Rotary Lawnmower Deflector Movable Stop Mechanism
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Solution Overview
Problem
Existing rotary lawnmowers require external components or forces to maintain a compact, closed deflector position for packaging, which complicates the conversion back to the standard two-position deflector arrangement after unpacking.
Innovation Solution
A movable stop mechanism that allows the deflector to automatically move to a closed position under resilient biasing force without external assistance, simplifying the packing and unpacking process by preventing movement from the deflecting to the closed position but allowing easy transition from the closed to the deflecting position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a second resilient spring is used to maintain the deflector in the closed position, then the deflector can be held in the closed position for packaging, but the device complexity increases and requires external packaging components to maintain the closing force
Solution Approach 1:
The patent removes the second resilient spring from the system entirely. Instead of using a complex two-spring mechanism, the invention extracts the unnecessary component and relies solely on the first resilient spring combined with the movable stop to achieve the closed position functionality during packaging.
Solution Approach 2:
The movable stop is designed to be automatically positioned by the deflector's own movement. When the deflector moves to the closed position under the first spring's force, the movable stop self-adjusts to the second position without requiring external packaging components or additional forcing mechanisms.
2Volume of moving object
If the deflector is made flush with the rear of the cutting deck housing in the closed position, then the lawnmower becomes more compact for packaging, but a mechanism is needed to maintain the closed position without external forces
Solution Approach 1:
The movable stop is designed as a dynamic component that can shift between two positions based on the deflector's movement. It moves from the first position (allowing deflector movement) to the second position (maintaining closed position) automatically, providing adaptive constraint rather than fixed restriction.
Solution Approach 2:
The movable stop acts as an intermediary element between the deflector and the housing. It mediates the interaction by providing a constraint force only when needed (in the second position) while allowing free movement when not needed (in the first position), enabling compact packaging without complex maintenance mechanisms.
3Ease of operation
If the movable stop is resiliently biased towards the first position, then the deflector can easily transition from closed to deflecting position, but the stop mechanism becomes more complex
Solution Approach 1:
The movable stop's biasing parameter is set to favor the first position, creating an asymmetric force distribution. This parameter change ensures that the stop naturally returns to allowing free deflector movement after the deflector transitions to the deflecting position, simplifying operation without requiring complex control mechanisms.
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 solution enables a more compact lawnmower design with reduced material and storage costs, while allowing seamless conversion back to the standard operation mode after unpacking without requiring external forces or packaging components to maintain the closed position.
Implementation Method 1
a spring which biases the deflector from the open position towards a deflecting position
Implementation Method 2
a movable stop having a first position which holds the deflector in the deflecting position against the resilient biasing force
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
The invention relates to a rotary lawnmower 100 comprising a cutting deck housing 110 which defines a cutting chamber 111. The housing has an aperture 112 to the rear through which grass cuttings are ejected from the cutting chamber in use. A deflector guard 120 is mounted about a hinge 121 at the rear of the housing, outboard of the aperture, for selectively deflecting the ejected grass cuttings. The deflector guard 120 is movable under a resilient biasing force provided by a helical torsion spring 122 from an open position in which the ejected cuttings are undeflected on their path from the aperture, through a deflecting position (A) in which the ejected cuttings are deflected downwards to the ground, to a closed position (B) in which the aperture is substantially closed. The lawnmower further comprises a movable stop 200 made from a resiliently deformable material. In a first position , movable stop 200 holds the deflector guard 120 in the deflecting position against the resilient biasing force of the spring 122, the spring extension arm 123 resting against the stop surface. In a second position, movable stop 200 allows the deflector guard to move under the biasing force from the deflecting position (A) to the closed position (B). The deflector will remain in the closed position in the absence of any external forces. In the reverse direction, movable stop 200 always allows movement from the closed position to the deflecting position.