WO1997026979A1

WO1997026979A1 - Oil reclamation device

Info

Publication number: WO1997026979A1
Application number: PCT/GB1997/000180
Authority: WO
Inventors: Richard Henry Howard Barr; Albert Neal Davies
Original assignee: Centrax Limited
Priority date: 1996-01-22
Filing date: 1997-01-21
Publication date: 1997-07-31
Also published as: AU1316497A

Abstract

An oil reclamation device (2) comprises, in a single unit, a full flow filter (10), a bypass filter (12) and a vapourising chamber (6). The full flow filter (10) extracts solid contaminants having a particle size of 15 microns or greater and the bypass filter (12) extracts solid contaminants having a particle size of 1 micron or greater. Liquid contaminants are removed in the vapourising chamber (6). If the full flow filter (10) and bypass filter (12) are fitted directly to the housing (4) of the vapourising chamber (6), the oil reclamation device (2) can be made extremely compact and easy to service. The housing of the vapourisation chamber (6) may be fitted with a heating device (72) for heating the housing (4) and additionally may be provided with means for detecting the temperature of the housing, such as a thermocouple (74). The thermocouple (74) can be used to control the output of the heating device (72) in response to the detected temperature of the housing (4). In this way, the housing (4) is kept within an acceptable temperature range, to ensure vapourisation of liquid contaminants in the vapourising chamber (6).

Description

OIL RECLAMATION DEVICE

This invention relates to an oil reclamation device for reconditioning oil used in machinery such as an internal combustion engine or an hydraulic system. Oil reclamation devices are already known which condition a bypass flow of oil and work in tandem with a conventional full flow oil filter. In many applications, it is difficult to site the oil reclamation device such that there is easy access to the replaceable components of the oil reclamation device. The problem is accentuated because it is desirable to site the oil reclamation device close to the full flow oil filter, so that both of them can be accessed and serviced at the same time. According to a first aspect of the present invention there is provided an oil reclamation device comprising, in a single unit: a full flow filter for extraction of solid contaminants; a bypass filter for extraction of solid contaminants of small particle size; and a housing defining a vapourising chamber for extraction of liquid contaminants.

Because the full flow filter, bypass filter and vapourising chamber are all combined in a single unit, the oil reclamation device is compact and easy to service .

Preferably, the full flow filter and bypass filter are fitted to the housing of the vapourising chamber. Preferably the full flow filter extract solid contaminants having a particle size of 15 microns or greater and the bypass filter extracts solid contaminants having a particle size of 1 micron or greater. Preferably, the full flow filter is fitted around the bypass filter. The full flow filter and bypass filter may be fitted within a casing which is fitted to the housing of the vapourising chamber. The casing may comprise an oil flow passage which directs oil through the full flow filter and through the bypass filter. The oil passage may contain a bypass valve which allows oil to bypass the full flow filter if it becomes blocked.

The bypass valve may comprise means for detecting the operative state of the valve. Means may be provided for indicating to an operator of the machinery, to which the oil reclamation device is fitted, that the bypass valve is open. The indicating means may comprise a warning light on an indicator panel, although any suitable device is contemplated, such as a warning buzzer or bell. If the machinery comprises an internal combustion engine, the means for detecting the operative state of the valve may provide an output to an engine management system, which may for example prevent the engine being restarted while the bypass valve is blocked or may otherwise indicate to an operator that servicing is required.

The oil passage may be provided with an oil drain tap from which oil samples may be taken. The oil may then be analysed to determine its condition. The oil drain tap is preferably provided upstream of the filters so that the condition of the unfiltered oil may be determined.

Preferably, the flow of oil from the oil passage into the bypass filter is controlled by a non-return valve which prevents contaminants from the bypass filter falling back into the oil passage if the oil pressure in the oil passage subsides.

The bypass filter may be fed by a metering jet and preferably comprises a filter element of compressed cotton fibre. Preferably, a coarse filter is provided beneath the metering jet to prevent contaminants in the oil passage blocking the jet if the full flow filter becomes clogged and the bypass valve opens. The course filter may comprise a cleanable metal screen.

