GB2265095A - Filter for diesel fuel - Google Patents

Abstract

A filter for diesel fuel comprises a housing enclosing a primary heater 9 and a graduated filter means 4, through which fuel flows from inlet 11 to outlet 14 and thence to the engine. Heater 9 is controlled by a thermostat in response to ambient air temperature and ensures that filter means 4 will not be clogged by wax particles. A second heater 13 at the bottom of the housing boils off any water which settles in that region, via secondary outlet 5, 6, and also heats the fuel further to enhance engine efficiency. In Figs. 4, 5 not shown, the heaters are arranged in separate chambers, upstream and downstream of the filter means, and the housing lid is lined with gauze which absorbs rising water vapour. <IMAGE>

Description

DIESEL FILTER DESCRIPTION This invention relates to a filter for fluids and is especially, but not exclusively, related to such a filter for diesel oil being supplied to a diesel engine of, say, a vehicle.

Diesel oil is obtained from crude oil in substantially the same manner as most other petroleum by-products distilled therefrom. Each such by-product has its own boiling point and is obtained by separating it from the other components of the crude oil by condensing it from the main crude distillate at a predetermined temperature.

Unfortunately, the modern technology associated with the refining of crude oil has failed to isolate many of the hydrocarbons at each distillation stage and, as a consequence, diesel oil is collected as a condensate contaminated with unwanted particles.

Efforts to remove these unwanted particles by, say, heating or chemical action have been substantially unsuccessful, in that the chemical composition and/or physical properties of the diesel oil itself are changed.

Although the unwanted particles in diesel oil are extremely small, they still tend to have an abrasive effect on the various components, such as, injectors, exhaust valves, pistons and cylinder walls, of diesel engines. Also, as these particles tend not to burn with the diesel oil during the combustion process, the power ratios of the diesel engines are correspondingly decreased and the level of harmful exhaust emissions is increased.

If these undesirable effects of unwanted particles in diesel oil could be overcome, then diesel engines could be redesigned in lighter materials, such as, aluminium alloys, rather than using the heavy cast iron blocks and heads of existing diesel engines.

Accordingly, the present invention sets out to overcome, or at least substantially reduce, the disadvantages associated with existing particlecontaminated diesel oil, as well as other types of fuel and lubricating oil which are similarly contaminated, so that diesel engine design, as well as other devices, such as, other types of internal combustion engine, oil pumps and the like, can be redesigned to be more efficient and cost effective.

One aspect of the present invention provides a fluid filter, preferably of generally unitary structure, comprising filter means through which a fluid to be filtered can be passed and primary heating means arranged to heat the fluid prior to its being passed through said filter means.

Secondary heating means may also be provided, preferably downstream of the filter means, for further heating of the fluid.

Another aspect of the invention resides in a fluid filter, preferably of generally unitary structure, comprising filter means through which a fluid to be filtered can be passed and means arranged to heat the fluid to a sufficient temperature to volatise any unwanted volatilisable material for subsequent removal thereof from the filter.

Such removal of any unwanted material, such as, a liquid by volatilisation may be carried out prior to, during or after filtration of the fluid, depending upon the location of the volatilising means with respect to the filter means.

In a preferred embodiment, however, such volatilising means is constituted by the optional secondary heating means which may be associated with the fluid filter defined above in accordance with the first aspect of the invention.

In the preferred embodiment of the invention also, the fluid filter is in the form of a diesel oil filter, the primary heating means being provided upstream of the filter means which is preferably graduated to filter out particles of decreasing size as the diesel oil is being passed therethrough.

Such graduated filter means may comprise discrete regions of given mesh sizes or may comprise a mass of filter material of continuously decreasing mesh size.

The preferred embodiment of diesel oil filter may be provided further with the secondary heating means downstream of the filter means for volatilising any undesirable liquids which may be present in the diesel oil after it has been passed through the filter means, whilst also preheating the filtered diesel oil prior to its being injected into the associated diesel engine.

Such secondary heating means may be included, for instance, embedded, in the filter means or may be provided upstream of the filter means, whereby any such liquid is volatilised prior to the diesel oil being passed through the filter means. In either of these cases, the volatilising means may be constituted by the secondary heating means or by other heating means, for instance, the primary heating means or additional heating means.

