Hydraulic regenerative braking and four wheel drive system

A hydraulic unit adapted for use with a wheel of a vehicle to operate as pump to pump fluid or as a motor to turn the wheel or both, the hydraulic unit comprising:

• a rotary cam adapted to be affixed to the wheel to turn therewith and having a plurality of lobes;
• a plurality of circumaxially spaced and radially extending cylinders;
• a plurality of pistons, each piston having a body and a follower, each follower being engageable with the lobes of the rotary cam to reciprocate its piston within a cylinder to pump fluid from the cylinder as the rotary cam rotates and the body having a circumferentially extending seal recess;
• and
• a seal ring received within the seal recess to seal between the piston and the cylinder, the seal ring being C-shaped in cross-section having an annular recess in its outer diameter and including a first segment, a second segment and an intermediate bight segment connecting therebetween and defining the annular recess, and the bight segment having openings extending from its outer diameter to its inner diameter;
• wherein when the seal ring is subjected to fluids having differing pressures on each of its first and second segments, that segment adjacent the lower pressure fluid seals between the piston and the cylinder with the other of the first or second segments being surrounded by the higher pressure fluid such that only the segment subject to the lower pressure fluid seals between the piston and the cylinder.

A hydraulic unit adapted for use with a wheel of a vehicle to operate as pump to pump fluid or as a motor to turn the wheel or both, the hydraulic unit comprising:

• a rotary cam adapted to be affixed to the wheel to turn therewith and having a plurality of lobes;
• a plurality of circumaxially spaced and radially extending cylinders;
• a plurality of pistons, each piston having a body and a follower assembly;
• at least one follower assembly having a yoke with a pair of laterally spaced apart arms, a roller pin extending longitudinally between and being supported by the arms of the yoke, a roller which rolls along a planar central path upon the rotary cam creating a variable radial force therebetween, bearings located between the roller and the roller pin which allow the roller to rotate about the roller pin and a compliant spring interposed between an arm of the yoke and the roller or the bearings to position the roller relative to the arms of the yoke;
• wherein the compliant spring allows the roller to longitudinally stray from the planar central path during high radial force portions of its piston's reciprocation and then returns the roller to the central planar path during low radial force portions of its piston's reciprocation.

A hydraulic unit adapted for use with a wheel of a vehicle to operate as pump to pump fluid or as a motor to turn the wheel or both, the hydraulic unit comprising:

• a rotary cam adapted to be affixed to the wheel to turn therewith and having a plurality of lobes;
• a plurality of circumaxially spaced and radially extending cylinders;
• a plurality of pistons, each piston having a body and a follower, each follower being engageable with the lobes of the rotary cam to reciprocate its piston within a cylinder to pump fluid from the cylinder as the rotary cam rotates;
• a stationary member supporting the cylinders and being adapted to affix to the vehicle;
• and
• a pair of laterally spaced sealing mechanisms which seal between the stationary member and the rotary cam to provide an annular scavenge chamber for collecting fluid which escapes from between the pistons and the cylinders, at least one sealing mechanism including:
• an annular non-rotating intermediate member which pilots relative to and remains concentric with the rotary cam during rotation of the rotary cam;
• an annular dynamic seal interposed between the intermediate member and the rotary cam to accommodate rotational movement between the intermediate member and the rotary cam;
• and
• an annular static seal interposed between the intermediate member and the stationary member to seal and to accommodate radial movement therebetween during rotation of the rotary member.