Off-Centre Steering Yoke Toroidal Pad Noise Suppression
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Solution Overview
Problem
The existing eccentric push member devices in rack-and-pinion steering systems experience noise and kinematic disturbances due to relative sliding and rolling movements between the rotating pad and its support, especially when load direction and amplitude change.
Innovation Solution
The design features an arcuate rotating pad with a cylindrical outer periphery and a cradle that bear on each other along two spaced contact lines parallel to the axis of rotation, eliminating rolling movements by positioning the force direction between these contact lines, ensuring symmetrical contact and stable force transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the rotating pad and cradle are both cylindrical with relative sliding movement, then the structure is simple and easy to manufacture, but rolling movements occur due to manufacturing clearances causing noise and kinematic disturbances
Solution Approach 1:
The invention replaces the cylindrical outer periphery of the rotating pad with a toroidal (doughnut-shaped) curvature. This toroidal shape allows the pad to contact the cradle along two parallel contact lines instead of a single line or point, eliminating rolling movements while maintaining smooth curvature for ease of manufacture. The toroidal geometry inherently prevents rolling by distributing contact across two lines, thus resolving the contradiction between manufacturing simplicity and noise elimination.
2Object-affected harmful factors
If the outer periphery of the rotating pad bears on the cradle along two spaced contact lines, then rolling movements are eliminated and noise is suppressed, but the manufacturing precision requirements increase
Solution Approach 1:
The toroidal curvature of the rotating pad's outer periphery creates two naturally formed contact lines with the cradle. The geometry of the torus inherently defines these contact lines through its surface curvature, reducing sensitivity to manufacturing tolerances. Instead of requiring precise positioning of contact lines through tight tolerances, the toroidal shape allows the contact lines to emerge naturally from the geometric interaction between the pad and cradle, thus achieving noise suppression without excessive precision requirements.
Solution Approach 2:
The invention changes the geometric parameters of the rotating pad from a cylindrical shape with a single contact line to a toroidal shape with two contact lines. This parameter change (from radius R to major radius R1 and minor radius R2) fundamentally alters the contact mechanics, transforming the contact from a line or point to two distributed lines. This parameter transformation reduces the system's sensitivity to manufacturing variations while maintaining the noise suppression benefit.
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 suppresses noise and improves the kinematics of the clearance compensation mechanism, maintaining effective engagement of the rack and pinion teeth without rolling movements, enhancing the overall performance of the steering system.
Implementation Method 1
a compression spring inserted between the pusher and a fixed support of the pad
Implementation Method 2
The movable stop is connected via a torsion spring to the support or to the element integral with the support
Implementation Method 3
a movable part forming a friction pad, guided in translation and biased by resilient means toward the back of the rack
Data Source
AI summary
The invention relates to a yoke device which includes a rotary pad (10), the inner periphery (11) of which is off-center relative to the outer periphery (12), clamped against the rear of the rack, and thus pushed toward the teeth of the steering pinion. The rotary pad (10) engages, via the outer periphery thereof (12), with an arcuate cradle (14) of a mounting (13) mounted in the steering gearbox, said pad being biased and rotatably positioned by a clearance-compensation mechanism having a spring means. The outer periphery (12) of the pad and the cradle (14) engage with one another following two contact lines (20, 21) which are spaced apart, parallel to the axis of rotation of the pad.