Hokushin Electric Works, Ltd.

Tokyo Keiso Kabushiki-kaisha

Yokogawa Electric Corporation

Yokogawa Hokushin Electric Corp.

Yugen-kaisha Techno Data

Tamotsu Kobayashi

Takashi Torimaru

Kunikazu Shigeta

Toru Fujii

Shigeru Goto

Yoshinori Matsunaga

Kazuie Suzuki

Kenichi Kuromori

Tadashi Azegami

Hironobu Ohta

Jun Futamura

Sadaki Igarashi

Takashi Torumaru

Hirofumi Ide

Norihiro Shikuya

A transmission measuring system includes a subject for transmission measurement for outputting, in response to a start signal for measurement from a central processing unit, an output signal including information on a transmission time to be measured. An analog-digital converter converts the output signal into digital data. The central processing unit processes the digital data to obtain the transmission time required for propagating the signal through the subject. A clock signal source provides a clock signal to the central processing unit, and a variable delay unit is interposed between the clock signal source and the analog-digital converter. The central processing unit delivers a delay time control signal to the variable delay unit so that the delay time of the clock signal of the analog-digital converter may be varied with time relative to the start signal for measurement.

Transmission measuring system with high time resolution

A transit-time difference type ultrasonic flowmeter comprises a pair of ultrasonic transducers mounted on a flow tube at an upstream side and a downstream side respectively, a switching device for switching the operational mode of each of the transducers alternatively to its transmitting or receiving mode, an amplifier for amplifying the signal received by the transducer of the receiving side, and a data reduction equipment includes an analog-digital converter and a digital signal processor; the converter converts the waveform into a plurality of voltage-time data sets; and the processor picks up an object peak of the voltage-time data sets on the basis of the time, or the data on the voltage, or determines the peaks of maximum voltage included within the waveform of the voltage-time data sets as an object peak, estimates at least one zero-cross point confined by the object peak or a peak adjacent to the object peak through the calculation made on the plurality of voltage-time data sets distributing along the time axis close to the zero-cross points, and finds the time required for propagating the wave from one zero-cross point or the average time required for propagating the wave from a plurality of zero-cross points.

Transit-time difference type ultrasonic flowmeter

The amplifying gain is controlled by means of a data reduction equipment on the basis of the control signal input into the amplifier for amplifying the received signal propagated through the fluid and received in the ultrasonic transducer in the receiving side. The data reduction equipment includes an analog-digital converter, a processor, and a memory, wherein converted into digital data are waveform data including a peak value of each of the received signals, and the obtained digital data are stored in the memory. The processor screens the peak values stored in the memory to obtain a screened peak value achieved on the fluid including no impurities such as bubbles or solid particles, compares the obtained peak value with the preset peak value set preliminary on the processor, sends a control signal to the gain control terminal of the amplifier on the basis of the result of the comparison, and controls the peak value included in the output signal of the amplifier so as to take the substantially equal value as that of the preset value of the peak.

Ultrasonic flowmeter for controlling the gain of an amplifier for amplifying received signals

A capacitance type electromagnetic flowmeter which is capable of measuring flow rates of fluid without being affected by the flow velocity distribution. When the flow tube of the flowmeter is an open conduit, the measurement is made without being affected by variations in the liquid level. The flowmeter comprises a flow tube insulated at least on an inner surface thereof; an exciting means for applying a magnetic field to the fluid, and a pair of detecting electrodes disposed in the flow tube, which are electrically insulated from the fluid and extend at right angles to the flow tube axis and magnetic field. The length of the electrodes is proportional to the cosine of an angle between a line normal to the wall of the flow tube and an axis perpendicular to both axes of the flow tube and magnetic field. Where a conduit is used, the liquid has a free surface, and currents produced from the detecting electrodes are converted by a current-to-voltage converter into voltage signals.

Capacitance type electromagnetic flowmeter

An electromagnetic flow meter for measuring the flow rate of a fluid by applying to the fluid a magnetic field generated with an exciting current and measuring the resulting signal voltage generated at a pair of electrodes; wherein the exciting current comprises two frequency components which are lower and higher than the usual commercial frequency and the signal voltage comprises two frequencies which are discriminated so that a higher frequency is extracted as a first output and a lower frequency is extracted as a second output, through a low pass filter having a large time constant. A predetermined operation, such as addition, zero correction, response correction, etc, is carried out on the first and second outputs to produce a flow rate output. The invention has quick response, stable zero point and reduced susceptibility to noises.

