Patent Publication Number: US-2010116367-A1

Title: On-off valve in a fuel delivery module and method for retrofitting the fuel delivery module

Description:
PRIOR ART 
     The invention is based on an on-off valve as defined by claim  1  and on a fuel delivery module as defined by claim  8 . 
     Fuel delivery modules are already known that have a reservoir pan and a two-stage delivery assembly disposed in the reservoir pan; with a first delivery stage, the delivery assembly aspirates fuel from a fuel tank into the reservoir pan, and with the second delivery stage, it draws fuel from the reservoir pan and delivers it, with increased pressure, via a pressure line to an internal combustion engine. It is disadvantageous that the two-stage delivery assembly cannot be replaced by a single-stage delivery assembly, since in that case there would be no active filling of the reservoir pan, which assures the fuel supply of the single-stage delivery assembly especially during cornering and while traveling on hills. 
     A fuel delivery module is already known from German Patent Disclosure DE 38 27 572 A1, having a single-stage delivery assembly, disposed in a reservoir pan, that aspirates fuel directly from the fuel tank via an on-off valve, and at low fill levels and/or when cornering or traveling on hills, the on-off valve switches over in such a way that fuel is aspirated from the reservoir pan. In this way, the active filling of the reservoir pan, which in the prior art is achieved with a first delivery stage of the delivery assembly or alternatively with a suction jet pump, is dispensed with. The on-off valve has two inlets and one outlet, and a first inlet and the outlet are provided on the face end and a second outlet is provided on the circumference of the on-off valve. The inlets discharge into a valve chamber, which can be made to communicate fluidically with the outlet via a valve seat opening, and the valve seat opening has a valve seat that is closable with a valve body disposed movably in the on-off valve, and the outlet protrudes with a valve seat portion into the valve chamber, and there is a radial gap provided between the valve seat portion and a circumferential wall of the valve chamber. It is disadvantageous that the on-off valve is integrated with the reservoir pan and is not suitable for retrofitting from a two-stage to a single-stage delivery assembly. 
     ADVANTAGES OF THE INVENTION 
     The on-off valve according to the invention having the characteristics of claim  1  has the advantage over the prior art that it is suitable for being retrofitted on a reservoir pan, in order upon replacement of a two-stage delivery assembly with a single-stage delivery assembly to assure the fuel supply of the single-stage delivery assembly in every operating state. This is attained according to the invention in that the on-off valve has its own, separate valve housing, which is embodied such that it can be inserted into and secured in a cylindrical opening of the reservoir pan. In this way, the on-off valve is embodied on the order of a cartridge. The cylindrical opening of the reservoir pan is embodied as originally empty, that is, without built-in fixtures, and serves the purpose of directly aspirating fuel through the first delivery stage of the two-stage delivery assembly. 
     By the provisions recited in the dependent claims, advantageous refinements of and improvements to the on-off valve defined by claim  1  and the fuel delivery module defined by claim  7  are possible. 
     In one advantageous embodiment, the valve housing has snap hooks, which are lockable in the cylindrical opening. 
     It is especially advantageous if the valve seat portion widens continuously or in stepped fashion toward the valve seat, since in this way an extremely narrow radial gap is formed on the valve seat and creates a predetermined pressure loss. As a result of the embodiment of the extremely small radial gap, a predetermined pressure profile at the valve body can be established that should be embodied as symmetrically as possible, in order to achieve a stable, horizontal position of the flat valve body. 
     It is furthermore advantageous if a further valve seat with a further valve seat opening is provided, and the valve body is disposed movably between the valve seat and the further valve seat in such a manner that either the first inlet or the second inlet communicates fluidically with the outlet, and a connecting part of a prefilter, on which the further valve seat is embodied, is disposed at the first inlet. By the embodiment of the further valve seat on a separate part, the on-off valve can be produced especially economically. 
     It is highly advantageous if the valve body protrudes past the valve seat radially with regard to a valve axis and has a through opening, since in this way, two fluidic communications can be selected with a single valve body. 
    
    
     
       DRAWINGS 
       One exemplary embodiment of the invention is shown in simplified form in the drawings and is explained in further detail in the ensuing description. 
         FIG. 1  shows an on-off valve of the invention in section; and 
         FIG. 2  shows the on-off valve of the invention of  FIG. 1  in section, in a fuel delivery module. 
     
