Seminar Report on I-Vtec

Seminar report i-vtec

“intelligent-VALVE TIMING AND LIFT ELECTRONIC CONTROL”

Seminar ReportSubmitted in the partial fulfillment of the requirements for the diploma of

DIPLOMAIN

MECHANICAL ENGINEERINGIn the faculty of Engineering and Technology

Guided By,Prof. Mr.

(Lecturer in Mech. Engg.)

Submitted by,Mr.

Department Of mechanical Engineering

Academic Year 2014-15

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C E R T I F I C A T E

This is to certify that the thesis titled “intelligent- VALVE TIMMING AND

LIFTELECTRONIC CONTROL “represents the bonafide work carried out by --------------submitted

in partial fulfillment of the requirement for the diploma in “Mechanical Engg. “The work has been

carried out in the Department of Mechanical Engg. (An Autonomous Institute Of Govt. Of

Maharashtra) under the guidance of Prof. Mr.----------

Prof.---------------- Dr.-----------

(Seminar Guide.) (HOD of Mech. Dept.)

Dr. ---------------

(Principle)

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ACKNOWLEDGEMENT

Firstly I thank none but one almighty GOD. For showering his mercy and blessing on me and

being with me always, and he is with me hence only I can finished my work successfully. Then I thank

my parents for their blessing, encouragement and moral support.

I would like to take this opportunity to express our deep sense of gratitude and respect to our guide Prof----------------, Lecturer in Mechanical Engineering. It was a great privilege to get his constant inspiration and guidance during our seminar work.

I extend word of thanks to Prof. Dr.-----------, head of the department of Mechanical Engineering and all those teaching and non-teaching staff stood behind to help and support us.

I am also thankful to our beloved principle Dr. ------------for providing all necessary activities and encouraging us throughout the work.

I am highly obliged to entire friends group providing the way in the difficult time.

Thankful I ever remain…………….

Date:

Place: Aurangabad Mr.

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i-VTEC ENGINE

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ABSTRACT

The most important challenge facing car manufacturers today is to offer vehicles that deliver excellent fuel efficiency and superb performance while maintaining cleaner emissions and driving comfort. This paper deals with i-VTEC (intelligent-Variable valve Timing and lift Electronic Control) engine technology which is one of the advanced technology in the IC engine. i-VTEC is the new trend in Honda’s latest large capacity four cylinder petrol engine family. The name is derived from ‘intelligent’ combustion control technologies that match outstanding fuel economy, cleaner emissions and reduced weight with high output and greatly improved torque characteristics in all speed range. The design cleverly combines the highly renowned VTEC system - which varies the timing and amount of lift of the valves - with Variable Timing Control. VTC is able to advance and retard inlet valve opening by altering the phasing of the inlet camshaft to best match the engine load at any given moment. The two systems work in concern under the close control of the engine management system delivering improved cylinder charging and combustion efficiency, reduced intake resistance, and improved exhaust gas recirculation among the benefits. i-VTEC technology offers tremendous flexibility since it is able to fully maximize engine potential over its complete range of operation. In short Honda's i-VTEC technology gives us the best in vehicle performance.

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INDEX

SR.NO

TOPIC NAME PAGE NO.

1. INTODUCTION 082. OBJECTIVE 09

33.

TERMS RELATED TO i-VTEC 3.1 Volumetric Efficiency 3.2 Torque 3.3 Power 3.4 Camshaft 3.6 Engine Breathing 3.7 Electronic Control Unit (ECU)

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44.

VTEC 4.1 Basic VTEC Mechanism 4.2 DOHC VTEC 4.3 SOHC VTEC 4.4 3-Stage VTEC

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5. VALVE TIMING CONTROL (VTC) 196. i-VTEC SYSTEM 207. ADVANTAGES OF i-VTEC SYSTEM 238. DISADVANTAGES OF i-VTEC 239. APPLICATIONS OF i-VTEC SYSTEM 24

110.

CASE STUDY OF ‘HINDA CITY’ 10.1 Specifications OF i-VTEC Engine. 10.2 Performance

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111.

FUTURE TRENDS 11.1 Pneumatic Valve 11.2 VTEC in Turbo 11.3 i-VTEC in Motorcycle

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112.

TOP 10 i-VTEC ENGINES 12.1 B16A 12.2 B16B Type R 12.3 B18C1 12.4 B18C Type R 12.5 C32B Type R 12.6 F20C1 12.6 H22A1

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12.7J37A4 12.8 K20A Type R 12.9 K24A2

13. CONCLUSION 3014. REFERANCE 31

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1. INTRODUCTION

1.1 Definition

An internal combustion is defined ‘as an engine in which the chemical energy of the fuel is released inside the engine and used directly for mechanical work’. The internal combustion engine was first conceived and developed in the late 1800’s. The man who is considered the inventor of the modern IC engine and the founder of the industry is Nikolaus Otto (1832-1891).

