ELECTRICAL
8-23
Electrical
ENGINE ELECTRICAL ALTERNATOR
terminal
Electronic
voltage regulator
Stern
terminal
Fan
The alternator has a built-in electronic voltage regulator. The output voltage is controlled by the voltage regulator through detection of the battery voltage. SPECIFICATIONS Nominal output . .
for Non-turbo Engine with for Non-turbo Engine with and Turbo Engine 14.4 at
Regulated voltage . . . . . . . . Rotating direction . . . . . . . . Clockwise
(viewed from pulley side)
ELECTRICAL
Engine Electrical
STARTER MOTOR
Reduction gear
Magnetic switch
terminal Shift lever
Pinion gear
Armature Permanent magnet
SPECIFICATIONS Type ................................ Nominal output ............ Rotating direction ........
Reduction drive
1.2 Clockwise (viewed from pinion side)
clutch
ELECTRICAL
8-25
Engine Electrical
IGNITION SYSTEM
Battery
control
1I
Power 1
Sensors
coil
To tachometer
engine speed
The ignition system is a two-coil ignition system that supplies sufficient energy for ignition up to high speeds. This engine does not have a distributor since the engine control unit directly activates the power transistor for ignition timing control. The functions and controls of the engine control unit and various sensors that control the ignition timing are described in the next chapter, IGNITION CONTROL SYSTEM. This ignition system has two power transistors and two ignition coils. Power transistor “A” controls the primary current of ignition coil “A” to activate the
and cylinders. spark plugs of the Similarly, power transistor controls ignition coil “B” which activates the spark plugs of the and cylinders. In this way, spark plugs of two cylinders are activated but actual ignition takes place only in the single cylinder that is on its compression stroke, because the other is on its exhaust stroke at that time. Power transistors “A” and “B” are activated by signals from the engine control unit, that controls which cylinder is fired at what time.
ELECTRICAL
Signal unit for , tachometer
No. 3
Engine Electrical
IGNITION COIL Two compact ignition coils of a molded type featuring outstanding ignition performance are used. Being a two-coil type, the ignition coil has a unit to supply signals for the tachometer. Specifications items
Specifications
Primary coil resistance Secondary coil resistance
0.86 at
12.1 at
Cylinder No. mark
To No. 1 spark plug To No. 4 spark plug
To No. 3 spark plug To No. 2 spark plug
POWER TRANSISTOR The power transistor is driven by a signal from the engine current of the ignition coil on control unit and turns the and off. Terminal symbol
External connection
Ground Engine control unit Engine control unit
Ignition coil terminal “2” Ignition coil terminal “1”
SPARK PLUG OC:
Engine Non-turbo
mm I
mm
8-27
Engine Electrical
ELECTRICAL IGNITION TIMING CONTROL SYSTEM
Ignition switch Air flow sensor
unit
Intake air temp. sensor Barometric pressure sensor Engine coolant temp. sensor position switch Top dead center sensor Crank angle sensor Vehicle speed sensor Power Ignition switch “ST” terminal Detonation sensor for turbo engine only
109 12
a
The ignition control system uses the engine control unit, that judges which cylinder is to be fired at what time based on the signals coming from various sensors. The engine control unit activates the power transistors so that ignition occurs, taking into
Ignition coil I
To tachometer Terminal for engine speed detection Terminal for ” idle speed adjustment and
consideration the operating conditions of the gine. The functions and controls of the engine control unit are described in the following page. The constructions and functions of the various sensors are described in GROUP 14.
ELECTRICAL
Engine Electrical
IGNITION TIMING CONTROL
of
power distribution control (selection of power transistor
signal
Control mode II
II
Control mode data
II
control
Power
Power “A�
The above block diagram shows the of the engine control unit for ignition timing control. One feature is that the engine control unit provides ignition power distribution control which is necessary because this engine is without a distributor, as has been described earlier. By activating two power transistors alternately, the primary current of two cylinders ignition coils, one for the No. 1 and and one for the No. 2 and No, 3 cylinders is turned on and thus causing the cylinders to fire in the order of 1, 3, 4, 2. For ignition timing control, -optimum ignition timing
is determined by making preset corrections which has been for engine coolant temperature, intake air temperature other conditions of ignition advance angle that has been preset according to the engine operating conditions. For vehicles with bocharger have a knocking control that corrects ignition advance angle according to the presence or absence of knocking. The engine control unit also controls the primary current energization time in order to secure stable ignition energy. These controls - - - - - - - are explained in detail below.
