Honda Paper (2009) on F1 engine development

[ZeeOSix]

Also read the sections on friction loss and temperature effects. Like I said before, on engines with high loads and high HP, the required oil flow through the bearings may have to be increased significantly to keep it from heating up and becoming damaged because the oil film boundary layer disappeared due to over heating the oil film. The only way to prevent that is to force feed the bearing more oil volume than it wants to naturally "suck" in order to carry away the generated heat.

And I see you totally ignored my post with the link that clearly showed that the supply pressure (from the PD oil pump) is a critical component of journal bearing design.

 

[Shannow]

LOL, which segues back so nicely into your statement that
"the percentage flow rates are the same at all RPM"
"but I'm saying that the percentage flow rate splits are the same, but NOT the percentage flowrates"

Or some ramblings around contradicting yourself on that point but being perfectly clear.

 

[ZeeOSix]

Guess you just can't admit the information I showed is correct and your thinking is flawed. The link I gave above is a solid source of information.
Tribology International Vol. 30, No. 11, pp. 825–834, 1997
http://web.iitd.ac.in/~hirani/rapid_perfromancce.pdf

We are right back to the point where you don't think engine components are "force fed" oil flow by the PD pump. You do realize (I hope) that flow is forced any time there is a pressure difference across a flow path. That's about the simplest aspect of understanding fluids there is.

 

[Shannow]

Originally Posted By: ZeeOSix
And I see you totally ignored my post with the link that clearly showed that the supply pressure (from the PD oil pump) is a critical component of journal bearing design.


I read your post, and the link.

And I read this post before your edit...

 

[Shannow]

Originally Posted By: ZeeOSix
Guess you just can't admit the information I showed is correct and your thinking is flawed. The link I gave above is a solid source of information.
Tribology International Vol. 30, No. 11, pp. 825–834, 1997
http://web.iitd.ac.in/~hirani/rapid_perfromancce.pdf

We are right back to the point where you don't think engine components are "force fed" oil flow by the PD pump. You do realize (I hope) that flow is forced any time there is a pressure difference across a flow path. That's about the simplest aspect of understanding fluids there is.


LOL, and THAT post before the edit too.

And that final statement, you have described before as your "belief" in what I'm believing.

There's simple fluids, and there's simplistic thinking regarding it, simplistic thinking that states that an electric pump feeding oil through a stationary shaft is identical to a running engine with all of it's dynamics.

 

[Jetronic]

the way to get more oil flow through a bearing (to reduce average bearing temp)) would be to increase the clearance, no?

 

[ZeeOSix]

Originally Posted By: Jetronic
the way to get more oil flow through a bearing (to reduce average bearing temp)) would be to increase the clearance, no?


Or increase the supply pressure to the bearing ... which is the better way. You want to keep the bearing clearance at it's required design number.

 

[Shannow]

Originally Posted By: ZeeOSix
Originally Posted By: Jetronic
the way to get more oil flow through a bearing (to reduce average bearing temp)) would be to increase the clearance, no?


Or increase the supply pressure to the bearing ... which is the better way. You want to keep the bearing clearance at it's required design number.


Per your posted photos...IF (note that word IF) you can't keep temperatures under control through the normal leakage route of the bearings.

Jetronic,
when designing bearings, it's an iterative process.

Come up with a design, model it, and see what the temperature rise is across it...as it's iterative, takes a few rounds to settle on what it is ultimately...if it's not right, then change something. (not that this is only the short bearing steady state, the bearings will pump more with the oscillations that come from cyclinc load, cumulatively with this.

Shows what parameters would normally change flows and in what direction, but has to be tempered with MOFT and keeping the bearing in it's stability range.

Even the transition to HTHS shear rates will drop the apparent viscosity (in bearings, squirters still see KV), and increase the flows some.

And as Per zeeosix...when you can't design your bearings the "IF you can't control temperature", you throw more pump at it, which isn't good design, as it changes everything else in how squirters, hydraulics etc. opperate, and increases parasitic losses.

Which is the VERY REASON that automotive manufacturers are going to variable displacement oil pumps.

http://www.melling.com/Portals/0/OE%20Pr...p%20systems.pdf

Note the difference between engine requirement and the typical PD delivery curve...engine doesn't need as much oil per revolution at higher RPM (see top chart), and the OEMs aren't interested in trying to jam that volume through the bearings.

