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1
A
Seminar
On
“MULTI-MODE 2/4-STROKE INTERNAL COMBUSTION ENGINE”
By
Mr. MOHAMMED HUSAIN ESMAIL MASALAWALA
Under The Guida...
2
Kalyani Charitable Trust’s
Late G. N. Sapkal College of Engineering
Sapkal Knowledge Hub, Kalyani Hills, Anjaneri, Trimb...
3
CONTENT
ACKNOWLEDGEMENT
ABSTRACT
INDEX
Sr.
No.
Description Page
No.
1 Introduction 6
1.1
1.2
1.3
Increase in demand of I...
4
FIGURE INDEX
FIGURE NO. TITLE PAGE NO.
1.1.1 Increasing demand 6
1.2.1 Scarcity of fuel 7
3.1 Working graph 1 13
3.2 Wor...
5
ACKNOWLEDGEMENT
I take this opportunity to express our deep sense of gratitude and respect towards
our guide MR. C. P. S...
6
ABSTRACT
In a multi-mode, 2-stroke/4-stroke internal combustionengine operation, by
switching the engine stroke from 4-s...
7
1. INTRODUCTION
1.1 INCREASE IN DEMAND OF INTERNAL COMBUSTION ENGINE
Severe traffic congestion and automobile-related he...
8
1.2 SCARCITY OF FUEL
Due to tremendous increase in usage of automobiles the depletion rate of fossil
fuels is increasing...
9
1.3 POLLUTION
Cars and trucks produce air pollution throughout their life, including pollution emitted
during vehicle op...
10
2 AREAS OF INTEREST
2.1 POWER
Firstly automobiles were used only for transportation purpose but now a days all
the yout...
11
Particulate matter (PM). These particles of soot and metals give
smog its murky colour. Fine particles — less than one-...
12
3 TYPES OF ENGINE
3.1 SUCTION IGNITION ENGINE
A petrol engine (known as a gasoline engine in North America) is an inter...
13
3.4 HYBRID ENGINE
Recently, Homogeneous Charge Compression Ignition(HCCI) engines have been
introduced, Which have high...
14
4 CONCEPT OF MULTI-MODE
Fig. 3.1 working graph 1
Fig. 3.2 working graph 2
15
In the above Fig. 3.1 and 3.2 show the comparison of engine operation strategy
between mode switching and mode/ stroke ...
16
Second, the stroke switching is able to be achieved moresmoothly than mode
switching. The temperature range of exhaust ...
17
Fig 3.1 and 3.2 show the valve timing diagrams, i.e., exhaust and intake valve
timings, for different combustion strate...
18
The injection timing and duration should be optimized to ensure that optimal
combustion phasing occurs. It is also poss...
19
5 TECHNOLOGICAL REQUIREMENTS
In accordance With the present invention, the intrinsic loadlimitation of HCCI is
overcome...
20
7 FIELD OF IMPLEMENTATION
1 Diesel engines for combat tanks
Fig. 7.1 Diesel engines for combat tanks
2Diesel engines fo...
21
3 Diesel engines for military heavy trucks
FIG. 7.3 Diesel engines for military heavy trucks
4 Diesel engines for speci...
22
8CONCLUSION
Several projects are developed for different clients. Among them one is the 4-2-
stroke Diesel engine proto...
