Camshafts/ESP Driven by Connecting Rod

Hi!

I'd like to revive the discussion about timing belts versus timing chains. It seems that among the established drive methods, there are only these two options.

Let's take a look at how rotational motion can be transmitted with minimal loss and noise, without slippage, and in a technically simple way (although only with a 1:1 gear ratio).

http://www.jockels-hobbyecke.de/shop/images/big/141.jpg

These locomotives are designed for speeds of 60 km/h and above. With a driving wheel diameter of approximately 1 meter, the connecting rod drive achieves a huge rotational speed (in relation) (~5 revolutions per second!). Translated to a passenger car camshaft drive, this would mean a 'stroke' of approximately 80 mm (realistically for torque transmission) in order to have less surface velocity than at the locomotive!
However, two crankshaft offsets of 90 degrees each (i.e., two connecting rods) are required for a complete connecting rod drive system to overcome dead center and transmit torque evenly (the locomotive uses both sides for the 90-degree offset).

Advantages of push-rod drive:

- Free from backlash, whipping effect, or elongation; provides absolutely precise power transmission, even at peak torque.
- When integrated into the lubrication circuit, it is completely maintenance-free for the entire lifespan of the engine, unlike belts and chains.
-Extremely quiet in plain bearing operation, possibly even quieter than a timing belt.
- It is possible to easily couple more than two waves (e.g., for VPs), even if they are not aligned in a straight line (as with a locomotive).
- In my opinion, it is definitely not more expensive than a chain drive.


Disadvantages:

- Increased overall width due to the two drive shafts positioned at a 90-degree angle, as well as the counterweights on both the input and output shafts.
-Not 100% balanced. Due to the relatively low rotational speeds and the high overall load, especially on the main bearing, but in my opinion, this is not significant.
-A direct drive with a ratio of 2:1 on the crankshaft is necessary for a one-to-one translation, but this reduces the distances between the shafts, which in turn decreases the mass of the connecting rods.

Given the interesting advantages, I wonder if there have been any engines with this type of propulsion system before, or if not, why not.

hello

Look at this!
http://www.ich-fahr-max.de/download/bmamo98d.pdf

Ah, interesting that my idea has already been implemented, and moreover, in a quite successful motorcycle engine .

http://img129.

/img129/9418/nsu4sh.jpg

However, the serious problem of thermal expansion of the drive shafts is mentioned (specifically, the difference in expansion between the block and the drive shafts). This may potentially be compensated for by a variable flank clearance on a large, 'floating' front gear.

SeatArosa1.7SDI wrote:

... - Free from backlash, whipping effect, or elongation; provides absolutely precise power transmission, even during torque peaks.

"...Only if the connecting rods were designed to be so massive that any deflection would be minimal or non-existent. Unfortunately, you won't be able to build a motor with that design that even comes close to the efficiency levels of current state-of-the-art technology. In trains, weight is necessary, but in cars, it's not desirable."

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Disadvantages: ... -Not 100% balanced. Due to the relatively low rotational speeds and the high overall load, especially on the main bearing, but in my opinion, this is not significant. ...

The crux of the matter, and the ultimate deciding factor, is that the auxiliary drive must be largely free from vibrations. Otherwise, you end up with an engine that shakes and vibrates excessively, which can only be stabilized with considerable effort. This requires either a lot of mass or balance shafts, both of which have their own drawbacks.

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... Given the interesting advantages, I wonder if there have been any engines with this type of propulsion system before, or if not, why not.

Counter question... Why all the fuss? / Why be so complicated?
A bottom-mounted camshaft with pushrods also worked perfectly fine. There were no problems with the camshaft drive.
Why are there hardly any more engines built like this anymore?
Then you have your answer as to why the connecting rod drive was also a dead end in engine design.

That's precisely the crux of the matter and the ultimate deciding factor. The internal combustion engine must be largely free from vibrations, otherwise you will end up with a shaking and rattling motor.

The fact that this principle was used in a successful motorcycle engine (motorcycle, not a Lanz Bulldog!!!) contradicts this blanket statement. In the motorcycle sector, engines with low vibration are more necessary than in any other type of vehicle.

... Only if the connecting rods were designed to be so massive that deflection would not occur (or would only be minimal).

If steel rods were already successful in motorcycle engines, just imagine what Kevlar rods could do...

An underslung camshaft with pushrod actuation also worked perfectly fine. There were no problems with the camshaft drive.
Why are there hardly any more engines of this type anymore?

