Steering Bearing Fixing Structure for Stable Internal Clearance
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Solution Overview
Problem
Conventional steering devices with rolling-element bearings face variations in internal clearance due to frictional forces, leading to inconsistent preload and potential misalignment, which affects the performance and reliability of the steering mechanism.
Innovation Solution
The steering device incorporates a double row angular contact ball bearing with split races and a fixing structure that applies a consistent axial load to the rolling elements, ensuring a predetermined internal clearance by integrating the split races with the ball screw nut and using a holding member or snap ring to secure the inner ring, thereby reducing variations and misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a lock nut is used to fasten the first split race to the ball screw nut, then the rolling-element bearing can be preloaded, but the fastening position may change due to frictional force variations, causing internal clearance variations
Solution Approach 1:
The first split race is integrated with the ball screw nut as a single component, eliminating the need for a separate lock nut. This merging of parts removes the interface where frictional force variations could cause fastening position changes, thereby ensuring consistent preload and internal clearance across all manufactured units.
2Ease of manufacture
If the lock nut is tightened with constant torque, then assembly is simplified, but frictional force variations still cause changes in fastening position and load distribution
Solution Approach 1:
By combining the first split race and ball screw nut into one integrated component, the patent eliminates the fastening operation entirely. This resolves the contradiction by removing the source of frictional variability while maintaining assembly simplicity, as no lock nut tightening is required.
3Reliability
If a double row angular contact ball bearing is used, then the rotating member can be rotationally supported, but the structure becomes complex with multiple components including split races and lock nuts
Solution Approach 1:
The patent reduces device complexity by integrating the first split race with the ball screw nut into a single component. This merging eliminates the lock nut and flange member from the assembly, reducing the total part count while maintaining the rotational support capability of the double row angular contact ball bearing.
Solution Approach 2:
The integrated first split race-ball screw nut component performs multiple functions simultaneously: it provides the raceway for rolling elements, serves as the mounting structure for the bearing, and eliminates the need for separate fastening components. This multi-functionality reduces overall device complexity.
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 internal clearance of the rolling-element bearing, enhancing the consistency and reliability of the steering mechanism by preventing preload variations and misalignment, and reducing the number of parts required.
Implementation Method 1
a ball screw mechanism that converts a rotation of the rotating member into a reciprocating motion of the rack shaft by a ball screw mechanism
Implementation Method 2
a fixing structure configured to fix the rolling-element bearing to an outer periphery of the rotating member in a state where a load in the axial direction is applied to the first split race, the first rolling elements, the outer ring, the second rolling elements, and the second split race
Implementation Method 3
a ball screw mechanism that converts a rotation of the rotating member into a reciprocating motion of the rack shaft
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
A steering device includes a rolling-element bearing (71) that rotationally supports a rotating member (61) in a housing (14 ). The rolling-element bearing includes an inner ring (72), an outer ring (73), first rolling elements (74), and second rolling elements (75). The first rolling elements and second rolling elements are disposed in parallel in the axial direction between the inner ring and the outer ring. The inner ring includes a first split race having a first inner peripheral track surface and a second split race having a second inner peripheral track surface. The steering device further includes a fixing structure configured to fix the rolling-element bearing to the outer periphery of the rotating member in a state where a load is applied to the first split race, the first rolling element, the outer ring, the second rolling element, and the second split race.