Commercial Motor Vehicle Cab Suspension Aerodynamics
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Solution Overview
Problem
The existing cab-over-engine commercial vehicle designs face challenges in achieving optimal aerodynamics due to the need for clearance between tiltable cabin parts and chassis-mounted components, which results in gaps that reduce aerodynamic benefits and increase noise, while also complicating manufacturing and operation.
Innovation Solution
The design incorporates a floating suspension system using spaced resilient suspension devices with forward and rearward spring elements, allowing the upper cabin part to tilt without creating gaps between the upper and lower exterior panels, ensuring seamless aerodynamics and minimal interference with wheels or chassis components during driving and tilting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the lower cabin part is fixed to the chassis to reduce clearance with wheels, then aerodynamic benefits are improved, but gaps between upper and lower cabin parts increase noise and reduce aerodynamics
Solution Approach 1:
The lower cabin part is made dynamically connected to the chassis through resilient suspension devices (springs and dampers) rather than being rigidly fixed. This allows the lower cabin part to move vertically with the chassis during suspension travel while maintaining aerodynamic continuity with the upper cabin part during normal driving, eliminating gaps without causing interference with wheels during tilting operations.
2Ease of operation
If the upper cabin part is made tiltable for engine access, then maintenance accessibility is improved, but clearance requirements with wheels increase aerodynamic drag
Solution Approach 1:
The cabin is segmented into an upper tiltable part and a lower fixed part that remains attached to the chassis. This segmentation allows the upper part to tilt for maintenance access while the lower part maintains aerodynamic continuity with the chassis, eliminating the need for large clearance gaps between cabin parts and wheels.
3Adaptability or versatility
If a substantial intermediate gap is provided between upper and lower cabin parts to allow relative movement, then tilting and suspension movement are enabled, but aerodynamic benefits are reduced and noise increases
Solution Approach 1:
Resilient suspension devices act as intermediaries between the lower cabin part and the chassis, enabling relative movement during suspension travel while maintaining aerodynamic continuity. The springs and dampers absorb the movement discrepancies, allowing the cabin parts to remain closely aligned during normal driving without requiring large clearance gaps.
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 solution eliminates the need for intermediate gaps between cabin parts, enhancing aerodynamic performance and reducing noise, while maintaining ease of tilting and suspension movement, and is more cost-effective and less cumbersome in manufacture and operation.
Implementation Method 1
a pair of forward spring elements operatively interposed between the chassis and the upper and lower cabin parts
Implementation Method 2
spaced resilient suspension devices can include a pair of forward spring elements operatively interposed between the chassis and the upper and lower cabin parts
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A commercial motor vehicle (1) having a chassis (3), an engine compartment defined between parallel elongate beams (3R, 3L) of the chassis, and a driver cabin (7, 9) positioned at least partially over the engine compartment. The driver cabin (7, 9) being supported on the chassis (3) by spaced resilient suspension devices (19, 21), and includes an upper cabin part (9) and a lower cabin part (7). The upper cabin part (9) is tiltable to allow access to the engine compartment by being hinged about a lower edge, while the lower cabin part (7) remains associated with the chassis (3) when the upper cabin part (9) is tilted. The lower part (7) of the driver cabin (7, 9) is supported by the resilient suspension devices (19, 21).