JPH05240185A - Fuel pump - Google Patents

Abstract

PURPOSE:To avoid the fixing of a shaft to an impeller caused by the biting of dust in fuel between the fitting surfaces of the impeller and the shaft and solve inconveniences such as a reduction in discharge flow rate and an operation failure. CONSTITUTION:A fuel pump is formed of a motor part 16 consisting of a driving motor and a pump part 17 having an impeller 2 driven by the driving motor. The shaft 9 of the driving motor is fitted into the mounting hole 5 of the impeller 2 in such a manner as to be capable of sliding in the axial direction and locking in the rotating direction. A recessed part 15 is provided on the fitting surface of the shaft 9 to the impeller 2. The dust contained in a fuel penetrating between the fitting surfaces of the shaft 9 and the impeller 2 is entered to the recessed part of the shaft 9, whereby the biting of the dust between the fitting surfaces can be prevented or reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel pump, and in particular to a Wesco type electric fuel pump which is mounted in a fuel tank of an automobile or the like and pumps fuel to an engine.

[0002]

2. Description of the Related Art A fuel pump of this type is usually composed of a motor section composed of a drive motor and a pump section having an impeller driven by the drive motor. Then, as shown in the explanatory view of FIG. 6, for example, the shaft 109 of the drive motor has a mounting hole 1 formed in the impeller 102.
05 is slidable in the axial direction and is rotatable in the rotation direction. That is, the end portion of the shaft 109 is formed into a substantially D-shaped cross section by forming a planar stopper surface 109a, and the mounting hole 105 through which the shaft 109 is inserted is also formed into a shape corresponding to the cross sectional shape. The shaft 109 is fitted in the mounting hole 105. 6A is a longitudinal sectional view of a main part, and FIG. 6B is a lateral sectional view thereof. Further, a seal portion clearance having a predetermined clearance is set between the axial end surface of the impeller 102 and the upper and lower wall surfaces of the pump chamber facing the axial end surface, and a part of the fuel is introduced into the clearance by utilizing the rotation of the impeller 102. By doing so, a centering function of the impeller 102 (also referred to as a seal portion clearance automatic adjusting function), such as holding the impeller 102 at the neutral position between the wall surfaces of the pump chamber with the fuel pressure, is imparted.
Smooth rotation of the impeller 102 is ensured. In addition,
The fuel pump as described above includes, for example, an actual Kaihei 2-10.
There is a 3193 publication.

[0003]

According to the above-mentioned conventional fuel pump, a part of the fuel flowing through the pump fuel flow passage 111 passes through the seal portion gap to the connecting portion (fitting portion) between the shaft 109 and the impeller 102. Invade the surrounding area. As a result, the dust contained in the fuel is caught between the fitting surfaces of the shaft 109 and the impeller 102, and the impeller 1 is attached to the shaft 109 by the accumulation of the dust.
When 02 is tilted obliquely or is biased to the wall surface on the other hand, the shaft 109 and the impeller 102 are firmly fixed to each other, and the impeller 102 cannot slide. Then, since the function of adjusting the clearance of the seal portion is deteriorated,
Since the impeller 102 is kept in contact with the wall surface of the pump chamber, sliding resistance during rotation of the impeller 102 increases, which causes problems such as a decrease in discharge flow rate and malfunction, which in turn results in durability and reliability. Affect. The dust is not only a mixture of sand and dust from the outside of the fuel tank,
In the case of methanol fuel, there are corrosive substances such as iron and aluminum due to water content contained in the fuel, and viscous extracts such as rubber and adhesive due to methanol.

Therefore, the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a shaft and an impeller by engaging dust in fuel between the fitting surfaces of the impeller and the shaft. An object of the present invention is to provide a fuel pump capable of avoiding sticking and improving problems such as reduction in discharge flow rate and malfunction.

[0005]

A fuel pump according to the present invention for solving the above-mentioned problems comprises a motor section composed of a drive motor and a pump section having an impeller driven by the drive motor. In a fuel pump in which a shaft is fitted in a mounting hole of the impeller so as to be slidable in its axial direction and non-rotatable in its rotational direction, a recess is provided on a fitting surface of the shaft with the impeller.

[0006]

According to the above-mentioned means, the dust contained in the fuel that enters between the fitting surfaces of the shaft and the impeller enters the recess of the shaft, so that the dust is caught between the fitting surfaces. Are prevented or reduced.

