Rocker Link CVP Shifting Mechanism for Lower Shift Effort
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Solution Overview
Problem
Existing continuously variable planetary (CVP) transmissions face challenges in efficiently adjusting speed ratios under high input torque and speed conditions, requiring significant manual or electromechanical effort, and struggle with static shifting and reverse operations.
Innovation Solution
A CVP transmission mechanism utilizing a rocker link and rocker gear system, which includes a rotatable carrier, rocker link, and shift driver to adjust skew angles on planet axles, reducing shift effort through a lever ratio increase and positive feedback loop, enabling efficient dynamic and static shifting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a conventional speed ratio adjusting mechanism is used in a CVP transmission, then the structure is simpler, but the shift effort required is excessive under high input torque and speed conditions
Solution Approach 1:
The patent implements a dynamic adjusting mechanism where the rocker link can rotate about an eccentric pin, creating a variable lever ratio that adapts during the shifting process. This dynamic configuration allows the mechanism to provide higher mechanical advantage when needed, reducing shift effort under high torque conditions while maintaining controllability throughout the adjustment range.
Solution Approach 2:
The rocker link serves as an intermediary element between the shift driver and the planet axles. By introducing this intermediate component with rotational freedom about the eccentric pin, the system transforms the direct force transmission into a leveraged motion, effectively reducing the effort required at the shift driver while maintaining control over the planet axle adjustment.
2Adaptability or versatility
If existing adjusting mechanisms are used, then the device complexity is lower, but the system cannot efficiently handle static shifting and reverse operations
Solution Approach 1:
The adjustable skew angle mechanism, enabled by the rocker link's rotation about the eccentric pin, provides dynamic adaptability that allows the system to handle various operating conditions including static shifting and reverse operations. This dynamic configuration adjustment capability enables versatile shifting performance without requiring multiple separate mechanisms.
3Force
If a direct connection between shift driver and planet axles is used, then the mechanism is simpler, but the lever ratio is insufficient to reduce shift effort
Solution Approach 1:
The patent employs an eccentric pin configuration that creates a curved, non-linear motion path for the rocker link. This curved geometry effectively increases the lever ratio during the shifting process, providing greater mechanical advantage and reducing shift effort compared to a straight-line direct connection.
Solution Approach 2:
The rocker link acts as an intermediary that introduces a leveraged motion between the shift driver and planet axles. By positioning the rocker link to rotate about the eccentric pin, the system creates a mechanical advantage that amplifies the force applied at the shift driver, effectively reducing the effort needed to adjust speed ratios under high torque conditions.
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 mechanism reduces shift effort by approximately 50% compared to existing systems, allowing for smooth and efficient speed ratio adjustments under high torque and static conditions, including rollback operations.
Implementation Method 1
a rocker gear rotatably coupled to a second end of the rocker link; and a shift driver engaged with the rocker gear. The rocker gear may comprise a journal rotatably coupled to the input carrier, and an eccentric pin grounded to the timing plate
Implementation Method 2
the rocker link is rotatably coupled to the second end of each planet axle by a spherical joint
Data Source
AI summary
A speed ratio adjusting mechanism for a continuously variable planetary (CVP) drive comprises a shift driver engaging a rocker gear, the rocker gear being rotatably coupled to an input carrier using a journal and rotatably coupled to a rocker link with a revolute joint. The rocker link is coupled to an end of a planet axle, wherein rotation of the shift driver rotates the rocker gear to translate the rocker link, imparting a skew angle on the planet axle to cause a change in tilt angle.