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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.
Just to be clear, I'm not opposed to the idea, I think it has its applications, I just have no interest right now to have or use such a vehicle myself. Maybe when I'm 90 years old (that's one of the applications). Elements of this technology have a use in preventing people from getting in trouble (e.g. preventing someone from driving through a red light or stop sign with other traffic coming, or preventing someone from making a left turn in front of another driver). I think the average person is a lot more opposed to the use of public transit than the optimists think they are. Car-sharing is likely to get people OUT of public transit and it won't help reduce congestion. And for all those idealists who think everything in the future is going to be automated ... I'd like to know whether those people think their own jobs are going to be automated. I know that automation in the world of manufacturing has replaced drudgery (an army of people each holding a manual spot-weld gun and pushing a button a thousand times per shift) with other jobs requiring skill - someone has to design the tooling, program the robot, and fix it when it breaks (and I'm one of those people). And someone still has to handle the parts that are going into the automation equipment ... It isn't practical to automate everything, and what would people do for a living if we did?
Airplane pilots have the ability to "think out of the box" when something goes wrong. They have the ability to judge whether a situation warrants emergency actions or can safely be ignored. They can manually pop the circuit breaker on a faulty electrical circuit. They can judge whether they can safely land with one of the landing gears not fully engaged. A fully automated aircraft without such an experienced pilot on board ... crashes.
It's one thing to handle a stop sign and a traffic light automatically at an intersection with all sorts of nice visible lane markings. It's quite another to handle it when all the markings are covered in snow. Or glare ice. Or the intersection is under construction and there aren't any markings. Or the power is out and a police officer is directing traffic. Or (as happened in a major blackout in Toronto in 2003) everyday citizens were directing traffic because there weren't enough police officers to cover all the intersections and they had enough other headaches on their hands. And even if it's sophisticated enough to handle that (which I doubt) ... How does the software distinguish a citizen directing traffic in the midst of a blackout ... from a teenager playing havoc, which you know is going to happen! I have little doubt that Tesla will be able to produce a better "autopilot" that works in more circumstances and that those circumstances will constantly increase in scope over time, but they are a loooooong way from being able to be summoned autonomously in the midst of a power blackout due to a snowstorm.
Show me the BSFC map. Operating the engine just above idle but under heavy boost is a recipe for having to implement a lot of detonation-control measures (EcoBoost is direct-injection but that doesn't exempt it from detonation) and those all cost efficiency. The turbo won't be in an efficient operating range that low in the revs, so the boost pressure will be coming from this gizmo (eating up crankshaft power), and "underexpanding" the power stroke isn't a recipe for making efficient power. Again ... show me the BSFC map. A three-banger running at 1200 rpm near full load (boosted) is apt to be mighty rough, too.
... and your point is? Do you want to go back to the old low-performance sealed-beam round headlights? Think about aerodynamics for a moment ...
I know the "idea" is to downsize for less friction and lower pumping losses ... and it works for getting through the very light engine loads in the European NEDC or most of the US EPA emission and fuel consumption testing. But it doesn't work in real world driving. The discrepancy between official and real world fuel consumption figures is increasing, and something like this would only increase it further. 32 mpg US = 7.3 L/100 km; this isn't particularly remarkable. Lots of cars with 200ish hp from larger displacement normally aspirated engines (and the usual variable valve timing that is used nowadays) will do that on the highway. Among rental cars, I had an Impala (2.5L normally aspirated 4 cyl) do better than a Cruze (1.4L turbocharged 4 cyl).
The article is silent on what the BSFC is when the engine is running under boost. 184 lb.ft torque from a 1.0 L engine means it is running at a very high boost pressure (probably somewhere near 2 bar boost = 3 bar intake manifold pressure) in order to achieve that. Real world experience with highly boosted gasoline engines has been that they can be economical when puttering around at light load (typical of government emissions and fuel consumption testing) but thirsty when put under load. This approach is essentially the opposite of the Atkinson cycle (which uses a higher expansion ratio than the compression ratio). Mechanical supercharging pretty much translates to a higher compression ratio and then throwing half of the power stroke away.
Now we just need NHTSA to get out of the stone age and allow this technology in the USA!
