JPH0754727A - Synthetic resin forming method for electric fuel pump and its rotor - Google Patents

Abstract

PURPOSE:To prevent entry of synthetic resin into a commutator slit part in order to prevent contact of a brush with the synthetic resin when a commutator piece is worn by providing a synthetic resin formed layer of which external surfaces are formed smoothly at a hook part on an iron core side rather than the bottom part of a flat type commutator. CONSTITUTION:In the motor rotor 2 of an electric fuel pump, a synthetic resin mold layer 18 is formed by sealing a hook part 7a for connecting a coil 6 part and a coil storing slot of an iron core 5 in which the coil 6 is inserted and a coil 6 to a flat commutator 7 more on an iron core 5 side than the bottom part 7e of the flat commutator 7 and filling synthetic resin material by using a metallic mold so that its external surfaces are finished smooth. By this, because entry of synthetic resin into a slit 7d part is prevented, so that molding pressure can be increased. If the molding pressure can be set higher, circulation of synthetic resin molding material may be improved to reduce production of voids in the coil storing slot, etc., and such a problem that the dynamic balance of the rotor 2 is lost may be solved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is used, for example, for feeding fuel to an internal combustion engine for a vehicle.
In particular, the present invention relates to an electric fuel pump configured such that fuel passes through the inside of a motor portion and is discharged, and a synthetic resin molding method for a rotor thereof. An electric fuel pump device of this type is usually used by immersing it in a fuel tank.

[0002]

2. Description of the Related Art FIG.
FIG. 6 is a cross-sectional view showing a conventional electric fuel pump disclosed in Japanese Patent Publication No. In the figure, reference numeral 1 denotes a tubular housing, which is composed of a pump portion located at a lower portion and a motor portion located above the pump portion. The motor unit includes a rotor 2, a stator 3 formed of a permanent magnet, a brush 4, and the like.
The rotor 2 supports an iron core 5 having laminated magnetic plates, a coil 6 wound around a slot of the iron core 5, a flat commutator 7 that supplies a current to the coil 6, and the iron core 5 and the flat commutator 7. And a motor shaft 8 that operates. The stator 3 is fixed to the inner peripheral surface of the housing 1 so as to face the iron core 5 of the rotor 2. The brush 4 is installed so as to abut the flat commutator 7, and is constantly pressed by the spring 9.

The pump portion is partitioned by a pump cover 10 fitted to the lower end of the housing 1 and a pump base 11 which forms a boundary with the motor portion, and an impeller 12 is rotatably arranged between them. At the outer peripheral edge of the impeller 12,
A large number of vane grooves 12a having a pump function are formed and fitted in a pump chamber 13 formed by a pump cover 10 and a pump base 11. Pump cover 10,
A fuel intake port 14 and a pump chamber outlet 15 are provided in the pump base 11 at a position facing the pump chamber 13. The center of the impeller 12 is connected to the motor shaft 8 extended from the motor section. In the above configuration, when a voltage is applied to the brush 4 connected to the external power source, a current flows from the brush 4 to the coil 6 via the flat commutator 7 and the rotor 2 rotates. This rotation causes the impeller 12 to rotate and suck the fuel from the fuel suction port 14. The pressure of the sucked fuel is increased in the pump chamber 13, passes through the pump chamber outlet 15, enters the motor chamber 16, and is discharged from the fuel discharge port 17 to the outside.

As shown in FIGS. 6 and 7, the rotor 2 has a coil 6 portion and a coil housing of the iron core 5 containing the coil 6 for the purpose of reducing the stirring resistance of the fuel flowing in the motor chamber 16. The slot 5a and the coil 6 are connected to the flat commutator 7
The hook portion 7a for connecting with is sealed with a synthetic resin material to make the surface smooth. That is, the synthetic resin molding layer 18 is formed by casting using a mold, and the coil 6 portion, the coil housing slot 5a, and the hook portion 7a of the flat commutator 7 are hermetically sealed so that the resistance during rotation is reduced. I have to. The flat commutator 7 is formed by integrally forming a commutator base 7g made of a synthetic resin on a brim-shaped commutator material and then forming a predetermined number of commutator pieces 7c by inserting slits 7d. is there.

[0005]

The conventional electric fuel pump 6 is constructed as described above, and as shown in FIG.
Since the hook tip portion 7b of the flat commutator 7 is at substantially the same height as the bottom portion 7e of the flat commutator 7, the hook tip portion 7b is formed.
In order to seal the above parts with the synthetic resin molding layer 18, the portion of the synthetic resin molding layer 18 overlaps the opening 7f of the slit 7d. Therefore, when molding the synthetic resin molding layer 18,
When the molding pressure is set high, the slit 7d of the flat commutator 7
The outflow portion 18a of the synthetic resin molding layer 18 enters the portion of FIG. Since the outflow portion 18a overlaps with the position of the brush 4, there is a possibility that the brush 4 and the outflow portion 18a of the synthetic resin molding layer 18 may come into contact with each other when the commutator piece 7c is worn, resulting in abnormal wear of the brush 4.

