decompression passage (65)
An on-off valve (SV) is provided to reduce the pressure of the liquid refrigerant during the defrost operation.

Further, one end of a gas vent passage (66) is connected to an upper portion of the receiver (34). Degassing passage (66)
Has an on-off valve (SV) and a capillary tube (CP), and the other end is connected to the second gas pipe (62) on the upstream side of the accumulator (35).

Each oil separator (32), (132) and each low-stage compressor (3
1A) and (131A) between the suction side and the capillary tube (C
Oil return passages (67), (67) provided with (P) are connected respectively.

The first gas pipes (60) and (60) on the discharge side of the low-stage compressors (31A) and (131A) are turned off when the high-pressure refrigerant pressure rises excessively and reaches a predetermined pressure. High pressure switches (HPS2) and (HPS2) for outputting signals and temperature sensors (STH2) and (STH2) for detecting the temperature of the discharged gas refrigerant are provided. A high-pressure sensor that detects high-pressure refrigerant pressure is provided between the junction of the discharge-side pipes of both low-stage compressors (31A) and (131A) and the four-way switching valve (33).
(SPH2) is provided. Both low-stage compressors (31A), (131A)
A low-pressure sensor (SPL2) for detecting low-pressure refrigerant pressure is provided in the second gas pipe (62) on the suction side.

The second low-stage refrigerant circuit (103B) has substantially the same configuration as the first low-stage refrigerant circuit (103A), but is configured to perform only the cooling operation without performing the defrost operation. I have. The second low-stage refrigerant circuit (103B) is a first low-stage refrigerant circuit.
(103A) does not include the four-way switching valve (124), and furthermore, the drain pan passage (63), the gas bypass passage (64), and the pressure reducing passage (6
5) is not provided. That is, the second low-stage refrigerant circuit
(103B) is a first and second low-stage compressors (31B), (131B), a condenser of the second refrigerant heat exchanger (111B), a receiver (34), and a cooling expansion valve (EV21). And a heat transfer pipe for evaporation (105b) and an accumulator (35) are connected in order by a first gas pipe (60), a liquid pipe (61), and a second gas pipe (62). The condensing section of the second refrigerant heat exchanger (111B) forms a condenser of the second low-stage refrigerant circuit (103B).

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 evaporation heat transfer tube (105b). The second refrigerant heat exchanger (111B) is a cascade condenser having an evaporator of the higher-stage refrigerant circuit (120) and a condenser of the second lower-stage refrigerant circuit (103B). It consists of a heat exchanger. The second refrigerant heat exchanger (111B) includes a refrigerant of the second lower stage refrigerant circuit (103B) and a higher stage refrigerant circuit (120).
The refrigerant in the second lower stage refrigerant circuit (103B) radiates heat and condenses, while the refrigerant in the higher stage refrigerant circuit (120) absorbs heat and evaporates.

The heat transfer tubes (105a) and (105b) for evaporation in the low-stage refrigerant circuits (103A) and (103B) are one evaporator (50).
In the evaporator (50), the refrigerant in both low-stage refrigerant circuits (103A) and (103B) exchanges heat with the internal air. The evaporator (50), the cooling expansion valve (EV21), and the drain pan passage (63) are provided in the cooling unit (101C), while the other compressors (31A), (131A), (31B), ( 131B)
Are provided in the cascade unit (101B).

A liquid temperature sensor (Th21) for detecting the temperature of the liquid refrigerant is provided in front of the flow divider (51) in the liquid pipe (61) in the first low-stage refrigerant circuit (103A). The evaporator (50) is provided with an evaporator temperature sensor (Th22) for detecting the temperature of the evaporator (50).

A temperature sensor (Tx) for detecting the temperature of the air in the warehouse is provided in the warehouse.

-Operation of Refrigeration Unit (110)-Next, the refrigeration operation of the refrigeration unit (110) will be described.

In the present refrigeration system (110), when the refrigeration load in the refrigerator is small, the first and second refrigerant circuits (103A) of the first lower stage side refrigerant circuit (103A).
When the low-stage compressors (31A) and (131A) are operated and the refrigeration load in the refrigerator is large, the first and second low-stage compressors (103A) and (103B) of both low-stage refrigerant circuits (103A) 31A), (131A), (31B), and (131B) are operated. That is, when the load in the refrigerator is small, a total of two compressors (31A) and (131A) are operated. Conversely, when the load in the refrigerator is large, a total of four compressors (31A), (131A), (31B) and (131B) are operated.

