[tsk1979]

In modern engines, many jobs earlier done by mechanical parts are now done by electronic ones. For example, now you have electronic fuel pumps, ECU to control fuel and air mixture etc.,
However, in one area, its still all mechanical. There have been experiments, but nothing concrete has come out.
That is the area of Cams and Valve timing.

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.,

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.

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.

When MPFI and CRDI came out, despite of many naysayers who swore by the carburettors and how ECUs will fry in those extreme temperatures, there was lot of excitement, and engine technology grew leaps and bounds.

However, replacing this mechanical domain with electronic, there is more smoke than fire.

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?

[ph03n!x]

Here is something from Wikipedia:

Camless engines are not without their problems though. Common problems include high power consumption, accuracy at high speed, temperature sensitivity, weight and packaging issues, high noise, high cost, and unsafe operation in case of electrical problems.

The articles also has a bunch of interesting references (not sure if have already referred to it).

[tsk1979]

Originally Posted by ph03n!x

Here is something from Wikipedia:


The articles also has a bunch of interesting references (not sure if have already referred to it).

I read that. However, none of the references go into the details of why.
Moreover, most of the sources are from 5 years ago. Solenoid tech as well as ECU tech has come a long way since then!

[ajmat]

If i am correct, the Fial Multi Air engine uses electro-hydraulic valve actuation already

[cranky]

Solenoids would be very impractical for car valve actuation.

A typical valve used to hold a door in a typical office would require about 10 watts to stay in steady state, and resist a typical pressure of 50kg/m if you didn't have Tom Cruise trying to break in.

The forces in an engine are much higher, so let's say it's 20 times. The solenoid power increases disproportionately, so assume 200 watts. That's 20 amperes. And then it switches on and off 8,000 times a second. If your alternator cut out, a typical engine made of four cylinders/8 valves would empty a battery in about one second at full power.

I can see also why they would be noisy. A cam is a smooth rotating piece, a solenoid will need an endstop or it'll simply pop out of its casing. It'll hit that endpoint every time it actuates. That's gonna be a racket with even just two valves per cylinder.

And imagine for a second the car ran out of electrical power and the engine was turning with the ignition going and no fuel to burn and no air to breathe if the valves cut out.

Hydraulic definitely seem better, but it's still (to an extent) mechanical. It would also be much, much quieter and if the system is properly sealed, more reliable.

My understanding of MultiAir technology is that it is a VVT technology that reconfigures inlet timing for low power output to maximise fuel consumption, and at high engine speeds it goes back to typical default configuration where the valve opening recouples almost directly to the camshaft input. could be wrong though.

[sindabad.sailor]

Hello all,

Apologies as I am an automotive novice tryping to peek into the subject.

However I currently am sailing on an absoloutely electronically controlled engine driven huuu...ge ship.

This engine 6S60ME-c meaning 6 cylinder, S-superlong stroke, 60 cm bore, electronically controlled marine engine is designed by MAN B&W built at Doosan Korea is doing great service to worlds most talked about hyper sized LNG ships on which I am sailing for over 2 years now.
In fact the ship is a twin screw ship meaning sails on two propellers (which work on the screw principle) and hence there are two eninges in the ship each of 18500KW capacity.

Having worked for some time on conventional cammed engines, this camless engine is a gem amongst all engines I have sailed so far.

I haven't experienced any of the proposed fears translating into reality in these years except a typical problem which was more due to faulty design than engine's being camless.

The exhaust valves have a capacitance type probe that measures the stroke. Earlier generation probes had comparatively slow response time and hence I often used to get Exhasut Valve Low stroke Alarm and eventually engines used to slow down automatically as a safety. However the manufacturers supplied improved probes and this problem is no more recurring.

Apart from this I did not have any single issue.

Advantages:

Marine fuel oils can have sulphur content upto 4% (allowed 5%) This upon combustion can cause generation of sulphuric acid vapours within the cylinder corroding it severely. To encounter the same the lubrication for the liner is supplied by injecting alkaline Cylinder Lube OIl of TBN 70. This oil costs fortunes and with ME-C engines specific LO consumption is substantially lower. Since ships are run for upto 30 years, the economics tilts in favour of electronically controlled engines.

Another big advantage is that shipping industry too is pressed hard for environmental norms under discussions. Since these norms are coming in succession to meet these norms a normal engine would require extensive hardware change. However with electroniclly controlled engines just a change in logarithm can change the injection characteristics and patterns hence would sure rule the marine engines of future.

Apologies if my explanations are bit OT. But I thought it could be relevent.
What I wanted to stress is that the fear about all electronically controlled engines is uncalled for.

Rgds and many thanks.

[pranavt]

Timing it precisely at high RPMs could be a factor IMO. The tech is available for sure, but nowhere near affordable enough to be put as OE components unless the prices fall massively.

Would be fun though lol. Instead of changing the cams for higher/lower lift/overlap, you could simply put new timing maps for the valves. The tech will definitely come in as OEM components in cars, but it will take time for it to become cheaper.

[SPIKE ARRESTOR]

Originally Posted by tsk1979

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
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.

Interesting topic. Will you prefer such vehicles for 4x4 applications? Why?

2. Will reduce the weight as well as cost

Not sure on this, I've seen some models with harnesses weighing up to 25-30 kgs.

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.

How?

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.

You won't find much.

Spike

[Sutripta]

Originally Posted by ajmat

If i am correct, the Fial Multi Air engine uses electro-hydraulic valve actuation already

Not camless, AFAIK.

