Motor-operated pump of intank type

Abstract: A motor-operated pump of the in-tank type comprising a motor (1) for driving the pump, the motor having a commutator (3); a bracket (9) covering one end of the motor (1) disposed adjacent to the commutator (3); a brush (4) held against the commutator (3) through a through hole formed in the bracket (9); and a bearing for supporting a shaft (5) of the motor. An annular projection (9d) is formed on a central portion of a surface of bracket (9) disposed in opposed relation to the commutator (3), and the annular projection (9d) is formed integrally with the bracket (9). Alternatively, an annular projection (3d) is formed on a central portion of the commutator (3) disposed in opposed relation to the bearing, and the annular projection (3d) is made of an electrically insulating material constituting the commutator (3), and is formed integrally with the commutator (3).

Description: BACKGROUND OF THE INVENTION This invention relates to a motor-operated pump of the in-tank type, and more particularly to a motor-operated pump of the in-tank type adapted to be sunk in a liquid fuel tank of a vehicle such as an automobile. Fig. 4 is a cross-sectional view of a conventional motor- operated pump of the in-tank type as disclosed in Japanese Laid-Open (Kokai) Patent Application No. 272994/88. In this Figure, reference numeral 1 denotes a motor serving as a pump drive source, reference numeral 2 denotes a rotor of the motor 1, reference numeral 3 denotes a commutator of the rotor 2, reference numeral 4 denotes a brush held in contact with the commutator 3 so as to supply electric power to the rotor 2, reference numeral 5 denotes a shaft of the rotor 2, reference numeral 6 denotes an impeller connected to the shaft 5 and forming the pump, reference numeral 7 denotes an intake port of the pump, reference numeral 8 denotes a pump casing, reference numeral 9 denotes a bracket of the motor 1, reference numeral 10 denotes a cover-out, reference numeral 10a denotes a discharge port of the pump, reference numeral 11 denotes a terminal mounted on the cover-out 10 so as to be supplied with electric power from the exterior, reference numeral 12 denotes a brush spring for urging the brush 4 against the commutator 3, and reference numeral 13 denotes a noise prevention device for preventing electrical noise. Bearings 8a and 9a are mounted on the pump casing 8 and the bracket 9, respectively. The bracket 9 has a through hole 9b receiving the brush 4. The conventional motor-operated pump of the in-tank type is constructed as described above, and when electric power is supplied to the terminal 11, the electric power is supplied to the rotor 2 via the noise prevention device 13, the brush 4 and the commutator 3. As a result, the rotor 2 is driven, and the impeller 6 connected to the rotor 2 is rotated, and fuel is drawn into the intake port 7 by the rotating impeller 7, and then is fed to an engine or the like (not shown) via the discharge port 10a. In the above-described conventional motor-operated pump of the in- tank type, the side 3a of the commutator 3 held in sliding contact with the brush 4 are disposed in opposed relation to the bracket 9 and the bearing 9a. Therefore, when the axially-movable rotor 2 is moved due to vibrations or the like, the brush-sliding contact surface 3a of the commutator 3 is brought into contact with a confronting surface 9c of the bracket 9 which results in a problem that the durability of the pump is adversely affected. Also, the brush-sliding contact surface 3a is brought into contact with the bearing 9a, which results in a problem that the performance of the pump is markedly lowered. A further prior art of a motor operated pump of the in-tank type that is of interest is that disclosed in US-A-3 676 025 that discloses all the features appearing in the pre-characterizing part of the accompanying Claim 1. In US-A-3 676 025 an annular projection is formed on a central portion of a surface of a bracket disposed in opposed relation to the commutator of the motor, said annular projection being formed integrally with said bracket. SUMMARY OF THE INVENTION The present invention has been made in order to overcome the above problems, and an object of the invention is to provide a motor-operated pump of the in-tank type in which stable performance of the pump is achieved by avoiding contact between opposed surfaces of a bracket and a commutator, thereby achieving a high reliability of the pump. According to the present invention, there is provided a motor-operated pump of the in-tank type comprising a motor for driving the pump, said motor having a commutator; a bracket covering one end of said motor disposed adjacent to said commutator; a brush held against said commutator through a through hole formed in said bracket; said bracket having a bore hole co-axial with the shaft of said motor; a bearing for supporting the shaft of the motor mounted within said bore hole; and an annular projection formed on a central portion of said commutator disposed in opposed relation to said bearing, said annular projection being made of an electrically insulating material constituting said commutator, formed integrally with said commutator and serving, should the bearing move toward the commutator, to prevent the commutator from being short circuited via said bearing. According to the invention, even if a rotor is moved due to vibrations, the annular projection is brought into contact with the bracket, thereby protecting the sliding contact surface. Further, the bearing is prevented from making contact with the sliding contact surface of the commutator. BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings: Fig. 1 is a vertical cross- sectional view of one example of the invention; Fig. 2 is a plan view of a commutator in Fig. 1; Fig. 3 is a cross- sectional view taken along the line III-III of Fig. 2; and Fig. 4 is a vertical cross-sectional view of a conventional motor- operated pump of the in-tank type. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Figs. 1 to 3 show an example of the invention, and in Figs. 1 to 4 identical reference numerals denotes the same parts respectively. A commutator 3 comprises a plurality of generally-fan shaped electrical conductor members 3b in sliding contact with a brush. Thus, the plurality of conductor members 3b constituting the commutator 3. An electrically insulating member 3c serves as a base member for the commutator 3, and holds the conductor members 3b. The commutator 3 has a central hole 3e through which a shaft 5 of a rotor 2 extends. An annular projection 3d is formed integrally with the insulating member 3c, and disposed in surrounding relation to the central hole 3e. A fuel feed operation in the construction of this embodiment is the same as that described with reference to Fig. 4, and therefore explanation thereof is omitted here. However, the annular projection 3d of an electrically insulating material is integrally formed on a central portion of a surface 3a of the commutator 3 disposed in sliding contact with a brush 4. Therefore, even when vibrations are imparted to the pump mounted on a vehicle or the like, the the brush-sliding contact surface 3a of the commutator 3 will not be brought into contact with a bracket 9, and only the annular projection 3d is brought into contact therewith. According to the invention, the annular projection of an electrically insulating material is formed integrally on the central portion of the brush-sliding contact surface of the commutator, and therefore the brush-sliding contact surface (the conductor portion) of the commutator can be protected, and a mechanical load due to the contact between the commutator and the brush can be kept to a minimum. Further, if the bearing should be moved toward the commutator, the commutator is prevented from being short-circuited via the bearing. This construction provides advantages such as low costs and an enhanced reliability.

