One-Hand Lawn Mower Chassis With Rear Steering Stability
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Solution Overview
Problem
Existing lawnmowers are not optimally designed for maneuverability and one-handed operation in small urban gardens with uneven terrain, often requiring significant effort and precision due to inconsistent steering behavior and wheel slippage.
Innovation Solution
A chassis design with non-steerable front wheels and a steerable rear wheel, combined with a tiltable and pivotable handlebar, allowing for improved maneuverability and one-handed operation by defining an instantaneous center of rotation through the front wheels, ensuring consistent steering and minimal slippage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If four rigid, non-steerable wheels are used at the corners of the chassis, then the lawnmower has stable support, but maneuverability is poor and steering requires significant force
Solution Approach 1:
The patent divides the wheel configuration into two functional groups: two steerable rear wheels for maneuverability and two non-steerable front wheels for stable support. This segmentation allows each wheel pair to perform its specialized function without compromising the other, resolving the contradiction between stability and ease of operation.
Solution Approach 2:
Instead of the conventional configuration with steerable front wheels and fixed rear wheels, the patent inverts the steering function to the rear wheels. This inversion allows the front wheels to provide stable, fixed support while the rear wheels handle all steering operations, improving both maneuverability and operational ease.
2Device complexity
If the handlebar is rigidly connected to the chassis, then the structure is simple, but precise positioning requires frequent lifting of the machine
Solution Approach 1:
The patent introduces dynamic articulation between the handlebar and chassis through pivoting and tilting joints. This allows the handlebar to move independently relative to the chassis, providing the operator with precise control over the lawnmower's positioning without requiring lifting, while maintaining operational simplicity.
3Force
If significant force is applied to steer the lawnmower, then steering is achieved, but wheel slippage occurs on uneven terrain
Solution Approach 1:
The patent segments the steering function to only the rear wheels, which are equipped with steerable mechanisms. This segmentation allows steering forces to be applied more efficiently through the articulated handlebar to the rear wheels, reducing slippage on uneven terrain while maintaining consistent steering behavior.
Data Source
Figure 1~2
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Figure 5
AI summary
The invention relates to an electric lawnmower (1) comprising a chassis (2) and a handlebar (3) pivotally connected to the chassis (2). The chassis (2) has a front end (F) extending forward in the intended direction of travel (X) and a rear end (R) extending backward, between which a mowing unit (4) is arranged. At the front end (F), it has a first rigid front wheel (5a) on the left side and a second rigid front wheel (5b) on the right side, each rotatable about a first axis of rotation (A) oriented transversely to the intended direction of travel (X). At the rear end (R), the chassis (2) has a steerable trailing wheel carrier (6) pivotally mounted about a vertical steering axis (L) relative to the chassis (2). At least one rear wheel (7) is rotatably mounted on the trailing wheel carrier (6) on a second horizontal axis of rotation (B).The second pivot axis (B) on the trailing wheel carrier (6) is offset by an axis offset (D) relative to the steering axis (L). The grab handle (3) is pivotally mounted on the chassis (2) via a hinge joint (8) with a substantially horizontal pivot axis (S). The grab handle is connected to the hinge joint (8) via a tilting joint (9).