JPH06229634A - Freezer - Google Patents

Abstract

PURPOSE:To provide a freezer which is free from inconveniences at a compressor part, such as a shortage of sealing and an unsmooth lubrication even when a lowering of refrigerant evaporation temperature causes a decreases in the refrigerant circulation amount and further in the freezer oil supply amount from an evaporator side to a compressor. CONSTITUTION:In the title freezer, an oil return pipe 9 provided with a solenoid valve 11 and a capillary tube 13 is connected to and communicated with an injection pipe 6 which is so arranged that it can supply liquid refrigerant condensed by a condenser 3 to a middle pressure part of a compressor 1. Therefore, when an evaporation temperature of the liquid refrigeratnt sensed by a temperature sensor 15 becomes lower than a prescribed value, only if the solenoid valve 11 is opened at a time when the liquid refrigerant is injected, freezer oil accumulated in an oil storing part of an oil separator 2 can be supplied together with the refrigerant to the middle pressure part of the compressor 1. As a result, a shortage of oil can be resolved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for improving reliability in a refrigerating apparatus equipped with a liquid injection cooling type compressor.

[0002]

2. Description of the Related Art A liquid injection cooling system is used for a refrigerating device using a rotary, scroll, screw type compressor or the like, which has a large compression ratio, in order to suppress the temperature rise of the gas refrigerant discharged from the compressor. Is common. This is because a part of the liquid refrigerant can be injected into the intermediate pressure portion of the compressor, so that the refrigerating capacity is not affected by the injection. However, since excessive injection appears as an increase in input rather than an increase in compression amount, it has been conventionally performed to suppress the injection amount by detecting the temperature of the discharge gas refrigerant compressed by the compressor. .

A refrigeration system equipped with an injection control valve whose valve opening degree increases as the temperature of the discharged gas refrigerant increases,
For example, it is disclosed in Japanese Patent Application No. 1-290230. Here, in order to detect the temperature of the discharge gas refrigerant from the compressor, a temperature sensitive cylinder installed by a fixture on the discharge gas refrigerant pipe is used, and the injection is controlled so that the difference between this temperature and the condensation temperature becomes constant. A refrigeration system using a control valve is shown.

Since the valve opening of this injection control valve can be changed linearly, it is possible to obtain the optimum liquid injection for the operating state at that time. Therefore, the degree of superheat of the discharged gas refrigerant is kept constant, and refrigeration operation with a wide evaporation temperature is possible by using the refrigerant R-22 in particular.

However, due to the liquid injection, the oil film of the refrigerating machine oil is destroyed at the sliding portion of the compressor to which the refrigerant such as R-22 is sprayed, and there is a risk of impairing the sealing property of the compression chamber. In particular, under operating conditions in which the refrigerant evaporation temperature in the evaporator has decreased, the circulation amount of the refrigerant decreases, so the refrigeration oil separated from the refrigerant in the oil separator has an oil level in the low pressure crank chamber of the compressor. In a refrigeration system that only has a mechanism for returning oil when the temperature drops, the problem is that the supply of refrigerating machine oil to the compression chamber is insufficient and the sealability of the compression chamber is further impaired, resulting in a significant reduction in compression efficiency. There is.
Therefore, the lower limit of the usable evaporation temperature is usually set.

[0006]

That is, there is a problem that the lower limit of usable evaporation temperature in the conventional refrigerating apparatus is regulated from the viewpoint of refrigerating machine oil supply, and the operating condition range is narrowed. The solution to this point was a problem.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and a compressor, an oil separator, a condenser, a pressure reducer, an evaporator, etc. are sequentially connected by a refrigerant pipe. In a refrigeration system in which an injection pipe for supplying the condensed liquid refrigerant to the intermediate pressure part of the compressor is provided with a flow rate control means, the oil storage part of the oil separator and the injection pipe are connected to the flow rate control means / pressure reducing means. It is intended to provide a refrigerating device characterized by being connected so as to be able to communicate with each other by an oil return pipe provided.

