FR2629588A1 - DEVICE FOR SENSING THE FUEL LEVEL IN A VEHICLE TANK - Google Patents

Abstract

Device 1 for sensor of the fuel level in a liquid level tank of a vehicle of the type comprising a hollow body 2 inside which a float 3 is movable, the position of which depends on the level of fuel in the tank. The device 1 comprises means 21, 22 for measuring the position of the minimum fuel level and therefore the position of the float 3 closest to a bottom wall 6 of the hollow body 2. These measuring means comprise at least one magnet 22 carried by float 3 and a magnetically actuated switch 21 (capable of being inserted into an electrical supply circuit of a light source for signaling the minimum fuel level) installed near the bottom wall 6 of the hollow body 2, and operable by said magnet 22.

Description

Fuel level sensor in a vehicle tank

  The invention relates to a device for measuring the fuel level in a vehicle tank. More; / in particular, the present invention relates to a sensor device comprising a hollow body, one of the bottom walls of which has a through hole through which the fuel flows inside the hollow body itself, o it acts on a mobile float along an i-vertical guide. The latter consists of a rod carrying a: -resistant wire on which acts a cursor carried by said float so as to define, overall, a variable resistance - 15 as a function of the fuel level

* in the tank.

  , -In operation, when the fuel level is:! close to the minimum, the float arrives near the * bottom wall of the hollow body. At this time the light indication of the minimum fuel level and therefore - - the indication that there is only the reserve in the fuel tank, is determined by the - electrical contact which s between the cursor carried by the float and a conductive spring carried by the bottom wall of the hollow body and inserted into the circuit

  power supply of a light source.

  - The main drawback of devices of the type -, - described above - resides in the fact that the spring is subject to progressive wear caused by the phenomenon - of electrolysis manifested by the presence of water in the fuel, especially in the fuel that powers the

Diesel engines.

  The object of the present invention is to provide a - fuel level sensor device which overcomes the above-mentioned drawback of the devices

of known type.

  The object mentioned above is achieved by the present invention, in that it relates to a device for sensing the level of fuel in a tank of a vehicle, of the type comprising: - a hollow body capable of being fixed to a pa - upper king of said tank, having a side wall and a bottom wall and, said fuel flowing inside thereof, in operation; - A float capable of translating inside said body, under the hydrostatic thrust exerted by said fuel; - first means for measuring the position taken by said float; and - second means for measuring the position of the minimum level of said fuel and therefore the position of said float closest to the bottom wall; said device being characterized in that said second means comprise at least one magnet carried by said float and a magnetically actuated switch (capable of controlling an electrical supply circuit of a light source for signaling the minimum level reached by said fuel in said tank) installed inside said body, near the bottom wall, and

actuable by said magnet.

  According to another characteristic of the invention, said float is capable of translating along a guide coaxial with said body and carried by said bottom wall; said switch being installed in a niche made inside said guide near

  the implantation thereof on said bottom wall.

  According to another characteristic of the invention, said guide is produced in two coaxial parts and connected to each other, said niche being produced in a first

  part of these, fixed to said bottom wall.

  According to another characteristic of the invention, two conductors are derived from said switch and cross-said guide to connect, in operation, for one to the reference electrical ground and, for the other, through said light source , at the positive pole of an electrical energy source, preferably the battery

of said vehicle.

  According to another characteristic of the invention, it comprises, near the side wall of said body, a tubular rod carried by said bottom wall and passing through said float; said switch being installed in a niche dug inside of it,

on the back wall.

  According to another characteristic of the invention, said rod is produced in two coaxial parts and connected to each other, said recess being produced in a first part thereof, fixed to said bottom wall. According to another characteristic of the invention, two conductors are derived from said switch and pass through said rod to connect, in operation, for one, to the reference electrical ground and, for the other, through said light source, to a positive pole of an electrical energy source, preferably the battery

of said vehicle.

  According to another characteristic of the invention, said switch is held in said niche by a layer

of adhesive material.

  According to another characteristic of the invention, said switch consists of two electrical contacts

magnetically actuated.

  According to another characteristic of the invention, said

  magnet is fixed on the upper face of said float.

