PROJECT - 106 SUSPENSION SYSTEM
Project 106
"Driving m/o Ihe future chassis
Philosophy
Theory always connected to a philosophy Closed loop system thinking involving the human being! ( not open loop ) Model describing complex phenomena in simple terms
Active Safety
Vehicle-road interaction
Driver-vehicle interaction
OBJECTIVES The objectives shall satisfy SAAB's goals to produce cars with high requirements on -
individuality driving pleasure thoughtfulness performance
Road holding Maximize the tyre reaction force capacity Minimize the vertical force Variation in roll and pitch
Maximize the road holding bandwidth Low track sensitivity Low sensitivity to disturbances Ride comfort Even load distribution at all wheels Good ride comfort and isolation characteristics High load capacity Low Vibration and noise level
Handling High stability Excellent acceleration and retardation properties High total body stiffness Superior handling and active safety properties Superior cornering properties Forgiving characteristics Fast and accurate response to the drivers input Immediate and disturbance free feedback signals to the driver Oualitv and costs High reliability and long life cycle The costs for design, materials, manufacturing and Service shall be minimized within the defined cost targets When ever possible, environmentally friendly material will be selected
McPherson Suspension Benefils: Compact High integrated Low gearing Produclion cks: Friction Kinemalics spec. camber track widht alt. roll center var. etc. Vibration and noise High engine hood
Double Wishbone Benefits: Kinematics spec. camber track widht alt. Comfort properties Vibration and noise Low engine liood
iwbacks: Larger side space Costs Production
Competitors Double wishbones: GME
Opel
Senator Mercedes
S
Nissan Infinity Skyline Honda Accord Legend Toyota Lexus McPherson: Volvo Audi BMW
Suspension properties The goals are broken down to suspension properties Important properties of the suspension system are e. Road holding High lateral and vertical stiffness Low unsprung mass Equal distribution of vertical forces at the wheels Welldamped unsprung mass Good suspension system geometry Ride comfort Low center of gravity High ratio of sprung/unsprung mass Well-damped vertical body movement Tuned pitch and roll stiffness distribution Excellent medium and high frequency isolation Suspension tuned to the human being
Handling Transverse front mounted engine Neutral steered car Superior steering properties Short roll moment arm Low roll center Variation High warp stiffness Well-tuned geometrical characteristics High braking and acceleration stability No interactions between eigenmodes Low dynamic index Distinct and accurate steering wheel torque lateral force from seat break and throttel information - to the driver Oualitv and costs Quality assurance by analysis and testing Carefully selected materials for each component
GEOMETRY DATA 106
Track width
9000
1515 mm 1522 mm
� alteration Roll center height
-4/-13 mm -13/-16 mm 32 mm
10 mm
185 mm
185 mm
Camber
- 0.5 degr
- 0.7 degr
King pin incl.
12.5 degr
11.3 degr
Wheel travel
� offset Caster
50 mm 3.8 degr
offset
62 mm 2 degr
17 mm
12 mm
Toe in
1 mm
1.5 mm
Scrub radius
0 mm
7.7 mm
Tire 185/65 R15 - 215/45 R 17 195/65 R15 - 225/45 R17
Rebound (mm) Bump (mm)
Dubbla svangarmar, SAAB fram
Camber angle (degrees)
Rebound (mm) Bump (mm)
Dubbla svangarmar, SAAB fram
Toe in (mm)
Toe out (mm)
Rebound (mm) Bump (mm)
Dubblft svang&rmar, SAAB 10Q fram
Rebound (mm) Bump (mm)
Dubbla svangarmar, SAAB fram
T>;
,^| , , , , ,,
(pr, Y-'r'l
N
GEOMETRY DATA
