SophE

In Sophe’s monocoque we rely on the proven concept, which we have used in LucE. In order to withstand the new demands of the all-wheel drive, we opted for a new layer structure by FEM simulation. An advanced aerodynamic package was developed to be able to put our new tires to their maximum. After very positive feedback from our drivers last year our ergonomics package did not change much. The novelty here is the fact, that the driver is able to adjust the pedals himself.

Aerodynamics:

• Front wing with 2 profiles
• Rear wing with 4 profiles, adjustable to reduce drag
• Compact and effective underfloor for downforce and sidewings to reduce the drag at the rear wheels
• Laminated, sintered brackets and load bearing structures for the connection of the rear wing
• Optimized side pods for maximum air inflow towards the radiators

Ergonomics:

• Weight and comfort optimized seat with the help of 3D scans
• Pedalbox is adjustable by the driver

Safety for the driver:

• LEO-System for firewall and battery case
• Isolation of accumulator container tested in cooperation with the university
• Tested 6-point seatbelt and beltconnections
• Revised crash element

To ensure optimal transmission of the power of all four engines on the road, the complete vehicle kinematics and the chassis design had to be adapted. Especially the steering kinematics has undergone some changes due to the motors on the front axle. The carbon fiber wishbones are connected by aluminum outserts with the monocoque and hub carriers to keep optimal state at all occurring influences. With steel springs, which have a main spring and an auxiliary spring, new damper kinematics and our two stabilizers with 3 tempers we are ready for any bump.
The direct contact to the road is established via new low-profile tires, which offer SophE greater cornering stability and thus make her more agile and more secure on the track.
Following last year’s innovation of an adjustable pedals, we are now gone a step further, so that it is now directly from the driver adaptable.

Tires/Rims:

• 205/470 R13, Continental
• Magnesium lightweight rims, 7 x 13 central locking

Spring/Damper:

• Steelsprings with one main spring and one additional spring

Anti roll bar:

• Front and rear, 3 levels of hardness each

Brakesystem:

• Selfdeveloped brake calipers, 4 pistons
• Braking force adjustable by the driver

Steering:

• Weight optimized steering gear with integrated steering angle sensor
• Perpendicularly steering rod between steering wheel and gear, transmitted through 90° angle gear

Wishbones:

• Carbon fibre tube with aluminium outserts

Wheel hub:

• Topology-optimized
• Glassplate to show gears

Upright:

• Topology-optimized 5-axis millingconstruction out of high strength aluminium
• Camber adjustment with metal disks
• Integration of motor and gearbox

The new engines and lower speed led to the development of a 1.5-stage planetary gear with a ratio of 13.38:1. Like last year, ring gear and wheel hub are integrated into the upright.
The all-wheel drive also creates new requirements for the cooling since the motors at the front axle also have to be kept at the right temperature. The cooling tubes of the front and rear axles, as well as the motors are connected in parallel order among themselves. Inverters and motors are cooled by two independent cooling circuits, each with its own temperature level.
With the inverter Housing, we rely on an innovative fixing of the inverter, which is perfectly adapted to our monocoque and mounting options.

Gearbox:

• Planetary gearbox with 1.5 stages
• Transmission: 13.38:1
• Max. speed: 132 km/h or 82 mph
• Max torque at the wheels: 1120 Nm
• Functionally integrated gearbox into the upright

Cooling:

• Two separate cycles for motors and inverters with flow-optimized components

Inverter housing:

• Weight-optimized aluminium cage as fixation and HV-shield

The module of Electronics includes and works with all low-voltage components in SophE. The data from the various sensors on the car is being processed in real time and can be read both on the track and off the track via WiFi. This enables us to gain a live overview of processes in the car and detect operating errors early. All signals are transmitted via 2 CAN bus systems to the telemetry Box.
Using a four-wheel-concept offers us the possibility of torque vectoring, meaning to control each motor separately in accordance to the current situation on track to achieve optimal cornering behaviour. To prevent SophE from producing smoking tires with her sheer power an anti-skid control was developed this year.

Sensorsystem:

• GPS sensor
• Accelerometer
• Torque encoder
• Brake pressure sensor
• Steering angle sensor
• Cooling temperature sensors
• Suspension travel sensor (For validation of aero and suspension)
• Brake disk temperature sensor
• self-developed SmartSensor PCBs to send sensor-data over CAN-bus

Electronic Control Unit:

• sbRIO-9626 (National Instruments) with CAN- and DIO-Module
• selfdeveloped supply module

Shutdown circuit:

• Insulation monitoring device (Bender)
• Crash sensor
• Self-developed brake system plausibility device
• Shutdown at overvoltage/undervoltage and high temperature of the accumulator cells

Cable Harness:

• 2 CAN bus systems (front/rear)
• Self-assembled LV+HV cable harness

Our high-voltage area is all about the battery, the inverter and the motor. Through this year’s all-wheel drive, the challenge is to monitor the 4 new motors of AMK and supply them . The specially-designed harness had to be accommodated elegant and effective in the monocoque.
An innovation this year is the excellent serviceability of our accumulator. By easily removable electronics from the battery, defects can be corrected quickly. Furthermore, through the specially developed battery management system and a thermal battery simulation with specially constructed measuring housing, errors can be detected and eliminated quickly.

Accumulator:

• Max. voltage: 600V
• Total energy: 7 kWh
• 288 lithium-polymer pouch cells with 144s2p interconnection
• Nominal voltage: 3,7V
• Capacity: 12,6 Ah
• Max. continuous current: 440A
• complex, self-developed battery management system

Drive System:

• AMK Inverter/ PDK_205481_KW26-S5-FSE-4Q
  • 4-way inverter
  • Max. output current: 107 Aeff
  • Max. output voltage: 490 VAVeff
• Four permanently excited synchronous motors; AMK/ DD5-14-POW-19000
  • Max. power: 35kW (x4)
  • Max. torque: 21 Nm
  • Max. rpm: 20,000