JPH0253636B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a refrigeration system including two compressors in one refrigerant circuit.

As shown in Fig. 1, a conventional refrigeration system of this type has two low-pressure dome-shaped fully hermetic reciprocating compressors 1' and 2' connected in parallel, which are connected to a condenser 3' and an expansion valve 4'. and an evaporator 5' are connected in sequence,
By changing the capacity of each compressor 1', 2' to an arbitrary ratio such as 1:1 or 1:2 and operating both or one of the compressors, the desired capacity control ratio can be achieved. There is something that can be obtained. However, in this case, a thick connecting pipe 6' or Two connecting pipes (not shown) are required, one for pressure equalization and one for oil equalization.
Not only does this require a large space for the compressor unit, but the piping connection work is also complicated and difficult. In addition, in order to omit the above-mentioned connecting pipe, a method of housing two compressor bodies in the same casing has been considered, but in this case, the casing has a flat cross section, so it is difficult to reduce the pressure during operation. Taking this into consideration, there were problems in that the casing became thicker and additional reinforcement was required.

The purpose of the present invention is to eliminate the above-mentioned defects and provide a new refrigeration system that is reliable and has good characteristics at low cost.To achieve this purpose, two compressors are installed. In the refrigeration system, one of the two compressors is a low-pressure dome-shaped totally hermetic compressor, and the other is a high-pressure dome-shaped totally hermetic compressor, and the suction pipe and connecting the discharge pipes to the evaporator and the condenser, respectively, and connecting the suction pipe and the discharge pipe of the high-pressure dome-type hermetic compressor to the low-pressure casing and discharge pipe of the low-pressure dome-type hermetic compressor, respectively; , a capillary tube is connected between the suction pipe and a vicinity of the appropriate oil level in the oil sump at the inner bottom of the sealed casing, and the suction pipe side connection portion of the capillary tube is located at a higher level than the low pressure casing side connection portion. It is characterized by its configuration.

Hereinafter, a refrigeration system according to an embodiment of the present invention will be explained with reference to FIGS. 2 to 4.

As shown in FIG. 2, the refrigeration system of this embodiment has the following features:
Two hermetic compressors 1, 2, condenser 3, expansion valve 4
and an evaporator 5 are connected in sequence,
Low pressure casing 11 as one totally hermetic compressor 1
A low-pressure dome-shaped fully hermetic reciprocating compressor with a reciprocating compressor main body 12 disposed inside is adopted, and a rotary compressor main body 22 is disposed within a high-pressure casing 21 as the other completely hermetic compressor 2. A high-pressure dome-shaped completely hermetic rotary compressor is used. Thus, the suction pipe 7 and the discharge pipe 8 of the low-pressure dome-shaped totally hermetic reciprocating compressor 1 are connected to the evaporator 5 and the condenser 3, respectively, while the high-pressure dome-shaped totally hermetic rotary compressor 2 The suction pipe 9 and the discharge pipe 10 are connected to a suitable position of the low pressure casing 11 of the hermetic reciprocating compressor 1 and a suitable position of the discharge pipe 8, respectively. In the case of this embodiment, a check valve 30 is interposed in the middle of the discharge pipe 10;
is necessary to prevent the backflow of refrigerant when a completely hermetic rotary compressor 2 that does not have a discharge valve (for example, a scroll type or a multi-vane type) is used, and is a type that has a discharge valve. is not necessary.

As shown in FIG. 3, the hermetic reciprocating compressor 1 includes a low-pressure casing 11 that is in an atmosphere of suction gas.
a reciprocating piston 1 driven by an electric motor 13 within the
The reciprocating compressor main body 12, which performs compression within a cylinder 15 by a spring 16, is resiliently supported by a spring 16. Note that the discharge gas is led out of the low pressure casing 11 through the discharge pipe 8.

The inner bottom of the low-pressure casing 11 is an oil reservoir 17 for storing lubricating oil, and on the side periphery of the low-pressure casing 11, a suitable lubricating oil level l or a level slightly above the suitable lubricating oil level l is provided. One end 6a of the oil capillary tube 6 is open.

The other end 6b of the capillary tube 6 is connected from below to the end of the suction pipe 9 of the hermetic rotary compressor 2, and the lubricating oil in the oil reservoir 17 of the low pressure casing 11 is connected to the suction pipe 9 flowing through the suction pipe 9. It is made inhalable by the ejector action of the gas (see Figure 4). Also, one end 6 of the capillary tube 6
The opening position at the other end 6b is slightly higher than the opening position at point a.

