JPH06272685A - Motor-driven fuel pump - Google Patents

Abstract

PURPOSE:To restrain the occurrence of negative pressure and a turbulent flow via the attainment of a smooth vortex flow, and improve pump efficiency by forming the predetermined angle of inclination on the rotating rear wall of an impeller vane groove in a rotational backward direction for a linear line orthogonal with the edge of the impeller. CONSTITUTION:A motor-driven fuel pump generates a vortex in fuel via many vanes 42 of a rotating impeller 4, thereby boosting fuel pressure. The impeller 4 is formed to have a disc shape, and many vane grooves 41 are formed on the periphery of both sides thereof via an intermediate wall 43. Also, the grooves 41 are formed among many vanes 42 arrayed at an equal pitch. In this case, the rotating rear wall 41a of the groove 41 is formed to be inclined at the predetermined angle of theta for a linear line L orthogonal with the edge 4a of the impeller 4 in a rotational backward direction. As a result, a flow in the vicinity of the wall can be smoothed, using the slope of the rotating rear wall 41a. According to this construction, the occurrence of a turbulent flow due to negative pressure is reduced, and pump efficiency is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric fuel pump used in automobiles and the like.

[0002]

2. Description of the Related Art As an in-tank type fuel pump used in an automobile or the like, an eddy current type (also called Wesco type or circumferential flow type) electric fuel pump is often used because of its advantage of high pressure and low pulsation. The eddy current type electric fuel pump has a drawback that pump efficiency is low because the fuel pressure is increased by rotating a disc-shaped impeller having a large number of blade grooves on the outer periphery by driving a motor unit. Further, in recent years, the development of pumps with reduced current consumption has become an urgent task in response to the social needs for low fuel consumption of automobiles, and it is necessary to improve the pump efficiency.

FIG. 4 shows a conventional example of an impeller in an eddy current type electric fuel pump. 4, (a) is an end view, (b) is a perspective view, (c) is an explanatory view of the flow of fuel,
(D) is sectional drawing of a blade groove. The impeller 140 has a disk shape as shown in FIGS. 3A and 3B, and has a large number of blade grooves 141 formed on the outer peripheral portions of both front and back surfaces thereof with an intermediate wall 143 interposed therebetween. The blade groove 141 is formed between a large number of blades 142 having an equal pitch.

When the impeller 140 is rotated by driving the motor portion of the electric fuel pump, each blade 142 is rotated.
As a result, a swirl flow is generated in the fuel, and the fuel pressure is increased.
This vortex flow is indicated by a thick arrow in FIG. The blades 142 of the impeller 140 are formed in a right angle shape with a predetermined thickness with respect to the intermediate wall 143 as shown in FIG. Therefore, the blade groove 14 of the impeller 140
Both wall surfaces 141a and 141b viewed from the rotation direction in 1 (see arrow R in the figure) are surfaces orthogonal to the end surface 140a of the impeller 140. The blade groove 14
The rotation front wall surface 141a in 1 corresponds to the back surface (referred to as the rotation direction back surface) viewed from the rotation direction of the blade 142, and the rotation rear wall surface 141b corresponds to the surface viewed from the rotation direction of the blade 142 (referred to as the rotation direction surface). .

[0005]

According to the above-mentioned prior art, as shown in the explanatory view showing the state of the vortex flow in FIG. 5, the impeller 140 is rotated at a high speed in the direction of arrow R in the drawing to generate the vortex ( (Refer to the thick arrow in the figure). Further, the back surface of the blade 142 of the impeller 140 in the rotation direction (141
Negative pressure (see the portion indicated by the small circle group in the figure) occurs in the vicinity of a). In FIG. 5, (a) is a sectional view of the blade groove, (b).
FIG. 4 is a partial end view of the impeller. Therefore, the blade groove 14
As a result of the fuel flowing out of 1 being drawn in by the negative pressure, a turbulent flow as shown by an arrow t in FIG.

Therefore, the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an electric fuel pump capable of improving deterioration of pump efficiency due to generation of turbulent flow. .

[0007]

The present invention for solving the above-mentioned problems is an electric fuel pump for boosting the fuel pressure by rotating a disc-shaped impeller having a large number of blade grooves on the outer periphery by driving a motor section. Then, the front wall surface of the impeller blade groove in the direction of rotation is set to be an inclined surface that is inclined rearward at an angle θ with respect to a straight line orthogonal to the end surface of the impeller.

[0008]

According to the above-described means, the vortex flow near the wall surface smoothly flows due to the inclined surface of the rotating front wall surface in the blade groove of the impeller, the negative pressure is hardly generated in the vicinity thereof, and the turbulent flow due to the negative pressure Is also eliminated.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. FIG. 3 shows a sectional view of a swirl type electric fuel pump. Referring to FIG. 3, the electric fuel pump includes a DC motor unit 2 incorporated in a cylindrical metal housing 1.
And a pump part 3 incorporated in the lower part thereof.

In the motor section 2, a synthetic resin motor cover 5 and a pump cover 6 are attached to the upper and lower ends of the housing 1, and a motor chamber 8 is formed in the housing 1. An armature 10 is arranged in the motor chamber 8, and upper and lower ends of a shaft 12 of the armature 10 are rotatably supported by the covers 5 and 6 via bearings 13 and 14, respectively. Armature 1
The lower end of the shaft 12 of 0 extends to the pump unit 3.

