Mower Cutter Blade Recessed Wind Generating Portion
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Solution Overview
Problem
Conventional cutter blades with enlarged wind generating portions to reduce noise by air communication between the front and back sides often clog with cut grass, leading to insufficient noise prevention due to hindered air communication and persistent negative pressure.
Innovation Solution
A cutter blade design featuring recessed portions at the outer end of the wind generating portion, which are more inwardly recessed than the remaining outer end portion, preventing negative pressure and clogging, ensuring continuous air supply and noise reduction even during prolonged grass cutting operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a hole portion is provided at the wind generating portion to establish air communication between the front side and back side, then noise is reduced by preventing negative pressure, but the hole portion becomes clogged with cut grass during use
Solution Approach 1:
The wind generating portion is divided into multiple segments along the longitudinal direction, with gaps between segments that allow air communication. This segmentation prevents grass clogging while maintaining the noise reduction function, as the multiple distributed gaps are less prone to complete blockage compared to a single large hole.
Solution Approach 2:
The blade body is designed with different local structures: the wind generating portion has a specific cross-sectional shape with curved surfaces optimized for wind generation, while the blade portion has a different cross-sectional shape optimized for cutting. This local differentiation allows each portion to perform its specific function effectively without interfering with the other.
2Productivity
If the wind generating portion is enlarged to increase wind generation capability, then the ability to raise grass and convey cut grass is enhanced, but negative pressure is generated on the back side leading to increased noise
Solution Approach 1:
The wind generating portion is segmented into multiple sections along the longitudinal direction, creating distributed air communication paths. This allows the wind generating portion to be enlarged for better productivity while the segmented structure prevents negative pressure buildup by allowing air to flow through the gaps between segments.
Solution Approach 2:
Air communication is achieved not only through holes in the planar direction but also through the three-dimensional structure of the wind generating portion itself, which is raised and bent to create internal air passages and gaps. This multi-dimensional approach to air flow allows for both enlarged wind generation capability and effective negative pressure prevention.
3Productivity
If the wind generating portion is formed relatively large to maintain wind generating function, then grass raising and conveyance are improved, but noise prevention becomes difficult without adequate air communication
Solution Approach 1:
The wind generating portion is divided into multiple segments that create distributed air communication paths throughout the structure. This segmentation allows the overall wind generating portion to be large enough for effective grass conveying while maintaining adequate air flow paths to prevent negative pressure and noise.
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 recessed portions effectively prevent negative pressure and noise generation while maintaining the wind generating function, reducing the likelihood of clogging and enhancing durability through smooth stress distribution.
Implementation Method 1
an amount of air is supplied via the recessed portion to the back side of the wind generating portion, so that generation of a negative pressure can be prevented
Implementation Method 2
The cutter blade generates a wind inside a housing by a wind generating portion, so that this wind raises grass for facilitating its cutting or conveying cut grass
Implementation Method 3
generation of such negative pressure leads to generation of vortex at this negative pressure portion, which in turn tends to invite increase of noise
Data Source
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Figure 3
AI summary
A cutter blade (26) for a mower is driven to rotate about a vertical axis (26a) inside a housing (21). The cutter blade (26) includes a blade body (70), a blade portion (81) formed in the blade body (70) and a wind generating portion (82) formed in the blade body (70) on its side opposite in a width direction thereof to the side where the blade portion (81) is formed, the wind generating portion (82) being formed by being raised and bent from the blade body (70) over a predetermined area from an end in a longitudinal direction thereof. At an outer end portion of the wind generating portion (82a) in the longitudinal direction of the blade body, there is formed at least one recessed portion (90) recessed more inwards than the remaining portion of the outer end portion (82a).