Aunmmonv
`ununnoox
`
`EDITION
`
`BMW1042
`Page 1 of 23
`
`

`

`Reproduction, duplication and translation
`of this publication,
`including excerpts
`therefrom,
`is only to ensue with our
`previous written consent and with parti(cid:173)
`culars of source. Illustrations, descrip(cid:173)
`tions, schematic diagrams and other data
`serve only for explanatory purposes and
`for presentation of the text. They cannot
`be used as the basis for design, installa(cid:173)
`tion, and scope of delivery. We undertake
`no liability for conformity of the contents
`with national or local regulations.
`We reserve the right to make changes.
`The brand names given in the contents
`serve only as examples and do not repre(cid:173)
`sent the classification or preference for a
`particular manufacturer. Trade marks are
`not identified as such.
`The following companies kindly placed
`picture matter, diagrams and other infor-
`'
`mative material at our disposal:
`Audi AG, lngolstadt;
`Bayerische Motoren Werke AG, Munich;
`Behr GmbH & Co, Stuttgart;
`Brose Fahrzeugteile GmbH & Co. KG,
`Coburg;
`Continental AG , Hannover;
`Eberspacher KG, EB1ingen;
`Filterwerk Mann und Hummel,
`Ludwigsburg;
`Ford-Werke AG, Cologne;
`Aktiengesellschaft Kuhnle, Kopp und
`Kausch, Frankental;
`Mannesmann Kienzle GmbH,
`Villingen-Schwenningen;
`Mercedes-Benz AG, Stuttgart;
`Pierburg GmbH, Neuss;
`RWE Energie AG, Essen;
`Volkswagen AG, Wolfsburg;
`Zahnradfabrik Friedrichshafen AG,
`Friedrichshafen.
`Source of information for motor-vehicle
`specifications: Automobil Revue Katalog
`1995.
`
`Imprint
`
`Published by:
`© Robert Bosch GmbH, 1996
`Postfach 30 02 20
`D-70442 Stuttgart
`Automotive Equipment Business Sector,
`Department for Technical Information
`(KHNDT).
`Management: Dipl.-lng.(FH) Ulrich Adler.
`
`Editor in chief:
`Dipl.-lng.(FH) Horst Bauer.
`
`Editors:
`lng.(grad.) Arne .Cypra,
`Dipl.-lng. (FH) Anton Beer,
`Dipl.-lng. Hans Bauer.
`
`Production management:
`Joachim Kaiser.
`
`Layout:
`Dipl.-lng.(FH) Ulrich Adler,
`Joachim Kaiser.
`
`Translation:
`Editor in chief:
`Peter Girling
`Translated by:
`lngenieurbOro fur T~chnische und
`Wissenschaftliche Ubersetzungen
`Dr. W.-D. Haehl GmbH, Stuttgart
`Member of the ALPNET Services Group
`William D. Lyon
`
`Technical graphics:
`Bauer & Partner GmbH, Stuttgart.
`Design, front cover, front matter:
`Zweckwerbung, Kirchheim u.T., Germany
`Technische Publikation, Waiblingen
`
`Distribution, 4th Edition:
`SAE Society of Automotive Engineers
`400 Commonwealth Drive
`Warrendale, PA 15096-0001 U.S.A.
`ISBN 1-56091-918-3
`
`Printed in Germany.
`lmprime en Allemagne.
`
`4th Edition, October 1996.
`
`Editorial closing: 31.08.1996
`
`BMW1042
`Page 2 of 23
`
`

