Rotary expansible chamber devices – Positively actuated abutment – Fluid biased
Reexamination Certificate
1999-11-12
2001-11-27
Lopez, F. Daniel (Department: 3745)
Rotary expansible chamber devices
Positively actuated abutment
Fluid biased
C418S251000
Reexamination Certificate
active
06322341
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
Not Applicable.
BACKGROUND OF THE INVENTION
The present invention relates generally to a rotary actuator and, more particularly, to a fluid-operated or hydraulic rotary actuator for integration into a mechanical component or system.
One field or application wherein the present inventive rotary actuator is particularly adapted is in the design of articulated robots for industrial use. Rotary power transmission equipment such as actuators and motors have been used to provide the primary component of a joint in these articulated robots. Conventional equipment used in these applications include rotary vane actuators, planetary helical rotary actuators, axial vane motors, rack and pinion rotary actuators, radial piston hydraulic motors, and a variety of hydraulic motor driven gear box combinations. In many applications, it is desirable for such equipment to be compact in size, lightweight, responsive, and capable of achieving precision rotary motion control. Since fluid-powered (e.g., hydraulic) rotary actuators may be designed to feature physical and operational attributes which are consistent with these desirable aspects, such actuators are often preferred to electric motors.
SUMMARY OF THE INVENTION
It is one of a several objects of the invention to provide an improved rotary actuator having one or more desirable features or capabilities.
It is another object of the invention to provide an improved fluid-powered rotary actuator.
It is yet another object of the invention to provide an improved hydraulic rotary actuator, such as one particularly adapted for integration into a joint of an articulated robot.
It will be shown that a rotary actuator of the present invention may be particularly useful in applications where a rotary actuator or low speed, high torque hydraulic motor is currently used. Further, certain embodiments of the inventive actuator are particularly appropriate for use in new and existing applications wherein precision rotary motion control and/or weight or volume constraints are critical. Applications include use in robotic manipulators and remotely operated systems provided in environments not particularly suitable for human occupancy. Embodiments of the present invention may provide, among other attributes, high torque and load capacity with respect to weight, an ability to tolerate harsh environments, reliability and improved response to control system input. It will also be shown that the rotary actuator design described herein lends itself to utilization of corrosion resistant materials in a water tight configuration.
In one aspect of the invention, a rotary actuator assembly is provided having a rotatable drive assembly characterized by a longitudinal axis. The drive assembly includes an output shaft having a coupling end for rotatably engaging a workpiece, and a rotor disposed concentrically about the longitudinal axis and rotatable in a designated angular direction to drive rotation of the output shaft. The rotor has a rotor radial surface that includes at least one (preferably a plurality) radially extending rotor vane. The actuator also has a stator assembly with a stator radial surface having at least one (preferably a plurality) radially extending stator vane. This stator assembly is disposed about the longitudinal axis such that the rotor and the stator are aligned or positioned to form a pressure chamber defined, at least partially, by the separation between the stator radial surfaces. Thus, the rotor vane is substantially sealingly engageable with the stator radial surface and the stator vane is substantially sealingly engageable with the rotor radial surface to form at least a first pressure cavity of the pressure chamber and a second pressure cavity of the pressure chamber. These pressure cavities are bounded, at least partially, by a rotor vane, a stator vane and the radial surfaces of the stator and rotor. The second pressure cavity is disposed adjacent the rotor vane in the designated angular direction and the second pressure cavity is disposed adjacent the rotor vane in the opposite angular direction.
The actuator may further include a fluid pressure circuit disposed in fluid communication with the first and second pressure cavities to produce a differential pressure acting on the rotor vane thereby rotatably moving the output shaft assembly in the angular direction. In such an actuator, the rotor assembly is substantially continuously rotatable up to and/or beyond about 360 degrees relative to the stator assembly. Alternatively, the rotor may be continuously rotatable relative to the stator assembly through a plurality of cycles.
One rotary actuator described herein is a rotor-stator vane type hydraulic rotary actuator featuring continuous rotation capabilities and stator vane operation that is synchronized with rotation of the rotor. In one aspect of the present invention, the actuator provides continuous rotation beyond 360 degrees. Such an actuator is particularly advantageous for use in powering the joints of a man-rated, underwater robotic manipulator system. For example, the inventive actuator may be used in a trainer/simulator that mimics a space station facility remote manipulator system and which may be provided in an underwater training facility. In conjunction with a servo hydraulic control system, such an actuator provides smooth, continuous rotary motion, while acting against externally applied torsional, bending, shear and axial loads. Preferably, the actuator is rotatable through a plurality of cycles.
Alternatively, a hydraulic rotary actuator assembly according to the invention has a rotatable drive assembly with a longitudinal axis and a stator assembly. The rotatable drive assembly includes an output shaft having a coupling end for rotatably engaging a workpiece, and a rotor disposed concentrically about the longitudinal axis and rotatable to drive rotation of the output shaft. Further, the rotor has an outside radial surface that includes at least one radially extending flange or rotor vane. The stator assembly is disposed concentrically about the rotor and has at least one radially movable stator vane that is sealingly engageable with the outside radial surface of the rotor throughout angular movement (e.g., rotation through a plurality of cycles) of the rotor. Sealing engagement between the stator vane and the outside radial surface forms at least a first pressure cavity and a second pressure cavity, wherein the first and second pressure cavities are sealingly bounded by at least the rotor vane and the stator vane.
Further, a fluid pressure system may be provided in fluid communication with the first and second pressure cavities to produce a differential pressure acting on one side of the rotor vane, thereby rotatably moving the output shaft assembly. In one aspect of the invention, the rotor assembly of the actuator is continuously movable or rotatable in one direction relative to the stator assembly (i.e., continuously beyond 360 degrees without pause or change of direction). Each of the stator vanes are disposed adjacent and is movably responsive to a variable control element such as a variable pressure cavity or force transmitting mechanical member. The variable control element is operable by a stator vane control circuit system (e.g, a system including one or more solenoid valves and/or pressure fluid accumulator) to change the position of the vanes relative to the stator and in synchronization with the rotation of the rotor. The stator vane control circuit may be operably interconnected (and thus synchronized with) the fluid pressure system. For example, the control circuit may be provided with solenoid operated, multi-port cartridge valves fluidly interconnected to stator pockets retaining the stator vanes, with a servo-hydraulic control system of the fluid pressure system.
Sealing engagement between components may be provided by a seal assembly having an outwardly facing seal material and a seal energizer disposed behind the seal material. Several variations of s
Johnson Engineering Corp.
Lopez F. Daniel
Rossi & Associates
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