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Opposed-piston, across-chamber-injection, two-stroke, uniflow-scavenged engines are not a new invention. Those who believe the Achates engine is going to revolutionize the future of transport, would do well to study the design, and the fate, of the Commer TS3. Look it up. They were in production for a couple of decades ... around fifty years ago.
There isn't crankcase scavenging, I know that. Detroit Diesel engines didn't use crankcase scavenging, either. That's not the issue. The issue is that one way or the other, a certain amount of oil needs to get to the piston rings. Those piston rings cross the port openings in the cylinder wall. Every time they do ... a little bit of the oil on that piston ring escapes out the port opening and thus either goes out the exhaust (if it is the exhaust ports in question) or into the cylinder and thus into the combustion system (if it is the inlet ports in question - on Detroit Diesels it only involved inlet ports because of the layout of the engines in question). Scavenging is coming from a mechanical blower ... conceptually much like Detroit Diesel did it. 4-stroke engines - or, more properly, engines that don't have inlet or exhaust ports in the cylinder wall that are crossed by piston rings - don't have this issue because the oil supply stays on the bottom of the oil control rings and the tiny film necessary to lubricate the compression rings stays put against the cylinder wall.
Piston porting + lubrication = lube oil getting somewhere it shouldn't. Detroit Diesel couldn't figure out out ... Same issue ... We'll see.
James, the vehicles in question, which are all model year 2015, came originally equipped with SCR - not a LNT. The earlier-generation models that used LNT (without SCR) are still in limbo, but the proposed solution (yet to be approved) involved a different LNT, not a SCR retrofit. VW was the only auto manufacturer to attempt to use LNT on its own in the North American market. Some BMW models use LNT in conjunction with SCR. Quite a few manufacturers have used LNT elsewhere in the world. California will NOT be withholding registration of the vehicles in question if owners choose to do nothing. That's what the huge compensation payment to the government by VW was for. Any state that took part of that compensation money is required to allow the cars to continue to be registered unmodified if users choose not to have them modified, and California was one of those (there are 5 states that did not but I don't know which they are - Calif is not one of them).
This article is rather short on suggestions. Alternative materials? Durability ... cost ... weather ... traction? Ignore it completely and let pavement degrade faster and have to do a major asphalt reconstruction project (not an environmentally friendly process) more frequently because of it? Dirt roads? Aside from some obvious safety implications, think about particulate matter. And materials put down to control the dust might have side effects, too.
350,000 km divided by 150 vehicles is just over 2000 km each. I am underwhelmed.
This is not a simple matter. The two-stroke concept - a further development of it which does not use air-assisted injection - is in current production by Rotax/Bombardier for snowmobile and outboard motor applications, but a piston-ported two-stroke will always have a trade-off between adequate lubrication of the piston rings for long life, and oil escaping either into the combustion system from the intake ports or out into the exhaust from the exhaust ports, leading to HC and PM emissions. Exhaust temperature tends to be low with a lot of dilution on two-strokes, which is not good for catalyst light-up after cold start. These applications do not require compliance with automotive emission standards nor is the engine expected to last 300,000 km with only basic maintenance. For applications requiring compliance with automotive or Euro 4 motorcycle emission standards, piston-ported two-stroke is not the answer. The Mahle pre-chamber is a lean-burn application which is evidently being used in Formula 1 to reduce fuel consumption at part load. This is also troublesome if you have to meet modern automotive emission standards. If you have to run stoichiometric to keep a catalyst happy, it's doubtful that this acoomplishes anything. Maybe if the prechamber is stoichiometric without a lot of recirculated exhaust and the main chamber is where the EGR is kept, it might be of some benefit. What needs research, and is surely the focus of this, is somehow addressing the fine particulate emissions that have become apparent with direct-injection four-strokes, improving the speed of combustion without encountering detonation so that the compression ratio can be increased for better efficiency and so that combustion is completed at that higher compression ratio, and controlling piston and exhaust valve temperatures to reduce the need for enrichment under load - the latter being a particularly significant issue for downsized forced-induction engines. Advanced engines that rely on HCCI under at least some operating conditions will be relying on this, too.
To me, this thing looks like a sealing nightmare (inside-out version of Wankel but same issues), and a cooling nightmare, and a lubrication nightmare, and a horrible-combustion-chamber-shape nightmare (read: lousy emissions and thermal efficiency), all rolled into one.
$440/kWh at the pack level is a little pessimistic. If GM says the Bolt's pack is costing about $145/kWh, I'll go with that. The integration into the vehicle is not tripling that. The Tesla powerwall includes a lot more than just the batteries.
