Safety valve for a venting line in a liquid container

The present invention relates to a safety valve for last circuit the air of a liquid tank, particularly a fuel tank may equipping a motor vehicle.

liquid tanks, in particular fuel tanks for motor vehicles, are today generally have, among others, a to the venting circuit. This circuit allows the introduction of air into the reservoir cases of depression (especially to compensate for the volume of liquid consumed) or evacuation of gases contained in the tank in case of overpressure (Especially when heated). This circuit also allows the pipeline and the possible filtering the gases to be discharged into the atmosphere, to meet environmental requirements becoming more stringent in this regard.

The vent circuit comprises in known manner a safety valve preventing as much as possible the liquid outlet from the reservoir in the event reversal or excessive inclination of the tank. This safety valve must offer a quick and safe response when its intervention conditions occur but with minimal sensitivity to abnormal phenomena such that in particular the very high flow rates, the overpressure in the reservoir or waves of low amplitude.

Many safety valves implement a float featuring an upper needle closing an access port between the reservoir and the air conditioning circuit. These elements allow not only meet all the above requirements.

It is known to add to them one or more elastic means of calibration, in special springs, but such sets do not meet so satisfying the requirements, particularly in that they fail to prevent a risk of adverse filling in severe conditions that could cause the Out of the balance of forces involved, for example in case of high overpressure in the tank.

It is also known, such as US Patent 3,765,435 to associate with a ball float being movable on an inclined plane pierced more holes and allowing in principle cause the float to the top and to close by means of a needle an upper opening of connection between the tank and the vent circuit if the tank tilt. Such system remains very sensitive to abnormal phenomena such as above.

The invention therefore aims to provide a safety valve for the circuit for venting a liquid tank preventing the liquid and drive with a minimum sensitivity to abnormal phenomena such as above.

Provided for this purpose a safety valve for last circuit like a liquid container preventing liquid entrainment, including a chamber which opens out inside the tank under the upper wall thereof, and whose upper portion is connected via an orifice to the last circuit air, comprising:<sl><li>a) a needle can be closed, in the high position, the hole in the head of valve;</li><li>b) a float associated with the needle and slidable vertically inside of the enclosure;</li><li>c) means for supporting the float and moving said float upwardly in case of inclination of the enclosure,</li></sl>wherein a shaft extends the lower part of the enclosure inside the tank under the means for supporting and float movement.

The safety valve is for the venting circuit of a tank 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 container may be intended for any use, especially in equipping a vehicle and more especially to equip a vehicle automobile.

The enclosure may have any shape, often internally adapted the sliding of the float. Most often, it is at this section of effect constant internal, at least in the part where the float must be movable. It is in particular at least in this section, internally cylindrical.

The outer shape of the float is obviously adapted to the inside of the space where it should be able to slide. In particular, it is externally cylindrical.

The float is associated with the needle any conventional manner. Of It is preferably integral with the needle. The float and the needle can be products in one piece or be produced separately and assembled. The needle can advantageously be equipped with a seal, by example of an elastomer seal membrame, favoring the sealing of the valve in closed position.

The orifice in the head of the valve makes it possible, when it is closed, the closure the valve. This port may also or alternatively be fitted with an O sealing, for example of a type of flat sealing elastomeric membrane.

The barrel extends the lower part of the enclosure inside the tank under the support means and float movement. It helps to channel fuel flow and obtain the necessary sensitivity to the functioning of valve. It protects the moving parts of the valve, in particular the float of essentially lateral waves of large amplitude that could the destabilize, and delay the closure of the valve and cause the drive to the liquid in the venting circuit. The valve is thus rendered insensitive to this problem and its functioning improved significantly.

The height of the barrel may be adapted case by case according to the amplitude of the abnormal phenomena to which we want to make the valve insensitive. we will obviously also account for the sizing of the precise position of valve in the reservoir and the effects that can induce potential close other elements such as for example a wall of the tank.

The safety valve allows venting of a liquid tank of the as described above. He did not, as such, serves to prevent the overfilling the tank. This function must, where appropriate, be filled by an independent device or by additional resources that would be associated with the valve. The characteristics of the valve, in particular the height of the barrel, are not dictated by the function of prohibiting overfilling.

Float means for supporting and moving said float when speaker's inclination can be of any known type. Advantageously, they comprise dense material ball being movable by gravity into a perforated truncated cup. By perforated it is meant that a plurality of openings are formed in the cup which permit liquid passage through the cup. In particular, the cup includes a frustoconical central orifice.

