JPH01314873A - Freezing device for freezing vehicle - Google Patents

Abstract

PURPOSE:To suppress an inflow amount of oil flowing to the suction side of a compressor, to prevent residence of oil, and to reduce the load of a compressor during the starting, by a method wherein an on-off valve being opened and closed by means of a suction pressure of a compressor is mounted to the oil return circuit of an oil separator. CONSTITUTION:When a suction pressure during rotational drive of a compressor 21 is reduced to a given value, a pressure switch is turned ON, and an on-off valve 31 is released. Thereby, oil flows from an oil separator 29 through an oil return circuit 30, and is fed to the suction side of the compressor 21. Meanwhile, when the suction pressure of the compressor 21 is high, the on-off valve 31 holds a closed state through a pressure switch, and no oil is returned to the suction side of the compressor 21. A flow amount of oil and a refrigerant fed to the compressor 21 is suppressed to a minimum, no oil resides to the suction side of the compressor 21, and liquid compression is prevented from occurring. Especially, return of a large amount of oil can be prevented from occurring during a high load, e.g. starting.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a refrigeration Vt device for a refrigerated vehicle, and in particular transfers gas discharged from a compressor to an oil separator, and transfers gas discharged from the oil separator from the oil separator. The present invention relates to a refrigeration system for a refrigerated vehicle that transfers oil separated from gas and discharged to the suction side of the compressor, and is capable of controlling the amount of oil returned to the suction side of the compressor.

(Prior Art) Generally, a refrigeration system for a refrigerated vehicle has a configuration as shown in FIGS. 5 and 6.

As shown in the figure, the refrigerated vehicle 1 is provided with a driver's cab 2 and a container 3, and is also equipped with a refrigeration system.

Specifically, as shown in Figure 6, the refrigeration system has a driver's cab 2
An electromagnetic clutch 3 is provided at the bottom of the electromagnetic clutch 3, and a pressure 1i! fi4 is connected to the compressor 4, a condenser unit 6 having a condenser 5 is connected thereto, and a cooling unit 8 on the right side of the evaporator 7 is also connected.

(Problem to be Solved by the Invention) By the way, in this type of refrigeration system, in order to adjust the amount of oil contained in the gas discharged from the compressor 1fi4, there is a gap between the compressor 4 and the condenser 5. An oil separator 9 is provided, and the oil separated from the gas and discharged by the oil separator 9 is directly returned to the suction side of the compression TA4 via an oil return circuit 10.

For this reason, conventionally, a large amount of oil discharged from the oil separator 9 flows into the suction side of the compressor 4, and when the compressor 4 is stopped for a long time, the oil and refrigerant are trapped, and the compressor 4 compresses the liquid when restarted. There was a problem.

The present invention has been devised to effectively solve the above problems.

The present invention makes it possible to control the withdrawal of oil discharged from an oil separator and returned to the suction side of a compressor, and provides a refrigeration system for a refrigerated vehicle that can prevent liquid compression in the compressor. The purpose is to

[Structure of the Invention] (Means and Effects for Solving the Problems) The present invention provides an oil separator that returns oil to the suction side of the compressor between a compressor and a condenser. The circuit is provided with an on-off valve that opens and closes depending on changes in the suction pressure of the compressor,
Control is performed so that when the suction pressure of the compressor is high, the on-off valve is closed, and when the suction pressure is low, the on-off valve is opened.

(Example) Hereinafter, one embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Figure 1 shows a refrigeration cycle used in a refrigerated vehicle.

As shown in the figure, an electromagnetic clutch 2 is attached to the engine of a refrigerated vehicle.
0 is connected, and the compressor 21 is also connected.

A condenser 22 and a fan 2 are provided on the discharge side of the compressor 21.
A condenser unit 24 with an evaporator 25 and a fan 26 is connected, as well as a cooling unit 27 with an evaporator 25 and a fan 26.

Further, an oil hiberator 29 for separating oil from the gas discharged from the compressor 21 is provided in the circuit 28 connecting the compressor 21 and the condenser 22. An oil return circuit 30 is connected to the suction side of the compressor 21.

In particular, this oil return circuit 30 is provided with an on-off valve 31 that opens and closes it, and this on-off valve 31 is configured to be opened and closed according to changes in the suction pressure of the compressor 21.

Specifically, the on-off valve 31 is opened and closed by an on-off means 32.

As shown in FIG. 2, this opening/closing means 32 has a relay 35 that is connected to a power source 33 via a thermostat 34, and an electromagnetic clutch 36 is connected to this relay 35. Pressure switch 37 that detects
and an on-off valve 31 are connected.

Therefore, the goomostat 34 is ON during cooling operation.
The contact of the relay 35 is turned ON, and then the electromagnetic clutch 36 is energized, so the compressor 2
1 will be rotationally driven.

When the compressor 21 is driven to rotate, if the suction pressure drops to a predetermined pressure, the pressure switch 37 is turned on.
The on-off valve 31 connected thereto opens. Therefore, oil flows out from the oil separator 29 via the oil return circuit 30 and is supplied to the suction side of the compressor 21. On the other hand, when the suction pressure of the compressor 21 is high, the on-off valve 31 is kept closed via the pressure switch 37, and oil does not return to the suction side of the compressor 21.