[0008]

When the evaporation temperature of the refrigerant in the evaporator decreases and the refrigerant circulation amount decreases, the oil storage section of the oil separator and the injection pipe are made to communicate with each other, so that the refrigerating machine oil accumulated in the oil storage section of the oil separator is (During liquid injection)
Since it is supplied to the intermediate pressure section of the compressor, even if the refrigerant reflux temperature to the compressor decreases and the refrigerating machine oil inflow to the compressor decreases, the sliding of the compressor The moving part does not run out of freezer oil. Therefore, the sealability of the compression chamber is not impaired, and the refrigeration operation at a lower evaporation temperature becomes possible.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to FIG. Compressor 1, oil separator 2, condenser 3, pressure reducer 4
The evaporator 5 is sequentially connected by a refrigerant pipe.

The refrigerant gas sucked into the compressor 1 is compressed here, becomes a high temperature and high pressure gas, and is discharged.
Flow into. Most of the refrigerating machine oil discharged from the compressor 1 together with the high-temperature and high-pressure refrigerant gas is separated from the refrigerant by the oil separator 2 and is collected in an oil storage section (not shown) provided below the oil separator 2.

The refrigerant gas containing a small amount of refrigerating machine oil and leaving the oil separator 2 flows into an air-cooled condenser 3 and is condensed there to become a low-temperature high-pressure liquid refrigerant. Further, the low-temperature high-pressure liquid refrigerant is decompressed by the decompressor 4, flows into the evaporator 5, evaporates, becomes a low-temperature low-pressure gas refrigerant, and is returned to the compressor 1 in a refrigeration cycle.

Reference numeral 6 is an injection pipe provided with a control valve 7 for controlling the flow rate on the way, and supplies a part of the low-temperature high-pressure liquid refrigerant condensed in the condenser 3 to the intermediate pressure portion of the compressor 1. Piping is possible. And the control valve 7
Is a means for detecting the temperature of the high-temperature high-pressure gas refrigerant compressed and discharged by the compressor 1, for example, the opening degree when the degree of superheat of the refrigerant detected by the temperature sensing cylinder 8 attached to the discharge-side gas refrigerant pipe increases. Since the proportional control is performed so as to increase, overheating of the compressor 1 and the gas refrigerant compressed and discharged from the compressor is effectively prevented.

The solenoid valve 9 is provided with a solenoid valve 11 and a capillary tube 13 in the middle thereof so that the oil storage portion of the oil separator 2, the control valve 7 of the injection pipe 6 and the compressor 1 can communicate with each other when desired. An oil return pipe 10 is provided with a solenoid valve 12 and a capillary tube 14 on the way to connect the oil reservoir of the oil separator 2 and the low pressure crank chamber of the compressor 1 so that they can communicate with each other when desired. It is an oil return pipe. Oil return pipe 9/10
The side communicating with the oil separator 2 may be a common pipe as in the embodiment or a separate pipe.

The solenoid valve 11 is opened when the refrigerant (evaporation) temperature detected by the temperature sensor 15 installed in the discharge side refrigerant pipe of the evaporator 5 becomes lower than a preset predetermined temperature, and the oil separator 2 is opened. It is possible to supply the refrigerating machine oil accumulated in the oil storage section to the intermediate pressure section of the compressor 1, thereby fulfilling the function of eliminating the shortage of the refrigerating machine oil amount in the compression chamber (not shown) of the compressor 1. For this reason, even if the refrigerant evaporation temperature in the evaporator 5 decreases and the refrigerant circulation amount decreases, and the refrigerator oil amount supplied to the compressor 1 via the evaporator 5 decreases, the oil amount becomes insufficient. There is no such thing as a lack of seal in the compression chamber.

