ECD SYSTEM(w/ Glow Plug Controller) SYSTEM DESCRIPTION

Fuel Injection Timing Control

1. Fuel injection timing is controlled as shown below.

   

   *1	ECM	*2	Atmospheric Pressure Sensor
   *3	Crankshaft Position Sensor (Engine Speed)	*4	Intake Air Temperature Sensor
   *5	Engine Coolant Temperature Sensor	*6	Diesel Turbo Pressure Sensor
   *a	Basic Injection Timing	*b	Correction
   *c	Injection Timing	*d	Final Injection Volume

Fuel Pressure Control

1. The ECM calculates the target injection pressure (30000 to 180000 kPa) based on the final injection volume and signals from the crankshaft position sensor.

2. To control fuel pressure, signals sent to the fuel metering unit of the supply pump regulate the pumping volume. Signals sent to the pressure control valve of the common-rail regulate the discharge volume, so that the pressure detected by the fuel pressure sensor matches the target injection pressure.

   

   *1	Suction Control Valve (Supply Pump Assembly)	*2	ECM
   *3	Fuel Pressure Sensor (Common Rail Assembly)	*4	Pressure Control Valve (Common Rail Assembly)
   *5	Common Rail Assembly	*6	Injector assembly
   *7	Atmospheric Pressure Sensor	*8	Intake Air Temperature Sensor
   *9	Engine Coolant Temperature Sensor	*10	Crankshaft Position Sensor (Engine Speed)
   *a	Final Injection Volume	*b	Calculation of Target Injection Pressure
   *c	Electric Signal	*d	Fuel Pressure

   Suction control valve control	The ECM controls the suction control valve opening in order to regulate the fuel volume that is pumped by the supply pump to the common-rail. Consequently, the fuel pressure in the common-rail is controlled to the target injection pressure.
   Suction control valve opening small	When the suction control valve opening is small, the fuel suction area is kept small, which decreases the transferable fuel quantity.
   	The plunger strokes fully, however, the suction volume is small due to the small suction area.
   	Pumping will start when the fuel pressure has becomes higher than the common-rail pressure.
   Suction control valve opening large	When the suction control valve opening is large, the fuel suction area is kept large, which increases the transferable fuel quantity.
   	The plunger strokes fully and suction volume will increase because the suction area is large.
   	Pumping will start when the fuel pressure has becomes higher than the common-rail pressure.

   Suction Control Valve Opening Small:

   

   *a	Cam Stroke	*b	Suction Control Valve
   *c	Small Suction Area	*d	Fuel Pumping Mass
   *e	Plunger Top-dead-center	*f	Plunger Bottom-dead-center
   *g	Pumping Starting Point	-	-

   Suction Control Valve Opening Large:

   

   *a	Cam Stroke	*b	Suction Control Valve
   *c	Large Suction Area	*d	Fuel Pumping Mass
   *e	Plunger Top-dead-center	*f	Plunger Bottom-dead-center
   *g	Pumping Starting point	-	-

Idle Speed Control

1. ISC correction is controlled as shown below.

   

   *1	ECM	*2	Engine Coolant Temperature Sensor
   *3	Vehicle Speed Sensor	*4	Crankshaft Position Sensor
   *5	Atmospheric Pressure Sensor	-	-
   *a	A/C Switch Signal (w/ Air Conditioning System)	*b	Power Heater Signal (w/ Combustion Type Power Heater)
   *c	PTC Heater Signal (w/ PTC Heater)	*d	Target Speed Calculation
   *e	Comparison	*f	Actual Engine Speed
   *g	DPF Status	*h	ISC Correction

Pilot Injection Control

1. Pilot injection is a method that provides an auxiliary fuel injection before the main fuel injection takes place. The purpose of pilot injection is to gently start the combustion of the fuel of the main injection in order to reduce combustion noise.

   

   *a	w/ Pilot Injection Control	*b	w/o Pilot Injection Control
   *c	Fuel Injection	*d	Combustion Pressure
   *e	Pilot Injection	*f	Main Injection
   *g	Time	-	-

2. During pilot injection, the pilot injection volume, timing, and interval (between pilot injection and main injection) are controlled as shown below.

   

   *1	ECM	*2	Atmospheric Pressure Sensor
   *3	Crankshaft Position Sensor (Engine Speed)	*4	Atmospheric Temperature Sensor
   *5	Engine Coolant Temperature Sensor	*6	Diesel Turbo Pressure Sensor
   *a	Basic Pilot Injection (Volume, Timing, Interval)	*b	Correction
   *c	DPF Status	*d	Pilot Injection (Volume, Timing, Interval)
   *e	Final Injection Volume	-	-

Turbocharger Control

1. The ECM controls the nozzle vane position in order to obtain the calculated target turbo pressure appropriate to the engine operating condition.

