Spray Bar Pressure Equalization for Non-Planar Topography
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Solution Overview
Problem
Conventional spray bars used in agricultural fields with non-planar topography experience pressure differences between nozzles due to height variations, leading to uneven liquid distribution and growth irregularities, exceeding the 10% volume gap requirement in some standards.
Innovation Solution
A device with sensors and control units that measure pressure differences and adjust the pressure within each duct using flow restricting members, such as needle regulators or solenoid valves, to equalize flow rates between nozzles, ensuring uniform liquid distribution across the field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the bar is adjusted to follow non-planar topography with raised areas, then the nozzles can reach different heights on the field, but pressure differences are created between nozzles causing uneven liquid distribution
Solution Approach 1:
The patent applies local quality by equipping each duct with its own pressure sensor and flow restricting member, allowing individual pressure compensation for each nozzle based on its specific altitude. This enables the system to adapt to non-planar topography while maintaining uniform liquid distribution, as each local segment can be independently regulated despite overall bar elevation changes.
2Manufacturing precision
If flow restricting members are added to equalize pressures, then uniform liquid distribution is achieved, but device complexity increases
Solution Approach 1:
The patent segments the bar into multiple independent ducts, each equipped with its own pressure sensor and flow restricting member. This segmentation allows distributed pressure compensation without requiring a centralized control system, reducing overall device complexity while achieving uniform liquid distribution. Each segment operates autonomously based on local pressure measurements.
3Productivity
If the bar moves at higher speed, then productivity increases, but pressure differences due to hydrostatic head become more significant
Solution Approach 1:
The patent implements feedback control by continuously monitoring pressure at each duct through pressure sensors and adjusting the flow restricting members accordingly. This closed-loop system compensates for pressure differences caused by high-speed movement and hydrostatic head, maintaining consistent flow rates even at elevated spraying speeds, thus preserving productivity without sacrificing flow uniformity.
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
The solution limits pressure differences to less than 5%, resulting in uniform liquid application and minimizing growth differences between plants, meeting stringent volume gap requirements.
Implementation Method 1
The flow rate of the nozzle being proportional to the square root of the pressure, the flow rate of liquid product differs on each nozzle, such that the liquid product is not uniformly sprayed on each surface unit. For example, in the case of a conventional rectilinear bar 36 m long moving over an 11% banking to spray a liquid fertilizer with a density of 1.32 at an average pressure of 1.5 bars, the nozzle situated at the lower end of the bar withdraws 18% more liquid fertilizer than the nozzle situated at the upper end of the bar, since the height difference of 3.9 m causes a difference between hydrostatic pressures at those nozzles
Implementation Method 2
several members designed to vary the pressures inside the respective ducts, each member being in fluid communication with at least one inlet port; and at least one control unit interconnected with the sensors so as to estimate the pressure differences between at least two ducts, said control unit being interconnected with the members so as to drive them to reduce said pressure differences or equalize said pressures
Data Source
AI summary
The device according to the invention comprises a bar that includes several consecutive ducts with at least one inlet connected to a source of the liquid product and outlets communicating with nozzles. The device further comprises several sensors for measuring a physical property making it possible to determine a pressure difference between ducts or a pressure in one respective duct, several members designed to vary the pressures inside respective ducts, as well as at least one control unit estimating the pressure differences between ducts and driving the members to reduce those pressure differences or equalize those pressures. This device thus limits the pressure differences, and therefore flow differences, of the liquid product between the nozzles, in particular between the ends of very long bars moving over significant bankings.