In a normal refrigerant utilising system, e.g. a refrigeration plant or air conditioning system, using CFC's as the refrigerant, the filter and accumulator are provided at separate locations in the system. Therefore they have always been manufactured and installed as separate items and oil collection may need to be carried out at both locations. Also, in a normal refrigerant utilising system using common refrigerants, the compressor lubricating oil in carried in the system with the refrigerant and eventually returns to the compressor. The amount of oil in a system varies depending on the length and diameter of plumbing and other variables and is calculated to allow sufficient to effectively lubricate the compressor.

In certain systems it has been found that oil tended to build up at particular spots and impair the performance of the system and also reduce the oil available for lubricating the compressor. For these applications an oil separator was developed in which oil was caused to settle out from the refrigerant by means of baffles and/or screens and when sufficient oil has built up, a float would cause a valve to open and the oil would be forced under pressure back to an oil reservoir or compressor crankcase.

The oil separators are usually placed in the high pressure outlet line of the compressor and are usually only found on systems of one horsepower or larger due to their high cost.

In the use of "Refrigerant Recovery Equipment" (RRE) a continual closed refrigerant circuit is not used because the compressor is used to pump refrigerant from an external refrigeration or air conditioning system into a storage cylinder. On certain types of RRE the compressor is used to pump refrigerant from the storage cylinder, through a purification system and back into the cylinder.

Because in RRE oil is collected from the refrigerant before it enters the compressor and is disposed of in other ways, any oil leaving the compressor with the refrigerant will not be returned to the compressor unless an oil separator is used.

When a compressor has been running and is turned off the outlet side will be under high pressure. If the compressor is restarted it must initially overcome this high pressure. In smaller refrigeration systems such as in household refrigerators, a bleed system is used to prevent motor damage due to the extra torque that would be required for a start up against a high pressure system. A small capillary tube with a designated inside diameter allows a small amount of refrigerant to continually flow from the high pressure side back to the low pressure side of the compressor. Thus, when the compressor is not operating the pressure between the high and low pressure sides will equalize, and start up will be under a virtual no load situation.

It is an object of a first aspect of the present invention to provide a refrigerant gas conditioner enabling a reduction in space requirements for a system utilising the gas conditioner and savings in components to be achieved.

It is a further and preferred object according to the first aspect of the invention to enable lubricant collection to be carried out at a reduced number of locations. It is the primary object of the present invention according to a second aspect to provide a lubricant collector for collecting oil from high pressure refrigerant and enabling both return of lubricant to the compressor and pressure equalisation upstream and downstream of the compressor after compressor shutdown. It is a preferred object of the present invention according to the second aspect to provide a relatively compact and inexpensive means of achieving the primary object of the second aspect.

According to a first aspect of the present invention there is provided a refrigerant gas conditioner for conditioning refrigerant gas, the conditioner being characterised by: a housing, an inlet in the housing for admitting refrigerant gas in liquid and/or vapour phase, an accumulator section in the housing for receiving refrigerant from the inlet and for collecting refrigerant in the liquid phase together with oil and allowing the refrigerant to separate by vaporisation, a vapour outlet in the housing through which refrigerant in vapour phase passes out of the housing, a filter element through which refrigerant entering the inlet must pass before reaching the vapour outlet, the filter element being arranged within

the housing and located above the accumulator section so as to drain any separated oil by gravity into the accumulator section of the housing, and an oil port in the accumulator section through which oil passes from the accumulator section out of the housing. Preferably there is provided a heating pipe in the accumulator section, the heating pipe being arranged to receive superheated high pressure refrigerant from an associated compressor so that the compressed refrigerant from the high pressure side of the compressor passes through the heating pipe and the superheat is yielded to the liquid phase refrigerant in the accumulator section.

In a first possible embodiment, the filter element is located in an upper portion of the housing, the inlet also being located in an upper portion of the housing so that refrigerant passes through the filter element in passing to the accumulator section, the vapour outlet being elevated above the accumulator stage and being located on the downstream side of the filter element relative to the inlet. In this embodiment, the filter element may rest on a support ledge extending inwardly from the walls of the housing, any oil collected and separated by the filter element draining from the support ledge into the accumulator section located below the support ledge. The filter element may comprise an inverted cup shaped element, the outlet comprising an outlet tube extending up into and opening at the top of the tube within the inverted cup shaped filter element.

