Variable Valve Train Lever Assembly for Independent Valve Lift Switching
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Solution Overview
Problem
Existing variable valve trains for internal combustion engines lack a reliable and simple mechanism for changing valve lift of gas exchange valves, requiring cylinder-selective control and lacking independent valve lift control curves, which complicates simultaneous and independent switching of multiple cylinders.
Innovation Solution
A power transmission device with first and second lever devices, each having a cam follower and receptacle, allowing for independent valve lift control curves by locking or releasing the cam followers hydraulically, enabling non-cylinder-selective switching and space-saving integration of switching functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a variable valve train uses traditional rocker arm assemblies with switching devices, then valve lift variation is achieved, but the device complexity increases and reliable simple control is lost
Solution Approach 1:
The valve train is divided into multiple independent lever devices (first lever device with first cam follower, second lever device with second cam follower), each capable of independent operation. This segmentation allows simple individual components to work together for complex valve lift variation without requiring a single complex switching mechanism.
Solution Approach 2:
Each lever device is designed to be multi-functional: the cam followers can be displaceably mounted to compensate for cam contours OR locked to transmit cam contours, allowing the same basic structure to serve multiple functions (compensation and transmission) without requiring separate mechanisms.
2Adaptability or versatility
If cylinder-selective control is implemented for valve switching, then individual cylinder control is achieved, but the control complexity and switching effort increase
Solution Approach 1:
The cam followers are designed with dynamic mounting - they can be displaceably mounted during certain phases and locked during others. This dynamic configuration allows the system to switch between compensation mode and transmission mode without requiring complex cylinder-selective control mechanisms.
3Reliability
If space is allocated for separate switching functionality, then reliable valve switching is achieved, but the overall device volume increases
Solution Approach 1:
The switching functionality is merged into the lever devices themselves. The cam followers are integrated directly into the lever arms, and the locking/displaceable mounting is part of the lever device structure. This eliminates the need for separate switching devices and reduces overall space requirements.
Data Source
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AI summary
The invention relates to a power transmission device (13) for a variable valve train (10) of an internal combustion engine. The power transmission device (13) comprises a first lever assembly (14). The first lever assembly (14) has a first cam follower (24) and a first receptacle (30) for the first cam follower (24). The first cam follower (24) is slidable and lockable in the first receptacle (30). The power transmission device (13) comprises a second lever assembly (16). The second lever assembly (16) has a second cam follower (54) and a second receptacle (58) for the second cam follower (54). The second cam follower (54) is slidable and lockable in the second receptacle (58).