AUTOTRONICS

1. AUTOTRONICS Cross 11, Tapovan Enclave Nalapani Road, Dehradun 248001 Email: info@iskd.inContact : +918979066357, +919027669947

2. INDEX

4. AUTOTONICS BasicsIntroduction to Clutches and Brakes With the increase of design integration of electronic control systems with mechanical systems, new concepts of engineering are being developed to simplify the overall equipment and increase its performance with the maximum reliability possible. The mixing of pure electronic circuitry with mechanical operation imposes a great burden on the design engineer in the form of additional knowledge of components that cross the discrete line of difference between electronic and mechanical parts. Electro-magnetic clutches and brakes are one of the most used and least understood of these components. There are several types and configurations of these electromagnetic devices, each a perfect answer to a particular design problem. Unfortunately, the selection of the wrong unit can lead to needless complications which may downgrade the system performance. It is necessary to understand the various types of electro-magnetic devices that are available and to know their exact functions as applied to the particular system under consideration.

6. Definations & Functions There are several types of devices for controlling mechanical motions or functions. They can be classified as purely mechanical in operation, or controlled by pneumatic, hydraulic, or electrical power. These notes will deal with the latter for the most part, specifically, the friction disc electro-magnetic devices that are manufactured by Autotronics , Inc. However, in order to give the engineer the broadest possible background, we will describe the basic types of devices that are available for use in the majority of applications. The definitions deal with the principle functions of a device without regard to the method of controlling these functions.

7. Brake The first device is the brake. A brake will, upon application of controlling power, exert a force that will retard or stop a rotating member or hold a static member against a specific force. The schematic representation of a brake is shown in Figure.

8. Clutch The next device is the clutch. The clutch, upon suitable command, will couple two rotating or static members together. The automotive clutch is a good example of this type of device. The schematic representation of a clutch is shown in Figure.

9. Clutch Brake The functions of both the clutch and the brake can be combined to give two interdependent actions within the same envelope. This is the clutch/brake unit. When properly applied, the clutch/brake is a very adaptable device which can solve many perplexing design problems for the engineer. The function of a clutch/brake is to either disengage a driving force and brake the driven member, or to disengage the brake member and apply the driving force. This action can occur simultaneously or within a very short interval of time. The schematic representations of the clutch/ brake and the brake/clutch are shown in Figure 3a and 3b, respectively. Modifications of the above brakes, clutches and clutch/brake units can give action either upon a direct application of the commanding signal or upon removal of the signal. Thus a clutch can be made to engage when energized, or to disengage when energized. The model BF brake and the CF clutch are examples of this “reverse” type of action.

10. Specially Designed Devices Autotronicscan furnish several modifications of the clutch, brake or clutch/brake combination to fit the system packages. These modifications are: • 1. Shaft length to your requirements. • 2. Adjustment of clutch and/or brake values for higher torque or lower slip torque as required for the application. • 3. Furnishing pre-assembled gears in place of the input flange, and pinion shafts or gears on the output shaft. • 4. Special mounting configurations for attachment to synchros, servo motors, gear heads, drive motors, counters and potentiometers. These complete assemblies are also available to your requirements from Autotronics.

11. Installation • Autotronics’ precision clutches, brakes and clutch/brake combination units are very rugged devices that will deliver reliable service when properly handled and installed. There are a few precautions that should be noted to assure the user of maximum reliability and service. When mounting gears to the input flanges, care should be taken to use the proper length screws. A screw that is too long will pass through the flange and gear and exert considerable pressure against the body.

13. Inspection A complete inspection record is packed with every Autotronics’ precision clutch, brake and clutch/ brake unit. It is sometimes necessary to re inspect a clutch or brake after it has been in service for some time or has been removed from an assembly. The main points of inspection should be the operational characteristics. The electrical characteristics of the clutch or brake will not change appreciably, i.e., coil resistance, response time, pull-in and drop-out voltages, and insulation resistance, unless some damage has been done. The mechanical characteristics that should be checked are: the clutch torque, brake torque, no-load drag torque, shaft runout and input hub runout.