 

[ZeeOSix]

Originally Posted By: Shannow
Originally Posted By: ZeeOSix
Guess you just can't admit the information I showed is correct and your thinking is flawed. The link I gave above is a solid source of information.
Tribology International Vol. 30, No. 11, pp. 825–834, 1997
http://web.iitd.ac.in/~hirani/rapid_perfromancce.pdf

We are right back to the point where you don't think engine components are "force fed" oil flow by the PD pump. You do realize (I hope) that flow is forced any time there is a pressure difference across a flow path. That's about the simplest aspect of understanding fluids there is.


LOL, and THAT post before the edit too.

And that final statement, you have described before as your "belief" in what I'm believing.

There's simple fluids, and there's simplistic thinking regarding it, simplistic thinking that states that an electric pump feeding oil through a stationary shaft is identical to a running engine with all of it's dynamics.


Your position all along in these discussions is that the journal bearing is not actually force lubricated by the oil pump. You've said it many times. If that's not your "theory" then you really need to try and explain exactly where you're at in these discussions. You instead keep deflecting and back peddling and never really stay focused on one discussion at a time. Just like these statements made by you (quote below) ... they don't align with what I'm saying and what information I've shown. And when I try to ask you a direct question on how you see something happening, you never respond and go off in the weeds with something else.

The part in red in your quote below clearly shows that you don't believe bearings supplied with high oil pressure by a PD pump are being "force fed" oil. You still believe that all journal bearings simply "suck" in the amount of oil they need (regardless of their supply pressure) due to their rotational dynamics and the tiny little vacuum they create due to their eccentricity while rotating. That "sucking in oil" part is true, BUT ONLY for atmospheric fed bearings, NOT for pressure fed bearings - that is the important part you keep missing.

In pressure fed bearings with any significant positive supply pressure there is never any area inside the journal bearing that is below atmospheric pressure (ie, at any level of vacuum). There might be an area inside them that is slightly below the supply pressure, but never below ATM pressure.

Originally Posted By: Shannow
Ahhh...there's your misunderstanding...they are not "resistive" at all...they replace oil that leaks out of them in service with oil from the galleries, if they need less than the pump delivers, then oil pressure goes up.

You do not pump oil through a bearing at all...

A big journal bearing can actually SUCK oil into itself up quite a few inches of head, so clearly, they are not being pumped into.


Here's a little visualization exercise for you to ponder. Lets say that Honda 2.4L V8 is running at a constant 10,000 RPM and everything in the oiling system is stabilized. Meaning all the journal bearings are floating where they want to be, and the oil flow in the entire oiling system is all going to where it wants to go.

Now magically stop the engine from running and keep all the mechanical components in the same exact physical positions they were in while running, BUT keep the PD oil pump still rotating at the same exact speed and oil volume output is was at when the engine was running at 10,000 RPM.

What do you think is going to happen to all that oil flow (~50 L/min = 13 GPM per the Honda paper, Figure 15) that is still coming out of the oil pump like the engine was still running at 10,000 RPM?


Since the oiling system is pressure fed by the PD pump, the same flow through everything is going to continue, and that includes all the journal bearings even though they are not turning because they are pressure fed. Do you agree with that? Or do you think the oil flow will magically stop and all the volume from the pump will pressure relief and shunt to the sump? Tell me what you visualize happening.

 

[ZeeOSix]

Originally Posted By: Shannow
Originally Posted By: ZeeOSix
Originally Posted By: Jetronic
the way to get more oil flow through a bearing (to reduce average bearing temp)) would be to increase the clearance, no?


Or increase the supply pressure to the bearing ... which is the better way. You want to keep the bearing clearance at it's required design number.


Per your posted photos...IF (note that word IF) you can't keep temperatures under control through the normal leakage route of the bearings.

Jetronic,
when designing bearings, it's an iterative process.

Come up with a design, model it, and see what the temperature rise is across it...as it's iterative, takes a few rounds to settle on what it is ultimately...if it's not right, then change something. (not that this is only the short bearing steady state, the bearings will pump more with the oscillations that come from cyclinc load, cumulatively with this.

First mistake ... that design flow chart you show is for only atmospheric fed bearings ... not pressure fed bearings to determine actual flow through the bearing. That has been shown many times now.

