HK1192307B - Method and apparatus for recovering the refrigerant from an air conditioning system - Google Patents

Description

Method and apparatus for recovering refrigerant from air conditioning system

Technical Field

The present invention relates to a method for recovering refrigerant from an air conditioning system (e.g., an a/C system of an automobile).

Furthermore, the invention relates to a device for recovering, purifying and refilling refrigerant into the air conditioning system.

Background

It is known that the refrigerant present in air conditioning systems, in particular in a/C systems on vehicles such as automobiles, is periodically recovered and circulated in order to eliminate impurities that accumulate during operation. One type of recovery and regeneration machine is disclosed in EP1367343a 1.

Furthermore, in order to counteract the greenhouse effect due to the dispersion of the refrigerant gases used in air conditioning systems, laws and regulations impose increasingly strict limits on the exhaust gas recovery process, such as the refrigerant R-134a currently known in most automotive air conditioning systems. In particular, currently known regulations require that at least 95.0% of the total gas contained in the air conditioning system be recovered.

With the introduction of new automobiles, for example, according to 2006/40/CE regulations for refrigerants called HFO-1234yf, which has a lower effect on global warming than HFC-134a but is higher in cost, the step of recovering gas becomes important in terms of environmental and economic aspects.

Another disadvantage related to the safety of the recovery and regeneration steps is related to the fact that the refrigerant HFO-1234yf is flammable. In fact, the recovery of the residual part of refrigerant present in the system requires too much time, which is normally discharged to the environment when the vacuum pump of the refrigerant recovery machine is operating. The vacuum step is a necessary step to be done before refilling with gas. The discharge of small amounts of refrigerant to be mixed with the oxygen present in the air can create a gaseous mixture that can explode or catch fire with the attendant risk to objects and personnel.

The operation of recovering, regenerating and refilling refrigerant effected by the machine described in EP1367343a1 must comply with certain standards, such as SAE J2843 and SAE J2788, which exceed a defined minimum threshold for recovering refrigerant (for example, 95%), as well as defining safety conditions and time limits for carrying out these steps. In particular, in the external temperature range between 21 ° and 24 ℃, at least 95.0% of the refrigerant must be recovered within a maximum time of 30 minutes without heating the components of the system.

The above criteria cannot be easily fulfilled by existing recycling machines. A particularly disadvantageous situation in which these criteria are not met occurs when the temperature around the air conditioning system is very low, at which it is difficult to recover even 90% of the refrigerant. In fact, at such low external temperatures, the refrigerant present in the system is mainly in liquid form and difficult to recover.

There is a circuit/loop equipped with a heating system to assist in recycling. However, these circuits make the air conditioning system less secure and more expensive. The operation of heating the system is also dangerous and complex because the reservoir of refrigerant for an automotive a/C system is typically located in an area that is not readily accessible, behind the motor.

Referring to fig. 1, a schematic diagram of an automotive a/C system 200 of known type comprises a condenser 201, a filter 202, calibrated orifices 203, an evaporator 204, a storage vessel 205 separating refrigerant in liquid and gaseous phases, and a compressor 206. Downstream of the compressor, a high pressure connection 221 is provided, while a low pressure connection 222 is provided on the storage vessel.

At present, a machine 230 (fig. 1) of a known type for recovering and regenerating refrigerant, similar to the one described in EP1367343a1, can recover refrigerant from a hermetic compressor 233, which hermetic compressor 233 is connected to the air conditioning system by flexible pipes reaching an accumulator 235 and a high pressure connection 221 and a low pressure connection 222. Due to the operation of the compressor 233, the refrigerant is drawn to a pressure lower than the atmospheric pressure and accumulated after a process for regeneration in the storage cylinder 234.

More precisely, when the system 200 is shut down, the liquid portion of the refrigerant tends to be diverted by the pressure differential from the high pressure region 221 toward the storage vessel 205, through the calibrated orifice 203 and the compressor 206. The refrigerant is recovered mainly in the liquid phase from the high-pressure connection 221 and in the gas phase from the low-pressure connection 222. However, under low temperature ambient conditions, a substantial liquid portion of the refrigerant is in the storage container 205, and the step of recovering the refrigerant from evaporation may be performed only by significantly reducing the suction negative pressure of the machine by the compressor unit 233. However, in order to achieve these conditions, a substantial increase in the time for recovering and disposing of the refrigerant is necessary. Until at least 95% is recovered, the time for recovery may exceed 30 minutes in order to meet the regulations.