Resistive heating elements can be put right in the item to be heated (e.g. seats, steering wheel), the intent being that you no longer have to heat the air (as much). It isn't feasible to do that with a heat pump. Heat directly applied to the windshield (via a resistive film) to defrost or defog it or melt snow/ice on the wiper blades is both more efficient and more effective than blowing air at it. This isn't an application for this plastic film but it's an example of where resistive heating will work and a heat pump is not feasible or not as effective, or both.
Henrik, VW optimistically wants 25% of their sales to be EV somewhere in that timeframe; EVs thus far have not met sales expectations. You really think they should stop development on everything that accounts for 75% (likely more) of their sales?? At this point in time, reducing consumption by 10% in the combustion-engine fleet is a more constructive exercise than leaving that technology to wither and (hopefully) replacing 10% of the sales with EVs. (Those EVs still require energy to be recharged ... and some of that energy to recharge them is coming from fossil fuels ... even more of it, if Germany doesn't operate their nuclear plants!) And, plenty of human-driven vehicles will still be sold after 2025 (which is only 8 model years away). I want no part of autonomous driving. I'll tolerate it as an option as long as it can be switched off (or not bought). In any case, the problems with getting vehicles to operate autonomously and without errors in all weather and traffic conditions have been underestimated. Tesla's "autopilot" system should have never been marketed as such; it is nowhere close to being an autonomous system and the real world evidence of that is mounting ... I'd be surprised if VW figures this out by 2025. I like this vehicle, though. A lot of the more radical features of it won't make production, though. (It's going to have tires with actual sidewalls, it's going to have a B pillar, the back doors will open the normal way, etc.)
The range on NEDC (400 km) will be the biggest number, so of course that will be shown first! I have seen elsewhere that real world range (whatever that means) of around 300 km is expected. That is 7.3 km (4.5 miles) per kWh, which is in a plausible range.
Turbomachinery typically doesn't scale down very well - Reynolds number effects (has to do with turbulent flow and fluid-dynamic losses) become killer when the size goes down. Also, the Brayton cycle (gas turbines) either requires a very high pressure ratio (only achievable with multi-stage compression and expansion) or very efficient regeneration and recuperation (only achievable with heat exchangers having large surface area and low flow losses i.e. they have to be BIG) and I see no evidence of that. The website mentioned above makes no mention of thermal efficiency or BSFC or anything of the sort ... and all this makes me think it's likely pretty poor.
Spark-ignition premixed-combustion engines on standard pump gasoline become knock limited very easily. Add more boost, and you have to drop compression ratio down or delay ignition timing or add lots of enrichment. It's not necessary to stack boosting devices in series to reach these limits! Thermal loading on pistons and exhaust valves (and catalytic converters) is a big issue. Direct-injection can help with knock control but they all run premixed-combustion under load which limits how far this can be taken. Diesel-style injection late in the compression stroke is resistant to detonation but not good for emissions. (same PM and NOx issues as diesel has) Yes, higher octane fuel (including ethanol) would help with this! It addresses the knock, but not necessarily the thermal loading. You can still melt a piston or an exhaust valve without detonation, although detonation makes it happen a whole lot sooner and faster. As mentioned above, I am quite sure that Ford crunched the numbers and did the simulations, and ended up with an exhaust-driven turbocharger on the Ecoboost for good reason. Use of a turbocharger is still compatible with running cam timing that emulates the Atkinson cycle at part load, to divvy up the energy in the exhaust between the pistons (turning the crankshaft) and the exhaust turbine (turning the turbo compressor). Yes, the supercharger will give more boost right off idle ... where detonation is at its worst. Or you can just change into the right gear when you need power, instead of lugging the poor thing ...
Hmmm ... Torotrak has been kicking around for quite a few years. If this really was an "Ecoboost" engine then the "incumbent" forced-induction device is a conventional exhaust-driven turbocharger, not a mechanically-driven positive-displacement supercharger. I gather that they are proposing to use this as part of a twin-charging scheme, as a supplement to a turbocharger to help out with low-end torque. The inability to fully convert remaining exhaust pressure into crankshaft torque by overexpansion (e.g. Atkinson cycle) does not act in favor of a boosted downsized engine, particularly when it's running under heavier load (on boost). Call me skeptical; our family's real-world experience with boosted gasoline engines has been that they are not more efficient in the real world than a bigger, but less highly tuned, normally aspirated engine ... If someone can figure out a way to get them to run under load on boost without enrichment and without melting themselves down, that would help. Cue Bosch's water-injection system ...
