Cover Story DIESEL ENGINES THE NEW 3-CYL ENGINE FROM VW’s MODULAR SYSTEM

With its new three-cylinder diesel engine, has created a universal basis for application in the small vehicle segments of the Group. This slimming down of the engine range and integration into the modular diesel architecture has succeeded in significantly reducing production effort and costs compared to the previous multi-engine strategy. Development was focused on cutting CO2 emissions, and all versions of the Polo equipped with the new engine also comply with the Euro VI emissions standard.

38 www.autotechreview.com AutHors OBJECTIVES

Volkswagen’s modular diesel engine sys- tem (MDB) was designed from the con- cept phase to incorporate a range of cylin- der numbers. The line-up is thus being expanded with a reduced-displacement DIPL.-ING. FRIEDRICH EICHLER is Head of Engine three-cylinder unit. The main area of Development at Volkswagen application for this is in the Volkswagen AG in Wolfsburg (Germany). Group’s smaller vehicle platforms. The specification document for the new three- cylinder TDI engine is focused particularly on the technical and economic require- ments for using diesel engines in small vehicle classes: :: Compatibility with all of the group's DIPL.-ING. JÖRN KAHRSTEDT transverse platforms; is Head of Diesel Engine Development at Volkswagen :: Significant reduction in CO2 emissions AG in Wolfsburg (Germany). and weight compared with preceding engine; :: Raising the specific power and torque compared with the previous engine and thus the potential for slimming down the engine line-up; :: Cost reduction through part sharing DR.-ING. EKKEHARD POTT from the modular diesel engine system is Head of Commercial Vehicle and through flexible production and and Small Diesel Engine Development at Volkswagen AG in assembly on existing equipment; and Wolfsburg (Germany). :: Fulfilment of Euro VI emission standards.

MAJOR ELEMENTS OF THE NEW THREE-CYLINDER ENGINE FAMILY

DIPL.-ING. (FH) HENRIK BEDDIES Following introduction of the four-cylin- is Project Manager of Diesel Engine der variants of the modular diesel engine Development at Volkswagen AG in [1, 2] Wolfsburg (Germany). system in 2012, the diesel range is now being expanded downwards with the new three-cylinder engine in three power outputs ranging from 55 kW (74 hp) to 77 kW (103 hp) and a common displacement of 1.4 l, 1. In its first appli- cation in the new Polo, the engine has been able to replace the 1.2 l three-cylin- der TDI and the 1.6 l four-cylinder TDI engines entirely [3, 4]. In view of the expanded performance spectrum and the elements familiar from the four-cylinder engines in the modular diesel engine system, development work on the new three-cylinder engine is able to call on extensive previous experience. While the crankcase, cylinder head and valve drive, turbocharging assembly and powertrain had to be reconfigured specifi- cally for the three-cylinder layout, it was possible either to carry over or optimise autotechreview September 2014 Volume 3 | Issue 9 39 Cover Story DIESEL ENGINES

1.4 l, 55 kW, Euro 6 1.4 l, 66 kW, Euro 6 1.4 l, 75 kW, Euro 6

3 3 3 Displacement 1422 cm 1422 cm 1422 cm

Bore/stroke 79.5/95.5 mm 79.5/95.5 mm 79.5/95.5 mm

Cylinder spacing 88 mm 88 mm 88 mm

Compression ratio 16.1 16.1 16.1

55 kW 66 kW 77 kW Rated power at 3000-3750 rpm at 2750-3250 rpm at 3500-3750 rpm 210 Nm 230 Nm 250 Nm Max. torque at 1500-2000 rpm at 1500-2500 rpm at 1750-2500 rpm

Weight (DIN 70020-GZ) 132 kg 132 kg 132 kg

❶ Technical data for the new three-cylinder TDI engine

existing assemblies for the ancillary drive :: Integration of thermal management faces are thermal-interference-fit thin- and timing gear, as well as on both the measures; wall liners made from GJL 250. Com- hot and cold side of the engine, 2. :: Placement of the threads for the pared with the preceding engine, just cylinder-head fasteners beneath the changing the material of the crankcase water jacket; achieved a weight reduction of 11 kg. CRANKCASE :: Optimisation of the untreated and In order to allow for the use of alu- clean oil circuits to reduce flow minium, the crankshaft bearing cover The development objective of a weight- losses; and alignment was widened and the thread reduced and acoustically optimised :: Extension of the oil-return and chamfer for the bearing cover screws crankcase was achieved through realisa- blow-by channels to the oil-sump raised. Further stress reduction in the tion of the following points: parting line. bearing was achieved by calculat- :: Designing the crankcase in alumin- The crankcase, which for the first time ing optimised relief grooves. As a result, ium with material-appropriate in the modular diesel engine system is the new engine is 11 kg lighter than a adaptations; made from gravity-die-cast AlSiCu3 comparable grey cast iron three-cylinder :: Dedicated coolant circuit for rapid alloy, makes a major contribution to and no less than 27 kg lighter than the component warm-up; weight reduction, 3. The cylinder sur- 1.6 l TDI engine.

