28. Internationales Wiener Motorensymposium 2007 Yves Boccadoro, Loïc Kermanac’h, Laur ent Siauve, Jean-Michel Vincent RENAULT POWERTRAIN DIVISION 

### Der neue aufgeladene TCE 1, 2 l Ottomotor von RENAULT The new RENAULT TCE 1.2 l tu rbocharged gasoline engine

Kurzfassung
RENAULT ist seinem Ziel verpflichtet, im Hinblick auf seinen Beitrag zur Reduzierung von CO 2 - Emissionen weiterhin weltweit auf den vorderen drei Rängen zu bleiben. Um dies zu erreichen und zusätzlich zur weiter fortschreitenden Entwicklung von hochgradig effizienten Dieselmotoren hat si ch RENAULT zum „Downsizing“ entschlossen, nämlich zur Verminderung der Hubraumkapazität durch den Einsatz von Turboladern als der für die nächsten Jahre erfolgversprechends ten Technik für Ottomotoren. In dieser Arbeit wird die Entwicklung eine s 1,2-Liter-Motors beschrieben, wobei die Zielstellung nicht nur auf ei ner bedeutenden Reduzierung von CO 2 - Emissionen in der so beliebten 100-PS-Reihe zum Er satz von 1,4 und 1,6 Saugm otoren liegt, sondern womit dem Kunden das in seiner Klasse führende alternative Preis-Leistungsverhältnis angeboten werden kann. Optimieren und Kompromisse ei ngehen waren die Schlüsselbegriffe für die Techniker von RENAULT, da jeder Cent so angelegt wer den musste, dass sein Aufwand von der Kundenperspektive her gerechtfertigt sein musste – und die Techniker können nun mit berechtigtem Stolz auf das Ergebnis blicken!

Der Motor hat ein maximales Drehmoment von 145 Nm bei 3000 rpm, wobei seine Maximalleistung 74 kW bei 5500 rpm beträgt. Besonderes Gewicht wurde dabei auch auf ein hohes Drehmoment im niedr igen Drehzahlbereich gelegt, wobei 125 Nm bei 1500 rpm eine höchst respektable Beschleunigung ermöglichen. Im Vergleich mit den selbstansaugend en 1,4 l und 1,6 l Motoren liegen die Treibstoffeinsparungen bei über 12 % für den Standard-Stadtfahrzyklus mit Kaltstart und außerstädtischen Fahrzyklus. Mit der Entwicklung einer bei re lativ hohen Produktionsmengen kostengünstig einsetzbaren Turbolader-Technik erwart et RENAULT ab 2008 eine Verminderung von CO 2 - Emissionen in der Größenordnung von 1g im Wagenparkdurchschnitt.



### Abstract
RENAULT is committed to remain among the th ree top world wide manufacturers in terms of contribution to CO 2 emission reduction. To achieve th is, and in addition to pursuing the development of highly efficient diesel engi nes, RENAULT has chosen "Downsizing", the reduction of engine displacement by turbo char ging, as the most promising technology for gasoline engines in the next coming years. This paper describes the development of a 1.2 Liter turbocharged engine with the objective not only to significantly reduce CO 2 emissions in the very popular 100 HP range by replacing 1.4 and 1.6 naturally aspirated engines, but also to offer the customer a best in class cost to value alternative.28. Internationales Wiener Motorensymposium 2007 Optimize and compromise were the two key words for RENAULT engineers as each cent to be spent had to be justified from a customer perspective. The engine has a maximum torque of 145 Nm @ 3000 rpm with maximum power of 74 kW @ 5500 rpm. Low rpm torque was given partic ular attention with 125 Nm @ 1500 rpm and a very pleasing acceleration capability. Compared to both 1.4l and 1.6l naturally aspira ted engines, the fuel economy is improved by more than 12% on NMVEG cycle. By developing a low cost tur bo-charging technology with relatively high volume production, RENAULT expects over 1g of CO 2 emission reduction as a fleet average from 2008.28. Internationales Wiener Motorensymposium 2007 