... except that none of those technologies are ready for prime time, the cost is not "low", and none of that in any way affects the velocity-squared relationship of aero drag in any case. Hypothetically making a vehicle self-driving doesn't miraculously make aero drag go away, and changing to a different fuel type doesn't change the velocity-squared consumption of whatever fuel type you are using. Ontario, Canada has chosen 105 km/h for the truck speed limiter setting a few years ago. It's doubtful that this has had any real world effect on safety; most truck collisions don't involve driving at a steady speed on a motorway. It has probably cut fuel consumption, and it has rendered trucks almost incapable of overtaking each other, which is really annoying. The choice of 105 km/h for the truck speed limiter setting is a tacit admission that Ontario's highway speed limit of 100 km/h is too low.
General aviation aircraft engine technology is roughly on par with the old air-cooled VW Beetle. No updated valve seats (that would allow use of unleaded fuel), therefore no catalytic converters, no emission controls at all. If they have fuel injection, it is an old open-loop design. Any change has to get through FAA certification, and the FAA is pretty resistant to change. It's hard to put new aircraft and powertrains on the US market due to the stifling legal environment, so old stuff keeps getting re-used and rebuilt again and again, and it has to run on the same leaded avgas that it always has. A number of more modern powertrains have been developed for aircraft use, but they have not made it to the end users in appreciable numbers.
The remaining challenge will be achieving this affordably. That's going to take longer. 500 km electric range in a car that costs $150,000 does me, and every other average non-rich person, precisely no good whatsoever.
That's the Atkinson (or Miller, if you wish) cycle. Nothing in Nissan's variable-compression-ratio system precludes the use of cam timing trickery to achieve Atkinson/Miller cycle operation. The "efficiency versus power" tradeoff relates more to cylinder pressure and detonation limitations. It can only operate at a very high compression ratio at lighter load on the engine (when boost pressure is low and intake is restricted - whether by throttle or by cam timing trickery is irrelevant). It becomes detonation-limited and peak-cylinder-pressure-limited at high engine load which means the compression ratio must be lowered (and BSFC suffers). You can rest assured that Nissan already knows how to do the Atkinson/Miller cycle, and they already know that they want to use the highest compression ratio that can practically be achieved under given operating conditions.
There is zero chance that a vehicle like this would be granted an exemption from collision standards in the foreseeable future ... unless it is a motorcycle.
A harmonic-drive gearbox is a type of high-ratio gear reduction unit (100:1 gear reduction is possible in a single stage). A stepper motor would be the most likely choice to operate that, and yes, the motor would be under direct ECU control. It is also possible to do it hydraulically based on engine oil pressure through a directional valve; VVT mechanisms already do this. It seems from the diagram that Nissan has chosen a harmonic drive reducer which would almost certainly be driven by a stepper motor. Stepper motors are already in common use for actuators that require high positioning accuracy (which this does). If high positioning accuracy is required, the hydraulic method is not so easy. VVT mechanisms use hydraulics because the adjustment has to be done inside a rotating assembly (the camshaft and drive pulley/sprocket). Controlling the position of an axis (the variable-compression mechanism) via a stepper motor in response to any inputs you care to choose, is a trivial exercise for modern engine control units. Feedback via knock sensor is almost certain to be part of the control strategy. Ignition timing would remain part of the knock strategy because it can respond on the next engine cycle, whereas the compression adjustment mechanism would take longer to react. Again, this is not a problem for modern engine controls. The ignition timing control loop is the "fast" response and the compression ratio control is the "slow" response. As for air/fuel ratio ... Given how the standards have been written and how the engineers have figured out how to (mostly) comply with them, this ain't gonna change. The standards have locked us into stoichiometric air/fuel ratio with lambda sensor and 3-way catalyst. You can play with exhaust recirculation, either via an explicit EGR system or by cam timing trickery, but air/fuel ratio remains stoichiometric. The variable compression mechanism in no way changes or affects this. Even if HCCI is used, it will still be stoichiometric, just with varying amounts of EGR - so that it can use a normal 3-way catalyst. Nothing else that we know how to do, is sufficiently future-proof. (Ask VW.) I agree with the statement that you can have efficiency or power, but not both simultaneously ... unless you are using high octane fuel (like E85) ... Modern engine controls, with knock sensors and lambda sensors, can figure out what mix of fuel is in the tank (within reason) without actually measuring what the fuel is. Gasoline is such a concoction of different compounds that measuring its properties in the fuel tank isn't all that reliable. But the knock sensor and the lambda sensor are enough to tell the engine controls what they need to know. The person who puts diesel fuel into the tank of a spark ignition engine is gonna be in trouble no matter what.