`

`4 Contents
`
`Contents
`
`10
`17
`39
`44
`52
`60
`66
`70
`86
`102
`122
`130
`135
`
`142
`150
`
`156
`164
`166
`170
`
`Physics, basics
`Quantities and units
`Conversion tables
`Vibration and oscillation
`Mechanics
`Strength of materials
`Acoustics
`Heat
`Electrical engineering
`Electronics
`Sensoren
`Actuators
`Electric machines
`Technical optics
`Mathematics, methods
`Mathematics
`Quality
`Engineering statistics,
`measuring techniques
`Reliability
`Data processing in motor vehicles
`Control engineering
`Materials
`174
`Chemical elements
`178
`Terminology and parameters
`180
`Material groups
`Material properties
`184
`Lubricants
`224
`232
`Fuels
`244
`Chemicals
`Corrosion and corrosion protection 250
`Heat treatment
`260
`Hardness
`266
`Maschine elements
`Tolerances
`Sliding and rolling bearings
`Spring calculations
`Gears and tooth systemsg
`Belt drives
`Threaded fasteners
`Joining and bonding techniques
`Welding
`Soldering
`Adhesives
`Riveting
`Pressurized clinching
`Punch riveting
`Sheet-metal processing
`Tribology, wear
`
`271
`274
`282
`288
`298
`302
`
`311
`313
`314
`315
`316
`317
`
`318
`321
`
`326
`327
`330
`342
`
`346
`
`351
`354
`356
`
`Motor-vehicle dynamics
`Road-going vehicle requirements
`Fuel requirements
`Dynamics of linear motion
`Dynamics of lateral motion
`Evaluating operating behavior
`(as per ISO)
`Special operating dynamics
`for commercial vehicles
`Agricultural-tractor requirements
`Environmental stresses
`Internal-combustion (IC) engines
`Operating concepts and classification 358
`Thermodynamic cycles
`359
`Reciprocating-piston engines
`with internal combustion
`361
`The spark-ignition (Otto) engine 364
`The diesel engine
`368
`Hybrid processes
`373
`Gas exchange
`374
`Supercharging/turbocharging
`378
`Power transfer
`382
`Cooling
`398
`Lubrication
`398
`Empirical values
`and data for calculations
`Reciprocating-piston engine with
`external combustion (Stirling engine)
`The Wankel rotary engine
`Gas turbines
`Engine cooling
`Air and water cooling
`Charge-air cooling/intercooling
`Oil cooling
`Intake air, exhaust systems
`Air filters
`Turbochargers and superchargers
`Exhaust systems
`Engine management for spark-
`ignition (SI) engines
`Control parameters and operation
`
`400
`412
`
`414
`416
`
`418
`420
`421
`
`422
`424
`430
`
`434
`
`436
`
`Ignition
`Basics
`Components
`Ignition coils
`Spark plugs
`Ignition systems
`Conventional coil ignition (Cl)
`445
`Transistorized ignition (Tl)
`448
`Capacitor-discharge ignition (COi) 450
`Electronic ignition (ESA and DU) 451
`Knock control
`454
`
`439
`440
`
`BMW1042
`Page 3 of 23
`
`

`

`Fuel supply
`Electric fuel pumps
`456
`Fuel management
`458
`459
`Carburetors
`Single-point fuel-injection systems (TBI )462
`Mono-Jetronic
`462
`Multipoint fuel-injection systems
`464
`K-Jetronic
`464
`KE-Jetronic
`466
`L-Jetronic
`468
`471
`LH-Jetronic
`Other engine-control functions
`473
`Idle-speed control
`474
`Electronic throttle control (ETC)
`474
`Electronic boost-pressure control
`Variable-geometry intake manifold 476
`Evaporative-emissions control system 477
`477
`Exhaust-gas recirculation (EGR)
`Integrated engine-management
`system, Motronic
`Detection and processing of
`measured variables
`Motronic system
`System configuration
`Racing applications
`Engine test technology
`Exhaust emissions from spark(cid:173)
`ignition (SI) engines
`Combustion products
`Emissions control
`Lambda closed-loop control
`Testing exhaust and evaporative
`494
`emissions
`496
`Test cycles and emission limits
`500
`Exhaust-gas analyzers
`Internal-combustion (IC} engines for
`alternative fuels .
`501
`LPG systems
`504
`Alcohol operation
`505
`Hydrogen operation
`Engine management (diesel engines)
`Fuel metering
`506
`Fuel-injection pumps, in-line
`508
`Fuel-injection pumps, control sleeve 514
`Fuel-injection pumps, distributor type 515
`Fuel-injection pumps,
`distributor-type, solenoid-controlled 518
`Time-controlled single-pump systems 519
`Common-rail system
`521
`Injection-pump test benches
`523
`Nozzles and nozzle holders
`524
`
`479
`480
`483
`483
`484
`
`486
`487
`490
`
`Contents 5
`
`541
`544
`
`545
`551
`
`554
`556
`559
`569
`571
`573
`574
`
`Exhaust emissions (diesel engines)
`Emissions control
`530
`Emissions testing
`531
`Test cycles and exhaust-emission
`533
`limits in Europe
`Exhaust-emissions testing equipment 536
`Auxiliary starting devices (diesel engines)
`Sheathed-element glow plugs
`538
`GI ow control unit
`539
`Starting systems
`Starters
`Starter protection devices
`Alternative drive systems
`Electric drives
`Hybrid drives
`Drivetrain
`Basics
`Clutches and couplings
`Transmissions and gearboxes
`Final-drive units
`Differentials
`All-wheel drive (AWD)
`Traction control (ASR)
`Chassis systems
`Suspension
`Suspension linkage
`Wheels
`Tires
`Steering
`
`580
`588
`592
`596
`606
`
`Braking systems
`Definitions, principles
`Legal regulations
`Design and components of a
`braking system
`Braking-system design
`Braking-force apportioning
`Braking systems for passenger cars
`and light utility vehicles
`Control devices
`Wheel brakes
`Braking-force distribution
`Antilock braking systems (ABS)
`for passenger cars
`Braking systems
`for commercial vehicles
`System and configuration
`Braking-force metering
`Wheel brakes
`Parking-brake systems
`Retarder braking systems
`Components for compressed-
`air brakes
`
`612
`616
`
`620
`621
`622
`
`624
`624
`625
`626
`
`627
`
`640
`640
`641
`644
`648
`648
`
`653
`
`BMW1042
`Page 4 of 23
`
`