According to a second aspect of the present invention there is provided an oil reclamation device comprising a housing defining a vapourising chamber and a heating device for heating the housing, means being provided for detecting the temperature of the housing. Preferably, means are provided for controlling the output of the heating device in response to the detected temperature of the housing. An indicating device may be provided to warn an operator of machinery to which the oil reclamation device is fitted that the temperature of the housing of the vapourising chamber is not within an acceptable range.

For a better understanding of the present invention, and to show how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings in which:- Figure 1 is a cross-section through an oil reclamation device;

Figure 2 is an enlarged view of a metering jet, coarse filter and non-return valve fitted to the oil reclamation device; Figure 3 is an enlarged view of an oil bypass valve provided in the oil reclamation device;

Figure 4 is a view from above, partly in section, of the top of a housing of the oil reclamation device; and Figure 5 is an enlarged view of a fixing arrangement by which the housing of Figure 4 is fitted to a casing of the oil reclamation device.

Figure 6 is a cross-section through an inverted oil reclamation device; Figure 7 is an enlarged view of a vapour outlet; Figure 8 is a cross-section through an inverted oil reclamation device having a bypass filter with a central mandrel;

Figure 9 is a cross-section through an oil- reclamation device having "spin-on" type canister filters;

Figure 10 is a cross-section through an inverted form of the oil reclamation device shown in Figure 9; Figure 11 is a view on line A-A in Figure 10; and Figure 12 is a partially sectioned view of an oil reclamation device in which the full flow filter and bypass filter are housed in separate "spin-on" canisters.

Figure 13 is a partially sectioned view of a modified oil reclamation device with the full flow filter and bypass filter disposed side-by-side; and Figure 14 is another modified oil reclamation device in which the full flow filter and bypass filter are disposed side-by-side.

Referring to Figure 1, an oil reclamation device, indicated generally at 2, comprises a housing 4, defining an oil vapourisation chamber 6, fitted to a casing 8 which contains a full flow filter 10 and a bypass filter 12.

A substantially L-shaped oil passage 14 is provided in the casing 8. A first branch 16 of the oil passage 14 extends from an oil inlet 18 at the top of the casing 8 to an oil outlet 20 at the bottom of the casing 8. An opening 26 is provided at the upper end of the first branch 16 of the oil passage 14 to communicate the upper end of the oil passage 14 with the interior of the casing 8. A second branch 22 of the oil passage 14 extends from the oil outlet 20 to an opening 24 which communicates the lower end of the oil passage 14 with the interior of the casing 8. A bypass valve 28 extends across the first branch 16 of the oil passage 14 through the wall of the casing 8. In its normally closed condition, the bypass valve 28 prevents flow of oil along the first branch 16.

Situated along the second branch 22 substantially centrally with respect to the oil reclamation device 2 as a whole, is located a drain tap 30 which extends through the wall of the casing towards the exterior of the oil reclamation device 2. A metering jet housing 32, situated above the drain tap 30, extends inwardly through the wall of the casing 8 and provides fluid communication between the second branch 22 of the oil passage 14 and the interior of the bypass filter 12. The bypass filter 12 comprises a pressed steel cylindrical canister 35 having centrally disposed apertures 36, 38 in its upper and lower end walls 40, 42. The lower end wall 40 is sealed to the casing 8 by means of an O-ring seal 44 and the upper end wall 42 is sealed to the housing 4 by means of an O-ring seal 46. The bypass filter 12 is oriented such that its longitudinal axis is coaxial with a metering jet 34 provided in the metering jet housing 32.

The bypass filter 12 comprises a filter element 41 of compressed twisted continuous filaments of unbleached natural cotton. The density of the filament is greater at the upper end than the lower end of the filter element 41, so that large particles tend to be trapped by the low density lower portion while smaller particles are trapped by the high density upper portion. In this way the useful life of the filter is extended and its operation is more efficient. The full flow filter 10 is situated around the bypass filter 12 and is slightly spaced from it to create an annular chamber 11. The full flow filter comprises an annular pressed steel canister 43 having inner and outer longitudinally disposed side walls 45, 47 which are provided with a plurality of small apertures 49, 51 over their entire surface area. The canister 43 is closed by upper and lower solid end walls 48, 50. The lower end wall 48 is sealed to the interior of the casing 8 by means of an O-ring seal 52 and the upper end wall of the canister 50 is sealed to the housing 4 by means of an O-ring seal 54.