1.2 Discovery

Over a century has elapsed since the discovery of IC engines. Excluding a few development of rotary combustion engine the IC engines has still retained its basic anatomy. As our knowledge of engine processes has increased, these engines have continued to develop on a scientific basis. The present day engines have advances to satisfy the strict environmental constraints and fuel economy standards in addition to meeting in competitiveness of the world market. With the availability of sophisticated computer and electronic, instrumentation have added new refinement to the engine design.

From the past few decades, automobile industry has implemented many advance technologies to improve the efficiency and fuel economy of the vehicle and i-VTEC engine introduced by Honda in its 2002 Acura RSX Type S is one of such recent trend in automobile industry.

The VTEC system provides the engine with multiple cam lobe profiles optimized for both low and high RPM operations. In basic form, the single barring shaft-lock of a conventional engine is replaced with two profiles: one optimized for low-RPM stability and fuel efficiency, and the other designed to maximize high-RPM power output. The switching operation between the two cam lobes is controlled by the ECU which takes account of engine oil pressure, engine temperature, vehicle speed, engine speed and throttle position. Using these inputs, the ECU is programmed to switch from the low lift to the high lift cam lobes when the conditions mean that engine output will be improved. At the switch point a solenoid is actuated which allows oil pressure from a spool valve to operate a locking pin which binds the high RPM cam follower to the low RPM ones. From this point on, the valves open and close according to the high-lift profile, which opens the valve further and for a longer time.

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2. OBJECTIVE

The objective of seminar report is;1) To know the VTC system

2) To know the components

3) To understand the construction & working

4) Operations

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i-VTEC SYSTEM:

he latest and most sophisticated VTEC development is i-VTEC ("intelligent" VTEC), which combines features of all the various previous VTEC systems for even greater power

band width and cleaner emissions. With the latest i-VTEC setup, at low rpm the timing of the intake valves is now staggered and their lift is asymmetric, which creates a swirl effect within the combustion chambers. At high rpm, the VTEC transitions as previously into a high-lift, long-duration cam profile.

T

The i-VTEC system utilizes Honda's proprietary VTEC system and adds VTC (Variable Timing Control), which allows for dynamic/continuous intake valve timing and overlap control.

The demanding aspects of fuel economy, ample torque, and clean emissions can all be controlled and provided at a higher level with VTEC (intake valve timing and lift control) and VTC (valve overlap control) combined.

The i stands for intelligent: i-VTEC is intelligent-VTEC. Honda introduced many new innovations in i-VTEC, but the most significant one is the addition of a variable valve opening overlap mechanism to the VTEC system. Named VTC for Variable Timing Control, the

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ACTUAL DIAGRAM OF VALVE IN i-VTEC


current (initial) implementation is on the intake camshaft and allows the valve opening overlap between the intake and exhaust valves to be continuously varied during engine operation.

3. TERMS RELATED TO i-VTEC:

3.1 Volumetric Efficiency

The engine produces a certain force from every power stroke as a result of burning air/fuel expanding. This force generally gets less for every power stroke as the engine revolves faster, as the air/fuel mixture has less time to get sucked into the cylinder. The volumetric efficiency of a engine at a certain speed is the pressure of air/fuel mixture inside the cylinder when the piston has finished sucking in the mixture, as a percentage of the atmospheric pressure. Thus an engine with 80% volumetric efficiency at a certain speed will have a mixture pressure of 80% of atmospheric pressure when the piston is at bottom dead centre after the intake stroke.

3.2 Torque

The torque of an engine is the total force the engine produces at a certain speed. This is a rotating force, but the easiest way to think of torque is to imagine an engine with a drum attached to it, winching up a weight vertically. The torque of the engine is the force that raises the weight The torque of an engine will increase as the engine rotates faster, because the number of power strokes per time period increases. However, the volumetric efficiency of an engine will drop after a certain speed, so each power stroke has less force. The point where the increase in force (from the increased number of power strokes) is equal to the drop in force (because of less efficiency) is the point of peak torque. This occurs anywhere from 2000 - 7000 rpm, depending on the engine. A higher performance engine will generally have a higher efficiency and maintain this longer, so will have peak torque at higher revs. In the case of my B16A VTEC engine, the torque peak is at about 7000 rpm, which is one of the highest of any mass produced vehicle engine.

