Method and valve for venting a fuel tank

Abstract

A valve including: a chamber configured to extend at least partly into a tank and to be connected via an upper venting aperture to a venting circuit; and a shut-off point defining a single maximum filling level within the tank, located away from the chamber, the shut-off point being in fluid communication with the chamber via a conduit, wherein the conduit includes a venting tube.

Claims

1. A fuel tank comprising: a first compartment and a second compartment; a bridge between the compartments; and a valve comprising: a chamber configured to extend at least partly into a tank and configured to be connected via an upper venting aperture to a venting circuit; and a shut-off point defining a single maximum filling level within the tank, located away from the chamber, the shut-off point being in fluid communication with the chamber, wherein the shut-off point is in fluid communication with the chamber via a conduit, wherein the conduit comprises a venting tube, and wherein one end of the conduit is located below a top of the bridge.

2. The tank according to claim 1, wherein plastic is injection molded into a shape of the chamber.

3. The fuel tank according to claim 1, wherein the venting tube is a flexible tube.

4. The fuel tank according to claim 3, wherein the flexible tube is attached to a nipple provided on the valve.

5. The fuel tank according to claim 4, wherein the nipple is made in one piece with the chamber.

6. The fuel tank according to claim 1, further comprising at least one semi-permeable membrane mounted inside the chamber to extend between the conduit and the upper venting aperture, the semi-permeable membrane configured to: allow liquid vapor within the tank to flow from the conduit to the upper venting aperture; and prevent liquid in the tank to flow from the conduit to the upper venting aperture.

Description

(1) These and other features and advantages of embodiments of the present invention will now be described in more detail with reference to the accompanying drawings, in which:

(2) FIG. 1 schematically illustrates a fuel tank equipped with a valve according to an embodiment of the present invention, arranged in an upper protrusion provided in one compartment of a saddle tank;

(3) FIG. 2 schematically illustrates a fuel tank equipped with a valve according to an embodiment of the present invention, arranged above the bridge of a saddle tank;

(4) FIG. 3 schematically illustrates a valve according to an embodiment of the present invention in more detail; and

(5) FIG. 4 schematically illustrates a fuel tank equipped with a valve according to another embodiment of the present invention, configured for liquid/vapor separation.

(6) The valve according to the present invention is equipped with a shut-off point defining a single maximum filling level within the tank, located away from the valve chamber. The shut-off point is in fluid communication with the chamber. The valve thus provides means for monitoring the fuel level, which confer on it the ability to impose a predetermined filling level. Refueling of the tank is possible until the shut-off level is not reached. When the shut-off level is reached, the valve takes a closed position.

(7) By the term closed is meant the fact that the communication between the inner volume of the tank and the upper venting aperture is obstructed/no longer active so that the tank can no longer be vented by the valve.

(8) The valve is intended for the venting circuit of a tank that may contain any liquid. In particular, the liquid may be a fuel, a brake fluid or a lubricant. More particularly, the liquid is a fuel. The tank may be intended for any use, especially for equipping a vehicle and even more especially for equipping a motor vehicle.

(9) The valve according to the invention comprises a chamber of any shape, usually of constant internal cross section. It preferably has a substantially cylindrical internal cross section. In an advantageous embodiment, it is provided with a cover that is pierced by an orifice preferably intended to be sealed by a float or any other sealing device preferably providing a ROV function as explained above.

(10) For a given tank having a given maximum filling volume, it is possible to advantageously set the shut-off level of the valve according to the invention below the level of the bridge in order to make a new filling volume version requirement out of the same tank. For example, considering a tank with a maximum filling volume of 85 litres (with fill level above the level of the bridge), it is possible to reduce this maximum filling volume to 78 litres (with fill level below the level of the bridge), by setting appropriately the predetermined filling level below the top of the bridge.

(11) In a preferred embodiment, the valve is mounted within the tank such that its chamber extends above the bridge. The on-board diagnostic (OBD) for detecting leaks in the fuel system requires the valve (that makes the tank to communicate with the canister) to be opened. The advantage of the configuration where the chamber of the valve extends above the bridge is that the valve can remain open at an excessively high angle of inclination of the tank, provided that the maximum filling level of the tank is not reached.

(12) The shut-off point may be constituted by a conduit having one extremity (also called hereafter inlet) which opens into the tank at a level which corresponds to the predetermined filling level, and another extremity (also called hereafter outlet) which opens into the chamber. Throughout the description, the conduit will also be referred to as a venting tube. The valve is a mono-port valve, i.e. a valve equipped with one gas inlet (i.e. the extremity of the conduit that opens into the tank).

(13) The gas inlet is located away from the chamber of the valve, so as to extend at the desired level in the tank. The functional dimensions of the conduit are its inner section (which will set a pressure drop between the two extremity of the tubes, and the velocity of the fluids inside the tubes) and the height of its inlets (which will set the predetermined fill level). Such architecture is compact and easy to implement. The term gas is understood in particular to mean the external air that has to be introduced into the tank or the gas mixtures contained in the tank, the removal of which has to be possible. In the case of a fuel tank, these gas mixtures comprise essentially air, and fuel vapour.

(14) Advantageously, the valve comprises a base designed for supporting the venting tube and for connecting it to the chamber of the valve. The base according to the invention may have any shape. It preferably has a substantially cylindrical internal cross section. Preferably, this base is a cup shape part, with a flat bottom. Advantageously, the base is designed to be clipped onto the chamber. In this manner, an existing FLVV may be used in conjunction with a base to form a valve according to the present invention.

(15) In another embodiment, the base comprises a threaded portion designed to be screwed on a corresponding threaded portion of the chamber. The venting tube is placed in communication (i.e. connected) with the chamber of the valve via a common aperture (i.e. the lower aperture of the chamber which corresponds to the upper aperture in the cup shaped base).

