Apparatus for measuring a force
First Claim
1. Apparatus for measuring a static force, comprising, a pair of beams arranged in parallel, means connecting adjacent ends of said beams providing two nodes at opposite ends of said beams, means for receiving a static force at one end of said pair of beams for loading said beams in an axial direction, vibrator means having relatively moveable parts connected respectively to said beams for applying equal and opposite oscillating forces transversely to said beams, frequency sensor means connected to at least one of said beams for detecting the frequency thereof and generating a resultant output signal, exciter circuit means having an input connected to said frequency sensor means and an output connected to said vibrator means for generating a fundamental signal for exciting said beams at a resonant frequency f in response to the fundamental frequency sensed by said sensor means, said exciter circuit means having means for generating a harmonic signal and superimposing it on said fundamental signal for also exciting said beams at a harmonic frequency, means responsive to said fundamental and harmonic signals for determining the magnitude S of said static force in accordance with the equation
wherein C0 and C1 are temperature dependent correction factors having values which depend on the properties of said beams.
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Accused Products
Abstract
The invention relates to an apparatus for measuring a force wherein the force to be measured is applied to a beam in an axial direction. Oscillating forces applied transversely to the beam sets the beam in its resonant state and the resulting resonant frequency is an indication of the magnitude of the force.
14 Citations
11 Claims
- 1. Apparatus for measuring a static force, comprising, a pair of beams arranged in parallel, means connecting adjacent ends of said beams providing two nodes at opposite ends of said beams, means for receiving a static force at one end of said pair of beams for loading said beams in an axial direction, vibrator means having relatively moveable parts connected respectively to said beams for applying equal and opposite oscillating forces transversely to said beams, frequency sensor means connected to at least one of said beams for detecting the frequency thereof and generating a resultant output signal, exciter circuit means having an input connected to said frequency sensor means and an output connected to said vibrator means for generating a fundamental signal for exciting said beams at a resonant frequency f in response to the fundamental frequency sensed by said sensor means, said exciter circuit means having means for generating a harmonic signal and superimposing it on said fundamental signal for also exciting said beams at a harmonic frequency, means responsive to said fundamental and harmonic signals for determining the magnitude S of said static force in accordance with the equation
- space="preserve" listing-type="equation">S=(f.sub.2 -C.sub.0)/C.sub.1
wherein C0 and C1 are temperature dependent correction factors having values which depend on the properties of said beams. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
Specification