15. General Characteristics 1. Zero Backlash. 2. No axial displacement when energized or de-energized. End play when measured with 5 oz. reversing load - .001” maximum. 3. No angular displacement when clutching or braking. 4. Instrument ball bearings Class ABEC 5 or better used throughout precision units. 5. Output shaft available on either or both ends. 6. Units meet all applicable specifications of MIL-E-5272B and C Environments. 7. Normal operating voltage, 24 to 28 volts D.C. (Special voltages available to order from 6 volts thru 150 volts D.C.) 8. Coils insulated for 500 volts R.M.S. 9. Coils and terminals are completely impregnated and potted into position. 10. Life in excess of one million operations. Tested at 60 cps. 11. All units will maintain minimum guaranteed torque throughout ambient temperature range of –55°C to +125°C. 12. Input flange tapped for gear or coupling, no alignment problem. 13. Input and output shafts are concentric with the servo-mounting pilot within .0015” T.I.R. 14. Gears can be provided in place of the input flange.

16. Applications The applications for Autotronics’ clutches, brakes and clutch/brake combination units are many and varied. A few of the most common ones will be presented here in order to give an idea of the versatility of the Autotronics’ electro-magneti • Servo and pot return to neutral. mc brake clutch potentiometer potentiometer mc brake clutch mc brake clutch potentiometer load servo motor mb clutch brake potentiometer • Duplex Clutch (Model MBC) Speed changing without decoupling can be accomplished easily using the MBC duplex clutch. One flange is coupled to the output shaft when the clutch is deenergized; the other flange is free running. Energizing the clutch releases the first flange and couples the second one. The action is analogous to that of a single pole, double throw switch. • Triplex Clutch (Model CCC) The CCC triplex clutch has many applications in speed changers, direction changers and additive controls. Their use in speed or direction changing is determined by the need for uncoupling in addition to the function desired.

17. 4 Triplex Brake/Clutch (Model CBC) The triplex brake/clutch has a variety of actions which can all be utilized in operating, holding, and releasing of functions in system applications.

18. Fuel Cells A fuel cell is an electrochemical energy conversion device. It produces electricity from various external quantities of fuel (on the anode side) and an oxidant (on the cathode side). These react in the presence of an electrolyte. Generally, the reactants flow in and reaction products flow out while the electrolyte remains in the cell. Fuel cells can operate virtually continuously as long as the necessary flows are maintained. Fuel cells are different from batteries in that they consume reactant, which must be replenished, whereas batteries store electrical energy chemically in a closed system. Additionally, while the electrodes within a battery react and change as a battery is charged or discharged, a fuel cell's electrodes are catalytic and relatively stable.) Proton Exchange Membrane Proton exchange membrane fuel cells, also known as polymer electrolyte membrane fuel cells (PEMFC), are a type of fuel cell being developed for transport applications as well as for stationary and portable applications. Their distinguishing features include lower temperature/pressure ranges (50-100 degrees C) and a special polymer electrolyte membrane.) Construction and Working A proton exchange membrane fuel cell transforms the chemical energy liberated during the electrochemical reaction of hydrogen and oxygen to electrical energy, as opposed to the direct combustion of hydrogen and oxygen gases to produce thermal energy. A stream of hydrogen is delivered to the anode side of the membrane-electrode assembly (MEA). At the anode side it is catalytically split into protons and electrons.

19. This oxidation half-cell reaction is represented by: newly formed protons permeate through the polymer electrolyte membrane to the cathode side. The electrons travel along an external load circuit to the cathode side of the MEA, thus creating the current output of the fuel cell. Meanwhile, a stream of oxygen is delivered to the cathode side of the MEA. At the cathode side oxygen molecules react with the protons permeating through the polymer electrolyte membrane and the electrons arriving through the external circuit to form water molecules. This reduction half-cell reaction is represented by membrane must conduct hydrogen ions (protons) but not electrons as this would in effect "short circuit" the fuel cell. The membrane must also not allow either gas to pass to the other side of the cell, a problem known as gas crossover. Finally, the membrane must be resistant to the reducing environment at the cathode as well as the harsh oxidative environment at the anode. Splitting of the hydrogen molecule is relatively easy by using a platinum catalyst. Unfortunately however, splitting the oxygen molecule is more difficult, and this causes significant electric losses Autotronics.