`

`6 Contents
`
`659
`
`663
`666
`
`668
`669
`670
`676
`
`678
`679
`
`680
`684
`685
`
`Antilock braking systems (ABS)
`for commercial vehicles
`Electronically controlled
`braking system (ELB)
`Brake test stands
`Vehicle Dynamics Control (VDC)
`Task
`Vehicle handling
`Control system
`System realization
`Road-vehicle systematics
`Overview
`Classification
`Vehicle bodies, passenger car
`Main dimensions
`Body structure
`Body materials
`Body surface,
`686
`body finishing components
`688
`Safety
`692
`Calculations
`Vehicle bodies, commercial vehicles
`Commercial vehicles,
`delivery trucks and vans
`Medium and heavy-duty trucks
`695
`and tractor vehicles
`696
`Buses
`698
`Passive safety
`Noise reduction in commercial vehicles 699
`
`694
`
`Lighting
`700
`Legal regulations
`701
`Main headlamps
`714
`Headlamp range adjustment
`715
`Fog lamps
`Auxiliary driving lamps, lights and lamps716
`Visual signalling devices
`722
`Headlamp aimjng devices
`723
`Bulbs
`724
`Signaling devices and alarm systems
`Acoustic signaling devices
`726
`Theft-deterrent systems
`727
`Windshield and headlamp cleaning
`Windshield-wiper systems
`730
`Rear-window wiper systems
`731
`Headlamp cleaning systems
`732
`Drive motors
`732
`733
`Washing systems
`Windshield and window glass
`734
`Heating, ventilation,
`and air-conditioning (HVAC)
`Heating systems using engine heat 736
`
`Air conditioners
`Auxiliary heater installations
`Communications and information
`systems
`Automotive sound systems
`Parking systems
`Trip recorders
`Navigation systems
`Mobile radio
`Board Information Terminal (BIT)
`
`737
`739
`
`7 40
`7 43
`7 46
`7 48
`750
`752
`
`762
`763
`764
`766
`769
`770
`
`773
`774
`776
`
`778
`779
`
`Safety systems
`753
`Seatbelt-tightener systems
`753
`Front airbag systems
`756
`Side airbag systems
`757
`Rollover protection system
`Comfort and convenience systems
`Power windows
`758
`Power sunroof
`759
`Seat and steering-column adjustment 760
`761
`Central locking system
`Automotive hydraulics
`Basics
`Gear pumps and motors
`Piston pumps and motors
`Valves
`Cylinders
`Tractor hydaulics
`Hydraulic accumulators,
`auxiliary drives
`Hydrostatic fan drives
`Hydrostatic drives
`Automotive pneumatics
`Door operation (buses)
`Radiator louvers
`Electrical system and power
`supply
`780
`Symbols
`784
`Circuit diagrams
`792
`Conductor-size calculations
`Electrical power supply in the vehicle 794
`Controller Area Network (CAN)
`800
`Starter batteries
`803
`Battery chargers
`807
`Alternators
`808
`Electromagnetic compatibility (EMC) 816
`and interference suppression
`Passenger car specifications
`Road traffic legislation
`Miscellaneous
`Alphabets and numbers
`Index of headings
`
`822
`852
`
`862
`863
`
`BMW1042
`Page 5 of 23
`
`

