Multi-chambered rotary piston actuator

Abstract

The subject matter of this document can be embodied in a fluid actuator, including a housing defining a first chamber, the first chamber including a first cavity and a first open end, a first piston assembly including a tubular first piston, the tubular first piston defining a second chamber, the second chamber including a second cavity and a second open end, the tubular first piston disposed within the first housing for reciprocal movement in the first chamber through the first open end, wherein a first seal, the first cavity, and the first piston define a first pressure chamber, a second piston assembly including a second piston, the second piston disposed within the first piston assembly for reciprocal movement in the second chamber through the second open end, wherein a second seal, the second cavity, and the second piston define a second pressure chamber, and a first portion of the second piston contacts a first end effector.

Description

[0001] This application is a divisional application of the patent application filed on August 4, 2017, with application number 201780062254.8 (international application number PCT / US2017 / 045628) and entitled "Multi-chamber rotary piston actuator". Priority Statement

[0002] This application claims priority to the following U.S. Provisional Patent Application No. 62 / 371,317, filed August 5, 2016; U.S. Provisional Patent Application No. 62 / 449,879, filed January 24, 2017; U.S. Patent Application No. 15 / 669,186, filed August 4, 2017; and U.S. Patent Application No. 15 / 669,314, filed August 4, 2017, the contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to actuator devices, and more particularly to rotary piston actuator devices, wherein the piston of the rotor is moved by a pressurized fluid. Background Technology

[0004] Various forms of linear hydraulic actuators are currently used in industrial machinery power conversion applications. A common industrial application is in construction machinery (e.g., excavators, backhoe loaders), where the linear motion of a hydraulic piston is converted into rotational motion around a joint. In specific applications, such as actuators for heavy machinery operation, increased actuation speed, wide range of motion, efficient use of hydrodynamics, and ease of maintenance are desirable. However, despite their widespread use, these characteristics may be difficult to provide in typical heavy machinery applications of linear hydraulic actuators, such as on the boom and bucket of excavators.

[0005] Various forms of rotary hydraulic actuators are also used in other types of industrial machinery power conversion applications. This industrial application is typically used for applications where continuous inertial loading is desired without the need for prolonged load holding, such as aircraft using rotary blade actuators on flight control surfaces, and applications where load holding is not an issue, such as backhoe loaders using hydraulic motors to horizontally pivot the compartment or boom relative to the chassis. However, the design of such actuators does not scale well to provide the combination of field availability and / or power-to-weight ratio, field availability characteristics, stiffness, holding capacity, torque-to-weight ratio, swing rate, and energy efficiency that heavy machinery operators typically expect their machinery to be usable elsewhere, for example, the actuation of the boom's vertical direct head. Summary of the Invention

[0006] This article generally deals with rotary piston actuators.

[0007] In a first aspect, a rotary piston actuator assembly includes a first rotary actuator, the first rotary actuator including a first housing, an arched first piston disposed in the first housing, and a first arched bearing sleeve assembly, the first housing defining a first arched chamber including a first cavity having a first open end, the arched first piston being configured to reciprocate within the first arched chamber through the first open end, and the first arched bearing sleeve assembly having an inner surface configured to contact the radially outer side of the first piston.

[0008] In a second aspect, according to aspect one, the first arched bearing sleeve includes an arched support portion and an arched inner liner portion, the arched inner liner portion being configured to conform to the inner surface of the arched support portion.

[0009] In a third aspect, according to aspect one or two, the first arched bearing sleeve assembly is removably fixed to the first housing.

[0010] In a fourth aspect, according to any one of aspects one to three, the first rotary actuator further includes a rotor assembly rotatably surrounding the first housing and defining a first central bore within the inner wall of the rotor assembly, wherein a first arched bearing sleeve assembly is radially arranged between the first piston and the inner wall and contacts the inner wall and the radially outer side of the first piston.

[0011] In the fifth aspect, according to aspect four, the first arched bearing sleeve assembly is arranged radially between the first piston and the inner wall, and contacts the inner wall and the radially outer side of the first piston.

[0012] In a sixth aspect, according to aspect four or five, the rotary actuator further includes a fluid delivery shaft having an elongated body, the fluid delivery shaft being disposed in a second central bore defined by the first housing and in fluid communication with the first cavity.

[0013] In the seventh aspect, according to any one of aspects four to six, the rotor assembly further includes a rotating output tube about an axis and a rotor arm that contacts a first portion of the first piston, the rotor arm extending radially outward to and connected to the rotating output tube.

[0014] In the eighth aspect, according to any one of aspects four to seven, the rotary actuator further includes a second rotary actuator disposed within the first central borehole.

[0015] In a ninth aspect, according to aspect eight, the second rotary actuator further includes a second housing and an arched second piston disposed in the second housing, the second housing defining a second arched chamber including a second cavity having a second open end, the arched second piston being used for reciprocating motion in the second arched chamber through the second open end.

[0016] In the tenth aspect, according to aspect nine, the rotary actuator further includes a second arched bearing sleeve assembly, the second arched bearing sleeve assembly being arranged radially between the second piston and the inner wall, and contacting the inner wall and the radially outer side of the second piston.

[0017] In the eleventh aspect, according to any one of aspects one through ten, the first arched bearing sleeve includes a group of bearings.

[0018] In the twelfth aspect, according to any one of aspects one through eleven, the first arched bearing sleeve includes a friction-reducing coating.

[0019] In a thirteenth aspect, a rotary actuation method includes: providing a first rotary actuator, the first rotary actuator including a first housing, an arched first piston disposed in the first housing, and a first arched bearing sleeve assembly, the first housing defining a first arched chamber, the first arched chamber including a first cavity having a first open end, the arched first piston being configured to reciprocate within the first arched chamber via the first open end, wherein a first seal, the first cavity, and the first piston define a first pressure chamber, the first pressure chamber including a portion or all of the first arched chamber, the first arched bearing sleeve assembly having an inner surface configured to contact the radially outer side of the first piston; forcing the first piston to rotate outward from a portion of the first pressure chamber; and applying a first radial force to the radially outer side of the piston via the first arched bearing sleeve portion.

[0020] In the fourteenth aspect, according to aspect thirteen, the method further includes: forcing the first piston portion radially outward; contacting the first piston with the first arched bearing sleeve assembly by a second radial force; transmitting the second radial force to the first housing; and constraining the second radial force through the first arched bearing sleeve assembly.

[0021] In a fifteenth aspect, according to aspect thirteen or fourteen, the method further includes: providing a second rotary actuator, wherein the rotor assembly is rotatably positioned around the first rotary actuator and the second rotary actuator.

[0022] In a sixteenth aspect, according to any one of aspects thirteen to fifteen, the method further includes: redirecting a first radial force through a first arched bearing sleeve assembly to a rotor assembly, the rotor assembly being rotatably circumferentially surrounding the first housing and defining a central bore within the inner wall of the rotor assembly, wherein the first arched bearing sleeve assembly is removably attached to the first housing.

[0023] In the seventeenth aspect, according to any one of aspects thirteen to sixteen, the method further includes redirecting the first radial force to the first housing via the first arched bearing sleeve assembly, wherein the first arched bearing sleeve assembly is removably fixed to the first housing.

[0024] In the eighteenth aspect, according to any one of aspects thirteen to seventeen, applying a first radial force to the radially outer side of the piston through the first arched bearing sleeve portion further includes applying a first radial force to a group of bearings in contact with the radially outer side of the piston.

[0025] In the nineteenth aspect, according to any one of aspects thirteen to eighteen, the first arched bearing sleeve portion includes a friction-reducing coating, and wherein applying a first radial force to the radially outer side of the piston through the first arched bearing sleeve portion further includes applying the first radial force to the friction-reducing coating that is in contact with the radially outer side of the piston.

[0026] In a twentieth aspect, a fluid actuator includes a housing defining a first chamber, a first piston assembly, and a second piston assembly. The first chamber includes a first cavity, a first fluid port in fluid communication with the first cavity, and a first open end. The first piston assembly includes a tubular first piston defining a second chamber. The second chamber includes a second cavity, a second fluid port in fluid communication with the second cavity, and a second open end. The tubular first piston is disposed within the first housing and is used for reciprocating motion in the first chamber via the first open end. A first seal, the first cavity, and the first piston define a first pressure chamber. The second piston assembly includes a second piston disposed within the first piston assembly and is used for reciprocating motion in the second chamber via the second open end. The second seal, the second cavity, and the second piston define a second pressure chamber, and a first portion of the second piston contacts a first end actuator.

[0027] In aspect 21, according to aspect 20, the first chamber is an arched first chamber, the arched first chamber including a first open end and a first closed end, the tubular first piston is an arched tubular first piston, the second chamber is an arched second chamber, the arched second chamber including a second open end and a second closed end, the second piston is an arched second piston, and the end actuator is a rotor arm.

[0028] In a twenty-second aspect, according to aspect twenty-one or twenty-one, the housing further defines a third arched chamber, the third arched chamber including a third cavity, a third fluid port in fluid communication with the third cavity, and a third open end; the first piston assembly further includes an arched tubular third piston defining a fourth arched chamber, the fourth arched chamber including a fourth cavity, a fourth fluid port in fluid communication with the fourth cavity, and a fourth open end; the arched tubular third piston is disposed in the first housing for reciprocating within the third arched chamber via the third open end, wherein the third seal, the third cavity, and the third piston define a third pressure chamber; the second piston assembly further includes an arched fourth piston disposed in the first piston assembly for reciprocating within the fourth arched chamber via the fourth open end, wherein the fourth seal, the fourth cavity, and the fourth piston define a fourth pressure chamber, and a first portion of the fourth piston contacts the second end actuator.

[0029] In aspect 23, according to aspect 22, the fluid actuator further includes a rotor arm, wherein the first chamber is an arched first chamber, the tubular first piston is an arched tubular first piston, the second chamber is an arched second chamber, the second piston is an arched second piston, the third chamber is an arched third chamber, the tubular third piston is an arched tubular third piston, the fourth chamber is an arched fourth chamber, the fourth piston is an arched fourth piston, the first end actuator is a rotor arm, and the second end actuator is a rotor arm.

[0030] In aspect twenty-four, according to aspect twenty-three, the second piston is oriented in the same direction of rotation as the first piston.

[0031] In aspect twenty-five, according to aspect twenty-three, the second piston is oriented in the opposite direction of rotation to the first piston.

[0032] In the twenty-sixth aspect, according to aspect twenty-three, applying pressurized fluid to the third pressure chamber forces the third piston to partially move outward from the third pressure chamber, thereby forcing the first piston assembly to rotate in a first direction; applying pressurized fluid to the fourth pressure chamber forces the fourth piston to partially move outward from the fourth pressure chamber, thereby forcing the second piston assembly to rotate in a first direction; the rotation of the second piston assembly in a second direction opposite to the first direction forces the fourth piston to partially enter the fourth pressure chamber, thereby forcing the pressurized fluid to exit the fourth fluid port; and the rotation of the first piston assembly in the second direction forces the third piston to partially enter the third pressure chamber, thereby forcing the pressurized fluid to exit the third fluid port.

[0033] In the twenty-seventh aspect, according to any one of aspects twenty-one to twenty-six, the housing further defines an arched actuation space defining an actuation arc about an axis between the first open end and the terminal end, and the fluid actuator further includes a rotor assembly including a rotating output tube rotatably surrounding the housing, wherein a rotor arm extends radially outward to the rotating output tube and is coupled to the rotating tube.

[0034] In aspect 28, according to any one of aspects 21 to 27, the first seal is disposed around the inner surface of the first open end.

[0035] In aspect twenty-nine, according to any one of aspects twenty-one to twenty-eight, the first seal is disposed around the perimeter of the first piston and configured to remain stationary relative to the first piston.

[0036] In the thirtieth aspect, according to any one of aspects 21 to 29, the second seal is disposed around the inner surface of the second open end.

[0037] In the thirty-first aspect, according to any one of aspects twenty-one to thirty, the second seal is disposed around the perimeter of the second piston and configured to remain stationary relative to the second piston.

[0038] In aspect thirty-two, according to any one of aspects twenty-one to thirty-one, the shell is formed as a single-piece shell.

[0039] In aspect thirty-three, according to any one of aspects twenty-one to thirty-two, the cross-section of the first piston has one of the following: square, rectangular, oval, elliptical, figure-eight, or circular.

[0040] In aspect thirty-four, according to any one of aspects twenty-one to thirty-three, the first piston assembly further defines a fluid port fluidly connecting the first chamber and the second chamber.

[0041] In aspect thirty-five, according to any one of aspects twenty-one to thirty-four, the first portion of the tubular first piston contacts the second end actuator.

[0042] In a thirty-sixth aspect, a fluid actuation method includes: providing a fluid actuator including a housing, a first piston assembly, and a second piston assembly, the housing defining a first chamber, the first chamber including a first cavity, a first fluid port in fluid communication with the first cavity, and a first open end; the first piston assembly including a tubular first piston defining a second chamber, the second chamber including a second cavity, a second fluid port in fluid communication with the second cavity, and a second open end; the tubular first piston being disposed in the first housing for reciprocating motion in the first chamber via the first open end, wherein a first seal, the first cavity, and the first piston define a first pressure chamber; and the second piston assembly including a second piston disposed in the first piston assembly for reciprocating motion via the second open end. The open end reciprocates in the second chamber, wherein the second seal, the second cavity, and the second piston define the second pressure chamber, and a first portion of the second piston contacts the first end actuator; pressurized fluid is applied to the first pressure chamber; the first piston is forced partially outward from the first pressure chamber to force the end actuator along a first direction; the end actuator is forced along a second direction opposite to the first direction; the first piston is forced partially into the first pressure chamber to force the pressurized fluid out of the first fluid port; pressurized fluid is applied to the second pressure chamber; the second piston is forced partially outward from the second pressure chamber to force the first piston assembly along a first direction; the first piston assembly along a second direction; and the second piston is forced partially into the second pressure chamber to force the pressurized fluid out of the second fluid port.

[0043] In the thirty-seventh aspect, according to aspect thirty-six, the first chamber is an arched first chamber including a first open end and a first closed end, the tubular first piston is an arched tubular first piston, the second chamber is an arched second chamber including a second open end and a second closed end, the second piston is an arched second piston, and the end actuator is a rotor arm. Forcing the first piston partially outward from the first pressure chamber to force the end actuator along the first direction further includes: rotating the rotor arm along the first direction with a substantially constant torque over the stroke. Forcing the second piston partially outward from the second pressure chamber to force the first piston assembly along the first direction further includes: rotating the first piston assembly along the first direction with a substantially constant torque over the stroke.

[0044] In a thirty-eighth aspect, an arm of a machine device includes a first arm portion, a second arm portion, and a joint portion connecting the first arm portion to the second arm portion. The joint portion includes a fluid actuator comprising: a housing, a first piston assembly, and a second piston assembly. The housing defines a first chamber, the first chamber including a first cavity, a first fluid port in fluid communication with the first cavity, and a first open end. The first piston assembly includes a tubular first piston defining a second chamber, the second chamber including a second cavity, a second fluid port in fluid communication with the second cavity, and a second open end. The tubular first piston is disposed in the first housing for reciprocating within the first chamber via the first open end. A first seal, the first cavity, and the first piston define a first pressure chamber. The second piston assembly includes a second piston disposed in the first piston assembly for reciprocating within the second chamber via the second open end. A second seal, the second cavity, and the second piston define a second pressure chamber. A first portion of the second piston contacts a first end actuator.

[0045] In aspect thirty-nine, according to aspect thirty-eight, the end effector is fixed to or integrated with the first arm portion.

[0046] In aspect 40, according to aspect 38 or 39, the shell is fixed to or integral with the second arm portion.

[0047] In a forty-first aspect, a multi-axis rotary actuator includes a first rotary piston actuator and a second rotary piston actuator, the first rotary piston actuator being configured to controllably actuate a first pivot joint between a first link and a second link about a first axis, and the second rotary piston actuator being configured to controllably actuate a second pivot joint connecting a second link to a third link about a second axis.

[0048] In aspect 42, according to aspect 41, the first axis is parallel to the second axis.

[0049] In aspect forty-three, according to aspect forty-one, the first axis is perpendicular to the second axis.

[0050] In aspect forty-four, according to aspect forty-one, the first axis intersects with the second axis.

[0051] In aspect 45, according to any one of aspects 41 to 44, at least one of the first and second rotary piston actuators includes a housing, a rotor arm, an arched first piston, and a rotor assembly. The housing defines a first arched chamber and an arched actuation space. The first arched chamber includes a first cavity that defines a first arcuate segment in a plane between a first open end and a first closed end, and has a first fluid port in fluid communication with the first cavity. The first arcuate segment has a first radius in the plane, which defines an axis perpendicular to the plane. The arched actuation space defines an actuation arcuate segment about an axis between the first open end and the terminal end. The rotor arm is configured to run along a second arcuate segment. Rotating motion within the actuation space, an arched first piston is disposed in the housing for reciprocating motion in a plane and within a first arched chamber via a first open end, wherein a first seal, a first cavity, and a first piston define a first pressure chamber comprising part or all of the first arched chamber, a first portion of the first piston contacts a rotor arm, a rotor assembly is rotatably disposed around the housing and includes a rotating cylinder about an axis, wherein the rotor arm extends radially outward to the rotating cylinder and is coupled to the rotating cylinder, wherein the housing is coupled to one of a first link, a second link, or a third link, and the rotor assembly is coupled to the other of the first link, the second link, or the third link.

[0052] In aspect 46, according to aspect 45, the multi-axis rotary actuator further includes a second arched chamber, the second arched chamber including a second cavity defining a second arc segment about an axis between a second open end and a second closed end, and having a second fluid port in fluid communication with the second cavity.

[0053] In aspect 47, according to aspect 46, the second arc segment has a second radius from the axis, the second radius being different from the first radius.

[0054] In aspect 48, according to aspect 47, the second arc segment is concentric with the first arc segment about the axis in the plane.

[0055] In aspect 49, according to aspect 48, the second open end is located at the terminal, and the arched chamber is oriented about the axis opposite to that of the first arched chamber in rotation.

[0056] In the fiftieth aspect, according to aspect forty-eight, the second arc segment is not in a plane, and at least a portion of the second arched chamber overlaps axially with the first arched chamber in a plane.

[0057] In the fifty-first aspect, according to aspect forty-eight, the multi-axis rotary actuator further includes an arched second piston disposed in the second housing for reciprocating motion in a second arched chamber via a second open end, wherein the second seal, the second cavity, and the second piston define a second pressure chamber comprising part or all of the second arched chamber, and a second portion of the second piston contacts the rotor arm.

[0058] In aspect 52, according to any of aspects 45 to 51, the rotor assembly provides load support for the housing.

[0059] In aspect 53, according to any one of aspects 45 to 52, at least one of the first rotary piston actuator and the second rotary piston actuator includes a housing defining a first arched chamber, a second arched chamber, and an arched actuation space. The first arched chamber includes a first cavity, which defines a first annular segment in a plane between a first open end and a first closed end, and has a first fluid port in fluid communication with the first cavity. The annular segment has a first outer radius in the plane, which defines an axis perpendicular to the plane, and has a first inner radius and a first middle radius in the plane. The second arched chamber includes an inner chamber wall defining a second cavity. The second cavity defines a second annular segment in a plane between a second open end and a second closed end, and has a second fluid port in fluid communication with the second cavity. The second annular segment has a second outer radius from the axis, which is greater than a first outer radius and concentric with the first outer radius in the plane about the axis. It also has a second inner radius in the plane smaller than the first inner radius, and the second inner radius is substantially the same as the first inner radius. The second arched chamber is oriented to be rotationally opposite to that of the first arched chamber about the axis. At least a portion of the shaped cavity shell is enclosed in a plane within a portion of the second arched cavity, thereby defining an arched tubular space between the first arched cavity shell and the inner cavity wall. The arched actuation space defines a third arc segment in the plane about an axis between a first open end and a second open end, a rotor arm, a rotor assembly, an arched first piston, and a tubular arched second piston. The rotor arm is configured to rotate along the third arc segment within the actuation space. The rotor assembly is coupled to the rotor arm. The arched first piston is disposed in the first shell for reciprocating motion in the plane and within the first arched cavity via the first open end. A first seal, a first cavity, and a first piston define a first pressure chamber. A first portion of the first piston contacts the rotor arm. A tubular, arched second piston is disposed in the second housing for reciprocating in the second arched chamber in a plane and in an arched tubular space via a second open end. A second seal, a third seal, a second cavity, and a second piston define a second pressure chamber, and a second portion of the second piston contacts the rotor arm. The housing is coupled to one of a first, second, or third link, and the rotor assembly is coupled to the other of the first, second, or third link.

[0060] In a fifty-fourth aspect, a multi-axis rotary actuation method includes: providing a multi-axis rotary actuator including a first rotary piston actuator and a second rotary piston actuator, the first rotary piston actuator being configured to controllably actuate a first pivot joint between a first link and a second link about a first axis, the second rotary piston actuator being configured to controllably actuate a second pivot joint about a second axis, the second pivot joint connecting a second link to a third link; applying pressurized fluid to the first rotary piston actuator; forcing the first pivot joint to actuate about the first axis in a first direction; forcing the first pivot joint to actuate about the first axis in a second direction opposite to the first direction; applying pressurized fluid to the second rotary piston actuator; forcing the second pivot joint to actuate about the second axis in a third direction; and forcing the second pivot joint to actuate about the second axis in a fourth direction opposite to the third direction.

[0061] In the fifty-fifth aspect, according to aspect fifty-four, applying pressurized fluid to the first rotary piston actuator further includes: applying pressurized fluid to a first pressure chamber of the first rotary piston actuator, the first pressure chamber being configured to force the first pivot joint to actuate in a first direction, and wherein applying pressurized fluid to the second rotary piston actuator further includes: applying pressurized fluid to a third pressure chamber of the second rotary piston actuator, the third pressure chamber being configured to force the second pivot joint to actuate in a third direction, and the method further includes: applying pressurized fluid to a second pressure chamber of the first rotary piston actuator, the second pressure chamber being configured to force the first pivot joint to actuate in a second direction; forcing the first pivot joint to actuate in the second direction about a first axis; applying pressurized fluid to a fourth pressure chamber of the second rotary piston actuator, the fourth pressure chamber being configured to force the first pivot joint to actuate in the second direction; and forcing the second pivot joint to actuate in the fourth direction about a second axis.

[0062] In a fifty-sixth aspect, an arm of a machine device includes a first arm portion, a second arm portion, and a joint portion pivotally connected to the second arm portion. The joint portion includes a multi-axis rotary actuator, which includes a first rotary piston actuator and a second rotary piston actuator. The first rotary piston actuator is configured to controllably actuate a first pivot joint between a first link and a second link about a first axis. The second rotary piston actuator is configured to controllably actuate a second pivot joint about a second axis, the second pivot joint connecting the second link to a third link.

[0063] In aspect 57, according to aspect 56, the first axis is parallel to the second axis.

[0064] In aspect 58, according to aspect 56, the first axis is perpendicular to the second axis.

[0065] In aspect 59, according to aspect 56, the first axis intersects with the second axis.

