Rack Guide Unit Frictional Holding for Steering Assembly
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Solution Overview
Problem
The existing rack guide units for rack-and-pinion-type steering systems require cumbersome assembly processes due to the need for snap rings to hold coned disc springs and intervening members, increasing the number of man-hours required and reducing assembly efficiency.
Innovation Solution
A rack guide unit design that includes a holding member frictionally engaged with the rack guide to secure coned disc springs, simplifying the assembly process by allowing the coned disc springs, holding member, and rack guide to be assembled as a single unit, with the holding member being directly or indirectly held by the rack guide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If snap rings are used to hold coned disc springs and intervening members in the plug, then the coned disc spring and intervening member can be securely held, but the assembly process becomes cumbersome and requires increased man-hours
Solution Approach 1:
The coned disc spring and holding member are extracted from the plug assembly and relocated to be installed directly on the rack guide. This removes the need for snap rings and the complex two-groove fitting process, while maintaining the securing function through frictional engagement between the holding member and rack guide.
Solution Approach 2:
The rack guide serves as an intermediary component that directly holds the coned disc spring assembly through the holding member. This eliminates the need for the plug to mediate the securing process, simplifying the assembly by allowing direct installation onto the rack guide without requiring snap rings.
2Reliability
If snap rings are fitted in both circumferential groove of plug and circumferential groove of intervening member, then the coned disc spring can be held securely, but the total number of man-hours needed to obtain subassembly increases
Solution Approach 1:
The coned disc spring assembly is extracted from the plug subassembly and repositioned to be mounted directly on the rack guide. This eliminates the need for the complex dual snap ring installation process involving both the plug and intervening member, reducing assembly time while maintaining secure holding through frictional engagement.
Solution Approach 2:
Instead of installing the coned disc spring assembly into the plug and securing it with snap rings, the approach is inverted by directly mounting the holding member with the coned disc spring onto the rack guide itself. This reverses the traditional assembly sequence and eliminates the need for snap rings entirely.
3Reliability
If coned disc spring is installed in series with compression coil spring in the plug, then impact load can be absorbed, but the assembly complexity increases due to multiple components
Solution Approach 1:
The coned disc spring and compression coil spring are merged into a single integrated assembly mounted on the rack guide, rather than being separately installed in the plug. The holding member secures both springs together, reducing assembly complexity while maintaining the combined impact absorption capability of both spring types.
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 enhances the efficiency of the rack guide unit assembly and the overall steering system by reducing the complexity of the assembly process and ensuring proper alignment and counteracting loads, allowing for smoother operation under high loads.
Implementation Method 1
The coned disc spring is deformed to absorb an impact only when an excessively high impact load is input into the coned disc spring
Implementation Method 2
a compression coil spring interposed between the rack guide and a plug pushes the rack guide toward the rack shaft to compensate for a clearance between the rack guide and the plug
Implementation Method 3
a holding member that holds the coned disc spring, and that is frictionally engaged with and held by the rack guide directly or indirectly
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A rack guide unit includes a closure member secured to an external opening end of an accommodation portion of a housing, and a rack guide. A compression coil spring and a coned disc spring that urge the rack guide toward a rack shaft are interposed between the closure member and the rack guide. A holding member that holds the coned disc spring includes a guide tube that guides a radially inner portion of the coned disc spring and a seat plate that receives a load from the coned disc spring. An elastic member held in an accommodation groove formed in the outer periphery of the guide tube is frictionally engaged with the inner periphery (opposed portion) of a tubular portion of the rack guide.