Shift-by-Wire Rotary Actuator Pin Structure for Sun Gear Accuracy
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Solution Overview
Problem
Existing rotary actuators for shift-by-wire systems in vehicles face issues with positional accuracy, strength, and wear of the regulating pin due to its integral formation with the fixing member, leading to potential mechanical failures and efficiency losses.
Innovation Solution
A rotary actuator design where the regulating pin is a separate member from the fixing member, with a strength equal to or greater than the maximum torque reaction force and a hardness difference set to prevent wear, allowing it to effectively restrict the sun gear's motion while maintaining positional accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the regulating pin is integrally formed with the fixing member as a single component, then the device complexity is reduced, but the positional accuracy and strength of the regulating pin deteriorate
Solution Approach 1:
The regulating pin is separated from the fixing member into two independent components. The regulating pin can be independently manufactured and installed into the fixing member, allowing precise control of its position and orientation. This segmentation resolves the contradiction by prioritizing positional accuracy over structural simplicity.
2Ease of manufacture
If the regulating pin is integrally formed with the fixing member, then the manufacturing process is simplified, but the strength and wear resistance of the regulating pin deteriorate
Solution Approach 1:
The regulating pin is made from a material with different properties (higher hardness) than the fixing member. This local quality differentiation allows the regulating pin to have superior wear resistance and strength at the engagement point with the sun gear, while the fixing member maintains its structural function. The hardness difference prevents wear and mechanical failure.
3Duration of action of stationary object
If the regulating pin has high hardness to prevent wear, then the wear resistance improves, but the risk of damaging the sun gear increases
Solution Approach 1:
The hardness parameter of the regulating pin is optimized to be higher than the sun gear material, creating a controlled hardness difference. This parameter change ensures the regulating pin resists wear from the sun gear while the separate member design and controlled hardness differential prevent excessive hardness that would damage the gear.
Data Source
AI summary
A rotary actuator is used in a shift-by-wire system for a vehicle. A speed reducer includes a ring gear and a sun gear and reduces a rotational speed of the motor. An output shaft outputs rotation of the motor at a reduced rotational speed by the speed reducer. A regulating pin is disposed in a fixing member and allows the sun gear to revolve around a rotational axis of the motor and to rotate about an eccentric axis. The regulating pin is a separate member from the fixing member. The regulating pin has a strength equal to or greater than a maximum torque reaction force received from the sun gear. A first difference in hardness between an engaging portion and the sun gear is set to be less than a second difference in hardness between the fixing member and the sun gear.