Technical Paper

Development of ecot3 for Tier 3 Engine (2)Masayuki Yoshitomi
Hideo Oguri

The ecot3 engines were developed to meet Tier 3 emission regulations and introduced into the market as
Komatsu engine series. Not only the emission regulations but also the low noise and fuel economy areother important propositions, and the ecot3 engine family has been launched as an ecological powersource as its name indicates. Medium and Large ecot3 engines were introduced in last Technology Report.
The background of the development and technical features are described below.
Key Words: Diesel engine, environmental friendliness, Tier 3, electronic control, common rail system

1. Introduction
The starting time for the enforcement and regulatory values themselves differ slightly for the output range of 56 to225kW, covering the SAA4(6)D107 and SAA6D114 engines,
and based on the actual output figure. Regulation on engines
in output ranges exceeding 130kW was enforced from 2006,
whereas from 2007, regulation has been successively enforced on engines of less than 130kW in output, in accordance with the output range.
Compared with the Tier2 regulation, the Tier3 regulation
sets the same regulatory value for particulate matter (PM)while that for nitrogen oxide (NOx) is set 40% lower. The
focus of the development was, therefore, compliance withthe stringent NOx regulatory value without causing the fueleconomy or PM emission level to deteriorate.

The overview and technical features of the Medium andLarge ecot3 engines were introduced in the previous Technology Report No. 157. The features of the small ecot3 engine covering the output range of 75kW to 225kW are described.
This paper describes the SAA6(4)D107 and SAA6D114
engines that meet the Tier3 emission regulations. However,
the technologies implemented in them differ slightly fromthose incorporated in medium and large engines. One
prominent difference is that Tier3 emission regulations are
met without the use of cooled EGR technology, which represented a considerable challenge. However, compliancewith the Tier3 emission regulation while maintaining theprevious fuel consumption level was enabled via the use ofan electronically controlled high pressure common rail andthrough the optimization of combustion technology.
From mid-2005 onwards, mass production of these engines started, initially for the PC200-8 and PC300-7E0, andthe products have been critically acclaimed by the market.
The SAA4(6)D107 and SAA6D114 engines that meet theTier3 emission regulation are described below.

3. Small Engine Series of ecot3 (ecology &economy - technology3)
3.1 Overview
Komatsu is currently developing, manufacturing and selling industrial diesel engines ranging from 3.3L to 78L. As
mentioned earlier, new emission regulations have been andwill be enforced in 2006 and 2007 in Japan, the United Statesand Europe. Among the family engines meeting these regulations and with capacities ranging from 3.3L to 23.2L and an
output of less than 560kW, the medium to small-sized ecot3
engines with displacement capacities of 4.5, 6.7 and 8.3L
respectively are described.
Figure 1 shows the displacements and outputs of the ecot3
engine series. Among the engines in this series, the displacements of the 4.5L SAA4(6)D107 and 6.7L SAA6D107

2. Trends of Emission Regulations for Construction Machinery Engines
The so-called Tier3 regulations, mainly in force in North
America and Europe, as well as on/off road Tier-3 emission
regulations for specified construction machinery in Japan
comprise emission regulations governing diesel engines forconstruction machinery.

2006 ② VOL. 52 NO.158

Development of ecot3 for Tier 3 Engine (2)― 1 ―pressure injection system, which implemented new improvements such as short injection time, micro fuel atomization via high pressure injection and improved combustion
during the final stage of combustion by the multi-stage injection of fuel.

engines have been increased about 14% compared with theexisting 3.9 and 5.9L by increasing the bore and stroke basedon the previous 102mm bore engine, allowing the engines tobe run with a leeway. By installing the new engines in someof the vehicles that previously installed the 114 Engine, thecost of vehicles has been reduced. The increase in displacement has been achieved by changing the liner part of thecylinder block to a Siamese structure while maintaining thesame cylinder pitch as in the 102 Engine. Consequently, theexternal dimensions of the cylinder block are as before, forestalling any impact on the machine body at the engine replacement from the 102 engine.

