Rear Frame Assembly With Central Crash Box for Suspended Powertrains
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Solution Overview
Problem
Motor vehicles with load-bearing engines are unsuitable for road driving due to direct engine vibration transfer, leading to handling difficulties, increased weight and dimensions, and inefficient energy absorption in rear crashes.
Innovation Solution
A motor vehicle design with a suspended driving unit using elastic suspension devices and a centrally arranged crash body to absorb rear crashes, reducing weight and dimensions while enhancing energy absorption efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the longitudinal members are made longer to accommodate a rearward-extending driving unit, then the driving unit can be positioned further back, but the weight and dimensions of the motor vehicle increase
Solution Approach 1:
The patent merges the crash box structure with the longitudinal members by integrating the cross member into the longitudinal member assembly. The longitudinal members extend from the rear shock tower and incorporate the cross member as part of their structure, creating a unified load-bearing assembly that reduces overall weight while maintaining structural integrity and positioning flexibility for the driving unit
2Volume of moving object
If the longitudinal members are made longer to accommodate a rearward-extending driving unit, then the driving unit can be positioned further back, but the dimensions of the motor vehicle increase
Solution Approach 1:
The patent merges the crash box structure with the longitudinal members by integrating the cross member into the longitudinal member assembly. The longitudinal members extend from the rear shock tower and incorporate the cross member as part of their structure, creating a unified load-bearing assembly that reduces overall length while maintaining structural integrity and positioning flexibility for the driving unit
3Strength
If the longitudinal members are designed with larger dimensions to support the driving unit, then the structural strength is improved, but the energy absorption efficiency decreases
Solution Approach 1:
The patent applies local quality by designing the longitudinal members with varying cross-sectional dimensions along their length. The members have different thicknesses and widths at different positions, allowing optimized strength distribution where needed while maintaining lighter weight and better energy absorption characteristics in critical impact zones
Solution Approach 2:
The patent employs composite material construction for the longitudinal members, combining materials with different properties to achieve optimal balance between structural strength and energy absorption. The composite structure allows the members to be strong where support is needed while being more compliant and energy-absorbing where crash forces are applied
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
The design allows road-worthy operation with reduced weight and dimensions, improved crash absorption, and efficient energy management during rear impacts.
Implementation Method 1
the vibrations of the engine are transferred directly to the frame, which makes it very difficult for the driver to handle the motor vehicle during use
Implementation Method 2
the driving unit is suspended with respect to the rear frame via elastic elements
Implementation Method 3
a rear crash box fixed so as to project at the rear with respect to the frame and having a function of absorbing rear crashes
Implementation Method 4
the longitudinal members usually have a low absorption efficiency, i.e. a low ratio of energy absorbed in the event of a rear crash to total weight
Data Source
AI summary
A motor vehicle has a forward moving direction, a rear frame having a front end and a rear end according to the forward moving direction, a driving unit comprising an engine and a gearbox, elastic suspension devices which couple the driving unit to the rear frame in an elastically oscillating manner relative to the rear frame around an equilibrium position, and a crash body for absorbing a rear crash along the forward moving direction, the crash body being fixed to the driving unit so as to project in a cantilever manner from a back of the driving unit according to the forward moving direction beyond said rear end along the forward moving direction.