A More Efficient Engine ： HCCI engine

MIT教授發明了新版的內燃機引擎，能同時兼具汽油引擎的低排放及柴油引擎的高效率。採用的最新的燃燒技術HCCI(Homogeneous Charge Compression Ignition)，能夠更平順的燃燒，排放更少的一氧化氮。

Clean burning: A new sparkless gas engine could significantly reduce fuel consumption. In a conventional engine (top), a mixture of fuel and air is ignited by a spark plug. In a diesel (middle), the fuel ignites when it's injected into hot, compressed air. An alternative to both is called homogeneous charge compression ignition (bottom).

Here, a mixture of fuel and air is compressed until it combusts. Because the fuel and air are premixed, they burn more evenly than they do in a diesel engine, producing much less soot and nitrogen oxide.

A new version of the internal combustion engine, which could significantly cut gas consumption, might be surprisingly practical and easy to deploy, according to recent findings by researchers at MIT. Tests on a prototype based on the technology, which allows engines to switch between conventional technology and the new gas-saving type of combustion, show that it does not require a special fuel, and engines using the technology can be cheaply made out of conventional auto parts.

The gas-saving technology, called homogeneous charge compression ignition, or HCCI, uses a form of combustion that is much more efficient than conventional spark ignition. Under some conditions, it can reduce fuel consumption by 25 percent, says William Green, a professor of chemical engineering at MIT who was coauthor of the new study. That's very similar to the efficiency of a diesel engine, which also achieves combustion by compression rather than a spark. But unlike diesel engines, HCCI results in a more uniform combustion and is thus much cleaner. A system that combines HCCI with conventional combustion could improve fuel economy by a few miles per gallon on average, Green says.

Several research groups are working on the new type of combustion. Volvo, for example, has built a hybrid system that can switch between conventional spark ignition and HCCI. Some experts, however, had expected that the new type of engine would require special fuel.

The MIT research shows that an HCCI engine can operate with any of the varieties of gasoline sold in North America, making a special fuel unnecessary. The researchers tested a range of different gasolines made at different refineries. They found that the HCCI engine "was less sensitive to the fuel than people had feared," says Green.

While the HCCI has several performance limitations, these can be addressed using a hybrid approach, in which an engine could switch between HCCI and conventional spark ignition. Using already mass-produced parts could make it relatively inexpensive to build such a hybrid, Green says.

In conventional gasoline engines, a spark ignites a mixture of fuel and air in a combustion chamber, creating an explosion that drives a piston. While this happens very efficiently when the engine is working hard, it's less efficient at lower loads, such as during cruising, when less gasoline is being pumped into the combustion chamber. At these times, to keep the ratio of fuel to oxygen optimized, a partial vacuum is created in the chamber. It takes extra energy to make this vacuum, which decreases the engine's efficiency.

The HCCI technology avoids the use of an energy-wasting vacuum. Instead, hot gases from a previous combustion cycle remain in the chamber;the engine uses a combination of heat from these hot gases and heat generated by compressing the mixture to raise temperatures high enough that the mixture explodes.

But if the engine's temperature is too low, such as when it's being started or being operated under very low loads, the mixture doesn't get hot enough to combust. And at high loads, when the temperature is high, the mixture can combust too early, out of sync with the cycling of the engine, causing a potentially damaging phenomenon called knock. Differences in fuels can also affect precisely when the mixture combusts.

The hybrid system switches between the two forms of combustion. To do this requires changing the way the engine deals with combusted gases. During spark combustion, the gases are forced out through an open valve. In HCCI, the timing of the opening of that valve is changed so that it closes before the gases completely escape, trapping them inside.

John Heywood, a professor of mechanical engineering at MIT who was not involved with this work, says that HCCI could eventually provide even greater benefits as researchers find ways to adapt the engine so that they can use it for a wider range of loads. What's more, it could be used in combination with other gas-saving technologies already available on many vehicles. The extent to which HCCI can be combined with other approaches could determine how widely it's adopted, suggests Heywood.

[Source：MIT Laboratory for Energy and the Environment]

Part1.Weight Transfer

Most people remember Newton's laws from school physics. These are fundamental laws that apply to all large things in the universe, such as cars. In the context of our racing application, they are:

The first law: a car in straight-line motion at a constant speed will keep such motion until acted on by an external force. The only reason a car in neutral will not coast forever is that friction, an external force, gradually slows the car down. Friction comes from the tires on the ground and the air flowing over the car. The tendency of a car to keep moving the way it is moving is the inertia of the car, and this tendency is concentrated at the CG point.

The second law: When a force is applied to a car, the change in motion is proportional to the force divided by the mass of the car. This law is expressed by the famous equation F= ma , where F is a force, m is the mass of the car, and is the acceleration, or change in motion, of the car. A larger force causes quicker changes in motion, and a heavier car reacts more slowly to forces. Newton's second law explains why quick cars are powerful and lightweight. The more F and the less m you have, the more a you can get.

The third law: Every force on a car by another object, such as the ground, is matched by an equal and opposite force on the object by the car. When you apply the brakes, you cause the tires to push forward against the ground, and the ground pushes back. As long as the tires stay on the car, the ground pushing on them slows the car down.

Let us continue analyzing braking. Weight transfer during accelerating and cornering are mere variations on the theme. We won't consider subtleties such as suspension and tire deflection yet. These effects are very important, but secondary. The figure shows a car and the forces on it during a ``one g'' braking maneuver. One g means that the total braking force equals the weight of the car, say, in pounds.