In the preferred embodiment, the volatilising means is in the form of a heater which heats previously-filtered diesel oil to a temperature above 1000C preferably about 2000C, to boil-off any moisture contained in the diesel oil. The resulting steam may be removed via an exhaust located adjacent the volatilising means.

Also, a third aspect of the invention involves a combination of the first and second aspects of the invention defined above, namely, a fluid filter, preferably of generally unitary structure, comprising filter means through which fluid to be filtered can be passed, primary heating means for heating the fluid prior to its passage through said filter means and means arranged to heat the fluid to a sufficient temperature to volatise an unwanted volatisable material for subsequent removal thereof from the filter.

The filter is preferably provided as a unitary structure which, when in the form of a diesel oil filter, can be inserted as a preformed unit in the fuel line between the diesel oil tank and associated diesel engine, rather than having separately located heating means and filter means, as in the case of prior art arrangements, where a heater is provided in the diesel oil or other fluid tank and is quite separate from any filter device for the oil or other fluid.

Any steam and/or other volatised liquids boiledoff from the diesel oil in the filter may be exhausted to the atmosphere or cooling system of the associated diesel engine.

Additionally or alternatively, a moistureabsorbing material may be associated with the filter for removing substantially all of any water or moisture contained in the fluid, such as, diesel oil, being filtered.

The filter, primary, secondary and/or other heating means may be located within respective generally separate compartments of the filter, with adjacent compartments in communication with each other to allow filtered/heated fluid to pass therethrough.

In order that the invention may be more fully understood, preferred embodiments of diesel oil filter will now be described by way of example and with reference to the accompanying drawings in which: Figure 1 is a sectional elevation of a first embodiment of filter; Figure 2 is a top plan view of the filter shown in Figure 1; Figure 3 is a bottom plan view of the filter shown in Figures 1 and 2.

Figure 4 is a plan view of a second embodiment of filter; and Figure 5 is a sectional elevation of the filter shown in Figure 4 along the line V-V thereof.

Referring firstly to Figures 1 to 3 of the drawings, a first embodiment of a diesel oil filter of unitary structure for incorporation in the fuel line of a diesel-engined vehicle, such as, a truck, is indicated generally at 1.

A generally cylindrical filter housing 2 of mild steel, aluminium alloy or similar material, has an internal annular shoulder 3 upon which rests a body 4 of suitable filter material.

Extending coaxially through the filter body 4 is an exhaust duct 5 whose lower end flares radially outwardly into a cone-shaped hood 6 with an open bottom end 7.

Secured to the top of the cylindrical filter housing 2 is an upper end cap 8 whose inner top wall is provided with a primary heating element 9.

The duct 5 extends coaxially through the heating element 9 and the top end cap 8 to protrude therefrom and is secured threadedly thereto by a threaded nut 10.

An inlet 11 for diesel oil also extends through the top end cap 8 to communicate with the interior of the cylindrical filtration housing 2 at the top end thereof.

At the bottom end of the cylindrical filter housing 2 is secured another, lower end cap 12 and this is provided with a secondary heating element 13 on its inner top wall.

An outlet 14 for filtered and heated diesel oil extends through the cylindrical wall of the filter housing 2, whilst the open lower end 7 of the coneshaped hood 6 at the lower end of the duct 5 is spaced slightly from the heating element 13.

The mating surfaces of the top and bottom end caps 8 and 12, and the corresponding top and bottom ends of the cylindrical filter housing 2 are provided with suitable sealing means, such as, O-rings, to provide fluid-tight seals therebetween. Also, the primary and secondary heating elements 9, 13 are of the electrical resistance type and are thermostatically controlled, with respective electrical terminals, 15, 16 being provided on the top and bottom end caps 8, 12.

Each end cap 8, 12 is internally threaded to correspond with the externally threaded top and bottom ends of the filtration housing 2.

Also, the bottom end cap 12 is provided with the drain hole 17 plugged with a removable Allen screw 18.

