Lawnmower Height Adjustment Mechanism for Stable Blade Position
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Solution Overview
Problem
Conventional lawnmowers experience instability in cutting blade height due to fluctuations in load and vibrations, leading to uneven cutting quality.
Innovation Solution
A work machine with a vertically adjustable work unit featuring a rotatable adjusting drive member, a converting mechanism, and elastic members that minimize play and friction, ensuring stable height adjustment through screw thread engagement and detent action, preventing rattling and inadvertent dropping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional height adjusting mechanism is used, then the structure is simple, but the cutting blade height becomes unstable due to rattling between members
Solution Approach 1:
A resilient member (spring) is introduced as an intermediary between the drive member and driven member. This spring eliminates play and rattling between the members while maintaining the simplicity of the screw thread mechanism, thereby improving height stability without significantly increasing complexity
Solution Approach 2:
The resilient member is pre-installed to cushion and absorb vibrations and load fluctuations before they can cause rattling or height instability. This beforehand cushioning prevents the harmful effects of vibrations on the height adjustment stability
2Reliability
If the support member is turned relative to the guide member for height adjustment, then height adjustment is achieved, but vibrations cause inadvertent dropping and uneven cutting
Solution Approach 1:
The resilient member acts as a mediator that maintains stable engagement between the screw thread of the drive member and the nut member, preventing vibrations from causing inadvertent dropping while allowing smooth height adjustment when needed
Solution Approach 2:
The resilient member converts the harmful vibrations and load fluctuations into beneficial elastic deformation, absorbing the shocks while maintaining continuous stable contact between the adjusting members, thus improving cutting quality
3Ease of operation
If friction is reduced for smooth adjustment, then ease of operation improves, but stability during operation may be compromised
Solution Approach 1:
The resilient member changes the normal force parameter dynamically - providing sufficient friction for stable position holding when stationary, while allowing smooth movement when adjustment force is applied, thus satisfying both ease of operation and position stability requirements
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a stable and precise height adjustment mechanism, enhancing the work unit's operational stability and durability, resulting in improved grass cutting performance.
Implementation Method 1
a first elastic member (66) provided on the machine main body (12) and resiliently and slidably abutting against the adjusting driven member (60) to urge the adjusting driven member (60) in a prescribed rotational direction
Implementation Method 2
A screw thread mechanism is formed between the inner circumferential surface of the guide member and the outer circumferential surface of the support member so that the height of the support member along with the cutting blade may be vertically adjusted by turning the support member relative to the guide member around the central axis thereof
Implementation Method 3
The grooves provide a detent action in cooperation with the bent or curved part of the sheet spring so that the adjusting driven member can be retained at each selected position in a stable manner
Implementation Method 4
an adjusting driven member (60) engaged by the adjusting drive member via a converting mechanism that converts a rotational motion of the adjusting drive member into a vertical motion of the adjusting driven member
Data Source
AI summary
A work machine (10) such as a lawnmower provided with a height adjusting mechanism comprises a machine main body (12), a guide member (50) supported on the machine main body so as to be rotatable around a vertical axis, a support member (60) engaged by the guide member via a converting mechanism that converts a rotational motion of the guide member into a vertical motion of the support member, a work unit (18) supported by the support member, and a sheet spring (66) provided on the machine main body and resiliently and slidably abutting against the support member to urge the support member in a prescribed rotational direction.