JP5222494B2 - Environmental tester - Google Patents

Description

The present invention relates to environmental test chambers, and more particularly, a compressor, a condenser, expansion means, having a plurality of refrigeration circuits composed of such an evaporator, a one yuan operation operating at a single refrigeration circuit, those concerning the environmental tester switching with a possible refrigeration system with multiple operation operating at two or more refrigeration circuits by using a cascade condenser.

  Conventionally, a refrigeration apparatus for cooling is used in a thermostat or an air conditioner. The refrigeration apparatus includes a refrigeration circuit that is constituted by a compressor, a condenser, an expansion unit, an evaporator, and the like and in which a refrigerant circulates. The refrigerant is compressed by the compressor, condensed by the condenser, expanded by the expansion means, evaporated by the evaporator, circulated back to the compressor again, and is evaporated at the evaporator. Cooling takes away heat from the surroundings.

To lower the temperature or to cool faster, it is necessary to increase the cooling capacity. In such a case, a refrigeration apparatus capable of multiple operation having two or more refrigeration circuits thermally connected by a cascade condenser or the like. Was sometimes used.
Such a refrigeration apparatus has a plurality of refrigeration circuits, and the condenser and the evaporators of the other refrigeration circuits are thermally connected by a cascade condenser, so that the condenser is more cooled than a normal method. Thus, the cooling capacity can be increased.

  When cooling is performed in a multi-source operation, the cooling capacity is increased. However, since a plurality of refrigeration circuits are operated, a large amount of energy is consumed. Therefore, when the cooling capacity is not so required, that is, when the capacity is sufficient with the single operation of operating one refrigeration circuit, it is desirable to operate with the single operation.

Therefore, Patent Document 1 discloses a refrigeration apparatus that can switch between a single operation and a multiple operation.
Japanese Patent Laid-Open No. 2001-174381

  By the way, at the time of the driving | operation by unitary operation, the temperature of the refrigerant | coolant in a compressor may become high depending on the driving | running condition. Thus, if the temperature of the refrigerant becomes too high, the refrigerant itself is likely to be deteriorated and the equipment is easily damaged. Therefore, an injection circuit that branches from between the condenser and the expansion valve and is connected to the compressor via another expansion valve is provided to reduce the temperature rise during compression.

As described above, the operation can be switched between the single operation and the multiple operation (two operation), and the injection circuit is provided by combining the refrigeration cycle of the single operation and the high temperature side refrigeration cycle of the multiple operation. As a thing, the freezing apparatus shown by FIG. 6 can be considered, for example.
This refrigeration apparatus 100 has two refrigeration circuits, a low temperature side refrigeration circuit 101 and a high temperature side refrigeration circuit 102, and a cascade condenser 105 is formed by a condenser 112 of the low temperature side refrigeration circuit 101 and an evaporator 124 of the high temperature side refrigeration circuit 102. The switching of the operation is performed by switching the flow of the refrigerant in the high-temperature side refrigeration circuit 102 by the on-off valves 126, 127, and 128.

In the case of a single operation, the on-off valve 126 and the on-off valve 128 are opened, the on-off valve 127 is closed, and only the compressor 121 of the high-temperature side refrigeration circuit 102 is operated.
Then, the refrigerant passes from the compressor 121 through the condenser 122, the expansion valve 133, and the evaporator 134, enters the compressor 121 and circulates again, takes heat away from the evaporator 134, and lowers the temperature of the cooling target 103. A part of the refrigerant branches from the condenser 122, passes through the expansion valve 125 of the injection circuit 104, and circulates to the compressor 121.

In the case of dual operation, the on-off valve 126 and the on-off valve 128 are closed and the on-off valve 127 is opened, so that both the compressor 111 of the low temperature side refrigeration circuit 101 and the compressor 121 of the high temperature side refrigeration circuit 102 are opened. Drive with moving.
Then, in the high temperature side refrigeration circuit 102, the refrigerant passes from the compressor 121 through the condenser 122, the expansion valve 123, and the evaporator 124, enters the compressor 121 again, and circulates. The temperature of the condenser 112 of the low temperature side refrigeration circuit 101 is lowered.
On the other hand, in the low temperature side refrigeration circuit 101, the refrigerant passes from the compressor 111 through the condenser 112, the expansion valve 113, and the evaporator 114, enters the compressor 111 and circulates again, and takes away heat from the evaporator 114. The temperature of the cooling target 103 is lowered.

