Eccentric Push Member for Rack-and-Pinion Steering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Eccentric pusher devices for rack-and-pinion steering systems face issues with inconsistent force application due to variable stresses and progressive rotation, leading to potential loss of contact between the leaf spring and the rack, which degrades the device's functionality.
Innovation Solution
The eccentric tappet device incorporates a rotary support with an eccentric internal periphery biased by spring means, mounted in a sliding housing perpendicular to the rack's plane, with additional damping spring means between the housing and the steering casing to stabilize and guide the rack, separating play compensation from straightness defect absorption, ensuring consistent force application and improved guidance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a leaf spring is mounted between the rotary support and the rack to compensate for straightness defects, then the rack can accommodate geometric defects, but the leaf spring loses contact with the rack under variable stresses and changes position over time, degrading device function
Solution Approach 1:
A sliding housing is introduced as an intermediary component between the rotary support and the rack. The housing provides a stable mounting surface for the leaf spring while allowing controlled sliding movement to accommodate rack straightness defects. This mediator prevents the leaf spring from losing contact with the rack under variable stresses, as the housing absorbs positional variations through its sliding capability in guided slots.
Solution Approach 2:
The device is segmented into distinct functional components: the rotary support for play compensation, the sliding housing for straightness defect absorption, and the leaf spring for controlled force application. This segmentation allows each component to perform its specific function optimally without interfering with others, preventing the leaf spring from changing position over time due to progressive rotation.
2Reliability
If the rotary support is allowed to rotate progressively to compensate for wear and assembly play, then play between pinion and rack teeth is taken up, but the orientation and intensity of forces applied to the rack vary over time, degrading function
Solution Approach 1:
The sliding housing acts as a mediator that decouples the rotational movement of the support from the linear movement of the rack. The housing slides in guided slots perpendicular to the rack's toothing plane, absorbing the rotational displacement while maintaining consistent force application orientation to the rack throughout the rotation cycle.
3Reliability
If the pusher device is made irreversible by design to prevent backtracking, then the device maintains steady pressure on the rack, but the degradation of irreversibility occurs over time due to component wear and position changes
Solution Approach 1:
The sliding housing with its guided slots provides beforehand cushioning for positional variations and wear. By accommodating movements in advance through controlled sliding, the system prevents degradation of the irreversible mechanism, maintaining its function throughout the device's operational lifespan despite component wear.
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 enhances the control of rack movements and positions, stabilizes the rotary support, and reduces degradation of the pusher device's irreversibility, providing better guidance and absorption of geometric defects, thus improving the overall operation of the eccentric tappet device.
Implementation Method 1
The support is biased in rotation in one direction by a spring (see in particular document FR 2 219 868 A cited above), so as to take up the play caused by the mounting inaccuracies and by the wear between the rack teeth and the pinion teeth.
Implementation Method 2
other damping spring means being arranged between the sliding housing and a fixed element, such as the steering casing, to act on said housing in its sliding direction.
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The push member device (1) of the present invention includes a rotatable mounting (4), the inner circumference (5) of which is eccentric relative to the outer circumference (6). The mounting (4) is rotationally biased in a direction by a spring (10) and is placed against the back of the rack (2) that is thus pushed against the teeth of the steering pinion. The rotatable mounting (4) is rotatably mounted in a housing (7), itself being slidably mounted in the steering gearbox. A shock absorbing spring means (11) is arranged between the sliding housing (7) and the steering gearbox to absorb the alignment defects of the rack (2).