Variable valve timing camshaft with improved oil transfer between inner and outer shafts

An adjustable camshaft comprising:

• an outer shaft that is hollow and includes a first radial opening;
• and
• an inner shaft disposed in the outer shaft and rotatable with respect to the outer shaft, the inner shaft including a cavity that receives oil and a second radial opening, wherein oil flows between the cavity of the inner shaft and an outside of the outer shaft during overlap of the first and second radial openings,
• wherein at least one of
• a cross-section of the first radial opening is greater on an inside of the outer shaft than on the outside of the outer shaft, or
• a cross-section of the second radial opening is greater on an outside of the inner shaft than on an inside of the inner shaft,
• wherein the second radial opening is one of a plurality of radial openings that are evenly distributed about a circumference of the inner shaft and enclose a same angle relative to one another,
• wherein the first radial opening is one of a plurality of radial openings that are distributed unevenly about a circumference of the outer shaft.

An adjustable camshaft comprising:

• an outer shaft that is hollow and includes a first radial opening;
• and
• an inner shaft disposed in the outer shaft and rotatable with respect to the outer shaft, the inner shaft including a cavity that receives oil and a second radial opening, wherein oil flows between the cavity of the inner shaft and an outside of the outer shaft during overlap of the first and second radial openings,
• wherein at least one of
• a cross-section of the first radial opening is greater on an inside of the outer shaft than on the outside of the outer shaft, or
• a cross-section of the second radial opening is greater on an outside of the inner shaft than on an inside of the inner shaft,
• wherein the first radial opening is one of a plurality of radial openings that are evenly distributed about a circumference of the outer shaft and enclose a same angle relative to one another,
• wherein the second radial opening is one of a plurality of radial openings that are distributed unevenly about a circumference of the inner shaft.