Motor vehicles – Power – Electric
Reexamination Certificate
2000-08-07
2002-11-26
Culbreth, Eric (Department: 3611)
Motor vehicles
Power
Electric
C180S065510, C701S022000
Reexamination Certificate
active
06484832
ABSTRACT:
This application is based on Japanese Patent Application No. 11-241874 filed Aug. 27, 2000, the content of which is incorporated hereinto by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for controlling an automotive vehicle equipped with a primary drive power source and a secondary or auxiliary drive power source, and more particularly to a drive control apparatus for an all-wheel-drive vehicle wherein one of a front-wheel drive system and a rear-wheel drive system is driven by the primary drive power source while the other drive system is driven by the auxiliary drive power source.
2. Discussion of the Related Art
An automotive vehicle equipped with a primary and a secondary or auxiliary drive power source is known. One example of this type of automotive vehicle is an all-wheel-drive vehicle wherein one of a front-wheel and a rear-wheel drive system is driven by the primary drive power source in the form of an engine (internal combustion engine) while the other drive system is driven by the auxiliary drive power source in the form of an electric or hydraulic motor. For improving the drivability of this type of all-wheel-drive automotive vehicle while maximizing the fuel economy or maintaining desired running characteristics of the vehicle, there is provided a motor drive mode which is selected to apply an output torque of the electric motor to the above-indicated other drive system as an assisting drive torque when it is desired to accelerate the vehicle.
The all-wheel-drive automotive vehicle indicated above can be accelerated even on a frozen, snow-covered or other roadway surface having a low friction coefficient, by driving the auxiliary drive wheels by the auxiliary drive power source (electric motor), when it is desired to accelerate the vehicle in an intermediate degree, during running of the vehicle at a relatively low speed. In this respect, there is known a control apparatus adapted to control the auxiliary drive power source so as to prevent a speed difference of the auxiliary drive wheels, when the vehicle is running straight without deceleration thereof on a roadway surface having a low friction coefficient. An example of this control apparatus is disclosed in JP-A-7-125556.
The known control apparatus for the automotive vehicle having a plurality of drive power sources as described above is not satisfactory in its capability of controlling the auxiliary drive power source, and tends to suffer from drawbacks in terms of the fuel economy and the driving characteristics of the vehicle.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an apparatus for controlling an automotive vehicle equipped with a plurality of drive power source, which apparatus assures satisfactory fuel economy and driving characteristics of the vehicle.
The above object may be achieved according to a first aspect of this invention, which provides an apparatus for controlling an automotive vehicle having a primary drive power source and an auxiliary drive power source, comprising; (a) required output determining means for determining a required output of the vehicle which is desired by an operator of the vehicle; and (b) first control means for controlling the auxiliary drive power source such that an assisting drive torque which is generated by the auxiliary drive power source and applied to the vehicle in addition to a primary drive torque generated by the primary drive power source increases with an increase of the required output of the vehicle and such that the auxiliary drive power source is operated for a length of time which decreases with the increase of the required output.
In the apparatus constructed according to the first aspect of the invention described above, the first control means controls the auxiliary drive power source such that the assisting drive torque generated by the auxiliary drive power source increases with an increase of the operator's desired output of the vehicle and such that the length of time during which the auxiliary drive power source is operated decreases with the increase of the operator's desired vehicle output. Thus, the auxiliary drive power source is suitably controlled. For example, the required vehicle output desired by the vehicle operator is represented by the operating angle or amount of an accelerator pedal. The first control means permits an increase of the total drive force of the vehicle corresponding to to the operating amount of the accelerator pedal, with the assisting drive torque generated by the auxiliary drive power source, so that a further increase in the operating amount of the accelerator pedal is prevented, and the required amount of fuel consumption by the vehicle is reduced.
The control apparatus is preferably applicable to an automotive vehicle wherein the primary drive power source, which may be an internal combustion engine, is used to drive one of a front-wheel drive system and a rear-wheel drive system, while the auxiliary drive power source, which may be an electric motor, is used to drive the other of the front- and rear-wheel drive systems. In this case, both of the front- and rear-wheel drive systems are driven while the auxiliary drive power source is operated, so that the vehicle can be suitably driven or accelerated with a suitable total drive force, even on a frozen or snow-covered surface or any other roadway surface having a comparatively low friction coefficient.
The control apparatus constructed according to a first preferred form of the above-indicated first aspect of the present invention further comprises assisting drive torque compensating means for compensating the assisting drive torque as determined by the first control means, so as to determine a ratio of the assisting drive torque as compensated by the assisting drive torque compensating means to the primary drive torque, so that fuel economy of the internal combustion engine is maximized.
The control apparatus constructed according to a second preferred form of the first aspect of this invention further comprises: roadway surface friction coefficient determining means for determining whether a friction coefficient of a roadway surface on which the vehicle lies is lower than a predetermined threshold; and second control means operable when the roadway surface friction coefficient determining means has determined that the friction coefficient of the roadway surface is lower than the predetermined threshold, the second control means reducing an output of the primary drive power source and operating the auxiliary drive power source, and wherein the first control means operates the auxiliary drive power source such that the assisting drive torque increases with the increase of the required output of the vehicle and such that the length of time of the auxiliary drive power source decreases with the increase of the required output, when the roadway surface friction coefficient determining means has determined that the friction coefficient is not lower than the predetermined threshold.
In the control apparatus constructed according to the second preferred form of the invention, the first control means is operated when the friction coefficient of the roadway surface is comparatively high, to operate the auxiliary drive power source such that the assisting drive torque generated by the auxiliary drive power source increases as the vehicle operator's desired vehicle output is increased, and such that the length of operation of the auxiliary drive power source decreases as the desired vehicle output is increased. Accordingly, the drivability of the vehicle is further improved, making it possible to prevent a further increase of the operating amount of the accelerator pedal and reduce the required amount of fuel consumption by the vehicle.
The control apparatus constructed according to a third preferred form of the first aspect of the invention further comprises third control means operable when the roadway surface friction coefficient determining
Ichioka Eiji
Morisawa Kunio
Culbreth Eric
Lum L.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Toyota Jidosha & Kabushiki Kaisha
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