❷ Modules with ­synergies and new modules

40 www.autotechreview.com head can be produced extremely econom- ically on the same production line as the four-cylinder unit.

CHARGE-AIR COOLING

Like all engines in the modular diesel engine system, the new three-cylinder also has a water-cooled , 6. In contrast to the four-cylinder engines, incorporation into the ’s smaller vehicle platforms means

❸ Crankcase that the intercooler had to be positioned on the transmission side of the cylinder head. The radiator block of the intercooler BALANCER SHAFT, CRANKSHAFT MDB. The valve-gear components were all is made from a total of seven horizontally DRIVE AND OIL SUMP carried over one-to-one. The cooling con- stacked flat aluminium tubes. Turbulence cept with the newly introduced thermal elements between, and indentations A balancer shaft rotating at engine management was also integrated, with a inside the tubes, lead to a considerable speed in the opposite direction to the two-part water jacket as its basis. improvement in heat transfer from the crankshaft is used to balance out the The straight symmetrical layout of the charge air to the coolant. The plastic air free moments of inertia. To reduce fric- valve star means that the intake and boxes are crimped together with the tion, the balancer shaft is integrated exhaust valves are respectively aligned. cooler package. into a combination module consisting of The parallel valve positioning and an the oil and vacuum pumps, 4. This intake channel arrangement optimised combined module is driven by a single- for minimum pressure loss leads to a COUPLED LOW-PRESSURE AND speed 1:1 gear drive with an acousti- higher degree of cylinder fill. The desired HIGH-PRESSURE EGR cally-optimised tooth profile. swirl level is assured by swirl cham- The crankshaft’s rotational moment of fers with targeted adaptations to the port The layout of the exhaust-gas aftertreat- inertia is minimised via optimised mass geometry, as well as an adjustable intake ment with NOx storage catalyst, DFP and balancing, incorporating the vibration manifold. The coolant circuit in the cyl- dual-circuit exhaust gas recirculation is damper and flywheel. This also reduces inder head facilitates needs-based adap- the same as that of the four-cylinder Euro the weight of the crankshaft. tation of the intake and exhaust ports to VI engine [5]. The cooled low-pressure The oil and vacuum pumps were - suit further possible power and emis- EGR system (LP EGR) on the exhaust side ried over as components from the four- sions requirements. is thus enhanced by a non-cooled high- cylinder TDI engine. Oil supply is via a The conceptual carry-over of the verti- pressure EGR system (HD EGR) with a vane-type pump with a regulated volu- cal intake flange from the four-cylinder valve on the transmission side. Because metric flow rate. In addition, a magnetic engine, as well as its drilling and fasten- the intercooler is located at the side of the valve (controlled by mapping specifically ing concept, means that the new cylinder engine for packaging reasons, the arrange- for three-cylinder engines) can be used to switch between low-pressure and high- pressure operation. The two-part oil sump features a strengthened pressure-die-cast aluminium upper part that helps to stiffen the engine/ transmission assembly. The lower section of the sump is made from sheet metal. Its special contours and higher ductility compared with cast components result in greater safety under contact with the road surface or foreign objects.

CYLINDER HEAD

The cylinder head, 5, too, is derived from the four-cylinder engine family of the ❹ Combination module autotechreview September 2014 Volume 3 | Issue 9 41 Cover Story DIESEL ENGINES