### 1 Introduction
Carlos GHOSN, CEO of RENAULT, announced in February 2006 the new three year plan referred to as "RENAULT Co mmitment 2009", in which he reasserted RENAULT's firm commitment to reducing CO 2 emissions with the objective to both counter the greenhouse effect and save fuel in or der to cut the energy bill. RENAULT is currently among t he best three worldwide on CO 2 emissions and the goal is to strengthen this position in the next three years by selling 1 million vehicles producing less than 140 g CO 2 /km, of which one-third less than 120 g CO 2 /km. This achievement relies, of course, on the ex tensive use of our popul ar 1.5l Diesel engine but also on the development for the small v ehicles of low consumption affordable gasoline engines. Indeed in this cat egory of vehicles with low and medium mileage, many customers prefer gasoline to Diesel. RENAULT consider s that engine downsizing by turbocharging is the best technology in terms of customer value (f uel economy and driving pleasure) versus unit cost and development expenses. RENAULT has a long experience in turbochar ged gasoline engine, as demonstrated by the legendary R5 turbo in 1978 or in Formula 1 from 1977 to 1985, but the challenge this time was to "domesticate" this technology to offer fuel economy and driving pleasure to many a customer. To a certain extent this had already been experienced when RENAULT developed a 2.0l turbo engine for Velsatis and Espace to repl ace a more traditional 2.5l NA engine as used by competitors, and which inaugurated the deployment of a "downsizing" strategy.
So, as a continuation, RENAULT decided in 2004 to develop the TCE 100 by turbocharging its smallest gas oline engine: a 1.15l MPI engine known as "D4F". It will be presented to the Press around the middle of this year. The chal lenge in this case was to propose an affordable alternative to the 1.4l and 1.6l engines us ed on current vehicles with equal or improved attractiveness for the cust omer but with fuel c onsumption reduced by more than 10%. In the following, the characteristics and ac hievements will be described before some insight is given as to how the difficult compromise between customer value versus industrial feasibility and cost competitiveness was obtained.28. Internationales Wiener Motorensymposium 2007 

### 2 The main achievements

2.1 Main features of TCE 100

Figure 1: TCE 100 engine
Engine Family D4F NA D4Ft / TCE 100 Displacement (cc) 1 149 1 149 Bore x Stroke (mm) 69 x 76.8 69 x 76.8 Number of cylinders / Valves 4 / 16 4 / 16 Compression ratio 9,8 9,5 Max Power kW CEE (hp) 55 (75) 74 (100) Max Power engine speed (rpm) 5 500 5 500 Max Torque Nm CEE 105 145 Max torque engine speed (rpm) 4 250 3 000 Max engine speed (rpm) 6 300 6 300 Injection type Sequential multipoint Sequential multipoint Idle speed 650 rpm 650 rpm Emission level Euro IV Euro IV

Table 1: Characteristics of TCE 100 comp ared to D4F naturally aspirated28. Internationales Wiener Motorensymposium 2007 2.2 Performance and Drivability The maximum power (74 kW) and maximum tor que (145 Nm) of the engine are delivered respectively at 5 500 rpm and 3 000 rpm. Fi gure 2 compares the output to existing naturally aspirated engines.

. 80 90 100 110 120 130 140 150 160

1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000
rpmT o rq u e (N m ) Iso 74 kW

TCE TCE with Over Power 1,2 l 16 V 1,4 l 16 V 1,6 L 16 V 80 90 100 110 120 130 140 150 160

1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000
rpmT o rq u e (N m ) Iso 74 kW

TCE TCE with Over Power 1,2 l 16 V 1,4 l 16 V 1,6 L 16 V

Figure 2: Torque curves comparison of TCE 100 and 1.4 & 1.6 NA Significant torque is available at a very low speed (125 Nm @ 1500 rpm) so that the driver will prefer it to the 1. 6L NA engine in all the usual operating conditions.

