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Hybrid Vehicles Toyota Prius What to expect from the next model year Prius
311 messages, Last post on Apr 26, 2009 at 5:43 AM
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We all know that Toyota, as with other auto companies, is on this track of more power with succeeding models whether the consumer needs it or not. With the Prius the most obvious upgrade is to let the 1NZ-FXE engine run at 6000rpm which should up the power from 76Hp to something around 90Hp with only incremental increases in the electrical equipment. Of course the engine may not be quite so clean at this level but does the DOT testing actually require the engine to touch maximum output over its standard driving cycle, does anybody know ? I have brought this up before that the amount of time that full power is ever used is comparitively small, perhaps the standard should be that when cruising at top speed. But could you even fail a vehicle on its pollution count at 100mph since that condition is beyond posted limits permitted in any state ? T2
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Replying to: toyolla2 (Nov 09, 2007 5:13 pm)
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Replying to: wwest (Nov 09, 2007 8:38 pm) However talking of engine use at max rpms, that is the reason I favor series hybrids. With control of the throttle most drivers will not rev above 4000rpm, so they have this large engine but they never use but two thirds its capacity. With Prius and series hybrids you relinquish that control to the ECU. In return you get, with the Prius, a performance boost not found with stepped transmissions as the engine continuously rises towards its full rpm at 51mph. Instead of capitalising further on this advantage, the industry appears to be looking to use more power to be sourced from batteries. Fom a recent announcement we learn Toyota is supplying two Prius to SoCal universities equipped with larger NiMH packs. I see that as a niche market with the cost of the battery raising the hybrid premium. Alternatively, I would like to see the Fiat 900cc two-cylinder engine style, from the Panda Aria concept that's scheduled for 2010 I believe, installed in the next design of Prius. It has 25% less weight and 20% more FE over the small four usually fitted to that Fiat vehicle. Fiat is working on a 65Hp naturally aspirated version but the turbocharged 105Hp is good to go. I can only guess that the higher CR used on the lesser engine is giving a NOX issue. Fewer cylinders would provide a needed cost reduction on the Prius. I would quite believe that the machining operations are similar in inline fours such that the price delta between 1.5L and 2.4L engines is quite small. It is going to need something like less cylinders to make a difference. They used to say about small engines 'a different hill needed a different gear'. The Prius servos with their ability to supply the exact ratio needed for the load torque at any point in time would seem ideally suited to these two-cylinder engines. T2
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Replying to: sailorman4 (Oct 26, 2007 6:24 pm) I hope you bought carbon offset credits for the flight. ha!  Just kidding, of course, but that joke works on so many levels, I couldn't resist! |
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Replying to: toyolla2 (Nov 12, 2007 11:48 am) The test vehicles are here to evaluate the usefulness of the extended range on EV only, to see if it is really worth the extra cost, in an urban setting. They are also evaluating the use of the plug-in feature, to see how that translates to reduced emissions, again, in a US urban setting, and the Japanese ones in their urban setting. It's hard for the engineers to know exactly how such a vehicle would be used, as that is different in different cultures, so these tests are to gather data on that.
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Replying to: toyolla2 (Nov 12, 2007 11:48 am) If it were possible to build a commercially-viable series hybrid, I think Toyota would already have done it. I hear lots of hype about series hybrids, but have yet to see an actual implementation, except for (I think) diesel train engines. Do you have any links to post for anyone who has ever produced such a auto comercially?
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Replying to: stevedebi (Nov 12, 2007 1:59 pm) http://www.azuredynamics.com/november262004b.htm Azure were working a deal in the UK with London Taxis International to supply them with a series hybrid cab. At least one was built and shipped from their plant in Vancouver, BC. Later on LTI introduced their new "Black Cab" for London's downtown. Said vehicle turned out to be a 2.2L diesel with automatic transmission. That's right, someone gave the greenlight to mixing thousands of diesel engines in one of the most populated areas in England, go figure. This particular action seemed hardly consistent with government policy to reduce air pollution in urban settings. A while later Azure closed their UK office. Azure Dynamics is a division of Ballard Power Systems. Last week Ballard announced the sale of its automotive fuel cell division. In the meantime it must have been somewhat embarrasing for Azure to learn that the highest mileage hybrid was in fact a Vancouver taxi in the form of a Toyota Prius, which had been running around in their own backyard. T2
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Replying to: pathstar1 (Nov 12, 2007 12:46 pm)  Regarding power limitation, you are probably aware the Prius - with software changes - could reach 60 mph using the nominal 21kw without actually overspeeding MG1 but is seven miles of this continuous type of operation going to be tolerable to the PSD ? Else it will be interesting to see how many opportunities there are to drive below 42mph for the extended range. T2
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Replying to: toyolla2 (Nov 13, 2007 10:35 am) As for low temps, I don't think -10 C would be too bad. I've not seen any problems with the "traction battery" so far, but I've also only seen -5C (this will be Pearl's first winter). Once you start using the battery it quickly warms up, and it only has to start the ICE at first.Others with more winter experience have not had problems with the "traction battery", it's been the 12V one that has failed them. We shall see. Now once the temp gets down below -40C (or F - they are about the same) then it gets interesting. THAT is when we start having battery problems with lead acid ones. At least the NiMH battery won't freeze at those temps.! It takes a lot of current to turn over an engine when the oil is that cold. It kind of tends to become molasses. I'm referring to the oil in the HSD, as the engine oil can be 5W30 synthetic (what I'm using) and it flows pretty well, even at -40. Yuck, thanks for reminding me what I'm going to experience in the next few months!
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Replying to: pathstar1 (Nov 13, 2007 12:14 pm) I think it's documented and confirmed by scantool that MG2's controller will current limit to a battery bus draw of 100 Amps. The two packs should share this current since the volt drop in their internal impedances may force a current equalising effect, not perfect but close enough for new packs and in the short term. I don't want to debate whether this is a good idea for reliability going forwards, perhaps not. But right now this is a test about the human interface response to an extended driving range. MG2 will have benefit from the upconverter that normally transforms the 201v pack voltage towards 500v as the vehicle goes from 20mph to 50mph, of which you may have forgotten. So connecting packs in series is not an issue here. As the vehicle gains speed over this range the current will have to reduce inversely of course to observe the nominal 21kw limitation on battery power specified with the Gen II Prius (NHW-20). And I suppose it goes without saying that as long as 21kw exceeds the power needed to cruise, the vehicle will continue to accelerate. You've not addressed my concern of MG1 approaching 10,000rpm as the vehicle nears 60mph which may setup an audible whine. This speed was promised earlier for the Li-ion pack which is why I bring it up. Have you seen these ? The following contain useful temperature / power graphs For CY1997-2000 NHW-10 Prius, 7.2V X 40 modules (cylindrical) For CY2000-2003 NHW-11 Prius, 7.2V X 38 modules (old prismatic) (They used to have a comparison page, but it was gone.) For CY2003-2005 NHW-20 Prius, 7.2V X 28 modules (new prismatic) For CY2005 HH/RX400h, 9.6V X 30 modules (metal prismatic) T2 |
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