Multi-Chamber Rotary Piston Actuator for Constant Torque Motion
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Solution Overview
Problem
Existing linear and rotary hydraulic actuators in heavy equipment face challenges in providing increased actuation speed, wide ranges of motion, efficient fluid power usage, and ease of maintenance, while also being susceptible to contamination and varying torque and motion characteristics across their range.
Innovation Solution
The development of a rotary piston actuator assembly that uses curved pressure chambers and pistons to provide compact, lightweight, and resistant to contamination, with sealed arrangements that allow for greater ranges of motion and more constant angular velocity, incorporating multi-axis fluid actuators for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If linear hydraulic actuators are used in heavy equipment, then they can provide linear motion and force, but they suffer from limited actuation speed, narrow ranges of motion, and poor fluid power efficiency
Solution Approach 1:
The patent inverts the conventional linear actuator approach by using rotary pistons that move in curved paths within arcuate chambers. Instead of converting rotary motion to linear motion through linkages, the system directly generates rotary motion through fluid pressure acting on curved piston surfaces, achieving higher actuation speeds and better fluid power efficiency
Solution Approach 2:
The patent employs arcuate (curved) chambers and curved piston surfaces to enable rotary motion. The curved geometry allows fluid pressure to directly generate rotational force, eliminating the need for linear-to-rotary conversion mechanisms and improving both actuation speed and fluid power efficiency
2Power
If rotary hydraulic actuators are used for continuous inertial loading, then they can provide continuous motion without load holding, but they do not scale well to provide the power-to-weight ratios and stiffness expected in heavy equipment
Solution Approach 1:
The patent uses nested concentric pistons where smaller pistons are positioned within larger ones, all sharing a common rotational axis. This nested configuration allows multiple pistons to contribute to the same rotational output, increasing power density and power-to-weight ratio while maintaining a compact structure suitable for heavy equipment
Solution Approach 2:
The rotary piston actuator design provides multiple functions: it delivers continuous inertial loading capability like traditional rotary actuators, while also providing load holding capability and high power-to-weight ratio like heavy equipment actuators. The multi-functional design allows it to scale effectively across different heavy equipment applications
3Reliability
If traditional hydraulic actuators are used, then they can provide force and motion, but they are susceptible to contamination and require frequent maintenance
Solution Approach 1:
The patent employs flexible seals and sealing rings that create effective barriers between fluid chambers and the external environment. These sealing elements prevent contamination from entering the actuator while allowing the flexible membrane structure to accommodate pressure variations and thermal expansion, reducing maintenance requirements
Solution Approach 2:
The actuator design incorporates sealed chambers that create a protected internal environment, isolating the hydraulic fluid and internal components from external contamination sources. This sealed configuration reduces susceptibility to contamination and extends maintenance intervals
4Stability of the object's composition
If linear actuators with lever arms are used to achieve rotary motion, then they can provide rotary actuation, but they have varying torque and motion characteristics across their range
Solution Approach 1:
The patent uses arcuate chambers with curved geometries that are specifically designed to produce constant angular velocity throughout the piston's stroke. The curved path of the piston within the arcuate chamber ensures uniform rotational motion, eliminating the varying torque characteristics associated with linear actuators and lever arm mechanisms
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The rotary piston actuator assembly offers enhanced positional holding, power/torque characteristics, resistance to contamination, and easier maintenance, with greater ranges of motion and more consistent angular velocity, addressing the limitations of existing actuators.
Implementation Method 1
curved pressure chambers and pistons to provide compact, lightweight, and resistant to contamination
Implementation Method 2
fluid actuator, a method of fluid actuation
Implementation Method 3
sealed arrangements that allow for greater ranges of motion
Data Source
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AI summary
The subject matter of this specification can be embodied in, among other things, a fluid actuator including a housing defining a first chamber having a first cavity and a first open end, a first piston assembly including a tubular first piston defining a second chamber having a second cavity and a second open end, disposed in said 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, and a second piston assembly having an second piston disposed in said 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.