Abstract:
A delivery unit ( 4 ) has a compensating baffle pot ( 5 ) provided with a fuel pump ( 6 ) arranged therein and a jet sucking pump ( 8 ) for conveying a liquid to the baffle pot ( 5 ). The jet sucking pump ( 8 ) has a propulsion jet nozzle ( 13 ) provided with an opening, a mixing pipe ( 14 ), a suction opening with a suction line ( 11 ) and a deflecting element ( 16 ) located downstream of the mixing pipe ( 14 ).

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a U.S. national stage application of International Application No. PCT/EP2006/050154 filed Jan. 11, 2006, which designates the United States of America, and claims priority to German application number 10 2005 014 287.7 filed Mar. 24, 2005, the contents of which are hereby incorporated by reference in their entirety. 
     TECHNICAL FIELD 
     The subject of the invention concerns a delivery unit and a jet suction pump. 
     BACKGROUND 
     A delivery unit may have a baffle pot, a fuel pump arranged in the baffle pot and a jet suction pump delivering into the baffle pot, the jet suction pump comprising a propulsion jet nozzle with a nozzle opening, a mixing pipe, a suction opening, a suction line connected thereto. The jet suction pump is used to deliver fuel from a fuel container into a baffle pot which is arranged within the fuel container. 
     It is known that fuel containers have many shapes. With the adaptation of the fuel container to the vehicle, using the available space, fuel containers which are subdivided into a plurality of chambers are produced. 
     These chambers are for the most part connected to a saddle. In such fuel containers, the problem arises that, when there is a low level, the fuel can no longer get from one chamber over the saddle into the other chamber. Since usually only one delivery unit is arranged in a fuel container, the fuel located in another chamber cannot reach the delivery unit. In these cases, jet suction pumps are used to feed the fuel present in another region of the fuel container to the delivery unit or to deliver the fuel at least into the chamber or the region in which the delivery unit is located. 
     Conventional jet suction pumps are arranged at the bottom of the chambers or the regions of the fuel container from which the fuel is to be delivered to the delivery unit. With the arrangement of the suction opening of the jet suction pump at the bottom of the fuel container, the jet suction pump is always in the fuel and is thus always ready to operate. Jet suction pumps of this type are distinguished by good efficiency. The delivery factor, that is the ratio of combined jet to propulsion jet, is at least around 7. The disadvantage in this case is that, with the propulsion line to the jet suction pump and the combined line from the jet suction pump, two lines are required, which have to be laid and fixed in the fuel container. 
     Furthermore, it is known to use sucking jet suction pumps which are arranged in the region of the delivery unit. From the jet suction pump, a suction line leads in the region from which the fuel is to be delivered. In order to produce the necessary negative pressure in the suction line, the jet suction pump has a specific propulsion jet nozzle. The outlet opening of the propulsion jet nozzle is designed as a slot. As a result of the slot, the propulsion jet fans out after emerging from the propulsion jet nozzle. The fanned out propulsion jet closes the mixing tube, by which means the necessary negative pressure is produced in order to be able to suck in the fuel over the relatively long suction line. As a result, only one line instead of two lines as hitherto has to be laid in the fuel container and to be fixed. The disadvantage with this arrangement is the low delivery factor of the sucking jet suction pump, which is approximately 2. This low delivery factor is caused by the propulsion jet fanning out after leaving the propulsion jet nozzle. 
     Furthermore, a jet suction pump is known which is arranged with the outlet end of the mixing pipe in a pot, so that the delivery medium in the pot seals off the end of the mixing pipe with respect to the atmosphere. By means of this liquid closure, a negative pressure is produced at the entry to the mixing pipe, which contributes to improving the suction performance. However, it has been shown that, under certain conditions, the suction performance is no longer achieved, which allows it to be concluded that the liquid closure of the outlet of the mixing pipe is not always ensured. 
     This can be caused, for example, by there being too low a quantity of the delivered liquid in the pot. 
     SUMMARY 
     A suction jet suction pump having an improved delivery factor, the suction performance being ensured even under unfavorable conditions, and a jet suction pump that is constructed simply and compactly and to be easy to mount can be provided by an embodiment of a jet suction pump comprising a propulsion jet nozzle with a nozzle opening, a mixing pipe, a suction opening, a suction line connected thereto, wherein a baffle element is arranged downstream of the mixing pipe. 
     According to a further embodiment, the surface of the baffle element facing the mixing pipe may be concave. According to a further embodiment, According to yet a further embodiment, the surface of the baffle element facing the mixing pipe may have ribs. According to a further embodiment, the ribs can be integrally molded in one piece on the baffle element. According to a further embodiment, the baffle element can be connected to the jet suction pump by a latching and plug-in connection. According to a further embodiment, the baffle element can be connected in one piece to the jet suction pump via at least one web. According to a further embodiment, the baffle element can be arranged on another component of the delivery unit, in particular the baffle pot or the fuel pump. According to a further embodiment, the baffle element can be integrally molded in one piece on the delivery unit. According to a further embodiment, the baffle element can be fixed to the delivery unit by means of a latching and plug-in connection. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be explained in more detail using a number of exemplary embodiments. Here, 
         FIG. 1  shows a schematic arrangement of a delivery unit in a fuel container, 
         FIGS. 2   a, b  show the enlarged illustration of the jet suction pump with baffle element according to  FIG. 1 , 
         FIG. 3  shows a sectional illustration through a mixing pipe of a jet suction pump with baffle element, 
         FIG. 4  shows a perspective view of a mixing pipe with baffle element, and 
         FIG. 5  shows the baffle pot of a delivery unit with a baffle element. 
     
