97 replies to this topic

[RVF400]

A friend sent me this. He said it was designed in the 70's by some guy named Salzmann.
Does anyone know what ever happened with this?

[Lee Nicolle]

I can understand why it was never heard of. Because it was another dumb idea.

[Vanishing Point]

A friend sent me this. He said it was designed in the 70's by some guy named Salzmann.
Does anyone know what ever happened with this?

[Grumbles]

I've never seen anything like that in an engine, but something very similar is often used in hydraulic pumps and motors. In these applications though the cylinders are, well, cylindrical rather than the reverse barrel shape shown here and the head of the piston/rod as well as the ring face is spherical. It works very well in hydraulics as it eliminates the need for a separate drive link but I can't quite grasp the advantage in an engine.

[cheapracer]

In theory it's advantageous in a 2 stroke where the port timing can be more appropriate allowing complete evacuation of the exhaust gas before the inlet is opened for example.

The Norman Hossack Cycle (of Hossack motorcycle fork fame) was discussed briefly recently, it appears to use straight bores ...

Edited by cheapracer, 20 November 2011 - 09:31.

[cheapracer]

A friend sent me this. He said it was designed in the 70's by some guy named Salzmann.
Does anyone know what ever happened with this?

The patents are here

http://www.google.co...l0l0l0l0l0ll0l0

...as Grumbles mentions I have also seen rocking piston pumps (air compressors to be exact) but it would never make it as an engine as the rings would be impossible to seal and the bore to difficult to manufacturer.

[Greg Locock]

The attraction would be
- reduced friction from the skirts ( I quite like that)
- reduced friction from gudgeon pin (probably miniscule)
- maybe lower reciprocating mass due to absence of skirts and gudgeon pin

I like the 2 stroke porting idea as well.

The big disadvantage is that grinding a bore that starts circular, goes elliptical, and ends up circular, would be rather tricky to say the least. Honing it would be pretty ugly as well. Also I had a feeling that the skirts help cool the piston head. I suppose you could use oil jets to get around that.

[Tony Matthews]

The big disadvantage is that grinding a bore that starts circular, goes elliptical, and ends up circular, would be rather tricky to say the least.

Yes, a complex shape. A bit like a cooling tower that, seen from one side is normal, but at 90° is cylindrical.

[24gerrard]

Yes, a complex shape. A bit like a cooling tower that, seen from one side is normal, but at 90° is cylindrical.

I only posted here to show Tony I appreciate his ability to see around corners.
Sign of a real artist that is.

[Magoo]

This deal springs from the mind of the late, great Willy Salzmann. He knew a couple of things about diesels... also, back in the mid '50s he designed a prototype microcar, the Soletta 750. Brilliant little thing, had a unique engine/gearbox/swing axle assembly employing rubber suspension. The chassis people here would get a hoot out of the arrangement, I'm sure. The car had a number of clever features but by that time the European microcar market was just about tapped out, I expect. The car is still around and pops up now and then at industry shows and so on. I think a Swiss museum or government entity owns it today. Well worth a look if you ever get the chance.

[saudoso]

Please forgive my stupidity, but why not just a spherical piston wall? Would work with straight bores...

[Grumbles]

Please forgive my stupidity, but why not just a spherical piston wall? Would work with straight bores...

That's what's used in the compressor and hydraulic applications. One major problem that stands out is the fact that you'd be limited to a single ring, so oil control would be a challenge. Especially if you had to spray it with oil to compensate for the lack of heat transfer through the skirt.

[saudoso]

tks

[Greg Locock]

That's what's used in the compressor and hydraulic applications. One major problem that stands out is the fact that you'd be limited to a single ring, so oil control would be a challenge. Especially if you had to spray it with oil to compensate for the lack of heat transfer through the skirt.

You'd need a single SPHERICAL ring, big enough to cover the full arc of the travel. Not easy.

[Lee Nicolle]

But why would one ever even bother. The whole thing would be very hard to machine, nigh impossibe to seal and cool and I expect it would viabrate badly too.
That is why we have what we have and that works well in any engine from a simple stationary engine to 18000rpm F1 engines.
It is totally reinventing the wheel!!
And at a guess the friction in that would be far worse than skirt drag which on a properly designed piston,ring, rod and bore combo is not that high and does transmit a lot of heat to the cooling system

[Greg Locock]

Big marine diesels use crosshead pistons. I don't know why exactly. This offers some of the same advantages. You are right, i doubt it would replace the standard architecture for all applications, but it may fulfil some niche requirements.

