Fault suppressing signal selection apparatus

Claim 2

Signal selection apparatus for use with a control system having at least three redundant channel signals comprising: a signal selector means, having a plurality of inputs each for receiving a separate one of said channel signals, said signal selector means for selecting an intermediate value signal from the channel signals received; comparator means, having two inputs, for comparing signals received at its inputs and generating a switching signal when the received signals differ by a predetermined amount; connective means for providing said selected intermediate value signal and a first redundant channel signal at the comparator means inputs; and, means responsive to said switching signal for substituting a passive signal at the signal selector means input which receives said first redundant channel signal.

Claim 3

The apparatus of claim 1 wherein a time delay element is connected between said comparator means and said means responsive to said switching signal, to introduce a time delay between comparison of the received signals and substitution of a passive signal, whereby nuisance switching due to transients in said first redundant channel signal is lessened.

Claim 4

Fault suppressing signal selection apparatus, for use in a control system having a plurality of redundant channel signals, a first pair of which is affected by a monitored element which generates a validity signal during proper operation, said signal selection apparatus comprising: a plurality of first sense pass extreme elements, each of which has two inputs and an output, each operable to select from the signals present at its inputs the extreme signal defined with respect to one sense and to provide said extreme signal at its output; means for providing said redundant channel signals to the inputs of said first sense pass extreme elements so that all first sense pass extreme elements receive a distinct pair of channel signals, one of said first sense pass extreme element receiving said first pair; a second sense pass extreme element, connected to receive the extreme signals at the outputs of said first sense pass extreme elements and operable to select from the received signals the extreme signal defined with respect to a sense opposite that of the first sense pass extreme element for use as a control signal and for said control system; first switching means, responsive to absence of said validity signal, for disconnecting the output of the first sense pass extreme element which receives said first pair of channel signals from the second sense pass extreme element; and, second switching means, responsive to absence of said validity signal, for substituting a passive signal for each of said first pair of channel signals at each first sense pass extreme element input to which one of said first pair was provided.

Claim 5

Fault suppressing signal selection apparatus, for use in a control system having a plurality of redundant channel signals, a first pair of which is affected by a monitored element which generates a validity signal during proper operation, said signal selection apparatus comprising: a plurality of first sense pass extreme elements, each of which has two inputs and an output, each operable to select from the signals present at its inputs the extreme signal defined with respect to one sense and to provide said extreme signal at its output; means for providing said redundant channel signals to the inputs of said first sense pass extreme elements so that all first sense pass extreme elements receive a distinct pair of channel signals, one of said first sense pass extreme element receiving said first pair; a second sense pass extreme element, connected to receive the extreme signals at the outputs of said first sense pass extreme elements and operable to select from the received signals the extreme signal defined with respect to a sense opposite that of the first sense pass extreme element for use as a control signal and for said control system; first switching means, responsive to absence of said validity signal, for disconnecting the output of the first sense pass extreme element which receives said first pair of channel signals from the second sense pass extreme element; and, second switching means, responsive to absence of said validity signal, for substituting a passive signal for each of said first pair of channel signals at each first sense pass extreme element input to which one of said first pair was provided.

Claim 6

The apparatus of claim 3 in combination with: a comparator, connected to receive the signal selected by the second sense, pass extreme element and one redundant channel signal, which comparator generates switching signal in the event that the difference between the signals the comparator receives exceeds a predetermined amount; and, third switching means responsive to said switching signal to substitute, at the inputs to said first sense pass extreme elements, a passive signal for the said one redundant channel signal.

Claim 7

Signal selection apparatus for a control system having four channel signals, with a first pair of channel signals affected by a monitored sensor, and a second pair of channel signals affected by an unmonitored sensor, said selection apparatus comprising: four input terminals to each of which a separate channel signal is supplied; first selector means for accepting pairs of channels signals, selecting the extreme signal of each pair with respect to a first polarity, and providing the selected signals as output signals; means for interconnecting the input terminals to saiD first selector means in pairs so that each channel signal at an input terminal is present in at least two of the pairs of channel signals at the first selector means; second selector means for accepting a plurality of input signals, selecting the extreme signal with respect to a second polarity, and providing the signal selected by said second selector means for use as a control signal; means for supplying the output signals from said first selector means as input signals to said second selector means; output validity logic responsive to failure of said monitored sensor to generate a logic signal when such failure occurs; and, switching means associated with the output validity logic and responsive to the logic signal therefrom to ground the two input terminals to which said first pair of channel signals is supplied.

Claim 8

Signal selection apparatus for a control system having four channel signals, with a first pair of channel signals affected by a monitored sensor, and a second pair of channel signals affected by an unmonitored sensor, said selection apparatus comprising: four input terminals to each of which a separate channel signal is supplied; first selector means for accepting pairs of channels signals, selecting the extreme signal of each pair with respect to a first polarity, and providing the selected signals as output signals; means for interconnecting the input terminals to saiD first selector means in pairs so that each channel signal at an input terminal is present in at least two of the pairs of channel signals at the first selector means; second selector means for accepting a plurality of input signals, selecting the extreme signal with respect to a second polarity, and providing the signal selected by said second selector means for use as a control signal; means for supplying the output signals from said first selector means as input signals to said second selector means; output validity logic responsive to failure of said monitored sensor to generate a logic signal when such failure occurs; and, switching means associated with the output validity logic and responsive to the logic signal therefrom to ground the two input terminals to which said first pair of channel signals is supplied.

Claim 9

The apparatus as defined by claim 5 wherein said first selector means is configured to receive not more than five pairs of channel signals, and said means for interconnecting connects the input terminals to said first selector means so that, with the exception of the subset comprised of said second pair of channel signals, the channel signals present at the input terminals are paired at the first selector means in all possible distinct subsets of two.

Claim 10

The apparatus as defined by claim 5 wherein a first pair of input terminals is supplied with said second pair of channel signals, and said first pair of the input terminals is interconnected with said first selector means so that each of the signals supplied to said first pair of the input terminals is paired only with signals supplied to the remaining input terminals not included in said first pair.