JPH0339864A - Refrigerating compressor cryostatic - Google Patents

Abstract

PURPOSE:To prevent refrigerating capacity from decreasing due to overheating and to increase an operating range of low temperature zone by pressure-reducing liquid refrigerant condensed by a condenser by a second pressure reducing unit, cooling suction gas overheated by cooling a motor, pouring it in a compressing chamber so that pressure-reduced refrigerant becomes an intermediate pressure, sucking suction gas from a suction port of the chamber to compress it. CONSTITUTION:Refrigerant gas sucked from a suction tube 17 flows around a motor 13 to cool the motor 13, and the suction gas is heated to be expanded to pass through a passage 19. Liquid refrigerant condensed by a condenser 2 is pressure-reduced by a second pressure reducing unit 4, heated by the motor 13 so that the suction gas heated by the motor 13 to show a high temperature is thermally exchanged by a suction gas cooler 9, and the suction gas is sucked into a suction port 7 of the chamber. The refrigerant heat exchanged with the suction gas is poured in inlets 11a, 11b on the way of compression, cooled, combined with refrigerant on the way of suction and compression from the port 7, discharged from a discharge tube 19, condensed by the condenser 2, and circulated. As described above, the suction gas heated by the motor 13 can be recooled to improve its performance.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention is directed to a low-temperature refrigeration pressure m that prevents a decrease in the refrigerating capacity caused by overheating of the suction gas D and enables an expansion of the operating range in the low-temperature region. = related.

[Conventional technology]

In the conventional closed-type refrigeration pressure #f machine that cools electric m* with suction gas, the specific volume of suction gas increases due to the heating of suction gas that accompanies motor cooling, and the amount of refrigerant vfI term decreases. There is a problem in that the refrigerating capacity decreases.

This effect increases as the temperature increases.Furthermore, if the temperature is used for low temperature applications, the refrigeration capacity will not decrease, and the temperature of the iron gas before being sucked into the compression chamber will become high due to the cooling of the electric IIB machine. As a result, the temperature of the discharged gas becomes abnormally high, making it impossible to use it as a refrigeration pressure vessel. As described above, conventional refrigeration compressors suffer from low refrigeration capacity due to heating of intake gas, and their practical use as refrigeration compressors is limited.

[Section 1 to be solved by the invention] The present invention solves the four problems of the prior art and provides a
This prevents the loss of suction gas due to mouth heat and secures the refrigerating capacity, and also prevents the discharge gas temperature from rising, thereby expanding the range of use for low-temperature applications.

[Means to solve the problem]

In order to achieve the above purpose, the liquid refrigerant condensed in the condenser is depressurized in a second pressure reducing device, and the latent heat of the depressurized refrigerant is used to
! The heated suction gas is recooled by the cooling V in step 4 before being sucked into the compression chamber to prevent heating loss. The reduced pressure refrigerant that has cooled the suction gas is sucked into the compression chamber V during compression, compressed and discharged together with the suction gas, and condensed again in the condenser. Injecting the reduced pressure refrigerant from the compression chamber during compression in this manner is possible with a normal positive displacement compressor. It is especially suitable for scroll type pressure*a machines and scree type compression chambers in which the intermediate pressure chamber during compression is shaped like 'J? An example of the structure of a scroll type compressor, for example, is shown in Japanese Patent Application Laid-open No. 76289/1983.

The present invention attempts to eliminate the problems of the prior art by cooling suction gas that has been heated up by the electric motor using the latent heat of the decompressed refrigerant. Another method is to suck the suction gas directly into the compression chamber, prevent the suction gas from being heated by the motor, etc., and cool the motor with the latent heat of the depressurized refrigerant.
Similarly, the same effect can be obtained by injecting it during compression.

