Fluid handling – Control by change of position or inertia of system – Vent opening or closing on tipping container
Reexamination Certificate
2001-07-10
2003-03-18
Hepperle, Stephen M. (Department: 3753)
Fluid handling
Control by change of position or inertia of system
Vent opening or closing on tipping container
C137S039000, C137S264000
Reexamination Certificate
active
06532983
ABSTRACT:
The present invention relates to a system for venting a liquid tank.
Liquid tanks, when they are likely to be moved along with the liquid that they contain, are generally fitted with a venting system which guarantees safety with respect to the environment when the tank is subjected to various influences: movements in all directions and of any amplitude, thermal stress, depression and overpressure.
This requirement is encountered in the case of fuel tanks, particularly when mounted on motor vehicles and when it is essential to prevent liquid fuel from getting out and to manage significant changes in the pressure and volume of the gas during filling and throughout the time of storage in the tank.
Solutions have been developed for addressing these problems, and implement safety valves immersed in the tank and the upper part of which passes through a wall thereof. These valves generally open onto a duct leading to a casing or canister containing a material capable of trapping liquid vapours present in the gases coming from the reservoir. However, it is not unheard of for systems of this type still to exhibit difficulties because, owing to the particular circumstances of use, such as abrupt movements or excessive inclination of the vehicle, liquid from the tank can nonetheless get past the safety valve barrier and find itself in the duct leading to the canister, or may even reach this canister and disrupt the free passage of vapours.
To remedy this accidental entrainment of liquid out of the tank, attempts have been made at retaining the liquid escaping through the duct leading to the canister by introducing into this duct a dead volume intended to act as a capacity in which the liquid can collect and allow the vapour to pass freely.
Moreover, when it is not possible to incorporate them into the safety valve itself, safety devices preventing the tank from being overfilled (OPDs) and for automatically shutting it off in the event of roll-over (“ROV” or roll-over-valve device) have also to be mounted on the tank or in its nearby surroundings. Many pipes therefore connect the valve, the OPD and the ROV device and the canister together. These pipes of the numerous connections they entail are often the source of tiny leaks which are unacceptable given the EURO 2000 drastic emissions reduction programme and targets. Nor is it unheard of for these many pipes to have low points and siphons in which small amounts of liquid build up and form a corresponding number of obstacles to the free passage of the gases.
British Patent Application GB-A-2 269 375 discloses the use of a capacity with liquid-tight walls incorporated into a fuel tank, in which capacity a safety valve (see FIG. 2) is housed. A calibrated opening 14 raised at the top of the capacity allows liquid to enter when the reservoir is too steeply inclined or moves too violently. A non-return valve 12 of the duck-bill type allows the capacity 11 to be drained when the liquid level has dropped.
In this system, there however remain problems associated with inadvertent closure of the valve and with the increase in pressure in the tank which may disrupt the correct running of the engine. Furthermore, when small droplets of liquid are entrained through the orifice 14, they may, because of their low weight, be entrained directly by the gaseous stream to the vent pipe 7 without dropping into the capacity 11. The OPD and ROV have therefore also to be connected to the valve by pipes external to the tank.
Moreover, this known system does not protect the reservoir against the effect of excessive depression either, in this case keeping the reservoir closed and not allowing it to be vented.
The invention sets out to overcome the disadvantages of the known venting systems by providing a system which avoids placing a capacity on the pipes external to the tank, allows the liquid held in the capacity to be drained if the level of liquid in the tank drops, meets the tightest environmental standards and causes neither overpressure nor depression inside the tank.
To this end, the invention relates to a system for venting a liquid tank comprising, on the one hand, a closed volume internal to the tank and equipped with a draining device which acts as a capacity intended to collect and hold any entrainment of liquid from the tank and, on the other hand, a float valve arranged in the tank, situated outside the volume of the capacity and connected to the latter by means of a duct of the air vent circuit, in which the valve comprises means for:
a) venting the tank, including when the latter is inclined with respect to the initial position for which it was designed,
b) preventing liquid from being ejected from the tank in the event that the latter becomes inclined or in the event that waves of liquid are produced within the tank,
c) automatically shutting off the tank in the event that the latter rolls over (“ROV” or “roll-over-valve” function),
d) regulating the useful volume of the tank and preventing the tank from being filled beyond a predetermined level (“OPD” or “overfill protection device” function),
e) degassing the tank while it is being filled.
As a preference, the vent duct communicating with the valve constitutes one end of a venting circuit. The venting circuit may be a single one or, by contrast, there may be many examples of it present. Even more preferably still, this duct constitutes the end of the single venting circuit.
The liquid tank is a closed chamber, of various shapes, generally sealed with respect to the outside, which may be equipped with various internal accessories or accessories passing through the wall of the chamber. The tank may contain any type of organic or inorganic liquid, or mixture of such liquids. In particular, it is a fuel tank for motor vehicles. All types of fuel used in motor vehicles can be stored in the liquid tank such as, in particular, petrol and diesel oil, particularly diesel oil.
The system for venting a liquid tank which is the subject of the invention is a device comprising several elements the overall function of which is to allow a tank to be degassed while it is being filled and to allow it to be vented while it is in use and while the liquid it contains is being used up while protecting the external environment from any leak or emanation of undesirable gas.
According to the invention, the venting system comprises a closed volume internal to the tank. The expression “closed volume” is to be understood as meaning a volume of any shape whatsoever delimited by gas-tight and liquid-tight walls. This volume is located inside the tank and communicates with the valve by means of the vent duct, one end of which is connected to the valve. Its function is to constitute a capacity capable of collecting and retaining any entrainments of liquid from the tank which might have got past the valve barrier.
The volume of this capacity is chosen to be large enough to collect all liquid entrainments likely to get past the valve barrier under particular circumstances, particularly when the tank is full or near to its maximum fill level. This volume also depends on the dimensions and the actual design of the valve and on the diameter of the duct connecting it to it.
According to the invention, the closed volume internal to the tank acting as a capacity in the venting system comprises a draining device. The term “draining device” is to be understood as meaning a check valve, situated at a low point of the capacity, which can open when a sufficient weight of liquid has been collected in this capacity and which communicates directly with the interior volume of the tank. The function of this draining device is to recycle the liquid which has been entrained with the gases leaving the reservoir and prevent the capacity from becoming filled beyond a predetermined maximum level that depends upon the shape of this capacity and upon the characteristics of the check valve.
The venting system according to the invention also comprises a float valve, that is to say a device allowing the reservoir to be opened with the aid of a check valv
Hepperle Stephen M.
Inergy Automotive Systems Management
Larson & Taylor PLC
LandOfFree
System for venting a liquid tank does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with System for venting a liquid tank, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and System for venting a liquid tank will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3007335