  Various other features and benefits of

  device l.'invention emerge from the description

  detailed below. An embodiment of the invention

  is shown by way of nonlimiting example on the des-

  attached sins in which: FIG. 1 represents a view in elevation and in section of a device produced according to the principles of the present invention; Figure 2 is a plan view of a float of the device of Figure 1; Figure 3 is a partial view, in section and on a larger scale, of a lower part of a vertical rod of the device of Figure 1; and FIGS. 4 and 5 are views in elevation and partially in section of respective devices produced according to the principles of the present invention, but with embodiments different from that illustrated on

Figure 1.

  As shown in Figures 1,4 and 5, it is indicated as a whole by 1 a fuel level sensor device in a tank (not shown)

of a vehicle.

  The device 1 comprises a body 2 substantially

  cylindrical and hollow, inside which is

  mounted a movable float 6 along a cylindrical guide 4 coaxial with the body 2 and preferably made of plastic. The body 2 has a cylindrical side wall 5 and a bottom wall 6 to which the lower end of the guide 5 is fixed, in a known manner. The bottom wall 6 has a through hole (not shown) through which, in operation, the fuel flows inside the body 2, so as to exert on the float 3 a hydrostatic thrust and, * .. therefore, determine a position depending on the level reached by the fuel inside the tank. The position of the float 3 is measured in a known and precise manner, by means of a plurality of electrical contacts 10 carried by the float itself which rubs on the surface of the guide 4 carrying a resistant wire 12. These contacts 10 are located inside a hole 11 made in the float 3 and crossed by the guide 4. The wall of

  bottom 6 further carries, in a known manner, a filter 13.

  It is observed that inside the hollow body 2 and near the side wall 5, is installed a rod 14 supported by the bottom wall 6 and passing through the float 3 by means of a radial notch 15 produced in the latter . The device 1 also comprises a flange cover 17 capable of coupling to a

  upper wall (not shown) of said tank.

  According to the present invention, it is observed that the device comprises an actuating switch

magnetic 21.

  This switch 21 is installed near the bottom wall 6, and, in operation, is inserted into the electrical supply circuit of a light source (not shown) capable of indicating the minimum level reached by the fuel in the tank. The switch 21 is actuated when it is near a permanent magnet. As regards the representation of FIG. 2, two magnets 22 of reduced dimensions

  are installed on the upper face of the float 3.

  In a first embodiment of the present invention, shown in FIGS. 1 and 3, the switch 21 is installed inside the rod 14, near the implantation of the latter in the bottom wall 6 The rod 14 is produced in two coaxial parts 23 (in metallic and / or plastic material) and 24

(plastic).

  Part 23 is of reduced longitudinal dimension and is carried by the bottom wall 6, while part 24 is located in part 23 and extends to the cover 17. The switch 21 is installed in a recess 25 provided inside the part 23 and is held in this niche 25 by a layer 26 of adhesive material. Two electrical conductors 27 starting from the switch 21 are naturally provided with protective sheaths and pass through the entire rod 14, to be connected, in a manner not shown, for one to a contact connected to the mass and to a spring 31 and, for the other, to a contact connected, through said light source, to the positive pole of a source of electrical energy, for example the vehicle battery. In this embodiment, the magnets 22 are arranged near the hole 15 made in the float 3 and at

through the rod 4.

  According to a second embodiment of the present invention, represented in FIG. 4, the switch 21 is installed inside the guide 4, near the implantation of the latter in the bottom wall 6. In this In this case, the guide 4 is tubular and has a recess 32 in which the switch 21 is held by means of a layer 33 of adhesive material. The conductors 27 derived from the switch 26 pass through the entire guide 4 to connect, as already indicated, to the

  spring 31 and a light source.

  In FIG. 5, the guide 4 is produced, in a similar manner to the rod 14 shown in FIG. 1, in two coaxial parts designated by 34 and 35. In the part 34 which is carried by the bottom wall 6, the niche 32 in which the switch 21 is held by means of the layer 35, while the part 35 is located on the part 34 and is crossed by the

  conductors 27. In the solutions shown on the.

