Ratchet Wrench Axis Fixing Device for Torque Transmission
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Solution Overview
Problem
The existing power-driven wrenches face issues with concentricity errors during the drilling process of the central axial bore, leading to misalignment of the drive shaft and socket member, which results in incomplete torque transmission and premature damage due to the elongated housing design causing bending of drilling bits and deviation of the bore axis.
Innovation Solution
A ratchet wrench design incorporating an axis fixing device with a transmission groove and axial hole, where the axis fixing device is mounted between the driving hole and transmission hole, ensuring the gear rotates perpendicular to the drive shaft axis, even if the bore is not perfectly aligned, thus maintaining torque transmission and extending the tool's lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the housing is designed with an elongated outline to accommodate the central axial bore, then the bore drilling can be performed, but the drilling bit bends due to excessive length-to-diameter ratio, causing the bore axis to deviate from the housing axis and resulting in excessive concentricity error
Solution Approach 1:
The invention divides the housing into multiple segments: the main housing body and an elongated extension portion. The central axial bore is formed only in the main housing body, not extending through the entire elongated structure. This segmentation allows the bore to be drilled with a shorter bit while still achieving the desired elongated housing shape for torque transmission, thereby resolving the contradiction between bore precision and housing length requirement.
2Ease of manufacture
If the central axial bore is drilled with a long drilling bit to accommodate the elongated housing, then the bore can be formed, but the bit flexes during drilling, increasing bore diameter error and causing axis deviation
Solution Approach 1:
The housing is segmented into a main body and an extension portion, with the bore formed only in the main body. This eliminates the need to drill through the entire elongated structure, using a shorter bit that does not flex excessively, thereby maintaining bore diameter accuracy while still achieving the elongated housing design for torque transmission.
3Strength
If the drive shaft is mounted in the deviated central axial bore, then the housing structure is maintained, but the rotating axis of the drive shaft is not perpendicular to the socket member axis, preventing smooth meshing of gear teeth and complete torque transmission
Solution Approach 1:
The housing is divided into a main body containing the precisely formed central axial bore and an extension portion that provides elongation without requiring bore extension. The drive shaft is mounted only in the main body portion where the bore maintains high precision and perpendicularity, ensuring complete torque transmission while the extension portion contributes to the overall elongated shape for mechanical advantage.
4Ease of operation
If the central axial bore is processed with grooves for bearings, then the drive shaft can be mounted, but concentricity error between the bore and grooves prevents smooth rotation and complete torque transmission
Solution Approach 1:
The housing is segmented into a main body with the central axial bore and bearing grooves, and an extension portion. By limiting the bore and groove processing to the main body portion, the concentricity between bores and grooves can be maintained at high precision levels, ensuring smooth drive shaft rotation and complete torque transmission, while the extension portion provides the necessary elongation without compromising precision.
Data Source
AI summary
A ratchet wrench includes a body having a head and a shank interconnected to the head. The head includes a driving hole extending along a first axis and receiving a driving device. The shank includes a transmission hole receiving a transmission shaft. An axis fixing device is mounted in a transmission groove between the driving hole and the transmission hole and includes an axial hole extending through the axis fixing device along a second axis that extends perpendicularly to and intersects with the first axis. A gear coupled to the driving device is received in the axial hole and is rotatable about the second axis. A driving end of the transmission shaft extends into the axial hole and is connected to the gear.