Variable Flow Gerotor Oil Pump

[WConley]

Most of you guys probably remember my oil pump dyno thread from earlier this year:

http://fepower.net/simplemachinesforum/index.php?topic=9685.0

You're probably saying to yourselves, "This guy must be an incredible nerd with too much time on his hands!  Why go to all of that trouble just to play with oil pump designs that have been around forever?"

FYI you're right about the nerd part    But there's I reason I did this.  Manufacturers are looking for every way possible to squeeze more economy out of our old dinosaur burners.  It turns out the oil pump is a pretty significant parasitic load on an engine.  Oil pumps are designed for the worst-case needs of your engine, like towing a heavy load up a mountain on a hot summer day.  When you're just turnpike cruisin', the engine is producing much less power and heat.  Oil flow can safely be cut by half or less.  This saves parasitic load on the engine and increases cruise fuel economy.

Standard gerotor oil pumps have a fixed oil flow for a given engine rpm, so people have had to go to vane-type pump designs to achieve variable flow independent of rpm.  These pumps work, but they're complex, delicate, and expensive.  They're also very sensitive to oil contamination.  Despite this, Ford went to a variable vane oil pump on the new Godzilla truck engine.  In the video below, Brian Wolfe explains how using a variable flow oil pump got them to their fuel economy goals without resorting to cylinder deactivation or direct injection.  Pretty cool!

https://www.youtube.com/watch?v=CJztLbsQ7Y4

So I got interested in variable flow pumps a couple of years ago.  The goals of my new design would be:

- Simple, durable, and cost effective
- Close as possible to existing "gerotor" pump technology
- Able to handle dirty oil as well as existing gerotor pumps
- Fail-safe design goes to maximum flow if the control fails
- Compact package, as close as possible to existing pump size
- Able to reduce flow (and pump drive power) at least 50%

Those are pretty lofty goals.  It took a couple of years of work, but I got there!  The fun part is that I used an FE oil pump (Melling M-57B) as the base for my first prototype.  The old dog can learn new tricks 

Here's a picture of the prototype pump:



I can't get into too many details on how it works (still too early in the patent process), but you can see a transmission control solenoid on the side of the pump.  The solenoid regulates a hydraulic circuit inside that moves mechanical parts to vary the rotor's flow volume.  I'll try to anticipate some thoughts people may have:

- I am not just dumping excess oil overboard, like auto transmission pumps do.  That's pretty wasteful.

- This is not a variable bypass design that sends extra oil from the output side back to the input.  Those controlled-bypass approaches have already been patented.  They don't seem to work very well, since Ford even bought one fifteen years ago and it has yet to appear in production.  I suspect oil aeration may be an issue based upon my earlier testing...

- Based upon patent searches, this seems to be a unique approach that can massively change the pump's output without adding too much size.

I've spent plenty of time on the test rig with this prototype.  Here are a couple of curves showing min (red) and max (green) flow and pressure.  I'll attach these charts so you can look at them in better detail.  The pump power drops proportionally as the flow and pressure drop:





Here's a shot of the pump mounted to the test rig adapter:



I also developed a little hand-held touchscreen controller to run the pump.  It can set the pressure anywhere within the colored area of those charts.  (There is a minimum and maximum built into the pump at any given speed.  You can't go below the red line or above the green line.  Anything in between is fair game!)  Here's what the controller looks like.  It plugs right into that control solenoid:



Here's a video showing the control working at 4,000 engine rpm.  The tachometer is showing pump rpm, which is 2,000.  When the video starts, the control is off and shows red.  I then touch the button and select different pressures.  You'll notice the rig speeds up a bit when I lower the pressure.  That's because the pump input power drops:

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

Here's a video showing what happens when I disconnect the pump control.  You'll see that the pump instantly reverts to max flow.  At this point it's just like a standard M-57B pump.

https://www.youtube.com/watch?v=rrg5fPuWveM

I tried to make this as short as possible, but it's two years of work.  There was a lot of frustration and plenty of scrap parts along the way.  I don't see a lot of interest from aftermarket guys or racers, since a couple of horsepower in savings isn't a lot.  Besides, when you're pushing it you'll want full oil flow anyway.  Hopefully this attracts the attention of a manufacturer.

I just wanted to share with you guys.  There are lots of smart cookies on here!  I know some of you guys are secretly as nerdy as I am    So, flame away!

