JP2510153B2 - Fluid pump - Google Patents

Description

TECHNICAL FIELD The present invention relates to a motor-driven fluid pump, for example, a fluid pump suitable for use as a fuel pump for an automobile.

[Prior art]

A conventional fluid pump of this type used for discharging fuel is disclosed in Japanese Patent Laid-Open No. 119959/1983. As shown in FIG. 2, this conventional fluid pump 1 has a motor section 10 and a pump section 20. The motor unit 10 has a pair of magnets 12 fixed to the inner peripheral surface of the motor housing 11 and an armature 13 rotatably arranged in the magnets 12. Armature 13
Includes a shaft 131, a core 132 mounted on the shaft 131 and including a core sheet and a winding coil, and a commutator 133 provided adjacent to the core 132.

The pump unit 20 includes an impeller 21 mounted at an end opposite to the commutator 133 with the core 132 of the shaft 131 of the armature 13 interposed therebetween. A pump housing 22 that defines the fluid flow path of the.

The fuel pump 1 is usually arranged in a fuel tank of an automobile such that the motor unit 10 and the pump unit 20 are in series in the direction of gravity, that is, in the posture shown in FIG. In this configuration, the shaft 13 of the armature 13
The axial force acting on 1 is equal to the total force of the self-weight of the armature 13, the spring force of the brush spring 14 pushing the armature 13 via the brush 15, and the magnetic attraction force acting between the magnet 12 and the armature 13. . To support this resultant force, a metal pin press-fitted into the pump housing 22
The head of 23 receives shaft 131 of armature 13.

〔problem〕

The spring force and the magnetic attraction force act in the direction of pressing the head of the pin 23. Therefore, the pin 23 and the tip of the shaft 131 are worn after long-time use. Furthermore, when the armature is arranged in the posture shown in FIG.
The own weight of 13 also acts on the head of the pin 23, further increasing wear.

Further, in order to suppress the shake of the brush 15, it is preferable to reduce the protrusion amount L of the brush 15 from the end surface 16a of the brush housing 16, that is, the distance L between the end surface 16a of the brush housing 16 and the end surface of the commutator 133. . However, the error of this distance L appears when the errors of the pump housing 22, the pin 23, the magnet 12, and the brush housing 16 are superimposed. Therefore, it is difficult to control the distance L to be sufficiently small. The wear of the pin 23 and the shaft 131 was also one of the reasons why the distance L could not be made sufficiently small. The runout of the brush is a cause of reducing the efficiency of the fluid pump and generating noise.

Therefore, it is an object of the present invention to provide a fluid pump capable of suppressing an increase in brush runout.

[Means for solving problems]

In order to achieve this object, in the present invention, a means is provided in which the axial center of the motor armature core is displaced from the axial center of the magnet in the same direction as the pressing force of the biasing means by a predetermined amount. ing.

[Action]

By disposing the center of the core in the axial direction and the center of the magnet in the axial direction, the magnetic attraction force in the direction opposite to the biasing force of the brush can be generated in the armature. By adjusting the amount of deviation, it is possible to generate a magnetic attraction force in the opposite direction that overcomes or cancels the biasing force of the brush.

As a result, the amount of protrusion of the brush protruding into the space inside the motor housing can be kept small.

〔Example〕

Next, embodiments of the present invention will be described with reference to the accompanying drawings.

First, FIG. 1 shows a fluid pump of one embodiment of the present invention used for a fuel pump of an automobile. The fuel pump 1 has a motor section 10 and a pump section 20.

The motor unit 10 has a motor housing 11 made of iron and a brush housing 16 made of resin fixed to the end of the motor housing 11 by caulking. The motor housing 11 works as a yoke of the magnetic circuit of the motor section. A pair of magnets 12, 12 are fixed to the inner peripheral surface of the motor housing 11 so as to face each other, and an armature 13 is rotatably accommodated therein. The brush housing 16 is formed with two through holes 17 for accommodating the graphite brush 15 and the brush spring 14 that presses the graphite brush 15, and one end of each is closed at a terminal 18.

The pump unit 20 has a magnet inside the motor housing 11.
A first resin-made pump housing portion 221 fixed adjacent to 12 and a second resin-made pump housing provided adjacent to the first pump housing portion 221 and fixed to the motor housing 11 by caulking. A pump housing 22 consisting of a portion 222 is provided. A pump chamber that rotatably accommodates the impeller 21 is formed in the pump housing 22, and a substantially annular fluid passage 223 is defined between the pump housing 22 and the impeller 21. In addition, the pump housing 22
A suction pipe line 224 and a discharge pipe line 225 are formed therein.
A resin valve 226 for adjusting the discharge flow rate is installed in the middle of the discharge pipe line 225, and the fuel is pressure-fed to the engine through the resin outlet pipe 25.

