JPH0519712Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a refrigeration system, and more particularly, to the structure of an accumulator in a refrigeration system.

(Prior Art) As shown in FIG. 4, the structure of a conventionally known accumulator includes a refrigerant return pipe 1 in a cylindrical container 9'.
0' and a U-shaped compressor suction pipe 11',
An oil return hole 1 is provided at the bottom of the compressor suction pipe 11'.
2' is formed so that oil is returned to the compressor side through the oil return hole 12' (see, for example, Japanese Utility Model Publication No. 57-33345). The diameter of the oil return hole 12' has generally been designed so that the maximum amount of oil returned is greater than or equal to the amount of oil discharged from a compressor operated at a constant frequency.

(Problems to be Solved by the Invention) However, in recent years, compressors with a variable frequency function have been increasingly used as compressors for refrigeration equipment. When using such a compressor, the amount of oil discharged from the compressor B (see Figure 3) suddenly increases in the high frequency range (approximately 85Hz or higher).
When using an accumulator with a structure like the conventional example above, the amount of oil returned from the oil return hole is A (see Figure 3).
As a result, there is a risk that the compressor will run out of oil as a result of an oil stagnation occurring in the accumulator.
In order to deal with this inconvenience, if an attempt is made to increase the oil return by enlarging the oil return hole, the amount of refrigerant returned to the compressor will also increase, resulting in a new problem of lowering the reliability of the compressor.

This invention was made in view of the above points,
The purpose of this is to ensure a sufficient amount of oil return during high frequency operation of the compressor without increasing the diameter of the oil return hole too much.

(Means for Solving the Problems) In the present invention, as means for solving the above problems, as shown in the drawings, a compressor 1 with a frequency variable function, a heat source side heat exchanger 3, an expansion mechanism 4,
In a refrigeration system equipped with a user-side heat exchanger 5 and an accumulator 6, the accumulator 6 is
A container 9, a refrigerant return pipe 10 facing into the container 9, and a compressor suction pipe 11 which has a U-shaped tube shape inside the container 9 and is used to draw gas refrigerant in the container 9 into the compressor 1. An oil return hole 12 is formed at the lowest position in the container 9 in the compressor suction pipe 11, and an oil return hole 12 is formed at the bottom of the container 9 and the compressor suction pipe 11.
An oil return pipe 13 is provided between the oil return pipe 13 and the oil return pipe 13, which performs an oil return function only in a frequency range where the amount of oil discharged from the compressor 1 is larger than the amount of oil returned to the compressor 1 through the oil return hole 12. I am intervening.

(Function) In the present invention, the following effects can be obtained by the above means.

That is, the compressor 1 operates in a high frequency range above a predetermined frequency (that is, the amount of oil protruding from the compressor 1 exceeds the oil return hole 12).
When the operation is performed in a frequency range in which the amount of oil is greater than the amount of oil returned to the compressor 1 through the In addition to the oil returned from the oil return pipe 12, the oil is returned from the oil return pipe 13, which corresponds to the amount of oil projected by the compressor 1 in the high frequency range, and effectively prevents the compressor 1 from running out of oil. It will be done. Note that when the compressor is operated at a frequency below the predetermined frequency, the oil return hole 1 is closed as before.
The oil is returned only from the compressor 2, and an amount of oil returned corresponding to the amount of oil discharged from the compressor 1 is ensured.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

As shown in FIG. 1, the refrigeration system of this embodiment includes a compressor 1 operated at a frequency controlled by a frequency controller 7, a four-way switching valve 2, a heat source side heat exchanger 3, and an expansion It is constructed by sequentially connecting a mechanism 4, a user-side heat exchanger 5, and an accumulator 6 with refrigerant piping. Note that the frequency controller 7 is adapted to be operated by a command from a controller 8.

The accumulator 6, as shown in FIG.
A refrigerant return pipe 10 from the four-way switching valve 2 and a compressor suction pipe 11 formed in the shape of a U-tube are arranged in a cylindrical container 9 so as to face each other. The refrigerant return pipe 10 opens downward at the inner upper part of the container 9, while the inlet opening of the compressor suction pipe 11 opens upward at the inner upper part of the container 9.

At the lowest position in the compressor suction pipe 11, the compressor 1 is connected to a normal frequency (for example, 50 to
An oil return hole 12 is formed with a hole diameter that matches the amount of oil protruding from the compressor 1 when the compressor 1 is operated at a frequency of 60 Hz).

Furthermore, the inner bottom of the container 9 and the compressor suction pipe 1
1 (in this embodiment, a position where a head difference H is created between the two), an oil return pipe 13 is interposed between the two.

The head difference H between both ends of the oil return pipe 13 is as follows:
In FIG. 3, the frequency (≒85Hz) at which the compressor discharge oil amount B suddenly rises or higher (that is, the oil amount discharged from the compressor 1 is the oil amount returned to the compressor 1 via the oil return hole 12). frequency range)
It is desirable that the setting is such that the oil return function can be performed when the compressor 1 is operated.

That is, the pressure inside the container 9 is P ₁ , the pressure at the outlet side of the oil return pipe 13 is P ₂ , the flow rate of refrigerant flowing in the compressor suction pipe 11 is v, and the pressure from the inlet of the compressor suction pipe 11 to the oil return pipe 13 is P 2 . The resistance coefficient up to the exit point is ζ
When, the pressure difference between both ends of the oil return pipe 13 is P ₁ −
P ₂ is given by the following equation.