[0066] In the sixtieth aspect, according to any one of aspects 56 to 59, at least one of the first and second rotary piston actuators includes a housing, a rotor arm, an arched first piston, and a rotor assembly. The housing defines a first arched chamber and an arched actuation space. The first arched chamber includes a first cavity that defines a first arcuate segment in a plane between a first open end and a first closed end, and has a first fluid port in fluid communication with the first cavity. The first arcuate segment has a first radius in the plane, which defines an axis perpendicular to the plane. The arched actuation space defines an actuation arcuate segment about an axis between the first open end and the terminal end. The rotor arm is configured to run along a second arcuate segment. Rotational motion within the actuation space, an arched first piston disposed in the housing for reciprocating motion in a plane and within a first arched chamber via a first open end, wherein a first seal, a first cavity, and a first piston define a first pressure chamber comprising part or all of the first arched chamber, a first portion of the first piston contacts a rotor arm, a rotor assembly rotatably surrounds the housing and includes a rotating cylinder about an axis, wherein the rotor arm extends radially outward to the rotating cylinder and is coupled to the rotating cylinder, wherein the housing is coupled to one of a first link, a second link, or a third link, and the rotor assembly is coupled to the other of the first link, the second link, or the third link.

[0067] In a sixty-first aspect, a rotary piston actuator assembly includes a first rotary actuator, the first rotary actuator including a first housing, a rotor arm, an arched first piston, a rotor assembly, and a fluid delivery shaft. The first housing defines a first central bore and a first arched chamber, the first arched chamber including a first cavity having a first actuator fluid port in fluid communication with the first cavity and the first central bore. The arched first piston is disposed in the first housing for reciprocating motion within the first housing. A first seal, the first cavity, and the first piston define a first pressure chamber, the first pressure chamber including a portion or all of the first arched chamber. A first portion of the first piston contacts the rotor arm. The rotor assembly is rotatably disposed around the first housing and includes a rotary output tube. The rotor arm extends radially outward to the rotary output tube and is coupled to the rotary tube. The fluid delivery shaft has an elongated body disposed in the first central bore and defines a first-axis fluid delivery path.

[0068] In aspect sixty-two, according to aspect sixty-one, the rotary piston actuator assembly further includes a second rotary actuator including a second housing and an arched second piston. The second housing defines a second central bore and a second arched chamber. The second arched chamber includes a second cavity having a second actuator fluid port in fluid communication with the second cavity and the second central bore. The arched second piston is disposed in the second housing for reciprocating motion within the second housing. A second seal, the second cavity, and the second piston define a second pressure chamber including part or all of the second arched chamber. A first portion of the second piston contacts a rotor arm. The rotor assembly is rotatably disposed around the second housing, and a fluid delivery shaft is disposed in the second central bore.

[0069] In aspect sixty-third, according to aspect sixty-one or sixty-two, a fluid delivery shaft defines an axis and includes a first axial fluid port along the body, a second axial fluid port near a terminal of the body, and a first axial fluid delivery path defined by the fluid delivery shaft and fluidly connecting the first axial fluid port to the second axial fluid port. A first axial seal is disposed around the fluid delivery shaft along the axis on a first axial side of the first axial fluid port, and a second axial seal is disposed around the fluid delivery shaft along the axis on a second axial side of the first axial fluid port and opposite to the first axial seal. A first central bore, the body, the first axial fluid seal, and the second axial fluid seal define a first fluid transfer chamber, and a first actuator fluid port is in fluid communication with the first fluid transfer chamber.

[0070] In aspect sixty-four, according to aspect sixty-three, the first central borehole further defines a first borehole portion and a second borehole portion, wherein the first borehole portion extends substantially along a first half of the axial length of the first central borehole, the second borehole portion extends substantially along a second half of the axial length of the first central borehole, and a first actuator fluid port is defined within the first borehole portion, wherein a first fluid transfer chamber extends approximately half of the axial length of the first central borehole, such that the first fluid transfer chamber extends along the first borehole portion in a first assembly of the first rotary actuator and the fluid delivery shaft, and the first fluid transfer chamber extends along the second borehole portion in a second assembly of the first rotary actuator and the fluid delivery shaft.

[0071] In aspect sixty-five, according to any one of aspects sixty-one to sixty-four, the first arched chamber further defines a first open end, and the first piston further includes a first piston assembly, the first piston assembly including a tubular first piston defining a second chamber, the second chamber including a second cavity, a second fluid port in fluid communication with the second cavity, and a second open end, the tubular first piston being disposed within the first housing for reciprocating motion in the first chamber via the first open end, wherein the first seal, the first cavity, and the first piston define a first pressure chamber, and the rotary piston actuator further includes a second piston assembly including a second piston disposed within the first piston assembly for reciprocating motion in the second chamber via the second open end, wherein the second seal, the second cavity, and the second piston define a second pressure chamber, and a first portion of the second piston contacts the first end actuator.

[0072] In the sixty-sixth aspect, according to any one of aspects sixty-one to sixty-five, a first cavity defines a first arc segment in a plane between a first open end and a first closed end and has a first fluid port in fluid communication with the first cavity, the first arc segment having a first radius in the plane, the first radius defining an axis perpendicular to the plane, and a first housing further defining an arched actuation space that defines an actuation arc segment about an axis between the first open end and the terminal end, wherein a rotor arm is configured to rotate along a second arc segment within the actuation space, and a first piston is disposed in the first housing for reciprocating in a plane and within a first arched cavity via the first open end, wherein a first seal, the first cavity, and the first piston define a first pressure chamber, the first pressure chamber including part or all of the first arched cavity.

[0073] In aspect sixty-seven, according to any one of aspects sixty-one to sixty-six, the first housing includes a first arched chamber housing defining a first arched chamber, wherein the first cavity defines a first annular segment in a plane between a first open end and a first closed end, the annular segment having a first outer radius in the plane and defining an axis perpendicular to the plane, having a first inner radius in the plane about the axis, and having a first intermediate radius in the plane, wherein the first housing further defines a second arched chamber including an inner chamber wall defining a second cavity, the second cavity defining a second annular segment in a plane between a second open end and a second closed end, and having a second fluid port in fluid communication with the second cavity, the second annular segment having a second outer radius from the axis, the second outer radius being greater than the first outer radius and concentric with the first outer radius in the plane about the axis, having a second inner radius in the plane smaller than the first inner radius, and having a second intermediate radius substantially the same as the first intermediate radius, wherein the second arched chamber about the axis The rotor arm is oriented in the opposite direction to the first arched chamber in rotation, and wherein at least a portion of the first arched chamber housing is enclosed in a plane within at least a portion of the second arched chamber and defines an arched tubular space between the first arched chamber housing and the inner chamber wall, the arched actuation space defines a third arc segment in a plane about an axis between a first open end and a second open end, the rotor arm is configured to rotate along the third arc segment in the actuation space, wherein an arched first piston is disposed in the first housing for reciprocating in a plane and in the first arched chamber through the first open end, wherein a first seal, a first cavity and a first piston define a first pressure chamber, and wherein the rotary piston actuator assembly further includes a tubular arched second piston disposed in the second housing for reciprocating in a plane and in the arched tubular space in the second arched chamber through the second open end, wherein a second seal, a third seal, a second cavity and a second piston define a second pressure chamber, and a second portion of the second piston contacts the rotor arm.

[0074] In a sixty-eighth aspect, a rotary actuation method includes: providing a first rotary piston actuator, the first rotary actuator including a first housing, a rotor arm, an arched first piston, a rotor assembly, and a fluid delivery shaft, the first housing defining a first central borehole and a first arched chamber, the first arched chamber including a first cavity having a first actuator fluid port in fluid communication with the first cavity and the first central borehole, the arched first piston disposed in the first housing for reciprocating motion within the first housing, wherein a first seal, the first cavity, and the first piston define a first pressure chamber, the first pressure chamber including a portion or all of the first arched chamber, a first portion of the first piston contacting the rotor arm, and the rotor assembly rotatably surrounding the first housing and including a rotary output tube, wherein... The rotor arm extends radially outward to the rotary output tube and is coupled to the rotary tube. The fluid delivery shaft has an elongated body disposed in the first central bore and defines a first axial fluid delivery path. Pressurized fluid is supplied to a second axial fluid port. The pressurized fluid is forced through the first axial fluid delivery path, the first axial fluid port, the first fluid transfer chamber, and the first fluid port to a first pressure chamber. The first piston is forced partially outward from the first pressure chamber to force the rotor assembly to rotate in a first direction. The rotor assembly is rotated in a second direction opposite to the first direction. The first piston is forced partially into the first pressure chamber to force the pressurized fluid to leave the second axial fluid port through the first fluid port, the first fluid transfer chamber, the first axial fluid port, and the first axial fluid delivery path.

[0075] In a sixty-ninth aspect, according to aspect sixty-eight, the method further includes: removing a first rotary actuator from a first assembly configuration with a fluid delivery shaft; reassembling the first rotary actuator to the fluid delivery shaft in a second configuration; providing pressurized fluid to a second shaft fluid port; forcing the pressurized fluid through a first shaft fluid delivery path, the first shaft fluid port, a first fluid transfer chamber, and a first fluid port to a first pressure chamber; forcing a first piston partially outward from the first pressure chamber to force a rotor assembly to rotate in a second direction; rotating the rotor assembly in a direction opposite to the second direction; and forcing the first piston partially into the first pressure chamber to force the pressurized fluid out of the second shaft fluid port through the first fluid port, the first fluid transfer chamber, the first shaft fluid port, and the first shaft fluid delivery path.

[0076] In the seventieth aspect, according to aspects sixty-eight or sixty-nine, a first central borehole defines a first borehole portion and a second borehole portion, wherein the first borehole portion extends substantially along a first half of the axial length of the first central borehole, the second borehole portion extends substantially along a second half of the axial length of the first central borehole, and a first actuator fluid port is defined within the first borehole portion; and wherein a first fluid transfer chamber extends approximately half of the axial length of the first central borehole, such that the first fluid transfer chamber extends along the first borehole portion in a first assembly of the first rotary actuator and fluid delivery shaft, and the first fluid transfer chamber extends along the second borehole portion in a second assembly of the first rotary actuator and fluid delivery shaft.

[0077] In a seventy-first aspect, according to aspect seventy, the method further includes: removing a first rotary actuator from a first assembly configuration with a fluid delivery shaft, wherein a first central bore portion, a body, a first shaft fluid seal, and a second shaft fluid seal define a first fluid transfer chamber in the first configuration; reassembling the first rotary actuator to the fluid delivery shaft in a second configuration, wherein a second central bore portion, a body, a first shaft fluid seal, and a second shaft fluid seal define the first fluid transfer chamber in the second configuration; providing pressurized fluid to a second shaft fluid port; and preventing the flow of pressurized fluid through a first pressure chamber.

[0078] In a seventy-second aspect, an arm of a machine device includes a first arm portion, a second arm portion, and a joint portion pivotally connected to the second arm portion. The joint portion includes a first rotary actuator, the first rotary actuator including a first housing, a rotor arm, an arched first piston, a rotor assembly, and a fluid delivery shaft. The first housing defines a first central bore and a first arched chamber, the first arched chamber including a first cavity having a first actuator fluid port in fluid communication with the first cavity and the first central bore. The arched first piston is disposed in the first housing for reciprocating motion within the first housing. A first seal, the first cavity, and the first piston define a first pressure chamber, the first pressure chamber including part or all of the first arched chamber. A first portion of the first piston contacts the rotor arm. The rotor assembly is rotatably disposed around the first housing and includes a rotary output tube. The rotor arm extends radially outward to the rotary output tube and is coupled to the rotary tube. The fluid delivery shaft has an elongated body disposed in the first central bore and defines a first-axis fluid delivery path.

[0079] In aspect seventy-three, according to aspect seventy-two, the rotor assembly is fixed to or integral with the first arm portion.

[0080] In aspect seventy-four, according to aspect seventy-two or seventy-three, the shell is fixed to or integral with the second arm portion.

[0081] In aspect seventy-six, according to any one of aspects seventy-two to seventy-four, the arm further includes a second rotary actuator comprising a second housing and an arched second piston, the second housing defining a second central bore and a second arched chamber, the second arched chamber including a second cavity having a second actuator fluid port in fluid communication with the second cavity and the second central bore, the arched second piston being disposed in the second housing for reciprocating motion within the second housing, wherein a second seal, the second cavity, and the second piston define a second pressure chamber including part or all of the second arched chamber, and a first portion of the second piston contacts the rotor arm, wherein the rotor assembly is rotatably disposed around the second housing, and a fluid delivery shaft is disposed in the second central bore.

[0082] In the seventy-sixth aspect, according to any one of aspects seventy-two to seventy-five, a fluid delivery shaft defines an axis and includes a first axial fluid port along the body, a second axial fluid port near a terminal of the body, and a first axial fluid delivery path defined by the fluid delivery shaft and fluidly connecting the first axial fluid port to the second axial fluid port. A first axial seal is disposed around the fluid delivery shaft along the axis on a first axial side of the first axial fluid port, and a second axial seal is disposed around the fluid delivery shaft along the axis on a second axial side of the first axial fluid port and opposite to the first axial seal. A first central bore, the body, the first axial fluid seal, and the second axial fluid seal define a first fluid transfer chamber, and a first actuator fluid port is in fluid communication with the first fluid transfer chamber.

[0083] In aspect seventy-seven, according to aspect seventy-six, the first central borehole further defines a first borehole portion and a second borehole portion, wherein the first borehole portion extends substantially along a first half of the axial length of the first central borehole, the second borehole portion extends substantially along a second half of the axial length of the first central borehole, and a first actuator fluid port is defined within the first borehole portion, wherein a first fluid transfer chamber extends approximately half of the axial length of the first central borehole, such that the first fluid transfer chamber extends along the first borehole portion in a first assembly of the first rotary actuator and the fluid delivery shaft, and the first fluid transfer chamber extends along the second borehole portion in a second assembly of the first rotary actuator and the fluid delivery shaft.

[0084] In a seventy-eighth aspect, a rotary actuator includes a housing defining a first arched chamber housing, the first arched chamber housing defining a first arched chamber and a second arched chamber. The first arched chamber includes a first cavity, the first cavity defining a first annular segment in a plane between a first open end and a first closed end and having a first fluid port in fluid communication with the first cavity. The annular segment has a first outer radius in the plane and defines an axis perpendicular to the plane, has a first inner radius in the plane about the axis, and has a first intermediate radius in the plane. The second arched chamber includes an inner chamber wall defining a second cavity, the second cavity defining a second annular segment in a plane between a second open end and a second closed end and having a second fluid port in fluid communication with the second cavity. The second annular segment has a second outer radius from the axis, the second outer radius being greater than the first outer radius and concentric with the first outer radius in the plane about the axis, having a second inner radius in the plane smaller than the first inner radius, and having a second intermediate radius substantially the same as the first intermediate radius. An arched chamber is oriented about an axis in a rotational opposite direction to a first arched chamber, wherein at least a portion of the first arched chamber housing is enclosed in a plane within at least a portion of a second arched chamber and defines an arched tubular space between the first arched chamber housing and the inner chamber wall, an arched actuation space defines a third arc segment in a plane about an axis between a first open end and a second open end, a rotor arm is configured to rotate along the third arc segment within the actuation space, a rotor assembly is coupled to the rotor arm, an arched first piston is disposed in the first housing for reciprocating in a plane and within the first arched chamber via the first open end, wherein a first seal, a first cavity, and a first piston define a first pressure chamber, a first portion of the first piston contacts the rotor arm, a tubular arched second piston is disposed in the second housing for reciprocating in a plane and within the arched tubular space via the second open end, wherein a second seal, a third seal, a second cavity, and a second piston define a second pressure chamber, a second portion of the second piston contacts the rotor arm.

[0085] In aspect seventy-nine, according to aspect seventy-eight, at least a portion of the second arched chamber overlaps axially with the first arched chamber in the plane.

[0086] In aspect eighty, according to aspects seventy-eight or seventy-nine, the rotor assembly is rotatably supported in the housing by a journal and includes a rotating output shaft along an axis, wherein a rotor arm extends radially inward to the rotating output shaft and is coupled to the rotating output shaft.

[0087] In the eighty-first aspect, according to any one of aspects seventy-eight to eighty, the rotor assembly is rotatably disposed around the housing and includes a rotating output cylinder about an axis, wherein a rotor arm extends radially outward to the rotating output cylinder and is coupled to the rotating output cylinder.

[0088] In aspect 82, according to any one of aspects 78 to 81, the first seal is disposed around the inner surface of the open end and is configured to remain stationary relative to the open end.

[0089] In aspect 83, according to any one of aspects 78 to 82, the first seal is disposed around the perimeter of the first piston and is configured to remain stationary relative to the first portion.

[0090] In aspect 84, according to any one of aspects 78 to 83, the first seal provides load support for the first piston.

[0091] In aspect 85, according to any of aspects 78 to 84, the rotor assembly provides load support for the housing.

[0092] In aspect 86, according to any one of aspects 78 to 85, the shell is formed as a single-piece shell.

[0093] In aspect 87, according to any of aspects 78 to 86, the first seal is a single-piece seal.

[0094] In aspect 88, according to any of aspects 78 to 87, the cross-section of the first piston is solid.

[0095] In aspect 89, according to any one of aspects 78 to 88, the cross-section of at least one of the first piston and the second piston is at least partially hollow.

[0096] In aspect ninety, according to any one of aspects seventy-eight to eighty-nine, the cross-section of the first piston has one of the following: square, rectangular, oval, elliptical, figure-eight, or circular.

[0097] In a ninety-first aspect, a rotary actuation method includes: providing a rotary actuator including a housing defining a first arched chamber housing, the first arched chamber housing defining a first arched chamber and a second arched chamber, the first arched chamber including a first cavity, the first cavity defining a first annular segment in a plane between a first open end and a first closed end and having a first fluid port in fluid communication with the first cavity, the annular segment having a first outer radius in the plane and defining an axis perpendicular to the plane, having a first inner radius in the plane about the axis, and having a first middle radius in the plane, the second arched chamber including... An inner chamber wall defines a second cavity, the second cavity defining a second annular segment in a plane between a second open end and a second closed end, and having a second fluid port in fluid communication with the second cavity. The second annular segment has a second outer radius from the axis, the second outer radius being larger than a first outer radius and concentric with the first outer radius in the plane about the axis, and has a second inner radius in the plane smaller than the first inner radius, and has a second intermediate radius substantially the same as the first intermediate radius. The second arched cavity is oriented in rotation opposite to the first arched cavity about the axis, and at least a portion of the first arched cavity shell... An arched tubular space is defined in a plane, enclosed within at least a portion of a second arched chamber and defined between a first arched chamber housing and an inner chamber wall. An arched actuation space defines a third arc segment in a plane about an axis between a first open end and a second open end. A rotor arm is configured to rotate along the third arc segment within the actuation space. A rotor assembly is coupled to the rotor arm. An arched first piston is disposed in the first housing for reciprocating motion in a plane and within the first arched chamber via a first open end. A first seal, a first cavity, and a first piston define a first pressure chamber. A first portion of the first piston contacts the rotor arm. An arched second piston is disposed in the second housing for reciprocating in a second arched chamber in a plane and in an arched tubular space via a second open end, wherein a second seal, a third seal, a second cavity, and a second piston define a second pressure chamber, and a second portion of the second piston contacts the rotor arm; pressurized fluid is applied to the first pressure chamber; the first piston is forced partially outward from the first pressure chamber to force the rotor arm to move in a first direction; the rotor arm is rotated in a second direction opposite to the first direction; and the first piston is forced partially into the first pressure chamber to force the pressurized fluid out of the first fluid port.

[0098] In aspect ninety-two, according to aspect ninety-one, rotating the rotor arm in a second direction opposite to the first direction comprises: applying pressurized fluid to a second pressure chamber and forcing a second piston partially outward from the second pressure chamber to force the rotor arm to move in a second direction opposite to the first direction.

[0099] In aspect ninety-three, according to aspect ninety-one or ninety-two, forcing the first piston partially outward from the first pressure chamber to force the rotor arm to move in the first direction further includes: moving the rotor arm in the first direction with a torque that is substantially constant in stroke.

[0100] In a ninety-fourth aspect, an arm of a machine device includes a first arm portion, a second arm portion, and a joint portion pivotally connected to the second arm portion. The joint portion includes a rotary actuator, the rotary actuator including a housing defining a first arched chamber housing. The first arched chamber housing defines a first arched chamber and a second arched chamber. The first arched chamber includes a first cavity, the first cavity defining a first annular segment in a plane between a first open end and a first closed end and having a first fluid port in fluid communication with the first cavity. The annular segment has a second fluid port in the plane. A second arched chamber includes an inner chamber wall defining a second cavity, the second cavity defining a second annular segment in the plane between a second open end and a second closed end, and having a second fluid port in fluid communication with the second cavity. The second annular segment has a second outer radius from the axis, the second outer radius being greater than the first outer radius and concentric with the first outer radius in the plane about the axis, and has a second inner radius in the plane smaller than the first inner radius. The first arched chamber has a second intermediate radius that is substantially the same as the first intermediate radius, wherein the second arched chamber is oriented in rotation opposite to the first arched chamber about an axis, and wherein at least a portion of the first arched chamber shell is enclosed in a plane within at least a portion of the second arched chamber and defines an arched tubular space between the first arched chamber shell and the inner chamber wall, the arched actuation space defines a third arc segment in a plane about an axis between the first open end and the second open end, the rotor arm is configured to rotate along the third arc segment within the actuation space, and the rotor assembly is coupled to the rotor arm. An arched first piston is disposed in the first housing for reciprocating motion in a plane and in a first arched chamber via a first open end, wherein a first seal, a first cavity, and a first piston define a first pressure chamber, and a first portion of the first piston contacts the rotor arm. A tubular arched second piston is disposed in the second housing for reciprocating motion in a plane and in an arched tubular space via a second open end in a second arched chamber, wherein a second seal, a third seal, a second cavity, and a second piston define a second pressure chamber, and a second portion of the second piston contacts the rotor arm.

[0101] In aspect ninety-five, according to aspect ninety-four, the rotor assembly is fixed to or integral with the first arm portion.

[0102] In aspect ninety-six, according to aspect ninety-four or ninety-five, the shell is fixed to or integral with the second arm portion.

[0103] In a ninety-seventh aspect, a rotary actuator includes a housing, a rotor arm, an arched first piston, and a rotor assembly. The housing defines a first arched chamber, the first arched chamber including a first cavity, the first cavity defining a first arcuate segment in a plane between a first open end and a first closed end, and having a first fluid port in fluid communication with the first cavity. The first arcuate segment has a first radius in the plane, the first radius defining an axis perpendicular to the plane. An arched actuation space defines an actuation arcuate segment about the axis between the first open end and the terminal end. The rotor arm is configured to rotate within the actuation space along a second arcuate segment. The arched first piston is disposed in the housing for reciprocating in a plane and within the first arched chamber via the first open end. A first seal, the first cavity, and the first piston define a first pressure chamber including part or all of the first arched chamber. A first portion of the first piston contacts the rotor arm. The rotor assembly is rotatably disposed around the housing and includes a rotary output tube about an axis. The rotor arm extends radially outward to the rotary output tube and is coupled to the rotary tube.

