Spindle Stop Mechanism for Percussion Drills
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Solution Overview
Problem
Existing spindle stop mechanisms for electric hand tools, particularly in percussion drills, are prone to mechanical stress and heat-induced deformation, leading to reduced robustness and service life due to the use of thin, elastic elements.
Innovation Solution
A spindle stop device featuring stiff, solid sliding elements and a one-piece brake ring with a notched disk design, which transmits torque through rollers and cams, eliminating the need for resilient elements and enhancing mechanical robustness and ease of production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If resilient elements (platelets with thin walls) are used to pre-position clamping elements, then the spindle stop can be implemented with simpler structure, but the mechanical robustness decreases and service life is reduced due to breakage and deformation under mechanical stress and heat
Solution Approach 1:
The patent changes the physical state and mechanical properties of the pre-positioning element from elastic/resilient to rigid/movable. The sliding element is designed to be stiff and solid rather than springy, fundamentally changing the parameter of material compliance to achieve higher mechanical robustness while maintaining the pre-positioning function
Solution Approach 2:
The patent employs a composite structure combining the sliding element with the control disk, where the sliding element acts as a rigid extension on the outer circumference of the control disk. This composite design integrates the pre-positioning function into a more robust structural unit that resists breakage and deformation
2Ease of manufacture
If resilient elements are used for pre-positioning clamping elements, then the device can be manufactured with simpler processes, but the service life is significantly reduced due to frequent breakage in percussion operation
Solution Approach 1:
The patent fundamentally changes the material parameter from elastic to rigid for the pre-positioning element. The sliding element is designed to be stiff and solid, which eliminates the weakness of resilient elements under percussion stress while maintaining manufacturability through standard machining processes
Solution Approach 2:
The sliding element is pre-positioned on the control disk to automatically set the clamping bodies at the correct distance from the cam before operation begins. This preliminary positioning action is performed by the rigid sliding element rather than resilient elements, ensuring consistent pre-positioning without the risk of deformation during percussion operation
3Quantity of substance
If thin-walled resilient platelets are used, then the initial device cost and manufacturing complexity are reduced, but the mechanical stress in percussion operation causes frequent breakage and heat-induced deformation
Solution Approach 1:
The patent changes the mechanical parameter of the pre-positioning element from compliant to rigid. The sliding element is designed with sufficient mass and stiffness to withstand percussion mechanical stress and heat-induced thermal expansion without breaking or deforming, while still performing the pre-positioning function
Solution Approach 2:
The sliding element performs the pre-positioning action before the clamping operation begins. By being rigid and massive, it ensures accurate pre-positioning of clamping bodies without the risk of deformation under subsequent mechanical stress and heat generation during percussion operation
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 increased mechanical robustness and extended service life, enabling reliable operation in percussion drills without the risk of element breakage or deformation, while simplifying production and assembly processes.
Implementation Method 1
a sliding element which can be displaced relative to the cam and which, when driven on the drive side by means of an entrainment element, positions a clamping body arranged on the side of the cam opposite the entrainment element at a distance from the cam
Implementation Method 2
With a drive-side drive, torque is transmitted from the drive unit via the driver elements and via the clamping bodies to a cam of the output unit, whereas with a tool-side drive the output unit is blocked by clamping at least one clamping body between part of the output unit and the clamping surface
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The electric hand tool has a housing, a motor-driven drive unit (2), an output unit (7) and a pull-in- or blocking unit (1), where the pull-in- or blocking unit has a clamping body (6,6'), assigned housing-fixed clamping surfaces (41) and pull-in elements (31) that are coupled with the drive unit. A sliding element (51) displaceable relative to a cam (71) is provided in the area of the cam. The sliding element is provided to position the clamping body at a distance from the cam in drive-sided drive by the pull-in elements, where the clamping body is arranged on the side of the cam.