[Effect]

With the above-described configuration, the suction gas, which is heated and expanded to increase its specific volume by cooling the electric motor, is cooled before being sucked into the compression chamber, and then is compressed if it is sucked. Therefore, it is possible to prevent a reduction in the refrigeration power due to heating of the intake gas. Furthermore, by suctioning and compressing the cooled suction gas, the temperature of the discharge gas can also be lowered. A scroll type or screw type refrigeration compressor has an intermediate pressure chamber in the middle of compression in the form of Fy, so that the reduced pressure refrigerant that has cooled the suction gas can be easily injected into the compression chamber in the middle of compression. By providing the injection port for the reduced pressure refrigerant at a position that does not communicate with the suction port, injection can be performed without reducing the flow rate of the suction gas.

The injected reduced pressure refrigerant is compressed and discharged together with the suction gas, @
Condensation in a condenser and circulation [Example] Figures 1 and 2 show examples of the present invention.

In FIG. 1, 1 is a compressor according to the present invention,
In this embodiment, a scroll type is used. This compressor 1
and condenser 2, first pressure reducing device 5, evaporator 8p and condenser 2
A refrigeration cycle is formed from the 'W path which branches off from the middle of the g1 pressure reducing device 5 and interposes a second pressure reducing device 114 which connects to the refrigerant injection pipe 8 of the compressor 2.

The compressor 1 has suction pressure in the casing 6. Refrigerant gas is guided into the casing 6 from the suction 117,
The fc4 motor is fixed to the frame 12, passes through a narrow gas passage 19, is provided near the outer periphery of the fixed scroll type O, and is sucked into the pressure a section from the compression chamber suction port 7. Crank 4 driven by 12
41i 1. i, compressed by the orbiting movement of the orbiting scroll 15 and discharged through the discharge pipework 8 connected to the central part 12 of the fixed scroll 1Of2).

II! The i1M scroll 10 has an injection port 11a that is opened into a space during compression as an injection hole.

11b. The injection port 1 1 a I l 1
1) includes the second $. A suction gas cooler 9 is connected to a refrigerant injection pipe 8 that communicates with the pressure and length. 1
4 is lubricating oil.

Next, the operation will be explained.

The refrigerant gas sucked through the suction pipe 17
It cools the motor 18 by flowing around it. Therefore, the suction gas is heated and expanded. When the same volume of refrigerant gas is sucked and compressed by heating and compressing, the work of compressing the gas remains constant regardless of the degree of heating, but the compression weight flow rate decreases, and the compression weight flow rate relative to the compression work decreases. and the efficiency of the compressor decreases. This is usually called heating loss. Although it is preferable to minimize this heating loss, it cannot be avoided in an OIE compressor having a structure in which tmt* is cooled with suction gas.

The refrigerant gas heated as described above passes through the passage 19 and is guided into the space formed by the fixed scroll IO and the casing 6. 7) An intake gas cooler 9 is provided in the space.
r D % This suction gas cooler 9 re-cools the suction gas before it is sucked into the compressed Mg&population 7.

This intake gas is cooled by condenser 2! The compressed liquid refrigerant is depressurized by the second pressure reducing device Φ, and the latent heat of the depressurized refrigerant and the suction gas heated by the electric motor 18 to a high temperature are exchanged with the suction gas cooler 9. . The refrigerant with which heat was exchanged with the suction gas is supplied to an injection port 11a provided in the fixed scroll.

The refrigerant is injected from 11b during compression, cooled by the above-mentioned y-hole, merges with the refrigerant that is being suctioned and compressed from the compression chamber suction port 7, is discharged from the discharge port f18, is condensed in the condenser 2, and circulates.

As described above, according to the present invention, the suction gas heated by the electric motor 18 can be recooled, and performance can be improved.

