[deetjohn]

Amazing tech! This engine promises the best of both worlds.

1) Higher compression ratio for fuel efficiency under low load and
2) Lower compression ratio to aid turbocharging for more power at higher rpms.

Hope it can stay reliable in the long run.

Here is a graphical representation of the design I pulled from Infiniti's patent application. Source




01 Cylinder Block
02 Cylinder
03 Piston
04 Crank Shaft
05 Crank Pin
07 Oil pan side wall
10 Variable compression ration mechanism
11 Lower link
12 Upper link
13 Control Link
14 First Control Axis Shaft
15 Eccentric Shaft Portion
16 Piston Pin
17 Upper link Connecting Pin
18 Control link Connecting Pin
19 Electric Motor - Actuator
20 Connecting Mechanism
21 Speed reduction unit
22 Housing
23 Second Control Shaft
24 Lever
25 First arm portion
26 First connecting pin
28 Second connecting pin

[arunphilip]

Here's a nice video from the Engineering Explained channel that discusses Nissan/Infiniti's variable compression turbocharged engine.

For those who've had trouble understanding how the actuator changes the compression ratio, take a note of the explanation at 2:00 in the video.

https://www.youtube.com/watch?v=kV2ApRM_Pi8

[RavenAvi]

Infiniti has unveiled it's turbo-charged variable compression gamechanger, the VC-T, at the ongoing Paris Motor Show.

Codenamed "MR20 DDT", the output figures of this remarkable engine have been officially released as well - 268BHP of power and 390Nm of torque.

The VC-T is a boosted 2.0-litre four-cylinder engine which has taken two decades of research and 300 patents to see the light of day. The engine will power unspecified Infiniti models beginning in 2018. The people at Infiniti promise that it is the most advanced internal combustion engines ever created. The VC-Turbo technology combines the power of a high-performance 2.0-litre turbo gasoline engine with the torque and efficiency of an advanced diesel powertrain - without the equivalent emissions.

The VC-T has four multilink mechanisms inside its crankcase and these offer computer control over each cylinder's compression ratio. The multi-link is a diamond-shaped component that replaces the connecting rod's big end. When the electronically driven mechanism rotates, it moves everything including the actuator arm, control shaft, lower link, as also the multilink which then helps in varying the piston's stroke within the cylinder bore. Infiniti claims that the VC-T is capable of providing any desired compression ratio between 8.0:1 (for performance) and 14.0:1 (for high efficiency).

The VC-T comes with port and direct fuel-injection systems but in addition to this it also gets an individual cylinder ignition timing, variable intake- and exhaust-valve timing, and electronic boost control. Infiniti has managed to save some weight too by integrating the exhaust manifold with the cylinder head, and by making the block and head of aluminum. This will also make sure that the cost remains on the lower side too.

With a development target power output of approximately 268 hp and 390 Nm torque, the VC-Turbo engine will be comparable to certain six-cylinder gasoline powertrains for performance, while significantly outperforming them in efficiency. The four-cylinder VC-Turbo engine achieves lower levels of noise and vibration than conventional internal combustion engines, particularly diesel, and is lighter and more compact than V6 units with comparable power outputs.

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