Continuous Variable Valve Duration Apparatus Tolerance Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing engine valve systems face issues with noise and vibration due to manufacturing tolerances, which affect the optimal operation of intake and exhaust valves depending on engine rotation speed, and current solutions like CVVL and CVVT do not adequately address these problems with simple construction and tolerance control.
Innovation Solution
A continuous variable valve duration apparatus with a camshaft, cam unit, guide bracket, worm wheel, control shaft, and tolerance adjusting pins, allowing for adjustable valve duration based on engine operation conditions, reducing noise and vibration through precise tolerance control and a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a continuous variable valve timing (CVVT) apparatus is used to change valve timing, then valve timing optimization depending on engine speed is achieved, but valve opening duration cannot be adjusted and manufacturing tolerances cause noise and vibration
Solution Approach 1:
The patent implements continuous variable valve duration by making the valve train system dynamically adjustable. The wheel housing can move axially relative to the camshaft, changing the effective cam profile and thus the valve opening duration. This dynamic adjustment capability allows optimization of both valve timing and duration depending on engine operating conditions, while the tolerance adjustment mechanism compensates for manufacturing variations to reduce noise and vibration.
Solution Approach 2:
The patent changes the operational parameters of the valve train by allowing axial movement of the wheel housing, which alters the cam-to-valve transmission geometry. This parameter change enables continuous variation of valve opening duration. Additionally, tolerance adjustment pins are used to fine-tune the positional parameters of assembled components, compensating for manufacturing tolerances and reducing harmful vibrations and noises.
2Adaptability or versatility
If CVVD technology is used to control valve opening duration, then optimal valve operation is achieved, but manufacturing tolerances of assembled parts cause quality differences and noise
Solution Approach 1:
The patent incorporates tolerance adjustment pins that can be pre-adjusted during assembly to compensate for manufacturing tolerances of the camshaft, wheel housing, and other components. This preliminary adjustment action ensures optimal alignment and fit before the engine enters service, reducing quality variations between assembled units and minimizing noise and vibration from tolerance accumulation.
3Adaptability or versatility
If multiple components are assembled to achieve continuous variable valve duration, then valve duration adjustment is enabled, but tolerance accumulation causes noise and vibration
Solution Approach 1:
The patent uses tolerance adjustment pins as intermediary elements between the camshaft, wheel housing, and guide bracket. These pins act as mediators that absorb and compensate for tolerance variations in the assembled components. By providing this intermediary adjustment mechanism, the system maintains precise relative positioning despite manufacturing tolerances, thereby reducing noise and vibration while preserving the continuous variable valve duration capability.
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 apparatus effectively adjusts valve duration according to engine operation, reduces noise and vibration, maintains a low valve train height, and can be integrated into existing engines with minimal design changes, enhancing productivity and reducing production costs.
Implementation Method 1
a guide shaft having a guide thread formed thereto to be movably inserted into the upper guide boss
Implementation Method 2
a worm wheel of which an inner thread engaged with the guide thread is formed on inside thereof and of which an outer thread is formed on outside thereof
Implementation Method 3
a control shaft of which a control worm engaged with the outer thread is formed thereto
Data Source
AI summary
A continuous variable valve duration apparatus includes a camshaft, a cam unit on which a cam is formed and the camshaft is inserted, a guide bracket of which an upper guide boss is formed, an inner wheel transmitting the rotation of the camshaft to the cam unit, a wheel housing of which a guide shaft having a guide thread formed thereto to be movably inserted into the upper guide boss is formed thereto, and of which a tail guide guiding the relative movement of the guide bracket is formed thereto, and the wheel housing into which the inner wheel is rotatably inserted, a worm wheel of which an inner thread engaged with the guide thread is formed on inside thereof and of which an outer thread is formed on outside thereof, and a tolerance adjusting pin inserted into the tolerance adjusting portion.