Multi-Chamber Rotary Piston Actuator for Compact High-Torque Motion
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Solution Overview
Problem
Existing rotary hydraulic actuators in heavy equipment applications face challenges in providing increased actuation speed, wide ranges of motion, efficiency in fluid power usage, and ease of maintenance, while also being compact and lightweight, with limited scalability to meet the power-to-weight ratios and field-serviceability requirements.
Innovation Solution
A rotary piston actuator assembly featuring an arcuate-shaped piston and bearing sleeve assembly, which allows for reciprocal movement within an arcuate chamber, providing a compact and lightweight design with improved torque-to-weight ratios and field-serviceability, and utilizing a fluid delivery shaft for efficient fluid communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If linear hydraulic actuators are used in heavy equipment applications, then they provide reliable power transmission, but they fail to achieve increased actuation speed, wide ranges of motion, and efficiency in fluid power usage
Solution Approach 1:
The invention transitions from linear reciprocating motion to continuous rotary motion, allowing the piston to dynamically rotate within the cylinder rather than moving back and forth. This dynamic motion pattern enables continuous fluid power utilization without the idle periods inherent in linear actuators, achieving both increased actuation speed and improved energy efficiency.
Solution Approach 2:
The rotary piston completes continuous rotational cycles, with fluid being continuously supplied and discharged in a periodic manner that maintains constant motion. This periodic action eliminates the start-stop nature of linear actuators, enabling sustained high-speed operation with consistent fluid power efficiency throughout the rotation cycle.
2Power
If rotary hydraulic actuators are used for continuous inertial loading, then they provide smooth operation, but they do not scale well to provide the power-to-weight ratios and field-serviceability features expected in heavy equipment applications
Solution Approach 1:
The rotary piston actuator is designed as a modular unit with distinct components (cylinder, piston, seals, fluid ports) that can be independently serviced or replaced. The removable piston assembly and accessible seal replacement procedures enable field serviceability without requiring complete disassembly, reducing maintenance complexity while maintaining high power-to-weight ratios.
Solution Approach 2:
The actuator incorporates self-lubricating bearing surfaces and wear-resistant materials that reduce the frequency and complexity of maintenance interventions. The design allows operators to perform basic maintenance tasks such as seal replacement without specialized tools or extensive training, improving field-serviceability while preserving the compact, high-power-density design.
3Force
If conventional actuator designs are used, then they provide adequate performance, but they fail to achieve compact and lightweight design with improved torque-to-weight ratios
Solution Approach 1:
The rotary piston and cylinder are designed with curved, arc-shaped profiles that optimize the distribution of forces during rotation. The arc-shaped piston path and curved sealing surfaces enable more efficient force transmission from fluid pressure to rotational torque, achieving higher torque-to-weight ratios without increasing actuator mass.
Solution Approach 2:
The actuator employs a compact nested arrangement where the rotary piston rotates within the cylindrical housing, and fluid channels are integrated into the piston and cylinder walls. This nested design minimizes the overall footprint and weight of the actuator while maximizing the torque-generating capacity through optimized fluid pressure application.
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 solution enables enhanced actuation speed, wider ranges of motion, and improved efficiency in fluid power usage, while maintaining a compact and lightweight design, addressing the limitations of existing rotary hydraulic actuators in heavy equipment applications.
Implementation Method 1
pressurized fluid is supplied to a rotary piston actuator... the pressurized fluid is supplied to a first rotary piston actuator... urging the first piston partially outward from the first pressure chamber
Implementation Method 2
a first arcuate bearing sleeve assembly having an inner surface configured to be contacted by a radially outer side of the first piston
Implementation Method 3
a fluid delivery shaft having an elongated body... in fluid communication with the first cavity
Data Source
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.