GB2187846A - A float of improved type for a fuel level sensing device of a vehicle tank - Google Patents

Abstract

A float (1) comprising a tubular body with an axial through-hole 2 is slidable along a vertical guide (3) and has on its upper end face an electrical contact element (4). This latter is essentially constituted by a flat annular plate (7) from the inner edge of which extends a group of three tongues (8) each of which has a folded free end constituting a contact shoe (5) slidable, in use, on helical resistor winding supported by the said guide (3). Internal projections (13) in the hole (2) guide the float and restrain it when the vehicle jolts. Lugs (12) on the contact plate (7) retain the bottom turn of an electrical contact spring (6). <IMAGE>

Description

SPECIFICATION A float of improved type for a fuel level sensing device of a vehicle tank The present invention relates to a float of improved type for fuel level sensor device of a vehicle tank.

More particularly, the present invention relates to a float having a tubular structure and supporting conductive shoes which slide, in use, on a resistive wire wound on a cylindrical guide. In known floats of the above-specified type there are in general two shoes mounted in facing positions within the float itself, which is therefore provided with suitable housing recesses conveniently constituted by longitudinal rather deep slots.

As in known, for the purpose of obtaining a good insensitivity to external mechanical stresses (for example jerks of the vehicle) it is appropriate that the useful volume of float be as high as possible. However, the reduced space (in a radial sense) available for the float does not allow this latter to be made with a very high volume. Moreover, the necessity of having available electrical contacts in the manner explained above involves, as already said, having to remove a significant percentage of the material and this constitutes a practically insuperable disadvantage in floats with the structure of the above-specified type.

The object of the present invention is that of providing a float of improved type for a device for sensing the level of fuel in a vehicle tank, which allows the disadvantages of floats of the known type specified above to be overcome.

According to the present invention there is provided a float for a device for sensing the level of fuel in a vehicle tank, characterised by the fact that it comprises: - a tubular body having an axial hole slidable, in use, along a guide by the effect of the hydrostatic thrust exerted by the fuel contained in the said tank; and - an electrical contact element supported by a face of the said float and essentially comprising a plate from which at least one tongue extends, towards the hole in the said float, the end of which tongue is bent over to constitute a contact shoe slidable, in use, on the surface of the said guide.

For a better understanding of the present invention a preferred embodiment is now de scribed purely by way of non-limitative example and with reference to the attached drawings, in which: Figure 1 is a plan view of a float formed according to the principles of the present invention; Figure 2 is a section taken on the line ll-ll of Fig. 1; and Figure 3 is a perspective view, on an en larged scale of a contact element carried by the float of Fig. 1.

As illustrated in Figs, 1 and 2, a float which can be installed within a fuel level sensor device (not illustrated) in a vehicle tank is generally indicated with the reference numeral 1.

The body of the float has a tubular structure with an axial through hole 2 and is slidable, in use, along a vertical guide 3 illustrated in broken outline. On the upper face of the float 1 is positioned a contact element 4 (Fig. 3) provided with contact shoes 5 which slide, in use, on a resistive wire (not illustrated) wound helically around the guide 3. In use, the contact element 4 is connected to a conductive wire terminal 6 (illustrated in broken outline in Fig. 2) wound helically and having an opposite terminal conveniently connected (in a manner not illustrated) to an electrical connector of the said device.

With particular reference to Figs. 2 and 3, the contact element 4 comprises an annular plate 7 along the inner edge of which are formed three slots to form three tongues 8 which are then folded orthogonally and downwardly. The said contact shoes 5 are constituted by the ends of the tongues 8 folded orthogonally in such a way as to lie in a radial position with respect to the axis of the guide 3 and disposed at 120 with respect to one another.

On the upper face of the float 1 are formed three narrow notches 9 each of which opens towards the hole 2 and is able to house a respective tongue 8. The correct positioning of the element 4 on the upper face of the float 1 is obtained by means of three pins 10 extending upwardly from the body of the float 1; each pin engages a respective through hole 11 formed in the plate 7 and is riveted onto the plate itself.