Oops - Linked to an incorrect video.  Fixed

[rcodecj]

Very cool! My 19 mustang GT has some sort of variable oil pressure set up. I'm not sure what they're using but it's 15 lbs at idle, 35 going down the road and I forget but 90 or so when revved out.
You can see it bounce up in pressure like you flipped a switch when it hits a certain rpm.

[WConley]

Very cool! My 19 mustang GT has some sort of variable oil pressure set up. I'm not sure what they're using but it's 15 lbs at idle, 35 going down the road and I forget but 90 or so when revved out.
You can see it bounce up in pressure like you flipped a switch when it hits a certain rpm.

I'm not sure they have put a variable flow pump in the Coyote yet, but it sure seems they have the pump output calibrated to be low at cruise. 

I think the next step for me is to develop this approach into a modern crank-mounted pump.  It will work with a hole through the rotors.

[rcodecj]

It is described as having a relief valve.
From the work manual:

Lubrication System

The engine lubrication system is of the force-feed type in which oil is supplied under full pressure to the:

crankshaft main bearings.
crankshaft thrust main bearing.
connecting rod bearings.
oil galleries.
All other parts are lubricated by splash of the oil.

The lubrication system of the 5.0L (4V) engine is designed to provide optimum oil flow to critical components of the engine through its entire operating range. The heart of the system is a positive displacement internal gear oil pump using top seal rotors.

The heart of the system is a positive displacement internal gear oil pump.

Generically, this design is known as a gerotor pump, which operates as follows:

The oil pump is mounted on the front face of the cylinder block.
The inner rotor is piloted on the crankshaft post and is driven through flats on the crankshaft.
System pressure is limited by an integral, internally-vented relief valve which directs the bypassed oil back to the inlet side of the oil pump.
Oil pump displacement has been selected to provide adequate volume to make sure of correct oil pressure both at hot idle and maximum speed.
The relief valve calibration protects the system from excessive pressure during high viscosity conditions.
The relief valve is designed to provide adequate connecting rod bearing lubrication under high-temperature and high-speed conditions.

[GerryP]

I would encourage everyone to watch the videos.  Amazing.  How would the end user know what pressure is appropriate for various situations?

[WConley]

I would encourage everyone to watch the videos.  Amazing.  How would the end user know what pressure is appropriate for various situations?

Gerry -

I'm operating the controller in manual mode during those videos.  I'm planning to test in a vehicle and on a dyno engine later this year.  For a real engine the controller can read engine load (vacuum or throttle position), engine rpm, and oil temperature.  Based upon those inputs the controller will set pressure from a map.

At lower revs, lower loads, and moderate oil temperature, you'd want lower flow.  When you romp it or things get hot, it'll up the flow.

[GerryP]

I was thinking it would have to be controlled by some sort of window switch.  Again, what an awesome accomplishment.  I can see the long haulers finding a home for that pump.  Imagine loping along down the interstate, in overdrive, and 25PSI, not 70PSI.  I would imagine that the pump would also reduce oil temperature since it's not absorbing energy just to make pressure beyond what is necessary.  I would also think that it would result in cleaner oil since at lower pressure and volume, the filter bypass probably isn't opening.

[WConley]

I would imagine that the pump would also reduce oil temperature since it's not absorbing energy just to make pressure beyond what is necessary.

That's a good observation!  My test rig running at 3,000 rpm will heat the oil up past 230 degrees in ten minutes of running at full pressure...

[blykins]

I can't help but think of the performance advantages for it. 

Tuning on the dyno would be awesome.  Oil takes horsepower to move around and it would be nice to be able to dial the pressure down to dial in the horsepower losses.

[winr1]

Nice work Bill !!



Ricky.

[WConley]

Thanks Ricky!  Appreciate the kind words.

- Bill

[Heo]

Interesting, was just thinking the other day what became of your oilpump dynoing

[rcodecj]

Just read the older thread. Learned a lot. Wow. Thanks!

[427John]

This would also be applicable to pretty much any ford distributor driven gerotor oil pump wouldn't it?

[cammerfe]

Bill---
You are one of the reasons this site is worth so much. The quality of your thoughts is directly in line with what we have come to expect from Jay. As I sit here thinking over what I've learned from you over the years, I simply develop a big grin!

Go for it!!

KS