5th International CTI-Symposium Innovative Automotive Transmissions 4th 7th December 2006, Berlin, Germany Drehmomentmessung mit Drehzahlsensoren Torque Measurement With Speed Sensors TOMCAT (TOrque Measurement Control for All Transmission Types) Thomas Karer / MAGNA Powertrain Engineering Center Steyr 1
Torque measurement in vehicles Only a dream till today? 2
General situation at the moment Powertrain components deal with torque - combustion engine - clutch - gearboxes and T-cases - differential and diff-locks - break systems, ESP Dream of every vehicle developer Knowledge of all torque values in the powertrain Till today only a dream, because Torque measurement is cost-intensive 3
General situation at the moment Torque will be calculated indirectly - pressure - length - angle - current, voltage - injected fuel quantity -... less accuracy Torque of powertrain is barely usable corrective factors narrow and expensive tolerances 4
Basic condition specification costs - non or low cost standard parts - replace hardware by software - no additional ECU function - accuracy: +/- 15 Nm for cars +/- 50 Nm for trucks - no temperature dependency - no wear TOrque Measurement Control for All Transmission Types result - torque signal + guaranteed tolerance - clearance of the powertrain 5
Advantages Major advantages of TOMCAT: Online measurement of torque in the powertrain Measurement of clearance size and wear in the powertrain Method for plausibilisation of transmission functions Optimization of gear shift strategy for all kind of automated transmissions (AT, DSG, CVT, DKG, Torque Vectoring,...) Evaluation of real stress for the whole series - Detection of overdimensioned components -> increase service intervals Improvement of ESP extended diagnosis - Gets important at high SIL level 6
Contents Measuring principle Basics Demonstration movie Measurement setup for different vehicle applications Test setup: Steyr truck 12M18, BMW X3/X5 Solution for serial production Algorithm Measurement results Possible applications functional advantages Test drive vehicles 7
Measuring principle Measurement of powertrain torsion ABS sensors Method of resolution: By using 2 existing ABS-sensors an one additional speed sensor in the transmission or T-case the torsion will be calculated relatively. The relative torsion is proportional to the transferred torque. Challenges: - Elimination of mech. clearance Speed sensor 8 - Conversion of relative torsion to an absolute value in [Nm]. Movie
Measuring principle 600 550 500 Effect of the mechanical clearance and the offset to the torque signal 450 Vorderachsdrehmoment [Nm] 400 350 300 250 200 150 100 50 0 mech. clearance Md-TOMCAT M d-va-gem = calculated essen M d-va-berechnet Md-reference = measured -50-100 Offset -150-200 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Zeit [s] 9
Measuring principle 3 sensor method 5 sensor method (rear- or all wheel drive) (double axle drive) Md ABS TOMCAT algorithm TC (opt.) TM ENG ABS TOMCAT algorithm TC (opt.) TM ENG Md Md 10
Contents Measuring principle Test setup: Steyr truck 12M18, BMW X3/X5 First test on truck Steyr 12M18 4x4 Measuring setup Different assembly of speed sensor in T-case Illustration CAN-bus structure Solution for serial production Algorithm Measurement results Possible applications functional advantages Test drive vehicles 11
Test setup 12M18 First test of torque measuring with Steyr 12M18 4x4 without strain gage measurement. Because of the high resolution of ca. 2,2 Nm on the rear cardan shaft Start of Torque sensor development (TOMCAT) Speed sensor near rear differential 12
Test setup BMW X3 reference torque (strain gage) - front ABS ESP DXC 4 variants 4 TOMCAT algorithm torque (calculated) front torque (calculated) rear reference torque (strain gage) - rear 13
Test setup BMW X3 Application of 3 rd speed sensor (4 variants) 1. Variant T-case output to front axle (Inductive sensor) 2. and 3. Variant T-case output to rear axle (Inductive sensor) 14
Test setup BMW X3 Application of 3 rd speed sensor 4. Variant T-case output to front axle (Hall sensor) Version for serial production 15
Test setup BMW X3 Reference measurement with strain gages Front cardan shaft Rear cardan shaft 16
Test setup BMW X3 Measurement instrumentation Signal amplification, signal conditioning, measurement device Data acquisition 17
Contents Measuring principle Test setup: Steyr truck 12M18, BMW X3/X5 Solution for serial production Solution for serial production (FA- and RA-torque measurement) Solution for serial production for all vehicle variants Algorithm Measurement results Possible applications functional advantages Test drive vehicles 18
Serial solution Serial solution (front- and rear axle torque measurement) CAN or Flexray Wheel speeds with time stamp ABS Transmission ECU + TOMCAT ABS sensors speed sensor in transmission - TOMCAT algorithm runs in transmission- or ABS- ECU - Speed sensor in transmission - Wheel speed via CAN with time stamp or via Flexray 19