[0104] In aspect ninety-eight, according to aspect ninety-seven, the rotary actuator further includes a second arched chamber, the second arched chamber including a second cavity defining a second arc segment about an axis between a second open end and a second closed end, and having a second fluid port in fluid communication with the second cavity.

[0105] In aspect ninety-nine, according to aspect ninety-nine, the second arc segment has a second radius from the axis, the second radius being different from the first radius.

[0106] In aspect one hundred, according to aspect ninety-nine, the second arc segment is concentric with the first arc segment about the axis in the plane.

[0107] In the 101st aspect, according to aspect 99 or 100, the second open end is located at the terminal, and the arched chamber is oriented about the axis opposite to that of the first arched chamber in rotation.

[0108] In the 102nd aspect, according to any one of aspects 99 to 101, the second arc segment is not in a plane, and at least a portion of the second arched cavity is in a plane and axially overlaps with the first arched cavity.

[0109] In a first 103 aspect, according to any one of aspects 99 to 102, the rotary actuator further includes an arched second piston disposed in the second housing and configured to reciprocate in a second arched chamber via a second open end, wherein the second seal, the second cavity, and the second piston define a second pressure chamber comprising part or all of the second arched chamber, and a second portion of the second piston contacts the rotor arm.

[0110] In the first 104th aspect, according to aspect 103, applying pressurized fluid to the first pressure chamber will force the first piston to partially move outward from the first pressure chamber to force the rotor arm to rotate in a first direction, and applying pressurized fluid to the second pressure chamber will force the second piston to partially move outward from the second pressure chamber to force the rotor arm to rotate in a second direction.

[0111] In the 105th aspect, according to aspect 103 or 104, at least one of the first piston and the second piston includes a rotor arm.

[0112] In the 106th aspect, according to any one of aspects 97 to 105, rotation of the rotor assembly will force the first piston partially into the first pressure chamber to pressurize the fluid and force the fluid out of the first fluid port.

[0113] In aspect 107, according to any one of aspects 97 to 106, the rotating tube includes a rotor arm.

[0114] In the 108th aspect, according to any one of aspects 97 to 107, the rotary actuator further includes a first housing sealing ring groove, a second housing sealing ring groove, and an annular seal, the first housing sealing ring groove being defined in the rotor assembly about an axis, the second housing sealing ring groove being defined in the housing about an axis and complementary to the first housing sealing ring groove, and the annular seal being located between the rotor assembly and the housing in the first housing sealing ring groove and the second housing sealing ring groove.

[0115] In a 109th aspect, a rotary actuation method includes: providing a rotary actuator including a housing, a rotor arm, an arched first piston, and a rotor assembly, the housing defining a first arched chamber including a first cavity, the first cavity defining a first arcuate segment in a plane between a first open end and a first closed end, and having a first fluid port in fluid communication with the first cavity, the first arcuate segment having a first radius in the plane, the first radius defining an axis perpendicular to the plane, an arched actuation space defining an actuation arcuate segment about the axis between the first open end and the closed end, the rotor arm configured to rotate within the actuation space along a second arcuate segment, and the arched first piston disposed in the housing for rotational movement via the first open end in a plane. The device reciprocates within a first arched chamber, wherein a first seal, a first cavity, and a first piston define a first pressure chamber comprising part or all of the first arched chamber, a first portion of the first piston contacts a rotor arm, a rotor assembly rotatably surrounds the housing and includes a rotating output tube about an axis, wherein the rotor arm extends radially outward to the rotating output tube and is coupled to the rotating tube; pressurized fluid is applied to the first pressure chamber; the first piston is forced partially outward from the first pressure chamber to force the rotor assembly to rotate in a first direction; the rotor assembly is rotated in a second direction opposite to the first direction; and the first piston is forced partially into the first pressure chamber to force the pressurized fluid out of a first fluid port.

[0116] In the 110th aspect, according to aspect 109, the housing further defines a second arched chamber, the second arched chamber including a second cavity body defining a second arcuate segment about an axis between a second open end and a second closed end and having a second fluid port in fluid communication with the second cavity body, the rotary actuator further including an arched second piston disposed in the first housing for reciprocating motion in the second arched chamber, wherein the second seal, the second cavity body and the second piston define a second pressure chamber, and a first portion of the second piston contacts the second rotor arm.

[0117] In aspect 111, according to aspect 110, the second piston is oriented in the same direction of rotation as the first piston.

[0118] In aspect 112, according to aspect 110, the second piston is oriented in the opposite direction of rotation to the first piston.

[0119] In the 113th aspect, according to any one of aspects 110 to 112, rotating the rotor assembly in a second direction opposite to the first direction includes: applying pressurized fluid to a second pressure chamber and forcing a second piston partially outward from the second pressure chamber to force the rotor assembly to rotate in a second direction opposite to the first direction.

[0120] In the 114th aspect, according to any one of aspects 110 to 113, rotating the rotor assembly in a second direction opposite to the first direction includes: applying a pressurized fluid to a second pressure chamber and forcing a first piston partially into the first pressure chamber to force the rotor assembly to rotate in the second direction opposite to the first direction.

[0121] In the 115th aspect, according to any one of aspects 109 to 114, forcing the first piston partially outward from the first pressure chamber to force the rotor assembly to rotate in the first direction further includes: rotating the rotor assembly in the first direction with a torque that is substantially constant in stroke.

[0122] In a 116th aspect, an arm of a machine device includes a first arm portion, a second arm portion, and a joint portion pivotally connected to the second arm portion. The joint portion includes a rotary actuator, which includes a housing, a rotor arm, an arched first piston, and a rotor assembly. The housing defines a first arched chamber, which includes a first cavity. The first cavity defines a first arcuate segment in a plane between a first open end and a first closed end and has a first fluid port in fluid communication with the first cavity. The first arcuate segment has a first radius in the plane, which defines an axis perpendicular to the plane. An arched actuation space defines an actuation mechanism. An actuating arc segment, the actuating arc segment surrounding an axis between a first open end and a terminal end, a rotor arm configured to rotate along a second arc segment within an actuation space, an arched first piston disposed in the housing for reciprocating motion in a plane and within a first arched chamber via the first open end, wherein a first seal, a first cavity, and a first piston define a first pressure chamber comprising part or all of the first arched chamber, a first portion of the first piston contacts the rotor arm, a rotor assembly rotatably surrounding the housing and including a rotating output tube surrounding an axis, wherein the rotor arm extends radially outward to the rotating output tube and is coupled to the rotating tube.

[0123] In aspect 117, according to aspect 116, the rotor assembly is fixed to or integral with the first arm portion.

[0124] In aspect 118, and according to aspect 116 or 117, the shell is fixed to or integral with the second arm portion.

[0125] A rotary piston actuator assembly includes a first rotary actuator, the first rotary actuator including a first housing, an arched first piston disposed in the first housing, and a first arched bearing sleeve assembly, the first housing defining a first arched chamber including a first cavity having a first open end, the arched first piston being configured to reciprocate within the first arched chamber through the first open end, and the first arched bearing sleeve assembly having an inner surface configured to contact the radially outer side of the first piston.

[0126] Various embodiments may include some, all, or none of the following features. The first arched bearing sleeve may include an arched support portion and an arched liner portion, the arched liner portion being configured to conform to the inner surface of the arched support portion. The first arched bearing sleeve assembly is removably attached to the first housing. The first rotary actuator may further include a rotor assembly rotatably disposed around the first housing and defining a first central bore within an inner wall of the rotor assembly, wherein the first arched bearing sleeve assembly is radially disposed between the first piston and the inner wall and contacts the inner wall and the radially outer side of the first piston. The first arched bearing sleeve assembly may be radially disposed between the first piston and the inner wall and contact the inner wall and the radially outer side of the first piston. The rotary actuator may further include a fluid delivery shaft having an elongated body, the fluid delivery shaft being disposed in a second central bore defined by the first housing and in fluid communication with a first cavity. The rotor assembly may further include a rotary output tube about an axis and a rotor arm contacting a first portion of the first piston, the rotor arm extending radially outward to and coupled to the rotary output tube. The rotary actuator may further include a second rotary actuator disposed within a first central borehole. The second rotary actuator may further include a second housing and an arched second piston disposed within the second housing, the second housing defining a second arched chamber including a second cavity having a second open end, the arched second piston being configured to reciprocate within the second arched chamber through the second open end. The rotary actuator may further include a second arched bearing sleeve assembly radially disposed between the second piston and an inner wall, and contacting the inner wall and the radially outer side of the second piston. The first arched bearing sleeve may include a group of bearings. The first arched bearing sleeve may include a friction-reducing coating.

[0127] An exemplary rotary actuation method includes: providing a first rotary actuator, the first rotary actuator including a first housing, an arched first piston disposed in the first housing, and a first arched bearing sleeve assembly, the first housing defining a first arched chamber, the first arched chamber including a first cavity having a first open end, the arched first piston being configured to reciprocate within the first arched chamber via the first open end, wherein a first seal, the first cavity, and the first piston define a first pressure chamber, the first pressure chamber including a portion or all of the first arched chamber, the first arched bearing sleeve assembly having an inner surface configured to contact the radially outer side of the first piston; forcing the first piston to rotate outward from a portion of the first pressure chamber; and applying a first radial force to the radially outer side of the piston via the first arched bearing sleeve portion.

[0128] Various implementations may include some, all, or none of the following features. The method may also include: forcing a first piston portion radially outward; contacting the first piston with a first arched bearing sleeve assembly using a second radial force; transmitting the second radial force to a first housing; and constraining the second radial force through the first arched bearing sleeve assembly. The method may also include: providing a second rotary actuator, wherein a rotor assembly is rotatably positioned around a first rotary actuator and a second rotary actuator. The method may also include: redirecting the first radial force through the first arched bearing sleeve assembly to a rotor assembly rotatably positioned around the first housing and defining a central bore within the inner wall of the rotor assembly, wherein the first arched bearing sleeve assembly is removably attached to the first housing. The method may also include: redirecting the first radial force through the first arched bearing sleeve assembly to the first housing, wherein the first arched bearing sleeve assembly is removably attached to the first housing. Applying the first radial force radially outward of the piston through the first arched bearing sleeve portion may include: applying the first radial force to a group of bearings in radial contact with the piston. The first arched bearing sleeve portion may include a friction-reducing coating, and the application of a first radial force to the radially outer side of the piston through the first arched bearing sleeve portion may further include: applying the first radial force to the friction-reducing coating that is in contact with the radially outer side of the piston.

[0129] An exemplary fluid actuator includes a housing defining a first chamber, a first piston assembly, and a second piston assembly. The first chamber includes a first cavity, a first fluid port in fluid communication with the first cavity, and a first open end. The first piston assembly includes a tubular first piston defining a second chamber. The second chamber includes a second cavity, a second fluid port in fluid communication with the second cavity, and a second open end. The tubular first piston is disposed within the first housing and is used for reciprocating motion within the first chamber via the first open end. A first seal, the first cavity, and the first piston define a first pressure chamber. The second piston assembly includes a second piston disposed within the first piston assembly and is used for reciprocating motion within the second chamber via the second open end. A second seal, the second cavity, and the second piston define a second pressure chamber, and a first portion of the second piston contacts a first end actuator.

[0130] Various embodiments may include some, all, or none of the following features. The first chamber may be an arched first chamber including a first open end and a first closed end; the tubular first piston may be an arched tubular first piston; the second chamber may be an arched second chamber including a second open end and a second closed end; the second piston may be an arched second piston; and the end actuator may be a rotor arm. The housing may further define a third arched chamber, the third arched chamber including a third cavity, a third fluid port in fluid communication with the third cavity, and a third open end. The first piston assembly also includes an arched tubular third piston defining a fourth arched chamber, the fourth arched chamber including a fourth cavity, a fourth fluid port in fluid communication with the fourth cavity, and a fourth open end. The arched tubular third piston is disposed in the first housing for reciprocating within the third arched chamber via the third open end. The third seal, the third cavity, and the third piston define a third pressure chamber. The second piston assembly also includes an arched fourth piston disposed in the first piston assembly for reciprocating within the fourth arched chamber via the fourth open end. The fourth seal, the fourth cavity, and the fourth piston define a fourth pressure chamber, and a first portion of the fourth piston contacts the second end actuator. The fluid actuator may further include a rotor arm, wherein the first chamber may be an arched first chamber, the tubular first piston may be an arched tubular first piston, the second chamber may be an arched second chamber, the second piston may be an arched second piston, the third chamber may be an arched third chamber, the tubular third piston may be an arched tubular third piston, the fourth chamber may be an arched fourth chamber, and the fourth piston may be an arched fourth piston. The first end actuator may be a rotor arm, and the second end actuator may be a rotor arm. The second piston may be oriented in the same rotational direction as the first piston. The second piston may also be oriented in the opposite rotational direction to the first piston. Applying pressurized fluid to the third pressure chamber forces the third piston partially outward from the third pressure chamber, thereby forcing the first piston assembly to rotate in a first direction. Applying pressurized fluid to the fourth pressure chamber forces the fourth piston partially outward from the fourth pressure chamber, thereby forcing the second piston assembly to rotate in a first direction. Rotation of the second piston assembly in a second direction opposite to the first direction forces the fourth piston partially into the fourth pressure chamber, thereby forcing the pressurized fluid out of the fourth fluid port. Rotation of the first piston assembly in the second direction forces the third piston partially into the third pressure chamber, thereby forcing the pressurized fluid out of the third fluid port. The housing may also define an arched actuation space defining an actuation arc about an axis between the first open end and the terminal end. The fluid actuator may also include a rotor assembly including a rotating output tube rotatably surrounding the housing, wherein rotor arms extend radially outward to the rotating output tube and are coupled to the rotating tube. A first seal may be disposed around the inner surface of the first open end.A first seal may be disposed around the perimeter of the first piston and configured to remain stationary relative to the first piston. A second seal may be disposed around the inner surface of the second open end. A second seal may be disposed around the perimeter of the second piston and configured to remain stationary relative to the second piston. The housing may be formed as a one-piece housing. The first piston may have a square, rectangular, oval, elliptical, figure-eight shaped, or circular cross-section. The first piston assembly may also define a fluid port for fluid connection between the first and second chambers. A first portion of the tubular first piston may contact the second end actuator.

[0131] An exemplary fluid actuation method includes: providing a fluid actuator including a housing, a first piston assembly, and a second piston assembly. The housing defines a first chamber, the first chamber including a first cavity, a first fluid port in fluid communication with the first cavity, and a first open end. The first piston assembly includes a tubular first piston defining a second chamber, the second chamber including a second cavity, a second fluid port in fluid communication with the second cavity, and a second open end. The tubular first piston is disposed in the first housing for reciprocating motion within the first chamber via the first open end. The first seal, the first cavity, and the first piston define a first pressure chamber. The second piston assembly includes a second piston disposed in the first piston assembly for reciprocating motion via the second open end. An end reciprocates in a second chamber, wherein a second seal, a second cavity, and a second piston define a second pressure chamber, a first portion of the second piston contacts a first end actuator; pressurized fluid is applied to the first pressure chamber; the first piston is forced partially outward from the first pressure chamber to force the end actuator along a first direction; the end actuator is forced along a second direction opposite to the first direction; the first piston is forced partially into the first pressure chamber to force the pressurized fluid out of a first fluid port; pressurized fluid is applied to the second pressure chamber; the second piston is forced partially outward from the second pressure chamber to force the first piston assembly along a first direction; the first piston assembly along a second direction; and the second piston is forced partially into the second pressure chamber to force the pressurized fluid out of a second fluid port. The first chamber may be an arched first chamber, including a first open end and a first closed end; the tubular first piston may be an arched tubular first piston; the second chamber may be an arched second chamber, including a second open end and a second closed end; the second piston may be an arched second piston; the end actuator may be a rotor arm; forcing the first piston partially outward from the first pressure chamber to force the end actuator along the first direction may further include: rotating the rotor arm along the first direction with a substantially constant torque over the stroke; and forcing the second piston partially outward from the second pressure chamber to force the first piston assembly along the first direction may further include: rotating the first piston assembly along the first direction with a substantially constant torque over the stroke.

[0132] An arm of an exemplary machine device includes a first arm portion, a second arm portion, and a connector portion connecting the first arm portion to the second arm portion. The connector portion includes a fluid actuator comprising: a housing, a first piston assembly, and a second piston assembly. The housing defines a first chamber, the first chamber including a first cavity, a first fluid port in fluid communication with the first cavity, and a first open end. The first piston assembly includes a tubular first piston defining a second chamber, the second chamber including a second cavity, a second fluid port in fluid communication with the second cavity, and a second open end. The tubular first piston is disposed in the first housing for reciprocating within the first chamber via the first open end. A first seal, the first cavity, and the first piston define a first pressure chamber. The second piston assembly includes a second piston disposed in the first piston assembly for reciprocating within the second chamber via the second open end. A second seal, the second cavity, and the second piston define a second pressure chamber. A first portion of the second piston contacts a first end actuator.

[0133] Various embodiments may include some, all, or none of the following features. The end effector may be attached to or integral with the first arm portion. The housing may be attached to or integral with the second arm portion.

[0134] An exemplary multi-axis rotary actuator includes a first rotary piston actuator and a second rotary piston actuator, the first rotary piston actuator being configured to controllably actuate a first pivot joint between a first link and a second link about a first axis, and the second rotary piston actuator being configured to controllably actuate a second pivot joint connecting a second link to a third link about a second axis.

[0135] Various embodiments may include some, all, or none of the following features: The first axis may be parallel to the second axis. The first axis may be perpendicular to the second axis. The first axis may intersect the second axis. At least one of the first and second rotary piston actuators may include a housing, a rotor arm, an arched first piston, and a rotor assembly. The housing defines a first arched chamber and an arched actuation space. The first arched chamber includes a first cavity that defines a first arc segment in a plane between a first open end and a first closed end, and has a first fluid port in fluid communication with the first cavity. The first arc segment has a first radius in the plane that defines an axis perpendicular to the plane. The arched actuation space defines an actuation arc segment about an axis between the first open end and the terminal end. The rotor arm is configured to rotate within the actuation space along a second arc segment. A first piston is disposed within the housing for reciprocating in a plane and within a first arched chamber via a first open end. A first seal, a first cavity, and the first piston define a first pressure chamber comprising part or all of the first arched chamber. A first portion of the first piston contacts a rotor arm. A rotor assembly is rotatably disposed around the housing and includes a rotating cylinder about an axis. The rotor arm extends radially outward to the rotating cylinder and is coupled to the rotating cylinder. The housing is coupled to one of a first, second, or third link, and the rotor assembly is coupled to the other of the first, second, or third link. The multi-axis rotary actuator may also include a second arched chamber comprising a second cavity defining a second arcuate segment about an axis between a second open end and a second closed end, and having a second fluid port in fluid communication with the second cavity. The second arcuate segment may have a second radius from the axis, different from the first radius. The second arcuate segment may be concentric with the first arcuate segment about the axis in a plane. The second open end may be located at the terminal, and the arched chamber may be oriented about an axis opposite in rotation to the first arched chamber. The second arc segment may not be in a plane, and at least a portion of the second arched chamber may be axially overlapped with the first arched chamber in a plane. The multi-axis rotary actuator may also include an arched second piston disposed in the second housing for reciprocating motion in the second arched chamber via the second open end, wherein the second seal, the second cavity, and the second piston define a second pressure chamber comprising part or all of the second arched chamber, and a second portion of the second piston contacts the rotor arm. The rotor assembly may provide load support for the housing.At least one of the first and second rotary piston actuators may include a housing defining a first arched chamber, a second arched chamber, and an arched actuation space. The first arched chamber includes a first cavity that defines a first annular segment in a plane between a first open end and a first closed end, and has a first fluid port in fluid communication with the first cavity. The annular segment has a first outer radius in the plane, which defines an axis perpendicular to the plane, and has a first inner radius and a first middle radius in the plane. The second arched chamber includes an inner chamber wall. A second cavity is defined, the second cavity defining a second annular segment in a plane between a second open end and a second closed end, and having a second fluid port in fluid communication with the second cavity. The second annular segment has a second outer radius from the axis, the second outer radius being larger than a first outer radius and concentric with the first outer radius in the plane about the axis, and has a second inner radius in the plane smaller than the first inner radius, and the second inner radius being substantially the same as the first inner radius. The second arched cavity is oriented to be rotationally opposite to the first arched cavity about the axis, and at least a portion of the shell of the first arched cavity is... The first arched chamber is enclosed within a portion of the second arched chamber in a plane, thereby defining an arched tubular space between the first arched chamber housing and the inner chamber wall. The arched actuation space defines a third arc segment in the plane about an axis between the first and second open ends, a rotor arm, a rotor assembly, an arched first piston, and a tubular arched second piston. The rotor arm is configured to rotate along the third arc segment within the actuation space. The rotor assembly is connected to the rotor arm. The arched first piston is disposed in the first housing for reciprocating motion in the plane and within the first arched chamber via the first open end. The first seal... A first cavity and a first piston define a first pressure chamber, a first portion of the first piston contacts the rotor arm, and a tubular arched second piston is disposed in the second housing for reciprocating in the second arched chamber in a plane and in an arched tubular space via a second open end, wherein a second seal, a third seal, the second cavity, and the second piston define a second pressure chamber, and a second portion of the second piston contacts the rotor arm, wherein the housing is coupled to one of a first link, a second link, or a third link, and the rotor assembly is coupled to the other of the first link, the second link, or the third link.

[0136] An exemplary multi-axis rotary actuation method includes: providing a multi-axis rotary actuator including a first rotary piston actuator and a second rotary piston actuator, the first rotary piston actuator being configured to controllably actuate a first pivot joint between a first link and a second link about a first axis, the second rotary piston actuator being configured to controllably actuate a second pivot joint about a second axis, the second pivot joint connecting a second link to a third link; applying pressurized fluid to the first rotary piston actuator; forcing the first pivot joint to actuate about the first axis in a first direction; forcing the first pivot joint to actuate about the first axis in a second direction opposite to the first direction; applying pressurized fluid to the second rotary piston actuator; forcing the second pivot joint to actuate about the second axis in a third direction; and forcing the second pivot joint to actuate about the second axis in a fourth direction opposite to the third direction.

[0137] Various implementations may include some, all, or none of the following features. Applying pressurized fluid to the first rotary piston actuator may further include: applying pressurized fluid to a first pressure chamber of the first rotary piston actuator, the first pressure chamber being configured to force a first pivot joint actuated in a first direction, and wherein applying pressurized fluid to the second rotary piston actuator may further include: applying pressurized fluid to a third pressure chamber of the second rotary piston actuator, the third pressure chamber being configured to force a second pivot joint actuated in a third direction, and the method may further include: applying pressurized fluid to a second pressure chamber of the first rotary piston actuator, the second pressure chamber being configured to force a first pivot joint actuated in a second direction; forcing the first pivot joint actuated in the second direction about a first axis; applying pressurized fluid to a fourth pressure chamber of the second rotary piston actuator, the fourth pressure chamber being configured to force the first pivot joint actuated in the second direction; and forcing the second pivot joint actuated in the fourth direction about a second axis.

[0138] An exemplary machine arm includes 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 includes a multi-axis rotary actuator, which includes a first rotary piston actuator and a second rotary piston actuator. The first rotary piston actuator is configured to controllably actuate a first pivot joint between a first link and a second link about a first axis. The second rotary piston actuator is configured to controllably actuate a second pivot joint about a second axis, the second pivot joint connecting the second link to a third link.

