Torque Coupling Locking Mechanism for Drill-Driver Mode Switching
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Solution Overview
Problem
Existing hand-held power tools, such as drills and screwdrivers, face challenges in reliably switching between drilling and screwing modes due to indirect axial blocking of the pressure plate, which can lead to overlocking of the torque clutch in drilling mode, requiring improved mechanisms for torque clutch activation and deactivation with reduced actuation forces and axial space.
Innovation Solution
A hand-held power tool design featuring a torque clutch with a blocking element, such as a blocking ring, secured against rotation, that allows for reliable activation and deactivation with minimal forces and space, enabling three operating modes: screwing, drilling, and percussion drilling, by limiting axial displaceability and using a planetary gear with locking cams and compression springs for torque limitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If indirect axial blocking of the pressure plate via spring retainer is used, then the torque clutch can be deactivated in drilling mode, but reliable blocking is limited and overlocking may occur
Solution Approach 1:
A blocking element is introduced as an intermediary component between the transmission element and the pressure plate. This blocking element directly blocks the pressure plate axially when engaged, eliminating the indirect blocking path through the spring retainer and preventing overlocking while maintaining simple overall structure
Solution Approach 2:
The blocking function is segmented from the spring retainer system. The blocking element operates independently to provide direct axial blocking, while the spring retainer maintains its tensioning function, allowing each component to perform its specific function reliably without interfering with the other
2Ease of operation
If axial displaceability of the transmission element is increased for torque clutch activation, then the torque clutch can be activated, but larger axial space and actuating forces are required
Solution Approach 1:
The blocking element is designed to be axially displaceable relative to the transmission element, allowing it to engage and disengage dynamically. This dynamic blocking mechanism enables torque clutch activation with minimal axial movement of the transmission element itself, reducing the required axial space and actuating forces
Solution Approach 2:
The blocking action is achieved through axial displacement of the blocking element rather than requiring large axial movement of the transmission element. This dimensional approach to blocking allows compact design while maintaining ease of 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 a robust, low-wear, and compact torque clutch system that prevents overlocking, allowing safe and reliable operation in multiple modes with precise torque control, ensuring reliable switching between screwing and drilling modes and enabling impact drilling functionality.
Implementation Method 1
the transmission element is axially prestressed against the ring gear by means of at least one compression spring
Implementation Method 2
the gear is designed in the manner of a planetary gear, with at least one latching cam being formed on a ring gear of a gear stage of the planetary gear facing the torque clutch
Implementation Method 3
at least one latching cam being formed on a ring gear of a gear stage of the planetary gear facing the torque clutch
Data Source
Figure 1
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AI summary
In a hand-held power tool (10), in particular a screwdriver or drill/driver, with a gearbox (20) arranged in a gearbox housing (24) for driving an output spindle (42), and with a torque coupling (40) associated with the output spindle (42), wherein a transmission element (58) axially displaceable in the direction of a longitudinal center axis (46) of the output spindle (42) is provided, a locking element (60) is provided which is axially immovable in the direction of the longitudinal center axis (46) and movable in a plane (64) arranged transversely to the longitudinal center axis (46) for activating and deactivating the torque coupling (40), and which is designed toto enable axial displacement of the transmission element (58) in the direction of the longitudinal center axis (46) in at least one first operating position for the purpose of activating the torque coupling (40) and to at least limit the axial displacement of the transmission element (58) in the direction of the longitudinal center axis (46) in at least one second operating position, wherein the output spindle (42) is at least substantially immobile axially in the direction of the longitudinal center axis (46) relative to the gearbox housing (24) in the second operating position of the locking element (60).