Author Topic: Ignition systems  (Read 6106 times)

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Online HighVoltage

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Re: Ignition systems
« Reply #25 on: October 01, 2021, 01:13:50 pm »
Modern coils are just HV generators, and will produce a high voltage the entire time the trigger signal is applied

I am not aware of such system.
Do you have an example of that setup?

A standard coil on plug is this type, 12V is applied all the time, there is a separate trigger pin. Search coil on plug and you'll see these types.
This system has been around for a very long time....
They can not "produce a high voltage the entire time", they work the same way as before and have to charge up the primary with energy before producing the high voltage at the output.

I am just developing a new ignition coil for an OEM.
The difference these days is that we have 30A primary current after only 100us of charge time.
And the secondary peak voltage must be >50kV, besides a few other crazy requirements.



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Offline SteveyG

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Re: Ignition systems
« Reply #26 on: October 01, 2021, 01:16:19 pm »
This system has been around for a very long time....
They can not "produce a high voltage the entire time", they work the same way as before and have to charge up the primary with energy before producing the high voltage at the output.

I certainly have some in the garage somewhere 5 pin with integral diagnostics, I'll see if I can dig one out later for disassembly, I think they were branded Haldex, but I can't remember off-hand.
« Last Edit: October 01, 2021, 01:22:11 pm by SteveyG »
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Online HighVoltage

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Re: Ignition systems
« Reply #27 on: October 01, 2021, 01:20:45 pm »
A few years ago, the 2 extra pins have been used to feed the OBD2 system.

These days the "intelligent" feedback information is all carried over one input signal wire.

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Online Circlotron

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Re: Ignition systems
« Reply #28 on: October 01, 2021, 01:39:37 pm »
I am just developing a new ignition coil for an OEM.
The difference these days is that we have 30A primary current after only 100us of charge time.
And the secondary peak voltage must be >50kV, besides a few other crazy requirements.
How much energy? Physically small coils don't give you much to work with. And why such high currents and short charge times? What's wrong with say 10A and 3mS? Less time for I2R dissipation in the primary?
 

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Re: Ignition systems
« Reply #29 on: October 01, 2021, 02:16:12 pm »
General definition would be the "standard ignition coil" as the large cylinder type which would feed the distributor, not a COP type.

Looks like there are various COP configurations though. I think only the 3 pin coils are the type with just a transistor inside.

by standard I mean like it has been for decades, a coil and a switch to charge the primary. The coil is just on the plug and the switch is a transistor integrated in the coil. I don't think any one has used distributors in a very long time. The reliabilty issue and mechanics to drive it is probably expensive compared to a few extra coils.

Some coils are 3-4-5 pins, sometimes it is just extra grounds
 

Online HighVoltage

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Re: Ignition systems
« Reply #30 on: October 01, 2021, 02:16:20 pm »
I am just developing a new ignition coil for an OEM.
The difference these days is that we have 30A primary current after only 100us of charge time.
And the secondary peak voltage must be >50kV, besides a few other crazy requirements.
How much energy? Physically small coils don't give you much to work with. And why such high currents and short charge times? What's wrong with say 10A and 3mS? Less time for I2R dissipation in the primary?
Almost 150 mJ Energy in the sustained spark.
Short charge time to keep the windings cold
30A primary current to get about 300 mA peak current in the spark.
And ion measurement is built in as well.
There is not much room for error in the dwell time.

And you can not trigger these coils with a typical ON signal.
1us after the ON signal starts, a signature is transferred to the coil to really turn ON.
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Offline SeanB

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Re: Ignition systems
« Reply #31 on: October 01, 2021, 02:52:31 pm »
Going to guess that is for multipulse ignition, for ultra lean operation, so you will have enough spark to ignite the fuel mix, even if the plug area is transiently non combustible, you have enough high energy sparks that the lean mix will strike before TDC and complete combustion to a large degree.

