Mitsuba Corporation

Mitsuba Electric Manufacturing Co., Ltd.

Susumu Aoki

Tsugio Onodera

Tadao Kodaira

Hideki Furuuchi

Chikafumi Sugai

Hideaki Abe

Yoshiaki Taniguchi

Wataru Mochizuki

Yasuhiro Kanai

Hideyuki Ogawa

Akihito Miyamoto

In molding coils wound around a motor rotor with resin material in a die assembly, the coil ends projecting from either axial end of the motor core are compressed radially inward by small diameter portions formed in the die surface. Because the unnecessary deposition of the resin material over the coil ends is minimized, the material cost can be reduced. Also, the elimination or the reduction of the need to eliminate excess resin material from the coil ends simplifies the production process, and reduces the production cost. Additionally, the reduction in the mass of the resin material over the coil ends, as well as the constraining of the coil wire into a relatively radially inner parts reduces the moment of inertia of the motor rotor, and can thereby improve the performance of the motor.

Device and method for molding motor coils

In an electric motor comprising a cylindrical yoke having a side wall at one end portion thereof, a driver unit for controlling and driving the electric motor is contained at an end portion in the side of the side wall in the yoke. A power supply opening portion through which inside and outside of the yoke communicate with each other and a signal line opening portion are formed in the side wall, and an electric connection to the driver unit is made through these portions. The driver unit is provided inside the yoke with FETs thereof kept in direct contact with the side wall. Also, a driver unit which integrates drive control circuitry with a brush holder may be provided and fixed on the outer surface of the side wall. In this case, an opening portion through which inside and outside of the yoke communicate with each other is formed in the side wall, and a brush is inserted through these portions. A driver unit is attached to a yoke with FETs thereof kept in direct contact with the side wall. As a result, in an electric motor having a power supply section provided deep in the yoke closed at its one end, the control drive section and the apparatus body can be integrally provided with each other without hindering the assembling operation.

Motor and electric power steering device

A power steering system to reduce the moment of inertia of the torque limiter and to accurately determine pressing force by a forcing member is provided. The torque limiter has a substantially-cylindrical limiter cover combined with and rotatable together with one of the output and input shafts; a limiter plate which is contained in the limiter cover and is combined with and rotatable together with the other of the output and input shafts; and a forcing member for forcing the limiter plate toward the limiter cover. The limiter cover has projecting portions formed in a circumferential line of the limiter cover by a cylindrical portion of the limiter cover that is deformed toward the inside, a disk-shaped plate is disposed between the projecting portions and the forcing member, and the forcing member, and the forcing member is supported by the projecting portions.

Torque limiter having cover with internal projecting portions to support forcing member of limiter plate

A power steering system to reduce the moment of inertia of the torque limiter and to accurately determine pressing force by a forcing member is provided. The torque limiter of the system has a basic structure in which a substantially-cylindrical rotating member which is rotatable together with one of the output shaft and the input shaft; and a rotated member which is rotatable together with the other of the output shaft and the input shaft, and which is forced toward the rotating member side by a forcing member supported by the rotating member. Typically, the rotating member is a substantially-cylindrical limiter cover with a bottom, and the rotated member is a limiter plate contained in the limiter cover. The forcing member may be supported by a concave portion formed in an inner-peripheral area of the limiter cover, or may be supported by a projecting portion which is formed by deforming the cylindrical portion of the limiter cover toward the inside. In the above basic structure, the rotated member may separately comprise a cylindrical portion, on the inner-peripheral surface of which plural splines are formed in parallel with its axial direction, these splines being engaged with the splines formed in the outer-peripheral surface of the other of the output shaft and the input shaft; and a flange portion, which is forced toward the rotating member side, by which the flange portion functions as a friction clutch. In this structure, efficiency of forming the limiter plate can be improved.

Power steering system

In an electric power steering device, a yoke made of a tubular member and carrying permanent magnets, and a hollow motor shaft coaxially and rotatably received in the yoke to carry a motor armature which cooperates with the permanent magnets to form an electric motor for the power steering device, a section of the yoke extending from an axial end thereof to a part thereof surrounding an axial end of the motor shaft defines an inner diameter which is greater than an outer diameter of the nut member so that the output torque of the electric motor can be measured during the course of assembling the power steering device by allowing a testing tool to be inserted from the open end of the yoke without any interference and to be applied to a suitable part of the nut member or the motor shaft. Thus, the performance of the electric motor can be directly evaluated before the power steering device is fully assembled so that any faulty electric motor can be either rejected or repaired before any further assembling work is conducted.