Further, if the molding pressure is set low in order to prevent the synthetic resin from entering the slit 7d, the circumference of the synthetic resin molding material (also called the flow of the synthetic resin molding material) is bad, and as shown in FIG. A void 18b is generated in the synthetic resin molding layer 18 in each coil storage slot 5a of the iron core 5. When the voids 18b are generated, the fuel in the motor chamber 16 that has been boosted when the pump is operating is discharged from the surface of the rotor 2 into the voids 1
If the voids 18b penetrate into the inside of 8b due to a capillary phenomenon and the position where the voids 18b are generated is deviated, there is a problem that the dynamic balance of the rotor 2 is disturbed and the vibration is increased to deteriorate the quietness of the electric fuel pump. Therefore, the setting range of the molding pressure of the synthetic resin molding layer 18 has to be set within a narrow range due to the above-mentioned limitation, and there is a problem that manufacturing control is difficult and productivity is deteriorated.

The present invention has been made to solve the above problems, and intrusion of a synthetic resin which causes abnormal wear of the brush due to contact between the brush and the synthetic resin molding layer when the commutator piece is worn. It is also an object of the present invention to provide an electric fuel pump with high productivity without the occurrence of voids that prevent the occurrence of voids and that increase the vibration of the rotor due to an unbalanced dynamic balance and deteriorate the quietness.

[0008]

An electric fuel pump according to the present invention includes a permanent magnet stator disposed in a cylindrical housing, and a flat commutator mounted on a coil wound around an iron core slot. An electric fuel pump including a motor unit having a rotor adapted to supply electric current through the motor unit, and a pump unit configured to discharge the fuel sucked and rotated by the motor unit through the inside of the motor unit. In the above, in the slot portion of the iron core of the rotor of the motor portion, the coil portion, and the hook portion that is closer to the iron core than the bottom portion of the flat commutator, the synthetic resin molding layer having a smooth outer surface is provided. is there. Further, the hook portion of the flat commutator is arranged so that it is closer to the iron core than the bottom portion of the flat commutator.

Further, as a method of providing the synthetic resin molding layer on the rotor, a cooling medium passage for cooling the flat commutator is provided in the molding die facing the flat commutator in the molding die.
The flat commutator is cooled while the synthetic resin molding material is injected.

[0010]

In the electric fuel pump constructed as described above, since the synthetic resin is prevented from entering the slit portion of the flat commutator, even if the commutator piece is worn, the brush and the synthetic resin molding layer contact each other. There is no.

Further, since the molding pressure can be set high, the synthetic resin molding material can be easily wrapped around, and voids can be prevented from being generated in the coil housing slots of the iron core.

[0012]

【Example】

Example 1. FIG. 1 is a perspective cross-sectional view of an essential part showing an embodiment of the present invention, in which the same or corresponding parts as in the prior art are designated by the same reference numerals and the description thereof will be omitted. In the figure, the structure of the iron core 5, the coil 6, the flat commutator 7, and the motor shaft 8 is the same as that of the conventional one. The synthetic resin molding layer 18 is provided on the iron core 5 side with respect to the bottom surface portion 7e of the flat commutator 7 so that the coil 6 portion and the coil housing slot 5 of the iron core 5 containing the coil 6 are formed.
The hook portion 7a for connecting a and the coil 6 to the flat commutator 7 is hermetically sealed and a synthetic resin material is cast using a mold so that the outer surface becomes smooth.

According to the above structure, since the synthetic resin is prevented from entering the slit 7d, the molding pressure can be increased. If the molding pressure can be set to a high level, the synthetic resin molding material can be easily rotated, the occurrence of voids in the coil housing slots 5a and the like can be reduced, and the problem that the dynamic balance of the rotor 2 is lost can be solved.

Example 2. In the first embodiment, the tip 7b of the hook portion 7a of the flat commutator 7 has substantially the same height as the bottom portion 7e of the flat commutator 7, but the bottom portion 7e is different due to variations in the connection work with the coil 6. Can be higher than. In this case, since the synthetic resin molding layer 18 is formed so as to be closer to the iron core 5 than the bottom surface portion 7e of the flat commutator 7, the synthetic resin is prevented from entering the slit 7d. However, if the tip portion 7b of the hook portion 7a is exposed, the stirring resistance of the fuel flowing in the motor chamber may increase. Therefore, in this embodiment, as shown in FIG. 2, the position of the hook portion 7a is set to the bottom portion 7 of the flat commutator 7.
It was arranged so as to be closer to the iron core 5 side than e. According to this embodiment, in addition to preventing the synthetic resin from entering the slit 7d, the problem of increase in fuel stirring resistance due to the exposure of the tip 7b of the hook 7a does not occur.

