Download how the starter motor works

OBJECTIVES
After studying Chapter 18, the reader should be able to:
1. Prepare for ASE Electrical/Electronic Systems (A6)
certification test content area “C” (Starting System
Diagnosis and Repair).
2. Describe how the cranking circuit works.
3. Discuss how a starter motor converts electrical
power into mechanical power.
4. Describe the hold-in and pull-in windings of a
starter solenoid.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CRANKING CIRCUIT
• For any engine to start, it must first be
rotated, using an external power source.
• It is the purpose and function of the cranking
circuit to create the necessary power and
transfer it from the battery to the starter motor
that rotates the engine.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CRANKING CIRCUIT
•
Modern cranking circuits include the following:
1. Starter motor. The starter is normally a 0.5 to 2.6 horsepower
(0.4 to 2.0 kilowatts) electric motor that can develop nearly 8
horsepower (6 kilowatts) for a very short time when first cranking
a cold engine.
FIGURE 18-1 A typical solenoid-operated starter.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CRANKING CIRCUIT
2. Battery. The battery must be of the correct capacity and
be at least 75% charged to provide the necessary
current and voltage for correct starter operation.
3. Starter solenoid or relay. The high current required by
the starter must be able to be turned on and off. A large
switch would be required if the current were controlled
by the driver directly. Instead, a small current switch
(ignition switch) operates a solenoid or relay that
controls the high starter current.
4. Starter drive. The starter drive uses a small pinion gear
that contacts the engine flywheel gear and transmits
starter motor power to rotate the engine.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CRANKING CIRCUIT
5. Ignition switch. The
ignition switch and
safety control switches
control the starter
motor operation.
FIGURE 18-2 Some column-mounted
ignition switches act directly on the contact
points, whereas others use a link from the
lock cylinder to the ignition switch.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CRANKING CIRCUIT
Control Circuit
• Many automobile
manufacturers use an
electric switch called a
neutral safety switch that
opens the circuit between
the ignition switch and the
starter to prevent starter
motor operation unless the
gear selector is in neutral or
park.
Automotive Electricity and Electronics, 2/e
By James D Halderman
FIGURE 18-3 A typical wiring diagram of a
starter circuit.
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
COMPUTER-CONTROLLED STARTING
• The ignition switch start position on the push-to-start
button is used as an input signal to the powertrain
control module (PCM).
• Before the PCM cranks the engine, the following
conditions must be met.
– The brake pedal is depressed.
– The gear selector is in park or neutral.
– The correct key fob (code) is present in the vehicle.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
COMPUTER-CONTROLLED STARTING
• Computer-controlled
starting is almost always
part of the system if a push
button start is used.
FIGURE 18-4 Instead of an ignition key to
start the engine, some vehicles are using a
start button which is also used to stop the
engine, as shown on this Jaguar.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
COMPUTER-CONTROLLED STARTING
• This feature allows the
heater or air conditioning
system to start before the
driver arrives.
FIGURE 18-5 The top button on this key
fob is the remote start button.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
HOW THE STARTER MOTOR WORKS
• A starter consists of the main structural
support of a starter called the main field
housing, one end of which is called a
commutator-end (or brush-end) housing
and the other end a drive-end housing.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
HOW THE STARTER MOTOR WORKS
• The commutator-end
plate supports the end
containing the starter
brushes.
• Through bolts hold the
three components
together.
FIGURE 18-6 A typical starter motor.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
HOW THE STARTER MOTOR WORKS
• The starter uses four
brushes—two brushes
to transfer the current
from the field coils to
the armature, and two
brushes to provide the
ground return path for
the current that flows
through the armature.
Automotive Electricity and Electronics, 2/e
By James D Halderman
FIGURE 18-7 This series-wound electric motor
shows the basic operation with only two
brushes: one hot brush and one ground brush.
The current flows through both field coils, then
through the hot brush and through the loop
winding of the armature before reaching ground
through the ground brush.
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
HOW MAGNETIC FIELDS TURN AN ARMATURE
• One basic principle of electromagnetism is
that a magnetic field surrounds every
conductor carrying a current.
• Inside the starter housing is a strong
magnetic field created by the field coil
magnets.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
HOW THE STARTER MOTOR WORKS
• Inside the starter housing is a strong magnetic
field created by the field coil magnets.
FIGURE 18-8 The interaction of
the magnetic fields of the
armature loops and field coils
creates a stronger magnetic field
on the right side of the conductor,
causing the armature loop to move
toward the left.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
HOW THE STARTER MOTOR WORKS
FIGURE 18-9 The armature loops rotate due to the difference in the
strength of the magnetic field. The loops move from a strong magnetic field
strength toward a weaker magnetic field strength.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
HOW THE STARTER MOTOR WORKS
• The magnetic field of
the starter motor is
provided by two or
more pole shoes and
field windings.
• The pole shoes are
made of iron and are
attached to the frame
with large screws.
Automotive Electricity and Electronics, 2/e
By James D Halderman
FIGURE 18-10 Pole shoes and field windings
installed in the housing.
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
HOW THE STARTER MOTOR WORKS
• Paths of magnetic flux
lines within a four-pole
motor.
