Lawnmower Cutting Unit With Pivoting Impact Protection
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Solution Overview
Problem
Lawnmowers with cutting units face a trade-off between cutting efficiency and safety, as high impact energy leads to efficient cutting but increases the risk of damage and detachment of cutting members upon hitting hard objects, posing safety hazards and reducing efficiency.
Innovation Solution
A cutting unit design with a cutting disc and pivotably arranged cutting members that pivot to a retracted position upon impact, using a stop assembly to prevent repeated impacts by ensuring the angle between cutting and retracted positions exceeds 180 degrees, utilizing centripetal force to maintain the retracted position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the cutting unit is designed to have high impact energy for efficient cutting, then cutting efficiency is improved, but the risk of damage and detachment of cutting members upon hitting hard objects increases
Solution Approach 1:
The cutting members are designed to be pivotally arranged on the cutting disc, allowing them to dynamically change position between a cutting position and a retracted position. During rotation, centrifugal force moves cutting members to the cutting position for efficient cutting. Upon impact with hard objects, they automatically pivot to the retracted position, reducing impact energy and preventing damage. This dynamic positioning resolves the contradiction between high cutting efficiency and durability.
2Reliability
If cutting members are allowed to pivot freely upon impact, then safety is improved by preventing damage, but repeated impacts can cause cutting members to break off and be ejected
Solution Approach 1:
A stop assembly is provided that pre-establishes a physical limit to the pivoting movement of cutting members. When cutting members pivot upon impact, the stop assembly prevents them from rotating beyond a predetermined angle, ensuring they remain secured to the cutting disc. This preliminary constraint prevents complete detachment and ejection of cutting members while still allowing sufficient pivoting for safety.
3Reliability
If the angle between cutting position and retracted position is increased to prevent repeated impacts, then durability is improved, but the complexity of the cutting unit increases
Solution Approach 1:
The stop assembly is designed to serve multiple functions simultaneously: it limits the pivoting angle of cutting members to prevent repeated impacts, provides structural support for the cutting members, and maintains the geometric relationship between cutting and retracted positions. By integrating these functions into a single assembly, the design achieves improved durability without excessive complexity.
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
This design allows for high cutting efficiency while preventing damage to cutting members and external objects, enabling the use of harder materials for longer durability and maintaining sharpness, reducing the risk of detachment and jamming.
Implementation Method 1
The cutting members are configured to assume the cutting position by the centripetal force acting on the cutting member upon rotation of the cutting disc around the rotation axis
Data Source
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AI summary
A cutting unit (1) for a lawnmower (2) is disclosed. The cutting unit (1) comprises a cutting disc (3) configured to rotate around a rotation axis (Ax) during operation of the lawnmower (2) and a cutting member (4, 4') freely pivotably arranged on the cutting disc (3) around a pivot axis (Pa, Pa') between a cutting position and a retracted position. The cutting member (4, 4') is configured to assume the cutting position by the centripetal force acting on the cutting member (4, 4') upon rotation of the cutting disc (3) around the rotation axis (Ax). The cutting unit (1) comprises a stop assembly (5, 5') configured to stop pivoting movement of the cutting member (4, 4') when the cutting member (4, 4') reaches the retracted position. The angle between the cutting position and the retracted position is more than 180 degrees. The present disclosure further relates to a lawnmower (2) comprising a cutting unit (1).