DENSO COMMON RAIL SYSTEM (CRS). SERVICE MANUAL (2007)

Table of Contents

Operation Section

GENERAL DESCRIPTION

1.1

Changes In Environment Surrounding The Diesel Engine

1-1

1.2

Demands On Fuel Injection System

1-2

1.3

Types Of And Transitions In ECD (ELECTRONICALLY CONTROLLED DIESEL) Systems

1-3

1.4

Common Rail System Characteristics

1-4

1.5

Common Rail System And Supply Pump Transitions

1-5

1.6

Injector Transitions

1-5

1.7

Common Rail System Configuration

1-6

COMMON RAIL SYSTEM OUTLINE

2.1

Layout of Main Components

1-7

SUPPLY PUMP DESCRIPTION

3.1

HP0 Type

1-12

3.2

HP2 Type

1-18

3.3

HP3 Type

1-27

3.4

HP4 Type

1-41

RAIL DESCCRIPTION

4.1

Rail Functions and Composition

1-46

4.2

Component Part Construction and Operation

1-46

INJECTOR DESCRIPTION

5.1

General Description

1-50

5.2

Injector Construction and Features

1-51

5.3

Injector Operation

1-54

5.4

Injector Actuation Circuit

1-54

5.5

Other Injector Component Parts

1-56

DESCRIPTION OF CONTROL SYSTEM COMPONENTS

6.1

Engine Control System Diagram (Reference)

1-59

6.2

Engine ECU (Electronic Control Unit)

1-60

6.3

EDU (Electronic Driving Unit)

1-60

6.4

Various Sensors

1-61

CONTROL SYSTEM

7.1

Fuel Injection Control

1-66

7.2

E-EGR System (Electric-Exhaust Gas Recirculation)

1-76

7.3

Electronically Controlled Throttle (Not Made By DENSO)

1-78

7.4

Exhaust Gas Control System

1-79

7.5

DPF System (Diesel Particulate Filter)

1-80

7.6

DPNR SYSTEM (DIESEL PARTICULATE NOx REDUCTION)

1-82

Table of Contents

8. DIAGNOSIS

8.1

Outline Of The Diagnostic Function

1-83

8.2

Diagnosis Inspection Using DST-1

1-83

8.3

Diagnosis Inspection Using The MIL (Malfunction Indicator Light)

1-84

8.4

Throttle Body Function Inspection

1-86

9. END OF VOLUME MATERIALS

9.1

Particulate Matter (PM)

1-87

9.2

Common Rail Type Fuel Injection System Development History And The World’s Manufacturers

1-87

9.3

Higher Injection Pressure, Optimized Injection Rates, Higher Injection Timing Control Precision, Higher Injection

Quantity Control Precision

1-88

9.4

Image Of Combustion Chamber Interior

1-90

Repair Section

DIESEL ENGINE MALFUNCTIONS AND DIAGNOSTIC METHODS (BASIC KNOWL-

EDGE)

1.1

Combustion State and Malfunction Cause

2-91

1.2

Troubleshooting

2-92

DIAGNOSIS OVERVIEW

2.1

Diagnostic Work Flow

2-93

2.2

Inquiries

2-94

2.3

Non-Reoccurring Malfunctions

2-96

DTC READING (FOR TOYOTA VEHICLES)

3.1

DST-2

2-98

3.2

DTC Check (Code Reading via the DST-2)

2-98

3.3

DTC Memory Erasure (via the DST-2)

2-98

TROUBLESHOOTING BY SYSTEM

4.1

Intake System Diagnosis

2-99

4.2

Fuel System Diagnosis

2-99

4.3

Basics of Electrical/Electronic Circuit Checks

2-102

TROUBLESHOOTING

5.1

Troubleshooting According to Malfunction Symptom (for TOYOTA Vehicles)

2-107

5.2

Other Malfunction Symptoms

2-122

DIAGNOSIS CODES (DTC)

6.1

DTC Chart (Example)

2-124

Operation Section

1-1

1. GENERAL DESCRIPTION

1.1 Changes In Environment Surrounding The Diesel Engine

z Throughout the world, there is a desperate need to improve vehicle fuel economy for the purposes of preventing global

warming and reducing exhaust gas emissions that affect human health. Diesel engine vehicles are highly acclaimed in

Europe, due to the good fuel economy that diesel fuel offers. On the other hand, the "nitrogen oxides (NOx)" and "par-

ticulate matter (PM)" contained in the exhaust gas must be greatly reduced to meet exhaust gas regulations, and tech-

nology is being actively developed for the sake of improved fuel economy and reduced exhaust gases.

(1) Demands on Diesel Vehicles

• Reduce exhaust gases (NOx, PM, carbon monoxide (CO), hydrocarbon (HC) and smoke).

• Improve fuel economy.

• Reduce noise.

• Improve power output and driving performance.