Example 3. According to the configuration of the second embodiment,
Since the hook portion 7a becomes long, the flat commutator 7 may be expensive to manufacture. That is, since the flat commutator 7 is usually formed by forging together with the hook portion 7a, not only the machining becomes difficult but also the thickness of the flat commutator 7 must be increased. The thicker the flat commutator 7 is, the larger the outer dimensions of the electric fuel pump are. Therefore,
In this embodiment, as shown in FIG. 3, a sealing member 20 made of an insulating material is provided around the side surface of the flat commutator 7, and a synthetic resin molding layer 18 is provided up to the sealing member 20. . According to this embodiment, the hook portion 7a is located at the position of the flat commutator 7.
It is not necessary to consider a special arrangement such that the iron core 5 side is located further than the bottom surface portion 7e.

Example 4. The embodiment shown in FIG. 4 relates to a method of molding the synthetic resin molding layer 18 for the rotor 2.
That is, 32 is a molding die, and 32c is a synthetic resin material injection port. Reference numeral 32b is a refrigerant passage for cooling the flat commutator 7, and is arranged so as to face the entire upper surface side of the flat commutator 7. In the case of molding, the synthetic resin molding material is injected while cooling the mold and the flat commutator 7 by passing the refrigerant through the refrigerant passage 32b. According to such a molding method, since the synthetic resin molding material is injected while the mold and the flat commutator 7 are cooled, even if the synthetic resin molding material enters the slit 7d, the synthetic resin molding material is injected. The material does not harden and penetrate into the slit 7d. In other words, as shown in FIG. 4, even if the synthetic resin molding layer 18 is provided up to the position facing the side circumference of the flat commutator 7, the injected synthetic resin molding material should be before entering the slit 7d. Since heat is taken away by the mold and the flat commutator 7 to cure, the synthetic resin molding material does not enter the slit 7d even if the molding pressure is set high.

[0017]

As described above, according to the present invention, since the synthetic resin is prevented from entering the slit portion of the flat commutator, even if the commutator piece is worn, the brush and the synthetic resin molding layer come into contact with each other. And the problem of abnormal brush wear is eliminated. Further, since the molding pressure can be set high, the synthetic resin molding material can be easily wrapped around, the occurrence of voids in the coil housing slots of the iron core, etc. can be prevented, and a well-balanced rotor can be obtained. It should be noted that the fact that the molding pressure can be set to a high value makes the electric fuel pump with high productivity and easy setting of molding conditions.

[Brief description of drawings]

FIG. 1 is a perspective sectional view of essential parts of a rotor according to a first embodiment of the present invention.

FIG. 2 is a perspective sectional view of a main part of a rotor according to a second embodiment of the present invention.

FIG. 3 is a perspective sectional view of a main part of a rotor according to a third embodiment of the present invention.

FIG. 4 is a sectional view of an essential part showing a method of molding a rotor according to a fourth embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a conventional electric fuel pump.

FIG. 6 is a perspective sectional view of an essential part of a rotor showing a conventional electric fuel pump.

7 is a cross-sectional view taken along the line AA of FIG.

[Explanation of symbols]

 1 Housing 2 Rotor 5 Iron Core 5a Coil Storage Slot 6 Coil 7 Flat Commutator 7a Hook Part 7d Slit 7e Bottom Part 18 Synthetic Resin Molding Layer 32 Molding Mold 32b Refrigerant Passage

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[Procedure amendment]

[Submission date] August 23, 1994

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Claims (4)

[Claims] 1. A stator made of a permanent magnet arranged in a tubular housing, and a rotor adapted to supply a current to a coil wound around a slot of an iron core through a flat commutator. An electric fuel pump comprising: a motor section having the motor section; and a pump section configured to discharge the fuel that is rotatably driven by the motor section through the inside of the motor section, wherein a slot portion of an iron core of a rotor of the motor section is provided. An electric fuel pump comprising: a coil portion; and a hook portion that is closer to the iron core than a bottom portion of the flat commutator, a synthetic resin molding layer having a smooth outer surface. 2. The electric fuel pump according to claim 1, wherein the hook portion of the flat commutator is arranged so as to be closer to the iron core than the bottom surface of the flat commutator. 3. The flat commutator is provided with a sealing member formed of an insulating material on a side circumference thereof, and a synthetic resin molding layer is provided up to the sealing member. Item 2. The electric fuel pump according to item 2. 4. A rotor having an iron core mounted on a rotating shaft and a flat commutator connected to a coil wound around a slot of the iron core through a hook portion is arranged in a molding die. Then, in the method of molding synthetic resin, in the molding die,
An electric fuel pump characterized in that a refrigerant passage for cooling the flat commutator is provided in a portion of the mold facing the flat commutator, and the synthetic resin molding material is injected while cooling the flat commutator. Method of molding synthetic resin for rotor.