Abstract: In a hydraulic controller of driving force distribution device, including: a hydraulic circuit composed of an oil pump for supplying hydraulic fluid to a piston chamber of a clutch (or a driving force distribution device), an opening and closing valve installed in an oil passage between a check valve and the piston chamber, and an accumulator communicating to the piston chamber; control is performed so that the piston chamber reaches a target hydraulic pressure based on the 1st characteristic by closing the opening and closing valve and driving the oil pump at the time of pressurizing the piston chamber; and control is performed so that the piston chamber reaches a target hydraulic pressure based on the 2nd characteristic by prohibiting the driving of the oil pump along with opening the opening and closing valve.

Abstract: In a hydraulic controller of driving force distribution device, including: a hydraulic circuit composed of an oil pump for supplying hydraulic fluid to a piston chamber of a clutch (or a driving force distribution device), an opening and closing valve installed in an oil passage between a check valve and the piston chamber, and an accumulator communicating to the piston chamber; control is performed so that the piston chamber reaches a target hydraulic pressure based on the 1st characteristic by closing the opening and closing valve and driving the oil pump at the time of pressurizing the piston chamber; and control is performed so that the piston chamber reaches a target hydraulic pressure based on the 2nd characteristic by prohibiting the driving of the oil pump along with opening the opening and closing valve.

Abstract: A driving force control apparatus for a four-wheel drive vehicle is provided for stably launching the vehicle irrespective of whichever condition of a road surface and whether or not a road is gradient.

Abstract: A fault detecting apparatus for a four-wheel drive vehicle is provided for avoiding without fail any erroneous detection due to a response delay associated with an operation for switching a speed increasing system and due to sudden fluctuations in wheel speed, to highly accurately detect a fault in the speed increasing system. The speed increasing system is configured to transmit a driving force of a prime mover directly to main driving wheels and to sub-driving wheels through associated clutches, and to increase rotational speed of the sub-driving wheels above rotational speed of the main driving wheels when a speed increase instruction signal is outputted. The fault detecting apparatus comprises an S-AWD•ECU for detecting a fault in the speed increasing system, and for disabling the fault detection until a predetermined time has elapsed after a speed increase instruction signal was outputted or after the output of the speed increase instruction signal was stopped.

Abstract: A driving force control apparatus for a four-wheel drive vehicle is provided for stably launching the vehicle irrespective of whichever condition of a road surface and whether or not a road is gradient.

Abstract: A fault detecting apparatus for a four-wheel drive vehicle is provided for avoiding without fail any erroneous detection due to a response delay associated with an operation for switching a speed increasing system and due to sudden fluctuations in wheel speed, to highly accurately detect a fault in the speed increasing system. The speed increasing system is configured to transmit a driving force of a prime mover directly to main driving wheels and to sub-driving wheels through associated clutches, and to increase rotational speed of the sub-driving wheels above rotational speed of the main driving wheels when a speed increase instruction signal is outputted. The fault detecting apparatus comprises an S-AWD•ECU for detecting a fault in the speed increasing system, and for disabling the fault detection until a predetermined time has elapsed after a speed increase instruction signal was outputted or after the output of the speed increase instruction signal was stopped.

Abstract: There is provided a control system for a front-and-rear wheel drive vehicle which connects and disconnects one pair of respective pairs of front wheels and rear wheels to and from an electric motor for driving the one pair of wheels by a clutch of a type actuated by pressure. The control system is capable of engaging the clutch promptly and reliably, thereby enabling excellent startability of the vehicle and a sufficient total driving force for the vehicle. In the control system, the front wheels are driven by an engine, the rear wheels are driven by the electric motor via the clutch, and the clutch is actuated by accumulator pressure, whereby the rear wheels and the electric motor are connected to and disconnected from each other. The control system increases the accumulator pressure by driving an electric oil pump when the accumulator pressure is equal to or lower than an operating pressure.

Abstract: There is provided a control system for a front-and-rear wheel drive vehicle which connects and disconnects one pair of respective pairs of front wheels and rear wheels to and from an electric motor for driving the one pair of wheels by a clutch of a type actuated by pressure. The control system is capable of engaging the clutch promptly and reliably during the start of the vehicle and during the travel thereof, thereby making it possible to ensure an excellent startability of the vehicle and a sufficient total driving force for the vehicle. In the control system for the vehicle, the front wheels are driven by an engine, the rear wheels are driven by the electric motor via the clutch of a type actuated by pressure, and the clutch is actuated by accumulator pressure accumulated in an accumulator, whereby the rear wheels and the electric motor are connected to and disconnected from each other.