We need zero emission engines that are sustainable not another planet destroyer like this gasser. It is time we start to phase out polluting tech by banning the registration of new non-zero emission vehicles for people and corporations in city areas. Then keep expanding these zero emission zones for new vehicle registrations until all new non-zero emission vehicles are banned altogether from 2025. It will still take another 20 years or until about 2045 before all vehicle air pollution is eliminated as there is a large fleet of gassers that needs to be worn out and scrapped if a total ban on new vehicles is effective by 2025. It is either that or a global warming apocalypse with mass extinction of species that cannot adapt fast enough to a warming planet.

Another advantage of simply banning polluting tech is that we do not need subsidies or taxes that are costly to administrate and enforce. A ban is far cheaper to implement and enforce.

We should keep the gasser and this one can be a success if it's more efficient. Some confused leftists and green wannabee are already opposing this gasser provoking a worldwide human economic crash written here in this blog and want to ban the billion gasser for the people.

Brian Petersen, you didn’t read carefully the presentation. The first described solution on http://www.slideshare.net/giurcal/supercharged-engine
is a four-stroke opposed piston engine. The major advantage for the supercharged version is the huge power density with only one cylinder. This version is also fully balanced and has a very low NVH level without additional balanced shaft and with reduced number of components, meaning low cost.

Will require adaptive fuelling strategy possibly before certainly during and post combustion.

To be able to cope with various fuel quality and (in tank) mixes.

These technology are well enough described and proven but not fully realised.

The tools to bring the fuelling question to production are.

I suspect that in the high-boost, high-flow conditions when low compression would be used, tumble might provide adequate turbulence.

I'm wondering what feedback informs the compression adjustment.
this sketch shows an eccentric shaft But does not mention what turns the shaft.

https://patentimages.storage.googleapis.com/US6505582B2/US06505582-20030114-D00007.png

This shows the 'Harmonic drive'

http://cdn.arstechnica.net/wp-content/uploads/2016/08/infiniti_-vc-t_tech_jpg_4k.jpg

There are people referencing a 'speed' (or rpm) relationship.

The Harmonic drive is a mystery could it be hydraulically or electrically driven or possibly even respond to engine knock without reference to the engines management computer.
Could the link arrangement be protective against engine knock whilst allowing traditional engine management to manage that.

The reference to agnostic fuel and strategy is made possible as this description from above notes.

"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.

Aside the introduction of an extra task to shift the compression, which in it self needs some sort of feedback,
so another layer of engine management, there is also an expectation that fuels and fuel air mixes will have a much larger range than expected by today's ICE engines.

I assume that the control shaft will be under computer control? possibly via the hydraulic? "harmonic drive"?
It is likely to be responding many times slower than the injectors and timing which can respond within one cycle.

It's important to protect against damaging knock while running as close to the limit as possible.

http://arstechnica.com/cars/2016/08/inifiniti-will-debut-a-variable-compression-ratio-engine-in-september/?comments=1

Might it not benefit from fuel monitoring at the tank.
If appropriate fuel quality sensing (on a chip) were available it would seem useful on this VCR engine.

The most likely way to turn the eccentric shaft is a hydraulic piston supplied with engine oil.

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.

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.

Sometime later 2nd Sept.

This is a similar engine.
Describing a Dual ratio Hydraulicaly actuated "little end eye" WTF? with pressure sensing.

It will need after treatment for pollution control same as standard engine so is as with all the attempts to clean up heat engines - going down the path of more complication.

http://articles.sae.org/14912/

He described FEV's 2-step VCR, which offers a 3-5% increase in fuel efficiency, as “a relatively big ‘hammer’ to employ for CO2 reduction. It can significantly extend the operating window, allowing you to operate at higher power levels without incurring (engine) knock.”

With the expanding European test program, the VCR technology is “gaining momentum” toward productionization, with FEV in discussions with potential Tier 1s, Tomazic noted. The modular technology can be adopted as a clean-sheet or retrofit for diesel, gasoline, flex-fuel engines in any cylinder configuration.

FEV has been in the vanguard of VCR design, development and testing since the 1990s. In 2009 the company published an SAE technical paper (http://papers.sae.org/2009-01-1457/) describing the 2-stage VCR system now under test by OEMs. The mechanical centerpiece is a clever adjustable-length connecting rod featuring a rotating eccentric eye within the rod’s “little end.”

“It’s a simple, passive system, requiring just a bit of hydraulics and a 2-way valve to lock the system into positions ‘A’ and ‘B,’” Tomazic explained. The con rod’s unique design incorporates two small hydraulic pistons, each within a dedicated chamber; the hydraulics in the two small cylinders serve only as a locking function to stabilize the mechanism in the ‘A’ position.

“We basically drain one chamber and make the other one accessible to low-pressure oil that comes through the crankshaft and the con rod into that chamber,” Tomazic said. The chamber fills up and the oil flows back through a check valve. The primary (large) piston is moved up and down relative to the rod exclusively by the mass and inertial forces.

Transitioning from compression ratio ‘A’ to ‘B’ is achieved within 0.2 to 0.6 s. According to Tomazic, a typical ratio change in a gasoline engine would be from 11:1 to 15:1. The piston’s maximum vertical lift threshold of 1.5 to 2 mm (.06 to .07 in) is adjusted in real time according to load and available fuel quality, via inputs from knock and fuel-octane sensors.

FEV engineers have evolved the VCR using one of the company’s proprietary analysis toolsets known as CMD (Charge Motion Design), based on optimized CFD. Compared with fixed-ratio and full-variable compression-ratio designs, the 2-stage VCR enables higher potential fuel economy in spark-ignited ICEs, particularly as average peak firing pressures (up to 170 bar/2466 psi) increase.

Some powertrain engineers have commented that even with the presumed cost benefit of mass production, FEV’s sophisticated con rod would be many times more expensive per unit than a current-production conventional steel rod. Tomazic argues that the greater complexity is part of the industry’s investment in advanced ICE technologies to meet the next phase of CO2 regulations.