Pushrods transmit a (non-sinusoidal!) oscillating motion. The mass inertia directly affects the entire system. For the same closing speed at high engine speeds, the valve springs must be correspondingly stronger. Consequently, the average force level that the camshaft must exert is higher, which increases frictional losses. (However, if high-tech, ultra-light materials are used for the pushrods, this type of drive mechanism could again become a viable option, such as a composite material made from titanium and Kevlar.)

In the case of a wobble plate drive, this problem does not occur because all the components involved follow a circular path.

No, your arguments so far are not sufficient to technically disqualify the crankshaft drive. In my opinion, 'cheap is good' and the second pot of money for automotive companies (the contract workshops, which also want to be employed) play a role.

SeatArosa1.7SDI wrote:

... The fact that this principle was used in a successful motorcycle engine (motorcycle, not a Lanz Bulldog!!!) contradicts this blanket statement. In the motorcycle sector, engines with low vibration levels are more necessary than in any other type of vehicle.

"... Someone who has undoubtedly driven thousands of Max karts can tell you that this engine is anything but "successful" and far from running smoothly. Compared to the crankshaft engines available at the time, it might have been better, but the OHC engines are vastly superior. That's why this concept disappeared."
If you're already delving into engine concepts, you might also want to look into "crankshaftless" engines.

Quote:

Quote: ... Only if the connecting rods were designed to be so massive that deflection would not occur (or would only be minimal). If steel rods were already successful in motorcycle engines, just imagine what Kevlar rods could do...

Kevlar in the engine?
If ceramics struggle to gain widespread use, what chance does Kevlar have, being much more sensitive to temperature?
If the temperature issue were resolved, that would be an ideal situation.

Quote:

Quote: An underslung camshaft with pushrod actuation also worked perfectly fine. There were no problems with the camshaft drive. Why are there hardly any more engines of this type anymore? Pushrods transmit a (non-sinusoidal!) oscillating motion. The mass inertia directly affects the entire system. For the same closing speed at high engine speeds, the valve springs must be stronger accordingly. Consequently, the average force level that the camshaft must exert is higher, which increases frictional losses. (However, if high-tech, ultra-light materials are used for the pushrods, this type of drive mechanism could again become a viable option, such as a composite material made from titanium and Kevlar.) In the case of a wobble plate drive, this problem does not occur because all the components involved follow a circular path.

... Both concepts "ignore" the deflection of the pushrods. This can only be controlled to a limited extent (at least with a fixed amount of bracing material).
Your point about the high-tech material is absolutely correct, but unfortunately, you would likely not be willing to pay the extra cost yourself.
For example, are you aware of the price difference between a Porsche connecting rod made of titanium and one made of steel? There's a significant price gap between the two.

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No, your arguments so far are not sufficient to technically disqualify the connecting rod drive system.

Not technically, but in terms of cost.

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IMO, the slogan "being stingy is great"

and the second profit distribution from automotive corporations (specifically, the contract workshops, which also want to be employed) } play a role.
Das "Geiz ist Geil" bestimmt immer noch der Kunde. So, you too.
Go ahead and finally buy yourself a motor with a fixed-ratio transmission. Why are you buying such a "lemon" with a variable ratio system and then complaining about that concept? It's because you're just as inconsistent and prefer to take the cheapest option (after all, being cheap is still appealing).
YOU are the one who reinforces the manufacturer's decision to continue building the engine in that way with your purchase.

Go ahead and finally buy yourself a ZR-loss motor. Why are you buying such a 'lemon' with ZR and then complaining about this concept? It's because you're just as inconsistent and prefer to take the cheapest version (after all, being cheap is still great).

'Incorrect. Because back then (in 1999), a product of mine was never offered without a timing belt. Moreover, the Arosa SDI, around 1997, was one of the first mass-produced diesel subcompact cars (and direct injection) that fit into the '5-liter car' category (i.e., 4.XL). It made headlines with its fuel consumption record for diesel passenger cars when it was used to cross the USA with a 3.XL. This impressed me in 1997, and since it was relatively inexpensive as a (nearly) new car around 1999, I managed to get one, so I went ahead and bought it.'

YOU are the one who reinforces the manufacturer's decision to continue building the engine IN THAT WAY with your purchase.