`

`44 Basic equations used in mechanics
`
`Basic equations used in mechanics
`See pp. 12 - 16 for names of units
`
`Symbol Quantity
`
`SI-Unit
`
`Symbol Quantity
`
`A
`a
`act
`
`d
`E
`Ek
`Ep
`F
`Fc1
`G
`g
`
`h
`i
`J
`
`L
`l
`M
`
`Area
`Acceleration
`Centrifugal-
`acceleration
`Diameter
`Energy
`Kinetic energy
`Potential energy
`Force
`Centrifugal force
`Weight
`Acceleration of free fall
`(g = 9,81 m/s2, seep. 11)
`Height
`Radius of gyration
`Moment of inertia
`(second moment of
`mass)
`Angular momentum
`Length
`Moment of force/Torque
`
`m2
`m/s2
`m1s2
`
`m
`J
`J
`J
`N
`N
`N
`m1s2
`
`m
`m
`kg. m2
`
`N·s · m
`m
`N · m
`
`m
`n
`p
`p
`r
`s
`T
`
`t
`V
`V
`
`w
`a
`E
`µ
`e
`<p
`(i)
`
`Mass (weight)
`Rotational frequency
`Power
`Linear momentum
`Radius
`Length of path
`Period, time of one
`revolution
`Time
`Volume
`Velocity
`v1 Initial velocity
`ui Final velocity
`Vm Work, energy
`Work, energy
`Angular acceleration
`Wrap angle
`Coefficient of friction
`Density
`Angle of rotation
`Angular velocity
`
`SI-Unit
`
`kg
`s-1
`w
`N ·s
`m
`m
`s
`
`s
`m3
`m/s
`
`J
`rad/s2 1)
`rad1)
`-
`kg/m3
`rad1)
`rad/s1)
`
`Relationships between quantities, numbers
`If not otherwise specified, the following relationships are relationships between
`quantities, i. e. the quantities can be inserted using any units (e. g., the SI units given
`above). The unit of the quantity to be calculated is obtained from the units chosen for the
`terms of the equation.
`In some cases, additional numerical relationships are given for customary units (e. g.,
`time in s, but speed in km/h). These relationships are identified by the word "numerical
`relationship", and are only valid if the units given for the relationship are used.
`
`Rectilinear motion
`
`Uniform rectilinear motion
`Velocity
`v=slt
`Uniform rectilinear acceleration
`Mean velocity
`Vm = (v1 + V2)/2
`
`Acceleration
`a= (v2 - v1)/t = (~ - vf )/(2s)
`Numerical relationship:
`a= (v2 - v1)/(3.6 t)
`a in m/s2, v2 and v1 in km/h, t in s
`
`1) The unit rad (= m/m) can be replaced by the
`number 1.
`
`Distance covered after time t
`S = Vf · t = V1 • t + (a· t2)/2
`= (v2 - Vf )/(2a)
`Final velocity
`v2 = V1 +a· t = Vvf + 2a · s
`Initial velocity
`v1=v2-a·t =Vvt- 2a ·s
`For uniformly retarded motion ( v2 smaller
`than v 1) a is negative.
`. .
`For acceleration from rest, substitute
`v 1 = O For retardation to rest, substitute
`V2= 0.
`
`BMW1042
`Page 6 of 23
`
`

`

`Basic equations used in mechanics 45
`
`Force
`F=m·a
`
`Work, energy
`W=F·s=m·a·s=P ·t
`
`Potential energy
`Ep= G · h = m · g · h
`
`Kinetic energy
`Ek=m · v/2
`
`Power
`P= Wlt=F· V
`
`Lifting power
`P=m·g·v
`
`Linear momentum
`p=m· V
`
`Rotary motion
`Uniform rotary motion
`Peripheral velocity
`v=r· w
`Numerical relationship:
`V = :rt • d · n/60
`v in m/s, d in m, n in min-1
`V = 6 • :rt• d · n/100
`v in km/h, d in m, n in min-1
`Angular velocity
`w = cplt = v/r = 2.n · n
`Numerical relationship:
`w = :r · n/30
`win s-1, n in min-1
`
`Uniform angular acceleration
`Angular acceleration
`a= (l0-2 - w1)/t .
`Numerical relationship
`a= 3t (n2 - n1)/(30t)
`a in 1 /s2, n1 and n2 in min-1 , t in s
`Final angular velocity
`w.i=w1 +a·t
`
`Initial angular velocity
`W1 =l0-2-a·t
`
`rotary motion
`For uniformly retarded
`(w.i is smaller than w1) a is negative.
`Centrifugal force
`Fct = m · r · w 2 = m · v 2/r
`
`Centrifugal acceleration
`ac1 =r· w2
`
`Moment of forcerrorque
`M= F· r= Plw
`Numerical relationship:
`M= 9550 · Pin
`Min N · m, P in kW, n in min-1
`
`Moment of inertia (seep. 48)
`J=m ·i2
`
`Work
`W = M·cp=P·t
`
`Power
`P = M · w = M · 2n · n
`Numerical relationship:
`P =M· n/9550
`(see graph, p. 50)
`P in kW, Min N · m (= W · s),
`n in min-1
`
`Energy of rotation
`Erot = J · W 2/2 = J · 2.n 2 · n2
`Numerical relationship:
`Erot = J · n2/182.4
`Erot in J (= N · m), Jin kg · m2,
`n in min-1
`
`Angular momentum
`L = J · w = J · 2.n · n
`Numerical relationship:
`L = J · .n · n/30 = 0.1047 J · n
`Lin N · s · m, Jin kg · m2, n in min-1
`
`Pendulum motion
`(Mathematical pendulum, i e. a point-size
`mass suspended from a thread of zero mass)
`Plane pendulum
`Period of oscillation (time for one com(cid:173)
`plete swing back and forth)
`T = 2:rt · v'lJi
`The above equation is only accurate for
`small excursions a from the rest position (for
`a= 10°, the error is approximately 0.2 %).
`
`Conical pendulum
`Time for one revolution:
`T= 2n · V(l cos a)lg
`Centrifugal force
`F 1 = m · g · tan a
`Fct
`c
`Force pulling on thread
`Fz = m · g/cos a
`
`BMW1042
`Page 7 of 23
`
`