20. Volt Technology As vehicles have become more and more complex with n number of accessories such as multimedia, climate control, safety systems, and then are the engine and transmission systems such as sensors and actuators, fuel pumps, coolant pumps etc. All these are increasing the load on the electric battery of a car. If the car is being kept on loaded with such amenities, soon then 12 V system of a car will no longer be able to cope with the power demands. Even today, some high end car manufacturers are being faced with this problem of electric energy. Moreover, with more electric power on board, some systems that use hydraulic or mechanical principles can be converted to electric thereby reducing overall long term cost. Today’s 12V batteries are charged by 14V supply. A 42V technology offers a 4 fold leap in the power output, and thus the charging power as well. Hence it is termed as 42V (i.e. 14V x 4 = 42V) technology. Timeline of automotive electrical power source. The various milestones in the automotive electrical power source is as given below: Invention of cars used 6 V technology 1912: Electric starter motor developed which changed electric needs of a car. Early 1950s: Implementation of high powered headlights. Introduction of high compression V8 engines with higher spark demands. Late 1950s: 6 volt batteries transited to 12V batteries.

21. It is sometimes referred to as 14V also as the charging voltage for the battery was 14V. transition was easy as the new systems utilized 6V technology that was simply adapted to work on higher voltages. 1960s and 70s: Transistors and integrated circuits replaced vacuum tubes. Radios became compact and portable and thus were fitted in cars. Along with this came the requirement of instantaneous warm-up, electronic engine controls, seat belt/starter interlock systems were the first to show up on cars. 1980s: Power demands of cars growing by 4% a year, and we are already crossing the 2kW mark. 3kW is a kind of breaking point for the 12V battery system. At 3kW power consumption, 79% of engine power will not make it to the driveline! 1990s: Thought of ‘beltless’ engines, which means engine drives only drivelines. Compressor fuel pumps etc driven by alternate electric source. It was here that 42V technology was coined. 1996: Mercedes sponsored MIT students completed report on 42V technology after a detailed study of American and German OEMs. 2002-2003: Early predictions of 1990s showed that 42V systems would be introduced in cars by this year. However many roadblocks prevented it from hitting the road. 2004: European OEMs claim to have ready technology to incorporate the 42V systems. 2010: Estimated time by which 42V technology will be introduced in production cars. 3.3) Roadblocks Inspite of the potential advantages of the technology, the industry is not completely sure on the profit aspects of the system. Volt Technology Economic hurdles

22. Charging System Requirements of a charging system. Dynamo: Principle of operation, construction and working. Regulators, Combined current and voltage regulators, etc. Alternator: Principle of operation, Construction, working. Rectification of AC to DC. 4.1) Introduction The modern charging system hasn't changed much in over 40 years. It consists of the alternator, regulator (which is usually mounted inside the alternator) and the interconnecting wiring. The purpose of the charging system is to maintain the charge in the vehicle's battery, and to provide the main source of electrical energy while the engine is running. If the charging system stopped working, the battery's charge would soon be depleted, leaving the car with a "dead battery." If the battery is weak and the alternator is not working, the engine may not have enough electrical current to fire the spark plugs, so the engine will stop running.

24. Requirements of Charging System The current demands on a modern vehicle are tremendous. The charging system must answer to these demands and also be able to charge the battery under all operating conditions. The charging output should be constant voltage regardless of engine load or speed. In brief, the following are the requirements of a charging system 1. Supply the current demand made by all loads. 2. Supply whatever charge current the battery demands. 3. Operate at idle speed. 4. Supply constant voltage under all conditions. 5. Have an efficient power to weight ratio. 6. Be reliable, quiet and have resistance to contamination. 7. Require low maintenance. 8. Provide an indication of correct operation

