multi air engine seminar report @vishalchauhan

SEMINAR REPORT MULTI AIR ENGINE

ASeminar Report

ON“ MULTI AIR ENGINE ”

Submitted to Submitted by AKARSH RAJ NIGAM VISHAL KUMAR SEMINAR COORDINATOR(ME) (1450140044)


STUDENT’S DECLARATION

I hereby, which is being presented in the Seminar Report, entitled “MULTI AIR ENGINE” in partial fulfillment of the requirement for the award of Degree of B.Tech in Mechanical Engineering, submitted in the Department of Mechanical Engineering of R.V.INSTITUTE OF TECHNOLOGY BIJNOR Affiliated to Dr.Abdul kalam Technical University (AKTU), Lucknow, Uttar Pradesh, is an authentic record of my work under the supervision of Mr.Akarsh Raj Nigam.

The results embodied in this report have not been submitted by me or any body else to any other University or Institute for the award of Degree.

VISHAL KUMAR1450140044

CERTIFICATE

This is to certify that the above statement made by the Student is correct to the best of our knowledge.

ER.AKARSH RAJ NIGAM ADITYA SACHAN Seminar Co-ordinator HOD, ME


AcknowledgementApart from the efforts of me, the success of any seminar report depends largely on the

encouragement and guidelines of many others. Firstly my special thanks to Mr.

AKARSH RAJ NIGAM Sir. I take this opportunity to express my gratitude to the

people who have been instrumental in the successful completion of this report.

I can’t say thank you enough for his tremendous support and help. I feel motivated and

encouraged every time I attend his meeting. Without his encouragement and guidance

this report would not have materialized.

The guidance and support received from all the members who contributed and who are

contributing to this report, was vital for the success of the report. I am grateful for their

constant support and help.


INDEX

1.1.Introduction&Features

2.1.history and other systems

3.1.Multi air modes & Development of the fait multi air system

4.1.Working Of Multi air technology

5.1.Futher potential of multi air technology

6.1.Difference between multi air and existing variable valve timing systems

7.1.Benefits Of Multi Air Technology

8.1.Conclusion

9.1.References


1.INTRODUCTION

Multiair is a fundamental breakthrough in petrol engine design that will dramatically cut fuel consumption, as well as significantly boosting power and torque, cutting carbon dioxide emissions by between 10 and 25 percent, and up to a 60 percent reduction in other engine pollutants.

•This higher output will allow Fiat to replace larger engines with smaller, more efficient ones, and the company's 1.0 liter and 1.4 liter engines will be the first to get the new technology, along with a new 900cc twin

Fiat Group was one of the first manufacturers to adopt what has become the increasingly common practice of improving official fuel economy and CO2 emissions by creating a small forced-induction engine which uses fuel at a modest rate when the turbocharger isn't operating but produces similar power to a much larger unit when it is. In 2010, it has taken the idea a stage further by introducing various versions the 1.4-litre MultiAir petrol engine to the Punto Evo and Alfa Romeo MiTo ranges.

In the Geneva Auto Show to launch a new engine technology which could ultimately be as important as the common rail diesel technology it invented 15 years ago. Dubbed MultiAir, the hydraulically-actuated variable valve timing (VVT) technology was first announced as a concept two years ago, and offers a more controllable flow of air during the combustion cycle in comparison with mechanical VVT systems. Vastly reduced fuel consumption and emmissions plus significantly more power are claimed, and the technology is even more effective when used with a supercharger or a diesel engine.

Fiat claims Multiair is a fundamental breakthrough in petrol engine design that will dramatically cut fuel consumption, as well as significantly boosting power and torque, cutting carbon dioxide emissions by between 10 and 25 percent, and up to a 60 percent reduction in other engine pollutants.

This higher output will allow Fiat to replace larger engines with smaller, more efficient ones, and the company's 1.0 liter and 1.4 liter engines will be the first to get the new technology, along with a new 900cc twin cylinder engine.

Unlike the common rail diesel technology, which it sold to Bosch during a financial crisis, and has regreted ever since, FIAT will not be relinquishing


ownership of the new Multiair system, having announced it will license it to other manufacturers or provide entire engines.

