Abstract:
The present invention relates to a fuel-drawing assembly for a motor vehicle tank, the assembly comprising a main pump ( 110 ) associated with a pressure regulator ( 170 ) and a reserve bowl ( 150 ) fed by a jet pump ( 160 ) and from which the main pump ( 110 ) draws fuel, the assembly being characterized by the fact that the jet pump ( 160 ) is integrated in the outlet from the pressure regulator ( 170 ), and that the jet pump and regulator ( 160  and  170 ) subassembly formed in this way is secured to a module ( 100 ) comprising the main pump ( 110 ) and the reserve bowl ( 150 ), a portion of the housing ( 171 ) for the pressure regulator ( 170 ) being integrated in the wall constituting the reserve bowl ( 150 ).

Description:
FIELD OF THE INVENTION 
     The present invention relates to the field of assemblies for drawing fuel from a motor vehicle tank. 
     BACKGROUND OF THE INVENTION 
     Numerous devices have already been proposed for drawing fuel from a tank and directing the fuel to feed the engine (carburetor or injector). 
     Most known devices comprise an electric pump associated with a pressure regulator. 
     Devices are also known in which the electric pump draws from a reserve, commonly called the “reserve bowl” placed inside the fuel tank. Such a reserve bowl can be filled from the tank via a float valve which opens to allow fuel to pass from the tank into the reserve bowl whenever the level in the tank is higher than the level in the reserve bowl. 
     Various configurations have also been proposed comprising a jet pump or Venturi effect pump for feeding the reserve bowl. The jet pump is generally fed by an outlet stage of the main pump or by the outlet of the pressure regulator. It takes fuel in from the tank and its outlet delivers to the reserve bowl. 
     Document EP-A-0 798 458 describes a pump device designed to be immersed in a motor vehicle tank, said device comprising a main body in which two contiguous cavities are provided, the first cavity having its main opening at the top and containing a pumping sub-assembly, and the second cavity having its main opening on the side and containing a filter cartridge, said cavity being connected to a fixing plate via a duct to the duct of the plate in order to feed fuel to the vehicle, while a pressure regulator is disposed on the side of the cavity having the main opening and is associated with a jet-pump type system which opens out into the first cavity. (page 1, 1.22). 
     In conclusion, numerous fuel-drawing structures have already been proposed. Nevertheless, most of them are very complex and do not always give satisfaction. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to propose novel means for drawing fuel that present performance that is improved compared with known devices. 
     In one embodiment of the present invention, a fuel-drawing assembly for a motor vehicle tank comprises a main pump ( 110 ) associated with a pressure regulator ( 170 ) and a reserve bowl ( 150 ) fed by a jet pump ( 160 ) from which the main pump ( 110 ) draws fuel. The jet pump ( 160 ) is integrated in an outlet from the pressure regulator ( 170 ) to form a subassembly secured to a module ( 100 ) comprising the main pump ( 110 ) and the reserve bowl ( 150 ). A portion of a housing ( 171 ) for the pressure regulator ( 170 ) is integrated into a wall constituting the reserve bowl ( 150 ), and the outlet from the jet pump ( 160 ) is associated with means for degassing the fuel before it reaches the reserve bowl ( 150 ). 
     As explained below, the present invention makes it easier to adjust the jet/regulator pump subassembly compared with prior known dispositions. 
     By integrating these two components it is possible to adjust the pressure regulator in the factory. This adjustment thus makes it possible to take account of the downstream back pressure imposed on the regulator by the jet pump (which downstream back pressure can modify the characteristics of the regulator). 
     In addition, the structure proposed in the context of the present invention makes it possible to eliminate any need for sealing means to be fitted between the outlet of the pressure regulator and the inlet of the jet pump. 
     The invention also provides a motor vehicle fuel tank fitted with such a fuel-drawing assembly. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other characteristics, objects, and advantages of the present invention will appear on reading the following detailed description, made with reference to the accompanying drawings that are given by way of non-limiting examples and in which: 
     FIG. 1 is a diagrammatic view of the general architecture of a fuel-drawing device in accordance with the present invention; 
     FIGS. 2 and 3 are diagrammatic vertical section views through two variant embodiments of an integrated pressure regulator and jet pump subassembly in accordance with the present invention; and 
     FIGS. 4 and 5 are diagrammatic vertical longitudinal section views of two variant embodiments of the jet pump in accordance with the present invention. 
    
    
     Accompanying FIG. 1 shows the general architecture of a fuel-drawing assembly of the present invention. 
     DETAILED DESCRIPTION OF THE INVENTION 
     In FIG. 1, there can be seen under general reference  10 , a fuel tank whose bottom is referenced  12  and whose top wall is referenced  14 . 
     A fuel-drawing module  100  is placed in the tank  10 . 
     Essentially, this fuel-drawing module  100  comprises an electric pump  110 , a primary filter  120 , a secondary filter  130 , a pressure regulator  170 , and a jet pump  160 . 