Anything in the 2025 timeframe and beyond is probably in the vicinity of the expected production lifetime of engines and transmissions developed today. As of right now, we need better powertrain efficiency out of combustion engines and stepped-gear transmissions. Don't accuse me of fighting the last battle. I'm fighting TODAY's battle. We have to get through today to have a hope of getting to tomorrow. For what it's worth, a customer of mine builds parts for both Tesla and for the Chevrolet Bolt, and another one just got an order for production equipment destined for Tesla. I'm powertrain-agnostic ... but I deal with reality - including today's reality. And today's reality is that I have to travel for work, there are still no publicly accessible DC fast charging stations in Ontario outside of Toronto (which does me no good) and outside of Tesla supercharging stations, I can't afford C$100,000 for a car which means those Tesla supercharging stations do me no good, and it's snowing outside with a forecast of bitter cold temperatures this coming week. Frankly, the reason that EVs to date have not sold is that EVs sold to date have either been priced out of range of the average person (Tesla) or have sucked (everything else). Sorry, but if that Nissan Leaf that the EV evangelists promote so much can't make it to my sister's house (nevermind be able to get there and back) ... it sucks. Sorry, if getting to my sister's house requires finding an obscure public access charger and stopping for three hours partway through the trip (160 km) ... it sucks. I hope that the Chevrolet Bolt will be a game changer ... a reasonably affordable EV that doesn't suck ... but I also know the sales projections. As long as these situations persist ... we'll need more efficient gasoline engines and transmissions. We'll be needing them for quite a long time to come.
Reality 1: The internal combustion engine is still going to be with us for a looong time. At this point a 1% improvement in gasoline engine fuel consumption saves more petroleum than the entire market share of EVs does if you completely neglect whatever it takes to generate the electricity that they are using. Reality 2: Buyers will have the choice between a Cruze (diesel or gasoline) with this transmission or a Bolt. in the same dealer. THEY will decide. And that is as it should be. Second and third ratios look awkwardly close together.
... or a device to game the Japanese emissions and fuel economy testing procedures, and probably Euro NEDC while they are at it.
Actually, this powertrain has NO plug-in at all. It is a hybrid vehicle ... not a plug-in hybrid. And let's not be legislating or prohibiting specific technologies, please. Let them survive or wither out on their own merits. Maybe Nissan has figured something out that Toyota and Ford have not. If they have ... more power to them and I wish them success. If reality intervenes ... let the consequences flow forth; they will become apparent in due course. Series hybrid has not historically been the optimal way to set up a powertrain - but there are specific circumstances where it could be. Those circumstances don't coincide with my own driving patterns (lots of suburban and motorway). That doesn't mean they won't coincide with someone else's (heavy stop and go).
They weren't and aren't free. An engine with VVT costs more to manufacture than one without. It has parts that don't exist in a non-VVT version of the same engine, and those weren't made for free. It's low cost ... not free. It might be "no extra cost" as in, not a line-item option that you have to pay for when placing an order for the car, but that doesn't mean it was free ... it just means you don't have the option of not paying for it.
Series hybrid traditionally isn't very efficient in straight motorway conditions because of the energy-conversion losses (mechanical to AC electric to DC to chemistry inside the battery, then chemistry in the battery to DC to AC and back to mechanical in the traction motor). If the engine output more-or-less matches demand then you can avoid at least some of the battery charge/discharge loss, but the others are still there. Whether all these losses balance the ability to stop the engine under more circumstances and only allow it to run under more efficient operating conditions ... is a crapshoot and will vary depending on circumstances. All this is why a Prius operates with mostly mechanical drive from the engine at higher road speeds. And so does a Volt, and so do all the other hybrids. There's a reason they did it that way. The Japanese test procedure is hopelessly optimistic. Circumstances that contain a lot of idling and very gentle acceleration and low speeds could very well offset all those energy-conversion losses by keeping the engine stopped more. But take the same vehicle out in the real world of higher speeds and faster accelerations and (for most of us) less idling ... and it is likely to be less efficient under those conditions than even a conventional non-hybrid powertrain. I await the real world testing ... ! ! !
Cam phasers aren't "no" cost, but they are fairly low cost. Most recently designed spark ignition engines have cam phasers on the intake camshaft at a mininum and many have it on both, and it's a common strategy to use them to emulate the Atkinson cycle when operating at part load. They switch to more normal cam timing events when acceleration is demanded.
The 48V systems are really just meant for auxiliary systems like HVAC (air conditioning compressor), fast-acting starter motors for stop/start, and mild e-assist systems. If you're going to the trouble of putting an electric motor/generator in place of the torque converter inside a transmission, you are better off making that part of a "Real" hybrid system, something with enough power to drive down the road. In that situation, it's better to operate it at a higher voltage in order to get the current down (and reduce the size and mass of all copper conductors in the system).
