[sindabad.sailor]

Hello Vina,

About the thing being obvious:

There are certain innovations which are exclusively aplicable to marine engines.e.g
2nd order moment compensators for cancelling such moments arising from big engines,
cross head lubrication technologies etc
These had been developed with marine engines in mind.

However I don't think camless engines idea was developed with marine engines in mind. It should have been an idea which marine engine makers realized useful after its emergence.

For example say VGT is still not heard in marine engine turbochargers. I was appearing for my certificate of competency exam when the Dy Chief Surveyor of India asked about latest developements in enigne tech. When I mentioned abt some research I had heard on VGT in mairne engines he gave expressions as if i was story telling some weird sci-fi movie. Point is technologically marine engines lag behind sautomotive engine developements on some fronts.

About temperatures in engine room, we have heat detectors at a few places to indicate existence of fire. One of the requirements is that they should give an alarm at 72 deg C ( i will check) apart from some rate of temperature rise etc requirements. And in what is called as purifier room, where all fuel and lube oil heaters and centrifugal separators are located , we often receive the fire alarms in persian gulf.
These centrigugal separators too have electronic sensors like speed pick-up, vibration sensors, proximity switches, Differential pressure trx apart from usual Pt100 and pressure trx. These are still going strong.
I definitely admit that it is no way close to 200 deg C but 72 deg C itslef is quite harsh to test electronics and I believe that even in automotive applications theses cards need not face 200 deg C.

BTW i have a lot of doubts pertaining to electronics. I hope you wouldn't mind if I PM you them.

Rgds.

[sindabad.sailor]

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

Marine engines are started by injecting compressed air usually at 30 bar pressure in the firing order. For this there is a DISTRIBUTOR involving cams and cam operated valves in convnetional engines.

Whenever reversing command is received, first this distributor is shifted to reversing poistion first. This achieved hydraulically in Sulzer engines and pneumatically in MAN engines. In reverse position, the distributor admits the starting air in reverse firing order and entire engine runs in reverse direction.

In ME engines this whole hardware has vanished as the ECU just manipulates the sequence of operation of solenoid valves openign starting air valves.

BTW this engine runs at 87 rpm with power output of 85% Max Continuous Rating (18.5 MW in this case) which is NCR (normal continuous rating) in marine engines.

Rgds.

[vina]

Originally Posted by sindabad.sailor

Hello Vina,


However I don't think camless engines idea was developed with marine engines in mind. It should have been an idea which marine engine makers realized useful after its emergence.

I agree - in fact the chronology of events suggests that is the case. However it may be so that automotive guys started it, didn't find it useful and then some bright guy said "wait a minute - marine can still find it useful" and then the marine guys developed the technology.

My point is just because it is a small market, doesn't mean that marine wouldn't innovate - but I guess you mentioned that already.

For example say VGT is still not heard in marine engine turbochargers. I was appearing for my certificate of competency exam when the Dy Chief Surveyor of India asked about latest developements in enigne tech. When I mentioned abt some research I had heard on VGT in mairne engines he gave expressions as if i was story telling some weird sci-fi movie. Point is technologically marine engines lag behind sautomotive engine developements on some fronts.

I know the government types, my father is a scientific officer and I lived in the midst of these guys all my young life. Don't go with what they get surprised with - though many (but that can be a small fraction) of them are good, most of them don't know what they are talking about.

I once had an argument with a director of one of the labs on household power supply - we had a transformer malfunction in the neighborhood and somehow the neutral wire started sending one of the phases. Our man argued that since both the voltages are same they should cancel out - he did use the word "phase" but didn't have any idea of vector addition. And he was a mechanical engineer by training.


About temperatures in engine room, we have heat detectors at a few places to indicate existence of fire. One of the requirements is that they should give an alarm at 72 deg C ( i will check) apart from some rate of temperature rise etc requirements. And in what is called as purifier room, where all fuel and lube oil heaters and centrifugal separators are located , we often receive the fire alarms in persian gulf.
These centrigugal separators too have electronic sensors like speed pick-up, vibration sensors, proximity switches, Differential pressure trx apart from usual Pt100 and pressure trx. These are still going strong.
I definitely admit that it is no way close to 200 deg C but 72 deg C itslef is quite harsh to test electronics and I believe that even in automotive applications theses cards need not face 200 deg C.