(2) Transition of Exhaust Gas Regulations (Example of Large Vehicle Diesel Regulations)

• The EURO IV regulations take effect in Europe from 2005, and the 2004 MY regulations take effect in North America

from 2004. Furthermore, the EURO V regulations will take effect in Europe from 2008, and the 2007 MY regulations

will take effect in North America from 2007. Through these measures, PM and NOx emissions are being reduced in

stages.

NOx

g/kWh

Europe

EURO

North America

1998 MY

2004 MY

2007 MY

3.5

2.7

North

America

2.0

0.13

1998 MY

2004 MY

2007 MY

0.11

0.03

0.27

0.013

20042005

2007 2008

20042005

2007 2008

Q000989E

Operation Section

1-2

1.2 Demands On Fuel Injection System

z In order to address the various demands that are imposed on diesel vehicles, the fuel injection system (including the

injection pump and nozzles) plays a significant role because it directly affects the performance of the engine and the

vehicle. Some of the demands are: higher injection pressure, optimized injection rate, higher precision of injection timing

control, and higher precision of injection quantity control.

< NOTE >

z For further information on higher injection pressure, optimized injection rate, higher precision of injection timing control,

and higher precision of injection quantity control, see the material at the end of this document.

Operation Section

1-3

1.3 Types Of And Transitions In ECD (ELECTRONICALLY CONTROLLED

DIESEL) Systems

z ECD systems include the ECD-V series (V3, V4, and V5) which implements electronic control through distributed pumps

(VE type pumps), and common rail systems made up of a supply pump, rail, and injectors. Types are the ECD-V3 and

V5 for passenger cars and RVs, the ECD-V4 that can also support small trucks, common rail systems for trucks, and

common rail systems for passenger cars and RVs. In addition, there are 2nd-generation common rail systems that sup-

port both large vehicle and passenger car applications. The chart below shows the characteristics of these systems.

'85

'90

'95

'00

ECD-V1

ECD-V3

ECD-V4

· The world's first SPV (electromagnetic

spill valve system) is used for fuel

ECD-V5

injection quantity control, so the

quantity injected by each cylinder can

· Inner Cam Pumping Mechanism

· Uses pilot injection to reduce the

be controlled.

· Maximum Injection Pressure 130 MPa

engine combustion noise.

· Maximum Injection Pressure 60 MPa

· Maximum Injection Pressure

100 MPa

System

Types and

Transitions

ECD-V3

ECD-V4

ECD-V5

Large Vehicle Common Rail

(HP0)

Passenger Car Common Rail

(HP2)

Common Rail System

· Fuel raised to high pressure by the

supply pump is temporarily

accumulated in the rail, then injected

after the injector is energized.

· Uses pilot injection to reduce the

engine combustion noise

· Maximum Injection Pressure 180 MPa

Supply Pump

Injector

Rail

Q000750E

Operation Section

1-4

1.4 Common Rail System Characteristics

z The common rail system uses a type of accumulation chamber called a rail to store pressurized fuel, and injectors that

contain electronically controlled solenoid valves to inject the pressurized fuel into the cylinders.

z Because the engine ECU controls the injection system (including the injection pressure, injection rate, and injection tim-

ing), the injection system is independent and thus unaffected by the engine speed or load.

z Because the engine ECU can control injection quantity and timing to a high level of precision, even multi-injection (mul-

tiple fuel injections in one injection stroke) is possible.

z This ensures a stable injection pressure at all times, even in the low engine speed range, and dramatically decreases

the amount of black smoke ordinarily emitted by a diesel engine during start-up and acceleration. As a result, exhaust

gas emissions are cleaner and reduced, and higher power output is achieved.

(1) Features of Injection Control

Injection Pressure Control

• Enables high-pressure injection even at low engine speeds.

• Optimizes control to minimize particulate matter and NOx emissions.

Injection Timing Control

• Enables finely tuned optimized control in accordance with driving conditions.

Injection Rate Control

• Pilot injection control injects a small amount of fuel before the main injection.

Common Rail System

Injection Pressure Control

Injection Timing Control

Injection Rate Control

Pilot injection

After-Injection

Optimized and Higher Pressure

· Injection pressure is more than double the current

Pre-Injection

Post-Injection

pressure, which makes it possible to greatly reduce

particulate matter.

Electronic Control Type

Main Injection

Common Rail System

Crankshaft Angle

Injection Quantity Control

Cylinder Injection Quantity Correction

Conventional

Pump

Speed

Injection Pressure

Q000751E

Operation Section

1-5

1.5 Common Rail System And Supply Pump Transitions

z The world's first common rail system for trucks was introduced in 1995. In 1999, the common rail system for passenger

cars (the HP2 supply pump) was introduced, and then in 2001 a common rail system using the HP3 pump (a lighter and

more compact supply pump) was introduced. In 2004, the three-cylinder HP4 based on the HP3 was introduced.

