Interrelated power delivery controls – including engine control – Transmission control – Continuously variable friction transmission
Reexamination Certificate
1999-07-09
2001-04-17
Estremsky, Sherry (Department: 3681)
Interrelated power delivery controls, including engine control
Transmission control
Continuously variable friction transmission
Reexamination Certificate
active
06217478
ABSTRACT:
This invention concerns a method for control of a positioning and/or angle device without an absolute positioning sensor, but with at least one position index for a controllable part in a motor vehicle using an electronic circuit and the device itself.
BACKGROUND OF THE INVENTION
Positioning and/or angle control devices have many uses in the motor vehicle technique, e.g. as adjusting devices for clutches, for the control of oil flows, as set value sensors for actuators in steering systems, for an adjustment of active shock absorbers and for control of the adjustment of the speed ratio of transmissions such as continuously variable toroidal drives or continuously variable transmissions (CVT transmissions).
As positioning and/or angle control devices units are often used which does not make possible a detection or feedback of the absolute position, e.g. in stepping motors. But since this absolute position becomes necessary for the use of control and regulation strategies, there have been already used among others the following possibilities:
a) external, separate measurement or detection of the absolute position;
b) continuous incremental detection occasionally, regularly, or at specific moments (e.g. initializing) of the absolute position in certain prominent positions (stops, additional/missing transmission detection among others);
c) continuous incremental detection by taking into account the position departing from the set nominal value and detection of the absolute position like in b);
d) determination from other detected system factors; this is possible only when a clear, sufficiently precise relationship exists;
e) a combination of the above methods.
For stepping motors a method according to c) is generally used (see also the publication of the firm Motorola Inc., 1990 “TPU Time Processor Unit Reference Manual”, chapter 3, page 103). In this initializing method described therein for a stepping motor, the latter is transferred from its momentary position to a preset basic position corresponding to a firm stop.
Especially in the motor vehicle technology it must be ensured that the divergences of the calculated from the real position (called “step errors” in stepping motors), which appear during the operation between the moments of the absolute position detection do not exceed an admissible measure. Such step errors can result, e.g. from the fact that due to vibrations high counterforces result which cannot be overcome by the electromotive force of the stepping motor associated therewith is important, since thereon directly depends the accurate control of the part, e.g. the adjustment of the reduction ratio of a continuously variable transmission in a motor vehicle. Incorrect adjustments of the speed ratio can result in too high or too low numbers of revolutions of the motor and therewith comfort impairment and also elevated fuel consumption. Besides, no adjusting power should act during stoppage on the continuously variable toroidal drive, since this can lead to mechanical damage.
SUMMARY OF THE INVENTION
Therefore, the problem to be solved by this invention is to provide a method for control of a positioning and/or angle adjustment device and the device itself with which an accurate adjustment of the absolute position of the positioning and/or angle control device is ensured in order thus to make possible an exact control of the part associated with the positioning and/or angle control device. But this must, as far as possible, be effected without damage to the service needs such as result from waiting periods while balancing the absolute position and taking into account special requirements in the motor vehicle.
This problem is solved by a method and a positioning and/or angle control device according to the invention.
Therefore, according to the invention, the method for control of a positioning and/or angle control device without an absolute position sensor consists in that the positioning and/or angle control device is initialized after termination of the operation of the motor vehicle. Thereby is advantageously obtained a detection or feedback to the electronic circuit concerning the absolute position. It is thus ensured, particularly in motor vehicle technology, that the divergences appearing during the calculation operation of the actual position between the moments of the absolute positioning detection do not exceed an admissible measure. In addition, there is obtained in this manner an exact adjustment of the absolute position of the positioning and/or angle control device without damage to the service needs such as waiting periods while balancing the absolute position.
In a preferred embodiment of the invention, it is proposed that the positioning and/or angle control device be advantageously a stepping motor designed for a controllable part such as a toroidal drive in a motor vehicle.
As mentioned at the beginning, such a method, the same as the positioning and/or angle control device, are adequate in multiple fields of use, but especially in motor vehicle technology. A preferred embodiment of such a method for control of a positioning and/or angle control device according to the invention is described herebelow in relation to the adjustment of the speed ratio of a continuously variable toroidal drive wherein positioning control device is provided as one having a stepping motor combined with a set value sensor.
Continuously variable toroidal drives with input and output discs situated coaxially relative to a common shaft and having toroidally designed inner surfaces wherein between the input and output discs, arranged in pairs, friction wheels are situated which can be actuated, via a hydraulically actuatable swiveling device, so that the reduction ratio can be continuously variable adjustable as has been described in the application DE 197 32 084.8.
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TPU Reference Manual,Time Processor Unit, Motorola 3-100, 4 pp.
Zykla, Wolfram: “Positionieren mit Schrittmotoren”. In: elektrische ausrüstung, Nr. 4, Aug. 1976, S. 18-021.
Bauer Gunther
Dreibholz Ralf
Vohmann Martin
Davis & Bujold P.L.L.C.
Estremsky Sherry
ZF Friedrichshafen AG
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