Valve Timing Device Eccentric Housing for Imbalance Reduction
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Solution Overview
Problem
Existing valve timing changing devices for internal combustion engines face limitations in reducing unbalanced mass during rotation, primarily due to the structural constraints and manufacturing variations of the vane and housing rotors.
Innovation Solution
The proposed valve timing changing device incorporates a vane rotor and a housing rotor with a toothed member and a housing member. The housing member is designed with a center of gravity eccentric from the axis on the opposite side of the vane rotor's imbalance, and the toothed member has a cutout portion to further reduce the imbalance. This configuration allows for relative movement and locking between the vane and housing rotors, effectively reducing the overall imbalance without increasing size or weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If opening or cutout portions are provided in the chain sprocket to reduce imbalance, then the imbalance amount is reduced, but the strength and structural integrity are compromised
Solution Approach 1:
The invention extracts the imbalance reduction function from the chain sprocket and relocates it to a dedicated balance weight member. This allows the chain sprocket to maintain its full structural integrity without cutout portions, while the separate balance weight member provides the necessary counterbalancing mass to reduce rotation-induced imbalance.
Solution Approach 2:
The invention segments the housing rotor into multiple independent components: the chain sprocket, the balance weight member, and the vane rotor. This segmentation allows each component to be optimized independently - the chain sprocket for strength and the balance weight member for imbalance reduction - while working together as an integrated system.
2Object-generated harmful factors
If the vane rotor and housing rotor are balanced symmetrically, then the imbalance amount is reduced, but the adjustment capability is limited by assembly and manufacturing variations
Solution Approach 1:
The invention introduces a movable balance weight member that can be positioned at different angular locations around the rotation axis. This dynamic positioning capability allows the balance weight member to be adjusted to compensate for assembly and manufacturing variations, providing adaptability while effectively reducing imbalance through proper positioning.
Solution Approach 2:
The invention applies local quality by concentrating the imbalance correction function in a specific localized component (the balance weight member) rather than requiring symmetric balancing of the entire vane rotor and housing rotor assembly. This localized approach provides better control and adjustability.
3Stability of the object's composition
If the housing member is made heavier to increase stability, then the stability is improved, but the overall weight and size increase
Solution Approach 1:
The invention uses a balance weight member with eccentric mass distribution to create counterbalancing forces that offset the imbalance generated by the vane rotor and lock pin. This allows the housing member to maintain stability through dynamic counterbalancing rather than increasing its overall mass, thus avoiding unnecessary weight and size increases.
Data Source
AI summary
The valve timing changing device includes a vane rotor 10 that rotates integrally with a camshaft around an axis S of the camshaft and includes a lock pin 42; and a housing rotor Hr that is rotatable relative to the vane rotor around the axis within the range of a predetermined movable angle Δθ and whose relative rotation is locked by the lock pin. The housing rotor Hr includes a toothed member 30 having a tooth row 31 to which a driving force is applied, and a bottomed cylindrical housing member 20 fixed to the toothed member and accommodating the vane rotor. The housing member 20 is formed with a center of gravity eccentric from the axis S on a side that relatively reduces an imbalance amount m1 of the vane rotor.