3.2 Aims for the development of ecot3 engine series
1) Compliance with all Tier3 emission regulations of Japan,
the United States and Europe
2) Equivalent or superior engine performance (in terms of
output and fuel economy) to existing machines
3) Reduced noise to meet EU noise regulations and the domestic super low noise regulations concerning construction machinery
4) Reliability and durability as industrial engines for construction and other forms of machinery.
5) Multi-purpose universality of Tier2 engines to endure use
in diverse global environments.
The principal specification list of the small ecot3 engines
is presented in Fig. 3, where an electronically controlled highpressure common rail system is adopted in place of the mechanically controlled fuel injection pump used up to theTier2 regulation era, in order to meet the development aims.
The number of intake and exhaust valves per cylinder has
been increased from the previous two valves per cylinder tofour, to boost the intake air volume. The injector is placed in
the center of each cylinder to ensure uniform fuel atomization in the combustion chambers and achieve the targetedemission performance.

23.2L
15.2L
11.0L
8.3L

Small ecot3
output range

6.7L
4.5L
3.3L
0

100

200

300

400

500

600
kW

Fig. 1 Komatsu ecot3 engine series

Figure 2 summarizes the trends of the technologies incorporated in the engines to meet the Tier1, Tier2 and now
Tier3 emission regulations.
The combustion temperature inside the cylinders must be
lowered to curb the oxidation of nitrogen and thus reduce thegeneration of nitrogen oxide (NOx). As one means ofachieving this, changes have been made from supercharging
engines (S) to engines with a water-cooled aftercooler (SA)and those with an air-to-air air-cooled aftercooler (SAA) tolower the charge temperature before combustion. All theengines in the ecot3 SAA4(6)D107 and SAA6D114 engine
series are of the air-cooled aftercooler specification.

Tier2
Tier3
Engine Model
SAA4D102 SAA6D102 SAA6D114 SAA4D107 SAA6D107 SAA6D114
Number of Cylinder
4
6
6
4
6
6
Bore×Stroke (mm) 102×120 102×120 114×135 107×124 107×124 114×135
Displacement (ltr)
3.92
5.88
8.27
4.46
6.69
8.27
Turbocharged Air-Cooled Aftercooler Turbocharged Air-Cooled Aftercooler
Aspiration
Conventional Mechanical Pump
Common Rail System
Fuel System
MechanicalElectronic
Engine Control
2 valves per cylinder
4 valves per cylinder
Valve per Cylinder

0.8
Emission Regulations for
U.S. EPA (130KW - 225KW)

0.7
P M [g/ KWh ]0.6

Fig. 3 Principal specification of the small ecot3 engine series
and the technologies incorporated in the series

Tier1

0.5

・Common Rail System
Multiple Injec tion・High Injec tion Pre ssure
・4 Valves per Cylin der

0.4
0.3

Tier3

0.2

Figure 4 shows a full view of the SAA6D107 engine installed on the PC200-8, the flagship Komatsu vehicle.

・ Air to Air Coole r
・ In jection Timing Retard
・ High Injection Pressure

Tier2

Compliant with the next-tieremission regulations

0.1
0
0

1

2

3

4

5

6

7

8

9

10

11

12

NOx+NMHC [g/KWh]

Fig. 2 Overview of technologies incorporated
to reduce emissions

The 40% reduction in nitrogen oxide required by the Tier3
emission regulation as part of Tier3 regulation proposals was
accomplished by reviewing the combustion concept, optimizing injection time and incorporating combustion improvement technology through multiple-mode injection. The
reduction of particulate matter (PM) was accomplished by
the use of the electronically controlled common rail high2006 ② VOL. 52 NO.158

SAA6D107 engines

Fig. 4 ecot3 series SAA6D107E-1 engine

Development of ecot3 for Tier 3 Engine (2)― 2 ―4. ecot3 Engine Technology

Figure 6 shows a full view of the fuel injector. The solenoid in the upper part of the injector opens and closes a
2-way valve on the push rod instantaneously and varies theinjection by changing the balance of fuel pressure, to facilitate multi-mode injection. The 107 and 114 Engines use thesame injector manufactured by Bosch, which has been
proven fully viable in terms of quality as a fuel injection partfor use in construction machines, and with a stringent operating environment, after verifying the resistance to dust andother parameters.