And THAT is the crucial flaw in thinking. The market mechanism isn't that simple (unfortunately!). Part of the 'customer desire' is also generated by the manufacturer themselves. From the car dealership salesperson to advertising and media coverage (ADAC & Co.), everyone manipulates, awakens specific desires, and directs the attention of the masses in a certain direction. See also http://de.wikipedia.org/wiki/Freier_Wille.
Und wenn diese im Mainstream mitschwimmende Schafsherde eine kritische Masse übersteigt, dann funktioniert dein oben gepriesener Marktmechanismus nicht mehr. D.h., wenn die Mehrheit der Käufer in gewissen Dingen leicht manipulierbar und nur noch schwer in der Lage ist, sich ein objektives Gesamtbild zu verschaffen, dann kann die Nachfrage nach 'ZR-los' bei den restlichen 40%Käufer so groß sein wie sie will, sie bewirkt nichts mehr. Denn ein Zugewinngeschäft mit unterproportional leisem Protest gibt man nicht freiwillig auf. Leise ist der Protest vielleicht auch deswegen, da der Käufer sich ja tröstet, ein gutes Auto erworben zu haben: Im Crashtest um 0,XX% besser, neuestes CD-Radio mit TIM, Metalliclack ohne Aufpreis, Klima sogar als Klimaautomatik, Schiebedach, 3L mehr Kofferraumvolumen.............Wartungsfreiheit des Triebwerks auf Lebenszeit wurde nie beworben und gelangt so gar nicht ins Bewußtsein. Ein ZR-Intervall beim TDI von 60.000km zu je 500€ wurde von den Medien nie als Skandal öffentlich angeprangert. [ironie]Das kann dann also nicht schlimm sein. 'Hab extra in der ADAC-Zeitschrift nachgelesen, daß mein Auto 0,X% besser ist als XYZ. Dann ist es auch gut. Das mit dem ZR muß wohl so sein. I'I'm going to complain a little bit today and tomorrow, but after that, I'll be happy with my car again.' [/irony]

hello
Holger.

SeatArosa1.7SDI wrote:

... Because a product was never offered without a timing belt in my target specifications back then (in 1999). ...

Then don't complain. By doing that, you strengthened the manufacturer's position.

You should also understand that your design goals can only be achieved with a small, lightweight engine. Chains or connecting rods make it significantly heavier and bulkier. This is still the case today. No engine with chain timing achieves such low fuel consumption values, probably because these engines are only installed in large vehicles where there is sufficient space. You mentioned the available space for his solution in your original post. It would give any packaging engineer gray hairs.

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... And THAT is the crucial flaw in thinking. The market mechanism isn't that simple (unfortunately!).

According to this, BMW and DC are no longer selling cars with rear-wheel drive or expensive ZR engines. However, they are still selling these vehicles in large numbers. They seem to be marketing the rear-wheel drive and robust engine design as attractive features for technically interested customers. Apparently, these customers are willing to pay significantly more for it, even if it means consuming more fuel, which seems to indicate that "being cheap is not cool." This contrasts with your (commendable) attitude. However, one must also accept the compromises that come with it, which you apparently still don't want to do.

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A portion of the "customer demand" is also generated by the manufacturer itself.

More likely from the media. The manufacturer doesn't need that.

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... The media never publicly denounced the practice of charging €500 for each service interval (ZR interval) on TDI vehicles, which were set at 60,000 km.

Yes, indeed. The reputational damage caused by publications like "ADAC Motorwelt" and "Auto Blöd" back then is still felt today.

Hi! I'll write something about it later. For now, this is a very nice overview of the 4 major types of nuclear propulsion systems and their historical development (you can scroll through from page 1 to 4).

http://www.oldtimer-markt.de/__C1256B96004F36DA.nsf/previewFS?OpenPage&A&ArticleIDsorted/~63B83C610570B308C1256C860054FC6A

The discussion is coming years too late .

Nowadays, it's clear that the ZR has undergone significant development and is now a mature, lightweight, quiet, and technically "well-controlled" system. When a designer today is working on a morphological design, they will ultimately turn to the ZR as a solution because it addresses all requirements comprehensively.

No car manufacturer will lightly dismiss a concept that they consider to be "theirs," as such an action would not be justified by the risk assessment of a new development project.

And yes, I bought an AJM (knowing about the 60,000 mile service interval) and have been driving it with great enthusiasm. Nowadays, the 120,000 mile service is no longer a major issue for most people (and it never really was for the gasoline versions anyway).

SeatArosa1.7SDI wrote:

...First of all, a very nice overview of the 4 important types of Northwest propulsion systems and their historical development...

"But there are still some missing."

- Gears (spur gears)
It has been present since the early days of the Northwest control system. Unfortunately, just like with the pushrods, thermal expansion and the structural complexity of these designs lead to failures, something that Volkswagen is currently experiencing with the T5 TDI.