P ₁ −P ₂ =ζ·v ² /2g Therefore, when the compressor 1 is operated at a low frequency (>85Hz), since the refrigerant flow velocity v is small, P ₁ −P ₂ <H, Since the pressure difference P ₁ - _{P 2} between both ends of the oil return pipe 13 is smaller than the head difference H,
No flow occurs in the oil return pipe 13. On the other hand, when the compressor 1 is operated at a high frequency (>85Hz), the refrigerant flow velocity v increases, P ₁ −P ₂ >H, and the pressure difference between both ends of the oil return pipe 13 P ₁ − P ₂ becomes larger than the head difference H. As a result, oil return pipe 1
3 (ie, oil return action) occurs. When the refrigerant flow velocity v further increases, the pressure difference P ₁ -P ₂ between both ends of the oil return pipe 13 increases, and the amount of oil returned also increases.
In other words, in the high frequency range (>85Hz), the third
As shown by curve C in the figure, the amount of oil returned increases rapidly (that is, oil is returned from both the oil return hole 12 and the oil return pipe 13), and the discharge of the compressor 1 due to the increase in frequency increases. This means that the increase in oil amount can be fully covered. Note that since the pressure difference P ₁ -P ₂ between both ends of the oil return pipe 13 is proportional to the square of the refrigerant flow velocity v, the oil return effect is extremely significant.

In the above embodiment, the oil return pipe 13 is connected to the inner bottom of the container 9 and the compressor suction pipe 11 on the outside of the container 9.
Although the oil return pipe 13 may be provided inside the container 9, the connection position of the inlet or outlet of the oil return pipe 13 may be changed as long as the positional relationship allows the head difference H to be secured. is not limited.

Furthermore, although the above embodiments describe a heat pump type refrigeration system, the present invention is of course applicable to other types of refrigeration systems.

(Effects of the invention) As described above, according to the invention, there is provided a refrigeration system that includes a compressor 1 with a variable frequency function, a heat source side heat exchanger 3, an expansion mechanism 4, a user side heat exchanger 5, and an accumulator 6. In the device, the accumulator 6
, a container 9, a refrigerant return pipe 10 facing into the container 9, and a compressor suction pipe having a U-shaped tube shape in the container 9, and for sucking the gas refrigerant in the container 9 into the compressor 1. An oil return hole 12 is formed at the lowest position in the container 9 in the compressor suction pipe 11, and an oil return hole 12 is formed at the bottom of the compressor suction pipe 11 in the container 9. An oil return pipe 13 is provided between the compressor 1 and the oil return pipe 13, which performs an oil return function only in a frequency range where the amount of oil discharged from the compressor 1 is greater than the amount of oil returned to the compressor 1 through the oil return hole 12. Therefore, in a frequency range (in other words, a high frequency range) where the amount of oil discharged from the compressor 1 is larger than the amount of oil returned to the compressor 1 via the oil return hole 12, the compressor 1
When the is operated, oil is returned to the compressor suction pipe 11 via the oil return pipe 13, and in addition to the conventional oil return from the oil return hole 12, oil is returned from the oil return pipe 13. As a result, the amount of oil discharged from the compressor 1 in the high frequency range is matched, and there is a practical effect that oil shortage in the compressor 1 can be effectively prevented.

In addition, since the amount of oil returned to the compressor 1 can be secured without increasing the diameter of the conventionally provided oil return hole 12, there is no risk of liquid back-up, etc., and the reliability of the refrigeration system is improved. There is also an effect that can be achieved.

[Brief explanation of the drawing]

Fig. 1 is a refrigerant circuit diagram of a refrigeration system according to an embodiment of the present invention, Fig. 2 is a longitudinal sectional view showing the structure of an accumulator in the refrigeration system of Fig. 1, and Fig. 3 is an operating frequency of a compressor in the refrigeration system. FIG. 4 is a longitudinal sectional view showing the structure of a conventionally known accumulator. 1...Compressor, 3...Heat source side heat exchanger, 4...
Expansion mechanism, 5...user side heat exchanger, 6...accumulator, 11...suction pipe, 13...oil return pipe.

Claims (1)

[Scope of utility model registration request] In a refrigeration system equipped with a compressor 1 having a variable frequency function, a heat source side heat exchanger 3, an expansion mechanism 4, a user side heat exchanger 5, and an accumulator 6, the accumulator 6 is placed in a container 9 and inside the container 9. The compressor suction pipe 11 is configured of a refrigerant return pipe 10 that is closed to the outside, and a compressor suction pipe 11 that has a U-shaped tubular shape inside the container 9 and that allows the gas refrigerant in the container 9 to be sucked into the compressor 1. The compressor suction pipe 11 has an oil return hole 1 at the lowest position in the container 9.
2, and between the inner bottom of the container 9 and a proper position of the compressor suction pipe 11, an amount of oil protruding from the compressor 1 is returned to the compressor 1 via the oil return hole 12. A refrigeration system characterized in that an oil return pipe 13 is provided which performs an oil return action only in a frequency range where the amount of oil is greater than the amount of oil being fed.