Concept
schmoncept
Suzuki has whipped the dust sheets off its Swift plug-in hybrid at the Tokyo Motor Show. Swift_002 Suzuki's Swift: mini EV The runabout is driven by a 54kW (72bhp) electric motor which draws its juice from a lithium-ion battery squeezed into the centre console between the two front seats. A full battery charge will propel …
Currently own a swift and it's a nice workhorse. I would however question the financial sense of making a fairly efficient little car (55-60 mpg on my motorway commute) a little bit cheaper to run. Surely the market is cars like bentlys where they cost so much to run that a decent motor and battery pay for themselves in a year or two rather than having to run the car into the ground for 4-5 years to make up the difference.
"A full battery charge will propel the car roughly 20km (12.5 miles), Suzuki said, after which a three-cylinder, 660cc petrol engine fires up to drive the electric motor through a generator."
Shirley it would be a lot more energy efficient to use the petrol engine to drive the wheels directly through a gearbox? Now there's a revolutionay way to save energy.
In all seriousness my neighbour gets fewer MPG from his Prius than I do from my similarly sized Lancer. So in what way are these hybrids saving the planet?
Due to taxation peculiarities, Japan has managed to polish the 660cc engine to an absolute perfection. Both Suzuki and Daihatsu examples in this class are capable of delivering crazy amounts of torque and power-to-mass ratios. Taxation used to put a power limit on it so none of these delivers more than around 60bhp. These engines can happily pull along a car of swift/sirion/micra size even in motorway conditions while leaving enough space and weight budget to fit an electric motor and battery. Their only downside is that they need some tweaking to fit the pollution reqs for EU and USA.
It is surprising why it bloody took both of them so long to use one of the prime pieces of engineering IP in their portfolios. Finally, about bloody time.
That's not even enough to get me to work in the morning. And we don't have any outlets in the parking lot.
Plug-in cars will not succeed in the US until you can go ~400 miles in any direction without stopping for a charge, and then are able to recharge it in a few minutes before continuing.
The only particularly powerful 660cc engines in Kei cars are turbocharged. Trust me I've owned a couple of Miras (a 2WD and a 4WD) and while the engine can deliver 85bhp (more with a new chip) it uses fuel like a bigger engine. Sure my Miras were capable of 0-60 in under 9 seconds, but that was because they were light.
That's the thing about internal combustion engines, it's not really the capacity that governs efficiency or power output, but the amount of air you can make it pump. You mix the air with fuel and burn and the more air you use the more fuel you need. So in other words if you make a small engine move as much air as a bigger engine and you will use as much fuel. Using a turbo will make a small engine produce good power and or torque at mid to high revs, but it will do nothing at high revs, but it won't work at all at low revs and because you need a low compression ratio to deal with the boost you end up with an engine that is even more feeble at low revs.
The end result of which is that in order to get reasonable performance at lower speed you need to use plenty of revs, which will be less fuel efficient than a larger engine with a similar peak power output.
Austin Rover tried to deal with this by using a high compression ratio. This worked to an extent, but limited the boost they could use. And also meant they needed some clever (for the time) electronics to limit mid range torque in order to protect the transmission.
Lancia and VAG have tried using a supercharger for low revs and a turbocharger. This sounds like a great idea. Indeed VAG claim their engine has the economy of a 1.4 with the power of a 2 litre, if this is the case why do they still make 2 litre engines? Because if they put it in a big car it would prove to use just as much fuel as the 2 litre engine. The other problem is that such an engine is much more complex and expensive to make than a conventional engine and of course more expensive to service.
The reason for the popularity of the 660cc engine in Japan is down to the Kei car regulations. Basically you are limitted in some cities to 660cc, along with power, speed and size restrictions unless you have your very own reserved parking space. So the engines have evolved to meet a niche requirement. If they were the solution that you seem to think they are, do you not think that Japanese manufacturers would be using them in the cars they sell over here?
Yup, they're great for powering a Copen or a TR-XX, but they just wouldn't do the job in something bigger.
For my sins, I drive a Toyota Prius. I am right fed up (insert other words of emphasis to choice!) with its appalling mpg compared with all sorts of cars of similar size, but without the added weight burden of electric motor and battery. The reason for Toyota's errors is that they got the basic design principle wrong. The Prius is a petrol car with a bolt on extra electric power pack.
This Suzuki machine, like the Volvo Recharge project car, is an electric vehicle with a bolt on generator. I suspect that the design will be much simpler without the CVT gearbox and other stuff necessary for a mechanical transmission. When they get the motors into the wheel hubs (as Volvo were doing last time I looked) they can do without mechanical brakes and rely instead on regenerative/resistive loads. Fewer mechanical bits to go wrong, easier car to look after.
"it will be a beautiful day when the city streets are free of automobile pollution."
Yet another selfish city dweller. So long as city streets aren't polluted you don't care about the rest of the planet? Lovely person you are.
The only way to really discourage people from producing pollution is to visit the results of the pollution upon the polluter. The supposed "zero emission" electric vehicle quite obviously is nothing of the sort, but city dwellers love the idea because it's zero emission as far a the driver is concerned an the rest of the planet can whistle.
The selfish ape indeed.
There are efficiency advantages in running the motors in series.
Internal combustion engines have a relatively narrow RPM range that provides maximum power at peak efficiency. Operating the engine outside of this rev range through direct drive to the wheels reduces engine efficiency considerably. If you could design and build some sort of an "infinite" gearbox that allows the motor to run at a constant speed then that would alleviate this problem.