FIGURE 18-11 Magnetic lines of force in
a four-pole motor.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
HOW THE STARTER MOTOR WORKS
• The field windings are
usually made of a
heavy copper ribbon to
increase their currentcarrying capacity and
electromagnetic field
strength.
FIGURE 18-12 A pole shoe and field winding.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
TYPES OF STARTER MOTORS
• Starter motors must provide high power at low starter motor
speeds to crank an automotive engine at all temperatures
and at the cranking speed required for the engine to start
(60 to 250 engine RPM).
• Many starter motors are series wound, which means that
the current flows first through the field coils, then in series
through the armature, and finally to a ground through the
ground brushes.
FIGURE 18-13 This wiring diagram illustrates the construction of a
series-wound electric motor. Notice that all current flows through the field coils,
then through the armature (in series) before reaching ground.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
TYPES OF STARTER MOTORS
Series Motors
• A series motor develops its maximum torque
at the initial start (0 RPM) and develops less
torque as the speed increases.
• Because the power (torque) of the starter
depends on the strength of the magnetic
fields, the torque of the starter decreases as
the starter speed increases.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
TYPES OF STARTER MOTORS
Shunt Motors
• Shunt-type electric motors have the field coils in
parallel (or shunt) across the armature.
FIGURE 18-14 This wiring diagram illustrates the construction of a shunt-type
electric motor. Shunt-type electric motors have the field coils in parallel
(or shunt) across the armature as shown.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
TYPES OF STARTER MOTORS
Compound Motors
• A compound-wound, or compound, motor has the
operating characteristics of a series motor and a shunttype motor, because some of the field coils are
connected to the armature in series and some (usually
only one) are connected directly to the battery in parallel
(shunt) with the armature.
FIGURE 18-15 A compound motor is a combination of series and shunt
types, using part of the field coils connected electrically in series with the
armature and some in parallel (shunt).
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
ARMATURE AND COMMUTATOR ASSEMBLY
• The motor armature has a laminated core.
FIGURE 18-16 A typical starter motor armature.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
ARMATURE AND COMMUTATOR ASSEMBLY
• Motor armatures are
connected to the
commutator in one of two
ways.
• In a lap winding, the two
ends of each conductor are
attached to two adjacent
commutator bars.
FIGURE 18-17 An armature lap winding.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
ARMATURE AND COMMUTATOR ASSEMBLY
• The armature core,
windings, and
commutator are
assembled on a long
armature shaft.
• This shaft also carries
the pinion gear that
meshes with the engine
flywheel ring gear.
FIGURE 18-18 The pinion gear meshes with
the flywheel ring gear.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
ARMATURE AND COMMUTATOR ASSEMBLY
• Most automotive starters have two grounded and two
insulated brushes, which are held against the commutator
by spring force.
FIGURE 18-19 A cutaway of a typical starter motor.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
PERMANENT-MAGNET FIELDS
• The permanent-magnet, planetary-drive starter
motor is the first significant advance in starter
design in decades.
• This eliminates the motor field circuit, which in turn
eliminates the potential for field wire-to-frame
shorts, field coil welding, and other electrical
problems.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DON’T HIT THAT STARTER!
• If struck with a heavy tool,
the magnets could be
broken with parts of the
magnet falling onto the
armature and into the
bearing pockets, making
the starter impossible to
repair or rebuild.
FIGURE 18-20 This starter permanentmagnet field housing was ruined when
someone used a hammer on the field
housing in an attempt to “fix” a starter that
would not work. A total replacement is the
only solution in this case.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
GEAR-REDUCTION STARTERS
• The purpose of the gear reduction (typically 2:1
to 4:1) is to increase starter motor speed and
provide the torque multiplication necessary to
crank an engine.
FIGURE 18-21 Chrysler was one of the first
vehicle manufacturers to
use a gear-reduction starter.
Automotive Electricity and Electronics, 2/e
By James D Halderman
FIGURE 18-22 Many gear-reduction
starters use a planetary gear reduction
assembly similar to that used in an
automatic transmission.
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
STARTER DRIVES
• A starter drive includes a
small pinion gear that
meshes with and rotates
the larger gear on the
engine for starting.
• The ends of the starter
pinion gear are tapered to
help the teeth mesh more
easily without damaging the
flywheel ring gear teeth.
Automotive Electricity and Electronics, 2/e
By James D Halderman
FIGURE 18-23 A cutaway of a typical
starter drive.
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
STARTER DRIVES
• If the engine starts and is
accelerated to 2000 RPM
(normal cold engine
speed), the starter will be
destroyed by the high
speed (36,000 RPM) if the
starter was not disengaged
from the engine.
FIGURE 18-24 The ring gear to pinion gear
ratio is usually 15:1 to 20:1.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
A BIT OF HISTORY
A Bendix Drive Is Now Called a Starter Drive
• Older-model starters often
used a Bendix drive
mechanism, which used
inertia to engage the starter
pinion with the engine
flywheel gear.
• The overrunning clutch,
which is built in as a part of
the starter drive unit, uses
steel balls or rollers
installed in tapered
notches.
