Abstract: A CPU computes a throttle opening degree increasing speed V?h and a steering wheel angular velocity V? based on a throttle opening degree ?h and a steering wheel angle ?. Based on the throttle increasing speed V?h and the steering wheel angular velocity V?, the CPU selects one of a first drive mode and a second drive mode. The CPU controls the power transmission ratio of a power transmitting device according to the selected drive mode. Therefore, the power transmission ratio of the power transmitting device is properly controlled in accordance with the degree of intention for acceleration of the driver, which is computed based on the throttle increasing speed V?h, and the turning speed of the steering wheel, which is computed based on the steering wheel angular velocity V?. Therefore, the drive mode is properly switched in accordance with the driving state of a four-wheel drive vehicle.

Abstract: A CPU computes a throttle opening degree increasing speed V?h and a steering wheel angular velocity V? based on a throttle opening degree ?h and a steering wheel angle ?. Based on the throttle increasing speed V?h and the steering wheel angular velocity V?, the CPU selects one of a first drive mode and a second drive mode. The CPU controls the power transmission ratio of a power transmitting device according to the selected drive mode. Therefore, the power transmission ratio of the power transmitting device is properly controlled in accordance with the degree of intention for acceleration of the driver, which is computed based on the throttle increasing speed V?h, and the turning speed of the steering wheel, which is computed based on the steering wheel angular velocity V?. Therefore, the drive mode is properly switched in accordance with the driving state of a four-wheel drive vehicle.

Abstract: A four-wheel drive vehicle has front wheels and rear wheels driven by an engine, and a coupling for changing the distribution ratio of torque to the front wheels and the rear wheels. An ECU determines whether engine braking is being applied based on the vehicle speed V and the throttle opening degree Od. When determining that engine braking is being applied, the ECU temporarily performs the engine braking related control. The ECU controls the engaging force of the coupling such that the distribution ratio of torque to the front wheels and the rear wheels is changed to a more equalized state in the engine braking related control than that before the engine braking related control is started. Accordingly, the fixing force of the front wheels and the rear wheels is temporarily increased without delay when engine braking is applied.

Abstract: A vehicle has a transmission apparatus that changes the distribution of power transmitted from a power source to a plurality of wheels. The method for distributing power of the vehicle includes detecting the temperature of a part located on a power transmission path between the power source and a wheel to which power is transmitted from the power source through the transmission apparatus, the heat of the part being increased as the power distribution ratio is increased; determining that the current state is a specific state in which the detected temperature reaches a previously set first reference temperature; and controlling the transmission apparatus to lower the power distribution ratio to the wheel from the transmission apparatus when the current state is determined to the specified state.

Abstract: A four-wheel drive vehicle includes a coupling, which varies the distribution ratio of torque to the front wheels and the rear wheels. The distribution ratio of torque to the front wheels and the rear wheels is determined by the engaging force of the coupling. An ECU sets first to third determination threshold values for the opening degree of a throttle valve of an engine in accordance with the detected vehicle speed. The ECU determines whether the vehicle is in a steady driving state by comparing the detected throttle opening degree with the set first to third determination threshold values and controls the engaging force of the coupling in accordance with the determination result. Thus, the steady driving state of the vehicle is correctly determined.

Abstract: A four-wheel drive vehicle has front wheels and rear wheels driven by an engine, and a coupling for changing the distribution ratio of torque to the front wheels and the rear wheels. An ECU determines whether engine braking is being applied based on the vehicle speed V and the throttle opening degree Od. When determining that engine braking is being applied, the ECU temporarily performs the engine braking related control. The ECU controls the engaging force of the coupling such that the distribution ratio of torque to the front wheels and the rear wheels is changed to a more equalized state in the engine braking related control than that before the engine braking related control is started. Accordingly, the fixing force of the front wheels and the rear wheels is temporarily increased without delay when engine braking is applied.

Abstract: A vehicle has a transmission apparatus that changes the distribution of power transmitted from a power source to a plurality of wheels. The method for distributing power of the vehicle includes detecting the temperature of a part located on a power transmission path between the power source and a wheel to which power is transmitted from the power source through the transmission apparatus, the heat of the part being increased as the power distribution ratio is increased; determining that the current state is a specific state in which the detected temperature reaches a previously set first reference temperature; and controlling the transmission apparatus to lower the power distribution ratio to the wheel from the transmission apparatus when the current state is determined to the specified state.

Abstract: A four-wheel drive vehicle includes a coupling, which varies the distribution ratio of torque to the front wheels and the rear wheels. The distribution ratio of torque to the front wheels and the rear wheels is determined by the engaging force of the coupling. An ECU sets first to third determination threshold values for the opening degree of a throttle valve of an engine in accordance with the detected vehicle speed. The ECU determines whether the vehicle is in a steady driving state by comparing the detected throttle opening degree with the set first to third determination threshold values and controls the engaging force of the coupling in accordance with the determination result. Thus, the steady driving state of the vehicle is correctly determined.