Abstract:
A feeding device for feeding fuel, comprising a feed pump, an electric motor driving the feed pump, filtering means, a housing composed of synthetic plastic and formed as a filter casing for receiving the electric motor, the feed pump and the filtering means, the filter casing having concentric housing walls, and a metal jacket arranged at the concentric housing walls at least at one side.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a feeding device for feeding fuel. 
     Feeding devices of the above mentioned general type are known in the art. In a known feeding device the fuel is supplied from a fuel tank, for example to an injection system of the internal combustion engine of a motor vehicle. Such a feeding device provided with a housing of synthetic plastic is disclosed for example in the German patent document DE 44 44 854 A1. In this feeding device, the feed pump is driven by an electric motor, and the fuel flows from the feed pump through a pre-filter, and after the feed pump is supplied under the feeding pressure to a main filter. These components are arranged in a filter casing with a removable cover. The electric motor and the feed pump are located in a central chamber, and the main filter is located in a ring chamber which is arranged concentrically around the main chamber. 
     The cover of the filter casing of this device has communications to tubular connections or pressure hoses through which the fuel is supplied to a connecting flange on the fuel tank. The feeding device forms a complete feeding module which can be directly mounted in the fuel tank. The fuel is aspirated from below on the feeding module and can be supplied from the connecting flange on the cover of the fuel tank through a supply conduit to an internal combustion engine. 
     Such a feeding module needs a plurality of connecting flanges and suspensions, for example for a fixed suspension of the central fuel pump. They are geometrically complicated and therefore produced of synthetic plastic, for example a synthetic plastic injection molded parts, for costs reasons. In this known device it is important to maintain a space for components which is as small as possible and to prevent electrical discharge which can lead to an ignition of the fuel or fuel-air mixture in the tank. The corresponding withdrawl of electrostatic charges can be performed with difficulties because the components are composed of synthetic plastic and they are either non conductive or have poor electrical conductivity. 
     SUMMARY OF THE INVENTION 
     Accordingly, its an object of present invention to provide a feeding device of the above mentioned general types which avoids the disadadvantages of the prior art. 
     In keeping with these objects and with others which will become apparent hereinafter, one feature of present invention resides, briefly stated, in a feeding device of the above mentioned type, in which a metal jacket is arranged in or on the concentric housing walls of the filter casing for receiving the filtering means at both sides of the filtering means or at one side. 
     When the feeding device is designed in accordance with the present invention, then in advantageous manner, a geometrical relatively complicated housing can be produced by free shaping of synthetic plastic, and with simple means an improvement of the strength properties is obtained with a small wall thickness, since the outer diameter of the filter casing can be maintained small due to relatively thin and eventually cast metal jacket. The synthetic plastic housing does not have any swelling problems under the action of the through flowing fuel which can lead to changes of its geometry. 
     Moreover, in the inventive device static discharges are withdrawn, since a metal jacket is arranged on the filtering means at the inner and/or outer side. This can be provided in a simple manner with an electrical connecting means. 
     Also, in advantageous manner uniform electrical potential can be produced through the metal jacket, for example through an electrically conductive tank cover, an electrically conductive feed pump, or a similar part of a motor vehicle located in a feeding path of the fuel. 
     In accordance with a preferable embodiment of the invention, the metal jacket can be formed as a tubular sleeve or a metal plate which is bent to form a tube. It can be interlocked or overlapped at the axial seam location. 
     Furthermore, the metal jacket can be provided with drilled openings or punched holes on its periphery, to ensure an efficient mechanical connection to the synthetic plastic parts of the filter casing. This advantage is also obtained when the metal jacket is provided at the side facing the filter unit with imprints, indentations and similar roughnesses. 
     The metal jacket, before the final mounting can extend substantially over the synthetic plastic part of the filtering unit, and then mounted by crimping, flanging, mortising on the housing part and on the cover for the filtering unit. Thereby a mechanical connection between these components can be established. 
     The metal jacket can be also produced on a terminal post of the electric motor for driving the fuel pump. Thereby a simple terminal guide for the electric motor is formed. 
