Toyoda Koki Kabushiki Kaisha

Akio Maekawa

Ryohei Shigeta

Yasushi Yamada

A torque distribution control device for a four-wheel drive vehicle having a torque distribution device for distributing the drive power transmitted from an engine to either of the front wheels or the rear wheels as prime drive wheels, to other wheels as sub-drive wheels determines a pre-torque in a feed forward sense based on the vehicle speed, the throttle opening degree and the gear shift step of a transmission. A compensation torque is determined in a feedback sense based on the vehicle speed and the rotational speed difference between the drive wheels and the sub-drive wheels. A torque transmission clutch is controlled based on a command torque which is obtained by the addition of the pre-torque and the compensation torque, so that the command torque is distributed to the sub-drive wheels.

Torque distribution control device for four-wheel drive vehicle

A torque distribution control device for a four-wheel drive vehicle is disclosed, wherein a torque transmitted from an engine to prime drive wheels is distributed by an electromagnetic clutch to sub-drive wheels on an on-demand basis. A pre-torque is determined based on a vehicle speed and a throttle opening degree in a feed-forward sense. A compensation torque is determined based on the rotational speed difference between the prime drive wheels and the sub-drive wheels and the vehicle speed in a feedback sense. The pre-torque and the compensation torque are added for a command torque, depending on which the electromagnetic clutch is controlled to transmit the torque from the engine to the sub-drive wheels. At this time, since the command torque is limited to an upper limit value therefor or below in dependence on the engine torque, an ECU can be prevented from applying an excess current to an electromagnetic coil of the electromagnetic clutch and hence, from generating heat to raise its temperature when the engine torque is small.

A drive-force distribution controller controls a drive-force transmission apparatus of a vehicle in order to control transmission of drive force to rear wheels or front wheels of the vehicle in accordance with a designated drive-force transmission ratio. The drive-force transmission ratio is changed on the basis of vehicle speed, differential rotational speed (speed difference between the front and rear wheels), and throttle opening. Alternatively, the drive-force transmission ratio is changed on the basis of vehicle speed, throttle opening, and throttle open speed. The change speed of current which is supplied to the drive-force transmission apparatus in order to control the drive-force transmission ratio is adjusted in accordance with a command current filter value which is determined on the basis of vehicle speed and a command current filter map of a vehicle-speed responsive type.

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Okazaki, Japan

Akio Maekawa