Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Indication or control of braking – acceleration – or deceleration
Reexamination Certificate
2000-03-09
2001-10-23
Zanelli, Michael J. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Indication or control of braking, acceleration, or deceleration
C701S070000, C180S170000
Reexamination Certificate
active
06308128
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a driving force control for an automotive vehicle.
BACKGROUND OF THE INVENTION
The term “standard resistance” or “standard running resistance” is herein used to mean any force which opposes the motion of an automotive vehicle which is driven to keep rolling over the surface of a flat road having 0% gradient at a constant vehicle speed. The term “running resistance” is herein used to mean any force which opposes the motion of an automotive vehicle which is driven to keep rolling over the surface of a road at a constant vehicle speed. Running resistance is equal to standard resistance if an automotive vehicle is driven to keep rolling over the surface of a flat road having 0% gradient at a constant vehicle speed. Running resistance increases and becomes greater than standard resistance if the automotive vehicle is accelerated to increase speed from the constant vehicle speed. The term “acceleration resistance” is herein used to mean this increment or difference in running resistance that has occurred due to acceleration. Running resistance is greater when the automotive vehicle is driven to keep rolling over the surface of a flat road having gradient greater than 0% at a constant vehicle speed than standard resistance for the same vehicle speed. The term “gradient resistance” is used to mean this increment or difference in running resistance.
JP-A 9-242862 discloses a driving force control system in which a speed ratio between an input shaft and an output shaft of an automatic transmission is controlled in response to road gradient, throttle opening degree, and vehicle speed. In order to estimate road gradient of a road, over which the vehicle is rolling, a road gradient torque (T&agr;) is determined by subtracting from a driving torque (To) a sum of a flat road running resistance torque (Tr) and an acceleration resistance torque (T&agr;). A characteristic of variation of flat road running resistance torque (Tr) against variation of vehicle speed is mapped. This mapped data are retrieved using a current reading point of vehicle speed to give a value of flat road running resistance torque (Tr).
JP-A 7-174042 discloses a driving torque control system for an automotive vehicle. This system adjusts a torque control element of an internal combustion engine in such a direction as to decrease a difference between an estimated driving torque and a target driving torque. Calculating product of an engine torque, a stall torque ratio of a torque converter, and a gear ratio of an automatic transmission gives the estimated driving torque. Retrieving a predetermined map gives the target driving torque against running condition of the vehicle. If there remains a portion of the difference between the estimated driving torque and the target driving torque, a braking torque is applied to cause a reduction in driving torque to assist in decreasing the estimated driving torque toward the target driving torque.
SUMMARY OF THE INVENTION
It is recognized as a potential problem that, at idling operation after operator releasing an accelerator pedal, a drop in detection accuracy of engine speed causes a considerable deviation of estimated value of driving torque from an actual value thereof. The deviation of the estimated driving torque might cause an error in estimated value of gradient resistance torque. Thus, a correction amount in driving force varies with varying estimated gradient resistance torque as shown by one dot chain line in FIG.
4
. The profile of this one dot chain line shows that there occur various deviations of the driving force correction amount from the target value. The occurrence of such various deviations may deteriorate ride feel of the vehicle operator.
On ascending road, if the vehicle operator releases the accelerator pedal to make a turn, the driving force may be subjected to an excessive correction due to the above-mentioned variations because the correction depends only on the estimated gradient resistance torque. Such excessive correction may deteriorate ride feel of the vehicle operator.
It is also recognized as another potential problem that a portion of torque that is converted into heat due to friction within a brake upon depressing a brake pedal might be detected as an increase in gradient resistance torque. If so, the degree of deceleration becomes low and may not meet operator deceleration demand.
If it employs the technique of increasing brake pressure to reduce the estimated driving torque during operation of driving force control, the driving force is increased in response to erroneous detection of increase in gradient resistance torque when the brake pressure is increased during braking operation at ascending road.
Accordingly, an object of the present invention is to provide a driving force control free from the above-mentioned potential problems.
One feature of the driving force control system is to prevent occurrence of undesired variation in driving force at engine idling or at braking.
According to one aspect of the present invention, there is provided a driving force control system for an automotive vehicle having an accelerator pedal and a powertrain including an internal combustion engine, comprising:
a vehicle speed sensor detecting an operating parameter indicative of a speed of the vehicle and generating a vehicle speed signal indicative of the detected operating parameter;
an ordinary target driving force generator determining an ordinary target driving force in response to operator manipulation of the accelerator pedal and the vehicle speed indicated by the vehicle speed signal and generating an ordinary target driving force signal indicative of the determined ordinary target driving force, the ordinary target driving force being a predetermined target value of driving force required to keep the vehicle rolling over the surface of a flat road that has 0% gradient;
a running resistance increment generator determining an increment in running resistance from a standard resistance that is predetermined for the vehicle and generating a running resistance increment signal indicative of the determined increment in running resistance;
an idle switch detecting idle operation of the engine and generating an idle signal;
a brake switch detecting braking operation of the vehicle and generating a brake signal;
a corrected target driving force generator receiving the ordinary target driving force signal, the running resistance increment signal, the idle signal, and the brake signal, and determining corrected target driving force, and generating the determined corrected target driving force,
the corrected target driving force generator being operative to restrain influence of the running resistance increment on the determined corrected target driving force when the idle signal and the brake signal indicate one of idle operation and brake operation.
REFERENCES:
patent: 5038880 (1991-08-01), Matsuoka et al.
patent: 5197564 (1993-03-01), Nishimura et al.
patent: 5557519 (1996-09-01), Morita
patent: 5845726 (1998-12-01), Kikkawa et al.
patent: 5925087 (1999-07-01), Ohnishi et al.
patent: 5961566 (1999-10-01), Heslop
patent: 6029107 (2000-02-01), Sato
patent: 6076032 (2000-06-01), Kuroda et al.
patent: 6104976 (2000-08-01), Nakamura
patent: 6188945 (2001-02-01), Graf et al.
patent: 7-174042 (1995-07-01), None
patent: 09207735 A (1997-08-01), None
patent: 9-242862 (1997-09-01), None
Nishijima Hiroaki
Toukura Nobusuke
Yasuoka Masayuki
Foley & Lardner
Gibson Eric M
Nissan Motor Co,. Ltd.
Zanelli Michael J.
LandOfFree
Driving force control for automotive 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 Driving force control for automotive vehicle, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Driving force control for automotive vehicle will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2596904