     The electric pump  110  has its axis extending vertically. Its inlet is connected to the primary filter  120  situated close to the bottom of the tank  10 , and more precisely inside the reserve bowl  150  as described below. 
     The outlet from the electric pump  110  feeds into the secondary filter  130  which is constituted by a filter that is finer than the primary filter  120 . 
     Thus, the fuel coming from the main pump  110  passes radially through the filter  130  from the outside towards the inside thereof (although the opposite disposition is possible, i.e. the outlet from the pump  110  can deliver to the inside of the filter  130 , in which case the fuel passes through the filter radially towards the outside thereof). 
     From the outlet of the filter  130 , the filtered fuel is directed via a duct  132  to a tubular fitting  140  carried by a base  142  for fixing on the top wall  14  of the tank. From there, the fuel is directed via a duct  144  to the injector assembly  20 . 
     As mentioned above, the primary filter  120  from which the inlet of the pump  110  draws fuel is disposed in the reserve bowl  150 . The bowl stands on the bottom wall of the tank  12  via short legs  152 . 
     The reserve bowl  150  is designed to be filled by the jet pump  160  associated with the pressure regulator  170 . 
     The pressure regulator  170  preferably possesses a housing  171  which receives a diaphragm  172 . In the particular embodiment shown in FIG. 1, the inlet to the housing of the regulator  170  is connected to the outlet of the secondary filter  130 . 
     The diaphragm  172  is subjected to the opposing forces from a rated spring  173  and from the pressure of the fuel that is applied via the inlet to the regulator  170 . 
     The diaphragm  172  carries a shutter  174  associated with a fixed seat  175 . Thus, when the fuel pressure is weaker than the force from the spring  173 , the shutter  174  rests against the seat  175  and the regulator  170  is closed. The jet pump  160  is then not fed. 
     Conversely, when the fuel pressure on the inlet of the regulator  170  exceeds the force from the spring  173 , the diaphragm  172  and the spring  173  are deformed. The shutter  174  is separated from its seat  175 . Fuel can thus flow towards the outlet of the regulator  170  which communicates with the inlet of the jet pump  160 . 
     More precisely still, the outlet from the regulator  170  communicates with the inlet of a nozzle  162 . 
     The jet pump  160  also has a suction duct  164  which communicates with the bottom of the tank  10  and whose outlet opens out into the body of the jet pump  160  downstream from the nozzle  162 . 
     The outlet from the jet pump  160  itself opens out into the inside of the bowl  150 . 
     The outlet from the jet pump  160  is preferably associated with means enabling the fuel to be degassed before it reaches the reserve bowl  150 . 
     As shown in FIG. 1, a low wall  154  can be provided facing the outlet from the jet pump  160 . This wall  154  is connected in leakproof manner laterally and at its base to the walls forming the reserve bowl  150 . Fuel coming from the jet pump  160  thus strikes the wall  154 . As a result, any bubbles of air carried along with the fuel in the jet pump  160  are broken up. The fuel reaches the reserve bowl  150  proper by overflowing over the wall  154 . The wall  154  thus defines the maximum level inside the reserve bowl  150  when it is not being fed by the jet pump  160 . 
     In a variant, such a wall  154  can be replaced by a spiral with a rising bottom whose inlet is placed facing the outlet of the jet pump  160  and whose outlet opens out into the reserve bowl  150 . Under such circumstances, the fuel is degassed progressively as it flows around the spiral. 
     In a variant embodiment, the inlet of the regulator  170  connected to the outlet of the fine secondary filter  130  in FIG. 1 could be connected upstream from the fine filter  130 . 
     FIG. 2 shows one way in which the pressure regulator  170  and the jet pump  160  can be integrated. 
     FIG. 2 shows the main wall of the reserve bowl  150 , the fine secondary filter  130  disposed in a housing  131 , the regulator  170  comprising a housing  171 , a diaphragm  172  associated with a spring  173 , and carrying a shutter  174  co-operating with a seat  175 , and also the jet pump  160  having a nozzle  162  and a suction duct  164 . 
     It will be observed that in the particular embodiment shown in FIG. 2, the shutter  174  carried by the diaphragm  172  is constituted by a spherical ball. 
     It will also be observed on examining FIG. 2 that the seat  175  and the nozzle  162  are formed at opposite ends of a single piece which is preferably made by turning. 
     In practice, the shape of the body of the jet pump  160  (converging portion, diverging portion) can be the subject of numerous variants depending on the characteristics desired for the pump. 
     For these reasons, the particular embodiment of the jet pump  160  shown in accompanying FIG. 2 is not described in detail below. 
     Nevertheless, it should also be observed that O-rings are present, particularly a first ring  180  between the outlet of the fine filter  130  and the wall of the bowl  150  communicating with the inlet of the pressure regulator  170 , a second ring  182  between the housing  170  of the pressure regulator and the wall of the reserve bowl  150 , and finally a third sealing ring  184  around the nozzle  162 , between the nozzle and the body of the jet pump  160 . 
