[DerAlte]

Originally Posted by vina

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? ...

Oh my, touchy, aren't we? Offense is usually taken, and almost never intended! I have no intention of getting under your skin. Chill!

Originally Posted by vina

... (a motor on each wheel) ...

I get a feeling you are talking of electric motors at each wheel (when the main discussion here is about gasoline / diesel engines) - something that Toyota has achieved 10 years back? Otherwise if you meant conventional engines at each wheel, I don't see how that is a more economical solution.

Originally Posted by vina

... cool looking technology doesn't make sense due to economic reasons ... give an argument that a different system may be the way to go? ...

With only a speculation (not calculation) giving inference of 'high cost'? Not the right method, isn't it?

Originally Posted by vina

... I don't believe the reliability part will be easy. The existing system (cam) doesn't require cooling to prevent catastrophe of course ...

Reliability of cam-driven valves took decades and a lot of $$$. Reliability is not a 'fallout' or 'happening'.

The existing cam system lubrication doesn't cool? Hmm...

Originally Posted by vina

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

How do the magnitudes matter? Any dI/dt (and yes, dV/dt too - that's what starts the whole thing) will cause HF output - some of that is significant enough. EMT.

Originally Posted by vina

... "All the time" is DC that doesn't radiate ...

How does one understand a system whose voltage varies aperiodically with rapid V/I variation / spikes, as DC where f=0?

Originally Posted by vina

... 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 ...

The diode bridge is the "commutator". Sorry, my mistake (apologies, @Sutripta) - I meant the slip rings / brushes that supply current to the rotating field coils. Colloquially, these have also been called "commutator". The source of RF here is the contact point between brushes and slip rings.

Originally Posted by vina

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

Dynamos (like used on cycles) used permanent magnets as field. In the interest of regulating alternator output, the field current (hence field magnitude) is modulated by the regulator by varying field current.

Originally Posted by vina

... how often they repeat and whether there is a pattern to that (ever heard of spread spectrum?) ...

K.I.S.S.!!!

Originally Posted by vina

... And shielding has its own cost and reliability issues too....

There you go again!

Originally Posted by vina

... I can give you better calculations ...

Sure you can, but for what?

Originally Posted by vina

... after all whether you know about sub-assemblies or not, I do know my components well. ...

Tit for tat, kya? Bad practice, since you have no clue what I have done or I do, may be nothing at all! What you know or do, you have made amply clear, on the other hand. Relax, my friend.

[vina]

Originally Posted by DerAlte

Oh my, touchy, aren't we? Offense is usually taken, and almost never intended! I have no intention of getting under your skin. Chill!

I get a feeling you are talking of electric motors at each wheel (when the main discussion here is about gasoline / diesel engines) - something that Toyota has achieved 10 years back? Otherwise if you meant conventional engines at each wheel, I don't see how that is a more economical solution.

I'm talking about electric motors. Rest you have figured out. The technology has advantages going beyond engine efficiency. And no Toyota hasn't achieved it - they may have made a prototype - it is still and active area of research because of its own problems. Some of those are:

1. Each motor needs its own speed control based on which direction the vehicle is moving in, what is the terrain, whether there is any roll/yaw etc.
2. Smaller motors that can easily fit and also can do regenerative breaking.

With only a speculation (not calculation) giving inference of 'high cost'? Not the right method, isn't it?

I think in one of the posts here I did a computation on what kind of driver is required for the solenoid. The compared that with an audio driver. You can check that.

Reliability of cam-driven valves took decades and a lot of $$$. Reliability is not a 'fallout' or 'happening'.

The existing cam system lubrication doesn't cool? Hmm...

I agree. And I agree. How is this relevant? Any new technology is compared against the state of the art (not how we achieved the state of the art).

How do the magnitudes matter? Any dI/dt (and yes, dV/dt too - that's what starts the whole thing) will cause HF output - some of that is significant enough. EMT.

You need to brush up on FFT and antennas. dV/dt is irrelevant (and doesn't even start dI/dt - in brush-commutator arrangement you break the contact - forcing the current to change - that leads to dV/dt via dV/dt = LdI/dt).

Magnitude of dI/dt tells you how much EMI is generated.

How does one understand a system whose voltage varies aperiodically with rapid V/I variation / spikes, as DC where f=0?

You said "all the time" - without explaining. What did that mean?


The diode bridge is the "commutator". Sorry, my mistake (apologies, @Sutripta) - I meant the slip rings / brushes that supply current to the rotating field coils. Colloquially, these have also been called "commutator". The source of RF here is the contact point between brushes and slip rings.

