Patent Publication Number: US-RE39599-E

Title: Fuel supply apparatus

Description:
TECHNICAL FIELD 
     This invention relates to a fuel supplying apparatus for supplying pressurized fuel to injectors injecting the fuel into an internal combustion engine. 
     BACKGROUND ART 
       FIGS. 7 and 8  illustrate a conventional fuel supplying apparatus disclosed in International Publication No. W096/23967,  FIG. 7  being a sectional side view and the  FIG. 8  being a plan view. In these figures, it is seen that a cover  3  for closing an opening portion  2  of a fuel tank  1  has a fuel pump  4 , a fuel filter  5 , a pressure regulator  6 , a fuel level gauge  7 , an electric connector  8  and a discharge pipe  9  which are functional components of the fuel supply system assembled thereon as an integral unit. In the fuel tank  1  made of metal or synthetic resin, the opening portion  2  is formed. For closing the opening portion  2 , the cover made of electrically insulating synthetic resin is provided. Between the cover  3  and the fuel tank  1  a gasket  10  is disposed on sealing therebetween. 
     The fuel filter  5  is composed of a filter element  12  made of paper accommodated within a housing  11 . The cover  3  is one part of the housing  11  and the fuel filter  5  is suspended from the cover  3 . The housing  11  comprises the cover  3  and the lower housing  13 , which is electrically conducting because it is molded with a synthetic resin material in which an electrically conductive material such as carbon fibers or carbon powders is mixed. The cover  3  and the lower housing  13  are liquid-tightly welded together over the entire circumference at an interface portion  14  and the filter element  12  is inserted within the inner space. 
     At the upper inner circumference of the housing  11  of the fuel filter  5 , an inlet pipe  5  as a fuel inlet is disposed and is connected to a discharge pipe  16  of the fuel pump  4 . A pipe  17  (shown by dot-and-dash lines) defining a first fuel outlet out of the two fuel outlets of the housing  11  extends upwardly from the lower end of the lower housing  13  along the axial direction. The pipe  17  is communicated with the discharge pipe  9  disposed in the cover  3  to define a fuel passage  18  for supplying fuel filtered through the fuel filter  5  to the injectors for the engine. A return pipe  19  defining a second fuel outlet is disposed at the lower portion of the lower housing  13  and is connected to the pressure regulator  6 . 
     The electrical connector  8  shown in  FIG. 8  is molded integrally with the cover  3  by directly insert-molding a plurality of terminal pins  8 a within the electrically insulating resin material of the cover  3 . The terminal pins  8 a of the electrical connector  8  are connected at the outside of the fuel tank  1  to an electric source and a control unit (not shown). Also, within the fuel tank  1  shown in  FIG. 7 , they are connected through unillustrated lead wires to an electrical connector portion  20  of the fuel pump  4  for supplying electric power to the motor of the fuel pump  4  and also connected through unillustrated lead wires to the fuel level gauge  7  (shown in  FIG. 8 ) for transmitting an electric signal indicative of the fuel level. 
     In the fuel supplying apparatus having the above-described structure, when an electric power is supplied to the fuel pump  4  through the electrical connector  8  and the electrical connector portion  20 , the fuel pump  4  sucks the fuel through the filter  21  to discharge it from the discharge pipe  16 . The fuel flows through a flow path  22  defined between the lower housing  13  and the cover  3  in the direction shown by an arrow A. The fuel then flows through the housing  11  from top to bottom and while doing so the fuel flows through the filter element  12  to be filtered with respect to dust or the like. As for the fuel passed through the filter element  12  and arrived at a bottom space  23  of the housing  11 , one portion of it is returned to the fuel tank  1  by the pressure regulator  6  to regulate the pressure of the fuel and the remaining major portion of the fuel is supplied through the discharge pipe  9  to the injectors (not shown) of the fuel injection apparatus mounted to the engine. 