  However, when performing dual operation, the low temperature side refrigeration circuit 101 does not function unless the evaporator 124 of the high temperature side refrigeration circuit 102 is cooled. Therefore, immediately after switching from the one-way operation to the two-way operation, the cooling capacity is reduced, and the temperature decrease rate of the cooling target 103 is slow even though the operation is performed in the two-way operation, There was a risk that the temperature would rise.

  Therefore, an object of the present invention is to provide a refrigeration apparatus that is capable of switching between a single operation and a multiple operation and that is unlikely to have a reduced cooling capacity when switching.

  And the invention for achieving the above-mentioned object has a low-temperature side condenser and a low-temperature side evaporator, circulates the refrigerant and cools by the low-temperature side evaporator, a high-temperature side condenser, A high temperature side first evaporator and a high temperature side second evaporator, provided with a high temperature side refrigeration circuit for circulating the refrigerant and cooling with the high temperature side first evaporator or the high temperature side second evaporator, A cascade condenser is formed by the condenser and the high temperature side second evaporator, and the refrigerant is circulated between the high temperature side condenser and the high temperature side first evaporator, and is cooled by the high temperature side first evaporator; The refrigerant is circulated between the high-temperature side condenser and the high-temperature side second evaporator, and the refrigerant is circulated between the low-temperature side condenser and the low-temperature side evaporator. Cool the side condenser and cool it with the low temperature side evaporator. The high temperature side refrigeration circuit has a connection path that functions as a suction injection circuit by circulating the refrigerant without passing through the high temperature side first evaporator during the single operation. A high-temperature side second evaporator that is used in multi-unit operation is disposed in the connection path, and a part of the refrigerant is allowed to flow also to the high-temperature side second evaporator during single-unit operation. The refrigeration apparatus is characterized in that when the low temperature side condenser is cooled and switched from the single operation to the multiple operation, the multiple operation is performed while the low temperature condenser is cooled.

According to the present invention, the high-temperature side refrigeration circuit has a connection path that functions as a suction injection circuit by circulating a part of the refrigerant without passing through the high-temperature side first evaporator during the unitary operation. Since the high-temperature side second evaporator used in the multi-way operation is arranged in the connection path, the refrigerant passes through the high-temperature side second evaporator during the single-way operation, and the low-temperature side condenser Thus, the cooling capacity of the multiple operation can be exhibited immediately after switching from the single operation to the multiple operation.

The invention described in claim 1, in an environment tester having a function of cooling the inside of the tank by the refrigeration system, the refrigeration system, the low-temperature side compressor, the low temperature-side condenser, the low temperature side expansion means and the low temperature side evaporator High-temperature side having a low-temperature side refrigeration circuit, a high-temperature side compressor, a high-temperature side condenser, a high-temperature side first expansion means, a high-temperature side second expansion means, a high-temperature side first evaporator, and a high-temperature side second evaporator A refrigeration circuit, and a cascade condenser is formed by the low temperature side condenser and the high temperature side second evaporator. The high temperature side refrigeration circuit includes a high temperature side compressor, a high temperature side condenser, a high temperature side first expansion means, and a high temperature side. The unitary refrigeration cycle circulating through the first evaporator and the multi-unit refrigeration cycle circulating through the high temperature side compressor, the high temperature side condenser, the high temperature side second expansion means and the high temperature side second evaporator can be switched, to configure centralized refrigeration cycle The road, the high-pressure side branches between the high-temperature side condenser and the high-temperature side first expansion means, is connected path that led and the low-pressure side branches between the high temperature side first evaporator and the high-temperature side compressor is formed, The connection path has expansion means for suction injection, functions as a suction injection circuit that bypasses a part of the refrigerant to prevent the temperature of the refrigerant from rising in the high-temperature side compressor, and is a unitary refrigeration cycle for the high-temperature side refrigeration circuit and one yuan operation with, can switch between multiple operation by the multiple refrigeration cycle and the low temperature side refrigerating circuit in the high temperature side refrigerating circuit, further, the connection path, the low-pressure side branch side than the suction injection expansion means A high temperature side second evaporator is disposed, and a confluence portion is formed between the expansion means for suction injection and the high temperature side second evaporator. The cycle, the high temperature-side refrigerant flows into the low-pressure side branches through the junction section from the connection path of the high temperature side second evaporator from the second expansion means, when the refrigerant is passed through the circuit to configure centralized refrigeration cycle, the refrigerant The low temperature side condenser is cooled by flowing a part of the refrigerant to the high temperature side second evaporator, and the temperature of the refrigerant in the high temperature side compressor is prevented from rising . In this case, multiple operation is performed in a state where the low temperature side condenser is cooled, the inside of the tank is cooled by the low temperature side evaporator and the high temperature side first evaporator, The high temperature side second evaporator is an environmental tester characterized in that it is outside the tank and cannot cool the inside of the tank .

