US 6,268,669 B1 · Electric motor for power steering device

Abstract

An electric motor 10 for an electric power steering system, in which a board mounting portion 23 of aluminum for partitioning an electric motor body 10A and a circuit board 40 is formed all over the inner side of a motor case 20 and in which a bearing 25 of an output shaft 11 of the electric motor body 10A is supported on the board mounting portion 23 to release the heat effectively from FETs 43 mounted on the circuit board 40 and the output shaft 11. On the other hand, pigtail wires 36 from brushes 33 are welded to brush leads 27 having a wide surface area so that the circuit board 40 may be prevented from rising to a high temperature at the welding time. A torque limiter 80 is interposed between the output shaft 11 and a worm shaft 92 in a worm case 90 to reduce the size of the entire system, and the cogging of the motor torque is suppressed by correcting the feed current to the electric motor body 10A on the basis of the position changes in a plurality of slits 101 which are formed in the outer circumference of a case 81 of the torque limiter 80 and in phase with the electrodes of a commutator 35.

Claims11

Dependent claims

An electric motor for an electric power steering system for applying an assisting force to a member to be steered, in accordance with an input torque inputted to an input member, comprising:

a motor case;
an electric motor body accommodated within said motor case;
a circuit board disposed within said motor case, said circuit board having a drive circuit installed thereon for driving said electric motor body, said circuit board further having a control circuit installed thereon for controlling said drive circuit;
a board mounting member formed across an inner space of said motor case as a wall partitioning said electric motor body and said circuit board, said board mounting member being made of a material having a high thermal conductivity and supporting a bearing of an output shaft of said electric motor body, which projects through said board mounting member toward said circuit board;
a lower case covering a lower side of said circuit board;
and
a torque limiter interposed between the output shaft of said electric motor body and a rotary shaft associated with said member to be steered, said torque limiter being accommodated in said lower case below said circuit board.

4 more elements

An electric motor for an electric power steering system for applying an assisting force to a member to be steered, in accordance with an input torque inputted to an input member, comprising:

a motor case;
an electric motor body accommodated within said motor case;
a circuit board disposed within said motor case, said circuit board having a drive circuit installed thereon for driving said electric motor body, said circuit board further having a control circuit installed thereon for controlling said drive circuit;
a board mounting member formed across an inner space of said motor case as a wall partitioning said electric motor body and said circuit board, said board mounting member being made of a material having a high thermal conductivity and supporting a bearing of an output shaft of said electric motor body, which projects through said board mounting member toward said circuit board;
a brush lead extending from a brush in sliding contact with a commutator of said electric motor body to said circuit board through said board mounting member, said brush lead having a wide surface area on the side of said brush;
an ECU lead extending from said circuit board and connected electrically with said brush lead;
and
a lead wire extending from said brush and welded to a part corresponding to the wide surface area of said brush lead.

5 more elements

Dependencies are inferred from the claim text.

Electric motor for power steering device

Life of this patent

Electric motor for power steering device

Life of this patent

Abstract

Claims11