JP2650102B2 - Electric fuel pump - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel pump used for an automobile or the like, and more particularly to an apparatus for injecting fuel into an engine based on a command from an electronic control unit. The present invention relates to an electric fuel pump configured as a part of a fuel pump for pumping fuel at high pressure to an injector. 2. Description of the Related Art Heretofore, positive displacement pumps have been mainly used as pumps for discharging fuel at high pressure ( ^{2 to 3} kg / cm ² G). However, this positive displacement pump cannot achieve the required performance unless the manufacturing precision is increased, and if high performance is to be obtained, the cost increases. For this reason, a regenerative electric fuel pump has conventionally been used. Therefore, first, the overall configuration of this type of conventional regenerative electric fuel pump will be described with reference to the drawings. FIG. 1 is a sectional view of a conventional regenerative electric fuel pump cut along a plane including an axis of the pump.
FIG. 2 is a longitudinal sectional view taken along line AA of FIG. This fuel pump is installed, for example, submerged in liquid fuel in a fuel tank of a vehicle. The fuel pump has a substantially cylindrical housing 10 having one axial end wall 13 and another end wall 14 having openings 11 and 12, respectively. The fuel pump further includes a regeneration pump portion 15 disposed in the housing 10 in contact with one axial end wall 13 of the housing 10 and an electric motor portion 16 disposed in the housing 10 adjacent to the regeneration pump portion.
The electric motor section 16 is connected to the regeneration pump section 15 so as to drive the regeneration pump section. The regenerative pump section 15 has a pump casing. The pump casing has a first casing portion 18 which substantially closes an opening 11 provided in one axial end wall 13 of the housing 10, and a first casing portion 18. A second casing portion 21 having an inner surface 19 defining a pump chamber between the inner casing 17 and the inner surface 17 of the casing portion 18. [0004] One end 26 of the rotating shaft 25 extending coaxially with the housing 10 in the axial direction is rotatable by a bearing 28 press-fitted into a central axial hole 27 provided in the second casing portion 21. It is supported by. One end 26 of the shaft 25 in the axial direction passes through the pump chamber, and
Has an axial end face located in a central recess 31 formed in the inner surface 17 of the casing part 18 of the housing. The disk-shaped impeller 3 is mounted on a rotating shaft 25 so as to be rotatable in the pump chamber. Impeller 3
Has a central axial hole 33 (FIG. 2) in which one end 26 in the axial direction is fitted to the rotating shaft 25, and a pair of diametrically opposed axial grooves 34 are formed in the wall surface of the central hole 33. ing. A pin 36 having a circular cross section extends through one end 26 in the axial direction of the rotating shaft 25 and has ends fitted into a pair of axial grooves 34, respectively. Thus, the impeller 3 is mounted on the rotation shaft 25 so as to be movable in the axial direction relative to the rotation shaft 25, but not to rotate relative to the rotation shaft 25. [0006] The impeller 3 has an axial end face 38 facing the inner surface 17 of the first casing portion 18 across the first gap W ₁ and a second casing W across the second gap W _2. The other axial end face 3 facing the inner face 19 of the portion 21
9. These gaps W ₁ and W ₂ are actually very small and FIG. 1 is exaggerated. The recess 31 provided in the first casing part 18 cooperates with the outer peripheral surface and the end surface of the axial end 26 of the rotary shaft 25 to form the chamber 43.
Is defined. A central axial hole 27 provided in the second casing part 21 defines a chamber 44 in the bearing 28 in cooperation with the axial end face and the outer peripheral face of the axial end 26 of the rotary shaft 25. As clearly shown in FIG. 2, a second pair of diametrically opposed axial grooves 45 are formed in the side surface of the axial central hole 33 provided in the impeller 3. The chambers 43 and 44 are in communication with each other by a second pair of axial grooves 45 so that the pressure between the chambers 43 and 44 is balanced. The impeller 3 has an outer peripheral portion defining a substantially annular pump flow passage 4 in the pump casings 18 and 21, and has an axial one end surface 38 and an other end surface 3.
9, a plurality of radial blade grooves 47 are formed at equal intervals in the circumferential direction of the impeller 3.
