Abstract:
In known devices for pumping fuel, suction jet pumps are used which are driven by the fuel flowing back from the internal combustion engine and pump fuel from a supply tank into an impoundment container of a fuel pumping unit. In known suction jet pumps, the suction power is limited by the fact that the fuel stream applies itself to the housing wall, so that the entire area of the fuel stream is no longer available for entraining fuel. The device of the invention lessens this effect by providing at least one rib between the first partial section of the fuel line and the mixing conduit.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a 35 USC 371 application of PCT/EP 2004/052991 filed on Nov. 17, 2004. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention directed to an improved device for pumping fuel. 
     2. Description of the Prior Art 
     A device for pumping fuel known from German Patent DE 198 56 298 C1 has a suction jet pump that has a fuel line and a mixing conduit; in a first partial section of the fuel line, oriented toward the mixing conduit, a nozzle-like constriction with a nozzle opening is provided, and the fuel line communicates fluidically with the mixing conduit via the nozzle opening. The mixing conduit is embodied at a storage container, and the nozzle-like constriction is disposed as a separate part on the end of the fuel line toward the mixing conduit. The suction jet pump aspirates fuel from a supply tank via an intake opening into an intake chamber. The aspirated fuel, because of the dynamics of the fuel that does not enter the intake chamber parallel to the fuel stream direction, has a tendency to deflect the fuel stream toward a wall of the mixing conduit, so that in an unfavorable case this stream applies itself to the wall and flows along it. As a result, the full surface area of the fuel stream is no longer available for entraining fuel, and the suction power is thus reduced markedly. 
     Because of tolerances between the nozzle and the fuel line, the nozzle, after installation in the fuel line, must be checked for whether it is oriented in the direction of the mixing conduit and the fuel stream extends in the direction of the mixing conduit rather than obliquely to it, so that the fuel stream will not strike the wall of the mixing conduit after a certain distance and contact it there. 
     SUMMARY AND ADVANTAGES OF THE INVENTION 
     The device according to the invention has the advantage over the prior art that the device of the invention is improved in a simple way, because with the same quantity of fuel stream a higher pumping capacity is achieved because the fuel stream is prevented from being applied to the housing wall. Because at least one rib is provided between the first partial section of the fuel line and the mixing conduit, the fuel flowing into the suction jet pump is deflected, guiding the flow, in such a way that the fuel stream undergoes no deflection, or only slight deflection, in the direction of the wall of the mixing conduit. 
     It is especially advantageous if the at least one rib connects the first partial section of the fuel line to the mixing conduit in one piece, since the nozzle of the fuel line is in this way oriented in a defined way to the mixing conduit. After the assembly of the device, the additional check whether the nozzle is correctly oriented is thus unnecessary. 
     In an advantageous feature, the at least one rib is flat or curved in the flow direction. 
     It is also advantageous if the at least one rib, originating at the first partial section of the fuel line, extends in the axial and radial direction as far as the mixing conduit. 
     It is highly advantageous if the at least one rib protrudes past the nozzle opening in the direction of the mixing conduit. 
     It is also advantageous if a plurality of ribs are disposed about the first partial section of the fuel line, since in this way a stable communication between the first partial section, having the nozzle, and the mixing conduit and good flow guidance are achieved. 
     It is furthermore advantageous if between the first partial section of the fuel line and the mixing conduit, an annular inlet opening into the mixing conduit is provided, since in this way the nozzle can be completely bypassed by the flow, and the fuel aspirated by the fuel stream enters the mixing conduit at least approximately parallel to the fuel stream. As a result, the deflection of the fuel stream is at least greatly reduced. 
     It is furthermore advantageous if the wall thickness of the at least one rib, viewed in the axial direction with respect to an axis of the mixing conduit, is small compared to the cross section of the inlet opening of the mixing conduit, since in this way the fuel aspirated by the fuel stream is made the least turbulent. 
     It is also advantageous if the first partial section of the fuel line, having the nozzle-like constriction, and the mixing conduit are inserted into a housing of the suction jet pump, since in this way a very simple assembly of the device is attainable. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       One exemplary embodiment of the invention is described in further detail in the ensuing description, taken in conjunction with the drawings, in which: 
         FIG. 1  shows a view of the device of the invention in section; and 
         FIG. 2  is a side view of the device of the invention of  FIG. 1 , taken along the line II-II. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The device of the invention has a suction jet pump  1 , with a fuel line  2  and a mixing conduit  3 . In a first partial section  2 . 1  of the fuel line  2 , oriented toward the mixing conduit  3 , a nozzle-like constriction  4 , hereinafter called a nozzle, with a nozzle opening  5  is provided; the fuel line  2  communicates fluidically with the mixing conduit  3  via the nozzle opening  5 . 