Features The application of the Multiair technology offers the potential to improve almost all the critical areas of SI engines:

Throttleless load control reduced fuel consumption

Optimal charge trapping efficiency increased performance

Fast and direct valve control improved dynamic response and fun to drive

Advanced combustion control reduced fuel consumption and emissions Performance and driveability increase potential is significant, thanks to:

Torque and power increase, due to optimal volumetric efficiency over the whole engine speed range, increasing both torque and


History

Multi-Air technology was patented in 2002 and introduced in Europe in 2009 on the Alpha Romeo MiTo. The first U.S. application was the 1.4-liter Multi-Air engine in the 2010 Fiat 500 along with a turbocharged version for the 500 Abarth. A 2.4 liter Tigershark engine with Multi-Air is available in the Dodge Dart and Jeep Cherokee. Current Multi-Air engines are port fuel injected and do not use EGR valves or cam phasing systems.

Multi-Air technology can be adapted to many different engine designs and allows Fiat the opportunity to license the technology to other manufacturers. Multi-Air benefits include increased power and torque, reduced fuel consumption, faster throttle response, reduced CO2 emissions and lower pumping losses. All of the benefits are due to instantaneous, fully variable intake valve lift and timing control. Intake valve actuation is no longer directly controlled by the intake cam lobe profile but rather by electrical control of the hydraulic actuator. Let’s take a closer look at exactly how the intake valve really works.

Other systems Currently ready alternatives to industrialization do not exist, but there are under development also totally camless systems. The Valvetronic system used by BMW allows the valve timing and lift to be varied but not the cam profile. The ability to vary the latter is characteristic of camless and the Multiair systems.

Multi-Air ModesAny fault the prevents the circuit from working such as a failed PCM fuse or relay may cause a cranking no-start that mimics an engine with no compression, like a broken timing belt. This computer control of intake valve actuation allows for a number of unique Multi-Air control modes which are, Full Lift, EIVC (early intake valve closing), LIVO (late intake valve opening), Multi Lift (multiple valve opening events) and No Lift (no valve opening). Full Lift mode is used when maximum engine power is requested or when there is a stored engine fault such as a misfire code. In full lift mode the solenoid is commanded on before the intake cam lobe contacts the hydraulic pump roller follower and remains energized during the entire cam lobe duration providing maximum valve lift and duration. This mode is seldom in use as was seen during extensive test driving of Multi-Air equipped vehicles.

EIVC mode is used extensively while driving and can be used as a primary load control mode that allows for less throttle control by the throttle body. The PCM determines the required engine torque and will close the intake valve once the necessary air mass has


been inducted into the cylinder, thus you can think of this as throttling via the intake valve. It can be seen while driving that during light engine load there is very little vacuum in the intake manifold thus lowering intake pumping losses and making the engine more efficient.

The two scan data captures (Figures 1 and 2) are from a Fiat 500 and show how as the engine is warming up it operates in LIVO mode and the intake pressure closely follows the throttle angle as in all throttled engines. After frame 220 as the engine accelerates, it changes to EIVC mode and the intake manifold pressure remains high at about 12.5 PSI (3.5 in.hg.) and no longer mirrors the throttle angle. Similar to how BMW targets a small vacuum level in the intake manifold on valvetronic equipped engines, the approximately 3.5 inches of mercury vacuum seen in Multi-Air engines appears to be a target level and allows for crankcase ventilation and charcoal canister purging. Due to this relatively high manifold pressure, or lack of intake vacuum, the engine is equipped with a camshaft driven vacuum pump to assist the vacuum brake booster.

The LIVO mode is used primarily at idle and low engine speeds. By delaying activation of the oil control solenoid some or most of the valve lift profile is lost depending on how late activation occurs. This allows for no valve overlap and very smooth idle and low speed operation. Any chance of charge dilution with exhaust gases from valve overlap are not possible and no EGR effect occurs with LIVO so it can only be used at idle or very light load.

Multi-Lift mode is a combination of EIVC and LIVO and can be used to increase valve open duration with small valve opening levels. Multi-Lift

Figure 1: Scan data graph with cursor showing how manifold vacuum follows throttle angle in LIVO mode.

Figure 2: Scan graph showing the change to EIVC mode and manifold pressure remaining high at light load.

