AU634737B2

AU634737B2 - A method for recovering a refrigerant

Info

Publication number: AU634737B2
Application number: AU47266/89A
Authority: AU
Inventors: Keiichi Tomaru
Original assignee: Sanden Corp
Current assignee: Sanden Corp
Priority date: 1988-12-22
Filing date: 1989-12-22
Publication date: 1993-03-04
Anticipated expiration: 2009-12-22
Also published as: DE68904751T2; EP0374964A3; JPH02169973A; DE68904751D1; AU4726689A; EP0374964B1; EP0374964A2

Description

AUSTRALIA

PATENTS ACT 1952 COMPLETE SPECIFICATION 634757 Form

(ORIGINAL)

FOR OFFICE USE Short Title: Int. Cl: Application Number: Lodged: Complete Specification-Lodged: Accepted: Lapsed: Published: Priority: Related Art: 000 Name of Applicant: Address of Applicant: 00 0*00 E COMPLETED BY APPLICANT SANDEN CORPORATION 20 KOTOBUKI-CHO

ISESAKI-SHI

GUNMA-KEN

JAPAN

Actual Inventor: Address for Service: *r.

00 0 00 GRIFFITH HACK CO., 601 St. Kilda Road, Melbourne, Victoria 3004, Australia.

Complete Specification for the invention entitled: A METHOD FOR RECOVERING A REFRIGERANT The following statement is a full description of this invention 'including the best method of performing it known to me:- 0 *0 0 0* *9 a9 A METHOD FOR RECOVERING A REFRIGERANT Background of the Invention This invention relates to a method for recovering a refrigerant.

A refrigerant, such as a fluorocarbon refrig-rant, is commonly employed in an air conditioner of an automobile or a refrigerator.

A refrigeration system will operate most efficiently when the refrigerant is relatively free of pollutants, such as, oil, air and water. However, in use, the refrigerant progressively becomes contaminated with pollutants.

S 15 Therefore, it is advisable periodically to remove the refrigerant from the refrigeration system and recharge the refrigerant in a recovery unit.

S.Various refrigerant processing and charging systems are known. For example, US patent 4,768.347 20 discloses a refrigerant recovery unit which comprises a liquefying unit which sucks refrigerant from an external o• freezing circuit or refrigeration circuit which is employed in, for example, an air conditioning system. The US patent also discloses a pressure switch controlling a solenoid valve positioned between the external freezing circuit and a suction conduit of the refrigerant recovery unit.

When the refrigerant is sucked from the external freezing circuit, the amount of the refrigerant in the external freezing circuit gradually decreases.

As a consequence of decreases the amount of the refrigerant, the inner temperature of the external freezing circuit gradually decreases by evaporation of the remaining refrigerant in the external circuit.

As a result, the inner pressure of the external I i\

C

freezing circuit becomes negative in comparison with atmospheric pressure. The negative pressure causes the external freezing circuit to be invaded by the atmosphere.

Summary of the Invention It is an object of the present invention to provide a method for recovering a refrigerant from an external freezing circuit without invasion of the atmosphere into the external freezing circuit.

It is another object of this invention to provide a method of the type described which can prevent the decrease of inner pressure of the external freezing circuit while charging the refrigerant.

Other objects of this invention will become clear as the description proceeds.

In accordance with this invention, there is provided a method for recovering a refrigerant from a refrigeration circuit under pressure, wherein the following steps are repeatedly carried out: 20 a) measuring the pressure in the refrigeration circuit; b) sucking the refrigerant from the refrigeration circuit to a refrigerant recovery unit when the pressure in the refrigeration circuit is equal to or greater than the 25 atmospheric pressure and recovering the refrigerant in the refrigerant recovery unit; c) stopping the suction operation by closing a valve in a suction conduit in the refrigerant recovery unit when the pressure in the refrigeration circuit is less than the atmospheric pressure to avoid the invasion of air into the refrigeration conduit.

Brief Description of the Drawing Fig. 1 is a block diagram of a refrigerant 4 -v recovery unit according to an embodiment of this invention.

Description of the Preferred Embodiment The refrigerant recovery unit shown in the figure is adapted to be connected to an air conditioning system of an automobile which uses a fluorocarbon refrigerant as an original refrigerant in a freezing circuit (not shown) Referring to Fig. 1, the refrigerant recovery unit comprises an inlet electromagnetic valve 10 on a conducting pipe 12 which is coupled to the external freezing circuit. The original refrigerant flows as a liquid phase and a gaseous phase through the conducting pipe 12.

For controlling inner pressure of the external 15 freezing circuit, a pressure sensor 11 is connected to the external freezing circuit. The pressure sensor 11 is for judging whether or not the inner pressure is negative in comparison with atmospheric pressure and to produce an internal signal when the inner pressure is negative. The 20 internal signal is sent to the electromagnetic valve through a wire lla. Responsive to the internal signal, the electromagnetic valve 10 is automatically driven to inhibit passage of the original refrigerant in the conducting pipe 12.

25 When the inlet electromagnetic valve 10 is opened for introducing the original refrigerant from the freezing circuit, the original refrigerant is sucked to a first filter drying 13 by virtue of a compressor 18 which will later be described. The inlet electromagnetic valve 11 can be disconnected from the freezing circuit. The first filter dryer 13 is for removing impurities, moisture, and acid content from the original refrigerant in a manner known in the art.

An accumulator 14 is connected to the first 4A filter dryer 13 for accumulating the original refrigerant.

The liquid phase flow is accumulated in a bottom part of the accumulator 14, and the gaseous phase flow thereon is supplied to a first oil interceptor 15. The first oil interceptor 15 is to intercept an oil element of the- "o oeoo *o •o* ••o eeo *el *o original refrigerant. The intercepted oil element is accumulated in an oil tank 17 through an oil valve 16.