3.3 Power

The gearbox modifies torque from the engine to torque at the wheels. If one engine produces the same torque as another, but at a higher engine speed, then force at the wheels will be higher for the first engine one the engine speed is converted by the gearbox to the same wheel speed. The power of an engine is the measurement of the torque of an engine at different engine speeds. Going back to our engine winching analogy, it is easy to see that if the engine is geared down so that the drum rotates half as fast, then weight will be raised slower be more weight can be lifted. The peak power point for an engine is the point where, ideally geared, the most force will be available at the wheels. The peak power point will always be above the peak torquepoint. In my B16A engine, the peak power occurs at about 7800 rpm.

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3.4 The Camshaft

The camshaft has a very big influence on engine breathing. The camshaft controls how long the intake and exhaust valves are open, and how high they open. The intake valvesalways open before the piston is at the top of the cylinder (and started sucking) and close after the piston is at the bottom of the cylinder (and stopped sucking). The shape of the cam lobes limits the valve opening and closing to a gradual opening from closed to fully open, then a gradual closing to fully shut. (Otherwise the value train will destroy itself at high speeds) So while the value opens before the cylinder is sucking, it is not open that much. There is a trade off in terms of efficiency with the camshaft. It is possible to open the values earlier, and have the valve open further for a longer period while the engine is sucking in mixture (it works the same for the exhaust). The valve will be open before the piston has reached the top of the cylinder, and some of the mixture will be pushed out of the cylinder but the piston. Because of the momentum effect of the intake mixture, this loss is less at higher revs, and more at lower speeds, when the intake mixture has not much momentum to overcome mixture being forced out of the cylinder.A camshaft that opens the values early and closes them late (called long duration, or ‘wild’ or ‘lumpy’) will be more efficient at higher engine speeds and less efficient at lower engine speeds. A camshaft that opens later and closes earlier (called short duration, or ‘mild’) will be more efficient at lower engine speeds and less efficient at higher engine speeds.

3.5 ECU

The ECU (electronic control unit = the fuel injection computer) is the heart of the engine. Basically the purpose of the ECU is to control fuel injection and ignition for the engine, for all the conditions which the engine can be expected to run under. This is a fairly complicated job considering the number of external factors that can influence the amount of fuel that needs to be injected into the engine, and the rate at which events happen. At 8500 rpm the ECU has to control 280 injector openings/closing per second and 280 ignition signals per second, while coping with 2400 signals from the distributor per second. Plus there are another 16-odd signals and sensor reading from the engine and outside world that ECU needs to know about.

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4. VTEC ENGINE:

VTEC (standing for Variable valve Timing and lift Electronic Control) does Honda Motor Co., Ltd. develop a system. The principle of the VTEC system is to optimize the amount of air-fuel charge entering, and the amount of exhaust gas leaving, the cylinders over the complete range of engine speed to provide good top-end output together with low and mid-range flexibility.

VTEC system is a simple and fairly elegant method of endowing the engine with multiple camshaft profiles optimized for low and high RPM operations. Instead of only one cam lobe actuating each valve, there are two - one optimized for low RPM smoothness and one to maximize high RPM power output. Switching between the two cam lobes is controlled by the engine's management computer. As the engine speed is increased, more air/fuel mixture needs to be "inhaled" and "exhaled" by the engine. Thus to sustain high engine speeds, the intake and exhaust valves needs to open nice and wide. As engine RPM increases, a locking pin is pushed by oil pressure to bind the high RPM cam follower for operation. From this point on, the valve opens and closes according to the high-speed profile, which opens the valve further and for a longer time.

4.1 BASIC V-TEC MECHANISM

The basic mechanism used by the VTEC technology is a simple hydraulically actuated pin. This pin is hydraulically pushed horizontally to link up adjacent rocker arms. A spring mechanism is used to return the pin back to its original position.

To start on the basic principle, examine the simple diagram below. It comprises a camshaft with two cam-lobes side-by-side. These lobes drive two side-by-side valve rocker arms.

134.1 VTEC OPERATION WITH GRAPH


The two cam/rocker pairs operates independently of each other. One of the two cam-lobes are intentionally drawn to be different. The one on the left has a "wilder" profile, it will open its valve earlier, open it more, and close it later, compared to the one on the right. Under normal operation, each pair of cam-lobe/rocker-arm assembly will work independently of each other.

VTEC uses the pin actuation mechanism to link the mild-cam rocker arm to the wild-cam rocker arm. This effectively makes the two rocker arms operate as one. This "composite" rocker arm(s) now clearly follows the wild-cam profile of the left rocker arm. This in essence is the basic working principle of all of Honda's VTEC engines.