The refrigerant recovery and regeneration steps require the vacuum pump 231 to reach the maximum vacuum level possible, discharge refrigerant that was not recoverable by the previous recovery step in the environment, and assist in the subsequent refilling of the regenerated refrigerant, wherein the vacuum pump 231 is completely separated from the compressor unit 233 and performs the vacuum step. It must be noted that the less refrigerant remaining after the recovery step, the more refrigerant is discharged into the atmosphere, with the above-described drawbacks of pollution, fire hazard and costly refrigerant waste.

Therefore, it is desirable to speed up the time for venting the air conditioning system and increasing the amount of recovered refrigerant.

An expensive solution would be to use a high power compressor for producing maximum suction of refrigerant in a short time. However, this solution would excessively increase the machine costs not only due to the higher cost of the compressor, but also due to the overall larger size of the suction system which withstands the more powerful action of the compressor. Furthermore, such a solution does not completely solve the above-mentioned problems and would complicate the regeneration process.

Disclosure of Invention

It is, therefore, a feature of the present invention to provide an apparatus for recovering refrigerant from an air conditioning system, such as an a/C system of an automobile, in such a manner that a minimum amount of refrigerant remains in a storage container of the air conditioning system and is recovered as quickly as possible.

It is another feature of the present invention to provide a device for increasing the velocity of fluid passing through the same device and reducing the time necessary to regenerate the fluid.

A particular object of the present invention is to provide a device which makes it possible to obtain the above-mentioned advantages without incurring excessive additional implementation costs.

It is another feature of the present invention to modify existing recovery or regeneration devices without introducing significant constructional complexity.

It is a further feature of the present invention to provide a method that achieves the same advantages.

These and other objects are achieved by an apparatus for recovering refrigerant from an air conditioning system, comprising:

-a collector arranged to hydraulically connect the high pressure branch and the low pressure branch of the air conditioning system through fluid transfer conduits in the device;

-an evaporator arranged to separate refrigerant and impurities by evaporation of a residual liquid fraction of the refrigerant, obtaining a purified refrigerant increasing towards an upper part of the evaporator and impurities concentrated in a lower part of the evaporator;

-a suction unit for circulating the purified refrigerant coming out of the evaporator, the suction unit being hydraulically connected to the delivery duct through the evaporator, the suction unit comprising a compressor;

-a condenser hydraulically connected to the suction unit for circulating the refrigerant, the condenser being arranged to cool and condense the refrigerant coming out of the suction unit;

-a storage vessel hydraulically connected to the condenser, the storage vessel being arranged to contain refrigerant condensed by the condenser;

wherein upstream of the evaporator, an auxiliary compressor element is provided, arranged in parallel with the delivery conduit, the auxiliary compressor element being configured to increase the flow rate of the refrigerant towards the evaporator and for assisting a progressive pressure reduction of the refrigerant in the air conditioning system in cooperation with the suction unit.

In this way, the auxiliary compressor element causes the air conditioning system to quickly reach a low pressure that allows for almost complete recovery of the refrigerant. More precisely, a suction unit is generally provided for circulating the purified refrigerant and is essentially a compressor arranged downstream of the evaporator, which suction unit performs the suction function of the cooling liquid coming from the air conditioning system through the evaporator and the delivery duct from the accumulator. The presence of an auxiliary compressor upstream of the evaporator pressurizes the compressor of the suction unit, speeds up the evacuation step of the system, recovers as much refrigerant as possible, and reaches the maximum vacuum rate in the system at the end of the recovery step. Thus, the recovery time can be significantly reduced by about 30% relative to prior art recovery systems.

Advantageously, the delivery duct comprises a first portion downstream of the accumulator, and a second portion contiguous to the first portion and arranged upstream of the evaporator, and the auxiliary compressor member is arranged in parallel with the second portion, in which second portion a feed valve is arranged, which is movable between an open position and a closed position in such a way that, when the pressure in the first portion is higher than a threshold value, the auxiliary compressor is not operated and the feed valve is in the open position, and, when the pressure in the first portion is lower than the threshold value, the auxiliary compressor member is open and the feed valve is in the closed position, causing the refrigerant to be delivered to the evaporator by the auxiliary compressor member, which in cooperation with the suction unit contributes to further reducing the pressure on the first portion of the delivery duct.

In this way, the first recovery step, i.e. when the pressure in the system is still sufficiently high, for example 200mb, can be carried out in a conventional manner only by the compressor of the suction unit. Conversely, for lower pressures, the intake valve is closed and the auxiliary compressor component is activated and helps quickly reach a minimum pressure value in the system.

In one possible embodiment, the auxiliary compressor member comprises a vacuum producing device. Thus, once a significant portion of the refrigerant recovery step is complete, e.g., more than 95%/96% of the recovered refrigerant, recovery may continue, increasing the vacuum rate in the system.

