Fluid handling – Systems – With pump
Reexamination Certificate
1998-08-28
2001-03-27
Maust, Timothy L. (Department: 3751)
Fluid handling
Systems
With pump
C137S565010, C137S565240, C137S343000, C137S351000, C123S497000, C123S510000
Reexamination Certificate
active
06206035
ABSTRACT:
The subject matter of the invention is a safety device for the avoidance of electrostatic charges in fuel tanks, particularly those of motor vehicles. This safety device is arranged on components, preferably the fuel filter and pressure regulator, which are located in the interior of a fuel tank.
A large number of different components are arranged in the fuel tanks of present-day motor vehicles. Consistent with their function, rapidly flowing fuel flows through some of them. Included are fuel pumps and recently, the pressure regulator arranged in the fuel tank in so-called non-return fuel supply systems. Both fuel pumps and pressure regulators have metal parts which build up an electrostatic charge due to the fuel rapidly flowing through them. While these electrostatic charges on the fuel pump are discharged via the electrical bonding, this possibility does not exist with a pressure regulator since it is only in contact with electrically insulating plastic parts. Thus there is the danger that the electrostatic charges may be released in the form of an electrical flashover which can result in a dangerous deflagration in a fuel tank.
Furthermore, fuel filters are also components through which fuel flows in which the higher demands on the filtration of the fuel has resulted in a strong reduction of the mesh size of the filter. A concomitant increased friction between the rapidly flowing fuel and the filter mesh also results in an electrostatic charge. Since the filters often have a housing or support made of non-conducting plastic, the actual filter medium being comprised of either plastic or a metallic material such as a fine wire braided fabric, the accumulating electrostatic charges cannot be dissipated in this case also.
The object of the invention is to avoid electrostatic charges on components in fuel tanks at low expense.
According to the invention, the objective is attained with the features of claim
1
.
Advantageous embodiments are described in claims
2
to
9
.
The electrostatic charges of the components in the fuel tank are effectively discharged by the arrangement of an electrically conductive safety device between the components and a part of the motor vehicle which is in contact with ground potential.
The advantage of the invention consists in the fact that the arrangement of an electrically conductive safety device eliminates the danger of arcing in the fuel tank. The arrangement of this safety device has the further advantage that no modification of the components or their arrangement is required and also the assembly process continues to be unchanged down to the safety device.
It is particularly advantageous if the electrically conductive safety device is a wire which is connected on the one hand with the components such as the fuel filter and pressure regulator and on the other hand with a part of the motor vehicle in contact with ground potential.
The effect of the safety device is increased if this connection is as short as possible. It is thus advantageous to utilize ground potentials already present in the fuel tank. One of these ground potentials is the electrically conductive housing of the fuel pump or the negative pole of the power supply for the fuel pump or the negative pole of the power supply of a fuel level sensor. In addition, short paths for the electrically conductive connection are cost-effective.
In a further embodiment of the invention, if the fuel filter is joined to the housing of a fuel pump, the support or the housing of the fuel filter itself can be made of metal in a known manner, which however, is clearly more expensive than plastic material.
With non-conductive filter material, an attempt could also be made to discharge the electrical charge with a flat, conductive coating. The desired effect is achieved in a substantially simpler and more cost-effective manner if the filter material itself is electrically conductive, e.g., made up of a fine wire braided fabric or an electrically conductive material in a known manner.
A floating electrical conductor such as a flexible lead could be used which would be fixed in an electrically conducting manner to the filter material on the one hand and to the pump housing on the other. However, for quick and reliably correct mounting, it is highly advantageous if the pump-side end of the safety device is fixedly arranged on the support or housing so that when it is connected, it must inevitably come into electrically conducting contact with the pump housing. No special operation is then required to produce the electrical contact.
A trouble-free flow of the fuel filter is assured if the safety device is arranged outside the flow area of the connection area between the fuel filter and pump. With an internal safety device, turbulences and unavoidable vibrations of the liquid flow could cause the development of undesirable noise or noise amplification.
The long-term reliable discharge of charges is promoted if the safety device is mounted to the pump housing with spring bias. For a reliable contact, it is furthermore of advantage if at least one sharp edge of the safety device is in contact with the pump housing, since slight relative motions caused by vibrations of the pump housing will then reliably remove any oxidation layers that may occur.
If the component is a pressure regulator, a wire is also particularly advantageous as an electrically conductive safety device. In the simplest case, the wire is soldered to the subhousing of the pressure regulator. In this way, no additional connecting elements are required.
According to another advantageous further development of the invention, the wire is fixed to a clamping ring fastened to the pressure regulator.
A further contribution to the simplification of the mounting of the wire is made if it is attached to a locking element provided on a bracket for the mounting of the pressure regulator which is required in any event for the attachment of the pressure regulator; aside from the wire this does not require any additional components.
According to an additional advantageous embodiment, the safety device is a bracket for the pressure regulator, the bracket being made of a conductive plastic and has a connection with a part of the vehicle in contact with ground potential.
The pressure regulator can be easily combined with all the parts to be connected to it into a unit which can be preassembled and tested in the fuel tank before installation if the bracket is made of one piece with a feeder unit.
REFERENCES:
patent: 3963408 (1976-06-01), Youngberg
patent: 5642718 (1997-07-01), Nakai et al.
patent: 5785032 (1998-07-01), Yamashita et al.
patent: 4214076A1 (1992-11-01), None
patent: 0754852A3 (1997-01-01), None
patent: 0898073A1 (1999-02-01), None
patent: 08232792 (1995-09-01), None
patent: 09032674 (1997-02-01), None
patent: 9323665 (1993-11-01), None
patent: WO98/42973 (1998-10-01), None
Ehinger Jürgen
Wehner Holger
Mannesmann VDO AG
Maust Timothy L.
Mayer Brown & Platt
LandOfFree
Safety device for a fuel 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 Safety device for a fuel tank, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Safety device for a fuel tank will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2454600