Lasers could replace spark plugs in car engines

[Lashout_UK]

Similar to the transition from dizzys and other spinning bits of metal to ECUs?
It's progress gonna happen isn't it.

Because that offered distinct benefits at a relatively cost-effective price - and I refer you to my previous statement, that kind of equipment is easy to diagnose and test. These are not.

Again, like I say in my post, it's something that may eventually happen, but not for any time yet.

This idea's been around for at least five years - so it's still in its infancy.

That assumes it can focus when covered in soot and petrol...

Why would focusing be an issue? Presumably all the focusing is done in the laser itself, what their using is the beam?

 

[BigglesPiP]

Is there anything stopping someone from taking one out of a car and using it as a weapon?

Same applies to spark plugs...

Could tie a bit of string to it and hit you, could use an old Anglia's coil to give you a nasty jolt, could use a modern 32A coil to kill you...

 

[Lashout_UK]

Because that offered distinct benefits at a relatively cost-effective price - and I refer you to my previous statement, that kind of equipment is easy to diagnose and test. These are not.

Again, like I say in my post, it's something that may eventually happen, but not for any time yet.

This idea's been around for at least five years - so it's still in its infancy.

That assumes it can focus when covered in soot and petrol...

Why would focusing be an issue? All the focusing is done in the laser itself, what they're using is the beam? The lens/glass will self-clean with every pulse (or they can additionaly fire it on the exhaust stroke to clear it).

 

[Lashout_UK]

In fact the idea's been around since 1978 - that says something

 

[BigglesPiP]

Why would focusing be an issue? All the focusing is done in the laser itself, what they're using is the beam?

The laser light has to come from somewhere and converge on a point.

What if the somewhere it comes from is covered in petrol? Petrol is a liquid and can refract light, so can affect focus. Can it get hot enough to evaporate all the fuel if it can't focus? You don't need a lens to be scuppered by Vaseline.

I'm not violently opposed to laser ignition, just playing devils advocate...

 

[tigerstyle]

Because that offered distinct benefits at a relatively cost-effective price - and I refer you to my previous statement, that kind of equipment is easy to diagnose and test. These are not.

When they are mass produced price won't be an issue, or when legislation forces them to be used for emissions price won't be an issue (along with production)

Also, easy to diagnose and test once you've shelled out for the suitable equipment+training necessary, take a modern car back in time 30 years and any mechanic wouldn't know how to fix it, they could change the sparkplugs though Repeat the process in anther 30 years and they'd no doubt be chancing your laser units too

 

[rypt]

One of the advantages is also going to be the ability to use multiple lasers that will "focus" on a point and thus you can control exactly where combustion begins and can potentially do is so that it begins in multiple places (and thus even perhaps start to control knock)

 

[Lashout_UK]

The laser light has to come from somewhere and converge on a point.

What if the somewhere it comes from is covered in petrol? Petrol is a liquid and can refract light, so can affect focus. Can it get hot enough to evaporate all the fuel if it can't focus? You don't need a lens to be scuppered by Vaseline.

I'm not violently opposed to laser ignition, just playing devils advocate...

I don't think it's an issue - after all they're just pulsing a laser that's set to focus somewhere in the combustion chamber, creating a plasma spark or a thermal reaction. I don't know the ins and outs but presumably they've got enough power to overcome any of the environmental conditions in the chamber itself - and hence, probably, why the mention using two distinct beams in the current article (besides creating a more even flamewall, it gives them a degree of redundancy if one doesn't cause ignition).

So little energy (on a laser scale) is required to light up an air/fuel mixture that even if it was obscured or scattered it'd probably still function with ease - and without the need for any precise focusing. If it doesn't light first time around, just fire the laser several times - job's a goodun

 

[Lashout_UK]

When they are mass produced price won't be an issue, or when legislation forces them to be used for emissions price won't be an issue (along with production)

Well, lasers on this scale aren't exactly costly to make anyway (although one older article I read ages ago did quote a figure of £350 a plug, hehe) - but if the idea's been around for 33 years you have to wonder what the drawback is. Potentially a case of not enough efficiency gain per % cost increase? I don't think they have any issues with endurance, vibration or cleaning.

Obviously emissions is becoming a key thing these days but with manufacturers already getting to the point where they can build sub 100g/km of CO2 emitting engines using conventional single spark plugs (not even doubles) then there'd have to be some substantial gains available to make them consider replacing such well-established tech, even more so if it costs more.

Also, easy to diagnose and test once you've shelled out for the suitable equipment+training necessary, take a modern car back in time 30 years and any mechanic wouldn't know how to fix it, they could change the sparkplugs though Repeat the process in anther 30 years and they'd no doubt be chancing your laser units too

It's only really the electronics that would cause them grief, as the majority of mechanical systems have remained effectively the same. although admittedly electrical failures tends to account for about 60% of failures these days

Take another car back in 30 years and they probably really would be stumped, because it'd most likely be electric, made entirely of composites and contain nothing servicable at all

I don't think many garages would shell out for the equipment or training - they'll just change them, as it'd probably be simpler and cheaper. If that doesn't fix it then they'll start diagnosing other issues....

 

[Dogbreath]

Well, lasers on this scale aren't exactly costly to make anyway (although one older article I read ages ago did quote a figure of £350 a plug, hehe) - but if the idea's been around for 33 years you have to wonder what the drawback is.

The ability to create the kind of power required for this application in a small, low cost and rugged form has only very recently been available. 33 years ago you'd have needed a CO2 laser or similar, which are large, expensive, fragile and have all sorts of complex drive requirements. Now a laser diode can be used to pump sufficient power into the gain block within the spark plug.

 

[Lashout_UK]

I'd thought it would most likely have something to do with that - I appreciate that it's come a long way.

I guess there's the potential for a system that uses one master laser, like a coil, and fibreoptics to carry the pulses to the revelant cylinder? I don't know how well fibreoptics would stand up to punishment like that, though?

 

[Dogbreath]

The fibres themselves can be made very tough. Not sure how useful a single master laser would be, since you'd have to switch it between different sparks plugs which would be more complex and likely more expensive than just having multiple laser sources, though a wasted spark system could potentially be used I suppose. High power laser diodes are now relatively cheap to manufacture, and large volume demand from the automotive sector would only drive prices lower.

The bit I would expect to require the most development is the plug itself which holds the ceramic gain medium. This is going to need to be able to run at high temperatures for long service intervals whilst handling very high peak optical powers. In traditional gain materials this would cause rapid degradation.

I'm quite interested in this as the company I work for make lasers for all sorts of applications, e.g. data/telecoms, medical, industrial etc.

 

[5abr3]

The issue of fibre optics is designing the cable to carry the frequency of light generated at a high enough power - and standard fibre optic cables aren't optimised for running in engine bay conditions. All the automotive fibre optics I am aware of (admittedly for ICE applications) are rated to less than half the temperature rating for a main engine loom.

Development/R&D on the fibre optic 'switch gear' needed to route the signal as well as the cable design itself would not be cheap as no connectors or cable exist to the temperature rating and none of the connector designs are suitable for confined engine bay spaces. Applying the connector ferrule to the fibre optic cable could also be problematic as these are generally laser welded and if the cable is extremely fine this makes the laser welding more difficult and the cable more prone to vibration induced damage. There is also a risk of increased attenuation through reguarly flexing the cable which would also play around with the resulant output frequency of the light and this could mean a drop in efficiency.

 

[helpimcrap]

makes sense - laser is pure energy.

 

[Dogbreath]

The issue of fibre optics is designing the cable to carry the frequency of light generated at a high enough power - and standard fibre optic cables aren't optimised for running in engine bay conditions. All the automotive fibre optics I am aware of (admittedly for ICE applications) are rated to less than half the temperature rating for a main engine loom.

The fibers used for audio SPDIF interfaces are cheap, multimode, plastic fiber which is why they have such low temperature ratings. To carry high power they would be using glass fibers; I wouldn't expect this to be a sticking point in the development.

 

[5abr3]

The fibers used for audio SPDIF interfaces are cheap, multimode, plastic fiber which is why they have such low temperature ratings. To carry high power they would be using glass fibers; I wouldn't expect this to be a sticking point in the development.

Glass suffers from surface fractures when under the heavy and constant vibrations experienced in engine conditions which causes the light to be randomly defracted through these cracks - which is one of the reasons (other than cost) that we use plastic for ICE. Granted this is primarily a data corruption concern but it will cause a drop in power for this application.

Anyway, I'm not paid to do the cable research and I'm sure one of the big 5 cable companies (and one of the big connector companies, probably Tyco) will pick it up if they see a big enough market and think that they might be able to make a cheaper cost solution than 4 laser-plugs. The switching on channels would be my primary concern after coming up with an affordable cable, as the lengths of cable used will be nothing compared to the amount used for 'general' applications by most applications which will not help the price in the slightest.

The larger focus for fibre cable manufacturers is fibre to the home from what I recall reading and I don't recall seeing any high temperature-high vibration cycle rated automotive cables in the works catalogue though there might be some in the industrial cables catalogue.