JPH11142003A - Refrigerating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a pump down operation time to a minimum to cause an early starting of a cooling operation, and improve reliability of a compressor. SOLUTION: A refrigerant circuit is provided consisting of a compressor, a condenser, a solenoid valve, an automatic temperature expansion valve, and an evaporator connected in order. A controller operation selective means executes pump down operations (ST2, ST3) for preventing a wet operation of the compressor when a low pressure of the refrigerant circuit is smaller than a prescribed decision pressure value P0, while the controller operation selective means executes cooling operations (ST2, ST5) when the low pressure is larger than the prescribed decision pressure value P0. When a temperature of a refrigerant discharged from the compressor is in excess of a prescribed decision temperature T0 after the pump down operation is started, the controller operation selective means changes the controller operation from the pump down operation to the cooling operation (ST4, ST5).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration system provided with a refrigerant circuit for circulating a refrigerant by a compressor, and more particularly, to a suitable operation at the time of starting the compressor.

[0002]

2. Description of the Related Art Conventionally, in a refrigerating apparatus provided with a refrigerant circuit in which a compressor, a condenser, an expansion valve and an evaporator are sequentially connected, and a liquid pipe of the refrigerant circuit is provided with an on-off valve, There is known a so-called pump-down operation in which the on-off valve is closed for a certain period of time at startup to limit the amount of refrigerant circulated. By such a pump-down operation, in a subsequent normal operation (cooling operation), liquid compression, oil forming, and the like due to the inflow of the liquid refrigerant into the compressor are prevented.

[0003] However, if the pump-down operation is uniformly performed for a predetermined time when the compressor is started, the low pressure is excessively reduced in a state where the low pressure is not so high, which may cause the stop of the compressor due to the low pressure cut.

Therefore, in order to prevent the low pressure from excessively decreasing, the refrigeration apparatus disclosed in Japanese Patent Application Laid-Open No. 7-19620 detects a low pressure in the refrigerant circuit, and when the low pressure exceeds a predetermined set pressure. The pump down operation is performed for a predetermined time.

[0005]

However, when the pump-down operation is performed based only on the low pressure of the refrigerant circuit, the liquid refrigerant is actually compressed, for example, when the expansion valve controls the refrigerant to a superheated state. In some cases, the pump-down operation is performed for a predetermined time even though there is no danger of flowing into the machine. As a result, the pump-down operation continues even though the cooling operation is possible,
There was a problem that the start of the cooling operation was delayed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to shorten the time required for performing a pump-down operation to minimize the time required for starting a cooling operation and to provide a compressor. The purpose is to improve the reliability.

[0007]

In order to achieve the above object, according to the present invention, the pump-down operation is performed based on the temperature of the discharged refrigerant.

Specifically, the invention according to claim 1 comprises a compressor (4, 54), a condenser (6, 56), an opening / closing means (7, 117), a pressure reducing mechanism (13, 63), and an evaporator ( 11,61) are connected in sequence, a cooling operation for evaporating the refrigerant in the evaporator (11,61) to perform cooling, and starting the compressor (4,54). A refrigerating apparatus configured to selectively execute a pump-down operation performed by controlling opening and closing of the opening and closing means (7, 117) so as to prevent the flow of liquid refrigerant into the compressor (4, 54). The discharge temperature detecting means (32, 82) for detecting the temperature of the refrigerant discharged from the compressor (4, 54), and the discharge temperature detecting means (32, 82) detected during the execution of the pump-down operation. An operation switching means for switching the operation from the pump-down operation to the cooling operation when the discharge refrigerant temperature is higher than the predetermined judgment temperature;
(92).

[0009] According to the above-described invention specific matter, when the compressor (4, 54) is started, the pump-down operation is performed. When the discharged refrigerant temperature is equal to or lower than the predetermined determination temperature, the pump-down operation is continued, and the liquid back to the compressor (4, 54) is reliably prevented. On the other hand, when the discharge refrigerant temperature is higher than the determination temperature, the pump-down operation ends, and the operation is switched to the cooling operation. Therefore, the pump-down operation is stopped to a necessary minimum, and the cooling operation is started early.