VTEC, the original Honda variable valve control system, originated from REV (Revolution-modulated valve control) introduced on the CBR400 in 1983 known as HYPER VTEC. In the regular four-stroke automobile engine, the intake and exhaust valves are actuated by lobes on a camshaft. The shape of the lobes determines the timing, lift and duration of each valve. Timing refers to an angle measurement of when a valve is opened or closed with respect to the piston position (BTDC or ATDC). Lift refers to how much the valve is opened. Duration refers to how long the valve is kept open. Due to the behavior of the working fluid (air and fuel mixture) before and after combustion, which have physical limitations on their flow, as well as their interaction with the ignition spark, the optimal valve timing, lift and duration settings under low RPM engine operations are very different from those under high RPM. Optimal low RPM valve timing, lift and duration settings would result in insufficient filling of the cylinder with fuel and air at high RPM, thus greatly limiting engine power output. Conversely, optimal high RPM valve timing, lift and duration settings would result in very rough low RPM operation and difficult idling. The ideal engine would have fully variable valve timing, lift and duration, in which the valves would always open at exactly the right point, lift high enough and stay open just the right amount of time for the engine speed in use.

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BASIC VTEC PRINCIPLE


4.2 DOHC VTECIntroduced as a DOHC (Double overhead camshaft) system in Japan in the 1989

Honda Integra XSi this used the 160 bhp (120 kW) B16A engine. The same year, Europe saw the arrival of VTEC in the Honda CRX 1.6i-VT, using a 150 bhp variant (B16A1). The United States market saw the first VTEC system with the introduction of the 1991 Acura NSX, which used a 3-litre DOHC VTEC V6 with 270 bhp (200 kW). DOHC VTEC engines soon appeared in other vehicles, such as the 1992 Acura Integra GS-R (B17A1 1.7-litre engine), and later in the 1993 Honda Prelude VTEC (H22A 2.2-litre engine with 195 hp) and Honda Del Sol VTEC (B16A3 1.6-litre engine). The Integra Type R (1995–2000) available in the Japanese market produces 197 bhp (147 kW; 200 PS) using a B18C5 1.8-litre engine, producing more horsepower per liter than most super-cars at the time. Honda has also continued to develop other varieties and today offers several varieties of VTEC, such as i-VTEC and i-VTEC Hybrid.

4.3 SOHC VTEC

As popularity and marketing value of the VTEC system grew, Honda applied the system to SOHC (single overhead camshaft) engines, which share a common camshaft for both intake and exhaust valves. The trade-off was that Honda's SOHC engines benefitted from the VTEC mechanism only on the intake valves. This is because VTEC requires a third center rocker arm and cam lobe (for each intake and exhaust side), and, in the SOHC engine, the spark plugs are situated between the two exhaust rocker arms, leaving no room for the VTEC rocker arm. Additionally, the center lobe on the camshaft cannot be utilized by both the intake and the exhaust, limiting the VTEC feature to one side.

However, beginning with the J37A4 3.7L SOHC V6 engine introduced on all 2009 Acura TL SH-AWD models, SOHC VTEC was incorporated for use with intake and exhaust valves. The intake and exhaust rocker shafts contain primary and secondary intake and exhaust

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DOHC VTEC ENGINE MODEL


rocker arms, respectively. The primary rocker arm contains the VTEC switching piston, while the secondary rocker arm contains the return spring. The term "primary" does not refer to which rocker arm forces the valve down during low-RPM engine operation. Rather, it refers to the rocker arm which contains the VTEC switching piston and receives oil from the rocker shaft.

The primary exhaust rocker arm contacts a low-profile camshaft lobe during low-RPM engine operation. Once VTEC engagement occurs, the oil pressure flowing from the exhaust rocker shaft into the primary exhaust rocker arm forces the VTEC switching piston into the secondary exhaust rocker arm, thereby locking both exhaust rocker arms together. The high-profile camshaft lobe which normally contacts the secondary exhaust rocker arm alone during low-RPM engine operation is able to move both exhaust rocker arms together which are locked as a unit. The same occurs for the intake rocker shaft, except that the high-profile camshaft lobe operates the primary rocker arm.

The difficulty of incorporating VTEC for both the intake and exhaust valves in a SOHC engine has been removed on the J37A4 by a novel design of the intake rocker arm. Each exhaust valve on the J37A4 corresponds to one primary and one secondary exhaust rocker arm. Therefore, there are a total of twelve primary exhaust rocker arms and twelve secondary exhaust rocker arms. However, each secondary intake rocker arm is shaped similar to a "Y" which allows it to contact two intake valves at once. One primary intake rocker arm corresponds to each secondary intake rocker arm. As a result of this design, there are only six primary intake rocker arms and six secondary intake rocker arms.