1996

1998

2000

2002

2004

2006

Common Rail

1st Generation Common Rail System

2nd Generation Common Rail System

System

HP0

120MPa

Large Trucks

HP4

Medium-Size Trucks

180MPa

Pre-Stroke Quantity Adjustment

Suction Quantity

Adjustment

HP3

HP2

Compact Trucks

180MPa

Passenger Vehicles

Suction Quantity

Adjustment

Suction Quantity

135MPa

Adjustment

Q000752E

1.6 Injector Transitions

1st Generation

2nd Generation

· 120MPa

· 180MPa

· Pilot Injection

· Multi-Injection

· 135MPa

· Pilot Injection

Q000753E

Operation Section

1-6

1.7 Common Rail System Configuration

z The common rail control system can be broadly divided into the following four areas: sensors, engine ECU, EDU, and

actuators.

Sensors

z Detect the condition of the engine and the pump.

Engine ECU

z Receives signals from the sensors, calculates the proper injection quantity and injection timing for optimal engine oper-

ation, and sends the appropriate signals to the actuators.

EDU

z Enables the injectors to be actuated at high speeds. There are also types with charge circuits within the ECU that serve

the same role as the EDU. In this case, there is no EDU.

Actuators

z Operate to provide optimal injection quantity and injection timing in accordance with the signals received from the en-

gine ECU.

Engine Speed Sensor /

Supply Pump

TDC (G) Sensor

(SCV: Suction Control Valve)

EDU

Accelerator Position Sensor

Injector

Engine ECU

Other Sensors

Other Actuators

and Switches

Diagnosis

Q000754E

Operation Section

1-7

2. COMMON RAIL SYSTEM OUTLINE

2.1 Layout of Main Components

z Common rail systems are mainly made up of the supply pump, rail, and injectors. There are the following types accord-

ing to the supply pump used.

(1) HP0 Type

• This system is the first common rail system that DENSO commercialized. It uses an HP0 type supply pump and is

mounted in large trucks and large buses.

Exterior View of Main System Components

Rail

Supply Pump (HP0 Type)

Injector

Q000755E

Configuration of Main System Components (Example of HP0)

Engine ECU

Accelerator

Position Sensor

Rail

Rail Pressure Sensor

Fuel Temperature

Sensor

Injector

Coolant Temperature

PCV (Pump Control Valve)

Sensor

Supply Pump

Cylinder

Recognition Sensor

(TDC (G) Sensor)

Crankshaft Position Sensor (Engine Speed Sensor)

Q000756E

Operation Section

1-8

(2) HP2 Type

• This system uses a type of HP2 supply pump that has been made lighter and more compact, and is the common rail

system for passenger cars and RVs instead of the ECD-V3.

Exterior View of Main System Components

Rail

Supply Pump (HP2 Type)

Injector

Q000757E

Mounting Diagram of Main System Components

EGR Valve

Intake Air Pressure Sensor

Engine ECU

Accelerator Position Sensor

Injector

Rail Pressure Sensor

E-VRV

Coolant Temperature

Intake Air Temperature

Sensor

EDU (Electronic Driving Unit)

Crankshaft Position Sensor

(Engine Speed Sensor)

Rail

Supply Pump

Cylinder Recognition Sensor

(TDC (G) Sensor)

Q000758E

Operation Section

1-10

(3) HP3 Type, HP4 Type

HP3 Type

• This system uses an HP3 type supply pump that is compact, lightweight and provides higher pressure. It is mostly

mounted in passenger cars and small trucks.

HP4 Type

• This system is basically the same as the HP3 type, however it uses the HP4 type supply pump, which has an in-

creased pumping quantity to handle larger engines. This system is mostly mounted in medium-size trucks.

Exterior View of Main System Components

Rail

HP3

HP4

Supply Pump

Injector

Q000759E

Mounting Diagram for Main System Components

Throttle Body

Intake Air

Engine ECU

EGR Valve E-VRV for EGR

Pressure

Sensor

DLC3 Connector

Airflow Meter

(with Intake Air

Temperature Sensor)

Accelerator Position Sensor

EDU

EGR Shut-Off VSV

R/B

Coolant Temperature Sensor

Rail Pressure Sensor

Injector

Pressure Discharge Valve

Supply Pump

Crankshaft Position Sensor

HP3

HP4

SCV

(Engine Speed Sensor)

Fuel Temperature

(Suction Control

Sensor

Valve)

Cylinder Recognition Sensor

(TDC (G) Sensor)

SCV

Fuel Temperature

(Suction Control

Sensor

Valve)

Q000760E

Operation Section

1-12

3. SUPPLY PUMP DESCRIPTION

3.1 HP0 Type

(1) Construction and Characteristics

• The HP0 supply pump is mainly made up of a pumping system as in conventional in-line pumps (two cylinders), the

PCV (Pump Control Valve) for controlling the fuel discharge quantity, the cylinder recognition sensor {TDC (G) sen-

sor}, and the feed pump.

