This is T2's Typepad Profile.
Join Typepad and start following T2's activity
Join Now!
Already a member? Sign In
T2
Recent Activity
Many years ago I looked at this problem. The hydraulics lab happened to have had a free piston engine dating from 1964. One thing for sure, that device certainly was noisy when running. And just like hydrogen fuel cells - as someone noted here - it will be tomorrows solution. ALWAYS. But it forces you to appreciate rotary motion all the more. However regarding rotating pulsating energy systems, the current practice is to use a crankshaft flywheel and a damper disk to smooth pulsations to a 3-phase generator which of course would prefer a constant torque input delivery. Noting that flywheels and damper disks are large and not inexpensive there must be some way to eliminate both these middlemen ! The mechanically "stiff" flywheel is not sympathetic to pulsating power and despite the use of a damper disk it is the cause of subsequent engine vibration. An idea I suggest is to electronically switch the rectifier tank circuit of the generator so that it would efficiently absorb the energy into an LC network and provide more of a dampening effect to the crankshaft. Basically you are understanding and accepting that the adiabatic expansion that forces the piston down the cylinder bore must be received with a counterbalancing electromagnetic force. A mechanical phasor would be required initially in the lab - the printing industry has used double planetaries for colour registration for many years - to align the generator magnetic poles on the rotor with the point of maximum thrust from the crankshaft. Consider that a single cylinder engine will provide one mechanical power pulse every 720 degrees. Consider also that a two pole single phase generator will absorb one mechanical power pulse every 180 degrees. Clearly one match would be to use a 4:1 reducer gear between the engine and the generator. Or one could take a four cylinder engine which would provide one mechanical power pulse every 180 degrees and therefore directly connect it to the generator.
Ferrite magnets ? It occurred to me that maybe we are misconceptioning the use of ferrite here. My familiarity with ferrite in applications is with high frequency transformers, specifically for its low hysterisis loss at high frequency, certainly not for its flux density or remanence. So that would make ferrite not a good candidate, I would think, to utilise on the rotor of a synchronous motor. However its use as stator material particularly at excitation frequencies approaching 600Hz would be an entirely different matter, especially since the stator is a lot easier to apply methods for cooling. Of course you would be looking at 18000 rpm with 4 pole machines although I would not rule out 6 pole machines for increased torque as long as the extra thermal load can be mitigated. My own preference is for the use of silicon steel since it will support flux densities up to 3X those of ferrite i.e. ~ 1.2T. I won't dispute the 2% efficiency advantage over ordinary induction motors, frankbank, but I wonder whether that figure allows for the fact that Field Oriented Controllers will automatically decrease the applied V/Hz on the stator when it is detected that the vehicle has attained its cruising speed and thus significantly reduce stator iron losses. Finally in the bigger picture, incremental aero losses at the upper speed range are more significant than motor efficiency. The problem is to find the most meaningful way to inform the driver. A Watt-hr per mile display doesn't quite cut it. Who knows what that figure should be ? Even the amperage is not the best indicator for the average driver as it will vary from vehicle to vehicle. OTOH if the expected Watt-hr per mile at 60mph, say, could be represented as 100% then at other vehicle speeds above/below this then specific consumption rate could be displayed as a percentage. The value rising above 100% as the driver slows down or falling below 100% as the driver begins to exceed 60mph. The hope is that the effect of the cube law on aero would be more dramatic in its presentation.
From 2011-2014 eh ! You can believe all the propaganda you want about this being a European effort but I see this predominantly as a German rebuttal to Elon Musk's Tesla Model S powertrain. Just 60kw today but obviously they will be scaling it up so that Merc, Audi and BMW will have something to fight with - when the time comes. Personally I believe they are already late for this party and the only thing I see holding back Tesla sales would be Teutonic Pride. Low cost powertrain packaging in the car is only one front they will have to defend. Not to forget that a good many of the 'no fee' superchargers have now been installed across Germany and the Bavarian region, prospective Tesla owners, like anyone else, will find the ability to avail themselves of this "Free stuff" compelling. Induction motors are the way to go since they are more resilient to high temperatures allowing them to tolerate a higher power density. Sure at low revs they don't compete well with magnet machines which provide flux fields with zero power loss. However the copper loss they incur to maintain unit torque remains constant, so as the induction motor spins up this loss becomes a smaller and smaller component of the increasing power being developed, ipso facto efficiency will improve proportionally with increasing rotational speed. I have found that the big problem is getting people to understand this since they are educated in an academia which is immmersed in the 60Hz world where slip is often referred to as a percentage rather than a constant which it in fact happens to be.