The invention according to claim 2 is a compressor (4,54),
The refrigerant circuit (1, 51) is formed by sequentially connecting the condenser (6, 56), the opening / closing means (7, 117), the pressure reducing mechanism (13, 63), and the evaporator (11, 61). , 61) to evaporate and cool the refrigerant, and the opening and closing means (7, 117) so as to prevent the flow of the liquid refrigerant into the compressor (4, 54) when the compressor (4, 54) is started. ) In a refrigeration apparatus configured to selectively execute a pump-down operation performed by controlling the opening and closing of the compressor (4, 5).
(4) a discharge temperature detecting means (32, 82) for detecting the temperature of the refrigerant discharged from the pump, and a discharge refrigerant temperature detected by the discharge temperature detecting means (32, 82) at the time of executing the pump-down operation. 1 if the temperature is higher than the judgment temperature,
17) is switched to the open state, while the discharged refrigerant temperature is
When the temperature is lower than a predetermined second determination temperature equal to or lower than the determination temperature, the switching control means (93) for switching the switching means (7, 117) to a closed state, and when a predetermined time has elapsed after the start of the pump-down operation, An operation switching means (92) for switching the operation from the pump-down operation to the cooling operation is provided.

[0011] According to the above specified matter of the invention, a pump-down operation is performed when the compressor (4, 54) is started. When the discharge refrigerant temperature is higher than the first determination temperature, the opening / closing means (7, 117) is switched to the open state, and the compressor (4, 54) itself is prevented from being overheated. On the other hand, when the discharge refrigerant temperature is lower than the second determination temperature, the opening / closing means (7, 117) is switched to the closed state, and liquid back to the compressor (4, 54) is avoided. When a predetermined time has elapsed since the start of the pump-down operation while performing such opening / closing control, the operation is switched and the cooling operation is started. Therefore, the compressor
(4,54) is prevented from overheating and wet operation, and the compressor (4,5)
4) The reliability is improved.

According to a third aspect of the present invention, in the refrigeration apparatus according to any one of the first and second aspects, the refrigerant circuit
When the compressor (4, 54) is started, the detected value of the low-pressure detecting means (33, 83) is equal to or more than a predetermined judgment pressure value when the compressor (4, 54) is started. In the case of (1), an operation selecting means (91) for executing the pump-down operation and executing the cooling operation when the detected value is smaller than the judgment pressure value is provided.

According to the above-mentioned invention, the refrigerant circuit (1,51)
If the low pressure is equal to or higher than the predetermined determination pressure value, the pump-down operation is executed, and the wet operation of the compressor (4, 54) is avoided. On the other hand, when the low pressure is smaller than the determination pressure value, there is no possibility of starting failure, so that the cooling operation is performed without performing the pump-down operation. Therefore, the cooling operation is started immediately after the device is started.

[0014]

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

<First Embodiment> As shown in FIG. 1, a refrigeration apparatus (10) according to a first embodiment is a refrigerator comprising an external unit (35) and an internal unit (36), circuit
(1) is provided. The refrigerant circuit (1) includes a main circuit (5) and bypass circuits (21), (22), (23), and (24).

The main circuit (5) is a rotary compressor (4)
, Condenser (6), solenoid valve (7) as opening / closing means, thermosensitive cylinder
The automatic temperature expansion valve (13) provided with (9) and the evaporator (11) are sequentially connected in a ring shape. A liquid receiver (8) is provided downstream of the condenser (6). In addition, condenser (6)
A dryer (D) is provided between the solenoid valve and the solenoid valve (7). Temperature-sensitive cylinder (9) of automatic temperature expansion valve (13), which is a pressure reducing mechanism
Is attached to the outlet pipe of the evaporator (11). An external pressure equalizing pipe (12) of the automatic temperature expansion valve (13) is connected to an outlet pipe of the evaporator (11).

The upstream end (21a) of the first bypass circuit (21)
The downstream end (21b) is connected between the evaporator (11) of the main circuit (5) and the suction side of the compressor (4). The first bypass circuit (21) is a circuit for unloading the compressor (4), and is provided with an unloading solenoid valve (15).

