WO2005049173A1

WO2005049173A1 - Fuel filter with heating device

Info

Publication number: WO2005049173A1
Application number: PCT/EP2004/012188
Authority: WO
Inventors: Giorgio Girondi
Original assignee: Ufi Filters S.P.A.
Priority date: 2003-10-31
Filing date: 2004-10-25
Publication date: 2005-06-02
Also published as: ITRE20030024U1

Abstract

Fuel filter provided with heater device (14) comprising an outer casing (2), the interior volume of which is separated by a filtering baffle (7) into two separate chambers (10, 11) to which a fuel inlet conduit (3) and a fuel outlet conduit (4) are connected respectively, with the chamber (10) to which the fuel inlet conduit (3) is connected there being associated a hollow body (12) which opens on the outside of the filter casing, and defines a seat (120) for receiving the heating device (14).

Description

DESCRIPTION

FUEL FILTER WITH HEATING DEVICE

TECHNICAL FIELD The present invention relates, in a totally general sense, to diesel engines and more particularly to a diesel fuel filter provided with a fuel heating device.

PRIOR ART Diesel fuel for automotive use is known to normally contain impurities, because of which the diesel engine feed system must be provided with a suitable fuel filter.

Modern diesel fuel filters generally consist of a cup-shaped casing closed by a cover and containing a coaxial filter cartridge of toroidal form. Between the casing and cup two chambers are defined for passage of the diesel fuel to be filtered and of the filtered diesel fuel respectively, the first connected to the pump unit and the second to the injection unit.

The chamber for passage of the diesel fuel to be filtered is normally provided by the inner region of the filter cartridge. In addition to said impurities, diesel fuel also generally contains waxy materials, such as paraffin, which are fluid even at relatively low temperatures, of the order of -10°C, and which tend to thicken until they solidify at lower temperatures, of the order of -20/25°C.

Hence, if the engine remains inactive for a certain time at very low temperatures (less than about -20°C), said waxy materials such as paraffin separate from the diesel fuel and solidify, with consequent clogging of the filter, making it impossible to operate the engine. To avoid this problem, filters are known provide with heating devices disposed within the chamber of the diesel fuel to be filtered. The purpose of said devices, which can also be of disposable or once-only use type, is to heat the diesel fuel to be filtered present in the chamber, to raise it to a temperature such as to enable the paraffin to melt, at least at the moment of starting the engine.

As the heating devices are positioned in the chamber of the diesel fuel to be filtered they are subjected to the pressure of the diesel fuel itself, which can reach values of the order of several bar. These pressures sometimes damage known heating devices, substantially shortening their useful life and hence limiting or even inhibiting their use.

DISCLOSURE OF THE INVENTION An object of the present invention is to overcome the state drawbacks within the context of a simple, rational and low-cost solution.

The invention attains said object by virtue of the characteristics indicated in the claims.

In particular, the invention provides a fuel filter comprising an outer casing, the interior volume of which is separated by a filtering baffle into two separate chambers to which a fuel inlet conduit and a fuel outlet conduit are connected respectively.

With the chamber containing the diesel fuel to be filtered, to which the fuel inlet conduit is connected there is associated a cup-shaped hollow body which opens on the outside of the filter casing, and defines a seat for receiving the heating device. Said hollow body advantageously forms a jacket for protecting the heating device from the pressure which the fuel exerts in the chamber interior. According to the invention, said heating device is removably received within said seat and is retained therein by suitable retention means. Said retention means are partly associated with said seat for receiving the heating device and partly associated with the heating device itself, and comprise at least one movable element collaborating therewith to maintain the heating device associated with the filter. In a preferred embodiment of the invention, the retention means associated with the seat comprise an annular portion of the hollow body which branches from the filter surface. Said portion presents, symmetrical about its axis, two slots with which there corresponds on the heating device a shoulder which together with said slots defines a seat for receiving the movable element intended to maintain the heating device associated with the filter.