Herman, I could have been persuaded but a closer look at the KERS unit convinced me that their unit cannot possibly be manufactured for anything like $2000. But even if it was, there are still some serious doubts in my mind now that I think about it. A 60mph to rest energy capture is only about 600MJ in a Prius sized vehicle and that's if you can capture energy at an initial peak rate of 240Kw. And it pre-supposes you are going to be able to re-use that energy before the flywheel spins down. On the race track that is not a problem but in real life... ? Then there are these considerations at play. First, only the rear axle where the KERS mounts can actually harvest kinetic energy. Second, wheel skid would definitely occur if the system attempted to recuperate half of the KE (300MJ) in a reasonable short space of time. Third, it is only the front axle that has the ability to do any wild braking bearing in mind that the vehicle will attempt to stand on its nose during a severe emergency braking manouvre thus removing the downward pressure at the rear and therefore the wheel friction that the rear tires could exert. It also begs the question. How simple and reliable can a transmission be, that is able to slow down one mechanical system while speeding up another and shortly after have the capability to do the opposite ? Obviously this is race car technology that is looking for application in the mass automobile market. But where ? With an EV handling large amounts of regenerated power suddenly is never a problem. Whereas with a hybrid, braking power of only 10Kw seems to have significantly reduced brake wear, even though owners say it probably satisfies only 95% of braking opportunities.
In electric only mode 75mph is max speed. Makes sense because aero losses start to get huge at that speed and a 5.2Kwhr pack won't last beyond 20 minutes putting out 12Kw. Stretching any electric motor out to 255km/hr demands a twin ratio gearbox I would think but there is no mention of one. Unfortunately the i8 will not be allowed in the Californian HOV lanes with a single driver since the white stickers have now whittled down to 40,000 presently. I would think that by the time the i8 reaches the North American market sales of existing hybrids will have used them all up. BMW is now behind the curve. If they had pretensions of bringing a sports car to these shores they should have got focussed on the e8 that was racing around the Nurburgring last year. I have found that most people are still not aware of the Tesla Model S and that's probably the case in Germany also. That said, with superchargers strung across Germany the expected sales of the i8 are likely to be shortlived when that realization hits home.
I hope the future is likely to be nowhere near as bleak as you are posting here. There are less onerous forms of transport available until walking becomes the only option left. Many will discover the utility of electrically assisted bicycles. The ability of the bicycle to carry 100lbs of cargo with panier bags will be appreciated as it takes only a small amount of extra effort. I also expect to see road infrastructure include dedicated bike lanes supplemented by plexiglass screens for reducing exposure to inclement weather and providing separation from the faster motorised traffic.
Powering 4 wheels all the time is an inefficient use of energy. Basis for this statement ?
I agree with henrik, Tesla will not be going the complexity route with gasoline engines. Musk has this mantra to reduce mechanical complexity of things which have significant reliability issues and replace them with highly complex electronic systems which do not. This explains the high growth of this company which has not been thwarted by major service issues. Sure there are 8000 cells in each pack but they are identical and their mounting does not require accurate dimensions to be maintained between each one in order to function correctly. Musk has identified the central electricity generation model to be a weak game. Their model should have included battery farms located in the immediate vicinity of their customers. These load centres would not only permit the use of lower capacity feeder lines from remote generators through load levelling but also insurance against power interruptions posed by natural causes e.g the recent ice storms. Although it is true that large batteries provide large power capability, so why not every car 185Kw ? The answer to that is that there should be performance differentiators as you go down market. Limiting top speed to 75mph, for instance will allow a higher reducer ratio from 8 to 12 say, and this will allow a smaller frame size motor without effecting acceleration ramps too much, even so I see 8 second ramps to be quite achievable at the lower price points. I would be disappointed if the horsepower race continues with electric vehicles before the range issues are improved. Quite frankly aerodynamics dictate that continuous operation above 70mph for an electric vehicle is somewhat counterproductive.
