Variable Valve Drive Fail-Safe Cam Carrier Actuation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing variable valve drive systems with sliding cam systems in internal combustion engines are vulnerable to failure, leading to inability to change valve control times if an actuator fails, particularly causing issues during engine braking mode.
Innovation Solution
A variable valve train with a shaft and cam carrier that includes a first and second actuator, allowing for axial displacement via engagement tracks, with a third emergency engagement track for fail-safe operation, enabling continued engine operation even if the primary actuator fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single actuator system is used for axial displacement of the cam carrier, then the device complexity is reduced, but the reliability deteriorates because the system cannot operate if the actuator fails
Solution Approach 1:
The patent implements a third emergency engagement track that is pre-configured on the cam carrier before any failure occurs. This emergency track allows the second actuator to perform axial displacement of the cam carrier in case the first actuator fails, ensuring continuous operation without requiring complex real-time decision systems or additional sensors.
Solution Approach 2:
The patent provides a fail-safe mechanism by pre-establishing the third engagement track and second actuator as a backup system. This cushioning against potential failure allows the engine to continue operating even when the primary actuator system fails, eliminating the need for complex failure detection and switching logic.
2Reliability
If multiple engagement tracks are added for fail-safe operation, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The second actuator is designed with multi-functionality: it can engage the second engagement track for normal operation and the third engagement track for emergency operation. This universal design allows a single actuator to perform multiple functions, reducing the need for separate dedicated backup actuators and minimizing overall system complexity while maintaining high reliability.
3Adaptability or versatility
If the cam carrier can be displaced in multiple axial directions, then the adaptability is improved for different operating modes, but the device complexity increases
Solution Approach 1:
The patent segments the engagement tracks into distinct functional zones: the first engagement track for one axial direction, the second engagement track for the opposite axial direction during normal operation, and the third engagement track for emergency operations. This segmentation allows independent control of each function while maintaining a unified cam carrier structure, achieving high adaptability without excessive complexity.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a variable valve train (10), in particular with a sliding cam system (14), for an internal combustion engine. The variable valve train (10) has a cam carrier (22) which has a first and second cam (28, 29) and a first to third engagement track (32, 34, 36). A first actuator (24) is configured to engage in the first engagement track (32) to displace the cam carrier (22) in a first axial direction. A second actuator (26) is configured to engage in the second engagement track (34) to displace the cam carrier (22) in a second axial direction opposite to the first axial direction, and to engage in the third engagement track (36) to displace the cam carrier (22) in the first axial direction.The variable valve train (10) can have the advantage that even if the first actuator (24) fails, a displacement of the cam carrier (22) normally caused by the first actuator (24) is possible, namely by the second actuator (26).