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More Details on the Lexus 600h L Hybrid Powertrain

Ls600h_002
LS 600h L.

At the Paris Auto Show, Lexus provided more details on the powertrain and performance of its luxury hybrid flagship, the LS 600h L, introduced earlier this year at the New York International Auto Show. (Earlier post.)

The Lexus Hybrid Drive in the LS 600h L combines a new 5.0-liter gasoline direct-injection V8 with large, high-output electric motors and a newly-designed battery pack to deliver more than 330 kW (442 hp) of total system power. Fuel consumption is rated at less than 9.5 liters/100km (more than 25 mpg US), and CO2 emissions are less than 220 g/km.

As with the Lexus RX and GS hybrid models, the LS 600h’s “600” suffix refers not to the cubic capacity of the engine but to a power output comparable to that of a 6.0-liter V-12 normally-aspirated engine.

Engine. The longitudinally-mounted 5.0-liter V8 gasoline engine is derived from the 4.6-liter powerplant in the LS 460. To reduce the overall weight of the engine, the cylinder block is die-cast from a lightweight, high-strength aluminium alloy. The block structure and rib reinforcement design have been finalized through the incorporation of cylinder combustion pressure data to minimize both vibration and noise. The engine head cover is also constructed in a lightweight magnesium alloy.

The new V8 features a D-4s (direct injection 4-stroke superior version) stoichiometric direct injection system, the world’s only automotive injection system to adopt two injectors per cylinder—one injector installed in the combustion chamber and a second mounted in the intake port.

The D-4s system’s port injectors employ 2 holes to inject fuel at a maximum pressure of 4 bar, while the in-cylinder injectors feature twin, 0.52 x 0. 3 mm rectangular slits producing a double fan injection pattern to effect the most homogeneous possible air/fuel mix.

Under cold start conditions, D-4s employs port injection during intake and direct injection during compression, producing a lean air/fuel mixture of 15-16:1. By concentrating the richer mixture around the spark plug it is possible to raise the combustion temperature, contributing to a quicker warm up of the Lexus thin-wall catalysts.

At idle, the engine runs on direct injection alone, due to its higher efficiency. In addition, and unique to the LS 600h and GS 450h, the electronic management maintains engine revolutions at an ideal speed to improve warm-up.

When the engine is running under a low- to medium-load at lower speeds, both direct and port injection systems are used during the intake stroke. This creates an homogeneous, 4.5: stoichiometric air/fuel ratio to stabilize combustion, improve fuel efficiency and reduce emissions.

When the engine is running under heavy loads, the direct injection system alone is employed. This achieves an intake cooling effect by injecting fuel directly into the combustion chamber, which improves the efficiency of each charge. It also allows for a higher engine compression ratio of 11.8:1, reducing pre-ignition tendencies and improving engine output and performance. Once again, a 12-15:1 stoichiometric air/fuel ratio is effected during the intake stroke.

D-4s substantially reduces combustion fluctuations in comparison to any conventional, direct or port injection system. D-4s realizes optimum engine efficiency throughout the power band and improving torque by 7.5% across the rev range, while minimizing fuel consumption and emissions.

The engine is also equipped with Lexus’ Dual VVT-i. This optimized, low-pressure loss, variable intake and exhaust valve timing system incorporates VVT-iE, the world’s first electric motor-driven intake camshaft, which operates across the full engine revolution and temperature spectrum.

Hydraulic VVT cannot operate below 1,000 rpm or during engine warmup. However, the Electric Motor Driven VVT system will operate across the full engine revolution and temperature spectrum, with a cam response speed of 50 degrees per second towards the lag phase and 50 degrees per second towards the advance phase.

Due to cam phase shifts when the engine stops, it is difficult to halt the cam at the optimum position for engine re-start using the electric motor alone. For that Lexus engineers have developed a mechanism employing frictional resistance and speed reduction gearing to hold the cam phase in the ideal position for engine start-up.

The new V8 further features a semi-dual exhaust manifold that reduces interference in the flow of exhaust gases, further improving output and combustion efficiency.

Motor and Electronics. The LS 600h Lexus Hybrid Drive employs a three-phase, permanent magnet AC synchronous motor, operating on a 650-Volt current, delivering more than 60 kW.

A change in the magnet distribution enhances operating quietness. Coiling the magnetic alternate, and hence holding the magnetic force, results in a smoother, more stable motor rotation.

The hybrid drive also consists of a generator; a high-performance NiMH battery; a power split device which combines and reallocates power from the engine, electric motor and generator according to operational requirements; and a Power Control Unit (PCU) to govern the high speed interaction of the system components.

All-wheel drive and transmission. The LS 600h features a new, mechanical, all-wheel drive system and a newly developed, dual-stage, electronically controlled continuously variable transmission.