Figure 3: TCE 100 engine full load torque & power curve In addition, in order to boost the overtaking c apability, a specific “Over Power” device gives a temporary increase of power (+5% or 5hp) and torque (+4% or 6 Nm) (fig. 3), limited to 2nd, 3rd and 4th gear. This function enhances the acceleration feeling of the engine at high speed ( ≥ 4000 rpm).28. Internationales Wiener Motorensymposium 2007 One of the critical issues fo r small turbocharged engines is the tip-in response time at low speed. Thanks to a low inertia turbocharger and air flow optimization, a response time of .5 sec is achieved, thus matching the respons e time of RENAULT's "dCi" engine which we know is highly praised by customers (fig. 4). Tip-in @1000 rpm in 3rd gear

0 0,05

0,1 0,15

0,2 0,25

0,3

-1 -0,5 0 0,5 1 1,5 2 2,5 3 (s)(g) 1,5 DCi TCE

Figure 4: Acceleration comparison between TCE 100 and 1.5 dCi. 2.3 Fuel Consumption Thanks to "Downsizing", a fuel consumption benefit of 12 % compar ed to the 1.4 16v MPI (and 13 % to the 1.6 MPI) is achieved on NMVEG cycle. Clio III, Modus and New Twingo will be below 140 g/km of CO 2 with TCE 100 engine and will be among the best on t he market (fig. 5).

Modus 1,4 16v 98 Modus 1,6 16v 115 Modus 1,2 16V Turbo 100 / Clio 1,2 Turbo 100

Clio 1,4 16v 100 Clio 1,6 16v 110 5,5 5,7 5,9 6,1 6,3 6,5 6,7 6,9 7,1 115 120 125 130 135 140 145 150 155 Max Torque(Nm)NMVEG fuel consumption z Modus

z Modus Competitors S Clio III S Clio Competitors

Modus 1,4 16v 98 Modus 1,6 16v 115 Modus 1,2 16V Turbo 100 / Clio 1,2 Turbo 100

Clio 1,4 16v 100 Clio 1,6 16v 110 5,5 5,7 5,9 6,1 6,3 6,5 6,7 6,9 7,1 115 120 125 130 135 140 145 150 155 Max Torque(Nm)NMVEG fuel consumption z Modus

z Modus Competitors S Clio III S Clio Competitors

Figure 5: Comparison between TCE 100 engine and competitors28. Internationales Wiener Motorensymposium 2007 However, the fuel efficiency is not limited to NMVEG cycle but is optimized for most common driving conditions. Idle stability allo ws an idle speed of 650 rpm, a significant benefit in urban traffic whilst the use of ho llow sodium valves (see §3.3.5) avoids deterioration of air/fuel ratio at high load. The benefit for the customer is summarized in the table bellow:
Cycle TCE 100 1.4 MPI Dif. TCE / 1.4 NEDC 5,9 6,7 -11,9% City jam 12,5 16,1 -22,4%

Urban 8,7 10,4 -16,3% Road 5,3 5,7 -7,0% Highway 7,9 8,3 -4,8% 60 km/h stabilized 3,8 4,2 -9,5% 90 km/h stabilized 5,2 5,5 -5,5% 120 km/h stabilized 7,4 7,7 -3,9% Table 2: Fuel consumption (l/100km)



### 3 The elements of success
3.1 Concept and technology selection As was already said, the main target for this project was to reduce fuel consumption by over 10% whilst keeping the cost com patible with large scale distribution. "Downsizing" through turbocharging technol ogy was chosen among alternative options such as lean burn engine or micro hybr idization because of its optimum CO 2 reduction to additional cost ratio in the ta rgeted categories of vehicle.

