Hi, check out these two links describing Honda's next generation IMA system, for installation in the new Civic-hybrid this Autumn.

http://world.honda.com/news/2005/4050705_b.html

Video describing how engine and IMA work together


It looks like the major advance is a third VTEC mode, where all the valves are shut to reduce pumping losses. This allows two things:

1) Reduced engine braking so more energy can be recovered from regenerative braking.

2) A low speed EV mode, where the electric-motor alone powers the car.

I wondered how they were going to get this mode without stepping on Toyota's patents - fairly inventive I think if a little circuitous!

http://mysite.wanadoo-members.co.uk/ecotech/ecot.htm

Interesting. So the electric motor spins *both* the wheels & the engine, to create an EV-only mode. Also, I see they've boosted output from 13 to 20 horsepower. That's a lot simpler than adding a second engine-motor clutch.




I don't see how this New Civic is going to be *more* efficient, when they increased the engine size from 1.3 to 1.8 liters??? Seems like it should be less efficient.

troy

I don't think it gets a 1.8 liter engine - it just has the equivalent power of one. It says it's still a 1.3 in the specification. Confusing the way they put it though.

The 1.8-liter engine is the new replacement for the 1.7-liter ones in the current regular Civics and the hybrid engine is supposed to be as powerful as a normal 1.8-liter engine.

http://money.cnn.com/2005/07/05/Auto...reut/index.htm

It's nice to see the article also talk about Honda's "green" achievements.

I did not completely read the article, but the most obvious upgrade for the HCH's engine is shutting off half the cylinders at cruising, just like the hybrid Accord. I'll be suprized if they don't do it.

61.5mpg lifetime - 82mpg in recent months

Best Run >
www.cleanmpg.com

"fanatic" is what the lazy call the dedicated

In 3-cylinder highway mode, multiplied by the 0.7 5th gear ratio, the Accord generates ~28hp @2000rpm. Plenty of power.

But that wouldn't work for the Civic. 2 cylinders is only ~10hp @2000rpm - not enough power to overcome the ~60mph wind resistance.

troy

I'd be suprized if Honda did not put a 2/4 cylinder engine in the hybrid Civic. Honda suggested such an engine in the IMAS concept car (sometimes dubbed the Insight II). This just does not seem that difficult to do.

The engineers would know how much horsepower is required for a Civic to cruise at 60 miles per hour. It would seem they would make the engine a little larger - say 2.0 liter if that's what it took to cruise on two cylinders. How could Honda resist offering a Civic that has more power and better FE?

61.5mpg lifetime - 82mpg in recent months

Best Run >
www.cleanmpg.com

"fanatic" is what the lazy call the dedicated

The minimum needed for 60mph cruising is about 20hp @ 2000rpm.


So given a 2-cylinder mode, you'd need a (20hp * 0.7 5th gear ratio / 2 cylinder mode * 6000 redline/2000rpm-cruise * 4cylinders) = 160hp/4-cylinder engine minimum. Probably 2.0 liter like you suggested. The problem with using a larger 2.0 liter instead of 1.3, is you have more mass, and therefore more energy losses from pistons constantly changing direction. Also a slightly-heavier car.

You'd be lucky to get 40mpg.




It is actually *more* efficient to just build a standard 4-cylinder 80hp engine, that has less mass, and therefore conserves energy... with estimated mpg=50.

troy

I looked up the power requirements for the 2G Prius according to Wayne Brown:

15.65 kW at 70 miles per hour
11.87 kW at 60 miles per hour

Two cycle deactivation in the '06 HCH that has ~ 18 kW/cylinder, would appear to allow two cylinders to operate in their efficient range presuming similar power requirements. Seems likes an improvement in engine efficiency, and hopefully MPG as well.

The power curve seems to be cut up really well now, what with EV, and assist for two or four cylinders. Less clear to me (my limitations, mostly), is ICE/motor system integration limitations, and transduction losses.

Hopefully a Graham Davies type person will step forward to analyze the HCH in the same way Graham has for the Prius. And of course, a bit of on road experience will be the bottom line. Interesting times! and kudos to Honda.

Addendum: Honda has a beautiful animation up. As far as I can tell, cylinder deactivation does not occur. Instead, a mechanical switch invokes valves with different timing -- Atkinson timing, perhaps ??

R2-E2, 2G Prius.
Highway/City/Husband/Wife MPG: 56.5, as of 12/2005, 26K miles

Jac Nasser, Ford President: "We are planning to launch a hybrid version of
this car [P2000] within this year [1998]. We will also make FCEV available in
2004."

hmm.. Car seems to be rated ULEV.

It's not like Honda to spin facts.

R2-E2, 2G Prius.
Highway/City/Husband/Wife MPG: 56.5, as of 12/2005, 26K miles

Jac Nasser, Ford President: "We are planning to launch a hybrid version of
this car [P2000] within this year [1998]. We will also make FCEV available in
2004."