Reinforced Handle Assembly Torque Redirection
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Solution Overview
Problem
Conventional door lock handle assemblies suffer damage due to stress concentration and breakage of the outside spindle when the handle is turned through a predetermined angle, as the existing clutch mechanisms do not effectively distribute torque, leading to impact on the weak coupling area.
Innovation Solution
A reinforced handle assembly is designed with a hub having angularly spaced protrusions, a rotatably mounted spindle, and a transmission member that includes a stop to prevent further rotation and distribute torque to the hub, reducing stress on the spindle by allowing the handle to impart torque directly to the hub rather than the spindle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the outside handle is allowed to rotate freely when locked to prevent damage to inner parts, then the clutch mechanism enables free rotation, but the spindle and coupling area suffer stress concentration and breakage after predetermined angle rotation
Solution Approach 1:
The transmission member is segmented into distinct functional zones: an engaging portion that couples with the handle, a stop that interacts with hub protrusions, and keys that engage with spindle coupling grooves. This segmentation allows different parts of the transmission member to handle different aspects of torque management, preventing stress concentration in any single area including the spindle and coupling region.
Solution Approach 2:
The transmission member acts as an intermediary element between the handle and the spindle. It includes keys that engage with coupling grooves on the spindle, and a stop that interacts with protrusions on the hub. This intermediary structure distributes and redirects torque through multiple engagement points, preventing direct stress transmission to the vulnerable spindle and coupling area while still enabling controlled free rotation when locked.
2Ease of operation
If holes are formed in the outside spindle for spring engagement, then the clutch mechanism can be implemented, but the spindle becomes weakened at the engagement location
Solution Approach 1:
The spring engagement function is extracted from the spindle structure itself and relocated to the transmission member. The transmission member includes a longitudinal hole through which the spindle extends, and the spring engages with features on the transmission member rather than requiring holes in the spindle. This extraction eliminates the weakening effect of holes in the spindle while maintaining the clutch mechanism's operational capability.
3Reliability
If the stop is designed to be stopped by hub protrusions after predetermined angle rotation, then torque distribution is improved, but the structure becomes more complex
Solution Approach 1:
The transmission member serves multiple functions within a single component: it couples the handle to the spindle through key engagement, provides the stop function to interact with hub protrusions for torque distribution, and includes the longitudinal hole for spindle passage. By combining these functions into one multi-functional transmission member rather than separate components, the structure achieves improved torque distribution without proportionally increasing device complexity.
Data Source
AI summary
A lock includes a handle, a hub, and a spindle rotatably mounted in the hub and coupled to the handle to turn therewith. A transmission member is fixed to the handle to turn therewith. The transmission member is mounted around and not rotatably engaged with the spindle. The transmission member is stopped by the hub after the handle has been turned through an angle, transmitting a torque from the handle to the hub via the transmission member. Thus, impact from the handle can be partly transmitted to the hub and then to a door on which the lock is mounted, instead of completely transmitted to the spindle. Damage to the spindle is, thus, avoided.