Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Transmission control
Reexamination Certificate
1999-07-29
2001-06-12
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Transmission control
C701S053000, C074S824000, C477S110000, C477S120000
Reexamination Certificate
active
06246942
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention concerns a system for evaluating vehicle, drive and operation parameters.
The desire for greater economy in motor vehicles with very good driveability demands, better coordination in the characteristic field of a prime mover and the vehicle operating conditions over the most favorable operating ranges. This is achieved with a multi-step or continuously variable transmission having a large speed ratio range. To be able to utilize the advantages, the transmission has to be optimally gear shifted or adjusted, which imposes high demands on the driver. If the continuously variable transmission is regarded as a transmission with several unlimited steps, considerations that apply to multi-step transmissions can, generally, be similarly transferred to a continuously variable transmission. Therefore, for the sake of simplicity, reference will hereinafter is particularly made to multi-step transmissions using the terminology adapted thereto.
In order to unburden the driver and increase comfort in driving, there is increasingly offered vehicles which have a fully automated train consisting of an engine, a starting element, such as a clutch and/or a converter, a gear with different speed ratios and a drive axle with wheels.
Part of the automation consists in selecting, for the respective operating state of the vehicle, a favorable speed ratio and determining the correct gear shift moment. At the same time, it must be taken into consideration that economy and driving comfort must not be impaired by too frequent gear shifts.
Already known are automatically shifting step-changing gears for motor vehicles which automatically shifted within the range of the gears available primarily depending on the number of revolutions and which are proportional to the driving speed and on load states, such as the position of the accelerator pedal or throttle pedal when idling, part load, full load or kick-down. In order to reduce the number of gear shifts, the driver can eliminate from the gear shift sequence, via a selector switch, gears in the upper or lower range, e.g. when mountain driving or in winter operation.
From DE 32 47 658 A is known, by a separate selector lever, to exclude from the automatic gear shift the number of gears not only in the upper range but also simultaneously in the lower range. This is especially favorable when idling or traveling with part load. Of course, the reduced number of automatically shiftable gears results in poor adaptation to the economic operating range of the engine.
It is further known from ATZ 85 (1983) 6, p. 393 ff that a electronic microprocessor system can determine the gear to engage according to a predetermined computing program. In one gear shift characteristic field, if an upshift or downshift characteristic line is reached, the electronic system triggers a corresponding gear shift operation. During the gear shift operation, the torque of the engine becomes reduced in order less to load the friction elements and improve driving comfort. For different driving situations, several programs are provided which have different gear shift characteristic fields. It is possible here to automatically change between the individual gear shift characteristic fields. It is also possible to adapt the gear shift characteristic lines according to desired operation parameters.
For commercial motor vehicles, multi-step mechanical transmissions are often used which are shifted with traction interruption. EP 0 255 519 B1 has disclosed a control device for automatic gear shifting of multi-gear step changing transmissions in which the gear shift points are established depending on the vehicle speed, the momentary requirement (throttle pedal position) and the acceleration determined from the number of revolutions of the gear output shaft. The acceleration is divided in six ranges, namely, a high deceleration, a low deceleration, a constant drive, a low acceleration, a medium acceleration and a high acceleration. Deceleration is computationally considered as negative acceleration.
Besides, the throttle pedal position is divided in three ranges, namely, an empty gas range, a medium position and a full gas range. With each range of the throttle pedal position is associated an acceleration range so that under said premisses eighteen gear shift points result. The gear shift conditions for the gear shift points are contained in tables wherein the values are empirically or computationally determined. According to the number of travel programs used, several tables are needed. The characteristic fields and tables required for the gear shift must be adapted to each type of vehicle and drive train. This involves considerable expenditure, since more than 3000 data must be considered. Besides, changes between the many unevenly stepped gear shift conditions are critical, since interactions can easily be generated which act unfavorably on the driveability of the vehicle.
SUMMARY OF THE INVENTION
The invention is based on the problem of providing a system for the selection of the gear speed ratios which can be uniformly applied to different, automatically adjustable gears and require less tuning parameters.
The invention is adequate for all vehicles having a fully or partly automated drive train consisting of an engine with or without a starting element, such as a clutch and/or a converter, a gear with different speed ratios and a drive axle with vehicle wheels. This transmission can be both a continuously variable transmission or a stepped transmission which is shifted with traction interruption or under load.
For each speed ratio or for each speed ratio range, a minimum dwell time is preset during which the speed ratio is not adjusted unless the vehicle acceleration is so high that during this time an upper or lower gear shift limit number of revolutions is reached.
Also preset is an adaptively fittable adjustment time, gear shift time, which on average is needed to change the gear from one speed ratio to another speed ratio. Taking into account the vehicle acceleration from the minimum dwell time and the adjustment time, an appertaining change in number of revolutions of the engine is calculated from which a set change in number of revolutions is determined. Finally, a gear shift number of revolutions is calculated as function of the set change in number of revolutions, of a minimum or maximum and of an economical optimum operation number of revolutions of an engine. In the engine characteristic field, the shift number of revolutions lies between an economical operation range and a lower or upper limit of number of revolutions of the engine. The ratio of the optimum operation number of revolutions to the gear shift number of revolutions is equal to the ratio of the set speed ratio to the real speed ratio. The change of speed ratio or the new speed ratio is engaged in order to return the operation point of the engine with an equal performance as possible to the economy range as soon as the real number of revolutions reaches or exceeds the gear shift number of revolutions.
Since the essential control parameters are interlinked by computer rules, consistent, clear evaluations result, and the number of parameters to be coordinated is substantially diminished by a factor 10. It is convenient to multiply the minimum dwell time, corresponding to different driving states, by preset factors. The minimum dwell time, can e.g. be multiplied in a kick-down downshift by the factor 1.4 and in a coasting downshift by the factor 0.2. Generally these factors do not apply, but must be synchronized with the existing vehicle type empirically or adaptively according to an optimization criterion.
If the speed ratio change is certain, a gear shift is effected as soon as the real number of revolutions reaches or exceeds the determined gear shift number of revolutions, specifically downwardly relative to a downshift and upwardly when an upshift must be effected. It has to be taken into account here that the minimum and maximum operation number of revolutions of the engine stil
Dobler Siegfried
Mayer Karl
Wolz Udo
Cuchlinski Jr. William A.
Davis and Bujold
Donnelly Arthur D.
ZF Friedrichshafen AG
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