Level measuring equipments

Claim 2

An acoustic wave level measuring apparatus for use with large capacity liquid medium stocking tanks, comprising in combination: a digital display metering indicator including a pulse counter; first and second counting pulse generating means; first electroacoustic wave transducer means activated by the presence of the liquid medium in the tank, to generate a first series of level measuring signals of medium accuracy of measurement during a complete operation of either filling, or emptying, the tank; second electroacoustic wave transducer means activated by the presence of the liquid medium in an upper portion of the tank, generating a second series of level measuring signals of higher accuracy of measureMent during that part of the filling, respectively emptying, operation concerning that upper portion of the tank, and, electrical signal gating means connected to said transducer and counter for controlling the selective application of the pulses from said first and second counting pulse generating means, to an activation input of said counter, said gating means including: first means controlling the application of the pulses from said first counting pulse generating means to said activation input under the control of the signals of said first series, second means controlling the application of the pulses from said second counting pulse generating means to said activation input under the control of the signals of said second series, third means blocking the application of pulses from said second counting pulse generating means during the periods of inactivity of said second electroacoustic wave transducer means, and, fourth means blocking the application of pulses from said first counting pulses generating means during the periods of activity of said second electroacoustic wave transducer means.

Claim 3

Apparatus according to claim 1, wherein: said first electroacoustic wave transducer means comprises a transducer located near the bottom of the tank and actuated from a source of medium frequency pulse electrical waves and a receiver of the said actuation wave and the echo pulses from said transducer, said receiver including means deriving therefrom a series of rectangular waveform signals the width of each of which is proportional to the time interval between a pulse from the actuation wave and the echo pulse from the transducer responsive to the said actuation pulse, said second electroacoustic wave transducer means comprises a transducer located in the upper part of the tank actuated from a high frequency pulse electrical wave and a receiver of the said actuation wave and the echo pulses from said transducer, said receiver including means deriving therefrom a series of rectangular waveform signals the width of each of which is proportional to the time interval between a pulse from the actuation wave and the pulse, said first counting pulse generating means comprises a transducer located at substantially the same level as the transducer of the said first electroacoustic wave transducer means, a wave reflector facing said transducer at a fixed horizontal distance therefrom, a self-relaxation oscillator arrangement of which said transducer and reflector are parts, and frequency multiplying circuits of the pulses from said oscillator arrangement, said second counting pulse generating means comprises a transducer located at substantially the same level as the transducer of the said second electroacoustic wave transducer means, a wave reflector facing said transducer at a fixed horizontal distance thereof, a self-relaxation oscillator arrangement of which said transducer and reflector are parts, and frequency multiplying circuits of the pulses from said oscillator arrangement, said first and second electrical signal gating means comprise an AND-gate receiving the counting pulses on one input thereof and the rectangular waveform pulses on another input thereof, said third electrical signal gating means comprises a gate receiving the pulses from the output of said frequency multiplying circuits of the second counting pulse generating means, having its output connected to the pulse input of the rectangular waveform signals from the said first electroacoustic wave transducer means through a gate having an inhibiting input fed with the rectangular waveform signals from the said second electroacoustic wave transducer means, the output of the last mentioned gate being further connected to the rectangular waveform input of said AND-gate, and, said fourth electrical signal gating means comprises a gate receiving the output pulses from the frequency multiplying circuits of the first counting pulse generating means, having its output cOnnected to the pulse input of said AND-gate and having an inhibiting input connected to the output of the rectangular waveform signals from the said second electroacoustic wave transducer means, said last mentioned output being further connected to the rectangular wave-form input of said AND-gate.

Claim 4

Apparatus according to claim 2, wherein an open ended acoustic wave guide is inserted between each one of the transducers of the said first and second electroacoustic wave transducer means and the top of the tank.

Claim 5

Apparatus according to claim 2, wherein cables connecting said transducers to said receiver circuits consist of a cable having a central conductor coated with fritted magnesia and sheathed with stainless steel.

Claim 6

Apparatus according to claim 4, wherein each transducer comprises a stainless steel casing, and a piezoelectric ceramic plate which is spring pressed against the speaking face of the casing with interposition of silver wires within a low temperature grease, said casing being watertightly soldered to the stainless steel sheath of the corresponding cable.

Claim 7

Apparatus for measuring the level of liquid in a tank comprising in combination: a first acoustic transducer located adjacent the bottom of the tank; a second acoustic transducer spaced vertically upwardly from said transducer and located near the top of the tank but below the intended upper level of liquid in the tank, both transducers arranged to propagate acoustic energy upwardly through liquid in the tank and to produce an output signal whenever an acoustic echo is returned to a transducer from the surface of liquid in the tank; means for synchronously energizing said transducer at substantially different frequencies, said second transducer being the higher frequency of the two; indicator means providing a readout of liquid level in the tank; and means including a gate for energizing said indicator means from the output of said first transducer whenever the liquid level in the tank is below the level of said second transducer and for inhibiting the input of said first transducer to said indicator and for energizing said indicator from said second transducer whenever the level of liquid is above said second transducer.

Claim 8

Apparatus for measuring the level of liquid in a tank comprising in combination: a first acoustic transducer located adjacent the bottom of the tank; a second acoustic transducer spaced vertically upwardly from said transducer and located near the top of the tank but below the intended upper level of liquid in the tank, both transducers arranged to propagate acoustic energy upwardly through liquid in the tank and to produce an output signal whenever an acoustic echo is returned to a transducer from the surface of liquid in the tank; means for synchronously energizing said transducer at substantially different frequencies, said second transducer being the higher frequency of the two; indicator means providing a readout of liquid level in the tank; and means including a gate for energizing said indicator means from the output of said first transducer whenever the liquid level in the tank is below the level of said second transducer and for inhibiting the input of said first transducer to said indicator and for energizing said indicator from said second transducer whenever the level of liquid is above said second transducer.

Claim 9

Apparatus as defined by claim 6 including means for varying the frequency of operation of said gate in accordance with the velocity of propagation of sound in the fluid in the tank.