     The suction jet pump  1  is disposed for instance in a storage container  8  and pumps fuel from a supply tank  9  into the storage container  8 . The storage container  8  is located inside the supply tank  9 , for instance near a tank bottom  10  of the supply tank  9 . 
     The first partial section  2 . 1  of the fuel line  2  and the mixing conduit  3  are disposed for instance in the direction of the tank bottom  10 ; this is also known as a horizontal disposition of the suction jet pump  1 . A disposition of the first partial section  2 . 1  of the fuel line  2  and of the mixing conduit  3  that is perpendicular to the tank bottom  10 , or vertical, is equally possible, however. 
     A second partial section  2 . 2  of the fuel line  2  communicates fluidically, for instance via a pressure regulating valve  11 , with a pressure line  12 , which extends from a pumping unit  15  to an internal combustion engine  16  and supplies the latter with fuel. The pumping unit  15  is disposed for instance in the storage container  8  and aspirates fuel via an intake line  17 , in which a prefilter  18  is for instance provided, and pumps the fuel at elevated pressure to the engine  16  via the pressure line  12 . In the pressure line  12 , a main filter  19  is for instance provided, which filters out fine dirt particles contained in the fuel. From the pressure line  12 , for instance downstream of the main filter  19 , the fuel line  2  branches off and, when the pressure regulating valve  11  is open, supplies the suction jet pump  1  with fuel. The pressure regulating valve  11  opens when the pressure in the pressure line  12  exceeds a predetermined value and causes excess fuel to flow out of the pressure line  12  back into the storage container  10 , via the fuel line  2  having the first and second partial sections  2 . 1 ,  2 . 2 , the nozzle  4 , and the mixing conduit  3  of the suction jet pump  1 . The suction jet pump  1  aspirates fuel from the supply tank  9  in a known manner; via an intake opening  22 , the fuel reaches an intake chamber  23  of the suction jet pump  1 . 
     The suction jet pump  1  may, however, also expressly be supplied via a return line that pumps excess fuel from the engine  16  back into the supply tank  9 . The suction jet pump  1  may also communicate fluidically with the pressure line  12  both upstream and downstream of the main filter  19 , the pressure of the pressure line  12  being lowered, for instance by means of a throttle. 
     The fuel from the fuel line  2  flows via the nozzle opening  5  of the nozzle  4  in the form of a so-called fuel stream into the intake chamber  23 ; beginning at the nozzle  4 , the fuel stream passes through the intake chamber  23  and extends as far as the mixing conduit  3  adjoining the intake chamber  23 . The fuel stream entrains fuel from the intake chamber  23  and/or the mixing conduit  3  in the flow direction, creating an underpressure in the intake chamber  23  that causes replenishing fuel from the supply tank  9  to flow via the intake opening  22  into the intake chamber  23 . The fuel of the fuel stream and the entrained fuel from the intake chamber  23  and/or from the mixing conduit  3  flow via the mixing conduit  3  and an outlet opening  24  from the mixing conduit  3  into the storage container  8 . The mixing conduit  3  widens, for instance on the order of a diffusor, over a portion of its length in order to avoid or reduce flow noise. 
     The first partial section  2 . 1  of the fuel line  2  for instance extends into the intake chamber  23  and can extend as far as an inlet region  25  at the beginning of the mixing conduit  3  or even beyond it. 
     The fuel flowing out of the intake chamber  23  in the direction of the mixing conduit  3  bypasses the first partial section  2 . 1  of the fuel line  2  with the nozzle  4  and passes through an annular inlet opening  26  between the mixing conduit  3  and the first partial section  2 . 1  of the fuel line  2  to enter the mixing conduit  3 . Because of the bypassing of the first partial section  2 . 1  of the fuel line  2 , the flow enters the mixing conduit  3  virtually parallel to the fuel stream, so that the flow forces that deflect the fuel stream are slight. 
     According to the invention, between the wall of the first partial section  2 . 1  of the fuel line  2  and the wall of the mixing conduit  3 , at least one rib  27  is provided, which orients the flow, entering through the annular inlet opening  26 , in the axial direction in such a way relative to an axis  29  of the mixing conduit  3  that the flow is not made as turbulent, and the fuel stream is not deflected, or not as much, in the radial direction transverse to the axial flow direction. In this way, the entire fuel stream area can be utilized for entraining fuel out of the intake chamber  23 , and thus the pumping capacity of the suction jet pump  1  is improved, given the same fuel stream quantity. 
