1. Starter Design and Operation
Unit 4
Starter Design and Operation

2. Introduction Almost every system relies on: Automobiles have:
12-volt storage battery
Electrical and electronic components
Engine starting system
Electrical charging system
Electronic control modules
Networking systems

3. Engine Starting (Cranking) Systems (1 of 7)
Starting system—method of rotating the internal combustion engine to start the cycle
Early vehicles—hand cranked
Modern vehicles—electric starter motor
Works for short periods of time
Cranks engine at sufficient speed to start it

4. Engine Starting (Cranking) Systems (2 of 7)
Consists of:
Battery
High- and low-amperage wires
Solenoid
Starter motor assembly ring gear
Ignition switch

5. Engine Starting (Cranking) Systems (3 of 7)
PCM-activated systems also have:
PCM
Relay
Related sensors
Control circuit that determines when/if cranking circuit functions

6. Engine Starting (Cranking) Systems (4 of 7)
Control circuit starts with:
Fuse
Ignition switch (or PCM circuitry)
Starter relay
Safety switch
Combination relay/starter solenoid

7. Engine Starting (Cranking) Systems (5 of 7)
Automatic transmissions—neutral safety switch or similar device
Manual transmissions—clutch safety switch
To determine starting system functions:
On-board computer (PCM)
Security system

8. Engine Starting (Cranking) Systems (6 of 7)
Two actions during cranking process
Starter motor pinion engages with flywheel ring gear.
Starter motor rotates to turn over (crank) the engine.

9. Engine Starting (Cranking) Systems (7 of 7)
Electric motor is mounted on engine block.
Typically powered by 12-volt storage battery
Some hybrids use high-voltage battery.
High turning effort at low speeds
Starter cables heaviest—carry high current
Engine flywheel, crankshaft rotate from resting

10. Engine Starting (Cranking) System—Starter Motor Principles (1 of 4)
Converts electrical energy to mechanical energy to crank engine
Three sections
Electric motor
Drive mechanism
Solenoid

11. Engine Starting (Cranking) System—Starter Motor Principles (2 of 4)
Mounted on transmission or cylinder block to engage a ring gear around the outside edge of:
Engine flywheel
Flex plate
Torque converter

12. Engine Starting (Cranking) System—Starter Motor Principles (3 of 4)
Operator activates switch in ignition lock assembly.
Small current flows through neutral safety or clutch switch to a starter relay.
Larger current operates the starter solenoid.
Solenoid plunger engages drive pinion gear into the ring gear.

13. Engine Starting (Cranking) System—Starter Motor Principles (4 of 4)
Large current from battery to starter motor
Rotates armature and drive pinion gear
Causes crankshaft to rotate
When engine starts:
Key is released.
Solenoid spring withdraws pinion gear from ring gear and armature halts.

14. Engine Starting Systems— Direct-Drive/Gear Reduction Styles (1 of 3)
On one end of armature shaft
Transfers rotating force directly to engine flywheel

15. Engine Starting Systems— Direct-Drive/Gear Reduction Styles (2 of 3)
Extra gear between armature and starter drive
4:1 reduction
Starter spins at higher speed with lower current.

16. Engine Starting Systems— Direct-Drive/Gear Reduction Styles (3 of 3)
Two types of gearing systems:
Spur gears—require armature to be offset via gear housing holding starter drive
Planetary gears—do not require offset housing; housed in drive-end housing in line with starter drive

17. Engine Starting Systems— Starter Motor Construction (1 of 4)
Components
Field coils or permanent magnets
Armature
Commutator
Brushes
Drive pinion with overrunning clutch

18. Engine Starting Systems— Starter Motor Construction (2 of 4)
Armature—revolving component of DC motor
Shaft supported at each end by brushes or bearings pressed into end frames
Centrally located in outer casings and between field coils or magnets

19. Engine Starting Systems— Starter Motor Construction (3 of 4)
Commutator end frame with copper-impregnated carbon brushes
Conduct current through armature
Brushes mounted in brush holders
Tension spiral springs keep brushes in contact.

20. Engine Starting Systems— Starter Motor Construction (4 of 4)
Half the brushes connect to end frame and ground armature windings to the negative battery terminal.
Other brushes are insulated from end frame and connect to positive battery terminal.