I helped my father install high energy inductive ignition, that used a vane that blocked an optical sensor, that then triggered a low resistance (IIRC under 0,8R primary) coil, to provide the ignition pulse. Had to use inductive wound Bougicord leads, as the carbon ones basically melted, and spark plugs had to be special Lodge ones, as the other brands like NGK or Champion would only last a week before misfiring. But was able to run really lean, and provide extra power at the top end of the RPM, even if your 10 000km service was change 4 spark plugs, rotor and distributor cap, as they would all be badly eroded, and not likely to make another service.

Big difference, made it a stealth supercar, well capable of beating the common sports models, 3 series BMW, low end Porsche, VW 1st generation GTI. None of them thought an Alfasud 1.5l was capable of beating them stop to stop, or at top end. He kept the stock exhaust as well, so it did not sound any different. Just used to eat gearbox synchros, and brake disks.
 

Offline paulcaTopic starter

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Re: Ignition systems
« Reply #32 on: October 01, 2021, 03:25:52 pm »
On coils....  related, sort of, but I read something suggesting that on motorcycles, the engine has a stator and a rotor for generation... like 99% of them do,  that's our alternator, however they claimed that on some bikes at least, they use different sized coils and power different things from each coil.

So there was a larger, heavier coil for powering the ignition, a smaller coil for powering lights and another smaller one, gone through a rectifier for running electronics.  Oh and a single neutral.  It's like a 6 phase generator with the phases split and used in singles or pairs for different sub-systems.  It makes sense to a degree, why pump all the current for the ignition at 17,000rpm through the rectifier and then use it t generate high voltage, reducing the size of the wiring and the rectifier.... and not broadcasting that ignition RF through out the bike, but keeping it close to the engine.

I'm just not sure how true this is or how common it is.

This video and section 1:33:
https://youtu.be/mdOJ717PKRc?t=93
« Last Edit: October 01, 2021, 03:30:54 pm by paulca »
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Online langwadt

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Re: Ignition systems
« Reply #33 on: October 01, 2021, 04:40:36 pm »
Going to guess that is for multipulse ignition, for ultra lean operation, so you will have enough spark to ignite the fuel mix, even if the plug area is transiently non combustible, you have enough high energy sparks that the lean mix will strike before TDC and complete combustion to a large degree.

I helped my father install high energy inductive ignition, that used a vane that blocked an optical sensor, that then triggered a low resistance (IIRC under 0,8R primary) coil, to provide the ignition pulse. Had to use inductive wound Bougicord leads, as the carbon ones basically melted, and spark plugs had to be special Lodge ones, as the other brands like NGK or Champion would only last a week before misfiring. But was able to run really lean, and provide extra power at the top end of the RPM, even if your 10 000km service was change 4 spark plugs, rotor and distributor cap, as they would all be badly eroded, and not likely to make another service.

Big difference, made it a stealth supercar, well capable of beating the common sports models, 3 series BMW, low end Porsche, VW 1st generation GTI. None of them thought an Alfasud 1.5l was capable of beating them stop to stop, or at top end. He kept the stock exhaust as well, so it did not sound any different. Just used to eat gearbox synchros, and brake disks.

sound like a story that gets better every time it is told, adding lots of spark energy isn't going to magically add sginificant power and running lean definitely isn't

 

Online HighVoltage

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Re: Ignition systems
« Reply #34 on: October 01, 2021, 04:44:40 pm »
Going to guess that is for multipulse ignition, for ultra lean operation, so you will have enough spark to ignite the fuel mix, even if the plug area is transiently non combustible, you have enough high energy sparks that the lean mix will strike before TDC and complete combustion to a large degree.


Yes, Multi Pulse is another reason to have an ultra fast charge time.

To get the combustion more stabilized, the spark current must be increased.
Especially for lean burn mixtures, a higher spark current is required.

Spark duration has become secondary in modern systems and long spark duration are a relic in the past.

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Offline Benta

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Re: Ignition systems
« Reply #35 on: October 01, 2021, 04:58:21 pm »
Going to guess that is for multipulse ignition, for ultra lean operation, so you will have enough spark to ignite the fuel mix, even if the plug area is transiently non combustible, you have enough high energy sparks that the lean mix will strike before TDC and complete combustion to a large degree.