In this figure, the black and white ``pie plate'' in the center is the CG. G is the force of gravity that pulls the car toward the center of the Earth. This is the weight of the car; weight is just another word for the force of gravity. It is a fact of Nature, only fully explained by Albert Einstein, that gravitational forces act through the CG of an object, just like inertia. This fact can be explained at deeper levels, but such an explanation would take us too far off the subject of weight transfer.

Lf is the lift force exerted by the ground on the front tire, and Lr is the lift force on the rear tire. These lift forces are as real as the ones that keep an airplane in the air, and they keep the car from falling through the ground to the center of the Earth.

We don't often notice the forces that the ground exerts on objects because they are so ordinary, but they are at the essence of car dynamics. The reason is that the magnitude of these forces determine the ability of a tire to stick, and imbalances between the front and rear lift forces account for understeer and oversteer. The figure only shows forces on the car, not forces on the ground and the CG of the Earth. Newton's third law requires that these equal and opposite forces exist, but we are only concerned about how the ground and the Earth's gravity affect the car.

If the car were standing still or coasting, and its weight distribution were 50-50, then Lf would be the same as Lr. It is always the case that Lf plus Lr equals G, the weight of the car. Why? Because of Newton's first law. The car is not changing its motion in the vertical direction, at least as long as it doesn't get airborne, so the total sum of all forces in the vertical direction must be zero. G points down and counteracts the sum of Lf and Lr, which point up.

Braking causes to be greater than . Literally, the ``rear end gets light,'' as one often hears racers say. Consider the front and rear braking forces, Bf and Br, in the diagram. They push backwards on the tires, which push on the wheels, which push on the suspension parts, which push on the rest of the car, slowing it down. But these forces are acting at ground level, not at the level of the CG. The braking forces are indirectly slowing down the car by pushing at ground level, while the inertia of the car is `trying' to keep it moving forward as a unit at the CG level.

The braking forces create a rotating tendency, or torque, about the CG. Imagine pulling a table cloth out from under some glasses and candelabra. These objects would have a tendency to tip or rotate over, and the tendency is greater for taller objects and is greater the harder you pull on the cloth. The rotational tendency of a car under braking is due to identical physics.

The braking torque acts in such a way as to put the car up on its nose. Since the car does not actually go up on its nose (we hope), some other forces must be counteracting that tendency, by Newton's first law. G cannot be doing it since it passes right through the cetner of gravity. The only forces that can counteract that tendency are the lift forces, and the only way they can do so is for Lf to become greater than Lr. Literally, the ground pushes up harder on the front tires during braking to try to keep the car from tipping forward.

By how much does Lf exceed Lr? The braking torque is proportional to the sum of the braking forces and to the height of the CG. Let's say that height is 20 inches. The counterbalancing torque resisting the braking torque is proportional to Lf and half the wheelbase (in a car with 50-50 weight distribution), minus Lr times half the wheelbase since Lr is helping the braking forces upend the car. Lf has a lot of work to do: it must resist the torques of both the braking forces and the lift on the rear tires. Let's say the wheelbase is 100 inches. Since we are braking at one g, the braking forces equal G, say, 3200 pounds. All this is summarized in the following equations:

3200lbs times 20 inches = Lf times 50 inches - Lr times 50 inches

Lf + Lr = 3200lbs (this is always true)

With the help of a little algebra, we can find out that
Lf = 1600+3200/5 = 2240lbs ; Lr = 1600-3200/5 = 960lbs

Thus, by braking at one g in our example car, we add 640 pounds of load to the front tires and take 640 pounds off the rears! This is very pronounced weight transfer.
By doing a similar analysis for a more general car with CG height of , wheelbase , weight , static weight distribution expressed as a fraction of weight in the front, and braking with force , we can show that
Lf = dG + Bh/wLr = (1-d)G - Bh/w

These equations can be used to calculate weight transfer during acceleration by treating acceleration force as negative braking force. If you have acceleration figures in gees, say from a G-analyst or other device, just multiply them by the weight of the car to get acceleration forces (Newton's second law!). Weight transfer during cornering can be analyzed in a similar way, where the track of the car replaces the wheelbase and d is always 50%(unless you account for the weight of the driver). Those of you with science or engineering backgrounds may enjoy deriving these equations for yourselves. The equations for a car doing a combination of braking and cornering, as in a trail braking maneuver, are much more complicated and require some mathematical tricks to derive.
Now you know why weight transfer happens. The next topic that comes to mind is the physics of tire adhesion, which explains how weight transfer can lead to understeer and oversteer conditions.

Automotive X-Prize announces first 31 teams accepted to competition

has announced the first thirty-one teams to be accepted into their upcoming mileage competition and several of our favorite subject companies are on the list. Among the teams that have been accepted into the first round of competition are Tesla, Zap, and Phoenix Motorcars. Other teams that we have covered here that made the cut are Fuel Vapor Technology and Team Velozzi. According to organizers over 300 teams have expressed interest in the competition and are considering jumping in.

XPrize宣佈有31個隊伍這個省油車的競賽，第一回合的比賽將由Tesla, Zap, Phoenix Motorlogy and Team Velozzi來參加。

The goal of the competition is to create a commercially viable vehicle that can exceed 100 mpg gasoline equivalent based on a combination of well-to-tank analysis and tank-to-wheels actual vehicle performance. The real key here is the commercial viability. Teams have to demonstrate not just vehicle performance but a business plan showing that they can sell the vehicles in volumes of 10,000 or more annually. Preliminary competitions including peer reviews start in 2008 with the actual vehicle competitions in 2009.