In case of inclination of the tank, the ball moves in the cup frustoconical, causes the float upward and causes the shutter by the the needle valve head hole before the level rises liquid in the valve avoiding completely the passage of liquid in the to the venting circuit.

Rollover Tank, dense material of the ball grows also the float to the valve closing position and maintained by gravity in this position.

In case of rise of the liquid level in the tank, this liquid enters in the valve by the lower part, through the openings of the cup frustoconical, causes the float upwards and also causes the shutter by the needle of the hole in the valve head.

In a preferred embodiment, the enclosure comprises in its part upper one or more lateral apertures allowing the passage of gas. More preferably, the enclosure comprises in its upper part several lateral openings allowing the passage of gas. Advantageously, the side openings are sized small dimensions to prevent the passing significant liquid flow rates, in particular by rolling. These openings may for example be made of a circuit provided with one or more baffles or labyrinth. In particular, these openings are section elongated rectangular. Advantageously, these openings are at least of 2, yet more preferably at least 4. Preferably, their number does not exceed 8. The assembly of these openings is preferably a total cross section of passage of at least 35 mm², More preferably of at least 45 mm². Good results have been obtained when the whole of these apertures represents a total passage section not exceeding 100 mm².

A gas is especially meant to be outdoor air introduced into the reservoir or the gas mixtures contained in the tank and whose evacuation must be made possible. In the case of a tank fuel, these gas mixtures consist essentially of air and fuel vapor.

By positioning in the upper part of the enclosure openings allowing the passage of gas is significantly reduced the impact any of these openings in the level of liquid and its movements, thereby making the air even in critical situations.

Advantageously, the float sliding within the vessel interior is formed by an adjusted guide. Thus, the float can hardly be move in a direction other than the vertical direction. This adjusted guide may in particular be performed by suitably dimensioning the two radial parts in contact and / or by a set of longitudinal ribs on the float and / or on the enclosure.

This embodiment improves the operation of the valve in that, by this adjusted guidance, it appears when the liquid level rises in the enclosure, a piston effect generated by the dynamic pressure of fluid and which promotes movement of the float upwards. On the contrary, when the liquid goes down, a suction effect also promotes the training of the float into position low.

Preferably, when the needle is in the high position and closes the orifice, it defines in the upper part of the enclosure an enclosed volume. In valve closing position, closed gas-filled volume provides the advantage a buffer effect preventing the liquid to reach near the vent opening and fortiori to leave the reservoir.

In a particular embodiment, the shaft may be beveled. Of this , it can be optionally selectively protect the valve against the fluid flows from a particular direction.

The components of the valve may be made of any material. Of Preferably, they are made thermoplastic base material. In this case, it should obviously choose the material or materials such that they resist operating requirements. The materials chosen must in particular be obviously inert vis-a-vis liquids with which they are caused to be in contact, especially vis-à-vis fuels.

The mode and valve attachment location on the tank can be chosen from any conventional manner adapted to the specific conditions. Of Preferably, the valve is assembled directly on the upper wall of the tank.

The invention also relates to a container comprising a valve as defined above.

The invention is illustrated in a nonlimiting way by the following figures:<ul><li>1 shows a safety valve according to the invention in open position;</li><li>2 shows the same valve in the closed position.</li></ul>

According to Figure 1, the safety valve (1) for the air conditioning circuit (2) is fixed on the upper wall of the tank (3). The safety valve (1) comprises an enclosure (4) which opens out inside the tank. In the enclosure (4), a float (5), shown in the lowered position, can slide vertically for seal via a needle (6) (produced in one piece with the float) in the high position, an orifice (7) located in the valve head. To to improve the sealing of the closure, the orifice (7) is provided with a seal elastomer (8). The float (5) can be moved by rising liquid in the valve through the perforated frustoconical cup (9) or, if of inclination of the tank, by movement of a ball (10) of dense material in the truncated cup (9). The enclosure (4) is extended in its lower part by a shaft (11). It comprises in its upper part 4 side openings (12) of small dimensions, allowing the passage of gas but preventing the passing significant liquid flow rates.

2 illustrates the float (5) in the upper position when the needle (6) closes the orifice (7). A closed volume (13) filled with gas is then defined in the upper part of the enclosure.