Further, the suction pipe 9 of the hermetic rotary compressor 2 is connected to the body of the low pressure casing 11, and the suction gas to the hermetic rotary compressor 2 is supplied through the inside of the low pressure casing 11. The low pressure casing 11 also acts as an accumulator for the hermetic rotary compressor 2.

On the other hand, as shown in FIG.
A rotary compressor main body 22, which performs compression within a cylinder 25 by a rotary piston 24 driven by an electric motor 23, is press-fitted and fixed therein. Reference numeral 27 is an oil reservoir at the inner bottom of the high-pressure casing 21 .

Next, the operation of the illustrated refrigeration system will be explained.

In this refrigeration system, in order to operate two compressors simultaneously, the refrigerant compressed by the hermetic reciprocating compressor 1 and the hermetic rotary compressor 2 is combined into the condenser 3, as shown by the arrow X, It reaches the evaporator 5 via the expansion valve 4 and returns to the hermetic reciprocating compressor 1 after fulfilling its intended purpose. The gas refrigerant required by the hermetic reciprocating compressor 1 is sucked into the cylinder 15 as usual, but it is now sucked into the hermetic rotary compressor 2 from the low-pressure casing 11 via the suction pipe 9. There is. Therefore, even if there is a large amount of unevaporated refrigerant in the refrigerant from the evaporator 5, the low-pressure casing 11 acts as an accumulator for the hermetic rotary compressor 2, and prevents liquid from backing up to the hermetic rotary compressor 2. can. In this case, the fully hermetic reciprocating compressor 1
When the oil level in the oil reservoir 17 becomes higher than necessary, the lubricating oil is returned to the hermetic rotary compressor 2 along with the suction gas refrigerant via the capillary tube 6 by the ejector action in the suction pipe 9. On the other hand, if too much lubricating oil accumulates in the oil sump 27 of the hermetic rotary compressor 2, the oil separation function within the high-pressure casing 21 will be significantly reduced, and the lubricating oil will mix with the discharged gas and flow out to the condenser 3 side. As a result, more oil is returned to the low-pressure casing 11 of the hermetic reciprocating compressor 1, which sucks the oil first.

Furthermore, when the hermetic rotary compressor 2 is stopped and only the hermetic reciprocating compressor 1 is operated, the refrigerant compressed by the hermetic reciprocating compressor 1 passes through the condenser 3, the expansion valve 4, and the evaporator 5. Return to the fully hermetic reciprocating compressor 1. In this case, since the pressure on the suction side of the hermetic rotary compressor 2 is higher than that of the capillary tube 6, lubricating oil flows from the hermetic reciprocating compressor 1 to the hermetic rotary compressor 2 for a short time. Also, as shown in the figure, the capillary tube 6 is connected to the suction pipe 9.
Since the other end 6b is connected from below, even after pressure equalization, the other end 6b of the capillary tube 6 is higher than the one end 6a, so the completely hermetic reciprocating compressor 1 rotates completely due to natural fall. No lubricating oil flows into the compressor 2. Therefore, the completely hermetic rotary compressor 2
There is no risk that the fully hermetic reciprocating compressor 1 will run out of lubricant due to too much lubricant remaining on the side.

Furthermore, when the fully hermetic reciprocating compressor 1 is stopped and only the fully hermetic rotary compressor 2 is operated, the process is exactly the same as when the two units are operated at the same time, and the fully hermetic reciprocating compressor 1 is simply stopped. Therefore, the lubricating oil between the two units is equalized in the same manner as when the two units are operated.

As mentioned above, in the illustrated refrigeration system, if the capacity ratio of the fully hermetic reciprocating compressor 1 and the fully hermetic rotary compressor 2 is selected to be 2:1, both can be operated simultaneously.
Capacity control of 100%, 66% when operating only the hermetic reciprocating compressor 1, and 33% when operating only the completely hermetic rotary compressor 2 can be achieved in an extremely stable manner, enabling operation commensurate with the load, resulting in savings. This makes it possible to provide an electric refrigeration system at low cost.