2. The ECM calculates the optimal nozzle vane position in accordance with the driving conditions (engine speed, injection volume, atmospheric pressure, engine coolant temperature, etc.). The ECM controls the nozzle vane position in accordance with the target nozzle vane position calculated by the ECM and the actual nozzle vane position signal provided by the nozzle vane position sensor.

   

   *1	DC Motor	*2	Nozzle Vane Position Sensor
   *3	Diesel Turbo Pressure Sensor	*4	ECM
   *5	Atmospheric Pressure Sensor	*6	Crankshaft Position Sensor
   *7	Engine Coolant Temperature Sensor	*8	Atmospheric Temperature Sensor
   *a	DC Motor Operation Current	*b	Actual Nozzle Vane Position Signal
   *c	DPF Status	*d	Injection Volume

Catalyst Support Control

1. For effective functioning of the NOx-purifying NSR (NOx Storage Reduction) catalyst and PM-removing DPF, intake air volume and fuel injection pattern are controlled according to information from 2 exhaust temperature sensors, 2 air fuel ratio sensors and a differential pressure sensor.

   

   *1	ECM	*2	Injector Assembly
   *3	Engine Coolant Temperature Sensor	*4	Mass Air Flow Meter
   *5	NSR (NOx Storage Reduction) Catalyst	*6	DPF (Diesel Particurate Filter)
   *7	H2S Sweeper	*8	Air Fuel Ratio Sensor (Bank 1 Sensor 1)
   *9	Exhaust Gas Temperature Sensor B1S1	*10	Exhaust Gas Temperature Sensor B1S2
   *11	Differential Pressure Sensor	*12	Air Fuel Ratio Sensor (Bank 1 Sensor 2)

   
   

   • DPF Control

   
   

   • If the DPF catalyst temperature becomes low, catalyst performance decreases, resulting in an increase of the amount of Particulate Matter (PM) stuck in the filter substrate. When the ECM detects clogs in the filter substrate, by calculating the accumulated volume of PM discharged by the engine, after injection and idle-up control are performed to reduce PM. At the same time, the filter substrate temperature becomes high and the PM reacts with active oxygen and changes into CO2. Fuel efficiency drops during this control.

     Tech Tips

     In the after injection, fuel is injected into the cylinder at a timing at which the fuel is not combusted, sending the fuel into the DPF and increasing the exhaust gas temperature by catalytic oxidation reaction, resulting in increasing the catalyst temperature.

   • A small portion of the fuel injected by the after injection enters the crankcase via the cylinder walls, causing dilution of the engine oil. The oil level is less likely to increase during normal use, as the fuel in the oil evaporates with the increase in the engine oil temperature.

     However, the engine oil is gradually diluted after consecutive driving of which the running distance per single trip is short, which results in reducing the lubricating performance. In an attempt to prevent this, the oil level sensor detects the engine oil level and turns on/blinks the oil maintenance indicator to urge the driver to change the engine oil.

   
   

   • NSR Control

   
   

   • The NSR catalyst adsorbs NOx, reducing the amount in the exhaust gas, but the amount that can be adsorbed is limited, so the NOx stored in the catalyst is periodically reduced. To reduce the NOx, the A/F of the exhaust gas passing through the catalyst must be controlled to a specified value to supply CO. For this reason, based on the information from the air fuel ratio sensor (bank 1 sensor 1), intake air volume and after injection are controlled to create a reducing atmosphere. Also, judgment of whether reduction has completed is made based on information from the air fuel ratio sensor (bank 1 sensor 2).

2. If the DPF catalyst temperature becomes low, catalyst performance decreases, resulting in an increase of the amount of Particulate Matter (PM) stuck in the filter substrate. When the ECM detects clogs in the filter substrate, by calculating the accumulated volume of PM discharged by the engine, after injection and idle-up control are performed to reduce PM. At the same time, the filter substrate temperature becomes high and the PM reacts with active oxygen and changes into CO2. Fuel efficiency drops during this control.

   Tech Tips

   In the after injection, fuel is injected into the cylinder at a timing at which the fuel is not combusted, sending the fuel into the DPF and increasing the exhaust gas temperature by catalytic oxidation reaction, resulting in increasing the catalyst temperature.

Supply Pump

1. Due to the rotation of the inner cam (eccentric cam), the outer cam pushes plunger "A" upward as illustrated below. The force of the spring pulls plunger "C". As a result, plunger "C" draws fuel in, and plunger "A" pumps fuel at the same time.

   

   *1	Suction Control Valve	-	-
   *a	Plunger A	*b	Plunger B
   *c	Plunger C	*d	to Common-rail
   *e	Pumping Complete	*f	Pumping Start
   *g	Suction	-	-