Transcript Lotus Europa Front Suspension Redesign

1970 Lotus Europa Front Suspension
Redesign
ME 462 Capstone Design
Spring 2007
Sponsor: Bishop Steering Technology
Kel Tiedman, Jason Wou
Team Members
Tom Filipucci
Brian Schludecker
Frank Faulkenberg
David Giles
May 3, 2007
Project Background

1970 Lotus Europa

1470cc, 4-cylinder engine producing 78 hp

120 mph top speed

13-inch wheels


2-piece control arms
 Stamped & welded
 Bolt-on ball joints
Coil-over shock
& spring arrangement
Customer Requirements

Maintain suspension geometry

Provide stable 200 mph ride

Maintain 5 inch ride height

Utilize 15 inch Audi wheels

Utilize current frame mounting points

Maintain wheel-to-wheel dimension

Attempt to utilize stock shock and spring size

Minimal bodywork modifications
Engineering Targets
Engineering Requirements
Target
Units
10
mm
50-100
mm
Car Ride Height
5
in
Anti-Dive
25
%
Steering Axis Inclination
7
deg
Caster Angle
4
deg
-0.5
deg
15-35
mm
Scrub Radius
Roll Center Height
Camber Angle
Caster Trail
Final Design
Final Design





Upper Arm = 5.60 in
Lower Arm = 11.03 in
Scrub = 10 mm
Steering Axis = 16.5º
Rotor Clearance = 0.69 in
Design Animation
Design Animation
Design Evaluation

Suspension
Analysis

Four-bar
Mechanism
Design Evaluation

“Fourbar” Program – Norton
 Evaluate each control arm length iteration
 Rough wheel motion

“Four-bar Mechanism” - Matlab
 Quantitative wheel motion

ProEngineer Mechanism output to Excel

“Camber Curve” - Matlab
 Camber curve comparison
Design Evaluation

Iteration Method

2 Iteration Sets

First Set – 11 possibilities


Manipulated Variables
 Scrub radius
 Steering axis
Second Set – 6 possibilities

Same Variables
 Smaller scrub radii
 Larger steering axes
Design Evaluation

Case 5:





Steering Axis – 16.5°
Scrub radius – 10.0 mm
Upper arm – 5.60 in
Lower arm – 11.03 in
Case 1:




Steering Axis – 16.0°
Scrub radius – 11.0 mm
Upper arm – 5.70 in
Lower arm – 11.04 in
Design Evaluation
Design Evaluation
Camber Curve Comparsion
2
Case 5
Case 1
Zero scrub/ 20 Degree steering axis
35 mm scrub/ 7 Degree steering axis
1.5
Vertical Wheel Travel
1
0.5
0
-0.5
-1
-1.5
-2
-6
-5
-4
-3
-2
Degree
-1
0
1
FEA Results
Final Evaluation
Engineering Requirements
Target
Result
10 mm
10 mm
50-100 mm
50.8 mm
Car Ride Height
5 in
5 in
Anti-Dive
25%
25%
Steering Axis Inclination
7º
16.5º
Caster Angle
4º
12º
-0.5º
-0.5º
15-35 mm
25 mm
Scrub Radius
Roll Center Height
Camber Angle
Caster Trail
Goal Met
Conclusion & Recommendations

Conclusion



Kinematic motion requirements met
Verified some physical packaging requirements
Recommendations




Further finalization of arm shapes
In-depth finite element analysis
Close examination of control arms and knuckle
attachment
One team for knuckle/brake and suspension design
Questions?