Moving Seal Carrier Rotary Actuator for Constant Torque
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Solution Overview
Problem
Current rotary hydraulic actuators face challenges in providing constant torque over a wide range of angles and loads, leading to inefficiencies and torque loss due to cross-vane leakage, radial deformations, and increased friction, which are not well-suited for heavy-duty applications requiring high power-to-weight ratios and field-serviceability.
Innovation Solution
The design incorporates a rotary piston actuator with a pressure chamber assembly and seal carrier assembly that accommodates radial distortions, using a pair of opposing rotary pistons and a load bearing assembly to maintain constant torque delivery by minimizing friction and mechanical interference, and a spring member for load bearing without torque loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional rotary hydraulic actuators are used, then rotary motion is achieved, but torque varies over the range of stroke and energy efficiency decreases
Solution Approach 1:
The piston is designed with a dynamic arcuate path that adjusts its position relative to the rotor center based on the rotational angle. This dynamic geometry ensures that the moment arm remains substantially constant throughout the stroke, maintaining constant torque delivery and energy efficiency from zero to full stroke.
Solution Approach 2:
The invention changes the geometric parameters of the piston path from a conventional circular arc to a specifically designed arcuate path with adjusted radius and center position. This parameter modification enables the piston to maintain optimal alignment with the force vector, ensuring constant torque output and preventing energy loss.
2Power
If conventional rotary actuators are used, then rotary motion is achieved, but friction and mechanical interference increase leading to torque loss
Solution Approach 1:
The dynamic piston design maintains optimal clearance between the piston and rotor housing throughout the stroke by adjusting the piston's arcuate path. This dynamic positioning minimizes friction and mechanical interference, preventing torque loss while maintaining constant torque delivery.
3Reliability
If rotary actuators with load holding capability are designed, then holding capacity is improved, but device complexity increases
Solution Approach 1:
The hydraulic system provides inherent load holding capability through the trapped fluid pressure in the sealed chambers. The piston's position is maintained by the balanced fluid pressures without requiring additional mechanical locking mechanisms, brakes, or complex holding devices, thus achieving reliability without increased complexity.
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
This solution enables a rotary piston actuator to provide substantially constant torque over a wide range of angles and loads, reducing weight and cost while maintaining efficiency and field-serviceability, making it suitable for heavy-duty applications.
Implementation Method 1
A rotary piston actuator includes a rotor and a piston that moves in an arcuate path from a first position to a second position as fluid pressure increases
Implementation Method 2
The seal carrier assembly is configured to accommodate radial distortions of the piston
Data Source
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AI summary
The subject matter of this specification can be embodied in, among other things, a rotary actuator that includes a housing defining a first arcuate chamber portion and comprising a first cavity, a first open end, a first seal carrier assembly defining a second arcuate chamber portion and comprising a second cavity in fluid communication with the first cavity, a first piston seal, a second open end, and a third open end opposite the second open end, a first face seal in sealing contact with the housing proximal to the first open end and the second open end, a rotary output assembly, and an arcuate-shaped first piston disposed in said housing for reciprocal movement in the first arcuate chamber portion and in the second arcuate chamber portion.