Patent Document

CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims priority to JP Application No. 2003-166188 filed 11 Jun. 2003. The entire contents of these applications are incorporated herein by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a fuel pump that pumps up and pressurizes fuel for supplying the fuel to an internal combustion engine. 
   2. Description of Related Art 
   An example of this kind of fuel pump is disclosed in JP-A-11-159412. As shown in FIGS. 9, 11 and 13 attached to the above publication, a power-supplying connector is coupled to a power-receiving connector formed in a motor cover. A pair of coupling pieces  37 ,  38  of the power-supplying connector are resiliently coupled to a pair of grooves  29 ,  30  of the power-receiving connector that is formed in a motor cover  4 . Both connectors are firmly connected to each other by engaging a projection  41  of the power-supplying connector with a drain hole  27  of the power-receiving connector. Since the coupling structure, i.e., the coupling pieces  37 ,  38  and the grooves  29 ,  30 , are aligned in the radial direction, it is unavoidable to make the diameter of the motor cover  4  large. 
   Another structure of a conventional fuel pump is shown in  FIG. 8  attached hereto. In this fuel pump  200 , a terminal  206  for supplying power to a motor of the fuel pump is located in a power-receiving connector  204  formed at an upper portion of a motor cover  202 . The terminal  206  is positioned above brushes  210  for supplying power to the motor. Therefore, an axial length of the fuel pump becomes long. 
   SUMMARY OF THE INVENTION 
   The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an improved fuel pump that is compact in size. In particular, an object of the present invention is to reduce a diameter and/or an axial length of the fuel pump. 
   The fuel pump is composed of a cylindrical housing, a rear cover covering the rear end of the housing, a front cover covering the front end of the housing, an electric motor contained in the housing, and a pump portion disposed between the rear cover and the electric motor. A power-receiving connector to be coupled to a power-supplying connector is formed in the front cover. The electric motor is driven by supplying electric power from an on-board battery through the power-receiving connector. The fuel pump is submerged in a fuel tank of an automotive vehicle. When the pump portion is driven by the electric motor, fuel in the fuel tank is pumped up through a fuel inlet port formed in the rear cover, the pumped up fuel is pressurized in the pump portion, and the pressurized fuel is supplied to an internal combustion engine through an fuel outlet port formed in the front cover. 
   The power supplying connector is connected to the power-receiving connector by coupling a pair of claws of the former to a pair of hooks of the latter. To make the diameter of the fuel pump small, the pair of hooks are formed at positions offset from the center of the front cover and close to the outer periphery of the front cover. The pair of claws are coupled to the pair of hooks so that each claw faces to each hook along the periphery of the front cover. To make the axial length of the fuel pump short, an elongate terminal in the power-receiving connector and brushes contacting an axial surface of a commutator located at a front end of an armature are positioned in parallel to the axial direction of the fuel pump. Also, the terminal and the brushes are positioned to overlap each other when viewed from a direction perpendicular to the axial direction. 
   Preferably, drain holes for draining water in the power-receiving connector are formed at positions corresponding to the pair of hooks, so that the drain holes and the hooks are simultaneously formed by molding. Preferably, the fuel outlet port is formed at the center of the front cover, so that a fuel supplying pipe is easily connected to the fuel outlet port regardless of angular positions of the fuel pump mounted on a vehicle body. 
   Other objects and features of the present invention will become more readily apparent from a better understanding of the preferred embodiment described below with reference to the following drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a cross-sectional view showing a fuel pump according to the present invention, taken along line I—I in  FIG. 2A ; 
       FIG. 2A  is a plan view showing a front side of the fuel pump, the front and rear sides being indicated in  FIG. 1 ; 
       FIG. 2B  is a side view showing a front cover of the fuel pump, viewed in direction IIB in  FIG. 2A ; 
       FIG. 3A  is a plan view showing the front cover and components contained therein, viewed from the rear side thereof; 
       FIG. 3B  is a cross-sectional view showing the front cover, taken along line IIIB—IIIB in  FIG. 3A ; 
       FIG. 4  is a perspective view showing the front cover and a power-supplying connector coupled to a power-receiving connector formed in the front cover; 
       FIG. 5A  is a front view showing the power-supplying connector; 
       FIG. 5B  is a side view showing the power-supplying connector, viewed in direction VB in  FIG. 5A ; 
       FIG. 6A  is a plan view showing the front cover to which the power-supplying connector is coupled; 
       FIG. 6B  is a cross-sectional view showing the front cover to which the power-supplying connector is coupled, taken along line VIB—VIB in  FIG. 6A ; 
       FIG. 7A  is a side view showing the front cover to which the power-supplying connector is coupled, viewed in the direction where a pair of drain holes is shown; 
       FIG. 7B  is another side view showing the front cover to which the power-supplying connector is coupled, viewed in direction VIIB in  FIG. 7A ; and 
       FIG. 8  is a cross-sectional view showing a relevant portion of a conventional fuel pump. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   A preferred embodiment of the present invention will be described with reference to  FIGS. 1–7B . A fuel pump  1  shown in  FIG. 1  is used as a fuel pump for pumping up fuel from a fuel tank, pressurizing and supplying the fuel to an internal combustion engine. The fuel pump  1  is submerged in the fuel tank. The fuel pump  1  is composed of a pump portion  2  and an electric motor  4  for driving the pump portion  2 , both being integrally contained in a housing  12 . For convenience of explanation, the upper side of  FIG. 1  is referred to as a front side of the fuel pump  1  and the bottom side is referred to as a rear side thereof. 
