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Improvement to Ready-Mix Drum Internal Load Cell Sensor

IP.com Disclosure Number: IPCOM000250059D
Publication Date: 2017-May-24
Document File: 6 page(s) / 299K

Publishing Venue

The IP.com Prior Art Database

Abstract

A ready-mix drum internal sensor that measures load or pressure needs to be heavy duty due to the magnitude of the load and because the parts in contact with the concrete are subject to wear. The self-weight of the sensor may affect the reading when very fluid concrete is in the drum. This document describes three concepts or functions that improve the performance of the load sensor: Auto-Zero function, Weight Compensation function, and Wear function.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 23% of the total text.

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Improvement to Ready-Mix Drum Internal Load Cell Sensor

Abstract:

A ready-mix drum internal sensor that measures load or pressure needs to be heavy

duty due to the magnitude of the load and because the parts in contact with the concrete are

subject to wear. The self-weight of the sensor may affect the reading when very fluid concrete

is in the drum. This document describes three concepts or functions that improve the

performance of the load sensor: Auto-Zero function, Weight Compensation function, and

Wear function.

Keywords:

 Ready-mix

 Workability sensor

 Probe

 Load cell

 Weight compensation

 Wear

 Auto-Zero

 Reset

Introduction:

One of the first internal sensors that was used in a ready-mix drum was described in

1975 by Garrison (United States Patent No. 3,924,447). Since that time, there have been very

few sensors that have been developed (e.g., Sensocrete, IBB, etc.). Modern sensors have a

load cell that measures the force, sometimes expressed as pressure. The load cell of such

sensors should be very sturdy because of the aggressive environment: the repetitive contact

of the aggregate on the sensor wears out the sensor. The range of the loads to be measured

vary by some two orders of magnitude. Therefore, the sensor should be precise and contain

some built–in functions to keep it working properly.

This document explains the working logic of the load cell that is a main feature of the

workability probe described in Canadian Patent No. CA2771589. The workability probe load

cell, like any scale, has an automatic reset function that allows for taring the scale. In this

document, this is referred to as “Auto-Zero function.”

The best position for the sensor to be in to make this automatic reset is in the top

position where the sensor is out of the concrete and where the gravity effect of the part of

the sensor usually in contact with the concrete is at a minimum. The load cell must be linked

with a processor and a position sensor, usually an accelerometer that allows for determining

the position and rotation of the drum.

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The probe is composed of an inside cylinder that includes the load cell and an outside

cylinder that is in contact with the concrete. The outside cylinder is linked by “hinges”

(described in United States Patent Application No. 62/381721) that allow the outside cylinder

to rotate and a ‘’ball joint’’ feature that transfers the load from the concrete.

When the drum of the truck is empty and the probe moves, the outer tube can put

some pressure on the load cell because of the weight of the outer tube. To compensate for

the weight of the tube, a “Weight Compensation function” has been created in such a way

that the pressure indicated by the load cell is near zero for any position of the drum using a

sinusoidal function.

With time, the outer tube will wear slightly as it passes through the concrete; the wear

is proportional to the distance travelled through the concrete and by the pressure applied on

the probe. More pr...