Brush Cutter Head Key Pin Coupling Mechanism
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Solution Overview
Problem
Existing brush cutter heads with blade cutting elements face issues of complex and difficult-to-activate safety systems, leading to potential disengagement of cutting elements during impact or replacement, and lack of clear visual inspection for proper coupling.
Innovation Solution
A brush cutter head design featuring a support body with radially distributed pins and movable keys that facilitate easy engagement and visual inspection of cutting elements, combined with a retaining system using slotted sections and elastic means to secure blades against radial and axial thrusts, and impact-absorbing slits to prevent disengagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex safety systems with hooks and movable pins are used to secure blades, then the blade constraint reliability is improved, but the device complexity and ease of operation deteriorate
Solution Approach 1:
The safety system is divided into separate functional elements: a pin for radial constraint and a key for axial constraint. The key can be independently positioned to engage with the pin, creating a simplified modular system that maintains reliability while reducing complexity compared to integrated hook-and-shell mechanisms.
Solution Approach 2:
The key acts as an intermediary element between the blade and the pin. Instead of direct hooking or complex movable pin systems, the key mediates the connection by engaging with the pin to provide axial constraint, simplifying the overall mechanism while maintaining security.
2Reliability
If hooking mechanisms inside shell openings are used, then blade security is improved, but ease of operation and inspection deteriorate
Solution Approach 1:
The constraint mechanism transitions from a hidden internal hooking system to an external dimensional arrangement where the key and pin are accessible from the outside. The key can be inserted and positioned externally, and its engagement with the pin is visible, allowing easy operation and inspection without disassembling shell structures.
3Ease of operation
If movable pins are used to allow blade insertion, then ease of operation is improved, but reliability and inspection clarity deteriorate
Solution Approach 1:
The pin is pre-positioned in a fixed location, and the key is designed to engage with it in a predetermined manner. This preliminary arrangement ensures that when the key is inserted, it automatically engages the pin to provide axial constraint, maintaining reliability while keeping the mechanism simple and inspectable.
4Device complexity
If impact forces are transmitted to the blade-pin coupling, then structural simplicity is maintained, but reliability deteriorates due to potential disengagement
Solution Approach 1:
The axial constraint function is extracted from the radial pin-blade coupling and assigned to a separate key mechanism. This separation allows the pin to handle radial forces while the key handles axial forces, improving reliability by preventing disengagement during impact without significantly increasing overall structural 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
The design simplifies the installation and replacement of cutting elements, ensures secure attachment against radial and axial forces, and absorbs impact to prevent disengagement, providing a safer and more user-friendly operation.
Implementation Method 1
a plurality of elastic means (6), distributed so that a respective elastic means (6) is active on each key (5)
Implementation Method 2
This coupling prevents the centrifugal force from causing the cutting element to disengage, projecting it away from the head
Data Source
AI summary
Head 1 for brush cutter for cutting grass and herbaceous plants of the type comprising a plurality of cutting elements 2, of the blade type and each having a front cutting portion 21 and a rear hooking portion 23, connectable to the head 1 on a support body 3, provided with a central portion 31 and a peripheral portion 32 extending from the central portion 31 radially around it. At the peripheral portion 32 there is a plurality of pins 4, engageable by the plurality of cutting elements 2, on which a plurality of keys 5 are active, connected to the central portion 31 of the support body 3. Each key 5 being engageable with a respective pin 4 and movable, under the activation by an operator, from a first position, in which the key 5 is in contact with the pin 4 to which the key 5 is facing, to a second position, in which the key 5 is spaced apart from the pin 4 generating a passage opening adapted to allow the engagement of the cutting element 2 on the pin 4. A plurality of elastic means 6 is active on the plurality of pins 5 and adapted to return the plurality of keys 5 from the second position to the first position once the action induced by the operator has ceased.