Automotive Systems course (Module 08) - Starting Systems for road vehicles

29 de novembro de 2016 | 1
SistemasAutomóveis
Starting Systems
Mário Alves (mjf@isep.ipp.pt)

SistemasAutomóveis
Outline
• Starting system: definition, components, requirements
• Starter motor: definition and classification
• Starter motor: excitation and electrical connections
• Starter motor types
• direct drive, axial (with lever)
• gear reduction, co-axial (without lever)
• gear reduction, co-axial (with lever)
• gear reduction (epicyclical, axial, with lever)
• permanent magnets, planetary gear reduction
• Direct drive vs. gear reduction
• Stator, rotor, brushes, overrunning clutch
• Heavy vehicles starter motors
• Start-stop systems
• Belt/Flywheel Alternator Starter
• Glossary
• Recommended references

SistemasAutomóveis
Starting System: definition and main components
• Starting system
• enables to crank the internal combustion engine
• Main (typical) components
• (battery, ignition key, flywheel)
• starter (aka cranking) motor
• starter solenoid
• electric motor
• overrunning clutch (aka bendix)
• pinion (small gear wheel)
• electric cabling
• command circuit (controls starter relay/solenoid)
• power circuit (feeds electric motor)
http://www.procarcare.com/images/shar/encyclopedia/8852BG58.gif

SistemasAutomóveis
Starting System: main components
http://www.pearltrees.com/kitching/item125272003
• It may also include
• starter fuse
• protects against over-currents
in the control circuit (thin red wire)
• power circuit (thick red wire)
is unfused
• starter relay
• to connect to the starter solenoid
• reduces control current at the
IG switch
• neutral or clutch safety switch
• automatic transmission
• signals Neutral or Park position
• manual transmission
• signals Clutch actuation

SistemasAutomóveis
Starting System: starter motor outlook
http://www.pearltrees.com/kitching/item125272003

SistemasAutomóveis
Starting System: requirements
• Main requirements
• support high currents
• battery, wiring, connectors, relays, switches, brushes, commutator,
stator/rotor windings
• starting current draw of typically 100-200 A (few seconds)
• peak (transient) currents of typically >500 A (few hundred ms)
• note: control circuit (solenoid) current of typically several A
• adequate power/torque, to support
• engine + other loads (water and oil pumps, A/C, alternator)
• friction, ICE compression, oil viscosity, inertia
• high durability/reliability
• user-perspective: no need to replace the starter motor for the
vehicle’s lifetime
• typically 15-20 years & 150-300 thousand km lifetime
• start-stop systems impose much higher standards
• compact size, light-weight, silent, low-cost
…

SistemasAutomóveis
• Starting current waveform
• Toyota 1600 CC 4A-FE gasoline engine
• Peak current  500 A | Steady state current (2) = 116 A
Waveform obtained using Fluke123 Scopemeter + active current probe + FlukeView @ ISEP Automotive Lab

SistemasAutomóveis
• Starting current waveform
• Toyota 2000 CC 2C Diesel engine
• Peak current (1) = 848 A | Final current (2) = 112 A
Waveform obtained using Fluke123 Scopemeter + active current probe + FlukeView @ ISEP Automotive Lab

SistemasAutomóveis
Starter motor: definition and classification
• Definition
• a starter (AKA starter motor) is a motor used for rotating an ICE so
as to initiate its operation under its own power
• The starter can be
• an electric motor
• a pneumatic motor
• a hydraulic motor
• an ICE (in case of very large engines)
• Most road vehicles feature electric motor starters
• thus, we will address this type of starter
…https://en.wikipedia.org/wiki/Starter_(engine)

SistemasAutomóveis
Starter motor: classification
• Electric starter motors can be classified according to, e.g.:
• excitation (stator) and electrical connections (stator-rotor)
• permanent-magnets
• electromagnets
• shunt-wound | series-wound | compound-wound
• gear ratio
• direct drive (1:1 gear ratio)
• gear reduction (N:1 gear ratio, N > 1)
• parallel gear train | planetary (epicyclical) gear train
• mechanical layout
• axial (pinion gear aligned with motor shaft)
• co-axial (pinion gear aligned with starter solenoid)
• mechanical drive (of the flywheel)
• pre-engaged (pinion gear engages flywheel gear before spinning)
• inertia-drive (pinion gear spins before engaging flywheel gear)
…

SistemasAutomóveis
Starter motor: excitation and electrical connections
A. Shunt-wound
B. Series-wound
C. Compound-wound
D. Permanent-magnet
http://what-when-how.com/automobile/starter-motors-and-circuits-automobile/

SistemasAutomóveis
http://www.sw-em.com/starter.htm
Series-wound motor Permanent-magnet motor