Using a newly developed engine that meets the Tier3
emission regulations, the ecot3 technology meets the mostrecent global gas emission regulations, yet guarantees engine
performance (in terms of output and fuel consumption), reliability and durability equivalent or superior to those of existing models and drastically reducing noise compared withthe conventional engines, as reported below.

4.1 Electronic control system
As mentioned earlier, the new ecot3 engine series comeswith an electronically controlled common rail injection system and uses a common electronic control system for the fullrange of engines, from large to small. To perfect this common electronic control system, quality verification was performed for a total of 100,000 hours to ensure durability andreliability that would fully meet customer expectations.
In the area of functions, the system controls the engine,
including the common rail injection system, as well as datainterchanges with the VCM (vehicular computer) throughhigh-speed CAN communications. The system also provides
interfaces that interact with the KOMTRAX system.

4.2 Heavy duty common rail injection system
Fig. 6 Full view of injector

All the engine families of the ecot3 engine series comewith an electronically controlled common rail injection system. The fuel injection system for small models is a systemmanufactured by Bosch, which has proven to be globally
viable. The fuel supply pump of the SAA6D114 engine in
the system is manufactured by Cummings.
The common rail injection system features not only
high-pressure injection, but also a high degree of freedom interms of injection time and multi-mode injection, reputedly
having the best potential of all the various injection systems.
Komatsu was the pioneer in mounting a common rail fuelinjection system in high-speed diesel engines for its medium
and large construction machines already in conformancewith Tier2 emission regulation. Komatsu also establishedengine performance at the same time through experience,achieving both low emissions and high performance. Figure
5 shows the schematic diagram of the new heavy duty common rail system adopted in the Komatsu engines.

Injection Rate

Figure 7 is a schematic diagram of multi-mode injectionused in small ecot3.
(1) The pilot injection curbs rapid heat generation via themain injection, thereby suppressing NOx generation. The
pilot injection is also effective in reducing combustion
noise.
(2) In regions of high output and high speed, post injection isadded to accelerate the oxidation of soot in the final stageof combustion, reducing the generation of smoke andPM.
Main injection
Pilot injection

Post injection

Time

Fig. 7 Schematic diagram of multi-mode injection

Figure 8 shows a full view model of a fuel supply pumpfor the SAA4(6)D107 engines manufactured by Bosch.
Many such pumps have been produced for truck engines inbulk production. The pump is lightweight and compact, due
to the fuel lubrication and needs no pipe for lubricating oil.
The exterior design, meanwhile, is simple and suitable forsmall engines. This pump is set to 1.33 times the engine rotation speed and includes three plungers that feed the pressurized fuell. This common rail system can generate up to
1600bar in maximum injection pressure.

Fig. 5 Common rail fuel injection system

2006 ② VOL. 52 NO.158

Development of ecot3 for Tier 3 Engine (2)― 3 ―EGR. The development was undertaken based on the following two points as the main concepts:

Fuel inlet
Fuel return
HP outlet

HPCR injector
Low NOx and low PM accomplishedsimultaneously through pilot andpost-injection

Optimum swirl
Optimization of mixing of fuelatomization and air - Low PM

Center protrusion of combustion chamber lowered
Entrainment of air atomization
accelerated - PM reduced

Fuel metering unit

Gear pump

DSA (Deep spray angle)
Diffusion combustion curbed by moving
atomization along the bottom of the
combustion chamber - Low NOx

Fig. 8 Fuel supply pump for the 107 Engine

On the other hand, the fuel supply pump for the
SAA6D114 engine is of a tandem in-line plunger type,oil-lubricated, and places more emphasis on reliability. A fullview of it is shown in Fig. 9.
All the pumps have been perfected by subjecting them toquality verification against various test codes required foruse in construction machinery, based on experience achievedin meeting the Tier2 emission regulations. Modifications
have been made to every detail and a system well deservingof the title heavy duty specification has been completed.

