JPH05126419A - Device for controlling oil level in refrigerating apparatus - Google Patents

Abstract

PURPOSE:To eliminate from use parts which are relatively large and expensive and reduce in number of the parts in use so as to make a refrigerating apparatus compact and available at a lower cost and enable appropriately controlling the oil levels even in the case of compressors differing in kind or in capacity. CONSTITUTION:For the control of the oil levels in a refrigerating apparatus 1, a refrigerant line connects a plurality of compressors 2, 3, an oil separator 4, a condenser 5, an expansion valve 7, and an evaporator 8; oil return pipes 10, 10a, 10b provided with solenoid valves 11, 12 connect the oil separator 4 to the compressors 2, 3; the compressors 2, 3 are provided with float switches 13, 14 respectively each being actuated by the rise and fall of the oil level and accordingly outputting signals which control the opening and closing of the solenoid valves 11, 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil level control device for a refrigeration system in which a plurality of compressors are connected by refrigerant piping.

[0002]

2. Description of the Related Art Conventionally, there are mainly the following two types of oil level control devices for this type of refrigeration system.

First, as disclosed in Japanese Utility Model Laid-Open No. 53-109847, the oil separated by the oil separator is temporarily collected in an oil tank, and then an oil regulator attached to each compressor from this oil tank. Supply the oil to
With this oil regulator, an appropriate amount of oil is returned to each compressor, and as disclosed in Japanese Utility Model Laid-Open No. 56-8876, the oil separated by an oil separator is sent to each compressor via an oil return pipe. After returning, the oil level of each compressor is adjusted by an oil equalizing pipe connecting these compressors.

[0004]

However, according to the above configuration, there are problems as described below.

First, although the former method works well in returning the oil to each compressor evenly,
Since relatively large and expensive parts such as an oil tank and an oil regulator are required, there is a problem that the device becomes large and the cost rises.

Further, according to the latter method, since the oil level of each compressor is controlled by the oil equalizing pipe, when the capacities of the compressors are different from each other, the pressure difference generated between the compressors during the total operation causes There was a problem that the oil levels of the compressors differ and it is not possible to control the oil level evenly among the compressors.

The present invention has been made in view of the above point, and by abolishing relatively large and expensive parts and reducing the number of parts, the miniaturization of the apparatus is promoted and the cost is reduced.
It is an object of the present invention to provide an oil level control device for a refrigeration system that can perform an appropriate oil level control even when the compressors have different capacities.

[0008]

According to the present invention, a plurality of compressors, an oil separator, a condenser, a pressure reducing device, and an evaporator are connected by a refrigerant pipe, and the oil separator and each compressor are connected to each other. In an oil level control device for a refrigeration system in which an oil return pipe having an on-off valve is connected, a float switch that operates by the vertical movement of the oil level to generate a signal is provided in each of the compressors. The opening and closing of the on-off valve is controlled by a signal.

[0009]

With the above structure, the oil level control device for a refrigerating apparatus of the present invention can directly control the opening / closing valve by detecting the oil level of each compressor with a float switch. Even if there is a pressure difference between the compressors, the oil level of each compressor can be independently adjusted to an appropriate amount without being affected by this.

Further, the oil level control device can be constructed by a simple method in which a relatively small and inexpensive float switch is attached to each compressor.

As a result, relatively large and expensive parts such as an oil tank can be eliminated, the number of parts can be reduced, the miniaturization of the apparatus can be promoted, the cost can be reduced, and even when the compressor has a different capacity, it is appropriate. It is possible to perform various oil level control.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

Reference numeral 1 is a refrigerating apparatus. This device comprises a 3-hp refrigeration hermetic scroll compressor 2 and a 4-hp refrigeration hermetic scroll compressor 3, an oil separator 4, a condenser 5, a liquid receiver 6, and an expansion valve. 7, an evaporator 8 and an accumulator 9 are connected by piping.

Reference numeral 10 denotes an oil return pipe connecting the oil separator 4 and the compressors 2 and 3, and the oil return pipe is branched from the middle and is connected to the compressors 2 and 3 by branch pipes 10a, 10
b. Reference numerals 11 and 12 are solenoid valves attached to the branch pipes 10a and 10b. 13 and 14 are compressors 2 and 3
It is a float switch attached to.

