[Don Collett]

Any chance that a Stirling cycle engine can be an option instead of a regular gasoline motor as the generator? DEKA has on their website that they are researching one (http://www.dekaresearch.com/coreTech.html). Maybe one of the engineers can look into it.

http://www.dekaresearch.com/popUps/stirling.html​

 

[Jason M. Hendler]

I love Stirling engines, but they tend to be too heavy for mobile applications. Right now, their most significant role is in concentrated thermal solar applications:

http://www.infiniacorp.com/technology/how_stirling_works.php

http://www.stirlingenergy.com/

I believe both of these companies have been snatched up by another company (that's why websites are down) intending to incorporate these designs into a more comprehensive renewable energy system that involves both electricity and hydrogen generation.

 

[Cybereye]

Gm is a car company. They make thier own engine. Why buy someone engine?

 

[Jason M. Hendler]

Gm is a car company. They make thier own engine. Why buy someone engine?

GM specialized in gasoline, alcohol and diesel piston internal combustion engines. There are other engine / motor types about which GM is NOT expert, so they would need to source, license or acquire:

- compressed air engines, piston and rotary
- stirling
- turbine
- electric motor of any type

 

[Cybereye]

your right, but GM have much better understand and better control over there own engine. I'm sure it also keep the price low. I would not says GM is great on motor. When better technology battery come along, I'm wondering if GM sell it engine sector to another company.

 

[Rooster]

Gm is a car company. They make thier own engine. Why buy someone engine?

Answer: it's cheaper and faster than developing your own inhouse design. Besides, GM is becoming more and more like a prime contractor like Lockheed and Boeing. They own the design and do the final assembly, but they subcontract the construction of the piece parts.

 

[nlh_90210]

take a look at the fuel sorce

http://www.precer.se/Files/Precer%20Data%20Sheet%20C.pdf.
I found this off of the Wikipedia site for Sterling engine. The biggest problem that I see with a Stirling engine is the low power to weight ratio, and the fact that you have warm up/cool down requirements. As mentioned in the Wiki page, some of this becomes less of an issue in a hybrid type application.

As for the previous line of post. The biggest problem I see right now stems from GM using their own engines. This is because they are unwilling to make changes because they "cost" too much. So we are stuck with 110 years of the damn piston engine. At least the RX7 and RX8 took a chance on the Wankel and I think the Prius uses an Atkinson cycle engine (both rotary and both with a high power to weight ratio).

 

[Jason M. Hendler]

nlh,

Thanks for mentioning the Atkinson cycle engine, Wiki's got a great animation to show how that works:

http://en.wikipedia.org/wiki/Atkinson_cycle

Honda has incorporated a Rankine cycle engine, instead of a Sterling engine, to convert the heat of exhaust gas into electricity:

http://www.motorhomemagazine.com/output.cfm?ID=1492219

Wiki's diagrams of Rankine cycle:

http://en.wikipedia.org/wiki/Rankine_cycle

 

[Cybereye]

great info Jason M. Hendler and nlh_90210.

I agree more on Rooster statement, then my own point of view. GM may be going to that path in the long run. I didn't think of that way.

 

[G35X]

 

[Don Collett]

Well...

It would seem that the warm up/cool down requirements and power ratios would not be an issue since its only the generator on the Volt. But yeah, additional weight is a problem. Perhaps DEKA (http://www.dekaresearch.com/) will find a way around that in their research which last I heard was still in progress. They were rather creative with the development of the Segway Human Transporter.

It does sound like there's other options to extend the mileage of the Volt even further by different choices for the gasoline assist. That's encouraging.

 

[nlh_90210]

fair enough

G35X, Is this correct?

A Wankel engine is a rotary Otto cycle. It's more or less as efficient as a piston Otto cycle and has a higher power to weight ratio. I guess the Prius uses a piston Atkinson cycle, which has a lower power to weight ratio but is more efficient than a standard piston Otto cycle. In theory you could have a rotary Atkinson cycle engine, which would have a higher power to weight ratio than a piston Atkinson cycle engine.