Receptacles – Sidewall structure – Contoured sidewall
Reexamination Certificate
1999-05-10
2001-01-16
Drodge, Joseph W. (Department: 1723)
Receptacles
Sidewall structure
Contoured sidewall
C220S675000, C210S435000, C210SDIG009
Reexamination Certificate
active
06173859
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a fuel filter housing for use with an automobile.
It is known from automobile construction for example, specifically in the field of fuel filters, to make the pot-shaped base of the filter housing from plastic. Lower manufacturing costs and weight savings are realized by contrast with the conventional metallic filter housings previously used. The lid is usually made in the form of a screw connection and is screwed directly to the base without any additional screws or the like, with the base and lid having matching external and internal threads.
Depending on the operating pressure that prevails in the filter housings and depending on the temperatures that prevail in the environment of the filter, the dimensional stability of the plastics used can decrease, causing deformation and hence a slight expansion of the base. The base can be reinforced areawise radially by the additional structural elements provided, such as flanges, connections, and the like, so that the expansion of the base takes place nonuniformly and therefore leads to out-of-roundness of the base with a basically round base cross section- As a result, the tightness between the base and the lid can be adversely affected.
It is known that reinforcements in the form of tensioning rings can be provided externally on the base in the sealing area of the base and lid. The term “sealing area” refers to the zone in which the reinforcements may be located and thus influence the rigidity of the base at the point where it is sealed off from the lid. These sleeve-like reinforcements in the form of tensioning rings increase the assembly costs for the filter housing. In addition, such sleeves fit uniformly around the circumference of the base so that the forces arising from inside, because of the partial reinforcement of the base by means of the other parts such as the flange, connections, and the like, can still produce an out-of-roundness of the base that is slightly reduced by the reinforcing measure.
Other reinforcing measures can consist in inserting reinforcing rings into the housing wall of the base, but these inserts result in higher production costs and can conceal the danger of material impurities or nonuniformity that can be disadvantageous for the recyclability of the filter housing.
A housing according to the species is known from DE-OS 28 31 070 (FIG.
6
). A lid with corners is provided on a round base. The base has a circumferential rib in its uppermost area close to the lid, said rib following the contour of the lid. Projections relative to the base result at the corners so that screws can be provided there to join the lid to the base, since the lid itself is not designed as a screw closure.
Connecting stubs terminate in the base close to and below the circumferential rib on two opposite sides. When the rib follows the contour of the lid, a circumferential rib has a reduced cross section not only above the connecting stub, but also at other points opposite the round base, so that the intrinsic stiffness of the base relative to pressure stresses arising from inside is not uniform around the circumference. As a result, depending on the choice of material and the wall thickness of the base, fluid leaks between the base and lid can result.
SUMMARY OF THE INVENTION
The goal of the invention is to permit a good contour stability of the base in its sealing area with means that are as simple as possible, thus permitting a good tightness of the filter housing and permitting an economical manufacture of the filter housing.
The present invention proposes providing one or more circumferential ribs on the base of the filter housing sealing area between the base and the lid, so that a stiffening of the base takes place in a zone that reinforces the contour stability of the housing at the point where the seal is produced between the base and the lid. Thus, an expansion of the base is opposed at the point where the tightness of the connection between the base and the lid is important. The provision of one or more ribs therefore does not serve to provide anchoring surfaces to receive screws as is the case in the housing constituting the species. Instead it allows economical design of a thin-walled housing which can be flexible areawise throughout during operation, but which is dimensionally stable at the points where the seal is produced between the lid and the base and thus prevents leaks.
By means of the basic stiffening of the base in this sealing area, which is achieved by the rib, according to the invention a retention of the specified contour of the base is produced that is as exact as possible, with the circumferential rib having a varying cross section and being weaker at those points where partial stiffening of the base is provided by the other elements that abut the base wall. The reinforcing effect of these additional parts and of the rib is supplemented radially around the base in such fashion that when the base is subjected to pressure, it opposes this pressure in the sealing area between the base and the lid with a resistance that is nearly the same all around the circumference, and therefore remains dimensionally stable.
A difference in rib cross section that is especially simple to manufacture can be achieved by the rib extending for various distances from the wall of the base and being brought closer to the wall at those points where the other parts abut the base wall.
According to the invention, the rib is not required to surround the base completely or to run completely around the base. Depending on the thickness of the rib and its reinforcing effect on the wall of the base, therefore, provision can be made such that the rib penetrates the base wall at those points where other parts abut the base wall, i.e. the length of the rib at this point returns to zero.
Since a screw connection is provided between the lid and the base, several ribs can advantageously be provided to produce a stiffening of the base that is as uniform as possible around the entire thread area, and to guarantee the tightness of the connection between the base and the lid in this fashion. By providing several ribs, optimum rigidity adaptation for compensation of the partial stiffening by the other structural elements can occur, so that a very exact contour retention of the base in the sealing area is accomplished not only radially but axially as well.
Surprisingly, tests have shown that the contour stability of the base can also be reinforced by the rib being weakened not only at those points where the other structural elements abut the base wall, but also where the base wall is free of such shaped structural elements. With the aid of such further or additional cross-sectional reductions that can be made until the rib cross section is reduced to zero, in other words until the rib breaks, a fine tuning is possible for example by which the final differences between the desired contour pattern of the base can be corrected that could result under the operating conditions of the filter.
The areas whose cross sections have been reduced in this fashion can be provided offset by an angle of several degrees, 10° for example, up to the diametrically opposite position, in other words at an angle of 180°, with the ideal position and ideal size of the cross sectional reduction being determined especially with the aid of modern computers in order to determine this fine adjustment of the contour pattern of the base.
REFERENCES:
patent: 2207399 (1940-07-01), Gaertner
patent: 2997180 (1961-08-01), Loveday
patent: 3333703 (1967-08-01), Scavuzzo et al.
patent: 4336042 (1982-06-01), Frantz et al.
patent: 4834885 (1989-05-01), Misgen et al.
patent: 2831070A1 (1979-02-01), None
patent: 3216395A1 (1983-11-01), None
patent: 4344588A1 (1995-06-01), None
patent: 0 634 203 A2 (1995-01-01), None
patent: 1 395 788 (1975-05-01), None
Renner Volker
Schumann Heiko
Drodge Joseph W.
Ing. Walter Hengst GmbH & Co. KG
Lahive & Cockfield LLP
Laurentano Anthony A.
Ocampo Marianne
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