[0139] Various embodiments may include some, all, or none of the following features: The first axis may be parallel to the second axis. The first axis may be perpendicular to the second axis. The first axis may intersect the second axis. At least one of the first and second rotary piston actuators may include a housing, a rotor arm, an arched first piston, and a rotor assembly. The housing defines a first arched chamber and an arched actuation space. The first arched chamber includes a first cavity that defines a first arc segment in a plane between a first open end and a first closed end, and has a first fluid port in fluid communication with the first cavity. The first arc segment has a first radius in the plane that defines an axis perpendicular to the plane. The arched actuation space defines an actuation arc segment about an axis between the first open end and the terminal end. The rotor arm is configured to rotate within the actuation space along a second arc segment. A first piston is disposed in the housing for reciprocating in a plane and in a first arched chamber via a first open end, wherein a first seal, a first cavity, and a first piston define a first pressure chamber comprising part or all of the first arched chamber, a first portion of the first piston contacts a rotor arm, a rotor assembly is rotatably disposed around the housing and includes a rotating cylinder about an axis, wherein the rotor arm extends radially outward to the rotating cylinder and is coupled to the rotating cylinder, wherein the housing is coupled to one of a first link, a second link, or a third link, and the rotor assembly is coupled to the other of the first link, the second link, or the third link.

[0140] An exemplary rotary piston actuator assembly includes a first rotary actuator comprising a first housing, a rotor arm, an arched first piston, a rotor assembly, and a fluid delivery shaft. The first housing defines a first central bore and a first arched chamber. The first arched chamber includes a first cavity having a first actuator fluid port in fluid communication with the first cavity and the first central bore. The arched first piston is disposed in the first housing for reciprocating motion within the first housing. A first seal, the first cavity, and the first piston define a first pressure chamber, which includes a portion or all of the first arched chamber. A first portion of the first piston contacts the rotor arm. The rotor assembly is rotatably disposed around the first housing and includes a rotary output tube. The rotor arm extends radially outward to the rotary output tube and is coupled to the rotary tube. The fluid delivery shaft has an elongated body disposed in the first central bore and defines a first-axis fluid delivery path.

[0141] Various embodiments may include some, all, or none of the following features. The rotary piston actuator assembly may also include a second rotary actuator comprising a second housing and an arched second piston. The second housing defines a second central bore and a second arched chamber. The second arched chamber includes a second cavity having a second actuator fluid port in fluid communication with the second cavity and the second central bore. The arched second piston is disposed in the second housing for reciprocating motion within the second housing. A second seal, the second cavity, and the second piston define a second pressure chamber comprising part or all of the second arched chamber. A first portion of the second piston contacts a rotor arm. The rotor assembly is rotatably disposed around the second housing, and a fluid delivery shaft is disposed in the second central bore. The fluid delivery shaft may define an axis and may include a first axial fluid port along the body, a second axial fluid port near a terminal of the body, and a first axial fluid delivery path defined by the fluid delivery shaft and fluidly connecting the first axial fluid port to the second axial fluid port. A first axial seal is disposed around the fluid delivery shaft along the axis on a first axial side of the first axial fluid port, and a second axial seal is disposed around the fluid delivery shaft along the axis on a second axial side of the first axial fluid port and opposite to the first axial seal. A first central bore, the body, the first axial fluid seal, and the second axial fluid seal define a first fluid transfer chamber, and a first actuator fluid port is in fluid communication with the first fluid transfer chamber. The first central borehole may further define a first borehole portion and a second borehole portion, wherein the first borehole portion extends substantially along a first half of the axial length of the first central borehole, the second borehole portion extends substantially along a second half of the axial length of the first central borehole, and a first actuator fluid port is defined within the first borehole portion, wherein a first fluid transfer chamber may extend approximately half of the axial length of the first central borehole, such that the first fluid transfer chamber extends along the first borehole portion in a first assembly of the first rotary actuator and fluid delivery shaft, and the first fluid transfer chamber may extend along the second borehole portion in a second assembly of the first rotary actuator and fluid delivery shaft. The first arched chamber may further define a first open end, and the first piston may further include a first piston assembly, the first piston assembly including a tubular first piston defining a second chamber, the second chamber including a second cavity, a second fluid port in fluid communication with the second cavity, and a second open end, the tubular first piston being disposed within the first housing for reciprocating motion in the first chamber via the first open end, wherein the first seal, the first cavity, and the first piston define a first pressure chamber, and the rotary piston actuator may further include a second piston assembly, the second piston assembly including a second piston disposed within the first piston assembly for reciprocating motion in the second chamber via the second open end, wherein the second seal, the second cavity, and the second piston define a second pressure chamber, and a first portion of the second piston contacts the first end actuator.A first cavity may define a first arc segment in a plane between a first open end and a first closed end and have a first fluid port in fluid communication with the first cavity. The first arc segment has a first radius in the plane, which defines an axis perpendicular to the plane. The first housing also defines an arched actuation space that defines an actuation arc segment about an axis between the first open end and the closed end. A rotor arm is configured to rotate along a second arc segment within the actuation space. A first piston is disposed in the first housing for reciprocating in the plane through the first open end and within the first arched cavity. The first seal, the first cavity, and the first piston define a first pressure chamber that includes part or all of the first arched cavity. The first housing may include a first arched chamber housing defining a first arched chamber, wherein the first chamber defines a first annular segment in a plane between a first open end and a first closed end, the annular 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 intermediate radius in the plane, wherein the first housing further defines a second arched chamber including an inner chamber wall defining a second chamber, the second chamber defining a second annular segment in a plane between a second open end and a second closed end, and having a second fluid port in fluid communication with the second chamber, the second annular segment having a second outer radius from the axis, the second outer radius being greater than the first outer radius and concentric with the first outer radius in the plane about the axis, a second inner radius in the plane smaller than the first inner radius, and a second intermediate radius substantially the same as the first intermediate radius, wherein the second arched chamber is rotationally related to the first arched chamber about the axis. The rotor arm is configured to rotate within the actuation space along the third arcuate segment, wherein at least a portion of the first arched chamber housing is enclosed in a plane within at least a portion of the second arched chamber and defines an arched tubular space between the first arched chamber housing and the inner chamber wall, the arched actuation space defines a third arcuate segment in a plane about an axis between a first open end and a second open end, wherein the first piston is disposed in the first housing for reciprocating in a plane and in the first arched chamber via the first open end, wherein the first seal, the first cavity, and the first piston define a first pressure chamber, and wherein the rotary piston actuator assembly further includes a tubular arched second piston disposed in the second housing for reciprocating in a plane and in the second arched chamber via the second open end in the second arched tubular space, wherein the second seal, the third seal, the second cavity, and the second piston define a second pressure chamber, and a second portion of the second piston contacts the rotor arm.

[0142] An exemplary rotary actuation method includes: providing a first rotary piston actuator, the first rotary actuator including a first housing, a rotor arm, an arched first piston, a rotor assembly, and a fluid delivery shaft, the first housing defining a first central borehole and a first arched chamber, the first arched chamber including a first cavity having a first actuator fluid port in fluid communication with the first cavity and the first central borehole, the arched first piston disposed in the first housing for reciprocating motion within the first housing, wherein a first seal, the first cavity, and the first piston define a first pressure chamber, the first pressure chamber including a portion or all of the first arched chamber, a first portion of the first piston contacting the rotor arm, and the rotor assembly rotatably surrounding the first housing and including a rotary output tube, wherein the rotor... The arm extends radially outward to the rotary output tube, and the rotor arm is coupled to the rotary tube. The fluid delivery shaft has an elongated body disposed in the first central bore and defines a first axial fluid delivery path; provides pressurized fluid to a second axial fluid port; forces the pressurized fluid through the first axial fluid delivery path, the first axial fluid port, the first fluid transfer chamber, and the first fluid port to a first pressure chamber; forces the first piston partially outward from the first pressure chamber to force the rotor assembly to rotate in a first direction; rotates the rotor assembly in a second direction opposite to the first direction; and forces the first piston partially into the first pressure chamber to force the pressurized fluid out of the second axial fluid port through the first fluid port, the first fluid transfer chamber, the first axial fluid port, and the first axial fluid delivery path.

[0143] Various implementations may include some, all, or none of the following features. The method may also include: removing a first rotary actuator from a first assembly configuration with a fluid delivery shaft; reassembling the first rotary actuator to the fluid delivery shaft in a second configuration; supplying pressurized fluid to a second shaft fluid port; forcing the pressurized fluid through a first shaft fluid delivery path, the first shaft fluid port, a first fluid transfer chamber, and a first fluid port to a first pressure chamber; forcing a first piston partially outward from the first pressure chamber to force a rotor assembly to rotate in a second direction; rotating the rotor assembly in a direction opposite to the second direction; and forcing the first piston partially into the first pressure chamber to force the pressurized fluid out of the second shaft fluid port through the first fluid port, the first fluid transfer chamber, the first shaft fluid port, and the first shaft fluid delivery path. The first central bore may define a first bore portion and a second bore portion, wherein the first bore portion extends substantially along a first half of the axial length of the first central bore, the second bore portion extends substantially along a second half of the axial length of the first central bore, and a first actuator fluid port is defined within the first bore portion; and wherein a first fluid transfer chamber extends approximately half of the axial length of the first central bore, such that the first fluid transfer chamber extends along the first bore portion in a first assembly of the first rotary actuator and fluid delivery shaft, and the first fluid transfer chamber extends along the second bore portion in a second assembly of the first rotary actuator and fluid delivery shaft. The method may further include: removing a first rotary actuator from a first assembly configuration with a fluid delivery shaft, wherein a first central bore portion, a body, a first shaft fluid seal, and a second shaft fluid seal define a first fluid transfer chamber in the first configuration; reassembling the first rotary actuator to the fluid delivery shaft in a second configuration, wherein a second central bore portion, a body, a first shaft fluid seal, and a second shaft fluid seal define the first fluid transfer chamber in the second configuration; providing pressurized fluid to a second shaft fluid port; and blocking the flow of pressurized fluid through a first pressure chamber.

[0144] Another exemplary machine arm includes a first arm portion, a second arm portion, and a joint portion pivotally connected to the second arm portion. The joint portion includes a first rotary actuator, which includes a first housing, a rotor arm, an arched first piston, a rotor assembly, and a fluid delivery shaft. The first housing defines a first central bore and a first arched chamber. The first arched chamber includes a first cavity having a first actuator fluid port in fluid communication with the first cavity and the first central bore. The arched first piston is disposed in the first housing for reciprocating motion within the first housing. A first seal, the first cavity, and the first piston define a first pressure chamber, which includes part or all of the first arched chamber. A first portion of the first piston contacts the rotor arm. The rotor assembly is rotatably disposed around the first housing and includes a rotary output tube. The rotor arm extends radially outward to the rotary output tube and is coupled to the rotary tube. The fluid delivery shaft has an elongated body disposed in the first central bore and defines a first-axis fluid delivery path.

[0145] Various embodiments may include some, all, or none of the following features. The rotor assembly may be fixed to or integral with the first arm portion. The housing may be fixed to or integral with the second arm portion. The arm may also include a second rotary actuator comprising a second housing and an arched second piston. The second housing defines a second central bore and a second arched chamber. The second arched chamber includes a second cavity having a second actuator fluid port in fluid communication with the second cavity and the second central bore. The arched second piston is disposed in the second housing for reciprocating motion within the second housing. A second seal, the second cavity, and the second piston define a second pressure chamber comprising part or all of the second arched chamber. A first portion of the second piston contacts the rotor arm. The rotor assembly is rotatably disposed around the second housing, and a fluid delivery shaft is disposed in the second central bore. The fluid delivery shaft may define an axis and may include a first axial fluid port along the body, a second axial fluid port near a terminal of the body, and a first axial fluid delivery path defined by the fluid delivery shaft and fluidly connecting the first axial fluid port to the second axial fluid port. A first axial seal is disposed around the fluid delivery shaft along the axis on a first axial side of the first axial fluid port, and a second axial seal is disposed around the fluid delivery shaft along the axis on a second axial side of the first axial fluid port and opposite to the first axial seal. A first central bore, the body, the first axial fluid seal, and the second axial fluid seal define a first fluid transfer chamber, and a first actuator fluid port is in fluid communication with the first fluid transfer chamber. The first central borehole may further define a first borehole portion and a second borehole portion, wherein the first borehole portion extends substantially along a first half of the axial length of the first central borehole, the second borehole portion extends substantially along a second half of the axial length of the first central borehole, and a first actuator fluid port is defined within the first borehole portion, wherein a first fluid transfer chamber extends approximately half of the axial length of the first central borehole, such that the first fluid transfer chamber extends along the first borehole portion in a first assembly of the first rotary actuator and fluid delivery shaft, and the first fluid transfer chamber extends along the second borehole portion in a second assembly of the first rotary actuator and fluid delivery shaft.

[0146] Another exemplary rotary actuator includes a housing defining a first arched chamber housing, the first arched chamber housing defining a first arched chamber and a second arched chamber. The first arched chamber includes a first cavity, the first cavity defining a first annular segment in a plane between a first open end and a first closed end and having a first fluid port in fluid communication with the first cavity. The annular segment has a first outer radius in the plane and defines an axis perpendicular to the plane, a first inner radius in the plane about the axis, and a first intermediate radius in the plane. The second arched chamber includes an inner chamber wall defining a second cavity, the second cavity defining a second annular segment in a plane between a second open end and a second closed end and having a second fluid port in fluid communication with the second cavity. The second annular segment has a second outer radius from the axis, the second outer radius being greater than the first outer radius and concentric with the first outer radius in the plane about the axis, a second inner radius in the plane smaller than the first inner radius, and a second intermediate radius substantially the same as the first intermediate radius. The second arched cavity... The chamber is oriented in rotation opposite to the first arched chamber about an axis, and wherein at least a portion of the first arched chamber housing is enclosed in a plane within at least a portion of the second arched chamber and defines an arched tubular space between the first arched chamber housing and the inner chamber wall, the arched actuation space defines a third arc segment in a plane about an axis between a first open end and a second open end, the rotor arm is configured to rotate along the third arc segment in the actuation space, the rotor assembly is coupled to the rotor arm, the arched first piston is disposed in the first housing for reciprocating in a plane and in the first arched chamber through the first open end, wherein the first seal, the first cavity and the first piston define a first pressure chamber, the first portion of the first piston contacts the rotor arm, the tubular arched second piston is disposed in the second housing for reciprocating in a plane and in the arched tubular space in the second arched chamber through the second open end, wherein the second seal, the third seal, the second cavity and the second piston define a second pressure chamber, the second portion of the second piston contacts the rotor arm.

[0147] Various embodiments may include some, all, or none of the following features. At least a portion of the second arched chamber may axially overlap with the first arched chamber in a plane. The rotor assembly is rotatably supported in the housing by journals and may include a rotating output shaft along an axis, wherein rotor arms extend radially inward to and are coupled to the rotating output shaft. The rotor assembly is rotatably surrounding the housing and may include a rotating output cylinder around an axis, wherein rotor arms extend radially outward to and are coupled to the rotating output cylinder. A first seal may be disposed around the inner surface of an open end and may be configured to remain stationary relative to the open end. A first seal may be disposed around the perimeter of a first piston and may be configured to remain stationary relative to a first portion. The first seal may provide load support for the first piston. The rotor assembly may provide load support for the housing. The housing may be formed as a one-piece housing. The diameter of the first seal recess may be that of a one-piece seal. The cross-section of the first piston may be solid. At least one of the first and second pistons may have a cross-section that is at least partially hollow. The first piston may have one of the following cross-sections: square, rectangular, oval, elliptical, figure-eight shaped, or circular.

[0148] Another exemplary rotary actuation method includes: providing a rotary actuator including a housing defining a first arched chamber housing, the first arched chamber housing defining a first arched chamber and a second arched chamber, the first arched chamber including a first cavity, the first cavity defining a first annular segment in a plane between a first open end and a first closed end and having a first fluid port in fluid communication with the first cavity, the annular segment having a first outer radius in the plane and defining an axis perpendicular to the plane, having a first inner radius in the plane about the axis, and having a first middle radius in the plane, the second arched chamber including an inner chamber wall. The inner chamber wall defines a second cavity, the second cavity defining a second annular segment in a plane between a second open end and a second closed end, and having a second fluid port in fluid communication with the second cavity. The second annular segment has a second outer radius from the axis, the second outer radius being larger than a first outer radius and concentric with the first outer radius in the plane about the axis, and has a second inner radius in the plane smaller than the first inner radius, and has a second intermediate radius substantially the same as the first intermediate radius. The second arched cavity is oriented in rotation about the axis opposite to that of the first arched cavity, and at least a portion of the shell of the first arched cavity is in the plane... The rotor is enclosed within at least a portion of a second arched chamber and defines an arched tubular space between the housing of the first arched chamber and the inner chamber wall. An arched actuation space defines a third arc segment in a plane about an axis between a first open end and a second open end. A rotor arm is configured to rotate along the third arc segment within the actuation space. A rotor assembly is coupled to the rotor arm. An arched first piston is disposed in the first housing for reciprocating motion in a plane and within the first arched chamber via the first open end. A first seal, a first cavity, and a first piston define a first pressure chamber. A first portion of the first piston contacts the rotor arm. The tubular arch... A second piston is disposed in the second housing for reciprocating in a second arched chamber in a plane and in an arched tubular space via a second open end, wherein a second seal, a third seal, a second cavity, and a second piston define a second pressure chamber, and a second portion of the second piston contacts a rotor arm; pressurized fluid is applied to a first pressure chamber; the first piston is forced partially outward from the first pressure chamber to force the rotor arm to move in a first direction; the rotor arm is rotated in a second direction opposite to the first direction; and the first piston is forced partially into the first pressure chamber to force the pressurized fluid out of a first fluid port.

[0149] Various implementations may include some, all, or none of the following features. Rotating the rotor arm in a second direction opposite to the first direction may include: applying pressurized fluid to a second pressure chamber and forcing a second piston partially outward from the second pressure chamber to force the rotor arm to move in the second direction opposite to the first direction. Forcing the first piston partially outward from the first pressure chamber to force the rotor arm to move in the first direction may further include: moving the rotor arm in the first direction with a torque that is substantially constant in stroke.

[0150] Another exemplary machine arm includes 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 includes a rotary actuator comprising a housing defining a first arched chamber housing. The first arched chamber housing defines a first arched chamber and a second arched chamber. The first arched chamber includes a first cavity. The first cavity defines a first annular segment in a plane between a first open end and a first closed end and has a first fluid port in fluid communication with the first cavity. The annular segment has a first outer radius in the plane. The second arched chamber includes an inner chamber wall defining a second cavity. The second cavity defines a second annular segment in the plane between a second open end and a second closed end, and has a second fluid port in fluid communication with the second cavity. The second annular segment has a second outer radius from the axis, which is greater than the first outer radius and concentric with the first outer radius in the plane about the axis. It also has a second inner radius in the plane smaller than the first inner radius. Having a second intermediate radius substantially the same as the first intermediate radius, wherein the second arched chamber is oriented in rotation opposite to the first arched chamber about an axis, and wherein at least a portion of the first arched chamber shell is enclosed in a plane within at least a portion of the second arched chamber and defines an arched tubular space between the first arched chamber shell and the inner chamber wall, an arched actuation space defining a third arc segment in a plane about an axis between a first open end and a second open end, a rotor arm configured to rotate along the third arc segment within the actuation space, a rotor assembly coupled to the rotor arm, the arch... A first piston is disposed in the first housing for reciprocating in a plane and in a first arched chamber via a first open end, wherein a first seal, a first cavity, and a first piston define a first pressure chamber, and a first portion of the first piston contacts a rotor arm. A tubular arched second piston is disposed in the second housing for reciprocating in a plane and in an arched tubular space via a second open end in a second arched chamber, wherein a second seal, a third seal, a second cavity, and a second piston define a second pressure chamber, and a second portion of the second piston contacts a rotor arm.

[0151] Various embodiments may include some, all, or none of the following features. The rotor assembly may be fixed to or integral with the first arm portion. The housing may be fixed to or integral with the second arm portion.

[0152] Another exemplary rotary actuator includes a housing, a rotor arm, an arched first piston, and a rotor assembly. The housing defines a first arched chamber, the first arched chamber including a first cavity. The first cavity defines a first arc segment in a plane between a first open end and a first closed end, and has a first fluid port in fluid communication with the first cavity. The first arc segment has a first radius in the plane, the first radius defining an axis perpendicular to the plane. An arched actuation space defines an actuation arc segment about the axis between the first open end and the terminal end. The rotor arm is configured to rotate within the actuation space along a second arc segment. The arched first piston is disposed in the housing for reciprocating in a plane and within the first arched chamber via the first open end. A first seal, the first cavity, and the first piston define a first pressure chamber including part or all of the first arched chamber. A first portion of the first piston contacts the rotor arm. The rotor assembly is rotatably disposed around the housing and includes a rotating output tube about an axis. The rotor arm extends radially outward to the rotating output tube and is coupled to the rotating tube.

[0153] Various embodiments may include some, all, or none of the following features. The rotary actuator may also include a second arched chamber comprising a second cavity defining a second arcuate segment about an axis between a second open end and a second closed end, and having a second fluid port in fluid communication with the second cavity. The second arcuate segment may have a second radius from the axis, different from a first radius. The second arcuate segment may be concentric with the first arcuate segment about the axis in a plane. The second open end may be located at the termination, and the arched chamber may be oriented rotationally opposite to the first arched chamber about the axis. The second arcuate segment may not be in a plane, and at least a portion of the second arched chamber may axially overlap with the first arched chamber in a plane. The rotary actuator may also include an arched second piston disposed in the second housing and configured for reciprocating through the second open end in the second arched chamber, wherein the second seal, the second cavity, and the second piston define a second pressure chamber comprising part or all of the second arched chamber, and a second portion of the second piston contacts the rotor arm. Applying pressurized fluid to a first pressure chamber forces a first piston partially outward from the first pressure chamber to force the rotor arm to rotate in a first direction, and applying pressurized fluid to a second pressure chamber forces a second piston partially outward from the second pressure chamber to force the rotor arm to rotate in a second direction. At least one of the first and second pistons may include a rotor arm. Rotation of the rotor assembly forces the first piston partially into the first pressure chamber to pressurize the fluid and force the fluid out of a first fluid port. A rotating tube may include a rotor arm. The rotary actuator may also include a first housing sealing ring groove, a second housing sealing ring groove, and an annular seal, the first housing sealing ring groove being defined about an axis in the rotor assembly, the second housing sealing ring groove being defined about an axis in the housing and complementary to the first housing sealing ring groove, and the annular seal being located between the rotor assembly and the housing in the first and second housing sealing ring grooves.