23
24
25
26
27
28
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a seminar report on multi-mode 2/4 stroke internal combustion engine

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magnetic refrigeration,multi-mode 2/4 stroke internal combustion engine

a seminar report on multi-mode 2/4 stroke internal combustion engine

  1. 1. 1 A Seminar On “MULTI-MODE 2/4-STROKE INTERNAL COMBUSTION ENGINE” By Mr. MOHAMMED HUSAIN ESMAIL MASALAWALA Under The Guidance Of Prof. C. P. SHINDE Submitted In Partial Fulfillment of the Requirement For Bachelor of Engineering (Mechanical)Degree of University of Pune Department of Mechanical Engineering Late G.N. Sapkal College of Engineering, Anjaneri, Nashik-422212 2013-2014
  2. 2. 2 Kalyani Charitable Trust’s Late G. N. Sapkal College of Engineering Sapkal Knowledge Hub, Kalyani Hills, Anjaneri, Trimbakeshwar Road, Nashik – 422 212, Maharashtra State, India CERTIFICATE This is to certify that Mr. MOHAMMED HUSAIN ESMAIL MASALAWALA has successfully completed his Seminaron the topic“MULTI-MODE 2/4-STROKE INTERNAL COMBUSTION ENGINE”, under the able guidance of Prof. C. P. SHINDEtowards the partial fulfillment ofThird YearofMechanical Engineering as laid down byUniversity of Pune during academic year 2013-14. Prof C.P, Shinde. Prof. T.Y. Badgujar [Seminar Guide] [ H.O.D. Mechanical ] Dr. Basavaraj S. Balapgol [Examiner] Principal
  3. 3. 3 CONTENT ACKNOWLEDGEMENT ABSTRACT INDEX Sr. No. Description Page No. 1 Introduction 6 1.1 1.2 1.3 Increase in demand of IC engine Scarcity of Fuel Pollution 6 7 8 2 2.1 Areas Of Interest Power 9 9 3 2.2 2.3 3.1 3.2 3.3 Efficiency Emissions Types Of Engine Suction Ignition Engine Compressed Ignition Engine Homogenous Compressed Charged Engine 10 11 11 11 12 4 3.4 3.5 Hybrid Engine Boosted Engine Concept Of Multi-mode 12 12 13 5 Technological Requirements 18 6 Successive Results 18 7 Field Of Implementations 19 8 Conclusion 21 9 Bibliography 21
  4. 4. 4 FIGURE INDEX FIGURE NO. TITLE PAGE NO. 1.1.1 Increasing demand 6 1.2.1 Scarcity of fuel 7 3.1 Working graph 1 13 3.2 Working graph 2 13 7.1 Diesel engine for combat tanks 19 7.2 I F V 19 7.3 Diesel engine for military trucks 20 7.4 Special purpose vehicles 20
  5. 5. 5 ACKNOWLEDGEMENT I take this opportunity to express our deep sense of gratitude and respect towards our guide MR. C. P. SHINDE, Department of Mechanical Engineering, Late G N Sapkal College Of Engineering , NASHIK. I am very much indebted to his for the generosity, expertise and guidance; I have received from him while collecting data on this seminar and throughout our studies. Without his support and timely guidance, the completion of my seminar would have seemed a farfetched dream. In this respect I find ourselves lucky to have his as our guide. He has guided us not only with the subject matter, but also taught us the proper style and technique of working and presentation. It is a great pleasure for me to express my gratitude towards those who are involved in the completion of my seminar report. I whole-heartedly thank to our HOD Mr. T. Y. BADGUJAR for their guidance. I am also indebted to all Sr. Engineers and others who gave me their valuable time and guidance. The various information and sources I used during my report completion find place in my report. I am also grateful to Senior Seminar Coordinators respected sir’s. MOHAMMED HUSAIN ESMAIL MASALAWALA III year, VSemister Dept. Of Mechanical Engineering (L.G.N.S.COE, Nashik) Magnetic Refrigeration
  6. 6. 6 ABSTRACT In a multi-mode, 2-stroke/4-stroke internal combustionengine operation, by switching the engine stroke from 4-stroke operation to 2-stroke operation so that the combustion frequency is doubled, doubling of the engine power is achieved even at the same work output per cycle. In order to meet the demand of extremely high power, the engine operates in 4-stroke boosted SI operation transitioned from 2-stroke HCCI operation at pre-set level of power and crank speed requirements. By combining the multi-stroke (2-stroke HCCI and 4-stroke HCCI) and multi-mode operation (2-stroke HCCI and 4-stroke boosted SI operation), full load range and overall high efficiency with minimal NOx emission are achieved.
