Interrelated power delivery controls – including engine control – Clutch control – Condition responsive control
Reexamination Certificate
1999-10-25
2001-10-02
Bonck, Rodney H. (Department: 3681)
Interrelated power delivery controls, including engine control
Clutch control
Condition responsive control
C477S005000
Reexamination Certificate
active
06296593
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to control of an electromagnetic clutch of a hybrid drive vehicle which performs regenerative braking using a generator.
BACKGROUND OF THE INVENTION
A parallel hybrid drive vehicle which runs under the drive force of a motor or an engine, or both, is disclosed in pp. 39-52 of “Automobile Engineering”, Vol. 46, No. 7 published in June, 1997 in Japan by Tetsudo Nihon Sha.
In this hybrid drive vehicle, when the load is small, the vehicle runs on the output of the motor alone, and when the load increases, the vehicle starts the engine to provide sufficient drive force.
On the other hand, during deceleration, so-called regenerative braking is performed wherein the motor is driven as a generator by the rotational energy of the drive wheels, and the power generated is used to charge a battery.
SUMMARY OF THE INVENTION
In order to increase power generation efficiency in regenerative braking, it is desirable to disengage the clutch which connects the drive wheels and the engine, and use all the deceleration force for power generation.
However, if the clutch is disengaged during deceleration, a time required for the re-engaging of the clutch will cause an energy loss of the engine and result in a delay in the acceleration response of the vehicle from the deceleration state.
In order to increase the response of the re-engaging of the clutch, the use of an electromagnetic clutch such as an electromagnetic powder clutch which can vary the engaging torque according to an energizing current, may be considered. Specifically, full release of the clutch is not performed during acceleration, but a weak energizing current to allow some transfer of torque, and improve the response of the re-engaging of the clutch.
However, if the clutch is frequently put into this partially engaged state, it leads to wear of clutch components such as powder, and the life of the clutch will be shortened. Moreover, since energy is consumed within the clutch, the power generation amount of the motor/generator decreases, and the energy recovery efficiency declines.
It is therefore an object of this invention to increase the energy recovery efficiency during regenerative braking without affecting the acceleration response of the vehicle from the deceleration state.
In order to achieve the above object, this invention provides an electromagnetic clutch control device for use with such a vehicle that comprises a generator connected to a drive wheel, a battery electrically connected to the generator, a conversion circuit which converts a power generated by the generator into a power stored by the battery, an engine and an electromagnetic clutch which transmits an output torque of the engine to the drive wheel under an engaging force according to an energizing current. The control device comprises a sensor which detects an output rotation speed of the electromagnetic clutch, a sensor which detects that the vehicle is in a predetermined deceleration state, and a microprocessor programmed to supply the energizing current to the electromagnetic clutch, and increase the energizing current the lower the output rotation speed of the electromagnetic clutch, when the vehicle is in the predetermined deceleration state.
This invention also provides a method for controlling an electromagnetic clutch of such a vehicle that comprises a generator connected to a drive wheel, a battery electrically connected to the generator, a conversion circuit which converts a power generated by the generator into a power stored by the battery, and an engine connected to the drive wheel via the electromagnetic clutch. The electromagnetic clutch transmits an output torque of the engine to the drive wheel under an engaging force according to an energizing current. The control method comprises detecting an output rotation speed of the electromagnetic clutch, detecting that the vehicle is in a predetermined deceleration state; and increasing the energizing current supplied to the electromagnetic clutch the lower the output rotation speed of the electromagnetic clutch, when the vehicle is in the predetermined deceleration state.
The details as well as other features and advantages of this invention are set forth in the remainder of the specification and are shown in the accompanying drawings.
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Toyota Motor Corporation, “Toyota Hybrid System”, Press Information, see pp. 4-9,1997.*
Tetsundo Nihon Sha, “Automobile Engineering”, vol. 46, No. 7, pp. 39-52, Jun. 1997.
Gotou Yuuji
Hattori Noboru
Bonck Rodney H.
Foley & Lardner
Nissan Motor Co,. Ltd.
Pang Roger
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