1. Stipulate HOV lanes. 2. Allow access to BEVs regardless of occupancy. Problem solved
-Henrik that should of course read - 25,000,000/255,500 = 97.8 gallons of ethanol per ton of feedstock per year
My take is that we should have people with some thermodynamic education in powerful positions that can make appropriate choices. Obviously Sen Baucus is morely likely to be interfacing with lobbyists for major power interests. Burning fossil fuels , mostly NG in this case, for space heating destroys the one chance to obtain electric power from that resource in a relatively inexpensive and simple manner compared to wind and photovoltaics. The latter sources have severely impacted my electricity bill when their generous Feed-in tariffs result in my billing having to incurr ever increasing rates per KwH.
And what about needing electricity during those months that we DON'T need home heating? Well ai_vin in the summer you can at least open a window and circulate air with a fan. There is no such immediate remedy in the winter - you freeze in the dark as many around these parts were finding out last week. An excuse to mention the susceptibility of centralised power generation systems given that the recent ice-storm brought many bad tree limbs down on to power lines cutting power to 300,000 homes in the greater Toronto region. It strains credibility but 46,000 were still without power FIVE days later. This scenario is seeming to repeat itself about once per decade. It will be interesting to see how the rest of the winter pans out. There is now talk of burying the wires in older neighbourhoods albeit at great cost, so I won't again be without power when someone down the street elects not to trim their tree out front. Buried wires, are they kidding ? That's what I want. NOT. Thanks to the cable company I already got dozens of buried wires around my property and they have no idea why or where they go !! Let's not give power companies free reign to do the same. Perhaps this would be the time to alternatively offer residents a grant for an alternative power plant. Last night we may have broken a record set in 1920 for overnite lows if the temperature fell below minus 21 deg C. In such conditions a microgeneration unit can always be brought up to max output by loading the generator with electric heating elements and also by drawing down the storage batteries during a cold spell. I don't think it is practicable or even necessary to construct a one-size-fits-all cure here as Florida and Alaskan climates are always going to need a different mix of equipment for optimal use at affordable price points. Ai_vin I support your ideas for demand management. I think there is much we can do as consumers. As someone pointed out, the way current natural gas heating works it is just too easy get up out of our chairs and raise the thermostat temperature - the equivalent of throwing yet "another log on the fire" as opposed to the work needed to erect further renewable infrastructure.
Although a diversified grid is desirable it still supports the centralised electricity generation culture. In Canada and most of the northern USA we should be moving towards residential/commercial electric power generation using Natural Gas powered gensets as a first line attack. Definitely NOT the renewables of solar and wind which IMO represents flawed thinking for these geographical regions. IOW instead of burning natural gas in the traditional open flame forced air heating system, instead we repurpose this gas into an internal combustion engine driving an alternator while extracting the waste heat from the engine jacket and exhaust system by coolants which are then passed through conventional radiators conveniently mounted inside the existing forced air plenums. For benefit of those not educated in thermodynamics, this is the same 70% of heat that is normally discarded by conventional thermal plants at the megascale level into lakes rivers and oceans or those huge cooling towers that you see whenever those other environments are unavailable. This microgeneration method is thermodynamically way more beneficial for the business client and home owner to be burning the gas in this way rather than paying someone else, i.e. the established power producers, to be doing it for us. Thus electricity comes by way of a byproduct of the home heating process but with the advantage of there being no electricity bill to worry about at the end of the month.
Aluminum @ $1.80/Kg and Magnesium @ $2.55/Kg Along with those figures, it is interesting to note that the specific densities of 2.7/1.7/8.0 gm/cc for Al,MG,steel. IOW the cost/lb of Al and Mg inverse to their densities. Since a particular casting process involves the volume of material needed and not weight then magnesium and aluminum are technically interchangeable without a cost rider if NaF6 cost is low. OTOH if energy input is becoming a major consideration in the manufacturing cycle it seems fair to avoid the metallic option. Fan shrouds can be the motor as well if the stator coils are impressed into the shroud periphery and the fan blade assembly is given a cylindrical rim. This rim could be impressed with strips of neodymium which could survive the molding temperature no doubt. Well, it does work for computer fans.
