Method of and apparatus for pipe length measurement

Claim 3

A method as specified in Claim 1 including the further steps of: determining the speed of sound under-the ambient conditions, adjusting the frequency of operation of the oscillator in accordance with such determination,

Claim 4

A method as specified in Claim 2 including the further step of visually displaying the oscillator count in units commonly used for pipe length measurement.

Claim 7

A method as specified.in Claim 4 including the further step of: measuring the ambient temperature, and adjusting the frequency of operation of the oscillator in accordance with the measured ambient temperature.

Claim 10

A method as specified in Claim 6 wherein the amplitude of the reflected acoustical wave resulting from the second pulse at which the count of the oscillator is stopped is above the threshold of reflected acoustical waves tending to be caused by debris in the pipe.

Claim 11

A method as specified in Claim 6 wherein the count of the oscillator is stopped when the amplitude of the reflected acoustical wave resulting from the second pulse is approximately forty percent (40%) of the greatest peak.

Claim 12

A method as specified in Claim 7 including the further steps of: measuring the ambient temperature, and adjusting the final count of the oscillator in accordance with the measured ambient temperature.

Claim 13

A hand-held probe for measuring the length of an open pipe from a selected end, said probe having a forward face in spaced open air communication with the interior of the pipe at the selected end, comprising, a transducer comprising a sound generator and a sound detector mounted in said probe adjacent the forward face of the probe, an oscillator, means for causing said transducer to produce at least a single sound pulse, means for causing the beginning of a count of the cycles of said constant frequency oscillator with the production of such sound pulse, means for modifying the duration of the oscillator count in accordance with a value that, for different pipe diameters over a predetermined range, is equal to twice the sum of the distances from the selected end of the pipe to the transducer and the other end of the pipe to the adjacent impedance-reflective surface, means including said transducer for detecting the resulting reflected acoustic wave from the impedance reflective surface adjacent the other end of the pipe, and means for stopping the count of said oscillator responsively to such detection.

Claim 14

A hand-held probe for measuring the length of an open pipe from a selected end, said probe having a forward face in spaced open air communication with the interior of the pipe at the selected end, comprising, a transducer comprising a sound generator and a sound detector mounted in said probe adjacent the forward face of the probe, an oscillator, means for causing said transducer to produce at least a single sound pulse, means for causing the beginning of a count of the cycles of said constant frequency oscillator with the production of such sound pulse, means for modifying the duration of the oscillator count in accordance with a value that, for different pipe diameters over a predetermined range, is equal to twice the sum of the distances from the selected end of the pipe to the transducer and the other end of the pipe to the adjacent impedance-reflective surface, means including said transducer for detecting the resulting reflected acoustic wave from the impedance reflective surface adjacent the other end of the pipe, and means for stopping the count of said oscillator responsively to such detection.

Claim 15

A hand-held probe as specified in Claim 10 further including means for determining the speed of sound under the ambient conditions; and means for adjusting the frequency of operation of said oscillator in accordance with such determination.

Claim 16

A hand-held probe as specified in Claim 11 further including means connected to said oscillator for visually displaying the oscillator count in units commonly used for pipe length measurement,

Claim 17

A pipe probe coupling means shaped to space the probe a distance from a selected end of the pipe that varies inversely with the pipe internal diameter.

Claim 18

A pipe probe coupling means shaped to space the probe a distance from a selected end of the pipe that varies inversely with the pipe internal diameter.

Claim 19

A hand-held acoustical probe for measuring the length of a pipe from a selected end including mechanical means for positioning said probe in spaced open.air communication with the interior of the pipe at the selected end, the shape of said means being such that the distance the probe is spaced from the selected end varies inversely with the pipe internal diameter.

Claim 20

A hand-held acoustical probe for measuring the length of a pipe from a selected end including mechanical means for positioning said probe in spaced open.air communication with the interior of the pipe at the selected end, the shape of said means being such that the distance the probe is spaced from the selected end varies inversely with the pipe internal diameter.

Claim 21

A hand-held probe as specified in Claim 14 wherein said probe comprises an elongated structure and includes an acoustical transducer adjacent a first end thereof, and wherein said mechanical means is attached to said first end, said mechanical means comprising a triangular wire frame the apex of which is positioned forwardly of said first end.

Claim 22

16: A hand-held probe as specified in Claim 15 wherein the angle of said triangular wire frame at the apex thereof is in a range of 96° to 136°.

