Development of Direct Electromagnetic Clutch System

Honda has developed the SH-AWD(Super Handling-All Wheel Drive) system (Ref. 1), the world's first 4WD system capable of continuously and variably distributing torque to all four wheels of the vehicle. The use of this system enables torque to be employed in the control of the yawing moment and the application of control to equalize the load ratio between all the wheels of the vehicle. This results in higher turning stability and increased turning limit performance.

These forms of control require a highly responsive actuator capable of controlling torque with a high degree of accuracy. A direct electromagnetic clutch in which solenoid attraction acts directly on the clutch was newly developed to satisfy the function described above.

Detection of the solenoid air gap is required to enable high-accuracy control of solenoid attraction. A search-coil-type -sensor based on a new concept was developed and employed to enable detection of the solenoid gap.