Seriously Nick ? The 3 million Prius on the road mean nothing ? Direct mechanical drive is becoming a thing of the past. The Accord hybrid design, with its recent introduction this fall, takes the next step forward in hybrids. In this design Honda has the Accord engine completely decoupled from the wheels for the most part and therefore avoids the churning of energy from the traction motor, MG2, back to the generator, MG1, while cruising as is done by the Prius Synergy drive. Naturally the Accord engine will need the road to be presented to it as a high torque low rpm load while cruising just like Prius in order to achieve Prius-like efficiency. At the moment I am not sure how the Accord design intends to accomplish this. Anyone who has studied series hybrids quickly realises that specifically for highway cruising an impedance converter is required in order to supply high voltage low current to the traction inverter while having to accept the complete opposite from the generator, viz low voltage and high current. This is in ACCORDance, no pun intended, with the engine's need to be running at lower rpms, during this period, to suffer the least friction for the power being delivered and hence the highest efficiency. I happen to have an idea how this can be done but to get back on topic - I don't understand why Toyota is upping the game on the Yaris. I have the coupe version of this car with the 5-speed it's a sleeper of a machine if you enjoy driving stick. OTOH it would be interesting to see that car equipped with an HSD and a two cylinder. Maybe I will - sooner than I think. It's just been announced on the news here that some car companies are talking of eliminating manual transmissions entirely from their fleets within a couple of model years.
LOL, the CPUC is sure screwed up. At the start they are accurate enough in specifying the peak power capacity of the storage resource in units of MW, however later on, in the schedule itself, they refer to it as the energy storage procurement ?? Which is all somewhat meaningless unless the expected backup time is quoted. If the existing thermal stations could have their load factors increased during the night in order to replenish these proposed energy storage devices we could probably avoid the huge expense of natural gas turbine peak lopping plants and the arbitrary contributions from those boutique energy sources of photovoltaics and wind.
Alex, clutches and two-speed transmissions probably work for WrightSpeed's business plan. If I remember more than 30 years ago Eaton Corp was working on a similar idea and abandoned it. Their team had problems getting the hydraulic actuators to work consistently. Much later Tesla tried the same thing, it failed, and Musk couldn't even get Magna onboard to build that type of system. There are easier ways to go. Tesla's problem was not difficult to solve but it was a case where the design team needed someone with a better grasp of the fundamentals. In essence they needed a motor with a larger magnetic circuit that would be capable of driving to 60 mph in four sec but with the motor turning at only 7000rpm rather than 14000 rpm. Then for those speeds exceeding 60 mph and approaching 125 mph they needed a Prius style voltage upconverter of around 100Kw. This would allow the controller to preserve the V/F ratio going forward. Acceleration would continue at constant power all the way to top speed and there would be an inverse torque drop off during this period but not as drastic as there would have been if the V/F had to suffer through the lack of an upconverter. Tesla didn't take this route, however. They chose a friendlier top gear ratio, moved 650 amp transistors up to 850 amp and did something to the motor on which there were no specific details. I think that progress is made when moving away from mechanical systems. Linamar's twin motor rear drive unit described on GCC this month is a case in point. Despite dispensing with a differential and a hollow shaft motor, the agregate power of two smaller motors could be 26% greater than one purely on considerations of surface/volume ratios alone. Thanks for the links BTW
@Alex Well, I would have to agree that a quadrature system would meet a constant power minimal torque ripple requirement. And as you imply it could be implemented with just four NPN power devices if each phase winding was center tapped. The downside of powering each half winding alternately would mean a 1/root2 derating compared to a bridge. Notwithstanding there is always that added benefit to have IMs operate to 14000 rpm. I don't understand why Honda, in the first place, would even consider a 12Kw automotive electric drive specifically within its 0-1500 rpm range. Finally their Accord Hybrid due out this year is using a 125Kw motor operating to 15,635 rpm which will probably be the same size.
