Hyundai Nu engine
In series Nu is four-cylinder petrol engines with double overhead camshaft ( DOHC) and four valves per cylinder. The engines are in South Korea, China and North America in Shandong (China ) were prepared.
General features
The engine block and cylinder head are made of aluminum. The 1.8-liter engine weighs 112 kg. Weights and cylinder dimensions of the other engines are not known, the same applies to the idle speed of the series.
All motors of the nucleotide series are controlled via an electronic accelerator.
The power is transmitted from the crankshaft to the cylinder head by means of maintenance-free timing chain, the ancillaries are driven by a serpentine belt. For this inspection, a replacement is provided from 100,000 km every 25,000 km, only identified need.
The valves are operated in the engines without CVVL via roller cam followers, which act like a seesaw. While one side pushes the valve down, lies on the other thereby stretching the spring by means of built hydraulic tappets flush (cf. valve closed, valve open). Wherein, the cam CVVL technology is applied to a rolling wheel, the friction by pressing on a lever to open the valve. This lever is adjustable and is used for varying the opening time and valve lift. Both forms of the lash adjuster are maintenance free, self- inspection is not provided in the maintenance schedule. An Erosion would notify by a ticking sound (see ).
Nu
The Nu- series adds all the technology that was developed by the producers away from direct injection and turbochargers for its petrol engines up to 2010. However, none of it made her debut with this series, which is why their top-end version was chosen for presentation.
Adapted from its predecessor series, varies a D (ual ) - CVVT named camshaft adjustment, the intake and exhaust sides. It has an effect on the timing of the valve opening from both sides, but not on the valve and thus the opening period. It is therefore comparable to the BMW Double Vanos technology. In addition to better torque in the lower speed range, it reduces mainly nitric oxide levels by the exhaust back leading effect is used a large overlap - this ejected gas is already sucked back into the combustion chamber. The D- CVVT is not always listed because of their seriality.
Dedicated to the air supply is also the variable intake system (Variable Induction System ). This takes account of the pulsation of the air in the intake pipe, which is formed by the opening and closing of the valves. Find these under and over pressure pulses a rhythm adapted their way into the engine compartment, there is a light resonance charging effect, similar to a turbocharger. To achieve it opens at low and high speeds suitable for this purpose, short air. At medium speeds ( 3000-5500 ), the longer air guide is used by means of a flap, resulting in consistently high torque and five percent more power.
While the above technologies with the Theta II series appeared, the offset crankshaft goes back to the Gamma series of 2006. The pistons are constantly pressed by the rotation of the crankshaft of a cylinder wall. An offset of which position one centimeter leaves the pistons now in the ignition phase with less friction slide down. This Friktionsreduzierung lowers next to the consumption, the vibrations. The same procedure used about Toyota Prius.
Not known is the use of friction-reducing coatings on piston and valve actuation, but found in other series engine use and thus likely to remain here only unmentioned.
To reduce costs, this stage remains without adaptation of the stop -start system ISG, which was developed in conjunction with Bosch.
The real consumption ranges from less than 5 to about 9 liters, centered between the U.S. EPA standard of 7.1 l/100 km joins.
Nu hybrid
For South Korea, the motor in the first full hybrid drive manufacturer was replaced with a 2.0L engine, the Nu- series. All other properties remain. The Verbund is now 191 instead of the previous 209 hp. Consumption side, the result is for the time being can not be determined, as the South Korean determining consumption differs significantly from the U.S., with the 209 hp variant has been measured exclusively. The numbers after the consumption of 6.4 decreased to 4.8 liters per 100 km, which exceeds the apparent effect of the exchange of two similar engines.
Nu GDI
Half a year after the Nu- series with this direct injection ( GDI) was fitted and used to market launch of the Hyundai i40 in summer 2011 for the first time. Together with the variable valve CVVL is the Gasoline Direct Injection is a prerequisite for the next homogeneous engines.
In the conventional injection for gasoline engines, the fuel injector is located in the intake manifold before the inlet valve. With increasing speeds, however, the opening time of the valve is getting shorter, and thus the time window for the introduction of the fuel. In the direct injection is therefore injected directly into the cylinder. Hyundai used like most competitors GDI for homogeneous, stoichiometric mixture formation and waives an inhomogeneous stratified ( stratified fuel charge). The latter is associated with systemic disadvantages, such as significantly increased particulate matter levels.
Is initiated with a pilot injection and ignition to move the piston in motion. While downward movement of the thrust -imparting, actual fuel injection and ignition follows. Through this more precise, as it is directly taking place in the cylinder fueling the Kompresssionsrate could be increased in the cylinder. This leads to a fuel saving (see ) and also results in a higher exhaust temperature. Of these, the faster heated catalyst which can thus reduce the emissions during the cold start phase benefited. The higher injection pressure of 150 bar (without GDI about 5 bar ) also causes a more homogeneous fuel atomization and thus a cleaner combustion. He is accompanied by a typical system tick noise (see video at 4:00 ).
Order to reduce consumption of Nu GDI is available with the stop -start system ISG, the effect of l / 100 km is in other vehicles in the standard consumption about 0.2, by their seriality in vehicles with Nu GDI engines but only by manually disabling verifiable is.
Nu CVVL
With the introduction of this variant ended in April 2010, the 44 -month development period of the Nu- number, the cost of 153 million euros should be specifically referred to the CVVL technology. Replacing the dual CVVT technology varies only the valves of the inlet side. All other features are identical to the Nu- series.