     During the passage of the fuel through the filter element  12  made of paper, electrostatic electricity is generated due to the friction between the fuel and the filter element  12 . This electricity is dissipated from the lower housing  13  made of an electrically conductive resin through water within the fuel to the exterior of the fuel tank  1 . 
     In the conventional fuel supplying apparatus as above described, the electrostatic electricity generated by the friction between the fuel and the filter element  12  during the passage of the fuel through the paper filter element  12  is dissipated from the lower housing  13  made of an electrically conductive resin. However, with this structure, a contact between the lower housing  13  and the fuel tank  1  during the dismounting of the fuel filter  5  may cause a sparking electric discharge therebetween. This sparking electric discharge causes the lower housing  13  to deteriorate, generating fuel leakage through the deteriorated portion from the interior of the lower housing  13  to the interior of the fuel tank  1 , degrading the filtering ability of the fuel filter  5  and decreasing the pressure of the fuel to an extent that the pressurized fuel cannot be supplied. 
     DISCLOSURE OF THE INVENTION 
     The pressure invention has been made to solve the above-discussed problems and has as its object the provision of a fuel supplying apparatus in which an electrostatic electricity generated while the fuel is passing through the paper filter element can be ensured to be dissipated, generating no deterioration of the fuel filter and which can stably supply the fuel. 
     According to the present invention, the provision is made of a grounding device for taking the grounding earth from the filter element. 
     Also, the filter element may be closely contacted by an electrically conductive member, and grounding terminals of a protector and an electrical connector may be electrically connected through the electrically conductive member. 
     Also, the filter element may be made electrically conductive by mixing an electrically conductive material, and filter element and a grounding terminal of an electrical connector may be electrically connected through an electrically conductive member. 
     Also, a housing of the filter element may have an intermediate terminal secured thereon, and one end of the intermediate terminal may be in abutment with a protector of the filter element and the other end of the intermediate terminal may be connected to a grounding terminal of an electrical connector. 
     Also, a housing of the filter element may have an intermediate terminal secured thereon, and one end of the intermediate terminal may be electrically connected through a grounding spring to a protector of the filter element and the other end of the intermediate terminal may be connected to a grounding terminal of an electrical connector. 
     Further, the apparatus may comprise an intermediate terminal secured to the inner wall portion of the housing of the fuel filter, a contact pawl formed on a protector of an filter element and engaging one end of the intermediate terminal and a contact piece connected to a minus terminal of the fuel pump and engaging the other end of the intermediate terminal, the contact piece being connected to a grounding terminal of an electrical connector. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a sectional side view showing one embodiment of the fuel supplying apparatus of the present invention; 
         FIG. 2  is a plan view showing another embodiment of the fuel supplying apparatus of the present invention; 
         FIG. 3  is a sectional side view showing still another embodiment of the fuel supplying apparatus of the present invention; 
         FIG. 4  is a sectional side view showing a further embodiment of the fuel supplying apparatus of the present invention; 
         FIG. 5  is a sectional side view showing another embodiment of the fuel supplying apparatus of the present invention; 
         FIG. 6  is a sectional side view showing still another embodiment of the fuel supplying apparatus of the present invention; 
         FIG. 7  is a sectional side view showing a conventional fuel supplying apparatus; and 
         FIG. 8  is a plan view showing the conventional fuel supplying apparatus. 
     
    
    
     BEST MODES FOR CARRYING OUT THE INVENTION 
       FIGS. 1 and 2  are views showing one embodiment of the fuel supplying apparatus of the present invention,  FIG. 1  being a sectional side view and  FIG. 2  being a plan view. In these figures, it is seen that a cover  3  for closing an opening portion  2  of a fuel tank  1  has a fuel pump  4 , a fuel filter  5 , a pressure regulator  6 , a fuel level gauge  7  (see FIG.  2 ), an electric connector  8  and a discharge pipe  9  which are functional components of the fuel supply system assembled thereon as an integral unit. In the fuel tank  1  made of metal or synthetic resin, the opening portion  2  is formed. For closing the opening portion  2 , the cover made of electrically insulating synthetic resin is provided. Between the cover  3  and the fuel tank  1  a gasket  10  is disposed on sealing there between. 