[0154] Another exemplary rotary actuation method may include: providing a rotary actuator including a housing, a rotor arm, an arched first piston, and a rotor assembly, the housing defining a first arched chamber including a first cavity, the first cavity defining a first arcuate segment in a plane between a first open end and a first closed end, and having a first fluid port in fluid communication with the first cavity, the first arcuate segment having a first radius in the plane, the first radius defining an axis perpendicular to the plane, an arched actuation space defining an actuation arcuate segment about the axis between the first open end and the closed end, the rotor arm configured to rotate within the actuation space along a second arcuate segment, and the arched first piston disposed in the housing for rotational movement in the plane via the first open end and... Reciprocating motion within a first arched chamber, wherein a first seal, a first cavity, and a first piston define a first pressure chamber comprising part or all of the first arched chamber, a first portion of the first piston contacts a rotor arm, a rotor assembly rotatably surrounding the housing and including a rotating output tube about an axis, wherein the rotor arm extends radially outward to the rotating output tube and is coupled to the rotating tube; applying pressurized fluid to the first pressure chamber; forcing the first piston partially outward from the first pressure chamber to force the rotor assembly to rotate in a first direction; rotating the rotor assembly in a second direction opposite to the first direction; and forcing the first piston partially into the first pressure chamber to force the pressurized fluid out of a first fluid port.

[0155] Various implementations may include some, all, or none of the following features. The housing may also define a second arched chamber including a second cavity that defines a second arcuate segment about an axis between a second open end and a second closed end and has a second fluid port in fluid communication with the second cavity. The rotary actuator may also include an arched second piston disposed in the first housing for reciprocating motion in the second arched chamber, wherein a second seal, the second cavity, and the second piston define a second pressure chamber, and a first portion of the second piston contacts a second rotor arm. The second piston may be oriented in the same direction of rotation as the first piston. The second piston may be oriented in the opposite direction of rotation to the first piston. Rotating the rotor assembly in a second direction opposite to the first direction may include: applying pressurized fluid to the second pressure chamber and forcing the second piston partially outward from the second pressure chamber to force the rotor assembly to rotate in a second direction opposite to the first direction. Rotating the rotor assembly in a second direction opposite to the first direction may include: applying pressurized fluid to the second pressure chamber and forcing the first piston partially into the first pressure chamber to force the rotor assembly to rotate in a second direction opposite to the first direction. Forcing the first piston partially outward from the first pressure chamber to force the rotor assembly to rotate in the first direction may further include: rotating the rotor assembly in the first direction with a torque that is substantially constant over the stroke.

[0156] Another exemplary machine arm includes 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 includes a rotary actuator comprising a housing, a rotor arm, an arched first piston, and a rotor assembly. The housing defines a first arched chamber including a first cavity. The first cavity defines a first arcuate segment in a plane between a first open end and a first closed end, and has a first fluid port in fluid communication with the first cavity. The first arcuate segment has a first radius in the plane, which defines an axis perpendicular to the plane. An arched actuation space defines an actuation arcuate segment. An actuation arc segment is arranged around an axis between a first open end and a terminal end. A rotor arm is configured to rotate within an actuation space along a second arc segment. An arched first piston is disposed in the housing for reciprocating motion in a plane and within a first arched chamber via the first open end. A first seal, a first cavity, and a first piston define a first pressure chamber, which includes part or all of the first arched chamber. A first portion of the first piston contacts the rotor arm. A rotor assembly is rotatably arranged around the housing and includes a rotating output tube about an axis. The rotor arm extends radially outward to the rotating output tube and is coupled to the rotating tube.

[0157] Various embodiments may include some, all, or none of the following features. The rotor assembly may be fixed to or integral with the first arm portion. The housing may be fixed to or integral with the second arm portion.

[0158] Details of one or more embodiments are set forth in the accompanying drawings and the following description. Other features and advantages will become apparent from the specification, drawings, and claims. Attached Figure Description

[0159] Figure 1 This is a schematic diagram of an exemplary excavator with a linear fluid actuator.

[0160] Figure 2 This is a schematic diagram showing an example of a hinged boom with a rotary piston actuator.

[0161] Figure 3 This is a partial cross-sectional view of an exemplary rotary piston actuator connector portion.

[0162] Figure 4 This is a partial cross-sectional view of another exemplary rotary piston actuator connector portion.

[0163] Figure 5 This is an exploded view of an exemplary rotary piston actuator connector portion.

[0164] Figure 6A and 6B These are cross-sectional and perspective views of an exemplary rotary piston actuator with multiple concentric pistons.

[0165] Figure 7A and 7B These are cross-sectional and perspective views of an exemplary rotary piston actuator having multiple spatially co-located pistons.

[0166] Figure 8A and 8B These are cross-sectional and perspective views of an exemplary rotary piston actuator with a multi-chamber piston.

[0167] Figure 9 This is an exploded view of an exemplary rotary piston actuator connector portion with a modular rotary piston actuator.

[0168] Figure 10 This is a cross-sectional view of an exemplary fluid delivery shaft.

[0169] Figure 11 This is a cross-sectional view of another exemplary fluid delivery shaft.

[0170] Figure 12 This is a flowchart of an exemplary process for performing rotary actuation.

[0171] Figure 13 This is a perspective view of an exemplary rotary piston actuator connector portion having an arched bearing sleeve assembly.

[0172] Figure 14 This is an exploded view of an exemplary arched bearing sleeve assembly for a rotary piston actuator.

[0173] Figure 15A and 15B These are, respectively, a cross-sectional side view and an exploded view of another exemplary rotary piston actuator with an arched bearing sleeve assembly.

[0174] Figure 16 This is a cross-sectional side view of another exemplary arched bearing sleeve assembly.

[0175] Figure 17 This is a cross-sectional side view of another exemplary arched bearing sleeve assembly.

[0176] Figure 18 This is a flowchart of an exemplary process for performing rotary actuation of an exemplary rotary piston actuator joint portion having an arched bearing sleeve assembly. Detailed Implementation

[0177] This document describes a device for generating rotary motion. In particular, it describes a device that converts fluid displacement into rotary motion using components more commonly used for generating linear motion, such as hydraulic or pneumatic linear cylinders. A vane-type rotary actuator is a relatively compact device for converting fluid motion into rotary motion.

[0178] Figure 1 This is a schematic diagram of an exemplary prior art excavator 100. The excavator 100 includes a "cabin" or "driver's cab" 110 mounted on a tracked, wheeled, or other typically otherwise mobile chassis 120. An articulated boom 130 extends from the cabin 110 and includes a boom portion 132 and a boom portion 134. The boom portions 132 and 134 are pivotally connected at a joint 135. The boom portion 134 and a bucket 140 are pivotally connected at a joint 142. Linear pistons 150 and 160 provide power to actuate the boom portion 134 and the bucket 140, for example, maneuvering the bucket 140 for digging, scooping, lifting, or other such operations.

[0179] Linear pistons utilize relatively mature sealing technology, which offers easily understood kinetic operation and leak-proof characteristics. However, linear pistons require additional mechanical components to convert their linear motion into rotational motion. In the illustrated example, linear piston 150 is connected at one end to arm portion 132 and at the other end to lever arm 136, which extends beyond joint 135. Linear piston 160 is connected at one end to arm portion 134 and at the other end to lever arm assembly 162, which extends beyond joint 142. By extending and retracting linear actuator 150, lever arm 138 is actuated and generates torque about joint 136 to convert the linear motion of linear actuator 150 into rotational motion of arm portion 134 relative to arm portion 132. Linear actuator 160 is arranged in a similar linear-to-rotational configuration to pivotally actuate bucket 140 relative to arm portion 134.

[0180] Such linear-to-rotary mechanisms are generally larger and heavier than rotary actuators capable of providing similar rotary motion, thus occupying, for example, a larger working profile. Typically, rotary piston assemblies use a bent pressure chamber and a bent piston to controllably push and pull the rotor arm of a rotor assembly about an axis. However, existing rotary piston assemblies are generally larger and heavier than linear-to-rotary mechanisms capable of providing similar torque and load handling capacity. The rotary piston assembly described herein provides rotary applications with the position holding and power / torque characteristics generally associated with linear piston fluid actuators, and achieves this using a relatively more compact and lightweight profile.

[0181] Linear-to-rotary mechanisms, such as those used in excavator 100, may also expose many of their components to contamination. For example, linear pistons 150 and 160 may expose polished or otherwise sensitive surfaces to dust, dirt, and other such contaminants commonly encountered at construction sites. In another example, linear pistons 150 and 160 may be exposed to liquid contaminants such as rainwater or mud (e.g., linear piston 160 may be partially submerged in them during excavation operations). In yet another example, sensitive portions of linear pistons 150 and 160 may be exposed to physical damage, such as impacts with solid objects. Solid contaminants and physical impacts can damage polished surfaces and seals, leading to leaks and decreased hydraulic performance. Fluid contaminants can infiltrate the hydraulic system and damage hydraulic pumps, hoses, and seals. In some examples, the various moving parts of joints 135 and 142, lever arms 136, and lever arm assembly 162 may also have multiple points of such contamination and damage.

[0182] In some embodiments, the rotary piston assembly described herein may offer relatively greater resistance to contamination and / or relatively easier maintenance than a linear-to-rotary assembly with similar position holding and power / torque characteristics.

[0183] Furthermore, linear-to-rotary mechanisms, such as those used in excavator 100, may have a relatively limited range of motion and may have torque and / or motion characteristics that vary across the range of motion. For example, the range of motion between arm portion 132 and arm portion 134 can be mechanically limited to an extreme point (e.g., approximately) as the linear piston 150 extends and contacts arm portion 132. Figure 1 (as shown in the position). This range can be limited to the other extreme, for example, by the lever arm 136 contacting the arm portion 132 or by the linear piston 150 retracting and the arm portion 136 becoming substantially aligned between the linear piston 150 and the connector 135.

[0184] In some embodiments, the rotary piston assembly described herein may provide a relatively larger range of motion, a larger angular velocity, and / or a more constant angular velocity over its range of motion compared to linear-to-rotary assemblies used in similar applications.

[0185] As the linear piston 150 extends and retracts at a constant rate, the angular velocity of the arm portion 134 and the torque generated around the joint 135 will vary. For example, for a constant rate of linear actuation, the arm portion 134 may have the maximum angular velocity and torque when the lever arm 136 is at approximately a right angle relative to the linear piston 150, and the velocity and torque will be at their minimum at the extremes of the motion when the angle between the lever arm 136 and the linear piston is minimal. Existing excavators such as the excavator 100 require the operator to manually overcome this variability or to provide more constant motion by implementing complex fluid control systems to operate the linear piston in a non-linear manner. Some existing excavators such as the excavator 100 implement oversized linear pistons to compensate for the torque losses inherent in many linear-to-rotary configurations, but this oversized design often comes with additional weight and cost.

[0186] In some embodiments, the rotary piston assembly described herein may provide a relatively greater range of motion and / or a relatively more linear torque in the actuation angle compared to linear-to-rotary assemblies used in similar applications.

[0187] Figure 2 This is a schematic diagram illustrating an example of an articulated boom 200 (e.g., an excavator boom) with a rotary piston actuator. In some embodiments, the articulated boom 200 may be used on an excavator. For purposes of description herein, the term "excavator" may include excavators, trenchers, backhoe loaders, drilling rigs, cranes, bulldozers, robot actuators, or any other suitable form of construction machinery having a rotary or pivotable articulated joint.

[0188] The articulated boom 200 includes a boom portion 210 and a bucket 220. In some embodiments, the boom portion 210 may be connected at an end 212 to another boom portion or to the excavator's cab or operator's cab. In some embodiments, the bucket 220 may be replaced by another type of end effector, such as a bulldozer blade, pulley (e.g., a crane), drill bit, trenching component, gripper, grappling hook, fork, or any other suitable form of end effector that can be used with heavy machinery.

[0189] The boom section 210 and the bucket are connected via a multi-axis fluid actuator. The multi-axis fluid actuator is configured to manipulate the bucket 220 for digging, shoveling, lifting, or other such operations. The multi-axis fluid actuator includes a joint 240 and a joint 250. Joint 240 includes a rotary piston actuator that pivotally connects joint arm 260 to joint arm 262 about a first axis. Figure 3 The connector 240 and the rotary piston actuator are described in more detail in the description. Connector 250 includes another rotary piston actuator that pivotally connects connector arm 262 about a second axis to connector arm 264. Further details will be provided in the description. Figure 4 and 5 The description of connector 250 and the rotary piston actuator is further detailed. The multi-axis fluid actuator is removably connected (e.g., bolted, pinned) to the boom portion 210 via connector arm 260 and removably connected to the bucket 220 via connector arm 264. Connectors 240 and 250 are configured to provide two axes of motion between the bucket 220 and the boom portion 210.

[0190] Figure 3 for Figure 2 A partial cross-sectional view of an exemplary connector 240. Connector 240 includes a rotary piston actuator 300. Generally, rotary piston actuators use a bending pressure chamber and a bending piston to controllably push and pull the rotor arm of a rotor assembly about an axis. In use, specific embodiments of the rotary piston actuator described herein can provide position holding characteristics generally associated with linear piston-type fluid actuators to rotary applications, and do so using a relatively more compact and lightweight profile generally associated with rotary vane actuators.

[0191] Actuator 300 includes a rotary piston assembly 310 and a pressure chamber assembly 320. Actuator 300 includes a first actuation section 360 and a second actuation section 370. In an example of actuator 300, the first actuation section 360 is configured to rotate the rotary piston assembly 310 in a first direction, such as counterclockwise, and the second actuation section 370 is configured to rotate the rotary piston assembly 310 in a second direction substantially opposite to the first direction, such as clockwise.

[0192] The rotary piston assembly 310 includes a connecting rod 380 connected to a connector arm 260. A plurality of connecting rod arms 382 extend radially from the connecting rod 380, and the distal end of each connecting rod arm 382 includes a bore 383 substantially aligned with the axis of rotation of the rotary piston assembly 310 and sized to accommodate one of a group of connecting pins (not shown).

[0193] The first actuating section 360 includes a rotating piston 312, and the second actuating section 370 includes a rotating piston 314. Although the exemplary actuator 300 includes two rotating pistons 312, 314, other embodiments may include more and / or fewer numbers of cooperating and opposing rotating pistons of various configurations. The following, for example, in the description of... Figure 6A Examples of other such embodiments will be discussed in the description of -11.

[0194] exist Figure 3In the exemplary rotary piston assembly 310 shown, each rotary piston 312, 314 includes a piston end 316 and one or more connecting arms 318. The piston end 316 is formed to have a body having a generally semi-circular arc segment and a substantially smooth surface. Each connecting arm 318 includes a drilled hole 384 substantially aligned with the axis of the semi-circular arc segment of the piston end 316 and sized to accommodate a connecting pin (not shown).

[0195] Figure 3 In the exemplary rotary piston assembly 310, rotary pistons 312 and 314 are oriented to be rotationally opposite to each other. Rotary pistons 312 and 314 can be assembled to connecting rod 380 by aligning connecting arm 382 with connecting arm 318 such that boreholes 383 and 384 are aligned. Connecting pins (not shown) can then be inserted through the aligned boreholes 383 and 384 to create a hinged connection between pistons 312 and 314 and connecting rod 380. Each connecting pin is slightly longer than the aligned borehole. In the exemplary assembly, a circumferential recess (not shown) extending beyond the outer periphery of each end of the aligned borehole around each connecting pin can accommodate a retaining fastener (not shown), such as a snap ring or helical ring.

[0196] The pressure chamber assembly 320 is removably connected to the connector arm 262 by a set of fasteners (not shown) (e.g., bolts, pins, screws) that pass through a set of drilled holes 370 in the connector arm 262 and into a set of corresponding drilled holes 371 in the axial end of the pressure chamber assembly 320. In the illustrated example, fluid pressure can be introduced to controllably force the rotary pistons 312, 314 away from the pressure chamber assembly 320. Movement of the rotary pistons 312, 314, assembled to the connecting rod 380, forces the connector arm 260 to pivot relative to the connector arm 262, which is assembled to the pressure chamber assembly 320.

[0197] The pressure chamber assembly 320 has a generally cylindrical shape. (Reference) Figure 2 The connector 240 includes a housing 241 configured as a tubular wall surrounding an inner bore sized to accommodate a pressure chamber assembly 320. The housing 241 is connected to or integrally formed with the connecting rod 380.

[0198] Back Figure 3 , outer shell 241 ( Figure 3(The middle portion is visible) substantially surrounds the pressure chamber assembly 320. As the rotating pistons 312, 314 are actuated, the generally cylindrical pressure chamber assembly 320 rotates within the housing 241. The housing 241 provides a bearing surface that supports the pressure chamber assembly 320 as it rotates. In some embodiments, the contact between the pressure chamber assembly 320 and the housing 241 can support a load. For example, a load on the connector arm 262 can be transferred to the pressure chamber assembly 320, to the housing 241 (e.g., via the bearing surface), to the connecting rod 380, and continues to the connector arm 260.

[0199] The connector arm 262 includes a circular sealing groove 390, and the housing 241 includes a corresponding sealing groove 392. When the connector arm 262 is mounted to the pressure chamber assembly 320, the sealing grooves 390 and 392 are aligned. The sealing grooves 390 and 392 receive a seal 394. As the connector arm 262 pivots relative to the housing 241, the seal 394 substantially prevents external contaminants (e.g., dust, water, dirt, mud, sand) from entering the actuator 300, including the bearing surface between the housing 241 and the pressure chamber assembly 320 and the rotary piston assembly 310. In some embodiments, the sealing arrangement of the actuator 300 is thus suitable for use or immersion in wet, dirty, or other contaminated environments without substantially exposing internal components (e.g., the polished surfaces of the rotary pistons 312, 314) to external contamination.

[0200] Figure 4 for Figure 2 A partial cross-sectional view of an exemplary connector 250. Figure 5 This is an exploded view of an exemplary connector 250. Connector 250 includes a rotary piston actuator 400. In some embodiments, the rotary piston actuator 400 may be... Figure 3 An exemplary rotary piston actuator 300 is shown. In some embodiments, a rotary piston actuator 400 may be used... Figure 2 The multi-axis connector 200.

[0201] Actuator 400 includes a rotary piston assembly 310 and a pressure chamber assembly 320. Actuator 400 includes a first actuation section 360 and a second actuation section 370. In an example of actuator 400, the first actuation section 360 is configured to rotate the rotary piston assembly 310 in a first direction, such as counterclockwise, and the second actuation section 370 is configured to rotate the rotary piston assembly 310 in a second direction substantially opposite to the first direction, such as clockwise.

[0202] The rotary piston assembly 310 of the actuator 400 includes a connecting rod 480 connected to a connector arm 262. A plurality of connecting rod arms 482 extend radially from the connecting rod 380, and the distal end of each connecting rod arm 482 includes a bore 483 substantially aligned with the axis of rotation of the rotary piston assembly 310 and sized to accommodate one of a group of connecting pins (not shown).

[0203] The first actuation section 360 of the actuator 400 includes a rotary piston 312, and the second actuation section 370 includes a rotary piston 314. Although the exemplary actuator 300 includes two rotary pistons 312, 314, other embodiments may include more and / or fewer numbers of cooperating and opposing rotary pistons of various configurations. The following, for example, in the description of... Figure 6A Examples of other such embodiments will be discussed in the description of -11.

[0204] Figure 4 and 5 In the exemplary rotary piston assembly 310, rotary pistons 312 and 314 are oriented to be rotationally opposite to each other. Rotary pistons 312 and 314 can be assembled to connecting rod 480 by aligning connecting arm 482 with connecting arm 318 such that boreholes 483 and 384 are aligned. Connecting pins (not shown) can then be inserted through the aligned boreholes 483 and 384 to create a hinged connection between pistons 312 and 314 and connecting rod 480. Each connecting pin is slightly longer than the aligned borehole. In the exemplary assembly, a circumferential recess (not shown) extending beyond the outer periphery of each end of the aligned borehole around each connecting pin can accommodate a retaining fastener (not shown), such as a snap ring or helical ring.

[0205] The pressure chamber assembly 320 of the actuator 400 is removably connected to the connector arm 264 via a set of fasteners (not shown) (e.g., bolts, pins, screws) that pass through a set of drilled holes 470 in the connector arm 264 and into a set of corresponding drilled holes 371 in the axial end of the pressure chamber assembly 320. In the illustrated example, fluid pressure can be introduced to controllably force the rotary pistons 312, 314 away from the pressure chamber assembly 320. Movement of the rotary pistons 312, 314, assembled to the connecting rod 480, forces the connector arm 264 to pivot relative to the connector arm 262, which is assembled to the pressure chamber assembly 320.

[0206] The pressure chamber assembly 320 of the actuator 400 has a generally cylindrical shape. (Reference) Figure 2 The connector 250 includes a housing 251 configured as a tubular wall surrounding an inner bore sized to accommodate a pressure chamber assembly 320. The housing 251 is connected to or integrally formed with the connecting rod 480.

[0207] Back Figure 4 , outer shell 251 ( Figure 4 (The middle portion is visible) substantially surrounds the pressure chamber assembly 320. As the rotating pistons 312, 314 are actuated, the generally cylindrical pressure chamber assembly 320 rotates within the housing 251. The housing 251 provides a bearing surface that supports the pressure chamber assembly 320 as it rotates. In some embodiments, the contact between the pressure chamber assembly 320 and the housing 251 can support a load. For example, a load on the connector arm 264 can be transferred to the pressure chamber assembly 320, to the housing 251 (e.g., via the bearing surface), to the connecting rod 480, and continues to the connector arm 262.

[0208] The connector arm 264 includes a circular sealing groove 390, and the housing 251 includes a corresponding sealing groove 492. When the connector arm 264 is mounted to the pressure chamber assembly 320, the sealing grooves 390 and 492 are aligned. The sealing grooves 390 and 492 of the actuator 400 accommodate a seal 494. As the connector arm 264 pivots relative to the housing 251, the seal 494 substantially prevents external contaminants (e.g., dust, water, dirt, mud, sand) from entering the actuator 400, including the bearing surface between the housing 251 and the pressure chamber assembly 320 and the rotary piston assembly 310. In some embodiments, the sealing arrangement of the actuator 400 is thus suitable for use or immersion in wet, dirty, or other contaminated environments without substantially exposing internal components (e.g., the polished surfaces of the rotary pistons 312, 314) to external contamination.

[0209] Figure 3 Rotary piston actuator 300 and Figure 4 The rotary piston actuator in -5 is used in some embodiments. Figure 2 An example of a rotary piston actuator with a multi-axis connector 200 is shown below. In some embodiments, rotary piston actuators of various configurations may be used. Figure 6A The description in -11 discusses several examples of such rotary piston actuators.

[0210] Figure 6A and 6B These are cross-sectional and perspective views of an exemplary rotary piston actuator 600 having a plurality of concentrically arranged pistons. In some embodiments, the rotary piston actuator 600 may be... Figure 3 An exemplary rotary piston actuator 300 is shown. In some embodiments, the rotary piston actuator 600 can be used... Figure 2The multi-axis connector 200 is included. The actuator 600 includes a rotary piston 610, a rotary piston 620, and a pressure chamber assembly 630. Although the exemplary actuator 600 includes two rotary pistons 610, 620, other embodiments may include more and / or fewer cooperating and opposing rotary pistons.

[0211] The housing 630 includes an arched chamber 631 having a cavity defining an arcuate segment, indicated by line 633. The arcuate segment 633 extends in a plane between the open end 634 and the closed end 636 of the chamber 631. The chamber 631 includes a fluid port (not shown) in fluid communication with the cavity. The arcuate segment 633 has a radius in the plane, indicated by line 635. The radius 635 defines an axis 638 perpendicular to the plane.