[0007]

Embodiments of the present invention will be described with reference to the drawings. [Embodiment 1] An example of a fuel pump is shown in a sectional view in FIG. What is shown in the figure is an in-tank type electric fuel pump provided in a fuel tank of an automobile or the like for driving a Wesco type pump by a brushless motor. The fuel pump is composed of a motor unit 16 including a drive motor such as a well-known brushless motor, and a pump unit 17 having an impeller 2 attached below the motor unit and driven by the motor.

The motor section 16 will be described. A shaft holder 21 and a pump cover 7 assembled in a substantially cylindrical housing 20 rotatably support the upper and lower ends of a shaft 9 of a drive motor via bearings 22 and 23, respectively. At the center of the shaft 9, a rotor 24 made of a multi-pole permanent magnet is fixed via a collar 25. A rotor cover 26 is provided on both end surfaces of the rotor 24.
Is installed. In the housing 20, a stator 27 is arranged around the rotor 24 at a predetermined distance.
Is fixed. The stator 27 is formed by laminating a plurality of thin plates 28 made of a ferromagnetic material and winding a coil 29 around the thin plates 28. The upper end of the shaft 9 is projected from the upper surface of the shaft holder 21. A support plate 31 having a sensor magnet 30 for detecting the rotational position of the rotor 24 arranged on the outer periphery is attached to this end portion.

A pressing holder 32 is attached to the housing 20 so as to be located on the shaft holder 21. A control circuit case 3 is provided between the holders 21 and 32.
3 is held. The circuit case 33 accommodates a board on which an electronic control circuit including a position detecting element sensitive to the sensor magnet 30 is mounted. The control circuit case 33 and the presser holder 32 are provided with a fuel passage 34 (the case-side fuel passage is not shown) through which the fuel passes from the lower side to the upper side in the figure. Further, a motor cover 35, which covers the upper opening surface of the housing 20 and is located on the holding holder 32, is attached to the housing 20. A fuel discharge port 36 is formed in the motor cover 35, and a check valve 37 is attached to the discharge port 36. Further, the motor cover 35 is provided with power supply terminals 38 and 39 for connecting an external power supply. The coil 29 and the control circuit are electrically connected to the terminals 38 and 39, respectively.

Next, the pump section 17 will be described with reference to the explanatory view of FIG. 1A is a vertical cross-sectional view of the main part, and FIG. 1B is a horizontal cross-sectional view thereof. The pump cover 1 includes a ring-shaped spacer 3 having two pump bodies 1.
And the center plate 4 located between the two spacers 3
It is assembled by the screw 8 via. As a result, upper and lower pump chambers (reference numeral omitted) are formed, and a pump part intermediate chamber 14 is formed so as to surround the lower end portion of the shaft 9 so as to communicate the two pump chambers. Further, the pump body 1 is formed with a pump portion inlet 10 which opens to the lower surface thereof and communicates with the lower pump chamber, and the center plate 4 is formed with a communication port 41 which communicates both pump chambers with each other. Is provided with a pump section outlet 12 that communicates the upper pump chamber with the internal space of the motor section 16.

A disk-shaped impeller 2 having a large number of blade grooves 2a for performing a pump function is arranged on the outer periphery of each pump chamber. Around the impeller of each pump chamber, from the pump section inlet 10 to the communication port 41
Alternatively, a pump fuel flow passage 11 is formed from the communication port 41 to the pump portion outlet 12.

A lower end portion of the shaft 9 is fitted in a mounting hole 5 formed in a central portion of each impeller 2 so as to be slidable in its axial direction and non-rotatable in its rotational direction. That is, the end portion of the shaft 9 is formed into a substantially D-shaped cross section by forming the stopper surface 9a having a planar shape, and the mounting hole 5 into which the shaft 9 is inserted is also formed into a shape corresponding to the cross sectional shape. The shaft 9 is fitted in the mounting hole 5. In addition, each impeller 2
A seal portion gap having a predetermined clearance, for example, a clearance of about 20 to 40 μm, is set between the axial end surface of and the upper and lower wall surfaces of the pump chamber facing the end surface.

A spiral groove 15 is formed in the shaft portion of the shaft 9 into which the impeller 2 is inserted. The spiral groove 15 has the same axis as the shaft 9 and has a spiral shape in a direction opposite to the rotation direction of the shaft 9 (in this example, the shaft plane, that is, the counterclockwise direction in FIG. 1B), that is, the right screw direction. I am doing it. Further, FIG. 1 shows that two spiral grooves 15 are provided with respect to the shaft 9 with a phase of 180 °. This spiral groove 15
Corresponds to the concave portion in the present invention.

