Cranktrain phase adjuster for variable compression ratio

A phase adjuster assembly for adjusting a phase between a driving component and driven component of an internal combustion engine, the phase adjuster assembly comprising:

• an input gear configured to be driven by the driving component;
• an output gear configured to drive the driven component and connected to a hub;
• a piston plate assembly configured to adjust a phase between the driving component and the driven component via axial displacement of the piston plate assembly, the piston plate assembly including a first piston control chamber on a first side of the piston plate assembly, and a second piston control chamber on a second side of the piston plate assembly, wherein a radial inner boundary of at least one of the first piston control chamber or the second piston control chamber is defined by the hub;
• and
• a hydraulic fluid system configured to selectively provide hydraulic fluid to the first piston control chamber and the second piston control chamber to axially displace the piston plate assembly such that the phase between the driving component and the driven component is adjusted.