The housing 4 is formed from aluminium and is cast in two parts 56, 58. The lower housing part 56 comprises an annular base portion 55 connected to a discontinuous convoluted thin wall portion 60 which is substantially M-shaped in the illustrated cross- section. A discontinuous annular flange 62 is formed integrally with base portion 55 and projects upwardly from it.

The upper housing part 58 of the housing 4 comprises a cover which engages the lower housing part 56 around the periphery of the base portion 55 and at its central portion 57. The upper housing part 58 has an inwardly facing wall 66 which is spaced from and conforms to the contours of the lower housing part 56. The oil vapourisation chamber 6 is defined between the upper and lower housing parts 56, 58.

Apertures 68 are formed around an upper part 60 of the thin wall portion 66 of the lower housing part 56 to provide fluid communication between the interior of the bypass filter 12 and the interior of the vapourisation chamber 6. Preferably, about ten aperture 68 are provided, each about m mm in diameter.

A heating element 72 is mounted centrally within the upper housing part 58 and is powered by the electrical system of the internal combustion engine.

Power may alternatively be supplied by any other source of electrical energy appropriate to a particular application.

A thermocouple 74 is mounted on the upper housing part 58 to one side of the heating element 72 and a vapour outlet 76 is located through the upper housing part 58 on the other side of the heating element 72. An oil outlet 79 is provided through the upper housing part 58 at a lower level than the vapour outlet 76.

Referring to Figure 2, the metering jet housing 32 comprises a non-return valve 80 situated beneath the metering jet 34. The non-return valve 80 comprises a ball 82 which rests on a seat 84 formed in the metering jet housing 32. The non-return valve 80 prevents solid contaminants from the interior of the bypass filter 12 dropping back into the oil passage 14 when the pressure in the oil passage 14 subsides (i.e. when an engine to which the oil reclamation device is fitted is switched off) and also prevents the loss of oil when the casing 8 is removed from the housing 4 during a filter replacement operation.

A coarse filter 86 is fitted in the metering jet housing 32 between the metering jet 34 and the non¬ return valve 80.

Referring to Figure 3, the bypass valve 28 comprises a valve element 88 which is fitted within a bore 89 through a wall of the casing 8. The valve element 88 comprises a body portion 91, which is a close fit within the bore 89, and a waisted portion 93 which is fixed between the body portion 91 and a sealing element 95. The valve element 88 is held against an abutment 90 formed on an inner wall of the casing 8, under the action of a spring 92. Fitted to an outside surface of the casing 8 is a cap 94 which locates the spring 92 and supports an electrical contact 96. An end 97 of the body portion 91 is extended towards the electrical contact 96.

Referring to Figures 4 and 5, the upper housing part 58 of the housing 4 comprises a substantially circular disc having equidistantly spaced projections 100 around its circumference. Each projection 100 is provided with a centrally disposed recess 102. Four projections 104 are formed on the casing 8, at an equidistant spacing around its upper end. Each projection 104 pivotally supports a threaded shaft 106 which engages in a corresponding one of the recesses 102 and is retained by a wing nut 108.

The oil reclamation device has many applications, but for the purpose of explaining the operation of the device, it is to be assumed that it is connected to an internal combustion engine. In use, pressurized oil from the oil pump (not shown) of the internal combustion engine is introduced to the oil passage 14 through the oil inlet 18. In normal operation, the bypass valve 28 is closed so that oil is forced through the upper opening 26 into the interior of the casing 8. From here, it passes through the apertures 51 in the outer side wall 47 of the full flow filter 10 through the filter element and out through the apertures 49 in the inner side wall 45 into the annular chamber 11 between the bypass filter 12 and the full flow filter 10. The oil then passes out of the casing 8 through the lower opening 24 into the second branch 22 of the oil passage 14 . The bulk of the oil leaves the casing 8 through the oil outlet 20 and is returned to the engine, still under pressure, to be used for lubrication.