   The pump portion  2  includes a rear cover  14  from which fuel is sucked into the fuel pump  1 , an impeller casing  15  and an impeller  16  disposed between the impeller casing  15  and the rear cover  14 . The electric motor  4  is a direct current motor that includes permanent magnets  40  forming a magnetic field, an armature  42  rotating in the magnetic field and a commutator  70  for supplying electric power to the armature  42 . 
   The rear cover  14  and a front cover  20  are disposed at a rear end of an armature shaft  19  and a front end thereof, respectively, and both covers  14 ,  20  are held by the housing  12 . The impeller case  15  and the rear cover  14  are connected together to the cylindrical housing  12  by crimping the rear end of the housing. A C-shaped pumping passage  100  is formed between the impeller case  15  and the rear cover  14 . The impeller  16  to be rotated by armature  42  is disposed between the impeller casing  15  and the rear cover  14 . The armature  42  is rotatably supported by a bearing  17  held in the impeller casing and another bearing  18  held in the front cover  20 . 
   The impeller  16  is disc-shaped, and plural blades and blade grooves are alternately formed at the outer periphery of the impeller  16 . When the impeller  16  is driven by the electric motor  4 , fuel is pumped up from a fuel tank into the pumping passage  100  through a fuel inlet port  102  formed in the rear cover  14 . The pumped up fuel is pressurized in the pumping passage  100  and flows through a space outside the armature  42 . The fuel is supplied to the internal combustion engine through a fuel outlet port  104  formed in the front cover  20 . The fuel outlet port  104  communicates with four communication passages  105  formed around the armature shaft  19  in the front cover  20 . 
   The front cover  20  is made of resin and covers the front end of the electric motor  4  where the commutator  70  is located. The fuel outlet port  104  is formed at the center of the front cover  20 . As shown in  FIG. 2A , a power-receiving connector  22  is formed at a position offset from the center of the front cover  20  and close to the outer periphery thereof. The power-receiving connector  22  has a depressed portion  23  where elongate terminals  26  fixed to the front cover  20  are disposed. As better seen in  FIG. 3B , the depressed portion  23  is depressed from the front end of the front cover  20 . A pair of hooks  24  to be engaged with a pair of claws  35  formed on a power-supplying connector  30  is formed on the walls of the depressed portion  23  (as better seen in  FIG. 6B ). A pair of drain holes  110  open to outside of the front cover  20  through the wall of the depressed portion  23  is formed at positions corresponding to the pair of hooks  24 , as shown in  FIGS. 2A and 2B . 
   As shown in  FIGS. 3A and 3B , components of the electric motor  4 , such as brushes  27 , springs  28  biasing the brushes  27  toward the commutator  70 , plates  29  electrically connecting the terminals  26  to the brushes  27 , are disposed in the rear space of the front cover  20 . As shown in  FIG. 3A , a pair of plates  29  are positioned circumferentially around the armature shaft  19 . As shown in  FIG. 3B , the longitudinal directions of the terminal  26  and the brushes  27  are in parallel to the armature shaft  19 , and are positioned to overlap each other, viewed from the direction perpendicular to the longitudinal direction of the armature shaft  19 . 
   As shown in  FIG. 4 , the power-supplying connector  30  couples to the depressed portion  23  of the power-receiving connector  22  formed in the front cover  20 . Thus, electric power is supplied from an on-board battery to the electric motor  4  through lead wires  36  (shown in  FIGS. 6A and 6B ), the power-supplying connector  30  and the power-receiving connector  22 . 
   As shown in  FIGS. 5A and 5B , the power-supplying connector  30  is composed of a flat box-shaped main body  32  and a pair of strips  34  formed at both sides of the main body  32 . Each strip  34  has claw  35  to be engaged with a hook  24  of the power-receiving connector  22 . The power-supplying connector  30  is coupled to the power-receiving connector  22  as shown in  FIGS. 6A and 6B . The pair of strips  34  partly exposes to outside of the power-receiving connector  22  and partly disposed inside. In other words, each strip  34  is bridged to the main body  32  so that one bridging point is exposed outside and the other bridging point is disposed inside of the power-receiving connector  22 . As shown in  FIG. 5B , the strip  34  is made narrower than the thickness of the main body  32 . The strip  34  is resiliently deformable so that the power-supplying connector  30  can be separated from the power-receiving connector  22  by resiliently deforming the pair of strips  34 . 
