Walk-Behind Equipment Variable Speed Control with Adjustable Acceleration Profiles
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Solution Overview
Problem
Current variable speed control systems for walk-behind working machines, such as lawnmowers, require operators to adjust maximum speed and acceleration by releasing one hand, compromising control of the machine, and do not allow for user-preferred acceleration rates.
Innovation Solution
A variable speed control system with a control lever and actuators that allow for adjustment of maximum speed and acceleration without releasing the handle, using a control unit to manage the machine's speed and acceleration profiles, enabling comfortable operation and user-defined settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If mechanical lever or rotary knob is used for adjusting maximum speed, then speed adjustment is possible, but operator control is reduced when adjusting
Solution Approach 1:
The patent replaces traditional mechanical adjustment mechanisms (levers, rotary knobs) with an electronic control system. The electronic system uses buttons or touch-sensitive inputs that can be operated with the thumb while the operator's hand remains on the handle, eliminating the need to release the handle for adjustments. This substitution of mechanical with electronic control resolves the contradiction by enabling speed adjustment without compromising operator control.
2Productivity
If acceleration is fixed or manually controlled, then system simplicity is maintained, but performance is compromised
Solution Approach 1:
The control system automatically manages acceleration by incorporating an acceleration profile feature that self-adjusts the rate of acceleration based on operating conditions. The system monitors the machine's state and automatically applies appropriate acceleration rates without requiring manual intervention from the operator. This self-service approach improves acceleration performance while maintaining reasonable system complexity through automated control algorithms.
Solution Approach 2:
The patent implements variable acceleration profiles that dynamically change acceleration parameters based on operating conditions. The control system can select from multiple acceleration rates (e.g., aggressive, moderate, gentle) and automatically adjusts these parameters to optimize performance for different situations such as grass type, terrain, and load conditions. This parameter variability enhances productivity while the automated selection keeps device complexity manageable.
3Speed
If quick acceleration is provided, then responsiveness is improved, but grass damage occurs
Solution Approach 1:
The control system dynamically adjusts acceleration parameters to prevent grass damage. It incorporates acceleration profiles that limit the maximum acceleration rate to prevent drive wheels from spinning excessively, which would damage the grass. The system can adaptively change acceleration parameters based on detected conditions, providing responsive acceleration when appropriate while preventing harmful wheel spin on sensitive surfaces.
Solution Approach 2:
The system uses feedback mechanisms to monitor operating conditions and adjust acceleration accordingly. Sensors detect wheel slip, grass resistance, and machine load, and this feedback is used by the control unit to modulate acceleration in real-time. When wheel spin is detected or predicted, the system reduces acceleration rate to prevent grass damage, while still maintaining responsive acceleration under normal conditions.
Data Source
AI summary
The present subject matter relates to adjustable ground speed control devices, systems, and methods for walk-behind equipment. A variable speed control system may include a control system base, a control lever selectively movable with respect to the control system base between a first operating position and a second operating position, a mode actuator positioned on the control system base for toggling between a standard mode and a selection mode, and an adjustment actuator positioned on the control system base in communication with a control unit to toggle between a first control mode and a second control mode when the mode actuator is in selection mode. The control unit applies a first acceleration profile to accelerate from the minimum operating speed to the variable maximum operating speed when in the first control mode and a second acceleration profile when in the second control mode.