Dual Bearing Strut Assembly Torque Reduction
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Solution Overview
Problem
Current strut assemblies for vehicle suspension systems experience torque issues due to the fixed position of one end of the coil spring, leading to a pull on the wheel assembly as the vehicle navigates road irregularities, known as bump steer.
Innovation Solution
The dual bearing strut assembly features a coil spring seated between upper and lower bearing assemblies, allowing the lower end of the coil spring to freely rotate about the damper cylinder during compression, thereby reducing torque transfer to the wheel assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the coil spring end is fixed to the damper cylinder, then the strut assembly structure is simple, but torque is generated on the damper cylinder during compression causing bump steer
Solution Approach 1:
A bearing assembly is introduced as an intermediary component between the coil spring lower end and the damper cylinder. The bearing assembly includes bearing rings that allow the coil spring to rotate freely during compression while maintaining axial support, thereby eliminating torque transfer to the damper cylinder without compromising structural integrity
2Force
If the coil spring end is fixed to prevent rotation, then torque on the damper cylinder is reduced, but the wheel assembly experiences pull during compression
Solution Approach 1:
The bearing assembly serves as a mediator that decouples the rotational movement of the coil spring from the damper cylinder and wheel assembly. By allowing free rotation at the bearing interface, the system eliminates both torque on the damper cylinder and pull on the wheel assembly during compression
3Object-generated harmful factors
If the coil spring is allowed to rotate freely about the damper cylinder, then torque on the damper cylinder is eliminated, but the bearing assembly complexity increases
Solution Approach 1:
The rotational freedom function is extracted from the fixed connection between the coil spring and damper cylinder. By separating the axial support function (performed by the damper cylinder) from the rotational constraint function (removed via the bearing assembly), the system achieves torque elimination with minimal added complexity
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 effectively isolates the coil spring's rotational movement, significantly reducing or eliminating torque on the damper cylinder and subsequent bump steer, enhancing vehicle stability and steering precision.
Implementation Method 1
The upper bearing assembly may include a pair of bearing rings with a plurality of ball bearings disposed between the pair of bearing rings. In the alternative, or in addition to, the lower bearing assembly may include a pair of bearing rings with a plurality of ball bearings disposed between the pair of bearing rings.
Data Source
AI summary
A dual bearing strut assembly for a vehicle suspension system includes a strut with a shock absorber comprising a damper cylinder and a piston rod, and a coil spring disposed around the shock absorber. The damper cylinder may be affixed to a knuckle of a vehicle wheel assembly and the piston rod may be affixed to a top strut mount. An upper bearing assembly and a lower bearing assembly are included. The coil spring has an upper end seated to the upper bearing assembly and a lower end seated to the lower bearing assembly. The lower end of the coil spring freely rotates about the damper cylinder when the coil spring is compressed thereby reducing torque on the damper cylinder and reducing “bump steer” of the vehicle steering system.