e poi e preso pari pari dalla produzione gm....bleah!!!
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deriva direttamente dal 1.6 twin port e rispetto al 1.8 gen 2 ne riprende buona parte delle misure interne tanto che le modifiche paiono minime , alleggerimento pistoni,(220 g contro 230g) aumento del piston pin(18mm a 19mm) aumento alzata valvole, nuovi profili degli alberi a camme e alleggerimento basamento, il tutto pesa 118 kg contro i 121 kg del vecchio , ma sopratutto la parte innovativa è il doppio variatore di fase dcvcp. Intervento del gruppo fiat?
Difficile stabilirlo dato che anche in documenti dettagliati non viene citata:
1 Introduction
The new 1.8 l engine is based on the 1.6 l
Twinport engine presented by Opel in 2003,
that offers an excellent cost-benefit ratio to
customers through its innovative high exhaust
gas recirculation (EGR) concept [1].
With the new 1.8 l engine variant, this customer
advantage was expanded to include
an improved power characteristic. Thus excellent
power performances combined
with reduced fuel consumption were the
top priorities of the product development
program.
With a power output of 57 kW/l, the engine
occupies a top position in this displacement
segment. Furthermore, it was
possible to offer 90 % of the maximum
torque in a broad range of 2200-6200 rpm.
The specific fuel consumption at the standard
2000 rpm/2 bar was reduced to 364
g/kWh.
The development targets were mainly
reached by optimizing the charge cycle using
of two continuously variable cam
phasers (DCVCP), a new design of the combustion
system, the cam profiles and the
complete intake and exhaust system.
The modular system of the engine family
permitted the adaptation of the cam
phasers without affecting the basic structure
of the engine. The main dimensions of
the 1.8 l engine were maintained from the
previous generation and thus all variants
of this engine family are produced on a
modified manufacturing system in the existing
engine plant, Table 1. In the future,
the engine will be offered in many applications
of Opel. In less than 30 months, from
the first concept engine to start of production,
the engine concept could be realized
and the development targets could be safely
reached by using state-of-the-art simulation,
test rig and rapid prototyping technology.
By Gunnar Böhler,
Uwe Dieter Grebe,
Torsten Löhnert,
Manfred Pöpperl and
Klaus Steffens
Der neue 1,8-l-Vierzylinder-Ottomotor
für Opel-Automobile
You will find the figures mentioned in this article in the German issue on page 242.
The New 1.8 l
Four-Cylinder
Spark Ignition Engine
for Opel Automobiles
2 Development Targets
The new 1.8 l engine was improved in all
relevant criteria compared to the previous
model. The most important development
targets have been summarized as follows:
increase of the brake mean effective
pressure in the entire speed range
fuel consumption reduction in the
MVEG cycle by 4 %
fuel consumption reduction in customer
use more than 4 %
emission limits according to Euro 4, potential
for Euro 5
total engine weight less than 120kg (DIN
70020)
maintaining the main geometric dimensions
low noise emissions
running smoothness
potential for further development.
3 Concept Definition
For the gasoline engines from Opel, the applicable
technology is carefully selected
based upon the displacement and the vehicle
segment, Figure 1.
While the reduction of the fuel consumption
was clearly the top development
priority for the 1.6 l Twinport engine, the
optimization of the full-load behaviour was
added as another development focus for
the new 1.8 l engine.
The largest potential solutions to fulfil
these complex requirements are through
the use of the DCVCP concept and/or the
gasoline direct injection. Due to the more
favourable cost-benefit ratio, the DCVCP
concept was selected for this price-sensitive
market segment.
4 Design
The design concept of the new 1.8 l engine,
Figure 2, is based on the 1.6 l Twinport engine.
New subsystems as cam phasers, an
oil-water heat exchanger, piston spray
nozzles, an intake manifold with variable
runner length, a new exhaust manifold as
well as a standardized oil pan module were
integrated. The base engine was adjusted
to higher load.
Within the virtual development process,
all components were optimized to the required
package, the structural strength, the
vibration behaviour and the thermal behaviour.
The layout of the subsystems and the
entire engine system were executed before
the prototype phase based on a complex calculation
of the charge cycle and a detailed
flow simulation. The number of prototypes
and development phases were clearly reduced
through the use of these tools.
4.1 Cylinder Block
The cylinder block is based on the proven
hollow-frame concept of Generation 3. On
the exhaust side, the oil cooler was installed,
in the area of the main oil gallery
the piston spray nozzles and in the front
area the direct VCP oil supply.