The upstream end (22a) of the second bypass circuit (22)
The main circuit (5) is connected between the discharge side of the compressor (4) and the condenser (6), and the downstream end (22b) is connected to the first bypass circuit (21).
Is connected between the upstream end (21a) and the unloading solenoid valve (15). The second bypass circuit (22) is a circuit for controlling an unloading mechanism (not shown) provided in the compressor (4), and is provided with a filter (F) and a capillary tube (16).

The upstream end (23a) of the third bypass circuit (23)
The second bypass circuit (22) is connected between the upstream end (22a) and the capillary tube (16), and the downstream end (23b) is connected to the unloading solenoid valve (15) of the first bypass circuit (21). Edge (21b)
Is connected between. The third bypass circuit (23) is a circuit for equalizing the pressure on the discharge side and the suction side of the compressor (4), and is provided with an electromagnetic valve (17).

The upstream end (24a) of the fourth bypass circuit (24)
The downstream end (24b) is connected between the condenser (6) of the main circuit (5) and the solenoid valve (7), and the downstream end (24b) is connected to the suction side of the compressor (4) in the main circuit (5) and the first bypass circuit (21). ) Downstream end (21b). The fourth bypass circuit (24) is a circuit for injecting a low-temperature refrigerant into the compressor (4) when the temperature of the discharged refrigerant becomes too high, and includes a filter (F) and an electric valve (25). Have been.

The discharge pipe of the compressor (4) is provided with a discharge temperature sensor (32) as discharge temperature detecting means for detecting the temperature of the discharged refrigerant, and a high-pressure switch (14). A high-pressure sensor (31), which is a pressure sensor for detecting the pressure on the high-pressure side of the refrigerant circuit (1), is provided between the discharge side of the compressor (4) and the condenser (6). On the other hand, a low pressure sensor (33) is provided between the suction side of the compressor (4) and the evaporator (11) as low pressure detection means for detecting the pressure (low pressure) on the low pressure side of the refrigerant circuit (1). Have been.

Compressor (4), solenoid valve (7), discharge temperature sensor
(32), the high pressure sensor (31) and the low pressure sensor (33) are connected to the controller (40). As shown in FIG. 2, the controller (40) includes an operation selecting means (91) and an operation switching means (92). When the compressor (4) is started, the operation selecting means (91) executes the pump-down operation when the low pressure is equal to or higher than the predetermined judgment pressure value P0, and executes the pump-down operation when the low pressure is smaller than the judgment pressure value P0. This is control means for executing a cooling operation.
The operation switching means (92) is a control means for switching the operation from the pump-down operation to the cooling operation when the discharge refrigerant temperature is higher than a predetermined determination temperature during the execution of the pump-down operation.

Next, the start control of the compressor (4) will be described with reference to the flowchart of FIG. First, step
After the operation of the refrigeration system (10) is started in ST1, the operation selection means (91) of the controller (40) determines whether the detection value (low pressure) of the low pressure sensor (33) is equal to or higher than a predetermined judgment pressure value P0. Is determined. The determination pressure value P0 is a reference pressure for preventing the low pressure from excessively lowering due to the pump-down operation, and is set to, for example, about 3 kg / cm ² .

When the low pressure is smaller than the judgment pressure value P0, the operation selecting means (91) judges that there is no risk of causing the starting failure of the compressor (4), and proceeds to step ST5 to start the cooling operation. I do. On the other hand, when the low pressure is equal to or greater than the determination pressure value P0,
Proceed to step ST3 to execute a pump down operation.

