[sudev]

@DKG : Trust you to throw in a cruve ball. As it is my mind (and time) is over flowing just reading the discussion. (and also some qucik peeks at links) and now you bring this up.

Okay so sleeve valve. What the hell is that? ....me wandering off to google and wikipedia!!

[DKG]

Another interesting option is the Wankel engine used by Mazda for their RX7. No valves at all !!

[vina]

Originally Posted by DKG

Since many are having fun discussing valves, instead of solenoids I feel a sleeve valve technology worked by an electric motor is a more interesting option. In the 20's Daimler used a mechanically actuated sleeve valve design for their engines. That could, I'm sure, be improvised with new materials and electrics doing away with cams and solenoid/mechanical valves completely.

@DKG

isn't it similar to the sliding valve in steam engines I mentioned ?

Here's the wikipedia article on sleeve valves: Sleeve valve - Wikipedia, the free encyclopedia

Very interesting idea. By the way - wouldn't the sleeve be heavier than the poppet valves (in today's technology)?

Originally Posted by DKG

Another interesting option is the Wankel engine used by Mazda for their RX7. No valves at all !!

I thought Wankels were not really in use - your post made me look closer.

Mazda actually has a new version of the Wankel in RX8 !

[DKG]

Originally Posted by vina

wouldn't the sleeve be heavier than the poppet valves (in today's technology)?

Do check out the rotary Wankel too. Two elements about that engine are interesting, one is there is no reciprocating piston that needs to translate into rotary action, the piston rotates itself and also there are no valves (atleast in as much as I understood the design). I've driven the RX7's and they were fun to drive. The engines were very responsive. There used to be sealing issues when the Wankel engine was first conceived but Mazda seems to have effectively solved that problem.

I am not an engineer so I wouldn't know much about weight issues but somehow the sleeve valve also seems like a more efficient valve as opposed to a reciprocating poppet valve. There would be more inertia needing to be overcome in a reciprocating valve, wouldn't it, as opposed to a sleeve rotating? What are your views

[sudev]

Hmmm wankle engines are getting new life? This thread is certified time waster!!!

Going OT and adding fuel to fire. OR turbine engines.

Many changes in materials technology and turbine design technology have taken place. Adoption of turbo in more and more vehicle attests that.

So engineers in here what says?

@tsk1979 : Perhaps topic heading needs a change if this goes OT too much??

[DKG]

Micro turbine engines is also a very neat idea for electricity generation. I would seriously look at that in a hybrid. You could have the turbine run on LPG ! and you can make this at home on a lathe

Basically we are talking about doing away with valves completely

[headers]

Originally Posted by DKG

Another interesting option is the Wankel engine used by Mazda for their RX7. No valves at all !!

Somehow Rotary engines never really clicked thanks to their efficiences

Originally Posted by DKG

Micro turbine engines is also a very neat idea for electricity generation. I would seriously look at that in a hybrid. You could have the turbine run on LPG ! and you can make this at home on a lathe

Basically we are talking about doing away with valves completely

, come on sir, we cant kill an entire industry

[SS-Traveller]

Originally Posted by vina

Anyway, guys here's something to look at:
http://http/autospeed.com.au/cms/tit...0/article.html
By the way, I estimated 1% loss due to valvetrain this one says 5 to 10%

@vina: Thanks for those links - very interesting read.

...cars would have to make a long-awaited move to 42-volt electrical systems (from the current 12 volts) before electronic valve control would be practical.
from WHAT'S NEXT; A Chip-Based Challenge to a Car's Spinning Camshaft - Page 2 - New York Times

Why 42V? Why not 48V (or even 110V)? And what about the weight and size of batteries to run 42V systems? Feasible in a small/medium sedan-sized car?

The following information of course opens up an entirely new range of possibilities in driving - 5 forward & 5 reverse gears, including overdrive in reverse!

Using camless valve actuators permits reprogramming to allow the engine to operate in reverse . This can be done by simply inverting one input wire pair. Reverse operation is advantageous in marine equipment having dual outdrives or T-drives. This feature would also eliminate the need for reverse gear in the transmission since forward gears would be used to operate in either vehicle direction. This provides an opportunity for multiple reverse gears without the added hardware.

@Sudev: Wouldn't you propose the Delhi-Jaipur "Reverse Rally" for camless cars?

[RS_DEL]

Originally Posted by DKG

Micro turbine engines is also a very neat idea for electricity generation. I would seriously look at that in a hybrid. You could have the turbine run on LPG ! and you can make this at home on a lathe

Basically we are talking about doing away with valves completely

This has already been implemented by Jaguar in one of their cars. The link to the post is here


http://www.team-bhp.com/forum/intern...ice-where.html

[tsk1979]

No need to go OT about gas turbine engines. There is a separate thread for that. Tata has bought a company in this regard
Here, you can go there
http://www.team-bhp.com/forum/indian...t-engines.html

[vina]

Originally Posted by tsk1979

No need to go OT about gas turbine engines. There is a separate thread for that. Tata has bought a company in this regard
Here, you can go there
http://www.team-bhp.com/forum/indian...t-engines.html

Actually the power efficiencies of rotary engines are poor (but theoretically can be improved - that's what I read several years ago in some technical-journalism papers on energy policy) and those of turbine engines are horrible (on account of how much heat they waste into exhaust, though in recent years they have improved with turbofans)

Both have better power/weight ratio, with the turbines having the best - for aircraft that is one key metric more important that efficiency.


