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Old 28th April 2011, 21:03   #46
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Default Re: Camless and electronic timing : The future?

Quote:
Originally Posted by Sutripta View Post
@Vina,
Again too much to discuss. So let me narrow it down to points where I have significant differences with your views.

I don't think processing power is a problem. Once the decision to operate (open/ close/ hold) a valve is taken, its actions will be determined by the mechanical (in the larger sense of the term) parameters. It will not be very much more computationally intensive than say multi injection in a modern diesel. And there are a vast number of tricks available to lessen even that computational load. (Crude eg. Think of Sine wave generation techniques in inverters before DSPs took over.)

The maximum source of unreliability is where the form of 'energy' changes:- actuators and transducers. (Power electronics falls in the category of actuator, in my view). After that will come the more common ones like power supplies, interconnections, mechanical switches etc. Chip level failure will be way down the list.

One thing you have not mentioned is handling all the electrical noise (EMI/ RFI/ Power line) which will be generated by the operation of so many highpower solenoids. This will play more havoc than alpha particle radiation.

One very minor point. Are Ne magnets temp stable?

Anyway, great posts. Keep them coming. A pleasure reading them. And a pleasure interacting.

Regards
Sutripta
Hi Sutripta

you are right mostly, computation is not a major issue - although some computation will still remain (though bandwidth of that will be far lower than the rpm).

My calculation was for the driver of the solenoids (if that is electronics), I didn't even consider DSP/uP anywhere in my post. The driver will need to be close to the solenoid due to EMI.

It is unlikely you'll find ay mechanical switches (or relays) that'll have timing precision of the order required here - and if you are going to do that anyway then what is wrong with the cam?


I'm not saying it can't be done - I'm saying it is probably not going to gain you anything to do so.
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Old 28th April 2011, 21:09   #47
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Default Re: Camless and electronic timing : The future?

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Originally Posted by SS-Traveller View Post
One thought: what is the temperature of the exhaust gas at the exhaust valve (and valve stem)? My guess would be, not less than 1000-1200*C even after the engine oil cools it down, but please correct me if I am wrong. What kind of electronics (i.e. the materials that make up the solenoid, chip etc.) is expected to tolerate that sort of temperature (although, @vina, you did talk about temperatures of 200*C)? And what would be the cost implications of such materials?

Also, the higher the rpm of an IC engine, the greater would be the exhaust gas temp anyway, so that might nullify the possibility of a camless engine managing to rev higher (as Tanveer suggested).

Saw that reference too! It's still the same, and is an appropriate one for some of our interesting discussions on this thread and elsewhere, isn't it?
I don't think it is 1000C, I think it is far less than that (though it'll be higher than 200C I'm sure - exhaust valves are known to develop problems). The flame temperature of petrol fumes will be a few hundred degree higher than this, but I don't think even at TDC the gases would be achieving this temperature.

also I talked about 200C because tsk1979 made a claim that chips can do 200C in a heartbeat - they can not and that's the point I made.
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Old 28th April 2011, 21:46   #48
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Default Re: Camless and electronic timing : The future?

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Originally Posted by vina View Post
The driver will need to be close to the solenoid due to EMI.
That's engineering detail design. Remember seeing a high power vector drive in which a optical fibre link was used.

It is unlikely you'll find ay mechanical switches (or relays) that'll have timing precision of the order required here - and if you are going to do that anyway then what is wrong with the cam?
I think you have misunderstood what I meant by 'mechanical'.
A solenoid cannot operate directly on a poppet valve, it has to be through some mechanical linkage. Once the solenoid is energised, it will generate a force. Which will act on a mass. Newtonian mechanics takes over.
Absolutely did not mean mechanical relays etc.

Quote:
Originally Posted by DerAlte View Post
Even the alternator throws out a significant amount of power in RF range - enough to possibly cause EMI disturbance. The engine bay is 5 sides shielded, so you cause minimal disturbance outside the car. The car electronics is 6 sides shielded, so it is not affected. Old tech - good electrical practices like grounding.
Well, I'd consider it rather difficult, esp the power line noise. But then, I'm not the professional!