  7. 7. 7 1. INTRODUCTION 1.1 INCREASE IN DEMAND OF INTERNAL COMBUSTION ENGINE Severe traffic congestion and automobile-related health problems will continue to build internationally unless the use of cars is curtailed, according to a study by the World- watch Institute, a United Nations-sponsored group. With nearly 400 million cars in use worldwide and many developing countries aggressively developing ''auto cultures,'' pollution will continue to increase, the study warns, and it questions the wisdom of heavy third-world investment in transportation systems that will serve ''a small, privileged class with ample purchasing power.'' The study recommends that in industrial nations higher taxes be assessed on cars that get low gas mileage and calls for all governments to ''discourage auto use where possible'' in favour of public transportation. ''Government policies favouring private car ownership by a tiny but affluent elite are squandering scarce resources and distorting development priorities,'' said Michael Renner, the study's author. ''In Haiti, for example, only one out of every 200 people owns a car, yet fully one-third of the country's import budget is devoted to fuel and transport equipment.'' Auto Industry Challenges Report Fig. 1.1.1 increasing demand
  8. 8. 8 1.2 SCARCITY OF FUEL Due to tremendous increase in usage of automobiles the depletion rate of fossil fuels is increasing . It has been estimated by USA council of Research in Fuel and Energy Production that if the consumption of fuel would continue the fuel deposits would get over within 50 years so it is utter most important to conserve our source of energy. The graph below shows us a rough idea about the increase in the consumption of fuels usage. After the year 1965 the fuel use increased and in year 1995 it increased nearly 3000 times. Therefore it is very important to check on the usage of fuels consumption the government needs to take the required measurements in order to make a safe future. Fig. 1.2.1
  9. 9. 9 1.3 POLLUTION Cars and trucks produce air pollution throughout their life, including pollution emitted during vehicle operation, re-fuelling, manufacturing, and disposal. Additional emissions are associated with the refining and distribution of vehicle fuel. Air pollution from cars and trucks is split into primary and secondary pollution. Primary pollution is emitted directly into the atmosphere; secondary pollution results from chemical reactions between pollutants in the atmosphere. The following are the major pollutants from motor vehicles: Particulate matter (PM). Hydrocarbons (HC) Nitrogen oxides (NOx). Carbon monoxide (CO). Carbon dioxide (CO2) Sulphur dioxide (SO2). Hazardous air pollutants (toxics) Greenhouse gases These gases are trapped in the converters situated at exhaust pipe of all the vehicles. But all the gases don’t get trapped so it is important to design a engine which is able to give same output power but should have less emissions.
  10. 10. 10 2 AREAS OF INTEREST 2.1 POWER Firstly automobiles were used only for transportation purpose but now a days all the youth is interested in buying a vehicle which has more power and is capable of getting high accelerations and attain maximum speed in less time. So in order to fulfil consumer’s demand the engine of the automobile should have high output power and should be able to reach the expectations of the drivers. Apart from this the there is requirement of power in I c engine in the defence vehicles too. As they need to survive in different conditions and have to cover uneven roads. So overall power of the automobile engine has to be increased. 2.2 EFFICIENCY As we have seen in the previous chapter that the demand of I c engines are increasing and because of which the total usage of fuel is also increased. This petroleum isn’t a renewable source of energy, hence it needs to be conserved for the future generations. But according to current rate of usage of the fuel and the fuel deposits available in earths crush it is estimated that in near future (approximately in next 20 years) the fossil fuel deposits will be finished. So in order to preserve them we need to either decrease the use of vehicles or we need to increase the average or efficiency of the I c engine. Usage of vehicle can’t be controlled so the only option left with humankind is to increase the efficiency of the automobiles as much as possible. 2.3 EMMISIONS The major source of air pollution is automobiles. In was seen that the 60% of air pollutions is caused because of the automobiles. The emissions from the automobiles are as follows-
  11. 11. 11 Particulate matter (PM). These particles of soot and metals give smog its murky colour. Fine particles — less than one-tenth the diameter of a human hair — pose the most serious threat to human health, as they can penetrate deep into lungs. PM is a direct (primary) pollution and a secondary pollution from hydrocarbons, nitrogen oxides, and sulphur dioxides. Diesel exhaust is a major contributor to PM pollution. Hydrocarbons (HC). These pollutants react with nitrogen oxides in the presence of sunlight to form ground level ozone, a primary ingredient in smog. Though beneficial in the upper atmosphere, at the ground level this gas irritates the respiratory system, causing coughing, choking, and reduced lung capacity. Nitrogen oxides (NOx). These pollutants cause lung irritation and weaken the body's defences against respiratory infections such as pneumonia and influenza. In addition, they assist in the formation of ground level ozone and particulate matter. Carbon monoxide (CO). This odourless, colourless, and poisonous gas is formed by the combustion of fossil fuels such as gasoline and is emitted primarily from cars and trucks. When inhaled, CO blocks oxygen from the brain, heart, and other vital organs. Sulfur dioxide (SO2). Power plants and motor vehicles create this pollutant by burning sulfur-containing fuels, especially diesel. Sulfur dioxide can react in the atmosphere to form fine particles and poses the largest health risk to young children and asthmatics. Hazardous air pollutants (toxics). These chemical compounds have been linked to birth defects, cancer, and other serious illnesses. The Environmental Protection Agency estimates that the air toxics emitted from cars and trucks — which include Benzene, acetaldehyde, and 1,3-butadiene — account for half of all cancers caused by air pollution. Greenhouse gases. Motor vehicles also emit pollutants, such as carbon dioxide, that contribute to global climate change. In fact, cars and trucks account for over one-fifth of the United States' total global warming pollution.
