Mower Deck Airflow and Fastening Design
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Solution Overview
Problem
Conventional mower units face challenges in efficiently conveying air to collect mown grass, particularly in densely grown areas, and suffer from insufficient air volume in the conveying air flow path from the discharge cover to the conveyance duct, as well as issues with foreign matter intrusion and loss of male screw members during fastening structure removal.
Innovation Solution
The mower unit incorporates a blade housing with a recess covered by a deck lid, creating an intermediate space for enhanced air flow and a fan unit with a labyrinth structure to prevent foreign matter intrusion, along with a fastening structure that includes a retaining member with a through part and slip-off prevention parts to prevent male screw member detachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If air intake ports are formed in the top panel of the blade housing to increase conveying air volume, then the conveying air volume is improved, but mown grass accumulates in the air intake ports region reducing air intake efficiency
Solution Approach 1:
The top panel is segmented into multiple air intake ports distributed across different regions, allowing air to be drawn from various locations while reducing grass accumulation in any single area. The side panels are also segmented with air intake ports to provide additional air supply paths away from the grass accumulation zone.
Solution Approach 2:
Air intake is extended from a two-dimensional top panel to include three-dimensional side panels. Air intake ports are formed in both the top panel and side panels, creating multiple spatial dimensions for air supply. This distributes the air intake function across different spatial zones, reducing dependency on any single region and minimizing the impact of grass accumulation.
2Productivity
If the blade housing is designed with a higher portion above the blade outer region to effectively collect wind flow, then wind collection efficiency is improved, but mown grass accumulates in the resulting recess
Solution Approach 1:
The blade housing structure maintains its higher portion above the blade outer region for effective wind collection, but air intake ports are strategically positioned to create dynamic air flow paths that prevent static grass accumulation in the recess areas. The air intake system adapts to the housing geometry to maintain productivity while mitigating the harmful accumulation effect.
3Productivity
If the fan rotor communicates with outside through the intake opening in a direct linear manner, then air intake efficiency is improved, but foreign matters easily enter the fan rotor and blade regions
Solution Approach 1:
A fan case is introduced as an intermediary structure between the intake opening and the fan rotor. The fan case surrounds the outer periphery of the fan rotor and connects to the intake opening, creating a controlled air flow path. This intermediary structure maintains air intake efficiency while preventing foreign matters from directly entering the fan rotor and blade regions.
4Ease of operation
If the male screw member is completely detached from the cover member and covered member during fastening structure removal, then assembly disassembly is simplified, but the male screw member may be lost
Solution Approach 1:
The male screw member is nested within the retaining member, which has a through part allowing the male screw member to pass through. The retaining member acts as a container that holds the male screw member during disassembly, preventing loss while allowing easy insertion and removal. The female screw member is received by the retaining member, creating a nested arrangement that secures components during operation.
Data Source
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AI summary
A mower unit (120) comprising a blade unit (170) including: a rotary shaft (171a, 173a) having a rotary axis (171, 173) extending in a vertical direction; and a blade (172, 174) which is provided on the rotary shaft (171a, 173a) and rotatable about the rotary axis (171, 173); a blade housing (121) including a top panel (121a) and a side plate (121b) extending downward from a peripheral edge of the top panel (121a), for covering the blade unit (170) from above to create a mowing space (108) therein; a mown grass discharge port (129) formed in the top panel (121a) for discharging conveying air flow generated by rotation of the blade; an intake part (102) that supplies ambient air to the conveying air, the intake part (102) includes an ambient air intake opening (102a; 102b; 102c) formed in mown grass discharge port (129) or in the vicinity thereof, and an auxiliary ambient air intake opening (121s; 121e; 121f; 121g) formed in the top panel (121a) or the side plate (121b); and a cover (200; 201; 202; 203; 125a) that covers the auxiliary ambient air intake opening (121s; 121e; 121f; 121g).