CHAPTER 13.7Exhaust Gas Re-Circulation Valve

EGR Cooler

• E – Exhaust • G – Gas• R – Recirculation

The ABC’s OfExhaust Gas Recirculation (EGR)

OVERVIEW

In general, the higher the engine temperature, the more efficient the engine.

Which results in:

1) Good Performance

2) Good Fuel Economy

The ABC’s OfExhaust Gas Recirculation (EGR)

When peak temperatures are high enough for long

enough periods of time, the nitrogen and oxygen in the

air combine to form new compounds, primarily NO and

NO2. These are normally referred to collectively as

“NOx – Nitrogen Oxide”

The ABC’s OfExhaust Gas Recirculation (EGR)

• Too much NOx in the atmosphere contributes

to the production of smog.• In October of 2002, new NOx standards required the

diesel engine industry to introduce additional

technology to meet the new standards.• EGR COOLER

The ABC’s OfExhaust Gas Recirculation (EGR)

How Can NOx Be Reduced?

• Since high cylinder temperatures cause

NOx, NOx can be reduced by lowering

cylinder temperatures. Charge air coolers

are already commonly used for this

reason.

• Reducing the amount of oxygen in the

cylinder, inhibits the combustion process

How Can NOx Be Reduced?

• The best way to reduce NOx is to limit the

amount of oxygen in the cylinder. Which

results in lower cylinder temperatures.

• This is done by recirculation of exhaust

gas (EGR) into the cylinder.

• This technique lowers cylinder

temperature, reducing NOx, But it also

reduces fuel economy and performance,

and creates excess soot.

The ABC’s OfExhaust Gas Recirculation (EGR)

• When EGR is required, the engine’s electronic controls open the EGR valve.

• Turbocharger & EGR Valve (1)

1

Exhaust Gas Recirculation (EGR)

• The exhaust gases flow through this pipe to the EGR cooler. (2)

2

The ABC’s OfExhaust Gas Recirculation (EGR)

• The exhaust gases are cooled by water from the engine cooling system. (3)

3

The ABC’s OfExhaust Gas Recirculation (EGR)

• The cooled exhaust gases

then flow through the EGR

transfer pipe into the

intake manifold. (4)

• Which then lowers the

cylinder temperature

• Results in lower NOx

production.

4

4

Intake Manifold

Regeneration SystemWhat is its job ?

• The system's job is to capture and burn off

(regenerate) the particulate matter (soot) in the

engine exhaust gas .

• It does this using a Diesel Oxidation Catalyst (DOC)

and a Diesel Particulate Filter (DPF). By monitoring

exhaust gas temperature and system back pressure,

Detroit Diesel Electronic Control determines when

and how additional help is needed to ensure

complete regeneration of the soot captured in the

DPF.

Types of Regeneration

• There are two types of Regeneration ?

1. Active

2. Stationary.

Types of Regeneration

1. Active Regeneration • During normal driving the Intake Throttle is

electronically actuated to help increase the

After treatment System temperature while the

unit is running.

• The Dosing Valve injects a mist of diesel fuel

into the exhaust system to further increase the

After treatment System temperature until

satisfactory regeneration is complete.

Types of Regeneration

2. Stationary Regeneration

• Depending on engine duty or application, the

Detroit Diesel Electronic Control (DDEC) may

notify the driver that stationary regeneration is

necessary.

• After the driver begins the manual activation of

the regeneration process, the RPM’s go up to

1650 (High Idle is 1400 RPM’s)

• Regeneration take about 20-30 minutes.

Stationary Regeneration Manual Activation

Manual Regeneration Switches

Regen Request

Regen Inhibit

Regeneration Manual Switch Position

Regen Switch UP

Hold Regen Request Switch up for 5 – 10 sec.

Regeneration Location

Regeneration Valve

Regeneration Trouble Shooting

References

• Detroit Diesel Engine Manual

• www.detroitdiesel.com

• Firefighter Chris Adams

Station 13C