In connection with the block development,
in spite of the increased loads, the
weight was reduced by 20 % compared to
the 1.8 l engine of the second generation,
COVER STORY 1.8 l Four-Cylinder Spark Ignition Engine
Engine Type 1,8 l 4V 1,8 l 4V
Generation 2 Generation 3
Displacement cm3 1796
Bore distance mm 86
Bore mm 80.5
Stroke mm 88.2
Stroke-bore ratio 1,1
Conrod length mm 129,75
Conrod mass g 440 421
Stroke / conrod ratio 0,314
Crankshaft bearing – diameter/width mm 43 / 17
Main bearing – diam/width mm 55 / 19
Piston pin diameter mm 18 19
Piston mass g 230 220
Inlet valve diameter mm 31,2
Exhaust valve diameter mm 27,5
Valve stroke, inlet / exhaust mm/mm 8,5 / 8 9,0 / 8,5
Cam phasing inlet / exhaust °CA fixed 60/45
Compression ratio 10,5
Rated torque at engine speed Nm 165 -170* 175
min-1 3800/4600* 3800
Rated power at engine speed kW 90-92* 103
min-1 6000 6300
Engine management Siemens Siemens
Simtec 71 Simtec 75
Fuel quality RON 91/ 95 / 98
Exhaust gas aftertreatment Close-coupled three-way catalyst
Emission standards EU IV
Engine mass (DIN 70020) kg 121 118
* depending upon the vehicle application
1 Introduction
Table1: Technical data of the 1.8 l engines
4 Design
Figure 2: Total engine view
4
and at the same time the stiffness of the engine-
and-transmission unit was optimized.
The grey cast iron block, at only 27 kg including
the bearing cap, will form the basis
of all future high-performance variants of
the Family 1 engine.
4.2 Crankshaft Drive
When designing the cranktrain components,
the focus was set on increasing the
strength. These requirements were met by
a new crankshaft design, a modified steel
conrod with floating piston pin bearing
and a new piston design. In spite of these
stiffening measures, the oscillating masses
were maintained. Piston cooling compensates
the high temperature profile that is
the result of the increased engine performance
and the geometry of the new lightweight
piston.
Regarding the cast crankshaft, a weight
saving of 6 % was reached, while the very
good bending qualities and the torsional
stiffness of the second generation are
maintained. The degree of balancing of the
rotating mass was improved by 60 %.
For the new 1.8 l engine, a new designed
crankshaft sensor system is used for the
first time. The anisotropic magnetoresistive
sensor (AMR) is integrated into a plastic
carrier and as a module it is pressed into
the cylinder block together with the crankshaft
seal made of PTFE. The corresponding
magnetized sensor disk is mounted between
the crankshaft and the flywheel.
The entire weight saving concerning the
cranktrain is 0.8 kg while maintaining the
mass moment of inertia.
4.3 Cylinder Head
When designing the cylinder head, special
attention was dedicated to the structural
strength and the cooling. The inlet and exhaust
port geometry was dimensioned by
simulating the charge cycle and the flow.
The new front camshaft bearing bridge
contains the control valves and the bores
for the cam phasers oil supply. In addition,
it provides the basis of the thrust bearing.
Due to adujusting the cylinder head cover
with the integrated oil separator the
bearing bridge contour, the sealing efficiency
could be improved.
4.4 Valve Train
Here, the friction-reducing concept of the
mechanical tappets with mass reduced
valves and springs was taken over from the
1.6 l of the third generation design. The hollow
cast camshafts were adjusted to the oil
supply of the phasers and the location of
the position sensors. The charge cycle calculation
provided the data to optimize the
cam profile and the valve lift.
4.5 Cam Drive and Cam Phasing
Maintaining the layout of the belt drive
and the toothed belt dimensions, the automatic
belt tensioner was adjusted to the increased
moments of inertia. The toothed
belt change interval of 150.000 km was
maintained.
The new 1.8 l engine is the first in the
market using a vane-type cam phaser out
of a thin-wall forming process. Low weight,
minimum space requirements and a wide
phasing authority characterize this concept.
The camshafts can be phased at the
inlet side by 60°CA and at the exhaust side
by 45 °CA, Figure 3.
Using de-throttling measures in the oil
circuit, additional software functions and
an optimized phasing and locking strategy,
the camshafts can be adjusted at ambient
temperatures up to -30 °C.
4.6 Oil Circuit
The large number of vehicle applications
required a new design of the oil pan. It was
achieved to develop a common die cast design
for all applications. Special attention
was dedicated to the dynamic behaviour of
the oil volume. The precasted oil suction
channel in connection with the plastic oil
scraper, which also covers the suction point
in the oil pan, provides an economic solution
as well as an optimum solution from
the functional point of view. According to
the requirements of the Vehicle Platforms,
it is possible to install different sensors.
