US 4,275,546 AGranted

Stone discriminator

AssigneeSperry Corporation

InventorsCarl E. Bohman, Peter G. Mitchell

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Abstract

An illustrative embodiment of the invention provides an acoustic sensor for detecting stones and other hard foreign objects mixed within crop material in a harvesting machine susceptible to damage thereby. The acoustic sensor comprises a sensing surface disposed within an input path in the harvesting machine for impacting engagement with the flow of crop material therein and an acoustic sensing device coupled to the sensing surface for detecting acoustic vibrations induced within the sensing surface as a result of impact therewith by stones and other foreign objects mixed within the crop material. The sensor provides electrical signals in response to the acoustic vibrations indicative of the impact of the crop material and the foreign objects with the sensing surface and includes isolation means for obviating the effects of extraneous acoustical signals of the same character as the foreign object impacting signals to accentuate the foreign object impacting signals and thereby reduce the false alarm signals.

Claims13

Dependent claims

In a harvesting machine susceptible to damage by a non-frangible foreign object included within crop material harvested from a field and fed into the harvesting machine along a predetermined path via a crop elevator, protective apparatus for providing a signal indicative of the presence of the non-frangible foreign object at a predetermined location along the predetermined path, comprising:

at least one sensing surface for traversing the flow of crop material in said crop elevator and for receiving impactions of crop material and foreign objects;
means for mounting at least one sensing surface in operative relationship to said crop elevator and including means for vibrationally isolating said sensing surface from said combine harvester;
piezoelectric transducer means attached to at least one sensing surface for providing output signals representative of the impactions of the foreign objects and the crop material;
means coupled to said piezoelectric transducer means for selecting said foreign object impact signal from other signals coupled thereto;
and
means coupled to said selection means responsive to said foreign object impact signal for generating a utilization signal useful for indicating the presence of said foreign object.

3 more elements

Dependencies are inferred from the claim text.