When CVVL system of cams is applied to a rolling wheel, the friction by pressing on a lever which then opens the valve. This lever is located on an eccentric shaft, so that its center of rotation is adjustable. A servo motor takes over this task, thus changing the horizontal rotation. In order for the valve ( Valve Lift ), the opening period and the opening time change. These three effects are linked. For a long stroke means a long opening period, as the strokes must be gentle on the material covered with not too rapid accelerations. A longer opening duration also means that the process begins and ends later time. Thus, the timing is changed. An independent variation of the parameters is only possible with a cam-less opening of the valves (see Multiair system). The CVVL system resembles in its construction, however, the BMW Valvetronic, but its elements are arranged differently. Was developed in the CVVL European Group Powertrain Center in Rüsselsheim, its precise structure but so far not disclosed.
By CVVL a throttle valve is unnecessary, which the associated reduced throttling losses. These occur on all elements which deflect the flow of air, including the valves themselves is considered to be the main cause, however, the throttle valve, which controls the intake air. Without it, more air would flow into the cylinder that, by its more of oxygen, the combustion temperature and thus the amount of nitrogen oxides rise above the euro - limits could be at part load. The variable valve lift can now take on even the air control. Thus he spare five and a half percent fuel compared to a Nu- engine without Ventilvariierung, which does not exist, however. The effect of the actual base stage of the series is expected to be between three and four percent.
Hyundai's vice - head of development explains the Nu- number as a link between theta and gamma engines. Especially the former is not architecturally suited for displacement of 1.8 liters. That notwithstanding, the producer did such a version for years in the theta range. The statement should therefore focus on the sustainability, especially fitness for homogeneous mixtures (HCCI ). These require very precise valve timing and fuel injection. With CVVL GDI and the Nu- row satisfies both conditions, albeit so far in separate motors. His first homogeneous motor plans Hyundai / KIA in 2012.
Outlook (Nu HCCI )
The efficiency expectations homogeneous engines are primarily based on their higher compression and low-emission combustion. An increase in compression from the usual today 11:1 to 15:1 and causes an increase in efficiency of about 20 % (see ). This compression, however, usually produces an uncontrolled self-ignition of gasoline. In this "knocking " expands the mixture too early, ie before the piston has completed its way up. This is replaced by a so abrupt braking from above, while being pressed by the crankshaft further upwards. Hence, avoid gasoline engines by means of knock sensors too much compression.
To increase the compression that mixture must be prepared so that it fires at the right time and at several points simultaneously. The latter, in order to achieve clean burning - since unburned fuel missing during excavation. A similar, partially homogeneous combustion already reached gasoline direct injection stratified charge ( " Stratified Injection "). However, they emit large amounts of nitrogen oxides and produce especially during load changes and carbon black as they vary the air flow through the valves little or not at all. Therefore, they require an expensive nitrogen oxide filtering of the exhaust gas, Euro standards, since 2009, also limit the particulate emissions for gasoline. Therefore homogeneous motors operate with a variable valve lift. So suck a larger amount of exhaust gas back into the cylinder and thus regulate the self-ignition. The lack of oxygen in the exhaust gas avoids a premature ignition during which heat allows for compression-ignition only. This requires about 1000 ° K. The combustion takes place at 2000 ° K; due to the low oxygen content of about 600 ° cooler than conventional gasoline engines. The nitric oxide levels fall so to a minimum. Nevertheless, the self-ignition has a disadvantage. The problem is the 36 bar rising already in the partial load range of 24 pressure during the ignition, especially its rapid rise and fall by the eponymous homogeneous, ie simultaneous combustion of all the fuel. Therefore, homogeneous motors operate only at partial load with compression-ignition while they fall back under full load to less compression and a spark plug. The same applies at high engine speeds at which the injectors no longer meet with the homogeneous mixture preparation. Therefore, the choice of a number of major engine displacements for HCCI development is useful because only give this enough power as often as possible in partial load operation to drive ( cf. Dies Otto engine ). The full load would already cause the materials to its limits, more on gasoline adding quite apart from Turboaufladungen with her.
CVVL is therefore necessary to precisely adjust the valves for compression and Abgasrücksaugrate, especially during load changes. Then, it is also changed from ignition to ignition by the spark plug at a low compression to prevent material damage. GDI in turn allows pilot injections. Only thus can the gas be added sequentially to the incoming air and thus accurately distributed in the combustion chamber, which is a prerequisite for auto-ignition.
What is the effect of the homogeneous mode will have once, has not been named by Hyundai / KIA. However, for the classification of HCCI engines is worth noting that European consumption determination can be traversed almost exclusively in the part-load operation. The first engines with a compression ratio of 14:1 HCCI same are the Skyactiv -G - drives of Mazda. However, these do without the auto-ignition, thereby presumably able to maintain the high compression and under full load. For the first time applied such a motor from summer 2011 is in the Mazda 3 facelift.
Data
Use
Listed are the world's Nu built engines for each model, not in every country all listed configurations are offered.
Hyundai Elantra
- Elantra UD / MD G4NB ( 148 hp ): 2010 -present
Hyundai i40
- I40 G4NC ( 177 hp ): 2011 -present
Hyundai Sonata
- Sonata YF G4NE (190 hp ): 2011 -present ( South Korea Only )
KIA Kia Optima
- Optima TF 2.0 CVVL ( 170 hp ) from 2012
KIA Soul
- Soul AM G4NA (164 hp ): 2011 -present ( North America and Canada)