Recently, we're seeing more about the dying Internal Combustion Engines. Lining up with it, today we're going to see about the offset crank or offset cylinder. Heard of it....? Yeah... Yamaha's BlueCore and Honda's HET refers this offset crank.. In this short article, let's understand what's this offset cylinder is all about.
In a conventional type of IC engine with normal crank angle, the piston inside the cylinder will be pushed down at the third stroke of the combustion cycle. If we take a closer look when the piston is at the Top Dead Center(TDC) of the cylinder, both the piston's pin and crank's center axis are aligned in a straight line.
The angle all together results is increased side thrust i.e the force exerted by the piston against the cylinder wall. To rectify this problem, conrod should be made strong, resulting in high reciprocating mass which directly affects the combustion power and efficiency. This problem can be avoided by increasing the length of the conrod resulting in another problem of power to weigh ratio and increased size of the engine.
Offset cylinders comes handy here. Simply, the cylinder is slightly offsetted from the crankshaft. The axis of the piston and conrod are vertically aligned at the power stroke of the combustion process exactly when the cylinder's pressure is at its peak. Piston's side thrust is greatly reduced resulting in good combustion efficiency.
There are many benefits on using this offset cylinder method. The length of the piston skirt can be reduced and so the force experienced by the piston which allows the bike makers to use lighter pistons and also the mechanical friction. Compact engines can be built by using this method as the size of the engine and the losses are reduced ultimately.
The word asymmetrical made everything more beautiful from the old S1000RR's headlamp to this offset cylinder.
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Crossplane crankshaft
In a conventional type of IC engine with normal crank angle, the piston inside the cylinder will be pushed down at the third stroke of the combustion cycle. If we take a closer look when the piston is at the Top Dead Center(TDC) of the cylinder, both the piston's pin and crank's center axis are aligned in a straight line.
The angle all together results is increased side thrust i.e the force exerted by the piston against the cylinder wall. To rectify this problem, conrod should be made strong, resulting in high reciprocating mass which directly affects the combustion power and efficiency. This problem can be avoided by increasing the length of the conrod resulting in another problem of power to weigh ratio and increased size of the engine.
There are many benefits on using this offset cylinder method. The length of the piston skirt can be reduced and so the force experienced by the piston which allows the bike makers to use lighter pistons and also the mechanical friction. Compact engines can be built by using this method as the size of the engine and the losses are reduced ultimately.
The word asymmetrical made everything more beautiful from the old S1000RR's headlamp to this offset cylinder.
Related articles
Crossplane crankshaft
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