• It supports the number of engine cylinders by changing the number of peaks on the cam. The supply pump rotates at

half the speed of the engine. The relationship between the number of engine cylinders and the supply pump pumping

is as shown in the table below.

Supply Pump

Speed Ratio

Number of Pumping Rotations for 1

Number of Engine Cylinders

Number of

(Pump: Engine)

Cam Peaks

Cycle of the Engine (2 Rotations)

Cylinders

4 Cylinders

6 Cylinders

1 : 2

8 Cylinders

• By increasing the number of cam peaks to handle the number of engine cylinders, a compact, two-cylinder pump unit

is achieved. Furthermore, because this pump has the same number of pumping strokes as injections, it maintains a

smooth and stable rail pressure.

PCV (Pump Control Valve)

Delivery Valve

Element

Overflow Valve

Cylinder Recognition Sensor

Feed Pump

(TDC (G) Sensor)

Pulsar for TDC (G) Sensor

Tappet

Cam x 2

Q000768E

Operation Section

1-14

(3) Supply Pump Component Part Functions

Component Parts

Functions

Feed Pump

Draws fuel from the fuel tank and feeds it to the pumping mechanism.

Overflow Valve

Regulates the pressure of the fuel in the supply pump.

PCV (Pump Control Valve)

Controls the quantity of fuel delivered to the rail.

Pumping

Cam

Actuates the tappet.

Mechanism

Tappet

Transmits reciprocating motion to the plunger.

Plunger

Moves reciprocally to draw and compress fuel.

Delivery Valve

Stops the reverse flow of fuel pumped to the rail.

Cylinder Recognition Sensor {TDC (G)

Identifies the engine cylinders.

Sensor}

Feed Pump

• The feed pump, which is integrated in the supply pump, draws fuel from the fuel tank and feeds it to the pump chamber

via the fuel filter. There are two types of feed pumps, the trochoid type and the vane type.

Trochoid Type

- The camshaft actuates the outer/inner rotors of the feed pump, causing them to start rotating. In accordance with

the space produced by the movement of the outer/inner rotors, the feed pump draws fuel into the suction port and

pumps fuel out the discharge port.

Outer Rotor

To Pump Chamber

Suction Port

Discharge Port

Inner Rotor

From Fuel Tank

Q000770E

Vane Type

- The camshaft actuates the feed pump rotor and the vanes slide along the inner circumference of the eccentric ring.

Along with the rotation of the rotor, the pump draws fuel from the fuel tank, and discharges it to the SCV and the

pumping mechanism.

Discharge Port

Rotor

Eccentric Ring

Vane

Suction Port

Q000771E

Operation Section

1-15

PCV: Pump Control Valve

• The PCV (Pump Control Valve) regulates the fuel discharge quantity from the supply pump in order to regulate the

rail pressure. The fuel quantity discharged from the supply pump to the rail is determined by the timing with which the

current is applied to the PCV.

Actuation Circuit

- The diagram below shows the actuation circuit of the PCV. The ignition switch turns the PCV relay ON and OFF to

apply current to the PCV. The ECU handles ON/OFF control of the PCV. Based on the signals from each sensor,

it determines the target discharge quantity required to provide optimum rail pressure and controls the ON/OFF tim-

ing for the PCV to achieve this target discharge quantity.

From PCV relay

PCV

To Rail

PCV Relay

Ignition Switch

PCV1

PCV2

Q000772E

Pumping Mechanism

• The camshaft is actuated by the engine and the cam actuates the plunger via the tappet to pump the fuel sent by the

feed pump. The PCV controls the discharge quantity. The fuel is pumped from the feed pump to the cylinder, and then

to the delivery valve.

PCV (Pump Control Valve)

Delivery Valve

To Rail

Plunger

Camshaft

Feed Pump

Cam (3 Lobes: 6-Cylinders)

Pulsar for TDC (G) Sensor

Q000773E

Operation Section

1-16

CYLINDER RECOGNITION SENSOR {TDC (G) SENSOR}

• The cylinder recognition sensor {TDC (G) sensor} uses the alternating current voltage generated by the change in the

lines of magnetic force passing through the coil to send the output voltage to the ECU. This is the same for the engine

speed sensor installed on the engine side. A disc-shaped gear, which is provided in the center of the supply pump

camshaft, has cutouts that are placed at 120? intervals, plus an extra cutout. Therefore, this gear outputs seven puls-

es for every two revolutions of the engine (for a six-cylinder engine). Through the combination of engine-side engine

speed pulses and TDC pulses, the pulse after the extra cutout pulse is recognized as the No. 1 cylinder.