Here, a description will be given of the operation when the load in the refrigerator is large. In this case, the high-stage compressor (121) of the high-stage refrigerant circuit (120) and the first and second low-stage compressors (31A) of both low-stage refrigerant circuits (103A) and (103B), ( 131A), (31B), and (131B) are driven together. In this state, the high-stage refrigerant circuit (12
In (0), the four-way switching valve (124) is switched to the solid line side in FIG. 1, and the opening control of the electric cooling expansion valves (EVL1) and (EVL2) described later is executed.

In the high-stage refrigerant circuit (120), the high-stage refrigerant discharged from the high-stage compressor (121) is condensed in the air heat exchanger (122) to become a liquid refrigerant, unit
(101B). The liquid refrigerant is divided into two branch pipes (104b) and (104c), and the cooling electric expansion valves (EVL1), (E
The pressure is reduced by VL2). Thereafter, the liquid refrigerant evaporates in each of the evaporating sections of the two refrigerant heat exchangers (111A) and (111B), turns into a gas refrigerant, returns to the high-stage compressor (121), and repeats this circulation.

On the other hand, in the first low-stage refrigerant circuit (103A), the four-way switching valve (33) is switched to the solid line side in FIG. 2, while the on-off valve (SV) of the pressure reducing passage (65) is closed to cool the refrigerant. The superheat degree of the expansion valve (EV21) is controlled. In the second low-stage refrigerant circuit (103B),
The degree of superheat of the cooling expansion valve (EV21) is controlled.

In the two lower stage refrigerant circuits (103A) and (103B), the lower stage refrigerant discharged from the lower stage compressors (31A), (131A), (31B) and (131B) is refrigerant. The liquid refrigerant is condensed in the condensing sections of the heat exchangers (111A) and (111B), and the liquid refrigerant is reduced in pressure by the cooling expansion valves (EV21) and (EV21). Thereafter, the liquid refrigerant evaporates in the evaporating heat transfer tubes (105a) and (105b) to become a gas refrigerant and returns to the low-stage compressors (31A), (131A), (31B), and (131B). This cycle is repeated.

The refrigerant heat exchangers (111A) and (111)
In B), the high-stage refrigerant and the low-stage refrigerant exchange heat,
The low-stage refrigerant in the low-stage refrigerant circuits (103A) and (103B) is cooled and condensed. On the other hand, in the evaporator (50), the low-stage side refrigerant evaporates to generate cooling air, thereby cooling the inside of the refrigerator.

Operation Control of High-Stage Refrigerant Circuit (120) Next, a control method of the high-stage refrigerant circuit (120) will be described with reference to the flowchart of FIG. This control is based on the pressure of the refrigerant discharged from the high-stage compressor (121) (hereinafter referred to as the high-stage discharge pressure P
d), the temperature of the discharged refrigerant (hereinafter, the high-stage discharge temperature T)
d) and the pressure of the suction refrigerant (hereinafter referred to as the high-stage suction pressure Ps) so that the high-pressure side pressure of the high-stage refrigerant circuit (120) becomes a predetermined value (for example, 15 kg / cm ² ). ,
Blowers (1), (2), on-off valve for pressurization (5) and on-off valve for venting
The control of (6) is performed. Thereby, the high-pressure side pressure of the low-stage refrigerant circuits (103A) and (103B) is stabilized.

In this control, the first control based on the high-stage discharge pressure is performed.
The parameter ΔFN1, the second parameter ΔFN2 based on the high-stage discharge temperature Td, and the third parameter ΔFN3 based on the load state of the high-stage compressor (121) are independent parameters, and controlled according to these three parameters. I am going to do.

The control in steps ST1 to ST9 described below is performed at predetermined time intervals. That is, each process described below is repeatedly executed at predetermined intervals.

Specifically, first, in step ST1, the high-stage discharge pressure Pd (kg
f / cm ² ), the first parameter ΔF based on Table 1
Determine N1.

[0057]

[Table 1]

Next, in step ST2, a second parameter ΔFN2 is determined based on Table 2 from the value of the high-stage discharge temperature Td (° C.) detected by the discharge temperature sensor (13).

[0059]

[Table 2]

Next, in steps ST3 to ST7, a third state is determined based on the load state of the high-stage compressor (121).
Determine the parameter ΔFN3. That is, step S
At T3, it is determined whether the value of the high-stage suction pressure Ps (kgf / cm ² ) detected by the low-pressure sensor (12) is smaller than a predetermined value (set to ² kg / cm ² in this example), and YES In the case of, the process proceeds to step ST4, and in the case of NO, the process proceeds to step ST6. In step ST4, it is determined whether or not the value of the high-stage discharge pressure Pd is larger than a predetermined value (in this example, set to 12 kg / cm ² ), or whether a control output parameter FH described later is 1 or not. In this case, the process proceeds to step ST5, and if NO, the process proceeds to step ST7. In step ST5, it is determined that the load on the high-stage compressor (121) is small, and
The operation of (121) is set to the unload operation, and the process proceeds to step ST6. In step ST6, it is considered that there is no need to change the control amount based on the load state of the high-stage compressor (121).
The value of the parameter ΔFN3 is determined to be zero. On the other hand, in step ST7, the third parameter ΔFN3 is set to ΔFN in order to suppress a decrease in the high-pressure side pressure of the high-stage refrigerant circuit (120).
3 = 2 (Ps−2) is set. That is, a negative number is set to the third parameter ΔFN3.