`

`46 Basic equations used in mechanics
`
`~
`I
`I
`t.
`
`Throwing and falling
`
`Body thrown vertically upward
`(neglecting air resistance).
`Uniform retardation.
`Retardation:
`a= g = 9.81 m/s2
`
`(See p. 44 for equation symbols)
`
`Upward velocity
`Height reached
`Time of upward travel
`
`At highest point
`
`V = V1 - g . t = V1 - ./2i77i
`h = V1 • t - 0.5 g • t2 r,..----
`V1 - V 11 - 2g . h
`V1 - V
`t= - - =
`g
`g
`2
`.!!J.
`V 2 = O; h2 = Vl ;
`2g
`g
`
`t2 :
`
`Body thrown obliquely upward
`(neglecting air resistance).
`Angle of throw a; ; superposition
`of uniform rectilinear motion
`and free fall
`
`Range of throw (maxi(cid:173)
`mum value at a = 45°)
`Duration of throw
`
`Height of throw
`
`Energy of throw
`
`v 2
`· sln2 a
`s=-1 __ _
`g
`= 2v1 • sin a
`1 =
`s
`V1 ' COS a
`g
`h= ~· s1n2a
`2g
`
`Velocity of fall
`
`V = g · t = 'V'[i7h
`
`Height of fall
`
`Time of fall
`
`h=EL:...!.= v2= v·t
`2
`2
`2g
`t = 2h = ~=~
`g
`g
`V
`
`Free fall
`(neglecting air resistance).
`Uniform acceleration;
`acceleration:
`a = g = 9.81 m1s2
`
`Fall with allowance of air
`resistance
`Non-uniform acceleration;
`initial acceleration:
`a1 = g = 9.81 m/s2, final
`acceleration a2 = O
`
`Velocity of fall
`
`The velocity of fall approaches a limiting velocity v0 at which
`the air resistance
`h = e ·cw· A· ifo/2 is as great as the weight
`G = m · g of the falling body, thus:
`vo = V"'2mc--·-g"""{(,-e_·_c_w_· A""")
`limiting velocity
`(e air density, cw coefficient of
`drag,
`A cross-sectional area of the body).
`v = v0 • y 1 - 1/x2
`The following abbreviated term is
`substituted:
`x = e8hlvi; e = 2.718
`2
`2
`h = vo
`In __!&_
`2g
`v~ -v2
`t = Vo In (x + \fx2- 1)
`g
`
`Height of fall
`
`Time of fall
`
`Example: A heavy body (mass m = 1000 kg, cross-sectional area A = 1 m2, coefficient of drag
`cw = 0.9) falls from a great height. The air density e = 1.293 kg/m3 and the acceleration of free fall
`g = 9.81 m/s2 are assumed to be the same over the entire range as at ground level.
`Height
`Neglecting air resistance, values at
`of fall
`end of fall from indicated height would be
`Time of fall
`Velocity of Energy
`s
`kJ
`fall mis
`
`Allowing for air resistance, values at
`end of fall from indicated height are
`Time of fall
`Velocity of
`Energy
`faH mis
`s
`kJ
`
`m
`
`10
`50
`100
`500
`1000
`5000
`10000
`
`1.43
`3.19
`4.52
`10.1
`14.3
`31.9
`45.2
`
`14.0
`31.3
`44.3
`99
`140
`313
`443
`
`98
`490
`980
`4900
`9800
`49000
`98000
`
`1.43
`3.2
`4.6
`10.6
`15.7
`47.6
`86.1
`
`13.97
`30.8
`43
`86.2
`108
`130
`130
`
`97
`475
`925
`3690
`5850
`8410
`8410
`
`BMW1042
`Page 8 of 23
`
`