Automotive Electricity and Electronics, 2/e
By James D Halderman
FIGURE 18-25 Operation of the overrunning
clutch. (A) Starter motor is driving the starter
pinion and cranking the engine. The rollers
are wedged against spring force into their
slots. (B) The engine has started and is
rotating faster than the starter armature.
Spring force pushes the rollers so they
can rotate freely.
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
A BIT OF HISTORY
A Bendix Drive Is Now Called a Starter Drive
• The spring between the
drive tang or pulley and the
overrunning clutch and
pinion is called a mesh
spring and it helps to
cushion and control the
engagement of the starter
drive pinion with the engine
flywheel gear.
Automotive Electricity and Electronics, 2/e
By James D Halderman
FIGURE 18-26 Cutaway of a solenoidactivated starter showing the solenoid, shift
lever, and starter drive assembly that
includes the starter pinion and overrunning
clutch with a mesh spring in one unit.
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
STARTER DRIVE OPERATION
• A starter drive is generally a dependable unit and
does not require replacement unless defective or
worn.
• Intermittent starter drive failure (starter whine) is
often most noticeable during cold weather.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
POSITIVE-ENGAGEMENT STARTERS
• Positive-engagement
starters, used on many
older Ford engines, utilize
the shunt coil winding and a
movable pole shoe to
engage the starter drive.
FIGURE 18-27 A Ford movable-poleshoe starter.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
POSITIVE-ENGAGEMENT STARTERS
• The movable pole shoe is
held down (which keeps the
starter drive engaged) by a
smaller coil on the inside of
the main drive coil.
FIGURE 18-28 A circuit diagram of a Ford
system using a movable-pole-shoe starter.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
SOLENOID-OPERATED STARTERS
• A starter solenoid is an electromagnetic switch containing
two separate, but connected, electromagnetic windings.
FIGURE 18-29 Wiring diagram of a
typical starter solenoid. Notice that
both the pull-in winding and the
hold-in winding are energized when
the ignition switch is first turned to
the “start” position. As soon as the
solenoid contact disk makes
electrical contact with both the B
and M terminals, the battery current
is conducted to the starter motor
and electrically neutralizes the pullin winding.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
HOW ARE STARTERS MADE SO SMALL?
• A starter can be
constructed smaller due to
the use of gear reduction to
achieve the same cranking
torque as a straight drive
starter, but using much
smaller components.
FIGURE 18-30 A palm-sized starter armature.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
SUMMARY
1. All starter motors use the principle of magnetic interaction
between the field coils attached to the housing and the
magnetic field of the armature.
2. The control circuit includes the ignition switch, neutral
safety (clutch) switch, and solenoid.
3. The power circuit includes the battery, battery cables,
solenoid, and starter motor.
4. The parts of a typical starter include the main field housing,
commutator-end (or brush-end) housing, drive-end
housing, brushes, armature, and starter drive.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
REVIEW QUESTIONS
1. Describe the difference between the control circuit
and the power (motor) circuit sections of a typical
cranking circuit.
2. List the parts of a typical starter.
3. Explain why a gear-reduction unit reduces the
amount of current required by the starter motor.
4. Describe the symptoms of a defective starter
drive.
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
1. Starter motors operate on the principle that
_____.
a) The field coils rotate in the opposite direction
from the armature
b) Opposite magnetic poles repel
c) Like magnetic poles repel
d) The armature rotates from a strong magnetic
field toward a weaker magnetic field
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
2. Series-wound electric motors _____.
a)
b)
c)
d)
Produce electrical power
Produce maximum power at 0 RPM
Produce maximum power at high RPM
Use a shunt coil
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
3. Technician A says that a defective solenoid
can cause a starter whine. Technician B
says that a defective starter drive can cause
a starter whining noise. Which technician is
correct?
a)
b)
c)
d)
Technician A only
Technician B only
Both Technicians A and B
Neither Technician A nor B
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
4. The neutral safety switch is located _____.
a) Between the starter solenoid and the starter
motor
b) Inside the ignition switch itself
c) Between the ignition switch and the starter
solenoid
d) In the battery cable between the battery and the
starter solenoid
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
5. The brushes are used to transfer electrical
power between _____.
a)
b)
c)
d)
Field coils and the armature
The commutator segments
The solenoid and the field coils
The armature and the solenoid
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
6. The faster a starter motor rotates _____.
a)
b)
c)
d)
The more current it draws from the battery
The less CEMF is generated
The less current it draws from the battery
The greater the amount of torque produced
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
7. Normal cranking speed of the engine is
about _____.
a)
b)
c)
d)
2000 RPM
1500 RPM
1000 RPM
200 RPM
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
8. A starter motor rotates about _____ times
faster than the engine.
a)
b)
c)
d)
18
10
5
2
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
9. Permanent magnets are commonly used for
what part of the starter?
a)
b)
c)
d)
Armature
Solenoid
Field coils
Commutator
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
10. What unit contains a hold-in winding and a
pull-in winding?
a)
b)
c)
d)
Field coil
Starter solenoid
Armature
Ignition switch
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
END
Automotive Electricity and Electronics, 2/e
By James D Halderman
© 2009 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458