In a second alternative embodiment, the filter element is located in an upper portion of the housing and is arranged to drain oil separated thereby into a lower portion of the housing where the accumulator section is located, the inlet being provided in a lower portion of the housing so that refrigerant enters the inlet directly into the accumulator section, the vapour outlet being located in an upper portion of the housing and downstream of the filter element relative to the inlet so that refrigerant in the vapour phase passes from the accumulator section upwardly through the filter element and thence to the vapour outlet. In this embodiment, the filter element may rest on a support ledge extending inwardly from the walls of the housing, any oil collected and separated by the filter element draining from the support ledge into the accumulator section located below the support ledge. The filter element may be of generally inverted cup shape and may be located above the accumulator section

so that refrigerant in the vapour phase passes upwardly into the inverted cup shaped filter element and passes therethrough to reach the vapour outlet. A coarse filter element comprising a filter gauze and associated baffle may be located above the accumulator section and above the inlet and below the filter element so that refrigerant in the vapour phase passes upwardly through the coarse filter element before reaching the filter element, oil separated by the coarse filter draining into the accumulator section.

An oil port communicating with the accumulator section may be provided, the oil port enabling collection of oil separated in the accumulator section and also drainted from the filter element into the accumulator section, the oil port being selectively opened to enable collection of oil.

An oil return port may communicate with the accumulator section and open into a vapour line extending from the vapour outlet, whereby oil collected in the accumulator section can be returned to an associated compressor or reservoir together with refrigerant in the vapour phase passing from the vapour outlet through the vapour line.

The present invention according to the first aspect also provides a refrigerant recovery apparatus having a compressor for compressing refrigerant recovered from an associated external refrigerating or air conditioning system, a condenser for receiving high pressure refrigerant from the compressor and for condensing the same, a refrigerant collection vessel for collection of liquid phase refrigerant from the condenser, the refrigerant recovery apparatus being characterised by a refrigerant conditioner according to the present invention, the refrigerant conditioner being connected so as to receive refrigerant from the external system through the inlet to the housing, the vapour outlet of the conditioner being connected to an inlet of the compressor, the high pressure outlet of the compressor passing superheated compressed vapour phase refrigerant through a heat exchange pipe passing through the accumulator section of the conditioner, the high pressure refrigerant then being passed to the condenser. The present invention according to the second aspect provides a lubricant separator for a refrigerant utilising system having a compressor, the lubricant separator being characterised by a housing defining a vessel, a refrigerant inlet for receiving high pressure

refrigerant from the associated compressor with lubricant contained in the refrigerant, the housing containing a liquid separating stage for separating and collecting lubricant from the high pressure refrigerant, a refrigerant outlet from the vessel for passing refrigerant therefrom, a lubricant outlet which is continuously open in use for lubricant flow and which communicates with a lubricant return line, the lubricant return line extending to the point upstream of the compressor or to a lubricant reservoir associated with the compressor, the lubricant return line also providing refrigerant communication between the high pressure side of the compressor and the low pressure side to enable pressure equalisation after shut down of the compressor.

The refrigerant inlet is preferably provided in the bottom of the vessel, the separating stage comprising a tortuous path providing a high surface area so as to enable lubricant to be separated from the refrigerant and to drain to the bottom of the vessel, the refrigerant outlet being located in the top of the vessel.

The lubricant outlet may have an associated selectively operable valve to control the flow rate of returning lubricant passing through the lubricant return line. This valve may comprise a hand operated valve which can be closed by an operator so that the associated compressor can be operated with an inlet supply line to the compressor closed upstream of the compressor until the pressure at the high pressure outlet side equals atmospheric pressure, whereafter the system may be opened.

Preferably, the lubricant return line is provided with a flow restricter at or downstream of the lubricant outlet, the restricter controlling the flow rate of lubricant passing through the lubricant return line so as to allow all collected oil to be returned but minimal refrigerant to be returned. The flow restricter may comprise a capillary tube of a predetermined diameter. The lubricant return line may also include a sight glass downstream of the flow restricter for enabling observation of the return oil flow.