According to the first aspect of the present invention, the high-temperature side second evaporator is arranged on the low-pressure side branch side of the expansion means for suction injection in the connection path functioning as the suction injection circuit in the central refrigeration cycle. And a confluence portion is formed between the suction injection expansion means and the high temperature side second evaporator. In the multi-component refrigeration cycle, the high temperature side of the connection path passes through the confluence portion from the high temperature side second expansion means. Since the refrigerant flows from the second evaporator to the low-pressure side branch, part of the refrigerant passes through the high-temperature side second evaporator and cools the low-temperature side condenser during the single operation. The cooling capacity of the multiple operation can be exhibited immediately after switching from the single operation to the multiple operation.

Moreover, the on-off valve provided on the high temperature side refrigerating circuit, the opening and closing of the valve can be switched centrally refrigeration cycle and multiple refrigeration cycle (claim 2).

According to a third aspect of the present invention, the high-temperature side refrigeration circuit has a switching branch in which piping from the high-temperature side condenser branches, and one of the high-temperature side refrigeration circuits is opened when using the one-way refrigeration cycle. The on-off valve leads to the high-pressure side branch, and the other is from the second on-off valve that is opened when the multi-component refrigeration cycle is used to the merging portion via the high-temperature side second expansion means. The expansion means for suction injection is The refrigeration apparatus according to claim 3, wherein the refrigeration apparatus has a function of preventing a backflow from the merging portion to the high-pressure side branch during multi-source operation.
Here, what has a function which prevents the backflow from a confluence | merging part to a high voltage | pressure side branch at the time of multi-component operation can prevent a backflow by conditions, such as a pressure and temperature.

According to the third aspect of the present invention, the high temperature side refrigeration circuit has a switching branch in which the pipe from the high temperature side condenser branches, and one of the high temperature side refrigeration circuits is opened when the one-way refrigeration cycle is used. The first on-off valve leads to the high-pressure side branch, and the other is from the second on-off valve that is opened when the multi-component refrigeration cycle is used to the merging section through the high-temperature side second expansion means, and the expansion for suction injection Since the means prevents backflow from the junction to the high-pressure side branch during multi-unit operation, the switching between the single operation and multi-unit operation can be performed with two on-off valves, the first on-off valve and the second on-off valve. It can be carried out.

  When the refrigeration apparatus of the present invention is switched from the single operation to the multiple operation, the cooling capacity of the multiple operation immediately after switching is prevented from being lowered, and smooth cooling is possible.

Hereinafter, specific examples of the present invention will be described.
The refrigeration apparatus 1 according to the first embodiment of the present invention has a refrigeration circuit as shown in FIG. 1 and cools the inside of the tank 13 of the environmental tester 5.

  The refrigeration apparatus 1 has two refrigeration circuits, a low temperature side refrigeration circuit 11 and a high temperature side refrigeration circuit 12. The low temperature side refrigeration circuit 11 and the high temperature side refrigeration circuit 12 are separate piping systems.

The low temperature side refrigeration circuit 11 has a low temperature side compressor 21, a low temperature side condenser 22, a low temperature side expansion means 23, and a low temperature side evaporator 24, and is connected by piping to form a circuit in which the refrigerant circulates. ing.
Specifically, the low temperature side refrigeration circuit 11 has only one circulation path and is not provided with a branch or the like. The low temperature side compressor 21, the low temperature side condenser 22, the low temperature side expansion means 23, and the low temperature side evaporator 24 are connected in this order.