     The fuel filter  5  is composed of a filter element  12  made of paper accommodated within a housing  11 . The cover  3  is one part of the housing  11  and the fuel filter  5  is suspended from the cover  3 . The filter element  12  has closed contacted thereto a protector  24  made of metal or an electrically conductive resin or the like and the protector  24  and a grounding terminal  8 b (shown in  FIG. 2 ) within the electrical connector  8  which will be described later are connected by an electrically conductive member  25 . The protector  24  and the electrically conductive member  25  constitute a grounding device. 
     The housing  11  comprises the cover  3  which is an upper housing made of an electrically insulating resin and a lower housing  13  made of a synthetic resin. The cover  3  arid the lower housing  13  are liquid-tightly welded together over the entire circumference at an interface portion  14  and the filter element  12  is inserted within the inner, space. 
     At the upper inner circumference of the housing  11  of the fuel filter  5 , an inlet pipe  5  as a fuel inlet is disposed and is connected to a discharge pipe  16  of the fuel pump  4 . A pipe  17  (shown by dot-and-dash lines) defining a first fuel outlet out of the two fuel outlets of the housing  11  extends upwardly from the lower end of the lower housing  13  along the axial direction. The pipe  17  is communicated with the discharge pipe  9  disposed in the cover  3  to define a fuel passage  18  for supplying fuel filtered through the fuel filter  5  to the injectors for the engine. A return pipe  19  defining a second fuel outlet is disposed at the lower portion of the lower housing  13  and is connected to the pressure regulator  6 . 
     The electrical connector  8  shown in  FIG. 2  is molded integrally with the cover  3  by directly insert-molding a plurality of terminal pins, such as plus side source terminal  8 a, a minus side grounding terminal  8 b and the like, within the electrically insulating resin material of the cover  3 . The terminal pins  8 a,  8 b of the electrical connector  8  are connected at the outside of the fuel tank  1  to an electric source and a control unit (not shown) through un unillustrated connector. Also, within the fuel tank  1 , they are connected through unillustrated lead wires to an electrical connector portion  20  of the fuel pump  4  for supplying electric power to the motor of the fuel pump  4  and are also connected through unillustrated lead wires to the fuel level gauge  7  (shown in  FIG. 2 ) for transmitting an electric signal indicative of the fuel level. 
     In the fuel supplying apparatus having the above-described structure, when an electric power is supplied to the fuel pump  4  through the electrical connector  8  and the electrical connector portion  20 , the fuel pump  4  sucks the fuel through the filter  21  to discharge it from the discharge pipe  16 . The fuel flows through a flow path  22  defined between the lower housing  13  and the cover  3  in the direction shown by an arrow A. The fuel then flows through the housing  11  from top to bottom as viewed in FIG.  1  and while doing so the fuel flows through the filter element  12  to be filtered with respect to dust or the like. As for the fuel passed through the filter element  12  and arrived at a bottom space  23  of the housing  11 , one portion of it flows in the direction shown by an arrow B and is returned to the fuel tank  1  by the pressure regulator  6  to regulate the pressure of the fuel and the remaining portion of the fuel flows in the direction shown by an arrow C and is supplied through the pipe  17  and the discharge pipe  9  to flow in the direction shown by an arrow D into the injectors of the fuel injection apparatus mounted to the engine. 
     During the passage of the fuel through the filter element  12 , the electrostatic electricity generated due to the heavy friction between the fuel and the filter element  12  is dissipated to the grounding terminal  8 b of the electrical connector  8  through the protector made of an electrically conductive material such as metal or an electrically conductive resin and the electrically conductive member  25 . 
     According to this embodiment, the electrostatic electricity generated at the filter element  12  is dissipated through the protector  24  and the conducting member  25  which are the grounding device to the grounding terminal  8 b of the electrical connector  8 , alleviating the deteriorating of the lower housing  13 , generating no fuel leakage into the interior of the fuel tank  1  due to the deterioration, enabling the stable supply of the fuel into the injectors. 