    
    
     DESCRIPTION OF THE EXEMPLARY EMBODIMENT 
       FIG. 1  shows an on-off valve of the invention in simplified faint, in section. 
     In an apparatus for delivering fuel, the on-off valve serves to control the fuel aspiration by a delivery assembly in such a way that fuel is aspirated either from a fuel tank or from a reservoir that is disposed in a fuel tank and is constantly filled via a fuel return. If the fill level in the fuel tank is sufficient, the delivery assembly aspirates the fuel from the fuel tank, and if the fill level is too low, it aspirates it from the reservoir. The switchover between the two switching positions is effected automatically, or in other words without external energy. 
     The on-off valve has a valve housing  1  with two inlets  2 ,  3  and one outlet  4 , and a valve body  5  is provided, which as a function of a fill level in the fuel tank fluidically connects either the first inlet  2  or the second inlet  3  with the outlet  4 . The valve housing  1  is embodied at least in some portions as cylindrical, sleevelike or cartridgelike, and the first inlet  2  is embodied on one face end, the outlet  4  is embodied on the opposite face end, and the second inlet is embodied on the circumference of the valve housing  1 . The inlets  2 ,  3  discharge into a valve chamber  8 , which can be made to communicate fluidically with the outlet  4  via a valve seat opening  9 . The valve seat opening  9  has a valve seat  10 , which is closable with the valve body  5  that is disposed movably in the valve chamber  8 . 
     At the first inlet  2 , a further valve seat  11  is provided, which likewise cooperates with the valve body  5 . The valve body  5  is disposed axially movably between the valve seat  10  and the further valve seat  11  relative to a valve axis  12 . The further valve seat  11  is provided for instance as a separate part in the valve housing  1 . In the exemplary embodiment, the further valve seat  11  is embodied on a connecting part  14  of a prefilter  15  which communicates with the first inlet  2  of the valve housing  1 . 
     The on-off valve is embodied such that upon contact of the valve body  5  with the valve seat  10 , the first inlet  2  communicates fluidically with the outlet  4 , and upon contact of the valve body  5  with the further valve seat  11 , the second inlet  3  communicates fluidically with the outlet  4 , and the first inlet  2  is closed. 
     The outlet  4  protrudes with a valve seat portion  4 . 1  into the valve chamber  8 , and a radial gap  17  is provided between the valve seat portion  4 . 1  and a circumferential wall  16  that radially defines the valve chamber  8 . The radial gap  17  extends over at least part of the circumference of the valve chamber  8 , and for instance over the entire circumference. The valve seat portion  4 . 1  is embodied as a separate part, for example. 
     The second inlet  3  is disposed such that it discharges into the radial gap  17  between the circumferential wall  16  of the valve housing  1  and the valve seat portion  4 . 1 . In this way the first inlet  2  and the second inlet  3  are disposed relative to one another such that with a single valve body  5 , a predetermined fluidic communication can be established between the inlet  2  or  3  and the outlet  4 , with the respective other fluidic communication interrupted. 
     In the exemplary embodiment, the valve seat portion  4 . 1  widens continuously or in stepped fashion toward the valve seat  10 , so that an extremely narrow radial gap  17  is formed, which upon the aspiration of fuel via the second inlet  3  toward the outlet  4  generates a predetermined pressure loss in the extremely narrow radial gap  17 . The second inlet  3  is disposed upstream of the extremely narrow radial gap  17 . The valve seat portion  4 . 1  could also have a constant diameter. The contour, which for instance is stepped, of the valve seat portion  4 . 1  is embodied on both the inner circumference and the outer circumference. 
     The valve body  5  protrudes past the valve seat  10  in the radial direction relative to the valve axis  12 , in such a way that upon contact of the valve body  5  with the valve seat  10 , the radial gap  17  is substantially covered. A predetermined radial play is provided between the circumferential wall  16  and the valve body  5  so that the valve body  5  does not become canted in the course of its reciprocating motion. The result is a slight flow of leakage fuel from the second inlet  3  into the outlet  4 , when the first inlet  2  is in fluidic communication with the outlet  4 . 
     In order for the outlet  4  to open for the first inlet  2  in the upper valve position, that is, upon contact of the valve body  5  with the valve seat  10 , the valve body  5  has at least one through opening  20 , radially inside the valve seat  10 . In the upper valve position, the second inlet  3  is essentially closed, so that the fuel is aspirated essentially directly from the fuel tank. In the lower valve position, that is, upon contact of the valve body  5  with the further valve seat  11 , the first inlet  2  is tightly closed, so that fuel is aspirated only from the reservoir via the second inlet  3 , and the fuel flows via the extremely narrow radial gap  17  and is deflected by approximately 180° and then reaches the outlet  4  via the valve seat opening  9 . The further valve seat  11  is embodied such that upon contact of the valve body  5  with the further valve seat  11 , the through opening  20  is tightly closed. The further valve seat  11  has at least one further valve seat opening  11 . 