Fig. 10 Concepts of Ecot3 combustion(1) The relationship between the shape of the piston combustion chamber and fuel spraying is optimized to curb
the generation of thermal NOx increased by high temperature, by curbing, in turn, the rapid combustion during
the initial stage of fuel injection.
(2) To design a combustion chamber so that active combustion takes place in the final stage of combustion to accelerate the oxidation of soot, and curb emissions of PM andsmoke.

EFC actuator
housingHigh pressure
pump head

To implement the foregoing combustion concepts, simulation calculations by KIVA and bench performance tests wererepeated to optimize the layout between the shape of thepiston combustion chamber and the diameter of the fuelspraying hole, and satisfactory emission and general performance was achieved.
Figure 11 shows the results of the analysis of the KIVA
combustion simulation.

High pressure
outlet fitting

EFC actuator

Cam housing

Chamfering of combustion chamber rims
Prevents fuel vapor flames from spreading to
the chamber floor

The center protrusion of the
combustion chamber is loweredto accelerate the entrainment of
air atomization, and thus reduce
the PM

Gear pump

Fig. 9 Fuel supply pump for 114 Engine (Full view)

4.3 ecot3 combustion system

The diffusion combustion flame
area is curbed by optimizing theangle between the bottom andwall of the combustion chamber
to curb NOx emissions

An emphasis was placed especially on the development of
a combustion system in new engines that meets the Tier3
emission regulation. The cooled EGR adopted in medium tolarge engines is effective in reducing NOx without deteriorating the fuel consumption rate. However, the increased costof the cooled EGR, valve and other components is a negative
factor, especially for small engines. A new combustion system was adopted to achieve high performance and meetemission regulations through enhanced injection performance via the electronically controlled common rail and by
developing a new combustion technology, to simultaneously
reduce NOx and PM without using a cooled EGR.
The basic concept of the new combustion system is illustrated in Fig. 10. The point in the development work was tofind a way to reduce NOx emissions without using a cooled

2006 ② VOL. 52 NO.158

Combustion is performed in thechamfered part during the final
stage of combustion to prevent
spreading to the lower surface ofhead and reducing the PM

Fig. 11 Combustion simulation by KIVA

Development of ecot3 for Tier 3 Engine (2)― 4 ―

4.5 Noise

Apparent heat release rate (Btu/deg)

As shown by the heat release patterns in a cylinder plottedin Fig. 12, heat is generated slowly during the initial stage of
combustion, thereby contributing to a reduction in thermal
NOx during the initial stage. The heat release rate lowers andthe oxidation of soot progresses swiftly during the final stageof combustion, thereby reducing PM emissions.

Beginning 2006, in Europe, the EU dynamic Tier2 noise
regulation has been enforced with construction machinery.
The PC200-8 has cited the accomplishment of a super low
noise level of Japan as a standard specification. With this inmind, quietness of the engine was one of the important targets during the development of the engine series.
The noise of the engine was lowered by using pilot injection to reduce the combustion noise via the use of the electronically controlled common rail injection system. The 107
Engine series reduced noise (1) by lessening the gear noise
through the provision of a gear to the node of the torsional
vibration of the crank shaft, as a rear gear train structure, and(2) through a reduction of radiation sound, caused by vibration of the cylinder block by reinforcing the stiffener of thecylinder block skirt.
As a method to reduce noise, the sources generating mostnoise had to be identified and a beam forming method wasused in this development work to assess the sound sources.
An example of sound source searching using the beam
forming method is shown in Fig. 14.
Compared with the conventional engine models, noise
could be reduced significantly by changing the engine structure and identifying and improving sound sources.

The slow increase in heatrelease curbs NOx generation
while PM generation iscurbed by rapid combustion.

Crank angle (deg atdc)
Fig. 12 Result of combustion simulation ofheat release patterns

4.4 Emission and fuel consumption
Optimization of contradicting proposals for emission reduction and the maintenance of low fuel consumption wasachieved by effectively utilizing multi-mode injections
shown in Fig. 7 as the basic concept of the injection system,
as opposed to the basic concepts of the combustion system.
As shown in Fig. 13, NOx and PM levels in the achievement
performance of the Tier3 SAA6D107E-1 engine are sufficiently high in relation to the Tier3 emission regulation levels, while accomplishing an equal fuel consumption rate inrelation to Tier2 engines.