[0212] The housing 630 includes an arched chamber 650 having a cavity defining an arcuate segment, indicated by line 653. The arcuate segment 653 extends in a plane between the open end 654 and the closed end 655 of the chamber 650. The chamber 650 includes a fluid port (not shown) in fluid communication with the cavity. The arcuate segment 653 has a radius indicated by line 655 radiating from axis 638.

[0213] Radius 635 is greater than radius 655, and arc segment 633 has a larger diameter than arc segment 653. Arched chamber 631 defines a space that is substantially concentric with arched chamber 650 in a substantially common plane about axis 638. In some embodiments, arched chamber 631 may occupy an angular range about axis 638 that at least partially overlaps with the angular range occupied by arched chamber 650. In the illustrated example, the angular range is shown by arc segment 660. Thus, arched chambers 631 and 650 are concentric about axis 638 and, in some embodiments, may occupy overlapping angular ranges about axis 638, substantially not intersecting each other. In other words, the arched chamber 631 and the arched chamber 650 are formed as two segments of two rings, wherein the two rings have two different diameters, such that the chambers 631 and 650 do not intersect each other, and the two segments can at least partially share an angular range around the axis 638, while the chambers 631 and 650 do not intersect each other.

[0214] exist Figure 6A and 6B In the exemplary rotary piston actuator 600 shown, the rotary piston 610 includes a piston end 612 and a contact end 614. The rotary piston 620 includes a piston end 622 and a contact end 624. The piston ends 612 and 622 are formed as bodies having a generally geometric shape and a substantially smooth surface. The contact ends 614 and 624 are configured to contact (e.g., push, push) the rotor arm 640.

[0215] The piston end 622 has an arch shape configured to fit within an arched chamber 631. The piston end 622 is disposed within the housing 630 for reciprocating motion within the arched chamber 631 in a plane passing through the open end 634. The seal 672, the cavity, and the piston end 622 define another pressure chamber, and the contact end 624 is oriented to contact the rotor arm 640.

[0216] The piston end 612 has an arch shape configured to fit within an arched chamber 650. The piston end 612 is disposed within a housing 630 for reciprocating motion within the arched chamber 650 in a plane passing through the open end 654. The seal 670, the cavity, and the piston end 612 define a pressure chamber, and the contact end 614 is oriented to contact the rotor arm 640.

[0217] Figure 6A In the exemplary actuator 600 of -6B, the rotating piston 610 is oriented in a rotational opposite manner to the rotating piston 620, and the piston ends 612 and 622 contact the angularly opposite sides of the rotor arm 640.

[0218] Rotor arm 640 is removably connected to the inner surface 682 of tubular rotor assembly 680. Rotor assembly 680 substantially surrounds housing 630. An arched actuation space 690 is defined between inner surface 682 and housing 630 and between terminals 692 and 694. Open end 634 is formed in terminal 692, and open end 654 is formed in terminal 694.

[0219] As fluid pressure is applied to the arched chamber 631, the piston end 622 is forced outward from the arched chamber 631. As the arched piston 620 moves, the contact end 624 contacts the rotor arm 640, which is removably connected to the rotor assembly 680, to force the rotor assembly 680 to rotate about axis 638. In the example shown, this pressurization will cause the arched piston 620, rotor arm 640, and rotor assembly 680 to rotate counterclockwise about axis 638.

[0220] As fluid pressure is applied to the arched chamber 650, the piston end 612 is forced outward from the arched chamber 650. As the arched piston 610 moves, the contact end 614 contacts the rotor arm 640, which is removably connected to the rotor assembly 680, to force the rotor assembly 680 to rotate about axis 638. In the example shown, this pressurization will cause the arched piston 610, rotor arm 640, and rotor assembly 680 to rotate clockwise about axis 638.

[0221] In some embodiments, the construction of concentric, non-intersecting, and angularly overlapping chambers 631 and 650 provides an extended actuation range. In the illustrated example, the arched actuation space 690 occupies an arc segment of approximately 180°. Thus, the rotor assembly 680 can be actuated relative to the housing 630 through an arc segment having an angle range of approximately 180°, for example, 180° minus the angular thickness based on the rotor arms 640 and contact ends 614 and 624 within the arched actuation space, which may vary depending on the application.

[0222] In some embodiments, the rotary piston actuator 600 may be used to pivotally connect to and actuate a joint. For example, housing 630 may be connected to a first arm portion or mounting point of the machine, and rotor assembly 680 may be connected to a second arm portion or mounting point on the machine to actuate the first arm portion or mounting point relative to the second arm portion or mounting point. In some embodiments, the rotary piston actuator 600 may be... Figure 3 -5. Rotary piston actuator 300 or 400. For example, housing 630 may be pressure chamber assembly 320 removably connected to connector arm 262, and rotor assembly 680 may be housing 241 removably connected to connector arm 260 or integrally formed with connector arm 260.

[0223] An exemplary rotary piston actuator 600 also includes a bore 695 formed substantially along axis 683. In some embodiments, one or more arched chambers 631, 650 may be in fluid communication with the bore 695 via one or more fluid ports (not shown). For example, fluid pressure may be applied to the bore 695 to pressurize chamber 631 and force rotor assembly 680 to rotate counterclockwise. In another example, rotor assembly 680 may rotate clockwise, thereby forcing piston end 622 into chamber 631, thereby pressurizing fluid in chamber 631 and forcing fluid out through the port leading to bore 695. In some embodiments, bore 695 may accommodate a fluid delivery shaft configured to provide part of a fluid loop between one or both of chambers 631, 650 (e.g., via fluid ports) and a fluid source (e.g., a fluid pump or reservoir) outside the actuator 600.

[0224] Figure 7A and 7B These are cross-sectional and perspective views of an exemplary rotary piston actuator 700 having multiple spatially co-located (e.g., nested) pistons. In some embodiments, the rotary piston actuator 700 may be... Figure 3 An exemplary rotary piston actuator 300 is shown. In some embodiments, the rotary piston actuator 700 can be used... Figure 2The multi-axis connector 200 is included. The actuator 700 includes a rotary piston 710, a rotary piston 720, and a housing 730. Although the exemplary actuator 700 includes two rotary pistons 710, 720, other embodiments may include more and / or fewer cooperating and opposing rotary pistons.

[0225] Actuator 700 includes a housing 730. Housing 730 includes an arched chamber housing 731 defining an arched chamber having a cavity formed as an annular segment along an arc segment shown by line 733. The arc segment 733 extends in a plane between the open end 734 of the chamber 731 and the closed end 736 of the chamber housing 731. The chamber housing 731 includes a fluid port (not shown) in fluid communication with the cavity. The arc segment 733 has a central radius in the plane shown by line 735. Radius 735 defines an axis 738 perpendicular to the plane.

[0226] The annular segment defined by the chamber housing 731 has an outer radius 701 in the plane. Radius 735 also defines an axis 738 and extends perpendicular to the plane. The annular segment defined by the chamber housing 731 also has an inner radius 702 in the plane.

[0227] The housing 730 includes an arched chamber 750. The arched chamber 750 has an inner chamber wall 704 defining a cavity formed as another annular segment along an arc segment 733 in a plane. The chamber 750 extends between an open end 754 and a closed end 756. The chamber 750 includes a fluid port (not shown) in fluid communication with the cavity defined by the chamber 750. The annular segment defined by the chamber 750 has an outer radius 706 extending from an axis 738. The outer radius 706 is greater than the outer radius 701 and is concentric with the outer radius 701 about the axis 738 in a plane. The annular segment defined by the chamber 750 also has an inner radius 707, which is smaller than the inner radius 702 and is concentric with the inner radius 702 about the axis 738 in a plane. The annular section defined by the chamber 750 also has a central radius 737, which is substantially the same as the central radius 735.

[0228] The arched chamber 750 is oriented in rotation opposite to that of the arched chamber shell 731 about axis 738. The arched chamber 731 defines a space that is substantially concentric with the arched chamber 750 about arc segment 733 and in a substantially common plane. At least a portion of the chamber shell 731 is enclosed within at least a portion of the chamber 750 in this plane. This concentric arrangement of the chamber shell 731 within the chamber 750 defines an arched tubular space 721 between the arched chamber shell 731 and the inner chamber wall 704.

[0229] In some embodiments, the arched chamber housing 731 may occupy an angular range about axis 738, which may at least partially overlap with the angular range occupied by the arched chamber 750. In the illustrated example, the angular range is shown by arc segment 760. Thus, the arched chamber housing 731 is nested within the arched chamber 750 along a portion of axis 738, and in some embodiments may occupy overlapping angular ranges about axis 738, substantially not in fluid communication with each other.

[0230] exist Figure 7A and 7B In the exemplary rotary piston actuator 700 shown, the rotary piston 710 includes a piston end 712 and a contact end 714. The rotary piston 720 includes a piston end 722 and a contact end 724. The contact ends 614 and 624 are configured to contact (e.g., push, push) the rotor arm 740.

[0231] The piston end 712 is formed as a body with a generally geometric shape and a substantially smooth surface. The piston end 712 has an arch, configured to fit within an arched cavity of an arched chamber housing 731. The piston end 712 is disposed within the housing 730 for reciprocating motion within the arched cavity of the arched chamber housing 731 in a plane passing through the open end 734. A seal 770, the cavity, and the piston end 712 define a pressure chamber, and a contact end 714 is oriented to contact the rotor arm 740.

[0232] The piston end 722 has an arched tubular shape configured to fit within an arched chamber 750. The piston end 722 is disposed within a housing 730 for reciprocating within an arched tubular space 721 between the arched chamber housing 731 and the inner chamber wall 704 in a plane passing through the open end 754. A seal 772, the cavity, and the piston end 722 define another pressure chamber, and a contact end 724 is oriented to contact the rotor arm 740.

[0233] Figure 7A In the exemplary actuator 700 of -7B, the rotating piston 710 is oriented in a rotational opposite manner to the rotating piston 720, and the piston ends 712 and 722 contact the angularly opposite sides of the rotor arm 740.

[0234] Rotor arm 740 is removably connected to the inner surface 782 of tubular rotor assembly 780. Rotor assembly 780 substantially surrounds housing 730. An arched actuation space 794 is defined between inner surface 782 and housing 730 and between terminals 790 and 792. Open end 734 is formed in terminal 794, and open end 754 is formed in terminal 792.

[0235] As fluid pressure is applied to the arched chamber 731, the piston end 712 is forced outward from the arched chamber 731. As the arched piston 710 moves, the contact end 714 contacts the rotor arm 740, which is removably connected to the rotor assembly 780, to force the rotor assembly 780 to rotate about axis 738. In the example shown, this pressurization will cause the arched piston 710, rotor arm 740, and rotor assembly 780 to rotate clockwise about axis 738.

[0236] As fluid pressure is applied to the arched chamber 750, the piston end 722 is forced outward from the arched chamber 750. As the arched piston 720 moves, the contact end 724 contacts the rotor arm 740, which is removably connected to the rotor assembly 780, to force the rotor assembly 780 to rotate about axis 738. In the example shown, this pressurization will cause the arched piston 720, rotor arm 740, and rotor assembly 780 to rotate counterclockwise about axis 738.

[0237] In some embodiments, the construction of substantially coaxially nested chambers, such as the arched chamber housing 731 within the arched chamber 750, can provide an extended range of actuation. In the illustrated example, the arched actuation space 790 occupies an arc segment of approximately 180°. Thus, the rotor assembly 780 can be actuated relative to the housing 730 through an arc segment having an angle space ranging from zero to approximately 180°, for example, 180° minus the angular thickness based on the rotor arms 740 and contact ends 714 and 724 within the arched actuation space, which may vary depending on the application.

[0238] In some embodiments, the rotary piston actuator 700 may be used to pivotally connect to and actuate a joint. For example, housing 730 may be connected to a first arm portion or mounting point of the machine, and rotor assembly 780 may be connected to a second arm portion or mounting point on the machine to actuate the first arm portion or mounting point relative to the second arm portion or mounting point. In some embodiments, the rotary piston actuator 700 may be... Figure 3 -5. Rotary piston actuator 300 or 400. For example, housing 730 may be pressure chamber assembly 320 removably connected to connector arm 262, and rotor assembly 780 may be housing 241 removably connected to connector arm 260 or integrally formed with connector arm 260.

[0239] An exemplary rotary piston actuator 700 also includes a borehole 795 formed substantially along axis 783. In some embodiments, one or more of the arched chambers in the arched chamber housing 731 and the arched chamber 750 are in fluid communication with the borehole 795 via one or more fluid ports (not shown). For example, fluid pressure may be applied to the borehole 795 to pressurize the chamber 750 and force the rotor assembly 780 to rotate counterclockwise. In another example, the rotor assembly 780 may rotate clockwise, thereby forcing the piston end 722 into the chamber 750, thereby pressurizing the fluid in the chamber 750 and forcing the fluid to exit through the port leading to the borehole 795. In some embodiments, the borehole 795 may accommodate a fluid delivery shaft configured to provide part of a fluid loop between one or both chambers of the chamber housing 731 and the chamber 750 (e.g., via a fluid port) and a fluid source (e.g., a fluid pump or reservoir) outside the actuator 700.

[0240] Figure 8A and 8B This is a cross-sectional view of an exemplary rotary piston actuator (RPA) 800 with a multi-chamber piston. Generally, the rotary piston actuator 800 is configured as an RPA within an RPA. Typically, an RPA may be configured to have a hollow piston that acts as a pressure chamber for a second piston within the hollow piston. In this example, the hollow piston separates two independent pressure chambers that can be actuated individually, for example, to provide two different torques or to provide coarse and fine positioning control. In some embodiments, the rotary piston actuator 800 may be... Figure 3 An exemplary rotary piston actuator 300 is shown. In some embodiments, the rotary piston actuator 800 can be used... Figure 2 The multi-axis connector 200.

[0241] Actuator 800 includes piston assembly 810, piston assembly 820, and pressure chamber assembly 860 (e.g., housing). Pressure chamber assembly 860 defines a chamber including a body 862a, a first fluid port (not shown) in fluid communication with the body 862a, and an open end 864a. Pressure chamber assembly 860 also defines a chamber including a body 862b, a fluid port (not shown) in fluid communication with the body 862b, and an open end 864b.

[0242] Piston assembly 820 includes a tubular piston 822a. The tubular piston 822a defines a chamber including a body 824a and an open end 826a. A fluid port (not shown) is in fluid communication with the body 824a. The tubular piston 822a is disposed in a pressure chamber assembly 860 for reciprocating within a chamber 862a via the open end 864a. A seal 866a, the body 824a, and the piston 822a define a pressure chamber 868a.

[0243] Piston assembly 820 includes a tubular piston 822b. The tubular piston 822b defines a chamber including a body 824b and an open end 826b. A fluid port (not shown) is in fluid communication with the body 824b. The tubular piston 822b is disposed in a pressure chamber assembly 860 for reciprocating within a chamber 862b via the open end 864b. A seal 866b, the body 824b, and the piston 822b define a pressure chamber 868b.

[0244] Piston assembly 810 includes piston 812a, which is disposed in piston assembly 820 for reciprocating motion in chamber 868a via open end 864a. Seal 826a, cavity 824a, and piston 812a define pressure chamber 828a. A portion 814a of piston 812a contacts rotor arm 870 (e.g., end actuator).

[0245] Piston assembly 810 includes piston 812b, which is disposed in piston assembly 820 for reciprocating motion in chamber 868b via open end 864b. Seal 826b, cavity 824b, and piston 812b define pressure chamber 828b. A portion 814b of piston 812b contacts rotor arm 870 (e.g., end effector).

[0246] In the example of actuator 800, pressure chambers 828a, 828b, 868a, and 868b are substantially sealed to each other and can be pressurized individually. For example, a fluid pressure can be applied to pressure chamber 828a and a different fluid pressure can be applied to pressure chamber 828b.

[0247] In the example of actuator 800, pressure chamber 828a is configured to rotate the rotary piston assembly 810 in a first direction, such as clockwise, and pressure chamber 828b is configured to rotate the rotary piston assembly 810 in a second direction that is substantially opposite to the first direction, such as counterclockwise.

[0248] In the example of actuator 800, pressure chamber 868a is configured to rotate the rotary piston assembly 820 in a first direction, such as clockwise, and pressure chamber 868b is configured to rotate the rotary piston assembly 820 in a second direction that is substantially opposite to the first direction, such as counterclockwise.

[0249] In some embodiments, the configuration of nested and independently pressurizable chambers 828a, 828b, 868a, and 868b provides an extended actuation range. In the illustrated example, chambers 828a, 828b, 868a, and 868b each provide approximately 90° of rotation. However, a coordinated combination of chambers 828a and 868a provides approximately 180° of rotation. Similarly, a coordinated combination of chambers 828b and 868b provides approximately 180° of rotation in opposite directions. Thus, the rotor arm 860 can be actuated relative to the housing 830 through an arc segment having a range of zero to approximately 180°, which may vary depending on the application.

[0250] In some embodiments, the rotary piston actuator 800 may be used to pivotally connect to and actuate a joint. For example, a housing 830 may be connected to a first arm portion or mounting point of a machine, and an end effector 870 may be connected to a second arm portion or mounting point on the machine to actuate the first arm portion or mounting point relative to the second arm portion or mounting point. In some embodiments, the rotary piston actuator 800 may be... Figure 3 -5. Rotary piston actuator 300 or 400. For example, housing 830 may be pressure chamber assembly 320 removably connected to connector arm 262, and end actuator 870 may be housing 241 removably connected to connector arm 260 or integrally formed with connector arm 260.

[0251] Figure 9 This is an exploded view of an exemplary rotary piston actuator connector portion 901. In some embodiments, connector 901 can be used... Figure 2 In the multi-axis connector 200, the piston actuator 400 has been replaced by a modular rotary piston actuator 900. Generally, the modular rotary piston actuator 900 includes one or more rotary piston actuator modules, such as in the case of... Figure 6A Examples of actuators 600, 700, and 800 discussed in the description of -8B.

[0252] Actuator 900 includes three rotary piston actuator modules 902a-902c. Generally, within the modular rotary piston actuator 900, the rotary piston actuator modules 902a-902c are individually replaceable and generally interchangeable. In some embodiments, each module 902a-902c may be... Figure 3 The embodiment of any of the rotary piston actuators 300, 400, 600, 700 or 800 of -8B, or other suitable rotary piston actuators, rotary vane actuators or combinations thereof.

[0253] The rotary piston actuator modules 902a-902c each include a rotary piston assembly 910 (e.g., rotary piston assemblies 310, 810, 820, rotary pistons 610, 620, 710, 720) and a housing 920, which also serves as a pressure chamber assembly (e.g., pressure chamber 320, pressure chamber assemblies 630, 730, 860).

[0254] Each rotary piston assembly 910 includes a connecting rod 980 (e.g., connectable to a connector arm 260). A plurality of connecting rod arms 982 extend radially from the connecting rods 980, each connecting rod arm 982 having a distal end including a bore 983 substantially aligned with the axis of rotation of the rotary piston assembly 910 and sized to accommodate one of a group of connecting pins (not shown). Although the exemplary actuator 900 includes three modules 902a-902c, other embodiments may include more and / or fewer cooperating and opposing rotary piston actuator modules of various configurations.

[0255] exist Figure 9 Each of the exemplary rotary piston assemblies 910 shown includes a rotary piston 912. Each rotary piston 912 includes a piston end 916 and one or more connecting arms 918. The piston end 916 is formed to have a body having a generally semi-circular arc segment and a substantially smooth surface. Each connecting arm 918 includes a drilled hole 984 substantially aligned with the axis of the semi-circular arc segment of its corresponding piston end 916 and sized to accommodate a connecting pin (not shown).

[0256] The pressure chamber assembly 920 has a generally cylindrical shape. The connecting rod 980 includes a housing 941 configured as a tubular wall surrounding an inner bore sized to accommodate the pressure chamber assembly 920. The housing 941 is connected to or integrally formed with the connecting rod 980.

[0257] The rotary piston actuator modules 902a-902c are removably assembled by inserting them axially into the housing 941. The rotary piston actuator modules 902a-902c are rotatably interconnected by a group of pins 951 and corresponding recesses (not shown) formed on the axial surface of the pressure chamber assembly 920. The rotary piston actuator modules 902a-902c are also rotatably interconnected by a group of rods 952 inserted into a group of drilled holes 970 formed axially along the pressure chamber assembly 920.

[0258] Each pressure chamber assembly 920 includes a central bore 995. A fluid delivery shaft 954 is arranged axially within the central bore 995. Figure 10 and 11 The description further discusses the fluid delivery shaft 954.

[0259] Each rotary piston actuator module 902a-902c is configured to be removably assembled in the actuator 900 in two different operating orientations. In the illustrated example, rotary piston actuator modules 902a and 902c are oriented to be rotationally compatible with each other. Rotary piston actuator module 902b is oriented to be rotationally opposite to rotary piston actuator modules 902a and 902c. In some embodiments, rotary piston actuator modules 902a-902c may be assembled into the actuator 900 in one of a clockwise or counterclockwise orientation. In some embodiments, a combination of clockwise and counterclockwise orientations of rotary piston actuator modules 902a-902c may be assembled into the actuator 900 in substantially any suitable order (e.g., axial arrangement).

[0260] Despite Figure 9 Three rotary piston actuator modules 902a-902c are shown and described, but in some embodiments, actuator 900 may implement more or fewer rotary piston actuator modules. In some embodiments, more rotary piston actuator modules 902a-902c may be oriented in one rotational direction rather than another. For example, actuator 900 may be used in an excavator arm where a larger operating torque may be required for lifting operations (e.g., up or clockwise rotation) compared to digging operations (e.g., "down" or "counterclockwise" rotation). In such an example, rotary piston actuator modules 902a-902c may be intentionally arranged to provide asymmetric torque that reflects the desired operating torque.

[0261] In some embodiments, the ability to configure actuator 900 with an asymmetric torque capability that reflects the application to which actuator 900 is applied means that the overall power-to-weight ratio, torque-to-weight ratio, and / or space requirements of actuator 900 can be improved. For example, a symmetric application may require two clockwise and two counterclockwise rotary piston actuator modules (e.g., four in total), while an asymmetric application may require only two clockwise and one counterclockwise rotary piston actuator module (e.g., three in total). In the example of the asymmetric application, the space, power consumption, and cost associated with a fourth rotary piston actuator module can be avoided.

[0262] Furthermore, component 900 can be reconfigured as needed to alter its asymmetric characteristics. For example, by rearranging or replacing the rotary piston actuator modules 902a-902c in actuator 900, an excavator originally configured to provide more lifting power than digging power for one set of tasks can be reconfigured to provide more digging power than lifting power for different sets of tasks.

[0263] The rotary piston 912 can be assembled to the connecting rod 980 by aligning the connecting arm 982 with the connecting arm 918, thereby aligning the bores 983 and 984. A connecting pin (not shown) can then be inserted through the aligned bores 983 and 984 to create a hinged connection between the piston 912 and the connecting rod 980. Each connecting pin is slightly longer than the aligned bore. In an exemplary assembly, a circumferential recess (not shown) extending beyond the outer periphery of each end of the aligned bore around each connecting pin can accommodate a retaining fastener (not shown), such as a snap ring or a spiral ring.