. ELECTRICAL
8-29
Engine Electrical
Power Distribution No. 1 TDC
No. 3 TDC
No
No 2 TDC
I dead center , I
Crank
angle Combustion stroke
No. 1 cylinder Intake stroke
No. 3 No. 4 No. 2 cylinder
Compression stroke Intake stroke
,
Exhaust stroke . stroke
stroke
Exhaust stroke Exhaust stroke
Compression stroke intake stroke
stroke
Intake stroke
stroke
The cylinder to be ignited is determined based on the top dead center signal and the crank angle signal. the top dead center signal has already been input to the engine control unit when the crank angle signal is input, the unit decides that the No. 1 cylinder (or No. 4) cylinder is on the compression stroke and turns off power transistor “A” and cylinder) to fire. causes the No. 1 cylinder (and If the top dead center signal has not been input to the engine control unit when the crank angle signal is input, the unit decides that the cylinder (or No. 2) cylinder is on the compression stroke and turns off power transistor “B” and causes the cylinder (and No. 2 cylinder) to fire. In this way, the power transistors “A” and are turned off alternately for ignition power distribution.
Ignition Timing The period of the crank angle signal is measured and based on this the time taken for the crank to make a revolution is determined. I
Crank
count start
Once is determined, the ignition timing is calculated using the value and the ignition advance angle (advance from determined by the engine control unit, with the Signal as a reference; then the primary current shut-off signal Sent to the power transistor when time has elapsed from the count start position (75 angle calculated by the engine
where is the ignition advance
ELECTRICAL
Engine Electrical
Ignition Advance Angle Control While
angle coolant temperature sensor
pressure sensor
temperature , sensor
normal
transistor
Advance angle map value to engine speed and intake volume
ignition
Engine coolant temperature correction
Barometric pressure
Intake air temperature
4
To ignition coil
adjustment
angle
The engine control unit has the ignition advance angle value for all cylinder stroke intake air volumes (engine load) and engine speeds stored in its memory; this is called the basic ignition advance angle. The control unit makes corrections in this value according to the engine operating conditions such as the engine coolant temperature, barometric pressure (altitude) and intake air temperature to obtain optimum advance angle for current engine conditions. At the engine start and during ignition timing adjustment, however, it is set to preset fixed timing. WHILE CRANKING When cranking, the ignition advance angle is fixed at in synchronization with the crank angle signal. (2) DURING NORMAL OPERATION Basic ignition advance angle: Map values that have been preset for all stroke intake air volumes (engine load) and engine speeds.
Engine coolant temperature correction: The engine coolant temperature sensor detects the engine coolant temperature and when it is low, the ignition timing is advanced to improve Barometric pressure correction: The barometric pressure sensor detects the barometric pressure and determines the altitude. When the pressure is low (i.e. when the vehicle is at a high altitude), the ignition timing is advanced to secure maximum driveability. intake air temperature correction: The intake air temperature sensor detects the intake air temperature and when it is low, the ignition timing is delayed to prevent knocking in cold weather. When it is high, the timing is also delayed to prevent of knocking. DURING ADJUSTMENT OF IGNITION TIMING When the terminal for ignition timing and idle speed adjustment is shorted to ground, the ignition timing in synchronization with the crank is set at angle signal, If the ignition timing does not agree turn with the reference ignition timing of the crank angle sensor to adjust the timing so that the crank angle signal agrees with the reference ignition timing. When the engine speed is approximately 1,200 rpm or higher, however, the timing advance is according to normal operation and therefore this ignition timing adjustment is not available.
Knocking Control for Turbo Engine Only coolant Advance map value
pressure
I
sensor
angle
Knock
I
Engine knocking is detected and the ignition timing is controlled accordingly to prevent continued knocking and to protect the engine. When knocking is detected, the engine control unit delays the ignition timing according to the signal from the detonation sensor until the knocking is eliminated (up to a maximum 12� in crank angle). In the case of an open or short circuit of the detonation sensor harness. the timing is delayed by a fixed angle (approximately 8� in crank angle) to prevent knocking.
If knocking continues, the advance angle map value is corrected gradually in the delay direction. In the absence of knocking, the map value is corrected gradually in the advance direction. In this way, optimum ignition timing is constantly controlled; this control is effective even when fuels of different octane ratings are used. This means that the engine is protected from knocking damage even when the fuel is switched from premium to regular or vice versa.
Energization Time Control While Synchronized with crank angle sensor signal During normal operation Map value responding to battery voltage
time is clipped at 75% of ignition interval
In order to obtain stable ignition energy, the gization time of the ignition coil primary current is controlled as to keep current at a constant value when the primary current is shut off. DURING NORMAL OPERATION Basic energization time The increase of the ignition coil primary current changes with the battery voltage. Therefore, the energization time is so controlled that the primary The basic current at time of ignition becomes energization time is so set that it is longer when the battery voltage is low and is shorter when the
Energization time clip: The new two-coil ignition system has its ignition interval doubled when compared to the al single type, allowing a longer clip time. As a result, a long energization time is secured for sufficient ignition energy even during high speed operation. WHILE CRANKING When cranking, the ignition coil is energized in synchronization with the crank angle signal.