Advantageously, the vacuum generating device is hydraulically connected to the evaporator by means of a three-way valve arranged to selectively connect the vacuum generating device to the evaporator or to an extraction line (purge duct), in such a way as to allow the vacuum generating device to alternatively work as an auxiliary compressor member, or to extract a refrigerant that cannot be regenerated but still remains in the air conditioning system. In this way, it is possible to stop recovering refrigerant that exceeds the above-mentioned significant threshold or upper threshold and to extract the residual part, while at the same time the evaporator, the compressor of the suction unit and the condenser are completing the regeneration of the refrigerant.

Alternatively, the auxiliary compressor means for reducing the pressure of the refrigerant on the first portion of the conveying piping comprises a dry-operated compressor, and wherein a vacuum generating device is arranged upstream of the dry-operated compressor to extract refrigerant that cannot be regenerated from the device for recovering refrigerant.

In this way, it is possible to use dry-operated compressors of minimum consumption and cost, in addition to the vacuum pumps normally present in recovery and regeneration machines of known type. A dry-running compressor does not require lubrication because it utilizes lubricant already present in the refrigerant that is drawn from the air conditioning system.

According to another aspect of the present invention, a method of recovering and regenerating refrigerant from an air conditioning system includes the steps of:

-delivering refrigerant through an accumulator in the refrigerant regeneration device, the accumulator being arranged to hydraulically connect a fluid delivery conduit of the device with the high pressure branch and the low pressure branch of the air conditioning system;

-evaporating the residual liquid portion of the refrigerant by means of an evaporator arranged to separate the refrigerant and impurities, obtaining a purified refrigerant concentrated in an upper part of the evaporator and impurities concentrated in a lower part of the evaporator;

-causing suction by a suction unit hydraulically connected with the delivery conduit through an evaporator and circulating refrigerant through the device;

-condensing refrigerant coming out of the suction unit by means of a condenser hydraulically connected to the suction unit for circulating refrigerant;

-accumulating the refrigerant condensed by the condenser in a container hydraulically connected to the condenser;

it is mainly characterized in that the steps of sucking and circulating the refrigerant through the device are performed by a suction unit and an auxiliary compressor member which operates upstream of the evaporator and increases the flow rate of the refrigerant towards the evaporator for assisting the pressure reduction of the refrigerant in the air conditioning system.

Drawings

Further features and/or advantages of the method and device for recovering and regenerating refrigerant in an air conditioning system according to the present invention will become clearer from the following description of an exemplary embodiment thereof, given by way of example and not limitation with reference to the accompanying drawings, in which:

figure 1 shows an arrangement according to the prior art for recovering and regenerating refrigerant connected to an air conditioning system;

FIG. 2 shows the circuit of the apparatus for recovery and regeneration according to the prior art of FIG. 1;

FIG. 3 shows a schematic view of a first exemplary embodiment of an apparatus for recovery and regeneration according to the present invention;

figure 4 shows a schematic hydraulic view of a first preferred exemplary embodiment of the device for recovery and regeneration according to the present invention;

FIG. 5 shows a schematic view of a second exemplary embodiment of an apparatus for recovery and regeneration according to the present invention;

FIG. 6 shows a schematic hydraulic view of a second preferred exemplary embodiment of the device for recovery and regeneration according to the invention;

FIG. 7 shows a schematic view of a third exemplary embodiment of an apparatus for recovery and regeneration according to the present invention;

FIG. 8 shows a schematic hydraulic diagram of a third preferred exemplary embodiment of the device for recovery and regeneration according to the invention;

Detailed Description

With reference to fig. 3, with respect to the prior art system of fig. 1 and 2, the means 230 for recovering and regenerating the refrigerant coming from the accumulator 235 comprise a vacuum pump 231 or, alternatively, a dry-operating compressor, located upstream of the evaporator 232 and in parallel with the delivery duct 101, in such a way that, in a predetermined operating configuration, the refrigerant can cover the path through the vacuum pump 231, the evaporator 232 and the suction unit 233 in succession.

The vacuum pump 231 may be removed from the regeneration circuit or included in the circuit through valves 241a and 241 b. This particular solution allows the vacuum pump 231 to operate in the pumping step only when the pumping unit 233 falls below a threshold pressure, obtaining a further reduction of the pressure in the conveying duct 101 and therefore in the device arranged between the collector 235 and the pumping unit 233.

Thus, unlike the prior art, such as described in fig. 1 and 2, the vacuum pump 231 of the system 230 according to the present invention, or alternatively, a dry-operated compressor, assists in the evaporation of refrigerant, thereby increasing the rate of refrigerant recovery and maximizing the amount of refrigerant recovered, as described above.