4.4 VTEC-E

The earliest VTEC-E implementation is a variation of SOHC VTEC which is used to increase combustion efficiency at low RPM while maintaining the mid range performance of non-vtec engines. VTEC-E is the first version of VTEC to employ the use of roller rocker arms and because of that, it forgoes the need for having 3 intake lobes for actuating the two valves—

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4.4 VTEC-E


two identical lobes for non-VTEC operation and one lobe for VTEC operation. Instead, there are two different intake cam profiles per cylinder—a very mild cam lobe with little lift and a normal cam lobe with moderate lift. Because of this, at low RPM, when VTEC is not engaged, one of the two intake valves is allowed to open only a very small amount due to the mild cam lobe, forcing most of the intake charge through the other open intake valve with the normal cam lobe. This induces swirl of the intake charge which improves air/fuel atomization in the cylinder and allows for a leaner fuel mixture to be used. As the engine's speed and load increase, both valves are needed to supply a sufficient mixture. When engaging VTEC mode, a pre-defined threshold for MPH (must be moving), RPM and load must be met before the computer actuates a solenoid which directs pressurized oil into a sliding pin, just like with the original VTEC. This sliding pin connects the intake rocker arm followers together so that now, both intake valves are now following the "normal" camshaft lobe instead of just one of them. When in VTEC, since the "normal" cam lobe has the same timing and lift as the intake cam lobes of the SOHC non-VTEC engines, both engines have identical performance in the upper powerband assuming everything else is the same.

With the later VTEC-E implementations, the only difference it has with the earlier VTEC-E is that the second "normal" cam profile has been replaced with a "wild" cam profile which is identical to the original VTEC "wild" cam profile. This in essence supersedes VTEC and the earlier VTEC-E implementations since the fuel and low RPM torque benefits of the earlier VTEC-E are combined with the high performance of the original VTEC.

4.5 3-STAGES VTEC

3-Stage VTEC is a version that employs three different cam profiles to control intake valve timing and lift. Due to this version of VTEC being designed around a SOHC valve head, space was limited and so VTEC can only modify the opening and closing of the intake valves.

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4.5 THREE STAGES OF ACTUATION OF VALVES


The low-end fuel economy improvements of VTEC-E and the performance of conventional VTEC are combined in this application. From idle to 2500-3000 RPM, depending on load conditions, one intake valve fully opens while the other opens just slightly, enough to prevent pooling of fuel behind the valve, also called 12-valve mode. This 12 Valve mode results in swirl of the intake charge which increases combustion efficiency, resulting in improved low end torque and better fuel economy. At 3000-5400 RPM, depending on load, one of the VTEC solenoids engages, which causes the second valve to lock onto the first valve's camshaft lobe. Also called 4-valve mode, this method resembles a normal engine operating mode and improves the mid-range power curve. At 5500-7000 RPM, the second VTEC solenoid engages (both solenoids now engaged) so that both intake valves are using a middle, third camshaft lobe. The third lobe is tuned for high-performance and provides peak power at the top end of the RPM range.

Vtec system which combines the standard Vtec and Vtec-e concepts to create a high power, fuel efficient valve train.

Utilizes 3 separate Camshaft Profiles. This system operates like Vtec-e closing one valve at low speeds and then opening both valves at a standard lift and duration at a midrange rpm. It then has a high rpm cam which opens both valves aggressively as in standard Vtec.

Like standard Vtec one rocker arm, usually on the highest lift profile, is not attached to a valve so that the highest lift is only used when the system is in operational Vtec range.

In the illustration below the three significant camshaft profiles can be seen. And the sliding pins for each stage are shown as well.

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5. VARIABLE TIMING CONTROL (VTC):

VTC operating principle is basically that of the generic variable valve timing implementation (this generic implementation is also used by Toyota in their VVT-i and BMW in their VANOS/double-VANOS system). The generic variable valve timing implementation makes use of a mechanism attached between the cam sprocket and the camshaft. This mechanism has a helical gear link to the sprocket and can be moved relative the sprocket via hydraulic means. When moved, the helical gearing effectively rotates the gear in relation to the sprocket and thus the camshaft as well.

5. VTC PRICIPLE

The drawing above serves to illustrate the basic operating principle of VTC (and generic variable valve timing). A labels the cam sprocket (or cam gear) which the timing belt drives. Normally the camshaft is bolted directly to the sprocket. However in VTC, an intermediate gear is used to connect the sprocket to the camshaft. This gear, labeled B has helical gears on its outside. As shown in the drawing, this gear links to the main sprocket which has matching helical gears on the inside. The cam shaft, labeled C attaches to the intermediate gear.