Although the illustrated embodiment shows a cooling-only refrigeration system, the present invention can of course also be applied to a heat pump type refrigeration system that can perform cooling and heating. By operating only the hermetic reciprocating compressor 1 and adding and operating only the hermetic rotary compressor 2, which has a small capacity, during heating operation, it becomes possible to cover the difference in required capacity between cooling and heating. , there is no need to provide an auxiliary heat source (such as an electric heater) during heating operation.

Next, the effects of the refrigeration system of the present invention will be listed below.

That is, according to the present invention, (1) In a refrigeration system including two compressors 1 and 2 in one refrigerant circuit, one of the compressors 1 and 2 is a low-pressure dome-shaped hermetic compressor. , the other is a high-pressure dome-shaped totally hermetic compressor,
Suction pipe 7 of the low pressure dome type hermetic compressor 1
and a discharge pipe 8 are connected to the evaporator 5 and the condenser 3, respectively, while the suction pipe 9 and the discharge pipe 10 of the high-pressure dome-shaped totally hermetic compressor 2 are connected to the low-pressure casing 11 of the low-pressure dome-shaped compressor 1, respectively. and the discharge pipe 8, and furthermore, the oil sump 1 at the inner bottom of the low pressure casing 11.
Since the capillary tube 6 is connected between the vicinity of the proper oil level at 7 and the suction pipe 9, a flexible capillary tube 6 can be used in place of the pressure and oil equalizing pipe required in the conventional example. By using this, the degree of freedom of installation can be expanded and the connection work can be simplified, and the low-pressure casing 11 can also function as an accumulator for the high-pressure dome-type hermetic compressor 2, making the compressor part more compact and reducing costs. (2) Since the capillary tube 6 is connected between the suction pipe 9 and the vicinity of the appropriate oil level in the oil sump 17 at the inner bottom of the low pressure casing 11, a high pressure dome-shaped totally hermetic compressor can be used. 2, the ejector action in the suction pipe 9 forces the lubricating oil accumulated in the low-pressure dome-shaped hermetic compressor 1 to the hermetic compressor 2 side. (3) Since the connection part on the suction pipe 9 side is located higher than the connection part on the low pressure casing 11 side in the capillary tube 6, it is possible to easily equalize the oil in the compressors 1 and 2. Even if 2 is out of operation,
This prevents lubricating oil from naturally falling from the operating low-pressure dome-type hermetic compressor 1 side to the stopped high-pressure dome-type hermetic compressor 2 side, and lubricates the stopped compressor 2 side. This has excellent effects such as preventing the compressor 1 side from running out of lubricating oil due to too much oil accumulating.

[Brief explanation of the drawing]

Figure 1 is a refrigerant circuit diagram of a conventional refrigeration system;
The figure is a refrigerant circuit diagram of a refrigeration system according to an embodiment of the present invention, and FIGS. 3 and 4 are a low-pressure dome-shaped fully hermetic reciprocating compressor and a high-pressure dome-type fully hermetic rotary compressor in the refrigeration system of FIG. FIG. 1...Low pressure dome type hermetic compressor, 2...High pressure dome type hermetic compressor, 3...Condenser, 5...Evaporator,
7, 9... Suction pipe, 8, 10... Discharge pipe, 11... Low pressure casing.

Claims (1)

[Claims] 1 Desired capacity control operation is possible by sequentially connecting two compressors 1 and 2, condenser 3, and evaporator 5 and selectively operating both or one of the compressors 1 and 2. In the refrigeration system, one of the compressors 1 and 2 is a low-pressure dome-shaped totally hermetic compressor, the other is a high-pressure dome-shaped totally hermetic compressor, and the low-pressure dome-shaped totally hermetic compressor is While connecting the suction pipe 7 and discharge pipe 8 of the machine 1 to the evaporator 5 and condenser 3, respectively,
The suction pipe 9 and the discharge pipe 10 of the high-pressure dome-shaped hermetic compressor 2 are connected to the low-pressure casing 11 and the discharge pipe 8 of the low-pressure dome-shaped compressor 1, respectively, and the oil at the inner bottom of the low-pressure casing 11 is connected to the A capillary tube 6 is connected between the vicinity of the appropriate oil level in the reservoir 17 and the suction pipe 9, and the connection portion of the capillary tube 6 on the suction pipe 9 side is located at a higher level than the connection portion on the low pressure casing 11 side. A refrigeration device featuring: