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🚗 | The first new generation of Lexus is "NX" new model ... PHV setting, touch tracer operation, etc.


Photo Lexus NX new prototype

The first new generation of Lexus is "NX" new model ... PHV setting, touch tracer operation, etc.

 
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The Direct Shift 8AT has been optimized for the features of turbo engines that generate high torque from low revs.
 

Lexus made the world premiere of the new "NX" (Lexus NX) on June 6.The brand's first PHV ... → Continue reading

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Turbocharger

Turbocharger(British: turbocharger) Is a compressor that utilizes the flow of exhaust gasCompressor)Internal combustion engineIncreases the density of air inhaled bySupercharger.

Overview

Turbochargers are mainlyExhaust gasRotates in response to the flow ofTurbine(British: turbines)When,TurbineTransmits the rotational force ofシ ャ フ ト(British: shaft), With the transmitted rotational force of the turbine空 気To capture and compresscompressor(British: compressor), And control the flow around the turbine and compressorhousing(British: housing).For the compressorCentrifugal compressorIs used, the turbine and compressor are fixed to both ends of one shaft, and the turbine and compressor rotate at the same rotation speed.

Increase the density of air taken in by the engine to get more oxygenCombustion chamberIt is the turbocharger that sends the fuel to the engine to obtain higher combustion energy, but compared to the mechanical turbocharger that obtains the power of the compressor from the output shaft of the engine, the exhaust gas that is normally discardedPhysical energyIt is highly efficient because it is driven by collecting.

The rotation speed of the turbine is 20 for small ones such as those for automobiles.rpmSome exceed[1], Hot exhaust (800-900[1]Receive directly.bearing Theengine oilIn many cases, the engine is required to be able to withstand high temperature environments.Also, when the engine is stoppedOil pumpIf the engine is stopped at a high temperature due to high load operation, the bearings will stop circulating.Burn-inAlso, the accumulated oil causes sludge.To prevent this, it is recommended to keep idling to cool the heat before stopping the engine in the instruction manuals of automobiles.

History

スイスInvented by a steam turbine engineer[2],1905Was patented.1912ToGermany OfRudolph Diesel Diesel locomotiveIn the low rpm rangetorqueWas enrolled in Buch to improveSulzerAttempted to introduce a turbocharger in partnership with the company[3]..Buch's turbo diesel engine1925Completed and widely spread mainly on ships[4].

In the United States, research was conducted ahead of other countries, such as the development of airplane motors and high-altitude flights as early as the end of World War I, and in the mid-1930s for next-generation military aircraft. Full-scale mass production was promoted as a power-up aircraft, and in the latter half of the 1930s, a system capable of mass production was established, which contributed to the superiority of the Allied aviation strategy in World War II.

On the other hand, in the Empire of Japan, research for aircraft was being carried out following the United States, but research for marine engines was also carried out without fail.1942ToJapanIntroduced turbocharger to 2-stroke diesel engine for the first time[4].. Made by MANUniflow scavenging diesel engineBased onMitsubishi Heavy IndustriesDeveloped for military vessels,Roots blowerThe turbocharger was connected in series.At the beginning of development, supercharging was mainly done for roots blowers, but gradually the ratio of supercharging was shifted to the turbocharger, and finally it succeeded in driving only with the turbocharger.1944Patented in[4]. But,Imperial Japanese NavyWas not introduced to military ships in time by the end of the war, and the first adoption on ships was the postwar passenger ship "Maiko Maru".[4].

On the other hand, for aviation, prototype level onesThunderbolt,Type XNUMX fighterThere is an example that it was installed in, but it could not be put into practical use because it could not overcome the technical difficulties including heat-resistant alloys and there were too many problems in mounting.[5].