The present invention according to the second aspect also provides a refrigerant utilising system having a compressor for compressing refrigerant and for passing refrigerant and lubricant from a high pressure side of the compressor, the system being characterised by a lubricant separator according to the second aspect

of the present invention, the lubricant separator being connected to receive refrigerant and lubricant from the compressor through the refrigerant inlet thereof and having the refrigerant return line connected to a point upstream of the compressor or to a lubricant supply reservoir associated with the compressor.

Possible and preferred features of the present invention will now be described with particular reference to the accompanying drawings. However it is to be understood that the features illustrated in and described with reference to the drawings are not to be construed as limiting on the scope of the invention. In the drawings:

Fig. 1 shows a sectional view through a gas conditioner according to the first aspect of the present invention,

Fig. 2 shows a sectional view of an alternative possible embodiment of a gas conditioner according to the first aspect, and

Fig. 3 shows a perspective, part cut away view of a lubricant separator according to the second aspect of the invention.

Referring to Fig. 1, the gas conditioner as illustrated is particularly useful for refrigerant recovery equipment (RRE) receiving refrigerant gas from an external system such as a refrigerator or air conditioning plant being drained for servicing or repair. In this situation, oil must be removed from the refrigerant prior to the refrigerant entering the compressor of the RRE.

In Fig. 1 there is a conditioner 10 which provides both filtering and accumlator functions and has other advantages.

Refrigerant that is being either recycled from a storage cylinder and being cleaned, or is being recovered from an external system containing refrigerant enters through refrigerant inlet 11 in the housing 12. Refrigerant passes through the filter element 15 which is in the form of an inverted cup shaped element. The filter element 15 functions to remove contaminants from the refrigerant, including particulate contaminants, moisture and possibly also lubricating oil. The liquid phase refrigerant and/or other matter that passes through the filter 15 accumulates in the accumulator section 20 in the bottom of the housing 12.

Superheated refrigerant from the high pressure side of an associated compressor 17 enters through high pressure inlet 21, the superheated refrigerant passing through heating pipe 22 shown as a

coil located in the accumulator section 20. Heat is yielded by the refrigerant so as to cause or assist vaporisation of the liquid refrigerant in the accumulator section 20. High pressure refrigerant leaves through high pressure outlet 23. The liquid phase refrigerant 25 in the accumulator section 20 vaporises and the vapour passes upwardly through the opening 31 in the support ledge 30 and enters outlet 26 which opens into the upper portion of the housing 12 within the filter element 15. Refrigerant can pass from the pipe 27 to the associated compressor for example. When all of the refrigerant 25 has been vaporised, the residual matter in the accumulator section 20 will be substantially entirely lubricant oil and this can be drained selectively through oil port 35. The oil can be measured if required to check the oil content of the refrigerant and/or enable re-charging of the associated refrigerant system with the required amount of oil.

The housing 12 may be provided with a permanent filter element

15 that is disposed of together with the housing 12. Alternatively the cover 13 may be removable so that the element 15 can be replaced.

The support ledge 30 supports the filter element and enables any oil separated by the filter to be drained inwardly through the aperture 31 and into the accumulator section 20. Gasket 32 is provided around the lower edge of the filter element to prevent refrigerant by-passing the element. A spring 33, or other biasing means, at the top of the filter element acts between the cover 13 and the filter element 15 and press the element downwardly onto the ledge

30. Gasket 14 is provided between the cover 13 and the housing 12.

In the alternative possible embodiment illustrated in Fig. 2, the same reference numerals are used for corresponding parts. The inlet 11 in Fig. 2 is provided in the lower accumulator section 20 of the housing 12 so that refrigerant and contaminants and oil enter the accumulator section 20. Refrigerant vapour passes upwardly through the aperture 31 in the support ledge 30 and passes through the filter 15 to the outlet 27 provided in the upper portion of the housing 12.

A coarse filter element 40 is interposed between the top of the accumulator section 20 and the aperture 31 so that refrigerant vapour and any contaminants being carried thereby must first pass through the coarse filter 40 before reaching the main filter element 15. The coarse filter 40 rests on a baffle 41 so that refrigerant vapour must

pass around the edges of the baffle 41 and pass through a substantial length of the filter 40 before reaching the aperture 31. The filter 40 may comprise a gauze material, e.g. made of copper. The filter 40 functions to separate contaminants including contaminants which can be drained back into the accumulator section 20 upstream of the filter element 15. This will prolong the effective life of the filter element 15.

