Hydraulic Lash Assembly Lever Arrangement for Valve Timing
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Solution Overview
Problem
Existing valvetrains face inefficiencies and increased wear due to lash variations caused by thermal expansion and component aging, leading to reduced engine performance and power loss, which existing hydraulic lash assemblies struggle to address effectively, especially in applications requiring precise intake timings and short intake durations.
Innovation Solution
A hydraulic lash assembly with a lever arrangement comprising a first arm and a second arm, where the second arm's pivot member supports the first arm, allowing independent rotational movement to transition the valve based on a driving force from a timing member, and providing lash compensation through a holding force from an actuator, thereby increasing the effective hydraulic stiffness of the assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional rocker arm valvetrain is used, then the structure is simple, but the lash varies due to thermal expansion and component aging leading to reduced engine performance
Solution Approach 1:
The rocker arm is segmented into a first arm and a second arm that can move independently relative to each other. The first arm receives driving force from the timing member and transitions the valve, while the second arm provides lash compensation through independent movement, resolving the contradiction by dividing the traditional single rocker arm into functional segments.
Solution Approach 2:
The lash assembly transitions from a static, fixed-geometry structure to a dynamic system where the second arm can move independently to compensate for lash variations. This dynamic adjustment mechanism maintains precise valve operation despite thermal expansion and component aging without requiring complex external adjustment systems.
2Reliability
If the lash is increased to accommodate thermal expansion, then component wear is reduced, but engine power and efficiency are reduced
Solution Approach 1:
The second arm of the rocker assembly automatically compensates for lash variations through its independent movement capability. This self-adjusting mechanism maintains optimal lash clearance without requiring external intervention or predetermined fixed clearance, allowing the system to self-regulate between wear protection and power efficiency.
3Power
If the lash is decreased for better engine performance, then power and efficiency are improved, but component wear increases and binding occurs
Solution Approach 1:
The dynamic second arm continuously adjusts the lash clearance based on operating conditions, preventing both excessive wear (from too much lash) and binding (from too little lash). This dynamic adaptation allows the system to maintain optimal performance across varying temperatures and component ages without sacrificing reliability.
4Reliability
If a hydraulic lash assembly is added to compensate for lash variations, then valve operation precision is improved, but the device complexity increases
Solution Approach 1:
The lash compensation functionality is merged directly into the rocker arm structure itself through the integrated first and second arms. This eliminates the need for separate external hydraulic adjustment mechanisms, achieving precise valve operation while minimizing additional complexity by combining multiple functions into a unified assembly.
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
This configuration enhances engine control and efficiency by maintaining precise valve operation, reducing latency and wear, and enabling faster intake cycles, particularly in heat recovery systems using supercritical fluids, by effectively compensating for lash and maintaining direct contact between valvetrain components.
Implementation Method 1
The first arm and the second arm form a lever arrangement whereby the pivot member of the second arm underlies and supports the first arm
Implementation Method 2
a second arm to receive a holding force from an actuator
Data Source
AI summary
A hydraulic lash assembly (HLA) for use in a valvetrain. The HLA preferably includes a first arm configured to transition a valve between a closed orientation and an open orientation. The first arm can include an engagement surface to receive a driving force from a timing member and to cause the valve to transition to the open orientation for a predetermined period. The HLA further preferably includes a second arm to receive a holding force from an actuator and a pivot section to couple to the first arm and displace the first arm based on the holding force from the actuator. Preferably, the first arm and the second arm form a lever arrangement whereby the pivot section of the second arm underlies and supports the first arm and allows for rotational movement of the first arm that is independent from the second arm.