losses is particularly important, when it comes to meeting the extremely strin-

gent restrictions on CO2 emissions in the geographical operating regions for a three-cylinder diesel engine, and plays a major role in the achievement of fuel consumption targets. Starting with the 1.2 l TDI three-cylin- der engine, the increase in displacement to 1.4 l was achieved by lengthening the stroke from 80.5 mm to the 95.5 mm familiar from the 2 l four-cylinder TDI engine. Systematic optimisation of the pis- ton assembly in respect of piston clear- ❺ Cylinder head ance, ring tension and ring contour more than compensated for the disadvantages of the less optimum stroke/ con-rod ratio. ment differs from that of the four-cylinder injectors, such as the use of a more A further reduction of the external Euro VI engine with the HD EGR feed powerful magnet coil and optimisation drive power is achieved via modifications positioned after the intercooler but before of the needle seat, have further to the timing gear, resulting from a reduc- the intake manifold. increased robustness for use in global tion in the number of toothed-belt guides markets. Appearing here for the first and pulleys, as well as a friction-opti- time is the so-called Cylinder Counter mised high-pressure pump. Modified cam- INJECTION SYSTEM Pressure Compensation (CCP) software shaft bearings in the new, one-piece, mod- function, which contributes to an addi- ular camshaft mounting frame reduce A strategic development objective for the tional improvement in injection preci- losses in the valve gear. entire modular diesel engine system was sion at relatively low cylinder back pres- The integration of the balancer shaft the fundamental compatibility of injec- sures and in regeneration cycles. with the oil and vacuum pumps into a tions systems from a range of different Combined with the aforementioned compact combined module negates the providers with all engines in the modular layout of the port geometry and valve need for a separate drive for the balancer diesel engine system, regardless of cylin- arrangement in the cylinder head, the shaft. The regulated oil pump incorpo- der number. The new three-cylinder TDI measures cited above lead to a significant rated into this module is specific to engine features the injection system called reduction of untreated emissions from the three-cylinder application, which also DFS 1.20 from Delphi with 2,000 bar of 1.4 l engine compared with the preceding reduces the power required to drive it. system pressure and seven-hole nozzles 1.2 l model. The water pump with a variable volu- with a flow rate of 500 mm3/60 s at 100 metric flow rate enables not just shorter bar test pressure. Reduction in the leakage warm-up times for the cooling system, rate at the DFI 1.20 solenoid valve injector FRICTION but also makes it possible to reduce to a has led to CO2 benefits in fuel metering. minimum the power consumption of the A number of adjustments to the A significant reduction in frictional pump, when running. A comparison of total engine drag shows that the measures cited led to an improvement of around 20 % compared with the preceding, lower-displacement version of the three-cylinder engine, 7.

NVH ANALYSIS

The new three-cylinder TDI engine her- alds the first application of an aluminium crankcase for the entry-level engines in Volkswagen’s modular diesel engine sys- tem. The new crankcase material meant that the objectives set for acoustic comfort necessitated intensive development work to ensure sufficient casing stiffness and to ❻ Charge-air assembly avoid any loss of acoustic comfort that

42 www.autotechreview.com might impact the customer. Further activi- the generation of disruptive tonal and pul- misation. Taken together, all of the meas- ties for minimising noise generation con- sating sound. Modifications to the timing ures achieve highly effective damping of centrated on the drive for the balancer gear in respect of tensioner positioning airborne noise from the driveline across shaft and the timing gear. and the aforementioned changes to the the entire rev range, 8. Extensive experimental structural anal- roller arrangement also have a positive ysis was carried out and measures for impact on acoustics. improvement of casing stiffness developed Beyond this, an extensive package of POWER AND TORQUE and implemented to ensure the lowest measures has reduced the emission of air- possible noise emissions from the crank- borne and structure-borne noise and The new 1.4 l three-cylinder TDI engine case, despite the change of material to improved vibration dampening. In partic- marks a significant upward expansion in aluminium. Using NVH calculations, an ular, intensive adaptation work was car- the power on offer within the three-cylin- optimum distribution of ribs is achieved ried out on the engine mounts and the der segment, 9. While the preceding on both the inside and outside of the cas- dual-mass flywheel to guarantee good engine was offered only with an output of ing. The noise-emitting surface of the decoupling of the body shell and trans- approximately 74 hp, the range now con- crankcase is thus beneficially divided into mission from the engine across the entire sists of three variants up to a maximum of several smaller, unevenly sized surfaces. frequency spectrum. To reduce noise close to 103 hp with a peak torque of up The tooth geometry and number of emission in the engine bay, there is also to 250 Nm. The ideal torque range, with teeth were optimised as a result of investi- an oil-sump baffle, an acoustically effec- more than 90 % of maximum torque, is gations carried out on the balancer-shaft tive design cover and an engine-mounted available across a broad rev range as of drive. The outcome effectively prevents air-filter box with extensive acoustic opti- 1,500 rpm in all engine versions. The per- formance benefits of the new 1.4 l engine are particularly evident in the 74 hp ver- sion. At 210 Nm, the maximum torque exceeds that of its predecessor by 30 Nm and is reached considerably earlier at just 1,500 rpm. This variant with the lowest output has undergone an increase in torque disproportionate to displacement of more than 30 % at the frequently used lowest end of the rev range, which is par- ticularly relevant to pulling away.