25. Charging system Graph The three important blocks of a charging system are the generator, battery and the loads. There are 2 configurations which are possible. They are shown in fig 4.3.1. when the alternator voltage is less than the battery (engine slow or not running for example), the direction of current flow is from battery to the vehicle loads. The alternator diodes prevent the current flowing into the alternator. When the alternator output is greater than the battery voltage, current will flow from the alternator to the vehicle loads and the battery. Thus it is clear that alternator battery voltage needs to be greater than the battery voltage at all times when the engine is running

27. Vehicle Charging System The main consideration of the charging voltage is the battery terminal voltage when fully charged. If the charging system voltage is set to this value, there can be no risk of overcharging the battery. This is knaown as the constant voltage charging technique. An amount of 14.2 ± 0.2V is the accepted charging voltage for a 12V system. The other areas for consideration when determining the charging voltage are any expected voltage drops in the charging circuit wiring and the operating temperature of the system and battery.

29. Voltage Regulator In older electromechanical regulators, voltage regulation is easily accomplished by coiling the sensing wire to make an electromagnet. The magnetic field produced by the voltage attracts a moving ferrous core held back under spring tension or gravitational pull. As the voltage increases, the magnetic field strength also increases, pulling the core towards the field and opening a mechanical power switch. As the voltage decreases, the spring tension or weight of the core causes the core to retract, closing the switch allowing the power to flow once more.

30. If the mechanical regulator design is sensitive to small voltage fluctuations, the motion of the solenoid core can be used to move a selector switch across a range of resistances or transformer windings to gradually step the output voltage up or down, or to rotate the position of a moving-coil AC regulator. Early automobile generators and alternators had a mechanical voltage regulator using one, two, or three relays and various resistors to stabilize the generator's output at slightly more than 6 or 12 V, independent of the engine's rpm or the varying load on the vehicle's electrical system.

31. Engine Starting requirements An IC engine requires the following in order to start and then continue in operation Combustible mixture Compression stroke A form of ignition (by spark plug in SI engine and by Glow plug during the time of starting for CI engine) Minimum starting speed (approx 100 rpm) In order to produce the first three of these, a minimum rpm of 100 is necessary, that is the fourth condition. This is where the electric starter comes in. the ability to reach this minimum speed is again dependant of the following factors Rated voltage of the starting system. Lowest possible temperature at which the system must function. This is known as starting limit temperature. Engine cranking torque. In other words the torque that has to be applied to start the engine. Battery characteristics. Voltage drop between battery and starter. Starter to ring gear ratio. Characteristics of the starter. Minimum cranking speed of the engine at starting limit temperature . The basic diagram of the engine starting system in conjunction with the other electric systems of a car.

32. Electrical system of a car

33. Starting system Various Torque terms used with engine starting There is basic 2 torques associated with engine starting. One is the starter torque and other is the engine torque. It must be noted that engine torque here is related to the amount of torque required for the engine to crank and thus eventually start. For passenger cars starter torque of 10 to 30 Nm is employed, and for heavy vehicles it is in the range 50 to 100 Nm. The starter torque and the engine torque vary considerably with temperature . Engine rpm vs required torque wrt torques. Typical starting limit temperatures are usually quoted by manufacturers at -20oC and +20oC and torque values are mentioned. Starting limit temperatures for typical vehicles are as follows: -18oC to -25oC for passenger cars. -15oC to -20oC for trucks and busses.

34. Ignition System Ignition systems Capacitor Discharge Ignition System, Distributor less ignition system, direct ignition system. Hall effect pulse generator, Inductive pulse generator, Constant dwell system, constant energy Functional requirements The main function of the ignition system is to give spark to the engine inside the combustion chamber at the end of the compression stroke, to ignite the A/F mixture in SI engines.