[0264] The pressure chamber assembly 920 is removably connected to the connector arm 964 via a set of fasteners (not shown) (e.g., bolts, pins, screws) that pass through a set of drilled holes 970 in the connector arm 964 and into a set of corresponding drilled holes 971 in the axial end of the pressure chamber assembly 920. In the illustrated example, fluid pressure can be introduced to controllably force the rotary piston 912 away from the pressure chamber assembly 920. Movement of the rotary piston 912, assembled to the connecting rod 980, forces the connecting rod 980 to pivot relative to the connector arm 964, which is assembled to the pressure chamber assembly 920.

[0265] The housing 941 substantially surrounds the pressure chamber assembly 920. As the rotary piston 912 is actuated, the generally cylindrical pressure chamber assembly 920 rotates within the housing 941. The housing 941 provides a bearing surface that supports the pressure chamber assembly 920 as it rotates. In some embodiments, the contact between the pressure chamber assembly 920 and the housing 941 can support a load. For example, a load on the connector arm 964 can be transmitted to the pressure chamber assembly 920, to the housing 941 (e.g., via the bearing surface), and continues to the connecting rod 980.

[0266] The connector arm 964 includes a circular sealing groove 990, and the housing 991 includes a corresponding sealing groove 992. When the connector arm 964 is mounted to the pressure chamber assembly 920, the sealing grooves 990 and 992 are aligned. The sealing grooves 990 and 992 accommodate a set of seals 994. As the connector arm 964 pivots relative to the housing 941, the seals 394 substantially prevent external contaminants (e.g., dust, water, dirt, mud, sand) from entering the actuator 900, including the bearing surface between the housing 941 and the pressure chamber assembly 920 and the rotating piston assembly 910. In some embodiments, the sealing arrangement of the actuator 900 is thus suitable for use or immersion in wet, dirty, or other contaminated environments without substantially exposing internal components (e.g., the polished surface of the rotating piston 912) to external contaminants.

[0267] In some embodiments, component 900 may include an internal gear between pressure chamber assembly 920 and connector arm 964. For example, component 900 may include a gear module shaped similarly to those in rotary piston actuator modules 902a-902c and assembleable between rotary piston actuator modules 902a-902c and connector arm 964 to modify the amount of torque or range of motion between the rotary piston actuator modules 902a-902c and connector arm 964. In some embodiments, the gear module may be a planetary gear module.

[0268] In some embodiments, component 900 may include an internal brake or clutch. For example, component 900 may include a clutch module shaped similarly to those in the rotary piston actuator modules 902a-902c and assembleable in component 900 to provide load holding capability. In some embodiments, a gear module may include features that may controllably interfere with gear motion to provide clutch or braking control.

[0269] In some embodiments, the connecting rod arm 982 and the piston end 912 may include anti-rotation features. For example, the connecting rod arm 982 may include extensions that rotatably engage with corresponding extensions of the piston end 912 about boreholes 983, 984. These engaging extensions prevent the connecting rod arm 982 from separating from the piston end 912 (e.g., in the event of a broken interconnected rod). This engagement prevents the piston 910 from rotating relative to the connecting rod arm 982 and reduces the load on the seals located within the pressure chamber assembly 920.

[0270] Figure 10 This is a cross-sectional view of an exemplary fluid delivery shaft 1000. In some embodiments, the fluid delivery shaft 1000 may be... Figure 9 An exemplary fluid delivery shaft 954 is shown. The fluid delivery shaft 1000 is shown axially arranged with a central bore 1003 through a group of modular rotary piston actuators 1002a-1002c (e.g., modular rotary piston actuators 902a-902c). Each modular rotary piston actuator 1002a-1002c includes a fluid port 1005 communicating with a pressure chamber 1007.

[0271] Fluid paths 1010a and 1010b are formed within the fluid delivery shaft 1000. Fluid path 1010a extends between a pair of terminal fluid ports 1012a formed near the axial end of the fluid delivery shaft 1000 and a group of axial fluid ports 1014a formed along the perimeter of the fluid delivery shaft 1000. Each axial fluid port 1014a is substantially aligned with a corresponding one of the modular rotary piston actuators 1002a-1002c.

[0272] The fluid path 1010b extends between a pair of terminal fluid ports 1012b formed near the axial end of the fluid delivery shaft 1000 and a group of axial fluid ports 1014b formed along the periphery of the fluid delivery shaft 1000. Each axial fluid port 1014b is substantially aligned with a corresponding one of the modular rotary piston actuators 1002a-1002c and is radially opposite to the corresponding axial fluid port 1014a.

[0273] A group of seals 1016 are arranged around the perimeter of the fluid delivery shaft 1000. Each fluid port 1005 and the corresponding opposing group of axial fluid ports 1014a and 1014b have a seal 1016a arranged along the length of the fluid delivery shaft 1000 on the first axial side of the axial fluid ports 1014a and 1014b and the fluid port 1005, and a seal 1016b arranged along the length of the fluid delivery shaft 1000 on the second opposing axial side of the axial fluid ports 1014a and 1014b and the fluid port 1005.

[0274] For each modular rotary piston actuator 1002a-1002c, borehole 1003, seals 1016a and 101b, and fluid delivery shaft 1000 define a fluid delivery chamber 1020. This arrangement creates a fluid loop that connects axial fluid ports 1014a and 1014b to a pressure chamber 1007 via fluid port 1005. Thus, terminal fluid ports 1012a and 1012b are in fluid communication with the pressure chamber 1007.

[0275] Each modular rotary piston actuator 1002a-1002c can be assembled about the fluid delivery axis 1000 in two arrangements (e.g., clockwise and counterclockwise). In the illustrated example, modular rotary piston actuators 1002a and 1002c are assembled in a first orientation, and modular rotary piston actuator 1002b is assembled in the opposite orientation. A set of plugs 1030 can be inserted into selected axial fluid ports 1014a and 1014b to select which fluid paths 1011a, 1011b supply fluid to the chamber 1007. In the illustrated example, port 1014b of modular rotary piston actuators 1002a and 1002c is blocked by plug 1030, as is port 1014a of modular rotary piston actuator 1002b. In the illustrated configuration, fluid path 1011a can be pressurized to supply fluid to modular rotary piston actuators 1002a and 1002c, thereby forcing rotation in a first direction, and fluid path 1011b can be pressurized to supply fluid to modular rotary piston actuator 1002b, thereby forcing rotation in the opposite direction.

[0276] Figure 11This is a cross-sectional view of an exemplary fluid delivery shaft 1100. In some embodiments, the fluid delivery shaft 1100 may be... Figure 9 An exemplary fluid delivery shaft 954 is shown. The fluid delivery shaft 1100 is shown axially arranged with a central bore 1103 through a group of modular rotary piston actuators 1102a-1102c (e.g., modular rotary piston actuators 902a-902c). Each modular rotary piston actuator 1102a-1102c includes a fluid port 1105 communicating with a pressure chamber 1107.

[0277] Fluid paths 1110a and 1110b are formed within the fluid delivery shaft 1100. Fluid path 1110a extends between a pair of terminal fluid ports 1112a formed near the axial end of the fluid delivery shaft 1100 and a group of axial fluid ports 1114a formed along the perimeter of the fluid delivery shaft 1100. Each axial fluid port 1114a is substantially aligned with a corresponding one of the modular rotary piston actuators 1102a–1102c.

[0278] The fluid path 1110b extends between a pair of terminal fluid ports 1112b formed near the axial end of the fluid delivery shaft 1100 and a group of axial fluid ports 1114b formed along the periphery of the fluid delivery shaft 1100. Each axial fluid port 1114b is substantially aligned with a corresponding one of the modular rotary piston actuators 1102a-1102c and is radially opposite to the corresponding axial fluid port 1114a.

[0279] A group of seals 1116 are arranged around the perimeter of the fluid delivery shaft 1100. Each fluid port 1105 and the corresponding group of axial fluid ports 1114a and 1114b have a seal 1116a arranged along the length of the fluid delivery shaft 1100 on a first axial side of the axial fluid ports 1114a and 1114b and the fluid port 1105, and a seal 1116b arranged along the length of the fluid delivery shaft 1100 on a second opposing axial side of the axial fluid ports 1114a and 1114b and the fluid port 1105. A third seal 1116c is arranged substantially centrally between each pair of seals 1116a and 1116b.

[0280] For each modular rotary piston actuator 1002a-1002c, borehole 1003, seals 1116a and 111b, and fluid delivery shaft 1100 define a fluid delivery chamber 1120a, and seals 1116c, 111b, and 1100 define a fluid delivery chamber 1120b. This arrangement creates a fluid loop that connects axial fluid ports 1114a and 1114b to a pressure chamber 1107 via fluid port 1105. Thus, terminal fluid ports 1112a and 1112b are in fluid communication with the pressure chamber 1107.

[0281] Each modular rotary piston actuator 1102a-1102c can be assembled about the fluid delivery axis 1100 in two arrangements (e.g., clockwise and counterclockwise). In the example shown, modular rotary piston actuators 1102a and 1102c are assembled in a first orientation, and modular rotary piston actuator 1102b is assembled in the opposite orientation.

[0282] In each modular rotary piston actuator 1102a-1102c, the fluid port 1105 is axially offset from the center of the pressure chamber along the borehole 1103. Thus, when assembled to the fluid delivery shaft 1100 in the first orientation, the fluid port 1105 will be closer to the proximal end and further away from the distal end of the fluid delivery shaft 1100, while in the opposite orientation, the fluid port 1105 will be relatively further away from the proximal end and relatively closer to the distal end.

[0283] When assembled around the fluid delivery axis 1100, depending on the orientation of the modular rotary piston actuators 1102a-1102c, the fluid port 1105 will be aligned between seals 1116a and 1116c or between seals 1116b and 1116c. Thus, depending on the orientation of the modular rotary piston actuators 1102a-1102c, either the fluid delivery chamber 1120a will fluidly connect the fluid path 1111a to chamber 1107, or the fluid delivery chamber 1120b will fluidly connect the fluid path 1111b to chamber 1107. In the example shown, the fluid port 1105 of the modular rotary piston actuators 1102a and 1102c is aligned with the fluid delivery chamber 1120a, and the port 1105 of the modular rotary piston actuator 1102b is aligned with the fluid delivery chamber 1120b. In the illustrated configuration, fluid path 1111a can be pressurized to supply fluid to modular rotary piston actuators 1102a and 1102c, thereby forcing rotation in a first direction, and fluid path 1111b can be pressurized to supply fluid to modular rotary piston actuator 1102b, thereby forcing rotation in the opposite direction.

[0284] Figure 12This is a flowchart of an exemplary process 1200 for performing rotary actuation. In some embodiments, process 1200 may be performed by... Figure 3 -11 rotary piston actuators 300, 400, 600, 700, 800, 900, 1002a-1002c and / or 1102a-1102c are used for execution.

[0285] At 1210, a rotary actuator is provided. An exemplary actuator 1200 includes a first housing defining a first arched chamber, a radially outwardly extending rotor arm, and an arched first piston disposed within the first housing. The first arched chamber includes a first cavity, a first fluid port in fluid communication with the first cavity, an open end, and a first seal disposed around an inner surface of the open end. The arched first piston is configured to reciprocate within the first arched chamber via the open end. The first seal, the first cavity, and the first piston define a first pressure chamber. For example, actuator 600 includes components of a rotary piston 610 and a pressure chamber assembly 630.

[0286] At 1220, pressurized fluid is applied to the first pressure chamber. For example, pressurized fluid may flow through a fluid port (not shown) into pressure chamber 650.

[0287] At 1230, the first piston is forced partially outward from the first pressure chamber to force the rotor arm to rotate in the first direction. For example, a certain volume of pressurized fluid flowing into the pressure chamber 650 will move a similar volume of rotating piston 610, causing the rotating piston 610 to be partially pushed out of the pressure chamber 650, which in turn will cause the rotor arm 640 to rotate clockwise.

[0288] At 1240, the rotary output shaft is rotated in a second direction opposite to the first direction. For example, the rotor arm 640 can be rotated counterclockwise by an external force, such as another mechanism, a load providing torque, a return spring, or any other suitable source of rotary torque.

[0289] At 1250, the first piston is forced partially into the first pressure chamber to force the pressurized fluid out of the first fluid port. For example, a rotating piston 610 can be pushed into the pressure chamber 650, and the volume of the piston end 612 extending into the pressure chamber 650 will displace a similar volume of fluid, causing it to flow out of the fluid port (not shown).

[0290] In some embodiments, exemplary process 100 can be used to provide substantially constant power over the stroke of the connected mechanism. For example, as actuator 600 rotates, the torque delivered to the connected load may remain substantially almost position-independent.

[0291] In some embodiments, the first housing further defines a second arched chamber, the second arched chamber including a second cavity, a second fluid port in fluid communication with the second cavity, and a second seal disposed around an inner surface of an open end. The rotor assembly also includes a second rotor arm, and the rotary actuator further includes an arched second piston disposed in the housing and a second connector. The arched second piston is used for reciprocating motion in the second arched chamber, wherein the second seal, the second cavity, and the second piston define a second pressure chamber, and the second connector connects a first end of the second piston to the second rotor arm. For example, actuator 600 includes a rotary piston 620 and a pressure chamber 631.

[0292] In some embodiments, the second piston may be oriented in the same rotational direction as the first piston. For example, the two pistons 812a and 822a are oriented to operate in a coordinated manner in the same rotational direction. In some embodiments, the second piston may be oriented in a rotational direction opposite to that of the first piston. For example, the rotating piston 610 is oriented to operate in the opposite rotational direction relative to the rotating piston 620.

[0293] In some embodiments, rotating the rotary output shaft in a second direction opposite to the first direction may include applying pressurized fluid to a second pressure chamber and forcing a second piston partially outward from the second pressure chamber to force the rotary output shaft to rotate in a second direction opposite to the first direction. For example, pressurized fluid may be applied to pressure chamber 631 to force rotary piston 620 outward, thereby causing rotor arm 640 to rotate counterclockwise.

[0294] Figure 13 This is a perspective view of an exemplary rotary piston actuator connector portion 1300 with a modular support belt. In some embodiments, the rotary piston actuator connector portion 1300 may be for... Figure 9 Modification of the exemplary rotary piston actuator connector portion 901 to include a group of arched bearing sleeve assemblies 1350a-1350c (e.g., modular support belts).

[0295] In some embodiments, connector 1300 can be used Figure 2 In the multi-axis connector 200, the piston actuator 400 has been replaced by a modular rotary piston actuator 900. Generally, connector 1300 includes one or more rotary piston actuator modules, such as in... Figure 6A Examples of actuators 600, 700, and 800 discussed in the description of -8B.

[0296] The connector 1300 includes three rotary piston actuator modules 1302a-1302c. Generally, within the connector 1300, the rotary piston actuator modules 1302a-1302c are individually replaceable and generally interchangeable. In some embodiments, each module 1302a-1302c may be... Figure 3 - An embodiment of any of the rotary piston actuators 300, 400, 600, 700, or 800 in the -8B series. Figure 9 Any one or any other suitable rotary piston actuator, rotary vane actuator or combination thereof in the rotary piston actuator modules 902a-902c.

[0297] Each of the rotary piston actuator modules 1302a-1302c includes a rotary piston assembly 1310 (e.g., rotary piston assemblies 310, 810, 820, rotary pistons 610, 620, 710, 720, 910) and a housing (not shown), the housing also serving as a pressure chamber assembly (e.g., pressure chamber 320, pressure chamber assemblies 630, 730, 860, 920). Although the exemplary actuator 1300 includes three modules 1302a-1302c, other embodiments may include more and / or fewer numbers of cooperating and opposing rotary piston actuator modules of various configurations.

[0298] exist Figure 13 Each of the exemplary rotary piston assemblies 1310 shown includes a rotary piston 1312 (e.g., rotary piston 912). Each rotary piston 1312 includes a piston end 1316 and one or more connecting arms 1318. The piston end 1316 is formed to have a body having a generally semi-circular arc segment and a substantially smooth surface.

[0299] The pressure chamber assemblies (e.g., pressure chamber 320, pressure chamber assemblies 630, 730, 860, 920) have a generally cylindrical shape. The housing 1341 (e.g., housing 941) is configured as a tubular wall surrounding an inner bore, the size of which is designed to accommodate the pressure chamber assembly. In some embodiments, the housing 1341 may be connected to or integrally formed with a link, such as the exemplary link 980.

[0300] The housing 1341 substantially surrounds the pressure chamber assembly. As the rotary piston 1312 is actuated, the generally cylindrical pressure chamber assembly rotates within the housing 1341. The housing 1341 provides a bearing surface that supports the pressure chamber assembly 920 as it rotates. In some embodiments, the contact between the pressure chamber assembly and the housing 1341 can support loads. For example, a load on the connector arm 1364 can be transmitted to the pressure chamber assembly, to the housing 1341 (e.g., via the bearing surface), and continues to the connecting rod.

[0301] Rotary piston actuator modules 1302a-1302c each include an arched bearing sleeve assembly 1350, each arched bearing sleeve assembly 1350 being formed as a modular wear band. Each arched bearing sleeve assembly 1350 has a generally semi-circular (e.g., crescent-shaped or "C") annular segment. Each arched bearing sleeve assembly 1350 is radially arranged between the corresponding rotary piston 1312 and the inner wall of the housing 1341. Each arched bearing sleeve assembly 1350 contacts the radially outer side 1317 of a corresponding rotary piston 1312 and the inner wall of the housing 1341. As the rotary piston 1312 is actuated, each arched bearing sleeve assembly 1350 provides a bearing surface that contacts and supports the radially outer side 1317 of the rotary piston 1312 as the rotary piston 1312 extends and retracts from the pressure chamber assembly. In some embodiments, the contact between the rotary piston 1312, the arched bearing sleeve assembly 1350, and the housing 1341 can redirect radial loads on the rotary piston 1312.

[0302] For example, as the rotating piston 1312 extends, radial (e.g., outward) forces can be generated. These radial loads can be applied to the piston seals (e.g., Figure 6A , 6B Increased stress is applied to the seals 670, 672, resulting in increased friction and wear, which can reduce performance (e.g., torque output) and lifespan (e.g., time to seal or other component failure). To mitigate the effect of this radial force, the arched bearing sleeve assembly 1350 is contacted by the rotating piston 1312 as the rotating piston 1312 extends. The radial force applied by the rotating piston 1312 is transmitted to the housing 1341 through the arched bearing sleeve assembly 1350, thus providing a force that resists and / or redirects the radial force and at least partially releases the radial stress applied to the seals. As the stress is released, actuator performance (e.g., torque) is maintained or restored.

[0303] Figure 14 This is an exploded view of an exemplary arched bearing sleeve assembly 1400 for a rotary piston actuator. In some embodiments, the arched bearing sleeve assembly 1400 may be... Figure 13 One of the exemplary arched bearing sleeve assemblies 1350 (e.g., modular support strip).

[0304] An exemplary arched bearing sleeve assembly 1400 includes an arched support portion 1410. The arched support portion 1410 has a generally semi-circular (e.g., crescent-shaped or "C") annular segment 1412. Mounting portions 1414a extend radially outward from a first end of the annular segment 1412, and mounting portions 1414b extend radially outward from a second end of the annular segment 1412. Mounting portions 1414a-1414b each have an arched outer surface 1416 configured to substantially conform to the curvature of the inner wall of the housing 1341. The arched support portion 1410 includes a set of holes 1418 configured to receive a set of fasteners, for example, to removably secure the arched support portion 1410 to the inner wall of the housing 1341.

[0305] The exemplary arched bearing sleeve assembly 1400 also includes a liner portion 1450. The liner portion 1450 is generally semi-circular (e.g., crescent-shaped or "C"-shaped) and has a radially outer surface 1452 and a radially inner surface 1454. The radially outer surface 1452 is configured to conform to the inner surface 1420 of the arched support portion 1410, and the radially inner surface 1454 is configured to conform to the radially outer surface of the rotating piston 1312. The liner portion 1450 is semi-concentrically assembled to the arched support portion 1410 such that the radially outer surface 1452 contacts the inner surface 1420.

[0306] In some embodiments, the liner portion 1450 is a replaceable wear-prone component. For example, contact between the rotating piston 1312 and the arched support sleeve portion 1400 can cause wear of the liner portion 1450 over time. The liner portion 1450 can be removed and replaced to maintain the radial load-bearing capacity of the arched bearing sleeve assembly 1400.

[0307] In some embodiments, the liner portion 1450 may include friction-reducing features. For example, the liner portion 1450 may be constructed or coated at least partially with a friction-reducing material (e.g., PTFE). In other examples, the inner surface 1454 may be textured (e.g., with crosshairs) to retain and / or distribute lubricant to the contact points between the inner surface 1454 and the rotating piston 1312.

[0308] Figure 15A and 15B These are cross-sectional side views and exploded views of another exemplary rotary piston actuator 1500 with an arched bearing sleeve assembly. Actuator 1500 includes a rotary piston assembly 1520 and a pressure chamber assembly 1530.

[0309] The rotary piston assembly 1520 includes a rotor shaft 1521. A rotor arm 1522 extends radially from the rotor shaft 1521, and the distal end of the rotor arm 1522 includes a bore 1556 that is substantially aligned with the axis of the rotor shaft 1521 and is sized to receive a connecting pin 1524.

[0310] The actuator includes a rotary piston 1550, which includes a piston end 1552 and one or more connecting arms 1554. The piston end 1552 is formed with a generally semi-circular body having a substantially smooth surface. Each connecting arm 1554 includes a drilled hole 1557 substantially aligned with the axis of the semi-circular body of the piston end 1552 and sized to receive a connecting pin 1524.

[0311] By aligning the connecting arm 1554 with the rotor arm 1522, such that the drilled hole 1556 of the rotor arm 1522 aligns with the drilled hole 1557 of the connecting arm 1554, the rotary piston 1550 can be assembled to the rotor shaft 1521. A connecting pin 1524 can then be inserted through the aligned drilled hole to create a hinged connection between the piston 1550 and the rotor shaft 1521. The connecting pin 1524 is slightly longer than the aligned drilled hole. In the exemplary assembly, a circumferential recess (not shown) surrounding the outer periphery of each end of the aligned drilled hole of each connecting pin 1524 can accommodate a retaining fastener (not shown), such as a snap ring or a spiral ring.

[0312] A rotary piston 1550 is inserted into a corresponding pressure chamber 1510, which is formed as an arched cavity in the pressure chamber assembly 1530. The pressure chamber 1510 includes a seal assembly 1512 surrounding the inner surface of the pressure chamber 1510 at an open end 1513. In some embodiments, the seal assembly 1512 may be a circular or semi-circular sealing geometry held on all sides of a standard seal groove. In some embodiments, commercially available reciprocating piston or cylinder-type seals may be used. For example, commercially available seal types that may already be used in linear hydraulic actuators on current aircraft may present sufficient capability for linear load and position holding applications. In some embodiments, the sealing complexity of the actuator 1500 can be reduced by using standard, such as commercially available semi-circular one-way seal designs used in linear hydraulic actuators. In some embodiments, the seal assembly 1512 may be a one-piece seal.