If you want to see how the design logic works with pressure fed journal bearings, then look at section 12-11 (starts on page 83) of this bearing design summary:
http://site.iugaza.edu.ps/mhaiba/files/2013/09/CH-12-Lubrication-and-Journal-Bearings2.pdf

And you said above that if the temperature rise is too high, then "change something". Well, what exactly are you going to change in your mind if it's not the oil supply pressure to control the needed flow through the bearing to keep it from over heating?

Originally Posted By: Shannow
And as Per zeeosix...when you can't design your bearings the "IF you can't control temperature", you throw more pump at it, which isn't good design, as it changes everything else in how squirters, hydraulics etc. opperate, and increases parasitic losses.

Which is the VERY REASON that automotive manufacturers are going to variable displacement oil pumps.


You can increase the PD pump output volume to force more oil flow volume through the bearings to cool them adequately, and still control the flow and pressure to other components like squirters, chain tensioners, turbos, lifters, rocker arms, oil coolers, etc, etc by using flow control orifices in the oiling system where needed. Most oiling systems use flow control orifices to give the right component oil flow & pressure to each component.

You do realize I hope that in an engine with a variable displacement oil pump that the whole oiling system is impacted by the pump's variable output. The main reason car manufacturer's are using variable displacement oil pumps is to help cut down on some parasitic HP loss due to the pump. They realize that the bearings and other components don't need as much oil feeding pressure at low engine speeds and low loads compared to higher RPM and loads. The old fashioned PD oil pumps worked just fine, but car manufacturers are trying to save any tiny sliver of fuel economy they can find these days due to imposed regulations on ever increasing required engine fuel efficiency.

 

[Shannow]

It's a dynamic system..."magically stopping" the crankshaft and asking me to visualise a nonsensical case means that you have not got even the simplest understanding of the fluid dynamics in the engine.

What is your problem with the actual curves and pump displacements in an operating engine that you feel such a need to revert back to static pressure and non dynamic engine components ?

You are trying to drag me into an idiotic fantasy argument, and then beat me with your experience in that realm.

And purposely strawmanning my position might work in secret agent engineering, but not real world.



When they AREN'T what's happening ?

 

[ZeeOSix]

Originally Posted By: Shannow
It's a dynamic system..."magically stopping" the crankshaft and asking me to visualise a nonsensical case means that you have not got even the simplest understanding of the fluid dynamics in the engine.


What it actually means is that you can't think outside the box, and basically have no real understanding of a pressurized oiling system that is virtually used in every vehicle on the road.

I knew you'd deflect this example I gave to try and turn on the light bulb, but you won't even try to understand the concept. If the engine was suddenly stopped and all the bearings were still at their running eccentricity position (it's really not hard to visualize), the flow through them would essentially still be the same (minus the very small "sucking" force factor) if the PD pump was still running at the same output and force feeding the bearings.

It's pretty simple, the oiling system is pressure fed - fluids flow from a high pressure to a low pressure, and if pressure is increased so is flow volume - that's the most simple fluids concept ever. I know you don't believe that is how it's working, but it really is, and you haven't shown anything to prove otherwise.

Originally Posted By: Shannow
What is your problem with the actual curves and pump displacements in an operating engine that you feel such a need to revert back to static pressure and non dynamic engine components ?

You are trying to drag me into an idiotic fantasy argument, and then beat me with your experience in that realm.

And purposely strawmanning my position might work in secret agent engineering, but not real world.

When they AREN'T what's happening ?


With all the information I've shown in these discussions, it's pretty clear that the oil flow through a journal bearing is different when the supply is pressurized vs not pressurize. You're stuck in a world where you think bearings "suck" only the oil volume they need from the galleries, regardless of how high of a pressure those galleries are at. If the gallery was at 300 PSI do you think the bearing will flow the same (due to it's "sucking action") as if the gallery was at ATM pressure?

I'm not dragging you into anything ... you've dragged yourself into the realm of wrong, and can't find a way to prove otherwise.

 

[Shannow]

Originally Posted By: ZeeOSix
With all the information I've shown in these discussions, it's pretty clear that the oil flow through a journal bearing is different when the supply is pressurized vs not pressurize. You're stuck in a world where you think bearings "suck" only the oil volume they need from the galleries, regardless of how high of a pressure those galleries are at. If the gallery was at 300 PSI do you think the bearing will flow the same (due to it's "sucking action") as if the gallery was at ATM pressure?