Since the float switches 13 and 14 have the same structure, the structure thereof will be described by taking the float switch 13 as an example.
A float 17 which is inserted into the column and moves up and down, a magnet 18 mounted in the float, and the column 16
Reed switch 19 provided inside, lead wire 20 connected to this reed switch and drawn out from the upper part of column 16, oil pipe 21 connecting the lower part of said container 15 and the lower part of compressor 2, and container 15 And a pressure equalizing pipe 22 that connects the upper part of the compressor to the compressor 2.

A control device 23 is electrically connected to the float switches 13 and 14 and controls the opening / closing operations of the solenoid valves 11 and 12 based on signals from the float switches.

In the float switch 13, the reed switch 19 is excited when the oil in the container 15 is in an appropriate amount as shown in FIG. 2, that is, when the oil level is between the points A and B. Signal is not output because the contact is opened. Next, when there is much oil in the container 15, that is, when there is much oil in the compressor 2 (when the oil level reaches point A), the float 17 rises and the reed switch 19 is no longer excited. Since the OFF signal is generated, the control device 23 turns OFF the solenoid valve 11.
A signal is output and the solenoid valve 11 is closed. Therefore, the oil is not supplied from the oil separator 4 to the compressor 2, and the oil level in the compressor 2 is maintained at an appropriate level. When the oil in the container 15 is low, that is, when the oil in the compressor 2 is low (the oil level is below the point B), the float 17 descends as shown by the broken line in FIG. The reed switch 19 is not excited and generates an ON signal, and the control device 23 outputs an ON signal to the solenoid valve 11 to open the solenoid valve 11. Therefore, oil is supplied from the oil separator 4 to the compressor 2 via the oil return pipe 10 and the branch pipe 10a. This oil supply is stopped when the oil level in the container 15 rises and reaches a level slightly exceeding point B. That is, since the reed switch 19 has a hysteresis, the reed switch 19 is reached when the point B is slightly exceeded.
Is excited by the magnet 18, and the OFF signal is output due to the opening of the contact due to this excitation.
Is stopped by closing.

Here, in FIG. 2, point A is the OF of the solenoid valve 11.
The position of the float 17 showing the F point, and the B point is the O of the solenoid valve 11.
It is the position of the float 17 indicating the N point.

Similar oil level control is performed for the float switch 14.

In the oil level control device of the refrigerating apparatus thus constructed, the oil level of each compressor 2, 3 is directly compressed by the float switch 13, 14 provided in each compressor 2, 3. Since the opening / closing control of the solenoid valves 11 and 12 can be performed by sensing the oil level of the compressor, even if there is a pressure difference between the compressors 2 and 3, the compressors 2 and 3 are not affected by this. The oil level of 3 can be independently adjusted to an appropriate amount.

Further, the oil level control device can be constructed by a simple system in which the relatively small and inexpensive float switches 13 and 14 are attached to the compressors 2 and 3, respectively.

As a result, relatively large and expensive parts such as an oil tank can be eliminated, the number of parts can be reduced, the miniaturization of the apparatus 1 can be promoted and the cost can be reduced, and the compressors 2, 3
It is possible to perform appropriate oil level control even when the oil has different capacities.

[0023]

As described above, according to the present invention, since the oil level of each compressor can be directly detected by the float switch to control the opening / closing of the opening / closing valve, the pressure of each compressor can be controlled. Even if there is a difference, the oil level of each compressor can be independently adjusted to an appropriate amount without being affected by this.

Further, the oil level control device can be constructed by a simple system in which a relatively small and inexpensive float switch is attached to each compressor.

As a result, relatively large and expensive parts such as an oil tank can be eliminated, the number of parts can be reduced, the miniaturization of the apparatus can be promoted, and the cost can be reduced, and even when the compressor has a different capacity, it is appropriate. It is possible to perform various oil level control.

[Brief description of drawings]

FIG. 1 is a refrigerant circuit diagram showing an oil level control device for a refrigeration system of the present invention.

FIG. 2 is a vertical sectional view showing a float switch of the present invention.

[Explanation of symbols]

 2,3 Compressor 10 Oil return pipe 11,12 Solenoid valve 13,14 Float switch

Claims (1)

[Claims] 1. An oil return system in which a plurality of compressors, an oil separator, a condenser, a pressure reducing device, and an evaporator are connected by a refrigerant pipe, and an on-off valve is provided between the oil separator and each compressor. In the oil level control device of the refrigeration system connecting the pipes, each of the compressors is provided with a float switch that operates by the vertical movement of the oil level to generate a signal, and the opening / closing control of the opening / closing valve is performed by the signal of the float switch. An oil level control device for a refrigeration system, which is characterized by performing the following.