Archives

I have watched every mfgr of hybrids take a slightly different approach to engine design.

The only constant I can see is they all use higher compression ratios and most are pushing the Atkinson scenario. The smart ones are Atkinsons with variable valve timing and some of those mfgrs are also sliding towards Atkinsons in non hybrids.

Toyota has taken a path more biased to valve phasing while Honda has been more focused on changing the size of the valve events. My comments are confined to the 4 cylinders mostly because I don't see the V block hybrids as being major players in the hybrid market as fuel prices rise. I believe that variable valve timing will facilitate better control of combustion which will enable larger displacement 4 cylinder engines which I see as the wave of the future.

So here is how I think we could reduce the engine cost. The Heron combustion chamber is very efficient and indisputeably the cheapest possible means to build a cylinder head especially in a cast iron configuration. Two spark plug variants are only slightly more expensive and allow even more thermal efficiency.

The only thing to be said bad about the Heron set up is it doesn't lend itself to good high speed volumetric efficiency(VE). This could easily be rectified with variable valve events within speed ranges applicable to 95% of all vehicles utilized for personal non racing transportation. The superior aspect of the valve train layout is it lends itself to the cheapest possible form of variable valve event technology. Most engines utilizing variable valve events only utilize variable intake events. Unfortunately high speed VE requires variable exhaust events and variable intake events. The valve layout in a Heron Chamber is such that all valves are parallel and in a single row. This means simple rocker arms providing variable size valve events no more costly than conventional rocker arms can be utilzed with one common control mechanism to alter the intake and exhaust valves as compared to the complex VTEC type mechanisms which are usually only used on intake valves due to excessive cost.
Patent 4,723,515 is also semi demodromic which gives it high speed capability without requiring heavy duty valve springs. Further refinements in this patent reduce cost by using a rotateable rocker shaft which facilitates the motion required to change valve events by rotating the rocker shaft which has mounting journals that are non concentric with the rocker shaft pivots.

Which brings us to the advantages of cast iron over aluminum in an engine focused on fuel efficiency. The thermal efficiency is attributeable to less heat loss. Weight? Have you ever lifted a fully assembled 4 valve per cylinder head with variable events and variable phasing? The Heron head is much more compact which diminishes the potential weight savings of utilizing Aluminum.

You might not agree with every thing I have said but I think most people would agree that there is some overkill in hybrid engine cost that could be eliminated to make the hybrids more affordable.

Hi Cob:

___Nice post … Could you please explain what the patent(s) are in your posts as I do not want to look them up and try and deduce what is being patented with a Patent Attorney’s write up trying to cover every base under the sun.

___I want to make a few comments. Most hybrid’s (Prius I/II, HCH-I/II, and Escape HEV) use what I would call an inexpensive ICE to begin with. The last time I read, Ford’s 4-valve per head - 2.3L ICE used in the Ranger, Focus, and Escape cost just $1,200 complete as outsourced out of Mazda’s Hiroshima plant a few years ago. I have no idea what the complete 2.3 ICE assembly’s coming out of the Dearborn Assembly cost but I doubt it’s that much higher if at all. The Escape HEV’s Atkinson intake is more of an intake valve timing tweak rather then a complete redesign of the heads and intake plenum IIRC. This is the whole ICE package including the head, block, crank, rods, pistons, controllers, injectors, and everything else ready to bolt to the tranny. A cast iron head vs. the aluminum one is a few $’s less but this is not the expensive part of today’s hybrid’s/non-hybrid’s given a $1,200 price tag for the whole ICE package vs. the same or higher for an outsourced pack from Panasonic or Sanyo. The pack, multiplexed controllers, multi-frequency capable MGSet’s, and inverter/up-converter are where the real expenses lye I would have to assume?

___Good Luck

___Wayne

Wayne

Thanks for the constructive response

Its hard to respond to your request for patent info because lawyers converse in a language that is foreign to most of us. However it is so easy to read patents on line. You just put USPTO into a search and follow prompts. Its a great way to learn whats coming down the road because you can read all the pending applications.

I find it so frustrating to make objective post because there is so much reference information out there that is not objectively based. Another one of my fantasies is SAE standards in journalism. Wouldn't that make the world a little easier to understand?

I don't know where you guys get most of your information but I use Automotive News for most of my references.

Regarding your cost figures- There were numerous articles written that the cost of a multivalve engine is typically 800 dollars more than a 2 valve per cylinder engine. My post is simply to encourage people to question the value of having more than 2 valves per cylinder in a hybrid. There is a lot of money to be saved by reducing the parts in a cylinder head by 50%. I could say it differently by asking what is the advantage of having more than 2 valves per cylinder in an engine with variable valve events. Been asking that question for 20 years and then Honda comes up with a 2 valve per cylinder hybrid so maybe there is some validity to my position on that matter.

Cob