     The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a view showing a section of a feeding device for fuel with an inwardly located filtering unit; 
     FIG. 2 is a view showing a section through a filter casing of the feeding module with an inventive arrangement of an additional outer and inner jacket of metal; 
     FIG. 3 is a view showing an embodiment with an outer metal jacket, which overlaps the housing part of the filter unit; 
     FIG. 4 is a view showing an embodiment with an inner metal jacket which is formed as a pole tube for an electric motor; 
     FIG. 5 is a view showing an embodiment of the metal jacket with a terminal for an electrical connection, in particular for the embodiment of FIG. 4; 
     FIGS. 6-10 are views showing embodiments of the metal jacket; and 
     FIG. 11 is a view showing two sections through the metal jacket of FIG.  10 . 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG. 1 shows a longitudinal section of a fuel tank  1  with a feeding module or a feeding device  2 , which can be inserted from above through an opening  3  of the fuel tank  1 . The opening  3  is closeable with the tank flange  4 . A connection pipe  5  is provided on the tank flange  4  for a not shown supply conduit which leads to an internal combustion engine of a motorvehicle and transports the fuel in direction of the arrow  6 . Furthermore, the tank flange  4  is provided with the connection for a fuel return conduit  7  coming from the internal combustion engine and for a pressure regulator  27  whose operation is not important for the understanding of the present invention. 
     The feeding device  10  is provided with a feed pump in a lower region. It aspirates fuel from a bottom region of the fuel tank  1  through a pre-filter  9 . The feed pump is driven by an electric motor  10  which is located above the feed pump  8  in a filter casing  11  as a housing. The electric motor  10  is supplied through connecting conductors  12  with an electrical voltage and controlled by it. The cover  13  of the electric motor  10  is composed of an electrically conductive material. 
     A tubular connection  15  is connected to a connecting flange  14  of the electric motor  10 . The supplied fuel flows through it through a connecting pipe  16  into an outer chamber  17  of the filter casing  11 . A main filtering element  19  is located in the filter casing  11  concentrically around the central chamber with the electric motor  10 . The main filter element  19  is subdivided by ring seals  20  of the filter casing  11  into the outer chamber  17  and the inner chamber  21 . The fuel filtered through the main filter element  19  passes from the inner chamber  21  to a connecting pipe  22 . 
     A tubular connection  23  is connected to the connecting pipe  22  and produces a communication to the tank flange  4 . Therefore, the fuel can flow in direction of the arrows  24  and  6  from the inner chamber  21  in the filter casing  11  to the outer supply conduit. Also, the fuel return conduit  7  is connected through a tubular connection  25  to a connecting pipe  26  of the fuel tank  1 . The main filter element  19  of the filter unit is located between an inner synthetic plastic wall and a concentrical outer synthetic plastic wall. In FIG. 2 an embodiment is shown with a metal jacket  30  on the inner wall and a metal jacket  31  on the outer wall. Also, a suspension  33  is illustrated in FIG.  2 . It is used for anchoring the outer metal tube  31  and the total filter casing  11 . 
     In the embodiment of FIG. 3 an outer tube  31  is provided. It projects, before the end mounting, upwardly of a predetermined region  34 . During mounting it is crimped, mortised or flanged and thereby provides a simple and fixed mounting of the filter casing  11 . 
     FIG. 4 shows an embodiment with an inner metal tube  30 , which can be used as a pole tube for the electric motor  10 . The metal tube  31  can be cast, for example in a synthetic plastic injection molding of the housing part for the filter casing  11 . A terminal connection for the electric motor  10  can be performed through an electrical contact to a terminal  31  as can be seen from FIG.  5 . 
     Further examples for the embodiment of an inner metal tube  30  and/or an outer metal tube  31  are shown in FIGS. 6-10. FIG. 6 shows a simple metal tube sleeve  36 , FIG. 7 shows a flanged sheet metal part  37  with interlocked regions  38  at the seam point, and FIG. 8 shows a sheet metal part  37  with overlapping  39  at the seam point. FIG. 9 shows a tubular sleeve  40  which, for improved mechanical contact with the synthetic plastic of the corresponding wall of the housing of the filter casing  11 , is provided with drilled openings or punched out formations  41 . In FIG. 10, for the same purpose, imprints  43  or indentations  44  are formed in the tubular sleeve  42  for the same purposes. The imprints  43  are illustrated in a section B—B and the indentations  44  are illustrated in section A—A in FIG.  11 . 
     It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above. 
     While the invention has been illustrated and described as embodied in feeding device for fuel, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. 
     Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention. 
     What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.