The pump-down operation is performed as follows. That is, the refrigerant discharged from the compressor (4)
Condensed in the condenser (6), decompressed and expanded by the automatic temperature expansion valve (13), evaporated in the evaporator (11), and circulated into the compressor (4). At this time, the solenoid valve (7) is opened when the detection value of the low pressure sensor (33) is equal to or lower than the predetermined first set pressure value P1, while the low pressure is equal to or higher than the predetermined second set pressure value P2. In case it is closed. The second set pressure value P2 is lower than the first set pressure value P1, for example, the first set pressure value P1 is about 2 kg / cm ² , and the second set pressure value P2 is 0.1 kg / cm ² .
It is set to about 2 kg / cm ² . Therefore, the solenoid valve (7)
In response, the opening / closing control as shown in FIG. 4 is performed, and the amount of refrigerant circulated is reduced. As a result, the low pressure of the refrigerant circuit (1) is maintained at a low pressure within a predetermined range, and the liquid refrigerant is stored in the receiver (8). Accordingly, the inflow of the liquid refrigerant to the compressor (4) is prevented.

Next, proceeding to step ST4, the controller
The operation switching means (92) of (40) determines whether the discharge refrigerant temperature detected by the discharge temperature sensor (32) is higher than a predetermined determination temperature T0. The determination temperature T0 is a temperature used as a reference for determining the degree of wetness of the refrigerant sucked into the compressor (4),
Compressor (4) based on test or simulation in advance
The temperature is set so that the liquid does not flow back into the container. In the present embodiment, the determination temperature T0 is set to 90 ° C. The operation switching means (92) returns to step ST3 to continue the pump-down operation when the discharge refrigerant temperature is equal to or lower than the determination temperature, and proceeds to step ST5 when the discharge refrigerant temperature is higher than the determination temperature. To execute the cooling operation.

In the cooling operation, the solenoid valve (7) is opened, and the refrigerant circulates in the same manner as in the pump-down operation. That is, the refrigerant discharged from the compressor (4) condenses in the condenser (6), expands in the automatic temperature expansion valve (13), and evaporates.
In (11), circulation is performed in which the evaporator vaporizes and is sucked into the compressor (4). As a result, the refrigerating device (10) performs a cooling operation.

As described above, in the present refrigeration system (10), when the pump-down operation is executed, if the discharged refrigerant temperature becomes higher than the judgment temperature T0, the operation is switched from the pump-down operation to the cooling operation. When the refrigerant drawn into the machine (4) becomes dry, the cooling operation can be started immediately. Therefore, useless pump-down operation can be avoided, and the time for the pump-down operation can be kept to a minimum. As a result, the start of the cooling operation can be accelerated.

Since the wet state is detected based on the temperature of the discharged refrigerant, it is possible to accurately estimate the liquid return to the compressor (4). Therefore, liquid back can be reliably prevented, and the reliability of the compressor (4) can be improved.

<Embodiment 2> Embodiment 2 is based on Embodiment 1.
In the refrigerating apparatus (10), the start-up control of the compressor (4) is executed by a method different from that of the first embodiment.

Since the configuration of the refrigeration system (10) is the same as that of the first embodiment, the description is omitted. However, in the present embodiment, as shown in FIG. 5, the controller (40) is operated by the operation selecting means (91).
Open / close control means (93) is provided in addition to the operation switching means (92). The opening / closing control means (93) switches the solenoid valve (7) to the open state when the discharge refrigerant temperature is higher than the predetermined first determination temperature during execution of the pump-down operation, while the discharge refrigerant temperature is lower than the second determination temperature. When small, solenoid valve (7)
Is a control means for switching to a closed state.

The start-up control of the compressor (4) will be described with reference to the flowchart of FIG.

First, after the operation of the refrigeration system (10) is started in step ST11, the operation selection means (91) of the controller (40)
Determines whether the low pressure of the refrigerant circuit (1) is equal to or higher than a predetermined judgment pressure value P0. If the low pressure is smaller than the determination pressure value P0, the process proceeds to step ST19 to start the cooling operation, while if the low pressure is equal to or greater than the determination pressure value P0, the process proceeds to step ST19.
Proceed to 13 to start the pump down operation. In this embodiment, the pump-down operation is started after the solenoid valve (7) is closed. Further, unlike the first embodiment, the opening / closing control based on the first set pressure value P1 and the second set pressure value P2 is not performed.