- Pneumatic valve controls (even without a network connection).
They existed very early on and are now state-of-the-art in Formula 1. However, they are probably too complex and expensive for everyday use, but they are incredibly lightweight and extremely accurate (fast). In my opinion, they represent the ultimate solution.

- Electromechanical actuation (also possible without a network connection).
Basically, it's a simpler alternative to pneumatic actuation. Unfortunately, it consumes a lot of energy.

- Piezoelectric actuation (also possible without a power supply).
How pneumatic actuation... future technology (I can't say more than that ).



You can see that there are significantly better concepts out there. However, they are still a ways off from being ready for mass production. Until then, we have to make do with these conceptual limitations.

Bertil wrote:

- Gears (spur gears). It was already present in the early versions of the NW control system. Unfortunately, just like with the pushrods, thermal expansion and the structural complexity of these designs lead to failures, something that Volkswagen is currently experiencing with the T5 TDI models.

Unfortunately, with a PD motor (which many people here have), gears and timing belts are also the only currently available solutions for direct drive. The other options are unfortunately not feasible in this case.

As you already mentioned, the front-mounted timing chain drive was also deemed unsuitable for the 5-cylinder TDI – it was too complex and too noisy. However, the main reason for phasing out this engine is that the VR6 TDI will cover this performance range in the future and can be used below the 4-cylinder models.

I also don't understand why so many people criticize the timing belt; it has evolved (as mentioned before). If we put aside the other concepts, the chain drive (which many prefer) can only be used with a CR engine. Furthermore, it also has some disadvantages (e.g., in the VW VR6 engine): It's difficult to access from the transmission side, and there are up to four sealing surfaces on the chain tensioner that come into contact with each other. If maintenance work is needed here, it becomes expensive and time-consuming.

Hello!

SeatArosa1.7SDI wrote:

Hi! However, two crankshaft offsets of 90 degrees each (i.e., two connecting rods) are required for a complete connecting rod drive system to overcome dead center and transmit torque evenly (the locomotive uses both sides for the 90-degree offset). Disadvantages: -Not 100% balanced. Due to the relatively low rotational speeds and the high overall load, especially on the main bearing, but in my opinion, this is not significant.

I recommend taking a ride on one of these locomotives, and if possible, even once on a two-cylinder steam locomotive. Both should be operating under load at speeds of 60-80 km/h.
You will see or experience that the term "not 100% free of imbalance" is a relative one.

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Advantages of push-rod drive: - Free from backlash, whipping effect, or elongation; provides absolutely precise power transmission, even at peak torque.

Depending on the applied force and the material used, an elongation will definitely occur.
The same kinds of compromises are required now as were needed in the past with locomotives.

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- It is possible to easily couple more than two waves (e.g., for VPs), even if they are not aligned in a straight line (as with a locomotive). - In my opinion, it is definitely not more expensive than a chain drive.

It's guaranteed to be more expensive than a chain drive, and it also requires significantly more space. You must not ignore the forces that need to be transmitted, especially when driving components like the fuel injection pump or variable valve timing system. The high torques required for diesel injection, combined with the sudden loads, pose a challenge for camshaft drives. For example, driving a fuel injection pump directly via a gear is difficult, if not impossible (not robust enough).

Connecting rods also introduce a significant amount of rotational inertia into the drive system.
"Exotic" materials would be too expensive again.

BYE
TDI mechanics.

Bertil wrote:

- Pneumatic valve controls (even without a network connection). - Electromechanical actuation (also possible without a network connection). - Piezoelectric actuation (also possible without a power supply).

These perspectives also highlight technical reasons against PD (presumably referring to a specific technology or approach) and in favor of CR (likely another technology or approach).

I find the question of the market window interesting here, because a small diesel generator for electricity generation in a full hybrid system wouldn't need all those extra features anymore...

pschaefer wrote:

Bertil wrote: - Pneumatic valve controls (even without a network connection). - Electromechanical actuation (also possible without a network connection). - Piezoelectric actuation (also possible without a power supply). These perspectives also highlight technical reasons against PD (presumably referring to a specific technology or approach) and in favor of CR (likely another technology or approach). ...

It's not necessarily a requirement. You can also use piezoelectric elements to generate the necessary pressure for a PD injection system without needing any cam actuation. In fact, there have even been initial attempts using this technology dating back 10 years ago. This technique would likely render the common rail (CR) system obsolete. Generating pressure directly at the point of injection is always better and more efficient.