Sliding Handle Grip Speed Control with Toothed Rack Lock
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Solution Overview
Problem
Existing walk behind lawn mower self-propel systems require complex handle grip mechanisms for speed control, leading to inconsistent ground speed and the need for constant operator adjustment, with no ability to temporarily increase speed without manual manipulation or maintain a constant speed setting.
Innovation Solution
A ground speed control system featuring a handle grip that slides up and down to adjust speed, with a pivotal lever and toothed members that allow for temporary speed boosts and cruise control settings, enabling the operator to lock the grip in a desired position for consistent speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a slidable handle grip mechanism is used for speed control, then the operator can adjust ground speed, but the structure becomes complex and requires constant manual adjustment to maintain consistent speed
Solution Approach 1:
The control system is divided into separate functional components: a slidable handle grip for speed selection, a pivotal control lever for temporary speed boosts, and a toothed rack mechanism for engagement. This segmentation allows each component to perform its specific function independently, simplifying the overall design while maintaining operational flexibility.
Solution Approach 2:
A toothed rack and pivotal control lever act as intermediaries between the operator's input and the self-propel system. The toothed rack provides mechanical engagement points that translate the control lever's movement into discrete speed adjustments, reducing the need for continuous manual manipulation of the handle grip itself.
2Reliability
If the operator manually adjusts the handle grip position frequently, then speed can be maintained on varying terrain, but operator effort and time are increased
Solution Approach 1:
The control lever is pre-positioned in an engaged state with the toothed rack, allowing the operator to quickly access temporary speed boosts or cruise control settings without needing to manually reposition the handle grip. This preliminary arrangement of control elements enables rapid response to terrain changes.
Solution Approach 2:
The control lever transitions between fixed engagement positions on the toothed rack, providing dynamic speed adjustment options. The system moves from a static handle grip position to a dynamic control mechanism that can quickly shift between predefined speed settings, reducing adjustment time while maintaining ground speed consistency.
3Ease of manufacture
If a simpler handle grip structure is used, then manufacturing cost is reduced, but the ability to provide temporary speed boosts and cruise control is lost
Solution Approach 1:
The patent combines multiple control functions into a unified system: the slidable handle grip for base speed selection, the pivotal control lever for temporary boosts, and the toothed rack for mechanical engagement all work together as an integrated assembly. This merging allows complex functionality to be achieved through coordinated simple components rather than a single complex mechanism.
Solution Approach 2:
The control lever serves multiple functions: it can engage temporary speed boosts by shifting the handle grip position, provide cruise control by locking at specific toothed rack positions, and return to neutral positions. This multi-functionality is achieved through a single pivotal lever component interacting with the toothed rack, maintaining ease of manufacture while providing versatile speed control.
Data Source
AI summary
A ground speed control system for an outdoor power equipment unit comprises a slidable handle grip that moves up and down on a handle to decrease and increase the ground speed, respectively. A pivotal control lever is provided on the handle grip. The pivotal lever includes a toothed sector gear. A toothed rack is fixed to the handle. Normally, the sector gear and toothed rack are out of engagement with each other during sliding motion of the handle grip. However, if the operator pivots the control lever to engage the sector gear with the rack, cooperation between the teeth of the sector gear and the teeth of the rack will move the slidable handle grip further down the handle to provide a temporary speed increase and will also lock the handle grip to the handle to provide cruise control capability. The handle grip is U-shaped and has two legs telescopically received inside the open upper ends of a pair of spaced handle tubes.