And when using the low temperature side freezing circuit 11, the low temperature side compressor 21 is made into an operation state.
Then, the refrigerant that has become high pressure in the low-temperature side compressor 21 moves from the low-temperature side condenser 22 to the low-temperature side expansion means 23, and further, the refrigerant expands to low pressure in the low-temperature side expansion means 23 and then goes to the low-temperature side. It passes through the evaporator 24 and enters the low temperature side compressor 21 again for circulation. When the refrigeration cycle in which the refrigerant circulates is performed, the low temperature side condenser 22 can release heat, and the low temperature side evaporator 24 can take heat from the outside to lower the temperature in the tank 13.

The high temperature side refrigeration circuit 12 includes a high temperature side compressor 31, a high temperature side condenser 32, a high temperature side first expansion means 33, a high temperature side second expansion means 34, a high temperature side first evaporator 35, and a high temperature side second evaporator 36. These are connected by piping.
Further, a cascade condenser 55 is formed by the high temperature side second evaporator 36 and the low temperature side condenser 22 of the low temperature side refrigeration circuit 11. In the cascade condenser 55, the low temperature side condenser 22 can be cooled by the high temperature side second evaporator 36, and the heat of the low temperature side condenser 22 can be transferred to the high temperature side second evaporator 36.

Further, the high temperature side refrigeration circuit 12 is provided with a first on-off valve 37 and a second on-off valve 38, and the flow of the refrigerant in the pipe can be switched.
Then, by changing the open / close state of the first on-off valve 37 and the second on-off valve 38, two refrigeration cycles can be formed in the high-temperature side refrigeration circuit 12, and the one-part refrigeration cycle as shown in FIG. 50 and the two-way refrigeration cycle 51 as shown in FIG. 3 can be switched.

The configuration of the high temperature side refrigeration circuit 12 is shown in FIGS. 1 to 3, and specifically has the following configuration.
First, the high temperature side compressor 31 is connected to the high temperature side condenser 32. In the switching branch 56, the pipe from the high temperature side condenser 32 branches in two directions, one of which is connected to the first on-off valve 37 which is opened when the one-way refrigeration cycle 50 is used, and the other is two When the original refrigeration cycle 51 is used, the second open / close valve 38 is opened.
The second on-off valve 38 is connected to the high temperature side second expansion means 34 and further connected to the junction 57. The junction 57 joins the connection path 62, and the junction 57 is arranged between the suction injection expansion means 63 arranged in the connection path 62 and the high temperature side second evaporator 36. .

The first on-off valve 37 is connected to the high-pressure side branch 60. In the high pressure side branch 60, the pipe from the first on-off valve 37 branches in two directions, one is connected to the connection path 62, and the other is the high temperature side first expansion means 33 and the high temperature side first evaporation. It is connected to the vessel 35.
The connection path 62 connects the high pressure side branch 60 and the low pressure side branch 61. In the connection path 62, a suction injection expansion means 63 and a high temperature side second evaporator 36 are arranged. The high temperature side second evaporator 36 is disposed closer to the low pressure side branch 61 than the expansion means 63 for suction injection.

  In the low pressure side branch 61, the pipe passing through the high temperature side first expansion means 33 and the high temperature side first evaporator 35 and the connection path 62 merge, and further, from the low pressure side branch 61 to the high temperature side compressor 31. Connected.

  The low temperature side evaporator 24 and the high temperature side first evaporator 35 are arranged in the tank 13 of the environmental tester 5 so that the inside of the tank 13 can be cooled.

Next, the one-way refrigeration cycle 50 and the two-way refrigeration cycle 51 will be described.
As shown in FIG. 2, the unitary refrigeration cycle 50 is a refrigeration cycle in which refrigerant circulates by a high temperature side compressor 31, a high temperature side condenser 32, a high temperature side first expansion means 33, and a high temperature side first evaporator 35. It is.
When using the one-way refrigeration cycle 50, the high temperature side compressor 31 is operated with the first on-off valve 37 open and the second on-off valve 38 closed.

Further, as described above, the high pressure side branch 60 is provided between the high temperature side condenser 32 and the high temperature side first expansion means 33, and the high temperature side first evaporator 35 and the high temperature side compressor 31 are provided. In addition, a low pressure side branch 61 is formed, and a connection path 62 that connects the high pressure side branch 60 and the low pressure side branch 61 is formed.
In the single refrigeration cycle 50, the connection path 62 functions as a suction injection circuit, as will be described later.