The supplementary diagram on the right shows what happens when we move the intermediate gear along its holder in the cam sprocket. Because of the interlinking helical gears, the intermediate gear will rotate along its axis if moved. Now, since the camshaft is attached to this gear, the camshaft will rotate on its axis too. What we have achieved now is that we have move the relative alignment between the camshaft and the driving cam-sprocket - we have changed the cam timing!

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6. i-VTEC SYSTEM:

Diagram explains the layout of the various components implementing i-VTEC. I have intentionally edited the original diagram very slightly - the lines identifying the VTC components are rather faint and their orientation confusing. I have overlaid them with red lines. They identify the VTC actuator as well as the oil pressure solenoid valve, both attached to the intake camshaft's sprocket. The VTC cam sensor is required by the ECU to determine the current timing of the intake camshaft. The VTEC mechanism on the intake cam remains essentially the same as those in the current DOHC VTEC engines except for an implementation of VTEC-E for the 'mild' cam.

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6.1 i-VTEC SYSTEM LAYOUT


The diagrams show that VTEC is implemented only on the intake cam. Now, note that there is an annotation indicating a 'mostly resting (intake) cam' in variations 1 to 3. This is the 'approximately 1-valve' operating principle of VTEC-E. I.e. one intake valve is hardly driven while the other opens in its full glory. This instills a swirl effect on the air-flow which helps in air-fuel mixture and allows the use of the crazy 20+ to 1 air-to-fuel ratio in lean-burn or economy mode during idle running conditions. On first acquaintance, variations 1 and 3 seem identical. However, in reality they represent two different engine configurations - electronic-wise. Variation 1 is lean burn mode, the state in which the ECU uses >20:1 air-fuel ratio. VTC closes the intake/exhaust valve overlap to a minimal. Note that lean-burn mode or variation 1 is used only for very light throttle operations as identified by the full load Torque curve overlaid on the VTC/RPM graph. During heavy throttle runs, the ECU goes into variation 3 Lean-burn mode is contained within variation-2 as a dotted area probably for the reason that the ECU bounces to-and-fro between the two modes depending on engine rpm, throttle pressure and engine load, just like the 3-stage VTEC D15B and D17A. In variation-2, the ECU pops out of lean-burn mode, goes back to 14.7 or 12 to 1 air-fuel ratios and brings the intake/exhaust overlap right up to maximum. This as Honda explains will induce the EGR effect, which makes use of exhaust gases to reduce emissions. Variation-3 is the mode where the ECU varies intake/exhaust-opening overlap dynamically based on engine rpm for heavy throttle runs but low engine revs. Note also that variations 1 to 3 are used in what Honda loosely terms the idle rpm. For 3-stage VTEC engines, idle rpms take on a much broader meaning. It is no longer the steady 750rpm or so for an engine at rest. For 3-stage VTEC, idle rpm also means low running rpm during ideal

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6.2 VALVE ACTUATION DIAGRAM


operating conditions, i.e. closed or very narrow throttle positions, flat even roads, steady speed, etc. It is an idle rpm range. The K20A engine implements this as well.

Variation-4 is activated whenever rpm rises and throttle pressure increases, indicating a sense of urgency as conveyed by the driver's right foot. This mode sees the wild cams of the intake camshaft being activated, the engine goes into 16-valve mode now and VTC dynamically varies the intake camshaft to provide optimum intake/exhaust valve overlap for power.

On i-VTEC engines, the engine computer also monitors cam position, intake manifold pressure, and engine rpm, then commands the VTC (variable timing control) actuator to advance or retard the cam. At idle, the intake cam is almost fully retarded to deliver a stable idle and reduce oxides of nitrogen (NOX) emissions. The intake cam is progressively advanced as rpm builds, so the intake valves open sooner and valve overlap increases. This reduces pumping losses, increasing fuel economy while further reducing exhaust emissions due to the creation of an internal exhaust gas recirculation (EGR) effect.

i-VTEC introduced continuously variable timing, which allowed it to have more than two profiles for timing and lift, which was the limitation of previous systems. The valve lift is still a 2-stage setup as before, but the camshaft is now rotated via hydraulic control to advance or retard valve timing. The effect is further optimization of torque output, especially at low RPMs.

Increased performance is one advantage of the i-VTEC system. The torque curve is "flatter" and does not exhibit any dips in torque that previous VTEC engines had without variable camshaft timing. Horsepower output is up, but so is fuel economy. Optimizing

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6.3 ACTUATION OF HIGH SPEED CAM


combustion with high swirl induction makes these engines even more efficient. Finally, one unnoticed but major advantage of i-VTEC is the reduction in engine emissions. High swirl intake and better combustion allows more precise air-fuel ratio control. This results in substantially reduced emissions, particularly NOx. Variable control of camshaft timing has allowed Honda to eliminate the EGR system. Exhaust gases are now retained in the cylinder when necessary by changing camshaft timing. This also reduces emissions without hindering performance.

