Dynamic vehicle-weighing system
First Claim
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1. An electronic system for weighing vehicles, comprising;
- at least one sensor section arranged to receive pressure force from an object such as a vehicle including at least one weight sensor, said weight sensor including a layer of piezoelectric material disposed between two electrodes, said weight sensor arranged to output a charge signal to a charge signal output in response to pressure applied thereto; and
means for converting said charge signal to a weight value according to the relationship
space="preserve" listing-type="equation">weight=q/d.sub.33, where q is said charge signal and d33 is the thickness sensitivity of said piezoelectric material, said means for converting charge to weight including means for converting said charge signal to a voltage signal, means for detecting the peak voltage of said voltage signal, and means for converting said peak voltage to a weight value.
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Abstract
A system for weighing a vehicle in motion is disclosed. One or more piezoelectric weight sensors produce charge outputs in response to the weight of a vehicle passing over the sensors. A charge amplifier converts the sensor outputs to a voltage level. A peak voltage detector detects the peak voltage, which represents the sum of all sensor outputs. The peak voltage is then converted to a weight value using the thickness sensitivity of the piezoelectric material.
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Citations
10 Claims
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1. An electronic system for weighing vehicles, comprising;
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at least one sensor section arranged to receive pressure force from an object such as a vehicle including at least one weight sensor, said weight sensor including a layer of piezoelectric material disposed between two electrodes, said weight sensor arranged to output a charge signal to a charge signal output in response to pressure applied thereto; and means for converting said charge signal to a weight value according to the relationship
space="preserve" listing-type="equation">weight=q/d.sub.33,where q is said charge signal and d33 is the thickness sensitivity of said piezoelectric material, said means for converting charge to weight including means for converting said charge signal to a voltage signal, means for detecting the peak voltage of said voltage signal, and means for converting said peak voltage to a weight value. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An electronic system for weighing vehicles, comprising:
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a plurality of sensor sections arranged to receive pressure force from an object such as a vehicle, each said sensor section including a plurality of weight sensors, each said weight sensor including a layer of piezoelectric material disposed between two electrodes such that each said weight sensor produces a charge signal in response to pressure applied thereto, each said weight sensor being electrically connected in parallel with one another to produce a total charge signal representing the sum of all said charge signals from said weight sensors at a common charge signal output;
said weight sensors encapsulated in resilient encapsulating material; andmeans for converting said charge signal to a weight value according to the relationship
space="preserve" listing-type="equation">weight=q/d.sub.33,where q is said total charge signal and d33 is the thickness sensitivity of said piezoelectric material, said means for converting charge to weight including a charge amplifier for converting said total charge signal to a voltage signal, means for detecting the peak voltage of said voltage signal, and means for converting said peak voltage to a weight value.
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9. A method for weighing a vehicle, comprising the steps of:
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providing a weighing device including a weight sensor having a layer of piezoelectric material disposed between two electrodes such that said weight sensor produces a charge signal at a charge signal output in response to pressure applied thereto, and locating said weight sensor so that it can be traversed by a wheel of a vehicle; traversing said weighing device with a vehicle to produce a charge signal at said charge signal output; and converting said charge signal to a weight value according to the relationship
space="preserve" listing-type="equation">weight=q/d.sub.33,where q is said charge signal, and d33 is the thickness sensitivity of said piezoelectric material, said means for converting charge to weight including means for converting said charge signal to a voltage signal, means for detecting the peak voltage of said voltage signal, and means for converting said peak voltage to a weight value.
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10. A method for weighing a vehicle, comprising the steps of:
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providing a weighing device including a plurality of weight sensors each having a layer of piezoelectric material disposed between two electrodes such that each said weight sensor produces a charge signal in response to pressure applied thereto, said weight sensors being electrically connected in parallel with one another to produce a total charge signal representing the sum of all said charge signals from said weight sensors at a common charge signal output, and locating said weight sensors so that they can be traversed by the wheels of a vehicle; traversing said weighing device with a vehicle to produce a total charge signal at said charge signal output; and converting said total charge signal to a weight value according to the relationship
space="preserve" listing-type="equation">weight=q/d.sub.33,where q is said total charge signal, and d33 is the thickness sensitivity of said piezoelectric material, said means for converting charge to weight including means for converting said total charge signal to a voltage signal, means for detecting the peak voltage of said voltage signal, and means for converting said peak voltage to a weight value.
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Specification