SistemasAutomóveis
…http://www.sw-em.com/starter.htm
• Electrical wiring schematics (series-wound)
• Control circuit (solenoid) and power circuit (stator + rotor)

SistemasAutomóveis
…http://what-when-how.com/automobile/starter-motors-and-circuits-automobile/
• Electrical circuits
A. inertia-drive starter
B. pre-engaged starter

SistemasAutomóveis
Starter motor: direct drive (1:1), axial (with lever)
http://www.rollaclub.com/wiki/index.php?title=Tech:Electrical/Starter_Motor/Conventional_Type&redirect=no

SistemasAutomóveis
1. IG ON  STA
pinion engages ring

SistemasAutomóveis
2. Pinion & Ring
fully engaged
motor rotates &
cranks ICE

SistemasAutomóveis
3. IG STAON
pinion disengages
from ring

SistemasAutomóveis
Starter motor: gear reduction, co-axial
http://www.rollaclub.com/wiki/index.php?title=Tech:Electrical/Starter_Motor/Reduction_Type

SistemasAutomóveis
• IG  STA

SistemasAutomóveis
• Pinion engaged

SistemasAutomóveis
• IG STA ON

SistemasAutomóveis
Starter motor: gear reduction, co-axial (with lever)
http://autosystempro.com/cranking-motor-designs/

SistemasAutomóveis
Starter motor: gear reduction (epicyclical, axial, with lever)
http://www.rollaclub.com/wiki/index.php?title=Tech:Electrical/Starter_Motor/Planetary_Type

SistemasAutomóveis
Starter motor: permanent magnets, planetary gear reduction
http://www.import-car.com/diagnostic-solutions-starter-battery-diagnostics/
http://what-when-how.com/automobile/permanent-magnet-starter-motor-automobile/

SistemasAutomóveis
Starter motor: direct drive vs. gear reduction
http://www.elreg.com/blog/why-are-gear-reduction-starters-replacing-direct-drive-starters
• Electrical power/current draw
• direct drive starters require more electrical power/current
• impacts battery, cables and other components
• Weight
• gear reduction starters are smaller and lighter
• Maintenance
• gear reduction starters have a higher part count
• Cost
• direct drive starters are slightly cheaper
• Speed
• typically, gear reduction starters turn the flywheel slower
• however, their torque is higher, so perform better when pistons are at
TDC on the compression stroke where it is most needed; this is why
they are ideal for diesel/high-compression ICEs

SistemasAutomóveis
Starter motor: stator and rotor interleave
http://autosystempro.com/tag/starting-system/
• Electric current in the rotor windings must flow in a
direction such that additive torque is obtained
…

SistemasAutomóveis
Starter motor: rotor
• Laminated core
http://www.groschopp.com/how-to-check-a-motor-armature/

SistemasAutomóveis
Starter motor: rotor
…
Lap winding Wave-wound winding

SistemasAutomóveis
Starter motor: stator
Permanent-magnet
stator
Electromagnets stator

SistemasAutomóveis
Starter motor: brushes
http://www.howacarworks.com/ignition-system/checking-and-replacing-starter-motor-brushes
• Usually 2 or 4 brushes

SistemasAutomóveis
Starter motor: overrunning clutch
http://autosystempro.com/starter-drives/
• Motivation
• ratio of the number of teeth on the flywheel ring gear and
the starter pinion gear is usually between 15:1 and 20:1
• starter motor rotates 15 to 20 times faster than ICE
• normal ICE cranking speed is about 100-200 RPM
• for a gear ratio of 20:1, the starter motor rotates at
2000-4000 RPM
• if the ICE started and was accelerated to 2000 RPM, the
starter would speed up to 40000 RPM!
• this would destroy the starter motor
if it was not disengaged from the ICE
…

SistemasAutomóveis
http://autosystempro.com/starter-drives/
• It is a roller-type clutch that transmits torque in one direction
only and freewheels in the other direction
• it allows the starter motor to transmit torque to the ring gear but
prevents the ring gear from transferring torque to the starter motor.
…

SistemasAutomóveis
http://www.tractordata.com/articles/technical/overrunning-pto-clutch.html
• Dynamics
• Note: starter pinion keeps rotating with the flywheel, after cranking
…
During cranking:
pinion drives flywheel
After cranking:
flywheel does NOT drive pinion

SistemasAutomóveis
Heavy Vehicles Starter Motors
http://what-when-how.com/automobile/inertia-drive-starter-motor-automobile/
• Large ICEs require more cranking power/torque
• trucks, tanks, big stationary diesel engines
• Increased cranking power/torque can be achieved through
• gear reduction (also common in light vehicles)
• higher voltage (24 V, 42 V)
• inertia-drive
• sliding armature

