Apparatus and method for detection of icing onset and ice thickness

Claim 1

Apparatus for detection of icing onset and ice accretion employing ultrasonic pulse-echo techniques, said apparatus including an ice-accreting surface and comprising: means for transducing electrical signals to and from ultrasonic signals, said means for transducing including means for transmitting and receiving ultrasonic shear waves; buffer means including first and second surfaces and reference reflector means, said second surface being coupled to said ice-accreting surface, said first surface being coupled to said means for transducing for receiving ultrasonic signals therefrom and for transmitting ultrasonic echo signals thereto, said reference reflector means being operative partially to reflect ultrasonic signals that are transmitted thereto through said first surface from said means for transducing back through said first surface to said means for transducing in the form of reference-echo signals; said buffer means being operative in providing a propagation time delay for ultrasonic signals propagating therethrough so that ultrasonic signals emitted from said means for transducing have substantially subsided therein prior to arrival thereat of ultrasonic echo signals, including reference echo signals, that have had their origin in the emitted ultrasonic signals; pulser/receiver means electrically coupled to said means for transducing for providing electrical signals thereto to effect transmission of corresponding ultrasonic signals therefrom and for receiving electrical echo signals corresponding to ultrasonic echo signals received by said means for transducing; and, means for resolving electrical echo signals received from said pulser/receiver means in relation to reference echo signals received from said pulser/receiver means to obtain electrical detection signals corresponding to icing onset and ice accretion conditions upon said ice-accreting surface; wherein said ice-accreting surface substantially reflects ultrasonic shear waves even if water is present thereupon, wherein ultrasonic signals propagate into an ice accretion in presence thereof upon said ice-accreting surface and reflect from an ice/air interface of the ice accretion in a discriminatably delayed manner in relation to reference echo signals reflected from said reference reflector means, and wherein ultrasonic shear waves are reflected substantially at said ice-accreting surface during icing onset thereupon in a discriminatably attenuated form in relation to reference echo signals reflected from said reference reflector means.

Claim 27

A method for detecting ice upon an ice-accreting surface, including detecting of icing onset, employing ultrasonic pulse-echo techniques including use of ultrasonic shear waves, the method being effected by an apparatus that includes transducer means coupled via buffer means to said ice-accreting surface, said buffer means including a reference reflector therein, the method comprising the steps of: (a) transmitting initial ultrasonic signals by said transducer means into said buffer mean toward said ice-accreting surface; (b) receiving ultrasonic echo signals of said initial ultrasonic signals by said transducer means from said buffer means, said ultrasonic echo signals including reference-echo signals, icing-presence detection signals, and icing-onset detection signals, said icing-onset detection signals using shear waves; (c) partially reflecting said initial ultrasonic signals from said reference reflector to provide said ultrasonic reference-echo signals; (d) reflecting portions of said initial ultrasonic signals from an ice/air interface of an ice accretion in the presence thereof upon said ice-accreting surface to provide said ultrasonic icing-presence detection signals, said ultrasonic icing-presence detection signals being discriminatably delayed in relation to said ultrasonic reference-echo signals in correspondence with the thickness of said ice accretion; (e) reflecting portions of said initial ultrasonic signals that use shear waves substantially at said ice-accreting surface during icing onset thereat to provide said ultrasonic icing-onset detection signals, said ultrasonic icing-onset detection signals being discriminatably attenuated in relation to said ultrasonic reference-echo signals as a consequence of said icing onset; (f) transducing said ultrasonic echo signals received by said transducer means to corresponding electrical echo signals and resolving the electrical signals corresponding to said icing-presence detection signals and to said icing-onset detection signals in relation to the electrical signals corresponding to said reference-echo signals to obtain electrical detection signals corresponding to ice-accretion and icing-onset conditions at said ice-accreting surface; said buffer means providing an ultrasonic propagation time delay for said initial ultrasonic signals and for said ultrasonic echo signals so that said ultrasonic echo signals arrive after subsidence of transmitted initial ultrasonic signals in said transducer means.

Claim 28

A method for detecting ice upon an ice-accreting surface, including detecting of icing onset, employing ultrasonic pulse-echo techniques including use of ultrasonic shear waves, the method being effected by an apparatus that includes transducer means coupled via buffer means to said ice-accreting surface, said buffer means including a reference reflector therein, the method comprising the steps of: (a) transmitting initial ultrasonic signals by said transducer means into said buffer mean toward said ice-accreting surface; (b) receiving ultrasonic echo signals of said initial ultrasonic signals by said transducer means from said buffer means, said ultrasonic echo signals including reference-echo signals, icing-presence detection signals, and icing-onset detection signals, said icing-onset detection signals using shear waves; (c) partially reflecting said initial ultrasonic signals from said reference reflector to provide said ultrasonic reference-echo signals; (d) reflecting portions of said initial ultrasonic signals from an ice/air interface of an ice accretion in the presence thereof upon said ice-accreting surface to provide said ultrasonic icing-presence detection signals, said ultrasonic icing-presence detection signals being discriminatably delayed in relation to said ultrasonic reference-echo signals in correspondence with the thickness of said ice accretion; (e) reflecting portions of said initial ultrasonic signals that use shear waves substantially at said ice-accreting surface during icing onset thereat to provide said ultrasonic icing-onset detection signals, said ultrasonic icing-onset detection signals being discriminatably attenuated in relation to said ultrasonic reference-echo signals as a consequence of said icing onset; (f) transducing said ultrasonic echo signals received by said transducer means to corresponding electrical echo signals and resolving the electrical signals corresponding to said icing-presence detection signals and to said icing-onset detection signals in relation to the electrical signals corresponding to said reference-echo signals to obtain electrical detection signals corresponding to ice-accretion and icing-onset conditions at said ice-accreting surface; said buffer means providing an ultrasonic propagation time delay for said initial ultrasonic signals and for said ultrasonic echo signals so that said ultrasonic echo signals arrive after subsidence of transmitted initial ultrasonic signals in said transducer means.