Quote:
Originally Posted by anujmishra View Post
Here you can see "Hybrid" mushroom cloud.
I guess for shock publicity, exploding Hydrogen is close enough to a thermonuclear (Hydrogen bomb) explosion!

Regards
Sutripta
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Old 28th April 2011, 21:52   #49
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Default Re: Camless and electronic timing : The future?

It is indeed a good discussion. I hope somebody can let us know about the losses in driving the valvetrain so my estimates can be validated and corrected.

See my comments below:


Quote:
Originally Posted by DerAlte View Post
Fantastic topic and discussion.
...


DC? Double the size? Why 'hold the magnetization'?

This is if you don't want to use permanent magnets. My assumption is that both the coils (the stationary and the moving) will need same amount of current - hence double the size (two coils vs. one)

By the way DC is the best option for stationary - you don't run into inductance problems with that, and if it is not switching then those losses are minimised.


CMOS is the most suitable material technology at high temp - getting it work reliably would be a matter of material science, not empirical thought. We are not talking of current tech state, are we?

I was talking about laws of Physics, this has nothing to do with technology. At higher temperatures more thermal EHP generation results in more electrons in the conduction band and more holes in the valence band. Also EHPs generated in the depletion region of a diode will move in opposite directions based on the applied electric field - The reverse biased diodes will leak very heavily.

Now CMOS depends on reverse biased diodes for isolation. In any CMOS chip there are more diodes than there are transistors. Once all the diode start leaking, your transistors will not work.

Also MOSFETs themselves leak heavily at higher temperatures. If you have worked in the lab with any of the chips, you'll see that at 125C in some chips leakage is as much as the dynamic current. At even higher temperatures this will stop any digital circuit from working.



Anyhow, the chips that you are talking about work in a well-protected environment - perhaps you are completely discounting the engineering practice of cooling (both natural and forced)?

The chips can not be very far - the phase delays involved will make control systems hard.


I'm not- but you are discounting the expenses and complexity associated with cooling, even forced cooling. Also how reliable will such a system be? the present CAM system may become inefficient but it will not stop working if it overheats by a hundred degrees.


One can write off the main equipment, let alone the electronics, when such rapid change happens. For example, in rockets 100degC temperature change in 3s would mean the rocket has disintegrated, or the satellite has broken up. Otherwise, the electronics would still be protected from exposure.

These are actual DRDO requirements for chips made by one of my ex-colleagues. They went into bombs and rockets.

A rocket unfortunately has no space, carries no weight, and can provide no thermal isolation. Also your enemy doesn't give you notice so you can not give the users advice such as "keep the engine idling for 30s before moving or turning off". If you are at a post in Kashmir sitting at -20C or worse, and suddenly launch a rocket then the temperature inside will change from roughly -20C to over 100C in a matter of seconds. And these are control system chips. The rocket will disintegrate, but a short while later (when it reaches the target)

One normally uses a. radiation hardening, and b. robust algorithms. These techniques have been around 30 years at least - since TTL and SSI days! Doesn't normally appear in college text books though.

I don't deny that - but what is the cost? I once designed a radiation hard FlipFlop - it was double the size of the normal.


Absolutely agree. If the objective is set after checking the quantum of gain then material science, technology and engineering will follow as always. One can look at the large investment needed in a different way - it is a business / economic opportunity that one can't pass over. No?

I agree. I'm saying there is no opportunity here.



Why would a valve take 500W to open and shut? You are assuming current tech again, right? What happens if one does away with the spring (which is used to hold the valve shut - and naturally is a hindrance to opening)? What if one uses a positioner instead of a solenoid? What happens if you get a different seat material? The possibilities are, if not endless, numerous enough. And one builds products by looking at possibilities, and not being deterred by constraints.

As I wrote about this - I don't know but I suspect this may actually be an underestimate. As I wrote earlier this is based on 1% power loss due to the valvetrain (which I requested for someone to validate)

Also I wrote about solenoid because we were talking about valves. I can't comment on positioner, though I would guess that since positioner is way more complex than simple open-close it will probably be even more power hungry.


You are right that a change in how things are done can make things better. I mean in steam engines sliding valves (no springs) were used and those may help here too. (But even then you have to move mass and hold it in position. Invariably friction losses will come into picture.
)

but I have been talking only about the case of keeping the engine largely the same - just removing camshafts and then operate the valves electromagnetically.