Electric power steering device

In a brush holder device, in which an action-side end portion 22a of a torsion spring 22 is engaged with a torsion spring engaging groove 25 recessedly provided in an end surface of the brush 24 on the side opposite to a commutator 23, so that the elastic force of the torsion spring presses the brush against the commutator 23, a first inclined surface 26 is formed in the end surface of the brush 24 so as to incline at an angle of 15.degree. relative to a plane perpendicular to the axis of the brush, and second inclined surface 27 is formed in the engaging groove 25, being superposed on the first inclined surface 26. Further, a pigtail 28 is connected to the brush at an offset point relative to the engaging groove 25. Because of the second inclined surface, the torsion spring can suppress so-called 'wild behavior' of the brush, and thereby, can prevent brush sound. The angle of inclination of the first inclined surface can be set at a small value, the brush can be molded using a molding die.

Brush holder device

Armature structure for motor

In bottoms of three bolt head receiving holes 26 of a stay body 11 made of resin, there are embedded respective collars 30 by insert molding, in such a manner that both end surfaces of each collar are exposed. In an outer peripheral surface of the collar body 31, a knurled portion 32 is formed to leave a non-knurled portion 33 in a lower end portion of the collar body 31. The collar 30 is embedded in the stay body by insert molding in such a state that a slightly chamfered seating surface 34 of the non-knurled portion 33 is slightly projected from a lower end surface of the stay body 11. Since a resin adhered portion is not formed on the seating surface of the non-knurled portion of the collar, the seating surface of the collar and a fastening surface 27 of a bracket 8 is fastened by bolts 29 to be in tight contact with each other, and the stay 10 and the bracket 8 can be maintained in desired parallelism.

Structure with a resin embedded fastener component

In a yoke arrangement for electric motors which are particularly suitable for use in electric power steering devices, the yoke comprises a first tubular portion, a second tubular portion which has a smaller diameter than the first tubular portion, and a tapered section connecting the two tubular portions. The length of the tapered sections is desired to be minimized so that the overall length of the electric motor may be minimized. Reducing the length of the tapered section and thereby increasing the taper angle of the tapered section leads to the reduction in the mechanical strength of the yoke against an axial force. To compensate for this reduction in mechanical strength, the wall thickness of the tapered section is made larger than that of the first portion. Thus, the overall mechanical strength of the yoke can be ensured with a minimum increase in the material cost and manufacturing cost. The yoke may be formed by plastic deformation such as swaging and expansion.

Yoke arrangement for an electric motor having an improved mechanical

Deformation absorbing grooves 16a are recessedly provided on the inner surfaces of both side walls 15a of a main body 15 of a brush holder made of resin in the sliding direction of a brush 44, and brush holding surface portions 16b holding both end edge portions of the outer surfaces of the brush are formed at edge portions of the grooves 16a on the inner surfaces of the side walls 15a. A pair of first reinforcing ribs 16c are projectingly provided at closing end sides of cutaway portions 18 and 19 on the outer surfaces of the both side walls 15a in the sliding direction of the brush, a pair of second reinforcing ribs 16d are projectingly provided at both top sides of the outer surface of a top side wall 15d for closing an end surface across the tops of the both side walls in the sliding direction of the brush, and an end portion 46a on the reaction side of a torsion spring 46 is engaged with an engageable portion 21A projectingly provided on the first reinforcing rib 16c.

Brush holder device and method of molding same

A labyrinth ring having a section of L-shape is radially, inwardly and integrally projected from the inner periphery of a brush holder stay of a motor. This labyrinth ring provides a labyrinth construction in a space portion extending from brushes and a ball and roller bearing in cooperation with the brush holder stay, a commutator, a bearing holder and a distance ring. The thickness of this labyrinth ring is determined to be so thin as to increase the volume of a carbon accumulating space portion formed between the bearing holder and itself as large as possible.

Growing community of inventors

Kiryu, Japan

Susumu Aoki