Rack-and-Pinion Steering End Stop Damping Assembly
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Solution Overview
Problem
Existing rack and pinion steering systems face challenges with end stop damping assemblies that are either too hard due to steep characteristic curves, leading to component stress and potential damage, or too soft due to series connections of elastic compression bodies, resulting in excessive space requirements and manufacturing complexity.
Innovation Solution
A simplified end stop damping assembly with a compression body having a spring/damping section between two contact surfaces, where the axial length of the spring/damping section is greater than the guide extension, allowing for freer deformation options and incorporating a stop ring to fix the guide bushing axially in the rack housing, thereby simplifying the design and assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the end stop damping assembly uses a compression body completely encapsulated in the damping assembly, then the damping assembly has a compact structure, but the compression body has restricted deformation options resulting in a very steep characteristic curve and hard end stop
Solution Approach 1:
The patent extracts the compression body from complete encapsulation and allows it to extend freely beyond the guide bushing. This extraction enables the compression body to have greater deformation freedom while maintaining a compact overall structure through the guide bushing's containment function.
Solution Approach 2:
The patent implements dynamic deformation capability by allowing the compression body to extend axially beyond the guide bushing's outer surface. This dynamic configuration enables the compression body to deform more freely under load, transitioning from a restricted to an unrestricted deformation state that produces a softer end stop characteristic.
2Strength
If the end stop damping assembly uses series connection of elastic compression bodies, then the end stop becomes very soft with large deformation path, but the damping assembly requires large space and has high manufacturing complexity
Solution Approach 1:
The patent merges the guide bushing and end stop damping assembly into a single integrated component. The guide bushing simultaneously serves as a structural support element and a container for the compression body, eliminating the need for separate series-connected compression bodies and intermediate stabilizing elements, thereby reducing manufacturing complexity.
Solution Approach 2:
The guide bushing is designed with multi-functionality: it guides the rack axially, provides structural support, contains the compression body, and its outer surface serves as a reference for the stop ring positioning. This universal design replaces multiple separate components, reducing both space requirements and manufacturing complexity.
3Ease of manufacture
If the stop ring is arranged to fix the guide bushing axially in the rack housing, then the assembly is simplified and requires fewer separate fastening components, but the guide bushing must accommodate minimal relative movement due to manufacturing tolerances
Solution Approach 1:
The patent uses parameter adjustment in the form of axial offset positioning of the stop ring relative to the guide bushing. The stop ring is positioned at a specific axial distance from the guide bushing's end face, creating a controlled play or clearance that accommodates manufacturing tolerances while maintaining assembly simplicity.
Solution Approach 2:
The axial offset arrangement of the stop ring provides beforehand cushioning for manufacturing tolerance variations. The designed clearance or play between the stop ring and guide bushing anticipates and accommodates dimensional variations, preventing binding or excessive stress while maintaining the simplified assembly structure.
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
The solution provides a balanced damping characteristic, reducing component stress, simplifying installation, and minimizing space and manufacturing complexity while ensuring effective damping and fastening of the guide bushing, thus enhancing the overall performance and reliability of the rack and pinion steering system.
Implementation Method 1
an axially displaceable toothed rack (20) between two end stops, with an end stop damping assembly (30) having two stop rings (34, 36) and an elastic compression body (38) The spring/damping section of the compression body (38) has an axial length (x1) which is greater than the axial length (x2) of the guide extension (40)
Implementation Method 2
the stop ring (36) fixes the guide bushing (44) axially in the rack housing (32)
Implementation Method 3
a guide bushing (44), which serves to guide the displaceable toothed rack (20) and is arranged in a recess (46) of the toothed rack housing (32)
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a rack-and-pinion steering (10), comprising a toothed rack (20) having a longitudinal axis (X), a toothed rack housing (32) in which the toothed rack (20) is axially displaceably guided between two limit stops, and a limit stop damping assembly (30) comprising at least one stop ring (34, 36) and at least one elastic compression body (38), wherein the compression body (38) surrounds the toothed rack (20) and the spring/damping section thereof has an axial length (x1) in a non-loaded state. The stop ring (34, 36) comprises a circumferential axial guide extension (40) located on the radial inside with respect to the compression body (38), said extension having an axial length (x2) that is smaller than the axial length (X1) of the spring/damping section of the compression body (38).