JPH074754A - Refrigerating device - Google Patents

Abstract

PURPOSE:To accurately protect a compressor by a method wherein, after a liquid refrigerant taken out from a liquid receiver or a refrigerant pipe at the outlet opening of the liquid receiver is subcooled by a air cooling type condenser, it is injected through a flow amount control means into the compressor. CONSTITUTION:The refrigerant for liquid injection is sent through the injection pipe 101 branching off a piping 111 between a liquid receiver 4 and a closing valve 5 into a sulcooler 301 formed at a part of an air cooling type condenser 3, the refrigerant subcooled by this condenser 3 is thereafter sent through an injection pipe 102, a closing valve 11 for servicing purpose, a solenoid valve 12 and an injection control valve 13 arranged in that order into an intermediate pressure injection port 201 of a scroll type compressor 2 and, by the resulting latent heat of vaporization, the compressive element is cooled. No flash gas is produced in the piping resisting area of the injection pipe and an invariably proper injection amount is supplied into the injection port 201 of the compressor 2 by the injection control valve 13.

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 the reliability of a refrigeration system that cools a compressor by a liquid injection method.

[0002]

2. Description of the Related Art In a refrigerating apparatus for cooling a compressor by a liquid injection method, if the refrigerant charge amount is insufficient due to a refrigerant leak or the like, the condensed refrigerant cannot be overcooled and flash gas is generated.

This flash gas also enters the liquid injection pipe to increase the passage resistance, so that the amount of the refrigerant passing through the injection amount control means sharply decreases.

If the injection amount is insufficient, the cooling effect of the compressor is lost, and the protective device may operate due to overheating of the discharge gas temperature and the like, and stable operation of the device cannot be performed. Further, if the injection amount becomes insufficient, serious damage such as galling and lock may occur on the compressor before the protective device is activated.

Conventionally, in order to avoid such a situation, the method disclosed in Japanese Utility Model Laid-Open No. 52060/1990 has been devised so that the flash gas does not easily enter the injection pipe.

[0006]

In this conventional method, if the charge amount of the refrigerant is insufficient, the refrigerant supplied to the cooling load side is insufficient before the flash gas is generated in the injection pipe, resulting in poor cooling of the apparatus itself. The operation of the low pressure switch occurred, and the user was informed of the shortage of the charge amount of the refrigerant, and appropriate measures were taken to prevent serious damage such as scoring and locking of the compressor.

However, even if the flash gas is separated by this method and only the liquid component of the refrigerant is supplied to the injection pipe, there is almost no subcooling in the refrigerant. Therefore, the piping resistance of the injection pipe or the head difference Flash gas could be regenerated at high temperatures and was not sufficient for compressor protection.

Further, a method of returning the refrigerant taken out from the liquid receiver to the air-cooled condenser and supercooling again in order to surely obtain the supercooling has been considered, but in this case, a part of the air-cooled condenser is used. Therefore, the size of the condenser must be increased in order to achieve a condensing temperature design equivalent to the case where supercooling is not performed.

If the size of the condenser cannot be increased, the effective heat transfer area of the condenser becomes small and the high pressure protection device may operate at high outside air temperature. In addition, the piping that goes in and out of the air-cooled condenser that has been added to obtain supercooling passes through the entire amount of refrigerant circulation, so a piping diameter equal to or larger than that of the liquid pipe that leads to the cooling load is required. Had the drawback of complicating.

In order to solve such a problem, the present invention relates to a liquid injection type refrigerating apparatus for cooling a compressor, which can reliably protect the compressor even when the refrigerant charge amount is insufficient due to a refrigerant leak or the like. A device is provided.

[0011]

According to the present invention, a refrigeration cycle is constructed by sequentially connecting a compressor, an air-cooled condenser, a liquid receiver, a decompression device, and an evaporator with a refrigerant pipe. In a liquid injection pipe for injecting into a compressor, and a refrigeration system equipped with a means for controlling the injection amount in the middle of this injection pipe,
The refrigerant liquid taken out from the liquid receiver or the refrigerant pipe at the outlet of the liquid receiver is supercooled by the air-cooled condenser and then injected into the compressor through the flow rate control means.

[0012]

In the refrigerating apparatus of the present invention, the refrigerant for injection into the compressor is surely supercooled by the air-cooled condenser, so that the user is prevented from insufficient charging of the refrigerant due to insufficient cooling of the apparatus or operation of the low pressure switch. The compressor can be cooled surely until it is known.

