Rear Subframe with Coplanar Elastic Isolators
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Solution Overview
Problem
Existing car designs that use a rear subframe connected to the frame via elastic isolating elements effectively reduce vibrations but compromise dynamic performance and structural efficiency, particularly in terms of handling and torsional stiffness.
Innovation Solution
A car design featuring a rear subframe fixed to the frame through four coplanar elastic isolating elements, with the subframe directly supporting the rear electric powertrain and suspensions, and incorporating removable stiffening beams and a unique quadrilateral-shaped base with 'C'-shaped support bodies to enhance structural integrity and dynamic handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a rear subframe connected to the frame by elastic isolating elements is used, then vibrations are reduced and comfort is improved, but dynamic performance and handling are compromised
Solution Approach 1:
The rear subframe is divided into modular components including a base structure, support bodies, and removable stiffening beams. This segmentation allows the vibration isolation system to be separated from the main frame while maintaining independent structural integrity, reducing vibrations without compromising handling.
Solution Approach 2:
The subframe incorporates removable stiffening beams that can be adjusted or removed based on driving conditions. This dynamic adjustability allows the structure to optimize between vibration isolation (beams removed) and handling performance (beams installed), resolving the contradiction between comfort and dynamic performance.
2Object-affected harmful factors
If a rear subframe connected to the frame by elastic isolating elements is used, then vibrations are reduced and comfort is improved, but structural efficiency is reduced
Solution Approach 1:
The subframe utilizes composite construction with support bodies featuring 'C'-shaped cross-sections that provide high structural efficiency per mass unit. These composite structural elements maintain torsional stiffness and strength while being connected through elastic isolating elements, achieving both vibration reduction and preserved structural efficiency.
Solution Approach 2:
The support bodies are designed with three-dimensional 'C'-shaped cross-sections that provide structural strength in multiple directions. This dimensional approach allows the subframe to maintain high torsional stiffness and structural efficiency while being isolated from the main frame, resolving the contradiction between vibration isolation and structural strength.
3Ease of operation
If fixing points are positioned close to the ground, then dynamic performance and handling are improved, but the structural configuration becomes more complex
Solution Approach 1:
The four fixing points serve multiple functions: they provide low-positioned attachment for improved handling, support the elastic isolating elements for vibration reduction, and maintain structural integrity through their coplanar quadrilateral arrangement. This multi-functionality reduces the need for additional complex structural components.
Solution Approach 2:
The fixing points are integrated directly into the support bodies, merging the mounting function with the structural support function. This consolidation simplifies the overall structural configuration while maintaining the low positioning of fixing points for optimal handling performance.
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 achieves a balance between comfort by reducing vibrations and high dynamic performance by positioning fixing points close to the ground and maintaining structural efficiency through removable stiffening beams, resulting in improved torsional stiffness and handling.
Implementation Method 1
the rear suspensions are fitted to a rear subframe, which is fixed to the frame through the interposition of elastic isolating means (for example small rubber blocks), which isolate the frame from the rear subframe from a vibrational point of view
Data Source
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AI summary
A car (1) having: a frame (7); two rear drive wheels (2); two rear suspensions (15), which support the two rear wheels (2); a drivetrain (5) having two axle shafts (14), which transmit the motion to the rear drive wheels (2); a rear subframe (11), which is fixed to the frame (7) in four fixing points (12) through the interposition of elastic isolating elements (13), directly supports at least part of the drivetrain (5), and provides a coupling for the rear suspensions (15). The four fixing points (12) are substantially arranged at the same vertical height. The frame (7) has two "C"-shaped elements (16), each having its two ends in the area of two fixing points (12). Two stiffening beams (18) are provided, each arranged longitudinally and screwed to the frame (7) in the area of the ends of a corresponding "C"-shaped element (16).