[RVF400]

When I first saw it I thought it might have been used in the experiments with rectangular pistons.
I guess it wasn't. At least the guy put his beer down long enough to draw something half way
interseting.

[munks]

But why would one ever even bother.

Yeah, agreed. Everything that could be good has already been invented, right?

[cheapracer]

When I first saw it I thought it might have been used in the experiments with rectangular pistons.
I guess it wasn't. At least the guy put his beer down long enough to draw something half way
interseting.

Hossack's engine had rectangular pistons, appears the picture I linked can't be linked so you will have to go to his site and look around, go to the 'design' link at the page ..

http://www.hossack-d...hp/page.php?p=4

[Grumbles]

Big marine diesels use crosshead pistons. I don't know why exactly...

The crosshead engines are usually double acting with a gland around the piston rod to allow both sides of the piston to be working sides.

[Lee Nicolle]

Yeah, agreed. Everything that could be good has already been invented, right?

For production vehicles it has to be reasonably simple to make. And for most motorsport categorys they require round bores so yes it will never take on.
Even rotarys still are not the most practical engine in the world after 50 years plus of trying to make them so and ever only sell in small numbers. And are quite expensive to machine and maintain.

[gruntguru]

The crosshead engines are usually double acting with a gland around the piston rod to allow both sides of the piston to be working sides.

Certainly the case with steam engines but rarely (perhaps never) for crosshead diesels.

The advantages of elimination of piston side thrust include:
- minimise skirt area and thus friction
- no piston rocking therefore ring wear is cylindrical (and reduced)
- reduce blowby (no rocking again)
- reduced oil consumption (skirt oiling requirement is reduced)

In addition:
- ability to seperate ring and thrust lubrication functions
- makeup oil (new oil) can go direct to ring pack (reduces contaminant buildup)

I'm sure there's lots more.

[bigleagueslider]

I can understand why it was never heard of. Because it was another dumb idea.

The Darwinian evolutionary principles such as survival of the fittest, natural selection, elimination of the weak, etc. apply to engine design as much as biological systems. Fortunately, evolutionary abnormalities like this Salzman concept are quickly eliminated through natural selection. With evolution of engine design, just as in evolution of biological species, the only developments that become successful are those that are better overall than the status quo. While the idea of a one-piece piston/rod would appear to have merit in principle, in practice the concept requires too many other compromises to be of any benefit.

Occasionally however, there is the rare example of an engine concept (like the Wankel rotary) that would seem to make no engineering sense, yet ends up being somewhat successful commercially due to relentless development effort. Ironically, the Wankel has a one piece "piston and rod".

[Greg Locock]

On a much smaller scale I always find it fascinating when one has to choose when to drop an architecture (or idea) during the development process, in favour of some other, usually more conservative, path. There are innovative ideas where the concentrated application of effort has resulted in success, and a successful innovator must have more of those under his belt than the ideas that never see the light of day despite equivalent effort. I wish I had that sort of brain, but I don't.

[24gerrard]

I think the principle starts with thinking of something as simple as possible to achieve the purpose in theory.
Then adding things that are essential for it to work in practise.

[Tenmantaylor]

As said it's nice to combine 2/3 components as 1 but the difficulty it then puts onto the bore process kills any gain when the entire manufacture procedure is taken into account.

Please forgive my stupidity, but why not just a spherical piston wall? Would work with straight bores...

Viewing a circle at an angle creates an ellipse. Would require circular wall when piston is vertically aligned, elliptical wall when piston is angled. Working out this constantly varying curvature is actually quite easy in a CAD system but not to manufacture. Well, compared to a pure cylindrical wall which would use a turning/drill type tool on a single axis.

Edited by Tenmantaylor, 22 November 2011 - 11:37.

[cheapracer]

Working out this constantly varying curvature is actually quite easy in a CAD system but not to manufacture.

Apparently quite easy to make any engine etc. in CAD and show that it's works in theory. If I was in power I would make it illegal to take any capital investment based on CAD animations.


Greg, I think a helpful approach is to imagine your invention/innovation is already the everyday standard and the everyday standard thing you're up against is the new invention and then weigh them up.

That also helps you to see why the successful things already have their place.

Probably the biggest mistake I see with "new engines" like this one above is they step outside of common machining practices - there's billions and billions of dollars invested in engine making machines worldwide but you want manufacturers to start all over again?