Alternator is called alternator because it generates AC. There is no current reversal at all in the brushes and slip rings. The direction of the current remains constant. As far as changing the magnitude of that current is concerned - that happens very very slowly (less than 10Hz bandwidth) and there are no sharp discontinuities so dI/dt is always small - this can't cause much EMI.

Also you have a few things to read up on:

Commutator = an arrangement to change direction of the current ("commute") every cycle. Commutator (electric) - Wikipedia, the free encyclopedia

Rectifier = device to convert AC into DC. Alternators use rectifier NOT commutator (Alternator - Wikipedia, the free encyclopedia) - though the rectifier is caller commutator in the context of automobile Alternators because (read below)

Dynamos (like used on cycles) used permanent magnets as field. In the interest of regulating alternator output, the field current (hence field magnitude) is modulated by the regulator by varying field current.

K.I.S.S.!!!

What does "K.I.S.S." mean? Automotive dynamos of old times used split ring commutators and generated DC (without a rectifier - no semiconductors were available earlier, and later they were neither cheap nor reliable till the 70s)

A proper commutator will generate huge EMI (sometimes you could actually see arcing and the brush and ring life was limited - also this was a fire hazard) because every half cycle the direction of the current would change. For permanent magnet dynamos the ring was split such the direction of current reversed when the magnitude was near-zero, for electrically excited armature since the current provided was DC, high voltages (hundreds of volts) were used to reduce dI/dt in large dynamos and even in DC motors.

Regarding bicycle dynamo - that is an alternator (though called a dynamo) Hub dynamo - Wikipedia, the free encyclopedia


There you go again!

Sure you can, but for what?

For fine tuning my calculations on what kind of driver is required (and hence how much will it cost)

Tit for tat, kya? Bad practice, since you have no clue what I have done or I do, may be nothing at all! What you know or do, you have made amply clear, on the other hand. Relax, my friend.

I'm sorry about that.

Regards
vina

[racerdabba]

Guys!
Chill. This is a helluva interesting and Educating Thread,And please continue it as such.

This video is of a working Camless engine, built by my friends as their final year project.

YouTube - Camless engine

The engine is a 102cc Activa/Dio. The timing was done using a disc with contacts connected to a "old is gold" magnetic relay. The relay actuates the solenoids.

No electronics at all. The response time of the solenoids are bad, and so is the timing delay.The engine had rough idle, and set up after much carburetor tunings etc.Still never crossed 1900-2000rpm.
Nevertheless, very much worked!!

[vina]

Originally Posted by racerdabba

Guys!
Chill. This is a helluva interesting and Educating Thread,And please continue it as such.

This video is of a working Camless engine, built by my friends as their final year project.

YouTube - Camless engine

The engine is a 102cc Activa/Dio. The timing was done using a disc with contacts connected to a "old is gold" magnetic relay. The relay actuates the solenoids.

No electronics at all. The response time of the solenoids are bad, and so is the timing delay.The engine had rough idle, and set up after much carburetor tunings etc.Still never crossed 1900-2000rpm.
Nevertheless, very much worked!!

very nice video.

Can you let us know how much current/power the solenoids took?

Relays have problems you can glean from this video itself (arcing, slow response ...)

I don't know if your friends are done with it, but if they are still on it then they can improve the speed using semiconductor switches (similar to the ones used in household inverters) - MOSFET or Bipolar or IGBT any would do. That can let you improve the timings as well well as rpm.

[rpmx1000]

Originally Posted by anujmishra

Here you can see "Hybrid" mushroom cloud.

Unless I am much mistaken , that was a conventional explosion in a nuclear plant (fire can cause many things to explode, but I am not one to comment on a nuclear ignition, but just for all idiots' sake, let's get this right. You cannot put a flaming match on a pile of radioactive uranium and hope it goes 'boom' - the nuclear, mushroom cloud, way).This video was not of a nuclear one, not even a 'hybrid' mushroom cloud. I suppose you know you were joking.If there was even a hint of a nuclear explosion, that video would have never come out.

[vina]

Originally Posted by rpmx1000

Unless I am much mistaken , that was a conventional explosion in a nuclear plant (fire can cause many things to explode, but I am not one to comment on a nuclear ignition, but just for all idiots' sake, let's get this right. You cannot put a flaming match on a pile of radioactive uranium and hope it goes 'boom' - the nuclear, mushroom cloud, way).This video was not of a nuclear one, not even a 'hybrid' mushroom cloud. I suppose you know you were joking.If there was even a hint of a nuclear explosion, that video would have never come out.

I think Anuj was joking

nuclear explosion is not triggered by temperature or even shock. It is not a chemical reaction. It is triggered when you somehow get enough critical mass of rdioactive material togerher for long enough (several microseconds) to cause a significant fraction of it to undergo chain reaction.

