Motor vehicles – Power – Electric
Reexamination Certificate
1998-10-27
2001-02-13
Mai, Lanna (Department: 3619)
Motor vehicles
Power
Electric
Reexamination Certificate
active
06186255
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a hybrid vehicle, and more particularly to a parallel hybrid vehicle.
2. Description of the Related Art
Generally known parallel hybrid vehicles have an internal combustion engine as a primary propulsive power unit and an electric motor, more accurately a generator motor which can also operate as an electric generator, for generating an assistive output power for assisting the output power produced by the engine. The output powers (mechanical powers) generated by the engine and the generator motor are transmitted through a transmission to drive wheels of the hybrid vehicle. If the transmission is a manual transmission, then a clutch mechanism is positioned between the engine and the transmission.
For accelerating the hybrid vehicle, the generator motor is controlled to generate an assistive output power, and both the output power produced by the engine and the assistive output power from the generator motor are transmitted to the drive wheels. Therefore, the power requirements for accelerating the hybrid vehicle can be met, and the output power produced by the engine may be relatively small, thus reducing fuel consumption by the engine and exhaust gases emitted from the engine.
When the hybrid vehicle is decelerated, a kinetic energy is transmitted from the drive wheels through the transmission to the generator motor to cause the generator motor to operate in a regenerative mode, and the electric energy generated by the generator motor is stored in an electric energy storage unit such as a battery used as a power supply for the electric energy.
When the generator motor operates in the regenerative mode upon deceleration of the hybrid vehicle, it is desirable that the kinetic energy of the vehicle be efficiently converted into electric energy for effective energy utilization.
On the conventional hybrid vehicles, the transmission for transmitting the kinetic energy of the vehicle from the drive wheels to the generator motor is manually operated by the driver for a desired gear position (manual transmission) or automatically operated for a desired gear position that matches the power requirements for acceleration or cruising (automatic transmission).
Upon operation of the generator motor in the regenerative mode when the hybrid vehicle is decelerated, the rotational speed of and the load on the generator motor may not be best suited to efficient regenerative operation of the generator motor, failing to convert the kinetic energy of the vehicle efficiently into electric energy.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a hybrid vehicle which incorporates a control system capable of efficiently converting the kinetic energy of the hybrid vehicle upon deceleration thereof into electric energy for retrieval, and increasing the general energy efficiency of the hybrid vehicle in various modes of operation including those modes other than the deceleration of the hybrid vehicle.
To achieve the above object, there is provided in accordance with the present invention a hybrid vehicle comprising an engine for propelling the hybrid vehicle, the engine having an output shaft, a transmission coupled to the output shaft of the engine for transmitting an output power of the engine to drive wheels of the hybrid vehicle, a generator motor coupled to the transmission for transmitting an assistive output power for assisting the output power of the engine through the transmission to the drive wheels, electric energy storage means for storing electric energy regenerated by the generator motor from kinetic energy of the hybrid vehicle transmitted from the drive wheels through the transmission when the hybrid vehicle is decelerated, and transmission control means for establishing a speed reduction ratio for the transmission to achieve a predetermined regeneration efficiency for the generator motor when the hybrid vehicle is decelerated, and controlling the transmission at the established speed reduction ratio.
With the above arrangement, when the hybrid vehicle is decelerated, the transmission control means establishes a speed reduction ratio for the transmission to achieve a predetermined regeneration efficiency for the generator motor, and controls the transmission at the established speed reduction ratio. Therefore, the generator motor can operate as an electric motor to regenerate electric energy at a rotational speed and under a load for an optimum regeneration efficiency.
Consequently, the kinetic energy of the hybrid vehicle as it is decelerated can be converted efficiently into electric energy for retrieval by the generator motor operating as the electric motor.
Preferably, the transmission control means comprises means for bringing the transmission into a neutral position when the engine is idling.
Alternatively, the hybrid vehicle preferably further comprises clutch means for selectively transmitting power between the output shaft of the engine, and the transmission and the generator motor, and clutch control means for disengaging the clutch means when the engine is idling.
When the engine is idling, the load on the engine is thus reduced, and hence the fuel consumption by the engine is lowered.
The clutch control means preferably comprises means for disengaging the clutch means when the hybrid vehicle is decelerated.
Alternatively, the hybrid vehicle preferably further comprises clutch means for selectively transmitting power between the output shaft of the engine, and the transmission and the generator motor, and clutch control means for disengaging the clutch means when the hybrid vehicle is decelerated.
If the clutch means were engaged when the hybrid vehicle is decelerated, part of the kinetic energy of the hybrid vehicle would be consumed by engine braking of the engine. However, when the clutch means is disengaged by the clutch control means upon deceleration of the hybrid vehicle, a greater amount of the kinetic energy of the hybrid vehicle is transmitted to the generator motor. Therefore, the efficiency with which the kinetic energy of the hybrid vehicle upon deceleration of the hybrid vehicle is converted into electric energy (regenerated electric power) by the generator motor is increased.
The transmission control means preferably comprises means for establishing a speed reduction ratio for the transmission to achieve a predetermined energy efficiency for the engine or a predetermined energy efficiency for the generator motor operating as an electric motor to generate the assistive output power, when the hybrid vehicle is running without deceleration, and controlling the transmission at the established speed reduction ratio.
With this arrangement, it is possible to operate the engine and the generator motor at a rotational speed and under a load for an optimum energy efficiency when the hybrid vehicle is running without deceleration, e.g., when the hybrid vehicle is accelerated. Consequently, the hybrid vehicle can run with an optimum energy efficiency while reducing fuel consumption by the engine and electric power consumption by the generator motor.
The hybrid vehicle preferably further comprises rotation transfer transmission means connected between the output shaft of the engine and the generator motor, for transmitting rotation between the output shaft of the engine and the generator motor at a speed reduction ratio for operating the engine and the generator motor in a rotational speed range to achieve predetermined energy efficiencies for the engine and the generator motor, when the transmission is controlled to operate to achieve a predetermined energy efficiency for the engine or a predetermined energy efficiency for the generator motor when the hybrid vehicle is running without deceleration.
Since the output shaft of the engine and the generator motor are connected to each other by the rotation transfer transmission means, when the transmission is controlled to operate to achieve a predetermined energy efficiency for the engine or a predetermi
Fukuchi Hironao
Nakano Kenji
Sawamura Kazutomo
Shimasaki Yuichi
Takahashi Hideyuki
Armstrong, Westerman Hattori, McLeland & Naughton
Honda Giken Kogyo Kabushiki Kaisha
Mai Lanna
McKinley Kevin
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