21. Engine Starting Systems— Starter Magnet Types (1 of 4)
Electromagnetic
Permanent magnets
Formed by current flow through heavy strop of copper windings
In similar location
Do not need electricity, so are smaller
Wind around iron pole shoes fastened to starter case

22. Engine Starting Systems— Starter Magnet Types (2 of 4)
Iron case concentrates magnetic field.
Starter motors with electronic magnetic field windings are series-wound motors.
High torque at low speeds
Torque drops when motor speed increases.

23. Engine Starting Systems— Starter Magnet Types (3 of 4)
CEMF—voltage generated in windings when armature spins in magnetic field
Increases with armature speed
Opposes current flow
Reduces both current flow and torque output
Faster the motor turns, less current drawn and less torque develops

24. Engine Starting Systems— Starter Magnet Types (4 of 4)
Series-parallel–wound starter motors have parallel-wired field windings.
Still wired in series with armature
More current flows in the circuit, with an overall increase in torque.

25. Engine Starting Systems— Starter Motor Engagement (1 of 6)
Engagement is provided:
From operation of ignition switch in start position
By PCM activating a starter-mounted solenoid
Moves operating fork, causing pinion to engage with ring gear and the plunger contacts to bridge with main starter terminals

26. Engine Starting Systems— Starter Motor Engagement (2 of 6)
Pinion drive mounted on a slight helix on the armature shaft
Pinion rotates when moved toward ring gear.
A chamfer on the leading edge of ring gear and pinion gear teeth
Assists in meshing teeth

27. Engine Starting Systems— Starter Motor Engagement (3 of 6)
Slight armature rotation from meshing spring pushes pinion teeth into mesh with ring gear.
Meshing spring forces pinion farther into ring gear until it contacts a stop ring.
Prevents further axial movement
Starter drive is locked to shaft via the helix.
One-way clutch drives the pinion gear.

28. Engine Starting Systems— Starter Motor Engagement (4 of 6)
Pinion has smaller number of teeth than ring gear (17:1).
Armature rotates 17 times for each rotation.
Multiplies torque from starter motor 17 times
If gear reduction starter is used, torque is multiplied further.

29. Engine Starting Systems— Starter Motor Engagement (5 of 6)
As soon as engine starts, may run 1000 rpm or more
Engine turns starter pinion gear 17 times faster (17,000 rpm).
Would destroy the armature
Overrunning clutch freewheeling prevents the armature from turning too fast.

30. Engine Starting Systems— Starter Motor Engagement (6 of 6)
Pinion remains meshed as long as engaging lever is held in the engaged position.
Releasing starter switch returns the following to original position:
Engaging lever
Starter drive
Pinion gear

31. Engine Starting Systems—Commutation and Brushes (1 of 8)
Electromagnetic field generated when current flows in a conductor
If placed so it cuts across a stationary magnetic field, conductor will be forced out of the stationary field.

32. Engine Starting Systems—Commutation and Brushes (2 of 8)
Stationary field lines distort electromagnetic field, return to straight-line condition.
Reversing direction of current flow causes conductor to move in the opposite direction.
Greatest when current-carrying conductor and stationary magnetic fields are at right angles

33. Engine Starting Systems—Commutation and Brushes (3 of 8)
Most efficient motor design—conductor loop that freely rotates within magnetic field
One side of loop up, other down

34. Engine Starting Systems—Commutation and Brushes (4 of 8)
Turning motion—motor effect
Causes loop to rotate to 90 degrees of magnetic field
Current flow direction must reverse at static neutral point to continue rotation.

35. Engine Starting Systems—Commutation and Brushes (5 of 8)
Commutator continuously reverses current flow to maintain rotation.
Carbon-filled brushes complete the circuit.

36. Engine Starting Systems—Commutation and Brushes (6 of 8)
Both sides of the conductor loop cut the stationary field to create rotation.
When loop passes where the field is no longer cut, rotation momentum carries the loop over.
Brushes maintain current flow in the same direction in each side.

37. Engine Starting Systems—Commutation and Brushes (7 of 8)
Process maintains consistent direction of loop rotation.
Number of loops must increase to achieve uniform motion and torque output.
Additional loops smooth out rotational forces.