For commercial gasoline vehicles1962To americanGeneral Motors(GM) says "Oldsmobile・ F85 "and"Chevrolet Corvair"ToOptionsIt was the first to set in.European carsThen.1973 OfBMW 2002 TurboWas adopted for the first time in.1978ToB&WIntroduced a static pressure supercharged turbocharger to a marine 2-stroke diesel engine to improve thermal efficiency[3].Japanese carThen.1979 OfNissan Cedric / グ ロ リ アWas adopted for the first time in.

In Japan,1980In the second half of the generationOrdinary passenger car(3 numbers) andSmall passenger car(5 number)Automobile taxThe difference is large (5 number 39,500 yen, 3 number less than 3000cc 81,500 yen), which is the upper limit of displacement of small passenger cars 2,000ccThe number of models equipped with a turbocharger on the engine of is increasing, mainly in luxury cars and sports cars.Also, in the turbo-charged engine at that time,knockingAs a countermeasure, the proportion of gasoline contained in the air-fuel mixture was intentionally increased, which also contributed to the deterioration of fuel efficiency.In addition, diesel engines are compatible with turbochargers because they do not require knocking countermeasures, so diesel vehicles continue to be actively equipped with turbochargers.2005Or later,VolkswagenReduces engine exhaust and supplements torque and horsepower with a turbochargerDownsizing conceptThe number of models that adopt is increasing, and other European manufacturers are following suit.It was difficult to improve fuel efficiency with the conventional turbocharged engine because the air-fuel ratio was increased to reduce knocking, but in recent models that adopt the downsizing concept, the air-fuel ratio is increased by direct injection of the fuel supply device. Knocking measures are taken without doing anything.2013Since then, Japanese manufacturers have followed the situation in Europe and have been equipped with turbochargers in combination with direct injection of fuel injection.In Europe, diesel engines are also being actively adopted in passenger cars, and many of them are equipped with turbochargers.Sales to passenger cars equipped with diesel engines (+ turbo) in the Japanese market are gradually being made.

Comparison with mechanical turbocharger

Powered from the output shaft of the engine via a mechanical mechanismSuperchargerThere is mechanical loss (mechanical loss), but since the turbocharger is driven by using a part of the energy (exhaust loss) that is wasted as heat of exhaust gas and kinetic energy, there is no mechanical loss of the engine output shaft. Only a small amount of exhaust resistance is generated.Generally, 40% of the energy obtained from combustion in a cylinder is exhaust loss, and turbochargers are said to be able to recover 7-10%.[6].

On the other hand, both the intake pipe and the exhaust pipe go through the turbocharger, which complicates the layout of the engine room.In addition, in applications such as automobiles where the rotation speed of the engine fluctuates greatly during operation, there is a delay until the turbine reaches the rotation speed at which sufficient boost pressure can be obtained during transient operation from low speed rotation to high speed rotation. OccursTurbo lagA phenomenon called is likely to occur.That is,throttleThe increase in engine output with respect to operation tends to be delayed.Since the bearing of a turbocharger becomes hot, ball bearings with high heat resistance are often used, or oil is circulated for cooling and lubrication in many cases.In applications such as automobiles, engine oil is cooled and lubricated, so engine oil tends to deteriorate.

As measures to reduce the influence of turbo lag, measures such as weight reduction of turbines and miniaturization of turbochargers are being implemented by each manufacturer.

Comparison with naturally aspirated

Since the turbocharger pumps the intake air to the engine, the output per unit displacement is improved.However, on the other hand, as the output increases, the combustion temperature rises and the cylinder internal pressure rises.Head gasket,Cylinder head,Cylinder blockStrength andpistonIt is necessary to increase the heat resistance of.The intake air temperature rises due to compression by the compressor and heat conduction from the turbine.IntercoolerIn many cases, the air intake after compression is cooled to improve the air filling rate.In the case of a gasoline engine, supercharging causes the air-fuel mixture to become hotter during the compression stroke of the engine.DetonationIs likely to occur.As a countermeasure, than the naturally aspirated engine of the same modelCompression ratioCan be set low or the air-fuel ratio[7]May be set darker.When the compression ratio is lowered, the thermal efficiency is lowered in the rotation range where the supercharging effect cannot be obtained, and the output is lower than that of the naturally aspirated engine.In addition, increasing the air-fuel ratio deteriorates driving fuel efficiency.In recent years, technology for injecting gasoline directly into the cylinder (Gasoline direct injection engine) Has solved the problem of detonation because only air is compressed in the compression stroke, and in passenger cars after 2010, the displacement is reduced, the weight of the vehicle is reduced, and the output is supplemented by a supercharger. Reduce driving fuel consumptionDownsizing conceptThe number of cases of adopting is increasing.