A pair of magnets 15 are fixed to the inner peripheral surface of the housing 1. A brush 16 which is in sliding contact with the commutator 10a of the armature 10 is installed in the motor cover 5 while being urged by a spring 17. The brush 16 is a choke coil 18
Is electrically connected to an external connection terminal (not shown) via.
Further, the motor cover 5 is provided with a fuel outlet 20 for connecting a fuel supply pipe (not shown) leading to, for example, a fuel injection valve of an automobile engine. At the fuel outlet 20,
A check valve 21 for preventing the reverse flow of fuel is incorporated in a state of being biased in the closing direction by a spring 22.

Further, in the pump portion 3, a center plate 24 and a pump body 7, which are sequentially located below the pump cover 6, are attached to a lower end portion of the housing 1. The pump cover 6 and the center plate 2
4 and pump body 7 for pump casing (code omitted)
Is configured. Between the pump cover 6 and the center plate 24, and between the center plate 24 and the pump body 7.
A disk-shaped impeller 4 having a large number of vane grooves 41 on the outer circumference is disposed between and. Both impellers 4
Are connected to the shaft 12 of the armature 10 by fitting.

Each impeller 4 is attached to the pump casing.
The upper and lower sides of the C-shape corresponding to the blade groove 41 on the outer periphery of the
A stepped channel 9 is formed. A lower end of the flow passage 9 communicates with a fuel intake port 26 provided in the pump body 7 and an end thereof communicates with a communication port 28 provided in the center plate 24. In addition, the upper channel 9 is
The start end communicates with the communication port 28 of the center plate 24, and the end end communicates with the fuel discharge port 27 provided in the pump cover 6. In FIG. 3, the fuel intake port 26, the fuel discharge port 27, and the communication port 28 are shown to be on the same line, but in reality, they are in a positional relationship that they deviate from each other by a predetermined angle.

In the electric fuel pump, the impeller 4 of the pump unit 3 is rotated by driving the motor unit 2 using a battery (not shown) of an automobile or the like as a power source. As a result, the fuel in the fuel tank is pumped up from the fuel intake port 26 to the lower flow passage 9. The pumped fuel is pressurized by the rotation of the impeller 4 while passing through each flow path 9, is discharged from the fuel discharge port 27 and enters the motor chamber 8, and is then discharged from the fuel outlet 20 of the motor cover 5.

The impeller 4 in the electric fuel pump will be described in detail with reference to the explanatory view of FIG. In Figure 1,
(A) is an end view, (b) is a perspective view, (c) is an explanatory view of the flow of fuel, (d) is a sectional view of a blade groove. Impeller 4
As shown in FIGS. 10A and 10B, the disk has a disk shape, and a large number of blade grooves 41 are formed on the outer peripheral portions of both front and back surfaces thereof with an intermediate wall 43 interposed therebetween. The blade groove 41 is formed between a large number of blades 42 having an equal pitch.

When the impeller 4 is rotated by the drive of the motor section 2, each blade 42 produces a swirl flow in the fuel to increase the fuel pressure. This vortex flow is indicated by a thick arrow in FIG.

The blades 42 of the impeller 4 are formed in a substantially right angle shape with a predetermined thickness with respect to the intermediate wall 43, as shown in FIG. The rotational rear wall surface 41b of the blade groove 41 of the impeller 4 as viewed in the rotational direction (see arrow R in the drawing) is a surface orthogonal to the end surface 4a of the impeller 4. The rotating rear wall surface 41b of the blade groove 41 corresponds to the surface of the blade 42 as viewed in the rotating direction (referred to as the rotating surface). The front wall surface 41a of the impeller 4 in the blade groove 41 is set to be an inclined surface that is inclined rearward at an angle θ with respect to a straight line L orthogonal to the end surface 4a of the impeller 4. The blade groove 41
The rotating front wall surface 41a in (1) corresponds to the rear surface (referred to as the rear surface in the rotational direction) viewed from the rotation direction of the blade 42.

According to the electric fuel pump provided with the impeller 4, as shown in the explanatory view showing the state of the vortex in FIG. 2, the vortex generated by the impeller 4 being rotated at high speed in the direction of the arrow R in the drawing (in the drawing, , Refer to the thick line arrow), the flow near the wall surface becomes smooth due to the inclined surface of the rotating front wall surface 41a in the blade groove 41 of the impeller 4.
In FIG. 2, (a) is a sectional view of the blade groove, and (b) is a partial end view of the impeller. Therefore, the negative pressure generated in the conventional one is almost eliminated, and the turbulent flow caused by the negative pressure is prevented or reduced, thereby improving the pump efficiency.

[0019]

According to the fuel pump of the present invention, since the vortex near the wall surface smoothly flows due to the inclined surface of the rotating front wall surface in the blade groove of the impeller, negative pressure and turbulent flow due to the negative pressure are generated. Prevented or reduced, thus improving pump efficiency.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an impeller.

FIG. 2 is an explanatory view showing a state of a vortex flow by the impeller of FIG.

FIG. 3 is a cross-sectional view showing an electric fuel pump.

FIG. 4 is an explanatory diagram showing a conventional impeller.

5 is an explanatory view showing a state of a vortex flow by the impeller of FIG.

[Explanation of symbols]

 4 Impeller 4a End face 41 Blade groove 41a Wall surface

Claims (1)

[Claims] 1. An electric fuel pump for increasing fuel pressure by rotating a disk-shaped impeller having a large number of blade grooves on the outer periphery by driving a motor unit, wherein a rotating front wall surface of the blade groove of the impeller is provided. An electric fuel pump having an inclined surface that is inclined rearward at an angle θ with respect to a straight line orthogonal to the end surface of the impeller.