Continuous Variable Valve Duration Apparatus for Engine
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Solution Overview
Problem
Existing engine valve systems, such as CVVL and CVVT, are complex and costly due to their need for varying valve lift and timing based on engine speed, which complicates optimal operation and increases manufacturing costs.
Innovation Solution
A continuous variable valve duration apparatus with a simple construction that includes a camshaft, variable phase angle cam, rocker arms, and motorized controllers to adjust valve opening duration based on engine conditions, allowing for continuous variation of valve profiles without excessive modification to existing engines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If general CVVL and CVVT are used to achieve optimal valve operation depending on engine speed, then valve timing and lift can be adjusted, but device complexity and manufacturing cost increase
Solution Approach 1:
The valve train is segmented into modular components: camshaft assembly with cams, rocker arms with roller followers, and valve stems. Each component has a specific function and can be independently optimized. The camshaft assembly includes multiple cams for different valves, allowing independent control of intake and exhaust valve timing and lift patterns.
Solution Approach 2:
The rocker arm assembly serves multiple functions: it acts as a lever to amplify cam profile effects, provides a roller follower to reduce friction, and enables variable valve timing through adjustable mounting positions. The same basic rocker arm structure can accommodate different cam profiles and timing requirements for various operating conditions.
2Adaptability or versatility
If general CVVL and CVVT are used to achieve optimal valve operation depending on engine speed, then valve timing and lift can be adjusted, but manufacturing cost increases
Solution Approach 1:
Valve timing and duration are controlled by changing the angular position parameters of the rocker arms relative to the camshaft. By adjusting the mounting angle and position of rocker arms on the camshaft, different valve timing patterns can be achieved without changing the physical cam profiles, allowing flexible adaptation to various engine operating conditions.
Solution Approach 2:
The invention uses standardized cam profiles and rocker arm designs that can be replicated across different valve positions. The same cam lobe design can be copied for multiple intake and exhaust valves, and identical rocker arm assemblies can be used throughout the engine, reducing manufacturing complexity and cost through economies of scale.
3Reliability
If traditional valve train design is used, then engine functionality is maintained, but weight and driving resistance increase
Solution Approach 1:
Traditional flat-tipped follower contacts are replaced with roller followers that reduce friction through rolling contact. The roller follower converts sliding friction between the cam profile and valve actuator into rolling friction, significantly reducing the force required to actuate the valves and reducing overall valve train weight while maintaining reliability.
4Reliability
If traditional valve train design is used, then engine functionality is maintained, but valve train height increases
Solution Approach 1:
The valve train components are arranged in a compact nested configuration: the roller follower is positioned at the end of the rocker arm, which rotates on the camshaft, which itself is positioned in the cylinder head. This nested arrangement minimizes the vertical height of the valve train while maintaining all necessary functional clearances and motion paths.
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
This solution enables optimal valve operation based on engine speed with reduced weight, size, and manufacturing costs, enhancing productivity and reducing the overall height of the valve train while maintaining efficient engine performance.
Implementation Method 1
An intake valve is pushed down by a cam to thereby open the intake valve, and a rotation angle of the camshaft is variable according to a rotation speed of the engine
Implementation Method 2
a roller follower contacting the cam and connected to a valve as a pair
Data Source
AI summary
A continuous variable valve duration system may include a camshaft, a first cam portion including a first cam, of which a relative phase angle of the first cam with respect to the camshaft is variable, an inner bracket transmitting rotation of the camshaft to the first cam portion, a slider housing on which a control slot is formed, the slider housing being rotatable around a pivot shaft, a first rocker arm including a first end contacting the first cam and a second end connected to a first valve, a rocker shaft to which the first rocker arm is rotatably connected, and onto which an eccentric shaft inserted into the control slot is formed, a duration controller configured to rotate the rocker shaft for the slider housing to move with respect to the camshaft, and an operation mode controller configured to change a position of the pivot shaft.