`

`Drag coefficients cw
`
`Body shape
`
`- I
`- )
`- 0
`
`-
`
`l
`
`Disc,
`plate
`
`Open dish,
`parachute
`
`Sphere
`Re< 200 000
`Re> 250 000
`
`Slender
`
`rotating body B [ : d=6
`
`Basic equations used in mechanics 4 7
`
`Cw
`
`1.1
`
`1.4
`
`0.45
`0.20
`
`0.05
`
`Body Shi3pe
`
`_f Long cylinder
`
`Re< 200 000
`Re> 450 000
`
`-
`
`-
`
`-
`
`~Longplate
`l : d;:;30
`Re ... 500000
`Re ... 200 000
`
`~ Long airto;1
`l : d;:; 18
`l: d = 8 Re ,.. 10s
`l: d;:; 5
`l : d ;:; 2 Re "' 2 · 1 Q5
`
`I
`
`-
`
`.
`
`Cw
`
`1.0
`0.35
`
`0.78
`0.66
`
`0.2
`0.1
`0.08
`0.2
`
`Reynolds number
`
`Re = ( v + Vo} · /Iv
`
`v Velocity of body in mis,
`v0 Velocity of air in m/s,
`l Length of body in m
`(in direction of flow),
`d Thickness of body in m,
`v Kinematic viscosity in m2/s.
`For air with v = 14 · 10-s m2/s (annual
`mean 200 m above sea level
`Re ""72, 000 (v + v0) • l with v and v 0 in m/s
`Re"" 20, 000 ( v + v0) • l with v and v0 in km/h
`The results of flow measurements on
`two geometrically similar bodies of dif(cid:173)
`ferent sizes are comparable only if the
`Reynolds number is of equal magnitude
`in both cases (this is important in tests
`on models).
`
`Discharge of air from nozzles
`
`The curves below only give approximate
`values. In addition to pressure and nozzle
`cross section, the air discharge rate
`depends upon the surface and length
`of the nozzle bore, the supply line and
`the rounding of the edges of the dis(cid:173)
`charge port.
`
`m3/min
`12
`
`~ ....
`;:
`0
`;:
`....
`<(
`
`8
`
`4
`
`0
`0 2
`
`6
`
`14
`10
`Nozzle bore
`
`18mmdia.
`
`Gravitation
`Force of attraction between two masses:
`F = f (m1 · m2}lr2
`r Distance between centers of mass
`/Gravitation constant
`= 6.67 · 10-11 N · m2/kg2
`
`Lever law
`
`F1 . r1 = F2 . r2
`
`l r1:?:;;;,
`
`F1
`
`BMW1042
`Page 9 of 23
`
`

`

`130 Electric machines
`
`Electric machines
`
`Series-wound machine
`
`• , · ~.
`
`Principal of operation
`
`Electric machines are used to convert
`electrical and mechanical energy. An
`electric motor converts electrical energy
`inro mechanical energy: a generator con(cid:173)
`verts energy in the opposite direction.
`Electric machines consist of a stationary
`component (the stator) and a rotating
`component (the rotor). There are special
`designs which depart from this configura(cid:173)
`tion such as linear machines which pro(cid:173)
`duce linear motion. Permanent magnets
`or several coils (windings) are used to
`produce magnetic fields in the stator and
`rotor which cause torque to develop bet(cid:173)
`ween these two machine components.
`Electric machines have iron stators and
`rotors in order to control the magnetic
`fields. Because
`the magnetic
`fluxes
`change over time, stators and rotors must
`consist of stacks of individual laminations
`which are insulated with respect to one
`another. The spatial arrangement of the
`coils and the type of current used (direct
`current, alternating current or three(cid:173)
`phase current) permit a number of diffe(cid:173)
`rent electric machine designs. They differ
`from one another in the way they operate,
`and
`therefore have different applica(cid:173)
`tions.
`
`Direct-current machines
`
`The stator of a direct-current machine
`contains salient poles which are magne(cid:173)
`tized by the direct-current field windings.
`In the rotor (here also called the arma(cid:173)
`ture), the coils are distributed among slots
`in the laminated stack and connected to a
`commutator. Carbon brushes in the stator
`frame wipe against the commutator as it
`rotates, thereby transferring direct current
`to the armature coils. The rotation of the
`commutator causes a reversal in the
`direction of current flow in the coils. The
`different ways in which the field winding
`and armature can be connected result
`in different rotational speed vs. torque
`characteristics:
`
`-0
`
`~.-..------
`a.
`(/)
`«i
`C
`0
`~
`0 er: L.._ ____ ..J
`Torque
`
`Shunt-wound machine
`
`,:J
`~ r - - - - - (cid:173)
`CJ) r-----.._,,_1
`a. '---
`cu
`-
`C
`0 .:: .s 0 er: L . ._ - - - - - . J
`
`Torque
`
`Motor with permanent-magnet exitation
`
`Series connection
`(series characteristic)
`Rotational speed is highly dependent
`upon load; high starting torque; "racing"
`of the machine if the load is suddenly
`removed, therefore load must be rigidly
`coupled; direction of rotation changed by
`reversing the direction of current in the
`armature or field winding; used, among
`other things, as motor vehicle drive motor
`and starter motor for internal-combustion
`engines.
`
`BMW1042
`Page 10 of 23
`
`