(16) In consequence, the flow of gas through this common aperture is possible until the lower extremity (i.e. the extremity that opened into a compartment) of the venting tube is closed by the liquid.

(17) Advantageously, the base and a nipple for receiving the venting tubes forms one block. This architecture is compact and facilitates mounting/dismounting operations. In another particular embodiment, this one block also includes the chamber.

(18) In order to work properly, the valve must be entirely tight from the inlet to the outlet. Otherwise there will be overfilling.

(19) In a preferred embodiment, the inlet section of the tubes extends horizontally (with respect to the bottom of the tank) in order to have a clear and precise shut-off.

(20) The tube is preferably flexible, such that it can be arranged in any desired position without difficulty. For example, the tube can have internal section comprised between 200 mm.sup.2 and 250 mm.sup.2.

(21) In a preferred embodiment, the base and the nipple for attaching the venting tube are made by injection moulding a plastic.

(22) In a preferred embodiment, the venting tube is made of plastic. The term plastic is understood to mean any polymeric synthetic material, whether thermoplastic or thermosetting, which is in the solid state under ambient conditions, as well as blends of at least two of these materials.

(23) The main function of the valve according to the invention is the fill-limit function, but advantageously, the valve according to the invention can include a roll-over function, a venting function and a liquid discrimination function. These functions can be implemented by using a device comprising a float within a housing with a spring or ball below it in order to make the float closing before 90 rotation. On the top of the float there is a seal (preferably elastomeric or plastic) that seals the vent orifice in the top part of the housing when the float is in shut position.

(24) FIGS. 1 and 2 depict a sectional schematic view of a saddle fuel tank 100 having a tank shell 101. The tank shell 101 comprises a primary compartment 102, a secondary compartment 103 and a dome 400. The primary compartment 102 and the secondary compartment 103 are connected together in a communicating manner by means of a bridge 104. The bridge provides an exterior concavity 105 which is intended to provide accommodation for drive and/or exhaust components of the vehicle to pass freely underneath.

(25) A valve 200 is disposed within the fuel tank 100. Preferably, the valve 200 is positioned at the centre of the tank (FIG. 2), such that it extends above the bridge 104.

(26) FIG. 3 shows a valve 200 according to an embodiment of the present invention. The valve 200 comprises a chamber 201. The chamber 201 of the illustrated valve is provided with a cover 202, which may either be moulded as one part with said chamber or it may form a separate part joined to the latter by any known means (mechanical fastening with a seal; welding etc.). This cover 202 is advantageously connected to a venting circuit via an aperture 203. For example, the aperture 203 is connected through a conduit to the inlet of a storage canister (not illustrated). The storage canister has an outlet conduit adapted for connection to the air inlet of an engine.

(27) The base 205 is fixed to the chamber by any known means (clips, screws . . . ). The base 205 is advantageously connected to (i.e. in communication with) the chamber 201 via an aperture. One extremity of the venting tube opens onto the base 205 and another extremity of the venting tube opens onto the volume of the tank. The open extremity corresponds to the shut-off level or the predetermined filling level L1. In a preferred embodiment, the base 205 and the venting tube 206 are made of plastic.

(28) As shown in FIGS. 1 and 2, the valve 200 according to a preferred embodiment of the present invention is designed to respond by taking a fully closed position when a fuel level in the tank 100 is equal to or higher than the predetermined filling level L1.

(29) With reference to FIG. 2, the predetermined filling level L1 is lower than the physical maximum filling level of the left compartment 103, which would correspond to the level of the top of the bridge 104.

(30) As will be described below, the valve 200 according to a preferred embodiment of the present invention comprises means for providing both the ROV function and the FLVV function.

(31) Advantageously, the valve according to the invention further comprises means which confer on it the ability to act as a pressure liquid vapour separator.

(32) In the embodiment shown in FIG. 4, the valve 700 is disposed within the fuel tank 710. Preferably, the valve 700 is positioned at the centre of the tank, such that it extends above the bridge 720. The valve 700 comprises a chamber 701. The chamber 701 of the valve is provided with a cover 702. This cover 702 is advantageously connected to a venting circuit via an aperture 703. In the example of FIG. 4, the aperture 703 is connected through a conduit to the inlet of a storage canister 730.

(33) In this example, the valve 700 further comprises a refueling vent block 704. The refueling vent block 704 comprises a base 705 designed to be mounted at the bottom of the chamber 701 and a venting tube 706 in charge of monitoring a level of fuel in a compartment of the tank.

(34) Advantageously, the valve 700 further comprises a semi-permeable membrane 708 mounted inside the chamber 701 such that it extends between the first 706 venting tube and the aperture 703. The membrane 708 is configured such that: it allows liquid vapour within the tank to flow from the conduit to the aperture; and it prevents liquid in the tank to flow from the conduit to the aperture.

(35) Thus, the membrane 708 allows only fuel vapour to be transferred to the canister 730 so as to avoid contamination and pass through to the atmosphere.

(36) Advantageously, the valve further comprises a small bleed orifice. For example, this bleed orifice is bored on the venting tube. The bleed orifice is used to minimize pressure spike at valve shut-off, in order to mitigate any fuel rising rapidly up the fill pipe and exiting the pipe as a result. This bleed orifice could be tuned to optimize refueling performance. The valve can comprise other bleed orifices placed at strategic locations, such as in an optional refueling vent block.

(37) While the invention has been described hereinabove with reference to specific embodiments, this is done to clarify and not to limit the invention, the scope of which is to be determined on the basis of the accompanying claims.