  In the refrigeration cycle 50 for one unit, the refrigerant that has become high pressure in the high temperature side compressor 31 passes through the first on-off valve 37 from the high temperature side condenser 32 and moves to the high temperature side first expansion means 33. After the refrigerant expands to a low pressure in the first expansion means 33, it passes through the high temperature side first evaporator 35, enters the compressor 31 again, and circulates. When this refrigerant circulates, the high temperature side condenser 32 can release heat to the outside, and the high temperature side first evaporator 35 can take heat from the outside to lower the temperature in the tank 13.

Then, a part of the refrigerant branches from the high pressure side branch 60 and flows through the connection path 62, and merges with the refrigerant that has exited the high temperature side first evaporator 35 at the low pressure side branch 61, to the high temperature side compressor 31. Flow and circulate. This connection path 62 functions as a suction injection circuit.
Therefore, when it operates using the unitary refrigerating cycle 50, the temperature rise of the refrigerant in the high temperature side compressor 31 can be prevented.
Moreover, since the refrigerant passes through the high temperature side second evaporator 36 of the connection path 62, the high temperature side second evaporator 36 absorbs heat and cools the surroundings. As a result, the low-temperature side condenser 22 that becomes the cascade condenser 55 and is thermally connected to the high-temperature side second evaporator 36 is cooled.
In this one-way operation, the refrigerant passing through the high temperature side second evaporator 36 is just after passing through the suction injection expansion means 63, so that the high temperature side second evaporator 36 can be sufficiently cooled. it can.

As shown in FIG. 3, the binary refrigeration cycle 51 is a refrigeration in which refrigerant is circulated by a high temperature side compressor 31, a high temperature side condenser 32, a high temperature side second expansion means 34, and a high temperature side second evaporator 36. Cycle.
When the two-way refrigeration cycle 51 is used, the high temperature side compressor 31 is set in an operating state with the first on-off valve 37 closed and the second on-off valve 38 opened.
Then, the refrigerant that has become high pressure in the high temperature side compressor 31 passes through the second on-off valve 38 from the high temperature side condenser 32 and moves to the high temperature side second expansion means 34, and further, the high temperature side second expansion means 34. Then, the refrigerant expands to a low pressure, and then passes through the high temperature side second evaporator 36 and enters the compressor 31 and circulates again. When this refrigerant circulates, the high temperature side condenser 32 releases heat to the outside, and the high temperature side second evaporator 36 takes the heat of the low temperature side condenser 22 of the low temperature side refrigeration circuit 11.

  Since the high temperature side second evaporator 36 is disposed in the connection path 62, the refrigerant flowing from the high temperature side second expansion means 34 enters the connection path 62 from the junction 57 and passes through the high temperature side second evaporator 36. To the low pressure side branch 61.

The compressors 21 and 31, the condensers 22 and 32, the expansion means 23, 33 and 34, the evaporators 24, 35 and 36, the cascade condenser 55, the refrigerant used, and the on-off valves 37 and 38 used in the refrigeration apparatus 1. In addition, known pipes can be used.
For example, the on-off valves 37 and 38 can use electromagnetic valves, and the expansion means 23, 33, and 34 can use expansion valves.

The connection path 62 of the present embodiment is not provided with an on-off valve. However, since the expansion means 63 for suction injection uses a temperature-type expansion valve that does not backflow during dual operation, During the original operation, no backflow from the junction 57 to the high-pressure side branch 60 occurs.
In addition, as the expansion means 63 for suction injection, the backflow may be prevented by using another expansion valve. In addition, when a device such as a capillary that may cause a backflow is used, a check valve or an on-off valve can be disposed between the high-pressure side branch 60 and the junction 57. When the on-off valve is arranged, the on-off valve is opened during the one-way operation and closed during the multi-way operation.

  And in the refrigeration apparatus 1, the one-way operation | movement which cools the tank 13 of the environmental tester 5 only with the high temperature side freezing circuit 12, and the two way operation performed using both the low temperature side freezing circuit 11 and the high temperature side freezing circuit 12; Is possible. This switching of operation is performed by controlling the first on-off valve 37, the second on-off valve 38, the low temperature compressor 21 and the high temperature side compressor 31, which is performed by a control means (not shown).

  As shown in FIG. 2, the unitary operation is performed using the unitary refrigeration cycle 50 of the high temperature side refrigeration circuit 12, and only the high temperature side compressor 31 is operated and the first on-off valve 37 is opened. Is done. And the temperature in the tank 13 is lowered by the high temperature side first evaporator 35.

