Vehicle Seat Actuator Cap Structure for Stable Thrust Bearing Pressure
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electric actuators in vehicle seats face issues with excessive contact surface pressure between the shaft and thrust bearing due to high fastening torque, leading to significant drive power loss.
Innovation Solution
The electric actuator incorporates a radial bearing, thrust bearing, housing, and cap configuration with slanting surfaces and serrated engagement portions to prevent rotation of the thrust bearing, thereby maintaining stable contact pressure and reducing the need for excessive fastening torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fastening torque of the adjustment screw is increased to prevent loosening, then the reliability of the thrust bearing position is improved, but the contact surface pressure between the shaft and thrust bearing becomes excessively high, causing drive power loss
Solution Approach 1:
The adjustment mechanism is segmented into multiple functional components: the adjustment screw for axial positioning, the cap for rotational restriction, and the engagement portions for securing the thrust bearing. This segmentation allows each component to perform its specific function independently, preventing thrust bearing displacement without requiring excessive fastening torque that would increase contact pressure.
Solution Approach 2:
The cap is preliminarily positioned on the thrust bearing before final assembly, with its engagement portions already configured to restrict rotation. This preliminary action ensures that the thrust bearing cannot rotate during assembly or operation, maintaining stable contact pressure without requiring high fastening torque to prevent loosening.
2Ease of operation
If the thrust bearing is allowed to rotate during cap insertion, then the ease of operation is improved, but the thrust bearing displacement occurs, causing unstable contact pressure
Solution Approach 1:
The engagement portions are designed with asymmetric geometry where the cap's outer circumferential engagement portion fits into the housing's inner circumferential engagement portion in a specific rotational orientation. This asymmetric design automatically prevents thrust bearing rotation during cap insertion while maintaining ease of operation, as the asymmetric features guide proper alignment and engagement.
Solution Approach 2:
The cap serves as an intermediary component between the housing and thrust bearing, with its engagement portions mediating the rotational restriction. The cap's outer engagement portion interfaces with the housing, while its inner engagement portion interfaces with the thrust bearing, thereby preventing thrust bearing rotation without requiring direct constraint mechanisms that would complicate insertion.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration stabilizes the performance of the electric actuator by preventing excessive contact surface pressure and drive power loss, ensuring consistent operation by controlling the rotational direction and displacement of the thrust bearing.
Implementation Method 1
a slanting surface is provided to at least one of a leading end of the outer circumferential engagement portion in an insertion direction of the cap or a part of the engagement target portion adjacent to the insertion port. The slanting surface slants to an imaginary line parallel to the rotation center axis. The slanting surface is configured to generate a rotational force that rotates the cap in a specific direction about the rotation center axis as the cap is inserted along the rotation center axis.
Implementation Method 2
The cap is provided with, on an outer circumferential surface thereof, an outer circumferential engagement portion engaged with an engagement target portion provided to an inner circumferential surface of the housing. The cap is provided with, on an inner circumferential surface thereof, an inner circumferential engagement portion engaged with the thrust bearing.
Data Source
AI summary
An electric actuator of the present disclosure includes an electric motor, a shaft, and a gear, and further includes a radial bearing supporting the shaft, a thrust bearing restricting a displacement of the shaft, a housing including a housing portion that houses the thrust bearing, and a cap inserted in the housing portion. The cap has a cylindrical shape and restricts a rotation of the thrust bearing. A slanting surface is provided to at least one of a leading end in an insertion direction of an outer circumferential engagement portion of the cap or a part adjacent to the insertion port in an engagement target portion. The slanting surface is configured to generate a rotational force that rotates the cap in a specific direction as the cap is inserted in the housing portion.