How to prolong the life of your petrol-engined car!

[:::Jerry::::]

You have to be moving first though..... You'll never put back, under regenerative braking, what gets taken out, otherwise you'll have designed perpetual motion !...

[:::Jerry::::]

[ bellow quoted by IMM ]

Trouble is, there are many 'normal' cars and trucks that have done that sort of mileage.

[:::Jerry::::]

So you think a service is just an oil change then, it might be to your slap-happy DIYer or back street grease monkey but to any half decent garage it's but a small part of the job.

[IMM]

Don't tell fibs. You are jealous.

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[Clive Summerfield]

Hmmm, interesting use of the concept of "simpler" there. Sure you've removed the complexity of the gearbox, but unless you're happy to treat the Prius' transaxle mounted power splitter as a simple black box of magic, you can't in all honesty claim that the car has "no complex transmission". And in fact, that's pretty much what you are doing by claiming "juts a planetary gear assembly". In the Prius this is achieved (iirc) by having the ring gear linked to both the diff and the motor, the IC engine linked to the planet carrier and the generator linked to the sun gear. The Prius is, after all, a parallel hybrid, not a serial hybrid and so there must be some method of taking power from the IC engine to the both the road wheels and the generator(s), and also taking the output of the electric motor(s) to the road wheels.

And by no stretch of the imagination could you describe the internal workings of an Atkinson engine as simpler. Especially when you consider what is required to a) achieve all four strokes of the Otto cycle in one revolution of the crankshaft, and b) have a power stroke that is longer than the intake stroke. And while the Atkinson engine doesn't require a seperate camshaft (or shafts) I wouldn't be too surprised if the Prius maintained a more conventional camshaft approach in order to take advantage of variable valve timing. In fact I'd hazard an educated guess that the Prius's engine, in spite of Toyota's claims, is more akin to a Miller cycle than an Atkinson. I can't imagine Toyota choosing the mechanical complexity of the Atkinson over the equivalent Miller cycle.

So I'm afraid your "simpler" claim doesn't really hold water. Especially when you take into account all the additional electronic systems required to monitor and control the hybrid system. And given the poor standard of electric on mass market cars from Ford, Vauxhall, etc, I'd hate to drive one of their hybrids.

Personally I think the future lies in serial hybrid cars based on the Stirling engine, albeit in the longer term once battery technology has advanced sufficiently to make serial hybrids practical as light vehicles. And if you incorporate a regenerator into an alpha-config Stirling engine then you can dramatically improve efficiency by both pre-heating and pre-cooling the gas in the closed cycle. Another advantage is that you're not tied to a specific fuel for the Stirling engine. Pretty much any fuel that can produce heat can be used. As the Stirling engine is most efficient under static load, then it is eminently suitable for use in a hybrid driving a generator. And by seperating the combustion from the actual drive mechanism, you can optimise both with fewer compromises.

Oh, and the only new thing about the Prius is the electronics. The rest of the technology has been around for years. Atkinson developed his Otto-variant in 1886, Miller produced his approach in 1947, planetary gears date back over 2000 years and electric motors and generators also have their origins in the 1880s.

Cheers Clive

[John]

SNIP

For those that are interested, a browse of the "how stuff works" site is useful in this context

[The Natural Philosopher]

Neat idea, totally circumvented by turbo charging, when you can effectively get any sort of performance you like.

[IMM]

You really don't know do you!

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[IMM]

You can. The power splitter is not a power splitter, it splits torque not power. It spliits torque from the engine to the wheels or generator. It is simple, very simple. It is just a planetary gear cluster. It just spins on bearings. Simple. It is NOT a CVT, as many desribe it.

this for the description and this:

the diagram at the bottom.

Brilliant idea. Just a planet gear with an IC engine and a motor connected and a generator. No transmission using step gears or a belt CVT as we know it. In short, no complex transmission. Transmissions absorb a hell of a lot of power and give a lot of extra weight too.

Wrong! It is serial/parrallel hybrid. It can run on:

- The engine only,

- The electric motor only,

- Both.

The planetary gear assembly does all that. Simple and brilliant. So much so, Ford have licensed it for the Escape, which is available right now, and most other makers who missed the hybrid development evolution stage are licensing the Toyota transmission too. By the end of the year Toyota will have three or four hybrids on the market, one a Lexus, with most other large makers at least one.