競賽的目的是製作出油耗能夠達到100mpg的車子，真正的關鍵在商業化的考量，參賽隊伍不只要展現車子的性能，還要提出完整的商業計畫，讓大家相信這部車子能夠賣出一萬輛甚至更多。預賽是2008舉行，而真正的決賽要到2009年。

The following 31 teams have signed a letter of intent signaling their intent to apply for the AXP competition:

• Aptera Motors – California, USA

• Commuter Cars Corp. – Washington, USA

• Cornell University – New York, USA

• DEHyds – Washington, USA

• Delta Motorsport – Northants, UK

• Desert Fuel – Arizona, USA

• Disruptech – California, USA

• Dragonfly Technology LTD – Northhampton, UK

• Fuel Vapor Technologies – British Columbia, Canada

• GreenIt! – Oregon, USA

• Herf Duo – Berlin, Germany

• HyKinesys – California, USA

• Kinetic Vehicles – Oregon, USA

• Kuttner Doran Inventions – Virginia, USA

• Loremo AG – Munich, Germany

• Maine Automotive X – Maine, USA

• MDI, Inc. & Zero Pollution Motors LLC – New York, USA

• Michigan Vision – Michigan, USA

• MotoTron Corporation – Wisconsin, USA

• Phoenix Motorcars – California, USA

• Prometheus Systems, LLC – Arizona, USA

• Porteon Electric Vehicles, Inc. – Oregon, USA

• Psycho-Active – Georgia, USA

• Roane Inventions – Texas, USA

• Society for Sustainable Mobility – California, USA

• Spirit One – Alberta, Canada

• Tesla Motors – California, USA

• Valentin Technologies – Wisconsin, USA

• Velozzi – California, USA

• X Tracer – Winterthur, Switzerland

• ZAP Motors – California, USA

[Source：AutoBlogGreen.com]

STRESS TO IMPRESS

A top Formula 1 driver doesn't give too much thought to any one of the hundreds of components that make up his race car failing while he's teetering on the brink of adhesion at 180mph plus. If he did then he probably wouldn't be able to do it. But there's more to it than that. You see, deep down perhaps, he can always feel safe in the knowledge that someone else has already worried about those components for him - someone like the Stress Analysis and Materials Group headed by Luca Furbatto.

Furbatto's dedicated band of engineers work in the drawing office - an ideal location as they often need to interact with the designers - and comprises experts in both composite materials and metallurgy, most of them recruited from the aerospace industry.

Racing is very much in Furbatto's blood then, which is useful, as the challenge the group faces is one that is central to modern race car design - that is, trying to achieve the balance between driver safety and car performance. It is up to the Stress Analysis and Material Group to ensure that while a component in the car is safe, and meets all the strict FIA regulations, it is also optimised to perform at its very best. It must meet stiffness and weight targets that are crucial to its performance on track. It's an immense challenge, but thankfully they have a quite incredible tool at their disposal to meet it.

"Structural simulation helps tremendously in terms of stiffness and strength visualisation," says Furbatto. "It helps us find out where the structure bends or twists, and then improve it. And all this can be done before a single component is actually made." This 'stress analysis' is carried out by FEM (Finite Element Method - also called FEA, the 'A' for Analysis). Basically, these computer programmes are able to apply a three-dimensional grid of elements to the designer's CAD renditions of the components. As these are then mathematical models, set forces and boundaries - which are derived from track data, limit conditions and FIA regulations - can be applied to them to give a virtual picture of the component under stress, showing it bend, vibrate or deform. Ninety per cent of the car is now modelled with FEM, and tests applied include everything from vibration on a wing, or torque on a gear, to the results of a side impact test on the monocoque.

"The loads we apply to structures are often very large," says Furbatto. "Under a front crash, for example, the load generated by the nosecone can reach 350kN, or 35 tonnes - that's about the size of a large truck..."

These loads can then be represented on the screen using a colour spectrum, which correspond to measurements along the screen edge, for quick reference. The grids, or 'meshes', can be fine or coarse, depending on the level of information required - a finer mesh means more elements, hence more information but longer run time. Yet with between 300 to 400 parts to look at per car, this is by no means a simple job.

As Furbatto points out, with each individual case "the maths behind it is very complicated, you are talking about very large matrices.The job requires a sound understanding of finite element method and numerical convergency." Indeed, with a large component such as a monocoque, analysis can take a full eight weeks from the start of meshing to the finished report.

That said, there's no doubt all this virtual testing has speeded up the build process of the modern Formula 1 car considerably, and has also allowed the designers to come up with components that are at the optimum weight and stiffness. As McLaren Racing's executive director of engineering, Neil Oatley, puts it: "In the past the development process was less precise, and you would always allow yourself much larger safety margins; Inevitably you would be more conservative so components would be heavier."

But in these days of ultra-strict FIA safety regulations it's not enough to simply prove that a part is up to the job on the screen alone, and it's part of the group's responsibility to set the parameters and coordinate the routine lab tests on the finished components too. This all takes place in the test lab, using non-destructive and destructive test frames supplied by McLaren Technology Centre Partner Instron.

"Once a part is designed to spec," says Furbatto, "in order to be approved for track use it has to go through a series of tests, including static tests, fatigue tests and destructive tests." Incidentally, the group also oversees material tests in the lab, working closely with Official Supplier Advanced Composites Group, as well as batch quality checks and failure analysis. All that said, it's the stress analysis that's still the core of the group's work, although in recent times its role has begun to change, as McLaren's chief designer Mike Coughlan explains. "Stress analysis is moving more towards the optimising of components now and higher level structural simulation," he says.

"CAD packages are getting to the point where simple stress analysis can be done by the designer. So the stress group is moving away from analysis of isotropic [that is, a single component with uniform properties] materials... Luca and the group are now looking towards the very high level contact problems, complex assemblies and composite ply-by-ply analysis."

This work sees the group working on the optimisation of everything from the monocoque - where it is looking at optimising the ply direction of the composite material to achieve better stiffness and strength - to the transmission, from aerodynamic part to suspension components.

But driver safety is always the top priority, and a major worry. As Furbatto says, "Every time that something fails on the car when it is a structural failure, not due to contact with other cars, it personally hurts. But even from this kind of event we continue to learn." According to Furbatto, there is always that vital balance to consider: "You can make a tank, and it will pass all the strength/FIA tests, but it is not going to be very quick!"


A version of this article originally appeared in the October 2005 edition of Racing Line, the McLaren Group's in-house magazine.

Seamless Shift Gearbox

Changing Strategies

At last we can reveal the revolutionary principle behind the ZeroShift gearbox and how the company has progressed since it was last featured in these pages

It was in February last year that we broke thestory about ZeroShift’s revolutionaryseamless gearchange system. At the time itwas agreed with the company that wewouldn’t reveal how the design worked oncondition that we could break the story when itwas able to go public. It has taken a while butnow, for the first time in any magazine in theworld, we can reveal the secret of how theZeroShift system operates. Unless you areextraordinarily patient, you have probably readthe panel explaining already. If not, then we urgeyou to read it and experience that eurekamoment, then we can bring you up to date on thecompany and the latest progress with the system.When we first visited ZeroShift in late 2003 toresearch that first feature, the company was verynew and very small. It had been founded todevelop an invention by one of its founders, BillMartin. The technology allowed different gearratios to be selected without any break in thetorque delivery from the engine to the wheels.This was ZeroShift and that same principle is stillat the core of everything the company is workingon today. However, in the intervening period,much else has changed. Initial interest frominvestors has been turned into a firm financialfooting that allows the company to take a morethorough approach to developing the system,rather than rushing to market with a hastilyproduced product in order to generate funds. It has also enabled the recruitment of a very wellqualified and able team of people to take the ideaand transform it into something marketable.Having read the panel, you may be wondering,with such a simple and elegant principle to workwith, what is there to develop? In fact there arecertain issues that come about during the transferto the real world. The most obvious one is whathappens to all that inertia in the engine when youengage a higher ratio? You cannot dissipate 500 to1000rpm in a millisecond without producing a bigimpact and ZeroShift’s aim is to achieve a flatacceleration curve on a graph.Current transmissions break the torque duringchanges, however briefly, resulting in a hole in thecurve, while a raw ZeroShift system produces a spike as the inertia in the engine delivers amomentary increase in torque while the revs dropto match the road speed in the higher ratio. This isobviously undesirable due to the load it puts onthe drivetrain and the tyres. But smoothing out aspike is something that is achievable, unlike fillingin a hole which is not.The team at ZeroShift is working on a numberof strategies for smoothing the spike, the simplestof which uses the clutch. By briefly reducing theclamping torque on the plates during the shift, itallows a moment’s slip that dissipates theunwanted energywithout breaking thetransmission of torqueto the rear wheels.Other techniquesinvolve cutting the fuel,or spark, or both duringa change creating ahole in the engine’storque delivery that can be filled by the unwantedinertia. In addition the company is investigatingin-line, driveshaft dampers that can absorb theextra torque, smoothing its impact on theacceleration curve.The engineers also showed us otheridiosyncrasies with the system and varioussolutions to other issues that appeared duringtesting that, in the interests of competitiveadvantage, we have been asked not to reveal. Allthis may seem a little daunting, but the companyhas assembled a team of bright, enthusiasticengineers to tackle them. Their backgroundsinclude Xtrac, Ricardo, Cosworth, Jaguar Racingand Prodrive, and the issue is not so much a lack of solutions but a question of choosing whichones to follow. Head of design is Miles Ashcroftwho has served time at Xtrac, BAR, Nissan and cuthis teeth on jet engines. He has been overseeingturning the concept into a practical reality with aview to bringing a product to market.But in our original feature, we reported that bynow the company would already have its firstproduct, an aftermarket version of the T5 gearboxon sale. So what went wrong? Bill Martin ispragmatic and refreshingly honest. ‘Whathappened was two things. First, at that time wedidn’t know what wedidn’t know. Secondly,we have taken a morelong-term approach todoing things that willtake the companytoward seriesproduction.’ Theresponse frominvestors has put them in a much strongerposition and the need for a marketable product isnot as pressing as was first envisaged. ‘We havebeen spending a lot of time on automating thesystem and developing control systems.’ Work iscurrently focusing on NVH and FMEA. ‘It’s beenexciting because we’re learning quickly.’The original concept of ZeroShift was for apassive manual system that worked like anordinary stick-shift gearbox. That was fine untilthey started to incorporate systems to smooth outthe torque spike. Trying to synchronise theseelectronic shift management systems with themechanical input from a gear lever proved moredifficult than managing the whole process electronically, so the plan now is to operate thefirst generation of ZeroShift electronically.To develop this the company has recruitedAndrew Bowyer, an engineer with expertise inindustrial automation for manufacturing. LikeMartin, he does not have a background intransmissions or even automotive applications sohe brings no preconceptions about how thingsshould be done. ‘Most car companies are doing itas open loop,’ he explains, ‘our system is based onclosed loop control so it is self taught. The clutchsystem will be self taught and the cut to theengine will be self taught so it will be constantlychanging.’ Normally thecost of torque sensorsmakes this strategyprohibitive, but Bowyerhas developed a way oftackling it without one.This is anotherunexpected feature ofthe company, as the coreproduct drives numerousspin-off technologies thatZeroShift is registeringwith the intention oflicensing in the future.The team obviously has a great deal of talentand experience within it, but the burning questionis are they turning ZeroShift into a workablesystem? Our experience of the company’s longsufferingTVR test bed suggests it is. Even with thebare minimum of smoothing strategies inoperation the change is only betrayed by asubdued clonk and a barely perceptible surge. It really is a seamless change with no break intorque delivery, the big giveaway being the lack ofacceleration reversal at any point in the change.In fact, when demonstrating ZeroShift to potentialcustomers, the subject of luxury carsas suitable applications is often raised byrepresentatives of car manufacturers. The guestswill also ask to be shown the system without thecontrol systems to gauge its appeal to the sportsmarket in its raw form.So, when can we expect a ZeroShift gearbox onthe market? With less need to generate revenuethan originally anticipated, the company is takingmore care over its firstretail product. The fivespeedT5 originallyintended as a base is nowconsidered less suitable.Instead work is switchingto a production six-speedunit, and the team nowexpects to have anaftermarket ZeroShiftversion on the marketlate in 2006.And what about itsapplication inmotorsport? The company is currently in talkswith a number of outfits and while we were there,Ashcroft gave us a glimpse of a concept for aFormula 1 gearbox. This demonstrated the abilityto provide seamless selection of all seven gears ina unit as restricted as the smallest currently in usein F1 today. It seems this dynamic new companyhas some exciting times ahead.