  Figures 4 and 5, the magnets 22 will naturally

arranged near hole 11.

  In operation, when the fuel inside the tank reaches the minimum level, the float 3 follows its level and therefore goes towards the bottom wall 6. The magnets 22 will consequently be located near the switch 21 which feels the magnetic field and, by closing a clean internal contact, determines the power supply to the light source. This indicates to the user that this minimum level is reached and thus the fact that the vehicle engine is powered by

reserve fuel.

  From the indications given above, the advantage that

  lets get the device looks obvious.

  In fact, the system used for supplying the light source indicating the minimum level of the fuel is not subject to wear in that the presence of water in the fuel has no influence on it. There is therefore no phenomenon of electrolysis. In addition, the solutions indicated here are simple to make and on the contrary make the construction less complex. of

device 1.

  Finally, it is clear that modifications and variants can be made to the device 1 described and illustrated here, without thereby leaving the protective field.

of the present invention.

  In particular, the switch 21 can be carried, still close to the bottom wall 6, by the internal surface of the hollow body 2. In this solution, a cut must be made along the side wall of the

  float 3, to allow axial translation thereof

  Ci and to carry the magnets 22. Finally, the switch 21 can be carried directly by the internal face of the

  bottom wall 6 or by a rim extending from it

  this. In the latter solution, the magnets 22 will have to

  be carried by the underside of the float 3.

Claims (10)

  1. Device for sensing the level of fuel in a tank of a vehicle, of the type comprising: - a hollow body (2) inside capable of being fixed to an upper wall of said tank, having a side wall (5) and a bottom wall (6) and, said fuel flowing inside thereof, in operation; - A float (3) capable of translating inside said body (2), under the hydrostatic thrust exerted by said fuel; - first measuring means (10,12) of the position taken by said float (3); and second means for measuring (10,12) the position of the minimum level of said fuel and therefore the position of said float (3) closest to the bottom wall (6); said device being characterized in that said second means comprise at least one magnet (22) carried by said float (3) and a switch (21) with magnetic actuation (capable of controlling a circuit for the electrical supply of a light source signaling the minimum level reached by said fuel in said tank) installed inside said body (2), near the bottom wall (6), and actuable by said magnet. (22).   2. Sensor device according to claim 1, characterized in that said float (3) is capable of performing a translation along a guide (4) coaxial with said body (2) and carried by said bottom wall (6 ); said switch (21) being installed in a niche (32) produced inside said guide (4) near the implantation thereof on said wall bottom (6).   3. Sensor device according to claim 2, characterized in that said guide (4) is made in two parts (34 and 35) coaxial and connected to each other, said niche (32) being made in a first part (34) of these (34,35), fixed to said bottom wall (6). 4. Sensor device according to claim 2 or 3, characterized in that two conductors (27-) are derived from said switch (21) and pass through said guide (4) to connect, in operation, for one, to the reference electrical ground (31) and, for the other, through said light source, to the positive pole of an electrical energy source, preferably the battery of said vehicle.   5. Sensor device according to claim 1, characterized by comprising, near the side wall (5) of said body (2), a tubular rod (14) carried by said bottom wall - (6) and passing through said float (3); said switch (21) being installed in a niche (25) dug inside of it (14), on the bottom wall (6).   6. Sensor device according to claim 3, characterized in that said rod (14) is made in two parts (23 and 24) coaxial and connected to each other, said niche (25) being made in a first part (23) of these (23,24), fixed to said wall of bottom (6).   7. Sensor device according to claim 5 or 6, characterized in that two conductors (27) are derived from said switch (21) and pass through said rod (14) to connect, in operation, for one, to ground electric reference (31) and, for the other, through said light source, to the positive pole of a source of electric energy, preferably the battery of said vehicle.   8. Sensor device according to any one of claims 2 to 7, characterized in that said switch (21) is held in said niche (32 or   ) with a layer of adhesive material (33 or 36).   9. Sensor device according to any one of claims 2 to 8, characterized in that said switch (21) consists of two contacts   electrically actuated.   10. Sensor device according to any one of claims 2 to 9, characterized in that said magnet (22) is fixed on the upper face of said float (3).