Referring in more detail to fig. 4, the conveying duct comprises a first portion 101a downstream of the collector, and a second portion 101b continuous with the first portion 101a and arranged upstream of the evaporator 232. In this way, the auxiliary compressor element is arranged in parallel with the second portion 101b, wherein the inlet valve 241a is present in the second portion 101 b. Such a valve is movable between an open position and a closed position, and when the pressure in said first portion 101a remains above a threshold value, the auxiliary compressor 231 (i.e. the vacuum pump or the dry-operated compressor) is not operated and the feed valve 241a is in an open position. Conversely, when the pressure in the first portion 101b is lower than the threshold value, the auxiliary compressor 231 is open and the feed valve is in the closed position, so that refrigerant is delivered to the evaporator by the auxiliary compressor 231, the auxiliary compressor 231 is operated so as to further reduce the pressure on the first portion 101a of the delivery pipe 101 in cooperation with the suction unit 233 in the recovery when the suction unit 233 "finds it difficult" to complete the recovery action. In fig. 3 and 4, a relief valve 241b is also shown, arranged to avoid losses and leakage through the auxiliary compressor 231 when the feed valve 241a is open.

In fig. 4, the components of the recovery and regeneration circuit are further shown, which are already known in existing machines, such as those already described in EP1367343a1, for example condensers, oil separators, collection reservoirs (collection reservoirs) for the residue collected by the evaporator 232, etc.

Referring to fig. 5 and 6, in an exemplary embodiment of the present invention, the vacuum pump 231 may be hydraulically connected to the evaporator 242 through the three-way valve 241c, in addition to the vacuum pump 231 being arranged to be excluded or included through the valves 241a and 241b as already described with reference to fig. 3 and 4. This particular solution allows the dual function of the vacuum pump 231:

when the valve 241b is also open and the valve 241a is closed, to the first hydraulic connection position of the vacuum pump 231 with the evaporator 232, i.e. for reducing the pressure in the conveying pipe 101 and thus in the apparatus arranged between the collector 235 and the suction unit 233 as described above,

when it is not advisable to continue recovering the refrigerant, it is moved to a second hydraulic connection position with the environment of the vacuum pump 231 for extracting the non-recoverable refrigerant.

With the valve 241a closed and the vacuum pump 231 active, the three-way valve 241c in the second position allows to continue the extraction and vacuum treatment system while insulating the evaporator 232 and the suction unit 233, which may complete the recovery until the refrigerant in the evaporator 232 is emptied.

Referring to fig. 7 and 8, one means for recovering and regenerating the refrigerant, relative to the prior art system of fig. 1 and 2, comprises a dry-operated compressor 243 upstream of the evaporator 232, in parallel with the delivery conduit 101. In the manner also described with reference to fig. 3-6, the dry-operating compressor 243 is either excluded from, or included in, the regeneration circuit through valves 241a and 241 b. This particular solution allows that when the pressure in the suction unit 233 falls below a threshold value, the dry-operating compressor 243 is only switched on in the suction step, obtaining a further reduction of the pressure in the conveying piping 101 and therefore in the equipment arranged between the collector 235 and the suction unit 233. Thus, similar to the other schemes described above, the dry-operating compressor 243 assists in evaporating refrigerant in the air conditioning system, increasing the rate at which refrigerant is recovered and the maximum amount of refrigerant recovered.

By closing the valves 241a and 241b and closing the dry-operated compressor 243, it is possible to operate the vacuum pump 231 in a conventional manner, which can accomplish regeneration until the refrigerant in the evaporator 232 is exhausted, by simultaneously insulating the evaporator 232 and the suction unit 233 for drawing the refrigerant that cannot be recovered, when it is not preferable to continue the recovery process.

The scheme of dry operating the compressor 243 maximizes the efficiency of the machine with minimal additional cost, as it is a low cost component and requires minimal maintenance. It does not require lubrication because it takes advantage of the oil present in the refrigerant recovered from the system. Furthermore, it generally has a high vacuum tightness and cannot be used for evacuating air-conditioning systems, but this function is not necessary, especially when there are vacuum pumps interfering with it as described above.

