JPH02154946A - Refrigerating system - Google Patents

Abstract

PURPOSE:To return the lubricating oil, that flows out in a large amount at start-up, to a compressor so as to avoid the lubricating oil shortage by a method wherein a lubricating oil return path having a diameter larger than a capillary tube is installed parallel with the capillary tube that connects an oil separator and an accumulator, and provided with a differential pressure valve that opens when the pressure difference between high and low pressure sides is little. CONSTITUTION:Lubricating oil is mixed with refrigerant and discharged in a large amount at the start-up of a compressor 1. The refrigerant mixture enters an oil separator 2 and is separated into the refrigerant and lubricating oil. The lubricating oil is returned through a capillary tube 8 leading from the bottom of the oil separator 2 to the compressor, however, the amount of returned lubricating oil is little because the pressure is not high enough immediately after start-up of the compressor. At this time, the lubricating oil is returned from A of a differential pressure valve 10 on an oil return path 9 to the compressor 1 through an orifice 14 of a moving plate 13, a path 12, and a return path 6. When the compressor 1 is continuously operated, a high pressure is established and the delivery rate of lubricating oil becomes constant, the pressure difference between the high and low pressures increases causing a moving plate 13 to overcome a spring 15 and to be pushed against a needle, so that the orifice 14 is closed. At this time, a pressure difference is produced across the capillary tube 8 so that the flow rate is restored to a flow rate corresponding to the delivery rate of the lubricating oil.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to oil return in a refrigeration system of an air conditioner, particularly in a compressor.

Conventional technology In recent years, refrigeration cycles have become more complex, and the compressors themselves have become rotary and scroll types, and control methods have become more diverse, including pole change and inverters. Improvement is emphasized.

An example of the above-mentioned conventional air conditioner refrigeration system will be described below with reference to the drawings.

FIG. 4 shows a conventional air conditioner refrigeration system. In Figure 4, 1 is a compressor that compresses the refrigerant, 2 is a compression F
An oil separator that separates the lubricating oil in the refrigerant discharged from M1, 3 an outdoor heat exchanger that is a condenser, 4 a cooling capillary that is an expansion means, 6 an evaporator that exchanges heat indoors, and 6 a return The pipes 7 are connected in sequence through an accumulator. A capillary tube 8 is led out from the bottom of the oil separator 2 and introduced into the return pipe 6 near the accumulator 7.

The operation of the refrigeration system configured as above will be explained.

First, the refrigerant compressed by the compressor 1 flows out in a mixed state with the lubricating oil held inside the compressor 1 and enters the oil separator 2.

In the oil separator 2, the refrigerant and lubricating oil are separated, and the refrigerant is sequentially circulated to the outdoor heat exchanger 3, cooling capillary 4, indoor heat exchanger 6, and return pipe 6, passes through the accumulator 7, and is returned to the compressor 1, where it is returned to the refrigeration system. form μ. The lubricating oil separated by the oil separator 2 is stored at the bottom of the oil separator 2, led out through a capillary tube 8 provided at the bottom, introduced into the return pipe 6 near the accumulator 7, and mixed with the refrigerant inside the accumulator 7. and returned to the compressor 1.

Problems to be Solved by the Invention However, in the above configuration, the amount of lubricating oil returned by the capillary tube is determined by the pressure difference between the high pressure and the low pressure. A large amount of lubricating oil is mixed with the refrigerant and flows out in large quantities at once. On the other hand, there is a problem in that the amount of lubricating oil returned to the capillary tube is insufficient, and the lubricating oil held in the compressor temporarily decreases, resulting in insufficient lubrication and failures such as seizure of the compressor.

In view of the above problems, the present invention provides a refrigeration system that reliably returns a large amount of lubricating oil that flows out when the compressor is started up into the compressor, eliminates the lack of lubricating oil, and improves the reliability of the compressor.

Means for Solving the Problems In order to solve the above problems, the present invention includes a high-pressure shear/V compressor, an oil separator, an expansion means, an evaporator, and an accumulator. A capillary tube communicating with the accumulator is provided, and an oil return circuit that is thicker than the capillary tube and has a differential pressure valve that opens when the pressure difference between the high pressure and the low pressure is small is provided in parallel with the capillary tube.

Effects of the present invention With the above-described configuration, after a large amount of lubricating oil that temporarily flows out in a mixed state with refrigerant when the compressor is started is separated by oil separation, a portion of the lubricating oil returns through the capillary tube, but the lubricating oil does not return to the compressor. Immediately after startup, the high pressure is difficult to rise, and the lubricating oil is returned to the accumulator through an oil return circuit that has a differential pressure valve that is open when the pressure difference between high and low pressures is small. When it flows out, the lubricating oil is returned through an oil return circuit having a differential pressure valve, and when the high pressure rises and the pressure difference between the high pressure and the low pressure increases, the differential pressure valve closes and the oil is returned only through the capillary tube.

EXAMPLE Hereinafter, a refrigeration system according to an example of the present invention will be described with reference to the drawings.

Incidentally, the same parts as those in the conventional example are given the same reference numerals, and the description thereof will be omitted.

