Components for Gasoline Direct Injection Systems - Denso

Powertrain Control
Components for Gasoline Direct Injection Systems
Afamiliar technology
in diesel engines, direct
injection is beginning to
appear in gasoline powertrains.
The technology requires
extremely sophisticated
engine management systems.
DENSO supplies a large and
growing line of products for
those systems.
Fuel return line
Fuel feed line
Fuel pressure sensor
Common rail
Fuel pressure relief valve
Fuel pump
High-pressure fuel line
High-pressure injector
■ Gasoline direct injection system
In the marketplace
Direct injection means injecting
the fuel directly into the cylinder
instead of premixing it with air in
separate intake ports. That allows
for controlling combustion and
emissions more precisely. But it
demands advanced engine
management technologies. Mitsubishi,
Toyota, and Nissan have introduced
direct injection engines for gasolinepowered
vehicles, and some
European automakers have introduced
gasoline direct injection engines
since 2000.
Electronic driver
unit (EDU)
10
The first commercial systems
employed constant fuel pressure,
but the industry is moving toward
variable-pressure systems. Similarly,
multiplunger designs are giving way
to simpler, single-plunger designs in
the high-pressure pumps. And
automakers are shifting to variablevolume
pumps, from constant-volume
models, to accommodate their
variable-pressure fuel systems.
Each automaker adopts unique
spray characteristics in their highpressure
injectors to accommodate the
combustion concept of their engines.
Injectors that form a cone-shaped
High-pressure fuel pump
Engine electronic
control unit (ECU)

spray are most common, though
Toyota has begun using a fan-shaped
spray.
We began limited production of
components for gasoline direct
injection engines in 1996 and have
been mass-producing them since 1997.
In 2000, we supplied components for
about 120,000 gasoline direct injection
engines. We strengthened our product
line during the year by introducing
lighter-weight, higher-performance
components.
Injector
High-pressure pump
Nozzle
configuration
Spray
■ High-pressure injection
Slit nozzle
Front view Side view
In comparison with
competitors
The low drive torque in our highpressure
pumps is significantly lower
than in competing products. And the
single-plunger design makes the
pumps smaller and less expensive
than multiplunger models.
Our slit nozzles produce the first
fan-shaped spray in the automobile
industry. And our experience in
mass-producing both slit and swirler
nozzles equips us to satisfy a full
range of automakers’ needs.
Combining components in hybrid
ICs has simplified and reduced the
size of our electronic driver units for
injectors. Our units are about 40%
lighter than competing products.
Electronic driver unit
11
Swirler nozzle
Fan-shaped Cone-shaped
Issues and outlook
Gasoline direct injection can help
reduce the environmental impact of
internal combustion power. By 2005,
we expect more than 20% of the
gasoline-powered new vehicles sold
in Japan to have direct injection.
Reducing cost is a pressing issue in
making direct injection available in a
broadened range of vehicle models.
We will cultivate economies of scale
by standardizing component designs
and installation methods for different
engines.
Technical highlights
Our common rail circuits allow for
controlling the fuel-delivery amount
to generate the fuel pressure required
by the engine. Electronic control
adjusts the amount of fuel delivery
with reference to a fuel pressure
sensor in the common rail.
We use a single-plunger design in
our high-pressure injection pumps to
provide high volumetric efficiency at
low drive torque and at low cost. Our
pumps have a built-in electromagnetic
control valve, and the control function
varies the fuel-delivery amount by
adjusting the timing of the drive
pulses sent to the valve. The drive
torque and pulsation inside the highpressure
lines are minimal, since our
pumps supply only as much fuel as
the engine actually requires.
Our high-pressure injectors are
available with different nozzles for
different spray configurations. We
offer a swirler nozzle to produce a
cone-shaped spray and a slit nozzle
for a fan-shaped spray. Ultraprecise
machining helps ensure a fine, highquality
spray. We optimize injector
performance with electronic driver
units that incorporate original ICs.