     In the embodiment shown in  FIG. 3 , a filter element  12 A made electrically conducting by mixing an electrically conductive material such as metal powders, metal fibers, carbon powders, carbon fibers or the like is employed. The electrically conductive filter element  12 A is electrically connected to the grounding terminal  8 b of the electrical connector  8  through the electrical conducting member  25  which is the grounding device and the protector  24  is not employed. The structure is the same as those shown in  FIGS. 1 and 2  in other respects, and it is to be noted that the above-described structure also provides a similar improved electrical grounding property. 
       FIG. 4  is a sectional side view showing another embodiment of the fuel supplying apparatus of the present invention. In the figure,  26  is an intermediate terminal made of an electrically conductive material and having a head portion  26 a of a large diameter and a terminal connecting portion  26 b of a small diameter, the terminal connecting portion  26 b being integrally and liquid-tightly secured to a bottom portion  13 a of the lower housing  13  and has formed a male thread  26 c at its tip portion. The top end surface of the head portion  26 a is brought into electrical contact with the bottom end surface of the protector  24 .  27  is a terminal plate connected to one end of the earth line  28 , inserted into the male thread  26 c and electrically connected by a nut  29 . Also, the other end of the earth line  28  is shunt-connected to the minus side of the electrical connector portion  20  of the fuel pump  4 . 
     According to this embodiment, the electrostatic electricity generated at the filter element  12  is dissipated to the grounding terminal  8 b of the electrical connector  8  through the protector  24 —the intermediate terminal  26 —the terminal plate  27 —the lead wire  28 —the minus side of the electrical connector portion  20  of the fuel pump  4 , whereby no electrostatic electricity is accumulated in the lower housing  13 . Therefore, even when the lower housing  13  and the fuel tank  1  are brought into contact with each other during the dismounting of the fuel filter  5 , no sparking discharge occurs, alleviating the deteriorating of the lower housing  13 , generating no fuel leakage into the interior of the fuel tank  1  due to the deterioration, enabling the stable supply of the fuel into the injectors. 
       FIG. 5  is a sectional side view showing the fourth embodiment of the fuel supplying apparatus of the present invention. In the figure,  31  is an intermediate terminal made of an electrically conductive material and having a head portion  31 a of a large diameter integrally and liquid-tightly secured to a bottom portion  13 a of the lower housing  13 , a flange portion  31 b brought into abutment with the bottom end surface  13 b of the lower housing  13 , a spring engaging portion  31 c on its one end and a male thread  31 d on its the other end.  32  is a grounding spring for electrically connecting the bottom end surface  24 a of the protector  24  and the intermediate terminal  31 . The flange portion  31 b is secured to the housing  13  by softening and spreading by heat calking the tip portion of the projection  13 c formed on the bottom end surface  13 b of the lower housing  13 .  27  is a terminal plate which is, similarly to the embodiment shown in  FIG. 4 , connected to one end of the earth line  28 , placed over the male thread  31 d and electrically connected by the nut  29 . Also, the other end of the earth line  28  is shunt-connected to the minus side of the electrical connector portion  20  (shown in  FIG. 4 ) of the fuel pump  4 . 
     According to this embodiment, the electrostatic electricity generated at the filter element  12  is dissipated to the grounding terminal  8 b of the electrical connector  8  through the protector  24 —the grounding spring  32 —the intermediate terminal  31 —the lead line  28 —the terminal plate  27 —the minus side of the electrical connector portion  20  of the fuel pump  4 , whereby no electrostatic electricity is accumulated in the lower housing  13 , so that similar advantageous results to those in the embodiment shown in  FIG. 4  can be obtained, and since the electrical contact between the intermediate terminal  31  and the protector  24  is improved because of the function of the grounding spring  32 , allowing a wider range of dimensional tolerance. 