The primary heating element 9 is used to preheat diesel fuel pumped into the filter 1 via the inlet 11, particularly in cold weather conditions, prior to its being passed through the filter body 4. This preheating of the diesel oil not only reduces its viscosity but also contributes to the prevention of socalled "waxing" in cold weather conditions.

The primary heating element 9 is controlled thermostatically via an ambient temperature thermostat (not shown) located preferably outside the diesel engine compartment of the associated vehicle and is advantageously sited in the front grill thereof. Also, it is connected in circuit with another heating element (also not shown) located in the main diesel oil tank of the vehicle and with the ignition system of the vehicle engine, whereby the engine will only start when the diesel oil reaches running temperature.

The optimum operating temperature of the primary heating element 9 is approximately 160C (60 OF), its temperature rise time being about 30 seconds from cold.

The heating element 9 is of a short truncated cone shape and is made of electrically-resistive nickelcopper mesh having a central hole through which extends the duct 5. Also, it has an off-set hole in registration with the diesel oil inlet 11 and is electrically insulated at 19 from the top end cap 8 to which it is secured by any suitable means.

At regularly spaced intervals on the lower, face of an end plate 9' of the heating element 9 are arcuate channels (not shown) which distribute the preheated diesel oil evenly around the top of the filter body 4 after it has exited from the mesh heating element 9.

The filter body 4 comprises four discrete regions or sections of diminishing gradation, although it may be of continuously diminishing gradation.

In this particular case, the four sections are graded from 3 microns down to 0.2 microns via 1.0 and 0.5 microns and are separated by 5 mm gaps, with coaxial holes through which the duct 5 can pass.

The body 4 is made of a thermally-conductive material, to provide good heat transfer from its upper to its lower end.

The bottom secondary heating element 13 is of any suitable form, for instance, a generally circular nickel-copper alloy, resistive heating plate, and is controlled thermostatically but independently of the upper, primary heating element 9, to operate continuously while the associated diesel engine is running.

The heating element 13 is provided with a central hole in register with the plugged drain hole 17, whilst its operating temperature is approximately 2000C (3900F), the combustion temperature of the diesel fuel in the vehicle engine being in the region of 8000C (14700F). In any event, its operating temperature is sufficiently high to cause any water separating from the diesel oil in the filter to be boiled-off, its other function being to heat further the diesel oil before it is pumped to the diesel engine of the vehicle. Other, undesirable liquids having boiling points of up to 2000C (390 F) and contained in the filtered diesel oil are also volatised by the secondary heating element 13 for subsequent expulsion from the filter 1 via the exhaust duct 5.

In use of the filter 1, it is fitted in a fuel line between the diesel tank and injectors of the associated vehicle engine, with the inlet 11 being connected to the fuel pump and the outlet 14 being connected to the injector pump.

As diesel oil is pumped into the cylindrical body 2 of the filter 1 via the inlet 11, it is first passed through the mesh heating element 9.

In cold weather, that is to say, at temperatures of 00C (300F) and below, the heating element 9 and the heater in the diesel tank of the vehicle are connected in series with each other and are controlled by a thermostat located in the front grill of the vehicle, to switch the primary heating element 9 and tank heater on and off as necessary. As these are switched on, they raise the temperature of the diesel oil to approximately 160C (600F) prior to filtration, thereby reducing the viscosity of the oil and reducing its tendency to wax.

During warm weather, the heater in the diesel oil tank may be switched off but the primary heating element 9 is controlled thermostatically at all times while the engine is running. Again, this preheats the diesel oil to reduce its viscosity before it is passed through the filter body 4.

With the diesel oil now warm and of a comparatively low viscosity, it is passed into the filter body 4 where it is filtered progressively as it passes through the four filter sections of reducing gradation. Correspondingly-sized particles inherent in the diesel oil are removed and any water and/or other undesirable volatisable liquid in the diesel oil either tends to collect in the filter body 4 or to separate from the filtered diesel oil downstream of the filter body 4.