The movable element preferably consists of a fork spring presenting two arcuate portions having a radius equal to the outer radius of the body of the heating device. Alternatively, said movable element can consist, according to the invention, of a pin to be inserted into a matching seat, of which a portion is associated with that part of the retention means associated with the heating device and the other portion with the retention means associated with the annular portion of the hollow body branching from the filter. The movable element could also consist of a screw, in which case a threaded hole would be present in said annular portion and in a portion of the outer body of the heating device. In a further variant of the invention, said movable element is associated with the heating device and comprises at least one tooth-shaped tang to be received in said slots provided in the annular portion of the hollow body branching from the filter. In a further variant of the invention the retention means comprise matching threaded portions for screwing the heating device to the filter.

Finally, the form of the body defining the chamber for receiving the heating device preferably matches the form of the device itself.

The heating device used by the invention is a usual heater of chemical type, well known to the expert of the art.

Further characteristics of the invention are stated in the dependent claims, which describe particular advantageous embodiments thereof.

BRIEF DESCRIPTION OF THE DRAWINGS The characteristics and the constructional merits of the invention will be more apparent from the ensuing description given with reference to the figures of the accompanying drawings which illustrate a particular preferred embodiment by way of non-limiting example.

Figure 1 is a perspective view of the invention. Figure 2 is an exploded perspective view of the invention.

Figure 3 is the section Ill-Ill of Figure 2.

Figure 4 is the section IV-IV of Figure 1.

Figure 5 shows an enlargement of a portion of Figure 4.

Figure 6 shows a variant of the invention.

BEST MODE FOR CARRYING OUT THE INVENTION Said figures show a filter 1 comprising an outer casing 2 provided with a fuel inlet conduit 3 and an outlet conduit 4.

The casing 1 comprises a cup 5 which is upperly closed by a cover 6.

The interior of the casing 1 (Figures 3 and 4) receives a toroidal filtering baffle 7 supported between a lower base 8 and an upper stem 9 branching from the cover 6. Said filtering baffle divides the interior volume of the casing 2 into two separate chambers 10 and 11 of which the first,

10, is connected to the inlet conduit 3 for the fuel to be filtered and the second 11 is connected to the outlet conduit 4 for the filtered fuel. There projects into the chamber 10 from the cover 6 an internally hollow metal body 12 which extends above the cover with an annular portion 13.

The hollow body 12 defines a seat 120 (Figure 4) for receiving a chemical heating device 14 of known type for once-only use.

Said seat advantageously forms a metal jacket for protecting the heating device from the pressure exerted by the fuel in the interior of the chamber

10.

It should be noted that this device 14 is well known to the expert of the art hence its detailed description will be omitted. For the purpose of the present invention is sufficient to state that the device 14 is activated by an operating pushbutton 140 positioned at the free end thereof emerging from the seat 120.

The heating device 14 is associated with the seat 120 by suitable retention means 15.

With reference to Figure 1 , said retention means 15 are partly associated with the filter, and in particular with the hollow body 12 (Figures 3 and 4), and partly with the heating device 14. The retention means 15 associated with the filter 1 comprise that annular portion 13 of the hollow body 12 which emerges from the upper surface of the filter cover 6. The annular portion 13 presents in proximity to its upper edge two diametrically opposing slots 16, the function of which is clarified hereinafter. The retention means associated with the heating device 14 comprise an annular shoulder 17 present on the outer surface of the device itself. The slots 16 together with the annular shoulder 17 define a seat for receiving a movable element able to axially retain the heating device 14 within the seat 120 of the hollow body 12. In the illustrated embodiment, said movable element consists of a fork-shaped spring 18 centrally presenting two opposing identical arcuate portions 19 (Figure 2) having a radius of curvature matching that of the annular shoulder 17 of the heating device 14. With reference to Figure 5, when the spring 18 is inserted into the receiving seat, the device 14 is prevented from leaving the seat 120 as the annular shoulder 17 engages against the spring 18. By virtue of the described retention means, replacement of the device 14 is advantageously very quick and simple for the user. In this respect the fork-shaped spring merely has to be withdrawn to enable the device 14 to be extracted from the seat 120 of the body 16. At this point a new device can be inserted into the seat 120 and the spring 18 be inserted into its receiving seat.

