Electric drive device and electric power steering device

1. An electric drive device comprising:

a motor housing accommodating therein an electric motor that drives a mechanical control element;

a heat radiation base body fixed to an end surface, which is an opposite side to an output shaft portion of a rotation shaft of the electric motor, of the motor housing and extending in a direction of the rotation shaft which is the opposite side to the output shaft portion;

one electronic control unit of a redundant system, the one electronic control unit arranged along a direction in which the heat radiation base body extends and having a board that is fixed to the heat radiation base body with thermal conduction to the heat radiation base body allowed;

another electronic control unit of the redundant system, the another electronic control unit arranged along a direction in which the heat radiation base body extends and having a board that is fixed to the heat radiation base body with thermal conduction to the heat radiation base body allowed; and

a rotation position detection circuit board which is disposed between the heat radiation base body and the end surface of the motor housing and provided with a detection element that detects magnetic pole position information of a rotor of the electric motor, and to which neutral terminals of the electric motor for each phase are connected, wherein:

an output terminal from the one electronic control unit and an output terminal from the another electronic control unit protrude from a gap between the rotation position detection circuit board and the heat radiation base body to a radially outer side, and

input terminals of the electric motor for each phase are directly connected to the output terminals.

2. The electric drive device as claimed in claim 1 , wherein:

a wiring pattern that electrically connects the neutral terminals for each phase is formed on the rotation position detection circuit board.

3. The electric drive device as claimed in claim 2 , wherein:

the heat radiation base body is fixed to the end surface of the motor housing at a position close to an area where the rotation shaft is disposed, and

the one electronic control unit and the another electronic control unit are arranged at opposite sides of the heat radiation base body.

4. The electric drive device as claimed in claim 3 , wherein:

the heat radiation base body has fixing surfaces of the boards of the one electronic control unit and the another electronic control unit, accommodation recessed portions formed on the respective fixing surfaces, and fixing flat surface portions enclosing the respective accommodation recessed portions,

power conversion circuit boards that form the one and the another electronic control units are fixed to the accommodation recessed portions, and

control circuit boards that form the one and the another electronic control units are fixed to the fixing flat surface portions so as to cover the respective power conversion circuit boards.

5. The electric drive device as claimed in claim 4 , wherein:

the rotation position detection circuit board is fixed to the end surface of the motor housing,

supporting stems that support the heat radiation base body are formed integrally with the end surface of the motor housing and arranged at opposite sides of the rotation position detection circuit board, and

the heat radiation base body is fixed to the supporting stems.

6. The electric drive device as claimed in claim 4 , wherein:

a power conversion circuit and a power supply circuit except an electrolytic capacitor are mounted on the power conversion circuit boards forming the one and the another electronic control units, and

a microcomputer that controls the power conversion circuit, a peripheral device and the electrolytic capacitor of the power supply circuit are mounted on the control circuit boards forming the one and the another electronic control units.

7. An electric power steering device comprising:

an electric motor providing a steering assistive force to a steering shaft on the basis of an output from a torque sensor that detects a turning direction and a turning torque of the steering shaft;

a motor housing accommodating therein the electric motor;

a heat radiation base body fixed to an end surface, which is an opposite side to an output shaft portion of a rotation shaft of the electric motor, of the motor housing and extending in a direction of the rotation shaft which is the opposite side to the output shaft portion;

one electronic control unit of a redundant system, the one electronic control unit arranged along a direction in which the heat radiation base body extends and having a board that is fixed to the heat radiation base body with thermal conduction to the heat radiation base body allowed;

another electronic control unit of the redundant system, the another electronic control unit arranged along a direction in which the heat radiation base body extends and having a board that is fixed to the heat radiation base body with thermal conduction to the heat radiation base body allowed; and

a rotation position detection circuit board which is disposed between the heat radiation base body and the end surface of the motor housing and provided with a detection element that detects magnetic pole position information of a rotor of the electric motor, and to which neutral terminals of the electric motor for each phase are connected, wherein:

an output terminal from the one electronic control unit and an output terminal from the another electronic control unit protrude from a gap between the rotation position detection circuit board and the heat radiation base body to a radially outer side, and

input terminals of the electric motor for each phase are directly connected to the output terminals.

8. The electric power steering device as claimed in claim 7 , wherein:

a wiring pattern that electrically connects the neutral terminals for each phase is formed on the rotation position detection circuit board.

9. The electric power steering device as claimed in claim 8 , wherein:

the heat radiation base body is fixed to the end surface of the motor housing at a position close to an area where the rotation shaft is disposed, and

the one electronic control unit and the another electronic control unit are arranged at opposite sides of the heat radiation base body.

10. The electric power steering device as claimed in claim 9 , wherein:

the heat radiation base body has fixing surfaces of the boards of the one electronic control unit and the another electronic control unit, accommodation recessed portions formed on the respective fixing surfaces, and fixing flat surface portions enclosing the respective accommodation recessed portions,

power conversion circuit boards that form the one and the another electronic control units are fixed to the accommodation recessed portions, and

control circuit boards that form the one and the another electronic control units are fixed to the fixing flat surface portions so as to cover the respective power conversion circuit boards.

11. The electric power steering device as claimed in claim 10 , wherein:

the rotation position detection circuit board is fixed to the end surface of the motor housing,

supporting stems that support the heat radiation base body are formed integrally with the end surface of the motor housing and arranged at opposite sides of the rotation position detection circuit board, and

the heat radiation base body is fixed to the supporting stems.

12. The electric power steering device as claimed in claim 10 , wherein:

a power conversion circuit and a power supply circuit except an electrolytic capacitor are mounted on the power conversion circuit boards forming the one and the another electronic control units, and

a microcomputer that controls the power conversion circuit, a peripheral device and the electrolytic capacitor of the power supply circuit are mounted on the control circuit boards forming the one and the another electronic control units.