Measuring and testing – Dynamometers – Responsive to multiple loads or load components
Patent
1994-12-05
1996-04-23
Chilcot, Richard
Measuring and testing
Dynamometers
Responsive to multiple loads or load components
73862191, G01L 516
Patent
active
055093140
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a torque-measuring arrangement of a gear drive for transmitting a rotary movement and the power of which is transmitted via helically toothed spur gears.
Known torque-measuring arrangements comprise a measuring shaft provided in the gear train of a gear drive for the transmission of power. Two transducers measuring the torsion angle of the measuring shaft are assigned to said measuring shaft at a defined axial distance, said torsion angle being proportional to the torque to be measured.
In the DE-OS 28 15 463 A1 and in the patent publications DE 31 12 714 C1, FR 1 596 833 and GB 644 234 two respective measuring gears are mounted on the measuring shaft at the above-mentioned distance; in addition to measuring purposes, said gears may be used for the transmission of power. When passing a sensor, the teeth of the measuring gears initiate electrical pulses the respective torque-dependent phase shifting of which is determined in an evaluation device.
The patent publication DD 257 488 also describes an arrangement operating according to the differential-angle principle, an arrangement in which a respective rotary encoder is connected to each shaft end in order to determine the torsion angle of a drive shaft.
Disadvantageous with these solutions is that the sensors directed onto the teeth of the measuring gears require additional mounting space in radial direction, and that the torque-dependent phase shifting is determined as a function of speed, which increases the efforts in the evaluation device, and that the sensitivity and accuracy of the measuring arrangement depends from the number and the pitch accuracy of the measuring gears or may be improved by means of a measuring shaft being of little torsional stiffness, which is limited by the power to be transmitted and the thus increased tendency to vibrate.
Further known torque-measuring devices operate with force-measuring devices, in particular strain gauges, which are are provided in a measuring bearing or directly in the toothing of the power-transmitting drive gear (DE 25 26 582 C2). Said devices have the disadvantage that the stiffness of such measuring bearings is smaller than that of conventional bearings requiring the same mounting space. Furthermore, the stiffness of the frames receiving the measuring bearings is reduced as a result of the larger mounting space needed for the measuring bearings so that, in general, the integration of measuring bearings brings about disadvantageous changes with respect to the dynamic gearing properties.
SUMMARY OF THE INVENTION
It is the object of the invention to develop a torque-measuring device making it possible to directly measure the torque transmitted in a gear train and ensuring a great degree of stiffness of the bearings and the drive elements.
According to the invention the object is achieved in that in a torque-measuring arrangement for a drive gear having at least three meshing helically toothed spur gear there is at least one distance sensor fixed on the frame and provided on at least one of said gears and directed onto a plane surface of said gear, said distance sensor being connected to an evaluation device.
The invention makes it possible to determine the torque by measuring the deformations of a shaft or a gearwheel. Due to the helical toothing of the spur gears forces acting towards the rotary axis of the measuring gearwheel occur on the circumference of said spur gears, in addition to tangential forces. Said axial forces cause the shaft and the gearwheel to bend. By measuring the bending the evaluation device may determine the torque.
It is advantageous to provide a highly sensitive measuring arrangement with two pairs of distance sensors, each pair of sensors being disposed on a diameter, below the root diameter, in a plane extending perpendicular to the rotary axis of the measuring gearwheel.
Thus, wobbling errors of the measuring gearwheel can be eliminated by in-phase correction of the signals of the pairs of distan
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Patent Abstracts of Japan No. 6150029 (Naoyiki) Mar. 12, 1986.
Patent Abstracts of Japan vol. No. 16193 May 11, 1992.
Application No. JP900133320 (Sanyo) May 22, 1990.
Kipphan Helmut
Uwe Tessmann
Chilcot Richard
Dougherty Elizabeth L.
Greenberg Laurence A.
Heidelberger Druckmaschinen AG
Lerner Herbert L.
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