1. SUBJECT SEMINAR TITLE: Drive By Wire - Automotive Systems (Electronic Throttle Control Systems) SUBJECT: 08MPD16 (SEMINAR) III SEM – M.Tech (PDM) YEAR 2008 BATCH SUBMITTED BY: GURU SUBRAMANI.R 5WA08MDZ07

2. 1.Introduction 2.IC Engines & Throttle system 3.Throttle by Wire systems 4.Components of ETC systems 5.Functions of an ETC 6.Case study 7.Conclusion 8.References CONTENTS

3. Introduction

4.  A technology known as “drive-by-wire”, also called "x-by- wire" or simply "by-wire” could change the way people drive  A car with this type of system mainly employs electronics to control a wide range of vehicle operations, including steering, braking, acceleration etc.,  Earlier Conventional cars mainly use hydraulic and mechanical technology to perform these same basic vehicle operations.  Although the mechanical systems are powerful, they can be overly complex, inefficient and conducive to wear and tear over the years.

5. Different X-By-Wire systems Topic of Interest

6. IC Engines & Throttle System

7.  In Internal Combustion engines, the throttle is a valve that directly regulates the amount of air entering the engine, indirectly controlling the fuel burnt on each cycle maintaining a relatively constant air / fuel ratio.  The Throttle is a butterfly valve, housed in a Throttle body.  The Throttle body is located between the Air filter box and the intake manifold.  In conventional throttle system, the valve is mechanically linked with the throttle pedal or lever.  In Electronic throttle Control (ETC), the valve is electronically controlled that allows Engine Control Unit (ECU) to reduce air emissions

8. Throttle or Butterfly valve Conventional Throttle System

9. Throttle Body location in an engine Intake manifold Electronic Throttle body Air filter duct Electronic Throttle body Throttle plate or Butterfly valve

10. Throttle by wire systems

11. Throttle by wire  Throttle by wire (TBW) systems is same as Electronic throttle control (ETC)  Basic components in ETC are  A position sensor on the accelerator pedal that detects the driver requirements  An electronically controlled throttle body with a small electric motor to open / close the throttle.  An Engine Control Unit (ECU) determines and positions the air valve the appropriate position through the use of a motor

12. ECU I/P Pedal Sensor I/P Throttle Feedback

13. Components of ETC systems

14. ETC Components 1. Accelerator Pedal Module  A potentiometer or contact-free sensor registers the exact position of the accelerator pedal.  A high degree of mechanical precision is guaranteed with very little pedal play & minimal tolerances. Pedal Sensor

15. 2. Electronic Control Unit (ECU)  This high power microcontroller controls the cylinder charge, the fuel injection & ignition. Sensors register the operating status, and all the relevant influencing variables.  Any deviations are immediately detected by the integrated On-Board Diagnostics. ECU circuit

16. 3. Electronic Throttle Body (ETB)  Based on the position of the accelerator pedal, the ECU calculates the required throttle valve opening, the ignition angle and the quantity of fuel to be injected.  A DC motor actuates the throttle valve shaft through gearing.  The throttle position sensor monitors the valve position & thus permits the position to be precisely maintained Electronic Throttle Body

17. ETB (showing internal parts)

18. 3.1 Throttle Position Sensor (TPS)  TPS is a feedback device that informs the ECU about the rate of throttle opening and relative throttle position.  It is mounted externally on the throttle shaft of ETB.  TPS is a variable resistor that changes resistance as the throttle opens & signals the ECU which then richen up the fuel mixture to maintain the proper air / fuel ratio. Throttle Position Sensor

19. Exploded view of an ETB DC Motor Throttle Bore Throttle Plate Throttle Shaft Main Throttle gear Idler gear Throttle gasket Throttle body or Housing Return spring Pinion Spur gear Adjusting screw Bore axis

20. Assembled view of an ETB Gear train Throttle plate DC Motor actuator Throttle Body (or) Housing Throttle Position Sensor mounted on throttle shaft

21. Functions of an ETC

22. Functional Block diagram of an ETC

23. Throttle Pedal assembly Functions  Throttle Pedal has two potentiometers attached to it, achieving the accuracy required from the pedal’s movement.  Combined signals allow the ETC Module to calculate a mean voltage output from the two signals.  This allows the pedal position to be calculated with greater accuracy than that by considering only a single voltage output  The waveform shown in the next slide indicates the throttle moving from idle to WOT (Wide Open Throttle) and back once again to idle.