0% 5% 10% 15% 20% 25% 30% CO 2 reduction on NMVEG [%]Additional cost

Stop/Start VVL Brake & Boost downsized GDI

GDI λ =1

VVT base MPI NA w/o VVT Diesel

Downsized MPI TCE

0% 5% 10% 15% 20% 25% 30% CO 2 reduction on NMVEG [%]Additional cost

Stop/Start VVL Brake & Boost downsized GDI

GDI λ =1

VVT base MPI NA w/o VVT Diesel

Downsized MPI TCE

Figure 6: Cost effectiveness of low CO 2 technologies Moreover, the fuel economy benefit is less sensitive to vehicle usage than other technologies. The high torque at low rpm of TCE 100 engine allows for an attractive trade-off between fuel economy and fun to drive through gear ratio definition. Nevertheless, cost considerations lead us to take the best of simple and well-proven28. Internationales Wiener Motorensymposium 2007 technologies. First, we decided to derive the TCE 100 from an existing 1.15l naturally aspirated engine giving the opportunity to use existing producti on facilities and to maximize the number of carried over parts. Its small displacement was suited to the performance target. The second important decision was to keep port injection as opposed to direct injection in order to limit fuel system cost and to keep current combustion chamber and cylinder head. Third: single-scroll turbocharger was preferred to twin-scroll. Simple turbocharger was considered as suitable for an engine that is us ed in most cases at low speed. Furthermore, maximization of power at high engine speed would have led to considerable design changes. So power target wa s limited on purpose, allowing the use of a simple turbocharger.
3.2 Combustion 3.2.1 Steady-State Conditions Tests carried on stationary bench s how that our technical definition choices lead to the same maximum power (74kW) as our current 1.4l naturally aspirated engine, despite a 20% lower displacement. Increased torque at low engine speeds and a maximum mean effective pressure of 16 bar have been achieved, which is significantly higher than 1.4l naturally aspirated engine (fig. 7). The goal of the development was to take the best of single scroll turbocharger in term of low end torque and fuel efficiency. As a result, the performances reach the maximu m that the base engine can stand without significant and costly modifications.

80 90 100 110 120 130 140 150 160

1000 2000 3000 4000 5000 6000 Engine Speed [rpm]Engine Brake Torque [N.m]

1.2lTC (74 kW@5500 rpm) 1.4l NA (72 kW @6000 rpm) 8 10 12 14 16 18

1000 2000 3000 4000 5000 6000 Engine Speed [rpm]BMEP [bar] 1.2lTC (74 kW@5500 rpm) 1.4l NA (72 kW @6000 rpm)

Figure 7: Final full load results (tests on stationary bench) Since the use of technologies such as vari able valve timing was also avoided for cost reasons, the development was focused on findi ng the right parameter s for turbocharger design, cam timing, tumble in take port pattern as well as intake lines and exhaust system design. 1) The turbocharger design is a balance between high boost pressure at low speeds (for maximum torque) and good efficiency at high speeds (for fuel economy).28. Internationales Wiener Motorensymposium 2007 2) The intake and exhaust lines must be designed for both aerodynamics and acoustics and must achieve a trade-off between pressure drop at maximum power and amplitudes of intake pressure waves at low engine speed. 3) The camshaft timing is also a compromise between low and high speeds performance, fuel consumption at part load and idle condition: • An early closing of the inlet valve at low speeds reduces backf low, thus improving volumetric efficiency, but goes against fuel consumption at part lo ad; furthermore the increase of the effective compression ratio is limited by knock. • The time of exhaust valve opening is optimized to increase scavenging during valve overlap at low and high speeds (fig. 8). With a late openin g, the timing of interaction between cylinders changes and the pressure at cylinder exhaust during scavenging decreases. • The overlap must be limited to avoid residual gas fraction trapped in the cylinders at idle and high speed full load.

0 10

0 180 360 540 720 Crank Angle [deg]Valve lift [mm]

0 3 6 9 12 15

1000 2000 3000 4000 5000 6000 Engine Speed [rpm]Residual Gas Fraction [%]

3%

Figure 8: Effect of exhaust valve opening de lay on residual gas fraction. The impact on volumetric efficiency at low engine speed of camshaft timing added to intake and exhaust layout proved to be successful.

1000 2000 3000 4000 5000 600 0 Engine Speed [rpm]Corrected Volumetric Efficiency[-] 

# ↕ 0.1 0

1000 2000 3000 4000 5000 6000 1.15l TC SS (74 kW @ 5500 rpm )
1.4l NA (72 kW @ 6000 rpm)

Figure 9: Final volumetric efficiency results at WOT. The volumetric efficiency is reduced to manifold conditions.28. Internationales Wiener Motorensymposium 2007 Thanks to acoustic effect (inlet system) at low rpm and turbocharger at high rpm, TCE engine volumetric efficiency is constant at every speed and therefore better than 1.4 l NA (fig. 9; note that volumetric data has been corrected in order to be comparable). 4) The tumble patterns also appeared to be helpful to reach the low engine torque target without deteriorating high speed performances. As shown in figure 10, the new intake ports improve the shape of co mbustion heat release. The energy in the turbine is increased, leading to a higher intake pressu re. Thus, the improvement in torque at low speeds (<1750 rpm) was measured from 2 to 6%.

