Abstract: The engagement force of an electromagnetic clutch can be precisely controlled at a target engagement force by a simple structure even when an air gap of the electromagnetic clutch varies. An electromagnetic clutch control system includes magnetic flux density sensors, a target engagement force calculating device, a target magnetic flux density calculating device, and a feedback control device. The target magnetic flux density calculating device calculates a target magnetic flux density &phgr;t based on a target engagement force Tt of electromagnetic clutches calculated by the target engagement force calculating device. The current supplied to the electromagnetic clutches is feedback controlled by the feedback control device so that an actual magnetic flux density &phgr; detected by the magnetic flux density sensors agrees with the target magnetic flux density &phgr;t.

Abstract: A driving force distribution system selectively operates right and left electromagnetic clutches and, thereby assisting a vehicle in turning by transmitting torque from the inner turning wheel to the outer turning wheel. The right electromagnetic clutch includes an armature on the right side of a core housing a coil. The left electromagnetic clutch includes an armature on the left side of the core housing a coil. When the right electromagnetic clutch is engaged in order to assist the turning by transmitting torque from the right driven wheel to the left driven wheel when the vehicle is turning right, since the right electromagnetic clutch includes the armature on the right side of the core, the armature is urged leftward toward the core due to a centrifugal force caused by turning right to reduce an air gap, thereby enhancing the responsiveness of engagement of the right electromagnetic clutch as well as reducing the power consumption.

Abstract: An electromagnetic clutch structure in a driving force distribution system selectively operates right and left electromagnetic clutches so as to transmit torque from the inner turning wheel to the outer turning wheel, thereby assisting turning, or so as to transmit torque from the outer turning wheel to the inner turning wheel, thereby stabilizing vehicle behavior. The right and left electromagnetic clutches each include a coil, a core housing the coils, armatures arranged so as to adjoin the core in the lateral direction, and frictional engagement members arranged on the inside, in the radial direction, of the core. The frictional engagement members are engaged by pressure of a pressure part of the armatures, the pressure part extending further inward in the radial direction than the core.

Abstract: In a vehicle in which a torque generated in an engine is transmitted to driven wheels through a torque converter and an automatic transmission, when a speed ratio e in the torque converter is equal to or larger than a predetermined value (e.g., 0.85), and the accuracy of estimating a capacity &tgr; of the torque converter is low, an estimated engine torque Ti is multiplied by a torque ratio k of the torque converter to estimate a drive torque Td. When the speed ratio e in the torque converter is smaller than the predetermined value, and a response lag is produced in the transmission of the engine torque, a drive torque Td is estimated from an engine rotational sped Ne and the speed ratio e in the torque converter. During shifting of the automatic transmission, a drive torque Td is estimated from a wheel speed V. Thus, a correct drive torque can be estimated.

Abstract: A co-operative control system for a vehicle including a force distribution device for distributing the driving force or braking force between the right and left wheels or between the front and rear wheels, includes a first control means for controlling the operation of the force distribution device, an electric power steering device, having a motor for applying a steering assist torque to a vehicle steering system, and a second control means for calculating a motor control signal for driving the motor. The motor control signal is based on at least the steering torque detected by a steering torque detecting means.

Abstract: A driving force distribution device which controls the engagement forces of electromagnetic clutches and which govern the torque distribution between the driving wheels of a vehicle by calculating a target magnetic flux density and converting the same into a target excitation current. Since the relationship between the target magnetic flux density and the target excitation current changes according to a decrease in the air gaps accompanying wear of the frictional engagement members of the electromagnetic clutches, a relationship between the magnetic flux density and the excitation current is determined by applying current to the electromagnetic clutches when torque distribution control is not being carried out such as when the system is started, and the target excitation current is calculated from the target magnetic flux density based on the determined relationship.

Abstract: A co-operative control system for a vehicle having a force distribution device for distributing at least one of a driving force and a braking force between spaced apart wheels, the co-operative system having: a first control mechanism for controlling the operation of the force distribution device, an electric power steering device having a motor for applying a steering assist torque to a steering system of the vehicle, and a second control mechanism for calculating a motor control signal for driving the motor based on at least a steering torque detected by a steering torque sensor, and for inhibiting drive of the motor based on at least an actual motor detected by a current sensor and the steering torque.

Abstract: A power steering apparatus on a motor vehicle such as a riding-type four-wheel motor vehicle includes a steering shaft with at least a steering handle mounted on an upper portion thereof, a lever arm arrangement angularly movable about the axis of the steering shaft, and an actuator arrangement for relatively acting on the steering shaft depending on a change in the arm ratio of the lever arm arrangement to assist in turning the steering shaft.