# US 11,029,196 B2 · Vibration sensor for fluid leak detection

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- Number: US 11,029,196 B2
- Document ID: US11029196B2
- Status: Granted
- Kind: B2
- Application number: 16/341,475
- Filed: 2017-10-13
- Published: 2020-03-05
- Granted: 2021-06-08
- Earliest claimed: 2016-10-13
- Assignees: South East Water Corporation
- Applicants: South East Water Corporation
- Inventors: Andrew Forster-Knight; Juan Londono; Eddy Mofardin; Ninad Mohan Dharmadhikari; Jonathan Philip Crook; Matthew Swan; Colin Neil Gehrig; Thomas James Merry; Owen David Neeson; Joseph Ignatius Maria Van Der Plas
- Web page: https://patentgrep.com/patent/US11029196B2

## CPC

- G01H 11/08: using piezoelectric devices
- E03B 7/078: {Combined units with different devices; Arrangement of different devices with respect to each other}
- G01M 3/243: {for pipes}
- G01M 3/28: for pipes, cables or tubes; for pipe joints or seals; for valves {; for welds}
- E03B 7/072: {Arrangement of flowmeters}
- G01F 1/05: by using mechanical effects
- G01F 1/58: by electromagnetic flowmeters
- G01F 1/66: by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters
- G01H: MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- E03B: INSTALLATIONS OR METHODS FOR OBTAINING, COLLECTING, OR DISTRIBUTING WATER (drilling wells, obtaining fluids in general from wells E21B; pipe-line systems in general F17D)
- G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01F: MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME

## Abstract

Some embodiments relate to a vibration sensor. The vibration sensor comprises: a sensor base to couple to a vibration source; a piezoelectric transducer coupled on a first side of the transducer to the sensor base; at least one conductor coupled to the piezoelectric transducer; and a seismic weight positioned on a second side of the piezoelectric transducer; wherein the sensor base, the piezoelectric transducer and the seismic weight are aligned along an axis and arranged so that relative movement between the sensor base and the seismic weight arising from the vibration source causes a current to be generated in the piezoelectric transducer and an output signal corresponding to the generated current is detectable on the at least one conductor.

## Claims

### Claim 1

A vibration sensor, comprising:
a sensor base to couple to a vibration source;
a piezoelectric transducer coupled on a first side of the transducer to the sensor base;
at least one conductor coupled to the piezoelectric transducer; and
a seismic weight defining a cavity into which the piezoelectric transducer is partly disposed such that the seismic weight is positioned on a second side of the piezoelectric transducer;
wherein the sensor base, the piezoelectric transducer and the seismic weight are aligned along an axis and arranged so that relative movement between the sensor base and the seismic weight arising from the vibration source, including small compressions and bending moments arising from vibrations transmitted through the sensor base, causes a current to be generated in the piezoelectric transducer and an output signal corresponding to the generated current is detectable on the at least one conductor.

### Claim 2 (depends on 1)

The sensor of claim 1, further comprising a compression component arranged to bias the seismic weight toward the sensor base.

### Claim 3 (depends on 2)

The sensor of claim 2, wherein the compression component comprises a spring.

### Claim 4 (depends on 3)

The sensor of claim 3, wherein the spring comprises a coil spring, a wave spring or leaf spring.

### Claim 5 (depends on 3)

The sensor of claim 3, wherein one end of the spring is coupled to the sensor base and an opposite end of the spring is coupled to the seismic weight.

### Claim 6 (depends on 3)

The sensor of claim 3, wherein the spring is disposed on a side of the seismic weight opposite to the sensor base and is arranged to have a first end of the spring bear on a bearing surface of the sensor and to have a second end of the spring bear on the seismic weight.

### Claim 7 (depends on 3)

The sensor of claim 3, wherein a spring constant of the spring is between about 1 N/mm and about 15 N/mm.

### Claim 8 (depends on 1)

The sensor of claim 1, wherein, in a rest state of the sensor, the piezoelectric transducer is compressed between the sensor base and the seismic weight.

### Claim 9 (depends on 1)

The sensor of claim 1, wherein the piezoelectric transducer is formed as a column transducer.

### Claim 10 (depends on 1)

The sensor of claim 1, further comprising a housing to cover the seismic weight and the piezoelectric transducer.

### Claim 11 (depends on 10)

The sensor of claim 10, wherein the housing and the sensor base define a chamber within which the seismic weight has limited freedom to move.

### Claim 12 (depends on 1)

The sensor of claim 1, further comprising an electronic interface coupled to the at least one conductor and arranged to communicate with an external controller.

### Claim 13 (depends on 12)

The sensor of claim 12, wherein the sensor is reliant on supply of power from an external device for operation of the electronic interface.

### Claim 14 (depends on 12)

The sensor of claim 12, wherein the electronic interface is configured to process input signals based on the output signal received via the at least one conductor to determine a fast Fourier transform (FFT) of the input signals.

### Claim 15 (depends on 14)

The sensor of claim 14, wherein the electronic interface is configured to amplify and filter the output-signal and perform an analogue-to-digital conversion of the amplified and filtered output signal in order to generate the input signals.

### Claim 16 (depends on 14)

The sensor of claim 14, wherein the electronic interface is configured to perform a comparison of at least one frequency-specific threshold against at least one section of a frequency spectrum of the FFT and to set a detection flag when the comparison indicates that an amplitude of the frequency spectrum in the at least one section exceeds the respective at least one frequency-spectrum threshold.

### Claim 17 (depends on 16)

The sensor of claim 16, wherein the detection flag is communicated to the external controller to indicate detection of a predetermined condition.

### Claim 18 (depends on 16)

The sensor of claim 16, wherein the comparison is performed multiple times for different frequency-specific thresholds and respective different sections of the frequency spectrum to set or not set at least one detection flag based on the multiple comparisons.

### Claim 19 (depends on 16)

The sensor of claim 16, wherein the frequency spectrum is between 0 and 1000 Hz.

### Claim 20 (depends on 12)

The sensor of claim 12, wherein the electronic interface is configured to sample the output signal for a short time period in response to an operation signal received from the external controller.

### Claim 21 (depends on 20)

The sensor of claim 20, wherein the short time period is between 0.05 seconds and 1.0 second.

### Claim 22 (depends on 21)

The sensor of claim 21, wherein the short time period is between 0.05 seconds and 0.2 seconds.

### Claim 23 (depends on 20)

The sensor of claim 20, wherein the electronic interface is configured to periodically sample the output signal multiple times over an extended time period.

### Claim 24 (depends on 14)

The sensor of claim 14, wherein the electronic interface comprises a microcontroller to process the input signals and determine the FFT.

### Claim 25 (depends on 24)

The sensor of claim 24, wherein the microcontroller is responsive to provision of power and an operation signal from the external controller to receive and process the input signals.

### Claim 26 (depends on 1)

The sensor of claim 1, wherein the at least one conductor comprises a first conductor coupled to a first end of the piezoelectric transducer and a second conductor coupled to an opposite second end of the piezoelectric transducer, wherein the output signal is detectable on the first and second conductors.

### Claim 27 (depends on 1)

The sensor of claim 1, wherein the seismic weight has a mass of between about 20 grams and about 250 grams.

### Claim 28 (depends on 1)

The sensor of claim 1, wherein the seismic weight is axi-symmetric about the axis.

### Claim 29 (depends on 1)

The sensor of claim 1, wherein the seismic weight can angularly tilt relative to the sensor base.

### Claim 30 (depends on 1)

The sensor of claim 1, wherein there is a gap between an inner wall defining the cavity and an outer surface of the piezoelectric transducer.