FIG. 1 shows a diagram of a refrigeration system in one embodiment of the present invention. In Figure 1, 1 is a compressor, 2 is an oil separator, 3 is a condenser, 4 is a cooling capillary, 6 is an evaporator, 6
7 is a return pipe, 7 is an accumulator, and 8 is a capillary tube, which are the same as the conventional example.

Reference numeral 9 denotes an oil return circuit, which is arranged in parallel with the capillary tube 8 led out from the bottom of the oil separator 2, has a differential pressure valve 1o in the circuit, and is introduced into the return pipe 6 of the accumulator.

As shown in FIG.
There is a movable plate 13 on the inflow side (-) A) having a needle /v11 fixed to I(...>B) and forming a passage 12 around it, and an orifice 14 in the center.

A spring 16 is installed between the needle/I/11 and the movable plate 13.
When a predetermined pressure difference occurs between the inflow side and the outflow side, the movable plate presses against the spring 16 and contracts. FIG. 3 shows a state in which the movable plate 13 is pressed against the needle/L/11 side and the orifice 14 is closed.

The operation of the freezing system constructed as described above will be explained below.

When the compressor 1 is started in a refrigeration system, the lubricating oil in the compressor 1 is mixed with the refrigerant and temporarily flows out in a large amount. This mixed refrigerant enters an oil separator 2 and is separated into refrigerant and lubricating oil, and the refrigerant is circulated to the normal refrigeration system. On the other hand, the separated lubricating oil is stored at the bottom of the oil separator 2, and some of it is returned through the capillary tube 8 led out from the bottom. Very few. At this time, the lubricating oil flows to the inflow side of the differential pressure valve 1o of the oil return circuit 9 (→
It enters from A), passes through the orifice 14 provided in the center of the movable plate 13, exits through the passage 12 around the needle/L/11, and flows from the outflow side (...) into the return pipe 6 of the accumulator 7 from B). It is mixed with refrigerant and introduced into the compressor 1. Further, as the operation of the compressor 1 continues, the high pressure increases and the outflow of lubricating oil becomes constant. As shown in FIG. is pressed against the needle μ by the spring 16, and the orifice 14 is closed.

At this time, since a pressure difference is generated before and after the capillary tube 8, the lubricating oil can be returned to the accumulator 7 side at a flow rate corresponding to the lubricating oil flowing out from the compressor 1.

As described above, according to this embodiment, by providing an oil return circuit that is thicker than a capillary tube with a differential pressure valve in parallel with the capillary tube led out from the bottom of the oil separator and introduced into the accumulator side, it is possible to temporarily return oil at the time of starting the compressor. When the pressure difference is small in response to a large amount of lubricating oil flowing out, the differential pressure valve is open, and the oil can be returned to the accumulator side by the oil return circuit that has the differential pressure valve, and the differential pressure valve closes when the pressure difference exceeds a predetermined value. In this state, the oil is returned only through the capillary tube, and a refrigeration system is obtained in which the oil return is reliably performed, there is no shortage of lubricating oil in the compressor, and the reliability of the compressor is improved.

Effects of the Invention As described above, the present invention provides a refrigeration cycle comprising a compressor, an oil separator, an expansion means, an evaporator, and an accumulator, which are connected in sequence. In addition to providing a capillary tube that communicates with the accumulator,
By installing an oil return circuit that is thicker than the capillary tube and has a differential pressure valve that opens when the pressure difference between the high pressure and the low pressure is small in parallel with the capillary tube, it is possible to prevent a large amount of lubricating oil that temporarily flows out when the compressor starts up. When the difference between high and low pressures is small, the differential pressure valve opens and can return a large amount of lubricating oil. Further, after operation, if the difference between high and low pressures exceeds a predetermined value, the differential pressure valve is closed, and oil is returned only through the capillary tube. As a result, a highly reliable refrigeration system can be obtained in which the lubricating oil held in the compressor can cope with a temporary large amount of leakage at the time of startup, and eliminates the problem of lubricating oil shortage in the compressor.

[Brief explanation of the drawing]

Fig. 1 is a diagram of the refrigeration system of an air conditioner according to an embodiment of the present invention, Figs. 2 and 3 are sectional views showing the open and closed states of a differential pressure valve used in the embodiment, and Fig. 4 is a diagram of a conventional air conditioner. It is a diagram of the refrigeration system of the machine. 1...Compressor, 2...Oil separator, 3.
...Condenser, 6...Evaporator, 7...
...Accumulator, 8...Capillary tube. 9...
...Oil return circuit, 10...Differential pressure valve. Name of agent: Patent attorney Shigetaka Awano and 1 other person7-
-Bakazuko ν Itto I4- Orifice 15-Spring Diagram

Claims (1)

[Claims] It is equipped with a high-pressure shell type compressor, an oil separator, an evaporator, and an accumulator, and is provided with a capillary tube that communicates the oil separator and the accumulator, and in parallel with the capillary tube, high pressure and low pressure are connected. A refrigeration system comprising an oil return circuit that is thicker than a capillary tube and has a differential pressure valve that opens when the pressure difference is small.