Prime-mover dynamo plants – Electric control – Engine control
Reexamination Certificate
2000-03-07
2001-11-13
Ponomarenko, Nicholas (Department: 2834)
Prime-mover dynamo plants
Electric control
Engine control
C322S016000, C180S065510
Reexamination Certificate
active
06316842
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an engine control system for a hybrid vehicle, and, more particularly, to an engine control system which stops or restarts the engine in consideration of the remaining charge of a high-voltage battery and the amount of power consumption by accessories or other devices.
This application is based on Japanese Patent Application No. 11-62414, the contents of which are incorporated herein by reference.
2. Description of the Related Art
Conventionally, hybrid vehicles which carry motors as power sources for driving the vehicles in addition to engines are known. Hybrid vehicles are divided into series hybrid vehicles and parallel hybrid vehicles. In the series hybrid vehicles, the engine drives a generator whose electric power output is used to drive the motor, which in turn drives the wheels. In the parallel hybrid vehicles, the motor coupled to the engine assists the rotation of the drive shaft of the engine while charging a high-voltage battery with electric energy using the motor itself as a generator or using a separate generator.
Because the engines of such hybrid vehicles can constantly run within the engine-speed range of a high fuel mileage and a low emissions level or their drive loads can be reduced, the hybrid vehicles can achieve lower fuel consumption and lower emissions levels than conventional engine vehicles.
As disclosed in, for example, Japanese Unexamined Patent Application, First Publication Hei 8-317505, some of those hybrid vehicles are designed to be capable of stopping the operation of the engine in accordance with predetermined driving conditions.
Because of the ability to stop the operation of the engine, such a hybrid vehicle is superb in preventing over-charging of the battery or achieving a further improvement on the fuel consumption by stopping the operation of the engine in accordance with predetermined operational conditions, such as the remaining charge of the battery, but has the following problem.
For example, while a certain amount of energy remains in the battery when fuel supply cut is carried out during deceleration, it is not adequate to keep fuel supply cut and stop the engine when the 12-V system consumes a large amount of power and energy should be supplemented from the high voltage battery to the 12-V battery, e.g., when turning on head lights while driving the vehicle in a night.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an engine control system for a hybrid vehicle, which can stop the engine in accordance with the power consumption of the 12V system.
To achieve this object, according to one aspect of this invention, an engine control system for a hybrid vehicle, which is equipped with an internal combustion engine (e.g., an engine E in one embodiment) and an electric motor (e.g., a motor M in the embodiment) as driving force sources and a power storage unit, and permits stopping and starting of the engine in accordance with predetermined drive conditions, comprises: power-consumption detector (e.g., the 12V system power-consumption sensor S
8
in the embodiment) for detecting the amount of power consumption by a predetermined device (e.g., accessories such as lights and an air conditioner, or an ECU); first power storage unit (e.g., a high-voltage battery BAT in the embodiment) for supplying electric energy to said motor and storing energy generated when the electric motor is operated as a generator by the internal combustion engine and energy regenerated by regeneration; second power storage unit (e.g., a 12-volt (low-voltage) auxiliary battery 12BAT in the embodiment) for supplying electric energy to the predetermined device; remaining charge detector (e.g., a current sensor S
7
or the like in the embodiment) for detecting a remaining charge of the first power storage unit (e.g., a remaining charge QBAT in the embodiment); stop/start determination device (e.g., step Sill, step S
216
and step S
316
in the embodiment) for determining whether to permit stopping or starting of the engine in accordance with the amount of power consumption by the predetermined device (e.g., the amount of 12V system power-consumption VELIDLn in the embodiment) and the remaining charge of the power storage unit; engine stopper (e.g., step S
129
and step S
320
in the embodiment) for stopping the engine based on a result of a decision by the stop/start determination device; and engine starter (e.g., step S
209
and step S
323
in the embodiment) for starting the engine based on the result of the decision by the stop/start determination device.
With the above structure, because stopping and starting of the engine can be permitted in accordance with the power consumed by the predetermined device and the remaining charge of the first power storage unit, the engine can be stopped according to the actual conditions based not only on the remaining charge of the first power storage unit but also on the amount of power consumption of the predetermined device. This can prevent the occurrence of the situation that while the engine is stopped because of certain amount of charge remains in the power storage unit, a large amount of power consumption by the predetermined device actually reduces the remaining charge of the first power storage and thus disables restarting of the engine.
The predetermined drive conditions for stopping the engine are, for example, such that on the premise that the engine can be started by the motor (e.g., when a motor-start enable/disable flag F_MOTSTB is “1” in step S
106
in the embodiment), the amount of the remaining battery charge (or the state of charge) SOC is equal to or above an over-discharge area (e.g., an energy-storage-zone flag F_ESZONE is “0” in step S
107
in the embodiment), and the engine coolant temperature TW is equal to or higher than a predetermined level (e.g., the coolant temperature TW is equal to or higher than a coolant-temperature lower limit TWFCMG in step S
108
in the embodiment).
According to another aspect of this invention, the first power storage unit supplies electric energy to the second power storage unit via a downverter, and is capable of supplying power to drive the predetermined device via the downverter, the stop/start determination device determines to permit stopping of the engine when the remaining charge of the power storage unit is equal to or greater than an upper threshold value of the remaining charge of the power storage unit (e.g., an engine-stop disable high-voltage battery capacity upper limit QBATIDHN in the embodiment) set in association with the amount of power consumption by the predetermined device, and determines to permit starting of the engine when the remaining charge of the power storage unit is equal to or smaller than a lower threshold value of the remaining charge of the power storage unit (e.g., an engine-stop enable high-voltage battery capacity lower limit QBATIDLN in the embodiment) set in association with the amount of power consumption by the predetermined device.
The stopping of the engine operation can include fuel supply cut when the vehicle decelerates. This can permit suppression of fuel consumption when the vehicle is decelerating. In this case, returning from the fuel cutting state or restart of fuel supply is implemented in accordance with the remaining charge of the power storage unit and the amount of power consumption by predetermined device.
REFERENCES:
patent: 5212431 (1993-05-01), Origuchi et al.
patent: 5697466 (1997-12-01), Moroto et al.
patent: 5771478 (1998-06-01), Tsukamoto et al.
patent: 5818116 (1998-10-01), Nakae et al.
patent: 5909720 (1999-06-01), Yamaoka et al.
patent: 6131538 (2000-10-01), Kanai
patent: 6166517 (2000-12-01), Wakashiro et al.
patent: 6216465 (2001-04-01), Wakashiro et al.
patent: 196 20 988 (1997-11-01), None
patent: 8-317505 (1996-11-01), None
Fukuchi Hironao
Kuroda Shigetaka
Takahashi Hideyuki
Wakashiro Teruo
Armstrong Westerman Hattori McLeland & Naughton LLP
Honda Giken Kogyo Kabushiki Kaisha
Ponomarenko Nicholas
LandOfFree
Engine control system for hybrid vehicle does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Engine control system for hybrid vehicle, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Engine control system for hybrid vehicle will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2610309