0 0,01 0,02 0,03 0,04 0,05 0,06 0,07 0,08

-20 0 20 40 Crank Angle (°)Heat release velocity (1/°V)

99 100 101 102 103 104 105 106 107

1000 1200 1400 1600 1800 2000 Engine Speed [rpm]Torque [%]

1000 1100 1200 1300 1400 1500

1000 1200 1400 1600 1800 2000 Engine Speed [rpm]Intake Pressure [mbar]

0,03 0,08

Crank An g le ( ° )Heatreleasevelocity(1/°V) Basic port - 1500 rpm - SA=16°V - CA50=12°V Tumble port - 1500 rpm - SA=12°V - CA50=13°V 1000 1500

En g ine S p eed [ r p m ]IntakePressure[mbar] Basic Ports Tumble Ports Figure 10: Impact of tumble at WOT

3.2.2 Transient Conditions We have tested the transient behav ior by measuring the time to reach 90% of the final torque at various constant speeds. The engine can quickly get to WOT performance thanks to the short distance between the cylinder head and the turbine, the low inertia of the turbocharger and the design of the intake line. In final, the acceleration capabi lity of the 1.15l turbocharged engine is equivalent to our current 2.0l twin scroll turbocharged engine.
3.2.3 Part Load To achieve a significant fuel economy compared to the 1.4l NA engine, several ways were adopted:

• The compression ratio (9.5) is high for a PFI turbocharged engine and close to the NA version, minimizing the lo ss of combustion efficiency.

• At low load, where unfavorabl e thermodynamic conditions of flame initiation are met, the tumble effect is positive on stability and combustion efficiency thanks to better combustion timing. The fuel economy im provement below 1.5 bar BMEP is shown on figure 11.28. Internationales Wiener Motorensymposium 2007 0 2 4 6 8 10 12 14 16

0,5 1 1,5 IMEP (bar)COV IMEP - FE (%) (*) Stability w/oTumble Stability withTumble Fuel Improvment

Figure 11: Effect of tumble on combustion stabi lity and fuel consumption (2000 rpm)

(*) COV IMPEP Covariance of Indicated Mean Effective Pressure / FE Fuel Economy

• The reduction of engine displacement in creases the engine BMEP for the same engine output power, moving the operating points towards increased efficiency areas. This, combined with optimizing the g ear box ratio thanks to higher low end torque is the main source of fuel econom y improvement in urban driving conditions.28. Internationales Wiener Motorensymposium 2007 3.3 Design concept

Exhaust side Intake side Figure 12: Views of TCE 100 engine

The TCE 100 was intended to be manufactured on the same production lines as the 1.15l naturally aspirated engine which meant, from the beginning, acc epting a number of limitations to the possible design changes to limit industrial investments. Moreover, we deliberately made maximum us age of existing parts: crankshaft, oil pan, bearings, driving and timing belt, camshaft pulley, oil and coolant systems are carried over from the existing engine wher eas all exhaust face component s (manifold, turbocharger, close-coupled converter, gaskets, and brackets), cylinder block, connecting rod, piston, cylinder head, exhaust valve, rocker co ver and intake manifold are new. 70 part references (48 %) are comi ng from the NA engine version. 3.3.1 Cylinder head The cylinder head has a "cross flow" archit ecture with a single overhead camshaft activating four valves per cylinder by means of rocker followers. The water circulation chosen after hydraulics calculations is “diagonal”. The design of the intake ports has been c hanged from NA engine. The improvement on tumble flow with new ports has been evaluat ed by 3D computations with VECTIS code. Figure 13 shows the port velocity vector flow pa tterns at intake valve center cross-section for current and revised intake ports. As shown in figure 13, the inlet flow with revi sed port is directed towards the exhaust side more than in case of existing port and enters the cylinder with a higher initial angular momentum which is favorable to generate tumble.28. Internationales Wiener Motorensymposium 2007 NA engine intake port tumble intake port Figure 13: Comparison of flow patterns between cu rrent intake port and revised intake port by 3D Calculations To achieve the aerodynamic requirements and to limit the tumble ra tio variations in production, a “mono block” architecture has been chosen for the water core design. This core is made of exhaust and intake pipes, linked to each other with the chamber. With this shape, the valve seats are maintained around the pipe, near the c hamber, and can be inserted before casting (fig. 14).

