JPH051868A - Refrigerating device - Google Patents

Abstract

PURPOSE:To return oil in refrigerant, which is stagnated in the evaporator of a refrigerating device, into a compressor by supplying high-pressure liquid refrigerant. CONSTITUTION:A refrigerating device is provided with a bypass circuit 7, bypassing a pressure reducing device 3, while the bypass circuit 7 is provided with a solenoid valve 8 which opens and/or closes the circuit 7. Upon operating the refrigerating device, the solenoid valve 8 is opened periodically to supply high-pressure liquid refrigerant from a condenser 2 into an evaporator 4 periodically while bypassing the pressure reducing device 3. Oil, stagnated in the evaporator 4, is returned forcibly into the compressor 1 by the high-pressure liquid refrigerant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil return device for a refrigeration system.

[0002]

2. Description of the Related Art As a refrigerating apparatus conventionally used for refrigerating foods, etc., as shown in FIG. 4, a compressor 1, a condenser 2, a capillary 3, an evaporator 4 and an accumulator 5 are connected by a refrigerant pipe 6. There is a so-called accumulator cycle refrigeration system connected. Reference numeral 10 is an electromagnetic clutch of the compressor 1, 11 is a blower fan of the condenser 2, and 12 is a blower fan of the evaporator 4.

In the above refrigerating apparatus, in order to maintain the freshness of food by keeping the inside of the freezer 100 at low temperature and high humidity, the freezer 1
It is necessary to reduce the difference between the temperature in 00 and the evaporation temperature of the evaporator 4, and for this reason, the evaporator 4 having a large capacity is used.

[0004]

However, as the capacity of the evaporator increases, the oil in the refrigerant discharged from the compressor tends to accumulate in the evaporator, particularly in the refrigerating apparatus, so that the oil may pass through the accumulator from the evaporator. As a result, oil returns to the compressor poorly, which may result in poor lubrication due to lack of oil in the compressor.

The present invention has been made in view of the above problems, and an object of the present invention is to reliably return the oil accumulated in the evaporator to the compressor by periodically supplying a high-pressure liquid refrigerant to the evaporator. To do.

[0006]

In order to achieve the above object, the present invention provides a refrigeration system in which a compressor, a condenser, a pressure reducing device, and an evaporator are sequentially connected, and a bypass for bypassing the pressure reducing device. A circuit, a solenoid valve arranged in the bypass circuit to open and close the bypass circuit, and a cycle of the solenoid valve so that the temperature of the outlet piping part of the evaporator does not become equal to or higher than the melting temperature during the operation of the refrigeration system. The control means for dynamically opening the valve is used.

[0007]

According to the above means, the solenoid valve is periodically opened during the operation of the refrigeration system. Therefore, when the solenoid valve is opened, the high pressure liquid refrigerant bypasses the decompression device and is supplied to the evaporator. Therefore, the oil accumulated in the evaporator is forcibly returned to the compressor by this high-pressure liquid refrigerant.

Since the high pressure and high temperature liquid refrigerant is periodically supplied to the evaporator so that the temperature of the outlet pipe portion of the evaporator does not exceed the melting temperature, the evaporation by the supply of the high pressure liquid refrigerant is performed. The decrease in the cooling capacity of the vessel can be suppressed.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration diagram of the refrigerating apparatus of the present invention.
In FIG. 1, 1 is driven by an engine or an electric motor (neither is shown) via an electromagnetic clutch 10.
A compressor for compressing and discharging the refrigerant, 2 a condenser for condensing and liquefying the high-temperature and high-pressure gas refrigerant discharged from the compressor 1, 3 a capillary for decompressing and atomizing the liquid refrigerant from the condenser 2.
Is an evaporator that evaporates the atomized refrigerant from the capillary 3 and cools it by an endothermic action. Reference numeral 5 is an accumulator that draws out the gas refrigerant from the gas-liquid two-phase refrigerant from the evaporator 4. A refrigerant circuit is formed which is sequentially connected and in which the refrigerant circulates in the direction of the solid line arrow. In addition, 11 is a condenser fan, 12 is an evaporator fan, and 100 is an evaporator 4.
The above is the same as the conventional configuration shown in FIG.

A difference from the conventional configuration shown in FIG. 4 is that a bypass circuit 7 that bypasses the capillary 3 is provided, and an electromagnetic valve 8 is provided in this bypass circuit 7. The point is to open the valve.

FIG. 2 is an electric circuit diagram of a main part of the refrigerating apparatus of the present invention. In FIG. 2, 10a is a relay of the electromagnetic clutch 10, 11a is a relay of the condenser fan 11,
2a is a relay of the evaporator fan 12, one of each of these relays 10a, 11a and 12a is connected via a refrigeration switch 23 from a power supply 24, and the other is connected to the control circuit 20.
It is connected to the.

An electromagnetic valve 8 for opening and closing the bypass circuit 7 is connected to the control circuit 20, and a later-described periodic opening of the electromagnetic valve 8 which is a feature of the present invention is programmed.
The control circuit 20 is connected to a temperature sensor 21 that detects the temperature inside the freezer 100 and a pressure switch 22 that is provided at the outlet piping of the condenser 2 and that detects an abnormality in the refrigerant pressure. The circuit is configured.