The original refrigerant is supplied to the compressor 18 from the first oil interceptor 15. At this time, the original refrigerant is in a gaseous phase.

The gaseous original refrigerant is compressed in the compressor 18 and is supplied as a compressed refrigerant to a condenser 20 through a second oil interceptor 19. The intercepted oil element is accumulated in another oil tank (not shown). In the condenser 20, the compressed refrigerant is cooled to thereby be condensed as a condensed refrigerant. The condensed refrigerant is supplied to a second filter dryer 21 which is for removing impurities, moisture, and acid content from the condensed refrigerant.

After that, the condensed refrigerant is supplied to a separation vessel 22 and is separated into a gaseous phase refrigerant component and a liquid phase refrigerant component in the separation vessel 22.

The separation vessel 22 comprises an upper part and a bottom part defining an upper space and a bottom space, respectively. The upper and bottom spaces are contiguous with each other to form a hollow space in the separation vessel 22. As well known in the art, the gaseous phase 25 refrigerant component has superior purity in comparison with the liquid phase refrigerant component.

The combination of the compressor 18, the second oil interceptor 19, the condenser 20, the second filter dryer 21, and the separation vessel 22 is referred to as "a 30 separating arrangement". A pipe 12 is provided for effecting the connection between the inlet electromagnetic valve 11 and the separation vessel 22.

The separation vessel 22 has a first outlet port 22a at an upper portion thereof and a second outlet port 22b at a bottom portion thereof. The first outlet port 22a is connected to a liquefication vessel 24a through a first supplying pipe 12a to communicate with a thermal space which is defined by the liquefication vessel 24a.

Therefore, the gaseous phase refrigerant component is sent as an object refrigerant from the separation vessel 22 to the liquefication vessel 24b. On the other hand, the second outlet port 22b is connected to an evaporator 24b through an automatic expansion valve 23 and a second supplying pipe 12b. Therefore, the liquid phase refrigerant component is sent as a liquid refrigerant from the separation vessel 22 to the evaporator 24b and is evaporated in the evaporator 24b to carry out cooling of a surrounding area of the evaporator 24b in a maimer known in the art.

The evaporator 24b is thermally coupled to the thermal space of the liquefication vessel 24a. In this embodiment, the evaporator 24b is contained in the liquefication vessel 24a. As a result, the gaseous phase refrigerant component is cooled in the liquefication vessel 24a by evaporation of the liquid refrigerant, namely, the liquid phase refrigerant component in the evaporator 24b. In other words, heat exchange is carried out between the gaseous and liquid phase refrigerant components. Therefore, the 25 evaporator 24b may be referred to as a liquefying arrangement.

After being evaporated in the evaporator 24b, the gaseous refrigerant is returned to the compressor 18 through a returning pipe 12c.

30 A temperature detecting unit 25 is thermally coupled to the returning pipe 12c. The temperature detecting unit is for detecting temperature of the liquid refrigerant at vicinity of the liquefication vessel 24a, to produce a temperature signal which is representative of the temperature. Responsive to the temperature signal, the automatic expansion valve 23 is automatically driven to adjust the flow rate of the liquid phase refrigerant component.

The liquefied object refrigerant is collected at a lower portion of the thermal space of the liquefication vessel 24a. A storage container 26 is placed under the liquefication vessel 24a and is connected to the thermal space by a sending pipe 27. Therefore, the liquefied object refrigerant drips from the liquefication vessel 24a towards the storage container 26 through the sending pipe 27 by gravitational force. As a result, the liquefied object refrigerant is charged in the storage container 26.

It is a matter of course that the modified refrigerant has a relatively higher purity in the storage container 26.

When the thermal space is not enough of quantity of the liquefied object refrigerant, the liquefied object refrigerant is prevented from charging towards the storage container 26.

20 For controlling quantity of liquid in the thermal space, a liquid level sensor 28 is connected to the liquefication vessel 24a. The liquid level sensor 28 is S. for detecting a predetermined liquid level to produce a condition signal. The condition signal is sent to an electromagnetic valve 29. The electromagnetic valve 29 is coupled to the sending pipe 27. Responsive to the condition signal, the electromagnetic valve 29 is automatically driven to adjust the movement of the liquefied object refrigerant through the sending pipe 27.

A combination of the sending pipe 27, the liquid level sensor 28, and the electromagnetic valve 29 is referred to as a control arrangement. It is preferable that the condition signal responsive to the predetermined liquid level be produced until the evaporator 24b is made 8 thoroughly wet by the liquefied object refrigerant in the liquefication vessel 24b to enhance the effectiveness of the heat exchange. When the detected liquid level is lower than the predetermined liquid level, the electromagnetic valve 29 is driven in response to the condition signal to stop the dripping of the liquefied object refrigerant to the storage container 26.

When the detected liquid level is higher than the predetermined level, the electromagnetic valve 29 is driven in response to the condition signal to open the sending pipe 27 so that the liquefied object refrigerant flows into the storage container 26. Preferably, a breathing pipe is disposed between the liquefication vessel 24a and the storage container 26 for venting residual gas of the refrigerant in the storage container 26 because of smooth flow of the liquefied object refrigerant. Therefore, the effectiveness of the heat exchange is increased in the liquefying arrangement.

The object refrigerant can be smoothly charged into the storage container 26 by repeating the operation described above.

'in connection with the above embodim be possible for tho -in the art to readily put this tie n I

Claims

2. A method for recovering a refrigerant from a e refrigeration circuit under pressure substantially as hereinbefore described with reference to the accompanying drawing. DATED THIS 16TH DAY OF DECEMBER 1992 SANDEN CORPORATION By Their Patent Attorneys GRIFFITH HACK CO. Fellows Institute of Patent Attorneys of Australia.