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may allow for good charge motion that may prove helpful if GDI is adapted to these engines. No-Lift mode would allow complete cylinder de-activation and would be helpful on larger V6 or V8 engines. As of this writing Multi-Lift and No Lift modes are not in use on current engines but may be implemented in future applications.

Oil Control SolenoidThe oil control solenoid is precisely controlled and closely monitored by the PCM and produces a unique current signature. By scope testing the oil control solenoid a better understanding of system operation can be gained. It must be understood that regardless of when the solenoid is turned on or off the valve movement is still dependent on the intake cam profile stroking the oil pump and producing oil pressure that can be applied to the hydraulic brake/pumping actuator. You cannot confuse solenoid activation current with intake valve movement as sometimes the solenoid is activated ahead of when the cam actually moves the follower.

When scope testing the oil control solenoid, the solenoid on-time may be longer in engine degrees of rotation than the listed intake cam lobe duration but the cam lobe moving the pump is what causes valve movement. The oil control solenoid is a low resistance solenoid and uses a peak and hold current control strategy. The first waveform seen (Figure 2) was taken from a known good rental vehicle and shows a peak current of about 10 amps with a hold current at 5 amps. The solenoid is similar to a GDI injector in that both wires are controlled by the PCM with no shared connection between all 4 cylinders. The solenoid feed wire is biased at 8 volts and pulsed to 12 volts for current control while the ground wire is also biased at 8 volts then held to ground while the solenoid is energized.


By adding rotation rulers to the waveform framing the cylinder ignition firing event you can see the current waveform hold section shows the solenoid was energized for 241 degrees of crank rotation (Figure 3). The engine was running in LIVO mode at the time. The turn-off event of the current waveform happens much sooner in EIVC mode and can be seen in the third waveform capture (Figure 4).

DiagnosticsDue to close monitoring of the Multi-Air system, diagnosis of the system is highly DTC driven. There are extensive circuit codes for the solenoids that allow not only

electrical fault identification but also hydraulic system problem diagnosis. There is a P1523 code for low oil pressure in the Multi-Air brick. By monitoring overall manifold vacuum, vacuum pulsations and RPM fluctuation during cranking the PCM can determine if the intake valves are operating.

Figure 3: Scope test with Multi-Air solenoid low voltage circuit on bottom, solenoid feed voltage circuit above that and solenoid current above that. Cylinder #1 ignition firing is the top pattern.

Figure 4: Rotation rulers used to measure Multi-Air solenoid on time in crank rotation degrees.

Figure 5: Multi-Air solenoid waveform showing EIVC mode and early solenoid turn-off.





The engine must be cranked for 10 seconds to set this code and no theft codes must be present as active SKIM codes may cause the PCM to disable the oil control solenoids yet the parameters for the P1523 code are still monitored. No MAP sensor codes can be present for this code test to run. To prove out the reliability of the self- diagnostics some experiments were performed. Using small diameter 18- gauge jumper wires to add some resistance to the solenoid circuit, the engine was started and the oil control solenoid current tested. Figure 5 shows the setup and the engine had a constant misfire with the jumper wires in place. The current waveform with jumper wires installed can be seen in the following scope capture (Figure 6).

The AC coupled MAP sensor voltage at the top of the waveform confirms there is no intake pull even though there is solenoid current present, but the current level is low. This experiment set 2 codes, a P1041-00 Implausible data from cylinder #1 oil supply solenoid valve received and P1061-00, Cylinder No. 1 oil supply solenoid valve stuck. The system can identify issues but the installed resistance was well below the threshold allowed using an ohmmeter to test the circuit as mentioned in the code chart so scope testing is the best way to identify problems.

Figure 9: Picture of the setup with jumper wires installed for the circuit resistance experiment.

Figure 6: Multi-Air solenoid current with resistance from 18-gauge jumper wires in the circuit.

Figure 7: Multi-Air crankshaft locking tool.

Figure 8: Multi-Air camshaft locking tool.






There are only four serviceable items in the Multi-Air system, the entire Multi-Air “brick,” the roller followers, a screw in oil temperature sensor and the oil supply O-ring between the brick and the cylinder head. While the oil pumping elements and hydraulic brake/pumping elements can be removed from the brick they cannot be purchased separately at this time. Speaking of service, there are a couple of special tools required to perform timing belt service on the engine as there are no timing marks.

