Velocity Profile Control for Power Vehicle Speed Adjustment
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Solution Overview
Problem
Existing power vehicles, such as zero-turning-radius mowers, face challenges in limiting maximum speed without reducing output, as current methods like throttle reduction impact attached implements' efficiency, and travel limiters are cumbersome to adjust and operate.
Innovation Solution
A velocity profile control system that adjusts the ratio of control lever movement to vehicle speed for a fixed power source output, allowing operators to change maximum potential vehicle speed without impacting power delivery to other subsystems, using a control link and adjustment member to vary the distance of control link ends from the pivot axis, enabling easy manipulation without tools or stepping off the vehicle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the engine throttle is reduced to limit maximum vehicle speed, then the maximum vehicle speed is reduced, but the output to attached implements (e.g., cutting deck rotational speed) is also reduced, potentially reducing cutting efficiency
Solution Approach 1:
The control system is segmented into independent channels: one controlling vehicle speed through the drive train and another controlling implement output through the power take-off (PTO) system. This allows the vehicle speed to be limited by restricting control lever travel, while the implement output remains independently controllable at full capacity, resolving the contradiction between speed limitation and cutting efficiency maintenance.
2Speed
If a control lever travel limiter is used to restrict maximum vehicle speed, then the maximum vehicle speed is reduced, but the device becomes more complex and time-consuming to adjust
Solution Approach 1:
The control lever stop assembly serves multiple functions: it limits control lever travel to restrict maximum vehicle speed, provides adjustable positioning through multiple detent locations, and maintains simplicity by integrating directly into the existing control mechanism. This multi-functionality eliminates the need for separate complex limiting devices, resolving the contradiction between speed limitation and adjustment simplicity.
3Speed
If the control lever travel is restricted to limit maximum vehicle speed, then the maximum vehicle speed is reduced, but the operator cannot rest the levers against the stops, reducing operator comfort
Solution Approach 1:
The control lever stop assembly provides dynamic adjustability through multiple detent locations along the control lever travel path. The operator can select different stop positions based on operational needs: a first detent location for reduced speed operation and a second detent location for maximum speed operation. This dynamic reconfigurability allows the stop to serve both as a speed limiter and as a rest position, resolving the contradiction between speed limitation and operator comfort.
Data Source
AI summary
Embodiments of the present invention relate to powered vehicles (e.g., lawn mowers) and, more particularly, to a control system for use with such a vehicle. In one embodiment, the vehicle includes a power source such as an internal combustion engine and one or more drive control levers incrementally movable between a neutral position and a maximum velocity position. The system may also include a velocity profile control system having an adjustment member that permits altering a ratio between control lever movement and velocity of an associated drive member or wheel. Thus, the system may alter a maximum potential velocity of the vehicle while the drive control lever(s) are positioned in the maximum velocity position without varying an output level of the power source.