Le Mans 2015 [wec]

[Guest EC2277]

Infatti la Williams utilizzava un KERS elettrico, nel quale le batterie erano sostituite da un volano-magnete.

https://www.youtube.com/watch?v=YgusgbHX0-Y

Kers per la F.1 - IL VOLANO MEGLIO DELLA BATTERIA? - Quattroruote

Questo dovrebbe consentire di avere un'unità meno pesante e consente alla Nissan di mantenere aperta la possibilità di realizzare un futuro sviluppo della vettura a 4 ruote motrici.

[ISO-8707]

Infatti la Williams utilizzava un KERS elettrico, nel quale le batterie erano sostituite da un volano-magnete.

https://www.youtube.com/watch?v=YgusgbHX0-Y

Kers per la F.1 - IL VOLANO MEGLIO DELLA BATTERIA? - Quattroruote

Questo dovrebbe consentire di avere un'unità meno pesante e consente alla Nissan di mantenere aperta la possibilità di realizzare un futuro sviluppo della vettura a 4 ruote motrici.

Questo è esattamente il sistema utilizzato sulla Audi R18 ed infatti è stato fornito dalla Williams

Nissan utilizza un sistema diverso, ma non sono ancora riuscito a trovare degli esplosi, disegni o schemi da cui se ne possa carpire il funzionamento.

Describe the GT-R LM NISMO’s propulsion system

“In simple terms we have gone with a petrol-electric propulsion system comprised of a compact, twin-turbocharged 3.0-litre V6 internal combustion engine (ICE) petrol engine, and a mechanical flywheel kinetic Energy Recovery System (ERS) that runs in the 2MJ class. Turbocharged V6 engines are something of a NISMO speciality, so our philosophy for the ICE was to build a super-efficient version, which has excellent drivability at relatively low rpm. It’s very, very torquey with a very flat power curve, which means we need only run with a 5-speed gearbox. This means we’re changing gear less and putting less wear-and-tear on the transmission components. The engine also has spectacular thermal efficiency, so we extract the most power we can from every last drop of petrol we use.”

What about the Energy Recovery System?

“We are running a flywheel-based energy recovery system, as Audi does, but where they use an electrical linkage we have gone with a mechanical system. It’s different and it’s smart and it has huge power potential. In tests on the dyno we’ve comfortably produced 1100bhp from our 8MJ KERS system alone. Combined with the internal combustion engine means have the potential for a little over 1600bhp at our disposal.

“Unfortunately due to the project’s extremely challenging timeframe – less than a year to form the team and design, engineer and develop the car from scratch – we’ve had to be pragmatic and scale things back with the hybrid system for this year’s Le Mans. That’s the flipside of innovation: it hurts when all the pieces don’t quite come together in time. However, we are going to learn a huge amount about getting the maximum from the V6 petrol engine in this year’s race, an you can be sure we’ll be back at Le Mans with full force in 2016.”

Ben Bowlby, NISMO, Q&A - Racecar Engineering

Modificato 14 Giugno 2015 da ISO-8707

[Guest EC2277]

Allora probabilmente è un volano supplementare, connesso all'albero motore (od alle ruote) mediante delle frizioni azionate elettronicamente.

In poche parole quando il pilota rilascia l'acceleratore e frena, la centralina fa innestare le frizioni ed il motore comincia a trascinare in rotazione il volano supplementare; il quale può così immagazzinare energia. Le frizioni poi si disinnestano automaticamente quando il pilota ricomincia ad accelerare ed il volano ruota libero, fino al momento in cui il pilota aziona il KERS. A quel punto le frizioni si reinnestano ed il volano cede energia al motore od alle ruote, aiutando la vettura ad accelerare.

Ovviamente si tratta di un sistema molto semplice, efficiente, robusto e leggero, ma che richiede un sistema di gestione delle frizioni estremamente complesso, per non causare degli "sbalzi d'intensità del freno motore".

Ho letto poco e frettolosamente riguardo a tale auto, ma mi pare che la Nissan abbia eliminato il KERS proprio per problemi nella gestione del freno motore; od ho capito male?

