GB2121942A

GB2121942A - Compression-condensation refrigeration system

Info

Publication number: GB2121942A
Application number: GB08310730A
Authority: GB
Inventors: Akira Kawamoto
Original assignee: Tokyo Shibaura Electric Co Ltd
Current assignee: Toshiba Corp
Priority date: 1982-04-22
Filing date: 1983-04-20
Publication date: 1984-01-04
Also published as: GB8310730D0; IT1161169B; JPS58162458U; DE3314140A1; IT8320758A0

Abstract

The system includes a check valve (26) provided between the suction side (21a) of a compressor (21) and an evaporator (25) for preventing a fluid from flowing from the suction side to the evaporator. A valve device (27) is provided between a condenser (22) and the evaporator (25) for preventing the fluid from flowing from the condenser (22) to the evaporator (25) during the stoppage of the compressor (21). A connection pipe (34) is connected between the valve device (27) and the suction side (21a) of the compressor (21) for transmitting the suction side pressure to the valve device. The valve device (27) is a pressure responsive type for closing upon sensing the suction side pressure of the compressor (21) becoming higher than a predetermined value upon stoppage of the compressor for preventing the fluid from flowing. <IMAGE>

Description

SPECIFICATION Refrigeration cycle The present invention relates to a refrigeration cycle which performs cooling of a chamber such as an interior of a refrigerator while controlling a temperature by driving or stopping a compressor.

A refrigeration cycle of this type is in general composed of a compressor, a condensor, a capillary tube or an expansion valve and an evaporator, which are sequentially connected. In this structure, when a chamber is cooled to a predetermined temperature, and thus the operation of the compressor is stopped, hot gas at the condenser side thereafter flows gradually to the evaporator. Accordingly, a temperature sensor provided in the vicinity of the evaporator operates before the temperature in the chamber has risen to a predetermined temperature, thus resulting in the renewed operation of the compressor. In this manner, this refrigeration cycle has the disadvantage that temperature control in the chamber is not performed in the desired state and power consumption is increased.

In order to solve the above problems, a refrigeration cycle is known in which a solenoid valve 12 is provided between a condensor 10 and a capillary tube 11, as shown in Fig. 1. In this refrigeration cycle, the valve 12 is energized simultaneously with the stopping of a compressor (rotary compressor) 13, thereby preventing hot gas from flowing from the condenser 10 to the evaporator 14. However, in this structure, the valve 12 remains energized during the stoppage of the refrigeration system, and hence, during the stoppage of the compressor. Thus, the problem of the wasteful use of electric power cannot be sufficiently overcome.

In Fig. 1, reference numeral 1 5 designates a check valve, which is provided between the compressor 1 3 and the evaporator 14 for preventing the hot gas at the condenser side from flowing through the compressor to the evaporator when the refrigeration system is stopped.

It is an object of the present invention to provide a refrigeration cycle which is capable of accurately performing temperature control with less power consumption.

This invention can be more fully understood from the following detailed description when taken in conjunction with the accompanying drawings, in which: Fig. 1 is a view showing a conventional refrigeration cycle; Fig. 2 is a view showing a refrigeration cycle according to an embodiment of the present invention; Fig. 3 is a sectional view showing a valve device used in the refrigeration cycle in Fig. 2; and Fig. 4 is a view showing a refrigeration cycle according to another embodiment of the present invention.

A refrigeration cycle according to an embodiment of the present invention will now be described in more detail with reference to the accompanying drawings.

In Fig. 2, reference numeral 21 designates a rotary compressor. The input side of an evaporator 25 is sequentially connected through a condenser 22, a main capillary tube 23 and an auxiliary capilliary tube 24 to the output side or an exhaust port of the compressor 21. The input side or a suction port 21 a of the compressor 21 is connected to the output side of the evaporator 25 through a check valve 26. This valve 26 prevents hot gas from flowing from the condenser through the compressor to the evaporator in the same manner as in the prior art. A valve device 27 of the pressure-responsive type is provided between the capillary tubes 23 and 24.

