Rotating Locking Element for Load Gear Shifts
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Solution Overview
Problem
Existing hand-held power tools with switchable gears face reliability issues when changing gears under load, as the switching process requires shutting off and restarting the tool, leading to sudden acceleration or deceleration and high component loading.
Innovation Solution
A multi-stage transmission system with a switchable switching element that rotates between latching and disengaged positions, allowing continuous gear changes without sudden coupling, enabling gear shifts under load with reduced component loading by allowing limited angular rotation of the locking element between end stop positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the switching element is rigidly connected to the housing and suddenly coupled during gear change, then the gear change mechanism is simple, but the component loading becomes excessively high and reliability deteriorates
Solution Approach 1:
The locking element is made rotatable relative to the housing instead of being rigidly fixed, allowing it to dynamically adjust its angular position during gear changes. This rotational freedom enables the locking element to gradually engage or disengage from the switching element, transforming a sudden coupling shock into a controlled progressive process that reduces component loading while maintaining mechanism simplicity
2Loss of time
If the switching element is suddenly coupled during gear change, then the switching process is quick, but torque shock and component stress increase significantly
Solution Approach 1:
The locking element's rotational capability allows it to progressively engage or disengage from the switching element over a limited angular range, transforming a sudden coupling shock into a controlled progressive process. This dynamic engagement process extends the gear change time slightly but dramatically reduces torque shock and component stress by distributing the load change over time and angle
3Device complexity
If the locking element is fixed to the housing, then the structure is simple, but gear change under load cannot be performed reliably
Solution Approach 1:
The locking element is designed to rotate relative to the housing within a limited angular range, enabling it to dynamically adjust its position during gear changes. This rotational freedom allows the locking element to smoothly engage or disengage from the switching element even under load conditions, making gear changes reliable and operable without requiring tool shutdown
Solution Approach 2:
The locking mechanism is segmented into independently movable components: the locking element that can rotate relative to the housing, and the switching element that transmits rotational motion. This segmentation allows the locking element to independently adjust its angular position to facilitate smooth gear changes under various operating conditions
Data Source
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AI summary
The invention relates to a hand-held power tool comprising a shiftable gearbox (4) having at least two gear steps which are to be selected by means of an adjustable shift element (11). In a first gear step, the shift element (11) with a stop element (12) is in a stop position and in a second gear step in a non-stop position. Said stop element (12) is mounted in rotation in the housing (3) inside a defined angular section between two end stop positions.