Honda is designing this motor for the IMA system which is focussed on the 0-1800 rpm range mainly. It is generally accepted that it is particularly difficult to get high effcy levels at 60Hz excitation levels, consequently all this effort to do with alternative magnetic structures. It should be pointed out that the standard induction motor efficiency will rise with applied frequency perhaps exceeding 95%. A property of the induction motor that I've noted is that constant copper loss is expended per unit torque i.e. rotations from 1 rpm to 10,000 rpm will incur a constant loss while providing constant torque. It is therefore evident that effcy must therefore improve with rpms. Of course iron loss is to be expected rise with the increasing frequency of excitation in order to gain those rpms however these iron losses can be mitigated with the use of thinner stator laminations as in those 400Hz motors employed in the avation industry. This new Honda motor is application specific to the company's IMA system and is not going to be suitable as an EV traction motor, but then neither are MG1 and MG2 on the Prius for that matter. However I wouldn't be surprised if it found further use as the generator on later variants of the new 2014 Accord hybrid design.
Whoa !! Did I read that article right ? Or do my eyes deceive me ? Regardless. Combat Engine = Me Want You may have felt, as have I, that there was some automotive need not yet fulfilled - but for no longer it appears. Finally for the aggressive driver, the one ingredient we've been missing all these years - the Combat Engine - may soon be available. In your dreams Honda with your "Earth Dreams" powertrains, the Combat Engine is for me. I can see me now whizzing down the road with the C.E. on WOT. Oops did I just nod off, sorry. But then this new engine is to be a two cylinder while an earlier report had recommended that a 3-cylinder configuration was optimal for exhaust gas flow when seeking to avoid unfavorable interactions with the discharge from the adjacent cylinders. (Or was this yet another technical article I clearly didn't comprehend). But then would even a 3 cyl 3.0 litre engine be enough to propel a tank ? I sure don't know. They mention a possible hybrid spinoff application. Really ? In case someone from the project is reading this I can save you heap of dough. Hybrids happen to need constant torque engines on account of the fact that +70Kw alternators have constant field excitation due to those expensive Neodymium magnets that you may have read about. But then diesel torque characteristically drops off above 2400 rpm. This infers that the allowable current generated will have to be proportionally reduced as the engine proceeds beyond that point towards top speed. And all just to reach that final 25% of max power. Not good. I would have thought that hybrid design - particularly the two machine variety - is difficult enough already without having to make that concession. Just where is Rafael Siedl when you need him ?
I do not see any error Take another look. I was referring to the graph for the gasoline version, not the diesel.
The DOE never seems to tire of throwing money at the problem of supply side management. At least here in Ontario we have put wind turbine installations on hold but you have to wonder how these projects get ramped up so rapidly. Oh right, lobbyists ! Meanwhile there seems to be precious little interest in promoting improvements that could be immediately beneficial on the demand side instead. Sure there is Time of Day metering with its punitive rates at peak periods, but no domestic electric water heater control that could allow power operators to remotely dump these significant low priority loads as peak periods are encountered. Other low tech solutions bring into question the reason for the poor availablility of LED fixtures for residential housing. It seems that unless you are prepared to use AA batts or wall sockets there seems to be a dearth of LED powered ceiling fixtures to be found in local stores.
The first engine graph has Torque and Power designations reversed !
Electric vehicle design always involves that quick or fast tradeoff. The reduction gear ratio chosen here allows for a fast 100mph top end but results in a disappointing 10sec to 60mph accel ramp. I would say that most drivers including myself would accept a lower 80mph limit if it came with a quicker 8 second ramp. Thoughts anyone ?
When taken out of park, the gearbox enables increased torque output while allowing for lower motor input speeds, an attribute that conserves battery energy and extends range. ?????? Very confusing. How does the single speed gearbox enable greater torque, surely the job of the controller ? Unless it's meant that controller current output is limited until the parking pawl is totally removed at which point motor current is allowed to increase to its maximum. As a point of good design all controllers must have a "creep" mode to avoid the vehicle falling backwards on a hill. OTOH killing initial acceleration to conserve energy - are they nuts ? Generally you want a good launch from those lower speeds to compensate for the lack of raw horsepower the EV will encounter at higher speeds. Further benefitting the refinement, the single-speed gearbox helps maintain the correct installed axle-shaft angles of the driveline. IOW something required of any gearbox mounting on the planet.