[rpmx1000]

Originally Posted by vina

I think Anuj was joking

nuclear explosion is not triggered by temperature or even shock. It is not a chemical reaction. It is triggered when you somehow get enough critical mass of rdioactive material togerher for long enough (several microseconds) to cause a significant fraction of it to undergo chain reaction.

Yes, vina , I know that very well,thanks I've read my 9th-10th Std Physics too. I was just trying to correct such a perception if it ever existed, his post was bordering on that!

[vina]

Originally Posted by rpmx1000

Yes, vina , I know that very well,thanks I've read my 9th-10th Std Physics too. I was just trying to correct such a perception if it ever existed, his post was bordering on that!

I'm sorry.

BTW, Fukushima did explode due to radioactive materials (the hydrogen gas was generated by radioactive decay in the first place) - though the explosion was no hybrid (I don't know what that even means)

[anujmishra]

Originally Posted by rpmx1000

Unless I am much mistaken , that was a conventional explosion in a nuclear plant (fire can cause many things to explode, but I am not one...

Well rpmx, you are correct. I was just joking. But what was the reason of that explosion which resulted in radioactive materials passed on the air.

Uranium in rich form when processed in reactor produces lots of heat. As you already said you read in 9th, 10th standard books. Yes, to control such heat cooling system should be in place. Otherwise any kind of disaster will happen. It released radioactive material in air in Japan due to that. Nuclear explosion also releases radioactive material in atmosphere and it just not only produces "Mushroom Cloud".

I was just quoting that if some crash happened with miniature nuclear powered engine in car and radiator go bust then similar situation would arise.

I am really sorry for offtopic

[vina]

Originally Posted by anujmishra

I was just quoting that if some crash happened with miniature nuclear powered engine in car and radiator go bust then similar situation would arise.

I am really sorry for offtopic

Well may not off topic - A lot of early satellites launched by US and USSR alike were nuclear powered. they did not have entire reactors on them but a miniature plant generating power via its own radioactive delay (no chain reaction) was used. They used isotopes different from Uranium with relatively short half lives. They are very expensive but give excellent energy density. Also radiation increases a little, but in space radiation is already higher than on earth.

you can read up more here:

Atomic battery - Wikipedia, the free encyclopedia

[vina]

Originally Posted by vina

Well may not off topic - A lot of early satellites launched by US and USSR alike were nuclear powered. they did not have entire reactors on them but a miniature plant generating power via its own radioactive delay (no chain reaction) was used. They used isotopes different from Uranium with relatively short half lives. They are very expensive but give excellent energy density. Also radiation increases a little, but in space radiation is already higher than on earth.

you can read up more here:

Atomic battery - Wikipedia, the free encyclopedia

so if this can be in a car - then not just the timings and cam, the whole engine can be removed.

There are a few problems though (contamination if the isotopes are released, e.g. in an accident; proliferation - terrorists can make dirty bombs ...) apart from costs that make it impractical.

[DerAlte]

Originally Posted by vina

... dV/dt is irrelevant ... dV/dt via dV/dt = LdI/dt). ...

Perhaps this is a more relevant explanation & equation, no? You are talking of back-EMF, like that causing arcing in the relays in the video, which can be completely avoided by connecting a diode in reverse across the contact of the relay.

Originally Posted by vina

... You said "all the time" - without explaining. What did that mean?...

Originally Posted by vina

... Also you have a few things to read up on:
... Wikipedia, the free encyclopedia ...

Originally Posted by vina

... What does "K.I.S.S." mean?
... Wikipedia, the free encyclopedia

Since Wiki etc. seems to be your favorite knowledge source:
K.I.S.S. principle
"All the time"

Now, could we please get back to discussing something (anything) relevant to the thread topic "Camless and electronic timing", rather than meandering our way through electric motors and possibilities of nuclear reactors in cars and obviating petrol/diesel engines? That is seriously OT, so 'cease and desist', as they say.

[vibbs]

Interesting discussion this.
@ Sindbad.sailor It was interesting reading your posts. Myself being a marine engineer too and despite the fact that camless engines have been around for some time you are perhaps the first person i m interacting with who s been sailing on one.

Now this is off topic but since the discussion has already moved on to marine engines, i want to add a few points here. I saw the discussion on reversing of the engines and doubt being asked about the engines needing to be stopped before reversing. Most engines are normally directly coupled to a fixed pitch propeller except for a few ships having controllable pitch propellers.

So in all the ships with FPPs the engine has to be stopped for stopping the ship not just for reversing.

