Collapsible antiroll bar improves handling

Collapsible and Contractive antiroll bar
Automotive application
Inventor: Mr Fausto Garsi
November 2013

This document is strictly confidential and for PwC use only

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Bushidō Consulting - Overview


Bushidō Consulting is a business development consulting firm and a professional network,
with operational offices in Turin, Modena, and Rome - Italy, Baden Baden - Germany,
Prague - Czech Republic and Detroit - USA.



Established in May 2010, capitalizing on 20 years of international experiences in the
automotive business by its founder Maurizio Agostini and professional Partners across the
whole product lifecycle: Marketing, Business Development, Product and Process
Engineering, Quality Management, Manufacturing, Key Account and Retail Sales, Dealer
Network Development, Product Support.



The Partners acquired such experience and competence working in management positions
within international world-class corporations such as:



Specialized in supporting enterprises of all sizes to create sustainable growth through
successful expansion into international markets.



Helping clients become more competitive and profitable in their business, providing sales
and marketing development expertise and executive PwC use only
This document is strictly confidential and for management consulting experience.
This document and the information thereon is the property of Bushidō Consulting and may only be used for the purpose for which it is supplied

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Mr Fausto Garsi - Profile



Born in Milan - Italy on September 27th, 1969



Graduated in Mechanical Engineering from the Politecnico of Milan



Involved since 2002 in the racing car field as race car engineer



Currently Technical Director of a Formula 3 Team



Resident in Milan - Italy


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Project of cooperation

Bushidō Consulting and Mr Fausto Garsi have an agreement for the development of a project
of cooperation.
Mr Fausto Garsi has decided to avail itself of the service offered by Bushidō Consulting, which
foresees a business development support concerning the presentation of an innovative
automotive mechanical device concept by key cars manufacturers and Tier1 suppliers in
Europe, other reference countries can be considered.
The device concept is covered by a relevant Patent and is related to the configuration of a
collapsible and contractive anti roll bar for vehicle applications.
The aim of the project of cooperation is to identify opportunities of design application within the
automotive market, through the definition and execution of a relevant project development plan.
Bushidō Consulting is responsible for the development of initiatives involving car manufacturers
and OEMs interested in the above mentioned device concept and acts as main point of contact
with them.


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Patent - Description
COLLAPSIBLE AND CONTRACTIVE ANTI ROLL BAR FOR VEHICLE APPLICATIONS



Deposit number: MI2011A002097 -



Italian patent extendable abroad with validly claiming priority



Inventor: Mr Fausto Garsi - Resident in Milan (Italy) Via Donna Prassede 3

Date of Deposit: November 11th, 2011

A mechanical device is applied inside the link rods and in the middle of the roll bar itself,
two relevant functions are provided as described here below:
Collapsibility: when the vehicle gets a significant bump from the road, the device collapses,
suddenly reducing the anti roll bar stiffness.
Contractiveness: a less stiff anti roll bar behaviour on the compressed side, while
maintaining the same roll bar overall characteristics in terms of stiffness. The roll centre
gets lower in turns.
Chance to have an anti roll bar with two different stiffnesses, which makes it possible to
improve the car handling performance and to increase the comfort behaviour at the same
time.

Device easily produced, low cost application.

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Device design details 1/3

Sketch

Joined to the vehicle chassis


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Link-rod device part assembly description
Device made with 3 different springs K1 – K2 – K3
 K1 preloaded works for collapsibility

K3

 K2 is softer than K3 and works on the compressed side
 K3 works on the side in extension (inner side in turn)

K2

K1


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Roll bar device part assembly description
The bar works as a traditional one in case of on phase forces

The centre of the bar gets locked to the chassis in case of opposite forces


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Link Rod device part purpose - Collapsibility function


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Link Rod device part purpose - Contractiveness function

CG = Centre of Gravity
Kroll = Roll Stiffness

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Different roll bar stiffness to equal roll angle
The contractive effect gets the Mass Centre Lower on turn, then assuming the same lateral
acceleration, the roll moment gets less because multiplied by a shorter arm due a lower Centre
of Gravity Height (CGH)
Lat G = Lateral Acceleration
CGH = Centre of Gravity Heigh
RM = Rolling Moment = Lat G * CGH
STANDARD

CONTRACTIVE

RM 1
Lat G 1

RM 2
Lat G 2

CGH 1

CGH 2

Lat G 1 = Lat G 2
CGH1 > CGH 2
RM 1 = Lat G 1 * CGH 1 > RM 2 = Lat G 2 * CGH 2
Considering a less Rolling Moment it is possible to have the same roll angle with a softer roll bar
stiffness.

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Collapsibility working sketch

K1 gets compressed when the force goes over the
preload.
Preload settled equal to max Force in roll stress.

K1 compressed


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Contractiveness working sketch

Outer corner side

Inner corner side

K3 compressed

K2 compressed


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Roll Bar device purpose

Undeformed bar
Deformed bar

No contractive effect because
the bar turns

Central device locks the bar to
the chassis allowing the
contractive effect


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Track test and related data


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Track test - Reference Data 1/2

Comparison between two Formula 3 cars (Imola circuit - Italy, chicane passing through) with
and without the device installed.
Data trace, see also next page:

collapsible/contractive

- BLACK – car with collapsible/contractive device
- RED – standard car without device
Trace 1 – Car speed [kph]
Trace 2 – Steering Wheel angle [°]

Trace 3 – Throttle [%] / Brakes Pressure [bar]
Trace 4 – Engine revs [rpm] / Number of gear engaged
Trace 5 – Time difference [s]


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Track test - Reference Data 2/2

speed

standard

steering wheel angle

Throttle

Brakes press

rpm
gear
Time difference


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New and alternative design


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New and alternative roll bar design
The contractive effect can be realized by a new and alternative roll bar design:


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New and alternative roll bar design

 Two coaxial pipes connected to give different stiffness at each side.