The front-end module including the integrated
oil and water pumps as well as the
toothed belt protection and the fastening
points of the accessories is in principle carried
over from the 1.6 l Twinport engine.
The flow volume of the oil pump, however,
had to be optimized due to the additional
oil requirements for piston cooling and cam
phaser purposes. To improve the oil pressure
behaviour in the cylinder head, pressure
control is now performed indirectly.
The increased thermal load of the oil required
the integration of an oil-water heat
exchanger. This new module, consisting of
heat exchanger and oil filter, included an
additional water by-pass tube. It is part of
the engine inherent water circuit.
The module was integrated under space
saving considerations at the exhaust side of
the cylinder block. The weight is only 1.1 kg,
Figure 4. This design ensures a maximum
intercooling of the oil and a minimum loss
of pressure. During the cold-start phase,
however, this measure allows a faster heating
of the engine oil and an early reduction
of the internal engine friction.
The cam phasers are supplied with oil
through separate bores in the cylinder
block and head. The recirculation of the increased
amount of oil in the cylinder head
is permitted through additional pre-cast oil
return channels.
4.7 Water Circuit and Thermal
Management
The cooling principle of the parallel flowthrough
known from Generation 3 was
kept. Redesigning the water jackets of
cylinder head and block regarding water
distribution and fluid dynamics, improved
the heat transfer significantly, Figure 5.
The additional water supply of the oil
cooler, parallel to the water circuit of the
engine, was designed by extensive CFD
simulations so that a minimum of water is
needed to achieve maximum oil cooling.
The new thermostat housing is executed
as a weight reduced plastic construction.
All vehicle-related interfaces of the cooling
circuit are identical for all generation 3 engines.
By increasing the cooling water temperature
in the part-load range, thermal management
contributes to a minimization of
customer fuel consumption by reducing
the frictional mean effective pressure and
the wall-heat losses.
4.8 Intake Manifold Module
Out of an intensive concept study, a twostep
intake manifold with a rotary sleeveswitching
device was selected. The lateral
position of the throttle valve permits an optimum
port formation of the single manifold
runners in connection with a reduction
of the losses in the fresh air section from
the air filter to the intake valve, Figure 6.
The cross-section of the runner is constant
over the entire length. The manifold
length in the power mode is 40 % of the
torque mode. In order to minimize the flow
resistance at high speeds, a rotary sleeve
was used instead of a flap-switching device.
This solution guarantees the maximum
possible cross-sectional area in the
open position. Another advantage of the
rotary sleeve design is that a high tightness
can be reached in the closed position.
4.9 Exhaust Manifold
The four-into-one exhaust manifold was
performed as a deep-draw design with a
close-coupled catalyst. A reduced exhaust
gas backpressure and an optimization of
the exhaust emissions were achieved
through an even distribution of the exhaust
gas when flowing into the catalyst
and an even flow of the lambda sensor.
4.10 Engine Management
System
Corresponding to the new requirements of
the camshaft phasing and the thermal
COVER STORY 1.8 l Four-Cylinder Spark Ignition Engine
management, the Engine Management
System was modified in the form of a higher
computing power and additional sensors.
The layout of the engine-mounted PCB
control unit was redesigned in order to
make allowance for the different vehicle
applications and for future extensions of
functions.
5 Strategy Camshaft Phasing
5.1 Internal Residual Gas as a
Result of Camshaft Phasing
In addition to an improvement of the fullload
behaviour, camshaft phasing offers a
considerable potential to minimize the fuel
consumption by allowing internal exhaust
gas recirculation and the associated reduction
of the engine’s pumping losses.
By a controlled camshaft phasing, the
internal residual gas is recirculated in three
different ways into the combustion chamber:
inlet port recirculation
exhaust port recirculation
combustion chamber recirculation.
Which of the three ways is the optimum depends
on the set load point. In Figure 7 the
simulation result is represented for the partload
point bmep=2 bar, n=2000 rpm [2].
5.2 Phasing Strategy in the
Engine Map
Based on the simulation, the subsequent optimization
on the engine test stand and in
the vehicle, the strategies for the individual
map areas were calibrated according to the
criteria: fuel consumption, emission, driveability
and full-load behaviour, Figure 8. The
engine related results are represented in sections
6.2 and 6.3, Part Load and Full Load.
6 Development Results
6.1 Combustion /
Thermodynamics
The combustion system was designed for
the fuel qualities RON 91 to 98, in order to
ensure a worldwide use of the powertrain
without major modifications. According to
a corresponding study, the optimum compression
ratio is 10.5: 1.
The combustion system was developed
with the systems AVL Visioknock and Visioflame
regarding the combustion initiation,
the course of combustion and the antiknock
properties.
