Abstract: A vibrator-type level sensor having a detecting pipe (20) in which an inner vibration member (22) with piezo-electric devices (8a) (8b) (8c) is mounted, the detecting pipe (20) and the inner vibration member (22) constituting a folded cantilever.

Abstract: A device primarily for attachment to the spout of a teakettle for generating a musical signal in response to the vapor pressure of boiling water. A diaphragm distorts in response to the pressure and closes an electrical switch which applies battery voltage to a circuit in which a representation of a pre-selected tune is stored. The tune is applied to a piezoelectric speaker within a resonating housing to audibly signal the user that the water in the teakettle is boiling.

Abstract: Piezoelectric type liquid level sensor for detecting whether the level of various liquids such as oil of an internal combustion engine, a generator or the like is a predetermined value or higher or not, and method of making the sensor. The sensor is arranged to eliminate the influence of the weight of the lead wires on the vibration element and to facilitate its assembly. The sensor may be provided with a damper member for increasing the sensitivity.

Abstract: A sensor for detecting an interface of a liquid in a container comprises a transmitter and a receiver of ultrasonic waves, each situated outside the container, and coupled to the wall of the container by a strip waveguide. The transmitter is arranged to cause surface acoustic waves to propagate through a portion of the wall, and the receiver is arranged to detect waves derived from the transmitter. When the liquid is adjacent to the portion of the wall, mode conversion of the surface acoustic waves in the wall of the vessel into compression waves in the liquid causes a change in the energy of waves reaching the receiver.

Abstract: Apparatus for determining the depth of precipitation accumulating on the surface of a pathway, such as an airport runway or the like, includes a sensor having electrical transducer means for emitting and sensing ultrasonic energy and having a body of material adapted to be embedded in the pathway with the top surface of the body being substantially flush therewith and exposed to the precipitation, the transducer means being physically coupled to the body. A circuit causes the transducer means to emit pulses of ultrasonic energy, which are reflected as first and second reflections from the top surface of the body and from the upper surface of an accumulation of precipitation on the top surface of the body and are respectively returned to the transducer which, in response to the reflected pulses, produces corresponding first and second electrical signals.

Abstract: Procedure to measure the level (14) of a liquid (13) by means of elastic waves, such liquid (13) being contained within an axially moving tube (11) and cooperating with a filler tube (12), the filler tube (12) being used as an element in the transmission of elastic waves to the liquid (13), such elastic waves being picked up (16) outside the axially moving tube (11).Device (10) to carry out the above procedure, which device (10) cooperates with a filler tube (12) and comprises:at least one transducer (15) to transmit energization of the vibration of the filler tube (12), andat least one receiver transducer (16) located outside the axially moving tube (11).

Abstract: An apparatus for detecting and controlling the presence of a gaseous fluid in relation to a predetermined level of liquid in a vessel, being of the ultrasonic type and comprising a pair of piezoelectric transducers, namely a transmitter and a receiver, capable of being disposed on opposite walls of the vessel. An oscillator provides an electric ultrasonic frequency signal to the transmitter transducer and a comparator compares the electric signal supplied by the receiver transducer with a reference signal for triggering an alarm signal when the disparity between the signals being compared exceeds a predetermined value.The apparatus moreover comprises processing means which periodically interrupt the electric signal sent to the transmitter transducer and which check the presence of an alarm at the output of the above mentioned comparator.

Abstract: A device for detecting the presence of a gaseous fluid in relation to a predetermined level of liquid in an elastically deformable vessel comprises a U-shaped body capable of accommodating within it a portion of the vessel at a predetermined liquid level. A pair of piezoelectric transducers in the body, used as transmitter and receiver, is fixed face-to-face on opposite arms of the U-shaped body. The device moreover comprises a cover capable of confining the portion of the vessel inside the U-shaped body, and an elastic device disposed between the cover and the U-shaped body and capable of producing an elastic deformation of the vessel and causing the contact surfaces of transducers to contact intimately the said portion of the vessel without entrapment of air.

Abstract: A transmitting transducer is mounted on the outside wall of a vessel and supplies bursts of ultrasonic energy. If liquid is present, the energy is coupled to the other side of the vessel. Otherwise, the energy is attenuated. A receiving transducer (which may be the same as the transmitting transducer) is positioned to receive the ultrasonic energy if liquid is present. It is gated to be active only when such energy should arrive in the presence of liquid. The receiving transducer therefore generates an electrical signal indicating presence or absence of liquid in the vessel at the level at which the transducers are mounted.

Abstract: An ultrasonic wave transmitter and an ultrasonic wave receiver are disposed in a tank in any positional relation to each other so long as the wave transmission and wave reception surface do not face each other to check whether the liquid level in the tank is above a predetermined level. When both the wave transmitter and wave receiver are submerged in the liquid in the tank, a wave radiated from the wave transmitter can be received by the wave receiver because of the facts that the directivity angle of the wave from the transmitter is large in the liquid and the wave propagates through the liquid without attenuation. When the liquid level decreases and becomes lower than either of the wave transmitters or wave receiver that is at an upper level, a wave from the transmitter can no longer be received by the receiver. This principle is utilized for the liquid level detection.