SistemasAutomóveis
Heavy Vehicles Starter Motors: inertia-drive
http://what-when-how.com/automobile/inertia-drive-starter-motor-automobile/
• Operating principle
• pinion is not fixed rigidly to the motor shaft - it is threaded on to it
• when the shaft starts spinning, the inertia of the pinion causes it to lag
behind and thus move along the shaft into engagement with the ring-
gear on the fly-wheel
• once the engine starts, it spins the pinion faster than the starter motor
shaft, screwing the pinion back down its thread and disengaging it
Ring gear
(flywheel)
Cushion
spring
Helical splines
(quick thread
Cushion
spring

SistemasAutomóveis
http://www.uniquecarsandparts.com.au/auto_technical_terms_9.php
• Detailed view
• pinion, sleeve and thread
http://www.jcrsupplies.co.uk/products/STARTER_MOTOR_REPAIR_PARTS/STARTER_MOTOR_DRIVES__PINIONS_AND_GEARS/M35J_and_M35G_INERTIA_STARTER_MOTOR_PINION_DRIVE_10_TEETH_.html

SistemasAutomóveis
https://en.wikipedia.org/wiki/Starter_(engine)#Inertia_starter
• Advantage
• since an inertia-drive starter is not driving the engine directly, it can
be of lower power than a “standard” pre-engaged starter
• this allows a lower weight and smaller size starter, as well as
lighter electrical cables and smaller batteries to power it
• thus, it most adequate for large ICEs
• e.g. aircrafts with large radial piston engines

SistemasAutomóveis
https://en.wikipedia.org/wiki/Starter_(engine)#Inertia_starter
• Disadvantages
• increased cranking time – can take a few seconds
• upon ICE cranking, the pinion returns back so violently that there has
to be a strong spring on the shaft to cushion its impact
• the violent engagement and disengagement of an inertia starter can
cause heavy wear on the gear teeth;
• to overcome these problems, the pre-engaged starter was
introduced (in the 80s)
• a starter solenoid is used
• pinion gear engages flywheel gear before starting to spin
http://www.howacarworks.com/basics/how-the-starting-system-works

SistemasAutomóveis
Heavy Vehicles Starter Motors: sliding-armature
http://what-when-how.com/automobile/heavy-vehicle-starter-motors-automobile/
• Operating principle
• Starter motor armature (rotor) progressively slides along the axis
• several armature windings (gradually feed)
• full torque is achieved when all armature windings are energized,
• but this happens only when the pinion gear is fully engaged with
flywheel gear
• This enables
• smoother pinion-flywheel engagement 
• less cranking noise
• less gear deterioration
• lower peak currents at start 
• thinner electrical wires
• smaller battery
…

SistemasAutomóveis
• Operation
• the motor is shown in the rest position
• when the field windings (stator) are energized
• the armature is pulled to the left and
• the pinion gear engages with the
ring gear (flywheel)
PINION

SistemasAutomóveis
• Three separate field (stator) windings
• main winding
• thick-section (low-resistance) winding
• connected in series to the armature
• auxiliary winding
• thinner wire (high resistance
• connected in series with the armature
and in parallel with the main winding
• holding winding
• high-resistance winding
• connected in parallel with the armature
as well as with the other two windings

SistemasAutomóveis
• A two-stage solenoid switch, mounted on the starter operates the
starter, and is energized by the IG switch
• when the ignition switch is operated, the first pair of contacts closes
but the second pair is held open by a pawl that engages in a slot in the
trip lever – Figure A
• Once the pinion is near fully engaged with the ring gear, the pawl
allows the second pair of contacts to close – Figure B
PINION

SistemasAutomóveis
• A: auxiliary windings, holding windings and armature are energized;
armature rotates slowly and moves axially towards the field poles;
simultaneously, the pinion slowly engages with the ring gear
• B: upon full engagement, the release disc on the armature strikes the
pawl and the trip lever closes the second pair of contacts; now current
feeds the main windings, causing the motor to develop its full torque

SistemasAutomóveis
Start-stop systems
• Motivation
• estimated fuel consumption of an idling engine is 0.6 l/hour per
liter of engine displacement
• an idling 2.0 liter engine consumes more than 1 liter of fuel
per hour
• engine idle for 30 minutes a day results in one fuel tank
every four months, without moving!
• engine idle for more than a few seconds consumes more fuel and
generates more greenhouse gas emissions than turning it off and
starting it up again
• thus, ICE should be turned off (automatically) at idle
• as far as both ICE and catalyst have achieved normal
operating temperatures (warmup phase finished)
http://www.ecomobile.gouv.qc.ca/en/ecomobilite/tips/idling_engine.php
http://www.roadandtrack.com/new-cars/car-technology/news/a18043/startstop-making-the-most-of-just-hanging-around/

