Type II Valvetrain Variable Valve Actuation
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Solution Overview
Problem
Existing valvetrain systems for Type II engines lack the capability to implement multiple variable valve actuation techniques on a single cylinder, limiting flexibility and functionality.
Innovation Solution
A valvetrain system comprising a valve bridge, switching rocker arm, center capsule, auxiliary rocker arms, and capsules that allow for selective application of multiple valve actuation profiles from overhead cam lobes, enabling combinations of cylinder deactivation, engine braking, hydraulic lash adjustment, late intake valve closing, early exhaust valve opening, and internal exhaust gas recirculation or reverse intake functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a prior art valve bridge is used to transfer valve lift to both valves, then the structure is simple, but only one variable valve actuation technique can be applied to the cylinder
Solution Approach 1:
The valvetrain is segmented into multiple independent actuation paths: a primary cam-driven rocker arm for baseline valve actuation, and separate auxiliary rocker arms with individual capsules for each valve that can apply additional actuation profiles. This segmentation allows multiple VVA techniques to be applied simultaneously to the same cylinder while maintaining structural organization.
Solution Approach 2:
The valve bridge structure is designed to be universal by accepting multiple types of actuation inputs: it can receive actuation from the primary cam-driven rocker arm and simultaneously accept actuation from multiple auxiliary rocker arms, each capable of implementing different VVA techniques. This multi-functional design enables the same valve bridge to support various VVA strategies.
2Adaptability or versatility
If multiple auxiliary rocker arms and capsules are added to enable multiple VVA techniques, then adaptability increases, but device complexity increases
Solution Approach 1:
The auxiliary rocker arms and capsules are integrated into the existing valve bridge structure in a nested manner. The capsules are positioned within the valve bridge assembly, and the auxiliary rocker arms are arranged to work in conjunction with the primary actuation system. This nesting minimizes the additional space and structural complexity required.
Solution Approach 2:
Multiple auxiliary rocker arms are merged into a single valve bridge assembly, sharing common structural elements such as the valve bridge body and mounting points. The capsules are combined with their respective rocker arms to form integrated actuation units, reducing the total number of separate components compared to fully independent systems.
3Ease of operation
If capsules are used to switch between active and lost motion states, then variable valve actuation control is improved, but manufacturing precision requirements increase
Solution Approach 1:
The capsules are designed to automatically switch between active and lost motion states based on the position and motion of the overhead cam lobes. The cam profile itself serves to control the capsule state changes, eliminating the need for separate control mechanisms and reducing manufacturing precision requirements for the switching mechanism.
Solution Approach 2:
The capsule mechanisms are pre-configured with spring elements and geometric constraints that automatically establish the correct active or lost motion state based on the cam position. This preliminary configuration ensures reliable state transitions without requiring high-precision active control during operation.
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 provides enhanced flexibility and functionality by allowing simultaneous application of multiple variable valve actuation techniques on both valves of a Type II engine, meeting customer demands for smaller engines while maintaining a compact footprint.
Implementation Method 1
The center capsule is configured to switch between an active state and a lost motion state. The active state is configured to transfer the selected first valve actuation profile or the selected second valve actuation profile, and the lost motion state is configured to absorb the selected first valve actuation profile or the selected second valve actuation profile.
Implementation Method 2
The center capsule is connected to either the valve end or to the pivot end
Data Source
AI summary
A valvetrain for a type II engine comprises a valve bridge, a switching rocker arm, a center capsule, a first auxiliary rocker arm, and a first auxiliary capsule. The selectively switching rocker arm is configured to switch configurations to transfer a first valve actuation profile from a first overhead cam lobe to the valve bridge center point and to transfer a second valve actuation profile from a second overhead cam lobe to the center point. The center capsule is configured to switch between an active state and a lost motion state. The first auxiliary rocker arm is configured to transfer a first auxiliary valve actuation profile from a third overhead cam lobe to the valve bridge first valve mounting area. The valvetrain can further comprise a second auxiliary rocker arm and a second auxiliary capsule.