New BMW 3 series Oil Pump

[SEBZX79]

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Ray H
It's not magnesium-aluminum alloy. BMW figured out how to cast a magnesium alloy outer casing around an inner aluminum cylinder block - in effect an aluminum block with a magnesium outer "block" with the coolant jacket seperating them. Given the different expansion rates of the dissimilar metals, it'll be interesting to see how well BMW anticipated and managed potential long-term sealing problems where the aluminum head and the dual metal block mate."

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That is what it suppose to sound like. After reading my reply just know it did not. Doing too many things at once here at work.

Yes it the outer casting that is Mag with a Alum inters. They are using some trick stuff on the new 3 will see how it holds up.

 

[segfault]

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Originally posted by moribundman:

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I'm sure there is some sort of fail-safe. The 2006 3-series also does not have a dipstick, you check the oil level from the on-board computer

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If the electric pump fails, what fail-safe could there possibly be?

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An error message on the dash telling you to stop as soon as possible, with blinking lights and sounds? I find it hard to believe that they overlooked the possibility of pump failure.

 

[punisher]

Good article. The electric pumps are used to transfer oil to the main sump when lateral ecceleration is >.6G. The oil pump itself looks like a standard mechanical variable displacement (a la transmission pumps as indicated in a previous post). Good idea on the main pump as it should reduce pump losses. I know the old style gear/gearotor pumps eat HP, I lost enough bronze distributor gears racing bigblocks.

 

[moribundman]

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An error message on the dash telling you to stop as soon as possible, with blinking lights and sounds? I find it hard to believe that they overlooked the possibility of pump failure.

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A blinking light and buzzer won't prevent your motor from seizing, so it's not a fail-safe, but only a warning with an extreme short-term deadline!I know how it feels to lose oil pressure at 120 mph and being bombarded with beeps and blinking lights, and it ain't pretty.

I'm not claiming an electrically powered oil pump is less reliable than a mechanical one, but I wonder. Mechanical oil pumps rarely suffer sudden, catastrophic failure. On an electric oil pump the electronics can fail in addition to the mechanical parts.

 

[JohnnyG]

Gee! After reading all of this, all they would have to do now is make it a "georotor" design so it won't shear oil as quickly and they'd REALLY have something! Oh wait, GM has been doing that for years...it can't be any good.

 

[shanneba]

If a light can be turned on when the pump fails, I wonder if they haven't just added a subroutine to the management software that shuts off the engine. They do have their "BMW asist" that will call for help and relay failure information to your dealer.
They also have removed the water temp gauge in the E90 3 series.

How much of this technology is coming from their F1 racing? They monitor everything on those cars.

 

[joatmon]

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Originally posted by SEBZX79:
"

quote:

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Ray H
It's not magnesium-aluminum alloy. BMW figured out how to cast a magnesium alloy outer casing around an inner aluminum cylinder block - in effect an aluminum block with a magnesium outer "block" with the coolant jacket seperating them. Given the different expansion rates of the dissimilar metals, it'll be interesting to see how well BMW anticipated and managed potential long-term sealing problems where the aluminum head and the dual metal block mate."

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That is what it suppose to sound like. After reading my reply just know it did not. Doing too many things at once here at work.

Yes it the outer casting that is Mag with a Alum inters. They are using some trick stuff on the new 3 will see how it holds up.

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Not only the 3, but the 5 as well. The 2006 5 series is already on the street with the same technology. Confidence or ????

 

[haley10]

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Originally posted by Jay:
I don't see how an electric oil pump would be more efficient than a mechanical one. If you look at the efficiency curves of a typical automotive alternator, best efficiency is about 25%--and that's at high rpm. At lower rpm, efficiency falls to 10% to 15%. Combined with the inefficiency of the electric motor of the pump, I don't see how you come out ahead.

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Food for thought, I guess. Electric brakes are rumored to be in the near future and 48V systems.

I once built a test stand for small aircraft alternators w/ 100A load. It took a 7.5 Hp electric motor to suffice. The motor was fully loaded.

 

[Gary Allan]

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the pop-off valve simply diverts more and more oil directly back to the crank case--wasting 3.25 times as much energy as required.

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Well, you may rethink that a little. I imagine that, once the relief is breached, the additional hp antenuates ..somewhat ..from that point on. I feel that it would be limited only to the additional power to move the mass of the vanes faster.

This is, naturally, just my offering of alternative thought.

However, a variable speed pump (also positive displacement) that would maintain a given pressure spec would be more advanced. What "real savings" it yields will be marginal.

I think that this will act as more of a "pressure dependant facilitator" than anything else. Downstream devices (cam phasers, etc.) can be more easily designed to react to pressure ..and any feedback loops can alter the oil flow accordingly to input from the PCM. An electronically controlled electric pump would be one way to achieve this type of interactive control of those functions.

 

[Mitch Alsup]

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Originally posted by Gary Allan:

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the pop-off valve simply diverts more and more oil directly back to the crank case--wasting 3.25 times as much energy as required.

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Well, you may rethink that a little. I imagine that, once the relief is breached, the additional hp antenuates ..somewhat ..from that point on. I feel that it would be limited only to the additional power to move the mass of the vanes faster.

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I suspect the math goes something like this:

The pressure drop from the pressureized side of the pump to the crank case side of the pop-off valve is rather constant while the pop-off valve is open.

The volume goes up with RPMs since this is a positive displacement pump and then engine requires a relatively constant amount of oil at supply pressure of x.

Therefore with the pop-off valve open the amount of energy consumed by pumping oil from the crankcase to the crankcase through the pop-off valve goes up rather linearly with RPMs. Even while the engine is getting a rather constant amount of oil pumped through it (at constant pressure).

