BMW Patents Its Electric Turbocharger Technology. More Power, Less Lag.

[southlight]

BIMMERPOST NEWS

BMW Patents Its Electric Turbocharger Technology. More Power, Less Lag.

71
COMMENTS

Tweet

Turbochargers are a popular technology in the automotive world as of late. It allows rather low displacement engines to have relatively high power outputs, while also managing to return fairly good fuel consumption figures (on paper).

Despite the technology being decades old, some of its drawbacks could still be improved upon. One of these issues is the well-known problem of turbo size. A smaller turbine spools up quicky but runs out of steam at higher revs while a bigger turbine offers enough power at high revs but often is too slow at lower revs which results in turbo lag.

BMW has now patented its own idea on how to address these issues, and it involves the use of an often rumored "electric turbocharger".

We reported before that BMW has considered (or may still be considering) the use of an electric turbocharger as part of a potential tri-turbo 6-cylinder engine for the next generation F80 M3 (the latest rumors point towards a bi or tri-turbo inline-6 as the new M3's powerplant). While we still don't know if the next gen M3 will be powered by an engine with an electric turbocharger, we do now know how such an electric turbocharger would be implemented, courtesy of a patent application BMW submittted to the German patent office.

First, here's an explanation of the electric turbo's individual parts (as labeled in the diagrams):
1) turbo layout
2) turbine
2') turbine axle
3) compressor
3') compressor axle
4) electric motor (and alternator)
5) turbo axle
6) (turbine axle) clutch
7) (compressor axle) clutch
8) gearing

We've highlighted and colored the following schematic diagrams to show how the technology works:

Unlike a traditional mechanical turbo layout, (exhaust) turbine and (intake) compressor aren't fixed on the same axle. Via the clutches #6 and #7 both the turbine and the compressor can be uncoupled from the turbine axle (#5). When the engine is idling or coasting, both clutches are open and an electric motor (#4) can operate without any load. Via gearing (#8) the speed of of the e-motor and the turbo axle can be further adjusted.

If the driver steps on the pedal the clutch (#7) closes and connects the electric motor (#4) to the compressor (#3). Due to the inertia of the (running!) electric motor, the compressor spools up quickly and compresses enough air to make for a fast engine response, which results in less lag. The turbine (#2) which wouldn't be able to spool up the compressor quickly enough is decoupled due to the clutch (#6) still being open.

Once the turbine (#2) has reached a certain speed, the clutch (#6) closes and both the turbine and the electric engine are used to run the compressor (#3).

When maximum boost is reached, the electric motor switches to an alternator mode, generates power for the battery, and avoids the turbine exceeding a certain speed. This renders a wastegate needless and ensures sure no energy from the turbine is wasted. If the driver backs off the accelerator, both clutches (#6, #7) open and the electric motor can continue running without any load from the turbine or the compressor.


According to BMW's patent application, this invention makes for a great engine response, particularly during the transition from idling to load. It also renders a wastegate needless and adds efficiency. We can't tell if this technology will actually make it into the next M3, but this sounds amazing without any doubt. Thanks to klaus kneip for his tips!

We'll keep you updated on the subject, in the meantime check out our previous coverage and spyshots of the F80 M3: http://www.bimmerpost.com/m3/f30m3/

[han405]

Wow!

[James T. Kirk]

Why is it that these patent drawings always look like Thomas Edison drew them with a straight-edge and quill?

Doesn't anyone at the office have AutoCad?

[M-Power111]

interesting, this will obviousley solve the turbo lag problem. i can def. see this being on the new M3 or atleast i hope it will be. a tri-turbo sounds better then a bi-turbo.

[Jblack4083]

Originally Posted by James T. Kirk

Why is it that these patent drawings always look like Thomas Edison drew them with a straight-edge and quill?

Doesn't anyone at the office have AutoCad?

exactly!

[ES BMW]

I was thinking the same thing about the drawings. It's like the format needs to be as if it were conceived on the underside of a napkin in a bar.

[M-Power111]

Originally Posted by My E90

I was thinking the same thing about the drawings. It's like the format needs to be as if it were conceived on the underside of a napkin in a bar.

its like their stuck in the past. i guess if it works then why update. who knows.

[positiveions]

interesting

[Merlosso]

Originally the rumors were that a tri-turbo set-up would be two traditional turbos and one electric one. Now that we know more about this "electric" turbo, it looks to be an evolution of the turbo that adds electric assist to get it spooling until there is enough exhaust gas to take over. This could allow for the use of bigger turbos without the lag that they are known for.

It seems like this could be used to reduce the number of turbos needed rather than be a supplemental turbo.

It will be interesting to see how these are used and how they perform.

[veightkiller]

It's kinda hard to imagine with all the squares in the drawing.

[taylors335]

sounds great ..... wonder how these clutch's and motor/gearbox will last with the extreme heat turbines can create !

[DDS2015]

Wow this is incredibly brilliant. However, it also sounds overly complex. Also, what will the lifespan of the clutches be? Sounds like it would be a nightmare to fix if something went wrong.

[M-Power111]

Originally Posted by DDS2015

Wow this is incredibly brilliant. However, it also sounds overly complex. Also, what will the lifespan of the clutches be? Sounds like it would be a nightmare to fix if something went wrong.

it sounds like this would be 1 contained unit per turbo, so if something goes wrong they might just swap the whole unit out and yes that does sound expensive.

[kaishang]

Tricky technology

Although turbochargers by definition operate on exhaust gases. So the electric motor is a supercharger. Or the unit can operate as a turbocharger or a supercharger. Or something.

[kaishang]

Also I think I will not queue up to buy a 1st model year example of a BMW with this inside....

[turb0mik3]

This will be fun for HPF to do a single turbo upgrade. LOL.

[sojirovskensi]

Assuming that this tri-turbo technology works, would it be harder to tune than twin-turbo since it involves a technology that most tuners have not experienced so far?

[Mr. ///M3 RD]

Would have expected some nicer up to date drawings for this presentation ... If one of my designers would come up with this simple building block I would have fired him, since every computer in a design department should have SutoCad installed .... Gosh

[Zebra99]

Originally Posted by taylors335

sounds great ..... wonder how these clutch's and motor/gearbox will last with the extreme heat turbines can create !

This will be the new "HPFP" issue, but for the M3's. Can you imagine the headache if this isn't properly test run for years. And it'll cost an arm and leg when it's new, will probably drag up the price for a new M3. I just hope that proper testing is done before they release these cars on the road and another 335i happens.

[rosskie]

Originally Posted by James T. Kirk

Why is it that these patent drawings always look like Thomas Edison drew them with a straight-edge and quill?

Doesn't anyone at the office have AutoCad?

if its very detailed someone can come in and do the same style turbo but different motor or bigger shaft and get away with it.

This way BMW can just say that was our idea u cant use it

[NewYearsBoy]

Originally Posted by James T. Kirk

Why is it that these patent drawings always look like Thomas Edison drew them with a straight-edge and quill?

Doesn't anyone at the office have AutoCad?

Thats probably why they never work...

[Tijuana]

This system sounds awesome for maximizing power and efficiency, which is right up BMW's alley these days. The first thing I think of is KERS from F1 with the energy recovering wastegate replacement.