7. ADVANTAGES OF i-VTEC:

1) Better Fuel Efficiency.2) High initial torque and relevant high power.3) Lower emission.4) Strong performance.

8. DISADVANRAGES OF i-VTEC:

1) Cost is high.

2) Available in Honda Models only.

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9. APPLICATIONS

Currently i-VTEC technology is available In Honda products;

1) Honda CRV2) Honda CITY 3) Honda Civic4) Honda Amaze5) Honda Mobilio6) Honda Accord

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10. CASE STUDY OF ‘HONDA CITY’:

The new i- VTEC system in Honda CITY 2006 uses its valve timing control system to deliver acceleration performance equivalent to a 2.0-liter engine and fuel economy approximately 6% better than the current 1.7-literCITY engine. During cruising, the new engine achieves fuel economy equivalent to that of a 1.5-liter engine.

In a conventional engine, the throttle valve is normally partly closed under low-load conditions to control the intake volume of the fuel-air mixture. During this time, pumping losses are incurred due to intake resistance, and this is one factor that leads to reduced engine efficiency.

The i-VTEC engine delays intake valve closure timing to control the intake volume of the air-fuel mixture, allowing the throttle valve to remain wide open even under low-load conditions for a major reduction in pumping losses of up to 16%. Combined with friction-reducing measures, these results in an increase in fuel efficiency for the engine itself.

A DBW (Drive by Wire) system provides high-precision control over the throttle valve while the valve timing is being changed over, delivering smooth driving performance that leaves the driver unaware of any torque fluctuations.

Other innovations in the new VTEC include a variable-length intake manifold to further improve intake efficiency and piston oil jets that cool the pistons to suppress engine knock.

In addition, lower block construction resulting in a more rigid engine frame, aluminum rocker arms, high-strength cracked connecting rods, a narrow, silent cam chain, and other innovations make the engine more compact and lightweight. It is both lighter and shorter overall than the current CITY 1.7-liter engine, and quieter as well.

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10.1 SPECIFICATIONS OF i-VTEC ENGINE:

1. Engine type and number of cylinders Water-cooled in-line 4-cylinder2. Displacement 1,799 cc3. Max power / rpm 103 kW (138 hp)/ 63004. Torque / rpm 174 Nm (128 lb-ft)/43005. Compression ratio 10.5:1

10.2 PERFORMANCE:

This new engine utilizes Honda's "VTEC" technology, which adjusts valve timing and lift based on the engine's RPM, but adds "VTC" - Variable Timing Control - which continuously modulates the intake valve overlap depending on engine load. The two combined yield in a highly intelligent valve timing and lift mechanism. In addition to such technology, improvements in the intake manifold, rearward exhaust system, lean-burn-optimized catalytic converter help to create an engine that outputs 103kW (140PS) @ 6300rpm,and provides ample mid-range torque. It also satisfies the year 2010 fuel efficiency standard of14.2km/Land receives the government standard of "LEV”.

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10.2 GRAPH SHOVING THE PERFORMANCE AS SPEED VS TORQUE


11. FUTURE TRENDS:

11.1 Pneumatic Valves

11.2 VTEC TURBOThe VTEC TURBO engine series included gasoline direct-injection, turbocharger,

variable valve motion technology such as VTEC.

The engines were introduced in 19-Nov-2013 as part of the Earth Dreams Technology range, which included 3 displacement capacities (1 liter 3-cylinder, 1.5 litre4-cylinders, 2 liter 4-cylinder).

Initial implementation for European vehicles included 2-litre 4-cylinder engine used in Honda Civic Type R, which included Euro 6 emissions compliance.

11.3 VTEC IN MOTORCYCLEApart from the Japanese market-only Honda CB400SF Super Four HYPER

VTEC, introduced in 1999, the first worldwide implementation of VTEC technology in a motorcycle occurred with the introduction of Honda's VFR800 sport bike in 2002. Similar to the SOHC VTEC-E style, one intake valve remains closed until a threshold of 7000 RPM is reached, and then the second valve is opened by an oil-pressure actuated pin. The dwell of the valves remains unchanged, as in the automobile VTEC-E, and little extra power is produced, but with a smoothing-out of the torque curve. Critics maintain that VTEC adds little to the VFR experience, while increasing the engine's complexity. Honda seemed to agree, as their VFR1200, a model announced in October 2009, came to replace the VFR800, which abandons the V-TEC concept in favor of a large capacity narrow-vee"unicam", i.e., SOHC, engine. However, the 2015 VFR800 will again sport the same VTEC system of the 2002-2009 VFR motorcycle.