See that's what I was talking about - 70C ambient is something you can (really) find in a car parked outside in sun in a Delhi summer afternoon. In fact two weeks ago my hands burned when I held (against my better judgement) the steering wheel of my wife's car in Mysore - the car had been standing in sun. This was around 11am and the max day temp those days was still less than 35C.

Making electronics work for that is still relatively easy (that is why automotive grade audio ICs also tolerate 125C - even though they obviously have no business being in the engine bay).

the problem is that in an automobile of today's configuration, the actuators will have to sit near the engine - and that gets HOT. When engines overheat, the radiators spew steam at high pressure - that should give you and idea.

Also your engine compartment (though it has its own problems) will hardly ever see shocks of the kind experienced when an automobile goes over a bump at high speed, and given that you live in enclosed areas vs. automobile is out in the open, there is no way to control what can get in.

Biggest constraint of all - people building thirty feet tall engines would probably not mind spending a little extra to get very reliable electronics hardware, and then providing enough space to house it. The two factors together are a problem for passenger cars and sports cars alike.

BTW i have a lot of doubts pertaining to electronics. I hope you wouldn't mind if I PM you them.

Rgds.

Please do feel free to write to me. I'll help you out to the best of my abilities.

[vina]

Originally Posted by sindabad.sailor

Marine engines are started by injecting compressed air usually at 30 bar pressure in the firing order. For this there is a DISTRIBUTOR involving cams and cam operated valves in convnetional engines.

Whenever reversing command is received, first this distributor is shifted to reversing poistion first. This achieved hydraulically in Sulzer engines and pneumatically in MAN engines. In reverse position, the distributor admits the starting air in reverse firing order and entire engine runs in reverse direction.

In ME engines this whole hardware has vanished as the ECU just manipulates the sequence of operation of solenoid valves openign starting air valves.

BTW this engine runs at 87 rpm with power output of 85% Max Continuous Rating (18.5 MW in this case) which is NCR (normal continuous rating) in marine engines.

Rgds.

Wouldn't you have to stop the engine first and then start it again to reverse?

Also (to others) what would be the purpose of having a car that can use all gears in reverse? Do you intend to drive it at high speed in reverse?

So far as I know the gear ratio for the reverse gear is usually such that the wheel-rpm/engine-rpm ratio is less than event that of the first gear. I don't think that is done to improve torque only, I think that is also done to restrict speed of the car in reverse.

[sindabad.sailor]

Wouldn't you have to stop the engine first and then start it again to reverse?

Of course in normal cases, engines are first stopeed and only then reversed.

There is an interlock called Wrong Direction Interlock which prevents fuel/starting air being injected in reverse firing order.

Since I have mentioned so much irrelevent stuff here I would like to share that in extreme emergency cases where collission is imminent, marine engines can be reversed from full steaming ahead to full astern without waiting for engine to halt intermittently. Actually eninge will pass zero prior reversing to full but only momentorily.

This is called crash astern or double ring astern in marine lingo. You might remember in some movies say Titanic, the wheel house rings the telegraph (which communicates what engine rpm wheelhouse wants) twice to full astern. The name double ring is from this act which communicates to engine room that crash astern is required.

The engine builders usually guarantees only two such crash astern operations in engines entire life (as taught to us in cirriculum). Of this one is spent during sea trials after new shipbuilding in proving emergency stopping distance. This leaves only one guaranteed crash astern operation in life time of engine. Thereafter the engine may or may not survive subsequent crash asterns.

Rgds.

[Born2Slow]

Hi Sinbad.sailor I belong to the side who troubles you all the time including the crash astern . What do you think VGT is not of much use to large marine engines as we operate at a very narrow RPM rage most of the times.

[vina]

Originally Posted by sindabad.sailor

Of course in normal cases, engines are first stopeed and only then reversed.

There is an interlock called Wrong Direction Interlock which prevents fuel/starting air being injected in reverse firing order.

Since I have mentioned so much irrelevent stuff here I would like to share that in extreme emergency cases where collission is imminent, marine engines can be reversed from full steaming ahead to full astern without waiting for engine to halt intermittently. Actually eninge will pass zero prior reversing to full but only momentorily.

This is called crash astern or double ring astern in marine lingo. You might remember in some movies say Titanic, the wheel house rings the telegraph (which communicates what engine rpm wheelhouse wants) twice to full astern. The name double ring is from this act which communicates to engine room that crash astern is required.