     The at least one rib  27  may be disposed for instance on the wall of the first partial section  2 . 1  of the fuel line  2 , and/or on the wall of the mixing conduit  3 ; the at least one rib  27  for instance extends from the first partial section  2 . 1  of the fuel line  2  toward the mixing conduit  3 , or vice versa. 
     The at least one rib  27  for instance connects the first partial section  2 . 1  of the fuel line  2  in one piece with the mixing conduit  3 . The at least one rib  27 , originating for instance at the first partial section  2 . 1  of the fuel line  2 , extends in the axial and radial direction relative to the axis  29 , protrudes past the nozzle opening  5  in the direction of the mixing conduit  3 , and extends for instance as far as up to and into the mixing conduit  3 . 
     In the one-piece embodiment of the nozzle  4  and mixing conduit  3  by means of the at least one rib  27 , the nozzle  4  and the mixing conduit  3  are oriented in a defined way to one another, so that the nozzle  4  with the nozzle opening  5  and the mixing conduit  3  are for instance disposed concentrically to one another. 
     The suction jet pump  1  is made of plastic, for instance, and the walls of the first partial section  2 . 1  of the fuel line  2  and of the mixing conduit  3  are produced in one piece for instance by means of injection molding in one injection molding operation. 
     The at least one rib  27  has a streamlined shape and is embodied as flat in platelike form or curved in the flow direction; the curvature of the at least one rib  27  may be provided to make for better unmolding of the device after the injection molding operation. The curvature of the at least one rib  27  may be embodied in the axial and/or the radial direction relative to the axis  29 . 
     For example, a plurality of ribs  27  are provided, for instance three ribs  27 , and the ribs  27  are disposed around the first partial section  2 . 1  of the fuel line  2  and distributed uniformly over the circumference, so that the ribs  27  divide the annular inlet opening  26  of the mixing conduit  3  into a plurality of individual partially annular openings. Because of the embodiment of the device with a plurality of ribs  27 , a mechanically more-stable connection is attained between the first partial section  2 . 1  and the nozzle  4  and the mixing conduit  3 . Moreover, in this way, the flow is guided even better in the direction of the mixing conduit  3  than if there were only one rib  27 . 
     The first partial section  2 . 1  of the fuel line  2  with the nozzle-like constriction  4  and the mixing conduit  3  are inserted into a housing  31 ; provided on the housing  31  are for instance the second partial section  2 . 2 , oriented toward the pressure regulating valve  1 , of the fuel line  2 , the intake chamber  23  with the intake opening  22 , and a mount  32  for the mixing conduit  3 . The housing  31  is for instance made from plastic. The second partial section  2 . 2  of the fuel line  2 , for instance near the first partial section  2 . 1 , has a deflection  37 , which may for instance be a 90° deflection. The mount  32  has a first receiving opening  33 , into which the mixing conduit  3  can be inserted. The second partial section  2 . 2  of the fuel line  2 , on the end toward the intake chamber  23 , likewise has a second receiving opening  34  for the insertion of the nozzle  4 . The first receiving opening  33  and the second receiving opening  34  are for instance disposed concentrically to one another. The second receiving opening  34  is for instance embodied as a stub. The intake chamber  23  protrudes past the first receiving opening  33  and the second receiving opening  34  in the radial direction relative to the axis  29 , so that the flow can bypass the circumference of the first partial section  2 . 1  of the fuel line  2  with the nozzle  4  and enter the mixing conduit  3  annularly. 
     For instance, the mixing conduit  3  is thrust, with the integrally joined first partial section  2 . 1  of the fuel line  2  leading, into the first receiving opening  33 , until the first partial section  2 . 1  of the fuel line  2  protrudes into the second receiving opening  34  of the second partial section  2 . 2  of the fuel line  2  and tightly closes off the second receiving opening  34  from the intake chamber  23 . 
     The assembly of the device is in this way greatly simplified, compared to the prior art. 
       FIG. 2  shows a sectional view of the device of the invention of  FIG. 1 , taken along the line II-II. In the device of  FIG. 2 , those elements that remain the same or function the same as in the device of  FIG. 1  are identified by the same reference numerals. 
     The wall thickness  30  of the at least one rib  27 , viewed in the axial direction relative to the axis  29  of the mixing conduit  3 , is very small compared to the flow cross section of the annular inlet opening  26  of the mixing conduit  3 , so as not to make the flow turbulent. The at least one rib  27 , viewed in the axial direction relative to the axis  29 , has a small but arbitrarily shaped cross section. For instance, this cross section is rectangular. In the exemplary embodiment of  FIG. 2 , three ribs  27  are provided. 
     The foregoing relates to a preferred exemplary embodiment of the invention, it being understood that other variants and embodiments thereof are possible within the spirit and scope of the invention, the latter being defined by the appended claims.