Protective Hood Stop Structure for Broken Cutting Wheel Energy Absorption
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Solution Overview
Problem
Existing handheld work apparatuses, such as cut-off machines, face challenges in reliably absorbing and dissipating the kinetic energy of a cutting wheel when it breaks during operation, due to limited freedom of movement of the protective hood.
Innovation Solution
A handheld work apparatus with a protective hood that pivots and is restricted by a mating stop on the motor support unit, ensuring the hood absorbs and transfers kinetic energy effectively, using a metal alloy for high strength and rigidity, and a load transfer structure to direct forces directly to the motor support unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the protective hood is designed to pivot with limited freedom of movement, then it can absorb kinetic energy of cutting wheel parts, but it cannot reliably dissipate the kinetic energy
Solution Approach 1:
The protective hood is designed to pivot about the axis of rotation, transforming from a static structure to a dynamic one that can move to absorb kinetic energy while maintaining controlled freedom of movement for energy dissipation
Solution Approach 2:
A stop element is introduced as an intermediary component between the protective hood and the motor support unit. This stop element mediates the interaction by providing a defined end position that allows the hood to pivot and absorb energy while preventing excessive movement, thus enabling reliable energy dissipation
2Device complexity
If the stop element is formed on the housing, then the structure is simpler, but large forces and torques cannot be reliably transferred
Solution Approach 1:
The stop element is formed on the motor support unit, which serves as an intermediary component specifically designed to handle high forces and torques. This separates the function of providing structural strength (motor support unit) from the function of limiting movement (stop element), enabling reliable force transfer without compromising structural integrity
Solution Approach 2:
The motor support unit is designed as a separate component from the housing, with the stop element formed on it. This segmentation allows the motor support unit to be optimized for strength and rigidity to handle high forces, while the housing maintains its protective function
3Reliability
If the protective hood is restricted to a small pivot angle, then it reliably absorbs kinetic energy, but the freedom of movement is insufficient
Solution Approach 1:
The stop element acts as an intermediary that defines the end position of the protective hood's pivot movement. This allows the hood to have sufficient freedom of movement to absorb kinetic energy while being reliably restricted to a maximum pivot angle, balancing both requirements
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 solution ensures reliable absorption and dissipation of kinetic energy from broken cutting wheel parts, preventing damage by maintaining contact and optimizing force transfer, even with deformation, thus enhancing safety and durability.
Implementation Method 1
the protective hood absorbs the kinetic energy of the cutting wheel parts
Implementation Method 2
the protective hood dissipates the kinetic energy of the protective hood
Data Source
AI summary
A handheld work apparatus includes: a housing (2); a motor support unit (10) which is separate from the housing (2) and is connected to the housing (2); a drive motor (3) arranged in the housing (2) for driving a tool (5) that rotates about an axis of rotation (8), wherein the drive motor (3) is attached to the motor support unit (10); a protective hood (51), the protective hood (51) at least partially covering the tool (5) and a stop (110) being provided on the protective hood (51). A mating stop (120) is formed on the motor support unit (10), in particular directly, which is provided for operative connection with the stop (110) of the protective hood (51) in order to restrict the pivoting movement of the protective hood (51) to an end position (131).