24. Blue Trace -- Conventional increasing voltage as pedal is depressed Red Trace -- Operation over a low voltage

25. Electronic Throttle Body Functions  The absence of any mechanical linkage between the throttle pedal and the throttle body necessitates the use of an electric actuator motor.  The electrical connections are there to actuate the control motor and for the throttle position sensor.  The actuator, often referred to as a ‘servomotor’ is operated by DC (Direct Current) & responds to the change in ‘duty cycle’  The duty cycle is a percentage reading between the ‘on and off’ time. This change can be monitored on an oscilloscope.

26. Duty cycle of the servo motor Blue Trace -- Position of the Throttle Position Sensor Red Trace -- Duty Cycle of the Servo motor

27. Duty cycle of the servo motor @ increased load Blue Trace -- Position of the TPS showing further indexing of motor Red Trace -- Duty Cycle of the Servo motor

28. Throttle Position Sensor Functions  Integral to the servomotor is the TPS (Throttle Position Sensor).  The voltage output from this particular sensor has to report back to the ETC Module, the exact position of the throttle butterfly.  The TPS in the same manner as the throttle pedal position sensor has two voltage outputs  The waveform shown in the next slide shows the throttle moving from idle to WOT (Wide Open Throttle) and vice versa  The combined signals allow the ECM to calculate a mean voltage output from the two signals allowing the throttle butterfly position to be calculated with greater accuracy.

29. Blue Trace -- Conventional rising voltage as butterfly valve opens Red Trace -- Inverted waveform as the butterfly valve closes

30. Case study – Bosch ME-Motronic system

31.  Motronic system takes radically a different approach to previous Engine management systems  Motronic determines the engine torque requirement, and electronically opens the throttle plate to allow the engine to develop more torque  The driver’s “Torque request” input is weighed up against other torque requests generated by traction control system, engine braking torque control, speed limiter etc.,  The ECU models the engine’s instantaneous torque development, adjusting the throttle opening based on relationship between the requested & developed torque Case Study – Bosch ME-Motronic ETC

32. Functional Schematic of ME-Motronic I/P & O/P of a Motronic system InputsOutputsMotronic ECU

33.  Accelerator pedal movement manipulates 2 rotary potentiometers to allow redundancy – if one fails other still lets system operate  Two potentiometers output are identical but with an offset  If the accelerator & brake pedals are depressed together, the throttle valve is automatically closed to a defined small opening  If the brake is pressed first followed by accelerator pressing, the torque request is enabled. Accelerator Pedal Position sensor (Motronic)

34.  ETC consists of a DC motor, reduction gear drive & dual feedback angle sensors (for redundancy)  While sensing throttle blade position, ECU recognizes 4 functions: 1. Lower mechanical limit stop: Valve is totally shut 2. Lower electrical limit stop: This position does not totally close the valve, thus preventing contact wear of housing & blade 3. Emergency running position: Valve position in an unenergized condition to allow sufficient airflow for an idle speed. 4. Upper electrical limit stop: The blade is fully open  Control system has a self-learning function, to determine the state of the mechanicals within the ETC (eg: Spring tensions) by the evaluation of Throttle valve’s reaction speed. Electronic Throttle Control actuator (Motronic)

35. Program 1: If throttle position sensor fails  Torque increasing requests from other systems ignored  Fault lamp illuminated Emergency running programs: (Motronic) Program 2: If throttle valve drive fails or malfunctions  Drive is switched off so that the valve defaults to small emergency running opening  As far as possible, ignition angle & turbo boost control are used to execute driver torque commands.  Fault lamp illuminated Program 3: If throttle valve position is unknown  Drive is switched off so that the valve defaults to small emergency running opening  Engine speed limited to around 1200 rpm by Fuel injection control  Fault lamp illuminated