       FIG. 6  is a sectional side view showing a still another embodiment of the fuel supplying apparatus of the present invention. In the figure,  41  is an intermediate terminal made of an electrically conductive material and integrally and liquid-tightly secured to the inner wall portion  13 d of the lower housing  13  and having a large diameter portion  41 a and a small diameter portion  41 b.  42  is a minus side pump terminal for supplying an electric power to the fuel pump  4  and having formed at its one end portion a male thread  42 a.  43  is a terminal plate having a clamp portion  43 a placed over the male thread  42 a and Electrically connected by the nut  29  and a contact piece  43 b bent downwardly from the camp portion  43 a into an L-shape, the contact piece  43 b elastically establishing an electrical connection with respect to the large diameter portion  41 a of the intermediate terminal  41 .  45  is a contact pawl projecting inwardly from one end of the inner circumferential portion of the protector  24 , which is elastically brought into electrical contact with the small diameter portion  41 b of the intermediate terminal  41 . 
     According to this embodiment, the electrostatic electricity generated at the filter element  12  is dissipated to the grounding terminal  8 b of the electrical connector  8  through the protector  24 —the contact pawl  45 —the intermediate terminal  41 —the contact piece of the terminal plate  43 —the minus side pump terminal  42  of the fuel pump  4 , whereby no electrostatic electricity is accumulated in the lower housing  13 , so that similar advantageous results to those in the previous embodiments can be obtained. 
     APPLICABILITY TO INDUSTRIES 
     According to the fuel supplying apparatus of the present invention, the provision is made of a grounding device for taking the grounding earth from the filter element, so that an electrostatic electricity generated due to the friction while the fuel is passing through the filter element can be ensured to be dissipated without generating spark discharge, generating no deterioration of the fuel filter and allowing a stable supply of the fuel to the injectors. 
     Also, the filter element is closely contacted by the protector made of an electrically conductive material, and grounding terminals of the protector and the electrical connector is electrically connected through the electrically conductive member, so that an electrostatic electricity generated due to the friction while the fuel is passing through the filter element can be ensured to be dissipated without generating spark discharge, generating no deterioration of the fuel filter and allowing a stable supply of the fuel to the injectors. 
     Also, the filter element is made electrically conductive by mixing an electrically conductive material, and the filter element and the grounding terminal of the electrical connector is electrically connected through the electrically conductive member, so that an electrostatic electricity generated due to the friction while the fuel is passing through the filter element can be ensured to be dissipated without generating spark discharge, generating no deterioration of the fuel filter and allowing a stable supply of the fuel to the injectors. 
     Also, the housing of the filter element is provided with an intermediate terminal secured thereon, and one end of the intermediate terminal is made in abutment with the protector of the filter element and the other end of the intermediate terminal is connected to the grounding terminal of the electrical connector, so that an electrostatic electricity generated due to the friction while the fuel is passing through the filter element can be ensured to be dissipated without generating spark discharge, generating no deterioration of the fuel filter and allowing a stable supply of the fuel to the injectors. 
     Also, the housing of the filter element is provided with an intermediate terminal secured thereon, and one end of the intermediate terminal is electrically connected through the grounding spring to the protector of the filter element and the other end of the intermediate terminal is connected to the grounding terminal of the electrical connector, so that an electrostatic electricity generated due to the friction while the fuel is passing through the filter element can be ensured to be dissipated without generating spark discharge, generating no deterioration of the fuel filter and allowing a stable supply of the fuel to the injectors. 
     Further, the apparatus comprises an intermediate terminal secured to the inner wall portion of the housing of the fuel filter, a contact pawl formed on the protector of the filter element and engaging one end of the intermediate terminal and a contact piece connected to a minus terminal of the fuel pump and engaging the other end of the intermediate terminal, the contact piece being connected to the grounding terminal of an electrical connector, so that an electrostatic electricity generated due to the friction while the fuel is passing through the filter element can be ensured to be dissipated without generating spark discharge, generating no deterioration of the fuel filter and allowing a stable supply of the fuel to the injectors.