The illustrated impeller 3 has one axial end face 38 thereof.
The bottom surface of the blade groove 47 formed at the bottom does not intersect the other axial end surface 39 of the impeller 3, and the bottom surface of the blade groove 47 formed at the other axial end surface 39 intersects the one axial end surface 38. It is not a so-called closed blade type. The pump passage 4 is provided with a first casing part 18.
Is connected to a liquid fuel in a fuel tank (not shown) through a fuel inlet 1 provided in the housing 1, and the housing 1 is provided through a fuel outlet 6 provided in the second casing portion 21.
It is connected to the space inside 0. Further, as shown in FIG. 2, the second casing portion 21 is provided with a partitioning portion 100 which opposes the radial outer periphery of the impeller 3 and separates the fuel suction port 1 and the fuel discharge port 6 of the pump flow path. It is formed. The electric motor section 16 has two substantially cylindrical permanent magnets 61 disposed in the housing 10 concentrically with the rotating shaft 25, and the rotating shaft 25 concentrically with the permanent magnets 61. Armature 2 fixed and mounted
And a commutator 63 connected to the armature 2 and fixed to the rotating shaft 25. Commutator 6
A brush 64 is in sliding contact with 3. The brush 64 is held by a brush holder 66 fixed to the end block 67. The end block 67 is provided in the housing so as to substantially close the opening 12 provided in the other axial end wall 14 of the housing 10.
The end block 67 has a central recess 71 formed on one axial end surface facing the space inside the housing 10, and a second central recess 72 formed on the bottom surface of the central recess. A plurality of grooves 73 are formed in the wall surface of the second central recess 72 so as to be spaced apart from each other in the circumferential direction. The groove 73 has an inclined bottom surface and an end opening to the bottom surface of the central recess 72. The end block 67 has a hollow protrusion 74 protruding outward from the other end surface in the axial direction.
Communicates with the second hollow recess 72. The hollow protrusion 74 is adapted to be connected to a fuel consuming equipment (not shown) such as an engine. The other end 81 of the rotating shaft 25 in the axial direction is a bearing 8
2, the bearing 82 of which is seated on a seat 83 formed by chamfering the second central recess 72, and the annular retainer 8 provided in the central recess 71.
5 is held at a predetermined position. The retainer 8
5 is a plurality of holes 86 formed apart from each other in the circumferential direction.
have. The rotating shaft 25 is held at a predetermined position by an annular retainer 85. The rotating shaft 25 is held at a predetermined position in the axial direction by a spacer 87 mounted on the rotating shaft 25 while being in contact with one axial end surface of the bearing 82 and a spacer 88 mounted on the bearing 28. ing. The fuel pump having the above-described structure operates as follows. That is, a brush 64 is supplied from a power source (not shown).
When the current flows through the armature 2, the armature 2 rotates, and the rotation of the armature 2 is transmitted to the impeller 3 by the rotating shaft 25, and the impeller rotates clockwise as indicated by an arrow in FIG. The liquid fuel in the fuel tank is introduced from the fuel inlet 1 into the pump flow path 4 by the rotation of the impeller 3. The introduced fuel is pressurized in the pump flow path 4 by the blade groove 47 of the impeller 3, is discharged through the fuel discharge port 6 into the space inside the housing 10, and has an annular gap between the permanent magnet 61 and the armature 2, a retainer. The hole 86 provided in 85, the groove 73 provided in the end block, and the hollow protrusion 74
To the fuel consuming facility through the hollow part of Here, the flow of the liquid fuel introduced into the fuel suction port 1 of the conventional regenerative electric fuel pump having the above configuration will be described. FIG. 3 is a cross-sectional view of the vicinity of a conventional general fuel inlet 1 viewed from the outer peripheral side, and an arrow λ indicates a rotation direction of the impeller. The fluid that has flowed in from the suction port 1 collides with the flow path side face 8a on the opposite side to the suction port 1 as shown by the arrow in the drawing, and then receives the pumping force by the impeller 3 and moves on the flow path side face 8b on the suction port 1 side. collide. This collision usually depends on the flow path length and the impeller peripheral speed.