After starting the pump-down operation in step ST13, the operation switching means (92) determines in step ST14 whether the operation elapsed time from the start of the pump-down operation has reached a predetermined time t. . In the present embodiment, the predetermined time t is set to three minutes. If the operation elapsed time has become 3 minutes or more, the process proceeds to step ST19 to start the cooling operation. On the other hand, if the operation elapsed time is less than 3 minutes, the process proceeds to step ST15.

In step ST15, the open / close control means (9
3) determines whether the discharged refrigerant temperature is higher than the first determination temperature T1. In the present embodiment, the first determination temperature T1 is 90
It is set to ° C. If the discharge refrigerant temperature is higher than 90 ° C., the process proceeds to step ST16, while the discharge refrigerant temperature is 9 ° C.
If it is 0 ° C. or lower, the process proceeds to step ST17.

In step ST16, the solenoid valve (7) in the closed state is switched to the open state, and thereafter, the process returns to step ST14.

On the other hand, in step ST17, the open / close control means (9
3) determines whether the discharged refrigerant temperature is lower than a predetermined second determination temperature T2. The second determination temperature T2 is a value equal to or lower than the first determination temperature T1, and is set to 80 ° C. in the present embodiment. If the discharged refrigerant temperature is lower than 80 ° C., the process proceeds to step ST18, while if the discharged refrigerant temperature is 80 ° C. or higher, the process returns to step ST14.

In step ST18, the solenoid valve (7) in the open state is switched to the closed state, and thereafter, the flow returns to step ST14.

As described above, according to the startup control of the present embodiment, in the pump-down operation, the temperature of the discharged refrigerant is equal to the first temperature.
If the temperature is higher than the determination temperature, the solenoid valve (7) is switched to the open state, so that the compressor (4) can be prevented from overheating. On the other hand, when the discharged refrigerant temperature is lower than the second determination temperature, the solenoid valve (7) is switched to the closed state, so that the liquid back can be reliably prevented. Therefore, the reliability of the compressor (4) can be further improved.

Third Embodiment As shown in FIG. 7, a refrigeration apparatus (60) according to a third embodiment is a refrigerator including an external unit (95) and an internal unit (96). Circuit (5
1) is provided. The refrigerant circuit (51) includes a main circuit (55) and bypass circuits (71), (72), (73), and (74).

The main circuit (55) includes a compressor (54) and an oil separator (5).
2), a condenser (56), a liquid receiver (58), and a first refrigerant channel (121) and a second refrigerant channel (12) provided in parallel with the evaporator (61).
2) are sequentially connected in a ring shape. The first refrigerant flow path (121) is provided with a liquid proportional control valve (EV) composed of a liquid electric valve. In the second refrigerant flow path (122), in order from the upstream side, an in-compartment solenoid valve (117) as an opening / closing means, a temperature automatic expansion valve (63) having a temperature sensing cylinder (59), and an electric A gas proportional control valve (MV) comprising a valve is provided.

The upstream end (71a) of the first bypass circuit (71)
The downstream end (71b) is connected between the evaporator (61) of the main circuit (55) and the suction side of the compressor (54). The first bypass circuit (71) is a circuit for unloading the compressor (54), and is provided with an unloading solenoid valve (65).

The upstream end (72a) of the second bypass circuit (72)
The main circuit (55) is connected between the oil separator (52) and the condenser (56), and the downstream end (72b) is connected to the upstream end (71) of the first bypass circuit (71).
a) and the unloading solenoid valve (65). The second bypass circuit (72) is a circuit for controlling an unloading mechanism (not shown) provided in the compressor (54), and is provided with a filter (F) and a capillary tube (66) in order from the upstream end (72a). ing.

The upstream end (73a) of the third bypass circuit (73) is connected to the oil separator (52), and the downstream end (73b) is connected to the evaporator (61) in the main circuit (55) and the first bypass circuit (73). 71) downstream end (71b)
Is connected between. The third bypass circuit (73) is a circuit for equalizing the pressure on the discharge side and the suction side of the compressor (54), and is provided with a filter (F) and a capillary tube (67) in order from the upstream end (73a). Have been.