There is also a special spring compressor tool to collapse the pumping elements for easier Multi-Air brick removal and installation. The cam timing tools can be seen installed on the engine, the crankshaft locking tool is Miller No. 10276 (Figure 07) and the camshaft locking tool is Miller No. 10277. The spring compressor is Miller No. 10259B. The camshaft locking tool is affixed to the back of the cylinder head once the camshaft driven vacuum pump is removed (Figure 8).

Fiat Multi-Air technology is expected to spread to further applications and will be showing up in your service bays sooner or later. Getting familiar with this innovative technology will keep you ready to service and repair these powertrains when trouble crops up.

Development of the Fiat MultiAir system In the last decade, the development of Common Rail technology for

diesel engines marked a breakthrough in the passenger car market. To be

equally competitive in the field of petrol engines, Fiat Group decided to follow

the same approach and focus on breakthrough technologies.

The aim was to provide customers with substantial benefits in terms of fuel economy and driving pleasure, while maintaining the engine’s intrinsic refinement, based on a smooth combustion process and on light structures and components.

The key parameter to control diesel engine combustion and therefore performance, emissions and fuel consumption, is the quantity and characteristics of the fuel injected into the cylinders. That is the reason why


the Common Rail electronic diesel fuel injection system was such a fundamental breakthrough in direct injection diesel engine technology.

However, the key to controlling petrol engine combustion, and therefore performance, emissions and fuel consumption is the quantity and characteristics of the fresh air charge in the cylinders. In conventional petrol engines the air mass trapped in the cylinders is controlled by keeping the intake valve opening constant and adjusting upstream pressure through a throttle valve. One of the drawbacks of this simple conventional mechanical control is that the engine wastes about 10 per cent of the input energy in pumping the air charge from a lower intake pressure to the atmospheric exhaust pressure.

A fundamental breakthrough in air mass control, and therefore in petrol engine technology, is based on direct air charge metering at the cylinder inlet ports by means of advanced electronic actuation and control of the intake valves, while maintaining a constant natural upstream pressure.

Research on this key technology started in the ’80s, when engine electronic control reached the stage of a mature technology.

At the outset, world-wide research efforts were focused on the electromagnetic actuation concept, by which valve opening and closing is obtained by alternatively energising upper and lower magnets with an armature connected to the valve. This actuating principle had the intrinsic appeal of maximum flexibility and dynamic response in valve control, but despite a decade of significant development efforts, the main drawbacks of the concept – it being intrinsically not fail-safe and its high energy absorption – could not be fully overcome.

At this point most automotive companies fell back on the development of the simpler, robust and well-known electromechanical concepts, based on valve lift variation through dedicated mechanisms, usually combined with camshaft phasers to allow control of both valve lift and phase.

The main limitation of these systems is low flexibility in valve opening schedules and a much lower dynamic response; for example, all the cylinders of an engine bank are actuated simultaneously, thereby excluding


any cylinder selective actions. Many similar electromechanical valve control systems were subsequently introduced over the past decade.

In the mid ’90s, Fiat Group research efforts switched to electro-hydraulic actuation, leveraging on the know-how gained during its Common Rail development. The goal was to reach the desired flexibility of valve opening schedule air mass control on a cylinder-by-cylinder and stroke-by-stroke basis.

The electro-hydraulic variable valve actuation technology developed by Fiat was selected for its relative simplicity, low power requirements, intrinsic fail-safe nature and low cost potential.

MultiAir Technology: how it works

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The operating principle of the system, applied to intake valves, is the following: a piston, moved by a mechanical intake camshaft, is connected to the intake valve through a hydraulic chamber, which is controlled by a normally open on/off solenoid valve.

When the solenoid valve is closed, the oil in the hydraulic chamber behaves like a solid body and transmits to the intake valves the lift schedule imposed by the mechanical intake camshaft.

When the solenoid valve is open, the hydraulic chamber and the intake valves are de-coupled; the intake valves do not follow the intake camshaft anymore and close under the valve spring action.

The final part of the valve closing stroke is controlled by a dedicated hydraulic brake, to ensure a soft and regular landing phase in any engine operating conditions.