 Solution applicable in case the available link rod dimensions are not enough to install 3 springs.
 Possibility to get a higher stiffness range than in the case of springs application.

 Possibility to get a proper pre load on the anti roll bar.


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Preload system applied to the alternative Roll Bar

On the new and alternative Roll Bar it is possible to apply a proper preload.
The preload gives the possibility to optimize stiffness characteristics within the Roll bar range work.
Very useful on finding a fine tuning during the vehicle final set up.

The preload system design is available.


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Preload and decreasing rate characteristics

Possibility to have improved roll bar stiffness characteristics
Better vehicle handling and ride comfort are respectively the consequences of an
initial infinite stiffness and a softer rate over a settled level of roll force

F

Standard Bar

Collapsible effect

Max Force in Roll

Roll Bar Preload

Infinite Stiffness

Deflection


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Simulations


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Simulations Models - Stiffness Parameters
Simulations performed, comparison between a Reference Std Vehicle and Vehicles with the following
characteristics:
Equivalent Roll Stiffness : total roll bar stiffness equal to the reference vehicle.
Equivalent Roll Angle : total roll bar stiffness in order to get an equivalent roll angle to the reference
vehicle.

Front Antiroll Bar

[Nmm/°]

Front Spring

Reference Std Equivalent roll
Vehicle
Stiffness
3350
20100

[N/mm]

57.23
/

22

4

/

900

250

[N/mm]

Front Drop Link Spring

57.23

[N]

Front Pre Load

57.23

[N/mm]

Front Pre Loaded Spring

Rear Antiroll Bar

Equivalent
Roll Angle
10050

/

22

4

1800

10800

5400

[Nmm/°]

Rear Spring

[N/mm]

108.28

108.28

108.28

Rear Pre Loaded Spring
Rear Pre Load

[N/mm]
[N]

/

12.5

2.27

/

450

150

Rear Drop Link Spring

[N/mm]

/

12.5

2.27


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Multi Body Vehicle Model Characteristics

Total Mass

1617 [kg]

Front Track

1.658 [m]

Rear Track

1.600 [m]

Wheelbase

2.600 [m]

COG Height

0.470 [m]

Tyres Model :
Magic Formulae Tyres

Front Tyres

225/35 R19

Rear Tyres

285/35 R19


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Simulations - Results
For the relevant specifications see the next page.

Reference Std
Vehicle

Equivalent roll
Stiffness

Equivalent Roll
Angle

Max Roll Angle [°]

3.55

2.91

3.55

Max Lateral Acceleration [g]

1.029

1.056 / +2.62 %

1.055 / +2.53 %

COG Height in Turn [mm]

479.8

456.6 / -4.83 %

456.4 / -4.87 %

Ramp Steer Simulation

Pitch Variation in turn

Front / Rear [mm]
Total Variation ∆ nose up / down [mm]

F +3.5 / R -3.8 F -27.0 / R -19.1 F -28.7 / R -17.7
∆ 7.3 up
∆ 7.9 down
∆ 11.0 down

Steering Pad Simulation
Max Roll Angle [°]

3.51

3.41

3.51

Max Lateral Acceleration [g]

1.0026

1.0033 / +0.07 % 1.0028 / +0.02 %

Comfort Road
RMS Vertical Acceleration [m/s^2]

0.247

0.1983 / -19.7 % 0.2025 / -18.0 %

0.1751

0.1643 / -6.17 % 0.1610 / -8.05 %

Bump Ride in Turn
Max Vertical Acceleration [g]



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Simulations - specifications

Ramp Steer
The vehicle at constant speed of 100 kph turns the steering wheel from 0° up to 120° in19 seconds
time.
Steering Pad Constant Radius
The vehicle, after a short straight, follows a 100 metres radius curve line, increasing the speed from
70 kph to 150 kph in 30 seconds.
Comfort Road

The vehicle at 70 kph constant speed rides an extra urban road profile. The road profile is in opposite
phase between the 2 car sides.
Bump Ride in Turn
The vehicle at 100 kph on turn rides a plateau profile bump only on the inner turn wheels.


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Summary


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Simulations results - Summary

 Better Handling Performance: + 2,5 % Lateral Acceleration
 Better Ride Comfort: - 18.0 % Vertical Acceleration

 Better Agility Behaviour: - 4.8 % Centre Mass Height
 Better Ride comfort on high bump : - 8.05 % Vertical Acceleration
 Positive Pitch angle on turn: 11 mm (nose down) equal to more aero down force.


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Device characteristics - Summary

Better general car handling because of the lower Centre of Gravity in Turns combined with
better comfort.
Roll bar characteristics with different stiffnesses in the work range, getting the possibility to
find a better vehicle set up with different behaviours combined.
Possibility to increase the car pitch angle on turn, extremely important benefits especially
for down force vehicles.
Application suitable for all kinds of vehicles, NOT only for sport cars, even better for
vehicles such as the SUV, because of the weight , high Mass centre and big roll angle.
Fully mechanical device.
Low cost and extremely reliable.


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Collapsible antiroll bar improves handling

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