Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle diagnosis or maintenance indication
Reexamination Certificate
2002-11-05
2004-11-16
Zanelli, Michael J. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle diagnosis or maintenance indication
C701S062000, C477S906000
Reexamination Certificate
active
06819987
ABSTRACT:
BACKGROUND
0
F THE INVENTION
The invention relates to a method for early recognition of abnormal occurrences in the operation of automatic or automated transmissions with shift elements being active in a non-positive fit.
Automatic transmissions, especially automatic transmissions in vehicles, and automated transmissions are known in a multitude of embodiments. They are available as purely mechanical transmissions, a combination of at least one mechanical transmission component and a hydraulic transmission component, or a mechanical transmission component and an electric transmission component, or a variable mechanical transmission. The hydraulic transmission component can comprise either a hydrostatic transmission component or a hydrodynamic component. If a transmission has at least two different transmission components, they are either connected in series or they operate with torque division. Such transmissions where a mechanical component is combined with a hydraulic component are described, for example, by J. M. Voith GmbH in “Hydrodynamics in Motive Power Engineering”, Krauskopf Verlag, 1987.
In most automatic and automated transmissions, the elements for changing the traveling conditions or the operating range utilized by the drive unit are controlled by electro-hydraulics. The desired traveling condition is pre-selected or changed by means of a control element in the form of a gearshift lever or a push-button switch. The physical values characterizing such operation then generate respective electrical signals that trigger control valves, which in turn actuate individual shift elements so as to realize a non-positive engagement or disengagement.
In fully automatic transmissions, the gears are changed automatically via a hydraulic or electro-hydraulic control system in dependence of the strain on the engine and the speed of the vehicle. The gears are changed with the aid of brake bands, multiple clutches or multiple disc brake systems under load. The primarily used shifting elements are hydraulically operated friction elements, preferably in the form of multiple disc clutches, flexible disc clutches and/or brakes whose function is to establish or interrupt the flux of force in the transmission in accordance with the selected gear.
Abnormal shift actions and conspicuous noise in the transmission are signs of abnormal occurrences in the transmission unit. It is known in the art to detect the cause of abnormal gear shifting by testing the modulator, controller and working pressures. The transmission is then provided with the required test connections where the test equipment with various measuring ranges can be connected. The modulator and working pressures can be tested while the vehicle is standing still with the engine running, but the controller pressure has to be tested while the vehicle is moving or on a roller test stand. However, most of the time, a diagnosis is not made until abnormal shift actions have occurred to a considerable degree, and specifically, until conspicuous noise in the transmission already caused higher wear on the friction elements to be coupled to each other in a non-positive fit. Therefore, the indicators for investigating abnormal shift occurrences are abnormal occurrences in the operation of an automatic transmission caused by damage. Usually, corrective action then involves the replacement of components.
Therefore, a method for early recognition of abnormal occurrences is known from DE 196 52 212 A1, especially early recognition of damage, using suitable indicators by means of which changes in the transmission, changes in the air-oil supply and in the components pertaining to the transmission control are detected early, as follows:
While the automatic transmission is in operation, a current actual value of at least one variable at least indirectly characterizing a shift action is determined in each shift. Said actual value is compared with at least one reference value for similar shift actions. If they deviate, the manipulated variable for actuating the elements of a shifting element to be brought into working connection in a non-positive fit is changed so as to at least indirectly influence the variable characterizing the shift action. At least one threshold value can be set for the actual value of a variable at least indirectly characterizing the shift action and/or at least one threshold value can be set for a variable at least indirectly characterizing the changing behavior of the actual value via a plurality of successively completed similar shift actions, i.e. from a first original gear to a following second target gear. The threshold values are associated with criteria characterizing an acceptable behavior of the actual value compared to the threshold value. If the threshold value deviates from the actual value such that said criteria are no longer met, an error message or an error signal is generated. The criteria for comparing the actual values or the changing behavior of the actual value with the threshold value or threshold values signify that the threshold value or threshold values are intended to cover a certain actual value range, within which the transmission is not damaged by operation. A substantial disadvantage of such a method is that the reference and actual values are adjusted via an adaptive control or regulation strategy. In this case, an abnormal occurrence or a potential subsequent abnormal occurrence can only be deduced indirectly in that the desired result is not achieved via adaptation. Therefore, said method can be used only for transmissions with adaptive gear shifting. Other transmission units which are based on other shifting systems characterizing the method of operation cannot be monitored with such methods.
SUMMARY OF THE INVENTION
Therefore, the aim of the invention is to develop a method for early recognition of interfering factors in the operation of an automatic or automated transmission which allows that damage and functional failure caused especially by manufacturing or assembly errors and by increasing wear, among other factors, are detected early, irrespective of the shift program, which means before any damage occurs which highly affects the function and may lead to a complete breakdown, and thus preventing more significant damage to the transmission. The method should be useable irrespective of the shift program at the same cost for any type of transmission unit, for both automatic and automated transmissions.
In accordance with the invention, during a shift action, especially shifting up, down or braking, a value at least indirectly characterizing the strain on the elements to be coupled to each other in a non-positive fit is determined continuously and added up in the form of a variable. In the easiest case, such value at least indirectly characterizing the strain on the elements to be coupled to each other in a non-positive fit is the friction work. It is determined by mathematically combining the difference between the respective current speed on the drive side, especially the transmission input shaft or the drive unit coupled with said shaft and the synchronizing speed of the following gear, also called target gear, and the pressure acting on the shifting element, especially the friction surfaces of the shifting elements to be brought into active connection. Synchronous speed of the following gear means the speed at the input of the gears, i.e. on the power take-off of the hydrodynamic component or the bridging coupling. The result is added up in the form of a variable where additional influencing factors, such as the current readjusting spring power and the centrifugal force are also included.
Before a shift, said variable is always reset to zero. The computation begins as soon as the current speed deviates from the synchronous speed of the last gear to be exited, i.e. the original gear, when the target gear is put in, or when a predefined time period has elapsed since the outgoing gear shift element has been disengaged or since the shift began. Said value is relevant, especially in a case w
Depping Herbert
Dietzel Bernd
Schönharr Thomas
Baker & Daniels
Voith Turbo GmbH & Co. KG
Zanelli Michael J.
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