Will faraday effect work THROUGH aluminum? For power generation

Factual Questions
1

Imagine a piston in an engine, a normal IC engine or even one of the weird ones like opposed-piston

now imagine that in the middle of the piston a magnet is mounted, so as to be part of the piston

now imagine you wrap the piston bore/block with copper wire coils a la a generator. That is, on the OUTSIDE of the aluminum piston bore, so the aluminum is “in the way” between the magnet and the coils

will a current still be induced in the coils? Or will the eddy currents that will get induced in the aluminum bore walls interfere and reduce the strength of the induced current in the copper coils on the outside? That is, does the aluminum “Get in the way”

How about if the engine block is steel/iron, which of course is ferromagnetic?

The idea of course is obvious, to create an electro-mechanical engine where the electric part comes directly from the engine, rather than by transmitting power mechanically through a shaft

2

Whether the material is ferromagnetic or not is irrelevant. What’s relevant is whether it’s conductive, and aluminum is. It’s not as conductive as copper, of course, but it’s still conductive enough that any aluminum cylinder thick enough to be practical for an internal combustion engine is going to let only a negligible amount of the magnetic power through to the copper.

3

It’s not quite the same thing, but a lot of small engines (like on lawnmowers) will have magnets on the flywheel which then generate electricity as they pass by coils mounted to the non-rotating part of the engine. While the mechanical power to generate the electricity is conducted through the crankshaft to the flywheel, this arrangement does not add any extra mechanical parts to the engine other than the magnets, since the shaft and the flywheel already need to be there for the engine just to function.

If you are trying to reduce weight and eliminate extra mechanical bits by getting rid of part of the shaft and/or the pulleys that drive the generator/alternator in a typical engine, this is one solution to that which actually works.

4

Suppose engine block is non-conductive (eg glass or unobtainium).

Would scheme to extract electricity directly from reciprocating pistons (in addition to at least enough rotational mechanical energy to keep engine running) be likely equivalent to simply attaching a generator (alternator), as we currently do?

I’m sure it would be harder to repair, but with less moving parts, maybe less likely to need it.

5

If the engine block is non-conductive, it’ll work, though it would take a better engineer than me to say whether it’d be practical.

6

Engine blocks have been made out of carbon fiber composites. The costs were extremely high and I’ve not heard of one put into production. But I think you see the problem, it makes the engine more complex and expensive and probably is no more efficient than using a conventional generator or alternator. Also the cylinder walls need sufficient strength to withstand combustion so there’s some less than ideal minimum distance between the magnet and the coils. And then on top of that the magnet will weaken as it gets hotter.

It is an interesting idea though, and the basis for some proposed Sterling engine generator designs.

7

magneto; it’s there to trigger the ignition coil which fires the spark plug.

it’d be worse, IMO.

  1. for a generator to be “efficient,” you need the field to be as closely coupled to the stator as possible. if you look inside an electric motor or generator, the rotor (armature for a motor, field for an alternator) has very little clearance to the coils (field for a motor, stator for an alternator.) The thickness of the cylinder wall alone would reduce the power output sharply.

  2. magnets are heavy, yo. You’d be adding a lot of reciprocating mass which would reduce the maximum operating RPM of the engine.

  3. “permanent” magnets lose strength as they heat up; and some of that loss of magnetic strength is irreversible. Neodymium (rare earth) magnets will start to permanently lose strength above 180F (in-cylinder temps are easily higher than this) and will completely lose their magnetism above about 600F.

  4. Alternators don’t really fail all that often anyway.

8

OK, but why would it stop it exactly? My understanding is that the moving magnet will induce a current in the cylinder bore which would then create a changing magnetic field which would then induce a current in the outside coils

I’m just thinking that because a solid bore is a sub-efficient design to “catch” the changing magnetic fields, and the thickness of the bore, that the induced field in the coils would be significantly reduced compared to other traditional magnet-rotor-coil combinations

anybody got the physics deets?*
*details

9

Eh, my OP train of thought is apparently a non-starter because of the coil distance and the curie temperature issues, so I’ll tell you guys the idea

I’ve always been convinced that there’s some geometry for an engine that no one’s yet thought of that would improve the efficiency of IC engines, or some way to do fuel-based motive power generally.