They have done it by variable vale timings. It is not a full Atkinson that does all 4 strokes in one rev of the crank. A sort of half way Otto/Atkinson.

The engine is effectively in top gear most of the time, the electric motor fills in the torque for the lower range.

That is a bit rich, as you know sweet FA about this car and how it works Don't you feel ashamed?

Batteries have come a hell of a long way. The Prius' batteries are guaranteed 8 years, while 12 years plus is expected, while Panasonic say 15 years is the life span.

The Stirling is the next step. External combustion and super smooth and quiet.

It uses a burner.

Yep. Except the advanced batteries.

Yep. But none of them were that efficient. Porsche produced a hybrid in

1902 or so, it went like hell on two electric motors. The motors were 250 lb each.

Many think the Prius complex, it is not, it is simpler than a normal car. It has a larger battery pack, no starter motor, but has an inverter that is extra to a normal car.

No complex conventional power sapping transmission, no starter motor and the only extra is an inverter. It has a management system, so do all cars these days, it is just bigger.

They are exceptionally reliable and cheap to run and service. The electric part is virtually service free. The engine runs at optimum conditions most of the time so the wear factor is super low on that.

Unless someone comes up with a cheap workable fuel cell car, hybrids will take over. In the US the electric part is being replaced by hydraulics for commercial vehicles.

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[:::Jerry::::]

You couldn't be more wrong, as usual, even if you tried to give me one or both I would say no thanks.

[Dave Plowman (News)]

Since you've never driven one let alone own one - or a DB6 - I'll treat that with the contempt it deserves.

Auto Express do not conduct accurate tests.

[Dave Plowman (News)]

It's been common on large engines - say ships etc - to analyse oil as to its continuing effectiveness rather than simply changing it. And exactly the same can be done with a car engine. Indeed service indicators are either available now - or on the horizon - which do just this on some upmarket models.

[Dave Plowman (News)]

If they became the norm, you'd soon say goodbye to any existing taxation incentives...

[Dave Plowman (News)]

So you've got a BMW too?

My old 528 did approximately 10,000 miles between oil changes on the recommended semi-synth. The later 530 is approx 15,000 miles on fully synthetic. The engines are basically the same.

[Dave Plowman (News)]

Anyone with a shred of mechanical knowledge would realise that an onboard petrol engine charging an onboard battery is merely a ploy to reduce emissions in city centres. Like for like it *must* be less efficient than direct drive. Of course the maker pulls every trick in the book to make it seem to work

- low friction tyres, low weight, low drag. Use the same technology on any conventional car and the results would then be directly comparable. However, in this real world, a small diesel will both out perform - consistently, ie when the hybrid has exhausted its small battery as happens regularly in practice, and most certainly when cruising.

Autocar drive all their test vehicles over a standard route, designed to simulate the sort of conditions most would encounter. Of course it's by nature a compromise, but provides a very real comparison between makes.

The Prius managed 44 mpg. A Ford Focus 1.8 diesel 55 mpg.

Hard driving is even more revealing. Over the duration of the Autocar test, which involves performance testing, the Prius only managed 23 mpg. The Focus 44 mpg. And the Focus has better performance in every way.

[Dave Plowman (News)]

Perhaps you'd like the relationship between power and torque explained?

[IMM]

Which you don't.

So, no hard evidence whatsover.

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[IMM]

Wouldn't touch one with a barge pole. I don't live in Essex.

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[Dave Plowman (News)]

Give us the benefit of yours, then, pet. Even Michael Howard attempts to answer things.

[:::Jerry::::]

Unless the science has radically changed since I talked at length to an oil spectrum analyser (if that is the correct title) about this very subject[1], most main dealers would not be in a position to do it and it certainly couldn't be done in-car. Indeed the person I was talking to worked for the then British Rail analysing oil samples from the locomotive fleet (aka very expencive medium diesel engines), all samples from the various depots were sent to a central lab - if BR couldn't afford to have regional labs what chance the motor trade.

[1] I was in need of having an oil sample analysed from a preserved locomotive I helped maintain.