Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Control of power distribution between vehicle axis or wheels
Reexamination Certificate
2000-10-10
2003-04-15
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Control of power distribution between vehicle axis or wheels
C180S065230, C180S243000, C701S089000
Reexamination Certificate
active
06549840
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a control apparatus for controlling a four-wheel-drive automotive vehicle, and more particularly to techniques for minimizing the operation of a rear-wheel driving electric motor so as to reduce a temperature rise of this electric motor, by controlling the ratio of distribution of the vehicle drive force to the front and rear drive wheels according to a desired vehicle drive force, particular while the vehicle is being started.
The present invention also relates to a control apparatus for controlling an automotive vehicle wherein one of a front and a rear drive wheels is driven by a first drive power source, while the other of the front and rear drive wheels is driven by a second vehicle drive power source.
2. Discussion of Related Art
There is known a control apparatus for controlling a four-wheel-drive automotive vehicle wherein the front wheels are driven by a first drive power source in the form of an engine while the rear wheels are driven by a second drive power source in the form of an electric motor. This control apparatus is arranged to increase the output torque of the electric motor with respect to the output torque of the engine, according to the operating amount of an accelerator pedal or the opening angle of a throttle valve. An example of such a control apparatus is disclosed in JP-A-63-188528.
In the known control apparatus for the four-wheel-drive vehicle described above, the output of the electric motor is controlled on the basis of the operating amount of the accelerator pedal and the vehicle running speed such that the output of the electric motor is increased with an increase in the operating amount of the accelerator pedal. However, the known control apparatus is not satisfactory and is required to be further improved, regarding the four-wheel driving mode in which the output of the engine for driving the front wheels and the output of the electric motor for driving the rear wheels are controlled depending upon the running condition of the vehicle. Where the operator's desired vehicle drive force is provided by the sum of the front wheel drive force and the rear wheel drive force in the four-wheel driving mode, for instance, the known control apparatus suffers from an inadequate control of the ratio of distribution of the vehicle drive force to the front and rear wheels, due to a change in the static condition and dynamic or running condition of the vehicle and a change in the road surface condition.
The known control apparatus indicated above has another drawback. That is, a permissible range of the output torque of the electric motor is not set depending upon the running condition of the vehicle. Accordingly, the electric motor may suffer from overheating, with a result of limiting the vehicle running condition in which the electric motor is operable, leading to deteriorated drivability of the vehicle. Namely, the output torque to be generated by the electric motor should be limited depending upon its operating temperature, in order to prevent overheating and other damages of the electric motor.
SUMMARY OF THE INVENTION
The prevent invention was made in view of the background prior art discussed above. It is a first object of the present invention to provide a control apparatus for controlling a four-wheel-drive automotive vehicle, which permits the vehicle to be driven with the operator's desired drive force, with an optimum ratio of distribution of the vehicle drive force to the front and rear wheels, irrespective of changes in the static and dynamic condition of the vehicle and the road surface condition.
A second object of the present invention is to provide a control apparatus for controlling an automotive vehicle having two drive power sources for driving respective front and rear drive wheels, which control apparatus permits increased drivability of the vehicle, by reducing a limitation of the vehicle running conditions in which the second drive power source in the form of an electric motor is operated.
The first object may be achieved according to a first aspect of the present invention, which provides a vehicle control apparatus for controlling a four-wheel-drive automotive vehicle of a type which comprises a first drive power source for driving one of a pair of front wheels and a pair of rear wheels, and a second drive power source for driving the other of the pairs of front and rear wheels, characterized in that the vehicle control apparatus is operable to control a front drive force for driving the pair of front wheels and a rear drive force for driving the pair of rear wheels, depending upon a static and a dynamic state of the vehicle such that a sum of the front drive force and the rear drive force is equal to the obtained operator's desired value of a vehicle drive force for driving said automotive vehicle, which operator's desired value is obtained on the basis of an amount of operation of a manually operated vehicle accelerating member and a running speed of the vehicle.
In the vehicle control apparatus constructed according to the first aspect of this invention constructed as described above, the front and rear drive forces for driving the respective pairs of front and rear wheels are controlled on the basis of the static and dynamic states of the vehicle such that a sum of the front and rear drive forces is equal to the operator's desired value of the vehicle drive force which is obtained on the basis of the amount of operation of the manually operated vehicle accelerating member and the running speed of the vehicle. This vehicle control apparatus permits the vehicle to be driven in the four-wheel driving mode such that the ratio of the front and rear drive forces with respect to each other suitably reflects the static and dynamic states of the vehicle, which includes the condition of the road surface on which the vehicle lies.
Preferably, the operator's desired value of the vehicle drive force is calculated on the basis of the operating amount of an accelerator pedal and the vehicle running speed and according to a predetermined relationship between the operator's desired value and the operating amount of the accelerator pedal and the vehicle running speed, and the front and rear drive forces for driving the front and rear wheels are controlled on the basis of the static state of the vehicle such as a load distribution ratio of the front and rear wheels, the dynamic state of the vehicle such as a difference between the rotating speeds of the front and rear wheels and a longitudinal acceleration value of the vehicle, and the road surface condition such as the friction coefficient and gradient of the road surface, such that the sum of the front and rear drive forces is equal to the calculated operator's desired value of the vehicle drive force.
According to one preferred form of the vehicle control apparatus according to the first aspect of the invention, the first drive power source consists of a plurality of drive power sources, preferably, a plurality of drive power sources of different types. In this form of the control apparatus, at least one of the two or more drive power sources of the first drive power source can be operated in an operating condition in which the efficiency is high enough to assure a high degree of fuel economy of the vehicle.
Preferably, the second drive power source consists of at least one motor/generator which selectively function as an electric motor and an electric motor. This second drive power source is desirably used to drive the pair of rear wheels.
According to another preferred form of the vehicle control apparatus according to the first aspect of this invention, a ratio of the front drive force and the rear drive force with respect to each other is determined on the basis of the operator's desired value of the vehicle drive force. For instance, the ratio is changed when the operator's desired value of the vehicle drive force has been reduced below a pre
Kawabata Takuji
Kondo Koichi
Mikami Tsuyoshi
Cuchlinski Jr. William A.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Pipala Edward
Toyota Jidosha & Kabushiki Kaisha
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