Furthermore, when the present invention is applied to a refrigeration cycle for ultra-low temperatures, even greater effects are exhibited. That is, in the case of ultra-low temperature applications, the suction gas pressure is low and the gas is diluted, but a certain amount of compression power is required to compress this diluted gas. Therefore, the more the pump is used at low temperatures, the more the suction gas is heated, and the loss due to increased heating loss becomes extremely large. - For example, if Freon 22 is used as the refrigerant and the evaporation temperature is about -60°C, the reduction in efficiency due to heating loss will reach 20% or more. The present invention not only improves this decrease in efficiency but also exhibits even more significant effects. In other words, it is divided into trial calculations under the same conditions! Motive 13
The amount of heating of the suction gas D is approximately 80°C. Due to such high temperatures, conventional refrigerated buoys without the suction gas cooler 9 cannot be operated due to the abnormal rise in discharge gas temperature and the overheating of the compressor.

However, according to the IIA of the present invention, by recooling the intake gas, it becomes possible to operate even under such extremely low temperature conditions.

Figure ii2 shows another embodiment of the invention. The difference from the embodiment 1 shown in FIG. Intake gas cooler 9
As an alternative, electric I21' @ cooler 20 is used as the second pressure reducing device
The refrigerant injection pipe 8 communicating with the fixed scroll IOK is connected to the injection port 11atllbK provided with the fixed scroll IOK. In this embodiment, the intake gas is not heated by the electric motor 18, so that no deterioration in performance occurs.On the other hand, the electric motor 1B is cooled by the electric motor cooler 20.The principle of the electric motor cooler 20 is as shown in FIG. Since it is the same as the intake gas cooler, the explanation will be omitted.

This embodiment also provides the same effects as in FIG. 1. In the embodiments shown in FIGS. 1 and 2, there are two injection ports, but it is possible to use only one injection port, and the same effect can be obtained even if there are two or more injection ports.

〔Effect of the invention〕

According to the present invention, not only can the heat loss of the suction gas D710 be reduced, but also it is possible to operate under conditions that conventionally could not be performed due to abnormally high suction gas temperature due to heating by the electric motor in the ultra-low temperature VCP. This has the effect of expanding the operating range on the low temperature side compared to conventional methods.

[Brief explanation of drawings]

FIG. 1 shows a profit diagram of a θ refrigeration compressor according to an embodiment of the present invention. FIG. 2 shows a configuration diagram of a refrigeration compressor according to another embodiment. l...Pressure m machine 2...Condenser 8...Evaporator 4...Second pressure reducing device Suction gas cooler 1 1a, 11b...Inlet...Motor cooler. 5...First pressure reducing device 0...Fixed scroll 18...WLtlh machine 9...0 1 (2)

Claims (1)

[Claims] 1. A refrigeration compressor is formed with a compression chamber having a pressure intermediate between suction pressure and discharge pressure, and has an injection port for injecting reduced pressure refrigerant into the compression chamber having an intermediate pressure. In a refrigeration cycle in which a refrigerant circuit is formed by a commercial compressor, a condenser, a first and second pressure reducing device, and an evaporator, the liquid refrigerant condensed in the condenser is depressurized in the second pressure reducing device, and the latent heat of this reduced pressure refrigerant is used to reduce the pressure of the liquid refrigerant. After cooling the suction gas that has been superheated by cooling the electric motor, the depressurized refrigerant is injected from the injection port into the compression chamber at an intermediate pressure, and the suction gas is sucked through the compression chamber suction port and compressed. A refrigeration compressor featuring: 2. A refrigeration compressor having a compression chamber having a pressure intermediate between suction pressure and discharge pressure, and having an inlet for injecting decompressed refrigerant into the compression chamber having an intermediate pressure; a condenser; In a refrigeration cycle consisting of a second pressure reducing device and an evaporator, the suction gas introduced into the refrigeration compressor is suctioned and compressed through the compression chamber suction port, either directly or while preventing heating, and the liquid refrigerant condensed in the condenser is transferred to the second A refrigeration compressor, characterized in that the pressure is reduced by a pressure reducing device, a conductive machine is cooled by the latent heat of the reduced pressure refrigerant, and the reduced pressure refrigerant is injected from the injection port into a compression chamber having an intermediate pressure.