Even the alternator throws out a significant amount of power in RF range - enough to possibly cause EMI disturbance. The engine bay is 5 sides shielded, so you cause minimal disturbance outside the car. The car electronics is 6 sides shielded, so it is not affected. Old tech - good electrical practices like grounding.

- alternator is two (or more) phase device working with sinusoidal waveforms of low frequency that have very few harmonics; The fundamental frequency (and harmonics) are cancelled out by the fact that their vector addition is 0 by design. Also fundamental frequency is very low (200Hz for 12000 rpm).
And to top it all it is very compact - the signal that does come out is DC which can not radiate anyway because the antenna size is small.

For valve-driver to be fast and programmable the rise/fall times will be very fast (hence the bandwidths I mentioned) and the wire is not compact. Nor will the phases necessarily cancel each other.

But still I agree with you that given the low frequencies involved the EMI may not be a big issue. You are right about shielding due to the car body - but do you really want this challenge.



My argument is this - I can think of multiple ways you can achieve variable opening/closing angle (with respect to shaft) though not a way where you can open and close multiple times within the same stroke (and even electrically that is very hard) that can be electro-mechanical (e.g. vary the spacing between drive shaft and the camshaft on the timing belt - changing the phase on the go)
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Old 28th April 2011, 22:10   #50
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Default Re: Camless and electronic timing : The future?

Hi Sindabad

thanks for another fascinating post. I'll just briefly put my points of disagreement below (everything else is very educational)

Quote:
Originally Posted by sindabad.sailor View Post

Any new technology that is introduced in shipping is obviously first developed ashore and tried out. Since marine engines market sizewise is very very small, there are pretty high chances that these technologies were developed for some different intentions (read automotive) and later found their way into shipping.


There is nothing obvious in this.

This is a part of the segment of large industrial/marine/railway engines. These are specialised products where customers care about performance and pay top $$$. Why would they not develop their own technology?

I mean if you think about it F1 is a small market to and the innovation usually happens there first.

It is possible though that the technology may piggyback wherever there is an overlap


Quote:
Originally Posted by sindabad.sailor View Post

As regards CPU and other electonics not sustaining environmental tortures, I strongly feel that todays electronics hardware is pretty strong to these external factors.

...

They have their own cabinets but no ventillation/cooling. Few fuel pipes carrying fuel at 145 deg C are passing close to it. The whole area is god damn hot and in areas like persian gulf is just unbearable but still this electronics is going strong, add to that the vibrations, humidity and dust. In a nutshell electronic components are pretty tough nowdays.

This should tell you the cost implications of the whole thing - your application can support entire room for electronics, a car probably can not (though a truck might). So even expensive electronics can be accomodated in the budget

Also you talk about it being unbearable in persian gulf - what that tells me is that the temperature is no more than 70C (at that temperature it'll be beyond unbearable - your skin will burn and develop boils)

Another thing - your engine is rated 18.5MW (as you wrote earlier) this is equaivalent to the peak power of about 350 Maruti Swift cars at their peak power. the price of the control systems will not come down 350 times when you try to resize it to cars (except the CCU you talked about, everything else will be similar and car engine having faster speeds - perhaps more expensive)
Keep writing more about your engine -
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Old 28th April 2011, 22:15   #51
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Default Re: Camless and electronic timing : The future?

Quote:
Originally Posted by DerAlte View Post
Fantastic topic and discussion.clap.
Any idea what kind of solenoids in used in the 2000 bar common rail injectors?
The frequency is also be comparable (ie fire 1 once every 4 strokes)...not counting pilots.

It seems like the pressure load is pretty high but IIRC the solenoids do not directly hold the fuel pressure.

Last edited by Mpower : 28th April 2011 at 23:15.
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Old 28th April 2011, 22:20   #52
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Default Re: Camless and electronic timing : The future?

Quote:
Originally Posted by Sutripta View Post
I think you have misunderstood what I meant by 'mechanical'.
A solenoid cannot operate directly on a poppet valve, it has to be through some mechanical linkage. Once the solenoid is energised, it will generate a force. Which will act on a mass. Newtonian mechanics takes over.
Absolutely did not mean mechanical relays etc.

