Rolling Element Braking Unit for Handheld Power Tools
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Solution Overview
Problem
Existing machine tool braking devices for portable tools lack efficient mechanisms to safely and effectively brake rotational movements within a specific time frame, particularly in hand-held tools with limited mass, while minimizing production costs and ensuring operator safety.
Innovation Solution
A machine tool brake device with a rolling element that activates a braking mode by converting kinetic energy into thermal energy through direct contact, utilizing a driver element to move a friction element, and incorporating a spring element for prestressing, allowing for a controlled braking and release process without additional electrical components, and designed as an assembly module for easy integration and maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a braking unit is added to portable machine tools, then operator safety is improved, but device complexity increases
Solution Approach 1:
The patent extracts the braking function from complex electrical braking systems and implements it through a simple mechanical rolling element mechanism. The rolling element (ball or cylinder) activates braking modes through pure mechanical interaction with the friction element, eliminating the need for additional electrical components, sensors, and control electronics that would increase device complexity.
Solution Approach 2:
The braking unit is designed to be self-activating through the rolling element mechanism. When the machining tool rotates, centrifugal force automatically positions the rolling element to engage the friction element, creating brake torque without requiring external control systems. The spring element provides automatic prestressing, and the ratchet mechanism enables automatic release, making the entire braking system self-regulating and eliminating complex control circuitry.
2Reliability
If braking time is reduced for safety, then operator safety is improved, but energy loss increases
Solution Approach 1:
The braking system operates in periodic cycles: during normal operation the rolling element is disengaged from the friction element (no energy loss), and during braking the rolling element engages to create friction (energy conversion to heat). The ratchet mechanism allows the brake to be released periodically when not needed, minimizing continuous energy loss while maintaining rapid braking capability when safety requires it.
Solution Approach 2:
The system changes the friction parameter dynamically through the rolling element mechanism. When braking is required, the rolling element engages the friction element to maximize friction and rapid deceleration. When braking is not required, the rolling element disengages, minimizing friction and energy loss. This parameter change is controlled by centrifugal force and spring prestressing rather than complex electronic control.
3Reliability
If additional safety components are added, then operator safety is improved, but production cost increases
Solution Approach 1:
The braking unit is designed as a compact assembly module using simple, inexpensive mechanical components: a rolling element (ball or cylinder), a friction element, a spring element, and a ratchet mechanism. These components can be manufactured using standard machining processes and assembled relatively easily. The modular design allows the entire braking unit to be produced as a separate assembly that can be integrated into portable machine tools without requiring expensive custom manufacturing or complex installation procedures.
4Reliability
If braking force is increased for safety, then operator safety is improved, but device complexity increases
Solution Approach 1:
The braking force is dynamically adjusted through the rolling element mechanism rather than being fixed. The spring element provides automatic prestressing that adapts to operating conditions, and centrifugal force dynamically positions the rolling element to engage the friction element with appropriate force. This dynamic braking force adjustment is achieved through passive mechanical means rather than active electronic control, maintaining simplicity while ensuring sufficient braking force for safety.
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 provides a safe and efficient braking mechanism that reduces the speed of portable machine tools by at least 50% within 0.1 to 3 seconds, ensuring operator safety and reducing production costs through a simple, structurally robust design that can be easily integrated into various portable tools.
Implementation Method 1
conversion of kinetic energy into thermal energy by means of direct contact between at least two components
Implementation Method 2
A rolling movement, in particular a rolling movement as a result of centrifugal force, of the rolling element can advantageously be used in order to activate the braking mode
Data Source
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AI summary
The invention is based on a power tool braking device, in particular a handheld power tool braking device, of a portable power tool, comprising at least one braking unit (14a; 14b; 14c), which is intended for braking a movement of a working tool at least in one operating mode. It is proposed that the braking unit (14a; 14b; 14c) has at least one rolling-contact element (18a, 20a, 22a; 18b, 20b, 22b; 18c, 20c, 22c), which is intended for activating at least one braking mode of the braking unit (14a; 14b; 14c).