Any water and/or other undesirable liquid droplets in the filter body 4 tend to agglomerate and eventually move downwardly to settle at the bottom of the filtration housing 2. At this point, the settled water and/or other liquid is boiled-off by the secondary heating element 13 and is exhausted from the filter 1 via the hood 6 and duct 5 to the atmosphere or to be condensed, such as, into the cooling system of the diesel engine itself.

As the diesel oil passes through the filter body 4, its temperature is also raised towards 2000C due to the heating action of the secondary heating element 13 at the bottom of the filter 1.

Such a substantial rise in the temperature of the diesel oil improves the efficiency of the vehicle engine to which diesel oil is pumped via the outlet 14.

The presently high combustion ratio of existing engines can be greatly reduced, whilst any particles still remaining in the preheated diesel oil are burnt more efficiently as are other potential air pollutants, such as, carbon monoxide, nitrogen oxides and hydrocarbons.

The filter body 4 can be removed for cleaning or replacement by disconnecting the fuel pipe from the inlet 11 and the electric cable connected to the terminals 15 on the top end cap 8. Then, the end cap 8 is unscrewed from the filter housing body 2. Removal of this cap 8 from the housing 2 also removes the filter body 4, duct 5 and associated cone-shaped hood 6 from the housing at the same time.

On removal of these components, the hood 6 can be unscrewed from the bottom end of the duct 5 and the filter body 4 slid therefrom, for cleaning or replacement with a new filter body.

Re-assembly of the filter 1 is carried out by reversing the steps described above.

The advantages associated with this first embodiment of inventive filter 1 fall into two categories. Firstly, preheating of the diesel or other fuel oil enables the high compression ratios of existing diesel or other internal combustion engines to be reduced, whilst enabling the materials used in engine construction to be lighter and by causing any fuel pollutants not removed by the filter 1 to be burnt-off more cleanly at the higher combustion temperatures.

Secondly the working life of the fuel injectors or valves of the engine, as well as any other associated engine components, is increased, with exhaust emissions being very much cleaner than those at present.

Referring now to Figures 4 and 5 of the drawings, a second embodiment of a diesel oil filter of unitary structure for incorporation in the fuel line of a diesel-engined vehicle, such as, a truck, is indicated generally at 101.

A filter housing 102 of mild steel, aluminium alloy or similar material, has a central compartment 103 which is of generally rectangular cross-section and in which is supported a body 104 of suitable filter material.

The filter body 104 is supported in the compartment 103 between the upper end of a duct 105, which connects the central compartment 103 to another compartment 123 to be described below, and a compression spring 106 acting between the top of the filter body and the inside wall of a cover 108 of the housing 101.

Secured by any suitable means to the top of the filter housing 102 is the cover 108 and a primary heating element (not shown) is located in a first end (left) compartment 113 of the filter housing 102 of generally semi-circular cross-section.

An inlet 111 for diesel oil is provided in the outer wall of the housing 102 and communicates with the interior of the primary heating element compartment 113 which, in turn, communicates with the central filter compartment 103 via an aperture 109 in the associated dividing wall 110.

A secondary heating element (also not shown) is located in a second end compartment 123 which, as mentioned above, communicates with the central filter compartment 103 via the duct 105 through the associated dividing wall 110.

An outlet 114 for filtered and heated diesel oil extends through the outer wall of the filter housing 102.

The mating surfaces of the cover 108 and the corresponding top ends of the walls 102, 110, 120 of the filter housing 102 are provided with suitable sealing means 130, to provide fluid-tight seals therebetween. Also, the primary and secondary heating elements are again of the electrical resistance type and are thermostatically controlled, with an electronic management unit 140 being provided on the top of the cover 108 and being retained in place by releasable clips 150. A sensor shown diagrammatically at 160, provides measurement of the flow rate of diesel oil passing through the filter 101, whilst the primary and secondary heating elements have respective connecting terminals at 170. A drain plug 180 is provided in a drain 190 in the bottom wall of the housing 102.

The primary heating element is used to preheat diesel fuel pumped into the housing 102 of the filter 101 via the inlet 111, particularly in cold weather conditions, prior to its being passed through the filter body 104. As discussed above, this preheating of the diesel oil not only reduces its viscosity but also contributes to the prevention of so-called "waxing" in cold weather conditions.