[Source：Racecar Engineering Magazine June-2005]

THE STARTER MOTOR

當F1車手準備下場比賽時，他會帶著水瓶、安全帽、耳機，唯一他不用帶的就是車鑰匙，因為他不需要自己去發動賽車。
When a grand prix driver prepares to go racing, he carries with him a number of objects: water bottle, helmet and earphones among them. One thing he doesn’t take is a set of keys; but then again, he does not need them to start a Formula 1 car.

F1 V8引擎馬力比一般道路車大了十幾倍，所以不可能只是轉動鑰匙就能發動。
At the beginning of a race, a complex system is deployed to breathe life into MP4-21. Numerous components are utilised in this secretive action, without which the car would go nowhere. When you consider that a Mercedes-Benz V8 is around ten times more powerful than a road car powerplant, you realise that it takes more than just the twist of a key to get it running.

電子啟動馬達是一個外部的裝置，有一根長長的棒子可以插入變速箱的後部，當技師按下按鈕，就會有24伏的電壓送進變速箱來啟動引擎，啟動馬達連接著電源供應器，電源裝置在手拉的小推車裡
The electrical starter motor is an external unit, held by a mechanic, which features a long wand that is plugged into the back of the gearbox. In simple terms, when he pushes the starter motor’s button, 24 volts are put through the gearbox to turn the engine. The starter has a remote battery supply, which is fitted to a trolley and pulled by the mechanic, the car either being started on the grid before a race, or in the garage or pitlane during testing.

Mclaren的Sub-Assembly技師Andy Barber說"首先，把長棒插入變速箱裡"，"然後依照指示按下啟動馬達上的按鈕"，引擎啟動後工程師透過Laptop監控引擎轉速與油壓，直到滿意後才啟動引擎的點火系統
"First of all, the mechanic inserts the wand in the gearbox," explains Andy Barber, McLaren Racing Sub- Assembly Technician."He then receives a signal to push the starter motor button. This turns the engine over until the engineers are happy with the engine speed and oil pressure and – using a laptop – they will effectively turn the ignition on."

因為。。。。。。
"Because the motor has such a kick in it, there is a reaction arm which hooks up on to the rear wing to stop it coming out of the mechanic’s hand."



啟動馬達由齒輪組及離合器所組成，由於引擎的轉速是啟動馬達轉速的五倍，所以必須設置離合器。這是為了保護技師的安全，如果偵測到了任何異狀，離合器會自動分離，避免意外的發生。
The starter motor features a set of gears and clutch, and as the engine will move five times faster than this, for safety there is a sprag clutch. This acts like the freewheel on a bicycle, allowing the mechanic to withdraw the wand without any danger to himself. Another safety measure is the break-off clutch, which will prevent an accident should the engine backfire.

啟動馬達是在Mclaren Technology中心製造的
While the starter motor itself is an off-the-shelf unit, modified to cope with the high voltage passed through it, the wand, gears, clutch and electronics are all produced in-house at the McLaren Technology Centre. A range of materials are used for the construction, including aluminium for the main body and steel for the wand.

