cover story tHrEE-CyLINDEr ENGINEs

22 www.autotechreview.com The New Hyundai-Kia 1.0 l Three-cylinder Gasoline Engine

With the new 1.0 l Kappa (κ) gasoline engine, which can be found in the face-lifted Hyundai i10 and the new Kia Picanto, Hyundai-Kia combines a three-cylinder concept with modern technologies such as the initial ­application of variable valve timing within this displacement segment.

autHors central role in the company’s efficiency are improved by reducing the future small cars number of cylinders. Therefore, determin­ ing the number of cylinders was crucial Climate change and the influence of hu­ for development of the Kappa 1.0 l engine. mans on it are the subjects of world-wide Compared to a four-cylinder engine, a discussion. The transportation sector, in­ three-cylinder engine has better perfor­ cluding cars, trains, aircraft and ships, is mance and fuel economy, ❶. Nevertheless, responsible for more than one-fifth of all a NVH (noise vibration harshness) prob­ Sunghoon Lee is Leader of Design for Kappa Engine global CO2 emissions. Hyundai-Kia is meet­ lem caused by increased unbalanced forces Family at Hyundai Motor Company ing the challenge to lower emissions as remained the weakness of the three-cylin­ (HMC) in Seoul (Korea). required by legislation in all markets. Such der. However, through optimal design of regulations, as well as rising energy prices, the cranktrain, reinforcement of the engine lead to an increased interest in compact structure and optimizing the match with a vehicles. The new 1.0 l three-­cylinder en­ vehicle, NVH can be improved. Contrast­ gine out of the Kappa family is part of the ing with a three-cylinder engine, a two- Hyundai-Kia sustainable product strategy cylinder engine generally fitted to a motor­ and combines high achievement with fuel cycle cannot meet NVH quality without a Youngsam Gu is Member of Design for Kappa efficiency. The selected three-cylinder con­ balance shaft because of excessive un­ ­Engine Family at Hyundai Motor cept fulfils high acoustic requirements due balanced forces caused by reciprocating Company (HMC) in Seoul (Korea). to intensive detail optimization. From the mass. If the balance shaft is applied, the beginning of development, the engine was vibration of the C1 component will be designed with country-specific requirements decreased. However, fuel economy will in mind. The economic and eco-friendly become worse due to power loss. Also, Kappa engine family will – when flanked by applying a balance shaft increases cost additional derivates – take over a central and weight. Moreover, larger and longer role in the company’s future small cars. intake and exhaust systems are necessary Dr. Taechung Kim is Leader of Engine Simulation at to reduce low-frequency combustion noise, ­Hyundai Motor Company (HMC) the unique noise of a motorcycle. Even in Seoul (Korea). Concept Decision: with the application of these technologies, Number of Cylinders there are limits to combustion noise re­ duction in a two-cylinder engine. Adding In the early phase of development, the an alternator, air conditioner compressor four-cylinder engine was typical in the and a starter motor on a two-cylinder 1.0 l class. However, owing to increasing engine body restricts design freedom. In demands for improved fuel economy, conclusion, considering NVH quality, cost Dr. Joachim Hahn three-cylinder engines were launched; the and other factors, the three-cylinder con­ is Leader of Design and Mechanical Development at Hyundai Motor Europe development of a two-cylinder engine was figuration was determined to best for the (HMETC) in Rüsselsheim (Germany). even reported. Friction loss and thermal Kappa 1.0 l engine. autotechreview September 2011 Introductory Issue 23 cover story tHrEE-CyLINDEr ENGINEs

weight is optimised by the cranktrain behaviour analysis to minimise three­cy­ linder engine vibration. In the case of the

4-cYLinDer 3-cYLinDer 2-cYLinDer three­cylinder engine, the major design + focus of the crankshaft is minimising both fueL conSumpTion + (~ 3 % … 5 %) the vertical pitching and longitudinal yaw­ performance + + ing. Both vibrations mainly depend upon + weighT + the balance­weight and one is inversely (~ -10 %) reference proportionate to the other. Therefore, it is nVh - -- crucial to minimise the pitching and the + coSTS + (~ -9 %) yawing. By analysing the crankshaft effecT of SYnergY* + o through dynamic simulations in the form of assembling pistons and connecting *with κ 1.2 l four-cylinder ❶ Decision matrix: number of cylinders rods, the Kappa is designed to the optimal shape of its crankshaft balance­weight. The endurance of the crankshaft was en ­ VerSion 51 kw / 69 pS 60 kw / 82 pS biVaLenT sured by computer­aided strength analysis number of cYLinDerS [-] 3 and evaluating the physical part. To

arrrangemenT [-] Inline improve fuel efficiency, the offset crank­ shaft mechanism, ❸ , is applied. The off­ DiSpLacemenT [cm³] 998 set crankshaft mechanism is the fuel bore x STroKe [mm x mm] 71 x 84 economy technology used to reduce the compreSSion raTio 10.5 friction force between the piston thrust DiSTance of cYLinDerS [mm] 78.5 face and the cylinder bore inner face on