Claim 23

A hand-held probe as specified in Claim 15 further including a cylindrical tube that is symmetrically attached at one end to said triangular wire frame between the apex thereof and said first end of said probe.

Claim 24

A hand-held probe as specified in Claim 15 further including a pistol grip handle positioned intermediate said first end of said probe and the other end thereof, said handle including a push button switch for initiating operation of said probe, and further including a display device at the other end for visually displaying pipe lenght measurements.

Claim 25

A hand-held probe as specified in Claim 15 including an ambient temperature compensating resistor mounted on said triangular wire frame at the inside of the bend at the apex thereof.

Claim 26

A hand-held probe for measuring the length of an open pipe from a selected end, said probe having a forward face in spaced open air acoustical communication with the interior of the pipe at the selected end, comprising, a transducer comprising a sound generator and a sound detector mounted in said probe adjacent said forward face, a pulse generator, a flip flop, a constant frequency oscillator, a power source, a switch means controlled by the switch for connecting said power source to activate said pulse generator and the said oscillator, said pulse generator when activated producing a pulse, and said oscillator when activated beginning a count, means connecting said pulse generator to said flip flop, means connecting said flip flop to said sound generator whereby the pulse produced by said pulse generator is transmitted through said flip flop to activate said sound generator to produce a sound pulse, acoustical reflection from the impedance reflective surface adjacent the far end of the pipe resulting from the pulse produced by said sound generator being detected by said sound detector, , a connection from said flip flop to said amplifier, a connection from said amplifier to said oscillator, and a connection from said oscillator to said display unit, a signal generated by said sound detector upon detection of said resulting acoustical reflection being transmitted by said flip flop and said amplifier to disable said oscillator to stop the counting.

Claim 27

A hand-held probe for measuring the length of an open pipe from a selected end, said probe having a forward face in spaced open air acoustical communication with the interior of the pipe at the selected end, comprising, a transducer comprising a sound generator and a sound detector mounted in said probe adjacent said forward face, a pulse generator, a flip flop, a constant frequency oscillator, a power source, a switch means controlled by the switch for connecting said power source to activate said pulse generator and the said oscillator, said pulse generator when activated producing a pulse, and said oscillator when activated beginning a count, means connecting said pulse generator to said flip flop, means connecting said flip flop to said sound generator whereby the pulse produced by said pulse generator is transmitted through said flip flop to activate said sound generator to produce a sound pulse, acoustical reflection from the impedance reflective surface adjacent the far end of the pipe resulting from the pulse produced by said sound generator being detected by said sound detector, , a connection from said flip flop to said amplifier, a connection from said amplifier to said oscillator, and a connection from said oscillator to said display unit, a signal generated by said sound detector upon detection of said resulting acoustical reflection being transmitted by said flip flop and said amplifier to disable said oscillator to stop the counting.

Claim 28

A hand-held probe as claimed in claim 20 including means for positioning the forward face of said probe with respect to the selected end of the pipe such that the sum of the distance thereof to the selected end of the pipe and the distance of the far end of the pipe to the impedance reflective surface is a constant, for convenience, designated "C", a delay device connected between said power source and said oscillator to introduce a delay of seconds, where V is the speed of sound, before activation of the oscillator to begin a count.

Claim 29

A hand-held probe as specified in Claim 20 or 21 including an ambient temperature sensor to sense the temperature of the air in the region of the selected end of the pipe, and further including means connected to said sensor for adjusting the frequency of operation of said oscillator to compensate for variations in the ambient air temperature.

Claim 30

A hand-held probe as specified in claim 20, 21 or 22 further including a display device, and a connection from said oscillator to said display device for displaying the count of said oscillator, said display device being mounted on a rear face of said probe.

Claim 31

A hand-held probe as specified in any of claims 20 to 23 wherein said flip flop, following the production of a pulse by said sound generator, introduces a delay of predetermined duration before accepting a signal from said sound detector and transmitting such signal to said amplifier and said oscillator to allcw for dampening of said sound generator.

Claim 32

A hand-held probe, as specified in any of claims 20 to 24 wherein said sound generator and said sound detector of said transducer are constituted by a single device, said single device comprising a diaphragm having a piezoelectric element attached substantially at the centre thereof with a reaction mass attached to the piezoelectric element.