Also, since only the injection refrigerant is supercooled, there is almost no increase in the size of the condenser,
The diameter of the pipe for supercooling is also small in proportion to the injection amount, and the pipe design can be facilitated.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. In the refrigeration cycle in FIG. 1, the low-pressure refrigerant gas sucked into the scroll compressor 2 through the gas-liquid separator 1 is compressed by the compressor 2 into high-temperature and high-pressure gas and discharged. Most of the high-temperature and high-pressure gas is cooled by the air-cooled condenser 3 and liquefied, and enters the liquid receiver 4. The refrigerant, which has become a complete liquid by separating a part of the gas in the receiver 4, passes through the closing valve 5, the filter dryer 6, and the sight glass 7, and is decompressed by the expansion valve 8 (pressure reducing device). It vaporizes in the evaporator 9 and cools the surroundings to perform a cooling action.

The liquid injection refrigerant is guided to a subcooler 301 formed in a part of the air-cooled condenser 3 by an injection pipe 101 branched from a pipe 111 between the liquid receiver 4 and the closing valve 5, and this air cooling is performed. After being supercooled by the condenser 3, it enters the intermediate pressure injection port 201 of the scroll type compressor 2 through the injection pipe 102, the service closing valve 11, the solenoid valve 12, and the injection control valve 13 in order, and is compressed by the latent heat of vaporization. Cool the element.

Since the refrigerant entering the injection pipe 102 is sufficiently supercooled, the flash gas is not generated due to the piping resistance of the injection pipe, the head difference, and the high temperature around the compressor, and the injection control valve 13 is used. A proper injection amount is always supplied to the injection port 201 of the compressor 2.

Further, even if flash gas is generated at the outlet of the receiver 4 due to refrigerant leakage or insufficient refrigerant filling during trial operation, heat exchange of the injection refrigerant is performed in the subcooler 301, so that at the inlet of the injection control valve 13. There is no generation of flash gas, and an appropriate injection amount control is performed. At this time, the amount of the refrigerant supplied to the cooling load side becomes small, so that the user can be made aware of the insufficient refrigerant due to defective cooling of the device, operation of the low pressure switch, or the like.

Further, if the value of the supercooling obtained by the supercooler 301 is designed to be large, the possibility of protecting the compressor becomes high even if the user's recognition of the lack of refrigerant is delayed.

Further, the amount of heat required for supercooling the refrigerant circulating for injection is only a few percent or less of the amount of heat exhausted by the condenser, and in most cases, the size of the condenser needs to be increased due to supercooling. Absent. Further, the injection pipes 101 and 102 need only have an inner diameter of about half of the pipe 401, and the pipe design is relatively easy.

Numeral 20 is a high / low pressure switch for device protection.

FIG. 2 is a refrigerant circuit diagram showing another embodiment of the present invention, in which the injection refrigerant is taken out from an injection refrigerant take-out pipe 401 located below the tip of a refrigerant take-out pipe 111 whose tip is connected to a cooling load. 1 is different from the refrigerant circuit diagram shown in FIG. The same components as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted.

[0022]

By using the refrigerating apparatus of the present invention configured as described above, it is possible to supercool only the refrigerant for injection (1) It is possible to reliably cool the compressor even when the refrigerant is insufficient. Protects the compressor from serious damage such as staking and locking. (2) Since the diameter of the pipe for supercooling the refrigerant can be made small, the pipe design becomes easy.
(3) It is easy to set a large amount of supercooling, and there is no problem even if there is some pressure loss for the solenoid valve, closing valve, etc. included in the injection circuit, and you can select a small size inexpensive solenoid valve / closing valve etc. .

[Brief description of drawings]

FIG. 1 is a refrigerant circuit diagram showing an embodiment of the present invention.

FIG. 2 is a refrigerant circuit diagram showing another embodiment of the present invention.

[Explanation of symbols]

 1 Gas-Liquid Separator 2 Compressor 3 Air-cooled Condenser 4 Liquid Receiver 8 Expansion Valve 9 Evaporator 111 Piping 101 Injection Pipe 102 Injection Pipe

Claims (1)

[Claims] 1. A liquid injection in which a compressor, an air-cooled condenser, a liquid receiver, a decompression device, and an evaporator are sequentially connected by a refrigerant pipe to form a refrigeration cycle, and the refrigerant liquid in the refrigeration cycle is injected into the compressor. In a refrigerating device equipped with a pipe and a means for controlling the injection amount in the middle of this injection pipe, the refrigerant liquid taken out from the refrigerant pipe at the receiver or the receiver outlet was supercooled by the air-cooled condenser. After that, the refrigerating apparatus is characterized in that it is injected into a compressor through a flow rate control means.