· For a 6-Cylinder Engine (Reference)

Cylinder Recognition Sensor

(TDC (G) Sensor)

No.1 Cylinder TDC (G) Pulse

· TDC (G) Pulse

No.6 Cylinder TDC (G) Standard Pulse

No.1 Cylinder Recognition TDC (G) Pulse

· Engine Speed Pulse

0 2 4 6 8 101214 0 2 4 6 8101 21 4 0 2 4 6 8 101 2

0 2 4 6 8101214 0 2 4 6 8101214 0 2 4 6 8 1012

0 2 4 6 8

No.1 Cylinder Engine Speed Standard Pulse

No.6 Cylinder Engine Speed Standard Pulse

Q000774E

Operation Section

1-17

(4) Supply Pump Operation

Supply Pump Overall Fuel Flow

• The fuel is drawn by the feed pump from the fuel tank and sent to the pumping mechanism via the PCV. The PCV

adjusts the quantity of fuel pumped by the pumping mechanism to the necessary discharge quantity, and the fuel is

pumped to the rail via the delivery valve.

Fuel Discharge Quantity Control

• The fuel sent from the feed pump is pumped by the plunger. In order to adjust the rail pressure, the PCV controls the

discharge quantity. Actual operation is as follows.

PCV and Plunger Operation During Each Stroke

Intake Stroke (A)

In the plunger's descent stroke, the PCV opens and low-pressure fuel is suctioned into the

plunger chamber via the PCV.

Pre-Stroke (B)

Even when the plunger enters its ascent stroke, the PCV remains open while it is not energized.

During this time, fuel drawn in through the PCV is returned through the PCV without being pres-

surized (pre-stroke).

Pumping Stroke (C)

At a timing suited to the required discharge quantity, power is supplied to close the PCV, the

return passage closes, and pressure in the plunger chamber rises. Therefore, the fuel passes

through the delivery valve (reverse cut-off valve) and is pumped to the rail. Specifically, the

plunger lift portion after the PCV closes becomes the discharge quantity, and by varying the tim-

ing for the PCV closing (the end point of the plunger pre-stroke), the discharge quantity is varied

to control the rail pressure.

Intake Stroke (A)

When the cam exceeds the maximum lift, the plunger enters its descent stroke and pressure in

the plunger chamber decreases. At this time, the delivery valve closes and fuel pumping stops. In

addition, the PCV opens because it is de-energized, and low-pressure fuel is suctioned into the

plunger chamber. Specifically, the system goes into state A.

Discharge Quantity

(H-h)

Intake Stroke

Pumping Stroke

Cam Lift

Pre-Stroke

Open Valve

PCV Operation Close Valve

When Discharge

Quantity Increases

Quantity Decreases

Pump Operation

Pumping the Required

Discharge Quantity

PCV

Return

From Fuel Tank

To Rail

Pumping

Mechanism

Delivery Valve

Plunger

(A)

(B)

(C)

(A')

Q000775E

Operation Section

1-18

3.2 HP2 Type

(1) Construction and Characteristics

• The supply pump is primarily composed of the two pumping mechanism (inner cam, roller, two plungers) systems,

the SCV (Suction Control Valve), the fuel temperature sensor, and the feed pump (vane type), and is actuated with

half the engine rotation.

• The pumping mechanism consists of an inner cam and a plunger, and forms a tandem configuration in which two sys-

tems are arranged axially. This makes the supply pump compact and reduces the peak torque.

• The quantity of fuel discharged to the rail is controlled by the fuel suction quantity using SCV (Suction Control Valve)

control. In order to control the discharge quantity with the suction quantity, excess pumping operations are eliminated,

reducing the actuation load and suppressing the rise in fuel temperature.

Fuel Temperature Sensor

Delivery Valve

Overflow

SCV

Fuel Suction (From Fuel Tank)

(Suction Control

Valve)

Regulating Valve

Feed Pump

Check Valve

Roller

Plunger

Inner Cam

Q000818E

Operation Section

1-21

(4) Component Part Functions

Component Parts

Functions

Feed Pump

Draws fuel from the fuel tank and feeds it to the pumping mechanism.

Regulating Valve

Regulates internal fuel pressure in the supply pump.

SCV (Suction Control Valve)

Controls the quantity of fuel that is fed to the plunger in order to control fuel

pressure in the rail.

Pumping

Inner Cam

Actuates the plunger.

Mechanism

Roller

Actuates the plunger.

Plunger

Moves reciprocally to draw and compress fuel.

Delivery Valve

Maintains high pressure by separating the pressurized area (rail) from the

pumping mechanism.

Fuel Temperature Sensor

Detects the fuel temperature.

Check Valve

Prevents the pressurized fuel in the pumping mechanism from flowing back

into the suction side.

Feed Pump

• The feed pump is a four-vaned type that draws fuel from the fuel tank and discharges it to the pumping mechanism.

