Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Transmission control
Reexamination Certificate
2000-11-07
2002-09-24
Zanelli, Michael J. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Transmission control
Reexamination Certificate
active
06456919
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a process for controlling switching or shifting processes in automatic gears for use in drivelines of vehicles with a drive motor, especially in the form of a combustion engine, individually with the specified features; further, a gear control device.
2. Description of the Related Art
The current trend in vehicles toward a greater space offering, more comfort, a better acceleration and deceleration behavior, for reasons of safety in all traveling condition, as well as the increasing importance of environmental protection aspects, means more demand on the design of drivelines in combustion engine vehicles, an improvement of the energy conversion, from the energy chemically bound in the fuel to the mechanical drive energy required on the vehicle wheels. Besides the improvement of the individual components, the main emphasis there lies on achieving possibilities of fuel saving by optimizing of the driveline by appraisal of the total system, especially of the cooperation between the individual motor and gear components. This demands an optimal adaptation of the gear transmission to the characteristics of the combustion engine, also called motor characteristics, in order to ensure in all traveling conditions and operation of the vehicle a correspondingly favorable fuel consumption value and optimal driving properties. It is well known that the driving performance, the fuel consumption as well as the useful life of the driveline can be considerably influenced by corresponding switching programs of automatic gears. From the state of the art a large number of different switching programs are known which can do justice to the most diverse requirements. The aim there is to achieve a limitation of the working range of the combustion engine to the economical operating points. In the simplest case this is possible by the stipulation of pedal-position dependent fixed switching speeds. There hitherto for reasons of simplicity there was used as switching speed the output turning rate of the gear, which can be assigned in each gear to a certain motor turning rate and which is proportional to the traveling speed. If there the upper limit speed is exceeded, a switching up is performed; if the lower limit speed is fallen below, a switching downward is performed. In traveling operation it is steadily checked whether for the actually traveled condition in actual operation the switching speed is reached or exceeded. If this condition is fulfilled the switching operation is performed. Since during a switching process to be performed, however, also power is transferred, so that there is present the possibility of a further acceleration of the vehicle during the gear change, the motor speed that sets in after the switching process will very much depend on what acceleration has arisen during the switching operation. Thus, it is possible that with an empty vehicle a great acceleration occurs and the motor speed after the switching, therefore, is comparatively high, while with a loaded vehicle a low acceleration occurs and the motor speed therefore is comparatively low. In the first case, with an empty vehicle, because of the necessarily high rate of rotation after the switching, a use disadvantage will occur, while with a loaded vehicle only is the after-the-switching use-optimal. For the avoidance of this disadvantageous effect, therefore, switching programs were developed in which the switching speeds are dependent not only on the load stages, but additionally on the longitudinal acceleration of the vehicle. Such a switching process is described, for example in the publication DE 195 16948 A1. In the process disclosed in this publication the switching-over occurs in dependence on acceleration. Thus depending on the requirements or traveling resistance, switching is done at lower or at higher off-drive or motor speeds, according to whether there is to be preferred a low fuel consumption or a sufficient acceleration. For the switching itself the acceleration of the vehicle or its deceleration is determinative. There, the two following limits—traveling states or accelerations—are always taken into account:
1. low vehicle load on flat or precipitous terrain=high vehicle acceleration and
2. high vehicle load on rising terrain=low vehicle acceleration.
In the first-mentioned case there is yielded then a high vehicle acceleration at low off-drive speeds. A switching-up of the gears, therefore, can occur early already, at a relatively low motor speed, which leads to a lowering of the fuel consumption. For the same reason also the switching-back of the gears occurs with less deceleration at a low motor speed. In the second case a greater motor performance is required, for which reason the switching-up occurs only at a relatively high off-drive speed that corresponds to a high motor speed. In dependence on the measured vehicle acceleration or deceleration the switching-up or switching-down of the gears occurs smoothly between these two traveling states, i.e., within a switching speed range. The switching speed range itself, furthermore, is dependent on the load conditions: with heavier loads, therefore, the switching takes also place at a higher speed.
With this switching program it is achieved that high accelerations lead to a switching-up at lower traveling speeds; the operating point of the motor, i.e., of the combustion engine, is therefore shifted early into a use-favorable range. Simultaneously, through the lower rate of rotation that follows the switching-up, the available motor performance is less. The two effects together lead to a reduction of the fuel consumption. The motor performance thereby limited at high accelerations is there only a desired side effect, which protects the passengers from inadmissible acceleration with empty vehicle. Also in the case of Kick-Down the maximally available power is always attainable, since an upshift does not occur until the regulating speed has been reached.
The designing of such an acceleration-dependent switching program occurs by means of standardized travel maneuvers in the computer. The necessary data on the admissible connection speeds and on the upper limit speeds are obtained there from the motor characteristic diagram. As further parameters there are needed the data of the driveline (converter characteristic curves, axial translation, etc.) and the vehicle data (mass, travel resistances). As the result of the design there is obtained a data set for the switching program, which in the normal case is then deposited in the control of the gear and with which the desired connection speeds are to be achieved without the occurrence of any gear oscillations. An essential disadvantage lies in that the optimal functioning of such an acceleration-dependent switching program requires the individual attuning to the circumstances of the particular driveline, i.e., for example, the axial translation, the existing tire dimension, the type of converter used, etc., from which there results a multiplicity of switching program variants that are expensive to develop and to govern. Also the delivery of the gear often cannot occur with an optimal switching program, whereby complaints and supplementary work are preprogrammed. The frequency of the arising of this type of problems will certainly increase in the future, since the vehicle manufacturer himself as a rule still is ignorant at all the vehicle data for the gear and, in the extreme case, even orders individual gear components separately. A further substantial disadvantage of such a switching program lies in the arising of clear scatterings of the connection speeds, especially in gears with converter operation and especially when the progression ratio is very high.
Underlying the invention, therefore, is the problem of further developing a process for the control of an automatic gear for use in drivelines of vehicles with a combustion engine and preferably an integrated CAN-Bus in such manner that the disadvantages mentioned are av
Depping Herbert
Dietzel Bernd
Haeckh Jakob
Körner Tillman
Trübswasser Franz
Baker & Daniels
Voith Turbo GmbH & Co. KG
Zanelli Michael J.
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