Trailing Arm Seat With U-Shaped Insert For Axle Alignment
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Solution Overview
Problem
Existing vehicle suspension systems for medium weight lorries face issues with misalignment of trailing arms due to distortion of axle casings under excessive force and stress concentration at welds, particularly during torsional loading, and difficulties in precise alignment of tapered trailing arms.
Innovation Solution
A vehicle suspension system featuring a trailing arm seat with a primary recess and a flexible or resilient U-shaped insert, where the insert is positively secured within the recess and welded to the axle casing, allowing for limited movement and reduced stress, while U-bolts secure the trailing arm to the seat.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If U-bolts are used to secure trailing arms to the axle casing, then the trailing arms can be easily installed and removed, but excessive force through the U-bolts causes distortion of the axle casing and misalignment of the trailing arms
Solution Approach 1:
A trailing arm seat is introduced as an intermediary component between the trailing arm and the axle casing. The seat includes a primary recess that receives the trailing arm and a secondary recess that receives an insert, which is then welded to the axle casing. This intermediary structure allows the trailing arm to be secured without applying excessive force directly to the axle casing, thereby preventing distortion and misalignment while maintaining ease of installation and removal.
2Strength
If a trailing arm seat is welded directly to the axle casing, then the seat is securely fixed, but large stresses are created in the axle casing at the weld location and positioning is difficult
Solution Approach 1:
The connection structure is segmented into multiple components: the trailing arm seat, the insert, and the axle casing. The insert acts as a separate element that is welded to both the seat and the axle casing. This segmentation distributes the welding stresses across multiple smaller weld joints rather than concentrating them in a single large weld, thereby reducing stress concentration in the axle casing while maintaining secure fixation.
Solution Approach 2:
The insert serves as an intermediary element between the trailing arm seat and the axle casing. Instead of welding the substantial casting seat directly to the thin sheet metal axle casing, the insert mediates the connection. This intermediary component allows for a more gradual transition of forces and reduces the stress concentration that would occur with direct welding of dissimilar components with different stiffnesses.
3Strength
If the trailing arms taper in both horizontal and vertical planes, then the design allows for better load distribution, but positioning the seat on the axle to hold the trailing arm in correct alignment becomes considerably more difficult
Solution Approach 1:
The insert is designed with specific geometric parameters including a U-shaped configuration with end sections that extend beyond the edges of the primary recess. The insert can be made from relatively thin sheet material that is bent into the U-shape, providing flexibility while maintaining the required strength. This parameter optimization allows the insert to accommodate the tapered geometry of the trailing arms while simplifying the positioning process.
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 ensures precise alignment and reduced stress concentration, eliminating fitting issues and stress-related misalignment, and allows for flexible accommodation of manufacturing tolerances, thereby enhancing the stability and reliability of the suspension system.
Implementation Method 1
the insert is fitted into the secondary recess and there secured by welding, with end sections of the insert extending beyond the edges of the primary recess
Data Source
Figure 1
Figure 2~3
AI summary
The invention relates to vehicle suspension systems of the type with a trailing arm, and to a seat for securing the trailing arm to an axle or axle casing. Hitherto, trailing arms have been located on axles or axle casings and held in place by the force of U-bolts holding the trailing arm to the axle. Under excessive loads as can be applied to vehicle suspension systems, trailing arms can be moved out of alignment to the detriment of the running of the vehicle. To avoid such movement, seats for trailing arms are known to be welded to vehicle axes or casings and to which the trailing arms are secured such as by U-bolts. Here, manufacturing tolerances can cause a bad, relatively loose fit between the seat and axle or axle casing, causing alignment difficulties when fitting or welding the seat in place, with a large build-up of stresses in the vicinity of the weld when the trailing arm seat is subjected to torsional loading, that can be particularly damaging to an axle casing that ordinarily is formed from the thin sheet metal. The object of the invention is to provide a vehicle suspension that avoids those difficulties mentioned above, which objective is met by a construction comprising an axle and at least one trailing arm, there being a seat for the or each trailing arm, the or each seat having a primary recess in which the axle is located, the primary recess having a transverse secondary recess in which an insert is located, the insert being positively secured in the primary recess, and having end sections extending beyond the edges of the primary recess, that are positively secured to the adjacent walls of the axle.