Regards
Sutripta
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?

Also, the power requirements will be similar to solenoids directly driving the valves - so alternator etc. still come into play.


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%

Last edited by vina : 28th April 2011 at 22:22.
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Old 28th April 2011, 22:32   #53
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Default Re: Camless and electronic timing : The future?

Valeo has customers for camless engine with "smart valve actuation" — Autoblog Green

Here's some more.

there was another blog mentioning the same company and talking about reliability problems.
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Old 28th April 2011, 22:39   #54
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Default Re: Camless and electronic timing : The future?

And another:

WHAT'S NEXT; A Chip-Based Challenge to a Car's Spinning Camshaft - New York Times

one page 2 you'll find " For one thing, the solenoids and the additional computer power taxed the car's already overburdened electrical system" as I have been arguing.

also "For car makers, the system's least attractive aspect was its price relative to camshafts"

"Motorola believes that the control computer could be programmed to soften and quiet the action of the solenoids" tsk1979 - this explains the noise. In a camshaft the opening and closing of valves in smooth - the velocity of the walls gradually falls to zero when it leaves its seat or approaches its seat. Not so with solenoids - they cause noise by hitting the piston.

"a device that uses piezoelectric crystals ..." I don't know what they were smoking.

And page-3 mentions why mechanical camshaft advances have made the technology redundant.
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Old 28th April 2011, 22:43   #55
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Default Re: Camless and electronic timing : The future?

Refer post #52
No, pure mechanical. If one wants to have a 'powerful' solenoid, the pole pieces have to be close together. Which means very small travel. It will have to be magnified. Something like a mechanical lever system. Which can be designed to move the solenoid physically away from the valve and its environment.

I don't think cam losses are significant enough to justify not using it, esp. if we have things like roller tappets.
In any case, it is about control. Way superior to VTEC/ VVT etc. (Even Goodbye Otto, welcome Atkinson/ Miller etc) And eliminating the throttle plate.

Valves are not operated multiple times a cycle.

Incidentally, there were valve systems other than poppet valves.

@Sinbad
What is the rpm of the engine? How do you reverse it?

Regards
Sutripta

Last edited by Sutripta : 28th April 2011 at 22:47.
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Old 28th April 2011, 23:02   #56
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Default Re: Camless and electronic timing : The future?

Quote:
Originally Posted by tsk1979 View Post
I tried searching the net, and most articles are pretty old, and list several disadvantages of using solenoid valves, controlled by a ECU for timing etc.,

The drawbacks are listed as difficulty of operation at speed, high fuel consumption etc.,

However, these articles are from 2007 or older.
ECU technology has come a long way, and today for the same price you get much faster and more durable processors.

So why is the technology not picking up. It will definitely remove lots of components like timing chains/belts, cams etc.,
Like Solenoid valves, people have experimented with drive by wire steering systems.
The reason you would never find a car with a drive by wire steering is because its too risky. An ECU may be a real-time system with high reliability, but it's still a risk!
Similarly, if a solenoid fails and if you have an interference engine setup, your solenoid valve will ruin the engine.
Not to mention, you will be wasting a lot of electrical energy actuating these solenoids. Imagine the amount of energy these solenoids will need to expel. This same electrical energy will be driven by the alternator. And since your alternator will consume more electricity to run the solenoids, it will sap additional power from your engine.
Or imagine -- an alternator failure can even lead to broken valves or a damaged engine!
There are too many 'dependencies' using this system.

Au contraire, ECU technology has little to do with the development of solenoid valves. If you can have injectors controlled by the ECU, you can pretty much do the same for solenoid valves.


Quote:
Originally Posted by tsk1979 View Post
All you will have is a set of solenoids controlling the valves, and a dedicated ECU. No more timing belt nonsense.

Even high speed engines going 10,000 rpm, its no big deal for todays processors. We are in the era of Giga flops.
I am afraid, that processing power has nothing to do with the actuation of the solenoid valves. Valves needs to be actuated quickly,which requires little processing power and if you were to actuate the valves using solenoids, you would need to take into consideration:
1) The amount of EMI generated by these valves.
2) There is a possibility of some sort of a back-EMI inducing and dampening the accurate actuation of adjacent valves, if not properly isolated.
3) Heavy ferrite cores may be required around the solenoids to insulate and shield the solenoids.