Use

Turbochargers are ships, generators,Construction machinery,Railway car, Widely used in automobiles, etc.In particular, it is suitable for applications such as ships and generators where the engine speed does not change significantly, because the turbocharger design can be easily optimized for its operating conditions and turbo lag, which is a drawback peculiar to turbochargers, does not occur.Also,diesel engineOnly aircylinderSince it is sucked into the air and compressed, the detonation that occurs in the gasoline engine does not occur, and the intake path is not narrowed even in the partial load range, so compatibility with the supercharger is particularly good.

Car etc.

In automobiles, in addition to trucks and buses equipped with diesel engines,Motor sportsVehiclessports carIt is also commonly used in such cases.The first commercial vehicle equipped with a turbocharger1973DebutBMW 2002 TurboIs.In Japan1979DebutNissan 430 CedricIntroduced the first grade equipped with a turbo, and since thenBluebird,ス カ イ ラ イ ンTurbo-equipped models are also born in major models such asNissan MotorBecame a pioneer of domestic turbo cars.Since the latter half of 2005, the number of vehicles for fixed-route buses has been increasing with turbochargers to reduce fuel consumption and exhaust gas by downsizing.

F1Well, once the turbo engine was in full swing,Honda WilliamsEven the engine (RA166E) that was supplied to V6 cylinderTwin turboIt is said that 776kW (1055 horsepower) was generated during the race due to the composition of[8], For safety reasons1987Supercharging pressure limit is added by regulation from 1987 (up to 4 in XNUMX)bar,1988Up to 2.5 bar), the use of turbochargers was banned at the end of the 1988 season.However, from 2014, it has become possible to use a 1,600cc V6 engine in combination with a single turbo.

Since the 2010s, passenger cars made by European manufacturers have a small displacement.Gasoline direct injection engineThe output is supplemented by a turbocharger while reducing the size and weight of the engine.Downsizing conceptThe number of vehicles that adopt the turbocharger is increasing, and the number of vehicles equipped with a turbocharger is increasing.A low pressure turbo and a twin scroll turbo are adopted, and a large torque is generated with flat characteristics from low rotation to medium and high rotation.In Japanese passenger carsLight carIn many cases, turbochargers are used.Also, onceAutomobile taxBecause the tax amount of the number 3 and the number 5 were very different5 number bodyIn many cases, turbochargers were used for engines with a displacement of 2,000cc or less.

aircraft

Aviation engineThen.1950 eraUntil then, most of them were reciprocating engines, so research on turbochargers was conducted to maintain output at high altitudes with low atmospheric pressure (low oxygen).Initially, a mechanical supercharger was adopted, but it was gradually replaced by a turbocharger.

Critical altitude (altitude that can output a predetermined output at full throttle)Sea level altitudeIn order to maintain the engine output up to the limit height at which the same output can be exhibited), a valve called a shortcut valve that automatically opens and closes the bypass flow path according to the altitude of the exhaust sent to the turbine is installed, and the atmospheric pressure At low high altitudes, the bypass flow path is closed to increase the exhaust sent to the turbine to increase the intake pressure, and at low altitudes with high atmospheric pressure, the bypass flow path is opened to reduce the exhaust sent to the turbine to reduce the intake pressure and the engine. Make the output constant.A constant engine output can be maintained from the ground to the critical altitude, but the engine output decreases above the critical altitude.[9].

