Measuring and testing – Dynamometers – Responsive to torque
Patent
1990-12-28
1993-08-24
Razavi, Michael T.
Measuring and testing
Dynamometers
Responsive to torque
73862321, G01L 302
Patent
active
052378802
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a measuring device comprising a torsion element including a radially extending bending rod. Such a known measuring device comprises two bodies of electrically conductive, non-magnetic material which are arranged coaxially relative to a shaft, are connected to the shaft for joint rotation therewith, and are rotatable relative to one another. Further, a coil is provided which is coaxial to the shaft. High-frequency alternating current flows through the coil, which is arranged in the immediate vicinity of the two bodies. The latter comprises cut-out portions whose reciprocal overlapping surface changes as the angle of rotation between the bodies increases, wherein the relative rotation of the two bodies can be determined for the purpose of measuring the change in impedance in the coil occurring as a result of the eddy currents induced in the bodies. A torsion rod is arranged in the axial direction of the shaft in order to produce this relative rotation, so that the measuring device has a relatively long construction (U.S. Pat. No. 4,356,732).
SUMMARY OF THE INVENTION
The object of the invention is measuring device, that has a relatively short construction and can be used under cramped installation conditions.
The object of the invention is achieved by providing first and second sleeve-shaped bodies secured at an end of the bending rod remote from an axis of the rotating machine part, in spaced relationship to each other, with each of the first and second sleeve-shaped bodies having a plurality of slots equidistantly spaced from one another and offset circumferentially relative to the slots of another of the first and second sleeve-shaped bodies, a third sleeve-shaped body having a plurality of equidistantly spaced slots and arranged between the first and second sleeve-shaped bodies, and at least one coil assigned to each of the first and second sleeve-shaped bodies. The coils are concentric relative to each other. Impedance of the coils changes in accordance with a relative position of the slots of the first, second and third sleeve-shaped bodies which relative position is a function of rod bending. Axial changes in spacing between the measurement coils and the measurement sleeves can be compensated for as a result of the sleeve-shaped measuring element, which comprises longitudinal slots formed in the axial direction of the shaft, and the arrangement of the coils on the outside and inside at the same vertical height. It is possible to determine the driving and driven torque in an accurate member with a relatively simple and compact construction.
The present invention both as to its construction so to its method of operation, together with additional objects and advantages thereof, will be best understood from the following detailed description of preferred embodiments when read with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a longitudinal cross sectional view of a torque sensor according to the invention;
FIG. 2 shows a side view in direction of arrow II of FIG. 1;
FIG. 3 shows a partial cross-sectional view of a sensor shown in FIG. 1; and
FIG. 4 shows a partial view of the sensor with the torsion element in a basic position and in a twisted state.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In FIG. 1, a shaft which comprises at its end a flange constructed as a spoke wheel 11 is designated by 10. It has an outer rim 13 in which a plurality of continuous holes 15 are formed at a distance from one another of approximately 90.degree.; e.g. an electric motor, not shown, can be flanged on via the holes 15. A driving torque can accordingly be introduced on the rim 13. The spokes 16 of the spoke wheel 11 are securely connected with the hub 17 and the rim 13 and serve as bending rods.
A sleeve 22, which comprises longitudinal slots 23 extending in the longitudinal direction of the sleeve 22, is fastened as far as possible in the area of the rim 13 at the spoke 16 or at the rim 13 itself with a bracket 21. Furthe
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patent: 4135390 (1979-01-01), Templin
patent: 4356732 (1982-11-01), Hachtel et al.
patent: 4448084 (1984-05-01), Dobler et al.
patent: 4592241 (1986-06-01), Obayashi et al.
patent: 4680976 (1987-07-01), Lustenberger
patent: 5027663 (1991-07-01), Frister et al.
patent: 5027663 (1991-07-01), Frister et al.
Dobler Klaus
Hachtel Hansjorg
Razavi Michael T.
Robert & Bosch GmbH
Shopbell Elizabeth L.
Striker Michael J.
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