Note: the amount of energy running the pumping of the oil through the engine is not part of this calculation. We are only talking about the energy of pumping the excess oil through the pop-off valve. That is, the energy that can be recovered or not consumed by better pumping strategies.

quote:

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This is, naturally, just my offering of alternative thought.

However, a variable speed pump (also positive displacement) that would maintain a given pressure spec would be more advanced. What "real savings" it yields will be marginal.

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I suspect the gains are small enough that no credible engineering team attempted this kind of oil pumping strategy before the advent of computerized electronic motors/monitoring.

quote:

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I think that this will act as more of a "pressure dependant facilitator" than anything else. Downstream devices (cam phasers, etc.) can be more easily designed to react to pressure ..and any feedback loops can alter the oil flow accordingly to input from the PCM. An electronically controlled electric pump would be one way to achieve this type of interactive control of those functions.

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It is highly likely that more constant pressure to the various oil pressure actuators will make the timing of variable cams more accurate and could lead to more HP and TQ at the output shaft. Maybe enven enough to justify 'alternate' pumping strategies.

However, I suspect a pressure regulator for the variable cam phasers would be at least as cost effective and at least as control effective.

 

[jaj]

Mitch

My 2003 BMW M5 engine has an electric oil pump to provide the 1400 PSI oil pressure to operate the M DUAL-VANOS variable valve timing equipment on the front of the camshafts. The regular lube circuits are run by the regular, chain-driven, positive displacement pump.

BMW doesn't publicize it's presence, but if you can access the factory maintenance and parts CD, it's there.

Cheers
JJ

 

[1maniac]

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Block is cast of a titanium-aluminum alloy.

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Yep, BMW goes hi tech on the block. However, I remember when the "Nikasil" block was high tech. That was untill the sulfur in american gasoline ate away at the nickel causing the need for engine replacement in the 4.0 V8 engines. Of course this was in the mid 1990's and in the 5 series and 7 series.

 

[Mitch Alsup]

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Originally posted by Jay:
I don't see how an electric oil pump would be more efficient than a mechanical one.

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The electric pump only pumps enough oil for the lubrication duties. The mechanical pump pumps this much oil and then all the oil that runs out of the pop-off valve (which can be 3X as much oil as runs through the galleys). So, instead of governing oil pressure/flow with a pop off valve, you govern the oil pressure/flow by the pressure guage.

My Ferrari (fully warmed up but operating on the street) reaches maximum oil pressure: 100 PSI at 2000 RPMs and stays there through 8,750 RPMs. So while the (positive displacement) oil pumps (3) pump 4.25 times as much actual oil at 8,750 RPMs, the pop-off valve simply diverts more and more oil directly back to the crank case--wasting 3.25 times as much energy as required.

 

[Gary Allan]

quote:

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I suspect the math goes something like this:

The pressure drop from the pressureized side of the pump to the crank case side of the pop-off valve is rather constant while the pop-off valve is open.

The volume goes up with RPMs since this is a positive displacement pump and then engine requires a relatively constant amount of oil at supply pressure of x.

Therefore with the pop-off valve open the amount of energy consumed by pumping oil from the crankcase to the crankcase through the pop-off valve goes up rather linearly with RPMs. Even while the engine is getting a rather constant amount of oil pumped through it (at constant pressure).

Note: the amount of energy running the pumping of the oil through the engine is not part of this calculation. We are only talking about the energy of pumping the excess oil through the pop-off valve. That is, the energy that can be recovered or not consumed by better pumping strategies.

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Well, I won't critique all of it ..but typically the oil isn't pumped from the crankcase to the crankcase. It's merely shunted back to the suction side of the pump ..sort of a regenerative loop. This is the case with many. That is, the volume shunted ..is volume not subjected to the verticle column of being drawn from the sump. Subsequently you have an effective throughput of the pump drawing only want the engine is receiving from the sump. So, in many installations ..it should be merely a slight increase over the mass of the vanes or rotors in lost hp. I think, however different our views appear ..that we're somewhat in agreement (although it really takes a moment or two to figure that out).


But .... let's not allow these minor matters of despute hinder our further exploration of this wonderous evolution in state of the art lubrication.

 

[segfault]

The new 3-series sales literature contains reference only to a "new type" of variable-volume oil pump, and does not specify whether it is electrical, mechanical, or a combination of the two. It does mention the electrically-driven water pump. The copy of the owner's manual that I have makes no mention of any technical details of the oil system other than the oil capacity and oil specification. I am not sure we have enough information to draw conclusions here. Can someone with a TIS subscription or other inside knowledge confirm that the oiling system is exclusively electric?

 

[Carmudgeon]

From the E90 PR:

Variable-volume oil pump.

Conventional oil pumps deliver oil in direct proportion to engine speed. In order to supply the necessary pressure to the VANOS system (which employs oil pressure to adjust the camshafts and thus vary valve timing) at all speeds and temperatures without excess capacity at high engine speeds, BMW engineers developed a new type of oil pump. By varying the output of its pump element according to engine oil pressure, the engineers achieved a pump that always delivers sufficient pressure to lubricate the engine and operate the VANOS, yet never pumps more oil than is necessary. Thus it –

• Contributes to the engine’s increased power output, by requiring less power from the engine.
• Doesn’t require a bypass to divert excess flow, which can be up to 80% with a conventional pump. This also avoids possible excess oil temperatures and oil foaming.

Oil/coolant heat exchanger.

Another feature that speeds engine warmup; during this phase of operation, it transfers heat from the coolant to the oil circuit. Under conditions of high engine power and high oil temperatures, it performs the reverse, transferring heat from the oil circuit to the coolant, from which the engine cooling system then removes excess heat.

Here's the OEM's page on the pump:

http://www.unitech.at/index.asp?page=products&product_id=117&division_id=1&category_id=6