As shown in detail in Fig. 3, the valve device 27 has a valve case 28 which has a cylindrical case body 28a opened at the upper end and a cover 28b provided to close the opening of the body 28a. An inlet 29 and an outlet 30 are respectively formed at the peripheral wall and the lower wall of the body 28a so as to communicate with the interior of the valve case. A connection port 32 is formed at the cover 28b so as to communicate with the interior of the case. A hollow bellows 31 which is vertically stretchable is provided in the case 28. The bellows 31 is opened at the upper end and is closed at the lower end in such a manner that the upper edge is mounted on the inner surface of the cover 28b and the interior communicates with the port 32. Consequently, the bellows 31 is hermetically sealed with the interior of the case 28 to depend from the cover 28b.A valve body 33 is projected from the lower or free end of the bellows 31 to face the outlet 30.

When the internal pressure of the bellows 31 is equal to that of the case 28, the bellows extends by its own weight into the lowermost position (at the position designated by a solid line in Fig. 3), thereby causing the valve body 33 to close the outlet 30. When the internal pressure of the bellows 31 becomes lower by a predetermined value than that of the case 28, the bellows 31 retracts to the upper position (at the position designated by a two-dotted chain line in Fig. 3) due to the pressure difference, and the valve body 33 closes the outlet 30.

In the valve device 27, the outlet 30 is connected to the inlet side of the capillary tube 24, and the inlet 29 is connected to the outlet of the capillary tube 23. The port 32 is connected to one end of a pipe 34. The other end of the pipe 34 is connected to the suction side of the compressor 21, and hence, to a suction pipe 35 for connecting the suction portion 21 a to the check valve 26.

In Fig. 2, reference numeral 36 designates a conventional temperature sensor which is provided in the vicinity of the evaporator in the chamber to be cooled to sense the temperature in the chamber so as to start the operation of the compressor 21 when the temperature becomes higher that a set value and to stop it when the temperature becomes lower than a set value.

The operation of the refrigeration cycle thus constructed will now be described.

Before the operation of the compressor 21 starts, the outlet 30 of the valve device 27 is closed by the valve body 33, as shown by a solid line in Fig. 3. When the temperature of the chamber becomes higher than a predetermined temperature and the compressor 21 is started by the output from the sensor 36, the pressure in the pipe 35 decreases, and the pressure at the condenser 22 side increases. Thus, the pressure in the bellows 31 decreases and the pressure in the valve case 28 increases. When the pressure difference between the internal pressure of the bellows and the internal pressure of the valve case 28 becomes higher than a predetermined value, the bellows 31 shrinks, with the result that the valve body 33 becomes isolated from the outlet 30, as shown by the two-dotted chain line in Fig.

3, thereby opening the outlet 30. On the other hand, a refrigerant which is compressed by the compressor 21 and is then liquefied by the condenser 22 is flowed sequentially through the capillary tube 23, the case 28 and the capillary tube 24 to the evaporator 25, in which the refrigerant is evaporated and is again sucked into the compressor 21. During the operation of this refrigeration cycle, the difference between the internal pressure of the bellows 31 and the interal pressure of the case 28 becomes substantially equal to the pressure loss due to the capillary tube 24, and the valve device 27 remains open due to this pressure difference. When the chamber is cooled to a predetermined temperature and the operation of the compressor 21 is stopped via the temperature sensor, the gas refrigerant of high pressure at the condenser 22 side is fed through the compressor 21 into the pipe 35.As a result, the internal pressure in the pipe 35 will abruptly rise, and the internal pressure in the bellows 31 will accordingly rise to become substantially equal to the internal pressure of'the condenser 22. On the other hand, the gas refrigerant which flows from the condenser 22 side to the pipe 35 is prevented from flowing into the evaporator 25 via the valve 26. Due to the pressure loss at the capillary tube 23 the internal pressure of the case 28 becomes lower than the internal pressure of the condenser 22, and at the same time, when the compressor 21 is stopped, the internal pressure of the bellows 31 accordingly becomes lower, by the value corresponding to the pressure loss at the capillary tube 23, than the internal pressure of the case 28. Consequently, the bellows 31 extends to close the outlet 30 via the valve body 33.

Subsequently, the high temperature, high pressure refrigerant in the condenser 22 gradually flows into the case 28 through the capillary tube 23.

Accordingly, the difference between the internal pressure of the bellows 31 and the internal pressure of the case 28 gradually decreases and finally equalizes. At this time, the bellows 31 is disposed at the lowermost position, and the outlet 30 remains closed by the valve body 33.