In the fuel pump described above, when the drive motor is operated, the rotor 24 rotates and the impeller 2 is rotated.
Rotates. With the rotation of the impeller 2, the fuel is sucked from the inlet 10 of the pump portion, the pressure is increased while flowing through both pump fuel flow passages 11, passes through the outlet 12 of the pump portion, and passes through the internal space of the drive motor to the fuel outlet 36. It is discharged to the outside. Further, due to the rotation of the impeller 2, a part of the fuel is introduced into the gap between the axial end surface of the impeller 2 and the wall surface of the pump chamber facing the axial end surface, so that the centering function of the impeller 2 is achieved as in the conventional example. (Seal clearance automatic adjustment function) is added.

In the fuel pump, a part of the fuel flowing through the pump fuel flow passage 11 passes through the seal gap and the periphery of the connecting portion between the shaft 9 and the impeller 2, and is between the fitting surface between the shaft 9 and the impeller 2. Break into. Then, even if dust is contained in this fuel, the dust is introduced into the spiral groove 15 of the shaft 9,
Entrapment of dust between the fitting surfaces is prevented or reduced. Therefore, by preventing the shaft 9 and the impeller 2 from sticking to each other, it is possible to prevent the seal portion clearance automatic adjustment function from being impaired, and as a result, a stable discharge flow rate and operation can be obtained for a long period of time. Further, according to this example, as the shaft 9 rotates, the fuel flows along the spiral groove 15, and the dust is positively flowed down to the bottom of the intermediate chamber 14 of the pump portion. The dust is effectively discharged from the spiral groove 15.

[Second Embodiment] A second embodiment will be described with reference to FIG. 3A is a longitudinal sectional view, and FIG.
FIG. This example is the same as that of the following examples (Example 1).
Since a part (concave portion) of the above is modified, the modified part will be described in detail, and the duplicate description of the part that is considered to have the same or an equivalent configuration as the first embodiment will be omitted. In this example, instead of the spiral groove 15, an appropriate number of linear shafts are formed on the shaft 9 in the axial direction.
Two vertical grooves 15a are formed. In this case, the dust in the fuel enters the vertical groove 15a of the shaft 9 to prevent or reduce the dust from being caught between the fitting surfaces. The dust in this case is accumulated in the vertical groove 15a or flows to the bottom of the pump section intermediate chamber 14 by the flow of fuel in the vertical groove 15a. The fuel flow in the vertical groove 15a in this example is a flow due to the pressure difference between the pump chambers, and is a more passive flow than that in the first embodiment.

[Third Embodiment] A third embodiment will be described with reference to FIG. In this example, instead of the spiral groove 15 of the first embodiment, an appropriate number of lateral grooves 15 that are annular around the shaft 9 are provided.
b is formed.

[Fourth Embodiment] A fourth embodiment will be described with reference to FIG. In this example, in addition to the spiral groove 15 of the first embodiment, a spiral groove 15c in the opposite direction, that is, in the left-hand screw direction is formed to form a mesh shape.

[0019]

According to the present invention, by providing the shaft with the recess into which the dust contained in the fuel is introduced, it is possible to avoid sticking of the shaft and the impeller due to the entrapment of the dust, and for a long period of time. A stable discharge flow rate and operation can be obtained, which in turn can improve durability and reliability.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a main part of a first embodiment.

FIG. 2 is a sectional view of a fuel pump.

FIG. 3 is an explanatory diagram showing a second embodiment.

FIG. 4 is an explanatory diagram showing a third embodiment.

FIG. 5 is an explanatory diagram showing a fourth embodiment.

FIG. 6 is an explanatory diagram showing a conventional example.

[Explanation of symbols]

 2 Impeller 5 Mounting hole 9 Shaft 15 Spiral groove (recess) 16 Motor part 17 Pump part

Claims (1)

[Claims] 1. A motor unit including a drive motor and a pump unit having an impeller driven by the drive motor, wherein a shaft of the drive motor is slidable in a mounting hole of the impeller in an axial direction thereof. A fuel pump fitted so as to prevent rotation in the rotation direction, wherein a recess is provided on a fitting surface of the shaft with the impeller.