Data processing: generic control systems or specific application – Specific application – apparatus or process – Mechanical control system
Reexamination Certificate
1998-03-13
2001-11-13
Grant, William (Department: 2121)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Mechanical control system
C702S045000, C177S016000
Reexamination Certificate
active
06317656
ABSTRACT:
RELATED APPLICATIONS
FIELD OF THE INVENTION
The present invention generally relates to an apparatus and a method of generating flow rates for displaceable materials in a displacement system using conveyor belt, augers, bucket elevators, horizontal screws dedicated pneumatic conveyors, and the like, by utilizing the power demand of the prime mover of the system to provide the flow rate data of the material being displaced.
BACKGROUND OF THE INVENTION
Prior art methods of measuring displaceable material, such conveyed crushed rock, coal, feed, etc, augered material such as powder, seeds, cement, etc, and liquid material such as water, oil, etc, are limited to conveyor belt and gravimetric scales which are calibrated to read in unit weight per unit time, or liquid flow rate meters reading in units of liquid measure per unit time, etc. The prior art methods strive for accuracy through sophisticated electronic components in precision electro-mechanical interaction, such as conveyor scales with electronic load cells, sensing physical movement in relation to the amount of material on the conveyor scale, or rotary impellers coupled to a sensor for liquids, or electronic physical displacement sensors mechanically coupled to an impacting surface measuring the rate of material flowing through a pipe, etc, resulting in the desired unit of measurement.
Prior art conveyor belt scales typically consists of a scale carriage with load cells and/or linear differential transformers and associated electronic circuits, a conveyor motion or speed sensor, and several idlers before and after the scale carriage. Installation of a conveyor belt scale generally requires mechanics and welders to mount the scale to the conveyor frame, electrician to run conduit and wires from the main panel in the control room to the scale, and trained factory technicians to inspect and configure the scale to the specific application. Thus, the installation process can be quite involved, including significant installation work, lengthy field wire runs conveyor, frame modification, weigh bridge installation, mechanical line-up for accuracy, additional sensor mounting and associated wires for conveyor speed, etc.
Conventional belt scales require almost constant calibration and trimming to account for variations in material density, conveyor belt carriage alignment, conveyor belt centering, wedged rocks in-between the scale measuring beams, etc., to obtain material flow rate data within the error tolerance of the scales. Maintenance personnel would need basic understanding of the conveyor belt system, scale carriage, load cell, speed sensor, electronics associated, etc., in addition to being familiar with voluminous user manuals. Thus, prior art systems are sophisticated electro-mechanical systems requiring highly trained personnel for installation and maintenance.
There is therefore a need for flow rate monitor that replaces complicated belt scales and requires no expertise on conveyor scales and their associated load cells, linear voltage differential transformers, scale beams, etc. and minimizes a large portion of the installation headaches that generally accompany the industrial belt scales.
There is therefore a need for flow rate monitor that compensated for the zero drift caused by mechanical components warm-up, changes in the ambient temperature and seasonal changes.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide a rate monitor for displaceable materials that involves no electronic load cells, linear voltage differential transformers (LDT), etc, mechanical impellers, switches, nor any kind of electro-mechanical interaction.
It is still another object of the present invention to provide a rate monitor for conveyed materials that eliminates the use of scale carriages fitted into the conveying system.
It is still another object of the present invention to provide a rate monitor for conveyed materials that eliminates the need for conveyor frame modification or the need to cut into a pressurized pipe to bolt a flow sensor or gravimetric scale.
It is yet another object of the present invention to provide a rate monitor for conveyed materials that eliminates running lengthy field wiring for system power or for signal cables back to the main control room.
It is another object of the present invention to provide a rate monitor that minimizes the concern with a conveyor angle of inclination which would interfere with scale accuracy or the minimum number of idlers before and after the typical conveyor scale installation.
It is still another object of the present invention to provide a rate monitor for conveyed materials that eliminates mechanical motion sensors.
It is yet another object of the present invention to provide a rate monitor for conveyed materials that provides system overburden/overload alarm.
It is still another object of the present invention to provide a rate monitor for conveyed materials that compensates for zero drift during operation with or without user intervention to maintain flow rate accuracy.
It is another object of the present invention to provide a rate monitor that is relatively easy to install, thereby minimizing the installation-intensive problems associated with prior art belt scales.
In summary, the present invention provides a flow rate monitor for indicating the amount of material being conveyed in a conveying system having a prime mover, comprising a power demand monitor for being operably connected to the prime mover; a programmable controller operably connected to the power demand monitor, the controller being adapted to convert the data from the power demand monitor and convert it to flow rate data using a linear relationship between the power demand of the prime mover and the flow rate of the material; and an indicator for indicating the flow rate of the material.
The present invention also provides a method for measuring the amount of material being displaced in any displacement system with an electric motor as a prime mover, in a substantially linear region of operation where the power demand of the prime mover is linearly related to the flow rate of the material, comprising the steps of establishing a linear equation relating the flow rate to the power demand by measuring the power demand of the prime mover when the displacement system is running empty to obtain the system-no-load power demand, and measuring the power demand of the prime mover when the displacement system is loaded with a known amount of material to obtain an actual flow rate corresponding to the power demand under load; monitoring the power demand of the prime mover; and calculating and displaying the flow rate of the material being conveyed from the monitored power demand and the linear equation.
In a system where the power demand is not linearly related to the flow rate of the material, the power demand is approximated by a series of linear zones whereby the flow rate is linearly related to the power demand in each zone.
These and other objects of the present invention will become apparent from the following detailed description.
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Garland Steven R.
Grant William
Shlesinger & Arkwright & Garvey LLP
Tecnetics Industries Inc.
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