The rotation of the drive shaft causes the feed pump rotor to rotate and the vane to move by sliding along the inner

surface of the casing (eccentric ring). Along with the rotation of the rotor, the pump draws fuel from the fuel tank, and

discharges it to the SCV and the pumping mechanism. To keep the vane pressed against the inner circumference, a

spring is provided inside each vane, in order to minimize fuel leakage within the pump.

Eccentric Ring

Spring

Rotor

Vane

Front Cover

Rear Cover

Q000821E

Regulating Valve

• The purpose of the regulating valve is to control the feed pressure (fuel pumping pressure) sending fuel to the pump-

ing mechanism. As the rotational movement of the pump increases and the feed pressure exceeds the pressure set

at the regulating valve, the valve opens by overcoming the spring force, allowing the fuel to return to the suction side.

Regulating Valve

Suction Inlet

Regulating Valve

Regulating Valve Body

Open Valve Pressure Characteristic

Open Valve

Filter

Pressure High

Spring

Open Valve

Piston

Pressure Low

Speed

Feed Pump

Bushing

(Discharge Side)

(Suction Side)

Q000822E

Operation Section

1-22

SCV: Suction Control Valve

• A solenoid type valve has been adopted. The ECU controls the duration of the current applied to the SCV in order to

control the quantity of fuel drawn into the pumping mechanism. Because only the quantity of fuel required to achieve

the target rail pressure is drawn in, the actuating load of the supply pump decreases, thus improving fuel economy.

Stopper

Coil

Needle Valve

Spring

Q000823E

SCV ON

- When current is applied to the coil, it pulls the needle valve upward, allowing fuel to be drawn into the pumping

mechanism of the supply pump.

To Pump Pumping Mechanism

From Feed Pump

Q000824E

SCV OFF

- When current is no longer applied to the coil, the needle valve closes and stops the suction of fuel.

From Feed Pump

Q000825E

Operation Section

1-23

Pumping Mechanism (Plunger, Inner Cam, Roller)

• The pumping mechanism is made up of the plunger, inner cam, and roller, and it draws in the fuel discharged by the

feed pump and pumps it to the rail. Because the drive shaft and the inner cam have an integral construction, the ro-

tation of the drive shaft directly becomes the rotation of the inner cam.

• Two plunger systems are arranged in series (tandem type) inside the inner cam. Plunger 1 is situated horizontally,

and plunger 2 is situated vertically. Plunger 1 and plunger 2 have their suction and compression strokes reversed

(when one is on the intake, the other is discharging), and each plunger discharges twice for each one rotation, so for

one rotation of the supply pump, they discharge a total of four times to the rail.

Plunger 1

Plunger 2

(Horizontal)

(Vertical)

Plunger Length Combination

· Plunger 1: Medium + Medium

· Plunger 2: Short + Long

Roller

Inner Cam

Roller Diameter:

(Cam Lift: 3.4mm)

Roller Length: 21mm

Material: Reinforced Ceramic

Plunger 1

Cam 90 Rotation

Plunger 2

Plunger 1: Start of Suction

Plunger 1: Start of Pumping

Plunger 2: Start of Pumping

Plunger 2: Start of Suction

Q000826E

Delivery Valve

• The delivery valve, which contains two valve balls, delivers the pressurized fuel from plungers 1 and 2 to the rail in

alternating strokes. When the pressure in the plunger exceeds the pressure in the rail, the valve opens to discharge

fuel.

From Plunger 1

To Rail

From Plunger 2

Guide

Stopper

Holder

Gasket

Valve Ball

· When Plunger 1 Pumping

· When Plunger 2 Pumping

Q000827E

Operation Section

1-24

Fuel Temperature Sensor

• The fuel temperature sensor is installed on the fuel intake side and utilizes the characteristics of a thermistor in which

the electric resistance changes with the temperature in order to detect the fuel temperature.

Thermistor

Resistance - Temperature

Characteristic

Temperature

Q000828E

Check Valve

• The check valve, which is located between the SCV (Suction Control Valve) and the pumping mechanism, prevents

the pressurized fuel in the pumping mechanism from flowing back into the SCV.

Pump Housing

Spring

Valve

To Pumping Mechanism

To SCV

Stopper

Plug

Q000829E

Check Valve Open

- During fuel suction (SCV ON), the feed pressure opens the valve, allowing fuel to be drawn into the pumping mech-

anism.

To Pumping Mechanism

From SCV

Q000830E

Check Valve Closed

- During fuel pumping (SCV OFF), the pressurized fuel in the pumping mechanism closes the valve, preventing fuel

from flowing back into the SCV.

From Pumping Mechanism

Q000831E

Operation Section

1-25

(5) Supply Pump Operation

Supply Pump Overall Fuel Flow

• Fuel is suctioned by the feed pump from the fuel tank and sent to the SCV. At this time, the regulating valve adjusts

the fuel pressure to below a certain level. Fuel sent to the feed pump has the required discharge quantity adjusted by

the SCV and enters the pumping mechanism through the check valve. The fuel pumped by the pumping mechanism

is pumped through the delivery valve to the rail.

