Patent Publication Number: US-2003221677-A1

Title: Device for supplying fuel from a tank to the internal combustion engine of a moter vehicle

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] The invention is based on a device for supplying fuel from a tank to the internal combustion engine of a motor vehicle.  
       [0003] 2. Description of the Prior Art  
       [0004] Devices of the general type according to the invention are already known, e.g. from DE 198 33 130 A1. These often have delivery capacities that are too low to be able to supply enough fuel for every operating state of an internal combustion engine or have a poor ratio of the aspirated volumetric flow to the volumetric flow of propulsion jet.  
       [0005] Furthermore, DE 197 36 088 A1 has disclosed the placement of a pin in a central nozzle opening, thus producing a fuel jet that widens out like an envelope of a cone, and preventing the fuel jet from directly striking a check valve.  
       OBJECT AND SUMMARY OF THE INVENTION  
       [0006] The device according to the invention has the advantage over the prior art that the device is simply improved in that a higher delivery capacity can be achieved with the same propulsion jet quantity than in known devices. This allows the suction jet pump to supply enough fuel, even to a fuel pump with a high delivery capacity.  
       [0007] Advantageous modifications and improvements of the device are possible. For example, it is particularly advantageous to dispose the pin centrally in relation to the nozzle in order to achieve a constant jet velocity and thus a constant suction capacity over the circumference of the jet.  
       [0008] For flow engineering reasons, it is also advantageous for the pin to taper in the downstream direction and to embody the cross section of the pin as circular, for example. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0009] The invention will be better understood and further objects and advantages thereof will become more apparent from the ensuing detailed description of preferred embodiments taken in conjunction with the drawings, in which:  
     [0010]FIG. 1 shows a simplified depiction of a device for supplying fuel from a tank to the internal combustion engine of a motor vehicle, and  
     [0011]FIG. 2 shows a longitudinal section through a detail of the device according to FIG. 1.  
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0012]FIG. 1 shows a simplified depiction of a device that can be used, for example, to supply fuel from a tank  1  to the internal combustion engine  2  of a motor vehicle. The tank  1  contains a collecting receptacle  3  from which fuel is drawn by a fuel delivery unit  4  disposed in the collecting receptacle  3 . A pressure fitting  5  of the fuel delivery unit  4  is connected to a pressure line  6  that leads to the internal combustion engine  2 . The pressure line  6  also contains a pressure regulator  7 , which regulates the pressure of the supplied fuel in the pressure line  6  to the system pressure that has been established for the internal combustion engine  2 . A return line  8  leads from the pressure regulator  7  back to the tank  1  and fuel that is not needed by the engine  2  flows back to the tank  1  through this return line. The return line  8  is connected to a suction jet pump  9  that is disposed in the tank  1  and feeds fuel into the collecting receptacle  3 . During operation of the engine  2 , the fuel delivery unit  4  feeds fuel from the collecting receptacle  3  to the engine  2 , and the fuel flowing back through the return line  8  drives the suction jet pump  9 .  
     [0013]FIG. 2 shows a simplified depiction of the suction jet pump  9  used in FIG. 1. It is comprised of a housing  10  with an inlet opening  11  to be connected to the return line  8 . The fuel entering through this inlet opening  11  is then conveyed through an inlet conduit  12  to a nozzle  13  spaced a certain distance after the inlet opening, via whose nozzle outlet  19 , fuel travels in the form of a jet  14  into a suction chamber  15 . The suction chamber  15  communicates with the tank  1 . The jet  14  aspirates fuel from the suction chamber  15 . As a result, a replenishing flow of fuel from the tank  1  flows into the suction chamber  15 . The aspirated fuel then travels through a mixing chamber opening  16  into a mixing chamber  17 , which leads through an outlet opening  18  into the collecting receptacle  3 . The cross section of the mixing chamber  17  widens out in the flow direction, for example in a continuous fashion, in order to reduce flow noise.  
     [0014] Upstream of the nozzle outlet  19 , a pin  20  begins, whose cross section is smaller than that of the nozzle  13  and that of the nozzle outlet  19 , and which extends, for example centrally, downstream into the mixing chamber  17 . The pin  20  can be embodied so that it tapers, for example in the flow direction starting from the mixing chamber opening  16 . The cross section of the pin  20  can, for example, be circular. The cross section of the pin  20 , however, is not limited to a circular cross section; the pin  20  can instead also have an oval, triangular, quadrangular, or other polygonal cross section.  
     [0015] The jet  14  is also referred to as the propulsion jet since it generates the vacuum that drives the suction jet pump  9  and therefore makes it possible for the aspiration of fuel to take place. The greater the surface area of the jet  14 , the more fuel can be aspirated over the surface area of the jet  14 , which permits the delivery capacity to be increased. A large surface area of the jet  14  is achieved through a large diameter of the nozzle  13 . In order to prevent the comparatively large diameter of the nozzle  13  from requiring an excessive volumetric flow of fuel from the return line  8 , the pin  20  is disposed for example centrally in relation to the nozzle  13  and reduces the free cross section of the nozzle  13 . It is important that the pin  20  extend into the mixing chamber  17  so that the jet  14  is guided downstream of the nozzle outlet  19  and as a result, its large surface area is preserved in a stable fashion. In comparison to known devices, therefore, the device according to the invention achieves a greater surface area of the jet  14  with the same volumetric flow of the propulsion jet and the same velocity of the jet  14 , and thus achieves a higher delivery capacity than known devices. The efficiency of the suction jet pump  9 , defined by the ratio of the aspirated volumetric flow to the volumetric flow of the propulsion jet, is significantly increased.  
     [0016] The foregoing relates to preferred exemplary embodiments 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.