On-board tire strut fault apparatus for aircraft and the like

Claim 2

Apparatus for sensing and signalling faults associated with a suspension structure for vehicles and the like having a plurality of spaced load-carrying supports such as wheels and the like, comprising a plurality of strain-gage transducer means each producing an electrical output characterizing the loading being carried by a different one of said supports, electrical comparator means for producing output signals characterizing differences between two input signals applied thereto, means applying as input signals to said comparator means a first signal related to the first electrical output from at least one of said transducer means and a reference signal related to a selected portion of the second electrical output from at least one other of said transducer means, and fault-signalling means responsive to said output signals from said comparator means, whereby said input signals to said comparator means tend to vary together with changes in the overall loading experienced by said suspensions structure and said differences between said input signals tend to increase upon occurrence of a fault which reduces the load carried by one of said supports and which causes the other of said supports to carry a greater share of the overall loading.

Claim 3

Apparatus as set forth in claim 1 wherein said comparator means includes two comparator channels each for producing said output signals, and wherein said input signals are applied to one of said comparator channels, and further including means applying as input signals to the other of said comparator channels said second electrical output and a reference signal related to a selected portion of said first electrical output.

Claim 4

Apparatus as set forth in claim 2 wherein said suspension structure includes at least four wheels in a substantially four-cornered array and serving as load-carrying supports for a vehicle, and wherein said transducer means are in stationary relationship with portions of said structure whose elastic deformations characteristize loadings carried by said wheels, said first electrical output comprising a combination of the electrical outputs from two of said transducers which sense said deformations characterizing loadings carried by two of said whEels which are substantially diagonally opposite one another in said array, and said second electrical output comprising a combination of the electrical outputs from another two of said transducers which sense said deformations characterizing loadings carried by another two of said wheels which are substantially diagonally opposite one another in said array.

Claim 5

Apparatus as set forth in claim 3 wherein said portions of said structure comprise axles on which said wheels are mounted, and wherein each said combination of electrical outputs comprises a summation of electrical outputs from two of said transducers.

Claim 6

Apparatus as set forth in claim 4 wherein said suspension structure comprises an aircraft undercarriage, wherein said wheels include pneumatic tires, and wherein said fault-signalling means includes self-latching warning signal means for warning of a ''''blown'''' tire condition of any of said tires, said reference signals being adjustable to prevent warning by said fault-signalling means except when effects of said ''''blown'''' tire condition upon said electrical outputs exceeds effects which may be encountered otherwise.

Claim 7

Apparatus for sensing and signalling faults associated with an aircraft undercarriage structure having struts and at least four pneumatically tired wheels in a four-cornered array and carrying the aircraft loadings, comprising a plurality of strain-gage transducer means each producing an electrical output characterizing the loading being carried by a different one of said wheels, a pair of electrical comparators each producing output signals characterizing differences between two input signals applied thereto, means applying as input signals to one of said comparators a first electrical signal which comprises the summation of electrical outputs from a first pair of said transducer means which characterize the loadings carried by two of said wheels which are substantially diagonally opposite one another in said array, and means applying as reference input signals to said one of said comparator a selected portion of a second electrical signal which comprises the summation of electrical outputs from a second pair of said transducer means which characterize the loadings carried by two other of said wheels which are also substantially diagonally opposite one another in said array, and means applying as input signals to the other of said comparators said second electrical signal and a reference signal comprising a selected portion of said first electrical signal, and fault-signalling means responsive to said output signals from said comparators.

Claim 8

Apparatus for sensing and signalling faults associated with an aircraft undercarriage structure having struts and at least four pneumatically tired wheels in a four-cornered array and carrying the aircraft loadings, comprising a plurality of strain-gage transducer means each producing an electrical output characterizing the loading being carried by a different one of said wheels, a pair of electrical comparators each producing output signals characterizing differences between two input signals applied thereto, means applying as input signals to one of said comparators a first electrical signal which comprises the summation of electrical outputs from a first pair of said transducer means which characterize the loadings carried by two of said wheels which are substantially diagonally opposite one another in said array, and means applying as reference input signals to said one of said comparator a selected portion of a second electrical signal which comprises the summation of electrical outputs from a second pair of said transducer means which characterize the loadings carried by two other of said wheels which are also substantially diagonally opposite one another in said array, and means applying as input signals to the other of said comparators said second electrical signal and a reference signal comprising a selected portion of said first electrical signal, and fault-signalling means responsive to said output signals from said comparators.

Claim 9

Apparatus as set forth in claim 6 wherein said transducer means sense load-induced deformation of axles on which said wheels are mounted, wherein said comparators each include a differential amplifier, and wherein said fault-signalling means includes self-latching relay means for actuating a fault-warning indicator.

Claim 10

Apparatus as set forth in claim 7 wherein at least two of said struts are associated with bogies each having at least four of said wheels in a four-cornered array, said struts being disposed at right and left portions laterally in relation to the aircraft, wherein said first electrical signal comprises the summation of electrical outputs from said first pair of said transducers means disposed on one of said bogies and from a like pair of said transducer means disposed in complementary relation on the other of said bogies, and wherein said second electrical signal comprises the summation of electrical outputs from said second pair of said transducer means disposed on one of said bogies and from a like pair of said transducer means disposed in complementary relation on the other of said bogies.

Claim 11

Apparatus as set forth in claim 8 wherein two further struts are associated with further bogies each having at least four of said wheels in a four-cornered array, one pair of said struts being forward of the other, and a second pair of electrical comparators each characterizing differeNces between two input signals applied thereto, means producing a third electrical signal which comprises the summation of electrical outputs from a third pair of said transducer means characterizing the loadings carried by two substantially diagonally opposite wheels on one of said further bogies and from a like pair of said transducer means disposed in complementary relation to the other of said bogies, means producing a fourth electrical signal which comprises the summation of outputs from a fourth pair of said transducer means characterizing the loadings carried by two other of said wheels which are also substantially diagonally opposite on said one of said further bogies and from a like pair of said transducer means disposed in complementary relation on the other of said bogies, means applying said third electrical signal and a selected portion of said fourth electrical signal as input signals to one of said second pair of comparators, and means applying said fourth electrical signal and a selected portion of said third electrical signal as input signals to the other of said second pair of comparators.

Claim 12

Apparatus as set forth in claim 9 wherein said fault-signalling means warns of a ''''blown'''' tire in the bogies associated with said two of said struts, and further fault-signalling means including self-latching relay means for actuating a ''''blown'''' tire indicator which indicates a ''''blown'''' tire in the bogies associated with said two further struts, said further fault-signalling means being responsive to output signals from said second pair of comparators.

Claim 13

Apparatus as set forth in claim 9 further including first means for comparing said first electrical signal with a selected portion of said fourth, signal, and second means for comparing said second signal with a selected portion of said third signal, and third means for comparing said third signal with a selected portion of said second signal, and fourth means for comparing said fourth signal with a selected portion of said first signal, said comparing means producing output signals characterizing differences between said compared signals, and two further fault-signalling means each for indicating that a strut in a different one of the two sets of struts is not properly supporting said aircraft, one of said further fault-signalling means being responsive only to outputs from said first and second means characterizing that both of said first and second signals are simultaneously less than the selected portions of said fourth and third signals, respectively, and the other of said further fault-signalling means being responsive to outputs from said third and fourth means characterizing that both said fourth and third signals are simultaneously less than the selected portions of said first and second signals, respectively.