  12. 12. 12 3 TYPES OF ENGINE 3.1 SUCTION IGNITION ENGINE A petrol engine (known as a gasoline engine in North America) is an internal combustion engine with spark-ignition, designed to run on petrol (gasoline) and similar volatile fuels. It was invented in 1876 in Germany by German inventor Nicolaus August Otto. In most petrol engines, the fuel and air are usually pre-mixed before compression (although some modern petrol engines now use cylinder-direct petrol injection). The pre- mixing was formerly done in a carburetor, but now it is done by electronically controlled fuel injection, except in small engines where the cost/complication of electronics does not justify the added engine efficiency. The method of mixing the fuel and air, and in using spark plugs to initiate the combustion process 3.2 COMPRESSED IGNITION ENGINE A diesel engine (also known as a compression-ignition engine) is an internal combustion engine that uses the heat of compression to initiate ignition and burn the fuel that has been injected into the combustion chamber. The engine was developed by German inventor Rudolf Diesel in 1893. The diesel engine has the highest thermal efficiency of any standard internal or external combustion engine due to its very high compression ratio. Low-speed diesel engines (as used in ships and other applications where overall engine weight is relatively unimportant) can have a thermal efficiency that exceeds 50% 3.3 HOMOGENUOS COMPRESSED CHARGED ENGINE HCCI has characteristics of the two most popular forms of combustion used in SI (spark ignition) engines- homogeneous charge spark ignition (gasoline engines) and CI engines: stratified charge compression ignition (diesel engines). As in homogeneous charge spark ignition, the fuel and oxidizer are mixed together. However, rather than using an electric discharge to ignite a portion of the mixture, the density and temperature of the mixture are raised by compression until the entire mixture reacts spontaneously
  13. 13. 13 3.4 HYBRID ENGINE Recently, Homogeneous Charge Compression Ignition(HCCI) engines have been introduced, Which have higher efficiency comparable to CI engines as Well as minimum particulate and NOx emissions characteristics, with the versatility of using gasoline as well as diesel fuel. In HCCI engines, a spark plug or a high-pressure injector is not used for initiation of the ignition of the fuel; instead, auto-ignition of the fuel (either gasoline or diesel) and air mixture at the end of the compression stroke is achieved by providing an elevated starting temperature at the beginning of the stroke. This elevated temperature is achieved mostly by two Ways: heating the intake air or using the exhaust gas from the previous cycle. In the latter system, one can re-induct or trap the hot exhaust gas from the previous cycle by changing the valve timings. The amount of the exhaust gas trapped in HCCI engines is usually about 50% in mass of the total gas inside the cylinder. Although this exhaust gas increases the mixture temperature before combustion, it actually decreases the peak temperature after combustion due to dilution effect. As a result, the NOx emission, which is exponentially proportional to the gas temperature, is about two orders of magnitude lower than that in conventional SI or CI engines. One can also achieve higher efficiency comparable to CI engines due to the de-throttling of the intake manifold and combustion shape closer to ideal Otto cycle. 3.5 BOOSTED ENGINE To overcome the load limitation, current state of art utilizesa hybrid of HCCI/ SI or boosted HCCI. In a hybrid approach, a mode switching from SI to HCCI occurs when the low load is required Where SI has poor efficiency.However, in this case, the emission and efficiency benefits of HCCI operation are lost in the medium to high load range, and the transientcombustion control of HCCI in mode switching is not a subtleissue in current research and industries. Secondly, boosted HCCI may give higher power, but it is also limited since the combustion becomes too noisy and destructive due to the high rate of pressure rise from rapid burn rate.