Arnold, what are you talking about? Infiniti's variable-compression system works with a normal DOHC 4-valve cylinder head and doesn't care whether the engine uses port-injection with premixed combustion, direct-injection with premixed or stratified charge, or both. It's also a really good way to facilitate HCCI over a much wider range of speed and load than otherwise possible. It doesn't care what the fuel is ... if anything, this system would allow operation on high percentages of ethanol in high-compression mode, thus taking advantage of the high octane rating of ethanol in a way that today's conventional flex-fuel engines can not. (For example, under given conditions, 87 octane gasoline might limit compression to let's say 9:1, but E85 would allow the compression under the same load conditions to be let's say 12:1, thus improving efficiency under those load conditions.) Knock sensors are commonplace today. Real-time combustion pressure sensing is not common but it is in production (many current emission-controlled diesels have it). The ability to vary the compression ratio opens up options for how to deal with the detection of knock. My main concern is combustion turbulence. Modern combustion chambers require the piston to approach the head closely in squish bands around the outside of the chamber, which improves turbulence and accelerates combustion. With this compression-adjustment system, when it is operating in low-compression mode, can't do that, because the piston no longer closely approaches the head!
Yes, I will grant that I did not read your self-promotion paper carefully, and I'm not planning to. The main point is that Nissan's development fits within the shape, envelope, and general architecture of a normal in-line 4-stroke piston engine, and yours doesn't. I saw piston-porting in the first diagram in your paper that I encountered, and stopped reading right there. It's problematic for emissions and lubrication. Ask Detroit Diesel.
Did they consider the large number of urban dwellers who live in apartment buildings, condominium units, downtown properties without access to recharging? It sounds plausible that 90% of trips are within the capability of current EVs but it doesn't sound plausible that that 90% of people have access to charging. Infrastructure needs some work to make this happen. Every trailer that I've ever towed increases fuel consumption by 30% - 50% because it buggers the aerodynamics of the tow vehicle. If you're going to have a range extender it needs to be on-board to avoid this. If it's going to be on-board then the space needs to be allocated in the vehicle for it. If the space needs to be allocated in the vehicle for it then it might as well be there all the time. Car sharing means you're sharing the previous owner's detritus left in the car unless someone's being paid to clean it after every use, just like normal car rentals ... up goes the cost ... Like it or not, lots of people are pigs. Car sharing also means I can't leave my hard hat, safety vest, tool box, etc in the car. It might work for some people but it won't work for all people ...
T2, Fiat already has the TwinAir engine (another one that I really like). A parallel-twin engine isn't necessarily less expensive nor more efficient than an inline-three, though. The Ford three-cylinder, and a number of others, can get away with not having a balance shaft if the engine mounts are carefully designed, but with a parallel-twin, it's pretty much unavoidable. In motorcycle applications, the NVH can be accepted in some cases, but most people wouldn't tolerate it in a car. The Fiat TwinAir is counterbalanced. I have my doubts that cylinder de-activation on an engine this small would save much in the real world ... it may just be another thing that increases the discrepancy between the EPA / NEDC tests and the real world. I have a car with a 1.0 3-cylinder, and it doesn't spend a whole lot of time at light engine load and higher revs where cylinder de-activation could help. Real world highway driving, the load on the engine is already pretty high most of the time. Real world city driving, the revs are low and cylinder de-activation would probably give unacceptable vibration. Cylinder de-activation schemes generally don't operate at low engine revs.