Lawnmower Blade Disk Torque Transmission and Dirt Management
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Solution Overview
Problem
Existing lawnmowers face issues with grass clippings lodging in the mower housing due to the disk's smaller diameter compared to the blade, leading to inefficiencies and increased dirt accumulation, which affects torque transmission and operational reliability.
Innovation Solution
A blade is connected to a disk in a rotationally fixed manner, with the disk non-rotatably held on the drive shaft, ensuring reliable torque transmission and incorporating a ribbed structure for stable knife positioning and dirt displacement, along with a fastening system that prevents loosening during operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the disk diameter is made smaller than the blade length, then the structure is more compact, but grass clippings fly past the disc and become lodged in the mower housing
Solution Approach 1:
The patent converts the harmful effect of grass clippings flying past the disc by extending the disc diameter beyond the blade length. This extension transforms the disc from a component that fails to contain clippings into an effective shield that prevents clippings from entering the housing, while the centrifugal force naturally propels clippings outward along the extended disc perimeter.
2Device complexity
If the blade is bolted directly to the drive shaft, then the structure is simple, but torque transmission may be insufficient and the blade may loosen during operation
Solution Approach 1:
The patent implements a nested fastening structure where the drive shaft passes through the blade, which is secured by a nut, which in turn is retained by a snap ring within a groove. This multi-layer nested arrangement ensures reliable torque transmission and prevents blade loosening while maintaining structural compactness.
Solution Approach 2:
The snap ring is pre-installed in the groove to create a preliminary mechanical barrier that prevents the nut from loosening during blade operation, eliminating the need for complex locking mechanisms while ensuring reliable fastening.
3Adaptability or versatility
If the disc has an opening with a bushing for the drive shaft, then the disc can float freely, but torque transmission from the drive shaft to the disc becomes less reliable
Solution Approach 1:
The patent segments the connection between the drive shaft and disc by introducing a keyed connection that divides the torque transmission path into distinct functional zones: the key transmits torque while the bushing provides floating capability, allowing each component to perform its specific function optimally.
4Area of stationary object
If the blade extends over the entire diameter of the disc, then coverage is maximized, but the distance between the cutting edge and disc is minimal, causing dirt accumulation
Solution Approach 1:
The patent extends the disc beyond the blade diameter, converting the potential harm of increased dirt accumulation into a benefit by using the extended disc perimeter to deflect grass clippings and dirt away from the housing, while the blade maintains optimal positioning for cutting performance.
Data Source
Figure 1~3
Figure 4~5
Figure 6~8
AI summary
The invention relates to a working device with at least one blade (6) driven by a drive motor (3) to rotate about a rotary axis (5). The working device has a drive shaft (4) on which a disc (7) is arranged. The at least one blade (6) is arranged on a side of the disc (7) facing the ground (38) during operation. The distance of the radial outer edge (55) of the blade (6) to the rotary axis (5) is smaller than the radius of the disc (7). The disc (7) is fixedly mounted on the drive shaft (4) to prevent rotation. The blade (6) is fixedly connected to the disc (7), and the drive torque for the rotation of the blade (6) is transmitted from the disc (7) to the blade (6).