The upstream end (74a) of the fourth bypass circuit (74)
The downstream end (74b) is connected between the liquid receiver (58) and the evaporator (61) of the main circuit (55), and is connected to the downstream end (71b) of the first bypass circuit (71) in the main circuit (55). And the downstream end of the third bypass circuit (73)
(73b). Fourth bypass circuit (74)
Is a circuit for injecting a low-temperature refrigerant into the compressor (54) when the discharged refrigerant temperature becomes too high.The filter (F) and the motor-operated valve (75) are arranged in order from the upstream end (74a).
Is provided.

A check valve (CV) is provided between the condenser (56) in the main circuit (55) and the upstream end (72a) of the second bypass circuit (72). A filter (F) is provided on a discharge-side pipe of the compressor (54). A dryer (D) is provided between the liquid receiver (58) in the main circuit (55) and the upstream end (74a) of the fourth bypass circuit (74).

The temperature sensing cylinder (59) of the automatic temperature expansion valve (63) is attached to the outlet pipe of the second refrigerant flow path (122) of the evaporator (11).

The discharge side pipe of the compressor (54) is provided with a discharge temperature sensor (82), a high pressure sensor (81) and a high pressure switch (64). On the other hand, a low-pressure sensor (83) is provided on the suction side pipe of the compressor (54).

The discharge temperature sensor (82), the high pressure sensor (81), the low pressure sensor (83) and the internal solenoid valve (117) are
0). The controller (90) is the first embodiment.
Like the controller (40) of the above, an operation selecting means (91) and an operation switching means (92) are provided.

Next, the operation of the refrigeration system (60) will be described. In the present refrigeration system (60), when the compressor (54) is started, the first embodiment
And the same startup control is performed. That is, the start control is executed according to the flowchart shown in FIG. However, in the present embodiment, the pump-down operation is executed as follows.

That is, the liquid proportional control valve (EV) is set to a fully closed state, and the gas proportional control valve (MV) is set to an open state. Then, the same open / close control as that of the first embodiment is performed on the internal solenoid valve (117). That is, the in-compartment solenoid valve (117) is opened when the low pressure is equal to or lower than the first set pressure value P1, and is closed when the low pressure is equal to or higher than the second set pressure value P2. As a result, the liquid refrigerant is stored in the liquid receiver (58), and liquid back to the compressor (54) is avoided.

Therefore, in the present embodiment, the same effect as in the first embodiment can be obtained.

<Embodiment 4> Embodiment 4 is based on Embodiment 3.
In the refrigeration system (60), the same startup control as in the second embodiment is executed.

Since the configuration of the refrigeration system (60) is the same as that of the third embodiment, its description is omitted. However, in the present embodiment, the controller (90) is provided with the opening / closing control means (93) as in the second embodiment.
It has.

As shown in FIG. 8, in this embodiment, when the pump down operation is started in step ST13,
While the liquid proportional control valve (EV) is set to the fully closed state,
The gas proportional control valve (MV) is set to the open state.

When the temperature of the discharged refrigerant is higher than the first determination temperature in step ST15, the flow proceeds to step ST16.
Proceeding to b, the internal solenoid valve (117) is switched to the open state, and the process returns to step ST14. On the other hand, when the temperature of the discharged refrigerant is lower than the second determination temperature in step ST17, the flow proceeds to step ST17.
Proceeding to 18b, the internal solenoid valve (117) is switched to the closed state, and the process returns to step ST14.

The other steps are the same as in the second embodiment.

Therefore, also in the present embodiment, the same effect as in the second embodiment can be obtained.

[0059]

As described above, according to the first aspect of the present invention, after the start of the pump-down operation, if the discharge refrigerant temperature is equal to or lower than the judgment temperature, the pump-down operation is continued, while the discharge refrigerant temperature becomes lower. If the temperature is higher than the determination temperature, the operation is switched from the pump-down operation to the cooling operation. Therefore, the pump-down operation is not performed when the refrigerant (sucked refrigerant) sucked into the compressor is not wet. Therefore, useless pump-down operation can be avoided, and the cooling operation can be started early. Further, since the degree of wetness of the suctioned refrigerant is estimated based on the temperature of the discharged refrigerant, the wetness state of the suctioned refrigerant can be accurately detected. Therefore, liquid back can be reliably prevented, and the reliability of the compressor can be improved.