The armature 13 has a shaft 131 and this shaft 131.
A core consisting of a core sheet and winding coil attached to the
132 and a commutator 133 provided adjacent to the core 132. The shaft 131 has a pump housing 22 and a brush housing 30 made of a sintered metal bearing 30.
It is supported by 16 and. The end of the shaft 131 opposite to the commutator 133 with the core 132 interposed therebetween is attached to the impeller 21. The commutator 133 is provided with a flat surface portion on the end surface in the axial direction at a right angle to the axial direction, and the brush 15 which receives the spring force of the brush spring 14 abuts and is pressed against the flat surface portion. An external power source (not shown)
The winding coil of the armature 13 is energized through the terminal 18, the brush spring 14, the brush 15, and the commutator 133. As a result, the armature 13 is excited, the motor rotates, and the pump operates. Therefore, fuel is pumped from the tank to the engine. 12V external power supply, rated speed 6000 [rpm], rated discharge pressure 10.8 x 10
[Pa] and a rated discharge flow rate of 80 [l / Hr] can be obtained.

In the armature 13, the center line CL1 of the core is a predetermined amount l (about 1 mm in this embodiment) with respect to the center line CL2 of the magnet 12, and is the same as the pressing force of the brush spring 14 to the brush 15. Direction). As a result, Armature 13 has about 2.9
A force of [N] to the brush side, that is, an upward force in the antigravity direction acts. Armature 13 has its own weight and brush spring 14
Since a total force of about 2.5 [N] with the spring force of is working in the direction of gravity, an upward force of about 0.4 [N] is eventually applied to the armature 13. This upward force is received by the tip of the shaft 131 coming into contact with the bottom of the shaft hole 19 provided in the brush housing 16.

The above-mentioned predetermined amount 1 should be determined in accordance with the total force of the armature's own weight and the spring force of the brush spring. It only needs to be sufficient to generate force.
According to this configuration, the factors that determine the amount L of protrusion of the brush from the end surface of the brush housing that affects the touch of the brush are the depth of the hole for the shaft and the length of the shaft 131 protruding from the commutator 133. Only. Therefore, it is more accurate to set the protrusion amount L to the necessary minimum (in this case, 0.2 mm to 0.6 mm), as compared with the conventional one in which dimensional errors of many members are overlapped and affected. And it can be done more easily. Further, by appropriately selecting the predetermined amount l of deviation, it is possible to generate a magnetic attraction force (that is, no upward force is generated) that cancels the resultant force of the armature's own weight and the spring force of the brush spring. . In that case, there is no contact between the tip of the shaft and the bottom of the shaft hole, wear of both can be prevented, and the protrusion amount L can always be kept constant.

In the pump of the present embodiment, the amount of protrusion of the brush can be determined with a small number of members, so it can be determined more accurately. Therefore, the shake of the brush can be prevented.

In addition, if a predetermined deviation causes a magnetic attraction force in the opposite direction that overcomes the biasing force of the brush and the armature's own weight, even if the shaft end is in contact with the pin as in the conventional one, both will wear. Can be suppressed. Further, as in the embodiment, the pin can be eliminated and the number of parts can be reduced. Furthermore, Akira Kai
There is no need to adjust the thrust force by the screw as disclosed in Japanese Patent No. 57-107842.

〔The invention's effect〕

In the present invention, since the wear of the end of the armature shaft protruding to the side opposite to the side where the brush is provided and the part in contact with this can be suppressed, the amount of protrusion of the brush does not increase, and therefore the brush It is possible to suppress an increase in the shake of the. This makes it possible to maintain a high level of pumping over a long period of use and prevent the generation of noise due to the vibration of the brush.

[Brief description of drawings]

FIG. 1 is a sectional view of a fluid pump according to an embodiment of the present invention, and FIG. 2 is a sectional view of a conventional fluid pump. 10 …… motor part, 12 …… magnet, 13 …… armature, 14 …… brush spring, 15 …… brush, 16 ……
Brush housing, 19 …… Shaft hole, 20 …… Pump part, 131 …… Shaft, 132 …… Core, 133 …… Commutator.

Claims (3)

(57) [Claims] 1. A fluid pump having a motor and a pump driven by the motor, wherein the motor is disposed in a space within a motor housing, and has a shaft protruding axially from one end and the other end. An armature having a flat commutator, a magnet surrounding the armature, a brush arranged parallel to the axis of the motor, and a pressing force parallel to the axis of the motor for urging the brush to the flat commutator. While abutting the brush from the axial direction, biasing means for projecting the brush into the space, and the axial center of the armature core is displaced in the same direction as the pressing force with respect to the axial center of the magnet. A fluid pump characterized by being arranged. 2. A fluid pump according to claim 1, wherein the axis of the motor is arranged so as to coincide with the direction of gravity. 3. The fluid pump according to claim 1 or 2, wherein the armature is positioned by abutting an end of the shaft protruding toward the side where the brush is provided. A fluid pump characterized in that