In this way, the oil discharged from the two oil separators is returned to the compression 121 depending on the suction pressure of the compression 1i 121, or is held in the return circuit 30, and the oil is supplied to the compression #M21. The inflow and hanging of refrigerant is suppressed to a minimum. Therefore, there is no oil stagnation on the suction side of the compressor 21,
No liquid compression occurs. Particularly, it is possible to prevent a large amount of oil from returning at times of high load such as startup.

Further, as shown in FIGS. 1 and 3, an oil return circuit 30 extending from the oil separator 29 is connected to the low pressure side of the condenser 22, and is connected to the bottom of a drain pan 38 provided at the bottom of the evaporator 25. The oil return circuit 3 is guided to the bottom of the drain pan 38 and extends to the bottom of the drain pan 38.
0 is connected to the suction side of the compressor 21 via a cooling vibe 39 attached along the bottom of the drain pan 38.

Therefore, the oil discharged from the oil separator 29 is primarily cooled on the low-pressure side of the condenser 22 and secondarily cooled in the evaporator 25, resulting in multistage cooling.

In this way, the oil discharged from the oil separator 29 is cooled and returned to the compressor 21.
1 is suppressed, an increase in discharge temperature can be suppressed, and deterioration of the refrigerant piping and oil can be delayed.

In addition, since the drain pan 38 is heated by the warm oil discharged from the oil separator 29, the drain pan 38
It is possible to prevent dew build-up.

In this embodiment, the oil discharged from the oil separator 29 is cooled in multiple stages in both the condenser 22 and the evaporator 25, but the present invention is not limited to this.
Either the condenser 22 or the evaporator 25 may be configured to perform cooling.

Figure 4 shows the oil l discharged from the oil separator 29.
This figure shows an embodiment of the present invention for cooling ~.

That is, an oil separator 29 is interposed between the compression Ia 21 and the condenser 22, and an oil separator chamber 41 partitioned by a partition plate 40 is formed within the oil separator 29. tj1
A refrigerant pipe 42 extending from the compressor 21 and a condenser 22 are used to separate oil A from the gas discharged from the compressor 21.
The refrigerant pipes 43 extending from the compressor 21 are connected to each other with a step difference in the vertical direction, and the refrigerant pipe 42 extending from the compressor 21 is inserted into the oil separator chamber 41 and its outlet portion is not obstructed. It is designed to be supported facing the plate 44.

Further, an accumulator chamber 45 is formed in the oil separator 29 below the oil separator chamber 41 with a partition plate 40 in between, and a refrigerant pipe 46 extending from the evaporator 25 is inserted into the accumulator chamber 45. With,
A refrigerant pipe 47 extending from the compressor 21 is inserted and connected.

A capillary tube 48 is connected to the oil separator chamber 41 and the accumulator chamber 45.
One end of this capillary tube 48 is pulled out from inside the oil separator chamber 41 and is wound along the outer periphery of a partition wall 49 that partitions the oil separator chamber 45, while the other end is on the bottom side of the accumulator chamber 45. It is configured to be inserted while facing the camera.

Therefore, gas is taken into the oil separator chamber 41 from the compressor 21, and the oil A separated from the gas in the oil separator chamber 41 is forced into the sharp redup 48 by the internal pressure in the oil separator chamber 45. Become.

In particular, when the oil A passes through the capillary tube 48, the capillary tube 48 is exposed from the oil separator chamber 41 and drawn out to the atmosphere, and the cooled gas from the evaporator 25 is transferred into the accumulator chamber 45. Therefore, the partition wall 49 that partitions the accumulator chamber 45 is cooled down, and the oil A in the capillary duplex 48 loses heat to the atmosphere and the cold partition wall 49, and is cooled down. .

This cooled oil Δ is introduced into the accumulator chamber 45 and transferred to the compressor 21 via the refrigerant pipe 47.

In this way, since the cooled oil A is supplied to the compressor 121, the discharge temperature of the compressor 21 can be maintained properly without increasing, and liquid compression can be prevented, similarly to the above embodiment. Furthermore, gasification of the liquid refrigerant in the accumulator chamber 45 can be promoted by utilizing the heat applied to the oil.

Note that the oil separator and accumulator are separated from each other and connected separately in the refrigeration cycle, and the oil return circuit is connected to the accumulator, and the capillary tube provided in the oil return circuit is tightly wound around the accumulator. It may also be configured so that it can be attached.

[Effects of the Invention] To summarize, according to the present invention, the oil return circuit of the oil separator is provided with an on-off valve that operates at compression-like suction pressure. The amount of oil can be suppressed, oil stagnation can be prevented, and the load on the compressor at startup etc. can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the refrigeration cycle of the refrigeration system of the present invention, Fig. 2 is a diagram showing the electric circuit of the on-off valve, Fig. 3 is a diagram showing the main parts of Fig. 1, and Fig. 4 is a diagram showing another embodiment. FIG. 5 is a schematic diagram showing a refrigerating truck, and FIG. 6 is a diagram showing a conventional refrigeration cycle. In the figure, 21 is a compressor, 22 is a condenser, 29 is an oil separator, and 31 is an on-off valve. Patent applicant: Toshiba Corporation

Claims (1)

[Claims] 1. An oil separator is interposed between the compressor and the condenser to return oil to the suction side of the compressor, and
A refrigeration system for a refrigerating vehicle, characterized in that the oil return circuit is provided with an on-off valve that opens and closes according to changes in the suction pressure of the compressor.