One-Way Rocker Arm Coupling for Auxiliary Valve Actuation
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Solution Overview
Problem
Existing valve actuation systems in internal combustion engines face challenges in providing auxiliary valve actuation motions, such as high power density compression-release engine braking and cylinder deactivation, due to the need for collapsing mechanisms that are not feasible or desired in all cases, and there is a lack of systems that efficiently integrate these features without hydraulic lash adjusters or guided valve bridges.
Innovation Solution
A valve actuation system comprising at least two rocker arms with a one-way coupling mechanism, where one rocker arm receives main valve actuation motions and another receives auxiliary motions, controlled by hydraulically-activated actuators to selectively convey or block these motions, and optionally incorporating a collapsing mechanism to decouple rocker arms and hydraulic lash adjusters for flexible operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a collapsing mechanism is deployed in a valve bridge to facilitate auxiliary valve actuation motions, then auxiliary valve actuation (such as engine braking and cylinder deactivation) can be achieved, but the device complexity increases and the system becomes infeasible for engines without valve bridges or guided valve bridges
Solution Approach 1:
The valve actuation system is segmented into separate rocker arms for main valve actuation and auxiliary valve actuation, each with independent actuators. This allows the auxiliary function to be added without modifying the existing valve bridge structure, thus avoiding increased complexity in engines without valve bridges while maintaining adaptability for auxiliary valve actuation.
Solution Approach 2:
The rocker arm system is designed with multi-functionality, where each rocker arm can independently perform main valve actuation or auxiliary valve actuation based on actuator control. This universal design allows the same basic structure to serve multiple functions across different engine types, eliminating the need for valve bridge-specific collapsing mechanisms.
2Power
If a collapsing mechanism is used in a valve bridge to lose main valve actuation motions for auxiliary functions, then high power density engine braking is achieved, but the system requires hydraulic lash adjusters or guided valve bridges which limits applicability
Solution Approach 1:
The system segments valve actuation into separate rocker arms for main and auxiliary functions, allowing independent control without requiring integrated valve bridge structures. This enables high power density engine braking through auxiliary rocker arms while maintaining compatibility with various engine types that lack specialized valve bridges.
Solution Approach 2:
The auxiliary rocker arm acts as an intermediary mechanism that receives actuation motions independently from the main rocker arm. This intermediary structure enables high power density engine braking without requiring modifications to the main valve actuation path, thus maintaining compatibility across different engine architectures.
3Adaptability or versatility
If a one-way coupling mechanism is used between rocker arms to transfer main valve actuation motions, then auxiliary valve actuation motions can be selectively conveyed, but the device complexity increases
Solution Approach 1:
Instead of using complex one-way coupling mechanisms to control motion transfer, the system inverts the approach by using independently controlled actuators on each rocker arm. Each actuator can selectively engage or disengage its rocker arm from the valve, providing selective motion conveyance without requiring mechanical one-way couplings, thus reducing device complexity while maintaining adaptability.
Data Source
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AI summary
A valve actuation system comprises at least one main rocker arm operatively connected to a first engine valve, the at least one main rocker arm configured to receive at least main valve actuation motions. A second rocker arm is operatively connected to a second engine valve, the second rocker arm being configured to receive first auxiliary valve actuation motions. The second rocker arm further comprising a hydraulically-controlled first actuator that can selectively couple or decouple the second rocker arm and the second engine valve thereby permitting or preventing conveyance of the first auxiliary valve actuation motions from the second rocker arm to the second engine valve. A one-way coupling mechanism disposed between the at least one main rocker arm and the second rocker arm permits valve actuation motions to be transferred from the at least one main rocker arm to the second rocker arm, but not vice versa.