Electromagnetic flow meter

In an electromagnetic flow meter converter comprising a deviation amplifier for amplifying the deviation between a feedback signal and an input signal from a flow rate detector, and a converter circuit for converting the amplified output of the deviation amplifier into a frequency signal, the improvement comprising a frequency divider for frequency dividing the frequency signal, a digital setting unit for setting the frequency dividing factor of the frequency divider, and a multiplier for multiplying the output of the frequency divider by a comparison voltage which is proportional to the current applied to the coil of the flow rate detector to provide the feedback signal, whereby the span is set digitally and whereby the compatibility between the converter and the flow rate detector is obtained by setting the product of the meter constant of the flow rate detector and a predetermined maximum flow velocity. A second embodiment uses an oscillator, frequency dividers and multipliers to adjust and expand the range of zero adjustment to a value lower than 0% and to prevent mutual interference between the zero adjustment and span adjustment.

Electromagnetic flow meter converter

A signal generator for reducing the influence of fluctuations in flow rate distribution in a fluid passing through the flow tube of an electromagnetic flowmeter, which fluid intercepts a magnetic field therein to induce an emf which is transferred to the meter electrodes, thereby yielding a signal as a function of flow rate. To this end, the tube is provided with auxiliary electrodes disposed at arbitrary positions at which the potentials developed thereon are equal to each other when the existing flow rate distribution is symmetrical with respect to the flow tube axis, the auxiliary electrodes being interconnected.

Signal generator for electromagnetic flowmeter

A ratio meter adapted to determine the ratio of a first input signal representing the difference between two input voltages and a second signal representing the sum of both input voltages.

Ratio meter for capacitive-type displacement converter

An electromagnetic flowmeter in which a low-frequency rectangular wave is supplied to the electromagnet coil of the flowmeter to produce an excitation current establishing a magnetic field which is intercepted by the fluid passing through the flow tube to induce a signal voltage in the electrodes disposed in the tube. This signal voltage is proportional to flow rate and is accompanied by an objectionable D-C noise component. To eliminate this noise component, the signal voltage is passed through a first high-pass filter, and to compensate for errors introduced by this filter, the signal voltage derived from the first filter is divided by a comparison voltage derived from the excitation current, but only after this comparison voltage passes through a second high-pass filter having essentially the same characteristics as the first filter.

Electromagnetic flowmeter with noise compensation

A resistance-to-current converter in which a sensing resistor, such as a resistance thermometer bulb for sensing changes in temperature, forms an arm in a resistance bridge which is periodically excited by a switching circuit interposed between a power supply and the input junctions of the bridge. The voltage produced at the output junctions of the bridge during the 'on' and 'off' excitation states are separately detected. The detected signal obtained in the 'off' state is subtracted from that obtained in the 'on' state to produce an output signal from which there is eliminated the error component resulting from a leakage resistance path coupled to said sensing resistor.

Resistance-to-current converter

A magnetic current meter adapted to sense the flow of liquid through an open channel to produce a mean flow velocity signal that is independent of fluctuations in the level of liquid in the channel. The meter includes a tube of insulation material so positioned in the channel that its longitudinal axis is normal to the direction of flow. Disposed in the tube is a rod having a coil wound thereon, the coil being excited by a low-frequency alternating current to produce an external magnetic field. A pair of electrodes are mounted on opposite sides of the tube on the outer surface thereof whereby the flow of liquid which intercepts the external field induces a voltage signal in the electrodes proportional to the mean flow velocity. The height of the meter exceeds the depth of the channel and is higher, therefore, than the liquid level regardless of fluctuations therein.

Magnetic current meter for open channel flow measurement

A Karman vortex flowmeter in which the fluid to be metered is conducted through a flow tube having a relatively large diameter. A multiplicity of rod-like units are arranged in parallel relation across the tube to define an obstacle array. Each unit acts as a vortex shedder and is constituted by rod sections which are coupled together axially by flow-detecting probes. Each probe in the array is so located as to avoid mutual interaction with the other probes. The electrical signals derived from the probes are so weighted and averaged as to obtain an output giving the mean flow rate. Even when the flowmeter is installed in a flow line containing elbows and other profile-disturbing elements, precise flow measurement can be accomplished.

Growing community of inventors

Yokohama, Japan

Tamotsu Kobayashi