Claim 33

A hand-held probe, as specified in claim 25 wherein said diaphragm is flat.

Claim 34

A hand-held probe, as specified in any of claims 20 to 26 wherein said oscillator includes a resistor-capacitor circuit, and wherein said probe further includes a plurality of resistors each having a different value, and switch means for selectively connecting said resistors in circuit with said resistor-capacitor circuit to vary the frequency of operation of said oscillator whereby to adjust the units of measurement.

Claim 35

A hand-held probe for measuring the length of an open pipe from a selected end, said probe having a forward face that when in pipe length measuring position is in spaced open air communication with the interior of the pipe at the selected end thereof, a transducer mounted adjacent the forward face of the probe and operative when activated to produce and direct an acoustical pulse into the interior of the pipe, said transducer including means for detecting reflected acoustical waves emanating from the interior of the pipe, a mircoprocessor including a programmed memory, a pulse generator, and a constant frequency clock oscillator, means including amplifying means.connecting said microprocessor to said transducer, the threshold level of response of said amplifying means being adjustable, switch means to activate said microprocessor, said microprocessor, when activated, operating responsively to said memory to carry out a sequence of operations including: . activating said pulse generator to produce a first electrical pulse and thereby through said amplifying means causing said transducer to produce a first acoustical pulse, responding to and measuring through said transducer and said amplifying mean's the amplitude of the greatest peak of the reflected wave resulting from the first acoustical pulse, adjusting the threshold of response of said amplifying means to an acoustical level that is substantially less than said greatest peak, activating said pulse generator to produce a second electrical pulse and thereby through said amplifying means causing said transducer to produce a second acoustical pulse, simultaneously causing a count to begin of the cycles of said constant frequency clock oscillator, and stopping said count responsively to the detection by said transducer, through said amplifying means, of a reflected acoustical wave having an amplitude exceeding said threshold.

Claim 36

A hand-held probe for measuring the length of an open pipe from a selected end, said probe having a forward face that when in pipe length measuring position is in spaced open air communication with the interior of the pipe at the selected end thereof, a transducer mounted adjacent the forward face of the probe and operative when activated to produce and direct an acoustical pulse into the interior of the pipe, said transducer including means for detecting reflected acoustical waves emanating from the interior of the pipe, a mircoprocessor including a programmed memory, a pulse generator, and a constant frequency clock oscillator, means including amplifying means.connecting said microprocessor to said transducer, the threshold level of response of said amplifying means being adjustable, switch means to activate said microprocessor, said microprocessor, when activated, operating responsively to said memory to carry out a sequence of operations including: . activating said pulse generator to produce a first electrical pulse and thereby through said amplifying means causing said transducer to produce a first acoustical pulse, responding to and measuring through said transducer and said amplifying mean's the amplitude of the greatest peak of the reflected wave resulting from the first acoustical pulse, adjusting the threshold of response of said amplifying means to an acoustical level that is substantially less than said greatest peak, activating said pulse generator to produce a second electrical pulse and thereby through said amplifying means causing said transducer to produce a second acoustical pulse, simultaneously causing a count to begin of the cycles of said constant frequency clock oscillator, and stopping said count responsively to the detection by said transducer, through said amplifying means, of a reflected acoustical wave having an amplitude exceeding said threshold.

Claim 37

2 9 . A hand-held probe as specified in Claim 28 including temperature responsive means positioned on the probe to respond to the temperature of the ambient air adjacent the selected end of the pipe, said memory being operative upon activation of said switch means to effect an adjustment in the frequency of operation of said constant frequency oscillator to compensate for variations in the ambient air temperature.

Claim 38

A hand-held probe as specified in claim 29 further including display means and display driving means connected thereto, and means connecting said display driving means to said microprocessor for activating said display means in accordance with the count of said constant frequency clock oscillator.

Claim 39

A hand-held probe as specified in claim 30 further including a standoff frame associated with the forward face of said probe to space said forward face a distance from the selected end of the pipe that is in inverse relationship with the diameter of the pipe.

Claim 40

A hand-held probe as specified in claim 28 wherein said memory has stored therein a table of sound velocity versus ambient air conditions, and further including means responsive to the condition of the ambient air adjacent the selected end of the pipe, said last mentioned means having a connection to said microprocessor whereby said microprocessor is enabled to determine the speed of sound at the ambient condition from the table and to effect a compensating adjustment to the pipe length measurement.