Switchable Rocker Arm Lock Member and Spring Mechanism
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Solution Overview
Problem
Existing rocker arms for internal combustion engines lack an efficient mechanism to selectively prevent the inner follower from reciprocating beyond a predetermined position, which limits their ability to switch between coupled and decoupled states effectively, impacting fuel efficiency and valve lift management.
Innovation Solution
A rocker arm design featuring a body with a central opening for linear reciprocation of the inner follower, a lost motion spring to bias the follower, and a lock member that moves between coupled and decoupled positions to control the follower's movement, preventing it from reciprocating past a predetermined position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a lock pin mechanism is used to prevent the inner follower from reciprocating, then the coupled state is achieved, but the device complexity increases due to additional locking components
Solution Approach 1:
The patent extracts the locking function from a separate lock pin mechanism and integrates it into the rocker arm body itself through a locking surface and spring-loaded engagement feature. This eliminates the need for a separate lock pin while maintaining the coupled state stability, thereby reducing device complexity while preserving reliability.
Solution Approach 2:
The locking surface is merged with the rocker arm body structure, combining the support function and locking function into a single integrated component. The spring mechanism is also integrated into the body, eliminating separate locking components and reducing overall device complexity while maintaining reliable coupled state engagement.
2Productivity
If the inner follower is allowed to reciprocate freely, then the decoupled state is achieved for fuel efficiency, but the manufacturing precision required to control movement increases
Solution Approach 1:
The patent introduces a spring as an intermediary element between the inner follower and the rocker arm body. This spring provides a controlled elastic force that guides the follower's reciprocation during decoupled state, ensuring precise movement control without requiring extremely tight manufacturing tolerances on the follower and body interfaces.
Solution Approach 2:
The spring mechanism changes the physical parameters of the follower's movement by providing a restoring force that controls the reciprocation amplitude and direction. This allows the system to achieve precise movement control through the spring's mechanical properties rather than relying solely on manufacturing precision of the follower guides.
3Reliability
If a traditional lock pin design is used, then the coupled state is secured, but the ease of assembly decreases due to complex installation procedures
Solution Approach 1:
The spring-loaded locking surface design allows the locking mechanism to self-engagement during assembly. When the rocker arm components are assembled, the spring automatically pushes the locking surface into engagement with the follower, eliminating the need for separate locking operations or complex assembly procedures while ensuring reliable coupled state engagement.
4Adaptability or versatility
If the rocker arm design includes comprehensive locking and spring mechanisms, then the switching capability is improved, but the volume of the rocker arm increases
Solution Approach 1:
The spring mechanism is nested within the rocker arm body cavity, and the locking surface is integrated into the body structure rather than being a separate external component. This nesting arrangement allows the locking and spring mechanisms to occupy minimal space within the existing rocker arm volume, maintaining switching capability while minimizing volume increase.
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
Enables efficient switching between coupled and decoupled states, allowing for precise control of valve lift, improving fuel efficiency and compactness while facilitating ease of assembly.
Implementation Method 1
a lost motion spring which biases the inner follower to move relative to the body along the reciprocation axis in a first direction
Data Source
AI summary
A rocker arm includes a body having a first wall and a second with a central opening provided therebetween, the first wall having a first aperture extending therethrough and the second wall having a second aperture extending therethrough. An inner follower within the central opening selectively reciprocates along a reciprocation axis relative to the body, the inner follower extends through the first aperture and the second aperture. A lost motion spring biases the inner follower to move relative to the body along the reciprocation axis in a first direction. A lock member is moveable along a lock member axis between a coupled position which prevents the inner follower from moving past a predetermined position in a second direction which is opposite of the first direction and a decoupled position which permits the inner follower to move past the predetermined position in the second direction.