A proportion of the oil in the second branch 22 of the oil passage 14 passes through the non-return valve 80 and coarse filter 86 in to the metering jet 34. The oil is ejected at a controlled rate from the metering jet 34 and is forced through the filter element 41 to the aperture 38 in the end wall 42 of the canister 35. The use of a metering jet 34 not only ensures good dispersion of the oil through the filter element 41, but also ensures that only a small proportion of the high pressure oil is diverted through the bypass filter, rather than being directed to the engine. It has been found that a bypass flow of approximately 6% to 10% of the total flow is appropriate for most applications.

As the oil passes through the filter element 41, solid particles down to about 1 micron in size are trapped by the filter element.

This filtered oil is forced upwardly into the housing 4 and is then ejected through the apertures 68 in the thin wall portion 66 of the lower housing part 56 to form a thin film on the walls of the vapourisation chamber 6.

Electrical energy is supplied to the heating element 72 which heats the entire upper housing part 58 by conduction. The heating element 72 also heats the lower housing part 58 by conduction due to the good heat transmitting surface contact between the upper and lower housing parts 56, 58 around their peripheral edges and directly beneath the heating element 72. The heat supplied should be sufficient to evaporate the light liquids in the oil, such as fuel, water and antifreeze, or like contaminants, without evaporating a substantial amount of the oil itself. To achieve this, the housing 4 is preferably maintained within a temperature range of 90.6 to 93.3°C (195 to 200°F) .

The thermocouple 74 constantly monitors the temperature of the housing 4 and by means of suitable circuitry (not shown) controls the operation of the heating element 72 to maintain the required temperature range. The heating element 72 may, alternatively, be provided with a thermostat which controls its heat output.

The thermocouple 74 may operate an indicating device (not shown) which warns an operator of the internal combustion engine, if the temperature of the housing 4 is not within the desired range. The evaporated contaminants pass out of the housing 4 through the vapour outlet 78 and are then vented to the atmosphere or may alternatively be fed back into the induction system of the engine to be consumed during combustion.

The filtered oil adheres to the walls of the vapourisation chamber 6 as a thin film and gradually passes through the vapourisation chamber along a convoluted path until it passes out of the oil reclamation device through the outlet 79. A length of clear plastic pipe may be connected to the outlet 79 so that an immediate check can be made as to whether oil is flowing properly through the oil reclamation device. The pipe may also provide a visual indication of the condition of the oil leaving the reclamation device. During its passage through the oil vapourisation chamber 6, the oil is constantly maintained at a temperature sufficient to cause evaporation of liquid contaminants, so that the oil leaving the oil reclamation device through the outlet 79 is substantially free of liquid contaminants.

The vapourisation chamber 6 is at low pressure (i.e. at atmospheric pressure or at the pressure of the vehicle induction system) to facilitate the evaporation of the contaminants and hence the oil is returned to the engine sump from the outlet 79 under the action of gravity.

Referring to Figures 1 and 3, if the full flow filter 10 becomes clogged, so that the oil pressure rises within the casing 8, at a certain point, the force on the sealing element 95 of the valve element 88 will overcome the force of the spring 92. Consequently, the valve element 88 will be driven away from the abutment 90, thereby aligning the waisted portion 93 of the valve element 88 with the oil passage 14 and permitting the flow of oil past the bypass valve 28. At the same time, the extended end 97 of the valve element 88 is driven into the electrical contact 96, causing a warning signal to be generated on the operating panel of the internal combustion engine. In this way, an operator of the machine is aware that the bypass valve 28 has opened and hence that the full flow filter 10 must be replaced.

At the prescribed service internals or when a warning is given that the bypass valve 28 is open, the full flow filter and bypass filter 12 can be replaced by unscrewing the wing nuts 108 and separating the housing 4 from the casing 8. The old filter canisters and O-ring seals may then be removed and replaced with fresh components, as in a conventional filter replacement operation. The housing 4 is then located over a gasket on the casing 8 and the threaded shafts 106 are pivoted up into respective recesses 102 on the upper housing part 58. The wing nuts 108 are then screwed onto the threaded shafts 106 to secure the housing 4 to the casing 8.

Before the casing 8 is separated from the housing 4, a sample of oil may be drawn off through the drain tap 30 and sent away for analysis. The drain tap 30 may also be used to completely drain the oil passage 14, to prevent spillage of oil during the filter replacement operation.