Abstract: The device for determining and/or monitoring a predetermined filling level in a container has two oscillatory rods secured with spacing adjacent one another on a diaphragm the edge of which is connected to a screw-in part. By means of the screw-in part the device is so secured in a screw-threaded aperture of the container wall at the height of the filling level to be detected that the oscillatory rods project into the container. At the side of the diaphragm remote from the oscillatory rods a bridging member is held spaced from the diaphragm by flexurally elastic rod-shaped supports. Each of the rod shaped supports is rigidly connected at one end to an oscillatory rod. Between the bridging member and the diaphragm there is held, with preloading of the diaphragm, a transducer column comprising in a stack a piezoelectric excitation transducer and a piezoelectric reception transducer.

Abstract: A liquid level sensor includes a pair of sonic waveguides separated from and parallel to one another. The waveguide pair together define axially separated pairs of lens surfaces so that sonic pulses are coupled therebetween in a time phase relationship when liquid covers those lens pairs below the liquid level, cross coupling of those lens pairs above the liquid level thereby being prevented. Since the axial separation dimension of the lens pairs is known as well as the vessel geometry and location of the waveguide pair in the vessel, counting the pulses returned by virtue of such cross coupling of those lens pairs below the liquid level will establish accurate level detection by standard algorithmic techniques.

Abstract: Method and apparatus for detecting the presence of liquid in a container includes an elongate rod (or other vibratory element) which extends into the container to contact liquid when a certain amount of liquid is present, a piezo-electric element coupled to the rod on the exterior of the container to cause the rod to vibrate in response to electrical signals and to produce electrical signals indicative of the amplitude of vibration of the rod, and circuitry for producing a utilization signal when the electrical signals produced by the piezo-electric element indicate that the amplitude and duration of vibrations of the rod are below some threshold level. Such vibrations fall below the threshold level when the rod contacts liquid in the tank and so production of the utilization signal is an indication that liquid in the container has reached a certain level.

Abstract: An apparatus for measuring acoustic transmission characteristics of at least one medium to be measured in which at least one elongated hollow chamber is immersed. The chamber is closed at its bottom end and is filled with an acoustic connecting liquid, and at least two separate movable transducers are immersed in the connecting liquid within the chamber in spaced relation to the wall thereof, the chamber having a cross-sectional shape such that a directional acoustic path between opposite emitter and collector transducers passes through the medium to be measured, the medium being out of direct contact with the transducers.

Abstract: The level detector is to be used for starting and stopping an electric system such as a pump. It comprises a piezo-electric crystal (31) squeezingly mounted between two elastically resilient membranes (22, 23) situated between two squeezing members (11, 12). These squeezing members form a top part (11) and a bottom part (12), respectively, which together form a sensor housing (10). On the outside the membranes are coated with a thin, insulating plastic layer (21, 24) and form the electric connection to the crystal. The two membranes are kept separated by means of a plurality of insulating, annular disks (25-28). In this manner a sturdy and reliable mounting of the piezo-electric crystal is obtained.

Abstract: An offshore drilling tower has at least one upright hollow member extending from below the water to support an above-water platform. A detector in or on the hollow member, usually below the water, responds to a water leak into the hollow member. The detector includes a signal generator responsive to pressure or chemical effect of the water. The detector is effective when actuated by water intrusion into the hollow member and into contact with the detector to send a signal of a unique or distinct frequency through the member itself to a signal receiver, preferably on the platform. The receiver is tuned to the distinct frequency and is effective upon receipt of such signal to afford an indication that the detector has been actuated by a water leak at a particular location.

Abstract: An electroacoustic transducer is provided in the form of a flexible tape formed of an inner flat metal foil 10 surrounded by a metal foil 14 and separated from the latter by an electret 12. The outer metal foil 14 is in turn surrounded by a PVC outer layer 20. This construction provides a flexible electret type of microphone with the additional advantage of immunity from ambient acoustic waves and electrical and magnetic fields.

Abstract: A highly sensitive liquid level detection system. It employs a piezoelectric transducer that has a natural frequency of vibration which effectively varies depending upon the amount that the transducer is immersed in a liquid. An emf is applied to the transducer to cause it to vibrate at the effective natural frequency, and the exact frequency is counted which count indicates the amount of immersion with a high degree of accuracy. A printer may be employed to periodically record the frequency count.

Abstract: A high liquid level sensor comprising a tubular probe, with a peripheral wall (6), and arranged to be suspended in a liquid container. An ultrasonic signal is transmitted around the wall (6) from a transmitting transducer (12) potted in a block (11), which is bonded to the inner surface of the wall, to a receiving transducer also potted in the block. A detector circuit connected to the receiving transducer via a lead (10) discriminates between the signal level when the probe is immersed in gas and the lower signal level when the probe is immersed in liquid, and provides a corresponding switched output.