Through solenoid valve opening and closing time control, a wide range of optimum intake valve opening schedules can be easily obtained.

For maximum power, the solenoid valve is always closed and full valve opening is achieved following completely the mechanical camshaft, which is specifically designed to maximise power at high engine speed (long opening time).

For low-rpm torque, the solenoid valve is opened near the end of the camshaft profile, leading to early intake valve closing. This eliminates unwanted backflow into the manifold and maximises the air mass trapped in the cylinders. In engine part-load, the solenoid valve is opened earlier,


causing partial valve openings to control the trapped air mass as a function of the required torque.

Alternatively the intake valves can be partially opened by closing the solenoid valve once the mechanical camshaft action has already started. In this case the air stream into the cylinder is faster and results in higher in-cylinder turbulence.

The last two actuation modes can be combined in the same intake stroke, generating a so-called Multilift mode that enhances turbulence and combustion rate at very low loads.

Working Of Fiat MultiAir Technology A piston, moved by a mechanical intake camshaft is connected to the intake valve

through a hydraulic chamber,further controlled by a normally open on/off solenoid valve.

When the solenoid valve is closed the oil inside it acts as a solid and does not involve in the lift schedule imposed by the mechanical intake camshaft

But when its open the hydraulic chamber and intake valve disconnect handing total control over to the valve spring action

The final stage of valve closing stroke is controlled by a dedicated hydraulic brake ensuring smoother landing phase under any operating conditions and with the solenoid mechanism a number of valve opening schedules can be obtained

For Maximum Power: Solenoid valve is always closed and the mechanical camshaft controls the full valve opening

For Low-RPM Torque: Solenoid valve is opened near the end of the camshaft profile which leads to early intake valve closing eliminating air-mass backflow and increasing air-mass trapped in the cylinder

Further Potential of MultiAir Technology


All breakthrough technologies open a new world of further potential benefits, which are usually not fully exploited in the first generation.

Common Rail technology, a Fiat Group worldwide premiere in 1997, paved the way to more than a decade of further technological evolutions such as MultiJet for multiple injections, small diesel engines, and the recent Modular Injection technology, soon to be launched on the market.

Similarly, MultiAir technology will pave the way to further technological evolutions for petrol engines:

Integration of the MultiAir Direct air mass control with direct petrol Injection to further improve transient response and fuel economy. Introduction of more advanced multiple valve opening strategies to further reduce emissions. Innovative engine-turbocharger matching to control trapped air mass through a combination of optimum boost pressure and valve opening strategies.

While electronic petrol injection developed in the ’70s and Common Rail developed in the ’90s were fuel-specific breakthrough technologies, MultiAir Electronic Valve Control technology can be applied to all internal combustion engines whatever fuel they burn.

MultiAir, initially developed for spark ignition engines burning light fuel ranging from petrol to natural gas and hydrogen, also has wide potential for diesel engine emissions reduction.

Intrinsic NOx reduction of up to 60 per cent can be obtained by internal exhaust gas recirculation (iEGR) realised with intake valves reopening during the exhaust stroke, while optimal valve control strategies during cold start and warm-up bring up to 40 per cent HC and CO reduction of emissions. Further substantial reductions come from the more efficient management and regeneration of the diesel particulate filter and NOx storage catalyst, thanks to the highly dynamic air mass flow control during transient engine operation.

Diesel engine performance improvement is similar to that of the petrol engine and is based on the same physical principles. Instead, fuel consumption benefits are limited to few percentage points because of the low pumping losses of diesel engines, one of the reasons for their superior fuel economy.


In the future, powertrain technical evolution might benefit from a progressive unification of petrol and diesel engine designs.

A MultiAir engine cylinder head can therefore be conceived and developed, where both combustion systems can be fully optimised without compromise. The MultiAir electro-hydraulic actuator is physically the same, with minor machining differences, while internal sub-components are all carried over from Fiat’s FIRE and SGE applications.

Difference between MultiAir and existing variable valve timing (VVT) systems


Current VVT systems rely on mechanical systems to open and close the valves. Engineers have long understood the benefits of changing valve opening and closing times to tweak an engine's power and emissions performance, depending on the need for power or parsimony.