The inside is repeated once or twice further toward the discharge side, and gradually decreases and disappears. The collision of the fluid on the flow channel side surfaces 8a and 8b is caused by the steady circulation flow of the flow channel 4 → the blade groove 47 → the flow channel 4 indicated by an arrow f in the explanatory diagram of the steady flow channel in the sectional direction of the pump shown in FIG. Disturbs and reduces pumping action. In order to avoid this, it is conceivable to arrange a partition in the flow path. However, there is a problem in that the number of steps increases and the effective flow path area decreases in manufacturing. As with the inlet 1 described above, the fuel outlet of the conventional regenerative electric fuel pump is connected to the regenerative pump unit 15.
The pump channel 4 is opened from the axial direction of the impeller 3 and communicates with the motor unit 16. Therefore, the flow of the fuel pressurized by the impeller 3 is suddenly changed from the rotational direction of the impeller 3 to the axial direction, so that the flow is disturbed and the fuel is lost. there were. In view of the above problems, an object of the present invention is to reduce the loss by guiding the flow of the impeller at the discharge port from the rotation direction to the axial direction. In order to achieve the above object, the present invention provides an electric fuel pump including a pump section and a motor section, wherein the pump section is formed in a disk shape.
An impeller having a plurality of blades on an outer periphery, a casing for rotatably housing the impeller, a pump flow path formed in an arc shape along the outer circumference of the impeller, an opening at one end of the pump flow path. A suction port for flowing the fuel into the pump flow path, an opening at the other end of the pump flow dew from the axial direction of the impeller, and a discharge port for discharging the fuel pressurized by the impeller and the impeller. A casing having a partition formed between the outer peripheral surface and the intake port and the discharge port, the partition having a partition, and further having a circumferential end face on the discharge side of the partition. A technical means of an electric fuel pump, wherein a side farther from the discharge port than a side closer to the discharge port is formed to protrude along a direction opposite to a rotation direction of the impeller, is adopted. . According to the structure of the electric fuel pump of the present invention described above, the casing accommodates the disk-shaped impeller in a rotatable manner. At one end of an arc-shaped pump flow path formed on the outer periphery of the impeller, a suction port for introducing fuel into the pump flow path is opened, and at the other end of the pump flow path, a discharge is performed from the axial direction of the impeller. The outlet opens. Then, a partition part that partitions the suction port and the discharge port is formed facing the outer periphery of the impeller. Here, the end face on the discharge port side of the partition portion is formed so that the side farther from the side closer to the discharge port protrudes along the direction opposite to the rotation direction of the impeller. For this reason,
The flow of the fuel flowing out from the pump flow path to the discharge port flows along the discharge port side end surface of the partition portion, and is guided in the axial direction from the rotation direction of the impeller as it goes out from the pump flow path to the discharge port. . Thereby, the turbulence of the flow at the discharge port is reduced. FIG. 7 shows an embodiment of an electric fuel pump to which the present invention is applied. FIG. 7 is a cross-sectional view of the vicinity of the suction port 1, the discharge port 6, and the partition part 100 as viewed from the outer peripheral side of the impeller 3. Here, first, the configuration near the suction port 1 of the electric fuel pump of the present invention will be described with reference to FIG. FIG. 5 is a cross-sectional view of the vicinity of the suction port 1 as viewed from the outer peripheral side of the impeller 3. As shown in FIG. 5, a flow path side surface 8a opposite to the suction port 1 is formed as a slope 8a 'having an inclination of θ. The slope 8a 'extends across the first casing 18 and the second casing 21, and the inclination angle θ is, as shown in FIG. 6, the inflow speed S ₁ of the fluid into the suction port 1 and the pressure feeding applied to the fluid from the impeller 3. taking into account the speed S _2,
It is determined in the direction of the combined vector of S ₁ and S ₂ . This will be specifically described in one embodiment.
Assuming that the suction port has a circular area having a diameter of φ4 at 1 / hr, the inflow velocity S ₁ is 2.652 m / sec.