Abstract: An apparatus for detecting a residual quantity of toner remaining in the supply hopper of a copying machine includes a piezoelectric vibrating element disposed in a wall of the hopper and having a surface normally positioned in contact with toner in the hopper, and an electronic circuit for causing vibration of the element at a predetermined frequency and for detecting changes in operating characteristics of the element as representative of a decrease in the amount of toner in the hopper to operate a warning device.

Abstract: An apparatus for locating the level of a liquid in a closed metallic container having curvilinear walls with a thickness of from 1/8 to 3/8 inch is disclosed comprising a manually portable transducer having a piezoelectric material for transmitting and receiving sonic waves, and a sonic pulse generator capable of exciting the piezoelectric material to emit sonic signals into the container from a location adjacent the outside wall of such container at a frequency within about 20% of the natural resinate frequency of the container.

Abstract: This invention relates to damping pads and accoustical horns for use with transducer assemblies. The problems of proximity detection ranges, subfreezing operating temperature ranges, ringing and backwave reflection are addressed. In a preferred embodiment of an ultrasonic level control indicator using a piezoelectric transducer, a resilient, compressible sound absorbing damping material (like polyurethane pads) is compressed against the transducer vibrating member to decrease ringing and backwave effects. An acoustical horn assembly with a tapered opening is positioned adjacent the transducer to improve the signal.

Abstract: Methods and systems employing acoustic techniques are disclosed for determining the level of fluid in a container. Flexural mode acoustic waves are set up in the walls of the container. The change in travel time of flexural mode acoustic waves are measured and calibrated in terms of the level of fluid in the container. Systems for continuously monitoring fluid level or indicating when fluid level reaches a predetermined horizontal level are disclosed.

Abstract: A liquid storage tank contents gauge comprises means providing an electrical signal corresponding to the vertical height of the liquid in a tank in the form of an ultrasonic transducer positioned at the base of the tank and emitting a pulse of acoustic energy vertically upwards and which detects the pulse when reflected from the liquid/air interface within the tank and including timing means provided to time the interval between the emission of the pulse and the detection of the reflected pulse, electronic means for deriving the volume of liquid corresponding to the vertical height, and an output means for providing a visual output of this volume.

Abstract: A liquid level sensing device consists of an elongate member in which flexure waves are induced. By partially submerging the elongate member in a fluid the depth of immersion can be determined from characteristics of the flexure waves. In one mode of operation the transit time for a flexure wave to travel along the elongate member is measured, and in another mode the nature of resonant modes in the flexure wave is determined.

Abstract: An ultrasonic filling position limit switch having disposed in the container at the full level thereof, at least one ultrasonic transducer for sending out ultrasonic pulses and for receiving echo pulses reflected off the opposite container wall. An amplifier of the electric output signals of the transducer is connected to a threshold limit switch which provides an output signal when the amplifier output signal exceeds a predetermined threshold value. The amplifier output is fed back to an amplifier control input by means of an amplifier control circuit which seeks to maintain the amplifier output signal at an adjustable constant nominal value. A control device blocks the control circuit for the duration of time in each sending period required for the sending out of the ultrasonic sending pulses and for receiving the echo pulses.

Abstract: The present apparatus is designed to determine the presence of an intruder in a swimming pool by detecting a predetermined change in water level caused by displacement. The surface of the pool water forms the lower boundary of an air filled acoustic cavity, and cavity resonance is excited therein by a sonic transducer coupled to the cavity and also to a signal amplifier, causing the cavity to determine the frequency of oscillation of the feedback amplifier. A rise in water level caused by intruder displacement decreases the vertical dimension of the cavity so that the cavity has a different resonant frequency than before intrusion, and the amplifier therefore oscillates at a different frequency. The predetermined change in amplifier signal output frequency is sensed by an electrical network and converted to an alarm device activating signal to indicate an intrusion.

Abstract: An ullage measuring device and an accurate method of using an ullage tape to find the surface of a liquid in a tank without visual sighting. The ullage device includes a composite tape formed of a tape from which readings of ullage may be obtained and electrical conductors to activate circuitry for rendering a crystal operative to transmit sonic energy to another crystal adapted to receive sonic energy and to activate one of the conductors to provide an audible indication at a point remote from the surface of the liquid when the effective end of the composite tape has reached the surface of the liquid.

Abstract: A method of controlling gas-liquid or liquid-liquid interface in monolayer reservoirs, wherein mechanical vibrations are excited within a section of the reservoir wall by means of a wave of acoustic vibrations, the velocity of propagation of mechanical vibrations being approximately equal to that of the wave wake of acoustic vibrations along this wall, the interface being ascertained from the amplitude of the acoustic wave transformed from said mechanical vibrations which propagate along said reservoir wall. A device for performing said method consists of two sound conductors with effective areas, an emitter of the wave of acoustic vibrations and a receiver of an acoustic wave being established on said effective areas respectively.