Grain Cleaning Airflow Control Using Ultrasonic Phase Shifts
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Solution Overview
Problem
Existing grain cleaning systems in combine harvesters rely on fan speed setpoints for control algorithms, which may not accurately represent the actual airflow conditions, leading to inefficiencies due to variations in material volume and airflow modification within the cleaning system.
Innovation Solution
The system determines the speed and direction of the cleaning airstream using phase shift measurements between transmitted and modified acoustic signals, employing ultrasonic transmitters and receivers to calculate airstream velocity, which is used as an input for controlling fan speed and sieve adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If fan speed setpoint is used as control algorithm input, then control system can operate, but airflow representation accuracy deteriorates due to material volume variations modifying airflow
Solution Approach 1:
The patent replaces the mechanical/fan-based airflow generation system with an acoustic measurement system. Ultrasonic transmitters send acoustic signals through the airstream, and receivers detect the modified signals to calculate actual airflow velocity using phase shift measurements. This substitution eliminates the need to rely on fan speed setpoints as proxies for actual airflow conditions.
Solution Approach 2:
The patent introduces acoustic signals as an intermediary to measure airflow conditions. Instead of directly measuring airflow velocity (which is difficult), the system uses acoustic waves as a mediator that can propagate through the airstream and have their phase shift measured, providing an indirect but accurate representation of actual airflow conditions.
2Productivity
If material volume in cleaning system increases, then more grain can be processed, but airflow velocity through duct decreases
Solution Approach 1:
The patent implements a feedback control system that continuously measures actual airflow velocity using acoustic signals and adjusts fan speed accordingly. The phase shift measurements provide real-time feedback on airflow conditions, allowing the control algorithm to compensate for variations in material volume and maintain optimal airflow velocity despite changes in processing capacity.
Solution Approach 2:
The patent makes the fan speed dynamic rather than static. The fan speed setpoint is continuously adjusted based on real-time airflow measurements from the acoustic sensing system. This dynamic adjustment allows the system to maintain optimal airflow velocity regardless of variations in material volume or processing conditions.
3Measurement precision
If ultrasonic sensing device is positioned in cleaning airstream path, then accurate airflow measurement is achieved, but device complexity increases
Solution Approach 1:
The patent makes the ultrasonic sensing device multi-functional by integrating both transmitter and receiver components into a single unit that can perform multiple measurement tasks. The same device measures both the speed and direction of the airstream, and can be positioned at different locations to provide comprehensive airflow characterization without requiring multiple separate sensing systems.
Solution Approach 2:
The patent measures airflow in multiple dimensions by positioning the sensing device to detect both the speed and direction of the airstream. The phase shift measurements provide information about airflow velocity in the longitudinal direction, while additional measurements can characterize airflow in other dimensions, providing a comprehensive three-dimensional understanding of airflow conditions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides an accurate representation of airflow conditions, optimizing grain cleaning efficiency by adjusting fan speed and sieve settings to enhance separation and reduce grain loss.
Implementation Method 1
the speed or velocity of the airstream itself is determined using measurement of phase shift between a transmitted acoustic signal and a portion of the transmitted signal that is modified by the airstream
Data Source
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AI summary
An ultrasonic sensing device (55) has a transmitter (T2) which is adapted to transmit a base signal (SB2) through a cleaning airstream in a grain cleaning system (30). The base signal (SB2) is modified by movement of the cleaning airstream creating a modified signal (SM1,SM2) that is detected by spaced-apart receivers (R1,R2). An electronic control unit (ECU) is configured to process the received modified signals (SM1,SM2) and determine a phase shift vale (ϕ1,ϕ2) from a base signal parameter and a modified signal parameter. The phase shift value is used as an input parameter for the generation of an airstream velocity value (Va) and control signals for the adjustment of various working units of a combine (10) including, by way of example, a fan (34) and sieves (38,39).