VaLVe arrangemenT [-] 4V – DoHC, Dual CVVt the explosion stroke by optimizing the eccentricity e. But the contact force on a VaLVe acTuaTion [-] tappet with mechanical lash piston anti­thrust side becomes greater Timing DriVe [-] roller chain while a piston moves up. As a result of inTaKe SYSTem [-] Fixed lenght Variable length Computer­Aided Engineering (CAE) analy ­ raTeD power [kw] 50.7 60.3 sis, the eccentricity e is optimised at 11 mm,

max. TorQue [nm] 95 giving the Kappa improved fuel economy of 1 % at low engine speed. By using De ­ fueL [-] Gasoline LPG / gasoline sign for Six­Sigma (DFSS) and FEM, the ❷ Engine specifications connecting rod is designed to be the light­ est one in its capacity class, ❹ , while improving fuel efficiency and ensuring endurance. In order to decrease the iner­ SpecificaTionS applied to the cylinder bore to enhance the tial force, the piston is optimised by mini­ abrasion durability. With added 0.7 mm mising the piston compression height The new Kappa 1.0 l engine – DOHC with spine on the outer surface of the liner, (24.7 mm), pin­bosses distance and skirt four valves per cylinder – achieves high­ adhesion between aluminium and the length. As a result, piston weight is 161 g. est values for power, fuel efficiency and cast­iron liner is improved. Therefore, the Decreased weight of the piston and con­ acoustics. The basic data of the aggregate deformation of the cylinder bore is reduced. necting rod enables the Kappa to improve are summarised in ❷ . The engine design Consequently, oil consumption and the fuel efficiency by about 0.5 %. Because will be explained in the following amount of blow­by gas are decreased. The the piston ring is coated with Physical paragraphs. shape of the skirt is designed as a corru­ Vapour Deposition (PVD), the tension of gated type to enhance stiffness. Also, for the piston oil ring is reduced by 33 %. minimising weight and improving NVH MoS2­coated piston skirt and reduced pis­ cranKcaSe performance, the ribs and shape are opti­ ton ring tension provide 0.6 % better fuel mised by FEM (Finite Element Method) efficiency to the Kappa. Two major tech­ The aluminium alloy cylinder block is analysis. nologies are applied on the bearings to applied to reduce engine weight by 12 kg. improve fuel efficiency. First, the multi­ Also, the cylinder block is designed as an boring bearing technology reduces oil open­deck type of high­pressure die­cast­ cranKShafT anD piSTon group leakage by eliminating the crush relief ing process. Meanwhile, to reduce the and optimizing the gap between crank­ length and weight of the Kappa engine, For reducing weight and manufacturing shaft journals and bearings. Therefore, the bore gap is designed to be 7.5 mm cost, the crankshaft is made of cast iron, the optimised inner profile of the bearing with a Siamese type. The cast­iron liner is FCD700C, and the shape of balance­ decreases the amount of consumed oil.

24 www.autotechreview.com Second, the partially grooved bearing overcomes the disadvantage of increasing by 10 % at whole engine speeds compared technology also reduces oil leakage by friction due to sliding contact between to a conventional valve spring. To reduce decreasing the grooved area of both ends. camshaft and tappet. In comparison with inertial mass, the MLA tappet minimises With these two technologies the oil pump nitrification coating, the DLC coating gets wall thickness. It is 20 % lighter than capacity is decreased by 13 %, increasing 0.3 % better fuel economy by reducing other replacements, creating the smallest fuel economy by about 0.4 %. valvetrain friction. The friction of the DLC- valve spring load and reducing friction. coated tappet is improved relatively better at low-engine speed than at high-engine Cylinder head speed. For improving fuel economy by Intake and Exhaust Manifold reducing valvetrain inertial mass, Kappa A pent-roof combustion chamber and a uses a beehive valve spring. Similar to the The three-cylinder engine is alternatively tumble inlet port, ❺, are applied to the shape of a beehive, the top diameter of equipped with an intake manifold of con­ cylinder head to reduce HC emission the beehive valve spring is designed to be stant length and a variable counterpart in while improving the characteristics of smaller than the bottom diameter. This order to achieve two power variants. In combustion. Also, tumble flow, which lowers the weight of the retainer and valve both cases the plenum is made of plastic was reinforced by 15.8 % than the initial spring and reduces the inertial mass of the to reduce weight and costs. To ensure design, was applied to improve combus­ valvetrain. Valvetrain friction is lowered high engine torque at middle speeds, the tion efficiency, therefore torque at low and middle speed (1500 to 3000 rpm) is improved by 1 %. For converging air-fuel mixture at the spark plug, the squish area ❸ Influence of crankshaft offset on friction takes 10 % of the cylinder bore area. The spark plug is placed in the centre to shorten flame paths thereby giving good combustion and reducing raw emission. The scissors angle of the valve was devel­ oped at 33.2 ° to minimise the surface of the combustion chamber, thereby improv­ ing combustion efficiency and minimising the size of the cylinder head.