Early on, I wondered about the idea of tip jets, but with fuel pumped in and compressed air coming in from a centrifugal compressor/turbocharger, and with the jets tilted down slightly to create lift. That was just part of thinking about rotary type engines generally.

The following idea is an obvious one when thinking of rotary engines, and a friend of mine said he even thought of something like it once: How about pistons that spin in a circular bore? There’s no cylinder head for the gas to push against, but that could be dealt with rotating mechanisms that block the bore at various points, and when necessary a cam spins them to open a through-pass for the pistons to pass through. Dealing with charges of compressed air vs. power stroke vs. exhaust stroke would be weird, but there are obvious solutions; have two of these mechanisms stacked and rotating counter to each other, and the compressed air from one compression stroke on one side could be passed to the about-to-happen power stroke on the other rotor.

It’s all just obvious stuff playing with rotary geometries in your head. It’d make for a weird engine, but it’d still be workable.

One downside, I was thinking, is that on the inner, uhhhh, “race” of the engine, there’d have to be a large cricular bearing so that the pistons travel motion could be transferred to a central shaft while keeping the cylinder bore (which, again, is a big circle) sealed. That’s a pretty big flaw, too much surface area bearing.

So then I was thinking, “OK, so how do we get rid of that?” answer is “By not transferring the power to the outside world mechanically through a shaft, and use something else”
So that got me thinking on how you can transfer the power hydraulically through some sort of pumping, and things like fluid bearings to reduce friction, or eletcrically.

The electrical solution intrigued me, because in the machinist class I’m taking, there’s this one guy who’s a genius with cars, he is/used to be a mechanic. He told me about how just some splashing oil can suck like 15 mpg out of an engine, or how ball bearings to join a piston rod to the crankshaft is way way more efficient, but it just doesn’t last. In general, the thing about engines is that all the mechanisms that make all the timing and valving and stuff work suck so much power. So, in theory, and electro-mechanical engine could get rid of all that. Without having to connect to the outside world with a shaft, all you have to do is make your mechanism move inside the engine, and the magnets are attached and so power is generated, which can be brought out with wires which are comparatively much smaller and don’t compromise engine things like sealing. And then there are obvious ideas from there like purely computer-controlled valving and injection.

Probably something people have thought of before, but it’s just what I was thinking about. I think if people worked on this, like really worked on it, they would come up with something. Unfortunately the world spends 90% of its time not taking the risks and working on what already works, which is hard enough as it is.

10

yeah, well, you haven’t thought of it either.

that’s been thought of. The Reg Technologies Rand Cam and Eugene Kauertz’s rotary vane engines have been trotted out every so often for decades. The simple answer is that they might work as a demonstration, but nasty real-world stuff like longevity, lubrication, etc. means that they can’t be mainstream.

huh? I used to be a mechanic, but I’m not so self-absorbed where I call myself a “genius with cars.” here’s a hint: people who need to tell you that they’re geniuses usually aren’t.

he’s an idiot. we have windage trays to deal with that, and they’re worth a couple of horsepower. certainly not 15 mpg. The extant automakers would kill you and everyone you know for a simple way to gain 15 mpg.

it is, but car engines don’t use ball/roller bearings because they have pressurized oiling systems.

bullshit. your theoretical engine still has to do all of that, you’ve just now introduced a few conversion steps to make it less efficient.

stick to what you know.

11

Lenz’s Law. The current in the cylinder bore will be just such that the field it produces will tend to cancel out the original change in field. How much it cancels out will depend on how good a conductor the cylinder is, but as mentioned, a chunk of aluminum thick enough to be a good engine cylinder is going to be a pretty good conductor.

12

Right, on the magnet-side of the bore, on the inside. But the outer edges will also have current, so magnetism would be generated on the outside, too. Or is that still canceled out by the original magnetic field?

13

he didn’t say that, I’m saying that, that’s how I’m describing him.

Hey, why don’t you calm the hell down with the attitude?

