A radial piston rotary device with compact gear drive mechanism, comprising:
- a base;
- a casing mounted to the base, the casing having an inner chamber;
- an endcap detachably mounted to an axial end of the casing to cover the casing;
- a rotary piston assembly rotatably mounted inside the chamber, the radial piston assembly having a pair of rotary first radial pistons and a pair of rotary second radial pistons, relative rotations of the first radial pistons and the second radial pistons forming and defining variable volume sub-chambers between adjacent radial pistons, each pair of first radial pistons and second radial pistons rotating at out-of-phase cyclically varying velocities with respect to each other during operation;
- the rotary piston assembly including:
- i) an elongate first rotary piston shaft rotatably mounted inside the chamber, said first rotary piston shaft having one end extending axially out a back end of said casing, said pair of first radial pistons extending radially in diametrically opposite directions from the opposite end of said first rotary piston shaft, and
- ii) an elongate second rotary piston shaft coaxially mounted to said first rotary piston shaft, said second rotary piston shaft having one end extending axially out said back end of said casing through said first rotary piston, said pair of second radial pistons extending radially in diametrically opposite directions from the opposite end of said second rotary piston shaft, said first radial pistons and said second radial pistons having a rotary meshed engagement with each other when assembled;
- a gearbox coupled to the casing, the gearbox having an inner chamber;
- an endcap detachably mounted to an axial end of the gearbox to cover the inner chamber;
- a gear assembly mounted inside the gearbox and coupled to the radial piston assembly, the gear assembly controlling the relative angular velocities of the first radial pistons and the second radial pistons to maintain an asynchronous, out-of-phase angular velocity relationship;
- the gear assembly including:
- i) an annular rack disposed inside said chamber of said gearbox, said annular rack having a plurality of inner gear teeth and divided into a first section and a second section;
- ii) a first planetary gear engaging said first section of said annular rack and orbital thereon, said first planetary gear having an eccentric crank pin extending axially from one face of said first planetary gear and a driver pin extending axially from the opposite face of said first planetary gear;
- and
- iii) a second planetary gear engaging said second section of said annular rack and orbital thereon, said second planetary gear being axially spaced from said first planetary gear, said second planetary gear having an eccentric crank pin extending axially from one face of said second planetary gear and a driver pin extending axially from the opposite face of said second planetary gear, the orbital movement of said planetary gears driving said flywheel assembly;
- a crank assembly coupling the rotary piston assembly to the gear assembly, the crank assembly transferring rotations of the first radial pistons and the second radial pistons to the gear assembly;
- and
- a flywheel assembly coupled to the gear assembly inside the inner chamber, the flywheel assembly having an elongate drive shaft axially extending out of the endcap of the gearbox to be coupled to at least one driven component, the gear assembly converting the out-of-phase angular velocities of the pairs of first radial pistons and second radial pistons into a uniform synchronous powered rotation of the drive shaft, the flywheel assembly including:
- i) an annular flywheel disposed inside the chamber of the gearbox adjacent said gear assembly;
- ii) a cross beam extending diametrically across the flywheel;
- iii) a pair of spaced driver sockets disposed on the cross beam, each driver socket adapted to receive a corresponding driver pin from the planetary gears;
- and
- iv) the drive shaft extends axially from the cross beam, and orbital movement of the planetary gears rotate the flywheel at uniform angular velocities to output power to the drive shaft.