In the refrigeration cycle of the above construction, when the operation of the compressor 21 is stopped, the valve device 27 is closed, thereby preventing the hot gas in the condenser 22 from flowing through the main and auxiliary capillary tubes 23 and 24 into the evaporator 25 and preventing the hot gas in the condenser 22 from flowing from the compressor 21 side to the evaporator 25 by the operation of the check valve 26. Accordingly, the evaporator 25 is not heated by the hot gas during the stoppage of the operation, thereby allowing it to accurately control the reoperation of the refrigeration cycle. Consequently, the compressor is efficiently operated, thereby saving power consumption.In addition, since the valve device does not require continuous electric power, as does the conventional solenoid valve, but is driven only in response to pressure changes in the refrigeration cycle, electric power consumption can be further decreased.

In the embodiment described above, a pressure reducing device is composed of the main and auxiliary capillary tubes. However, as shown in Fig.

4, the pressure reducing device may be formed of a single capillary tube 36, and the valve device 27 may be provided between the tube and the condenser 22. The valve device 27 may also be provided between the pressure reducing device and the evaporator. In this case, the suction side pressure of the compressor decreases (as an ordinary operation), and it is necessary to set the valve device so as to open when it becomes lower than the condenser side pressure of the valve device so as to increase the suction side pressure upon stoppage of the compressor, and to close when it becomes substantially equal to the condenser side pressure. The term "substantially equal pressure" here indicates the case where the suction side pressure increases, so that the pressure difference decreases, though the suction side pressure is lower than the condenser side pressure, and the case where the suction side pressure becomes higher than the condenser side pressure.

In the embodiments described above, the pressure reducing device employs a capillary tube.

However, other implements such as an expansion valve may also be employed. The compressor is not limited only to the rotary type, and other types, such as a reciprocating type, may also be employed.

Claims

1. In a refrigeration cycle comprising a compressor, a condenser connected to the exhaust side of said compressor, an evaporator connected to the suction side of said compressor, a pressure reducing device connected between said evaporator and said condenser, a check valve provided between the suction side of said compressor and said evaporator for preventing a fluid from flowing from the suction side to the evaporator, and a valve device provided between said condenser and said evaporator for preventing the fluid from flowing from said condenser to said evaporator during the stoppage of said compressor, the improvement being that said valve device comprises a pressure responsive type valve means closing upon sensing the suction side pressure of said compressor becoming higher than a predetermined value upon stoppage of said compressor for preventing the fluid from flowing.

2. The refrigeration cycle according to claim 1, further comprising a connection pipe connected between said valve device and the suction side of said compressor for transmitting the suction side pressure to said valve device.

3. The refrigeration cycle according to claim 2, wherein said valve device comprises a valve housing having an inlet connected to said condenser side, an outlet connected to said evaporator side and a connection port connected to said connection pipe, a valve body provided in said housing, and a drive mechanism for sensing the suction side pressure of said compressor and the condenser side pressure and opening and closing said valve body to the outlet according to the pressure difference therebetween.

4. The refrigeration cycle according to claim 3, wherein said connection port and said outlet are formed in said valve housing to face each other, said drive mechanism has a bellows which is provided in said housing to communicate with said connection port, to be hermetically sealed from said housing, and to be retracted due to the pressure difference when the internal pressure becomes lower by a predetermined value than the pressure in said housing, thereby isolating said valve body from said putlet.

5. The refrigeration cycle according to claim 1, wherein said pressure reducing device comprises a capillary tube provided between said condenser and said valve device, said valve device opens when the suction pressure of said compressor becomes substantially equal to the pressure of the capillary tube side of said valve device and closes when the former becomes higher than the latter.

6. The refrigeration cycle according to claim 5, wherein said pressure reducing device comprises another capillary tube connected between said valve device and said evaporator.

7. The refrigeration cycle according to claim 1, wherein said pressure reducing device comprises a capillary tube connected between said valve device and said evaporator, and said valve device opens when the suction side pressure of said compressor is lower than the condenser side pressure of said valve device and closes when the former becomes substantially equal to the latter.

8. A refrigeration cycle, substantially as hereinbefore described with reference to the accompanying drawings.