1 , which is for instance embodied as crescent-shaped, in split ring fashion or annularly. The annular shape of the further valve seat  11  is formed for instance because a disklike valve seat body  112  is disposed centrally in the circular further valve seat opening  11 . 1 , the diameter of this body being less than the diameter of the further valve seat opening  11 . 1  and this body being connected by means of ribs  11 . 3  to one edge  11 . 4  of the further valve seat opening  11 . 1 . One annularly encompassing collar  11 . 5  is provided on each of the two edges of the annular further valve seat openings  11 . 1 ,  11 . 2 , and in the lower valve position the valve body  5  comes to rest on this collar. The through opening  20  is disposed for instance radially inside the further valve seat opening  11 . 1 . 
     The valve body  5  is embodied for instance as disklike and flat. It can be made from a metal or plastic, for example. On the side remote from the valve seat  10 , the valve body  5  has a sealing means  21 , which is embodied for instance as a flat seal, a layer, or a coating and which is solidly connected to the valve body  5 . In this way, the further valve seat  11  closes tightly upon contact with the valve body  5 . The sealing means  21  is made for instance from rubber or elastic plastic. 
     The valve housing  1  protrudes with its end portion oriented toward the first inlet  2  into a cylindrical portion  14 . 1  of the connecting part  14  and is connected to it. In the exemplary embodiment, a snap or detent connection is provided; for instance, an annular bead  22  is embodied on the outer circumference of the valve housing  1  and snaps into place into a complementary indentation  23  on the inside circumference of the cylindrical portion  14 . 1  of the connecting part  14 . It is understood that some other type of connection, such as a press-fit or welded connection, would also be possible. On the cylindrical portion  14 . 1 , a flange portion  14 . 2  is provided, which extends in the radial direction relative to the valve axis  12 . Radially inside the cylindrical portion  14 . 1 , the further valve seat  11  having the further valve seat opening  11 . 1  is embodied on the connecting part  14 . 
     On the end portion oriented toward the outlet  4 , the valve housing  1  also has a snap or detent connection for connecting to a fuel delivery module. For this purpose, snap hooks  24  are for instance embodied, which are distributed over the circumference of the end portion. 
       FIG. 2 , in section, shows the on-off valve of  FIG. 1 , secured in an intake opening of a reservoir pan of a fuel delivery module. 
     In the fuel delivery module of  FIG. 2 , those parts that are the same or function the same as in the on-off valve of  FIG. 1  are identified by the same reference numerals. 
     According to the invention, it is provided that the on-off valve has its own, separate valve housing  1 , which is embodied such that it can be inserted into and secured in the intake opening  27  of a reservoir pan  28  of a fuel delivery module  29 . In this way, an on-off valve that was not originally provided on the reservoir pan  28  is can be provided by retrofitting. A delivery assembly  37  is provided in the reservoir pan  28  of the fuel delivery module  29 ; it aspirates fuel via the on-off valve  1  and delivers it, with elevated pressure, via a pressure line  38  to an internal combustion engine  39 . With an intake stub  40 , the delivery assembly  37  protrudes into the outlet  4  of the on-off valve. However, the outlet  4  of the on-off valve can also extend into an inlet of the delivery assembly. The fuel delivery module  29  is disposed on the bottom  42  of a fuel tank  43 . 
     From outside, that is, from the side of the reservoir pan  28  toward the fuel tank, the on-off valve of the invention is inserted, with the end portion toward the outlet  4  leading, into the intake opening  27  of the reservoir pan  28  that is part of the fuel delivery module  29 . As a result of this retrofitting of the reservoir pan  28 , it is possible, in a fuel delivery module originally equipped with a two-stage delivery assembly, to use a single-stage delivery assembly. 
     The intake opening  27  is provided in the bottom  30  of the reservoir pan  28  and for instance has an annular collar  31  that protrudes into the reservoir pan  28 . The on-off valve is inserted into the intake opening  27  in such a way that the snap hooks  24  engage a collar rim  32  of the annular collar  31  from behind and in this way lock the on-off valve. The annular collar  31  has a shoulder  35 , for example. A sealing ring  36  is provided on the outer circumference of the valve housing  1 ; viewed in the axial direction, it is disposed between the cylindrical portion  14 . 1  of the connecting part  14  and the shoulder  35  of the annular collar  31  of the intake opening  27 . 
     For example, at least one snap hook  24  of the on-off valve is locked by the mounting of the delivery assembly  37  in the reservoir pan  28 , in that a bearing journal  37 . 1  of the delivery assembly  37  protrudes into an interstice between the snap hook  24  and the outlet  4  and blocks any possible inward yielding of the snap hook  24 .