Claims: A motor-operated pump of the in-tank type comprising a motor (1) for driving the pump, said motor having a commutator (3); a bracket (9) covering one end of said motor disposed adjacent to said commutator; a brush (4) held against said commutator through a though hole formed in said bracket; and wherein said bracket (9) has a bore hole co-axial with the shaft (5) of said motor (1) characterized in that a bearing (9a) for supporting the shaft (5) of the motor (1) is mounted within said bore hole; and an annular projection (3d) is formed on a central portion of said commutator disposed in opposed relation to said bearing, said annular projection (3d) being made of an electrically insulating material constituting said commutator (3), formed integrally with said commutator and serving, should the bearing (9a) move toward the commutator, to prevent the commutator from being short circuited via said bearing.

Inventors: IWAI SHINGO C O MITSUBISHI DEN, YOSHIOKA HIROSHI C O MITSUBISH, IWAI, SHINGO, C/O MITSUBISHI DENKI K.K., YOSHIOKA, HIROSHI, C/O MITSUBISHI DENKI K.K.
Applicants: MITSUBISHI ELECTRIC CORP, MITSUBISHI DENKI KABUSHIKI KAISHA
Application year: 1990
Main classification: F04D13
IPC codes: F04D13, H02K7, H02K5, H02K23, F02M37, H02K13, H01R39