According to the second aspect of the present invention, after the start of the pump-down operation, if the discharge refrigerant temperature is higher than the first determination temperature, the opening / closing means is switched to the open state, while the discharge refrigerant temperature is changed to the second determination. If the temperature is lower than the temperature, the opening / closing means is switched to the closed state. Therefore, the overheating operation and the wet operation of the compressor can be avoided, and the reliability of the compressor can be improved.

According to the third aspect of the invention, when the low pressure of the refrigerant circuit is smaller than the determination pressure value, the cooling operation is performed without performing the pump-down operation. Can be started. Therefore, it is possible to further accelerate the cooling operation.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram of a refrigeration apparatus.

FIG. 2 is a block diagram of a controller according to the first embodiment.

FIG. 3 is a flowchart of start control according to the first embodiment.

FIG. 4 is a diagram showing opening / closing control of a solenoid valve.

FIG. 5 is a block diagram of a controller according to a second embodiment.

FIG. 6 is a flowchart of start control according to the second embodiment.

FIG. 7 is a refrigerant circuit diagram of the refrigeration apparatus.

FIG. 8 is a flowchart of start control according to the fourth embodiment.

[Explanation of symbols]

 (4) Compressor (5) Main circuit (6) Condenser (7) Solenoid valve (8) Liquid receiver (9) Thermosensitive cylinder (11) Evaporator (13) Automatic temperature expansion valve (31) High pressure sensor ( 32) Discharge temperature sensor (33) Low pressure sensor (40) Controller

Claims (3)

[Claims] 1. Compressor (4,54), condenser (6,56), opening / closing means
(7,117), a refrigerant circuit (1,51) formed by sequentially connecting a pressure reducing mechanism (13,63) and an evaporator (11,61), and the evaporator (11,61)
And a compressor (4,5)
The pump-down operation, which is performed by controlling the opening / closing means (7, 117) so as to prevent the inflow of the liquid refrigerant into the compressor (4, 54) at the time of starting the 4), is selectively executed. A discharge temperature detecting means (32, 82) for detecting a temperature of the refrigerant discharged from the compressor (4, 54); and a discharge temperature detecting means (3
An operation switching means (92) for switching the operation from the pump-down operation to the cooling operation when the discharge refrigerant temperature detected by (2, 82) is higher than a predetermined judgment temperature. . 2. Compressor (4,54), condenser (6,56), opening / closing means
(7,117), a refrigerant circuit (1,51) formed by sequentially connecting a pressure reducing mechanism (13,63) and an evaporator (11,61), and the evaporator (11,61)
And a compressor (4,5)
The pump-down operation, which is performed by controlling the opening / closing means (7, 117) so as to prevent the inflow of the liquid refrigerant into the compressor (4, 54) at the time of starting the 4), is selectively executed. A discharge temperature detecting means (32, 82) for detecting a temperature of the refrigerant discharged from the compressor (4, 54); and a discharge temperature detecting means (3
(2, 82), when the detected refrigerant temperature is higher than the predetermined first determination temperature, the opening / closing means (7, 117) is switched to the open state while the discharge refrigerant temperature is lower than the predetermined first determination temperature. If the temperature is lower than the second determination temperature, the switching means
Switching control means (93) for switching (7,117) to a closed state, and when a predetermined time has elapsed after the start of the pump-down operation,
An operation switching means (92) for switching an operation from a pump-down operation to a cooling operation, and a refrigeration apparatus characterized by comprising: 3. The refrigeration apparatus according to claim 1, wherein the low pressure detection means detects low pressure of the refrigerant circuit.
When the compressor (4, 54) is started, if the detected value of the low pressure detecting means (33, 83) is equal to or higher than a predetermined judgment pressure value, the pump-down operation is performed, while the detected value is determined by the judgment value. An operation selecting means (91) for executing a cooling operation when the pressure is smaller than the pressure value.