As a specific example of the opening / closing operation of the solenoid valve 11, when the refrigerant vaporization temperature becomes equal to or lower than the predetermined temperature, the solenoid valve 11 is opened / closed in synchronism with the opening / closing of the control valve 7 to store the oil in the oil separator 2. It is desirable that the refrigerating machine oil stored in the section is controlled so as to be injected together with the liquid refrigerant into the intermediate pressure section of the compressor 1.

Further, the solenoid valve 12 is controlled so as to open when the oil level of the refrigerating machine oil in the low pressure crank chamber of the compressor 1 falls below a preset predetermined position, and closes when the predetermined position is restored. Therefore, each time the amount of refrigerating machine oil in the low pressure crank chamber of the compressor 1 decreases, the refrigerating machine oil is appropriately supplied from the reservoir of the oil separator 2, and the amount of refrigerating machine oil in the low pressure crank chamber is constantly controlled within a predetermined range. To be done.

By the way, since the present invention is not limited to the above-mentioned embodiment, it can be appropriately modified and implemented without departing from the scope of the claims. For example, since the evaporation temperature of the refrigerant in the evaporator 5 depends on the refrigerant pressure in this portion, a pressure sensor capable of detecting the refrigerant pressure is installed at the same position instead of the temperature sensor 15, and this pressure sensor detects the pressure. Depending on the refrigerant pressure
It is also possible to provide so as to control the opening and closing of the solenoid valve 11 provided in the oil return pipe 9.

Although a refrigerating apparatus having a simple structure is shown in FIG. 1 in order to clarify the gist of the present invention, when actually designing the refrigerating apparatus, the pressure reducing valve 4 and the evaporator 5 are It goes without saying that an appropriate device is incorporated, such as installing a liquid receiver between them.

[0019]

As described above, the present invention provides a compressor /
The oil separator / condenser / pressure reducer / evaporator, etc. are sequentially connected by a refrigerant pipe, and the injection pipe for supplying the condensed liquid refrigerant to the intermediate pressure part of the compressor is equipped with a flow rate control means and is frozen In the device, the oil storage part of the oil separator and the injection pipe are refrigeration devices characterized in that they are communicably connected by an oil return pipe equipped with a flow rate control means / pressure reducing means,

Even if the evaporation temperature of the refrigerant is lowered and the amount of refrigerant returned to the compressor is reduced, the refrigerating machine oil accumulated in the oil storage section of the oil separator (when injecting the liquid refrigerant)
It is also supplied to the intermediate pressure part of the compressor, and the sliding part does not run out of refrigerating machine oil. For this reason, not only the sealability of the compression chamber is not impaired, but also the refrigeration operation at a lower evaporation temperature becomes possible. Further, since the sealing property of the compression chamber is improved, the liquid injection amount can be made smaller than in the past, and the condenser can be downsized, which is a remarkable effect.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an example.

[Explanation of symbols]

 1 Compressor 2 Oil separator 3 Condenser 4 Pressure reducer 5 Evaporator 6 Injection pipe 7 Control valve 8 Temperature sensor 9/10 Oil return pipe 11/12 Solenoid valve 13/14 Capillary tube 15 Temperature sensor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshio Ida 2-18 Keihanhondori, Moriguchi City, Osaka Sanyo Electric Co., Ltd. (72) Tsutomu Mori 2-18th Keihanhondori, Moriguchi City, Osaka Sanyo Denki Co., Ltd. (72) Inventor Hiroshi Nishikawa 2-18 Keihan Hondori, Moriguchi City, Osaka Sanyo Electric Co., Ltd.

Claims (1)

[Claims] 1. A compressor, an oil separator, a condenser, a pressure reducer, an evaporator and the like are sequentially connected by a refrigerant pipe, and an injection pipe for supplying a condensed liquid refrigerant to an intermediate pressure portion of the compressor controls a flow rate. A refrigerating apparatus provided with a means, wherein the oil storage part of the oil separator and the injection pipe are connected so as to be able to communicate with each other by an oil return pipe having a flow rate controlling means and a pressure reducing means.