Shaft-Hub Recess Geometry for Compact Torque Transmission
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Solution Overview
Problem
Existing shaft-hub connections require materials suitable for welding, which have corrosion resistance issues and necessitate pre-cleaning, and occupy significant installation space, limiting their application in electrical actuators like electric brake boosters.
Innovation Solution
A shaft design with recesses featuring radial and axial walls, optimized for torque and axial force transmission, and a hub with convex sections, allowing for a secure, compact, and cost-effective connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a weld seam is used to connect the shaft to the hub, then the connection can transmit torque and axial force, but the corrosion resistance deteriorates and additional manufacturing steps are required
Solution Approach 1:
The patent replaces the weld-based mechanical connection system with a press-fit mechanical connection system. The hub is pressed onto the shaft with interference fit, and the keyway-key connection transmits torque. This eliminates welding entirely, avoiding corrosion issues while maintaining strong mechanical connection for torque and axial force transmission.
Solution Approach 2:
The invention extracts and removes the welding process from the shaft-hub connection system. By using a press-fit connection with keyway, the patent eliminates the harmful welding step while achieving the same functional goals of torque and axial force transmission without compromising corrosion resistance.
2Strength
If a weld seam is used to connect the shaft to the hub, then the connection can transmit torque and axial force, but the manufacturing complexity increases due to cleaning requirements
Solution Approach 1:
The patent replaces the weld-based mechanical connection system with a press-fit mechanical connection system. The hub is pressed onto the shaft with interference fit, and the keyway-key connection transmits torque. This eliminates welding entirely, avoiding corrosion issues while maintaining strong mechanical connection for torque and axial force transmission.
Solution Approach 2:
The invention extracts and removes the welding process from the shaft-hub connection system. By using a press-fit connection with keyway, the patent eliminates the harmful welding step while achieving the same functional goals of torque and axial force transmission without compromising corrosion resistance.
3Volume of moving object
If a compact shaft-hub connection is designed, then the installation space is reduced, but the stress concentration increases at contact surfaces
Solution Approach 1:
The patent applies curvature by providing a transition radius at the transition from the radial recess wall to the axial recess wall. This rounded transition eliminates sharp corners that would cause stress concentration, distributing stress more evenly across the contact surfaces while maintaining the compact recess design for space-efficient connection.
Solution Approach 2:
The invention applies different geometric properties to different regions: the recess walls provide compact geometry for space efficiency, while the transition radius provides stress-distributing curvature at the critical transition zone. This local differentiation optimizes both space utilization and stress distribution.
4Object-affected harmful factors
If a press-fit connection without welding is used, then the corrosion resistance is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent segments the connection function into two independent elements: the press-fit connection for axial positioning and force transmission, and the keyway-key connection for torque transmission. This segmentation allows each element to be optimized independently, with the keyway providing precise angular positioning that compensates for variations in press-fit dimensional tolerances.
Solution Approach 2:
The invention creates a composite connection system combining press-fit interference connection and keyway mechanical engagement. This composite approach distributes the functional requirements across two mechanisms, reducing the precision burden on any single element while achieving reliable torque and axial force transmission.
Data Source
Figure 1a~1b
Figure 2a~2c
Figure 3~4
AI summary
Shaft (10), for transmitting a torque and/or an axial force, comprising a longitudinal shaft axis (12), a shaft surface (14) and a shaft end (16), wherein the shaft surface (14) has at least one recess (18) with an axial recess wall (20) and a radial recess wall (22) adjoining the axial recess wall (20), wherein the at least one recess (18) is open axially in the direction of the shaft end (16), and wherein the radial recess wall (22) has a recess radius (28) such that the radial recess wall (22) has at least a concave recess arc shape facing away from the longitudinal shaft axis (12) in sections, and hub (48) with a hub longitudinal axis (50), wherein at least one hub arc section (56) has a convex shape facing the longitudinal hub axis (50). has hub arch shape, shaft-hub connection (68) with a shaft (10) and a hub (48),as well as an electric actuator with a shaft-hub connection (68) .,