  14. 14. 14 4 CONCEPT OF MULTI-MODE Fig. 3.1 working graph 1 Fig. 3.2 working graph 2
  15. 15. 15 In the above Fig. 3.1 and 3.2 show the comparison of engine operation strategy between mode switching and mode/ stroke switching in terms of output power versus engine speed. Fig. 3.1represents the conventional 4S SI/HCCI multi-mode strategy. At low power output, the conventional SI engine suffers lower efficiency mainly due to the intake throttling. Typical HCCI engine uses Wide-open-throttle and controls the output power by varying the ratio between exhaust gas and fresh charge, called residual fraction (RF). This de-throttling combined With nearly constant volume combustion process results in higher efficiency of HCCI operation at low power. In addition to the efficiency benefit, HCCI engine minimizes the NO,C emissions from the dilution effect as mentioned above. For these reasons, the multi-mode engine is operated in 4S HCCI at low power output region. On the other hand, at high power limit, the RF in HCCI operation should be decreased to provide enough fresh charge, which results in high rate of heat release and high peak pressure and temperature due to lower dilution of exhaust gas, Which is very destructive to the engine. Therefore, the mode switching from 4S HCCI to 4S SI occurs to meet the power requirement as the power demand increases. At high power output, SI operation recovers the efficiency by lowering the level of throttling, but the efficiency and emission benefits of HCCI over SI are still sacrificed. At high engine speed, the 4S HCCI operation is limited due to increased trapped gas temperature and hence suffers rapid heat release during combustion. This sets the higher engine speed limit of 4S HCCI and the engine is operated in 4S SI, even at low power output. Consequently, the intake throttling is inevitable and the multi-mode engine suffers the low efficiency in this region of operation. Also it is seen in Fig. 3.2 shows the operational strategy of the present invention combining multi-mode and multi-stroke operation strategies. At low power output and low-to medium engine speed, the engine is running in 4S HCCI for the same reasons as in the conventional multi-mode. As the intermediate or high power is required, the engine is switched to 2S HCCI instead of 4S SI. Operating in 2S HCCI has two advantages over using 4S SI. First, While doubling the combustion frequency in 2S HCCI produces power output comparable to 4S SI, the benefits of high efficiency and low NO,C emissions of HCCI operation are retained.
  16. 16. 16 Second, the stroke switching is able to be achieved moresmoothly than mode switching. The temperature range of exhaust gas is similar in 4S HCCI and 2S HCCI, but typical 4S SI has 200-300 degrees higher exhaust temperature. Considering that HCCI phasing is sensitive to the temperature of trapped gas, the stroke switching achieves smoother transient operation than the mode switching. Additionally, 2S HCCI can cover the high engine speed range with moderate rate of heat release. In 2S operation, the mixture does not have enough time to mix completely due to shortened gas exchange process and compression stroke, and hence this less homogeneous mixture results in slower heat release than in 4S HCCI and makes 2S HCCI a feasible solution to operate at higher speed. In addition, for extremely high power and engine speed requirements, the engine may be switched to 4S boosted SI operation so that the higher limit of the output power can be extended over 2S HCCI operation. This mode switching is also readily possible due to the flexible valve timing and intake boost system. Consequently, in accordance With the present invention, the efficiency and emission benefits of HCCI can be exploited in typical operating range of the multi-mode strategy and 4S boosted SI operation expands the operating range to the higher power and speed region. Fig. 3.3 shows a block diagram of an example engine system in accordance with the present invention. The enabling technologies for multi-mode/multi-stroke operation include variable valve actuation such as an EHVS (or cam-phaser) EHVS controller, hydraulic supply, direct injector and combinations of supercharger, compressor and turbine. In addition, the electronic control unit (ECU) monitors the power demand and engine speed, and determines the optimal combustion strategies among 4S HCCI, 2S HCCI and 4S boosted SI according to the pre-set operational map. The information of the engine speed and the piston location for stroke/mode switching is transmitted from the incremental encoder 6 which is connected to the crank shaft. The in cylinder pressure trace is measured by a pressure transducer or ion sensor 7 and monitored by ECU 5. From the pressure signal, ECU 5 locates the combustion phasing of the current operating condition and performs the feedback control of combustion timing by changing valve timing or fuel injection timing. The measurement in lambda sensor 14 provides the minute information, and intake and coolant temperature sensors, which are not shown in Fig 3.2, are used to provide a feedback signal to reject disturbances from real environment operation.
