Variable Valve Actuation Rocker Arm Switching Mechanism
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current rocker arm designs for internal combustion engines lack efficiency and additional capabilities, particularly in variable valve actuation systems, leading to suboptimal fuel economy and emissions control.
Innovation Solution
A discrete variable valve lift (DVVL) system with a switching rocker arm configuration that utilizes a diamond-like carbon (DLC) coating and dual feed hydraulic lash adjuster, enabling two-mode discrete valve lift operation with reduced mass and moment of inertia, while maintaining hydraulic lash adjustment for maintenance-free operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a traditional rocker arm design is used, then the structure is simple and easy to manufacture, but the fuel economy and emissions control are suboptimal
Solution Approach 1:
The rocker arm is divided into two separate arms (first rocker arm and second rocker arm) that can operate independently or together. This segmentation enables discrete variable valve lift functionality where the valve can be actuated at different lift levels, improving fuel economy by optimizing valve operation across different engine operating conditions while maintaining a relatively simple manufacturing process for each individual arm component.
Solution Approach 2:
The rocker arm system transitions from a static, fixed-lift design to a dynamic, variable-lift system. The first and second rocker arms can switch between latched and unlatched states, allowing the valve lift to vary dynamically based on engine conditions. This dynamic capability improves fuel economy and emissions control without significantly complicating the manufacturing of individual components.
2Productivity
If a switching rocker arm system is implemented, then fuel economy improves, but the device complexity increases
Solution Approach 1:
The first rocker arm is positioned within or alongside the second rocker arm, creating a nested or closely integrated configuration. This nesting approach allows both arms to share common mounting structures, pivot points, and actuation mechanisms, thereby reducing overall system complexity despite the added functionality. The nested arrangement minimizes the number of separate components and simplifies the latch mechanism required to connect or disconnect the arms.
Solution Approach 2:
The rocker arm system is designed so that the first and second rocker arms can perform multiple functions depending on their latched or unlatched state. When latched, they work together to provide high-lift operation; when unlatched, they provide low-lift or valve-deactivated operation. This multi-functionality is achieved within a single rocker arm assembly structure, reducing the need for additional separate components and maintaining relatively simple device complexity.
3Reliability
If DLC coating is applied to slider interface, then wear resistance and durability are enhanced, but the manufacturing process becomes more complex
Solution Approach 1:
The diamond-like carbon (DLC) coating is applied selectively to specific slider interfaces where wear occurs, rather than coating entire components. This localized coating approach concentrates the advanced material properties exactly where needed (at the contact surfaces between rocker arms and valve components) while minimizing the complexity of the manufacturing process. The selective coating can be applied through targeted surface treatment processes that are simpler than full-component coating methods.
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 system achieves improved fuel economy, reduced emissions, and extended durability by enabling efficient switching between low and high lift modes within one cam revolution, with the DLC coating enhancing slider interface stresses and wear resistance.
Implementation Method 1
A diamond-like carbon coating (DLC coating) allows higher slider interface stresses in a compact package. Testing results show that this technology is robust and meets all lifetime requirements with some aspects extending to six times the useful life requirements.
Implementation Method 2
Mode switching (i.e., from low to high lift or vice versa) is accomplished within one cam revolution... The DVVL switching rocker arm embodiments described herein focus on the design and development of a switching roller finger follower (SRFF) rocker arm system which enables two-mode discrete variable valve lift on end pivot roller finger follower valve trains.
Data Source
AI summary
A system for monitoring operation and diagnosing malfunctions in a variable valve actuation device is disclosed. The system has a rocker arm assembly that includes a first arm, a second arm with the first and second arms attached at a first end, a hydraulically operated latch assembly that functions to secure the first arm to the second arm when latched. The latch may be operated by a remote device. The rocker assembly pivots on a hydraulic lash adjuster (HLA). A control gallery connects the hydraulic valve to the latch. A pressure transducer is positioned either in the control gallery or the HLA and creates a signal indicating the sensed pressure. A reads the signal from the pressure transducer and identifies malfunctions of the rocker arm assembly. The system may also employ a non-contact transducer that monitors the state of the rocker arm assembly. The system may also employ a valve stem position sensor that monitors the engine valve position to determine malfunctions of the rocker arm assembly.