Since it is directly coupled to and FP propeller there is nothing like idling the engine like we normally have in our cars. Its like the car is perpetually in gear u start the engine when you want to move and stop the engine when you want to stop. Since you cant apply brakes on water we then have to reverse the engine and run it in opposite direction if we want the ship to stop before it overcomes the inertia and stops on its own. Normally this is done by providing the starting air in the reverse direction as to normal running which sindbad.sailor has already explained.

Since the forces involved are very high you dont give the reversing kick when the engine is running in ahead direction. Interlocks are provided for the safety part for the same. Although in emergencies you can give a reversing kick even when the engine is in the ahead direction though you never know what damage it could cause to the engine due to the high level of stresses induced in the components. Its like sacrificing the engine to save the ship.

But again it is only after giving the stop command. In a ship with the engine running at 87 to 90 rpm for quite some time even on giving the stop command and the fuel being cut off the engine will still keep on rotating in the same direction for sometime due to the inertia of the propeller. It is here when we give a reversing kick before the propeller stopping in case of crash stop. Not when the engine is firing in ahead direction. Reversing is always after stop command.

Sorry for going OT just wanted to add that most marine engines have to be stopped not only for reversing but also for stopping the ship and even in crash astern the stop command comes first.

[vina]

Originally Posted by DerAlte

Perhaps this is a more relevant explanation & equation, no? You are talking of back-EMF, like that causing arcing in the relays in the video, which can be completely avoided by connecting a diode in reverse across the contact of the relay.

You know, I'm not talking of back-emf. Also since the diode conducts (via breakdown - if the voltage is too large) putting a diode is a cheap but bad idea - nobody does it any more, and it'll not even solve the problem (diode will conduct- so the realy opening doesn't mean current stops).

and no the explanation of the equation is not relevant - you need to go into Maxwell's equations in details, derive wave equations (or find all that in a good book) and figure out that an accelerating charge radiates (nothing to do with voltage - an electron in motion radiates. This was a problem with Bohr's model of the atomic structure) - since dI/dt => accelerating charges there will be radiation (i.e. EMI) whether there is dV/dt or not.

You can cause dI/dt without causing dV/dt (that's what will happen if you put a diode in parallel with the relays) and radiation will still occur (though much less and at different frequencies)

Originally Posted by DerAlte

Since Wiki etc. seems to be your favorite knowledge source:
K.I.S.S. principle
"All the time"

Now, could we please get back to discussing something (anything) relevant to the thread topic "Camless and electronic timing", rather than meandering our way through electric motors and possibilities of nuclear reactors in cars and obviating petrol/diesel engines? That is seriously OT, so 'cease and desist', as they say.

If you check all the time in the link above - that says continuous - that is the definition of DC.

[DerAlte]

<Sigh> You should try and understand the Kabir doha:
Pothi padh padh jag mua, pandit bhaya na koye,
Dhai akhar prem ka, padhe so pandit hoye
'Prem' here represents worldly experience, without which one does not get wisdom - and that does not come from books. Get your nose out of books and go out and smell the coffee, buddy.

1. The diode you are pooh-poohing is called a quenching diode, and connecting that in reverse across the relay/contactor coil or the switching contact is a standard practice (will always be) in electrical panels. It safely prevents the back-EMF from producing an arc across the switching contact. Without this there will be ultimately a. insulator breakdown in the coil causing it to short and fail and b. erosion in the contact material of the switching contact

2. You seem to have found a sure-fire method of 'accelerating charge' and producing current without any voltage (sure, one can sit and move a soft iron core in and out of the solenoid coil perpetually to get that current without needing voltage).
Otherwise, wherever the brushes jump up and down on the surface imperfections of the copper rings, they cause first a disruption of the voltage being applied on the field coil (first dV/dt) causing back-EMF in the field coil (dI/dt caused, resulting in second dV/dt, -ive) which leads causes arcing (micro-arcing) which causes more dV/dt and dI/dt, all of which produce nasty RF noise. And one has the whole field coil as an antenna, though RF comes out of only the ventilation holes. Capisce? Now, could you please try to explain this to me with Maxwell's and other equations?

What perhaps you are not understanding is that when we are practically dealing with product engineering (whether in forward or in reverse), we are never trying to solve fundamental equations. At that time, we are only applying technology, which systematically creates building blocks by applying appropriate science, which has created and solved all the fundamental equations. If you are reverse-traversing the science->technology->engineering, we need to get the right reference points right otherwise we land up in an unintended state. I am sure you will not agree with this.

Originally Posted by vina

... If you check all the time in the link above - that says continuous - that is the definition of DC.

What would you call a signal whose magnitude continuously varies but aperiodically (cannot resolve fundamental sinusoid components / too many fundamental sinusoid components, like in white noise; possibly with DC bias)? DC? AC?