Variable Speed Control Lever for Walk-Behind Equipment
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Solution Overview
Problem
Current variable speed control systems for walk-behind working machines, such as lawnmowers, require operators to release one hand to adjust maximum speed settings, compromising control, and acceleration rates are either fixed or user-dependent, leading to potential damage or frustration.
Innovation Solution
A variable speed control system featuring a control lever and mode actuator that allows operators to adjust speed and acceleration without releasing the handle, using a control unit to manage the machine component's operation between minimum and variable maximum speeds, with different acceleration profiles based on selected modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a mechanical lever or rotary knob is used to adjust maximum speed setting, then the maximum speed can be adjusted, but the operator must release one hand from the control handle, compromising control
Solution Approach 1:
The patent combines the maximum speed adjustment function with the existing control handle assembly by integrating an adjustable maximum speed setting mechanism that can be operated while maintaining grip on the handle. This merging of functions allows the operator to adjust speed without releasing the handle, resolving the contradiction between adjustability and control.
Solution Approach 2:
The patent introduces an intermediary mechanism (such as a selectable range mechanism or electronic control interface) that mediates between the operator's hand on the handle and the speed adjustment function. This intermediary allows adjustment to be made through the existing control interface without requiring hand release, maintaining both control and adjustability.
2Device complexity
If acceleration rate is fixed in the drive system, then the system is simple to control, but the acceleration may be too quick causing damage to grass or too slow causing user frustration
Solution Approach 1:
The patent implements a dynamic acceleration control system where the acceleration rate is no longer fixed but can be selectively adjusted based on operating conditions. The control system provides multiple selectable acceleration profiles or rates that adapt to different mowing conditions, terrain, and user preferences, resolving the contradiction between simplicity and adaptability.
Solution Approach 2:
The patent changes the acceleration parameter from a fixed value to a variable parameter that can be selected from multiple options. By providing different acceleration rates as selectable parameters, the system maintains simplicity through standardized options while achieving adaptability to various operating conditions and user needs.
Data Source
AI summary
A variable speed control system and method for a walk-behind working machine includes a control system base, a control lever selectively movable with respect to the control system base between two operating positions, a mode actuator positioned on the control system base for toggling between a plurality of control modes, and a control unit in communication with the control lever, the mode actuator, and a machine component. The control unit selectively controls the operation of the machine component between a minimum operating speed and a variable maximum operating speed. The control unit applies a different acceleration profile to accelerate from the minimum operating speed to the variable maximum operating speed depending on the control mode selected.