Valvetrain and Timing Drive

The Kappa adopts the world’s first Dual Continuously Variable Valve Timing (Dual-CVVT) technology in its capacity class. Dual-CVVT technology maximises fuel efficiency and performance by opti­ mizing valve timing. It continuously alters inlet/outlet valve timing depending on driving conditions to reduce pumping loss Optimized conrod and increase volumetric efficiency. With

Dual-CVVT technology the Kappa improves Other engines κ 1.0 l engine fuel economy by up to 3 % and perfor­ 700 mance significantly compared to a non- CVVT engine. Also, it decreases emission 600 gases such as NOx and HC by the effect of the internal Exhaust Gas Recirculation 500 (EGR). Moreover, the internal EGR helps

to achieve cost reduction, because catalyst Weight [g] 400 jewelry weight is reduced. The Kappa is developed with Mechanical Lash Adjuster 300 (MLA) tappet of the direct acting type, ❻, for reducing inertial mass of the valve sys­ 200 800 1000 1200 1400 1600 1800 2000 2200 tem and saving costs. The MLA tappet is 3 coated with Diamond Like Carbon (DLC) Displacement [cm ] to improve fuel efficiency. DLC coating ❹ optimized κ 1.0 l conrod in the field of competition autotechreview September 2011 Introductory Issue 25 cover story Three-cylinder Engines

❺ Combustion chamber shape and layout of cylinder head variety, which improves torque and maximum power by 1.0 Nm and 1.5 kW, respectively. The exhaust manifold is made of cast iron, thereby reducing cost by 30 % compared to a stainless steel exhaust manifold. The increased content of silicium enables the Kappa to resist ­oxidation under high-temperature condi­ tions and to improve the catalyst durabil­ ity. The new engine fulfils the latest Euro 5 standard.

Operation Strategy

All derivatives of the new three-cylinder engine are available in combination with an engine start-stop system which lowers fuel consumption by approximately 3 %. The decision to implement an engine start-stop system was taken after evaluat­ ing a number of single parameters, such as the clutch pedal position, the shift lever, ve­hicle speed, level of battery ­charging, the outside temperature and electrical consumption. In the algorithm, safety-relevant aspects get highest priority. Vehicles with a start-stop system have a more efficient starter as well as a battery with higher capacity. An Alternator ­Management System (AMS) controlling the alternator based on driving conditions is also used and increases fuel economy ❻ Friction-optimized by about 1.5 %. valvetrain

Optimization of Engine and Vehicle Acoustics static tube corresponds to the long posi­ experiment and specified to 451 mm. The tion of the switchable runner. The mani­ shape of the surge tank is changed to a For reducing noise when the engine is at fold length was verified by simulation and curved structure from the typical straight idle, a ramp profile of the camshaft is

❼ Improvement examples by NVH analysis

26 www.autotechreview.com 160 the Kappa. Volumetric efficiency of the Kappa 1.0 l Bi-Fuel engine is improved by Trendline 140 applying a Liquid Petroleum Injection (LPI) system. This injects LPG into each cylinder head port’s entrance and controls 120 the rate of fuel flow accurately. Therefore,

CO2 is reduced by 5 % while power is improved as much as in the gasoline vari­ 100 Dry mass [kg] Other engines ant. The Kappa LPI Bi-Fuel engine is κ-1.0 l engine equipped with both gasoline and LPG 80 injector. And because of poor conditions in the combustion chamber caused by the dry characteristic of LPG, superior valve 60 800 1000 1200 1400 1600 1800 2000 2200 2400 seats and valves in properties of abrasion, corrosion and heat conductivity are devel­ Displacement [cm3] oped. Also, the piston top ring is PVD ❽ Dry mass of new κ 1.0 l engine in comparison to competitor engines (Physical Vapour Deposition) coated to improve durability.