In this embodiment, the oil inlet 18 and the oil outlet 20 are spaced apart vertically, for ease of illustration. However, it will be appreciated that they could be positioned to suit existing engine porting with the oil passageways, bypass valve 28 and drain valve 30 positioned accordingly. A preferred orientation would be for the ports to be situated side by side, in close relationship to each other, at the top end of the filter housing 4.

The oil reclamation device has been illustrated such that the housing 4 is mounted above the casing 8. However, in an alternative embodiment, shown in Figure 6, the oil reclamation device is mounted in an inverted state. The basic construction of the oil reclamation device is similar to the previous embodiment and the same reference numbers are used to identify the corresponding portions of the device. Because, in this inverted orientation, the bypass filter 12 is situated above the oil vapourisation chamber 6, the heating element 72 can be fitted directly into the housing part 58. The housing part 58 is provided with discontinuous annular baffles 59 on to which oil is sprayed from above from the apertures 68. As a consequence of this orientation, an oil film is established over the surface of the baffles 59 and on the interior surface of the housing part 58 and as these parts are formed in one piece, they provide a continuous heat sink which surrounds the heating element 72, . Consequently, proper vapourisation of the oil can be achieved using a heating element 72 of lower specific output than is required by the previous embodiment.

The purified oil passes out of the vapourisation chamber 6 through an outlet 79 and is returned to the engine sump under the action of gravity. The evaporated contaminants pass out of the vapourisation chamber 6 through the vapour outlet 76 shown in Figure 7. The vapour outlet 76 is mounted in a projection formed on the upper edge of the housing part 58 and is connected to the interior of the vapourisation chamber 6 by means of a passageway 71.

The vapour outlet 76 is connected to the induction system of the engine by means of a vacuum pipe and is provided with a check valve to prevent oil being drawn out of the vapourisation chamber 6 into the induction system, if there is a large drop in manifold pressure. Pressurized oil enters the oil reclamation device through the inlet 18 and the bulk of the oil returns to the engine through the outlet 20, having passed through the full flow filter 10. Six to 10% of the pressurized oil which enters the oil reclamation device through the inlet 18 passes through the bypass filter 12 via the metering jet 34. In this embodiment, the metering jet 34 is situated above the bypass filter 12, so there is no risk of oil leaking back through it when the supply of pressurized oil stops (e.g. when a engine to which the oil reclamation device is fitted is switched off) . Consequently, there is no need for a non-return valve in the metering jet housing 32. There is, however, a course filter in the metering jet housing 32 as in the previous embodiment.

Periodic monitoring of the condition of the oil is carried out by drawing off oil through the drain tap 30. The drain tap is situated at the end of a passage 31 which is formed through the housing parts 56, 58 and opens into the oil passage 14 close to the pressurised oil inlet 18.

Figure 8 shows a modified form of the Figure 6 embodiment in which the bypass filter 12 is provided with a central perforated mandrel 13. The mandrel 13 provides a circular flow passage which is open at its end towards the vapourisation chamber 6 and which is closed off at its end towards the metering jet 34.

The bypass filter 12 is sealed to the housing part 56 of the vapourisation chamber 6 by means of an O-ring seal 37 and is held against the seal by means of a spring 33 which acts between the body of the oil reclamation device and the upper wall of the bypass filter 12.

The outer side wall 39 of the bypass filter 12 is provided with perforations, so that oil ejected from the metering jet 34 passes outwardly over the top of the bypass filter 12, is forced down the sides of the bypass filter 12 and is ejected through the apertures in the side wall 39 into the filter media of the bypass filter 12. The filter media of the bypass filter 12 comprises a filter element 41 of compressed twisted continuous filaments of unbleached natural cotton. The cotton filaments are wound on to the central mandrel 13 during manufacture of the bypass filter 12 resulting in a denser filter media adjacent the mandrel 13 than adjacent the side wall 39 of the bypass filter 12. Oil pressure forces the oil across the bypass filter 12 into the interior of the mandrel 13 through the openings in the side wall of the mandrel 13. From there, the oil is forced into the vapourisation chamber through the apertures 68 in the housing part 56 of the vapourisation chamber 6.

