Measuring and testing – Testing of apparatus
Reexamination Certificate
1998-02-02
2001-02-06
Noland, Thomas P. (Department: 2856)
Measuring and testing
Testing of apparatus
C073S001790, C702S094000, C702S150000
Reexamination Certificate
active
06182518
ABSTRACT:
BACKGROUND AND SUMMARY OF THE INVENTION
This application claims the priority of German patent document 197 03 488.8, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a process for measuring the relative movement of at least two components.
The measuring of the relative movement of components with respect to one another is important wherever these components interact with one another. Operations in which such interactions occur, for example, are engaging operations in clutches, the moving of a tooth of a gear wheel into the tooth space of a second gear wheel, displacements of meshing gearwheels under load, bending of shafts and bodies, and many other operations. Such measurements are carried out in order to more closely examine the course of the observed event.
In this context, very high demands are made on the measuring precision. In addition, the analysis of the measuring value becomes difficult, particularly when the observed components are moved not only with respect to one another but each component is also moved separately. Other components which cannot be measured by measuring techniques also influence the sequence of movements. In brief, the analysis of the measuring values becomes difficult because several parameters influencing the sequence of movements must be analyzed simultaneously.
The measuring of the synchronizing operation when a gear in a synchronized vehicle transmission is engaged, which so far has been difficult, can be used for demonstrating this problem:
A known observation of this operation by visual methods presents problems because the corresponding components move fast and observing them is difficult because of the excess oil.
In a known detection of the rotating movements by corresponding angular momentum generators, because of the rotational speed level as well as the measuring inaccuracies of the rotational speed generators, the actual event of the synchronization which takes place in a range of smaller changes of the detected signals is difficult to identify and analyze.
The moving direction of individual components can briefly change during the contact. Direction change is difficult to reproduce by conventional illustration methods, for example, line recording of the rotational speeds.
As a rule, the contact of components causes a change in the movement direction or a change of their speed. In the case of rotating components, this momentum change is normally detected by measuring techniques as a change of the rotational speed. Without any further analysis, this often brief change of rotational speed provides little information regarding the direction of force, angular change or contact points.
These and other objects and advantages are achieved by the measurement process according to the invention in which, after detecting the series of measuring values, while first taking into account known marginal conditions, at least a portion of the series of measuring values is adjusted by a mutual linking. By using known marginal conditions during the adjustment of the series of measuring values, the precision of the measurement is clearly improved using simple devices and without any additional expenditures with respect to the sensor assembly or the measuring process. As a result of the marginal conditions, the relationship of the measuring value in the range of the marginal conditions is known precisely or nearly so.
Furthermore, by means of a subsequent standardization of the series of measuring values, as required, the reference system, that is, the location of the observer of the measurement is freely selectable so that it is possible to observe the event from a particularly suitable reference system. The common representation of the series of measuring values precisely defines the relative movement of the components to be observed so that, on the whole, an analysis of the measurement is possible. This improves the precision and its ability to be analyzed.
An example of an adjustment while taking into account suitable marginal conditions is the following: If, during a measurement, two components, in this case, two gear wheels, move at precisely the same speed because they mesh with one another without slip, as a rule, a different rotating speed of a few rotations per minute is sensed as the measured quantity. This rotational speed difference, which differs from the actual value, has its causes in the measuring precision of the measuring chain of both components which is finitely limited and is within a permissible tolerance (see also FIG.
3
). The speed difference, which is determined for reasons of a measuring inaccuracy, is computed as an “offset” from the mathematical difference of both signals and is added to the numerical values of the measured speed of at least one of the two components. Only a time range may be used for the speed adjustment in which the above-mentioned marginal conditions (speed equality) are valid. This ensures that the numerical values of both speeds, on the average, exhibit no relative deviations. The speed offset can be determined very precisely when one copy of the measuring series is smoothed by means of a digital (e.g., Butterworth) low-pass frequency of approximately 5% of the used sensing frequency and the difference is formed from the smoothed signals. The speed adjustment is permissible only if the measuring chains of the measured components are within the tolerance of a required measuring accuracy and within the measuring range valid for the respective measuring chain (outside an unacceptable limit range). In addition, it must be ensured that the measuring value sensing system has no aliasing effects or other systematic disturbances.
It is suggested to first calculate a position of the components from the series of measuring values. For this purpose, the pertaining movement or rotations are normally computed from the numerical values of the measured speeds or rotational speeds by means of a time-related integration. From the numerical values of the measured accelerations, the pertaining movement or rotations are calculated by a double time-related integration. In the case of each of these integrations, an integration constant will occur which is determined by the marginal conditions and is fixed to suitable values. This results in a positional adjustment of the components. The following is a corresponding example: By means of the present invention, the angle of rotation of mutually meshing components can be determined (for example, in the case of synchronous couplings), from the integration of the rotational speeds. The integration constants will be determined such that, at a selected point in time, where the components mesh with one another, the angle of rotation of the first components is 0° and the angle of rotation of the second component amounts to the matching angular pitch. Thus, a penetration of the bodies is impossible. The position of both components is therefore determined.
If, as suggested, the marginal conditions for adjusting the series of measuring values are selected such that these marginal conditions are within the range of an event to be observed, that is, are valid in this range, the precision is increased exactly where the key point of the observation is situated. All conditions may be used as marginal conditions which increase the analysis and measuring precision.
To standardize the measuring values, it is suggested to use one of the series of measuring values. In this approach, the observer's location is identical with that component whose measuring values, such as its rotational movement, were used for the standardizing.
As an alternative, it is suggested to use a fixed value for the standardizing. In this approach, the observer takes up an apparently fixed location. It would be particularly advantageous if, in addition, this fixed value were to be selected from one of the series of measuring values. The reason is that the location of the observer would correspond to the position or movement of an observed component at a fixed point in tim
Dr. Ing. h.c.F. Porsche AG
Evenson, McKeown, Edwards & Lenahan P.L.L.C.
Noland Thomas P.
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