Valve Timing Assist Spring Structure to Prevent Slippage
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Solution Overview
Problem
Conventional valve timing adjustment devices experience slippage and disengagement of the assist spring due to torque fluctuation and engine vibration, and have deteriorated spring assembling properties due to the specific contact points between element wires.
Innovation Solution
A valve timing adjustment device with a spiral-spring-type assist spring where the inner peripheral end is formed in a non-bent shape, wound around a holder, and the second winding is in contact with the inner peripheral end, with no contact between windings from the second winding to the outermost periphery, preventing slippage and disengagement while facilitating assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inner peripheral end of the spring is bent toward the center and engaged with an engagement groove, then the spring can be retained on the boss portion, but the spring slides due to torque fluctuation or engine vibration and the engagement is released
Solution Approach 1:
The spring structure is segmented into distinct functional zones: the inner peripheral end forms a closed-loop configuration that engages with the engagement groove, while the body windings provide elastic functionality. This segmentation allows the retention function and elastic function to be independently optimized, preventing slippage while maintaining reliability.
Solution Approach 2:
Instead of bending the inner peripheral end outward to engage with the groove, the invention inverts the approach by bending it inward to form a closed loop. This inverted configuration creates a more secure engagement that resists torque fluctuation and vibration, preventing disengagement while maintaining spring functionality.
2Reliability
If the spring is disposed in a state where a plurality of specific points of an element wire are in a slight contact with each other, then the spring can be engaged with the engagement groove, but the spring assembling property is deteriorated due to torque application
Solution Approach 1:
The spring exhibits local quality differentiation: the inner peripheral end has a closed-loop configuration with specific contact characteristics for reliable engagement, while the body windings maintain appropriate spacing for easy assembly. This localized differentiation allows the engagement zone to provide secure retention without requiring torque application, while the rest of the spring remains easy to assemble.
Solution Approach 2:
The closed-loop configuration of the inner peripheral end is pre-formed during spring manufacturing, creating a self-retaining structure that automatically engages with the engagement groove without requiring additional torque application or adjustment during assembly. This preliminary action eliminates the need for torque application and simplifies the assembly process.
3Reliability
If the inner peripheral end of the spring is bent toward the center, then the spring can be engaged with the engagement groove, but the spring slides due to torque fluctuation or engine vibration
Solution Approach 1:
The spring is segmented into a closed-loop inner peripheral end for engagement and a body portion for elastic function. This segmentation creates a stable engagement interface that resists torque fluctuation and vibration, maintaining positional stability while preserving engagement capability.
Solution Approach 2:
The inner peripheral end is bent inward to form a closed loop instead of outward, creating a more stable engagement configuration. This inverted design provides better resistance against torque fluctuation and engine vibration, preventing slippage while maintaining reliable engagement with the engagement groove.
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 suppresses slippage and disengagement of the assist spring, improves assembly by reducing torque requirements, and enhances fatigue strength through shot peening, ensuring reliable operation and improved assembly efficiency.
Implementation Method 1
a spiral-spring-type assist spring that is disposed outside the plate of the first rotating body, has an outer peripheral end portion fixed to the first rotating body, has an innermost periphery and an inner peripheral end portion wound around an outer periphery of the holder and fixed to the second rotating body, and biases the second rotating body in one direction with respect to the first rotating body
Data Source
AI summary
Provided is a valve timing adjustment device that suppresses slippage of an assist spring, prevents disengagement, and facilitates assembly of the assist spring. A valve timing adjustment device adjusts an opening timing and closing timing of an intake valve or an exhaust valve of an internal combustion engine. In the assist spring, the inner peripheral end portion is formed in a non-bent shape, the outermost periphery is in contact with the rib, a second winding is in contact with the inner peripheral end portion, and there is no contact between windings from the second winding to the outermost periphery.