The present invention is applicable not only to oil reclamation devices in which the filter elements are contained in a removable casing, but is also applicable to an oil reclamation device having rigid canister "spin-on" filters. In such an embodiment both filters would be screwed onto the housing 4, for example, one beside the other or one inside the other. Also a single spin-on filter is contemplated which contains both a full flow filter and a bypass filter. In order to provide the necessary distribution of oil through the filter elements, the oil flow passage 14 could be incorporated into the housing 4. Figure 9 shows an embodiment of the invention using a single "spin-on filter" which incorporates both a bypass filter 12 and a full flow filter 10 in a common canister 110. The canister 110 is of conventional appearance comprising a cup shaped steel body portion 112 fixed to an annular wall 114 which is integrally formed with an annular flange 116 having an internal thread.

The housing 4 is of similar construction to that of the Figure 1 embodiment. However, the housing part 56 is connected to a plate 118 which forms part of an engine mounting bracket 117 and contains an oil flow passage and bypass valve (not shown) which opens if the full flow filter becomes clogged. Oil enters the oil flow passage through an oil inlet 119 and leaves through an oil outlet 121. The plate 118 is formed with a projection 120 having an external thread which cooperates with the internal thread in the annular flange 116 of the canister 110. An opening 122 is provided through the centre of the plate 118. An annular seal 124 is located between the periphery of the wall 114 and the plate 118 and a second oil seal 126 of smaller diameter than the first oil seal 124 is located between an intermediate portion of the wall 114 and an annular rib 128 formed on the lower surface of the plate 118.

A ring of openings 130 is provided in the wall 114 between the oil seals 124 and 126. A second ring of openings 132 is provided in the bottom wall 114 between the second oil seal 126 and the annular flange 116. The full flow filter 10 is of hollow cylindrical construction having a perforated sheet steel, or perforated cardboard carcass 134 containing a conventional full flow filter element 136. The bottom wall of the full flow filter 10 is sealed to the bottom wall of the canister 110 by means of an O-ring seal 138 and the upper wall of the full flow filter 10 is sealed to the wall 114 by means of an O-ring seal located between the rings of openings 130 and 132.

The bypass filter 12 is located centrally within the full flow filter 10 and comprises a thin steel casing 140 which has an opening 142 at one end and which houses the metering jet 34 at the other end. A spring 144 biases the bypass filter 12 upwardly compressing an O-ring seal 142 against the wall 114 of the canister 110. The plate 118 is provided with an oil inlet 119 which is connected via the ring of openings 130 with the inlet side of the full flow filter and an oil outlet 121 which is connected via the ring of holes 132 to the inlet side of the bypass filter 12. In use, high pressure oil enters the oil reclamation device through the oil inlet 119 and passes through the ring of openings 130 into the space between the canister 110 and the full flow filter 10. Oil is forced through the full flow filter and emerges in the space between the full flow filter 10 and bypass filter 12. The bulk of the oil then passes out of the canister 110 through the ring of openings 132 and leaves the oil reclamation device through the oil outlet 121. The remaining oil (approximately 6 to 10% of the total flow) passes through the metering jet 34 into the bypass filter 12 and is forced into the vapourisation chamber 6 through the opening 122 in the bottom plate 118 and through the openings 68 in the housing part 58 of the vapourisation chamber 6.

An oil sampling tap may be provided on the inlet side of the oil reclamation device, from which oil samples can be taken to determine the condition of the oil. This arrangement is not illustrated in Figure 9, but could, for example, be incorporated into the oil reclamation device or could be provided as a tapping on the connection between the oil pump and the oil reclamation device.

At specified service intervals, the canister 110 is unscrewed from the housing 4 and is replaced by a fresh canister 110, in the manner of a conventional "spin-on" full flow filter.

Figures 10 and 11 show an inverted form of the oil reclamation device illustrated in Figure 9. In this embodiment, the housing 4 containing the vapourisation chamber 6 is substantially identical to that shown in the Figure 6 embodiment. However, in order to provide an oil supply to the openings 68, the opening 122 through the plate 118 is flared outwardly towards the vapourisation chamber end. A bypass valve 28 is provided to allow oil to bypass the full flow filter if it becomes blocked, and a non-return valve 80 is provided in the inlet passage 119.