.... Not going to happen.

[24gerrard]

Probably the biggest mistake I see with "new engines" like this one above is they step outside of common machining practices - there's billions and billions of dollars invested in engine making machines worldwide but you want manufacturers to start all over again?

.... Not going to happen.

Thats why my ESERU is not yet in production, needs a completely knew manufacturing base.
It is also why electric vehicles cannot replace ic vehicles over night.

[Magoo]

I'm not sure that cylinder profile is so difficult to replicate. I've seen it done accidentally lots of times.

[Magoo]

I've never seen anything like that in an engine, but something very similar is often used in hydraulic pumps and motors. In these applications though the cylinders are, well, cylindrical rather than the reverse barrel shape shown here and the head of the piston/rod as well as the ring face is spherical. It works very well in hydraulics as it eliminates the need for a separate drive link but I can't quite grasp the advantage in an engine.

Rocking pistons are also extremely popular in air compressors, aerators, and vacuum pumps. One advantage: oilless.

[Tony Matthews]

I'm not sure that cylinder profile is so difficult to replicate. I've seen it done accidentally lots of times.

[Bloggsworth]

With modern CNC machinery it would be a doddle to make. Modern injection moulding tools don't even need polishing after they come out of the machining centre.

[Tenmantaylor]

With modern CNC machinery it would be a doddle to make. Modern injection moulding tools don't even need polishing after they come out of the machining centre.

I agree it's entirely possible to be machined accurately (almost anything is) but not feasibly on the mass produced scale that car engine blocks are. On a multi axis machine the cycle time would be huge, many times longer than a simple rotating bore procedure. The reward wouldn't be worth the effort. The concept doesn't appear to be a reward at all based on comments here. Maybe if the performance reward was big prestige marques could afford it.

[gruntguru]

On a much smaller scale I always find it fascinating when one has to choose when to drop an architecture (or idea) during the development process, in favour of some other, usually more conservative, path. There are innovative ideas where the concentrated application of effort has resulted in success,

Conversely there have been many ideas that deserved to win through but didn't simply through lack of effort. Why? - usually lack of vision or conservatism from potential backers - sometimes deliberate supression by those who stand to lose.

[gruntguru]

With modern CNC machinery it would be a doddle to make. Modern injection moulding tools don't even need polishing after they come out of the machining centre.

Cylinder bores would require an additional process or two.

[Lee Nicolle]

The Darwinian evolutionary principles such as survival of the fittest, natural selection, elimination of the weak, etc. apply to engine design as much as biological systems. Fortunately, evolutionary abnormalities like this Salzman concept are quickly eliminated through natural selection. With evolution of engine design, just as in evolution of biological species, the only developments that become successful are those that are better overall than the status quo. While the idea of a one-piece piston/rod would appear to have merit in principle, in practice the concept requires too many other compromises to be of any benefit.

Occasionally however, there is the rare example of an engine concept (like the Wankel rotary) that would seem to make no engineering sense, yet ends up being somewhat successful commercially due to relentless development effort. Ironically, the Wankel has a one piece "piston and rod".

The rotary engine after 50 + years really is still an expensive oddity. It is smooth and reasonably powerfull but not very economical and has frequent and high service costs.
Has anybody seen a 300000k untouched rotary, no nor have I . About half that for a well maintained one before they start to get hard to start because the seals are leaking.
But how many 600000km 6s and V8s are around. Lots, most old cabs have done in excess of that and if maintained properly have never been apart and still go ok. Even the occasional 4 does 400000 + without being touched.

[cheapracer]

With modern CNC machinery it would be a doddle to make.

Doesn't even come close to the simplicity of machining and finishing to size/final surface of a simple round hole.

[scolbourne]

This design might make sense in cheap 2 stroke model engines which could be simply cast (not requiring machining), and having less parts would keep the cost down and result in an engine with less things to go wrong.


Has this been built yet ?

[Greg Locock]

I suppose two architectures spring to mind -swash plate engines and wankels.

In one case hardly anybody has put much money into them, and they work, in a niche, where it fits perfectly. In the other case one company has given several generations of graduates the chance to get to grips with a never-ending series of difficult real world problems, and come up with a solution that is somewhat competitive to the state of the art.

[cheapracer]

I suppose two architectures spring to mind -swash plate engines
In one case hardly anybody has put much money into them,

I thought many millions had been put into at least one ......... since I met one of the suckers I can't force myself to put a smiley here, poor bastard (literally now).

