Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Transmission control
Patent
1998-07-21
2000-03-28
Wolfe, Willis R.
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Transmission control
701110, 477111, 123399, B60K 4106, F02D 1110, F02D 4104
Patent
active
060443189
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to powertrain control systems for motor vehicles.
BACKGROUND TO THE INVENTION
It is becoming increasingly common to eliminate the traditional direct link, (usually a mechanical linkage such as a "Bowden" cable), between the driver operated accelerator pedal of a motor vehicle and the fuelling system of its engine. It is replaced with electrical control of the engine fuelling, normally in the form of an engine management system running closed loop feed-back control. Such systems are commonly known in the art as "drive by wire".
"Drive by wire" systems usually employ a pedal demand potentiometer connected to the driver operated accelerator pedal to provide a signal of demanded power to the engine management system. The engine management system controls the supply of fuel and air to the engine in response to that pedal demand signal.
When a vehicle is to be used off-road, in conditions where the surface over which it is travelling is rough or uneven, there is a requirement for a low sensitivity in the accelerator pedal, at least over the initial range of pedal travel. This is because there is generally a lot of vibration which makes the vehicle hard to control if the accelerator is too sensitive. On the other hand, for on-road driving, where the driving surface is relatively smooth, a more sensitive accelerator pedal is usually preferable to give a more powerful feel to the vehicle. Known systems generally result in a compromise between these conflicting requirements.
EP 0 322 790 discloses a slip control system in which various throttle characteristics are available which limit the power available to varying degrees. The control system changes between characteristics to reduce power if slip is detected.
GB 2154763 and FR 2483012 each disclose a system having different throttle characteristics which are selectable by the driver to give the driving characteristics required, such a sporty feel or economy of fuel.
U.S. Pat. No. 5,111,570 discloses a throttle regulated traction control system which varies the response of the throttle so as to match the slip rate of the drive wheels with a target slip rate. The object of U.S. Pat. No. 5,111,570 is to prevent a loss of speed when driving on rough roads which might result from an erroneously high determination of the slip rate and subsequently undue decrease in the driving force available.
The problem outlined above has not been addressed by the prior art.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides a powertrain control system for a motor vehicle comprising a power output varying means for varying the power output of the vehicle powertrain, a driver operated power demand means for producing a power demand signal, detection means for detecting whether the vehicle is in an on-road driving condition or an off-road driving condition, and a control means operative to control said varying means in response to said power demand signal in accordance with a control characteristic wherein said control means can select either of first and second different control characteristics over at least a range of conditions of the power demand means, characterized in that the power demand means is movable by a driver through a range of positions to vary the power demand signal, in that when the first characteristic is selected, for low displacements of the power demand means, the control means is more sensitive to changes in the power demand signal than when the second characteristic is selected, and in that the control means is arranged to select the first characteristic when the vehicle is in the on-road condition and the second characteristic when the vehicle is in the off-road condition.
The power varying means may comprise a throttle valve or a fuel supply system such as a fuel injection system.
Preferably the characteristics relate the condition of the power output varying means to the power demand signal.
Preferably each of the characteristics is applicable over substantially the full range of operable
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Bourdon Klaus
Haggett Martin Roy
Meisberger Deiter
Rose Axel
Woolley Andrew Peter
Bayerische Motoren Werke AG
Rover Group Limited
Wolfe Willis R.
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