Chassis technology today is one of the key functional areas responsible for overall performance in terms of vehicle dynamics, safety and fuel efficiency, and these functions can be seen as the key contributor to competitive advantage.
At its simplest the chassis can been defined as the frame of the vehicle plus its ‘running gear’ consisting of steering, suspension, wheels and brakes. However, today this description misses an essential point in that the chassis now is a complex set of components that are responsible for the vast majority of the ride, handling, comfort and safety. Furthermore, through the use of advanced materials and systems it has a significant role to play in reducing CO2 output.
Table Of Contents
Introduction Electrification within the chassis Chassis performance Design compromise Manufacturing economics Platform development and component commonality Noise vibration harshness
Key Development Drivers Greenhouse gas emissions and fuel efficiency The European Union The United States Japan China Other countries Chassis materials developments Increasing electrification Electronic systems integration The packaging dilemma The future for chassis design
Suspension systems Challenges and barriers
Suspension technology development passive moving to active Kinematics and elastokinematics
Suspension element technology Control arms Spring systems Active body control Anti-roll or stabiliser systems Adaptive damping system Air suspension Pneumatic and hydropneumatic systems The âskyhook control strategy Active suspension systems Electronic Damper Control (EDC) Active Suspension Geometry (ASG) Semi-active suspension BWI MagneRide: Magneto-rheological damping Active electronic suspension system Recuperative damping systems Future trends
Chassis and Corner Modules
Steering Systems Electrically Power Assisted Steering (EPAS) Surface acoustic wave Software enabled features Electro-Hydraulic Power Steering (EHPS) Electric Power Steering (EPS) Active Front Steering (AFS) Four-wheel steering Steer-by-wire Automated parking
Braking System Development Anti-Lock Braking System (ABS) Electronic Braking System (EBS) or Electronic Brake Distribution (EBD) Brake Assist (BA) Autonomous emergency braking Ceramic composite brakes Lightweight brake discs Brake-by-wire Electro-hydraulic brake-by-wire Electro-mechanical brake-by-wire Regenerative braking systems and brake blending Vehicle stability systems
Four-wheel Drive (4WD) Emissions and Fuel Economy Active Torque Dynamics (ATD) Safety and AWD Technologies and Challenges Electric AWD Integration of Control Systems Active All Wheel Drive (AWD) Torque vectoring Future trends
Figure 1: Additional functionality requires higher voltages - 48 volts Figure 2: Conventional suspension compromises Figure 3: Matching and similar parts for the Volkswagen B/C platform Figure 4: Common and matching parts (Chassis, drivetrain, steering system) for the Volkswagen B/C platform Figure 5: Progress from platform through modular to assembly kit strategy for Volkswagen Golf Figure 6: Volkswagen MQB platform Figure 7: Additional functionality requires higher voltages - 48 volts Figure 8: The complex functional harmony required to provide driving quality Figure 9: Global CO2(g/km) progress normalised to NEDC test cycle Figure 10: CO2 (g/km) performance and standards in the EU new cars 1994 -2011 Figure 11: Additional functionality requires higher voltages - 48 volts Figure 12: Weight share of modules and their weight increase Figure 13: Aluminium steering knuckle Figure 14: A lightweight strut with a fibreglass wheel carrier Figure 15: Average profit per vehicle versus CO2 compliance costs Figure 16: Global market revenue forecast for OEM electronic systems (billions) Figure 17: Electronic Stability Control installation rates Figure 18: High performance domain control ECUs can simplify overall network complexity Figure 19: A schematic of data fusion from multiple sensors Figure 20: X-by-wire roadmap Figure 21: Average power consumption 1990 - 2010 for mid size and luxury cars Figure 22: Electrical power requirements for NEDC and actual customer requirements for various vehicle classes Figure 23: The extended performance envelope for fully active suspension compared to conventional passive and semi-active systems Figure 24: Ford Focus control blade suspension Figure 25: Additional functionality requires higher voltages - 48 volts Figure 26: Typical control arm designs Figure 27: Suspension control arm configurations Figure 28: BWIâs Active Stabiliser Bar System Figure 29: Dynamic Ride Control main module schematic Figure 30: A schematic of Monroeâs kinetic system Figure 31: Continentalâs 4-Corner air suspension system Figure 32: Continentalâs air suspension system Figure 33: CO2 reduction using pneumatic suspension systems Figure 34: Graph showing the range in which CDC can continuously vary damping forces in compression and rebound Figure 35: CDC dampers with internal and external valves Figure 36: Cross section of a MagneRide actuator Figure 37: Comparison of force-velocity characteristics of a MagneRide damper, typical variable valve dampers and a passive damper Figure 38: Boseâs fully electromechanical front and rear suspension modules Figure 39: A schematic representation of Genshock technology Figure 40: Steering system design compromise (EPAS) Figure 41: BWIâs corner module Figure 42: MOBISâ front chassis module Figure 43: Additional functionality requires higher voltages - 48 volts Figure 44: Mechanical and electric control systems for EPAS Figure 45: Differing steering rack types, force and mechanical performance by vehicle class Figure 46: A schematic of AFS used in a driver assistance function to enhance vehicle stability Figure 47: Renaultâs active four-wheel steer systems as fitted to the Laguna GT Figure 48: Nissanâs steer-by-wire system Figure 49: A schematic illustrating 4 Wheel Active Steer functionality Figure 50: Fordâs park assist system Figure 51: Brake control systems roadmap Figure 52: Continentalâs electronic wedge brake on test Figure 53: Continentalâs electro-hydraulic combi braking system layout Figure 54: By-wire brake system layout with regeneration Figure 55: Mazdaâs supercapacitor based regenerative braking system layout Figure 56: Continentalâs regenerative braking system layout Figure 57: Comfortable regeneration requires uncoupling the pedal and quiet and highly dynamic of braking force regulation Figure 58: Boschâs yaw torque compensation system. Figure 59: Attributes of lifestyle and AWD wagons and performance AWD vehicles Figure 60: Attributes of SUVs and crossover vehicles
Table 1: Comparison between various automotive suspension systems Table 2: Front axle design proportions, worldwide light passenger vehicles (%) Table 3: Front axle design by segment, worldwide light passenger vehicles (%) Table 4: Rear axle design proportions, worldwide light passenger vehicles (%) Table 5: Rear axle design by segment, worldwide light passenger vehicles (%) Table 6: Advantages of EPAS