The all-wheel drive transmission relies on a 3-differential configuration and a propeller shaft, coupled directly to the hybrid transmission.A permanently engaged mechanical transfer system distributes drive power with a ratio of 40% to the front wheels and 60% to the rear.

A center limited-slip differential optimizes grip, traction and vehicle handling on all-road conditions. Traction and grip characteristics are further enhanced by the vehicle’s advanced stability control system, Vehicle Dynamics Integrated Management.

As in the GS 450h, the Lexus Hybrid Drive’s electric motor, generator, power split planetary gear mechanism and motor-speed reduction gearing are all housed in one lightweight, highly compact transmission casing.

The combined installation of these components within a single compact casing is fundamental to the successful installation of Lexus’ hybrid drive system in a longitudinal, front-engine sedan platform.

The Lexus Hybrid Drive ECU selectively controls the rpm of the engine and electric motor, and the E-CVT (Electric Continuously Variable Transmission) simulates a continuous variation of the transmission’s current ratio. Similar to that of the GS 450h, the two-stage motor speed reduction gearing generates maximum low-gear torque for significantly enhanced acceleration, as well as extended high-gear performance for high speed cruising with improved fuel efficiency.

Comments

yo chill boys !!

yo! chill boys !!

agree to disagree!

Patrick

jw,
Are you now asserting that this forum requires formal writing? I simply pointed out that you lacked the ability to comprehend what you were reading in its entirety. If you would like to make this a “formal” writing event as your latest post suggests then I recommend the following:
1. “…I assume the next gen Prius…”
Don’t use “gen” as it is not a proper word even though it is found in common dialogue.
2. “…there is high tech being applied…”
Don’t use “tech” as it is not a proper word even though it is found in common dialogue.
Here is something quite interesting:
Right when you complain to my use of the term “such engine efficiency technology”, which you are completely unable to discern and decipher, you fumble through this statement: “Well, if other people buy the technology and it lowers fuel consumption, emissions, and so forth, it definitely has an impact on your life.” You have no concept of relating the article to the comments in a mildly abstract way (similar to someone using the terms latter and former in a written work) yet here you are using “and so forth”. I suggest you avoid vague and general phrases of that nature when you don’t understand how to comprehend them in a piece of writing.
3. “…Because [sic] that’s precisly [sic] what…”
Precisely includes an additional “E”. You left out a comma as well.
4. “Say you do an average of 15K miles per year, your monthly gas consumption should be around 38 gallons.”
You have a comma-splice in this sentence.
I see your multitude of problems are overwhelming indeed. Now I can understand why you have such problems with comprehension; it is compounded with problems of grammar mechanics and spelling.

You are lecturing on spelling, word usage and making exact specific statements yet you fail on every account.
I can suggest some resources for you if you would like.

jw

Amazing.

Patrick

Wrong, you attacked my comments without comprehending the entirety of them. You failed to understand the statement laid out in plain language. There was no need for me to defend the specific comment because you were wrong in your attack of my initial statement due to your lack of understanding of what was said.

I made no mention of grammar, spelling, etc until you brought it up because those little faucets of the conversation are inconsequential. Understanding what is being presented is not inconsequential. If you had understood the statement I made, in its entirety and with the context of the article being applied there would have been no need for any of this.

I didn't even go into it too far nor did I spend more than 5 minutes looking at your previous statements.

I say you failed to understand what you read and you say I am attacking you with petty name calling yet in the end what is it which you respond with? "dummy"? That makes for refreshing and highly intelligent discourse.

Patrick

Sorry guy, that was most definitely not me. The style and diction is obviously different from what I use. Without access to the server I have no way of providing any evidence to support my statement though.

Patrick

BTW- the only time I have had a comment "yanked" (as far as I know) was due to the inclusion of three "x"s in a row when I was trying to illustrate a variable.

Patrick

Funny how you think there is something to "win" here claiming that there can be a loser.

Roger Pham

Hi Patrick,
I can identify with the essential of what you're saying. I've vowed to myself never to buy any cars with more than 4 cylinders, because it will simply be a wasteful practice. Also, being an occasional weekend mechanic, I would much rather work on a 4-cylinder engine with a wide-open engine bay than that of an ultra-crowded 8-cylinder super-duper vehicle. I guess Lexus mechanics must be paid higher to put up with the crowding of an 8-cylinder Lexus engine compartment.

However, the wasteful-rich don't care about burning fuel needlessly, and gas-guzzler tax is but a joke on cars costing above $100,000USD, so, little effort is made to make uber-luxury car fuel-efficient.

Therefore, Toyota should be applauded for giving the rich a chance to burn more $$$$(money) than gasoline! Money is renewable, so it's okay to burn as much as they want, where as petroleum is not renewable. Except for Hydrogen made from renewable sources, and for that, BMW should also be applauded also for their initiative on the BMW 7 super hydrogen burner. Burning both renewable cash AND renewable fuel in large quantity, what more can a rich man ask for?

