Two-Mode Hybrid

i thought it was GM who said that HSD would fail because it had so many extra components... :lol: hypocrites.

 

I was under the impression that the 2-mode design was supposed to solve an inherent energy loss of HSD caused by the ~ 2/3rds ICE transduction though M/G rather than straight to the wheels.

Makes me think the diagram should show the wheels connected to the second PSD.

But yeah, that is one complicated design. How many feet does a driver need ?

 

My first guess is that it's a way to bypass key patents held by Toyota. I can't belive anyone would prefer to build a car with three clutches, two gearboxes and a partridge in a pear tree.

 

The stated point is to increase efficiency on motorway cruise. It eliminates one of the efficiency weaknesses of the HSD - during cruise a significant amount of the power output by the engine has to be tapped off by MG2 and fed back into MG1 to balance the torque forces in the system, with the inherent electrical conversion losses.

With the two-mode system, it can switch to a more efficient parallel-type system during cruise, so the engine can drive the wheels directly.

Now, how much this actually helps in quantifiable terms, I don't know. And is it worth the extra mechanical complexity? It's still less complex than a traditional automatic transmission, and the clutches will be under computer control, so won't suffer the sort of wear seen in a standard manual car. Quite similar to the clutches in the Volkswagen DSG system, in that respect.

 

There is a report that the two-mode prototype delivered worse fuel economy in highway driving than the conventional diesel.

http://www.greencarcongress.com/2004/12/gm_daimlerchrys.html

Ken@Japan

 

The article doesn't say that - it says that their previous non-two-mode (so HSD-like?) prototype delivered worse highway economy than the conventional diesel, justifying the creation of the two-mode system.

 

It's also worth pointing out that the two-mode system takes up the same packaging space as a regular transmission, so GM, Mercedes etc should be able to retrofit most of their models with the two mode system without such a major redesign. So it's not that huge and complex!

There is a picture here (see second one down) of the two mode transmission installed in a diesel Astra. Looks pretty production ready to me, wonder when they'll be putting it on sale?

I like the 0-60 in less than 8 seconds bit!

 

One of the problems for GM and the boys is their target. It makes things a whole lot more difficult when you put the hybrid in a pickup. Now, the system has to work well under no load...

And, when you have a horse trailer with 22000 pounds hooked up, going up a mountain (or down)...

I know they have a car design too... It's just hard to trim down the ICE to be super efficient when it has to be the right size to get good fuel economy when unloaded on the freeway, but also be enough power to pull a load up a mountain.

Good luck with figuring that all out.

 

They wrote...

We'll see how good the Two-Mode system is in a few years.

Ken@Japan

 

A major concern for at least BMW and Mercedes, is that people in Europe expect the (passanger) cars to be able to do 1 - 60 mph (0 - 100 km/h) in less than 6 secs and at the same time achieve 250 km/h on the AutoBahn for hours.

Perhaps the Two-Mode system is addressing these challenges in a better way than the current HSD system is?

 

Is that eligible in the CARB states?
As you know, California is the most demand state for hybrid vehicle.

Ken@Japan

 

i would think this would be more correct.
[Broken External Image]:http://img12.imageshack.us/img12/2702/gm5gp.th.gif
and after looking at the green car progress link, it looks almost the same. they chose to add a few things together to make it a straighter line though.

you'll have to forgive me for the quick edit of the pic, i didn't have much time at the moment.

 

Population of California: 36 million. Population of EU: 450 million.

The market is there, especially at realistic fuel prices ($5-6 per gallon) in Europe, so I think these vehicles would come to production regardless of CARB requirements.

Having said that, Mercedes' Bluetec diesel system appears to meet US emission rules for all 50 states, including California. Fairly sure given recent hybrid co-operation GM could license it from them.

 

I am fairly certain that we will see several interesting - even promising - hybrid versions from different vendors over the next few years. The Two-Mode Hybrid is clearly one of those.

Even so, I am personally sceptical to the quality/reliability of these new systems initially. Remember, both Toyota and Honda have had years already to sort out any problems, bugs etc., so in any case I will not buy any american/european hybrid before 2010 at the earliest.

 

I'm saying the hybrid awareness market.

(note: data below is until Oct 2005.)
Toyota sold about 212,000 Prius in the US.
In the five CARB states, Toyota sold about 39% or 83,000 Prius.
I have no data for the EU market, but Toyota sold only about 37,000 Prius except Japan and US.
So, the CARB states are the huge market for hybrid vehicles and none is related to the population.

Again, is the Opel Astra Diesel Hybrid eligible in the CARB states?

Ken@Japan

 

I wouldn't rag on GM for this seemingly less than optimum design. Their bread and butter are large cars and trucks/SUVs, and the HSD setup might not scale up well. Our RPM limits and torque division may not work well for a multi-ton truck pulling a trailer.

As applied to the Prius, it was not just a new drivetrain, but a new car. GM is looking to leverage their substantial investment in the current design of their front engine/rear drive vehicles. A design that is a "form/fit/function replacement" for the current transmission has a lot of appeal economically.

The timing of this development, just as GM rolls out what was to be a savior of a truck line, means they can retrofit the "new trucks" without a complete redesign. It may not be the most optimum engineering approach (especially on terms of wearout items like clutches), but it fits their product lines and does not require ditching their recent investment in the new trucks.

They will of course tout this system as better, which is probably not true for smaller cars like the Prius. But it may well succeed in the market for truck/SUV buyers who favor traditional designs and marketing.