35. Constant energy systems Constant energy means that, within limits, the energy available to the spark plug remains constant under all working conditions. The basis of this system is that the dwell must increase with the increase in engine speed. This will only benefit if the ignition coil can be charged to its full capacity in a smaller time, i.e. the time available for the maximum dwell at the highest possible engine speed. The constant energy coils are very low resistance and low inductance. Typical resistance is less than 1 ohm. Due to the high nature of constant energy ignition coils, the coil cannot be allowed to be switched on for more than a certain time. This is not a problem when engine is running at variable dwell or current limiting circuits which limits coil overheating. Some form of protection must be provided for when the ignition is on but engine is not running. This is called the ‘stationary engine primary current cutoff’ An energy value of 0.3 mJ is required to ignite a static stoichiometric ratio. In some conditions, the need rises to 3- 4 mJ. This has made constant energy almost essential for all today's vehicle to meet the stringent emission norms. Fig – Constant energy systems

37. Wiring Different connections used in cars .Wiring harness system The vehicle harness system has developed over the years from a loom containing just a few wires, and to looms used at present in top of the range vehicles, containing as much as 1000 separate wires. Modern vehicles have wiring harness constructed in a number of ways, which are given as follows: Bundle of wires wrapped in non adhesive PVC tape. The tape is non adhesive as it gives flexibility to the bundle of wires Place the cables side by side and plastic weld them. This makes it flat, which causes the cables to run through thin sections such as under the carpets etc. The wires are placed in tubes of contours designed as per shape of the car. It makes the harness design waterproof and also makes it better sealing.

39. Electronic Engine Controls • Electronic Engine Controls Electronic control module (ECM), operating modes of ECM (closed loop and open loop), inputs and output signals from ECM. Electronic spark timing, Electronic spark control, Air management system, Idle speed control. • Electronic Control Module (ECM) In automotive electronics, an electronic control module (ECM), also called a control unit or control module is an embedded system that controls one or more of the electrical subsystems in a vehicle.

40. Transmission Control Unit (TCU) This is common in automatic transmission which facilitates gear changes and various gear ratios in automatic/semi-automatic transmission system. Telephone Control Unit (TCU)deals with telematics and telemetry . Man Machine Interface (MMI)Deals with the ergonomical aspects of the vehicle. Door Control unit deals with aspects such as door locking, child safe door locking Seat Control Unit deals with automatic seat positioning as per driver needs in case of multiple driver driven vehicle (one car may be driven by more than one people Climate Control Unit adjusts the climate inside the car in context to temperature and humidity. Controls operation of air conditioner and car heater in conjunction to the set value. An engine control unit (ECU) is an electronic control unit which controls various aspects of an internal combustion engines operation.

41. Sensors and Actuators SENSORS Thermisters, inductive sensors, position sensors (rotary and linear), Pressure sensors, Knock sensors, Hot wire and thin film air flow sensors, vortex flow/turbine fluid flow sensors, optical sensors, oxygen sensors, light sensors, methanol sensor, rain sensor, operating principles, application and new developments in the sensor technology. ACTUATORSIntroduction, function, operating principles, construction of solenoid actuators, relays, motorizes actuators, thermal actuators, electrohydraulic actuators, electromechanical valve actuators etc. application and new developments in actuator technology . SENSORS PRINCIPLES Sensors are those systems/components that give an electrical signal that is relative to the parameter they are measuring. These are extensions of transducers. All sensor use transducer technology, in conjunction with other systems/technology to measure the given parameter and give a suitable output . Thermisters A thermistor is a type of resistor with resistance varying according to its temperature. The word is a combination of thermal and resistor. Thermisters are of 2 types, they are given as follows NTC Type To measure the temperature of air and fluid in vehicle sensor materials which change their electrical resistance with effect of heat is used. Most of these sensors are NTC Resistors, for example the coolant temperature sensor, the changed air temperature sensor. Consider the coolant temperature sensor. The sensor consists of a semi conductor material which has the negative temperature co-efficient. This means the resistance of sensor drops as temperature increases.

42. Lighting and Reflectors Lighting Types of lamps ,energy demands of lamps,. Head lamps: construction and types, setting and control. Reflectors: parabolic, homifocal, poly-elipsoidal. Fog lamp, side lamp, tail lamp, parking lamp, brake warning lamp, , trafficators, blinkers, flashers, electronic flasher circuit, instrument panel. 10.1) Types of lamps There are various lamps used in cars. Lighting • Halogen bulb, twin filament Headlight reflectors The light produced by the bulb is insufficient as it is directed toward a particular direction only. To give the light emitted from the bulb, a definite pattern to cover considerate amount of longitudinal and lateral visibility. Headlights are used which reflect the light from the bulb into a particular pattern on the road. The object of the headlight reflector is to direct the random rays of light produced by the source (i.e. the bulb) into a concentrated beam of light by applying laws of reflection. Bulb position relative to the reflector is important. It determines the exact pattern of the light beam.

