Viscosity measurement by means of damped resonant vibration normal to an approximate rigid plate
OwnerHubert Arthur Wrightinventor
Life of this patent
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Abstract
A brief but intense magnetic impulse generated by a coil 42 is used to excite resonant bending mode vibration in a magnetically permeable cantilevered beam 2 immersed in a fluid 22. A permanent magnet 36 and a magnetically permeable circuit 44, 38, 40, 56, 32, 6, and 2 enhance the magnetic coupling between the flexible beam 2 and the coil 42. A rigid post 6, positioned close to the beam and normal to the plane of oscillation is used to substantially increase the shearing induced in the fluid and thereby the rate of viscous attenuation of the vibrating beam. Oscillation of the vibrating beam 2 is detected by the same coil 42 that initiated the vibrations. The rate of decay of the vibrations is related to absolute viscosity.
Claims14
A viscosity sensing device consisting of:
- a flexible beam immersed in a fluid,
- impulsive means to initiate resonant oscillation of the beam,
- a rigid surface oriented perpendicular to the direction of oscillation of the beam in close proximity to at least a portion of the beam positioned and spaced so as to substantially affect the viscous attenuation of the beam vibration,
- circuitry to determine the resultant rate of decay of the beam oscillations,
- computational means to relate the rate of oscillation decay to viscosity,
- and output devices to enable access to the computed result.
A viscometer consisting of:
- a magnetically permeable and flexible beam supported near the face of the device,
- a permanent magnet mounted on the beam facing the device,
- means to immerse the face of the device in a fluid,
- a coil within the device magnetically coupled to the flexible beam and magnet,
- excitation circuitry which periodically forces a brief burst of current in the coil creating an impulsive magnetic force on the beam and magnet, inducing natural oscillations, the duration of the excitation being approximately one-half the period of the natural oscillation,
- a rigid surface oriented perpendicular to the direction of oscillation of the beam in close proximity to at least a portion of the beam positioned and spaced so as to substantially affect the viscous attenuation of the beam vibration,
- circuitry to detect the electromotive force induced in the coil as a result of oscillation of the beam and magnet, including amplification and frequency selective filtering,
- computational means for measuring the rate of decay of the beam oscillations and relating the rate of decay to viscosity
- and circuitry to output the computed viscosity in a useful format.
Dependencies are inferred from the claim text.