optimised to eliminate vibration from Bi-Fuel Variant for Driving Results valve action. The shape and volume of with Gasoline and LPG the delivery pipe are changed to decrease With the application of the latest tech­ ticking noise of an injector, thereby mini­ With tightened CO2 regulations and oil nologies, such as Dual CVVT and the mising the high-frequency noise compon­ price fluctuation, the need for developing switchable intake manifold (VIS), the new ent. In order to reduce radiated noise in an LPG engine is growing. However, Kappa 1.0 l engine achieves the best-in- Wide Open Throttle (WOT), the engine because of the shortage of LPG infrastruc­ class performance. The same technologies structure is analysed and modified by ture, demands on the development of in combination with a carefully detailed using extensive CAE. Also, to improve Bi-Fuel engine – which consumes both optimization – particularly in the field of engine NVH, a high-strength aluminium gasoline and LPG fuel – are increasing. the engine mechanics – allow partial-load engine block and ladder frame are used. To meet these needs, Hyundai-Kia has fuel consumption to represent a new The circular matching structure allows the developed the 1.0 l LPI Bi-Fuel version of ­optimum within the competitor engines powertrain to be stiffened. Additionally, compact and strong accessory packaging is ap­­­plied by directly mounting both the 100 alternator and air conditioning compres­ ❾ Performance and torque curve of the new sor on engine block. To reduce radiated κ-1.0 l engine (3-cyl) κ 1.0 l ­engine noise, the vibration path from piston to ε-1.0 l engine (4-cyl) ladder frame is optimised and radiation (predecessor) from radiation surfaces such as head 80 cover, chain cover and in/exhaust is reduced. ❼ shows the analytical results of reduction of vibration and radiated noise 60 from a chain cover and a head cover by using CAE. To reduce rumble noise from the engine partial load operation condi­ Power [PS] tions, ECU data, such as spark timing, are 40 100 optimally matched. To decrease both whine and ticking noise of the chain drive 90 a Pressure Regulation Valve (PRV) is applied to the chain tensioner. Also, cool­ 20 80 ing fan noise of the alternator at middle- and high-speed acceleration was reduced 70 Torque [Nm] by applying a dual fan configuration. Vibration level in the vehicle interior is 0 60 reduced by using a stiffer dash panel and 1000 2000 3000 4000 5000 6000 7000 a dense isol­ation pad. Speed [rpm] autotechreview September 2011 Introductory Issue 27 ATZ. A VARIETY IN AUTOMOTIVE 200 Other vehicles 180 KNOWLEDGE. Kia Picanto 160

140 emission [g/km] 2

CO 120

100 Gasoline (95 g/km) Bi-fuel (90 g/km) 80 800 900 1000 1100 1200 1300 1400 1500 Displacement [cm3]

❿ CO2 emission of new Kia Picanto in the field of competitors

(λ=1 and Non-EGR) with a value of only identify a new benchmark in the 1.0 l 375 g/kWh at 2000/min and 2 bar. By class, ❿. As the further variant, the pro­ using various tech­nologies to decrease duction of an ethanol-compatible engine noise, the Kappa improves NVH quality (FFV) will start within 2011; a turbo­ about 2 to 3 dB over competitive engine charged version of the 1.0 l engine is at whole engine running zones. To reduce under development and will mark a 6 TITLES WITH TOPICS weight, the Kappa uses an aluminium ­further, consistent step toward sustain­ FOR EVERY DISCIPLINE. ­cylinder block, plastic intake manifold able mobility in near future. and other technologies. Through strain Up-to-date information, printed and and stress analysis and NVH develop­ References ment, the shape of rib is optimised and [1] Sunghoon Lee, Bosung Shin: The Design and digital formats, advanced training Development of New Hyundai Kappa 1.2 L Dual- the thickness of the wall becomes thin­ and events: this is ATZ. Professional CVVT Engine. SAE, 2011 ner. As a result, the Kappa weighs only [2] Sunghoon, Lee, Bosung Shin, Chunseok Jeon: journals for every discipline within 71.4 kg, making it the lightest 1.0 l engine The Design and Development of the New Hyundai Kappa Engine. APAC, 2009 the automotive world, with addi- in comparison to competitor engines, ❽. [3] Joachim Hahn, Peter Birtel, Seung Beom Yoo: tional digital features like ATZ online Hyundai-Kia solutions for European LPG market. portal and eMagazines. Plus events, IAV-Tagung Gasfahrzeuge, 2010 conferences and seminars. One pub- Summary and Outlook lisher, every bit of information. The interdisciplinary efforts in the course of the development of the new See the entire collection at Kappa 1.0 l engine led to an aggregate www.ATZonline.com with high power and efficiency. The derivate with switch­able intake manifold delivers 60 kW/82 PS and achieves a maximum torque of 94 Nm, ❾. The ­specific advantages of the three-cylinder concept, the application of selected tech­ nologies – such as start-stop system, but THANKS also detailed optimizations of all compo­

nents – contribute to an efficient ve­hicle These results would not have been possible engine. High requirements for comfort without the cooperation of Sungwon Shin and were fulfilled by consistent treatment Dr. Myongho Kim of Hyundai Motor Company, of the concept-specific challenges. CO 2 so the authors wish to express gratitude for emissions of 95 g/km for the new Kia their contribution. Picanto with a gasoline engine and 90 g/ km for the variant with Bi-Fuel engine

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