Figure 14: Cylinder head, valve seat and core The main advantages to use inserted valve seats before casting versus more usual designs (i.e. binding and machined) is to reduc e the misalignment betwe en the valve seat and the pipe at competitive cost and to improve conductibility. A specific water jacket has been implemented thus reducing the maximum fire deck temperature by 35°C This was necessary to improve the cylinder head reliability and the knock limit of the engine and reach the required performance (fig. 15).28. Internationales Wiener Motorensymposium 2007 Figure 15: Comparative thermal calculation between NA and turbocharged engine 3.3.2 Piston and rings Turbo charging leads to high combustion c hamber temperature and pressure. So piston cooling oil jets with adapted jet speed and flow ra te are added to meet ou r reliability target at high specific power (about 65 kW/liter) (fig. 16).

Figure 16: Piston and oil jet Specific material is required to sustain the rmo-mechanical loads. In or der for the piston to run under severe lubrication conditions, the oil rings has been reinforced with a nitriding treatment. An innovative shape has been designed for the 1 st groove to achieve our reliability target at minimum cost (fig.17).28. Internationales Wiener Motorensymposium 2007 Figure 17: Piston first groove design 3.3.3 Connecting rod Associated to floating pin, a bush is needed on the small end side. Before starting reliability engine bench tests, FEM simulation validation have been carried out to minimize fatigue stress (fig. 18).

Figure 18: Connecting rod FMEA calculation 3.3.4 Cylinder Block Due to high specific power, it is necessary to check the maximum thermo mechanical stress value reached in the cylinder block, especially around the bore. On the next picture (fig. 19), t he bore thermal map is presented. On this calculation, it is possible to check the water cooling efficien cy and its compatibility with acceptable wear level on rings and bore roughness.28. Internationales Wiener Motorensymposium 2007 Figure 19: Water cooling calculation on cylinder block results The water cooling system is simple, classi cal and perfectly adapted to the requirement.
3.3.5 Exhaust valves High air/fuel ratio at high load leads to high valve temperature not compatible with standard valve technology. To reach our fuel consumption target, hollow sodium valves technology was chosen. The thermal gradient in the valves signif icantly reduced (about 150°C) (fig. 20).

Figure 20: Thermal comparison between st andard and sodium hollow valve 3.3.6 Turbocharger The turbocharger, made by MHI Netherlands, has single-scroll architecture, which is simple and reliable. The exhaust is simplified both in design and material. Cast iron (D5SNiResist) is used instead of st eel (KN2) for the manifold. The bearing housing is water-cooled. FEM calculations are made to avoid cr acks on hot components and leakages at the interfaces

.28. Internationales Wiener Motorensymposium 2007 Figure 21 : Turbocharger cutaway 3.4 Quality management For the design of new parts, we used the "D esign to Quality" approach, a methodology, recently developed with the help of NISSAN, which has been at the center of the Quality breakthrough achieved by RENAULT Powertrains in the last 2 years. It relies upon the systematic use of "standards" for known parts and specific attention given to "innovative parts" including a method called “previous reliabili ty”, based on exploitation of tools such as Provisional risk analysis, Perfect Fault Tr ee Analysis, Failure Mode and Effect Analysis 3.5 Manufacturing The TCE 100 is produced at Douvrin in the north of France, by "Française de Mécanique". The "D engine" department wit h capacity of over 500,000 engines per year was elected several years running as the mo st efficient plant in Europe by Harbour Consulting. The TCE 100 will also benefit of this high level of competitiveness.28. Internationales Wiener Motorensymposium 2007 

### 4 Conclusion
The challenge with the TCE 100 engine was to develop an AFFORDABLE turbocharged version of an existing and already highly optimiz ed 1.2l engine in orde r to replace 1.4l and/or 1.6l naturally aspirated engines in the core of RENAULT's B-segment.

Figure 22: Twingo Concept No exceptional technology was used but each parameter was optimized to give maximum customer value to cost benefit. The single scroll turbocharger and associ ated aerodynamics were adapted to produce high torque at very low rpm, thus matching the larger engines acce leration capabilities and driving pleasure. Structural design modifications were minimized in order to lim it industrial investments and make maximum use of existing facilities. We are convinced this engine will have great success with our customers, thus helping RENAULT reach its ambitious CO 2 emission targets.