Integrated electric power steering apparatus

1. An integrated electric power steering apparatus in which a control unit for controlling a motor is disposed inside a housing, said control unit is disposed so as to be coaxial to an output shaft of said motor, and in which said control unit and said motor are integrated, wherein:

said control unit includes a circuit board and an intermediate member;

main parts are mounted to said circuit board;

wiring is disposed on said intermediate member;

said circuit board and said intermediate member are stacked;

said parts are mounted to first and second surfaces of said circuit board; and

a portion of said housing and first surfaces of said parts disposed on the second surface of said circuit board are placed in direct contact or are placed in contact so as to have a heat-transferring member interposed,

wherein the second surface of said circuit board faces the motor.

2. The integrated electric power steering apparatus according to claim 1 , wherein:

said intermediate member comprises a plurality of busbars for wiring;

a surface of said intermediate member that faces said circuit board comprises a projecting portion; and

said projecting portion is placed in contact with said parts or said circuit board.

3. The integrated electric power steering apparatus according to claim 1 , wherein:

said housing is made of a metal; and

said intermediate member is disposed on an opposite side of said circuit board from said portion of said housing.

4. The integrated electric power steering apparatus according to claim 1 , wherein:

said control unit is disposed at an opposite end of said motor from an output shaft of said motor; and

said portion of said housing is a portion of a frame that forms a boundary between said motor and said control unit.

5. The integrated electric power steering apparatus according to claim 1 , wherein:

said control unit is disposed at an identical end of said motor to an output shaft of said motor; and

said portion of said housing is a portion of a unit case that is joined to a reduction gear upon which output from said motor acts.

6. The integrated electric power steering apparatus according to claim 4 , wherein parts that generate heat among said parts include at least parts that are placed in contact with said housing and parts that are placed in contact with said intermediate member.

7. The integrated electric power steering apparatus according to claim 6 , wherein:

said parts that are mounted to said first surface of said circuit board include switching elements, said switching elements being placed in direct contact with said portion of said housing or being placed in contact therewith by means of heat-transferring members; and

said parts that are mounted to said second surface of said circuit board are placed in direct contact with said intermediate member or are placed in contact therewith by means of heat-transferring members.

8. The integrated electric power steering apparatus according to claim 4 , wherein:

said circuit board, said intermediate member, and a unit case with connector are stacked side by side in order of closeness to said motor; and

said unit case with connector and said intermediate member are made of an insulating resin.

9. The integrated electric power steering apparatus according to claim 5 , wherein:

said intermediate member, said circuit board, and said unit case are stacked side by side in order of closeness to said motor;

said unit case is made of a metal; and

a portion of an outer circumference of said unit case is cut away and a connector is mounted thereto.

10. The integrated electric power steering apparatus according to claim 9 , wherein at least one connecting pin of said connector is connected directly to said circuit board.

11. The integrated electric power steering apparatus according to claim 1 , wherein a plurality of groups of parts that constitute an inverter circuit for driving said motor are mounted so as to be consolidated into each phase of a winding of said motor on said circuit board.

12. The integrated electric power steering apparatus according to claim 11 , wherein penetrating apertures are disposed on said circuit board so as to correspond to said groups of parts.