Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Electric vehicle
Reexamination Certificate
1999-12-03
2001-11-06
Beaulieu, Yonel (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Electric vehicle
C320S104000, C320S132000, C180S065100, C180S065230, C180S065310
Reexamination Certificate
active
06314346
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a control system for a hybrid vehicle with an engine and a motor, and in particular, to a control system for a hybrid vehicle which appropriately charges a battery even when the vehicle is cruising and the engine is not assisted by the motor.
This application is based on Japanese Patent Application No. Hei 10-347543, 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 series hybrid vehicles, the engine drives a generator, which outputs electric power to the motor, and the motor drives the wheels.
Because the engine and the wheels are not mechanically connected, the engine constantly runs within a rotational range which reduces fuel consumption and emissions, as compared with conventional engine vehicles.
In parallel hybrid vehicles, the motor connected to the engine assists the rotation of the drive shaft of the engine while charging a battery using a generator which is separate from the motor or is the motor itself.
Although the engine and the wheels are mechanically connected, the parallel hybrid vehicle can reduce the load to the engine. Thus, the parallel hybrid vehicle also has reduced fuel consumption and emissions as compared with conventional engine vehicles.
In the parallel hybrid vehicle, the motor for assisting the output of the engine is directly connected to the output shaft of the engine, and acts as a generator for charging the battery when the vehicle speed is reduced. Alternatively, either or both of the engine and the motor may generate the drive power, and the generator may be provided separately.
When a hybrid vehicle accelerates, the engine is assisted by the motor, and, when it decelerates, various operations are performed, such as charging the battery by deceleration regeneration, so as to maintain sufficient electric energy in the battery (hereinafter referred to as the “state of charge (remaining charge)”) to meet the driver's demands. Specifically, because high deceleration regeneration is obtained after high speed cruising, the battery regains a part of the consumed energy when decelerating. After the vehicle goes up a slope such as a mountain path, the vehicle can charge its battery by deceleration regeneration when the vehicle goes down (as disclosed in, for example, Japanese Patent Application, First Publication No. Hei 7-123509).
In the conventional hybrid vehicles, in particular, in the parallel hybrid vehicle in which the driving shaft of the engine is connected with the motor, when the vehicle is cruising while the motor does not perform torque assist for the driving shaft of the engine, the motor acts as a generator, thereby increasing the remaining charge of the battery.
The remaining charge, however, is not always increased when the vehicle is running. The remaining charge mainly depends on the past running condition. The amount of electric power generation should be adjusted appropriately in consideration of the remaining charge.
When the remaining charge is decreasing depending on the running condition and on the road condition, the amount of electric power generation must be adjusted so as to stop the decrease of the remaining charge.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a control system for a hybrid vehicle which adjusts the amount of electric power generation, taking in consideration the remaining charge of the battery, when the vehicle is cruising.
In a first aspect of the present invention, the control system is provided for a hybrid vehicle with an engine (E) for producing a driving force for the vehicle, a motor (M) for producing an assist driving force to assist the output from the engine, and a power storage unit (battery
3
) for supplying electric energy to the motor and storing regenerated energy produced by regeneration of the motor when the vehicle decelerates. The control system comprises: a charge zone determining device (steps S
402
, S
405
, and S
409
) for determining whether the state of charge (SOC) is within normal use range (zone A), temporary use range (zone B), over-discharge range (zone C), or over-charge range (zone D); a generation mode selector (steps S
403
, S
406
, S
410
, and S
411
) for selecting one of a normal generation mode (step S
410
) corresponding to the normal use zone, a low generation mode (step S
411
) corresponding to the temporary use zone, a high generation mode (step S
406
) corresponding to the over-discharge zone, and a generation stop mode (step S
403
) corresponding to the over-charge zone, based on the determination by the charge zone determining device; and a generation amount setter (step S
414
) for setting the amount of electric power generation corresponding to each mode.
First, the charge zone determining device determines the remaining charge of the power storage unit. Then, the generation mode setter selects the mode. That is, when in the over-charge zone, the generation stop mode is selected. When in the over-discharge zone, the high generation mode is selected. When in the temporary use zone, the low generation mode is selected. When in the normal use zone, the normal generation mode is selected. The amount of electric power generation is set depending on the generation stop mode, the high generation mode, the low generation mode, and the normal generation mode by the generation amount setter.
The present invention can appropriately control the SOC, taking into consideration the remaining charge, because the generation amount setter sets the amount of generation, depending on the generation mode determined by the charge zone determining device.
In a second aspect of the present invention, the system further comprises: a DOD limit determining device (step S
407
) for determining whether the vehicle is in a depth-of-discharge limit control mode, in which the power storage unit is charged to recover the initial state of charge (SOCINT in step S
101
), which was detected at the starting of the vehicle, when the remaining charge is decreased from the initial state of charge by a predetermined amount (DODLMT in step S
102
). When the DOD limit determining device determines that the vehicle is in the depth-of-discharge limit control mode, the generation mode selector selects a DOD limit generation mode (step S
408
), and the generation amount setter sets the amount of generation corresponding to the DOD limit generation mode.
When DOD limit determining device determines that the vehicle is in the depth-of-discharge limit control mode, the generation mode selector selects the DOD limit generation mode, and the generation amount setter appropriately sets the amount of electric power generation corresponding to the depth-of-discharge limit control mode when the vehicle is cruising.
In the depth-of-discharge limit control mode, the generation is increased (step S
408
of initiating the DOD limit generation mode when in the cruise mode), the frequency of charging the power storage unit is increased (step S
245
of increasing the value for the throttle assist trigger), and the assist amount is decreased (step S
318
of decreasing the assist amount when in the acceleration mode).
In a third aspect of the present invention, the electric power generation set by generation amount setter has the relationship of: the electric power generated in the high generation mode>the electric power generated in the low generation mode≧the electric power generated in the DOD limit generation mode>the electric power generated in the normal generation mode>the electric power generated in the generation stop mode=0.
As the remaining charge of the power storage unit decreases, the generation is increased. When the power storage unit is over-charged, the generation is stopped. More electric power is genera
Fukuchi Hironao
Izumiura Atsushi
Kitajima Shinichi
Kumagai Katsuhiro
Uchida Keisuke
Armstrong,Westerman, Hattori, McLeland & Naughton, LLP
Beaulieu Yonel
Honda Giken Kogyo Kabushiki Kaisha
LandOfFree
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 Control system for hybrid vehicle, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Control system for hybrid vehicle will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2605011