Fred

Carnot Efficieny trumps all, we are chasing ever diminishing improvements in the IC engine. Turbos, VVI and Direct Enjection are getting real close to 33% efficient; there will be no further Leaps of efficiency in an IC engine.
Put the money into transmissions and batteries, you'll get more bang for the buck.

lensovet

christ people, chill out.
anyway, what bugs me most here is that a lot of the "innovations" here are just overblown, existing technologies. take this loaded sentence:
The hybrid drive also consists of a generator; a high-performance NiMH battery; a power split device which combines and reallocates power from the engine, electric motor and generator according to operational requirements; and a Power Control Unit (PCU) to govern the high speed interaction of the system components.
um duh, it's called a hybrid....
anyway, it's interesting to see this project move forward and i can't wait for this car to come out. it doesn't matter how people drive it, what matters is that they drive it. take a look at the GS 450/430 ratio – three quarters of those cars sold are hybrids. the people who bought them would have simply gotten a 430 instead, they would NEVER even CONSIDER a prius or civic hybrid.

let me repeat. yes, this car is overkill in terms of every feature imaginable, including horsepower. but that really doesn't matter.

i'm much more interested in the following: how come they have a mechanical connection between the front and rear axles/wheels? wouldn't it be safer and simpler to just stick an extra electric motor on the back wheels?

Patrick

Reduced maintenance and parts sourcing (simpler) but much more difficult to create the code to insure at all points of operation the right amount of torque is produced from an electric motor to match the needs from the front motor, driver, and traction conditions. Much less challenging than the 4 in wheel motor concepts we have seen though (the Mini EV conversion and Mitsubishi's MIEV).

pialwtaafi

What a cool car! I wish I were older.

haha

This could be the dumbest car ever. Asians will never get it right. They should stick to tin cans but good on gas (accord, prius, eclipse, civic, camry). They should leave nice cars to the big boys (GM, Ford, Mercedes and the rest of europe). And the asians are the only ones pursuing hybrid as deisel is the way to go. Too bad no one told them hybrid is a bad idea

madpistol

This is directed at haha.

Ford and other companies do a crappy job at creating large cars compared to Toyota. Here's why:

The 2006 Ford Fusion has a 3.0L V6 engine that produces 221HP and has a fuel economy of 27MPG highway.

In comparison, The 2007 Toyota Camry has a 3.5L V6 engine that produces 268HP and has a fuel economy of 31MPG highway.

Now, no offense, but from this, I can see no reason to buy a Ford car. Toyota/Lexus gives you more power and better fuel economy than a Ford. I'd say that pretty much sums it up. Toyota wins.

Gary

Oh for crying out loud ... who isn't sick of having low mgp hybrids barfed up on us?!? I'm about ready to junk our perfectly good RX-400h, if Lexus (or Toyota Hylander) can't get their s**t together.

How stupid can they be?!? How many folks have to continue screeming at them, "screw the power, and give us better mileage !!". What is their problem. We are getting so sick of their ad guru's steering them in the wrong direction. We are TIRED of funding Bin Laden & their buddies. GET IT?

Roger Pham

Gary,
If you want maximum mpg, just quietly sign up to buy a 2007 Prius. Then, by 2009, when the next-gen Prius will offer ~90 mpg, then trade in your 2006 Prius for the spanking new one.
Happy?

Meanwhile, be happy that Toyota is the ONLY car company who offers that kind of exceptional gas mileage for a car packing over 440 hp. Get it? No other car company are getting anywhere near 25mpg in a ~$100,000 car packing over 440 hp!! The average for a car in this power range is ~13-15mpg. Now, the environmental-concious rich can have an unique opportunity of burning more money than petrol!

More seriously, production numbers of these flagship uber-cars will amount to less 0.1% of regular models. The real public and environmental menace is the monstrous 6000-lb SUV's or large extented-cab pick-up trucks averaging 15mpg, and they are roaming everywhere.

Sione

Why not ditch the electrics altogether and build a petrol/petrol hybrid? You can have the big multi-cylinder engine waiting on stand-by for accelerative purposes and use a small engine to handle base load and cruising duties. Two (or more) engines could have their output combined by an epicyclic gearbox system analogously to Toyota's petrol/electric hybrid system of today or similar to the "father & son" marine set-ups used on fast ferry-boats. To optimise the whole set up it shouldn't too difficult to cast a single engine block to contain multiple prime movers. By doing this sort of thing everything remains warm and ready to go.

Performance and response would be excellent. Economy would be at least as good as the 600h (probably better). The purchase price and life-cycle cost would be lower (much lower). The entire thing would weigh a lot less (no battery pack obesity to lug around all the time). Simple engineering, do-able now should the public really be interested in efficiency or emissions (which I'd contend when it comes to brass tacks no-one really gives $2 about).

nick e. buhia

what is the meaning of D4-D?

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