   Referring to  FIG. 1  again, the structure of the fuel pump  1  will be further explained. Four permanent magnets  40  are fixed to the inner bore of the housing  12  with adhesive at equal intervals, so that S-poles and the N-poles are alternately positioned. The commutator  70  is positioned at the front end of the armature  42 , and the rear end of the armature  42  is covered with a motor cover  80 . The armature  42  includes a center core  44  firmly connected to the armature shaft  19  and six coil units  50  connected to the outer periphery of the center core  44 . Each coil unit is composed of an armature core  52 , bobbin  60  and armature coil  62  wound around the bobbin  60 . 
   One end of each armature coil  62  is electrically connected to a terminal  64  positioned at the commutator side of the armature  42 . The terminals  64  are positioned a little inside of the outer periphery of the armature  42  so that the terminals  64  does not interfere with fuel flowing through the space between the housing  12  and the armature  42 . The terminal  64  is connected to another terminal  74  located further inside of the terminal  64 . The other end of each armature coil  62  is electrically connected to a terminal  66  which in turn is connected to a terminal  68 . The commutator  70  has six segments  72  which are circularly aligned and insulated from one another. The segment  72  is made of carbon, for example, and electrically connected to the terminal  74  through an intermediate terminal  73 . The brushes  27  sildably contacts an axial end surface of the commutator  70 . 
   Advantages in the present invention are as follows. The pair of hooks  24  that engages with the pair of claws  35  of the power-supplying connector  30  is formed in the power-receiving connector  22 . Each hook  24  is formed at a position close to the outer periphery of the front cover  20  and apart from the axial center. The pair of claws  35  engage with the pair of hooks  24  on a line perpendicular to the radial direction (on the line VIB—VIB in  6 A). Therefore, a space occupied by both connectors  22 ,  30  along the radial direction can be made small. In other words, the diameter of the fuel pump  1  can be made small. Further, since the motor components, such as brushes  27 , springs  28  and plates  29 , are positioned in a space formed at the rear side of the front cover  20 , the length of the fuel pump  1  can be shortened. 
   The power-receiving connector  22  is made by depressing the front cover  20  in the axial direction, and the power-supplying connector  30  is inserted into the depressed power-receiving connector  22 . Thus, the total length of the fuel pump  1  can be made shorter. Since the drain holes  110  are formed at positions corresponding to the hooks  24 , both of the drain holes  110  and the hooks  24  can be made at the same time in a molding process. Since the fuel outlet port  104  is formed in the axial center of the fuel pump  1 , the fuel outlet port  104  can be easily connected to a fuel pipe even if the fuel pump  1  is rotated at its mounting position. Further, since a pulsating pressure of compressed fuel is applied to the axial center, vibration of the fuel pump  1  can be made small. 
   The claw  35  of the power-supplying connector  30  is formed on a thin and narrow strip  34  which is bridged to the main body  32  at two positions. The strip  34  is made to have a sufficient resiliency and mechanical strength. Therefore, a space occupied by the strips  34  and claws  35  can be minimized, and further, the power-supplying connector  30  can be easily detached from the power-receiving connector  22  by resiliently deforming the strips  34 . Further, since the terminals  26  and the brushes  27  are positioned to overlap in the rotational direction of the armature  42 , the length of the fuel pump can be further shortened. 
   The present invention is not limited to the embodiment described above, but it may be variously modified. For example, two important features, i.e., positioning the brushes  27  and the terminal  26  in parallel to and to overlap each other (viewed in the direction perpendicular to the axial direction), and forming the pair of hooks  24  along the circumferential direction of the front cover  20 , are employed in the foregoing embodiment, it is possible to employ only either one of these two features. Though the hooks  24  are integrally formed with the front cover  20  in the foregoing embodiment, it is also possible to make the hooks  24  separately from the front cover  20 . Further, it may be possible to form the hooks  24  at the front surface of the front cover  20  either integrally with or separately from the front cover  20 . 
   Though the power-receiving connector  22  is made in a female shape in the foregoing embodiment, it is possible to make the power-supplying connector  30  in a female shape. The drain holes  110  may be made at other places as long as water retained in the depressed space  23  can be drained. The power-supply connector  30  may or may not be counted as one of the components constituting the fuel pump  1 . 
   While the present invention has been shown and described with reference to the foregoing preferred embodiment, it will be apparent to those skilled in the art that changes in form and detail may be made therein without departing from the scope of the invention as defined in the appended claims.

Technology Category: f