As an example Figure 9 illustrates the
ignition phase, i.e. the flame propagation a
short time after the ignition and the local
distribution of the knock-event probability
during a knocking combustion at full load.
Due to the adaption of the charge motion
and the cylinder-head cooling, a optimized
combustion can be reached that
avoids the formation of local areas with a
high number of knock events.
The even spatial distribution of the
knock-event probability with local peaks
documents the optimum design of the system
from a combustion point of view.
The quality of the combustion system is
confirmed by the analysis of the 50 %-Mass
fraction burned at full load, Figure 10.
The influence of the rotary sleeve position
of the variable intake manifold onto
the charge motion and thus onto the combustion
process is demonstrated in the area
of the switching point at n = 4200/min. The
reduced volumetric efficiency in the power
mode is compensated by an almost optimum
position of the 50 %-Mass fraction
burned. At higher speed the 50 %-Mass fraction
burned can, given a high volumetric
efficiency, be maintained around the optimum.
6.2 Part Load
Due to the application of intake and exhaust
cam phasers and the option of another
variable by positioning the manifold
rotary sleeve in torque or optimum position,
the total system became more complex.
The system was optimized through a
process simulation and corresponding experiments.
Parameter variations on the
test stand were considerably reduced by a
pre-selection of optima from the simula-
COVER STORY 1.8 l Four-Cylinder Spark Ignition Engine
7 Vehicle Application
Table 2: Technical data of a vehicle from the D-segment
Vehicle-Segment D-Segment
Vehicle curb weight kg 1300 1320
Acc. to 70/156/EEC
Engine 1.8 l Gen.2 1.8 l Gen.3
Transmission 5th speed
Transmission ratio
1st / 2nd / 3rd / 4th / 5th speed 3,727 /
2,136 /
1,414 /
1,121 /
0,892
Axle ratio 3.737
Tires 195 / 65 R15
Top speed km/h 205 213
Acceleration
0-100 km/h s 11.2 10.5
Fuel consumption acc. to
99/100/EEC
Total l/100km 7.6 7.3
CO2 emission g/km 182 175
tion by means of Design of Experiments
and an automatically performed test series.
Compared to a system with constant
cam timing, a potential fuel saving of up to
5 % is developed in the consumption map
with the use of continuously variable times
at the intake and exhaust sides.
By fine-tuning the parameters, a specific
fuel consumption figure of 364 g/kWh
was achieved for the representative partload
standard point (bmep = 26 bar / 2000
rpm), Figure 11.
6.3 Full Load
One of the main development targets was
the demonstration of a peak position concerning
the specific torque and power values
and to ensure the possibility of extension.
In the development process, the simulation
of the charge cycle essentially contributed
to the new design of the charge cycle
components and their harmonization
with the fully variable cam phasers in the
intake and exhaust tracks.
By using cam phasers, it was possible to
optimize the cam profile for filling at low
and medium speed ranges. This measure
would lead to a reduced volumetric efficiency
at higher engine speeds, but due to
the very good dynamic properties of the
two-step intake manifold, this consequence
is compensated.
6
The geometry of the four-into-one exhaust manifold with
close-coupled catalyst was adjusted by detail optimization to
the variable charge cycle components at the intake side.
Comparing the present engine to the previous one, the volumetric
efficiency was increased in the lower and medium speed
range by up to 11 % and up to 15 % at maximum speed. Special
attention may be dedicated to the almost constant course of
volumetric efficiency at high speeds, which demonstrates potential
for further power optimization, Figure 10.
The maximum torque (175 Nm/3800 rpm) and the maximum
power (103 kW/ 6300 rpm) could be increased by 6 or 14 % respectively.
Thus, an excellent weight-to-power ratio of 1.14
kg/kW was achieved.
The implemented measures for full load optimization ensure
a top position among comparable competitor’s engines, Figure
12.
7 Vehicle Application
In a direct vehicle comparison, better driving performances and
a reduced fuel consumption can be offered to the customer.
Table 2 shows an example of a comparison between the 1.8 l engine
Generation 2 and 3 in a vehicle of the D-segment.
8 Summary
The new 1.8 l engine was reengineered in all relevant areas. The
current version sets a standard for power range and customer
fuel consumption. At the same time, it offers the potential to
meet future demands of the market as well as legal requirements.
The lambda-1 concept permits the application of conventional
emission treatment methods and the use of several
fuels worldwide. The engine perfectly fits the modular concept
of the mid-size engine family, which reduces the processing and
assembly work accordingly and offers the necessary flexibility
in view of future developments.
su quello hai ragione. ma il problema può essere risolto dalla casa stessa,basta diffondere le immagini il giorno stabilito ,non capisco perchè devono essere fornite in anticipo.