Variable Valve Lift Apparatus Friction Reduction
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Solution Overview
Problem
Existing variable valve lift (VVL) apparatuses face challenges in minimizing friction and power loss while achieving optimal valve operation based on engine speed, and they often require complex designs and assembly processes.
Innovation Solution
A VVL apparatus featuring a cam, rocker arm, cam follower, and swing arm with rollers and a hydraulic lash adjuster, controlled by a DC motor and worm gear system, allowing for variable valve lift and reduced friction through precise control of the relative rotation angle of the rocker arm around the camshaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a variable valve lift apparatus is designed to minimize friction and power loss, then energy efficiency is improved, but the structural complexity increases
Solution Approach 1:
The rocker arm's rotation angle relative to the camshaft is made variable through an actuator, allowing the system to dynamically adjust valve lift characteristics. This dynamic configuration enables optimization of friction and power loss at different operating conditions without requiring multiple fixed complex mechanisms.
Solution Approach 2:
The system changes the rotation angle parameter of the rocker arm to achieve variable valve lift. By adjusting this angular parameter, the apparatus can minimize friction and power loss at different engine speeds and loads, improving energy efficiency without fundamentally changing the mechanical structure.
2Ease of operation
If the rocker arm rotation angle is made variable for optimal valve operation, then valve operation performance is improved, but the device complexity increases
Solution Approach 1:
The rocker arm is designed with variable rotation angle capability through an actuator mechanism, enabling optimal valve operation at different engine speeds. The dynamic adjustment of the rocker arm angle allows the system to adapt to varying operational requirements without requiring entirely separate mechanisms for different operating modes.
Solution Approach 2:
The variable rotation angle rocker arm serves multiple functions: it provides optimal valve lift at different engine speeds, enables friction minimization, and maintains compact design. This multi-functional component replaces what would otherwise require multiple specialized mechanisms, managing complexity while improving operation.
3Loss of energy
If rollers are added to minimize friction at contact portions, then friction loss is reduced, but the device complexity and assembly difficulty increase
Solution Approach 1:
The rollers are designed to be self-installing components that automatically find their correct positions during assembly. The cam follower and swing arm structures incorporate features that guide the rollers into place, eliminating the need for complex alignment procedures or specialized assembly tools, thus reducing assembly difficulty while maintaining friction reduction benefits.
4Loss of energy
If the cam follower is designed to pivot around the rocker arm, then friction is minimized, but the manufacturing precision requirements increase
Solution Approach 1:
The cam follower incorporates self-aligning features that automatically compensate for minor manufacturing variations. The pivot mechanism includes tolerance-compensating elements that ensure proper alignment and minimal friction even when manufacturing precision varies within normal tolerances, reducing the stringency of precision requirements.
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 minimizes friction and power loss, enhances controllability, and simplifies assembly by enabling adjustable valve lift based on engine speed, improving engine performance with reduced operational complexity.
Implementation Method 1
The actuator may comprise a DC motor. The actuator may comprise a worm gear connected with the DC motor and a worm wheel attached to the one end of the rocker arm
Implementation Method 2
A first roller may be disposed to the contact portion of the cam follower and contacts the cam. A second roller may be disposed to the other end of the cam follower and rotatably contacts the swing arm
Data Source
AI summary
A variable valve lift apparatus may include a cam that is disposed to a camshaft and rotates, a rocker arm that is disposed to the camshaft and in which a relative rotation angle of the rocker arm around the camshaft is variable, a cam follower that contacts the cam, receives rotation of the cam, and pivots around the rocker arm, and a swing arm that contacts the cam follower and drives a valve.