Overflow Orifice

Regulating Valve

Delivery Valve

From Fuel Tank

To Tank

To Rail

Cam

SCV1

Check Valve 1

Check Valve 2

Head

SCV2

Feed Pump

Plunger

Q000832E

Operation Section

1-26

Fuel Discharge Quantity Control

• The diagram below shows that the suction starting timing (SCV (Suction Control Valve) ON) is constant (determined

by the pump speed) due to the crankshaft position sensor signal. For this reason, the fuel suction quantity is controlled

by changing the suction ending timing (SCV OFF). Hence, the suction quantity decreases when the SCV is turned

OFF early and the quantity increases when the SCV is turned OFF late.

• During the intake stroke, the plunger receives the fuel feed pressure and descends along the cam surface. When the

SCV turns OFF (suction end), the feed pressure on the plunger ends and the descent stops. Since the suction quantity

varies, when suction ends (except for maximum suction) the roller separates from the cam surface.

• When the drive shaft rotates and the cam peak rises and the roller comes in contact with the cam surface again, the

plunger is pressed by the cam and starts pumping. Since the suction quantity = the discharge quantity, the discharge

quantity is controlled by the timing with which the SCV is switched OFF (suction quantity).

Crankshaft

360 CR

Angle

TDC #1

TDC #3

TDC #4

TDC #2

Compression

Top Dead Center

Cylinder Recognition

Sensor Signal

0 2 4 6 8 10121416 0 2 4 6 8 101214

0 2 4

6 8 10121416 0 2 4 6 8 101214

Crankshaft Position

Sensor Signal

Increased Suction

Quantity

Suction

SCV 1

OFF

Suction

Decreased Suction

Suction

SCV 2

Quantity

OFF

Delivery Valve

Discharge

Horizontal

Cam Lift

Pumping

Suction

Pumping

Suction

Vertical

Cam Lift

Pumping

Suction

Pumping

Suction

Fuel

SCV

OFF

Check Valve

Fuel

Plunger

Delivery Valve

Roller

Suction

Pumping

Start of Suction

End of Suction

Start of Pumping End of Pumping

Q000833E

Operation Section

1-27

3.3 HP3 Type

(1) Construction and Characteristics

• The supply pump is primarily composed of the pump unit (eccentric cam, ring cam, two plungers), the SCV (suction

control valve), the fuel temperature sensor and the feed pump (trochoid type), and is actuated at 1/1 or 1/2 the engine

rotation.

• The two compact pump unit plungers are positioned symmetrically above and below on the outside of the ring cam.

• The fuel discharge quantity is controlled by the SCV, the same as for the HP2, in order to reduce the actuating load

and suppress the rise in fuel temperature. In addition, there are two types of HP3 SCV: the normally open type (the

suction valve opens when not energized) and the normally closed type (the suction valve is closed when not ener-

gized).

• With a DPNR system (Diesel Particulate NOx Reduction) system, there is also a flow damper. The purpose of this

flow damper is to automatically shut off the fuel if a leak occurs in the fuel addition valve passage within the DPNR.

Suction Valve

Plunger

Feed Pump

Ring Cam

SCV (Suction Control Valve)

Fuel Temperature Sensor

Delivery Valve

Q000835E

Operation Section

1-29

(3) Component Part Functions

Component Parts

Functions

Feed Pump

Draws fuel from the fuel tank and feeds it to the plunger.

Regulating Valve

Regulates the pressure of the fuel in the supply pump.

SCV (Suction Control Valve)

Controls the quantity of fuel that is fed to the plungers.

Pump Unit

Eccentric Cam

Actuates the ring cam.

Ring Cam

Actuates the plunger.

Plunger

Moves reciprocally to draw and compress fuel.

Delivery Valve

Prevents reverse flow from the rail of the fuel pumped from the plunger.

Fuel Temperature Sensor

Detects the fuel temperature.

Feed Pump

• The trochoid type feed pump, which is integrated in the supply pump, draws fuel from the fuel tank and feeds it to the

two plungers via the fuel filter and the SCV (Suction Control Valve). The drive shaft actuates the outer/inner rotors of

the feed pump, thus causing the rotors to start rotating. In accordance with the space that increases and decreases

with the movement of the outer and inner rotors, the feed pump draws fuel into the suction port and pumps fuel out

the discharge port.

Outer Rotor

To Pump Chamber

Suction Port

Discharge Port

Inner Rotor

From Fuel Tank

Q000770E

Regulating Valve

• The regulating valve keeps the fuel feed pressure (discharge pressure) below a certain level. If the pump speed in-

creases and the feed pressure exceeds the preset pressure of the regulating valve, the valve opens by overcoming

the spring force in order to return the fuel to the suction side.

