Spindle Lock Layout for Low-Friction High-Speed Power Tools
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Solution Overview
Problem
Existing automatic spindle locks in hand-held power tools experience significant frictional losses at high speeds, leading to heat generation, reduced tool service life, and inefficient power usage, as well as issues with clamping rollers moving during torque peaks, causing centrifugal forces and poor handling.
Innovation Solution
A spindle lock design featuring a rotating driven part that delimits the clamping space radially on the outside, reducing friction by allowing clamping means to be pushed radially outwards during rotation, and incorporating wedge-shaped depressions for defined positioning and reduced contact with the housing, enabling friction-free idling and efficient torque transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the clamping rollers are in constant contact with the housing-fixed outer surface of the clamping gap, then the spindle lock can effectively lock the spindle, but frictional force generates heat and reduces service life at high speeds
Solution Approach 1:
The patent makes the outer surface of the clamping gap dynamic by forming it on the rotating driven part instead of using a housing-fixed surface. This allows the clamping rollers to experience alternating contact conditions during rotation, reducing constant friction and heat generation while maintaining locking effectiveness when needed.
Solution Approach 2:
The rotating driven part creates periodic contact between the clamping rollers and the outer surface of the clamping gap. During each rotation cycle, the rollers engage and disengage from the contact surface, providing locking action only when required rather than continuous friction, thereby reducing heat generation and extending tool service life at high speeds.
2Reliability
If the clamping rollers are in constant contact with the housing, then the spindle lock provides continuous locking, but power loss increases and efficiency decreases
Solution Approach 1:
By forming the outer surface of the clamping gap on the rotating driven part, the system transitions from continuous static contact to dynamic periodic contact. This reduces energy loss through friction while maintaining the locking function when torque is applied, improving overall system efficiency.
3Loss of energy
If the clamping means are pushed radially outwards during rotation, then friction with the housing is minimized, but the clamping space must be precisely delimited
Solution Approach 1:
The patent uses the rotation of the driven part to dynamically push the clamping means radially outwards during operation, minimizing frictional contact with the housing. The clamping space is precisely delimited by the rotating driven part itself, which provides both the functional surface for clamping and the geometric constraint for radial movement.
4Power
If the driven part is fixed to the housing, then torque transmission is straightforward, but centrifugal forces cause clamping rollers to move undefined during torque peaks
Solution Approach 1:
The patent makes the driven part rotating relative to the housing, allowing centrifugal forces to act predictably on the clamping means during rotation. This dynamic arrangement enables the clamping rollers to be pushed radially outwards in a controlled manner during torque peaks, providing defined positioning rather than undefined movement.
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 virtually friction-free idling mechanism and defined clamping positioning, ensuring efficient power transmission and extended tool service life, even at high speeds, by minimizing contact with the housing and utilizing centrifugal force to maintain clamping means alignment.
Implementation Method 1
The at least one clamping means can be displaced within the clamping space by rotation of the spindle relative to the driver arrangement in order to clamp the driven part against the support arrangement
Data Source
Figure 1
Figure 2~3A
Figure 3B~3C
AI summary
The powered hand tool machine (10) has a housing (12), a drive unit, a driven spindle (16), at which a tool is attached, and a spindle lock (14), where the spindle lock has a follower arrangement which transfers a driving torque of the drive unit on the spindle, in which the driven part is brought. The driven part is connected into engagement with the spindle in a rotating manner. A clamping unit (32) is received in a clamping chamber which is limited radially outwardly by the driven part and radially inwardly by a support arrangement in circumferential direction.