The gas conditioner illustrated in Figs. 1 and 2 does not substitute for any filtration which may be placed on the high pressure side of the associated compressor 17 if that is needed.

By closing the inlet port 11 and running the associated compressor 17 until the high pressure side of the compressor equals atmospheric pressure, the filter element 15 may be replaced with virtually no loss of refrigerant to atmosphere. According to the second aspect of the invention there is provided a lubricant separator for use in a refrigeration system. The lubricant separator 50 in Fig. 3 is in use in a system including a compressor 17 having a high pressure outlet 51. The lubricant separator 50 enables continuous return of lubricant to a point 52 upstream of the compressor or to a lubricant reservoir 58 of the compressor 17, and at a controlled rate through a return line 53. The return line 53 also provides pressure equalizing communication from the high pressure outlet side 51 of the compressor 17 after a shutdown of the compressor 17 to the low pressure side 52. By creating an oil separator 50 without a float and valve mechanism, both space and cost are reduced.

Because the oil separator 50 is particularly useful for systems of less than one horsepower, a smaller physical size is possible than is currently commercially available, but the principle used in our example is useful for larger systems.

The actual method of separating the oil could also be varied by using various sieves, screens, mesh or perforated panels to allow the oil to settle and drain, but would not alter the principle of operation of this improved oil separator. The superheated refrigerant flows from the outlet 51 of the compressor 50 and enters the oil separator 50 via refrigerant inlet 55 in vessel 54 and is taken to the lowest point via pipe 56. It then flows up through the liquid separating stage 60, e.g a mesh

gauze to provide a tortuous path with a high surface area where oil separates and refrigerant flows out through outlet port 61. The separated oil settles to the bottom of the separator vessel 54. The principle up to this point is as with all oil separators and is not subject to our patent application.

The arrangement for returning the oil to the compressor 17 is where our invention lies. The oil that collects in the bottom of the separator vessel 54 enters lubricant outlet 62 and feeds down through a pipe 63, the size of which may vary as described below. In this version a hand operated valve 65 is fitted but is not a necessary component.

Downstream of the hand valve 65 is a device 66 to restrict the flow. The size of this device 66 is calculated to be sufficient to allow all of the oil that collects at this point to pass through the return line 53 but not excessive so as to prevent as much refrigerant as possible from passing through with the oil.

As an alternative to the pipe 63, a capillary tube may be used to perform the functions of the restrictor 66 which will be deleted.

Downstream from whatever form of restrictor 66 is selected a sight glass 67 may be installed to enable the operator to observe the oil passing on its way back to the compressor either via the low (suction) side point 52 or direct to the crankcase oil supply 58.

By installing the hand valve 65 and sight glass 67 it is possible to service the restrictor 66 either to change its size or to clean it. The hand valve 65 can be closed and the compressor 17 operated with the inlet line upstream closed until the downstream pressure equals atmosphere. The system may then be opened as in standard refrigeration practice. Because a filter can be installed in the low side also, this is a way of changing the filter without releasing the refrigerant into the atmosphere.

The restrictor device 66 or capillary in place of pipe 63 has a second purpose which is to allow equalization of the system as described above.

The refrigerant gas conditioner according to the first aspect of the invention enables oil collection which is important in RRE where oil may be contaminated and must be prevented from entering the compressor. If oil enters the compressor the level may rise to a

point where damage to the compressor or at least performance reduction of the compressor occurs.

By collecting the oil that has been removed with the refrigerant from the external system being serviced, the correct amount of oil to be added back into that system can be determined.

The gas conditioner described herein can remove up to 99% of oil and therefore it is suited particularly for RRE. If the gas conditioner is used in a refrigerant utilising system, such as a refrigerator or air conditioning plant, it can have a small bleed hole at the point marked 50 in Fig. 1, so that the oil can return to the compressor as is desirable in a closed refrigeration system.

The combined functions of accumulator and filter achieved by the gas conditioner is both efficient and space saving and is more economical to manufacture and use. The lubricant separator according to the second aspect of the invention, by using a restrictive device to both allow oil back to the compressor and to equalize the system, enables costs can be saved and the RRE system can be made more compact and thus lighter and easier to move around. By installing the hand valve the system can be serviced without allowing refrigerants to escape into the atmosphere and by installing the sight cover the oil flow can be visually inspected and faults readily identified.