The engine builders usually guarantees only two such crash astern operations in engines entire life (as taught to us in cirriculum). Of this one is spent during sea trials after new shipbuilding in proving emergency stopping distance. This leaves only one guaranteed crash astern operation in life time of engine. Thereafter the engine may or may not survive subsequent crash asterns.

Rgds.

How is anything you wrote irrelevant? The thread is about camless and electronics timings and yours is almost the only production engine that is camless and uses electronic timing to the fullest.

What you wrote is very interesting, however I remember that in the movie they first stopped the engine and then reversed it.

Also I believe that one was a steam engine (they were hauling coal).


I would assume that in the emergency you described even the propellers (or whatever you have now) will also have to stop first - otherwise those can also get destroyed (along with the bearings etc.)

[sindabad.sailor]

Hi Sinbad.sailor I belong to the side who troubles you all the time including the crash astern . What do you think VGT is not of much use to large marine engines as we operate at a very narrow RPM rage most of the times.

God I feel so great there is no phone number thing on Team-BHP.
Jokes apart.I was guessing there would sure be lot of seafarers over here.
Anyways lucky me nobody has ever troubled me over crash astern so far. Nice to make acquaintences with you.

I think VGT can have applications on ship's main engines. You must be aware of FUSS engineers make when wheel house asks for some intermediate speed. That is all because if speed set point not chosen wisely at speeds below half manoeuvring speed the auxiliary blowers will keep cutting in and out and we might burn them out.
With VGT, Turbos can be matched even for this part load operations and in the long run would you not like marine engines to be step less?

I would assume that in the emergency you described even the propellers (or whatever you have now) will also have to stop first - otherwise those can also get destroyed (along with the bearings etc.)

Marine engines are directly coupled to propellers, at least the ones that i have sailed on so far. Thus engine speed zero invariably means propeller speed too is zero.

BTW Vina, I had a problem few years back. The amplifiers for Exhaust temperatures were fitted on to exhaust receivers. Temperatures there used to be severe. Once i went there and burnt the sole of my safety shoes. Due to this intense heat the isulation of cables running from PT100 to amplifier used to burn away and these cables used to short with body causing erratic readings and engine slowdown.
These PT100 were supplied integral with special cables of specific resistence. Hence whenever I used to replace the grounded bare cables with high temperature cables from my store, the readings used to go hayway due to change in the resistence.
I know if I use 3 -wire loop instead of 2 wire loop, I can cancel the effect of resistence variation. However I am unable to remember how to go about 3 wire looping. Though this is more an electrical problem than electronics one, I hope you can help.

Rgds.

[Sutripta]

Originally Posted by sindabad.sailor

In ME engines this whole hardware has vanished as the ECU just manipulates the sequence of operation of solenoid valves openign starting air valves.
Rgds.

So it's pushbutton now. Thats what I wanted to know.

Originally Posted by vina

I would assume that in the emergency you described even the propellers (or whatever you have now) will also have to stop first - otherwise those can also get destroyed (along with the bearings etc.)

Propellers directly coupled. In fact that is why you have to reverse the engines. Fortunately, easy with steam or purposemade diesels. Incidentally twostrokes can also easily operate in reverse.

Originally Posted by sindabad.sailor

I know if I use 3 -wire loop instead of 2 wire loop, I can cancel the effect of resistence variation. However I am unable to remember how to go about 3 wire looping. Though this is more an electrical problem than electronics one, I hope you can help.

Rgds.

Considering we are talking of robust engineering, the fact that the Pt100s were not setup for 3 wire system is really surprising. Or maybe the resistance could be measured and entered in the measuring instrument.

General:
Reversing an automobile engine is problematic, because ancillary services like water and oil pumps are direction sensitive.
That said, one of the bubble cars had to be reversed by stopping and reversing the engine. I forget which. DAF?

Regards
Sutripta

[sindabad.sailor]

So it's pushbutton now. Thats what I wanted to know.

Yes and no. It is controlled by what is called as telegraph which is a rotary handle. Early generation handles used to depress pilot valves which was similar to pushbuttons.
But nowadays it is all contactors getting closed and opened sending electric signals.

Considering we are talking of robust engineering, the fact that the Pt100s were not setup for 3 wire system is really surprising.

Bang on point sir. But apperently they have robust after sales calculations. I mean they probabaly did it on purpose so that in every such case we would have to buy a new PT100 with cables from them. One pice once costed some 300-350 USD.