[0313] In some embodiments of the exemplary actuator 1500, the sealing assembly 1512 may be included as part of the rotating piston 1550. For example, the sealing assembly 1512 may be located near the piston end 1552, opposite the connecting arm 1554, and slide along the inner surface of the pressure chamber 1510 to form a fluid seal as the rotating piston 1550 moves in and out of the pressure chamber 1510. In some embodiments, the sealing assembly 1512 functions as a bearing. For example, the sealing assembly 1512 may provide support for the piston 1550 as it moves in and out of the pressure chamber 1510.

[0314] In some embodiments, actuator 1500 may include a wear member between piston 1550 and pressure chamber 1510. For example, accessible seal assembly 1512 includes a wear ring. In another example, actuator 1500 accessible seal assembly 1512 includes one or more roller (e.g., needle roller) bearings. The wear ring and / or roller bearings may act as a pilot member for piston 1512 and / or as a bearing providing support for piston 1512.

[0315] In the exemplary actuator 1500, when the rotary piston 1550 is inserted through the open end 1513, the sealing assembly 1512 contacts the inner surface of the pressure chamber 1510 and the substantially smooth surface of the piston end 1552 to form a substantially pressure-sealed region within the pressure chamber 1510. The pressure chamber 1510 may include a fluid port (not shown) formed through the pressure chamber assembly 1530 through which pressurized fluid can flow. When a pressurized fluid, such as hydraulic oil, water, air, or gas, is introduced into the pressure chamber 1510, the pressure difference between the interior of the pressure chamber 1510 and the ambient conditions outside the pressure chamber 1510 causes the piston end 1552 to be forced outward from the pressure chamber 1510. As the piston end 1552 is forced outward, the piston 1550 forces the rotary piston assembly 1520 to rotate.

[0316] An exemplary actuator 1500 includes an arched bearing sleeve assembly 1580 removably attached to a pressure chamber 1510. In some embodiments, the arched bearing sleeve assembly 1580 may be Figure 14 An exemplary arched bearing sleeve assembly 1400 is shown. As the piston 1550 extends in the helical direction, it may also have a radially outward force. Without additional radial mechanical support, this radially outward force can increase the load applied to the seal assembly 1512, potentially increasing friction and wear and reducing the performance (e.g., torque capacity) of the actuator 1500. To mitigate this effect, the arched bearing sleeve assembly 1580 provides radial mechanical support for the piston 1550.

[0317] The arched bearing sleeve assembly 1580 has an arched support portion 1582 and an inner liner portion 1584. The inner liner portion 1584 is generally semi-circular (e.g., crescent-shaped or "C"-shaped) and has a radially outer surface 1585 configured to conform to the inner surface 1583 of the arched support portion 1582. The arched support portion 1582 is formed as a generally semi-circular (e.g., crescent-shaped or "C"-shaped) annular segment. The radially inner surface 1586 of the inner liner portion 1584 is configured to conform to the radially outer surface 1551 of the rotating piston 1550. The inner liner portion 1584 is semi-concentrically assembled to the arched support portion 1582 such that the radially outer surface 1551 contacts the inner surface 1586.

[0318] When the arched bearing sleeve assembly 1580 is in place, as the piston 1550 extends in the rotational direction, the radially outer side 1551 of the piston contacts the liner portion 1584. The radially outward force exerted by the rotating piston 1550 causes the rotating piston to contact the liner portion 1584, which transmits the force through the arched support portion 1582 to the pressure chamber assembly 1530. The connection between the pressure chamber assembly 1530 and the arched support portion 1582 causes the arched bearing sleeve assembly 1580 to resist (e.g., redirect, restrain) the outward radial force presented by the rotating piston 1550. In some examples, the arched bearing sleeve assembly 1580 supports loads that would otherwise be supported by the seal assembly 1512, thereby maintaining the performance of the rotating piston actuator 1500 (e.g., torque capacity, seal life).

[0319] In some embodiments of the exemplary actuator 1500, the pressure chamber assembly 1530 may be formed from a single piece of monolithic material, which has no seams except for those formed by the open end 1513 or the fluid port. For example, the pressure chamber 1510, the opening 1513, and the fluid port may be formed by molding, machining, or otherwise as a single piece of material.

[0320] Figure 16 This is a cross-sectional side view of another exemplary arched bearing sleeve assembly 1600. In some embodiments, the arched bearing sleeve assembly 1600 may be... Figure 13 All or a portion of the arched bearing sleeve assemblies 1350, 1400, and / or 1580 in –15B. As previously described, the arched bearing sleeve assembly may include friction-reducing features. For example, the arched bearing sleeve assembly may be constructed or coated with a friction-reducing material (e.g., PTFE), and / or may be textured (e.g., with crosshairs) to retain and / or distribute lubricant to the contact points between the assembly and the rotating piston.

[0321] In the example of the arched bearing sleeve assembly 1600, the grouped recirculating ball (or roller) bearings 1610 are provided with friction-reducing features that can constrain or redirect the outward radial force of the rotating piston 1550. The radially outer surface 1551 of the rotating piston 1550 contacts the sub-assembly of bearings 1610, and as the rotating piston 1550 moves relative to the arched bearing sleeve assembly 1600, the bearings 1610 roll or rotate.

[0322] Figure 17 This is a cross-sectional side view of another exemplary arched bearing sleeve assembly 1700. In some embodiments, the arched bearing sleeve assembly 1700 may be... Figure 13 All or part of the arched bearing sleeve assemblies 1350, 1400 and / or 1580 in -15B. As previously described, the arched bearing sleeve assembly may include friction-reducing features.

[0323] In the example of the arched bearing sleeve assembly 1700, the grouped bearing assembly 1710 provides friction-reducing features that can constrain or redirect the outward radial force of the rotating piston 1701. Each bearing assembly 1710 includes a piston bearing 1712 and a housing bearing 1714. The piston bearing 1712 is arranged such that, as the rotating piston 1701 extends and retracts (e.g., enters and exits the pressure chamber assembly 1530), the piston bearing 1712 will contact the radially outer surface 1702 of the rotating piston 1701. The housing bearing 1714 is arranged such that it will contact both the radially inner surface 1733 of the arched housing 1730 and the piston bearing 1712.

[0324] In use, the rotating piston 1701 contacts the piston bearing 1712. The radially outward force provided by the rotating piston 1701 is transmitted to the piston housing 1712, to the housing bearing 1714, and to the radially inner surface 1733 of the housing 1730. Thus, the housing 1730 can at least partially resist, restrain, and / or redirect the radially outward force of the rotating piston 1701.

[0325] In some embodiments, the rotary piston 1701 may be an exemplary rotary piston 1550, and the housing 1730 may be an exemplary arched support portion 1582. For example, the rotary piston 1550 may contact the piston bearing 1612, and the radially outward force provided by the rotary piston 1550 is transmitted to the piston bearing 1712, to the housing bearing 1714, and to the radially inner surface of the housing 1550. Thus, the arched support portion 1582 may at least partially resist, restrain, and / or redirect the radially outward force of the rotary piston 1550.

[0326] In some embodiments, the rotary piston 1701 may be an exemplary rotary piston 1312, and the housing 1730 may be an exemplary outer housing 1341. For example, the rotary piston 1312 may contact the piston bearing 1712, and the radially outward force provided by the rotary piston 1312 is transmitted to the piston bearing 1712, to the housing bearing 1714, and to the radially inner surface of the outer housing 1341. Thus, the outer housing 1341 may at least partially resist, restrain, and / or redirect the radially outward force of the rotary piston 1312.

[0327] In some embodiments, piston bearing 1712 may have a larger or smaller diameter than housing bearing 1714. For example, in some embodiments, both housing 1730 and rotary piston 1701 may move in the same direction of rotation but not at the same speed. The diameter difference between piston bearing 1712 and housing bearing 1714 can provide speed adaptation functionality between rotary piston 1701 and housing 1730 (e.g., providing gear reduction or amplification). In an example of rotary piston actuator joint portion 1300, housing 1341 and rotary piston 1312 both move in the same direction and have similar angular velocities but different linear velocities. By having multiple bearings (e.g., piston bearing 1712 and housing bearing 1714) in each bearing assembly 1710, the rolling motion of the bearings can be compatible with the motion of both rotary piston 1701 and housing 1730. Furthermore, by having multiple bearings formed with suitable different diameters, the transmission motion of bearing assembly 1710 can make the rolling motion of the bearings compatible with the motion of both rotary piston 1701 and housing 1730.

[0328] Figure 18 This is a flowchart of an exemplary process 1800 for performing rotary actuation of an exemplary rotary piston actuator joint portion having an arched bearing sleeve assembly. In some embodiments, process 1800 can be used in systems having Figure 13 The exemplary arched bearing sleeve assembly 1350 in the example Figure 14 The exemplary arched bearing sleeve assembly 1400 in the example Figure 15A Exemplary arched bearing sleeve assembly 1580 in -15B Figure 16 The exemplary arched bearing sleeve assembly 1600 or Figure 17 An exemplary arched bearing sleeve assembly 1700 is shown in the example.

[0329] At 1810, a first rotary actuator is provided. The rotary actuator includes: a first housing defining a first arched chamber, the first arched chamber including a first cavity having a first open end; and an arched first piston disposed in the first housing for reciprocating motion in the first arched chamber through the first open end, wherein a first seal, the first cavity, and the first piston define a first pressure chamber including part or all of the first arched chamber; and a first arched bearing sleeve assembly having an inner surface configured to be contacted by the radially outer side of the first piston. For example, an exemplary connector 1300 includes three rotary piston actuator modules 1302a-1302c. Each of the rotary piston actuator modules 1302a-1302c includes an arched bearing sleeve portion 1350, which is radially positioned between the piston 1312 and the inner wall of the housing 1341.

[0330] In 1820, the first piston is forced to rotate partially outward from the first pressure chamber. For example, piston 1312 of rotary piston actuator module 1302a can be forced out of the pressure chamber (e.g., Figure 6A -6B pressure chamber 650).

[0331] At 1830, a first radial force is applied to the radially outward side of the piston by the first arched bearing sleeve assembly. For example, as the rotating piston 1312 extends, the radially outward side 1317 contacts the arched bearing sleeve assembly 1350. This contact provides a radial force that constrains the radially outward movement of the rotating piston 1312.

[0332] In some embodiments, process 1800 may include: forcing a first piston portion radially outward, contacting the first piston with a second radial force against a first arched bearing sleeve assembly, transmitting the second radial force to a rotor assembly, and constraining the second radial force via the first arched bearing sleeve assembly. For example, the radially outward force provided by the rotating piston 1312 may be transmitted to the housing 1341 via the arched bearing sleeve assembly 1350. The housing 1341 constrains these forces, including the radial force of the rotating piston 1312.

[0333] In some embodiments, process 1800 may further include providing a second rotary actuator, wherein the rotor assembly is rotatably disposed around the first and second rotary actuators. For example, rotary piston actuator module 1302a may be assembled within housing 1341. Rotary piston actuator module 1302b may also be assembled within housing 1341, housing 1341 being rotatably disposed around both rotary piston actuator modules 1302a and 1302b.

[0334] In some embodiments, process 1800 may further include redirecting a first radial force through a first arched bearing sleeve assembly to a rotor assembly rotatably positioned around the first housing and defining a central bore within the inner wall of the rotor assembly, wherein the first arched bearing sleeve assembly is removably attached to the first housing. For example, a radially outward force provided by the rotating piston 1312 may be transmitted to the housing 1341 through an arched bearing sleeve portion assembly 1350. The housing 1341 constrains these forces, including the radial force of the rotating piston 1312.

[0335] In some embodiments, the first radial force can be redirected through the first arched bearing sleeve assembly to the first housing, wherein the first arched bearing sleeve assembly is removably attached to the first housing. For example, the arched bearing sleeve assembly 1580 is removably attached to the pressure chamber 1510.

[0336] In some embodiments, applying a first radial force to the radially outer side of the piston via the first arched bearing sleeve portion may further include applying the first radial force to a group of bearings that contact the radially outer side of the piston. For example, the radial force of the rotating piston 1550 may be transmitted via the group of bearings 1610. In another example, the radial force of the rotating piston 1701 may be transmitted via the group of bearings assembly 1710.

[0337] While some embodiments have been described in detail above, other modifications are possible. For example, the logical flow depicted in the figures does not require the specific order or sequence shown to achieve the desired result. Furthermore, other steps may be included in the described flow, or steps may be eliminated, and other components may be added to or removed from the described system. In another example, the individual pistons may have square, rectangular, oval, elliptical, figure-eight shaped, or circular cross-sections. Thus, other embodiments are within the scope of the following claims.

Claims

1. A rotary actuator, comprising: Housing, the housing defining: A first arched chamber housing defines a first arched chamber, the first arched chamber including a first cavity, the first cavity defining a first annular segment in a plane between a first open end and a first closed end and having a first fluid port in fluid communication with the first cavity, the annular segment having a first outer radius in the plane and defining an axis perpendicular to the plane, having a first inner radius in the plane about the axis, and having a first middle radius in the plane; A second arched chamber, comprising an inner chamber wall defining a second cavity, the second cavity defining a second annular segment in the plane between a second open end and a second closed end, and having a second fluid port in fluid communication with the second cavity, the second annular segment having a second outer radius from the axis, the second outer radius being greater than a first outer radius and concentric with the first outer radius in the plane about the axis, having a second inner radius in the plane smaller than the first inner radius, and having a second intermediate radius substantially the same as the first intermediate radius, wherein the second arched chamber is oriented in rotation opposite to the first arched chamber about the axis, and wherein at least a portion of the first arched chamber shell is enclosed in the plane within at least a portion of the second arched chamber and defines an arched tubular space between the first arched chamber shell and the inner chamber wall; and An arched actuation space, the arched actuation space defining a third arc segment in the plane around the axis between the first open end and the second open end; A rotor arm configured to rotate along the third arc segment within the arched actuation space; A rotor assembly, the rotor assembly being connected to the rotor arm; An arched first piston, disposed within a first arched chamber housing, is configured for reciprocating motion in the plane and within the first arched chamber via a first open end, wherein a first seal, the first cavity, and the first piston define a first pressure chamber, and a first portion of the first piston contacts the rotor arm; and A tubular arched second piston, disposed within a second arched chamber housing, is configured for reciprocating motion within the second arched chamber via a second open end in the plane and within the arched tubular space. A second seal, the second cavity, and the second piston define a second pressure chamber. A second portion of the second piston contacts the rotor arm. A borehole is formed along the axis, with one or more of the first and second arched chambers in fluid communication with the borehole to apply fluid pressure to the borehole to pressurize one or more of the first and second arched chambers. The borehole accommodates a fluid delivery shaft configured to provide part of a fluid loop between one or more of the first and second arched chambers and a fluid supply external to the rotary actuator. Wherein, at least a portion of the second arched chamber overlaps angularly with the first arched chamber around the axis, and The rotor assembly is rotatable around the housing, and the rotor arm extends radially outward to the rotating output cylinder of the rotor assembly around the axis, and the rotor arm is connected to the rotating output cylinder. Wherein, the first portion of the first piston and the second portion of the second piston contact the angularly opposite sides of the rotor arm. Wherein, the first open end of the first arched cavity is formed in the first end of the housing, and the second open end of the second arched cavity is formed in the second end of the housing, defining an arched actuation space between the inner surface of the rotor assembly and the housing and between the first end and the second end of the housing.

2. The rotary actuator according to claim 1, characterized in that, The first seal is disposed around the inner surface of the first open end and configured to remain stationary relative to the first open end.

3. The rotary actuator according to claim 1, characterized in that, The first seal is disposed around the outer surface of the first piston and configured to remain stationary relative to the first piston.

4. The rotary actuator according to claim 1, characterized in that, The first seal provides load support for the first piston.

5. The rotary actuator according to claim 1, characterized in that, The rotor assembly provides load support for the housing.

6. The rotary actuator according to claim 1, characterized in that, The housing is formed as a single-piece housing.

7. The rotary actuator according to claim 1, characterized in that, The first seal is a single-piece seal.

8. The rotary actuator according to claim 1, characterized in that, The cross-section of the first piston is solid.

9. The rotary actuator according to claim 1, characterized in that, The cross-section of at least one of the first piston and the second piston is at least partially hollow.

10. The rotary actuator according to claim 1, characterized in that, The cross-section of the first piston has one of the following shapes: rectangular, oval, elliptical, figure-eight, or circular.

11. The rotary actuator according to claim 10, characterized in that, The rectangle is a square.

12. A rotational actuation method, comprising: A rotary actuator is provided, the rotary actuator comprising: Housing, the housing defining: A first arched chamber housing defines a first arched chamber, the first arched chamber including a first cavity, the first cavity defining a first annular segment in a plane between a first open end and a first closed end and having a first fluid port in fluid communication with the first cavity, the annular segment having a first outer radius in the plane and defining an axis perpendicular to the plane, having a first inner radius in the plane about the axis, and having a first middle radius in the plane; A second arched chamber, comprising an inner chamber wall defining a second cavity, the second cavity defining a second annular segment in the plane between a second open end and a second closed end, and having a second fluid port in fluid communication with the second cavity, the second annular segment having a second outer radius from the axis, the second outer radius being greater than a first outer radius and concentric with the first outer radius in the plane about the axis, having a second inner radius in the plane smaller than the first inner radius, and having a second intermediate radius substantially the same as the first intermediate radius, wherein the second arched chamber is oriented in rotation opposite to the first arched chamber about the axis, and wherein at least a portion of the first arched chamber shell is enclosed in the plane within at least a portion of the second arched chamber and defines an arched tubular space between the first arched chamber shell and the inner chamber wall; and An arched actuation space, the arched actuation space defining a third arc segment in the plane around the axis between the first open end and the second open end; A rotor arm configured to rotate within the actuation space along the third arc segment; A rotor assembly, the rotor assembly being connected to the rotor arm; An arched first piston, disposed within a first arched chamber housing, is configured for reciprocating motion in the plane and within the first arched chamber via a first open end, wherein a first seal, the first cavity, and the first piston define a first pressure chamber, and a first portion of the first piston contacts the rotor arm; and A tubular arched second piston is disposed in a second arched chamber housing for reciprocating motion in the second arched chamber via a second open end in the plane and in the arched tubular space, wherein a second seal, a second cavity, and a second piston define a second pressure chamber, and a second portion of the second piston contacts the rotor arm; A borehole is formed along the axis, with one or more of the first and second arched chambers in fluid communication with the borehole to apply fluid pressure to the borehole to pressurize one or more of the first and second arched chambers. The borehole accommodates a fluid delivery shaft configured to provide part of a fluid loop between one or more of the first and second arched chambers and a fluid supply external to the rotary actuator. Pressurized fluid is applied to the first pressure chamber; This forces the first piston partially outward from the first pressure chamber, thereby forcing the rotor arm to move in a first direction; Rotate the rotor arm in a second direction opposite to the first direction; and This forces the first piston partially into the first pressure chamber, thereby forcing the pressurized fluid out of the first fluid port. Wherein, at least a portion of the second arched chamber overlaps angularly with the first arched chamber around the axis, and The rotor assembly is rotatable around the housing, and the rotor arm extends radially outward to the rotating output cylinder of the rotor assembly around the axis, and the rotor arm is connected to the rotating output cylinder. Wherein, the first portion of the first piston and the second portion of the second piston contact the angularly opposite sides of the rotor arm. Wherein, the first open end of the first arched cavity is formed in the first end of the housing, and the second open end of the second arched cavity is formed in the second end of the housing, defining an arched actuation space between the inner surface of the rotor assembly and the housing and between the first end and the second end of the housing.

13. The method according to claim 12, characterized in that, Rotating the rotor arm in a second direction opposite to the first direction includes: Apply pressurized fluid to the second pressure chamber; and This forces the second piston partially outward from the second pressure chamber, thereby forcing the rotor arm to move in a second direction opposite to the first direction.

14. The method according to claim 12 or 13, characterized in that, Forcing the first piston partially outward from the first pressure chamber to force the rotor arm to move in the first direction further includes moving the rotor arm in the first direction with a torque that is substantially constant over the stroke.

15. An arm of a machine device, the arm comprising: First arm section; Second arm section; as well as A joint portion of the first arm portion is pivotally connected to a joint portion of the second arm portion, the joint portion including a rotary actuator comprising: Housing, the housing defining: A first arched chamber housing defines a first arched chamber, the first arched chamber including a first cavity, the first cavity defining a first annular segment in a plane between a first open end and a first closed end and having a first fluid port in fluid communication with the first cavity, the annular segment having a first outer radius in the plane and defining an axis perpendicular to the plane, having a first inner radius in the plane about the axis, and having a first middle radius in the plane; A second arched chamber, comprising an inner chamber wall defining a second cavity, the second cavity defining a second annular segment in the plane between a second open end and a second closed end, and having a second fluid port in fluid communication with the second cavity, the second annular segment having a second outer radius from the axis, the second outer radius being greater than a first outer radius and concentric with the first outer radius in the plane about the axis, having a second inner radius in the plane smaller than the first inner radius, and having a second intermediate radius substantially the same as the first intermediate radius, wherein the second arched chamber is oriented in rotation opposite to the first arched chamber about the axis, and wherein at least a portion of the first arched chamber shell is enclosed in the plane within at least a portion of the second arched chamber and defines an arched tubular space between the first arched chamber shell and the inner chamber wall; and An arched actuation space, the arched actuation space defining a third arc segment in the plane around the axis between the first open end and the second open end; A rotor arm configured to rotate within the actuation space along the third arc segment; A rotor assembly, the rotor assembly being connected to the rotor arm; An arched first piston, disposed within a first arched chamber housing, is configured for reciprocating motion in the plane and within the first arched chamber via a first open end, wherein a first seal, the first cavity, and the first piston define a first pressure chamber, and a first portion of the first piston contacts the rotor arm; and A tubular arched second piston, disposed within a second arched chamber housing, is configured for reciprocating motion within the second arched chamber via a second open end in the plane and within the arched tubular space. A second seal, the second cavity, and the second piston define a second pressure chamber. A second portion of the second piston contacts the rotor arm. A borehole is formed along the axis, with one or more of the first and second arched chambers in fluid communication with the borehole to apply fluid pressure to the borehole to pressurize one or more of the first and second arched chambers. The borehole accommodates a fluid delivery shaft configured to provide part of a fluid loop between one or more of the first and second arched chambers and a fluid supply external to the rotary actuator. Wherein, at least a portion of the second arched chamber overlaps angularly with the first arched chamber around the axis, and The rotor assembly is rotatable around the housing, and the rotor arm extends radially outward to the rotating output cylinder of the rotor assembly around the axis, and the rotor arm is connected to the rotating output cylinder. Wherein, the first portion of the first piston and the second portion of the second piston contact the angularly opposite sides of the rotor arm. Wherein, the first open end of the first arched cavity is formed in the first end of the housing, and the second open end of the second arched cavity is formed in the second end of the housing, defining an arched actuation space between the inner surface of the rotor assembly and the housing and between the first end and the second end of the housing.

16. The arm according to claim 15, characterized in that, The rotor assembly is fixed to or integral with the first arm portion.

17. The arm according to claim 15 or 16, characterized in that, The housing is fixed to or integral with the second arm portion.

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