Quote:
Originally Posted by tsk1979 View Post
Even solenoids are a lot better and faster than what used to be in the market 5 years from now.

So while lots of companies like BMW, Renault, Mercedes are apparently experimenting, this is one area where there is no "buzz" or excitement in the auto world.

As an electronics guy, I would prefer everything which can be made electronic to be made electronic.
Reasons are simple
1. Hardware is cheap and can last 10-15 years before failure, if proper quality control is used
2. Will reduce the weight as well as cost
3. With an ECU, no more complex circus required for variable valve timing. you can literally advance and retard timing as per need on the fly.
4. It will enable simpler variable compression engines.
5. Theoratically, it will enable you to create a variable stroke engine. I am not sure about this, but looking at how an otto engine works, if you could operate valves at will, you could change length of the con-rods on fly and have your engine long or short stroke.

As for disadvantages, wikipedia will give you a list, but does not tell you why. Nor do the internet links tell you the "why" of those disadvantages.

Any engine experts care to comment?
Mercedes has also experimeted with fly by wire steering systems. All manufacturers will continue to experiment.

Hardware is cheap, but only after manufacturers have the ability to churn out the hardware in large quantities. New technology costs money. There are R&D costs that need to be recovered in the beginning. Concept may exist, but implementation of this concept requires a lot of research

Last edited by thermalpaste : 28th April 2011 at 23:04. Reason: spelling mistake
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Old 28th April 2011, 23:03   #57
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Default Re: Camless and electronic timing : The future?

Quote:
Originally Posted by Sutripta View Post
Refer post #52
No, pure mechanical. If one wants to have a 'powerful' solenoid, the pole pieces have to be close together. Which means very small travel. It will have to be magnified. Something like a mechanical lever system. Which can be designed to move the solenoid physically away from the valve and its environment.

I don't think cam losses are significant enough to justify not using it, esp. if we have things like roller tappets.
In any case, it is about control. Way superior to VTEC/ VVT etc. (Even Goodbye Otto, welcome Atkinson/ Miller etc) And eliminating the throttle plate.

Valves are not operated multiple times a cycle.

Incidentally, there were valve systems other than poppet valves.

@Sinbad
What is the rpm of the engine? How do you reverse it?

Regards
Sutripta

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.

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.

sinbad's engine is a MAN engine, rated 18.5MW@91rpm (that is right)

http://mandieselturbo.com/files/news...ng%20%20ME.pdf


The engine is the size of a whole apartment building.
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Old 28th April 2011, 23:21   #58
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Default Re: Camless and electronic timing : The future?

Quote:
Originally Posted by cranky View Post
@vina:
...

I'm guessing F1 can afford the costs of developing technology like this and at 20k rpm things change significantly enough. I wonder how they power the array though - I think it's primarily a hydraulic system, with only control input from electronics.

I would guess you are right about F1
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Old 29th April 2011, 07:45   #59
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Quote:
So while lots of companies like BMW, Renault, Mercedes are apparently experimenting, this is one area where there is no "buzz" or excitement in the auto world.
Because the experiments are not successful as yet!


Quote:
5. Theoratically, it will enable you to create a variable stroke engine. I am not sure about this, but looking at how an otto engine works, if you could operate valves at will, you could change length of the con-rods on fly and have your engine long or short stroke.
Sir, this is a BIG statement. Can you elaborate on this please? The con rods have physical dimensions!!!

Variable cylinder management is possible but variable stroke is like

Electronics have improved leaps and bounds, but the "correct" failure time is not established.

Infact, a major indian auto manufacturer {with presence on this forum} showcased one of their best sellers with a electronic steering way back in a Auto Expo at New Delhi. It would eliminate the steering rack and the steering box mechanisms entirely because it used encoders and servo motors for the same.

It has not yet come to the market for reasons best known to the manufacturer!!!

Electronic timing is possible with limitations though.
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Old 29th April 2011, 09:34   #60
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Default Re: Camless and electronic timing : The future?

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.
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