Or maybe the resistance could be measured and entered in the measuring instrument.

I instead used to use span adjustments to achieve remote reading equal to local pyrometer readout. This used to solve purpose in a way. But thenat part load the readings again used to go hayway as zero was not done. We simply could not afford to waste time adjusting span zero span zero aswe otherwise would have required to wait every time for the PT100 to cool to room temperature to carry out zero after heating in calibrator for span adjustments.
But these new age ships have distributed control system and hence it is much easy to read out local reading and force the engineered output for the specific channel using computers. Though the layout on these ships is better hence no such problems have occured so far.

Rgds.

[DerAlte]

Originally Posted by vina

... This is if you don't want to use permanent magnets. My assumption is that both the coils (the stationary and the moving) ...

Errr... aah... Solenoids?

Originally Posted by vina

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

Enh? Cooling and phase delays?

Originally Posted by vina

... I'm not- but you are discounting the expenses and complexity associated with cooling ...

Originally Posted by vina

...but what is the cost?... I'm saying there is no opportunity here. ...

Oooooh! I am sure a course in any B-school will enable you to look at the capitalist way of looking at business, the same capitalist way that has got the world modern electronics - everything from semiconductors to equipment.

Going by your economic principles, we wouldn't have seen Diesel Injection systems: development of electrically controllable injectors cost a few hundred million dollars over 20 years. And common rail injection systems started 60 years back. Surely you wouldn't have seen an opportunity there either?

As far as cooling is concerned, anyone who has done it at least once knows how simply and economically it can be done. To those who haven't, it is complex. Of course, those involved in insides of components don't often think at sub-assembly and system level. Just like a brick-maker does not think of walls or architecture.

Originally Posted by vina

... - alternator ... Also fundamental frequency is very low (200Hz for 12000 rpm). ... can not radiate anyway because the antenna size is small. ... but do you really want this challenge. ...

Look inside the alternator - there is a commutator which conducts current to the field coil, and that current is modulated to modulate the output voltage. High frequencies are produced when there are discontinuities or inflections in the field V or I, i.e. whenever there is high dV/dt or dI/dt - and that is rather very often, almost all the time.

A simple spectrum analysis of these inflections (FFT will do well) will show you which frequencies are produced. Part of that is the famous 'alternator noise' in audio (badly grounded systems, that is). Another part is RF noise. Same thing happens in ignition systems based on contact breaking - ever heard an old auto or scooter crackle your audio at a red light? Old cars with contact breaking ignition don't do that, right? That's 5 side shielding for you.

What challenge? Solenoids are comparatively benign, and are much easier to shield.

Originally Posted by Mpower

Any idea what kind of solenoids in used in the 2000 bar common rail injectors? ... IIRC the solenoids do not directly hold the fuel pressure.

No, they don't directly work against the high pressure - the pressure helps it lift the constricting pin very fast. And the power consumed is about 20W for a few milliseconds depending on the injection profile). Piezo ones consume even less.

[Sutripta]

Originally Posted by DerAlte

Look inside the alternator - there is a commutator which conducts current to the field coil, and that current is modulated to modulate the output voltage.

??
Regards
Sutripta

[vina]

Originally Posted by DerAlte

Errr... aah... Solenoids?

Enh? Cooling and phase delays?


Oooooh! I am sure a course in any B-school will enable you to look at the capitalist way of looking at business, the same capitalist way that has got the world modern electronics - everything from semiconductors to equipment.

Going by your economic principles, we wouldn't have seen Diesel Injection systems: development of electrically controllable injectors cost a few hundred million dollars over 20 years. And common rail injection systems started 60 years back. Surely you wouldn't have seen an opportunity there either?

As far as cooling is concerned, anyone who has done it at least once knows how simply and economically it can be done. To those who haven't, it is complex. Of course, those involved in insides of components don't often think at sub-assembly and system level. Just like a brick-maker does not think of walls or architecture.

Aren't these comments bordering on personal biases? How do you know I don't have a MBA? and what makes you think I'm working at component level?

I think you should read my posts again - I'm saying all of this is possible by not economical and there are more promising ways of doing things overall (a motor on each wheel) - what the hell is more capitalistic than telling you that a cool looking technology doesn't make sense due to economic reasons? And how do those involved in insides of components who don't often think at sub-assembly and system level give an argument that a different system may be the way to go?