啟動馬達最重要的是可靠度，而不是輕量化，Barber說"過去F1曾經使用車載的啟動馬達，我們希望它越輕越好，所以我們使用air starter"。但是現在我們專住在它的耐用度，而它的表現也相當不錯。
"The starter is made to be reliable, not light, which is one of the benefits of having an external unit,"explains Barber. "In the past, when we had an on-board starter, we wanted it to be as light as possible so we used an air starter. Now we concentrate on durability and this is generally a trouble-free piece of equipment."

Technical Specification

Overall length: 120cm
Weight: 15 kilos
Power: 24 volts


A version of this article originally appeared in the April 2005 edition of Racing Line, the McLaren Group's in-house magazine.

[Source：http://www.mclaren.com/features/technical/starter_motor.php]

Asphalt VS. Gravel

砂石與柏油路面就像"粉筆和起司"
Gravel and asphalt are like chalk and cheese - but drivers in the FIA World Rally Championship must master both to stand a chance of winning the title .

輪胎的設計與選用還是扮演著最關鍵的角色
Tyres play a key role on both terrains; therefore good tyre design is one of the main components in the fight to create a car really in tune with the road conditions.

碎石路面輪胎設計使用較高海陸比，可以挖開鬆軟的沙石讓輪胎接觸到下層較硬的路面來得到抓地力。為了獲得較好的抓地力，WRC車手必須用更具侵略性的跑法。
Tyres designed for gravel have an open tread pattern that digs through the loose surface to find grip. WRC drivers need to drive more aggressively on gravel so that these can cut through to the solid surface underneath.

在碎石路面，輪胎還必須能吸收來自路面的衝擊及起伏，因此必須要有更厚的胎壁及更強的結構來緩衝這些衝擊。砂石路面輪胎胎高比柏油路面胎來個高，所以要搭配較小的輪圈。
On gravel, tyres also have to absorb bumps and impacts characteristic to the surface; therefore these have to have a deep sidewall and a strong construction to cushion the impact. The gravel tyre is taller than the asphalt one so it is mounted on a smaller wheel.

柏油路面輪胎的目的是要盡可能的使更多的橡膠與路面接觸
Asphalt tyres are designed quite differently. On tarmac the target is to get as much rubber in contact with the surface as possible. For this, the tarmac tyre has to have the least tread possible.

柏油路面比較平坦，所以輪胎設計比砂石胎硬的多來獲得更清晰的路感，並且有更扁的輪胎跟18inch的輪框。
On tarmac, the bumps are much smaller so the tyre has to be built harder to make the World Rally Car's handling feel very direct. These tyres have less of a sidewall and an 18-inch wheel.

輪胎配方的選用也是相當重要。軟胎能提供較好的抓地，硬胎則較
An important factor when selecting compounds is to try to find a compromise between grip and endurance. Softer compounds give a high grip but wear out quickly, while hard compounds offer less grip but last longer.

在雨胎的選擇：較硬的配方較慢熱因而抓地力較差，較軟的配方抓地力較好
In wet conditions, a hard compound tyre does not heat up so much, offering less grip, but softer compounds are more predictable in the rain.

下半季還有八場比賽，四場柏油賽事，四場砂石賽事。輪胎選擇依然主宰著比賽的勝負
The second half of the season has eight rallies left, four of them asphalt and the rest gravel. Choosing the right tyre for the conditions - and then using it correctly to master the surface - could play an important role in the outcome of the championship.
WRC ANALYSIS

Compression or Spark ?

Diesel versus Gasoline

John Judd’s company Engine Developments Ltd (EDL) powered the runner up at last year’s Le Mans race. That Pescarolo gasoline LMP1 car with its naturally aspirated 5.0 litre V10 engine finished just four laps adrift of the winning Audi V12 5.5 litre turbo-diesel after a full 24 hours of racing. For this year EDL has an enhanced 5.5 litre V10 and at the same time it is jointly developing with Ricardo a turbo-diesel derivative, to be able to fight Audi in future seasons like with like. John Judd Senior can therefore see the diesel picture from both sides, which is why I asked him for his views on it.

現行規則：Diesel 集器箱限流器面積比Petrol大50％
I started the conversation by referring to diesel restrictor sizes, currently some 50% larger than for the comparable gasoline engine. If you developed a gasoline LMP1 engine around an intake air restrictor area 50% greater than is currently permitted, I think it is fair to assume that you would have around 50% more top end power – something like 900 bhp?
“Yes, on top end power, with a petrol engine the horsepower is more or less proportional to the restrictor area.”

So why are the Audi and Peugeot turbo-diesel V12s, having that 50% intake area advantage, nowhere near 900 bhp?

“Because the diesel cannot use all of the air. With a petrol engine, with port injection or carburettors, you can essentially burn all of the oxygen. With a petrol engine horsepower is governed by the mass flow of oxygen – to all intents and purposes that is what counts.

features of the petrol engine (
“In fact by running the engine slightly rich of stoichiometric (Lambda = 1.0: the theoretical correct amount of fuel to combine with all the available oxygen) you make the most power. If you are running at about Lambda 0.92, you will draw out the oxygen molecules and combine them all with the fuel molecules in the time available for combustion.