Next, the process proceeds to step ST8, where the value of the control output parameter FH is determined based on a predetermined arithmetic expression.
Specifically, the first to third parameters ΔFN1, ΔFN
2. In order to perform weighting of ΔFN3, predetermined coefficients A1, A2, A
3 and set ΔFN to ΔFN = A1 × ΔFN1 + A2 ×
It is determined by ΔFN2 + A3 × ΔFN3. Next, based on this ΔFN, FN = MIN (MAX (FN ′ + Δ
FN, 1), 6) are determined. That is, FN '+ ΔFN
And the larger value of 1 and 6 is compared, and the smaller value of both is set as FN. Note that FN 'is
This is the FN determined in the previous cycle (that is, one cycle before). Then, the value of the control output parameter FH is set to FH = MI
N (MAX (INT (FN), 1), 6). In other words, the numerical value obtained by converting FN into an integer and the larger numerical value of 1 are compared with 6, and the smaller numerical value of both is set as FH.

Next, the process proceeds to step ST9, where the first blower is obtained from Table 3 based on the value of the control output parameter FH.
(1) The states of the second blower (2), the on-off valve for pressurizing (5), and the on-off valve for degassing (6) are determined, and a control signal is output to each to set the state.

[0063]

[Table 3]

As described above, according to the present embodiment, the first
Since the blower (1) and the second blower (2) are controlled not only based on the outside air temperature but also based on the parameters of the high-stage refrigerant circuit (120), the high-stage refrigerant circuit (12
0) The high pressure side pressure can be adjusted directly. Therefore, appropriate control flexibly responding to a large load change can be performed.

Further, in addition to the control of the blowers (1) and (2), the control of the opening and closing of the pressurizing on-off valve (5) and the degassing on-off valve (6) is also performed. In addition to this, the amount of circulating refrigerant can be adjusted. Therefore, the high-stage refrigerant circuit (12
The control of 0) can be executed even for a wider range of load fluctuation.

Further, the unload operation of the high-stage compressor (121) is possible, and the operation control of the high-stage refrigerant circuit (120) is performed based on the operation state of the high-stage compressor (121). Therefore, appropriate operation control can be performed even for a larger load change.

<Other Embodiments> The outdoor unit (101A) may be provided with a temperature sensor (14) for detecting the temperature of outdoor air. And
The controller (7) may perform the operation control in consideration of the detection value (outdoor air temperature) of the temperature sensor (14) in addition to the discharge refrigerant temperature, the discharge refrigerant pressure, and the suction refrigerant pressure. Even in this case, unlike the operation control based only on the outdoor air temperature, since the control is performed based on the parameters of the high-stage refrigerant circuit (120), the air heat exchanger (122)
Control that can flexibly respond to the load of the system.

On the other hand, the controller (7) may control the operation based on only the discharge refrigerant pressure and the suction refrigerant pressure. That is, control may be performed regardless of the load state of the high-stage compressor (121). Thus, for example, when the high-stage compressor (121) is configured to operate at a constant capacity, control can be simplified.

The pressurizing passage (3) and the gas venting passage (4) are not always necessary, and the opening / closing control of the pressurizing on / off valve (5) and the gas venting on / off valve (6) is not necessarily required. Therefore, the controller (7) may be configured to control only the blowers (1) and (2).

The low-stage refrigerant circuit does not need to be composed of two refrigerant circuits, but may be composed of a single refrigerant circuit. Further, it may be composed of three or more refrigerant circuits.

[0071]

As described above, according to the present invention, since the blower is controlled based on the parameters of the high-stage refrigerant circuit, the control which flexibly responds to a large load change of the air heat exchanger can be performed. It becomes possible. This makes it possible to appropriately control the high-stage refrigerant circuit according to the low-stage refrigerant circuit.

Further, by providing a pressurizing passage and a gas venting passage in the high-stage refrigerant circuit and controlling the opening and closing of the pressurizing on / off valve and the gas venting on / off valve, a wide range of operation capable of coping with a larger load fluctuation. Control becomes possible.

Further, by configuring the compressor of the high-stage refrigerant circuit so as to be capable of unloading operation and performing control in accordance with the load state of the compressor, a wide range of operation control capable of coping with a larger load change can be realized. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a high-stage refrigerant circuit of a refrigeration apparatus.

