Ball-Type Latching Clutch for Reliable Power Tool Mode Switching
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Solution Overview
Problem
Existing hand-held power tools face issues with unreliable operation due to coupling balls failing to return to their intended position after a safety stop, leading to a loss of axial adjustment capability and potential damage to transmission components.
Innovation Solution
Incorporating an auxiliary depression in the guide tube with a larger opening angle than the main latching depression, along with a spring-loaded cone ring and specific cone shoulder configurations, ensures the coupling ball has a defined position, allowing axial adjustment of the function setting tube and preventing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the coupling ball is engaged in the main latching depression for torque transmission, then the function setting tube can be axially adjusted for various operating modes, but the coupling ball may fail to return to its intended position after a safety stop, causing loss of axial adjustment capability
Solution Approach 1:
The guide tube is segmented into multiple functional zones: the main latching depression for torque transmission and the auxiliary depression for safety positioning. This segmentation allows the coupling ball to have distinct functions for normal operation and safety stop scenarios, ensuring it returns to the correct position after a safety stop and maintains axial adjustment capability.
Solution Approach 2:
The auxiliary depression acts as an intermediary positioning element between the main latching depression and the coupling ball. When the coupling ball is displaced during a safety stop, the auxiliary depression provides an intermediate defined position that allows the function setting tube to be repositioned axially, mediating the return to operational state.
2Strength
If the main latching depression has a small opening angle for secure engagement, then torque transmission is reliable, but the coupling ball cannot be easily positioned or returned to the correct position after displacement
Solution Approach 1:
Different regions of the guide tube are given different local qualities: the main latching depression has a small opening angle (70-80 degrees) for secure torque transmission engagement, while the auxiliary depression has a larger opening angle (>90 degrees, preferably >120 degrees) for easy positioning and safety stop functionality. This local differentiation optimizes both torque transmission reliability and positioning ease.
3Strength
If the spring-loaded cone ring provides sufficient actuating force to prevent coupling ball displacement, then transmission component damage is prevented, but the function setting tube cannot be axially adjusted when torque exceeds the actuating force
Solution Approach 1:
The system dynamically adapts to varying torque conditions through the interaction between the spring-loaded cone ring and the two depressions. Under normal operation, the coupling ball engages the main latching depression for torque transmission. When torque exceeds the spring's actuating force, the coupling ball can be displaced to the auxiliary depression, which then provides a defined position allowing axial adjustment while still protecting against component damage.
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 enhances the reliability of hand-held power tools by ensuring consistent axial adjustment and reducing the risk of transmission component damage, even when torque exceeds the spring-loaded cone ring's actuating force.
Implementation Method 1
a spring-loaded cone ring. The coupling ball can deflect in the radial direction, with respect to the guide tube, against an actuating force of the spring-loaded cone ring
Data Source
AI summary
Electric hand-held power tool, in particular a hammer drill and/or rotary hammer, having a function setting tube, which can be actuated via a manual function selector switch to bring about various operating modes, a guide tube equipped with a tool fitting, and having a ball-type latching clutch for transmitting a rotary movement from the function setting tube to the guide tube, wherein the ball-type latching clutch has a radial aperture formed in the function setting tube, a main latching depression formed in the guide tube, a coupling ball mounted in the radial aperture and intended to engage in the main latching depression, and a spring-loaded cone ring against whose actuating force the coupling ball can deflect in the radial direction, wherein the guide tube has formed therein an auxiliary depression that is different from the main latching depression and whose opening angle is larger than an opening angle of the main latching depression.