“So you run richer than stoichiometric, at about Lambda 0.92. If you lean off from that, say to Lambda 0.94 or 0.95, you will get better fuel consumption but you start losing power. I would imagine this is pretty universal across this type of petrol racing engine. )

features of the diesel engine 「
“By contrast, the diesel, due to the nature of the fuel and the combustion process, it is not able to use all of the available oxygen. Unless you use a lot of excess oxygen it will smoke. You can get more power out of a diesel simply by chucking more fuel at it but it will smoke. If you have been to a tractor pull, you’ll have seen the mushroom clouds of smoke. So diesels are smoke limited. 」

壓力越高，分子越細小 ，燃燒面積越大
“Petrol is volatile and evaporates – if you put petrol in a saucer it will steadily disappear, whereas diesel fuel will stay there forever. You need very high pressure to atomise diesel – nowadays they are looking to 2000 bar. The higher the pressure the smaller the droplet size, hence the bigger the surface area presented by the fuel in the chamber.

噴射技術的進步，燃油分子跟空氣結合更好，但還有很多發展的空間
“Diesel has improved out of sight over the last few years in road cars, mainly due to improvement in injection technology. Pressure has increased tenfold, which has improved the ability of the fuel to mix with the air. So they are getting better air utilisation but it is still essentially an imperfect process.

汽油引擎：airflow增加50％，馬力也增加50％ 柴油引擎：增加供油，只會有更多的煙產生
"So in the case of a petrol engine there is a direct relationship between the amount of power that you can get and how much air you have. If you increase airflow by 50% you will increase power by about 50%. In the case of a diesel it is a case of how much smoke you are prepared to accept.”
We are saying that the diesel needs the excess air to avoid visible smoke – so if that wasn’t an issue, you could get 900 bhp?

柴油引擎的壞話：「 I don’t know about 900. So far as I am aware nobody really knows – it is only of academic interest, with no practical value. It is not just the smoke that you have to worry about it is also the gumming up of the piston rings, things like that. If you ever see inside a diesel engine you will see how dirty it is, compared to a petrol engine.

“There are a lot of practical problems with diesel, for example the unburned carbon particles will form a hard layer on the side of the ring lands, which can lead to piston seizure. Diesel engine development is difficult and very specialised.” 」

So what percentage air restrictor advantage for the diesel would be fair?

“I don’t know. The ACO doesn’t know – nobody really knows. Right now you have almost anti-diesel hysteria, with people saying that you can’t compete with a diesel engine. I don’t doubt that with the diesel particulate filter cleaning up the exhaust, the Audi can run a lap of Le Mans with a fair amount more power than we have, without producing visible smoke. But I cannot say for how long they would be able to continue to do that…

“It all comes down to how good a job they have done on the combustion system. I don’t know how that has worked out for them. It is my suspicion that thesy have got a useful amount more power than we have got but I don’t see that as the whole reason for their race performance as having been so good. Their race performance was pretty good before they had a diesel engine!”

You mention the power advantage over one lap but over a 24 hour race distance…

“I don’t know. Over a race distance they certainly have as much power as we have and they can get more from the engine. Diesel technology is evolving all of the time. Diesel road engines have become so much better over the last 10 years in a way that petrol engines haven’t. There has been an evolution in the technology of the diesel engine and I think that process of improvement will continue, although not so rapidly as we saw in the transfer from mechanical injection to high pressure common rail.

Audi的優勢 “I think diesel technology will continue to evolve and it is impossible for me to say what point Audi has reached. Obviously for them the Le Mans engine is a flagship project, so it has to be the best thing they have in the company.

You also have to consider the fact that the fuel they run is not average pump diesel. It is formulated for its purpose: you have to consider that a bit of an advantage.”

Also they have almost 3.0 bar boost: that must help the overall power curve?

diesel engine無法到達高轉速的原因：delay time of 柴油的燃燒特性 "They can’t work a diesel at high rpm. There is a delay between when they inject the fuel and when it burns and that is an almost constant figure so as rpm increases you get to a point at which there isn’t time to burn the fuel properly. So they have to go down the route of low rpm and high boost pressure to get the power.

“Let us say, for sake of argument, they have 650 bhp at 4500 rpm, which is a bit more power than we have got and we achieve our maximum power at 7000-7500 rpm. To achieve maximum power at 4500 rpm they have much higher mep and, due to the nature of the compression-ignition process, much higher peak combustion pressure as well. Our peak combustion pressure is around about 85 bar, whereas theirs is probably around about 200 bar.

“You need an extremely strong engine to withstand that sort of pmax.

最重要的還是Tractive Effort，引擎扭力再大還是，透過齒比輸出後又是另一回事
“Because the power is at relatively low speed, there is higher torque than we have but engine torque doesn’t really matter: the only thing that counts is tractive effort. It doesn’t matter what speed the engine is running at and what torque figure it is giving, that will all wash out through the gear ratios: what counts is the tractive effort at the rear wheels and that is a product of the horsepower the engine is making.

仍有待修改的規則 "One thing I think that is wrong with the regulations is that I don’t think the petrol engined cars should have to run the same car minimum weight as the diesels. The diesel is permitted to exploit certain engine advantages – they have got more power than we have – but they would have a very hard job to get their car below 925 kg. We could run less and to my mind the petrol engined cars are having to run the minimum weight that the diesels need. To my mind that is just as anomalous as last year giving the diesel the same tank capacity as petrol engined cars.

“I don’t like the fact that the ALMS rules are flexible but I do think it correct that they allow petrol-engined cars to run less weight. I think that 880 kg for the petrol LMP1 cars would be fairer for Le Mans and the ALMS.”