Track width alteration Roll center height Wheel travel Camber
106
9000
1492 mm
1492 mm
2 /-15 mm
0 mm
70 mm
200 mm
200 mm
210 mm
- 0.75 degr
Toe in
7 mm
Caster
12.9 degr � offset
Scrub radius
Tire 185/65 R15
195/65 RI 5
- 0.25 degr 2.5 mm --
27 mm
-----------
7 mm
-----------
- 215/45 R 17
- 225/45 R17
074, DOUBLE WISHBONE, LOTUS (MODIFIED)
a
Rebound (mm) Bump (
ß
Rebound (mm) Bump (mm)
074, DOUBLE WISHBONE. LOTUS (MODIFIED)
Rebound (mm) Bump (mm)
074, DOUBLE WISHBONE, LOTUS (MODIFIED)
22-FTB-1990 10.42.33M
Rebound (mm) Bump (
074, DOUBLE WISHBONE, LOTUS (MODIFIED)
SAAB 9000 (1990) LOTUS 4 WHEEL DRIVETRAIN W1SHBONE REAR SUSPENSION
t
CHASSIS SYSTEM - QPTIONS A number of additional options can be selected ro the Standard equipment:
Traction Control Svstem offer good starting and hill-climbing properties especially on low and split friction surfaces allows the driver higher safety margins in split friction, rain or winter conditions at the limit of adhesion very resource efficient with a minimal addition of equipment
Four wheel drive (in Cooperation with LOTUS) a torque sensing centre differential system with fast response to torque differance torque distribution to give neutral handling properties no additional control system required automatic ABS compatibility design capacity of 350 Nm
Four wheel steer the front is steered by a power assisted rack-and-pinion steering gear the rear is steered by active eiectro-hydraulic proportional valve
the Computer controlled rear steering uses signals from accelerometers, tachometer, gyro and steering wheel angle will improve the handling properties and increase the active safety
Adaptive suspension varies the damping force of the shock absorbers uses sensor signals to change the damping force three settings : soft, medium and hard automatic ride height selection independent of load no extra fuel consumption small design modifications
Active suspension (in Cooperation with LOTUS) increases the ride comfort and the road holding properties on rough road surfaces and/or high velocity wheel bandwidth up to 30 Hz several suspension system settings possible advanced suspension system for high performance or luxury car only
ADAPTIV SUSPENSION OBJECTIVES DEVELOP AN ADAPTIV SUSPENSION THAT CLEARLY IMPROVES THE ACTIVE SAFETY (HANDLING AND ROADHOLDING) AND RIDE COMFORT COMPARED TO THE PASSIV SYSTEM.
OUR ADAPTIV SUSPENSION SHALL BE BETTER OR EQUAL TO OUR COMPETITORS, WHEN INTRODUCED, REGARDING THE FUNCTIONAL QUALITIES.
BE A PLATFORM FOR FUTURE DEVELOPMENT OF SEMIACTIVE SUSPENSIONS.
8
4
IN 9901S77 lOSr tOl 89-02
D ESCRIPTION
*
LEVELLING AT THE REAR (HYDRO-PNEUMATIC)
*
AUTOMATICALLY ADJUSTABLE DAMPING IN THREE LEVELS TO CONTROL
THE
ROLL/
PITCH
AND
HEAVE
MODE
OF
THE
CARBODY. *
TWO DIFFERENT CONTROL PROGRAMS CAN BE SELECTED "NORMAL"
*
AND
"S PORT"
CONTROL PARAMETER
FOR THE ADAPTIV DAMPING IS VEHICLE
SPEED, STEERING WHEEL ANGLE AND ANGULAR RATE/ BRAKE LIGHT SWITCH, THROTTLE ANGLE, LONGITUDINAL ACCELERATION, VERTICAL ACCELARATION AND DISPLACEMENT BETWEEN REAR AXLE AND CARBODY, *
POWER
FOR THE LEVELLING IS PRODUCED FROM AN ENGINE
DRIVEN PISTON PUMP.
*
A DIAGNOSIS PROGRAM IS INCLUDED IN THE SOFTWARE FOR FAULT MONITORING AND INFORMATION.
IN 9901577 lOS/iOi 39-02
C ONTROL
T HE
STRATEGY
BASE SHOCK ABSORBER SETTING IS
S WITCHING
TO
"M EDIUM "
OR
"HARD"
"S OFT".
IS MADE IN CASE OF
CORNERING, EMERGENCY TURNING, BRAKING, ACCELERATION OR ROAD WAVES. WHEN THE "SPORT" PROGRAM IS SELECTED ONLY THE "M EDIUM " AND "H ARD " SETTINGS ARE USED . T HE
LEVELLING IS MADE TO INITIALLY SINK THE REAR END
PARALLEL TO THE FRONT AND THEN STABILIZE IT AT A LEVEL 20 MM BELOW THE UNLOADED LEVEL.
