Valve Timing Gear Backlash Reduction via Segmented Planetary Carrier
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Solution Overview
Problem
Existing valve timing control apparatuses for internal combustion engines face challenges in eliminating backlash between gear portions, leading to abnormal sounds and potential damage due to manufacturing tolerances, which complicates simultaneous adjustment of meshed portions between the first and third gear portions and the second and fourth gear portions.
Innovation Solution
A valve timing control apparatus with a planetary rotary member and a biasing member that adjusts the contact points between gear portions to reduce backlash, utilizing a resilient member to exert restoring forces radially outward, ensuring regular contact and minimizing collisions between gear portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the third gear portion and the fourth gear portion are unitarily provided with a planetary rotary member, then a large reduction ratio can be attained with a compact structure, but it becomes difficult to simultaneously eliminate backlash at both meshed portions
Solution Approach 1:
The planetary rotary member is divided into a first planetary rotary member (with third gear portion) and a second planetary rotary member (with fourth gear portion). This segmentation allows independent adjustment of each gear portion relative to the sun gear, enabling backlash elimination at both meshed portions while maintaining the compact unitary structure.
Solution Approach 2:
The patent introduces adjustable mechanisms that allow the first and second planetary rotary members to be dynamically positioned at different radial distances from the rotation center. This dynamic adjustability enables optimization of meshed portion contacts to eliminate backlash while preserving the compact structure.
2Object-affected harmful factors
If backlash is eliminated at one meshed portion, then abnormal sound and damage are reduced, but the unitary structure prevents simultaneous elimination at both meshed portions
Solution Approach 1:
By segmenting the planetary rotary member into two independently adjustable parts, the patent enables separate optimization of each meshed portion. This allows backlash elimination at both the first-third and second-fourth meshed portions, thereby reducing abnormal sounds and damage without requiring overly complex adjustment mechanisms.
Solution Approach 2:
The patent applies different radial positioning adjustments to different parts of the system. The first planetary rotary member is positioned at a first radial distance while the second is positioned at a second radial distance, allowing localized optimization of each meshed portion's contact quality to eliminate backlash specifically where needed.
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 effectively reduces backlash between gear portions, preventing abnormal sounds and damage by ensuring consistent contact and smooth operation, thereby enhancing the reliability and performance of the valve timing control system.
Implementation Method 1
a biasing member interposed between the planetary rotary member and the planetary carrier to bias the planetary rotary member radially outward
Data Source
AI summary
A first rotary member rotates with a crankshaft and has a first gear. A second rotary member rotates with a camshaft and has a second gear that is axially shifted from the first gear. A planetary rotary member has third and fourth gears, which are eccentrically meshed respectively with the first and second gears to perform a planetary motion. A biasing member is interposed between the planetary rotary member and a planetary carrier, which supports the planetary rotary member. The planetary rotary member is in contact with the biasing member at a contact portion having an axial center. The axial center is located on a radially inner side of a meshed portion between the second and fourth gears, which has a backlash larger than that of a meshed portion between the first and third gears.