Again, the primary heating element is controlled thermostatically via an ambient temperature thermostat (not shown) located outside the diesel engine compartment of the associated vehicle and is advantageously sited in the front grill thereof. Also, it may be connected in circuit with another heating element (also not shown) located in the main diesel oil tank of the vehicle and with the ignition system of the vehicle engine, whereby the engine will only start when the diesel oil reaches running temperature.

The lowest operating temperature of the primary heating element is a constant minimum temperature of 600C (1400F), its temperature rise time being about 30 seconds from cold. This is the lowest temperature to which the diesel oil must be heated for it to have its viscosity reduced sufficiently to pass through this particular filter body 104. The applies to only Class Al diesel oils having cetane grades of 40-50. Coarsers diesel oils may require to be heated to higher temperatures, with the coarsest Class C oils requiring a temperature of about 1100C (2300F).

The primary heating element may be made of electrically-resistive nickel-copper mesh, a heating strip coiled around the inner wall of the associated compartment 113, or a heating rod. In each case, however, the primary heating element is arranged to allow convection to take place.

The filter body 104 may comprise four discrete regions or sections of diminishing gradation, although it may be of continuously diminishing gradation ranging from, say, 3 microns down to 0.3 microns, and may be made of a woven polypropylene filter medium thermally sealed and bonded to polypropylene end caps, core and cage as a replaceable cartridge.

The secondary heating element is also of any suitable form, for instance, a nickel-copper alloy, resistive heater, a heating strip coiled around the inner wall of the associated compartment 123, or a heating rod, and is controlled thermostatically but independently of the primary heating element, to operate continuously while the associated diesel engine is running.

The secondary heating element has an operating temperature of approximately 1000C (2120F) to 1500C (3020F), the combustion temperature of the diesel fuel in the vehicle engine being in the region of 8000C (14700F). In any event, its function is to heat further the diesel oil before it is pumped to the diesel engine of the vehicle. As in the case of the primary heating element, the operating temperature of the secondary heating element is dependent upon the grade of diesel oil used and the particular application of the engine for which the diesel oils is used as fuel.

In use of the filter 101, it is fitted in a fuel line between the diesel tank and injectors of the associated vehicle engine, with the inlet 111 being connected to the fuel pump and the outlet 114 being connected to the injector pump.

In cold weather at, say, temperatures of 00C (300F) and below, the primary heating element and the heater in the diesel tank of the vehicle are connected in series with each other and are controlled by a thermostat located in the front grill of the vehicle, to switch the primary heating element and tank heater on and off as necessary. As these are switched on, they raise the temperature of the diesel oil to a minimum temperature of approximately 600C (1400F) prior to filtration, thereby reducing the viscosity of the oil and reducing its tendency to wax.

During warm weather, the heater in the diesel oil tank may be switched off but the primary heating element is controlled thermostatically at all times while the engine is running. Again, this preheats the diesel oil to reduce its viscosity before it is passed through the filter body 4.

With the diesel oil now heated and of a comparatively low viscosity, it is passed into the filter body 104 where it is filtered as it passes therethrough. Correspondingly-sized particles inherent in the diesel oil are removed and any water and/or other undesirable volatisable liguid in the diesel oil either tends to collect in the filter body 4 or to separate from the filtered diesel oil downstream of the filter body 4.

Any moisture in the diesel oil is absorbed by a moisture-absorbing material in the form of a replaceable gauze (not shown) located in the underside of the cover 108 and covering substantially the whole area thereof. The replaceable, moisture-absorbing gauze is preferably held in place by means of a spring clip (also not shown) which recesses into the peripheral wall portion of the cover 108. The thickness of the gauze in this particular case is 4 millimetres.

The substantial rise in the temperature of the diesel oil due to the heating action of the secondary heating element, improves the efficiency of the vehicle engine to which diesel oil is pumped via the outlet 114. Indeed, the operating temperature of the secondary heating element is at least as great as that of the boiling point of water, substantially all of any water in the diesel oil is removed by being boiled off, with at least some being absorbed in the moistureabsorbing gauze in the underside of the cover 108.