Figure 12 shows an alternative embodiment of the invention using "spin-on" filters. In this embodiment, the bypass filter 12 is housed in a "spin-on" canister 146 which is screwed directly to the base of the housing 4 which contains the vapourisation chamber 6. The housing 4 is integrally formed with a mounting bracket 117 by which the oil reclamation device may be fitted to, for example, a vehicle bulk head or a suitable part of the vehicle engine such as the cylinder head or block.

Integrally formed with the mounting bracket 117 is a top plate 148 having an oil inlet (not shown) and an outlet passage 150 which extends into the housing 4. At an end of the outlet passage 150 is situated a metering jet 34 which meters the flow of oil into the bypass filter 12. The top plate 148 is substantially in the form of a conventional "spin-on" filter top plate and is provided with a ring of holes (not shown) through which oil enters a conventional "spin-on" full flow filter canister 152, and a threaded flange (not shown) onto which the canister 152 is screwed and which provides an oil outlet from the canister 152. In use, oil under pressure is pumped into the oil inlet and passes through the holes in the top plate into the space between outside surface of the full flow filter element and the inside wall of the canister 152. Oil pressure forces the oil through the filter element into a perforated central mandrel which is aligned with the threaded flange in the top plate 148. The oil passes up the mandrel, through the threaded flange and into the outlet passage 150. The majority of the oil is then be returned to the engine to be used for lubrication.

Six to 10% of the oil which has passed through the full flow filter is forced through the metering jet 34 into the bypass filter 12. Oil passes through openings 154 into the space between the outside wall of the bypass filter 12 and the inside wall of the filter canister 146, is forced through the filter element into a central mandrel, passes up into the housing 4 and is ejected into the vapourisation chamber 6 through the opening 68. The construction and operation of the housing 4 containing the vapourisation chamber 6 is identical to the Figure 1 embodiment and is not repeated.

As in the previous embodiments, a bypass valve (not shown) is provided in the top plate 148 to allow oil to bypass the full flow filter if the full flow filter becomes blocked.

At specified service intervals, or when one or other of the filters becomes blocked, they are simply unscrewed from their respective top plates and replaced with fresh canisters. A conventional "spin-on" canister filter can be used as the full flow filter in this embodiment and, apart from the filter element, the construction of the "spin-on" bypass filter is substantially conventional. Hence the oil reclamation device will be inexpensive and easy to service. Furthermore, although the full flow filter, bypass filter and vapourisation chamber are contained in a single unit, the full flow filter and bypass filter can be replaced independently of one another, so that the replacement interval for the full flow filter does not have to be the same as the replacement interval for the bypass filter.

The oil returned to the engine from the outlet 79 of the oil reclamation device is substantially free of solid contaminant particles greater than 1 micron and is also substantially free of liquid contaminants. Consequently, the oil is substantially reconditioned and refined and is suitable for extended use. For example, an internal combustion engine in a vehicle could be expected to run for hundreds of thousands of miles without an oil change, if an oil reclamation device according to the present invention is fitted. Figure 13 shows a modification of the Figure 12 embodiment in which the oil outlet passage 150 from the full flow filter housing is connected to a flow passage 14 which extends within the casing 8 of the bypass filter 12. A metering jet 34 is provided in the end of the oil passage 14 beneath the full flow filter 12. In use, filtered oil from the full flow filter housing is forced under pressure down the oil passage 14 and is ejected from the metering jet 34 into the bypass filter 12. Following filtration by the bypass filter 12, the oil is forced up into a vapourisation chamber where impurities are driven off and the oil is returned to the engine, as described in the previous embodiments.

Figure 14 shows an oil reclamation device similar to the Figure 13 embodiment in which the bypass filter 12 and vapourisation chamber 6 are inverted. In this embodiment, the oil outlet passage 150 from the full flow filter terminates at a metering jet 34 in the top of the bypass filter housing 8. In use, oil which has been filtered by the full flow filter is forced through the metering jet 34 into the bypass filter 12. Following filtration by the bypass filter, the oil passes into the vapourisation chamber 6 through the apertures 68. The impurities are driven off in the vapourisation chamber 6 and the oil is returned to the engine in a similar manner to the Figure 6 embodiment described above. For ease of operation, a drain tap 30 opens directly into the oil outlet 150 from the full flow filter, so that oil samples can be drawn from the oil flow before it enters the bypass filter.