In addition, since the pumping speed S ₂ given to the fluid from the impeller is generally 0.7 times the impeller flow speed, if the impeller rotation speed is 4400 rpm and the impeller diameter is φ40, S ₂ = 6.451 m / sec. From this, θ = 68 °. Although the inclination θ shown in FIG. 5 is constant, it may be changed continuously. The configuration of the electric fuel pump of the present invention other than the configuration near the suction port is the same as the conventional configuration shown in FIG. Although the shape of the suction side has been described above, the inclination of the discharge side is exactly the same as that of the suction side as shown in the cross-sectional view of FIG. 7, and the same effect as that of the suction side can be obtained. Therefore, the configuration on the discharge side is shown in FIG.
This will be described with reference to FIG. As shown in FIG. 7, the suction port 1 of the pump flow path
The end face on the discharge port 6 side of the partitioning portion 100 that partitions the discharge port 6 has a side 100 a near the discharge port 6 when viewed from the discharge port 6.
The side 100b farther from the discharge port 6 than the impeller 3
Is formed so as to protrude in the direction opposite to the rotation direction. As a result, as shown in FIG. 7, when the impeller 3 rotates and enters the lower part of the partition part 100, the one blade 3a of the impeller 3 first moves to the side 3b farthest from the discharge port 6 of the blade 3a. Enters the lower part of the partition 100, and then the side 3c of the blade 3a near the discharge port 6 enters the lower part of the partition 100. For this reason, the flow of the fuel flowing out of the pump flow path to the discharge port 6 flows along the end face of the partition section 100 on the discharge port 6 side. Is guided in the axial direction. As a result, the fuel can be smoothly changed from the rotation direction of the impeller 3 to the axial direction, and the turbulence of the flow can be reduced, and the noise is reduced. According to the configuration and operation of the present invention described above, the end face of the partition, which is a part of the pump flow path, on the discharge port side is closer to the side farther than the side closer to the discharge port. Are formed to protrude along the direction opposite to the rotation direction of the impeller. Thereby, the flow of the fuel flowing out from the pump flow path to the discharge port can be reliably guided from the rotation direction of the impeller to the axial direction as it flows out from the pump flow path to the discharge port. Therefore, the turbulence of the flow can be reduced and the noise can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a conventional electric fuel pump. FIG. 2 is a sectional view taken along line AA of FIG. FIG. 3 is a cross-sectional view of the vicinity of a conventional fuel inlet 1 viewed from an outer peripheral side of an impeller 3. FIG. 4 is an explanatory view of a steady flow in a sectional direction of a pump. FIG. 5 is a cross-sectional view of the vicinity of the suction port 1 as viewed from the outer peripheral side of the impeller 3, showing the configuration of an embodiment of the electric fuel pump according to the present invention. FIG. 6 is a combined vector diagram for explaining the present invention. FIG. 7 is a sectional view showing a configuration of an example of the present invention. [Description of Signs] 1 suction port 3 impeller 4 pump flow path 6 discharge port 15 pump section 16 motor section 18 first casing section 21 second casing section 100 partition section

Continuation of front page    (72) Inventor Ken Matsuda               1-1-1 Showa-cho, Kariya-shi, Aichi Japan               Denso Co., Ltd.                (56) References Japanese Utility Model Showa 54-63506 (JP, U)                 JP-B-36-3779 (JP, B1)

Claims (1)

(57) Claims: (1) In an electric fuel pump including a pump unit and a motor unit, the pump unit is formed in a disk shape, and has an impeller having a plurality of blades on an outer periphery; A casing that rotatably houses the impeller
A pump flow path formed in an arc shape along the outer periphery of the impeller ; an inlet opening at one end of the pump flow path to introduce fuel into the pump flow path; A partition opening at the other end of the pump flow path and facing the outer peripheral surface of the impeller and the discharge port for discharging the fuel pressurized by the impeller, and partitioning between the suction port and the discharge port. A casing having a portion, and a circumferential end face on the discharge port side of the partition portion,
An electric fuel pump, wherein a side farther from the discharge port than a side closer to the discharge port protrudes along a direction opposite to a rotation direction of the impeller. (2) The electric fuel pump according to claim 1, wherein a circumferential end face on the discharge side of the partition portion is formed to be inclined.