Interesting. Never heard of this before.
I know of multiple pulse direct injection (FSI, TSI, TFSI, whatever they like to call it), where only the immediate area around the spark plug has stoichiometric mix and the rest is lean.

Please give an example of a production engine that uses multipulse ignition.

 

Offline LaserSteve

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Re: Ignition systems
« Reply #36 on: October 01, 2021, 05:42:30 pm »
Yes,

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Offline bdunham7

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Re: Ignition systems
« Reply #37 on: October 01, 2021, 06:09:18 pm »
Please give an example of a production engine that uses multipulse ignition.

I've seen both Ford and BMW products that use multistrike.  Ford in particular has been using it for a decade-plus now.
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Offline james_s

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Re: Ignition systems
« Reply #38 on: October 01, 2021, 07:36:07 pm »
sound like a story that gets better every time it is told, adding lots of spark energy isn't going to magically add sginificant power and running lean definitely isn't

Lean burn is done for fuel economy, not power. It has been a common technique for decades, lean out the mixture as much as possible during light load when it is less likely to ping and the total heat energy is not enough to burn valves.
 
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Offline james_s

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Re: Ignition systems
« Reply #39 on: October 01, 2021, 07:45:46 pm »
Was watching a video about Harley Davidsons.  They really are a pile of junk.  The engineering is many places is, well, really, really poor.  It's not even like they evolved and adapted with the times/tech, they don't/didn't.  And.... are now dieing.

They used a single crank pin for 2 pistons, not because that was a good choice, but because they couldn't be bothered to have two crank pins, balance the engine and have a sane firing interval.  They use a 45* firing interval as a result.  So BANG, BANG................ BANG BANG.  Then because they were cheap skates they decided that per-cylinger ignition was too much effort so they just fire both plugs.  This results in the BANG, BANG, POP.....  The POP is caused by the engine being so poorly made there is enough combustable exhaust gas in the exhaust strike to ignite!

With an unbalanced crank, the bike shakes violently when idleing.  So they mounted the engine on rubber.... with a cheap and nasty steel frame that flexed.  Resulting in many deaths caused by death wobble oscilations.  They added a counter balance (to fix the unbalanced pistons) such that the vibration of the unbalanced mass was forward/back, not up/down, hence the shaking.  The only saving grace is that when moving, some of that insane vibration is muted by the road motion.

I think the video making summed it up by saying, Harley's, you either get them or you don't.  I don't.


Yes, it's clear that you don't. They are not really my cup of tea either, but I do appreciate that they are one product that has had the sense to not mess with a successful formula. A modern Harley is very similar to one that was made 20, 40 or even more years ago and that is a great part of the appeal to people who buy them. I do love the sound personally, and I like the fact that it's essentially a slice of a radial engine. A friend of mine is a motorcycle enthusiast, he has several Japanese sport bikes, an electric bike and a Harley, he rides the latter the least, but he has said that riding it has a very manly feel and he loves it for a cruise on a nice day. It's an iconic vintage classic that you can still buy new.

If Harley changed their design to be more modern, they would lose what makes them unique and they would completely alienate their entire customer base while then trying to compete in a market that is saturated by other brands, it would be the dumbest move they could possibly make. They'd lose their existing customers and you still wouldn't buy one.
 

Offline Benta

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Re: Ignition systems
« Reply #40 on: October 01, 2021, 08:33:30 pm »
Please give an example of a production engine that uses multipulse ignition.

I've seen both Ford and BMW products that use multistrike.  Ford in particular has been using it for a decade-plus now.

This does not sync with my knowledge. AFAIK, only Mercedes is (half-heartedly) following this track lately. Everything else is aftermerket/tuning accessories.
« Last Edit: October 01, 2021, 08:37:11 pm by Benta »
 

Offline bdunham7

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Re: Ignition systems
« Reply #41 on: October 01, 2021, 10:10:06 pm »
This does not sync with my knowledge. AFAIK, only Mercedes is (half-heartedly) following this track lately. Everything else is aftermerket/tuning accessories.