Ships have very long service lives (25 - 30 years). Using low sulfur fuel is something that can be done that benefits emissions from not only new ships but also existing ships. Using LNG, or alternative powertrains in general, is something that is only viable on a new ship, since it has to be engineered in, not added on, and then it takes a long time for the fleet to be renewed. As for the post above ... Let's see the cost estimate to cross the Pacific ocean ... someone needs to do some math for us. Realistic numbers, please, not just hopelessly optimistic randomness. And you want to have just one connection? Not much redundancy there. One ship that goes down is a tragic loss, but nothing compared to what would happen if that single connection went down - or if something happened at the terminal at either end. It would sure be a target for the terrorists out there. A ship can sail from any port that it can fit into, to any other port in the world that it can fit into. Same with airplanes. Can't do that with fixed links. Travel with any such system would require a whole lot of stopovers and transfers - just like taking the bus or train, but waaaaaay worse if expanded to a global scale. How does that proposed Hyperloop deal with crossing tectonic plate boundaries (earthquake zones)? I genuinely don't know the answer to this. A connection between Australia and Asia would have to gradually become shorter over time ... and it would have to cross a pretty active geological zone which also happens to be an ecologically sensitive zone. For that matter, much of the west coast of North America is either geologically active or ecologically sensitive or both. Major construction projects on land in a lot of British Columbia are hard to get done.
A number of the latest transmission designs already allow for a clutch and electric motor/generator to be installed in place of the torque converter (the clutch is needed to allow the engine to be stopped). The ZF 8-speed (longitudinal) and 9-speed (transverse) transmissions are like this, and there are a few production vehicles that make use of it (and more are coming). Hyundai and VW hybrids also use this layout.
I should also add that with regards to the "million miles per fatality" statistics, when you get towards the vehicles that have big numbers, it's because they have a small number of fatalities. This, of course is a good thing, but it also means that the sample size (of fatalities) is small, and random situations that lead to just one more or one fewer fatality can shuffle the order with no real underlying reason behind it. The Accord and Impala numbers should have good statistical significance, but the others could be in any order depending on random circumstances. "Million miles per fatality" is also strongly affected by demographics. Two vehicles with identical collision performance, but one of them is bought by teenagers and another by fortysomethings, will have drastically different real world crash frequency. There were a number of minivans a couple vehicle generations ago which had notoriously poor offset-frontal crash performance, but yet few real-world fatalities, because of who drives them and how. I'm not concerned with Tesla's collision safety.
Autopilot is not "approved by all authorities jurisdiction by jurisdiction before it is deployed feature by feature just like the autopilots of other car makers". That ain't the way it works (for now). In North America, there is no third-party approval body for ANY such thing. The auto manufacturers self-declare compliance with FMVSS (USA) or CMVSS (Canada); NHTSA or Transport Canada review submitted paperwork, do occasional spot-checks, and investigate complaints. That's it. Some other jurisdictions (notably EU) do have a third-party type-approval process, but the approval bodies have a set of rules that they follow and check compliance with, and if it conforms to the standard then they grant WVTA (whole vehicle type approval). There currently IS NO standard that governing bodies apply to driver-assistance systems, never-mind self-driving systems! If there is no standard then the type-approval body has no grounds to say "Nein"! Those falcon-wing doors have been troublesome, and it doesn't take a whole lot of searching to dig up all manner of issues with them. Check Consumer Reports, if nothing else. Oh look; they are skeptical of Autopilot, and the Model X is not recommended due to the falcon-wing doors:
If Tesla is so far ahead of the rest of the players as a certain other person thinks they are then they'll be the ones to find out the hard way. FMEA. MTTFd. They mean something. I'm not convinced Elon Musk knows or pays heed. Everyone else who designs stuff for the auto industry has nightmares about those. Ignoring them doesn't make them go away. It just ensures that you'll get bitten by them. And just for the record, I'm not anti-Tesla. A customer of mine builds parts for them. I love a lot of the things they've done ... but not Autopilot, and not falcon-wing doors, both of which I consider to be FMEA failures!
I am not talking about liability for individual collisions. I am talking about general product liability as a whole - the responsibility of a manufacturer to sell a vehicle which is, to the extent reasonably foreseeable and within the limits of available technology, free of safety defects. This is not just "oops, I bumped into the other car". This is GM ignition switches plus Toyota "sudden acceleration" plus Takata airbag explosions magnified by hundreds, if not thousands, in terms of potential liability if there is ANY fault found in the software. Tesla's "autopilot" system DID prompt a lot of discussion in engineering circles about the safety of these systems and their relative failure to account for human psychology. There is a fair argument that the de-activation of (seemingly all?) autopilot features with the introduction of the new hardware is a tacit admission by Tesla that the system should not have been implemented and marketed in the way that it was. It should have been implemented and marketed as adaptive cruise control and lane-keeping assistance ... just as other manufacturers have done. Calling it "autopilot" led to misinterpretation that the system had more capability than it actually did. Obviously this new version has much more capability ... I'm just waiting for someone to see what it will do in a snowstorm.
Deploying such systems prematurely, before the technology is ready for prime time (and it isn't), would be "mass murder". It will eventually happen but it will take a lot longer than Henrik predicts it will. Liability is one thing Henrik has not considered. When an individual driver causes a collision the liability repercussions are pretty limited to that driver's insurance coverage. When a big faceless corporation does something that causes an injury, the lawyers get dollar signs filling their eyes.