Again, the presently high combustion ratio of existing engines can be greatly reduced, whilst any particles still remaining in the preheated diesel oil are burnt more efficiently as are other potential air pollutants, such as, carbon monoxide, nitrogen oxides and hydrocarbons.

The filter body 104 can be removed for cleaning or replacement by removing the cover 108 from the filter housing body 102. Removal of this cover 108 from the housing 102 also allows removal of the primary and secondary heating elements from their respective compartments 113, 123.

Re-assembly of the filter 101 is carried out by reversing the steps described above.

Furthermore, the interior of the filter may be pressurised. This applies to any of the embodiments described above but is especially applicable to the embodiment of Figures 4 and 5.

The filter interior may be pressurised by any suitable means but a pressure line from the injection system of the engine of the associated vehicle is preferred.

In the embodiment of filter described above in relation to Figures 4 and 5, the preferred minimum internal pressure rating of the filter is 100 KPa (14.504 psi), whilst the preferred maximum pressure rating is 500 KPa (72.519 psi).

Claims (20)

1. A fluid filter, preferably of generally unitary structure, comprising filter means through which a fluid to be filtered can be passed and primary heating means arranged to heat the fluid prior to its being passed through said filter means.

2. A fluid filter according to claim 1, including secondary heating means for further heating of the fluid.

3. A fluid filter according to claim 2, wherein said secondary heating means is downstream of said filter means.

4. A fluid filter according to claim 2, wherein said secondary heating means is included, preferably embedded, in said filter means or is located upstream of said filter means.

5. A fluid filter according to any of claims 2 to 4, wherein said secondary heating means is arranged to volatilise any undesirable material present in the fluid, for subsequent removal from the filter.

6. A fluid filter according to claim 5 when dependent upon claim 2, wherein said secondary heating means is constituted by said primary heating means.

7. A fluid filter according to claim 5 or 6, including means arranged to exhaust any undesirable and volatilised material from the filter.

8. A fluid filter preferably of generally unitary structure, comprising filter means through which a fluid to be filtered can be passed and means arranged to heat the fluid to a sufficient temperature to volatise any unwanted volatilisable material for subsequent removal thereof from the filter.

9. A fluid filter according to claim 8, wherein said volatilising means is arranged to volatilise any unwanted volatilisable material prior to, during or after filtration of the fluid by said filter means.

10. A fluid filter according to claim 8 or 9, wherein said volatilising means is located upstream of said filter means and is constituted by primary heating means arranged to heat the fluid prior to its being passed through said filter means.

11. A fluid filter according to any of claims 8 to 10, including means arranged to exhaust any undesirable and volatilised material from the filter.

12. A fluid filter according to any preceding claim, wherein said filter means is graduated to filter out particules of decreasing size from the fluid.

13. A fluid filter according to claim 12, wherein said graduated filter means comprises discrete regions of given mesh size or a mass of filter material of continuously decreasing mesh size.

14. A fluid filter according to any preceding claim, wherein at least said filter means, primary and/or secondary heating means and/or volatilising means, as the case may be, are located in the generally separate compartments in a housing for the filter, the compartments being in communication with each other to permit passage of a fluid to be filtered to pass therethrough.

15. A fluid filter, preferably of generally unitary structure, comprising filter means through which fluid to be filtered can be passed, primary heating means for heating the fluid prior to its passage through said filter means and means arranged to heat the fluid to a sufficient temperature to volatise any unwanted volatilisable material for subsequent removal thereof from the filter.

16. A fluid filter, preferably of unitary structure, comprising the combination of a fluid filter according to any of claims 1 to 7 and a fluid filter according to any of claims 8 to 14.

17. A fluid filter according to any preceding claim, wherein a moisture-absorbing material, preferably in the form of a replaceable gauge thereof, is associated with the filter, for removing substantially all of any water or moisture in the fluid being filtered.

18. A fluid filter according to -any preceding claim whose interior is capable of being pressurised.

19. A diesel oil filter substantially as hereinbefore described with reference to the accompanying drawings.

20. A diesel engine in association with a filter according to any preceding claim.