`

`parallel (shunt) connection
`(shunt characteristic) .
`Rotational speed remains largely con(cid:173)
`stant regardless of load; direction of rota(cid:173)
`tion is changed by reversing the direction
`of the current in the armature or field win(cid:173)
`ding; used for instance, as drive motor for
`machine tools and as direct-current gene(cid:173)
`rator. A shunt characteristic can also be
`obtained by using a separate power sup(cid:173)
`ply for the field winding (separate excita(cid:173)
`tion) or by using permanent-magnet poles
`in the stator. Used for motors with perma(cid:173)
`nent-magnet excitation in the motor-vehicle
`starter motors, windshield wiper motors
`and fractional horsepower motors for
`various drives. If the motor incorporates
`both series and parallel field windings
`(compound-wound motor), intermediate
`levels in the rotational speed vs. torque
`characteristic can be obtained; applica(cid:173)
`tions: large starter motors for instance.
`All direct-current machines are easily
`capable of speed control over a wide
`range. If the machine Incorporates a sta(cid:173)
`tic converter which allows adjustment
`of the armature voltage, the torque and
`therefore the rotational speed are infini(cid:173)
`tely variable. The rotational speed can be
`further increased by reducing the field
`current (field weakening) when the rated
`armature voltage is reached. A disadvan(cid:173)
`tage of direct-current machines is carbon
`brush and commutator wear which makes
`regular maintenance necessary.
`
`Three-phase machines
`A
`three-phase winding
`is distributed
`among the stator slots in a three-phase
`machine. The three phases of current
`produce a magnetic field which rotates
`(rotating field). The speed no (in min-1 ) of
`the rotating field is calculated as follows:
`no=60 ·Jl p
`J = frequency (in Hz), p = number of pole
`pairs.
`Three-phase machines are either syn(cid:173)
`chronous or asynchronous, depending
`upon rotor design.
`
`Asynchronous machines
`The laminated rotor contains either a
`. three-phase winding, as in the stator, or a
`
`Three-phase asynchronous motor with
`squf"el-cage rotor
`Star-connected
`stator winding
`
`Delta-connected
`stator winding
`
`i. ,,
`!
`'
`
`bar winding. The three-phase winding is
`connected to slip rings which are short(cid:173)
`circuited either directly or via external re(cid:173)
`sistances. In the case of the bar winding,
`the bars are connected to one another by
`two short-circuiting rings (squirrel-cage
`rotor). As long as the rotational speed
`of the rotor deviates from no, the rotating
`stator field induces current in the rotor
`windings,
`thereby generating
`torque.
`Deviation of the rotational speed of the
`rotor n from n0 is termed slip s:
`s = (no - n) I no
`Continuous operation is only economi(cid:173)
`cal in the vicinity of n0, because losses
`increase as slip increases (nominal slip
`~ 5%). In this range the asynchronous
`machine has a shunt characteristic. The
`machine operates as a motor when n < n0,
`and as a generator when n > n0• The di(cid:173)
`rection of rotation is changed by reversing
`two of the phases.
`The asynchronous machine is the most
`frequently used electric motor in the field
`of drive engineering. With a squirrel-cage
`rotor it is easy to operate, and requires
`little maintenance.
`
`Examples of rotating field speeds
`
`Frequency
`Number of
`I 200 Hz
`I 150 Hz
`poles (2p) 50 Hz
`Rotating field speed in min-1
`3000
`9000
`12000
`1500
`4500
`6000
`1000
`3000
`4000
`750
`2250
`3000
`600
`1800
`2400
`500
`1500
`2000
`
`2
`4
`6
`8
`10
`12
`
`BMW1042
`Page 11 of 23
`
`

`

`132
`
`Electric machines
`
`Sychronous machines
`In the rotor (here also called the inductor),
`the poles are magnetized by direct-current
`coils. The magnetizing current is usually
`transferred via two slip rings to the rotor.
`The inductor can be made of solid steel,
`because the magnetic flux remains con(cid:173)
`stant over time.
`Constant torque is generated as long
`as the rotor rotates at a speed of no. At
`other speeds, the torque fluctuates peri(cid:173)
`odically between a positive and a nega(cid:173)
`tive maximum value, and excessively
`high current is produced.
`For this reason, a synchronous ma(cid:173)
`chine is not self-starting. The synchro(cid:173)
`nous machine also differs from the asyn(cid:173)
`chronous machine in that the reactive
`power absorption and generation are
`adjustable. The synchronous machine is
`most frequently used as a generator in
`electric power plants. Synchronous mo(cid:173)
`tors are used in cases where constant
`motor speed based on constant line fre(cid:173)
`quency is desired, or where a reactive
`power demand exists. The motor vehicle
`three-phase alternator is a special type of
`synchronous machine.
`The rotational speed of all three-phase
`machines is determined by the stator
`frequency. Such machines can operate
`over a wide range of speeds if used in
`conjunction with static converters which
`vary the frequency.
`
`EC Motors
`The "electronically-commutated direct(cid:173)
`current'' or "EC" motor is becoming in(cid:173)
`creasingly popular. It is essentially a per(cid:173)
`manently-excited synchronous machine,
`and thus dispenses with a slip ring. The
`EC motor is equipped with a rotor-position
`sensor, and is connected to the DC power
`source through its control and power
`electronics. The electronic transfer circuit
`switches the current in the stator winding
`according to rotor position - the magnets
`which induce the excitation current are
`attached to the rotor - to provide the inter(cid:173)
`dependence between rotational speed
`and torque which is normally associated
`with an externally-excited DC unit. The
`respective magnetic functions of
`the
`stator and rotor are the opposite of what
`
`Star-connected three-phase synchronous
`generator
`Slip-ring rotor with field winding.
`
`EC Motor
`1 Electric machine with rotor-position sensor,
`2 Control and power electronics, 3 Input.
`
`2
`
`3
`
`OJ
`
`1
`
`N
`
`they would be in a classical direct-current
`machine.
`The EC motor's potential applications
`are a result of the advantages which this
`drive principle provides: Commutator and
`carbon brushes are replaced by elec(cid:173)
`tronic circuitry, dispensing with both brush
`noise and wear. EC motors are mainten(cid:173)
`ance-free (long service life) and can be
`constructed to meet high degrees of pro(cid:173)
`tection (s. below). The electronic control
`feature makes it easy for drive units with
`EC motors to incorporate auxiliary func(cid:173)
`tions such as infinitely-variable speed
`adjustment, direction reversal, gradual
`starts and lock-up protection.
`The main areas of automotive applica(cid:173)
`tion are for climate control and ventilation,
`pumps and servo units. In the area of pro(cid:173)
`duction machinery, EC motors are chiefly
`employed as precision drive units for
`feed-control in machine tools. Here the
`decisive advantages are freedom from
`maintenance,
`favorable dynamic pro(cid:173)
`perties and consistent torque output with
`minimal ripple.
`
`BMW1042
`Page 12 of 23
`
`