[Stiletto]

Si, il motivo principale è l’instabilità che tale sistema genera all’avantreno durante la fase di ‘recupero’ in frenata e al retrotreno, durante l’erogazione, che rende la vettura nervosa e difficile da controllare. Ma anche così com’è ora (trazione anteriore) è difficile da guidare a causa delle violente reazioni sul volante ad ogni accelerazione: il pilota alla fine del turno ha le braccia distrutte …

Ma credo anche che ci siano altri problemi sull’ibrido Nissan. Uno di questi è il peso. Inizialmente dovevano essere usati due volani, ma visto che la GT-R è già sovrappeso si è scesi ad uno, presente a bordo, ma inutilizzato. L’altro mi pare sia relativo all’ACO che non sarebbe in grado di misurare l’energia effettivamente recuperata dal sistema Nissan essendo questo totalmente meccanico.

Ad ogni modo è un colpo al cuore vedere addirittura le GTE tenere il loro passo nelle curve lente e talvolta essere anche superiori. Quando una Porsche 911 RSR deve scartare improvvisamente a destra per non tamponare una LMP1 in uscita da una ‘esse’ si capisce, purtroppo, che il progetto è quello che è …

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Trovato!

Questo dovrebbe essere concettualmente simile (viene prodotto dalla stessa azienda) a quello montato sulla Nissan

A British firm has developed a new form of automatic transmission that it says can cut fuel consumption on SUVs and trucks by 20 percent when compared with a conventional automatic gearbox.The company, Torotrak, says that the cost of its Infinitely Variable Transmission is comparable to a conventional auto box, and it is looking for an American company interested in building the units for sale to American manufacturers. GM has already tested the Torotrak system and approved it, and although the company is not prepared to build the transmissions itself, it would be prepared to look at proposals from any of its Tier 1 component suppliers who were prepared to undertake manufacture of the gearboxes.

The Torotrak transmission differs from a conventional automatic in that it has no torque converter. The torque converter transfers the drive from the engine to the gearbox by means of a fluid coupling that takes the place of the mechanical clutch used in manual transmissions. The fluid allows the drive from the engine to “slip” while the car is at rest or while shifts are being made, thus making it unnecessary to disengage the drive using the clutch.

Slipping into economy

Torque converters are convenient for drivers, but are inherently inefficient because of the slippage, and this inefficiency makes itself felt in gas mileage.

In place of the torque converter, the Torotrak has a system of two clutches in which the drive is transmitted by variators. The variators are discs that run in contact between two dished clutch plates, transferring the drive from the input plate to the output plate and performing the job carried out by the transmission fluid in a torque converter. Slippage is minimal, however, and the power losses and consequent fuel consumption associated with the torque converter are drastically reduced. By varying the angles of the variators, the drive ratio can be changed infinitely, and by using a system of lockable clutches and a planetary gearset, the drive transmitted to the road wheels is totally seamless, unlike that of a conventional automatic, in which fixed ratios are engaged as required. The Torotrak thus combines the advantages of the torque converter – clutchless drive – and the CVT, or Constantly Variable Transmission, which achieves seamless power transmission through belts – which can be prone to slippage – running on variable circumference pulleys.

The Torotrak’s increased fuel efficiency comes partly from the absence of the torque converter and partly from the fact that the gearbox is capable of sustaining very high overdrive ratios, with 70 mph per 1000 engine revolutions being easily achievable.

Another advantage of the system is that it is capable of ‘slipping’ without the overheating that comes from running a torque converter in this way for any extended period of time. Although a car with a conventional automatic can be held on a hill by leaving it in Drive and applying the throttle gently, if this is done for too long the transmission fluid will overheat. With no fluid present, the Torotrak can be held on the throttle for much longer periods. An advantage of this quality — which has great potential for off-road vehicles — is the fact that the gearbox can slow the vehicle on descents. This is done by engaging reverse and allowing the slippage of the clutches to work against the weight of the vehicle. The engine is effectively trying to drive the vehicle back up the hill, and the rate of descent can be controlled very precisely.

In production vehicles, it would not be necessary to select reverse gear physically. Since the gearbox is completely controlled by software, it would be a simple matter to write the software in such a manner that when ‘Hill Descent’ is selected with a dashboard switch, the gearbox takes over automatically. Another advantage of software control is that the gearbox software settings can be controlled by a “smart key.” In the same way that the keys of individual drivers can now set seat positions and radio selections to personal tastes, the gearbox can also be controlled for individual drivers. The possibility of setting maximum speeds for teenage drivers is an obvious advantage of this system.