Next, the operation of the above structure will be described with reference to FIGS. 1 and 2 and FIG. 3 showing a time chart. When the freezing switch 23 is turned on, the control circuit 2
0 is energized, the relay 12a is closed, the evaporator fan 12 is operated, and air is blown to the evaporator 4. t ₀ hours (about 5 minutes)
After a lapse of time, the relay 11a is closed and the condenser fan 11 is operated to blow air to the condenser 2. At the same time, the relay 10a is closed and the electromagnetic clutch 10 is operated to drive the compressor 1 to start the operation of the refrigeration system.

After the start of operation of the refrigeration system, t ₁ hour (about 10
After a lapse of (minutes), the solenoid valve 8 is energized and the solenoid valve 8 is t
The valve is opened for a time (about 5 seconds), and the high-pressure liquid refrigerant from the condenser 2 bypasses the capillary 3 and is supplied to the evaporator 4. It should be noted that the solenoid valve 8 is opened for t hours in this cycle of t ₁ hours, which is repeated several times.

After the above repetition is completed, t ₂ hours (about 60
After a lapse of (minutes), the solenoid valve 8 is energized and the solenoid valve 8 is t
The valve is opened for a time (about 5 seconds), and the high-pressure liquid refrigerant is supplied to the evaporator 4 as described above. It should be noted that the repetition of opening the solenoid valve 8 for t hours in the cycle of t ₂ hours is performed until the operation of the refrigeration system is stopped.

As described above, since the high pressure liquid refrigerant is supplied to the evaporator 4 from the condenser 2 by the periodic opening of the solenoid valve 8, the high pressure liquid refrigerant accumulates in the evaporator 4. The oil is sent to the accumulator 5, flows into a small hole (not shown) of the gas refrigerant outlet pipe 5a provided in the accumulator 5, and is forcibly returned to the suction side of the compressor 1 via the outlet pipe 5a.

Here, after turning on the freezing switch 23, t ₀
It is the compressor 1 that stops the operation of the refrigeration system for a certain period of time.
For the protection of. However, when the compressor 1 may be driven at the same time when the refrigerating switch 23 is turned on, this delay of operation for t ₀ time is not necessary.

As described above, opening the solenoid valve 8 for t hours in a short cycle of t ₁ hours for a while after the start of operation of the refrigerating device is because the refrigerant stagnates at the time of startup. This is because the oil accumulated in the evaporator 4 easily comes out of the evaporator 4 by supplying the high-pressure liquid refrigerant.

By the way, there is a method of defrosting the evaporator by opening the solenoid valve to bypass the pressure reducing device and supplying a high temperature liquid refrigerant from the condenser to the evaporator when the evaporator is frosted. It is necessary to open the solenoid valve for a long time (several minutes) for defrosting, and the temperature of the outlet pipe portion 4a of the evaporator shown in FIG. 1 is about 3 ° C. or higher for melting frost. , Which temporarily reduces the cooling capacity of the evaporator.

On the other hand, in the present invention, since the opening time of the solenoid valve is short (several seconds), the temperature of the outlet pipe section 4a of the evaporator shown in FIG. 1 is maintained below the freezing temperature, Almost no decrease in the cooling capacity of the evaporator occurs.

Next, in this embodiment, the capillary is used as the pressure reducing device, but other pressure reducing devices such as an expansion valve may be used. Further, although the present embodiment is applied to the refrigerating device of the accumulator cycle, it can also be applied to refrigerating devices other than the accumulator cycle as long as the oil easily accumulates in the evaporator.

In this embodiment, the valve opening period and the valve opening time of the solenoid valve were programmed in the control circuit by the values obtained in advance by experiments, but a temperature sensor was attached to the outlet pipe of the evaporator. Alternatively, the control circuit may directly control the valve opening period and the valve opening time of the solenoid valve according to the temperature detected by the temperature sensor.

[0023]

Since the present invention is constructed as described above, the oil accumulated in the evaporator is reliably returned to the compressor by the periodic supply of the high-pressure liquid refrigerant, so that the oil of the compressor is Lubrication failure due to lack is prevented.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a refrigeration apparatus of the present invention.

FIG. 2 is an electric circuit diagram of a main part of FIG.

FIG. 3 is a time chart for explaining the operation.

FIG. 4 is a schematic configuration diagram of a conventional refrigeration system.

[Explanation of symbols]

1 compressor 2 condenser 3 Capillary (pressure reducing device) 4 evaporator 4a Evaporator outlet piping 7 Bypass circuit 8 solenoid valve 20 Control circuit (control means)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hisashi Matsunaga             Nihonden, 1-1, Showa-cho, Kariya city, Aichi prefecture             Sozo Co., Ltd.

Claims (2)

[Claims] 1. A refrigeration system in which a compressor, a condenser, a decompression device, and an evaporator are sequentially connected, and a bypass circuit for bypassing the decompression device and a bypass circuit disposed in the bypass circuit for opening and closing the bypass circuit. An electromagnetic valve, and a control means for periodically opening the electromagnetic valve so that the temperature of the outlet pipe portion of the evaporator does not exceed the freezing temperature during the operation of the refrigerating apparatus. Refrigeration equipment. 2. The refrigerating apparatus according to claim 1, wherein a valve opening cycle of the solenoid valve is shortened at an initial stage of operation of the refrigerating apparatus.