Valve Timing Adjuster Planet Gear Support
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Solution Overview
Problem
Existing valve timing adjusting apparatuses face issues with durability and noise generation due to tilting and wobbling of rotatable bodies, leading to potential wearing and damage, caused by clearance between the crankshaft and camshaft components.
Innovation Solution
A valve timing adjusting apparatus with a differential gear mechanism that includes a planet gear system, where the driven-side rotatable body supports the driving-side rotatable body from a radially inner side, limiting axial movement and engagement, and utilizing a sun-and-planet motion to adjust valve timing, thereby reducing tilting and wobbling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If clearance is provided between the crankshaft side rotatable body and the camshaft to permit relative rotation, then the valve timing adjusting apparatus achieves the required rotational freedom, but the crankshaft side rotatable body tilts and wobbles, causing wearing, seizing, noise, and potential damage
Solution Approach 1:
A spherical member is introduced as an intermediary between the crankshaft side rotatable body and the camshaft. This spherical member fits into a spherical hole in the crankshaft side rotatable body and engages with the camshaft, acting as a mediator that permits relative rotation while constraining tilting and wobbling movements, thereby resolving the contradiction between rotational freedom and reliability
Solution Approach 2:
The support structure changes from a conventional clearance-based rotational joint to a spherical constraint mechanism. By changing the geometric parameters and constraint conditions through the spherical member, the system achieves both rotational capability and stability, preventing the tilting and wobbling that would otherwise occur with simple clearance-based rotation
2Device complexity
If a differential gear mechanism with planet gear is used to change relative rotational phase, then compact design with large speed reducing ratio is achieved, but the crankshaft side rotatable body becomes susceptible to tilting and wobbling under gravity and oscillating torque
Solution Approach 1:
The spherical member serves as a stabilizing intermediary that counteracts the destabilizing effects of gravity and oscillating torque on the differential gear mechanism. By constraining the crankshaft side rotatable body at the support position, the spherical member prevents tilting and wobbling that would otherwise compromise the stability of the compact differential gear design
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 enhances durability and reduces noise and damage by limiting tilting and wobbling, ensuring accurate valve timing adjustment over a long period.
Implementation Method 1
a planet gear, which includes a first outer gear and a second outer gear. The first outer gear and the second outer gear are meshed with and are driven together with the first inner gear and the second inner gear, respectively, to have a sun-and-planet motion, so that the planet gear changes a relative rotational phase between the first rotatable body and the second rotatable body
Data Source
AI summary
A driving-side rotatable body includes a driving-side inner gear, which has an axial extent that does not overlap with an axial extent of a driven-side inner gear of a driven-side rotatable body. A driven-side outer gear and a driving-side outer gear of a planet gear are meshed with and are driven together with the driven-side inner gear and the driving-side inner gear, so that the planet gear changes a relative rotational phase between the driven-side rotatable body and the driving-side rotatable body. The driven-side rotatable body supports the driving-side rotatable body from a radially inner side of the driving-side rotatable body at a location, which is radially outward of the driven-side inner gear.