Tapered Lobular Driver for Multi-Size Fastener Engagement
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Solution Overview
Problem
Existing torque transmission drivers are limited in their ability to efficiently drive multiple sizes of fasteners without cam-out, leading to inefficiencies and increased misinstallation, particularly with small fasteners, due to their design limitations and the need for multiple drivers for different sizes.
Innovation Solution
A torque transmission driver with a tapered bit featuring alternating lobes and troughs with a taper angle between 15° and 65°, allowing engagement with at least two sizes of fasteners, and a drive side transition angle that reduces the likelihood of cam-out, enabling a single driver to effectively torque multiple fastener sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dedicated driver for each fastener size is used, then the driver can effectively drive that specific size without cam-out, but the device complexity and inventory requirements increase
Solution Approach 1:
The driver bit is designed with a tapered geometry that allows a single driver to engage multiple fastener sizes. The taper angle (15°-65°) enables the driver to self-align and maintain proper engagement across different fastener diameters, making one driver universal for multiple sizes rather than requiring dedicated drivers for each size
2Device complexity
If a single driver is used for multiple fastener sizes, then the device complexity is reduced, but the driver cam-outs from small fasteners leading to misinstallation
Solution Approach 1:
The driver incorporates a specific taper angle parameter (15°-65° from the rotational axis) that changes the engagement geometry. This parameter allows the driver to maintain optimal contact pressure and alignment across different fastener sizes, preventing cam-out even when driving smaller fasteners with a universal driver
3Power
If traditional spline-type drive systems are used, then the drive angle can be increased to 10°-20° for higher torque capacity, but the lobe drive angle cannot be retained less than five degrees causing force components to rise and lead to lobe failure
Solution Approach 1:
The patent optimizes the taper angle parameter to fall within 15°-65° from the rotational axis, which balances the torque transmission capability with the structural integrity of the lobe engagement. This parameter range allows sufficient torque capacity while maintaining a small enough drive angle to prevent excessive force components that would cause lobe failure
Data Source
Figure 1A~1D
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Figure 6~7
AI summary
A torque transmission driver has a first end portion adapted to receive and transmit torque from a torque generation source, and a second end portion including a shaped tapered bit having drive surfaces with an alternating series of five or six lobes and troughs about a rotational axis, having a taper angle between 15 and 65 from the rotational axis operable to engage corresponding drive surfaces in a plurality of at least two size fasteners, the tapered drive surfaces of the bit comprising a first tapered portion operable to engage drive surfaces of a first sized fastener and a second tapered portion operable to engage drive surfaces of a second sized fastener, the drive surfaces of the second sized fastener being larger than the drive surfaces of the first sized fastener. The taper angle may be nominally 52 from the rotational axis.