SistemasAutomóveis
Start-stop systems
• Motivation
• fuel savings and emission reductions of 8-15 % (measurements
based in the New European Driving Cycle (NEDC))
• In combination with a modern gasoline engine, the amount of
fuel required for warm starting is only the same as that used
when idling for 0.7 seconds.
• stop function has a beneficial effect from the very first
second (for both people and environment).
http://de.bosch-
automotive.com/en/parts_and_accessories/motor_and_sytems/start_stop_system/functionality_start_stop_system/functionality_start_stop_system

SistemasAutomóveis
Start-stop systems
• Configurations
• for “conventional” ICE powertrains
• “conventional” battery, starter and alternator
• Belt Alternator Starter (BAS) aka Integrated Starter
Generator (ISG)
• for hybrid electric-ICE powertrains
• hybrid powertrain cranks the ICE
• In this module, we will address start-stop systems for
conventional ICEs
• (hybrid powertrains will be treated separately)
http://de.bosch-
automotive.com/en/parts_and_accessories/motor_and_sytems/start_stop_system/functionality_start_stop_system/functionality_start_stop_system

SistemasAutomóveis
Start-stop systems: market trend
http://www.altenergystocks.com/archives/energy_storage/batteries/

SistemasAutomóveis
http://www.altenergystocks.com/archives/energy_storage/batteries/

SistemasAutomóveis
http://www.marketsandmarkets.com/Market-Reports/variable-valve-timing-vvt-market-1206.html

SistemasAutomóveis
Belt/Flywheel Alternator-Starter (BAS and FAS)
• Both BAS and FAS systems
• substitute conventional starters/alternators
• starter (motor) mode: BAS/FAS drives crankshaft
• generator (alternator) mode: crankshaft drives BAS/FAS
• enable “mild-hybrid” (AKA “micro-hybrid”) operation
• mild levels of regenerative braking, start-stop, power assist
• trend for higher voltage systems/batteries (> 36 V)
• Belt Alternator-Starter (BAS)
• belt connects BAS and ICE crankshaft pulley
• Flywheel Alternator-Starter (FAS)
• mounted directly to the engine crankshaft
(replaces existing flywheel)
http://wikicars.org/en/Belt_Alternator_Starter_(BAS)

SistemasAutomóveis
• Typical block diagram
http://www.eetimes.com/document.asp?doc_id=1272189

SistemasAutomóveis
• Power MOSFET control diagram
• brushless DC motors tend to be preferred over induction motors on
account of their efficiency and controllability
http://www.eetimes.com/document.asp?doc_id=1272189

SistemasAutomóveis
Belt Alternator-Starter (BAS)
• GM BAS “mild-hybrid”
• 115V lithium-ion battery
• 15 kW alternator
• regenerative braking
(helped by alternator torque load)
• up to 11 kW (15 hp) of electric power
assistance during acceleration
• automatic ICE start-stop
http://gmauthority.com/blog/gm/gm-engines/luk/
http://www.gminsidenews.com/forums/f12/next-generation-gm-hybrid-system-announced-geneva-61607/index6.html

SistemasAutomóveis
Flywheel Alternator-Starter (FAS)
• Volvo Crankshaft-Integrated Starter Generator
(C-ISG)
• pioneered by Volvo in 2001
• 42V system intended for a “mild hybrid”
application
• current C-ISG
• XC90 T8 PHEV model
• 400 hp Direct-Injection
Turbo&Supercharged
• 2.0 liters, 4 cylinders, in-line configuration
• 65 kW (87 hp) electric rear axle drive
(ERAD)
• C-ISG
• 9.2 kWh lithium-ion battery
• 34 kW (46 hp) generator/motor
(150 N.m torque)
• water-cooled
• 3 functions:
• starter, generator
• power boost
• torque infill between gear shifts
(smooth drive feeling)
• extra boost (start-up and
hard acceleration
http://insideevs.com/volvo-xc90-t8-phev-first-drive-recap/
https://www.media.volvocars.com/global/en-gb/media/pressreleases/5278

SistemasAutomóveis
Flywheel Alternator-Starter (FAS)
• Honda ACG
• brushless DC motor/generator
• Starter: current applied to the stator coils
• Alternator: rotor magnets produce EMF
http://world.honda.com/motorcycle-technology/Engineidlingstop/p3.html
Starter operation
Alternator operation
http://www.hondacengkareng.com/teknologi-acg-starter-motor-honda/

SistemasAutomóveis
Glossary (English/Portuguese)
• …

SistemasAutomóveis
Recommended references
• http://www.autoshop101.com/forms/elec04.pdf
• https://www.youtube.com/watch?v=ITFW2PkqXWw
• http://www.roadandtrack.com/new-cars/car-technology/news/a18043/startstop-making-
the-most-of-just-hanging-around/

Automotive Systems course (Module 08) - Starting Systems for road vehicles

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