43. Accessories Instrument panel, Electric horn, wipers, fuel pump, power operated windows etc. Function of Instrument panel Vehicle conditioning monitoring (VCM) is a technique when relevant vehicle performance parameters are displayed to the driver. The purpose of this is to either just to keep the driver informed with any warnings in response to which the driver may take action Electric horn Automobile horns are usually electric klaxons, driven by a flat circular steel diaphragm that has an electromagnet acting upon it and is attached to a contactor that repeatedly interrupts the current to the electromagnet. This arrangement works like a buzzer or electric bell. There is usually a screw to adjust the distance/tension of the electrical contacts for best operation.

44. ELICTRICAL AND WIRING SYSTEM On this system, the power is fed to the driver's door through a 20-amp circuit breaker. The power comes into the window-switch control panel on the door and is distributed to a contact in the center of each of the four window switches. Two contacts, one on either side of the power contact, are connected to the vehicle ground and to the motor. The power also runs through the lockout switch to a similar window switch on each of the other doors. When the driver presses one of the switches, one of the two side contacts is disconnected from the ground and connected to the center power contact, while the other one remains grounded. This provides power to the window motor. If the switch is pressed the other way, then power runs through the motor in the opposite direction.

45. Telematics • The term telematics is used in a number of ways: It can be defined as the integrated use of telecommunications and informatics, also known as ICT (Information and Communications Technology). More specifically it is the science of sending, receiving and storing information via telecommunication devices. More commonly, telematics have been applied specifically to the use of Global Positioning System technology integrated with computers and mobile communications technology in automotive navigation systems.

46. Intelligent Vehicle Systems Telematicscomprise electronic, electromechanical, and electromagnetic devices — usually silicon micro machined components operating in conjunction with computer controlled devices and radio transceivers to provide precision repeatability functions (such as in robotics artificial intelligence systems) emergency warning validation performance reconstruction. Intelligent vehicle technologies commonly apply to car safety systems and self-contained autonomous electromechanical sensors generating warnings that can be transmitted within a specified targeted area of interest, say within 100 meters of the emergency warning system for vehicles transceiver. In ground applications, intelligent vehicle technologies are utilized for safety and commercial communications between vehicles or between a vehicle and a sensor along the road. Auto insurance The basic idea of telematic auto insurance is that a driver's behavior is monitored directly while the person drives and this information is transmitted to an insurance company. The insurance company then assesses the risk of that driver having an accident and charges insurance premiums accordingly. A driver who drives long distance at high speed, for example, will be charged a higher rate than a driver who drives short distances at slower speeds.

47. Intelligent Vehicle Systems ABS system ABS components Wheel speed sensors Most of these devices are simple inductance sensors and work in conjunction with a toothed wheel. They consist of a permanent magnet and a soft iron rod around which is wound a coil of wire. As the toothed wheel rotates the changes in inductance of the magnetic circuit generates a signal; the frequency and voltage of which are proportional to wheel speed. The frequency is the signal used by the ECU.

49. Active Suspension Active suspension is an automotive technology that controls the vertical movement of the wheels via an onboard system rather than the movement being determined entirely by the surface on which the car is driving. The system therefore virtually eliminates body roll and pitch variation in many driving situations including cornering, accelerating, and braking. This technology allows car manufacturers to achieve a higher degree of both ride quality and car handling by keeping the tires perpendicular to the road in corners, allowing for much higher levels of grip and control.

50. Electric Power Steering Electric power steering (EPS or EPAS) is designed to use an electric motor to reduce effort by providing assist to the driver of a vehicle. Most EPS systems have variable assist, which allows for more assistance as the speed of a vehicle decreases and less assistance from the system during high-speed situations. This functionality requires a delicate balance of power and control that has only been available to manufacturers in recent years.