Transmission Trim Ring Brake for Constant Output Speed
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Solution Overview
Problem
Conventional mechanical power transmission systems, such as those used in aircraft electrical power systems, face limitations in providing a relatively constant output rate over a wide range of input speeds, especially when the input speed varies significantly, and are often complex and difficult to implement.
Innovation Solution
A transmission assembly with a trim ring, planets, and an overrunning clutch, where a brake controls the trim ring's rotation speed to maintain output speed within a predetermined range by shifting between stationary and rotating conditions, allowing for a normalized output speed range of 1 to 2.3 over an input speed range of 1 to 5, and optionally using a continuously variable transmission for constant output speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional constant speed drives are used to regulate variable speed input to constant output, then output speed stability is improved, but input speed range is limited
Solution Approach 1:
The patent applies dynamics by making the trim ring rotatable at variable speeds between 0 and input speed, allowing the transmission to adapt to different input speed conditions. The brake mechanism dynamically adjusts the trim ring's rotation state (stationary, partial rotation, or full rotation with input), enabling the system to maintain stable output across a broader input speed range than conventional constant speed drives.
2Power
If planetary gear arrangements are used to transmit mechanical power, then power transmission capability is improved, but device complexity increases
Solution Approach 1:
The patent segments the planetary gear system into distinct functional components: an arm with mounted planets, a separate rotatable trim ring, and a brake mechanism. This segmentation allows independent control of the trim ring's rotation state, simplifying the overall system architecture while maintaining power transmission capability. The brake mechanism specifically targets the trim ring, enabling precise control without complex interactions throughout the entire gear system.
Solution Approach 2:
The trim ring serves as an intermediary element between the input (arm) and output (ring gear) of the planetary system. By controlling the trim ring's rotation through the brake, the system can adjust the effective gear ratio and maintain stable output without requiring complex control mechanisms throughout the entire transmission. The overrunning clutch also acts as an intermediary, allowing relative rotation between the arm and trim ring during transitions.
3Measurement precision
If brake torque is actively controlled to maintain output speed, then output speed control precision is improved, but energy consumption increases
Solution Approach 1:
The overrunning clutch enables the trim ring to freely rotate with the input during steady-state operation, eliminating the need for continuous brake application and reducing energy consumption. The brake only activates when speed control is needed or during transitions between different operating conditions. This self-service mechanism allows the system to maintain precision output speed control while minimizing active brake control and associated energy use during normal operation.
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 mechanical power transmission with a significantly improved input range while maintaining a relatively constant output speed and acceleration, addressing the limitations of conventional systems and simplifying the transmission design.
Implementation Method 1
An overrunning clutch operatively connects the arm to the trim ring to allow relative rotation of the arm and trim ring in the first condition and when shifting between the first and second conditions, and to allow common rotation of the arm and trim ring in the second condition, preventing rotation speed of the trim ring exceeding input rotation speed of the arm
Implementation Method 2
A brake is operatively connected to the trim ring for controlling rotation of the trim ring. The brake is configured and adapted to shift the transmission assembly from a first condition in which the trim ring is held stationary relative to the arm, and a second condition in which the trim ring and arm rotate together.
Data Source
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AI summary
A transmission (100) for providing mechanical power from an input (104) includes a transmission assembly having an arm (106) configured and adapted to be connected to a mechanical input for rotation at an input speed. A first planet (108) is rotatably mounted to a first end of the arm. A trim ring (110) operatively contacts the first planet for mutual rotation therewith. A brake (112) is operatively connected to the trim ring for controlling rotation of the trim ring. A second planet (114) is rotatably mounted to a second end of the arm. The second planet operatively contacts the first planet for mutual rotation therewith. An output ring (116) operatively contacts the second planet for mutual rotation therewith to rotate at an output speed based on an input speed of the arm and a trim speed of the trim ring.