Serial solution Summary for requirements Necessary hardware FA-measurement: 1 speed sensor in T-case RA-measurement: no hardware using transmissions with output speed sensor Wheel speed information Speed signals via Flexray alternative: Speed signals via CAN with time information from ABS alternative: Wiring ABS-hardware-outputs No additional ECU Calculation algorithm runs in transmission-, ABS- or Torque Vectoring ECU ECU requires speed sensor input 20
Contents Measuring principle Test setup: Steyr truck 12M18, BMW X3/X5 Solution for serial production Algorithm Measurement results Possible applications functional advantages Test drive vehicles 21
Algorithm Speedsensors Calculation of angle differences Relative alternation of torque disturbance (car, truck): deformation of vehicle (can be reduced to a minimum with models for a defined type of vehicle) Vehicle data via CAN Finding absolute value [Nm] Mech. clearance Absolute torque signal [Nm] 22
Algorithm Measurement principle is independent of temperature - TOMCAT provides better results at very cold temperatures as strain gage shafts Measurement principle is contactless - no wear 23
Contents Measuring principle Test setup: Steyr truck 12M18, BMW X3/X5 Solution for serial production Algorithm Measurement results Result without corrections Torque signal with corrections Tolerance of torque signal Availability of torque signal Measurement of mechanical clearance Possible applications functional advantages Test drive vehicles 24
Signal without clearance correction clearance clearance 25
Torque signal quality Offsetcorrections Md-FA-TOMCAT Md-FA-reference FA-State 26
Torque signal quality Long time measurement ca. 6 min ENTWURF Md-FA-TOMCAT Md-FA-reference FA-State Messsignal ist spiel- und offsetkorrigiert 27
Torque signal quality Max. deviation [Nm] with longer drive time or different drive manoeuvres like: - overrun condition, - narrow curves, - acceleration signal quality improves to ca. +/- 15 Nm 45 30 15 0-15 -30-45 Drive time 1. deceleration (C,D) narrow curve (F) acceleration (K) Speed > 3 km/h (O,M) accuracy: +/- 30 Nm: after 5 25 sec +/- 15 Nm: after 5 80 sec 28
Torque signal quality speedway 100 km without stops 98% 95% highway with stops 15% 75% city with Stop and Go traffic 29
Size of mechanical clearance Summation of all torque free conditions. Shaft is always between 0 and maximum of mechanical clearance Md [Nm] 350 325 300 275 250 225 200 175 150 Size of clearance Md-VA-berechnet Md-VA-gemessen VA-Spiel v Fahrzeug 80 75 70 65 60 55 50 45 40 v Fahrzeug [km/h]; Winkel Fahrpedal [%] 125 35 100 30 75 25 Result: 50 25 20 15 Size of clearance 0-25 10 5-50 0 30
Basic necessities Measurement possible for a: Relative altering torque signal: vehicle speed > 3 km/h (passive inductive speed sensor) vehicle speed > 1 km/h (active hall sensor) Absolute torque value [Nm] 2 additional conditions: Completion at least 1 drive manoeuvre - eg. vehicle acceleration, narrow curve, overrun condition,... calculation of clearance - Only necessary for new vehicles or modifications - later only for monitoring clearance eg. every 1000 km 31
Contents Measuring principle Test setup: Steyr truck 12M18, BMW X3/X5 Solution for serial production Algorithm Measurement results Possible applications functional advantages Possible configurations: cars, trucks Test drive vehicles 32
Applications Standard passenger car (4x2) Sensor position Measuring position Necessary hardware Transmissionoutput torque RA 1 speed sensor in manual transmission or no hardware if transmission has output speed sensor Transmissionoutput torque FA 1 speed sensor in manual transmission or no hardware if transmission has output speed sensor 33
Applications All wheel driven cars (4x4) Sensor position Measuring position Necessary hardware Transmissionoutput torque FA Transmissionoutput torque RA 1 speed sensor in T-case (fixed gear wheels) or in manual transmission or no hardware if T-case (fixed gear wheels) in combination with transmission with output speed sensor Transmissionoutput torque FA 1 speed sensor in T-case with friction clutch 34
Applications Torque Vectoring cars, Hybrid Sensor position Measuring position Necessary hardware Lateral shaft torque left 2 speed sensors in Torque Vectoring unit Lateral shaft torque right Total torque of combustion engine + electric motor 1 speed sensor in manual transmission or no hardware if transmission has output speed sensor 35
Applications Standard trucks (4x2, 6x4,...) Sensor position Measuring position Necessary hardware Transmissionoutput torque RA No hardware (transmission output speed sensor is available in trucks) Transmissionoutput torque RA No hardware (transmission output speed sensor is available in trucks) 36
Applications All wheel driven trucks (4x4, 6x6,...) Sensor position Measuring position Necessary hardware Transmissionoutput torque FA Transmissionoutput torque RA No hardware (transmission output speed sensor is available in trucks) Transmissionoutput torque FA Transmissionoutput torque RA No hardware (transmission output speed sensor is available in trucks) 37
Test vehicles Anschließend Demonstrationsfahrt Transmission test drive 07.12.2006 Official presentation of the TOMCAT torque measurement system in the test vehicle Author: Thomas Karer / ECS Date: 06.12.2006 38