  17. 17. 17 Fig 3.1 and 3.2 show the valve timing diagrams, i.e., exhaust and intake valve timings, for different combustion strategies. In FIGS. 3a, 3b and 3c, SOI stands for startof injection, BDC for bottom dead centre, and TDC for top dead centre. Combustion TDC is explicitly labelled With TDC and combustion, while intake TDC is simply labelled TDC. In each of FIGS. 3a, 3b and 30, two engine revolutions are shown, i.e., 720 crank angle degree (CAD) operation. Fig. 3.1 shows the valve timing for 4S HCCI. To trap some amount of exhaust gas, the exhaust valve closes before TDC and intake valve opens after TDC. There is no valve overlap, called negative valve overlap (NVO). As depicted with lateral arrows in Fig. 3.2, exhaust valve closing timing (EVC) and intake valve opening timing (IVO) are adjusted symmetrically to change RF in the next cycle: the earlier EVC, the higher RE. The fuel is injected after IVO, but this can be flexibly changed to meet the power output and combustion phasing requirements. At the end of compression stroke, the combustion phasing occurs near TDC, as shown in red. The valve timings and injection strategies shown in Fig. 3.1 represent one example embodiment of 4S HCCI. Other embodiments with other valve strategies such as late intake valve closing, and other injection strategies such as multiple injection strategies, are possible. Fig 3.2 shows the valve timing for 2S HCCI operation. It should be noted that there is one combustion event per revolution, which is double the frequency than in 4S operation. The exhaust valve opens during expansion stroke and closes after BDC. The intake valve opens after EVO and closes in the middle of compression stroke. Hence, there is valve overlap in 2S HCCI operation, and it is when the scavenging takes place. The amount of valve overlap is used to control the power output: at larger valve overlap, the air flow increases due to higher scavenging and the power output Will be increased. Complete scavenging does not need to occur since HCCI operation requires significant amount of burnt gas remaining inside the cylinder, Which makes the system simpler because the complete scavenging has always been an issue of 2S operation. The intake boost system is required for efficient scavenging and delivery of the intake air during compression stroke.IVC is optimized to minimize the need for intake boost pressure and hence maximize the overall system efficiency at a given condition. For example, early IVC results in poor charging efficiency and late IVC induces backflow of the mixture gases into the intake manifold, which results in the uncertainty of mixture composition in the next cycle. The fuel for 2S HCCI operation is directly injected into the cylinder after EVC to eliminate the fuel escape into the exhaust port.
  18. 18. 18 The injection timing and duration should be optimized to ensure that optimal combustion phasing occurs. It is also possible to optimize the efficiency, emissions and power by controlling the other valve timings. Fig. 3.3 shows the valve timing for 4S boosted SI. Although it has some similarities to the typical valve timing of 4S DISI (direct injection spark ignition), including valve overlap during gas exchange, injection during intake stroke, and spark ignition before TDC, the difference is in that the intake has boost pressure Which increases the power output, and IVC, spark timing, and injection timing should be adjusted to pre vent knocking from occurring with high boost pressure and compression ratio than in the typical DISI engine.To switch the stroke/mode according to the power and speed requirements, the valve timings mentioned above, as Well as spark ignition, boost of intake air and injection timings are changed as present configuration. This switching should occur at combustion top dead center (TDC) because this allows the engine to be ready for different stroke/mode operation in the next cycle. The details of operation in each mode are explained below. In 4S HCCI operation, the exhaust gas is trapped during NVO and mixed With fresh air and fuel. The trapped gas raises the initial mixture temperature, so the mixture Will be ignited at the end of compression stroke. To vary the power output, the RF is changed by adjusting the duration of NVO, and combustion phasing is controlled by injection timing. The super and turbo chargers and spark ignition system are turned off in this operation. When the combustion mode is switched to 2S HCCI, the super and turbo chargers are activated. This super and turbo charging combination is configured to optimize the overall efficiency of the engine. For example, at a low engine speed where there is not enough energy available in the exhaust, the super charger is mainly operating, while, at a high speed, both the super and turbo chargers are activated to boost the intake air. The exact balance of operation between the super and turbo chargers depends on the engine operating condition. An intercooler may be incorporated to increase the efficiency of the boosting system. The engine power output is controlled by the duration of valve overlap, that is, the extent of the scavenging. Due to shortened gas exchange process, 2S HCCI can be more susceptible to cyclic variations, which requires the feedback control on the combustion event. The combustion control is achieved by two factors: IVC which determines the effective compression ratio, and injection timing which affects the homogeneity of mixture.