Sound is high in red
to yellow parts

After improvement

No variation in the rated fuelconsumption from Tier2 to Tier3

NOx reduced by 35%
from Tier2 to Tier3

Fig. 13 Achievement of emission and fuel consumption

Fig. 14 Sound source search by beam forming andimprovement made2006 ② VOL. 52 NO.158

Development of ecot3 for Tier 3 Engine (2)― 5 ―with the Tier2 regulation. This technology aims to increase
the density of air suctioned into the engine cylinders andlower the temperature of the intake air. The system cools thetemperature of air supercharged by the turbo charger down toa necessary temperature by a heat exchanger (air-to-air) withouter air. This system lowers the combustion temperatureand reduces NOx emissions.
Figure 16 shows the relationship between the intake airtemperature and NOx emissions. By lowering the intake airtemperature by 5°C, NOx emissions at a rating point can be
reduced by about 7%. The small ecot3 engine feeds air of alarger quantity than the Tier2 specification into the engine, toreduce emissions, and this air-cooled aftercooler plays a very
important role.

Figure 15 compares engine noise with both the new
SAA6D107E-1 engine and existing SAA6D102 engine underfull load. The new engine was subsequently found to reducenoise by 2dB (A) on average in all regions, both under load
and no load conditions.

Noise (db (A))

Noise of SAA6D107E-1 engine under full load

Tier2 102 Engine
Tier3 107 Engine

Fig. 15 Effect of engine noise reduction

Under a full load, combustion noise was a dominant factor
in engine noise and slow initial combustion by pilot injection
curbed a radical increase in pressure inside the cylinders, toreduce noise. On the other hand, the gear meshing sound andmechanical noise caused by vibration of the cylinder block
were found to generate most noise under conditions of noload. The rear gear train structure and reinforced stiffener inthe lower part of the cylinder block also contributed to reducing mechanical noise.
In both the 107 and 114 Engines, noise is also reduced
also by lowering the engine speed under a light load byisochronous control tuned to vehicle requirements.

BS NOX (g/KWh)

Engine speed (rpm)Intake air temperature andNOx emissions

Intake air temp. (°C)
Fig. 16

Intake air temperature and NOx emissions

The cooling losses of the new SAA6D107 engine and a
Komatsu Tier2 engine are compared in Fig. 17. A combustion efficiency equivalent to that of a Tier2 engine was accomplished and heat losses to cooling water could be prevented. On the other hand, the intake air quantity was increased to meet the Tier3 regulations and the temperature at
the outlet of the air-cooled aftercooler was set 5°C lower
than the conventional Tier2 specification. The net result wasthat cooling losses of the air-cooled aftercooler increased by
17%, but the heat loss increase for the entire engine was 4%,
meaning that significant increases in the capacities of coolingcomponents, such as the radiator and air-cooled aftercooler,
could be curbed.

4.6 Engine startability

Cooling loss by air-cooled aftercooler
Cooling loss to cooling water
4% increase in total

Cooling loss (kW)The electronically controlled common rail injection system enabled optimum control of fuel injection characteristics
during engine start-up, which could not be controlled by themechanically controlled fuel injection systems up to Tier2,
achieving both good startability at a low temperature and adrastic reduction in emissions of black smoke at a normal
temperature.
Fuels of a low cetane number are used in North America
and some other regions and a major problem in these regionsin the past with mechanically controlled fuel injection pumps,
which had many limitations in complying with Tier1 andTier2 regulations, was the control of white smoke being
emitted when the engine was started at a low temperature.
The electronically controlled common rail injection system
has drastically reduced emissions of white smoke during
engine start-up at low temperatures, even with fuels of a low
cetane number. The engine has indeed become eco friendly
under various environmental conditions.