I agree...apply more pressure, and the flow through the unloaded side of the bearing goes up, and temperatures go down...I agree with the papers that you posted that IF you can't get a proper temperature through designing it properly for natural oil flow, you CAN increase pressure to provide increased cooling.

However, the fundamental requirement for an automotive system supplying mains and big ends is to ensure that adequate supply is there to ensure that the bearing's make-up requirements are met (and yes, that includes the pressure required to simply GET it to the conrods in adequate volume).

Your force feeding concept is NOT how automotive bearings are designed.

 

[ZeeOSix]

Originally Posted By: Shannow
Originally Posted By: ZeeOSix
With all the information I've shown in these discussions, it's pretty clear that the oil flow through a journal bearing is different when the supply is pressurized vs not pressurize. You're stuck in a world where you think bearings "suck" only the oil volume they need from the galleries, regardless of how high of a pressure those galleries are at. If the gallery was at 300 PSI do you think the bearing will flow the same (due to it's "sucking action") as if the gallery was at ATM pressure?


I agree...apply more pressure, and the flow through the unloaded side of the bearing goes up, and temperatures go down...I agree with the papers that you posted that IF you can't get a proper temperature through designing it properly for natural oil flow, you CAN increase pressure to provide increased cooling.

However, the fundamental requirement for an automotive system supplying mains and big ends is to ensure that adequate supply is there to ensure that the bearing's make-up requirements are met (and yes, that includes the pressure required to simply GET it to the conrods in adequate volume).

Your force feeding concept is NOT how automotive bearings are designed.


Glad you agree that the supply pressure does certainly change the total flow through the bearing. Higher the pressure, higher the flow if everything else is held constant.

In high HP modern engines the bearings certainly are designed for force feeding with a pressure fed oiling system if it's determined they need certain flow rates to survive. If the temperature rise isn't too high with an un-pressurized system (small low RPM, low HP engines), then just using some kind of simple splash system or whatever to get oil into the bearing at ATM pressure is OK.

That crazy Honda 2.4L V8 is a good example where the designers were using the performance parameters of the oil pump in conjunction with the design of the bearings and other components in the engine to ensure proper pressure & oil flow to everything in the oiling system. That engine wouldn't last 2 minutes at full power levels if the system wasn't pressurized to that 130 PSI they are using.

Small low HP engines used for lawn mowers, etc don't typically use pressure fed oiling systems, so the design of those bearings would fall under the atmospheric oil fed bearing types. The last link I showed for bearing design clearly broke the two types of bearings into separate design logic.
http://site.iugaza.edu.ps/mhaiba/files/2013/09/CH-12-Lubrication-and-Journal-Bearings2.pdf

 

[Ramblejam]

Re: Hydrodynamic Journal Bearings -

http://turbolab.tamu.edu/proc/turboproc/T34/t34-16.pdf

 

[ZeeOSix]

^^^ Somewhat taken out of context, because the part where is says "supply more and the extra oil will fall to the sides and be wasted" just means that the journal bearing is only using the thin film volume it will naturally use while operating, regardless of how much oil supply pressure was put on the bearing. Doesn't mean that some journal bearings still would need pressurized flow, or that the flow is the same regardless of what supply pressure is put on them (it's not). Some bearings will survive without pressurized flow, but almost every vehicle on the road uses a pressurized oiling system which means the bearings are force fed their oil supply, and are flowing more than if they were not pressure fed.

That info really does not agree with all the technical information shown about pressure fed bearings. The first sentence is plain wrong in the case of pressurized bearings. This article is not even addressing how journal bearings flow oil when pressurized. Plenty of design information out there that show how journal bearings flow when pressurized. This one is pretty basic, and shows the equation used to determine flow ... not the pressure term in the equation. If p is increased, so is the flow q.

http://www.mathworks.com/help/physmod/hy...w.mathworks.com

Read all the stuff that's been shown in this discussion - and note the difference on how journal bearings flow oil when pressurized vs not pressurized. It's very clear that if you put 200 PSI on the inlet to a journal bearing that the oil flow through it (per the design equation) will be significantly higher than say supplying oil at only 10 PSI. A bearing supplied with a ATM pressure oil supply will flow the least.