In modern timesJet engine,Turboprop engineDue to the high performance of the engine, the reciprocating engine is used only for small aircraft, but it is installed to increase the output while suppressing the engine size rather than the high altitude performance.Even if the reciprocating engine is equipped with a turbocharger, the license is the same as for naturally aspirated engines, which is a "piston", so some manufacturers use the engine as a higher-end model with the engine replaced with a turbocharger.

Major manufacturers

Type (mainly automobile terminology)

  • (Light pressure turbo / low pressure turbo)
  • Twin scroll turbo
  • Variable nozzle (VG) turbo
  • [10][11][12]
    • In May 2011, IHI announced the commercialization of an electrically power assisted turbo.Detailed performance such as the number of revolutions at which the supercharging effect of the turbine appears has not been announced. (Although supercharging pressure is generated when the intake turbine rotates, if it is not rotated from a speed lower than the turbocharging start speed of the engine alone, it will cause torque fluctuations such as turbo lag.)
  • (TWT: Three Wheel Turbochager)
    • In addition to intake and exhaust, a part (wheel) that assists rotation at low speed is added to make it a three-wheel.In a broad sense, the above-mentioned electric assist is also included, but as a term, it is often used for assisting by turning an oil turbine via flood control.The hydraulic type has been researched and developed mainly for commercial diesel vehicles, but it has not been widely used due to problems such as the requirement for extremely high hydraulic pressure.

footnote

  1. ^ a b Koji Nakano, Yusuke Wada, Makoto Shirono, Shigeru Narihiro "New in-line 4-cylinder gasoline direct injection supercharged downsizing engine" "Honda R & D Technical Review" Vol.28 No.1, 2016, pp. 133-139.
  2. ^ This says todayTurbo compoundIt was also an engine.
  3. ^ a b Takashi Suzuki 2001.
  4. ^ a b c d Koichiro Imasuke "Technical systematization survey of exhaust gas turbine supercharger"Technology Systematization Survey Report," Vol. 16, National Museum of Nature and Science, 2011.
  5. ^ Takanori Maema, "The Legend of Man Machine Showa"
  6. ^ "Nippon Foundation Library (Digital Library) XNUMXS Class Marine Mechanic Guidance Book”. The Nippon Foundation. 2015/12/9Browse.
  7. ^ The darker the flame propagation speed, the slower the detonation.
  8. ^ Proceedings of the 19th Gas Turbine Regular Lecture ('91 -5)
  9. ^ Mitsuru Ishida, 1989, "Piston Engine for Aircraft", Japan Aeronautical Technology Association <Aeronautical Engineering Course XNUMX> ISBN 4930858100
  10. ^ "Electric assist turbo !! (PDF) "IHI Giho" Vol. 51, No. 1, 2011.
  11. ^ "Fuel efficiency improved by 1% -IHI's electric assist turbo". Daily car newspaper(July 2010, 10). http://www.njd.jp/topNews/dt/1079/ 
  12. ^ Seiichi Ibaraki, Yukio Yamashita, Kunio Sumita, Koji Ogita "[http://www.mhi.co.jp/technology/review/pdf/433/433036.pdf Development of Electric Assist Turbocharger "Hybrid Turbo"] (PDF) "Mitsubishi Heavy Industries Technical Report, Vol. 43, No. 3, 2006.

References

  • Takashi Suzuki, 2001, "Engine History in the 20th Century: The Rise and Fall of Sleeve Valves and Aviation Diesel", Miki Shobo ISBN 4895222837
  • Takanori Maema, 1993, "Showa Legend of Man Machine: From Aircraft to Automobile", Kodansha ISBN 4062059983 NCID BN09468958
  • Takanori Maema, 1993a, "Showa Legend of Man Machine: From Aircraft to Automobile", Kodansha ISBN 4062065819 NCID BN09468958

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