Rack-and-Pinion End Stop Damping Assembly Torsional Load Management
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Solution Overview
Problem
Rack-and-pinion steering systems experience significant wear and reduced service life due to torsional stresses at the end stop, primarily affecting the compression body, which is less robust than the stop member, leading to premature wear and frequent replacements.
Innovation Solution
The stop member is mounted between two opposite supporting surfaces of the rack housing, providing a maximum damping travel and ensuring reliable fastening, while being designed to absorb torsional loads, thus reducing the stress on the compression body and prolonging the service life by preventing rotation and distributing torsional moments to the more robust stop member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the compression body is used to dampen the end stop, then the end stop damping function is achieved, but the compression body is subjected to high torsional stresses leading to wear and reduced service life
Solution Approach 1:
The stop member acts as an intermediary between the rack and the compression body. It receives the torsional loads from the rack and transfers them to the rack housing, preventing these harmful torsional stresses from being transmitted to the compression body. The stop member thus mediates the force transmission path to protect the more sensitive compression body while maintaining the damping function.
Solution Approach 2:
The end stop damping assembly is segmented into distinct functional components: the stop member handles torsional loads and positioning, while the compression body handles only axial damping. This segmentation allows each component to be optimized for its specific function, with the stop member being robust against torsion and the compression body providing elastic damping without excessive torsional stress.
2Reliability
If the stop member is mounted for limited displacement between two supporting surfaces, then the maximum damping travel is defined and reliable fastening is ensured, but the structure becomes more complex
Solution Approach 1:
The stop member serves multiple functions simultaneously: it acts as a stop for the rack, provides axial positioning of the compression body, defines the maximum damping travel, and transfers torsional loads to the rack housing. By combining these functions into a single component, the overall structure is simplified despite the increased functional requirements.
Solution Approach 2:
The stop member merges the stop function and the fastening function into a single component. Instead of having separate elements for stopping the rack and for securing the damping assembly, the stop member integrates both functions, reducing the number of parts while improving reliability.
3Duration of action of stationary object
If the stop member absorbs torsional loads, then wear on the compression body is reduced, but the stop member must be designed to withstand these loads
Solution Approach 1:
The stop member is designed as a robust structural element that copies the load-bearing functions of traditional end stop designs, while the compression body provides the damping function. This allows the stop member to be optimized for strength and torsional resistance based on proven designs, while the compression body can be a simpler elastic element.
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 design significantly reduces wear on the compression body, extends the service life of the end stop damping assembly, and minimizes the risk of damage to the rack-and-pinion steering system by effectively managing torsional and axial loads, ensuring reliable operation and reduced maintenance intervals.
Implementation Method 1
a compression body (34) for damping an end stop (62)
Implementation Method 2
the stop member (36) includes detent elements (48) and produces a detent connection with the rack housing (30)
Data Source
AI summary
A rack-and-pinion steering for a motor vehicle, having a rack which has a longitudinal axis, a rack housing in which the rack is guided for axial displacement, and at least one end stop damping assembly for the rack, the end stop damping assembly being received in the rack housing, the end stop damping assembly including a compression body for damping an end stop and a stop member which is mounted to the rack housing for limited displacement in the axial direction, the stop member resting against a first supporting surface of the rack housing at least partly by means of the compression body in a first axial direction and resting against a second supporting surface of the rack housing in an opposite, second axial direction.