And that quote is wrong about the bearing only flowing what it uses, unless they are specifically talking only about ATM feed bearings. The side leakage is the only volume made up on the supply side while the bearing is in operation with ATM oil pressure supply. With pressurized bearings, the side leakage is huge in comparison because the oil is being forced through the bearing at a much higher volume to keep it cool. As all the design information shows, if the bearing is supplied with pressurized oil it will flow more oil through it as the supply pressure increases.

If you did not supply some journal bearings in high HP, high load engines with pressurized oil to increase their oil flow, they would not last very long.

 

[ZeeOSix]

Also, the last sentence in that paper quote is totally wrong - unless again they are only talking about NON-pressurized journal bearings (which I think they are throughout that paper).

It's been shown in many different design sources (with equations) that increasing oil flow through the bearing with pressurized oil has a huge effect on lowering the temperature rise in the journal bearing because the oil flow is increased to carry away the generated heat.

 

[weasley]

I've been following this debate, over the various threads, with some interest. I can see both sides of the argument and both protagonists have good points, but in the end I sit in Shannow's camp.

Here's a thought for you: if you increase the pump rate to the bearings, and this results in increased flow through the bearings, how does the oil pressure increase? The oil pressure in the system is a direct result of the bearings NOT using all the oil sent to them. The bearings will use whatever oil is available to them, and an increased delivery of oil will be needed for faster spinning bearings to prevent oil starvation or cavitation. Any oil that flows 'through' the bearing as a result of increased pressure is essentially overspill.

 

[ZeeOSix]

Originally Posted By: weasley
Here's a thought for you: if you increase the pump rate to the bearings, and this results in increased flow through the bearings, how does the oil pressure increase?
The oil pressure in the system is a direct result of the bearings NOT using all the oil sent to them. The bearings will use whatever oil is available to them, and an increased delivery of oil will be needed for faster spinning bearings to prevent oil starvation or cavitation. Any oil that flows 'through' the bearing as a result of increased pressure is essentially overspill.


The oil pressure in the system is really the result of the PD oil pump trying to force a certain volume through an overall oiling system flow resistance. As engine RPM increases, the PD pump is rotated faster, and it's volumetric output also increases accordingly. That's why the oil pressure rises near linearly with increased engine RPM. On GM V8s, that is generally about 10 PSI per 1000 RPM.

The bearings will flow more oil volume as the pressure and RPM increase. The PD oil pump needs to be designed to essentially "keep up" with the bearings ability to flow oil as engine RPM increase, and to provide enough gallery pressure to increase bearing flow if added cooling is part of the design. So the PD oil pump volume output as a function of RPM is basically matched to the oiling system to not over feed or under feed the engine components. When the bearings are supplied with good oil pressure in the galleries, they will flow more than they naturally would if not pressure fed, and the main reason to "over feed" them is to help keep them cooler and to prevent the thin film boundary layer from getting too thin from heat and load (ie, high HP outputs), which could cause the film thickness to go to zero and damage the bearing.

 

[Shannow]

Originally Posted By: ZeeOSix
You do realize I hope that in an engine with a variable displacement oil pump that the whole oiling system is impacted by the pump's variable output. The main reason car manufacturer's are using variable displacement oil pumps is to help cut down on some parasitic HP loss due to the pump. They realize that the bearings and other components don't need as much oil feeding pressure at low engine speeds and low loads compared to higher RPM and loads. The old fashioned PD oil pumps worked just fine, but car manufacturers are trying to save any tiny sliver of fuel economy they can find these days due to imposed regulations on ever increasing required engine fuel efficiency.


Bass ackwards Zee0Six...

They don't need the volume at high RPM, as per the bearing design curves that both you and I have posted from different sources, and must therefore agree that's how they work.

Here's the Mellings chart from the link that I posted for your review.

Clearly, more volume per revolution is required at lower speeds, and the volume requirement tapers off at higher speeds, exactly the reverse to your posit if the bearings required overfeeding for temperature control (remember too (again, as they keep dropping off your radar for whatever reason) the big ends too...they are clearly NOT pressure fed per your assertion).

As to the BOP (Balance of Plant in the parlance), yes, they are impacted by Variable displacement oil pumps too...positively as itturns out.

Here's the general design that they follow to achieve the more volume at low RPM, less at high.

Basically they are oversized, and pressure controlled to a constant output pressure.

So things like squirters, phaser and chain tensioners have the right pressure through most of their range...the overpressure that a traditional pump CAN apply to a chain tensioner isn't good for the chain, not parasitic losses.