Figure 6 shows a variant of the invention which differs from the already described embodiment with respect to the means which enable the device 14 to be retained within the seat 120, with particular reference to the retention means associated with said heating device. In the description of this variant of the invention the same reference numerals are used for identical components already described and illustrated in the preceding embodiment of the invention. With reference to Figure 6, this shows that the heating device 14 is provided with two opposing identical tooth-shaped tangs 22 of flexible material.

The two tangs 22 are associated with the device 14 by a preferential fracture line, not shown because of known type, which is flexible in one direction and fragile in the opposite direction. When the device 14 is received in the seat 120, the tangs 22 snap into the slots 16 in the annular portion 13, their purpose being to prevent axial withdrawal of the device 14 from the seat 12. It should be noted that in certain embodiments of the invention, said heating device can be provided with a single tang 22. When the user needs to replace the device 14, it is merely extracted from the seat 120, the traction force exerted by the user being sufficient for the tangs, by virtue of the preferential fracture line, to withdraw from the heating device to enable it to be extracted from the hollow body 12.

Claims

1. A fuel filter provided with a heater device (14) and comprising an outer casing (2), the interior volume of which is separated by a filtering baffle (7) into two separate chambers (10, 11) to which a fuel inlet conduit (3) and a fuel outlet conduit (4) are connected respectively, characterised in that with the chamber (10) to which the fuel inlet conduit (4) is connected there being associated a hollow body (12) which opens on the outside of the filter casing, and defines a seat (120) for receiving the heating device (14).

2. A filter as claimed in claim 1 , characterised by comprising retention means (15) arranged to retain said heating device (14) within said seat (120) of the hollow body (12).

3. A filter as claimed in claim 2, characterised in that said retention means (15) are arranged to removably associate said device (14) with said hollow body (12).

4. A filter as claimed in claim 2, characterised in that the retention means are partly associated with the filter casing (2) and partly associated with the heating device.

5. A filter as claimed in claim 4, characterised by comprising at least one movable element (18) collaborating with the retention means (15) to maintain said heating device (14) associated with said filter (1).

6. A filter as claimed in claim 3, characterised in that the movable element is a pin to be inserted into a matching seat, a portion of which is associated with that part of the retention means associated with the heating device and the other portion with the retention means associated with the filter.

7. A filter as claimed in claims 4 and 5, characterised in that the retention means associated with the filter comprise an annular portion (13) which branches from the upper surface of the filter casing (2) an d presents two opposing slots (16) defining a portion of a seat or receiving said movable element, the other portion of the seat being provided in an annular shoulder (17) present on the outer surface of said heating device.

8. A filter as claimed in claim 7, characterised in that the movable element is a fork-shaped spring (7) to be inserted into said receiving seat defined by the retention means.

9. A filter as claimed in claim 8, characterised in that said fork-shaped spring (7) presents two opposing arcuate portions (19).

10. A filter as claimed in claim 5, characterised in that the movable element is a screw to be inserted into a matching seat, a portion of which is associated with that part of the retention means associated with the filter and the other portion with the retention means associated with the heating device (14).

11. A filter as claimed in claim 4, characterised in that said retention means (15) comprise matching threaded portions.

12. A filter as claimed in claim 4, characterised in that said retention means associated with the filter comprise an annular portion (13) of said hollow body (2) that branches from the upper surface of said casing (2) and presents at least one slot (16).

13. A filter as claimed in claim 4, characterised in that said retention means associated with the heating device comprise at least one tooth- shaped tang (22).

14. A filter as claimed in claims 12 and 13, characterised in that said at least one tang is able to be received in said at least one slot to retain said heating device within said seat (120) of the hollow body (120.

15. A filter as claimed in claim 13, characterised in that said at least one tang is associated with said heating device by means of a preferential fracture line which is flexible in one direction and fragile in the opposite direction.