    
    
     DETAILED DESCRIPTION 
     According to an embodiment, a baffle element is arranged downstream of the mixing pipe. 
     By means of the baffle element arranged downstream of the mixing pipe, the delivered medium emerging from the mixing pot at high velocity is split and swirled in the region of the outlet opening of the mixing pipe. This swirling of the medium ensures a permanent and reliable liquid closure of the outlet opening of the mixing pipe, so that an adequate negative pressure can form in the jet suction pump, which permits the medium to be delivered to be sucked in over a great distance. 
     According to an embodiment, the surface of the baffle element facing the mixing pipe is concave or formed as a pocket. An embodiment of this type can be produced with little effort and is therefore particularly inexpensive. 
     A shape of the baffle element that can likewise be produced beneficially is given by ribs on the surface of the baffle element facing the mixing pipe. In this case, the ribs can be integrally molded in one piece on the baffle element if the baffle element is produced by means of injection molding. 
     The costs for the production of the concave surface or the ribs can be reduced if these are arranged in the region of the outlet opening of the mixing pipe. 
     The baffle element can, moreover, be produced more inexpensively if it is connected to the jet suction pump by means of a latching and plug-in connection. In this case, the connection can be made both to the mixing pipe and to the housing of the jet suction pump. 
     Mounting of the baffle element with the jet suction pump is avoided, according to another embodiment, if the baffle element is connected in one piece to the jet suction pump. In the simplest case, this connection is formed as at least one web, which extends from the mixing pipe to the baffle element. In this way, baffle element and jet suction pump form one unit. As a result, the jet suction pump can be used at any desired locations. 
     If the jet suction pump is used for filling the baffle pot, the jet suction pump is able to deliver over the upper edge into the baffle pot, and can be advantageously arranged in the region of the upper edge. In this case, according to a further embodiment, the baffle element can be arranged on another component of the delivery unit, in particular the baffle pot, the fuel pump, filter or pressure regulator. 
     Here, the baffle element can be arranged on components of the delivery unit by means of a latching and plug-in connection, by means of adhesive bonding or welding or by means of a one-piece formation on a component, for example by spraying on to the baffle pot. 
     A fuel container  1  comprising two chambers  2 ,  3  is illustrated in  FIG. 1 . Fixed in the fuel container  1  is a delivery unit  4 , comprising a baffle pot  5  and a fuel pump  6  arranged therein. The fuel delivered by the fuel pump  6  to an internal combustion engine, not illustrated, is led via a flow line  7 . Arranged on the inner wall of the baffle pot  5  is a jet suction pump, its mixing pipe  9  projecting into the baffle pot. Fuel from the fuel pump  6  is fed to the jet suction pump  8  via a line  10 . A further line  11  extends from the jet suction pump  9  into the other chamber  2 . Fuel from the chamber  2  is delivered directly into the baffle pot  5  via the line  11 . Downstream of the jet suction pump  8  there is arranged a baffle element  12 . 
     The jet suction pump  8  illustrated in  FIG. 2   a  comprises a propulsion jet nozzle  13 , a mixing pipe  14  having an outlet opening  15  and the suction line  11 . In the region of the outlet opening  15  there is arranged a baffle element  16 . Its surface  17  facing the outlet opening  15  is concave, so that the jet emerging from the mixing pipe  14  is swirled by the concave surface  17  and leads to a liquid closure of the mixing pipe  14 . As a result of the liquid closure, a sufficient negative pressure can be built up in the jet suction pump  8 , by means of which fuel is delivered from the fuel container via the suction line  11 . 
     The jet suction pump  8  illustrated in  FIG. 2   b  differs from the pump according to  FIG. 2   a  in the baffle element  16 . Ribs  18  are integrally molded in one piece on the baffle element  16 , with which ribs the same effect is produced as with the concave surface. 
     According to  FIG. 3 , the mixing pipe  14  of the jet suction pump  8  is provided with an external circumferential groove  19 . Arranged in this groove  19  is a clip  20 , which merges into a web  21 . The baffle element  16  is integrally molded in one piece on the web  21  with a pocket  22 . This clip  20  having the baffle element  16  is produced particularly inexpensively as a simply constructed molding by means of injection molding. 
     According to  FIG. 4 , the baffle element  16  is fabricated in one piece with the jet suction pump  8 , by being connected to the outlet opening  15  of the mixing pipe  14  via webs  23 . 
       FIG. 5  shows a further embodiment of the delivery unit, in which the jet suction pump  8  is fixed to a cover  24  of the baffle pot  5 . By means of the propulsion jet line  10 , a propulsion jet is fed to the jet suction pump  8  from the fuel pump, not illustrated. A nonreturn valve in the propulsion jet line seals off the latter with respect to running empty. In the region of the propulsion jet nozzle  13 , the suction line  11  opens into the jet suction pump  8 . The propulsion jet emerges through the propulsion jet nozzle  13  and enters the mixing pipe  14 . After leaving the mixing pipe  15 , the jet strikes the pocket  22 , by which means the jet is swirled and seals off the outlet opening  15 . The pocket  22  is part of the baffle element  16 , which is welded onto the inner wall of the baffle pot  5 . The baffle element  16  can, however, also be clipped to the baffle pot  5 , in particular hooked onto the upper edge of the baffle pot  5  or arranged on the cover  24 . On account of the liquid closure of the mixing pipe  14  brought about by the baffle element, the propulsion jet produces a substantially higher negative pressure, which is in turn is sufficient to deliver a relatively large quantity of fuel into the baffle pot  5  over a relatively great distance by means of the suction line  11 .