Variable Valve Train Rocker Arm Planetary Gear Adjustment
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Solution Overview
Problem
Conventional variable valve trains for internal combustion engines cannot continuously and independently adjust valve opening and closing times and strokes, and require changes to surrounding components to convert a non-variable valve train to a variable one.
Innovation Solution
A variable valve train with a switchable rocker arm arrangement and a planetary gear system that allows for continuous adjustment of valve opening and closing times and strokes by changing the transmission properties of the rocker arm assembly, enabling independent adjustment regardless of the existing valve position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple cams with different contours are used to achieve variable valve lift, then valve opening and closing times can be varied, but the device complexity increases due to multiple camshafts or cam blocks
Solution Approach 1:
The single camshaft is segmented into multiple independent cam lobes, each with different contours for different valve lift profiles. This allows multiple valve timing characteristics to be achieved on a single camshaft rather than requiring multiple camshafts or cam blocks
Solution Approach 2:
The single camshaft is designed to perform multiple functions by incorporating different cam contours that can actuate different valves with different timing requirements, eliminating the need for separate camshafts for different valve types
2Adaptability or versatility
If axial displacement of cam block is used to change valve parameters, then valve lift can be varied, but the adjustment can only take place during base circle phase against spring force
Solution Approach 1:
The camshaft design allows dynamic adjustment of valve timing parameters during operation. The independent cam lobes can be selectively engaged or disengaged from their respective valves, enabling continuous adjustment of valve lift and timing without being constrained to base circle phase only
Solution Approach 2:
A control mechanism acts as an intermediary between the camshaft and valves, allowing selective engagement of different cam lobes with different valves. This intermediary system enables smooth transitions between different valve timing profiles without requiring axial displacement against spring force
3Adaptability or versatility
If conventional rocker arm design is modified to achieve variable valve timing, then valve control flexibility improves, but the moving mass increases
Solution Approach 1:
The rocker arm assembly is segmented into lighter, modular components that can be selectively positioned. This segmentation allows the system to achieve variable valve timing through selective engagement of cam lobes rather than requiring a single heavy, complex rocker arm design
Solution Approach 2:
The system achieves variable valve timing by changing the engagement parameters between cam lobes and valves rather than modifying the physical dimensions or mass of the rocker arm assembly. This allows flexibility in valve control without increasing moving mass
4Adaptability or versatility
If existing valve train is converted to variable valve train, then adaptability improves, but surrounding components must be changed
Solution Approach 1:
The camshaft is designed as a universal component that can serve both fixed and variable valve timing functions. By incorporating multiple cam contours on a single camshaft, the system maintains compatibility with existing valve train components while adding variability, eliminating the need to change surrounding components
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
Enables continuous and independent adjustment of valve opening and closing times and strokes without altering the conventional rocker arm and camshaft design, reducing moving mass and providing a robust, fully variable control suitable for commercial and industrial engines.
Implementation Method 1
The invention features a planetary gear system that allows for continuous adjustment of valve opening and closing times and strokes by changing the transmission properties of the rocker arm assembly
Implementation Method 2
The valve rocker arm has a roller, in particular a pressure roller, at its second end. The transfer rocker arm is operatively connected to the roller of the valve rocker arm via a contour surface, in particular a contour surface that defines the valve lift
Data Source
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AI summary
A variable valve train (1) comprises a switchable rocker arm arrangement for actuating a poppet valve, having a transmission rocker arm (10) and a valve rocker arm (20) pivotably mounted on different rocker arm axes (13, 23). The transmission rocker arm (10) engages a cam (2) of the camshaft (3) at a first end (11) and is operatively connected at a second end (12) via a contour surface (16) to the roller (26) of the valve rocker arm (20), such that a rocking movement of the transmission rocker arm (10) generates a rocking movement of the valve rocker arm (20), during which the roller (26) of the valve rocker arm (20) rolls on the contour surface (16).The valve train includes an actuating device for switching the rocker arm arrangement, by means of which the contour surface (16) can be rotated about the rocker arm axis (13) of the transmission rocker arm (10) by means of a planetary gear (19) in order to generate a displacement of a rolling area of the roller (26) on the contour surface (16; 516) and to transmit the stroke specified by the cam (2) to the valve rocker arm (20).