Variable Valve Lift Cam Axial Positioning Thermal Expansion
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Solution Overview
Problem
Existing multiple variable valve lift systems face reliability issues due to thermal expansion caused by temperature changes, affecting the relative position of cams and valve opening/closing units, leading to inconsistent engine performance.
Innovation Solution
A multiple variable valve lift apparatus featuring a moving cam with a hollow cylindrical shape, a cam guide protrusion device, a controller, stopper grooves, and a stopper device with a stopper ball and elastic member, allowing for axial movement and precise control of valve lifts, while minimizing the impact of temperature-induced deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a cam shift type variable valve lift apparatus is used to manage relative position of cams and valve opening/closing device, then multiple valve lifts can be implemented, but thermal expansion deforms constituent elements and deteriorates reliability
Solution Approach 1:
The patent uses thermal expansion parameter changes to advantage by designing the camshaft and cam guide protrusion device with controlled expansion characteristics. The cam guide protrusion device is positioned to accommodate thermal deformation, allowing the system to maintain reliable cam shift functionality across temperature variations while implementing multiple valve lifts.
Solution Approach 2:
The cam guide protrusion device acts as an intermediary element between the camshaft and valve opening/closing device. It mediates the thermal expansion effects by providing a guided interface that accommodates deformation while maintaining precise cam positioning, thus preserving reliability during cam shifts.
2Ease of operation
If constituent elements are designed to guide cam shift, then valve operation can be controlled, but thermal deformation causes incorrect positioning and reduces reliability
Solution Approach 1:
The patent incorporates beforehand cushioning by designing the cam guide protrusion device and stopper mechanism to anticipate and accommodate thermal deformation before it causes positioning errors. The stopper groove and stopper ball arrangement provides a tolerance buffer that maintains accurate valve positioning even when thermal expansion occurs during engine operation.
3Productivity
If multiple cams are used to achieve different valve lifts, then engine performance can be optimized for different RPM, but the configuration becomes more complex
Solution Approach 1:
The patent merges multiple cam functions into a single integrated camshaft assembly with multiple cams arranged axially. Instead of using separate camshafts or complex switching mechanisms, the invention combines all valve lift functions into one unified structure that rotates with the camshaft, reducing overall system complexity while maintaining multiple valve lift capabilities for optimized engine performance.
Solution Approach 2:
The camshaft is designed as a universal component that performs multiple functions simultaneously - it provides different valve lifts for both intake and exhaust valves across various RPM ranges through its multiple cams. This multi-functional design eliminates the need for separate dedicated camshafts for each valve type or lift level, simplifying the overall configuration.
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 ensures reliable cam shift and stable valve operation across varying engine conditions by maintaining precise control over valve lifts, enhancing engine performance and durability through a simple configuration.
Implementation Method 1
an elastic member provided in the stopper mounting groove and elastically supporting the stopper ball
Data Source
AI summary
A multiple variable valve lift apparatus may include a moving cam formed of a hollow cylindrical shape, configured to be moveable in an axial direction of a camshaft while being rotated with the camshaft, and forming a plurality of cams implementing a cam guide protrusion device and different valve lifts from each other; an operation device selectively guiding a cam guide protrusion device to move the moving cam in the axial direction of the camshaft; a controller configured for controlling an operation of the operation device; a valve opening/closing device in contact with any one cam among the plurality of cams; a plurality of stopper grooves formed at an external circumference of the camshaft; and a stopper device provided at the moving cam and inserted to the stopper groove to be rotated at a position after the moving cam is moved.