38. Engine Starting Systems—Commutation and Brushes (8 of 8)
Starter motor armature—many conductor loops, many segments on the commutator

39. Engine Starting Systems—Solenoid Operation (1 of 16)
Two main functions:
Switches high current flow by starter motor on/off
Engages starter drive with the ring gear
Cylindrical device mounted on starter motor
Two electrical windings:
Pull-in winding
Hold-in winding

40. Engine Starting Systems—Solenoid Operation (2 of 16)
One end with a moving soft iron plunger is connected to a lever moving the starter drive.
Other end:
Has insulated cap with electrical connections to the windings
Has a set of high-current contacts and movable copper disc completing the cranking circuit when the plunger is drawn forward

41. Engine Starting Systems—Solenoid Operation (3 of 16)
Once cranking circuit is completed, current flows to the starter fields and armature.

42. Engine Starting Systems—Solenoid Operation (4 of 16)
Starter control circuit activates the solenoid winding to draw the plunger forward, activated by:
Ignition switch
PCM

43. Engine Starting Systems—Solenoid Operation (5 of 16)
When activated, supplies battery power to the two windings
Pull-in winding—draws higher current and creates stronger magnetic field than hold-in winding
Input of windings connects to the S-terminal.

44. Engine Starting Systems—Solenoid Operation (6 of 16)
Output of pull-in winding connects to main starter terminal:
Leads to field and armature windings
Provides ground to pull-in winding until solenoid contacts close

45. Engine Starting Systems—Solenoid Operation (7 of 16)
Current passes through both starter windings when the starter activates.
Magnetic fields attract the solenoid plunger toward the main starter terminals.

46. Engine Starting Systems—Solenoid Operation (8 of 16)
Plunger movement operates shift fork lever.
Drive pinion is engaged with the flywheel ring gear.
Plunger contacts a switching pin, closing the main solenoid terminals.
Allows large current to flow from battery through the starter motor windings

47. Engine Starting Systems—Solenoid Operation (9 of 16)
Closing contacts shorts-to-power the output wire of pull-in winding, resulting in:
Battery voltage applied to both the input and output of the winding
Stops current flow through pull-in winding
Stops magnetic field

48. Engine Starting Systems—Solenoid Operation (10 of 16)
Hold-in winding has power from the control circuit.
Holds plunger in place while starter cranks
Helix action on rotating armature shaft causes pinion gear to be held with flywheel ring gear.

49. Engine Starting Systems—Solenoid Operation (11 of 16)
Hold-in winding ensures moving contact continues to bridge main starter terminals.

50. Engine Starting Systems—Solenoid Operation (12 of 16)
Control circuit deactivates when engine starts.
Current stops flowing through control circuit to supply input.
Output of pull-in winding still activated through bridged solenoid contacts.

51. Engine Starting Systems—Solenoid Operation (13 of 16)
Current flows backward through pull-in winding, then forward through hold-in winding.

52. Engine Starting Systems—Solenoid Operation (14 of 16)
Two magnetic fields oppose each other:
Tend to cancel each other out
Plunger returns spring to retract the plunger.
Disconnects power from windings, starter motor
Engine stops cranking.
Pinion gear retracts to rest position.

53. Engine Starting Systems—Solenoid Operation (15 of 16)
Ford starter with moveable pole shoe
Separate starter relay in engine compartment instead of solenoid
Spring-loaded pole shoe on starter magnetically pulled into position during current

54. Engine Starting Systems—Solenoid Operation (16 of 16)
Ford starter (cont’d)
When pole shoe moves to position:
Shift fork engages starter drive with flywheel ring gear
No need for separate starter solenoid

55. Engine Starting Systems—Starter Control Circuit (1 of 3)
Operates starter motor within certain parameters:
Transmission in park
Clutch depressed
Brake pedal applied
Proper ignition switched used

56. Engine Starting Systems—Starter Control Circuit (2 of 3)
Switches traditionally have been placed in series with the starter solenoid windings.
Prevented starter from being activated unless each switch is closed
Automatic transmission—neutral safety switch incorporated into shift linkage
Standard transmission—clutch switch that closed when clutch pressed down

57. Engine Starting Systems—Starter Control Circuit (3 of 3)
Newer vehicles—computer monitors info so starter won’t activate until parameters met.
PCM either:
Activates starter relay
Activates starter directly
Starter control circuit part of theft-deterrent system

58. Engine Starting Systems—Vehicle Immobilization System (1 of 4)
A computer-managed security system with an electronic system to identify each unique vehicle key by security code
Built-in electronic circuit board to store the code
Difficult to start vehicle without a coded key
Key and code must both match the vehicle.

