Rear Suspension Bush Layout for Flexural-Torsional Stiffness Balance
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Solution Overview
Problem
The torsion beam-type rear suspension construction faces challenges in balancing flexural stiffness and torsional stiffness, leading to difficulties in independent suspension of rear wheels when excessive flexural stiffness impairs torsional movement.
Innovation Solution
A rear suspension construction featuring a hub carrier with a wheel support part, front and rear arm parts, a lateral beam, and trailing arms with bushes having support shafts oriented differently, allowing for balanced flexural and torsional stiffness without a dedicated torsion beam, thereby improving energy efficiency and packaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the flexural stiffness of the torsion beam is excessively high, then the lateral force transmission is improved, but the torsional stiffness deteriorates making it difficult for the torsion beam to twist
Solution Approach 1:
The trailing arm is divided into two separate bushes (first bush and second bush) with different support shaft orientations. The first bush handles lateral force transmission through its support shaft oriented in the vehicle width direction, while the second bush accommodates torsional movement through its support shaft oriented in the vehicle front-rear direction. This segmentation allows each bush to specialize in one function, resolving the contradiction between lateral stiffness and torsional flexibility.
Solution Approach 2:
Different parts of the suspension system are given different stiffness characteristics through the two bushes. The first bush provides high stiffness for lateral force transmission, while the second bush provides flexibility for torsional movement. This local differentiation of mechanical properties allows the system to simultaneously achieve both lateral stability and torsional independence.
2Ease of operation
If a torsion beam is used to achieve independent suspension, then the torsional stiffness is improved, but the device complexity increases due to the need to balance flexural and torsional stiffness
Solution Approach 1:
Instead of using a single torsion beam that must simultaneously provide both lateral stiffness and torsional flexibility, the system segments these functions into two separate bushes. Each bush is optimized for its specific function, eliminating the need to balance conflicting stiffness requirements in a single component and reducing overall design complexity.
Solution Approach 2:
The trailing arm assembly with two bushes serves multiple functions: lateral force transmission, torsional movement accommodation, and independent suspension operation. By integrating these functions into a unified multi-component system rather than requiring a complex torsion beam design, the solution achieves versatility while reducing the complexity of stiffness balancing.
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 enables effective balancing of flexural and torsional stiffness, enhancing energy efficiency and stability by eliminating the need for a torsion beam, allowing smoother force transmission and vibration isolation, and improving vehicle convenience.
Implementation Method 1
a first bush joining a vehicle front end portion of the trailing arm to a vehicle body, and a second bush joining the front arm part to a front arm attachment part disposed on the trailing arm. Respective axial directions of a first support shaft of the first bush and a second support shaft of the second bush are oriented differently from each other
Data Source
AI summary
A hub carrier includes a front arm part extending toward an inner side of a vehicle on a front side of an axle of a rear wheel; and a rear arm part extending on a rear side of the axle of the rear wheel. The rear arm part is joined to a lateral beam on the rear side of the axle of the rear wheel. A vehicle rear end portion of a trailing arm, extending in a vehicle front-rear direction, is joined to the lateral beam. A vehicle front end portion of the trailing arm is joined to a vehicle body using a first bush. A front arm part is joined to a front arm attachment part disposed on the trailing arm using a second bush. First and second support shafts of the first and second bushes have respectively axial directions oriented differently from each other.