FR2535844A1 - Improvement to level-checking devices, particularly for automobile petrol tanks - Google Patents

Abstract

The device consists of a float 30 moving inside a settling pipe 20 immersed in the liquid 12 in the tank, with a pipe 40 leading to the atmosphere. To prevent the liquid rising inside the pipe 40, and particularly to avoid any accumulation of liquid in a bend 42 in the pipe, a pellet 50 preferably made of a sintered material forms a static valve which allows air and vapour to pass through it but prevents the passage of any liquid.

Description

 The present invention relates to a device for controlling the level of a liquid in a tank, in particular an automobile fuel tank.

 This type of tank has in fact an often complex shape to allow it to be housed inside the vehicle without encroaching on the useful loading volume thereof.

 Furthermore, the level detectors generally used comprise a float with movable linear displacement inside a tranquilizer tube immersed in the liquid of the reservoir.

Due to the complex shape of the tank, it generally happens that the movement of the float is limited upwards to a position corresponding to a level below the maximum filling level of the tank. It is then necessary to close the tranquilizer tube at its upper part and to provide a venting tube, one of the ends of which opens out at a location situated at a level higher than the maximum filling level of the tank and whose l the other end is connected to the upper part of the tranquilizer tube, above the float, thus avoiding the formation of an air pocket in the upper part of the tranquilizer tube which would prevent the float from moving freely following variations the fuel level in the tank
The disadvantage of this arrangement lies in the risk of a liquid reserve being formed in a bend in the vent pipe, in the manner of a siphon, which would be consecutive to a rise of liquid in this tubing, when the general level of the liquid is higher than the level at which the upper part of the tranquilizer tube is located.

In this case, the venting is no longer ensured, producing an incorrect gauging of the tank by hampering the free movement of the float.

 To remedy this drawback, the invention proposes closing the orifice located at the top of the tranquilizer tube, and communicating with the venting tube, by a static valve allowing the gases to pass but not letting the liquids: it is thus forbidden the ascent of fuel in the manifold and the accumulation of fuel in an elbow thereof which would interrupt the venting.

 This static valve is preferably a pellet of sintered material.

 Other characteristics and advantages of the invention will appear on reading the detailed description below, made with reference to the appended figure, which represents a sectional view of the device of the invention, placed in an automobile tank. .

 In this figure, the tank 10 has been filled, by a filling orifice 11, with fuel 12: the level of the latter varies between a minimum low level No and a maximum high level N1.

 The level transmitter consists of a tranquilizer tube 20, the lower part 21 of which dips into the liquid, and containing a float 30 capable of moving between a lower position 31 and an upper position 32. The detected level N2 corresponding to this position higher is, due to the external conformation of the tank, lower than the maximum filling level N1.

 The upper part 22 of the tube 20, located at a level N3, is closed and has an orifice 23 connected, via a tube 40, to an air intake 41 placed at a level N4 higher than that of the level maximum filling N1.

 The tubing 40 optionally comprises elbow-shaped parts 42 in which, in the prior art, an accumulation of liquid could occur obstructing the passage of air.

 To overcome this drawback, the device of the invention comprises a pellet 50, closing I1 orifice 23 to form a static valve preventing the ascent of liquid from the reservoir to the tubing.

This pellet is, however, permeable to air and vapors, in order to ensure the balance of pressures between the atmosphere and the air pocket 23 situated between the float and the top of the tube 20.

 The material of this pellet is preferably an agglomerate of bronze-brass and compressed metal fragments. Such tablets are for example sold by the company METAFRAM. In addition to its role as a sealing means, this pellet advantageously allows a slight mechanical damping of the displacements of the float, due to the pressure drop occurring during the passage of gases through this pellet, in a direction or in the other. This damping ensures a better reading of the average level of the tank during sudden instantaneous variations of the level at. inside of it.

Claims (3)

 1. Device for controlling the level of a liquid (12) in a tank (10), in particular an automobile fuel tank, this level being able to vary, depending on the filling of the tank, between a high level (N1) and a low level (No),  this device comprising a float (30) with linear displacement mobile within a tranquilizer tube (20) immersed in the liquid of the reservoir,  the movement of the float being limited upwards to a position (32) corresponding to a level (N2) lower than the high level (N1) of the tank,  the upper part (22) of the tranquilizer tube being closed and provided with an orifice (23) connected to an air intake opening at a location (41) located at a level (N4) higher than the high level (N1) of the tank ,  characterized in that this orifice is closed by a static valve (50) allowing the gases to pass but not letting the liquids pass.  2. Device according to claim 1, characterized in that the static valve is a pellet of sintered material.  3. Device according to claim 2, characterized in that the material of the pellet is an agglomerate of bronze-brass and compressed metal fragments.