Hedge Trimmer Cam Assembly for Blade Engagement
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Solution Overview
Problem
Existing outdoor tools, such as hedge trimmers, face challenges in maintaining blade engagement and efficiency due to lack of effective mechanisms for alternating motor direction and securing blades during operation.
Innovation Solution
The hedge trimmer design incorporates a cam assembly with a cam cover and slide cam washer, an output shaft positioned eccentrically, and a motor that alternates rotational direction based on a trigger switch input, along with a blade assembly that includes bushings for reciprocating motion and a fully enclosed blade sheath for protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cam assembly with rigid mounting is used to secure blades, then blade engagement reliability is improved, but device complexity increases
Solution Approach 1:
The cam assembly is divided into separate components: a cam cover, a cam body, and a cam washer. This segmentation allows each component to perform its specific function while simplifying the overall assembly and disassembly process, reducing the complexity burden while maintaining reliable blade engagement through the coordinated action of these segmented parts.
Solution Approach 2:
A cam washer is introduced as an intermediary component between the cam body and the blade mounting structure. This washer serves as a mediator that distributes the mounting forces, ensures proper alignment, and simplifies the interaction between the cam assembly and blade, thereby maintaining reliability while reducing direct structural complexity.
2Productivity
If an output shaft with eccentric cam assembly is used for reciprocating blade motion, then blade operation efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The output shaft is designed with varying diameters at different locations: a first portion with a first diameter for supporting the cam assembly and a second portion with a second diameter for supporting the output gear. This local variation in geometry allows for precise positioning of the eccentric cam assembly while maintaining ease of manufacture through standardized machining operations for each section.
Solution Approach 2:
The cam assembly is pre-configured with the cam cover, cam body, and cam washer in a predetermined arrangement before being mounted on the output shaft. This preliminary assembly allows for pre-positioning and alignment of components, reducing the precision requirements during final installation and enabling easier manufacturing while maintaining the eccentric configuration for efficient reciprocating motion.
3Strength
If a fully enclosed blade sheath is used for blade protection, then blade durability is improved, but device complexity increases
Solution Approach 1:
The blade sheath is constructed as a protective enclosure that can be made from flexible or thin-walled materials that provide adequate protection for the blades during storage and transport. This approach maintains blade durability while minimizing the structural complexity and material usage of the protective sheath.
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 configuration ensures rigid blade mounting, efficient blade operation, and enhanced durability by preventing disengagement and providing a secure, protected environment for the blades, while allowing for easy switching between forward and reverse motor directions.
Implementation Method 1
the cam assembly is positioned at a perpendicular plane respective to the second portion and supported for rotation about an axis to rotate eccentrically with respect to the output shaft axis
Data Source
AI summary
An outdoor device comprising: a first blade comprising a first blade opening at a proximal end; a second blade comprising a second blade opening at a proximal end; a first cam coin comprising a first cam coin opening; a second cam coin comprising a second cam coin opening; an output gear comprising an output gear opening; and an output shaft comprising a first portion and a second portion, the first portion wider than the respective openings, the second portion wider than the output gear opening, wherein the respective openings are aligned to form a cam assembly, and wherein the output shaft is positioned through the respective aligned openings such that the cam assembly is positioned at a perpendicular plane respective to the second portion and supported for rotation about an axis to rotate eccentrically with respect to the output shaft axis.