36. Fail Safe operation (Motronic)

37. 1. Limit Performance mode  Whenever there is a loss of accelerator pedal redundancy fault  Once tripped, gives dulled throttle response & less engine torque at all throttle positions. But still possible to continue driving. Fault countermeasures (Motronic) 2. Forced Idle mode  This happens when there is a complete failure of pedal sensors  Engine will be forced to idle condition & will not respond to accle- rator applications  The main aim is to maintain power for vehicle heating or cooling

38. 3. Power management mode  This activates when the system fails to control engine power via throttle.  Throttle actuation is disabled, allowing throttle valve to spring back to its default position  Still possible to continue driving but very slowly. 4. Engine shutdown mode  This activates when unable to control algorithms or engine power  The ETC system disables ignition & throttle outputs & engine is totally shutdown  The main cause for this is a processor fault or inability of the throttle or intake system to control airflow

39. Conclusion

40.  The use of throttle actuation ensures that the engine only receives the correct amount of throttle opening for any given situation  Reduced exhaust emissions and drivability is maintained regardless of the circumstances. Coupling the ETC to the adaptive cruise control, traction control, speed limiter and vehicle stability control systems also means finer control can be achieved.  Eliminating the mechanical element of a throttle cable and substituting it with fast responding electronics, reduces the number of moving parts (and associated wear) and therefore requires minimum adjustment and maintenance.  Greater accuracy of data improves the driveability of the vehicle, which in turn provides better response and economy  Fail safe operation & Fault counter measures in ETC ETC Vs Conventional Throttle system

41. Design freedom  Almost arbitrary cockpit design is possible with a comprehensive drive-by-wire system  Inputs can be reduced to hand controls. Could be useful for disabled drivers Adaptability  Controls can be programmed to suit driver preferences. For example throttle/brake pressures, steering wheel angles  Driver position does not need to be fixed. Controls could be designed to be easily moved to adapt to different countries Drive by Wire advantages

42.  Considerable safety improvements are possible  Conventional steering column and pedals are dangerous for the driver in the event of an accident  Electro mechanical systems have potential to be more reliable than conventional hydraulic/mechanical systems  Increased presence of control allows for the introduction of more safety systems, for example a collision avoidance system Safety aspects

43.  The cost of Drive by Wire systems is often greater than conventional systems.  The extra costs stem from greater complexity, development costs and the redundant elements needed to make the system safe.  Failures in the control system could theoretically cause a runaway vehicle (although this is no different to the throttle return spring snapping on a traditional mechanical throttle vehicle). The vehicle could still be stopped by turning the ignition off if this is occurred.  Manufacturers often reduce throttle sensitivity in the low-mid throttle range to make the car easier or safer to control - or to protect the drive train (gearbox, clutch, etc) from driver abuse. The feeling to the driver is that the throttle feels less responsive. Disadvantages

44. References [1] Tom Denton, Automobile Electrical and Electronic systems, Third edition, Elsevier Butterworth-Heinemann, Linacre House, Jordan Hill, Oxford OX2 8DP200 Wheeler Road, Burlington, MA 01803 [2] Bosch Automotive Handbook, Seventh edition, SAE, ISBN: 978-0-7680- 1953-7 [3] Edward Albert Bos, James Richard Rauch, Visteon Golobal technologies Inc, Electronic Throttle Body with insert moulded actuator motor, US Patent 6557523 B1, May 6, 2003, Dearborn, MI (US) [4] Robert D. Garrick, Delphi technologies Inc, Piezo Electronic Throttle actuator, US Patent 7159563 B1, Jan 9, 2007, Troy, MI (US) [5] Ola Larses, Modern Automotive Electronics from an OEM perspective, Technical report Mechatronics lab, Department of Machine design, Royal institute of technology, KTH S-100 44 Stockholm

45. [6] BMW ETC Systems, http://www.picoauto.com/applications /electronic-http://www.picoauto.com/applications /electronic- throttle-control.html, Dec 4, 2009 [7] The Bosch ME-Motronic System Part 1, http://autospeed.com/cms/titleThe- Bosch-MEMotronic-System-Part-1/A_108379/article.html, Dec 6, 2009 [8] The Bosch ME-Motronic System Part II, http://autospeed.com/cms/titleThe-ttp://autospeed.com/cms/titleThe- Bosch-MEMotronic-System-Part-2/A_108380/article.html, Dec 10, 2009 References

46. Thank you