Page 289 of 796
09-131451-01
3. CIRCUIT DIAGRAM
Page 290 of 796
10-31413-00
1. SPECIFICATIONS
Description Specification
Glow plug Rated voltage 4.4 V
Max. temperature1100 °C
Operating temperature1080 °C ~ 1000 °C
Resistance23 °C: 0.39 ~ 0.52Ω
Glow plug control unit Operating voltage 6 ~ 16 V
Operating temperature-40°C ~ 110°C
Dark current Max. 1 mA
Page 291 of 796
10-4
1. OVERVIEW
The pre-heating system for D20DTR engine has the glow plug to the cylinder head (combustion
chamber), and improves the cold start performance and reduces the emission level.
The pre-heating resistor (air heater) is used to heat the intake air.
This enables the diesel fuel to be ignited in low temperature condition.
The ECU receives the information such as, engine rpm, coolant temperature, engine torque, etc.,
through CAN communication during pre-heating process; and the pre-heating control unit controls the
pre-heating, heating during cranking and post-heating by the PWM control.
Glow plug
Engine ECU (D20DTR)Glow indicator
Glow plug control unit
(GCU)
Page 292 of 796
10-51413-00
2. SYSTEM OPERATION
1) Input/Output Diagram of Glow Plug Control Unit
2) System Diagram
Page 293 of 796
Page 294 of 796
10-71413-00
4) Operation
Glow plug is installed in the cylinder head. It enhances the cold starting performance and reduces the
exhaust gas during cold starting.
ECU receives the data (engine rpm, coolant temperature, vehicle speed) through CAN lines. Based on
the data, GCU controls the pre-glow, cranking and post-glow. It also checks the glow plugs, and sends
the result to ECU.
(1) Temperature/Current Properties of GCU
GCU increases the temperature of glow plug very rapidly (approx. 2 seconds up to
1000°C)
FETs (similar to transistor) for each cylinder are integrated in GCU. During the pre-glow
period, battery voltage is supplied to the glow plugs directly to heat them rapidly.
After getting the desired temperature by pre-glowing, the temperature is controlled by duty
ratio. Step 1:
Step 2 & 3:
Step 4:
This shows the supplying voltage and time by GCU in each step. The step 4 is the period to keep
the temperature. -Step 1: I1
Step 2: I2
Step 3: I3
Step 4: I4
Page 295 of 796
10-8
(2) Pre-heating time control based on battery voltage
GCU monitors the battery voltage. If it is low, GCU extends the pre-heating time.
GCU monitors the energy to glow plugs (the amount of pre-heating energy is always same). -
-
GCU monitors the battery voltage. If it is low, GCU extends the pre-heating time to get enough
energy. -
GCU monitors the battery voltage. If it is low, GCU increases PWM duty.. -
Page 296 of 796
10-91413-00
(3) Power control
GCU PWM control
This describes the voltage supplying types to glow plugs. -
GCU estimates the temperature of glow plug for pre-heating. To avoid the power loss and overheat,
GCU supplies the lowest power for getting target temperature when turning ON the ignition from
OFF. -
(4) Operation
Frequency: 20~33Hz
PWM control duty ratio
- 1st step: 100%
- 2~3 step: 35%
- 4th step: 23%