Locking Lever Spring Layout for One-Handed Tool Operation
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Solution Overview
Problem
Hand-held work devices with safety locking mechanisms are often uncomfortable and non-intuitive to operate, requiring operators to release their grip to actuate both levers simultaneously, which can be challenging and inefficient.
Innovation Solution
A hand-held working device with a locking lever pivotally mounted about an axis of rotation, featuring a spring unit that biases the locking lever into a locking position, allowing operation in both directions with equal restoring force, and wing elements for ergonomic access, enabling comfortable operation with either hand.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If both levers are arranged to be pressed simultaneously with one hand, then operation speed is improved, but operator comfort and intuitiveness deteriorate
Solution Approach 1:
The locking lever is pre-loaded by a spring mechanism into a locked position that automatically engages with the actuating lever. This preliminary action allows the levers to be arranged such that the locking lever can be actuated first to release the lock, enabling the actuating lever to be pressed subsequently without requiring simultaneous two-handed operation, thus improving both comfort and intuitiveness while maintaining operational efficiency
2Reliability
If the locking lever is pre-loaded by a spring mechanism, then the locking lever returns to locked position reliably, but the actuation force required increases
Solution Approach 1:
The spring mechanism is designed to provide dynamic loading characteristics where the pre-load force is optimized to ensure reliable return to the locked position while maintaining acceptable actuation force levels. The spring constant and pre-compression are calibrated to balance reliability requirements with operator effort constraints
3Ease of operation
If the levers are arranged for one-handed simultaneous operation, then device portability is improved, but grip firmness deteriorates
Solution Approach 1:
The locking lever is positioned and pre-loaded such that it can be actuated with a thumb or finger motion before the actuating lever operation. This sequential arrangement allows the operator to maintain a firm grip on the handle with one hand while easily actuating the locking mechanism, eliminating the need to relinquish grip firmness for lever 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 ergonomic operation by allowing the locking lever to be easily unlocked in various grip positions and directions, enhancing usability for both right- and left-handed users and reducing the need for operators to release their grip on the handle.
Implementation Method 1
a spring unit (6) for the locking lever (5) preloads the locking lever (5) toward the locked position (10)
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
Hand-held work device comprising a tool (3) and a drive motor (2) for driving the tool (3), a handle (26) having a longitudinal axis (18), an actuating lever (4) for operating the drive motor (2), a locking lever (5) for the actuating lever (4) wherein the locking lever (5) is pivotably mounted about a pivot axis (8) of the locking lever (5), and a longitudinal plane (27) wherein the longitudinal plane (27) contains the longitudinal axis (18) of the handle (26) and is parallel to the pivot axis (8) of the locking lever (5), wherein the locking lever (5) locks the actuating lever (4) in a locking position (10) and releases it for actuation in at least one release position (11, 11'), a spring unit (6) for the locking lever (5) wherein the spring unit (6) interacts with a contour (15) on the locking lever (5),wherein the contour (15) extends over an angular segment around the axis of rotation (8) of the locking lever (5) and has a lower section (16) extending towards the axis of rotation (8), wherein the spring unit (6) bearing against the lower section (16) of the contour (15) biases the locking lever (5) in the direction of the locking position (10).