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11-13-2011, 11:07 AM | #46 |
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exactly...would be foolish to make it all nice for everyone to see and copy before they even make it
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12-07-2011, 01:11 AM | #47 |
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A +3 (or 4 or whatever) on the cheesy drawings. Patent drawings DO NOT have to be hand drawn nor of any specific format. Certainly the comments about the less detail and the broader the scope apply, but come on hand drawn, really, by BMW...
That being said this could very well be the goodbye to turbo lag.
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05-21-2012, 08:21 PM | #49 |
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This idea goes back at least several decades.
The idea of an electric turbocharger goes back at least several decades. The Russians used an electric motor/alternator coupled to a standard turbocharger on an aircraft engine (diesel) back in the 80s. I don't believe that BMW has the patent on the idea of en electric turbo, just the specific setup using the various clutches. It may even be that the only reason for the clutches was to get around the Russian invention, or to allow BMW to give the impression that they had some important IP for electric turbos.
Ultimately the idea goes all the way back to the turbo compound aircraft engines used on post WW2 piston engine airliners. In these engines the turbo is actually used to convert some of the waste energy in the exhaust power back to the engine/propellor (and of course also to power the turbosupercharger). In the turbo compound engines they used gears to feed the power back to the engine rather than the motor generator used on the Russian and BMW systems. These gears were the Achilles heal of the turbo compound engine because it was very difficult to build gearing systems that could match the very high RPM of the turbo to the very low RPM of the big radial engines of the day. A single backfire could tear up the gears, but even barring such a failure the gears were constantly getting beaten by the huge power pulses of the slow turning engine. The Russian application was the first I have seen that used a motor generator to harness some of the waste energy (energy not used by the turbo itself). I am not sure why BMW needs all the clutches and other stuff but perhaps they found that they got somewhat better efficiency under the varying loads of a car vs. the much more constant load in an airplane that the Russian system was meant for. |
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05-22-2012, 07:12 AM | #50 | |
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perhaps now that gearbox management is by computer and is more intelligent than any human it might work but.... |
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05-24-2012, 02:11 PM | #51 | |
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Yeah it seems to me that the clutches are key to why this is such a good electric turbo application. Btw, it's not just old airplane engines, but many auto component companies have been exploring electric turbos for a few years now. Some of them completely separate the turbine from the compressor so they are only connected by electrical wiring, some use an electric motor to help spin up a traditional turbocharger.
The specific benefits of this BMW design seem to be: -disengaging the turbine during coasting, idling, and launch means the exhaust can spin the turbine to a higher RPM and leave more energy for possible further turbos in a sequential setup to also spin to a higher RPM because it doesn't have to waste energy spinning the compressor (which wouldn't even create boost at that low engine speed, nor would boost be desirable even if it could). -disengaging the compressor (along with the turbine) during coast and idle means that the electric motor can pre-spool to very high RPM while using relatively little energy because it doesn't have to waste any energy spinning the turbine or compressor around. -Compared to the purely electric turbo concepts, the BMW design only requires one motor/generator versus having a dedicated motor and a dedicated generator, and maintaining the mode where you have a direct mechanical link between the turbine and compressor should be more efficient than having to convert pneumatic energy>mechanical energy>electrical energy>mechanical energy>pneumatic energy. Quote:
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06-13-2012, 07:47 AM | #52 |
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There is only one reason for this and it is to put it in the m3. Eventually, you will see it used across the board in all turbo charged BMW's giving better gas mileage as a result.
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06-13-2012, 08:39 AM | #53 |
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09-17-2012, 10:00 AM | #55 |
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I want to knwo how easy this will be to add the electric turbo to other engines, such as the n52
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09-17-2012, 10:35 AM | #56 |
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Sorry, but there is no electric turbo on the N57S, just 3 conventional turbos that are brought on-line at different points in the RPM range.
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09-23-2012, 02:37 PM | #57 |
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07-01-2013, 12:49 PM | #59 | ||
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Just found this thread and it seems to confirm that something similar to what will be seen i F1 next year might be on the M3/M4:
Of particular interest is the MGU-H (Motor Generator Unit - Heat) that is attached to the turbo: Quote:
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Any rumours of a electric turbocharger on the next M3/M4 might be a similar device as shown here, to spool up the turbos, or slow it down instead of using a wastegate to dump excess exhaust. Source: http://www.renaultsport.com/Nouvelle...Energy-F1.html Here is MagnetiMarelli's version of a "electric/hybrid" turbo. TThey have chosen a slightly different solution with the generator/motor unit between the compressor and turbine units of the turbo. Seems like Mercedes is using a variant of this solution as well. BTW, this is what next years F1 engine will sound like: |
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07-01-2013, 01:01 PM | #60 |
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If BMW did something like this for the M3/M4 it would make it a really unique engine. I think this would be great and it would potentially represent the next leap forward with FI engines.
