Spindle Lock Buffering Inertia Impact in Power Tools
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Solution Overview
Problem
Existing automatic spindle locks in power tools engage suddenly when the motor transitions from operating to non-operating conditions, causing noise and potential damage due to inertia, and existing solutions struggle to vary delay effectively without altering multiple components.
Innovation Solution
A spindle lock system with a wedge roller and ramp surface mechanism, utilizing a speed reduction gear transmission and helical springs to control and buffer rotational inertia, ensuring consistent torque and modularity across different power tool models.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an automatic spindle lock is used to prevent spindle rotation when the motor stops, then the spindle lock engagement is sudden and causes noise and potential damage due to inertia, but using a delay mechanism increases device complexity
Solution Approach 1:
The patent applies beforehand cushioning by introducing a damping element that absorbs the impact energy before the locking engagement occurs. The damping element is positioned between the locking element and the spindle, and it cushions the impact when the locking element engages with the spindle groove, thereby preventing noise and potential damage while maintaining a relatively simple mechanism structure.
2Loss of time
If spring force is increased to delay spindle lock operation, then the delay effect is improved, but the force becomes uneven in forward and reverse directions
Solution Approach 1:
The patent applies asymmetry by designing the damping element with different structural characteristics for forward and reverse directions. The damping element includes a first damping portion for the forward direction and a second damping portion for the reverse direction, with different damping coefficients. This asymmetric design allows the spindle lock to have appropriate delay effects in both directions while maintaining force balance, avoiding the uneven force problem caused by symmetric spring designs.
3Force
If multiple spring members are used to achieve equal force in both directions, then the force uniformity is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent applies merging by combining the damping functions for both forward and reverse directions into a single integrated damping element. Instead of using separate spring members for each direction, the damping element integrates multiple damping portions with different damping coefficients into one component, achieving equal force effect in both directions while simplifying the overall structure and easing manufacturing.
4Ease of operation
If the spindle lock engages within the free angle of rotation, then the lock operates smoothly during normal rotation, but inertia causes sudden engagement and impact when the motor stops
Solution Approach 1:
The patent applies intermediary by introducing a damping element as a mediator between the locking element and the spindle. This damping element serves as an intermediate component that absorbs and dissipates the impact energy generated when the spindle inertia causes sudden engagement, thereby reducing noise and potential damage while allowing the spindle lock to operate smoothly within the free angle of rotation during normal 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 system provides reliable torque control with minimal delay variation, preventing impacts and noise, and allows for varying torque capacity using common parts, thus enhancing the operational efficiency and durability of power tools.
Implementation Method 1
a spring (25) which applies a resilient force to control and buffer the rotation of the spindle (13) and to delay the engagement of the locking structure (10")
Implementation Method 2
a wedge roller (26) and a ramp surface (35a, 35b) mechanism
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A spindle lock (10) includes a detent arrangement including springs (25) acting on projections (30), each projection engaging one of a pair of recesses (40, 41) to control and buffer the rotation of a spindle (13) and to delay the engagement of locking elements (26a, 26b). A compact, reliable mechanism with a high degree of modularity is achieved by providing the recesses in an inner rotor (31) and the springs and projections in an outer rotor (18) that extends about the inner rotor.