I've seen, tested and measured these systems and I assure you they are common in at least Ford products.  You can just google 'Ford multistrike' to read about it.  This system famously killed a Ford engineer a while back--it turns out that the rapid succession is much better at stopping the heart than single pulses.
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Offline BrokenYugo

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Re: Ignition systems
« Reply #42 on: October 01, 2021, 10:33:16 pm »
Going to guess that is for multipulse ignition, for ultra lean operation, so you will have enough spark to ignite the fuel mix, even if the plug area is transiently non combustible, you have enough high energy sparks that the lean mix will strike before TDC and complete combustion to a large degree.

I helped my father install high energy inductive ignition, that used a vane that blocked an optical sensor, that then triggered a low resistance (IIRC under 0,8R primary) coil, to provide the ignition pulse. Had to use inductive wound Bougicord leads, as the carbon ones basically melted, and spark plugs had to be special Lodge ones, as the other brands like NGK or Champion would only last a week before misfiring. But was able to run really lean, and provide extra power at the top end of the RPM, even if your 10 000km service was change 4 spark plugs, rotor and distributor cap, as they would all be badly eroded, and not likely to make another service.

Big difference, made it a stealth supercar, well capable of beating the common sports models, 3 series BMW, low end Porsche, VW 1st generation GTI. None of them thought an Alfasud 1.5l was capable of beating them stop to stop, or at top end. He kept the stock exhaust as well, so it did not sound any different. Just used to eat gearbox synchros, and brake disks.

sound like a story that gets better every time it is told, adding lots of spark energy isn't going to magically add sginificant power and running lean definitely isn't

Definitely a bit of a "bigger fish" story (though a tuned up Alfasud outrunning a stock Mk1 GTI or 3 series BMW is certainly well within the realm of plausibility), but there is some truth to it. The big deficiency of points ignition is you have a dwell angle energizing the coil, not dwell time, so as revs climb at some point you aren't closing the points long enough to saturate the coil and ignition energy falls off. This is where "dual point" distributors came in, by staggering a pair of rubbing blocks (the cam that operates the points) and points a longer dwell better suited to high RPM operation could be achieved with realistic rubbing block geometries.
 

Online langwadt

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Re: Ignition systems
« Reply #43 on: October 01, 2021, 11:19:40 pm »
Going to guess that is for multipulse ignition, for ultra lean operation, so you will have enough spark to ignite the fuel mix, even if the plug area is transiently non combustible, you have enough high energy sparks that the lean mix will strike before TDC and complete combustion to a large degree.

I helped my father install high energy inductive ignition, that used a vane that blocked an optical sensor, that then triggered a low resistance (IIRC under 0,8R primary) coil, to provide the ignition pulse. Had to use inductive wound Bougicord leads, as the carbon ones basically melted, and spark plugs had to be special Lodge ones, as the other brands like NGK or Champion would only last a week before misfiring. But was able to run really lean, and provide extra power at the top end of the RPM, even if your 10 000km service was change 4 spark plugs, rotor and distributor cap, as they would all be badly eroded, and not likely to make another service.

Big difference, made it a stealth supercar, well capable of beating the common sports models, 3 series BMW, low end Porsche, VW 1st generation GTI. None of them thought an Alfasud 1.5l was capable of beating them stop to stop, or at top end. He kept the stock exhaust as well, so it did not sound any different. Just used to eat gearbox synchros, and brake disks.

sound like a story that gets better every time it is told, adding lots of spark energy isn't going to magically add sginificant power and running lean definitely isn't

Definitely a bit of a "bigger fish" story (though a tuned up Alfasud outrunning a stock Mk1 GTI or 3 series BMW is certainly well within the realm of plausibility), but there is some truth to it. The big deficiency of points ignition is you have a dwell angle energizing the coil, not dwell time, so as revs climb at some point you aren't closing the points long enough to saturate the coil and ignition energy falls off. This is where "dual point" distributors came in, by staggering a pair of rubbing blocks (the cam that operates the points) and points a longer dwell better suited to high RPM operation could be achieved with realistic rubbing block geometries.

sure if the ignition system is marginal upgrading it will help, but there's no point is going to plug melting levels

amazing how long it took before they figured out an extra coil and wasted spark was smarter than all the distributor nonsense
 

Online Circlotron

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Re: Ignition systems
« Reply #44 on: October 02, 2021, 09:26:30 am »
Probably one of the driving forces for getting rid of the distributor was simplifying engine assembly on a production line. Now no need to get it all synced up. Just attach all the parts and it is ready to run.
 

