Brake Assembly for Hand-Held Cutting Device Kickback Protection
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Solution Overview
Problem
Conventional brake assemblies for power-driven hand-held cutting devices, such as chainsaws, often experience unintended deactivation of the brake after activation, compromising user safety due to design flaws in the kickback safety mechanism.
Innovation Solution
A brake assembly with a biased brake member and a cam-based holding mechanism that ensures quick and reliable activation of the brake, utilizing a resilient element to maintain the brake in the activated position and a switch to shut off the motor, allowing intentional deactivation only when the lever is moved to the first position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional brake band and brake drum mechanism is used, then the brake can be activated to stop the chain, but the brake may unintentionally be inactivated after activation
Solution Approach 1:
The patent extracts the brake member from the conventional brake band-drum mechanism and creates a separate, independent brake member that can be directly actuated by the hand guard. This brake member is biased towards the activated position and can be held in either activated or deactivated position, eliminating the unintended inactivation issue while simplifying the overall structure.
Solution Approach 2:
The brake member is designed with a bias towards the activated position, meaning it automatically maintains itself in the safe activated state without requiring additional holding mechanisms. The system serves itself by using the inherent bias to ensure reliable brake activation and maintenance.
2Speed
If the brake is designed to activate quickly to stop the chain, then user safety is improved, but the brake may unintentionally deactivate compromising safety
Solution Approach 1:
The brake member is biased towards the activated position, automatically maintaining itself in the safe activated state without requiring additional holding mechanisms. This self-servicing design ensures the brake stays activated reliably while activating quickly when needed.
Solution Approach 2:
The patent changes the parameter of brake member positioning by introducing a bias towards the activated position. This parameter change ensures the brake member naturally settles and remains in the activated position, providing both quick activation and reliable maintenance of the activated state.
3Object-affected harmful factors
If the brake assembly uses a hand guard to activate the brake during kickback, then safety protection is provided, but the brake may be unintentionally inactivated after activation
Solution Approach 1:
The patent extracts the brake function from the conventional brake band-drum mechanism and creates a separate brake member that is directly actuated by the hand guard. This extracted brake member with bias towards activated position ensures stable brake activation during kickback protection without unintended inactivation.
Solution Approach 2:
The brake member's inherent bias towards the activated position creates a self-servicing mechanism that automatically maintains brake engagement during kickback events, ensuring the brake stays activated reliably without requiring additional holding structures.
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 brake assembly provides enhanced reliability and rapid stopping capabilities, ensuring user safety by maintaining the brake engaged until intentional deactivation, while also protecting the motor from overheating.
Implementation Method 1
a first resilient element arranged to bias the brake member in a direction towards the activated position
Implementation Method 2
the brake member arranged to engage with the brake element in the activated position to hinder rotation of the rotatable part
Data Source
Figure 1
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AI summary
A brake assembly (1) for a hand-held power-driven cutting device (2) is provided comprising a movably arranged lever (14), at least being movable between a first- and a second position, a brake member (16), and a brake element (20) connected to or forming one unit with a rotatable part (22) of a transmission of the cutting device (2), wherein the brake member (16) is movable between a non-activated position and an activated position, and wherein the brake member (16) is arranged to engage with the brake element (20) in the activated position to prevent rotation of the rotatable part (22). The brake assembly (1) further comprising a holding mechanism (23) arranged to hold the brake member (16) in the non-activated position when the lever (14) is in the first position, and a first resilient element (18) arranged to bias the brake member (16) towards the activated position, and wherein the brake member (16) is arranged to be released from the holding mechanism (23) as a response to the lever (14) coming into the second position, and wherein when released the brake member (16) is adapted to be forced towards the activated position by means of the first resilient element (18), and wherein the brake member (16) is arranged to engage with a structure (34) of the brake element (20) in said activated position so as to prevent rotation of the brake element (20).