  19. 19. 19 5 TECHNOLOGICAL REQUIREMENTS In accordance With the present invention, the intrinsic loadlimitation of HCCI is overcome by switching the engine stroke from 4-stroke S‖ to 2-stroke S‖ so that the combustion frequency is doubled and hence, even at the same work output per cycle, the engine can double the power Which is comparable to that in the conventional SI/CI engines.Although this stroke switching of the present invention produces about the similar power range as the mode switching from 4S HCCI to 4S SI does, the differences are in the emission and efficiency. HCCI operation is inherently clean and efficient combustion even in 2S operation. Additionally, the stroke switching between the same combustion strategies is much simpler and smoother than the mode switching between the different strategies. Consequently, the stroke switching is superior to mode switch to operate in 2S HCCI mode, the followings are required, The first is the flexible valve system such as Electro-Hydraulic Valve System (EHVS) or cam-phaser to operate at different valve profiles for stroke switching between 25 to 4S HCCI.Secondly, a super charger or combination of turbo and super chargers to boost the intake manifolds to enable fast gas exchange for 2S operation. It is noteworthy that in 2S HCCI, the complete scavenging is not required because large portion of the exhaust gas is used in the next cycle, which makes the system and control simpler than in a hybrid of 4S/2S SI Which has additional intake system for 2S operation. 6 SUCCESSIVE RESULTS The engine with the proposed improvements is capable almost to double (1.7 – 2.0 time increase) its output power and hold it up for a short period of time (this short period depends on a type of the engine) without overheating. This feature allows the vehicle power-to-weight ratio to be doubled upon necessity in accordance with the vehicle operation conditions.
  20. 20. 20 7 FIELD OF IMPLEMENTATION 1 Diesel engines for combat tanks Fig. 7.1 Diesel engines for combat tanks 2Diesel engines for infantry fighting vehicles (IFV) Fig. 7.2 IFV
  21. 21. 21 3 Diesel engines for military heavy trucks FIG. 7.3 Diesel engines for military heavy trucks 4 Diesel engines for special purpose vehicles (i.e. emergency vehicles, fire trucks, etc.) FIG. 7.4 special purpose vehicle
  22. 22. 22 8CONCLUSION Several projects are developed for different clients. Among them one is the 4-2- stroke Diesel engine prototype built for the very common tractor engine. Another engine for special purpose machine is slightly modernized in such a way that the same engine can produce about 12% more power while the original lay out, weight, dimensions, and specific fuel consumption (per hour)are almost unchanged. But this project is capable of giving all the positive sides ie. it increases the efficiency increases the power and also reduces the emissions. 9BIBLIOGRAPHY Andre Kulzer, Ansgar Christ, Martin Rauscher, Christina Sauer, GernotWurfel and Thomas Blank, "Thermodynamic analysis and benchmark of various gasoline combustion concepts," SAE paper 2006-01-0231, 2006. Caton, P. A., Simon, A. J., Gerdes, J.C., and Edwards, C.F. "Residual-Effected Homogeneous Charge Compression Ignition at a Low Compression Ratio Using Exhaust Reinduction," Int. J. Engne Res., vol. 4, No. 3, 2003. G. Haraldsson and B. Johansson, "Operating Conditions Using Spark Assisted HCCI Combustion During Combustion Mode Transfer to SI in a Multi-Cylinder VCR-HCCI Engine," SAE paper 2005-01-0109, 2005. J. A. Eng, "Characterization of Pressure Waves in HCCI Combustion," SAE paper 2002-01-2859, 2002. J. Yang, T. Culp, and T. Kenney, "Development of a Gasoline Engine System Using HCCI Technology-The Concept and the Test Results," SAE paper 2002- 01-2832, 2002. Kaahaaina, N., Simon, A., Caton, P., and Edwards C. "Use of Dynamic Valving to Achieve Residual-Affected Combustion," SAE Transactions, Journal of Engines, vol. 110, Section 3, pp. 508-519, 2001-01-0549.
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