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The valve spring pocket is replaced with a chamber

pressurized with a gas (usually nitrogen because it is

less temperature-sensitive than O2)

Still use traditional camshafts

The system has been used in Formula 1 racing since

1980s

Allows higher RPMs – valve springs have to be very

stiff to allow high RPMs which creates more engine

drag and slower valve timing.

BASIC CONCEPT OF PENUMATIC VALVE IN i-VTEC


Honda incorporated the technology into the NC700 series, including the NC700D Integra, released in 2012, using a single camshaft to provide two timing routines for the intake valves.

12 TOP 10 i-VTEC ENGINES:

If you're thinking of picking up your first Honda project or are ready to pull the trigger on a swap and can't decide which engine is going to be right for you, then check out this quick, basic guide to some of the best options available.

i. B16A

Origin: 1989-1993 JDM Integra XSi, RSi; 1989-1991 JDM Civic/CRX SiRHorsepower/Torque: 160hp/112lb-ftBut why?: It's the first DOHC VTEC engine that you could afford.

ii. B16B Type R

Origin: 1997-2000 JDM Civic Type RHorsepower/Torque: 185hp/118lb-ftBut why?: A de-stroked version of Honda's B18C, the B16B boasts an amazing, high-RPM friendly rod/stroke ratio.

iii. B18C1

Origin: 1994-2001 Integra GS-RHorsepower/Torque: 170hp/128lb-ftBut why?: The B18C1 was Honda's first 1.8L VTEC engine and the first production engine to feature a dual-stage intake manifold.

iv. B18C Type R

Origin: 1995-2001 JDM Integra Type RHorsepower/Torque: 200hp/137lb-ftBut why?: It's Honda's most powerful B-series. What's not to like?

v. C32B Type R

Origin: 2002-2005 JDM NSX-RHorsepower/Torque: 290hp/224lb-ftBut why?: A meticulously balanced and blueprinted version of Honda's standard NSX engine, the Type R isn't just expensive, it's also nearly impossible to source.

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vi. F20C1

Origin: 2000-2005 S2000Horsepower/Torque: 240 hp/153lb-ftBut why?: Considered by many to be Honda's most impressive four-cylinder to date, the F20C1 features amazing RPM capabilities without sacrificing mid-range power.

vii. H22A1

Origin: 1993-1996 Prelude VTECHorsepower/Torque: 190hp/158lb-ftBut why?: Honda's first big-block engine, the H22A1 helped secure a number of drag racing records and went on to make Honda history.

viii. J37A4

Origin: 2009-2013 TL SH-AWDHorsepower/Torque: 305hp/273lb-ftBut why?: It's Honda's most powerful production engine to date. What more do you want?

ix. K20A Type R

Origin: 2001-2005 Civic Type R and Integra Type RHorsepower/Torque: 212hp/149lb-ftBut why?: At 212hp, it's the top-of-the-line K-series for engine swappers.

x. K24A2

Origin: 2004-2008 TSXHorsepower/Torque: 205hp/164lb-ft

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13 CONCLUSION:

1. i-VTEC system is more sophisticated than earlier variable-valve-timing systems, which could only change the time both valves are open during the intake/exhaust overlap period on the transition between the exhaust and induction strokes.

2. By contrast, the i-VTEC setup can alter both camshaft duration and valve lift .i-VTEC Technology gives us the best in vehicle performance.

3. Fuel economy is increased, emissions are reduced, derivability is enhanced and power is improved.

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14 REFERANCES:

a. Deccan Honda, Service Centre, Waluj Aurangabad.b. Mr. Santosh Gade (service manager Deccan Honda)c. Mr. Bodkhe Sir (worker)d. Wikipedia,e. (www.wikipedia.com/ivtec)f. Street Magazine,g. (www.streetmagazine.com)h. Delphi Variable Cam Phases. 2014. 1 May 2014

http://www.delphi.com/manufacturers/auto/powertrain/gas/valvetrain/vcp/ i. VANOS. 2007. 1 May 2007. http://www.bmw.dk/teknisk/en_artikkel.asp?id=5 j. Different Types of VVT. 2005. 3 May 2014.

http://www.autozine.org/technical_school/engine/vvt_2.htm k. Honda Worldwide. 2014. 1 May 2014. http://world.honda.com/motorcycle-

technology/vtec/img/p3_04.jpg l. VTEC . 2014. 1 May 2014.

http://www.luk-korbmacher.de/Autos/Technik/vtec.htm m. BMW Valvetronic. 2014. 4 May 2014. http://youtube.com/watch?

v=rEELtXVTymU

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Seminar Report on I-Vtec

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