I of course refer to the "Split Cycle Engine Company" of Australia.

[Greg Locock]

Oh, I was thinking of Harrison V* ACUs, and torpedo engines, as niches for swashplates. Was Split Cycle a swashplate?

[gruntguru]

The Queensland Split Cycle had radially oriented pistons actuated by a kind of rolling cam mechanism.

[cheapracer]

The Queensland Split Cycle had radially oriented pistons actuated by a kind of rolling cam mechanism.

Well there you go, I always thought it was a swashplate but then I never actually saw one - but then again, did anybody .....

[malbear]

The Queensland Split Cycle had radially oriented pistons actuated by a kind of rolling cam mechanism.

It never realy produced enough power to run itself . most demos were powered by a suply of compressed air..
A french testing house eventually came up with a figure of 1% eficiency.

[MatsNorway]

This design might make sense in cheap 2 stroke model engines which could be simply cast (not requiring machining), and having less parts would keep the cost down and result in an engine with less things to go wrong.


Has this been built yet ?

The main issue with this design is the unavoidable vibrations. due to the piston not going simply down and up but also in a kinda 8 figure it would generate more sideways as well. Perhaps the addition of the vibrations, from the tilting of the piston as well.

Considering a nitro model engine does 30 000rpm or more, im not sure it would have gains on the exisiting motors.

I do like it however. As a two stroke motor.

[cheapracer]

It never realy produced enough power to run itself . most demos were powered by a suply of compressed air..
A french testing house eventually came up with a figure of 1% eficiency.

I seem to rememeber they ran one in a Targa Tasmania but i didn't hear much more or can't remember much more (damn you Johnny Walker).

I got a headache trying to work out the patent, try again tomorrow ...

http://www.google.co...A...mp;q&f=true

[JtP1]

It would seem simpler and more effective just to make it a ossillating engine.

[bigleagueslider]

On a much smaller scale I always find it fascinating when one has to choose when to drop an architecture (or idea) during the development process, in favour of some other, usually more conservative, path. There are innovative ideas where the concentrated application of effort has resulted in success, and a successful innovator must have more of those under his belt than the ideas that never see the light of day despite equivalent effort. I wish I had that sort of brain, but I don't.

GregLocock,

With regards to innovation in automotive piston engines, I love the story of Pontiac engineer Clayton Leach who developed the stamped steel rocker arm. I don't know if you've ever seen the stamped steel rocker arms that were used on GM pushrod engines throughout the 60's, 70's and 80's, but in my opinion this innovation ranks as one of the greatest in the history of piston engine design.

Think about this idea for a second. If you had not seen it done, would you believe it possible to make a production quality rocker arm from a steel stamping? I wouldn't, and the management at GM didn't believe it possible either when Clayton Leach proposed the idea. So after his idea was rejected by his bosses at GM, he went home and worked on the idea in his basement. Using crude stamping tools he made himself, he eventually produced a usable stamped steel rocker arm, and then presented it to his bosses. His bosses were impressed, and the stamped steel rocker arm soon went into production.

While the stamped steel rocker arm may outwardly appear crude and unimpressive, it saved GM a couple of bucks on each of over 100 million pushrod engines it produced for over 4 decades. Pontiac's management didn't have the type of foresight regarding innovation you describe, but fortunately Clayton Leach did. And his simple innovation resulted in hundreds of $millions in profits for GM shareholders.

slider

[24gerrard]

I would have thought that sintering for producing rocker arms was a more important development.
Almost all Leyland engines in the 60/70's had them and few needed any bushes to run on the shafts.
(I did make a few out of carbon fibre along with steel tipped push rods for the cooper S engines.)
If I remember, the steel pressed versions were two piece riveted, or welded together.
Later Leyland did a lot of pioneer work in electron beam welding with companies like AP.

[cheapracer]

I would have thought that sintering for producing rocker arms was a more important development.
Almost all Leyland engines in the 60/70's had them and few needed any bushes to run on the shafts.

You have completely missed the point, the stamped rockers totally eliminated the need for rocker shafts along with support towers and all the drillings for oil feed and accurate boring for rockers. It also lowered engine heights (and widths in the case of a 'V').

If I remember, the steel pressed versions were two piece riveted, or welded together.

I have only ever seen single stamped pieces that very typically look like this ..