Measuring and testing – Dynamometers – Responsive to torque
Patent
1997-03-26
1999-06-29
Patel, Harshad
Measuring and testing
Dynamometers
Responsive to torque
G01L 302
Patent
active
059182865
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention describes a new apparatus and method for measuring the angle of torsion on loaded rotating shafts. When the angle is known, it is possible to calculate the torque and the power as the RPM also will be known or measured.
2. Description of the Related Art
The most used method for measuring the power on rotating shafts used in various types of machinery has until now been done by the use of strain gauges glued to the shaft. The signals measured by the strain gauges have been transferred to the instrument electronics and the display by means of sliprings or telemetri. When telemetri is used, it is necessary to have a transmitter mounted on the rotating shaft and powered by a rotating battery, or in newer systems, wireless transfer of power to the strain gauge electronics on the shaft.
A later system uses so-called magnetic hall effect sensors. The sensors pick up signals by means of two gear wheels which are placed on the shaft in an adequate distance from each other. When the shaft is loaded there will be a time delay between the pulses detected by the two hall effect sensors, each of which is sensing on a gear wheel. The time delay between the pulses determine the torsional angle of the loaded shaft. A similar system to this is described in the publication "Antriebstechnik" 33 (1994) No. 8 page 53: "Entwicklung eines robusten beruhrongslosen Drehzahl-Drehmoment-Messystems."
U.S. Pat. No. 4,520,681 is a system which uses a pulse train principle with rotating coders in an adequate internal distance from each other and mounted to the shaft. The torsional angle is measured by means of the time delay between electronic pulses. Two sensors are mounted in an adequate distance from each other, one sensor at each rotating coder. The same time delay between the pulses from the said sensors is measured in electronic counting circuits. In U.S. Pat. No. 4,520,681 either optical or magnetic sensors are used. This system uses similar or identical principles to the system as described at page 53 in the publication "Antriebstechnik" 33 (1994) No. 8.
The above-mentioned systems have the common principle of operation that they will have to use two electronic sensors to make it possible to detect the torsional angle of a loaded shaft.
SUMMARY OF THE INVENTION
To achieve a sufficient accuracy in systems using two sensors placed at a distance from each other, it is necessary that the trigger points of the sensors do not drift from each other. Aging and/or temperature variations may cause the trigger points to drift from each other and possibly in opposite directions.
The invention described herein uses only one single sensor system to measure the torsional angle of a rotating loaded shaft. This eliminates that the measured time delay between the sensed pulses can drift and thus causing inaccuracies to occur. This invention presents itself as a new system which has a high degree of accuracy and longtime stability.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective drawing of the system shown in accordance with the preferred embodiment of the invention having a single light source transmitter and receiver.
FIG. 2 shows the apparatus of FIG. 1, with an additional receiver, fiber optic cable, and transmitter interposed between the light source transmitter and receiver of FIG. 1.
FIGS. 3A and 3B essentially show the apparatus of FIG. 2, with the light being interrupted by discs. FIG. 3B shows the apparatus having the light beam split in two parallel paths.
FIGS. 4 and 5 are illustrations of light pulses after having passed through the various vane and discs shown in the previous figures.
FIG. 6 shows an implementation of the invention in an overall system.
FIG. 7 is illustrative examples of discs used in the systems of FIGS. 3A, 3B and 6, and the respective pulses that are generated.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
FIG. 1 shows the apparatus with one light source as the transmitter and a light sensitive electronic sensor as receiver. Th
REFERENCES:
patent: 3888116 (1975-06-01), Spinella
patent: 3938890 (1976-02-01), Flavell
patent: 4520681 (1985-06-01), Moore et al.
patent: 4637264 (1987-01-01), Takahashi et al.
patent: 4693123 (1987-09-01), Bacardit
patent: 4953411 (1990-09-01), Coenen et al.
patent: 5374821 (1994-12-01), Muhs et al.
patent: 5490430 (1996-02-01), Anderson et al.
Antriebstechnick, 33 (1994) No. 8, "Entwicklung eines robusten beruhrungslosen . . . ", pp. 53-57.
Smith Frantz Karsten
Storesund Marvin Sigmund
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