8
4
IN 990157? (OS^Ol 89-02
SPECIFICATIONS (KEY NUMBERS)
DURABILITY :
17 YEARS/ 5000 H0URS* 300000 KM (EXCEPT FOR THE ACCUMULATORS)
RELIABILITY :
COMPARABLE TO THE ABS-SYSTEM
W EIGHT:
+ 13 KG COMPARED TO PASSIVE
COST: (PARTS ONLY) SHOCK ABSORBERS: P UMP: N UMBER
OF SENSORS :
+ 6000 SEK COMPARED TO PASSIVE (1000 CARS/YEAR)
TWO-PISTON, THREE SETTINGS, SWITCH TIME < 50 MS T ANDEM
PUMP ,
1 L/MIN
P rojekt 106
"Driving into the future" -- - chassis
philosopny
Theory always connected to a philosophy
Closed loop system thinking involving the human being (not open loop)
Model describing complex phenomena in simple terms
Flgure 1: Driver Vehicl« Ck>s«4 Leop System f-fJZCATAsy/SS? S TA S /i~ (Try
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PfC£ £• / ■
f'ö&CA f/ f
/jr- ^
y
S/<S*4t-.
- SAC*C r££0~ AS4/S£.
AUTOMATIC TRANSMISSION
MANUAL TRANSMISSION
RIGID REAR AXLE
4WS PLATFORM 106 CHASSIS/TRANSMISSION
CHASSIS DESIGN FEATURES IMPORTANT PARAMETERS TO BE TUNED INDEPENDENTLY A HIGH LATERAL STIFFNESS TUNING NOT INFIUENCING OTHER IMPORTANT PARAMETERS
D HIGH DEGREE OF CAMBER COMPENSATION TO GIVE ROAD- HOLDING
B LINEAR BUMP-STEER OVER FULL STROKE TO REDUCE NOISE FRON ROAD DISTURBMICES
E KINEMATICS AND ELASTO-KINEMATICS CHOSEN TO GIVE NO TORQUE OVERSTEER INITIALLY, AND F0R6IVIN6 CHARACTERISTICS AT LIMIT OF ADHESION
C LOU INITIAL CAMBER TO REDUCE TIRE-WEAR AND IMPROVE ROLLING RESISTANCE
F KINEMATICS AND ELASTO-KINEMATICS CHOSEN TO GIVE DESIRED STEER-EFFECTS AT THROTTLE ON-OF AND BRAKING
OTHER FEATURES LARGE FUEL TANK BETVEEN WHEELS AND IN FRONT OF THE AXLE B FUTURE ACTIVE MUFFLER SYSTEMS GIVE POSSIBILITY TO INCREASE FUEL TANK VOLUME FOR METHANOL
DESIGN FEATURES A
LONGITUDINAL KINEMATIC TO GIVE LOU IMPACT
B
KINEMATICS GIVING LONC PASSENGER COMPARTMENT FOR A GIVEN UHEELBASE
PftOJl.C.T- /OC
Comparison different platforms Design speciflcatlon
Project 106
Project
J*
Project V
BASIC CHASSIS 1. Lateral stiffness to be tuned separately from sideforcesteer 2.
a) Toe-out on bump to reduce disturbance from road irre- gularities b) Linear characteristics over full stroke
3. Low initial camber to reduce tire wear
Yes
No
No
Yes
Possible
No
Yes
No
No
Yes
No
No
3 degrees/100 mm bump
2 degrees/100 mm bump
2 degrees /100 mm hu mp
4. Camber compensation
5. Insensitive to seif aligning torque
i
Geometry chosen Yes to give no torque- steer initially but to help at limit of adhesion
ies
6. Sideforce steer to give forgiving behaviour at limit of adhesion
Yes
Yes
Yes
7. Longitudinal kinematic to give low impact
Yes
Ye s
8. Kinematics giving long passenger compartment for a given wheelbase
Yes
Light weight: Yes Fully laden: No No
No
9. Space between wheels for fuel tank
Yes
No
No
No
Comparison different platforms Design speclflcation
Projcct
Project
106
Project
V
4WD Posslble to use identical passive chassls parts as for 2WD
Yes
No
No
4WS 1.
Posslble to use identical passive C h a s s i s parts
Yes
No
No
2.
a) Posslble to use only one No actuator b) Possibility for future Yes advanced force feedback systems with two actuators
Yes
?
?
?
Same low unsprung mass as on passive car
Yes
No
No
Yes
No
No
3.
ACTIVE RIDÂŁ Posslble to easily adapt bumpsteer for active ride
4
MULTI LINK REAR SUSPENSION T-/J-CAR TOE IN CHANGE JOUNCE ----------------
MULTI LINK AXLE _____ DEVELOPMENT RANGE*
3 PASS.
.<VCONV. SEMI TRAILING REAR AXLE
/
TOE IN
IMPROVEMENTS VS SEMI TRAILING -REDUCED DEFLECTKDN
REBOUND _________________
STEER -REDUCED TIRE WEAR -TOE CHANGE WDEPENDENT FROM CAMBER CHARACTERISTIC