Originally Posted by pranavt

Instead of changing the cams for higher/lower lift/overlap, you could simply put new timing maps for the valves.

That was the promise of 'helenoids', for R&D, rather than production. This would be the 80s. But haven't heard of it for a very long time. Wonder what happened to it.

Regards
Sutripta

PS. Wonder what will be the reaction of a person having 'mechatronic' (in a DSG) trouble to electrically operated cams?

[julupani]

I think cranky has hit the nail on the head perfectly over here.

I woul like to add one thing, that is, technology is never implemented practically, just because it exists. There has to be an economically justified need for it.

The point is, are there any serious advantages to be gained out of implementing a camless valve operation. Does going camless give you a certain advantage, which cams cant at this stage in time.

The only serious advantage I see is an ease of implementing variable valve timing. With mechanical systems like VTEC doing the job more than fine and reliably so, there doesnt seem to a need to go camless. Agreed, camless would allow for a lot more variation in timing, but is there a need to have such minute variations in timing.

Also, as a mechanical engineer, let me make it clear, it will not pave the way for variable compression engines. It may help in the future, but let me assure you it will make the problem no easier.

It wont be as simple as changing out a con-rod. The major problem with implementing variable compression is you cant change out any of the moving parts, independently of each other. The piston, conrod and the crankshaft are the cause of almost all of the vibrations that you feel in a car. Valves and camshafts contribute in a very minor way, almost completely negligible. The piston, conrod and crankshaft have to be designed in sync to keep the vibrations to a minimum. One cant just change out the conrod simply with one of different length. It would upset the balance of the engine.

If you have to implement variable compression in this way, you would need to change out all three components. This would mean keeping a prepared set of theses components for each block design.

Also, if you want to practically implement variable compression, it should be able to occur on the fly, without having to go to a workshop to change out half the engine.

It may be useful in racing engines, but not for day to day cars.

[SS-Traveller]

Yes, Tanveer, the future it is, but how far ahead would be anybody's guess - maybe by that time you just might be able to buy a nuclear powered WE.

Originally Posted by cranky

Solenoids would be very impractical for car valve actuation.

@cranky: Very succintly summed up issues. Even with valves being actuated by camshaft lobes, valve bounce and float are issues in the higher revving engines - usually counteracted by heavier valve springs, or even pneumatic springs in racing engines. To have a solenoid do the job a camshaft does would mean generating that much more electricity, which would negate the power gain because the load of the camshaft is eliminated - in fact, without getting into the maths of it, I think there would be a heavier power sapping because of the load of a massive generator, than the load imposed by the valve train as per current designs.

Originally Posted by sindabad.sailor

...an absoloutely electronically controlled engine driven huuu...ge ship.

This engine 6S60ME-c meaning 6 cylinder, S-superlong stroke, 60 cm bore, electronically controlled marine engine...18500KW capacity.
...with electroniclly controlled engines just a change in logarithm can change the injection characteristics and patterns hence would sure rule the marine engines of future.

Point taken. But then the operational parameters of a marine engine are vastly different (and 100x bigger) than any engine in automotive use. Again, marine engines have moved on from using fossil fuels to nuclear - probably another scary scenario for us right now, but in the future one can expect the world to run out of fossil fuels and switch over to alternate (read: nuclear) power sources.

If camless technology is not running in F1 engines now, we don't expect to see them implemented in road-going cars even 10 years into the future. But the IC engine has been partially replaced by the electric motor quite successfully, and I expect to see the IC engine missing from under the bonnet of my car completely before the camshaft makes itself scarce.

Originally Posted by Sutripta

PS. Wonder what will be the reaction of a person having 'mechatronic' (in a DSG) trouble to electrically operated cams?

[tsk1979]

Originally Posted by SPIKE ARRESTOR

Interesting topic. Will you prefer such vehicles for 4x4 applications? Why?

What has 4x4 got to do with all this.

How?

IF you can precisely control your valves using software, having the ability to advance or retard timing at will, you can change your stroke to alter compression at will.

[pranavt]

Originally Posted by julupani

It may be useful in racing engines, but not for day to day cars.

On the contrary, it would be utterly useless in racing engines. They operate in a very short powerband (60-100% of the redline RPM). Plus, they have atleast high octane (98+) fuel, and at best, 110+ octane race fuel. Don't see why race engines would need to lower compression. Remember, even when variable valve timing was not banned in F1, nobody used it. Mainly because it added weight and didn't really serve much of a purpose.

Originally Posted by tsk1979

IF you can precisely control your valves using software, having the ability to advance or retard timing at will, you can change your stroke to alter compression at will.

What? How does having control over timing have anything to do with the stroke? If you are purely talking about compression, then you can change the dynamic compression by altering the valve lift and timing. But the static compression would stay constant unless you moved bottom-end closer or farther away from the combustion chamber.

[Sutripta]

Originally Posted by SS-Traveller

To have a solenoid do the job a camshaft does would mean generating that much more electricity, which would negate the power gain because the load of the camshaft is eleiminated

The promise is better control, (and eliminating the throttle plate) rather than eliminating camshaft mechanical losses.

But the IC engine has been partially replaced by the electric motor quite successfully, and I expect to see the IC engine missing from under the bonnet of my car completely before the camshaft makes itself scarce.

Our friends up North are heavily betting on this.

Regards
Sutripta

[SS-Traveller]

Originally Posted by tsk1979

...you can change your stroke to alter compression at will.

How would one be able to change the stroke of an IC engine at will? AFAIK the stroke is invariably related to the crankshaft offset. What has camless valve actuation got to do with it?