[Source : Motorsport-Guide.com]

So many Green Techs of GM in Frankfurt

GM公司宣佈它的E-flex版的Opel概念車將會在九月的Frankfurt展出。E-Flex設計是由電動馬達提供動力，由引擎發電或直接插電來提供電力。
GM has announced that it will reveal a new Opel concept car powered by its E-Flex propulsion system at September’s Frankfurt Auto Show. The E-Flex design features an electric motor that provides drive to the wheels, and runs on batteries charged by a secondary powerplant or even a household power outlet.

GM公司已經展示了E-Flex系統可以跟汽油引擎或氫燃料電池動力做搭配，現在又多了柴油引擎的選擇。而下一代的E-flex概念車是"GM's Hydrogen4"
GM has already displayed E-Flex vehicles mated with petrol and hydrogen fuel-cell powerplants, and is now set to reveal a version working in conjunction with an ultra-efficient diesel motor. Alongside the new E-Flex concept will be GM’s HydroGen4, the carmaker’s next-generation hydrogen fuel-cell vehicle.

圖中是Opel new Corsa 1.3L CDTI，GM宣稱它一公里僅僅排放119g的碳。另外還有新的渦輪增壓引擎和柴油引擎，可以使用E85生質酒精燃料及天然氣。最後，GM還會展出16款新環保的引擎及10款變速系統，可以增進油耗表現及減低CO2的排放，預計在2012年推出。
Also on display will be Opel’s new Corsa 1.3L CDTI (pictured), which GM claims will emit just 119g of carbon per kilometer. Other initiatives include a new range of turbocharged petrol and diesel engines, E85 Bio-ethanol motors and compressed natural gas powered vehicles. Finally, GM will unveil plans for 16 new engine families and 10 transmission groups, all designed at reducing CO2 and improving fuel-economy, for introduction by 2012.

VW's and Merc's Future Engine

VW公佈了一些有關將來eco-friendy engines的新技術。一個是新的混合燃燒技術CCS，類似柴油引擎，CCS將油氣混合的更完美，排放出更少的NO。但是CCS需要新的汽油來達到這項技術。Volkswagen has revealed details about some of its upcoming technologies planned for its cars, with most of the spotlight centered on more eco-friendly engines. First up is a new Combined Combustion System (CCS) engine technology. Similar to diesel units, CCS mixes the fuel and air ‘homogeneously’ inside the engine, which in effect removes any trace of soot and reduces polluting nitrogen oxides. CCS also requires a synthetic fuel for optimal results.

新的汽油"SynFuel"是從天然氣中提煉出來，目前有好幾個汽車公司在發展。 第二項新技術："汽油壓縮點火系統，GCI system"，能夠兼具汽油引擎的乾淨排放與柴油引擎的燃燒效率。GCI系統在車子起步及急加速的時候才點火，而在低負荷下改用壓縮點火。 這兩項新的技術要到2015年才會用在量產車上面。
The new fuel, called SynFuel, is derived from natural gas and is currently under development by several carmakers. Another engine technology is Gasoline Compression Ignition(GCI) system, which promises to be as clean as petrol motors but as efficient as diesels. GCI works by using spark plugs during start-up and hard acceleration, but relying on sparkless compression ignition, like a diesel, during low load situations, such as cruising on a highway. Both the CCS and GCI is planned to be introduced into production cars by 2015, 4Car reports.


Merc：儘管柴油科技已經突飛猛進，但是問題是他還是需要消耗柴油。在美國市場，加柴油比汽油來的難找許多。因此，Merc提出一項新的發展概念"DiesOtto"。 Diesel technology has improved by leaps and bounds, but the trouble is, it still runs on diesel. In the American market, at least, finding a diesel pump is still a pain compared to filling up with conventional gasoline. Mercedes-Benz says it's found the solution with a new developmental powertrain concept it calls DiesOtto.

好幾年前我們曾經報導這個概念，但現在已經製造出了雛型引擎。DiesOtto仍舊靠汽油運轉，但是卻擁有柴油引擎的優點。這個雛型引擎為一具1.8L四汽缸引擎，使用直噴、可變壓縮比、渦輪增壓與"controlled auto ignition"的新技術，產生高達238hp/295lb-ft的馬力及扭力，油耗達到相當驚人的39.2mpg。而且這些數據是搭載在S-Class車型上所測得的，這非常有可能造成全面的革新，無論如何，這真是該死的令人印象深刻啊！
We first reported on the project a couple of years ago, but the German automaker now has a functioning prototype. Rather than actually running on diesel, the DiesOtto engine is said to incorporate the benefits of a diesel engine, but runs on regular old unleaded. The prototype is a 1.8-liter four-cylinder engine that uses direct injection, variable compression, turbocharging and something MB calls "controlled auto ignition" to deliver 238 horsepower and 295 lb-ft of torque, with a claimed return of "less than 6 liters per 100 kilometers", which translates to 39.2 mpg. Those numbers, Benz claims, are not based on a small car (like the C-Class or smaller) but on a large sedan (like the S-Class). They may not be entirely revolutionary figures, but any way you look at it, they're damn impressive.

Merc並沒有說明這項科技何時會用在量產車上，只說這是相當適合新能源過渡時期的技術。 Mercedes hasn't put a timeline on producing and marketing a powertrain based on the DiesOtto prototype, but says it's a "feasible proposition in the midterm". We certainly hope so.

[Source：autoblog.com]