VC-Turbo| First Variable Compression Ratio Engine Explained
As many of you would know, an engine with variable compression ration will not be found on any car. But Infiniti had a solution.
Variable compression ration technology represents a breakthrough in powertrain development. The VC-Turbo changes its compression ratio seamlessly with an advanced multi-link system, continuously raising or lowering the pistons reach to transform compression ratio, offering both power and efficiency, on demand.
A high compression ratio offers to the driver a greater efficiency but it can comes with an disadvantage like in certain applications poses the risk of premature combustion or also known as knocking. A low compression ratio gives the possibility to obtain greater power and torque and in the same time to avoid knocking. What Infiniti has on QX50's engine, is a compression ratio between 8:1 (for high performance) and 14:1 (for high efficiency). The VC-Turbo engine power output (264 hp/200kW and 280lb-ft/380 Nm) is higher than many competing turbocharged gasoline engines, and comes close to the performance of some V6 gasoline engines.
Other highlights include compact packaging and some materials that will make it very light. The engine block and cylinder head are cast in aluminum alloy and the multi-link components are made from high-carbon steel alloy.
So the interesting part from this engine will remain the multi-link system. Together with the multi-link system, the engine has an electric motor with a unique Harmonic Drive gear to transform its compression ratio. The electric motor is connected to the Harmonic Drive with a control arm. As the harmonic Drive rotates, the control shaft at the base of the engine rotates, moving the multi-link system within the engine. As the angle of the multi-link arms changes, it adjusts the top-dead position of the piston and the compression ratio with them. An eccentric control shaft changes the compression ratio of all the cylinders at the same time. So in the end, the engine capacity varies between 1,997 cc (low ratio) and 1,970 cc (high ratio). The VC-Turbo can switch between Atkinson and regular combustion cycles without interruption.
In the Atkinson cycle, air and fuel intakes overlap, allowing the fuel in the combustion chamber to expand to larger volumes for greater efficiency. The Atkinson cycle operates under higher compression ratios, with longer piston strokes allowing the intake valves to open for a short time as the compression stroke starts. When the compression ratio drops, the engine reverts to a regular combustion cycle-intake, compression, combustion, exhaust-in separate phases to enable greater performance.
To help even more, a single-scroll turbocharger maximizes performance and efficiency and at the same time will reduce the loss of thermal energy and exhaust pressure. The engine has a low friction "mirror bore coating" which reduces with 44% the cylinder friction. This coating is applied by a plasma jet, then hardened and honed to create ultra-smooth cylinder walls.
Find more here:
INFINITI VC-Turbo | Variable Compression Turbo Engine - NAIAS 2018 Detroit
Infiniti VC Turbo Engine vs. Conventional Engine
Copyright Infiniti
Variable compression ration technology represents a breakthrough in powertrain development. The VC-Turbo changes its compression ratio seamlessly with an advanced multi-link system, continuously raising or lowering the pistons reach to transform compression ratio, offering both power and efficiency, on demand.
A high compression ratio offers to the driver a greater efficiency but it can comes with an disadvantage like in certain applications poses the risk of premature combustion or also known as knocking. A low compression ratio gives the possibility to obtain greater power and torque and in the same time to avoid knocking. What Infiniti has on QX50's engine, is a compression ratio between 8:1 (for high performance) and 14:1 (for high efficiency). The VC-Turbo engine power output (264 hp/200kW and 280lb-ft/380 Nm) is higher than many competing turbocharged gasoline engines, and comes close to the performance of some V6 gasoline engines.
Other highlights include compact packaging and some materials that will make it very light. The engine block and cylinder head are cast in aluminum alloy and the multi-link components are made from high-carbon steel alloy.
So the interesting part from this engine will remain the multi-link system. Together with the multi-link system, the engine has an electric motor with a unique Harmonic Drive gear to transform its compression ratio. The electric motor is connected to the Harmonic Drive with a control arm. As the harmonic Drive rotates, the control shaft at the base of the engine rotates, moving the multi-link system within the engine. As the angle of the multi-link arms changes, it adjusts the top-dead position of the piston and the compression ratio with them. An eccentric control shaft changes the compression ratio of all the cylinders at the same time. So in the end, the engine capacity varies between 1,997 cc (low ratio) and 1,970 cc (high ratio). The VC-Turbo can switch between Atkinson and regular combustion cycles without interruption.
In the Atkinson cycle, air and fuel intakes overlap, allowing the fuel in the combustion chamber to expand to larger volumes for greater efficiency. The Atkinson cycle operates under higher compression ratios, with longer piston strokes allowing the intake valves to open for a short time as the compression stroke starts. When the compression ratio drops, the engine reverts to a regular combustion cycle-intake, compression, combustion, exhaust-in separate phases to enable greater performance.
To help even more, a single-scroll turbocharger maximizes performance and efficiency and at the same time will reduce the loss of thermal energy and exhaust pressure. The engine has a low friction "mirror bore coating" which reduces with 44% the cylinder friction. This coating is applied by a plasma jet, then hardened and honed to create ultra-smooth cylinder walls.
Find more here:
INFINITI VC-Turbo | Variable Compression Turbo Engine - NAIAS 2018 Detroit
Infiniti VC Turbo Engine vs. Conventional Engine
Copyright Infiniti
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