Valves are an engine's nose and mouth – it inhales through inlet valves and exhales through exhaust valves. Sounds simple enough, but actually engines are a lot like people. Depending on what they're doing, they need to breathe more or less air and the timing and rate of their breathing needs to vary. Like competitive swimmers who time their breathing to match the stroke, an engine wants to take long deep breaths when it's working hard and short shallow ones when it isn't.

Trouble is, it can't. The ancient method of opening and closing valve, the camshaft, is still in use today because it's simple to make, robust and very effective. Each valve is opened by a rotating cam on the camshaft whose shape and size controls how the valve opens and shuts and when it does so. The valve is closed by a simple spring because, in 100 years, no-one's found a better tool for the job. But what's right for developing high power at high rpm isn't right for that torquey, low-speed slog around town and greater variability of valve opening and closing helps reduce consumption and CO2 emissions too.

A lot of modern engines try to overcome the inadequacies of the traditional valvetrain with phasers to vary the timing of when valves open and shut. They may also have cam profile switching (like the Honda VTEC system), which switches to a hotter cam profile at higher revs. But the effect is limited. If the engine were a swimmer, it would still be gagging to get the right amount of air at exactly the right time, like when its face was under water.

The MultiAir system replaces the twin camshafts of a four-valves-per-cylinder engine. It's so cleverly designed, not only can it be incorporated in new engines, it fits exsiting motors too – so potentially all sorts of engines (not just Fiat's) could use it. The single camshaft opens up all four valves.


Exhaust valves are not variable and are opened in the usual way by mechanical cam lobes. But between the inlet cam lobes and inlet valves are hydraulic chambers from which oil can be released by electronic solenoid valves.

Benefits Of MultiAir Technology A Power-oriented mechanical camshaft increases maximum power by 10 percent Early Intake Valve strategies improve low RPM torque by 15 percent Elimination of Pumping Losses improve fuel consumption cuts down CO2

emissions and fuel consumption by 10 percent MultiAir turbocharged and downsized engines deliver 25 percent better fuel

economy over the conventional naturally aspirated engines enhancing same level of performances

Valve control strategies result in reductions of 40 percent for unburnt hydrocarbons and carbon monoxide (HC/CO), and up to a 60 per cent cut in oxides of nitrogen, (NOx)

Enhanced driving pleasure and a superior dynamic engine response Most importantly the technology could be used for both petrol as well as diesel

engines


.


ConclusionIn short, an engine equipped with MultiAir technology is more powerful, more responsive across the entire engine speed range, uses considerably less fuel, and reduces all types of exhaust emissions by a substantial amount. It will also assist in enabling Fiat to maintain its lead in low emissions and low fuel consumption technology, which has seen Fiat crowned for the past two years as the number one car maker for the lowest range-wide CO2 emissions.

The first new engine to be equipped with MultiAir will be the 16-valve 1.4 litre family of naturally aspirated and turbocharged engines, and the first car to go on sale with MultiAir installed will be the Alfa MiTo at the end of 2009. Its second application will be as an integral part of a new two cylinder engine family.

•The beauty of “Multiair” system is its simplicity; it essentially achieves what Valvetronic does by using hydraulic fluid running through narrow passages connecting the intake valves and the camshaft so the two can be decoupled.

This system is modulated by an electronically controlled solenoid, and there are effectively two modes:

•When the solenoid is closed, the incompressible hydraulic fluid transmits the intake-cam lobe’s motion to the valve, as in a traditional engine.

•When the solenoid is open, the oil bypasses

•For example, to shut the valves early, as in a part-load situation, the solenoid would be closed initially and then open partway through the intake cycle.

•The tricky business is correctly timing the switching of the solenoid, and Fiat has painstakingly optimized the responsiveness of the electronic controls.

•Aside from the fuel-economy and emissions benefits, it is claimed that Multiair can also enable a 10-percent horsepower boost.

•Components of 4WD vehicles can be serviced in basically the same manner as the same components on a 2WD vehicle. •Some AWD vehicles have a third differential, called an interaxle differential, instead of a transfer case.


REFERENCES

1. WWW.GOOGLE.COM2. WWW.WICKYPEDIA.COM3. WWW.HOWSTUFFWORKERS.COM4. WWW.FIAT.IN

THANK YOU

BY VISHAL KUMAR [email protected]