`

`Electric machines 133
`
`Single-phase alternating(cid:173)
`current machines
`
`Two-value capacitor motor
`
`Universal motors
`The direct-current series-wound motor
`can be operated on alternating current if a
`laminated rather than a solid iron stator is
`used. It is then called a universal motor.
`When operated on alternating current,
`a torque component at twice the fre(cid:173)
`quency of the current is superposed on
`the constant torque component.
`
`Single-phase asynchronous motors
`with squirrel-cage rotor
`The simplest design of a single-phase
`asynchronous motor is a three-phase
`asynchronous machine in which alterna(cid:173)
`ting current is supplied to only two stator
`phases. Although its operation remains
`largely the same, the power and the
`maximum torque are reduced. In addition,
`the single-phase asynchronous machine
`is not self-starting.
`Machines which are Intended only for
`single-phase operation have only a single
`phase main winding in the stator, as well
`as auxiliary starting circuits. The stator
`also contains an auxiliary winding con(cid:173)
`nected in parallel with the main winding
`for this purpose. The necessary phase
`shift of the auxiliary winding current can
`be achieved through increased winding
`resistance (low breakaway torque) or by
`means of a capacitor connected
`in
`series with the auxiliary winding (some(cid:173)
`what greater starting torque).
`The auxiliary winding is switched off
`after the motet starts. The direction of
`rotation of the motor is changed by rever(cid:173)
`sing the two auxiliary or main winding
`connections. A motor which has a capa(cid:173)
`citor in series with the auxiliary winding
`is called a capacitor motor. Capacitor
`motors with a starting and running capa(cid:173)
`citor also operate continuously with capa(cid:173)
`citor and auxiliary winding. Optimum ope(cid:173)
`ration is achieved by correctly choosing
`the capacitor for a specific working point.
`An additional capacitor is often used in
`order to increase the starting torque; this
`capacitor is then disconnected after the
`motor starts.
`
`-,--
`
`®
`
`Duty-type ratings for electric
`machines
`(VDE 0530)
`
`S 1: Continuous-running duty
`Operation under constant load (rated out(cid:173)
`put) of sufficient duration for thermal equi(cid:173)
`librium to be reached.
`
`S 2: Short-time duty
`Operation under constant load is so brief
`that thermal equilibrium is not reached.
`The rest period is so long that the
`machine is able to cool down to the tem(cid:173)
`perature of the coolant.
`Recommended short-time duty periods:
`10, 30, 60 and 90 min.
`
`S 3 to S 5: Intermittent duty
`Continuous alternating sequence of load
`and idle periods. Thermal equilibrium is
`not reached during the load period or du(cid:173)
`ring the cooling period of one duty cycle.
`S 3 Intermittent duty without influence
`of starting on temperature.
`S4 Intermittent duty with influence of
`starting on temperature.
`S5 Intermittent duty with influence of
`starting and braking on temperature.
`·
`
`S 6: Continuous operation with inter(cid:173)
`mittent loading
`Operation with intermittent loading. Conti(cid:173)
`nuous alternating sequence of load peri(cid:173)
`ods and no-load periods, otherwise as
`S3.
`
`S 7: Uninterrupted duty
`Operation with starting and braking.
`
`1 I ii
`I 'l
`
`,)
`
`in
`,:1
`'' :'j
`'' i'l " !
`
`. · I
`,l
`
`.
`
`BMW1042
`Page 13 of 23
`
`

`

`134 Electric machines
`
`S 8: Uninterrupted duty
`Operatio