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07-03-2013, 08:10 AM | #61 |
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11-16-2014, 05:32 AM | #62 | |
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However if you want to add the complexity and weight of a hybrid drivetrain to the engine (crank) you need sufficient battery capacity to make it work for more than a few seconds a time. The weight of the electric motor, and the necessary coupling/transmission to connect the electric motor to the crank, isn't that different if you have a 30kW or 90kW motor added. And, if you choose to add a hybrid drivetrain then you want to make the most out of the weight penalty that follows from this. For instance the McLaren P1 has a 130kW/177hp e-motor, the Porsche 918 a 94kW/128hp and the LaFerrari a 118kW/161hp e-motor. And even a Prius has a 49kW/67hp e-motor. Look at a Prius and you see that the hybrid drivetrain adds weight and complexity, even at that low power output... And with very little gain in performance... Picture illustrating what's involved in the hybrid drivetrain, in addition to the combustion engine and transmission, on a Prius: If you really want to add the weight and complexity of a hybrid drivetrain, you also want to add enough kW/hp from the e-motor to the drivetrain to make a noticeable difference in performance. And, even a e-motor to spool up the turbo needs a separate high voltage battery system. For instance a modest 2kW output at 12V would need 167Amps... Studies from 2006 by Garret on the viability of a "e-turbo" showed that a single turbo was preferrable since that required a 2,1kW motor, while a twin turbo set up required two 1,4kW motors. The study also showed that under normal driving conditions there wasn't enough exhaust gas flow to sufficiently take advantage of the e-motor attached to the turbo as a generator. Implying that the batteries would need charging in addition to the charge available from the e-motor. I personally find the e-turbo tech very fascinationg and hope to see that employed in road cars soon. But, this is getting seriously off topic now. I suggest that the hybrid/turbo material/tech discussion is either closed now, or continues in a dedicated thread (like in one of the old threads that discussed hybrid turbo tech in depth). |
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11-16-2014, 05:32 AM | #63 | ||
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And one of the main points besides turbo spool up, is to harvest electrical energy from the otherwise wasted exhaust gases. This is what the MGU-H does on the current F1 engines. MGU-H means Motor Generator Unit -Heat (heat as in exhaust gases). The MGU-H serves a dual purpose. It works as a motor and spools the turbo when boost is needed quickly, and it serves as a wastegate by braking the turbine shaft, thereby harvesting electrical energy while operating as a generator. This works great on a engine that spends most of the time either on 0% throttle or 100% throttle. On a daily driver the throttle is much more often on part throttle and too little exhaust gas flows through the turbo for the MGU-H to be able to harvest energy from the exhaust gases... I have uploaded the Garrett PDF file as an attachment. Here is presentation from 2003 that I just found on the subject: http://energy.gov/sites/prod/files/2...eer_shahed.pdf An SAE article https://www.sae.org/automag/features...1-113-9-86.pdf |
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11-16-2014, 05:33 AM | #64 | |
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11-16-2014, 01:28 PM | #65 |
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Check out phantom electric superchargers. They are using electric motors to drive centrifugal compressors.
They have dyno proven results in several types of cars. Unfortunately the systems are rather small however I wonder if two systems one for each turbo could work on the S55. Compounding turbo technology could be an alternate to turbo upgrades, by pre-pressurizing the air charge the pressure ratios are multiplied and the stock turbos can produce higher than normal boost pressures more efficiently. Thoughts? |
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11-16-2014, 02:39 PM | #66 |
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I thought this all initially sounded good but looking deeper the advantages seem to be unavailable from such a system under real world conditions.
Using electricity to drive the T/C at low engine speeds will help reduce lag but the electricity has to come from somewhere, unless you are driving with sufficient load after pulling away (a situation where a normal waste gate would be opening) there can be no electric generation without slowing the turbo, the charge used for spooling the turbo will need to be replenished from the vehicles electrical system. Conversely If you are driving under high loads where you have plenty of excess exhaust to drive the generator this charge needs to be stored somewhere, should the battery reach a state of full charge you have no facility to stop the turbo over spooling unless the waste gate is retained. Based on this it would seem that the battery sizing and initial charge state would need to be tailored to the actual driving conditions the vehicle is about to experience to be fully effective. Other manufacturers have had success with combined turbo+supercharging which removes the need for the (heavy) batteries these systems would require. The supercharger is clutched in only at low rpm before the turbo spools up or under heavy throttle for increased performance, so as to minimize power taken from the engine. Ultimately though, I feel that the anti lag system employed in the S55 (even though I'm not really sure quite how this works) is sufficient to render the concept of electric turbos redundant. The electric supercharging concept mentioned in the previous post may be suitable as a performance upgrade but you would have to consider the size/weight of any batteries required to run this for any sustained length of time. A mechanical supercharger would be a more efficient option should you consider using the vehicles existing (or upgraded) electrical system as you cut out the losses associated with turning mechanical energy to electrical energy, electrical resistance and then turning it back to mechanical energy again. An alternative idea would be to use the electrical supercharger like a rechargeable NOS system, having a much smaller battery being trickle charged from the vehicle when not in use but giving a short term bump in power at the push of a button, only when "needed", before waiting for the battery to recharge. |
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