Multi-chamber rotary piston actuator

A method of rotary actuation comprising:

• providing a rotary actuator comprising:
• a housing defining:
• a first arcuate chamber defining a first arcuate chamber wall defining a first ring segment in a plane between a first open end and a first enclosed end and having a first fluid port in fluid communication with the first arcuate chamber, the first ring segment having a first outer radius in the plane and defining an axis perpendicular to the plane, a first inner radius in the plane about the axis, and a first central radius in the plane;
• a second arcuate chamber comprising an inner chamber wall defining a second ring segment in the plane between a second open end and a second enclosed end and having a second fluid port in fluid communication with the second arcuate chamber, the second ring segment having a second outer radius from the axis, larger than the first outer radius and concentric with the first outer radius about the axis in the plane, a second inner radius smaller than the first inner radius in the plane, and a second central radius substantially the same as the first central radius, wherein the second arcuate chamber is oriented rotationally opposite to the first arcuate chamber about the axis and wherein at least a portion of the first arcuate chamber housing is enclosed within at least a portion of the second arcuate chamber in the plane and defining an arcuate tubular space between the first arcuate chamber housing and the inner chamber wall;
• and
• an arcuate actuation space defining a third arc in the plane about the axis between the first open end and the second open end;
• a rotor arm configured for rotary movement within the arcuate actuation space along the third arc;
• a rotor assembly coupled to the rotor arm;
• an arcuate-shaped first piston disposed in said first housing for reciprocal movement in the first arcuate chamber and in the plane through the first open end, wherein a first seal, the first arcuate chamber, and the first piston define a first pressure chamber, and a first portion of the first piston contacts the rotor arm;
• and
• a tubular, arcuate-shaped second piston disposed in said housing for reciprocal movement in the second arcuate chamber, in the arcuate tubular space and in the plane through the second open end, wherein a second seal, a third seal, the second arcuate chamber, and the second piston define a second pressure chamber, and a second portion of the second piston contacts the rotor arm;
• applying pressurized fluid to the first pressure chamber;
• urging the first piston partially outward from the first pressure chamber to urge movement of the rotor arm in a first direction;
• rotating the rotor arm in a second direction opposite that of the first direction;
• and,
• urging the first piston partially into the first pressure chamber to urge pressurized fluid out the first fluid port.

An arm of a machine apparatus comprising:

• a first arm portion;
• a second arm portion;
• and
• a joint portion pivotally connecting the first arm portion to the second arm portion, the joint portion comprising a rotary actuator comprising:
• a housing defining:
• a first arcuate chamber housing defining a first arcuate chamber defining a first ring segment in a plane between a first open end and a first enclosed end and having a first fluid port in fluid communication with the first arcuate chamber, the first ring segment having a first outer radius in the plane and defining an axis perpendicular to the plane, a first inner radius in the plane about the axis, and a first central radius in the plane;
• a second arcuate chamber comprising an inner chamber wall defining a second ring segment in the plane between a second open end and a second enclosed end and having a second fluid port in fluid communication with the second arcuate chamber, the second ring segment having a second outer radius from the axis, larger than the first outer radius and concentric with the first outer radius about the axis in the plane, a second inner radius smaller than the first inner radius in the plane, and a second central radius substantially the same as the first central radius, wherein the second arcuate chamber is oriented rotationally opposite to the first arcuate chamber about the axis and wherein at least a portion of the first arcuate chamber housing is enclosed within at least a portion of the second arcuate chamber in the plane and defining an arcuate tubular space between the first arcuate chamber housing and the inner chamber wall;
• and
• an arcuate actuation space defining a third arc in the plane about the axis between the first open end and the second open end;
• a rotor arm configured for rotary movement within the arcuate actuation space along the third arc;
• a rotor assembly coupled to the rotor arm;
• an arcuate-shaped first piston disposed in said first housing for reciprocal movement in the first arcuate chamber and in the plane through the first open end, wherein a first seal, the first arcuate chamber, and the first piston define a first pressure chamber, and a first portion of the first piston contacts the rotor arm;
• and
• a tubular, arcuate-shaped second piston disposed in said housing for reciprocal movement in the second arcuate chamber, in the arcuate tubular space and in the plane through the second open end, wherein a second seal, a third seal, the second arcuate chamber, and the second piston define a second pressure chamber, and a second portion of the second piston contacts the rotor arm.