Principles in motion

Torotrak has been in existence as a company since 1998, and the Torotrak system has been under development since 1988, but up till now only a few industry engineers have had the opportunity to drive Torotrak-equipped vehicles. I was among the first journalists to sample the system, fitted to one of fifteen Ford Expedition SUVs that Torotrak has converted to demonstrate its capabilities. Torotrak has identified the SUV/truck market in the U.S. as a major opportunity, and it was to show how the system worked in such a vehicle that the firm chose to work with the Expedition. For the moment, the work is concentrated on rear-drive vehicles, which constitute the biggest proportion of the market, but an all-wheel-drive Torotrak system is feasible.

On the road, the Torotrak behaves like any other automatic. The PrNDL selector is the same, and after selecting Drive the Expedition moved off quite normally. Acceleration is no swifter than a standard automatic, but the big vehicle, with its 5.4-liter engine, was soon able to reach a good freeway cruising speed, blending in with other traffic from the entry-ramp easily and smoothly. Smoothness is the keyword with the Torotrak, which gave totally seamless acceleration, with none of the clunks or jumps that can come with a badly-adjusted automatic.

Once at cruising speed on the freeway, it was fascinating to see the rev-counter hovering around the 1000 mark as the speedometer indicated 70+ mph. In town and on country roads, the drive was smooth, and torque was always available for moving off or acceleration. Where engine braking is required, the company’s engineers have built in low-range locks similar to those found on conventional automatics.

Torotrak has measured the consumption of the Expedition, not on the road, but in statutory fuel-consumption tests that are more reliable and repeatable, and has found that the Expedition equipped with the company’s transmission is consistently 20 percent more fuel-efficient than the standard vehicle.

Descending power

Off the road and on the test track, I was able to sample the Torotrak’s ability to control speed on a steep descent. With reverse selected, the big SUV could be held stationary on a 25-percent downward incline just by gentle pressure on the accelerator. When the accelerator was released, and the vehicle’s weight took over, the Expedition rolled slowly downhill. It was strange to see the way it started to reverse when it arrived on level ground. Naturally, in a production model, software would select reverse when required for this purpose and release it as soon as it was not needed. Going back up the 25-percent grade, the Expedition could again be held stationary on the throttle, this time with Drive selected.

The Torotrak company has no plans to start producing gearboxes using its technology. It is structured purely as a technology provider, and it licenses specialist manufacturers to develop and produce their own gearboxes using Torotrak principles. Currently, Getrag of Germany and Japan’s Aisin AW hold licenses, but no U.S. manufacturer has yet joined them, hence Torotrak’s work on proving the feasibility of the transmission for SUVs and trucks, which are currently seen as the world’s largest potential market for the unit.

Torotrak: The Next CVT? - The Car Connection

[xyzteam]

24 Ore di Le Mans - Gené: "La GT-R LM Passerà Alle Quattro Ruote Motrici" - Quattroruote

[Aymaro]

Peccato per la Ferrari #51 nel GTE, prima fino a poco fa grazie ad un mostruoso bruni, fermata da un problema al cambio

[Guest EC2277]

Trovato!

[…]

Hai sbagliato video : il tuo spiega come funziona il cambio toroidale, che collega il volano-accumulatore alla trasmissione. Quello che spiega come funziona il sistema nel suo complesso è questo:

Grossomodo funziona come ho ipotizzato io. Con la differenza che io ho pensato a delle frizioni, mentre loro (giustamente) usano un cambio toroidale; mi ero dimenticato che esisteva. In poche parole il sistema di comando dei dischi intermedi, cambia il rapporto di trasmissione a seconda se il volano deve accumulare, conservare o cedere energia.

Bella trovata, mi piace molto di più dei sistemi ibridi veri e propri.

Modificato 14 Giugno 2015 da EC2277

[ISO-8707]

Hai sbagliato video : il tuo spiega come funziona il cambio toroidale, che collega il volano-accumulatore alla trasmissione. Quello che spiega come funziona il sistema nel suo complesso è questo:

A me interessava quello come funzionasse il sistema nel complesso lo sapevo già

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-5 minuti

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Bella gara, vittoria meritata della porsche.

Modificato 14 Giugno 2015 da ISO-8707

[ISO-8707]

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