Dual Body Rocker Arm Latching Actuation
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Solution Overview
Problem
Existing switchable rocker arm systems in internal combustion engines face challenges in maintaining a default latched configuration, particularly when the latch is biased towards an unlatched state, which can lead to unreliable operation and require precise timing for actuation.
Innovation Solution
A valve train assembly with a dual body rocker arm featuring a latching arrangement biased to an unlatched configuration, an actuator arrangement with a selector cam and biasing means to ensure default latching, and a compliance biasing system to ensure the latch pin moves into the latched position when possible, along with a hard stop to prevent over-rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the latching arrangement is biased to an unlatched configuration to enable easy switching, then the ease of operation is improved, but the reliability deteriorates because the system cannot maintain a default latched configuration without precise timing control
Solution Approach 1:
The patent inverts the conventional approach by using a biasing means (spring) to actively maintain the latched configuration as the default state, rather than relying on the absence of actuation. The biasing means exerts a force to keep the latch engaged, and the actuator must actively overcome this bias to unlatch. This inversion ensures that the system defaults to a safe latched state without requiring precise timing or continuous control signals.
Solution Approach 2:
The biasing means is pre-configured to automatically maintain the latched configuration without requiring active control. The spring is pre-loaded to exert a latching force, ensuring that the system is already in the desired latched state before any actuation occurs. This preliminary action eliminates the need for precise timing synchronization during normal operation.
2Device complexity
If the latching arrangement is biased to an unlatched configuration to simplify the actuation mechanism, then the device complexity is reduced, but the reliability deteriorates due to potential failure modes when power is lost or communication fails
Solution Approach 1:
The patent inverts the failure mode behavior by designing the biasing means to default to the safe latched configuration when power is lost or actuation stops. Instead of defaulting to unlatched (which would cause failure), the spring-based biasing system automatically returns to maintaining the latched state, making the system fail-safe. This inversion of the default state ensures reliability during power loss or communication failures.
Solution Approach 2:
The biasing means acts as a cushioning mechanism that is pre-loaded to compensate for potential failure modes. The spring stores energy that can be released to maintain latching force during power interruptions, providing a buffer against reliability issues. This beforehand cushioning ensures that the system can withstand power loss or communication failures without compromising the latched configuration.
3Reliability
If precise timing synchronization is required for actuation to maintain default latching, then the reliability is improved, but the productivity deteriorates due to limited flexibility in switching between modes
Solution Approach 1:
The biasing means is pre-configured to automatically maintain the latched configuration without requiring active control or timing synchronization. The spring is pre-loaded to exert a latching force, ensuring that the system is already in the desired latched state before any actuation occurs. This preliminary action eliminates the need for precise timing synchronization during normal operation, allowing flexible switching when needed.
Solution Approach 2:
The latching arrangement is self-sustaining through the biasing means, which automatically maintains the latched configuration without requiring external control signals or timing coordination. The spring-based system self-regulates to keep the latch engaged, freeing the control system from the need for precise timing management and enabling more flexible operational modes.
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
Ensures reliable operation by maintaining the latched configuration as a default, even in the absence of power or communication failures, and allows for flexible switching between modes without precise timing synchronization.
Implementation Method 1
the actuator arrangement comprises a biasing means arranged to bias the shaft rotationally in a first direction towards the first configuration
Implementation Method 2
the component is a selector cam rotatable to operate the latching arrangement; wherein the selector cam comprises a lobe profile and a base circle
Implementation Method 3
wherein the actuator arrangement comprises a hard stop arranged to prevent the shaft from rotating in the first direction beyond the first configuration
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A valve train assembly comprises at least one dual body rocker arm comprising a first body, a second body, a latching arrangement for latching and unlatching the first body and the second body. The latching arrangement is biased to an unlatched configuration. The assembly further comprises an actuator arrangement external to the rocker arm for controlling the latching arrangement. The actuator arrangement is configured so that its default setting is to cause the latching arrangement to be in a latched configuration.