Electricity: motive power systems – Positional servo systems – With stabilizing features
Reexamination Certificate
2002-02-04
2003-09-16
Masih, Karen (Department: 2837)
Electricity: motive power systems
Positional servo systems
With stabilizing features
C318S139000, C180S065230
Reexamination Certificate
active
06621244
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a control apparatus for a hybrid vehicle in which a propulsion force for running the vehicle is generated by output from an engine assisted by an electric motor as required.
BACKGROUND ART
Heretofore, there is known a hybrid vehicle incorporating an electric motor in addition to an engine as a drive source for vehicle propulsion.
One type of such hybrid vehicle is a parallel hybrid vehicle wherein an electric motor rotated by electricity is used as an auxiliary drive source for assisting the output from an engine, being an internal combustion engine. In this parallel hybrid vehicle, various control is carried out, such as assisting the output from the engine by means of the electric motor at the time of acceleration for example, and charging a battery by deceleration regeneration at the time of deceleration, so that the stored charge of the battery can be maintained while satisfying the requirements of the driver. (For example, as disclosed in Japanese Unexamined Patent Application, First Publication No. Hei 7-123509.)
An engine, being an internal combustion engine, sometimes generates unpleasant vibrations at the time of low speed, that is, when idling. In a hybrid vehicle as described above, an electric motor that can reliably control torque electrically is incorporated into the engine, so that the engine vibration can be suppressed by controlling the torque of this electric motor. The present inventor has filed a first application for an engine vibration damping apparatus using such an electric motor (Japanese Unexamined Patent Application, First Publication No. Hei 9-248374).
Such an engine vibration control apparatus generates a plurality of different sine waves in proportion to the rotational frequency of the engine output shaft depending on the running conditions of the engine, generates a composite wave of these sine waves as a torque waveform for the electric motor to generate to reduce the torque variation of the engine output shaft, and controls the vibration by controlling the electric motor according to this composite wave torque waveform. In order to operate such an engine vibration damping apparatus, some energy may be consumed.
Accordingly, if such vibration damping control is performed at the time of idling for example, depending on the state of power being consumed elsewhere in a vehicle, such as lighting, wiper operation, or furthermore the operation of a car stereo or the like, the electric power supply generated by the engine may be insufficient, and the deficiency is drawn from the electric motor battery, resulting in the stored charge of the electric motor battery being reduced. In this manner, if the stored charge of the electric motor battery is reduced, assistance cannot be given to the engine even if the conditions require it.
DISCLOSURE OF THE INVENTION
The present invention takes into consideration the above situation, with an object of providing a control apparatus for a hybrid vehicle that prevents a situation in which a stored charge of an electric motor battery is reduced below a minimum required due to the vibration damping control device being operated, in other words, priority is given to preventing the stored charge of the electric motor battery being reduced below the minimum required, so that the occurrence of a situation that requires assistance to the engine by the electric motor can be handled without fail.
Furthermore, the present invention has an object of providing a control apparatus for a hybrid vehicle that can prevent the stored charge of the electric motor battery from being reduced below the minimum required at the time of idling, and additionally can increase the stored charge.
To achieve the abovementioned objects, a control apparatus for a hybrid vehicle (for example, an ECU in embodiments) of a first aspect of the invention comprises: an engine (for example, an engine
11
in the embodiment) which outputs a propulsion force for a vehicle; an electric motor (for example, a motor
12
in the embodiment) which assists the output from the engine; a battery (for example, an electric motor battery
17
in the embodiment) for an electric motor that drives the electric motor and also stores electric power generated by the electric motor; and a storage state monitoring device (for example, a current sensor
24
and an ECU
15
in the embodiment) which monitors the stored charge of the electric motor battery, and is characterized in that one condition for permitting operation of vibration damping control by the electric motor, for suppressing vibration caused by torque variation of the engine, is that a stored charge of the electric motor battery detected by the battery storage state monitoring device must be greater than a predetermined stored charge threshold, and when the condition is satisfied, vibration damping is performed by the vibration damping device, or alternatively when the condition is not satisfied, vibration damping by the vibration damping device is inhibited.
Here, vibration damping control for controlling engine vibration by the electric motor is performed through a vibration damping device (for example, a power drive unit
16
in the embodiment).
With such a construction, only in the case where the stored charge of the electric motor battery is greater than a predetermined stored charge threshold, that is, only in the case where there is some surplus stored charge in the electric motor battery, is vibration damping control performed by the vibration damping device. Accordingly, a situation does not occur in which there is no surplus stored charge of the electric motor battery, leading to the stored charge of the electric motor battery being reduced below the minimum required due to the operation of the vibration damping control device.
A second aspect of the invention is characterized in that conditions for permitting operation of vibration damping control require that, in addition to a stored charge of the electric motor battery detected by the storage state monitoring device being greater than a predetermined stored charge threshold (for example, a determination of step S
9
in the embodiment), the vehicle is idling (for example, a determination of step S
1
of the embodiment), engine speed is within a prescribed range (for example, a determination of step S
5
in the embodiment), and engine load is within a prescribed range (for example, a determination of step S
6
in the embodiment), and vibration damping control is performed when all conditions are satisfied.
With such a construction, it is possible to perform vibration damping control in a state where there is some surplus stored charge in the electric motor battery, the vehicle is idling, and the engine rotation is stable in regard to the engine speed and engine load, but excepting a case where a high load is required on the engine, that is, only when vibration damping control is genuinely required.
A third aspect of the invention is characterized in that conditions for permitting operation of the vibration damping device require that an electrical load of the vehicle excluding the electric motor is greater than a predetermined electrical load threshold (for example, a determination of step S
10
in the embodiment), and when the electrical load exceeds the predetermined electrical load threshold, vibration damping control by the vibration damping device is performed for a predetermined limited time (for example, step S
12
in the embodiment), and conversely, when the electrical load is less than or equal to the predetermined electrical load threshold, vibration damping control by the vibration damping device is performed without any set time limit (for example, step S
11
in the embodiment).
With such a construction, in the case where the electrical load of the vehicle is high, the electric power produced by the engine is insufficient, and the deficiency is drawn from the electric motor battery, vibration damping control can be performed only for a predetermined limited time. Accordingly, it is possible to
Izumiura Atsushi
Kitajima Shinichi
Kiyomiya Takashi
Kuroda Shigetaka
Matsubara Atsushi
Armstrong Westerman & Hattori, LLP.
Honda Giken Kogyo Kabushiki Kaisha
Masih Karen
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