Plug system for a fuel tank filler pipe

The present invention relates to a built-in plug system for a fuel tank filler pipe.

Filler pipes present on fuel tanks, particularly tanks on board motor vehicles, are plugged during normal use of the tank, when the tank is not being filled. Plugging is generally achieved by means of a cap inserted into the upper part of the pipe and twisted in order to seal the pipe against liquids and gases. Various types of cap may be encountered, made of metal and/or made of plastic, sealing being achieved by compressing a seal, this being achieved by screwing the cap in or by turning a key inserted into the middle of the part outside the pipe.

The operations of removing the cap before filling the tank and of replacing this cap and closing off the pipe after filling are usually done manually by the user or by the service station attendant dispensing the fuel. When the tank filling operation is over, people sometimes forget to replace the cap and this can then give rise to the loss of this cap and to the pipe being left open to the atmosphere for some length of time. During this period, losses of liquid fuel may occur and vapours escape into the ambient atmosphere.

With a view to avoiding cap losses and the ensuing atmospheric pollution, plug systems built into the filler pipe have been proposed as a replacement for the conventional cap. Improved versions thereof generally comprise locking means that prevent the said systems from opening unexpectedly, for example when the bowl (the depression in the bodywork in which the filler pipe is located and which is closed off by the fuel filler flap) is being cleaned using a pressure washer.

The fuel flap is usually formed in the bodywork. It is designed to prevent access to the cap or to the plug system when the flap is closed and to give access to the cap or to the plug system when it is open. When closed, the flap is usually flush with the bodywork so as to present little or no height difference with respect to the bodywork.

To save the user having to operate the locking means manually, it is prior art to activate them by a movement of the fuel flap. The movement of the flap is generally transmitted to the locking means by a mechanical connection system so that as the flap moves it transmits a force to the mechanical connection system which in turn acts on the locking means.

Application WO 03/010022 in the name of the Applicant Company describes a plug device equipped with locking means that can be disengaged by a thrust force parallel to the axis of the top of the pipe and re-engaged automatically when the fuel flap is closed by a mechanical connection between the flap and the locking means. Automatic locking occurs throughout the closing movement of the flap. This means that the force produced by the locking means for completely locking and sealing the plug is transmitted via the mechanical connection to the flap. This can result in a misalignment of the flap by the time it reaches the end of the closing movement.

The present invention solves the problem of the misalignment of the fuel flap when its movement is connected to the direct activation of the locking means.

To this end the present invention relates to a plug system built into the top of a fuel tank filler pipe, comprising

• • a plug with a locking device,
  • a fuel flap able to occupy a position allowing access to the pipe and a position preventing access to the pipe, and
  • a mechanical connection system able to transmit a movement from the flap to the locking device in such a way as to lock or unlock the plug,

characterized in that the mechanical connection system comprises components able to interact by part of a movement of one component being transmitted to another, adjacent component in such a way that only part of the movement of the flap can be transmitted to the locking device in order to lock or unlock the plug.

The term “fuel tank” is intended to denote any type of tank capable of storing a liquid and/or gaseous fuel under varying temperature and pressure conditions. Those more particularly concerned are tanks of the kind found in motor vehicles. The expression “motor vehicle” is intended to include motor cars, motorcycles and trucks.

The filler pipe is a pipe which communicates with the inside of the tank and allows fuel to be introduced into it.

The tank and the pipe may be made of metal or of plastic.