  Further, as shown in FIG. 3, the binary operation is performed using the low temperature side refrigeration circuit 11 and the high temperature side refrigeration circuit 12, and the low temperature side compressor 21 and the high temperature side compression. The machine 31 is operated and the second on-off valve 38 is opened. And the temperature in the tank 13 is lowered by the low temperature side evaporator 24.

In the unitary operation, only the high temperature side compressor 31 is operated, which saves energy, and is performed when the temperature in the tank 13 is relatively high.
Moreover, since the cooling capability is high in the multiple operation, the cooling is performed at a relatively low temperature.

  The refrigeration apparatus 1 of the present embodiment is used in the environmental tester 5 and operates when the inside of the tank 13 needs to be cooled. However, when the temperature in the tank 13 is relatively high, the tank 13 is used. When the inside is cooled, a unitary operation is performed. When the temperature in the tank 13 is relatively low, the inside of the tank 13 is cooled, or even when the temperature in the tank 13 is high, the cooling is rapidly performed. Two-way operation is performed.

Therefore, in the process of cooling the tank 13, switching from the one-way operation to the two-way operation may be performed. And in the refrigeration apparatus 1 of this embodiment, it can exhibit immediately after switching the cooling capacity of two-way operation from one-way operation.
That is, when the one-way operation is performed, the one-side refrigeration cycle 50 for the high temperature side refrigeration circuit 12 is used, and the refrigerant passes through the high temperature side second evaporator 36 of the connection path 62. For this reason, the low temperature side condenser 22 itself and the refrigerant inside thereof are cooled, and the low temperature side compressor 21 can be operated in this state. Therefore, the refrigeration cycle by the low temperature side refrigeration circuit 11 is cooled immediately after the operation. Can demonstrate ability. And the cooling in the tank 13 in a binary operation can be performed smoothly.

  In the above-described embodiment, the single operation performed only by the high temperature side refrigeration circuit 12 and the dual operation by the low temperature side refrigeration circuit 11 and the high temperature side refrigeration circuit 12 are performed. For example, it is possible to use a configuration that performs three-way or more multi-way operation instead of two-way operation.

  Further, the positions of the on-off valves 37 and 38 and the positions of the branches 56, 60 and 61 and the merging portion 57 are not particularly limited, and the one-way refrigeration cycle 50 and the two-way refrigeration cycle 51 are switched and used. It is possible to adopt another structure in which the high-temperature side second evaporator used in the binary refrigeration cycle 51 is arranged in the connection path 62 that functions as a suction injection circuit in the single refrigeration cycle 50. it can.

  For example, the refrigeration apparatuses 2 and 3 in the second and third embodiments as shown in FIGS. 4 and 5 can be employed.

The refrigeration apparatus 2 in the second embodiment is shown in FIG. 4, and the position of the on-off valve 37 provided in the refrigeration apparatus 1 in the first embodiment described above is changed. Specifically, an on-off valve 71 is arranged between the high-pressure side branch 60 and the high-temperature side first expansion means 33, and an on-off valve 72 is arranged between the high-pressure side branch 60 and the suction injection expansion means 63, Other structures are the same as those of the refrigeration apparatus 1.
In the one-way operation, the on-off valve 71 is opened, the on-off valve 38 and the on-off valve 72 are closed, and in the two-way operation, the on-off valve 38 and the on-off valve 72 are opened. 71 is closed.

The refrigeration apparatus 3 in the third embodiment is shown in FIG. 5, and the arrangement of the high temperature side first expansion means 33 provided in the refrigeration apparatus 2 in the second embodiment described above is arranged more than the branch 60 a. The other structure is the same as that of the refrigeration apparatus 2 except that the expansion means 63 for suction injection is not provided in the connection path 62.
The operation switching is the same as that of the refrigeration apparatus 2 described above, and the on-off valve 71 is opened during the one-way operation, the on-off valve 38 and the on-off valve 72 are closed, and the two-way operation is performed. The on-off valve 38 and the on-off valve 72 are opened, and the on-off valve 71 is closed.

  Further, although not shown, in the refrigeration apparatuses 2 and 3 in the second and third embodiments, a structure in which a three-way valve is provided in the high-pressure side branch 60 or the branch 60a instead of the on-off valve 71 or the on-off valve 72. The operation may be switched by switching the three-way valve.

