Interrelated power delivery controls – including engine control – Plural engines – Electric engine
Reexamination Certificate
1999-11-15
2001-03-20
Marmor, Charles A (Department: 3681)
Interrelated power delivery controls, including engine control
Plural engines
Electric engine
C477S020000, C477S091000, C477S107000
Reexamination Certificate
active
06203468
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a control device for a hybrid vehicle which jointly uses an engine and two electric motors. More particularly, the invention pertains to a control device for a hybrid vehicle having the ability to switch it between series drive mode and parallel drive mode depending on running conditions.
2. Description of the Related Art
Among vehicles including motor vehicles, hybrid vehicles which jointly use an engine and electric motors have been developed in recent years due to their low-pollution and resource-saving features. These hybrid vehicles employ many techniques for achieving an improvement in kinetic energy recovery efficiency and for maintaining running performance by installing two motors, one for power generation and the other as a power source.
One known example of a hybrid vehicle of this kind is made such that it is switched between series drive operations, in which the hybrid vehicle runs while driving a motor for electric power generation with mechanical output of an engine and then driving a motor for running with both generated electric power and electric power output discharged from a battery, and parallel drive operation, in which the hybrid vehicle runs mainly with the mechanical output of the engine and the difference between required output and the mechanical output of the engine is made up for by means of the motors, depending on running conditions.
As an example, Japanese Patent Laid-Open No. 98322/1996 discloses a series-parallel hybrid electric vehicle comprising an engine, a generator driven by mechanical output of the engine, a battery charged with electricity generated by the generator, a motor driven by electric power discharged from the battery, and coupling/decoupling means like a clutch for establishing and breaking a mechanical link between the generator and the motor.
In the aforementioned series-parallel hybrid electric vehicle, series drive operation is selected when the clutch is engaged, while parallel drive operation is selected when the clutch is disengaged, and the rotating speed of the generator is matched with that of the motor before the clutch is engaged to avoid shocks caused by its engagement.
It is, however, likely that fluctuation in toque occurs due to a difference in output torque between the engine and motor sides at the time of switching from series drive operations to parallel drive operation if the clutch is engaged simply upon matching the rotating speed of the generator with that of the motor. Fluctuation in toque may also occur at the time of switching from the parallel drive operation to the series drive operation if the clutch is simply disengaged.
SUMMARY OF THE INVENTION
This invention has been made in view of these circumstances.
Accordingly, it is an object of the invention to provide a control device for a hybrid vehicle which makes it possible to prevent fluctuations in rotating speed or in toque at the time of switching between series drive and parallel drive operations and achieve smooth running without deteriorating a feeling of comfortable driving.
In a first embodiment, the invention relates to a control system for a hybrid vehicle having an internal combustion engine mounted on the vehicle for outputting a driving force via an output shaft, a lockup clutch mechanically and coaxially connected to the engine for connecting and disconnecting the driving force to a driving wheel, a transmission rotatably connected to the lockup clutch for changing a rotating speed thereof, a battery mounted on the hybrid vehicle for storing and providing an electric energy therefrom to various electric equipment, an accelerator pedal sensor provided in vicinity of an accelerator pedal for detecting a depressed amount thereof and for producing an accelerator signal, a brake switch provided near a brake pedal for detecting whether or not a driver steps thereon and for generating a brake signal when the driver steps thereof, and an inhibitor switch attached on a gear select mechanism for detecting whether a select lever is set in a drive range (D) and a rear range (R) or not and for outputting an ON signal when the lever is set in at least either one of the ranges, comprising:
a first motor (A) interposed between the output shaft and the lockup clutch and electrically connected to the battery for generating an auxiliary electric energy and for returning thereof to the battery when the lockup clutch is released while the vehicle is running in a series running mode;
a second motor (B) interposed between the first motor (A) and the transmission and electrically connected to the battery for assisting the engine when the lockup clutch is connected while the vehicle is running in a parallel running mode;
a planetary gear interposed between the lockup clutch and the second motor (B) for alternatively and effectively using the motors (A) and (B) so as to be changeable to a motor or a generator as required; and
electronic hybrid engine control means responsive to the accelerator signal, the brake signal, the ON signal for connecting the lockup clutch after setting the driving force to substantially zero in addition to making an r.p.m. of the first motor (A) to coincide with the r.p.m. of the second motor (B) when a driving condition is transiting from the series running mode to the parallel running mode and for disconnecting the lockup clutch after making the r.p.m. of the first motor (A) to coincide with the r.p.m. of the second motor by gradually increasing the r.p.m. of the second motor (B) at the time of when the driving force becomes substantially zero by incrementally adding a driving torque of the second motor (B) as much as a decreased torque of the engine when the driving condition is transiting from the parallel running mode to the series running mode in addition to gradually decreasing the driving force so as to correctly avoid uncomfortable changes of the r.p.m. and torque without deteriorating a good drive feeling and to effectively realize a smooth running of the vehicle.
In a second embodiment, the invention relates to a control method for a hybrid vehicle having, an internal combustion engine mounted on the vehicle for outputting a driving force via an output shaft, a lockup clutch mechanically and coaxially connected to the engine for connecting and disconnecting the driving force to a driving wheel, a transmission rotatably connected to the lockup clutch for changing a rotating speed thereof, a battery mounted on the hybrid vehicle for storing and providing an electric energy therefrom to various electric equipment, an accelerator pedal sensor provided in vicinity of an accelerator pedal for detecting a depressed amount thereof, a brake switch provided near a brake pedal for detecting whether or not a driver steps thereon, and an inhibitor switch attached on a gear select mechanism for detecting whether a select lever is set in a drive range (D) and a rear range (R) or not, comprising the steps of:
generating a first auxiliary electric energy by interposing a first motor (A) between the output shaft and the lockup clutch and by electrically connecting to the battery when the lockup clutch is released while the vehicle is running in a series running mode;
assisting the engine by a second motor (B) interposed between the first motor (A) and the transmission and electrically connected to the battery when the lockup clutch is connected while the vehicle is running in a parallel running mode;
interposing a planetary gear between the lockup clutch and the second motor (B) in order to alternatively and effectively use the motors (A) and (B) as required; and
connecting the lockup clutch by electronic hybrid engine control means after setting the driving force to substantially zero in addition to making an r.p.m. of the first motor (A) to coincide with the r.p.m. of the second motor (B) when a driving condition is transiting from the series running mode to the parallel running mode; and
disconnecting the lockup clutch after making the r.p.m. of the f
Jinbo Yoshitaka
Nitta Tomoaki
Farber Martin A.
Fuji Jukogyo Kabushiki Kaisha
Ho Ha
Marmor Charles A
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