Rgarding cooling - if it can be done easily and reliably then that is great. I don't believe the reliability part will be easy. The existing system (cam ) doesn't require cooling to prevent catastrophe of course, so that is +1 for reliability.


Look inside the alternator - there is a commutator which conducts current to the field coil, and that current is modulated to modulate the output voltage. High frequencies are produced when there are discontinuities or inflections in the field V or I, i.e. whenever there is high dV/dt or dI/dt - and that is rather very often, almost all the time.

I wish to know how much dI/dt are we talking about. dV/dt doesn't radiate and doesn't matter.

"All the time" is DC that doesn't radiate - I guess you know that.

Also being a "component level guy" I don't understand why do you need a commutator in a device that generates AC (and converts it into DC later using a diode bridge).

I would think that a dynamo might do that, I didn't know cars (or even scooters) use that still.


A simple spectrum analysis of these inflections (FFT will do well) will show you which frequencies are produced. Part of that is the famous 'alternator noise' in audio (badly grounded systems, that is). Another part is RF noise. Same thing happens in ignition systems based on contact breaking - ever heard an old auto or scooter crackle your audio at a red light? Old cars with contact breaking ignition don't do that, right? That's 5 side shielding for you.

OK - I wrote this may not be a problem, though there is a likelyhood, you say there definitely is a problem. thanks for making my point.

By the way, FFT is not needed a handheld spectrum analyser will do just fine for this purpose. And no, I never heard my radio crackle even when my father's Bajaj Chetak was idling nearby - they hardly had any shielding near the ignition coil so far as I remember.

What I do know is that even if these systems radaited, the amount of radiation depends not only on dI/dt but also on the dt in that equation and on how often they repeat and whether there is a pattern to that (ever heard of spread spectrum?)


What challenge? Solenoids are comparatively benign, and are much easier to shield.

It is not the solenoids that will radiate. It is the wire connecting the high frequency semiconductor switches to the solenoid. The problem is accute enough that Audio manufacturers demand flitering in class-D amplifiers driving 2W over 1m long cable. I'm sure your current levels are way higher than what they have.

And shielding has its own cost and reliability issues too.


No, they don't directly work against the high pressure - the pressure helps it lift the constricting pin very fast. And the power consumed is about 20W for a few milliseconds depending on the injection profile). Piezo ones consume even less.

So we get a number for power. If you can get me reasonable power estimate for the solenoid I can give you better calculations - after all whether you know about sub-assemblies or not, I do know my components well.

May be you need to look at some of the links I sent. Most of the claims I made are fully supported in those.


Regards
Vina

[vina]

Originally Posted by sindabad.sailor

BTW Vina, I had a problem few years back. The amplifiers for Exhaust temperatures were fitted on to exhaust receivers. Temperatures there used to be severe. Once i went there and burnt the sole of my safety shoes. Due to this intense heat the isulation of cables running from PT100 to amplifier used to burn away and these cables used to short with body causing erratic readings and engine slowdown.
These PT100 were supplied integral with special cables of specific resistence. Hence whenever I used to replace the grounded bare cables with high temperature cables from my store, the readings used to go hayway due to change in the resistence.
I know if I use 3 -wire loop instead of 2 wire loop, I can cancel the effect of resistence variation. However I am unable to remember how to go about 3 wire looping. Though this is more an electrical problem than electronics one, I hope you can help.

Rgds.

My honour to help you in this, and I hope this works.

In the attached picture, the top picture is the structure you have. With the stock cables with your PT100 sensor, R1 is constant and any delta(Rab) you get (after calibration) is coming almost entirely from the PT100.

If you replace the stock cables with the high temp cables then the R1 changes as well and the delta(Rab) = d(Rpt100) + 2*d(R1)

and since d(R1) is not something easily calibrates your readings go haywire.


If you use the bottom arrangement then all you need to do is instead of using delta(Rab) you use delta(Rdiff) = delta(Rab) - delta(Rbc)

then delta(Rbc) = 2*delta(R1) and delta(Rdiff) = delta(Rpt100) as you wanted it in the first place - do remember to calibrate it, though if original stock cable R1 was substantially constant then this would work fine.


EDIT: the bottom port is C, forgot to include in drawing.

[sudev]

Ahhhh even more intense engineering and application thereof.

Interesting. Professors please carry on. Poor Tanveer his thread is royally hijacked but I am sure he would be pleased with the direction(S) it is taking.

Fascinating.