     In the embodiment shown in FIG. 2, the jet pump  160  has its axis horizontal. 
     FIG. 3 shows a variant embodiment in which the pressure regulator  170  and the jet pump  160  are constituted by the same means as those shown in FIG.  2  and as descried above. 
     However, in the variant of FIG. 3, the jet pump  160  (and the regulator  170 ) has its axis at an angle to the horizontal, sloping down towards the bottom  12  of the tank on going towards the outlet from the nozzle  162 . 
     This disposition makes it possible to reduce the suction and priming height of the jet pump  160 . 
     In non-limiting manner, the axis of the jet pump  160  can thus typically be inclined at an angle of about 18° to the horizontal. 
     Typically, this disposition makes it possible to reduce the priming height of the jet pump  160  to a height A of about 6.4 mm for the embodiment shown in FIG. 3 compared with a priming height A of about 15.7 mm for the embodiment shown in FIG.  2 . 
     According to another advantageous characteristic of the present invention, the jet pump  160  can have a nozzle of variable section. 
     By way of example, the jet pump can be one in which the nozzle which receives the injected flow is made up of a nozzle piece comprising a plurality of lips of resilient material adapted so that the nozzle piece presents a section that varies depending on the injected pressure and flow rate, as proposed by the Applicant in Applicant&#39;s patent application filed in France on Sep. 26, 1996 under the No. 96/11739. 
     In another variant, as shown in FIGS. 4 and 5, the jet pump  160  can have a nozzle  162  and a core  165  mounted to move relative to the outlet nozzle piece of the nozzle  162 , downstream therefrom. 
     In yet another variant, as shown in FIG. 5, the core  165  can be provided with a longitudinal through channel  166  forming an auxiliary nozzle. 
     The core  165  can be guided in translation along the axis of the jet pump  160  by any suitable known means. Naturally, these guide means must not disturb the flow of fuel from the nozzle  162  and suck into the suction duct  164 . 
     It may be observed that the core  165  is urged towards the outlet of the nozzle  162  by a rated spring  167 . 
     The core  165  preferably rests against the free end of the nozzle  162  which is in the form of a zone restricted substantially to a circular ridge or against a contact generator line defined on the nozzle  162 . 
     Nevertheless, the particular shape of the end of the nozzle  162  and of the segment of the core  165  resting thereagainst can be the subject of numerous variant embodiments as described in a parallel patent application filed in the name of the Applicant. That is why those various embodiments and the detailed structure of the jet pump with a core shown in FIGS. 4 and 5 is not described in detail below. 
     The operation of the jet pump shown in FIG. 4 is essentially as follows. 
     At the lowest injected flow rates, the ejection section, i.e. the free section of the nozzle  162  is small which makes it possible to increase the power imparted to the jet pump by a high injection pressure. 
     At higher return flow rates, the core  165  is pushed away from the nozzle  162  against compression of the spring  167 , thus increasing the outlet flow section of the nozzle  162  and limiting the back pressure upstream from the nozzle  162  to an acceptable level. 
     The operation of the jet pump shown in FIG. 5 is essentially as follows. 
     When the outlet flow rate from the pressure regulator  170  i.e. at the inlet of the jet pump  160  is zero, the same applies for the flow rate in the suction inlet  164  and for the flow rate at the outlet from the jet pump. Under such circumstances, the core  165  rests against the end of the nozzle  162 . 
     When the flow rate injected into the inlet of the jet pump  160  from the outlet of the pressure regulator is low, the back pressure remains below the pressure threshold for opening the core  165  (as a function of the rating of the compression spring  167 ), thereby localizing injection through the auxiliary nozzle formed by the longitudinal channel  166  in the core  165 . The Venturi effect is thus implemented in conventional manner and the transferred flow is collected via the mixer tube situated downstream from the core  165 . 
     When the flow injected into the inlet of the pump increases, the back pressure rises above the pressure threshold and the core  165  moves back progressively deforming the spring  167  and releasing an annular flow section between the core  165  and the nozzle  162 . This discharge serves to limit the increase of pressure above the opening threshold at high injected flow rates while guaranteeing a secondary Venturi effect at the outlet from the nozzle  162 , thereby contributing to increasing the flow rate sucked in through the inlet  164  after the core  165  has backed off. 
     Thus, in first variant embodiment, provision can be made to use a portion of the wall of the reserve bowl in the form of a shell to form a portion of the housing  171  of the pressure regulator  170 , or indeed to fit the housing  171  of a conventional pressure regulator inside a back piece formed by said wall of the reserve bowl  150 . 
     It should be observed that the fuel-drawing assembly of the present invention is preferably also fitted with conventional means for gauging the level of fuel in the tank  10 .