Online Circlotron

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Re: Ignition systems
« Reply #45 on: October 02, 2021, 11:59:35 am »
Going to guess that is for multipulse ignition, for ultra lean operation, so you will have enough spark to ignite the fuel mix, even if the plug area is transiently non combustible, you have enough high energy sparks that the lean mix will strike before TDC and complete combustion to a large degree.


Yes, Multi Pulse is another reason to have an ultra fast charge time.

To get the combustion more stabilized, the spark current must be increased.
Especially for lean burn mixtures, a higher spark current is required.

Spark duration has become secondary in modern systems and long spark duration are a relic in the past.
With older engines at least, long spark duration was considered desirable.
What size plug gap is your new coil meant to be used with, and what is present day thinking on this?
 

Online HighVoltage

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Re: Ignition systems
« Reply #46 on: October 02, 2021, 12:18:27 pm »
With older engines at least, long spark duration was considered desirable.
What size plug gap is your new coil meant to be used with, and what is present day thinking on this?

Yes, you are correct, it was desired but why?
We always believed this myth. But University research out of the early 80s has shown that this is not correct.

The longest spark duration I had measured was 3 ms
Imagine an engine running at 6000 RPM = 100 Hz = 36 degree crank angle / ms
So, even a 1ms long spark would last for 36 degree crank angle.

Lets say that same engine has a spark advance of 30 degree before TDC
If you retard this spark advance only a few degree, the engine looses power dramatically.
Only the first few 100 us are responsible for a good ignition process.
You can force a long duration spark to stop at shorter duration and it makes no difference for the engine.

Even in the old days, with old style ignition systems it was the case.
Porsche had a stock CDI in some 911 engines with 500us spark duration and they had full power and no problems. At the same time, GM had the HEI with over 2ms spark duration.
I think the inductive system got stronger and stronger with higher currents on the primary and automatically the secondary windings and the secondary inductance increased. And because of the large secondary L, the long spark duration followed as a consequence.

On the new coils, the spark gab will stay at 0.8 mm.
One important aspect is the ion measurement across the spark gap and the analysis for each spark.
There is more software in a modern coil these days as hardware. :-DD
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Online themadhippy

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Re: Ignition systems
« Reply #47 on: October 02, 2021, 01:11:14 pm »
Quote
On coils....  however they claimed that on some bikes at least, they use different sized coils and power different things from each coil.

I'm just not sure how true this is or how common it is.
don't know about modern bikes,but it was certainly true on the  some of the bikes  i had in the past.On my ole z200 it came in handy to get the thing home when the cam bearing started to wear out,turning on high beam made the engine work harder,putting more tension on the timing chain.
 

Offline Benta

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Re: Ignition systems
« Reply #48 on: October 02, 2021, 02:42:11 pm »
Quote
On coils....  however they claimed that on some bikes at least, they use different sized coils and power different things from each coil.

I'm just not sure how true this is or how common it is.
don't know about modern bikes,but it was certainly true on the  some of the bikes  i had in the past.On my ole z200 it came in handy to get the thing home when the cam bearing started to wear out,turning on high beam made the engine work harder,putting more tension on the timing chain.

??? Your magneto was on the cam shaft? What kind of bike was this? The ones I know of have it on the crank shaft.
 

Online themadhippy

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Re: Ignition systems
« Reply #49 on: October 02, 2021, 03:58:50 pm »
Quote
Your magneto was on the cam shaft? What kind of bike was this? The ones I know of have it on the crank shaft
no,the cam bearing was worn,causing the timing  chain  that drove the points to go slack ,putting more load on the engine, by turning on the headlights , took enough slack out to get me home.I discovered the "cure" when i hit the indicators to pull over as the engine was dying and dam thing started running again,turning  off the indicators  and the engine started to die.
 


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