Electricity: motive power systems – Braking – Dynamic braking
Reexamination Certificate
2000-08-02
2001-12-11
Dang, Khanh (Department: 2837)
Electricity: motive power systems
Braking
Dynamic braking
C318S139000, C180S065230
Reexamination Certificate
active
06329775
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a control apparatus of a hybrid vehicle which is driven by an engine and an electric motor, in particular, to one for controlling the amount of assisted (or auxiliary) output by the motor which assists the engine output when the vehicle is driven at high speed.
2. Description of the Related Art
Conventionally, a hybrid vehicle having not only the engine but also an electric motor as the drive source is known.
As a hybrid vehicle, a parallel hybrid vehicle is known, which uses an electric motor as an auxiliary drive source for assisting the engine output. In the parallel hybrid vehicle, the engine output is assisted using the electric motor during the accelerating operation (i.e., acceleration mode), while during the decelerating operation (i.e., deceleration mode), the battery and the like are charged via a regenerating operation, that is, “deceleration regeneration” is performed. According to various control operations including the above, the remaining capacity (corresponding to the electric energy) of the battery is maintained while the driver's demands can also be satisfied. An example thereof is disclosed in Japanese Unexamined Patent Application, First Publication, No. Hei 7-123509.
According to the control apparatus of such conventional hybrid vehicles, for example, in the acceleration mode, an assist driving force using a motor is also output in addition to the driving force obtained by the engine output. This output assist by the motor for assisting the engine output is continuously performed even in the high-speed driving mode in which the fuel supply to the engine is cut off according to a specific limit defined by the fuel supply. In this case, the engine side controls the vehicle so as to decrease its speed, but the motor side still controls the vehicle so as to assist the driving force obtained by the engine output. Therefore, these controls are inconsistent with each other.
Due to such an unnecessary assist by the motor, the battery capacity may be decreased, thereby causing excessive discharge of the battery.
SUMMARY OF THE INVENTION
In consideration of the above circumstances, an objective of the present invention is to provide a control apparatus applied to a hybrid vehicle, by which the output assist by the motor with respect to the engine output can be limited or stopped in the high speed driving mode.
Therefore, the present invention provides a control apparatus of a hybrid vehicle, wherein:
the hybrid vehicle comprises:
an engine for outputting force for driving the vehicle;
an electric motor for assisting the output from the engine according to the driving state of the vehicle; and
a battery device for storing energy generated using the motor as a generator driven by the engine, and energy regenerated via a regenerating operation performed by the motor when the vehicle is decelerated, and
the control apparatus comprises:
a speed limiting section for stopping the operation of the motor from assisting the engine output when the engine output is assisted by the motor and the speed of the vehicle exceeds a predetermined first threshold value; and
a regenerating operation starting section for starting the regenerating operation of the motor when the speed of the vehicle exceeds a predetermined second threshold value which is larger than the first threshold value.
According to the above control apparatus, when the fuel is supplied to the engine and simultaneously the engine output is assisted by the motor, (i) the output assist can be stopped when the vehicle speed exceeds the first threshold value (e.g., 160 km/h), and (ii) when the vehicle speed further exceeds the second threshold value (e.g., 170 km/h), the regenerating operation using the motor can be started so as to store the engine output as regenerated energy, thereby decreasing the driving force obtained by the engine output. Therefore, the vehicle speed can be limited without stopping the fuel supply to the engine; thus, the purifier for purifying the exhaust gas of the vehicle is not much affected in comparison with the case of stopping the fuel supply.
In addition, the output assist using the motor is stopped before the fuel supply to the engine is stopped; thus, it is possible to prevent inconsistencies between the control at the engine side and the control at the motor side.
The present invention also provides a control apparatus of a hybrid vehicle, wherein:
the hybrid vehicle comprises:
an engine for outputting force for driving the vehicle;
an electric motor for assisting the output from the engine according to the driving state of the vehicle; and
a battery device for storing energy generated using the motor as a generator driven by the engine, and energy regenerated via a regenerating operation performed by the motor when the vehicle is decelerated, and
the control apparatus comprises:
an assisted amount decreasing section for:
gradually decreasing an amount of the output from the motor for assisting the engine when the engine output is assisted by the motor and the speed of the vehicle exceeds a predetermined first threshold value; and
setting the amount of the assisted output to zero when the speed of the vehicle exceeds a predetermined second threshold value which is larger than the first threshold value; and
a generation starting section for generating energy by using the motor as a generator when the speed of the vehicle exceeds the second threshold value.
According to this control apparatus, when the fuel is supplied to the engine and simultaneously the engine output is assisted by the motor, (i) the output assist can be gradually decreased and stopped when the vehicle speed exceeds the first threshold value (e.g., 160 km/h), and (ii) when the vehicle speed further exceeds the second threshold value (e.g., 170 km/h), the motor can be used as a generator so as to generate energy by using the engine output, thereby limiting the vehicle speed. Therefore, the driving force can be smoothly decreased by gradually decreasing the amount of assisted output using the motor, and it is possible to prevent a sudden change of the driving state of the hybrid vehicle. In addition, the driving force obtained by the engine output can be smoothly decreased by converting the engine output to the generated energy, thereby improving the driving comfortableness.
The above structure may further comprise a fuel cut-off section for stopping the supply of fuel to the engine when the speed of the vehicle exceeds a predetermined third threshold value which is larger than the second threshold value.
In this case, when the vehicle speed exceeds the third threshold value (e.g., 180 km/h), the fuel cut-off can be executed so as to limit the vehicle speed. Here, the output assist using the motor has been completed when the fuel cut-off is executed; therefore, it is possible to prevent inconsistencies between the control at the engine side and the control at the motor side.
REFERENCES:
patent: 6140780 (2000-10-01), Oshima et al.
patent: 7-123509 (1995-05-01), None
Izumiura Atsushi
Matsubara Atsushi
Oki Hideyuki
Sawamura Kazutomo
Takahashi Hideyuki
Armstrong Westerman Hattori McLeland & Naughton LLP
Dang Khanh
Honda Giken Kogyo Kabushiki Kaisha
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