The foregoing description of the specific embodiments will so fully reveal the invention according to the conceptual point of view, so that others will be able to modify and/or adapt for various applications such an embodiment by applying current knowledge without further research and without parting from the invention, and it is therefore to be understood that such adaptations and modifications will have to be considered as equivalent to the specific embodiments. The methods and materials for performing the different functions described herein may have different properties for this reason without departing from the field of the invention. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

Claims (6)

1. An apparatus (230) for recovering refrigerant from an air conditioning system (200), said apparatus (230) comprising:

-a collector (235) hydraulically connected to a high pressure branch (221) and a low pressure branch (222) of the air conditioning system (200) through a fluid delivery duct (101) in the device (230);

-an evaporator (232) arranged to separate the refrigerant and impurities by evaporation of a residual liquid portion of the refrigerant, so as to obtain a purified refrigerant evaporating and rising towards an upper portion of the evaporator (232), and to obtain impurities concentrated in a lower portion of the evaporator (232);

-a suction unit (233) for circulating the purified refrigerant coming out of the evaporator (232), the suction unit (233) being hydraulically connected with the delivery duct (101) through the evaporator, the suction unit (233) comprising a compressor;

-a condenser (236) hydraulically connected to the suction unit (233), the condenser (236) being arranged to condense the refrigerant coming out of the suction unit (233);

-a storage vessel (234) hydraulically connected to the condenser (236), the storage vessel (234) being arranged to contain the refrigerant condensed by the condenser (236);

characterized in that upstream of the evaporator (232) an auxiliary compressor element is provided, arranged in parallel with the delivery duct, configured to increase the flow rate of the refrigerant towards the evaporator (232) and for assisting, in cooperation with the suction unit (233), a progressive pressure reduction of the refrigerant in the air conditioning system (200).

2. The device (230) according to claim 1, wherein the delivery duct (101) comprises a first portion (101a) downstream of the collector (235), and a second portion (101b) continuous with the first portion (101a) and arranged upstream of the evaporator (232), and the auxiliary compressor member is arranged in parallel with the second portion (101b), wherein in the second portion (101b) a feed valve (241a) is arranged movable between an open position and a closed position, such that, when the pressure in the first portion (101a) is higher than a threshold value, the auxiliary compressor member is closed and the feed valve (241a) is in an open position, and such that, when the pressure in the first portion (101a) is lower than the value, the auxiliary compressor member is open and the feed valve (241a) is in a closed position, so that the refrigerant is delivered to the evaporator (232) through the auxiliary compression member, which cooperates with the suction unit (233) for further reducing the pressure on the first portion (101a) of the delivery conduit (101).

3. The apparatus (230) according to claim 2, wherein said auxiliary compressor means for reducing the pressure of said refrigerant on said first portion (101a) of said conveying piping comprises a vacuum generating device (231).

4. The apparatus (230) according to claim 3, wherein the vacuum generating device (231) is hydraulically connected with the evaporator (232) by a three-way valve (241c), the three-way valve (241c) being arranged to selectively connect the vacuum generating device (231) with the evaporator (232) or an extraction pipe (242) in order to cause the vacuum generating device (231) to selectively operate as an auxiliary compressor member or as an extraction member for extracting the refrigerant that cannot be regenerated but still remains in the air conditioning system (200).

5. The apparatus (230) according to claim 2, wherein the auxiliary compressor means for reducing the pressure of the refrigerant on the first portion (101a) of the conveying piping (101) comprises a dry-operated compressor (243), and wherein upstream of the dry-operated compressor (243) a vacuum generating device (231) is arranged to extract non-renewable refrigerant from the apparatus (230) for recovering refrigerant.

6. A method for recovering and regenerating refrigerant from an air conditioning system (200), the method comprising the steps of:

-delivering refrigerant into a recovery and regeneration device (230) through an accumulator (235), the accumulator (235) being arranged to hydraulically connect a delivery duct (101) of the device (230) with a high pressure branch and a low pressure branch of the air conditioning system (200);

-evaporating a residual liquid portion of the refrigerant from an evaporator (232), the evaporator (232) being arranged to separate the refrigerant and impurities, obtain a purified refrigerant rising towards an upper part of the evaporator (232) for evaporation, and obtain impurities concentrated in a lower part of the evaporator (232);

-inducing suction and circulation of said refrigerant through said device (230) by means of a suction unit (233), said suction unit (233) being hydraulically connected with said delivery duct (101) through said evaporator (232);

-condensing refrigerant coming out of the suction unit (233) by means of a condenser (232) hydraulically connected to the suction unit (233);

-accumulating the refrigerant condensed by the condenser (232) into a container (234) hydraulically connected to the condenser (232);

characterized in that said step of causing suction and circulation of said refrigerant through said device (230) is performed by said suction unit (233) in combination with auxiliary compressor means operating upstream of said evaporator (232) and increasing the flow rate of said refrigerant towards said evaporator (232) for assisting a progressive pressure reduction of said refrigerant in said air conditioning system (200).