Along the perimetral edge of theplate 7 are formed three pairs of radial notches disposed at 120 with respect to one another. Each pair of notches defines a radial projection 12 which is folded substantially in the form of an inverted V. In use the three projections 12 retain a first turn of the conductive wire 6 against the surface of the float 1, thus obtaining the electrical contact between this latter and the element 4.

As illustrated in Figs. 1 and 2, in correspondence with the hole 2 the float body 1 has a set of three equidistant longitudinal projections delimited towards the interior by a cylindrical surface the diameter of which is slightly greater than the diameter of the guide 3. The purpose of the projections 13 is that of correctly guiding the float 1 with respect to the guide 3 preventing radial stresses, caused for example by a jerk of the vehicle, from becoming transferred onto the contact shoes 5 of the element 4 damaging them. Each of these contact shoes 5 lies between two adjacent projections 13 in such a way as to rest on the guide 3 exerting on it a slight contact pressure deriving from a predetermined deformation of the associated blade 8.Moreover, it is to be observed that each projection 13 extends above the face on which the element 4 rests, for the purpose of acting, in use, as a spacer element between the body of the float 1 and a cover (not illustrated) of the sensor device in the case when the tank is full and the float 1 is pressed by the fuel towards the highest point the device. In this way there remains a certain distance between the upper face of the float 1 and the opposite surface of the said cover and this allows the coil defined by the conductive wire 6 to be collected without being squashed and/or deformed.

From a study of the characteristics of the float formed according to the present invention the advantages which it allows to be obtained are evident. First of all, the almost entirely flat conformation of the contact element 4 and the positioning of this element 4 in correspondence with the upper face of the float 1 allows a large useful volume to be obtained. In fact the only removals of material which take place in the float 1 are those relating to the production of the notches 9, which since they only have to house the tongues 8 are of small extent. It is therefore possible to provide a float which, for the same useful volume with respect to current floats, has a smaller diameter. This therefore allows sensor devices of smaller radial dimensions to be formed and therefore corresponding housing seats of reduced extent in the tank in which they are installed to be obtained.

Finally, it is clear that the float 1 described and illustrated here can be modified and varied without by this departing from the present invention.

Claims (9)

1. A float of improved type for a device for sensing the level of fuel in a vehicle tank, characterised by the fact that it comprises: - a tubular body having an axial hole slidable, in use, along a guide by the effect of the hydrostatic thrust exerted by the fuel contained in the tank; and - an electrical contact element supported by a face of the said float and essentially comprising a flat plate from which at least one tongue extends, towards the axial hole of the said float the folded end of which tongue constitutes a contact shoe slidable, in use, along the surface of the said guide.

2. A float according to Claim 1, characterised by the fact that the said tongue is disposed in a plane orthogonal to the said plate and is housed in a notch formed on the upper face of the said body opening into said hole; the said shoe being disposed on a radial plane with respect to the axis of the said hole.

3. A float according to Claim 2, characterised by the fact that it includes three tongues disposed in respective planes parallel to planes tangent to the said hole in such a way that the said contact shoes are located at 120 with respect to one another; the said tongues being defined by respective slots formed along the inner edge of the said plate.

4. A float according to Claim 3, characterised by the fact that along the said hole there are formed three longitudinal projections extending radially to define a correct radial position of the body of the said float with respect to the said guide.

5. A float according to Claim 4, characterised by the fact that the said projections have respective upper ends which extend beyond the upper face of the said body.

6. A float according to any preceding Claim, characterised by the fact that from the said outer peripheral edge of the said plate extend three projections folded substantially as an inverted V and engageable, in use, with a turn of a suitable helically wound conductive wire operable to connect the said contact element with suitable measuring means.

7. A float according to at least one of the preceding Claims, characterised by the fact that pins riveted in respective through holes in the said plate extend upwardly from the said upper face of the said body.

8. A vehicle tank fuel level sensor device characterised by the fact that it includes a float as claimed in any of Claims from 1 to 7,

9. A float of improved type for a vehicle tankful level sensor device substantially as described with reference to the attached drawings.