It is a refrigerant circuit figure of the freezing apparatus in the 1st Embodiment of this invention. It is a refrigerant circuit figure of the state which operated the freezing apparatus of FIG. FIG. 2 is a refrigerant circuit diagram in a state where the refrigeration apparatus of FIG. It is a refrigerant circuit figure of the freezing apparatus in the 2nd Embodiment of this invention. It is a refrigerant circuit figure of the freezing apparatus in the 3rd Embodiment of this invention. It is a refrigerant circuit figure of the freezing apparatus of a comparative example.

1, 2, 3 Refrigeration apparatus 5 Environmental tester 11 Low temperature side refrigeration circuit 12 High temperature side refrigeration circuit 13 Tank 21 Low temperature side compressor 22 Low temperature side condenser 23 Low temperature side expansion means 24 Low temperature side evaporator 31 High temperature side compressor 32 High temperature Side condenser 33 High temperature side first expansion means 34 High temperature side second expansion means 35 High temperature side first evaporator 36 High temperature side second evaporator 37 First on-off valve 38 Second on-off valve 50 One-way refrigeration cycle 51 Multi-component refrigeration Cycle 55 Cascade capacitor 56 Switching branch 57 Junction section 60 High voltage side branch 61 Low voltage side branch 62 Connection path

Claims (3)

In an environmental tester equipped with a function to cool the inside of the tank with a refrigeration system,
The refrigerating apparatus includes a low temperature side compressor, a low temperature side condenser, a low temperature side expansion means and a low temperature side evaporator, a high temperature side compressor, a high temperature side condenser, a high temperature side first expansion means, and a high temperature side. Side expansion means, a high temperature side first evaporator, and a high temperature side second evaporator, and a cascade condenser is formed by the low temperature side condenser and the high temperature side second evaporator. The refrigeration circuit includes a high-temperature side compressor, a high-temperature side condenser, a high-temperature side first expansion means, and a high-temperature side first evaporator, a central refrigeration cycle, a high-temperature side compressor, a high-temperature side condenser, and a high-temperature side second. The expansion unit and the multi-component refrigeration cycle circulating through the high-temperature side second evaporator can be switched, and the circuit constituting the single-unit refrigeration cycle includes a high-pressure side between the high-temperature side condenser and the high-temperature side first expansion unit. Branch, high temperature side first evaporator and high temperature side Is the low-pressure side branch and is connected path that led the formation during compressor, connecting channel has expansion means for the suction injection, the temperature rise of the refrigerant in the higher temperature side compressor by bypassing a part of the refrigerant It functions as a suction injection circuit to prevent, and can switch between a single operation by a single refrigeration cycle of a high temperature side refrigeration circuit and a multiple operation by a multiple refrigeration cycle of a high temperature side refrigeration circuit and a low temperature side refrigeration circuit, the connection path, and the high temperature side second evaporator is arranged on the low pressure side branch side than the suction injection expansion means, is merging section between the expansion means and the high temperature side second evaporator for suction injection formation In the multi-component refrigeration cycle, the high-temperature side second expansion means passes through the junction and passes from the high-temperature side second evaporator of the connection path to the low-pressure side branch. Refrigerant flows when the refrigerant is passed through the circuit to configure centralized refrigeration cycle, the refrigerant in said high temperature side compressor to cool the low-temperature side condenser by passing also a part of the refrigerant on the high temperature side second evaporator The temperature increase is prevented , and when the unit operation is switched to the unit operation, the unit operation is performed in a state where the low-temperature side condenser is cooled ,
The inside of the tank is cooled by the low temperature side evaporator and the high temperature side first evaporator, and the high temperature side second evaporator is outside the tank and cannot cool the inside of the tank. . The environmental tester according to claim 1 , wherein the high-temperature side refrigeration circuit is provided with an open / close valve, and the open / close valve is opened and closed to switch between the single- unit refrigeration cycle and the multi-component refrigeration cycle. The high temperature side refrigeration circuit has a switching branch in which the pipe from the high temperature side condenser branches, and one of the high temperature side refrigeration circuits leads to the high pressure side branch from the first on-off valve that is opened when using the one-way refrigeration cycle, The other is from the second on-off valve that is opened when the multi-component refrigeration cycle is used, to the merging portion via the high-temperature side second expansion means, and the suction injection expansion means is connected to the merging portion during multi-component operation. The environmental tester according to claim 2 , which has a function of preventing backflow to the high-pressure side branch.

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