PERFORMANCE AND FUEL CONSUMPTION

Intensive refinement work on flow

❼ Comparison of engine drag at 1600 rpm and 90 °C oil temperature paths, charge cycling and the combus- (schematic; overall improvement around 20 %) tion process in the new three-cylinder engine has resulted in improved turbo- charger response and high-torque power delivery in every power variant. In the new Polo, this led to an improvement in the elasticity figures for all the diesel engines, combined with a decrease in fuel consumption compared with the equally powered predecessor. Perfor- mance optimisations in the 74 hp power variant are particularly notable. The 66 kW (88 hp) version marks Volkswagen’s first use of a three-cylinder TDI engine in combination with its well- known seven-speed DSG dual-clutch transmission. The shift programme is designed for a very low-revving driving style and, alongside the vehicle-based fuel-consumption measures (BlueMotion

❽ Sound output with and without engine-related acoustic measures Technology), is a key factor in the CO2 autotechreview September 2014 Volume 3 | Issue 9 43 Cover Story DIESEL ENGINES

three-cylinder engine fulfils the Euro VI emissions standard and, due to its mod- ular structure, can be adapted to comply with further emissions legislation. With the new three-cylinder TDI engine, Volkswagen has created a uni- versal basis for application across the Group's small vehicle segments. By establishing the MDB, slimming down the engine programme and incorporat- ing it into the modular diesel engine system, effort and cost have been reduced significantly compared with the previous engine ranges. The objectives set for the new engine and laid out at the beginning of this article have thus been fulfilled in their entirety.

REFERENCES [1] Neußer, H.-J.; Kahrstedt, J.; Jelden, H.; En- gler, H.-J.; Dorenkamp, R.; Jauns-Seyfried, S.; ❾ Power and torque curves for the 55 kW, 66 kW and 77 kW versions of the new 1.4-l three-cylinder engine Krause, A.: The New Modular TDI Generation from (EA288) versus the preceding engine with 55 kW (EA189) Volkswagen. 33rd International Vienna Motor Sym- posium, 2012 [2] Neußer, H.-J.; Kahrstedt, J.; Jelden, H.; Dorenkamp, R.; Düsterdiek, T.: The Euro 6 En- decrease of 19 g/km compared with its of the development process were a con- gines from Volkswagen’s Modular Diesel Engine preceding four-cylinder engine variant. siderable weight reduction compared with System – Innovative Close-to-engine Exhaust Gas Despite the greater demands set by emis- the preceding engine, combined with Treatment for Further Reduction of NOx and CO2. 34th International Vienna Motor Symposium, 2013 sions legislation and increased comfort exceptionally low fuel consumption and [3] Rudolph, F.; Hadler, J.; Engler, H.-J.; Krause, expectations, all the engine variants with improved performance. A.; Lensch-Franzen, C.: The New 1.2-l TDI from manual transmissions also boast signifi- As it currently stands, the new Volkswagen – Innovation with 3 Cylinders for Ex- tremely Low Fuel Consumption. 31st International cantly lower CO2 emissions than the out- engine has been developed for an out- Vienna Motor Symposium, 2010 going versions, ❿. put range of 74 to 103 hp, thus enabling [4] Rudolph, F.; Hadler, J.; Engler, H.-J.; Krause, it to replace four-cylinder engines with A.; Stamm, M.: The New 1.6-l TDI Engine from low specific power. It marks the first use Volkswagen. 30th International Vienna Motor Sym- posium, 2009 CONCLUSION of a pressure die-cast aluminium crank- [5] Neußer, H.-J.; Kahrstedt, J.; Dorenkamp, R.; case optimised for stiffness and weight. Jelden, H.: The Euro 6 Engines from the Volkswa- Within the scope of the Volkswagen The extremely compact design makes it gen Modular Diesel Engine System. In: MTZ 74 (2013), No. 6 brand’s engine strategy, the modular die- particularly suitable for use in the Volk- sel engine system (MDB) has been swagen Group’s small vehicle platforms, enhanced with a new, universally applica- where there are high demands for espe- ble three-cylinder engine. The focal points cially low CO2 emissions. The new

55 kW 66 kW 77 kW BlueMotion With DSG Acceleration [s] : 0-80 km/h 8.6 8.6 7.4 7.4 6.9 : 0-100 km/h 12.9 12.9 10.9 10.9 9.9 Elasticity 80-120 km/h [s] : 4th gear 12.0 12.0 9.5 – 9.0 : 5th gear 15.5 15.0 13.0 – 12.5 Top speed [km/h] : 5th gear 173 178 184 184 194

CO2 emissions [g/km] 88* 82 88 92 90 *Without start/stop = 94 g/km Read this article on ❿ Fuel consumption and performance data for the new Polo www.autotechreview.com

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