Measuring and testing – Volume or rate of flow – Thermal type
Reexamination Certificate
1999-06-29
2001-12-04
Raevis, Robert (Department: 2855)
Measuring and testing
Volume or rate of flow
Thermal type
Reexamination Certificate
active
06324905
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for measuring the angle of a first rotatable body which coacts with two further rotatable bodies, the angle of the two further bodies being measured and the angle of the first body being determined therefrom.
BACKGROUND INFORMATION
A conventional method and apparatus are described in German Patent Application No. 195 06 938, in which a first gear which is equipped with a number of teeth and is rotatably through more than 360° is provided as the first rotatable body. The two further rotatable bodies are also gears, which are in engagement with the first gear and whose numbers of teeth is less than the number for the first gear. In addition, the numbers of teeth of the two further bodies differ, for example, by one tooth.
Associated with each of the two further bodies is a sensor with which the angle of the body can be measured absolutely, i.e. even when the body is stationary. The angle of the first body can be determined from the measured angles of the two further bodies.
The accuracy of the angle determined for the first body can be influenced by an appropriate selection of the number of teeth of the first body and of the two further bodies. It has been found, however, that even after optimization in this regard, the angle determined for the first body still exhibits inaccuracies.
SUMMARY OF THE INVENTION
Proceeding therefrom, it is the object of the present invention to develop a method and an apparatus of the kind cited initially in such a way that exact determination of the angle of the first rotatable body is possible.
This object is achieved according to the present invention in that the angle of the two further bodies is measured simultaneously.
Simultaneous measurement ensures that even when the angles of the two further bodies are measured during rotation of the bodies, an exact determination of the angle of the first body is possible. If the angles of the two further bodies were not measured simultaneously, the result, especially in the event of rotation of the bodies, could be that the body measured later would already have rotated further by a slight “delta.” This delta is in itself very small, but can nevertheless means that the requisite accuracy can no longer be obtained in the subsequent determination of the angle of the first body. This is reliably avoided by simultaneous measurement of the angles of the two further bodies. Measurement of the angles of the two further bodies is thus synchronized, with the substantial advantage that the accuracy of the determination of the angle of the first body is thereby improved.
Because of the synchronization, the angles of the two other bodies are measured at a single sampling time, i.e. simultaneously. Synchronization and definition of the single sampling time, and thus simultaneous measurement, are achieved with the aid of a signal with which measurement of the two angles is started.
In one embodiment of the present invention, the measured angles of the two further bodies are stored. The result of this is that determination of the angle of the first rotatable body is independent of measurement of the angles of the two further bodies. It is thus unnecessary to process the measured angles of the two further bodies immediately; rather it is possible, because the measured angles are stored, to process these measured angles regardless of the time at which measurement occurred.
It is also advantageous if each of the two further bodies is equipped with a magnet, associated with which is an AMR sensor that is provided for measuring the angle of the associated further body; and if an analysis circuit is provided which is coupled to the two AMR sensors and is provided for analyzing and optionally for transforming the measured angles of the two further bodies. The AMR sensors are suitable for making an absolute measurement of the angles of the two further bodies. The angles can thus be measures with no need to impart any rotation to the two bodies. The analysis circuit associated with the two AMR sensors is provided in order to process the measured angles further in a first step. In particular, it is possible for the analysis circuit to transform the measured angles, for example, into pulse-length modulated signals or other digital signals.
In another embodiment of the present invention, the analysis circuit is equipped with an arrangement, in particular with sample-and-hold elements, for storing the measured angles of the two further bodies. The above-described decoupling of the measurement of the angles of the two further bodies from the determination of the angle of the first body is thereby accomplished in simple manner.
It is particularly useful if a calculation device, in particular a programmable microprocessor, is provided for determining the angle of the first body. This makes it possible, in a simple manner, to adapt the determination of the angle of the first body, for example, to the geometry of the two further bodies. All that is necessary in this context is to modify the corresponding values in the program of the microprocessor.
In another embodiment of the present invention, the calculation device can generate a start signal with which simultaneous measurement of the angles of the two further bodies by the two AMR sensors can be triggered. The calculation device is thus responsible for the simultaneous measurement of the angles of the two further bodies. The calculation device triggers this simultaneous measurement by generating a single start signal which brings about measurements at both AMR sensors. This represents a reliable but nevertheless very simple possibility for achieving simultaneous measurement of the angles of the two further bodies.
The result of this common start signal is that the angles of the two further bodies are measured at a single sampling time, i.e. simultaneously. The single sampling time is defined by the start signal.
In another embodiment of the present invention, a line is provided with which the calculation device is connected to the analysis circuit, and on which the start signal can be delivered to the analysis circuit. The analysis circuit is acted upon by the start signal by way of this line.
Further features, potential applications, and advantages of the present invention are evident from the description below and from exemplary embodiments of the present invention which are depicted in the drawings. In this context, all features described or depicted constitute, of themselves or in any combination, the subject matter of the present invention.
REFERENCES:
patent: 5065095 (1991-11-01), Suzuki
patent: 5825178 (1998-10-01), Hipp et al.
patent: 195 06 938 (1996-08-01), None
patent: 196 01 657 (1997-07-01), None
Fuhrmann Horst
Noltemeyer Ralf
Kenyon & Kenyon
Raevis Robert
Robert & Bosch GmbH
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