59. Engine Starting Systems—Vehicle Immobilization System (2 of 4)
Key coding done with scan tool with:
Correct software
Pass-through device to enable the BCM to be programmed from the Internet

60. Engine Starting Systems—Vehicle Immobilization System (3 of 4)
Key ID system—two operation states
Mobilized—engine components operate normally
Immobilized—activated to protect vehicle and prevent the engine from starting/cranking

61. Engine Starting Systems—Vehicle Immobilization System (4 of 4)
Immobilizes when engine switches off and key removed
Flashing warning lamp to identify immobilization
To mobilize, either:
Key inserted in ignition and switched on
Smart key, hit brake pedal, push start button

62. Engine Starting Systems— Keyless Starting/Remote Starting
Now used by some immobilizer systems
Start button on dash
Works only if key in proximity of the vehicle
Key detected wirelessly to mobilize the system
Vehicle is started remotely by pressing start button on key fob.

63. Engine Starting Systems— Starter Drives and the Ring Gear (1 of 6)
Transmits rotational drive from starter armature to engine via ring gear mounted on either the:
Engine flywheel
Flex plate
Torque converter

64. Engine Starting Systems— Starter Drives and the Ring Gear (2 of 6)
Composed of:
Pinion gear
Internal spline that mates with external spine on armature shaft
Overrunning clutch
Return spring

65. Engine Starting Systems— Starter Drives and the Ring Gear (3 of 6)
Pinion gear small compared to ring gear
Starter turns faster than engine ring gear.
Allows starter motor to crank over the ICE
Overrunning clutch drives pinion gear in one direction, allows it to freewheel in opposite direction.

66. Engine Starting Systems— Starter Drives and the Ring Gear (4 of 6)
Roller bearings between inner and outer shell
Outer shell—tapered ramps for the roller bearings to ride
Rollers pushed toward ramp ends by springs

67. Engine Starting Systems— Starter Drives and the Ring Gear (5 of 6)
Rollers are pushed toward ramp ends by springs.
Rollers roll in forward direction between tapered ramps, pinched between shells.
Once engine starts, rollers roll in opposite direction up inclined ramps.
Starter motor is prevented from being driven by the engine once engine starts.

68. Engine Starting Systems— Starter Drives and the Ring Gear (6 of 6)
Starter drive teeth engage ring gear when starter solenoid activates.
Starter drive connects to the solenoid plunger by a lever.
Pushes starter drive into mesh with ring gear
Retracts starter drive when solenoid deactivates

69. Engine Starting Systems— Starter Location Variation
Traditionally mounted on one side of engine
Often under exhaust manifolds or engine covers
Transverse engines—often mounted on side closest to firewall
Easier to reach from underneath the vehicle
May need to remove engine covers and components to reach it

70. Engine Starting Systems— Hybrid Vehicle Starters (1 of 2)
Hybrid vehicles use both ICE and electric motors to power the drive train.
Some powered by an ICE, with idle-stop feature
A high-voltage electric motor for:
Engine start-up
Auxiliary power
Regenerative braking

71. Engine Starting Systems— Hybrid Vehicle Starters (2 of 2)
ICE needs cranking over.
On most, done by main electric drive motor
Spins ICE at faster and smoother rate
Some with a more conventional ICE starter if main high-voltage battery bank discharged

72. Summary
The starting system provides a method of rotating (cranking) the vehicle’s internal combustion engine (ICE) to begin the combustion cycle.
The starting system consists of a battery, cables, a solenoid, a starter motor, a ring gear, and an ignition switch.

73. Summary
The starter motor converts electrical energy to mechanical energy.
Some starters operate through gear reduction, giving the same amount of torque at less size and weight.
A starter motor is basically an electromagnet.
The starter motor pinion must mesh with the engine ring gear to turn the engine over and allow the vehicle to start.

74. Summary
Once the engine starts running on its own, the starter must disengage from the ring rear to avoid damaging the starter or the ring gear.
The solenoid on the starter motor performs two main functions: It switches the high current flow required by the starter motor, and it engages the starter drive with the ring gear.

75. Summary
Vehicle immobilizers generally comprise a computer-managed security system that disables the start and engine systems by using an electronic system to uniquely identify each vehicle key by security code system.

76. Credits
Unless otherwise indicated, all photographs and illustrations are under copyright of Jones & Bartlett Learning.