At specified service intervals, the full flow filter canister in the Figure 13 and 14 embodiments can be unscrewed and replaced with a fresh canister. Also screws 154 on the housing 8 of the bypass filter 12 are unscrewed so that the lower portion of the housing 8 can be removed, together with the bypass filter 12. A fresh bypass filter 12 is then installed, the bypass filter housing 8 reassembled and the nuts 154 tightened to complete the servicing procedure.

Claims

1. An oil reclamation device comprising, in a single unit: a full flow filter for extraction of solid contaminants; a bypass filter for extraction of solid contaminants of small particle size; and a housing defining a vapourising chamber for extraction of liquid contaminants.

2. An oil reclamation device as claimed in claim 1, in which the full flow filter and bypass filter are fitted to the housing of the vapourising chamber.

3. An oil reclamation device as claimed in claim 1 or 2, in which the full flow filter is fitted around the bypass filter.

4. An oil reclamation device as claimed in any one of claims 1 to 3, in which the full flow filter and bypass filter are permanently fitted into a replaceable canister, which is releasably connectable to the housing.

5. An oil reclamation device as claimed in claim 1 or 2, in which the full flow filter and bypass filter are disposed side by side.

6. An oil reclamation device as claimed in any one of claims 1, 2 or 5, in which the full flow filter and bypass filter are permanently fitted into respective replaceable canisters.

7. An oil reclamation device as claimed in any one of claims 1 to 3, in which the full flow filter and bypass filter are fitted within a casing which is fitted to the housing of the vapourising chamber, the casing comprising an oil flow passage which directs oil through the full flow filter and through the bypass filter.

8. An oil reclamation device as claimed in claim 7, in which the oil passage contains a bypass valve which opens to allow oil to bypass the full flow filter if the full flow filter becomes clogged.

9. An oil reclamation device as claimed in claim

8, in which means is provided for detecting whether the full flow filter is clogged.

10. An oil reclamation device as claimed in claim

9, in which the means for detecting whether the full flow filter is clogged comprises means for detecting the operative state of the bypass valve.

11. An oil reclamation device as claimed in any one of claims 8 to 10, in which means is provided for indicating to an operator of machinery to which the oil reclamation device is fitted that the filter is clogged.

12. An oil reclamation device as claimed in claim 11, in which the indicating means comprises a warning light on an indicator panel.

13. An oil reclamation device as claimed in claim 11 or 12, in which the indicating means emits an audible warning.

14. An oil reclamation device as claimed in any one of claims 7 to 13, in which the oil passage is provided with an oil drain tap.

15. An oil reclamation device as claimed in any one of the preceding claims, in which oil is ejected into the bypass filter from a metering jet.

16. An oil reclamation device as claimed in claim 15, in which a coarse filter is provided beneath the metering jet.

17. An oil reclamation device as claimed in any one of the preceding claims, in which the bypass filter comprises a filter element of compressed cotton fibre.

18. An oil reclamation device as claimed in any one of the preceding claims, in which the housing is provided with a heating device.

19. An oil reclamation device as claimed in claim 18, in which the housing is provided with temperature detecting means.

20. An oil reclamation device as claimed in claim

19, in which means are provided for controlling the output of the heating device in response to the output of the temperature detecting means.

21. An oil reclamation device comprising a housing defining a vapourisation chamber and a heating device for heating the housing, means being provided for detecting the temperature of the housing.

22. An oil reclamation device as claimed in claim 21, in which means are provided for controlling the output of the heating device in response to the detected temperature of the housing.

23. An oil reclamation device as claimed in claim 21 or 22, in which an indicating device is provided to warn an operator of machinery to which the oil reclamation device is fitted that the temperature of the housing of the vapourisation chamber is not within an acceptable range.

24. An oil reclamation device, substantially as described herein, with reference to and as shown in Figures 1 to 5, Figures 6 and 7, Figure 8, Figure 9, Figures 10 and 11 or Figure 12 of the accompanying drawings.