FIG. 2 is a circuit diagram of a low-stage side refrigerant circuit of the refrigeration apparatus.

FIG. 3 is a flowchart of operation control of a high-stage refrigerant circuit.

FIG. 4 is a refrigerant circuit diagram of a conventional refrigeration apparatus.

[Explanation of symbols]

 (1), (2) Blower (3) Pressurizing passage (4) Gas venting passage (5) Pressurizing on-off valve (6) Degassing on-off valve (7) Controller (control means) (11) High pressure sensor (Discharge (12) Low pressure sensor (suction pressure detecting means) (13) Discharge temperature sensor (discharge temperature detecting means) (103A), (103B) Low stage refrigerant circuit (120) High stage refrigerant circuit (121) High stage compressor (122) Air heat exchanger

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-5567 (JP, A) JP-A 63-66768 (JP, U) JP-A 52-55735 (JP, Y2) (58) Field (Int.Cl. ⁷ , DB name) F25B 7/00

Claims (3)

(57) [Claims] 1. A refrigeration apparatus comprising a high-stage refrigerant circuit (120) and a low-stage refrigerant circuit (103A, 103B) connected to each other via a refrigerant heat exchanger (111A, 111B). The stage side refrigerant circuit (120) includes a compressor (121), an air heat exchanger (122), an expansion mechanism (EVL1, EVL2), and the refrigerant heat exchanger (1).
11A, 111B), a receiver (125) provided between the air heat exchanger (122) and the expansion mechanism (EVL1, EVL2), and the high stage side A pressurizing passage (3) communicating the high pressure side pipe (40) of the refrigerant circuit (120) with the receiver (125), and a pressurizing on-off valve provided in the pressurizing passage (3)
(5), a gas vent passage (4) for communicating the receiver (125) and the low pressure side pipe (41) of the high stage refrigerant circuit (120), and a gas vent passage (4). A blower (1, 2), which is provided with a vent valve (6) for supplying air to the air heat exchanger (122).
Discharge pressure detection means (11) for detecting the pressure of the refrigerant discharged from the compressor (121), discharge temperature detection means (13) for detecting the temperature of the refrigerant discharged from the compressor (121), The discharge pressure detecting means (11) and the discharge temperature detecting means (1
Based on the detected value of 3), the blower (1, 2), the pressurizing on-off valve (5) and the gas venting so that the high-pressure side pressure of the high-stage refrigerant circuit (120) becomes a predetermined value. A refrigerating apparatus comprising: a control unit (7) for controlling an on-off valve (6). 2. A refrigeration system comprising a high-stage refrigerant circuit (120) and a low-stage refrigerant circuit (103A, 103B) connected to each other via a refrigerant heat exchanger (111A, 111B). The stage side refrigerant circuit (120) is a compressor (121) that can be unloaded, an air heat exchanger (122), and expansion mechanisms (EVL1, EVL2)
A main circuit (120a) connected to the refrigerant heat exchangers (111A, 111B); the air heat exchanger (122); and the expansion mechanism (EVL).
1, EVL2), and a pressurized passage (3) communicating the high-pressure side pipe (40) of the high-stage refrigerant circuit (120) with the receiver (125). A gas for communicating between the on-off valve (5) for pressurization provided in the pressurization passage (3), and the pipe (41) on the low-pressure side of the receiver (125) and the high-stage refrigerant circuit (120). Aisle
(4) a blower (1, 2) comprising a degassing opening / closing valve (6) provided in the degassing passage (4), and supplying air to the air heat exchanger (122).
Discharge pressure detection means (11) for detecting the pressure of the refrigerant discharged from the compressor (121), discharge temperature detection means (13) for detecting the temperature of the refrigerant discharged from the compressor (121), Suction pressure detecting means (12) for detecting a pressure of refrigerant sucked into the compressor (121); a first parameter (ΔFN1) based on a detection value of the discharge pressure detecting means (11); A second parameter (ΔFN2) based on the detection value of the means (13);
(11) and a third parameter (ΔFN3) indicating a load state of the compressor (121) based on the detection value of the suction pressure detection means (12), and the high-stage refrigerant circuit ( 12
0) the blower (1, 2) so that the high-pressure side pressure becomes a predetermined value.
And a control unit (7) for controlling the pressurizing on-off valve (5) and the degassing on-off valve (6). 3. The refrigeration apparatus according to claim 1, wherein the low-stage refrigerant circuit includes a plurality of refrigerant circuits (103A, 103B) each including a refrigerant heat exchanger (111A, 111B). The high-stage refrigerant circuit (120) includes the refrigerant heat exchangers (111A, 111A).
A refrigeration apparatus connected to each of the refrigerant circuits (103A, 103B) via B).