Pump Housing

Bushing

Piston

Feed Pump

Spring

SCV

Plug

Q000837E

Operation Section

1-30

Suction Control Valve (SCV)

• In contrast to the HP2, the SCV for the HP3 supply pump is equipped with a linear solenoid valve. The fuel flow vol-

ume supplied to the high-pressure plunger is controlled by adjusting the engine ECU supplies power to the SCV (duty

ratio control). When current flows to the SCV, the internal armature moves according to the duty ratio. The armature

moves the needle valve, controlling the fuel flow volume according to the amount that the valve body fuel path is

blocked. Control is performed so that the supply pump suctions only the necessary fuel quantity to achieve the target

rail pressure. As a result, the supply pump actuation load is reduced.

• There are two types of HP3 SCV: the normally open type (the suction valve opens when not energized) and the nor-

mally closed type (the suction valve is closed when not energized). The operation of each type is the reverse of that

of the other.

• In recent years, a compact SCV has been developed. Compared to the conventional SCV, the position of the return

spring and needle valve in the compact SCV are reversed. For this reason, operation is also reversed.

Normally Open Type

- When the solenoid is not energized, the return spring pushes against the needle valve, completely opening the fuel

passage and supplying fuel to the plungers. (Total quantity suctioned → Total quantity discharged)

- When the solenoid is energized, the armature pushes the needle valve, which compresses the return spring and

closes the fuel passage. In contrast, the needle valve in the compact SCV is pulled upon, which compresses the

return spring and closes the fuel passage.

- The solenoid ON/OFF is actuated by duty ratio control. Fuel is supplied in an amount corresponding to the open

surface area of the passage, which depends on the duty ratio, and then is discharged by the plungers.

Return Spring

Solenoid

Conventional SCV

Valve Body

Needle Valve

External View

Cross Section

Q002340E

Compact SCV

Solenoid

Valve Body

Return Spring

Needle Valve

External View

Cross Section

Q002309E

Operation Section

1-31

Duty Ratio Control

- The engine ECU outputs sawtooth wave signals with a constant frequency. The value of the current is the effective

(average) value of these signals. As the effective value increases, the valve opening decreases, and as the effec-

tive value decreases, the valve opening increases.

Low Suction Quantity

High Suction Quantity

OFF

Average Current Difference

QD0710E

When the SCV Energized Duration (Duty ON Time) is Short

- When the SCV energization time is short, the average current flowing through the solenoid is small. As a result, the

needle valve is returned by spring force, creating a large valve opening. Subsequently, the fuel suction quantity

increases.

Conventional SCV

Feed Pump

SCV

Large Valve Needle

Opening

Valve

Q002341E

Operation Section

1-32

Compact SCV

Feed Pump

Large

Needle Valve

Opening

Q002321E

When the SCV Energized Duration (Duty ON Time) is Long

- When the energization time is long, the average current flowing to the solenoid is large. As a result, the needle

valve is pressed out (in the compact SCV, the needle valve is pulled), creating a small valve opening. Subsequently,

the fuel suction quantity decreases.

Conventional SCV

SCV

Feed Pump

Small

Needle

Opening

Valve

Q002342E

Operation Section

1-34

Normally Closed Type

- When the solenoid is energized, the needle valve is pressed upon (in the compact SCV, the cylinder is pulled upon)

by the armature, completely opening the fuel passage and supplying fuel to the plunger. (Total quantity suctioned

→ Total quantity discharged)

- When power is removed from the solenoid, the return spring presses the needle valve back to the original position,

closing the fuel passage.

- The solenoid ON/OFF is actuated by duty ratio control. Fuel is supplied in an amount corresponding to the open

surface area of the passage, which depends on the duty ratio, and then is discharged by the plungers.

Conventional SCV

Return Spring

Solenoid

Valve Body

Needle Valve

External View

Cross Section

Q002343E

Compact SCV

Valve Body

Solenoid

Return Spring

Needle Valve

External View

Cross Section

Q002323E

Duty Ratio Control

- The engine ECU outputs sawtooth wave signals with a constant frequency. The value of the current is the effective

(average) value of these signals. As the effective value increases, the valve opening increases, and as the effective

value decreases, the valve opening decreases.

High Suction Quantity

Low Suction Quantity

OFF

Average Current Difference

Q000844E

Operation Section

1-35

When the SCV Energized Duration (Duty ON Time) is Long

- When the energization time is long, the average current flowing to the solenoid is large. As a result, the needle

valve is pushed out (in the compact SCV, the needle valve is pulled), creating a large valve opening. Subsequently,

the fuel suction quantity increases.

Conventional SCV

Feed Pump

SCV

Needle

Large

Valve

Opening

Q002344E

Compact SCV

SCV

Feed Pump

Large Valve

Needle

Opening

Valve

Q002324 E

DENSO COMMON RAIL SYSTEM (CRS). SERVICE MANUAL (2007) - page 1