Lowering the intake airtemperature by 5°C will
reduce NOx emissions 7%

17％ increase

Loss to water notchanged

4.7 Air-to-air air intake cooling system
Another important element of emission technologies forengines of construction machinery is the technology related
to the air-cooled aftercooler that has been adopted in dealing

2006 ② VOL. 52 NO.158

Fig. 17 Comparison of cooling losses of Tier2 and ecot3

Development of ecot3 for Tier 3 Engine (2)― 6 ―5. Reliability and Durability

About one year has passed after the ecot3 engine made its
market debut and the evaluation results of the market on theengine will be fed back. Our task will be to absorb suchmarket information to refine and mature the engine to further
improve it and to pass on the information gained during suchprocess to develop a Tier4 engine.

Throughout the development process of the new ecot3 engine series, all the quality verification codes of Komatsu forindustrial engines that had been set were met. New evaluation test codes were additionally developed and added toevaluate the new injection system and verification tests toadequately ensure reliability and durability of the new technologies were conducted. Flawless and fine control under avariety of environmental conditions, such as operation in thehighlands and under auxiliary operation materials, including
low-grade fuel and oil, was of concern especially due to theadoption of the electronically controlled common rail injection system. Sufficient tests were conducted to verify quality
under these severe conditions. In parallel with the adoptionof the common rail injection system, a high-efficiency fuelfiltration system was developed to protect the fuel injection
system in a dusty environment for use in global markets.
Almost all the components of the 107 Engine with an increase in displacement were newly designed, including theengine structure, power cylinder, valve mechanism, lubrication system and injection system. Their durability and reliability were verified in durability and abuse bench tests, aswell as in field tests in vehicles, totaling 10,000 hours induration. Problems encountered in these tests were correctly
addressed and regular production commenced after all the
new parts were verified to pass the quality target.

References:
ENGINE TECHNOLOGY April 2006
State-of-the-art technology of “Komatsu ecot3 Engine”“Development of Tier Engine ecot3,” Komatsu Technical Report No. 157
Introduction of the writers
Masayuki Yoshitomi
Entered Komatsu in 1981.
Currently assigned to the Product Engineering Group, Industrial Power Alliance,
Ltd.

Hideo Oguri
Entered Komatsu in 1983.
Currently assigned to the Product Engineering Group, Industrial Power Alliance,Ltd.

6. Conclusion
The features and emission reduction technologies of the
new small “ecot3” diesel engine for construction machinery
meeting the Tier3 emission regulation are described.
Conventional technologies for fuel injection were found to
be unable to meet the Tier3 emission regulations and a newcommon rail system was adopted to do so. As additional
technology to meet the next Tier4 emission regulation,
post-processing of exhaust gases will be mandatory. In addition to exhaust gas regulations, environmental considerations
are demanded by society, including noise regulation and therecycling of parts. The engineers engaged in engine development must build and introduce engines to the market in atimely fashion to meet such social needs.
The share of passenger cars powered by a diesel engine isincreasing in Europe because of their high fuel economy.
Once emissions of diesel particulate, which is a weakness ofdiesel engines, are reduced, high-efficiency diesel engines
will naturally survive as engines that are environmentallyfriendly due to low CO2 emission amount.
Research and development of hybrid and fuel cell technologies is also conducted for construction machinery, although these technologies are not yet viable to replace diesel
engines. Construction machinery manufacturers have alreadystarted moves toward the next phase to establish technologies
to meet the Tier4 regulation using diesel engines. It is feltthat challenges must constantly be made to innovate technology to develop Tier4 engines that will reduce emission
gases and be friendly to customers and the environment.

2006 ② VOL. 52 NO.158[A few words from the writers]
One year has already passed since the 107 and 114 Engines
meeting Tier3 were introduced to the market. Their market introduction has been smooth, without major problems, which is a
reward for the development effort and previous hard work.
Hardly resting, even for a moment, the new task of developing aTier4 engine has already started and the Tier3 engine is now athing of the past for the IPA. The challenge for IPA to engage inthe mass production of Tier4 engines is now entering its criticalphase.

Development of ecot3 for Tier 3 Engine (2)― 7 ―