14

Are you talking about a toroidal engine? Look here Swing-piston engine - Wikipedia of here http://www.roundengine.com

I know it’s popular to think people/companies play it too safe; however, the true problem with many of these type of ideas is when theory meets reality. Take the Wankel engine; sounds great in theory, but couldn’t match fuel efficiency or emissions of a traditional piston engine.

As a thought experiment on your theoretical engine, think about a couple of common issues - how to keep everything lubricated for longevity, how to keep everything sealed (no combustion leaks, no oil leaks), how to efficiently get air/fuel in and exhaust gasses out.

15

The outer edges will only have current if there’s still a changing magnetic field for them to cancel (i.e., it hasn’t already been canceled by the inner parts), and the current will be such as to cancel out that residuum of changing magnetic field.

16

OK, good, it’s good to know it’s got an actual name.
Yes, similar to these, but without oscillations. Continuous rotary motion. Why none of these guys considered to have an opening-closing cylinderheads, by simply having a mechanism that looks sort of like a BMW logo or those “loading” icons on computers, to spin and seal the pistons from the front or back when necessary, but also spin to reveal a center through-hole, I dunno why they didn’t think of that
Could be that it could be really awkard and/or inefficient for it to work, maybe, I dunno

In general the whole point of this, like anything, is to get me/us/anyone thinking and walk to different concepts.
I’m thinking that advances in computers and ceramics might allow an engine like this to run super efficiently by avoid all timing and valve control mechanisms (replaced by computer/servo activation) and do the electro-mechanical generation thing like I mentioned

17

oh snap, the wikipedia article linked to a similar idea

https://www.youtube.com/watch?v=k7R9xXPfIio

I’m telling you guys, if there’s a way to get more efficiency out of engines, it will be in this vein. It may require some future change in technology like better ceramics or fluid bearings or computer systems but it’s there; some geometry somebody’s not thinking of is out there

The generator/engine in question has a large downside of those bearing ball guideways - would seem to produce a lot of friction

18

I had a long post written and lost it…:smack: but look up:

Atkinson Engine - more efficient piston engine, worked great in 1882 but too much monkey motion.

Jocko Johnson’s rotary - Worked well, looks impressive and your buddy will like it.

Abarth Fiat 500 with electrohydraulic valve train…scary complicated.

You should join the Speedtalk and Landracing forums and start reading…

Learn some physics. Newton starts to kick your ass at even a few 100 RPM.

Heavy magnets in pistons are a really bad idea.

19

To make chronos’ point very clear. Lenz’s Law means the opposite to what you thought would happen. You had a train of thought where moving magnet -> magnetic field in block - > external magnetic field. But that isn’t what happens. The magnetic field in the block is the opposite way around to the field in the moving magnets - so you get cancellation - not transmission of the field. You want the opposite effect - as little induced magnetism in the block as possible, so that as much of the moving field gets out as possible. As noted above, this means a non-conductive block. Non-conductive could mean aluminium with non-conducting gaps. But everything gets harder and harder.

As noted above, magnetic fields are hard things to tame and make use of. The fields run in a circuit, you need to be able to get the field to stay concentrated in a circuit that runs from pole to pole of the magnet, and have that concentrated field intersect your power generating coil. Even the smallest gap in the circuit makes the circuit very weak. This is why generators and alternators have very tight tolerances and are made largely of materials that have very high magnetic permeability (the magnetic equivalent of conductivity). This means ferromagnetic materials - which for any affordable use means stuff with iron in it.

Magnets hate high temperatures, and at about 700C most ferro-magnetic materials will lose their magnetic properties.

So, as described above, mixing magnetic systems with an ICE is a problem doomed for a host of reasons. Sometimes things align to make systems work nicely, other times they align to make things really bad. This is one of the latter.

20

If you want the most efficient way to put gas into something and get electricity out, you build a fuel cell. Turning the chemical energy into heat energy into pressure into moving a piston into moving a magnetic field and finally into electricity is never going to be better than a single step process. ICE engines make sense when the rotary motion is itself desirable, but attaching alternators to it has always been an admittedly inefficient extra step.

The only real downside to fuel cells is cost, and that’s being gradually overcome, so whatever way of making the ICE a more efficient generator of electricity is being discussed, keep in mind that if it isn’t also cheap, you’re not really accomplishing anything useful.