The world's fastest speed in a car was achieved using a turbojet engine (the car was an aircraft with wheels generating downward thrust instead of lift - didn't survive its maiden journey)

There was a motorbike with a small Rolls Royce turbojet (Jay Leno had one - I saw it on NatGeo extreme machines - don't remember the brand though) but again not cheap, not efficient.

[vina]

Originally Posted by DKG

Micro turbine engines is also a very neat idea for electricity generation. I would seriously look at that in a hybrid. You could have the turbine run on LPG ! and you can make this at home on a lathe

Basically we are talking about doing away with valves completely

Is there any specific reason why you wouldn't want valves? Turbines and Wankel have their own complications and well known efficiency problems as well as material science challenges (in combustion chambers of turbojets, the blades used are under so much much stress that each blade has to be a single flawless crystal)

[Sutripta]

Originally Posted by vina

This can perhaps work - remote controlling the valves hydraulically. The question is what is the complexity of hydraulic actuated valves?

Also isn't this kind of system (somewhat) already in use in F1?
Pneumatic springs.
...
Anyway, guys here's something to look at:

http:/autospeed.com.au/cms/title_Camless-Engines/A_0910/article.html

By the way, I estimated 1% loss due to valvetrain this one says 5 to 10%:
Seriously doubt this figure.
D

Originally Posted by vina

Even hydraulic can magnify force. Also if all you want to do is change the valve timings then electro-mechanical systems working on the timing belt can achieve that very very cheaply - no solenoids needed.
And also nowhere near as versatile. Just timing - VVT. Lift - Valvetronic/ Multiair. Together + more?


Direct mechanical linkage will be almost as complex as camshaft and VVT implementations.
??

In my childhood I was fascinated by railway's steam locomotives - those used sliding valves. So do some of the rotary engines.
Steam engines:- working models. Every boys wet dream.

sinbad's engine is a MAN engine, rated 18.5MW@91rpm (that is right)
The engine is the size of a whole apartment building.
Pretty standard as far as rpm and size go for main engines. These have ladders inside the crankcase for people to climb into!

Originally Posted by DKG

Do check out the rotary Wankel too.
The Wankel discussed to death before it died. Essentially bad combustion chamber shape, huge surface area, too many quench areas.
NSU went bankrupt because of the Wankel (Seal problems).
There used to be an AC compressor - Ogura Wankel. Get a scrap one, take of the front plate and replace with a acrylic sheet, and turn it by hand. Fascinating.
And I did say

There would be more inertia needing to be overcome in a reciprocating valve, wouldn't it, as opposed to a sleeve rotating? What are your views
Sleeve valves have had their proponents, notably Ricardo (of the BMC heartshaped combustion chamber shape which you saw in Ambassadors)

Originally Posted by SS-Traveller

Why 42V? Why not 48V (or even 110V)?
Check out the date of the links.
Our 12 V system is actually a 14.4 V system. Round off and call it 14 V. Triple it and call it 42 V.
As electrical loads started increasing in cars, wiring started becoming a problem. The higher voltage system was supposed to answer that.

The following information of course opens up an entirely new range of possibilities in driving - 5 forward & 5 reverse gears, including overdrive in reverse!
Reversing the engine. Thats why I asked Sinbad

Regards
Sutripta

[DKG]

Originally Posted by vina

Is there any specific reason why you wouldn't want valves?

No just wondering aloud on whether one can do without all that drivetrain for the valves. Cutting out all the extra weight and moving parts bit.

Check out this new tech called wave disk engine

[vina]

Originally Posted by Sutripta

[/b]

Originally Posted by vina
This can perhaps work - remote controlling the valves hydraulically. The question is what is the complexity of hydraulic actuated valves?

Also isn't this kind of system (somewhat) already in use in F1?
Pneumatic springs.
...
Anyway, guys here's something to look at:

http:/autospeed.com.au/cms/title_Camless-Engines/A_0910/article.html

By the way, I estimated 1% loss due to valvetrain this one says 5 to 10%:
Seriously doubt this figure.
D

Regards
Sutripta

So do I, so did a little more research (it is very hard to find numbers) - Engine friction lubricant sensitivities: A comparison of modern diesel and gasoline engines - Taylor - 2006 - Tribotest - Wiley Online Library is the abstract of a book. Tell you that Merc engine at 2500 rpm expends 1.5kW in mechanical losses using the lubricant in question, with roughly 300W of that being valvetrain losses. The engine is question generates roughly 100kW (depending on varients).

So I think it is reasonable to assume valvetrain losses at 0.3% in this engine at 2500rpm. Also losses (as a fraction of engine power) will increase when engine capacity is smaller and power obtained is smaller - in a non-merc engine running at higher rpm I wouldn't be surprised to see 0.5% kind of losses.

Anyway, the number I used earlier (http://www.team-bhp.com/forum/techni...ml#post2330869) were quite a bit right in the ballpark.