Unfortunately we cant build such a gearbox that is both cheap and reliable, if at all.
Fortunately however, if you use electric motors, you can design a generator + motor combination that runs at the RPM for which it is at its peak efficiency and use it to charge a battery for the electric motor, which doesn't have an efficiency problem at different speeds.
HTH
Double the battery, give it a solar roof for a 'free' 'top-up' and I'll take one.
I've never objected to the Swift as a design and the girlfriend quite likes it as well. It would get me to work and back each day comfortably plus I am sure I could convince the building manager at work would agree to lease me a charge point.
I'm no hippy but I like the idea of having something ecological and economical.
Bob
"Shirley it would be a lot more energy efficient to use the petrol engine to drive the wheels directly through a gearbox? Now there's a revolutionay way to save energy."
That's 'Surely', not 'Shirley'.
And no, it would absolutely NOT be more efficient to drive the wheels directly.
It would be MASSIVELY less efficient to do that.
This way the engine can run at a constant RPM, and any 'leccy generated that isn't used by the motor is fed into the battery. This is the way that Diesel Trains have been working for years.
Firstly develop a sense of humour (or failing that a knowledge of popular culture) before you get on your high horse. The joke goes: "Yes, I am serious and don't call me Shirley."
And you can achieve the same constant rpm using a mechanical variable drive, usually known as CVT. You will find that these are less fuel efficient than a manual transmission, because more energy is lost in the transmission.
Driving a generator will in itself take a certain amount of energy, you are converting energy from one form to another and that always involves losses. You are then converting it back again which will involve more losses. There is also the fact that lugging around the weight of a generator and electric motors is going to make the whole car heavier than a conventional setup which will also reduce the efficiency.
Diesel electric locos and indeed earth moving kit do not use this arrangement for any reasons of efficiency. They use it because a conventional transmission could not cope with the loads, at least not without being huge and prohibitively complex. There are diesel hydraulic locos out there, but these tend to be more expensive to make and maintain than diesel electrics although they do have other advantages. There are also some diesel railcars which use more conventional transmissions, but these are generally capable of only hauling light loads.
My original point was that there is a headlong rush towards EVs without any real thought and so many of the ideas in use really need to be investigated more fully. The best bet would be to stop all development and have some thinking time. Unfortunately the nature of business means that this is unlikely to happen and a lot of blind alleys will be needlessly explored. Which is hardly an efficient way of doing things.
"Firstly develop a sense of humour (or failing that a knowledge of popular culture) before you get on your high horse. The joke goes: "Yes, I am serious and don't call me Shirley." "
OK fine you were making a joke, but there's nothing wrong with my sense of humour., and yes I have seen the Steve Martin sketches, however your use of the joke was pretty bad to be fair, as the joke is in Frank Drebin's misunderstanding of "surely / Shirley" not in the actual saying of it.
I'm sorry if you took offence at my comment - but I get so used to people using terrible English on here, you can understand my reaction. Also, I didn't resort to insults as you did. Perhaps you should grow a thicker skin, or learn to tell jokes better - for example by finishing them.
ANYWAY
"And you can achieve the same constant rpm using a mechanical variable drive, usually known as CVT."
You are correct in theory, but CVTs are piss poor for higher power applications - i.e. in any thing much heavier than a Ford Fiesta, or anything that you want to get from 0-60 in less than a week. This is because they can't handle the torque - generally speaking. Newer CVTs are coming out, but they still won't be as efficient as a serial hybrid, and they are horrendously expensive.
Also, an engine with CVT may be running at 1 or 2 set RPMs, but the load will vary. Engne->Generator is constant load, constant rpm and it only needs to run when the battery is low, or in some implementations, when an extra burst of power is required.
"Driving a generator will in itself take a certain amount of energy, you are converting energy from one form to another and that always involves losses. You are then converting it back again which will involve more losses."
Yes there are losses (tiny ones) in running a generator, but in the hybrid you are envisioning, you are running a generator AND running a transmission. Transmissions, even CVTs and IVTs are not nearly as efficient as a serial setup.
"There is also the fact that lugging around the weight of a generator and electric motors is going to make the whole car heavier than a conventional setup which will also reduce the efficiency."
Eh? You still need motors, batteries and a generator in a parallel hybrid.
A parallel also needs a far more powerful engine as it has to physically move the car, whereas the serial only need to generate electricity at a constant rate - and (excluding generation loss) NONE of the energy it generates is wasted. With serial hybrids you can also use in-wheel motors, which can also act as generators, so you don't need separate regenerative braking systems. So in fact, a serial hybrid is much lighter than a parallel
"My original point was that there is a headlong rush towards EVs without any real thought and so many of the ideas in use really need to be investigated more fully. The best bet would be to stop all development and have some thinking time. Unfortunately the nature of business means that this is unlikely to happen and a lot of blind alleys will be needlessly explored. Which is hardly an efficient way of doing things."
An interesting point, however that is what vehicle designers are paid to do. And development has been going on for years. The industry has already pretty much split into 3 camps: Electric only, Parallel Hybrid, and Serial Hybrid.
Personally I thing Serial hybrids are the way forward because they are so simple. Electric Only is currently no good unless you're buying it as a second car due to low range and long recharge times, and Parallel hybrids are overly complicated.