Field Sprayer PWM Valve Phasing for Lower Pressure Pulsation
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Solution Overview
Problem
Field spraying devices face challenges in efficiently controlling application rates and reducing pressure pulsations due to simultaneous start-up of electronically controlled field spray valves, leading to increased demands on pressure regulation and potential irregularities in application behavior.
Innovation Solution
Implementing a method where at least two field spray valves are operated with a predetermined phase offset in the start of their pulse width modulation periods, allowing for controlled changes in application rates by adjusting the duty cycle or frequency of pulse width modulation, while synchronizing timers to maintain consistent operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If field spray valves are operated simultaneously with pulse width modulation, then the application rate can be changed efficiently, but pressure pulsations occur and demand on pressure regulation increases
Solution Approach 1:
The patent applies periodic action by using pulse width modulation (PWM) to operate field spray valves in a periodic manner rather than continuously. The valves are opened and closed in periodic cycles with varying duty cycles to achieve desired application rates while avoiding simultaneous operation of all valves, thereby reducing pressure pulsations in the fluid supply system.
Solution Approach 2:
The control unit预先 determines and coordinates the operation timing of multiple field spray valves to prevent simultaneous start-up. By planning the valve operation sequences in advance and introducing phase offsets, the system avoids sudden pressure demands that would occur if all valves opened at the same time, thus reducing pressure pulsations before they can affect the supply system.
2Device complexity
If field spray valves are operated simultaneously, then the system structure is simple, but irregularities in application behavior occur
Solution Approach 1:
The patent introduces dynamic control by varying the duty cycle and frequency of pulse width modulation for different field spray valves based on their position and operational requirements. The control unit dynamically adjusts opening times and durations for individual valves, ensuring consistent application behavior across the spray bar while maintaining a relatively simple overall system structure.
3Quantity of substance
If duty cycle is increased to raise application rate, then more fluid is applied, but power consumption increases
Solution Approach 1:
The patent employs parameter changes by adjusting both the duty cycle and frequency of pulse width modulation to control application rates. By optimizing these parameters, the system achieves desired fluid application rates while minimizing power consumption - for example, using higher frequencies with lower duty cycles or lower frequencies with appropriately tuned duty cycles to reduce overall energy demand while maintaining effective spray coverage.
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 reduces pressure pulsations and improves application behavior by smoothing the sudden changes in volume flow, enabling precise control over application rates and reducing power consumption through optimized phase offset and synchronization techniques.
Implementation Method 1
The valve body can be held in the closed position using a holding magnet. A holding magnet is understood to mean an electromagnet in which no mechanical movement takes place.
Implementation Method 2
The electromagnetic actuators are formed with a coil and an armature that moves inside the coil, the movable armature being coupled to the valve body. The electromagnetic actuator must generate an opening force that depends on the size of the valve plate and the pressure difference between a primary line and a secondary line of the field spray valve
Data Source
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AI summary
The invention relates to a method for operating a field sprayer. The field sprayer has several electronically controlled spray valves, each operated by means of pulse width modulation. In the method, at least two spray valves are operated with a predetermined phase offset in the start of the pulse width modulation periods, thereby reducing pressure pulsations in the fluidic system. The application rate of the spray valves is influenced, firstly, by changing the duty cycle of the pulse width modulation. Secondly, the application rate is influenced by changing the frequency of the pulse width modulation.