Eccentric Hydraulic Lash Adjuster for Fuel Injector Clearance
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Solution Overview
Problem
In the midrange and heavy duty engine markets, hydraulic lash adjusters (HLAs) are too large to be effectively integrated into the valve train assemblies without interfering with fuel injectors, as they compete for space in the 'nose' of the rocker lever, leading to noise and vibration issues that are not adequately addressed by current axisymmetric configurations.
Innovation Solution
The implementation of an eccentric hydraulic lash adjuster with a pivot ball positioned at an offset from the lateral centerline of its outer housing, allowing for a clearance area between the intake and exhaust rocker lever assemblies, enabling the placement of a fuel injector while maintaining the lash adjustment functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional axisymmetric hydraulic lash adjuster is used, then the lash adjustment functionality is maintained, but the fuel injector space is interfered with due to the HLA being too large for the nose of the rocker lever
Solution Approach 1:
The patent applies asymmetry by positioning the pivot ball at an offset from the lateral centerline of the HLA outer housing. This asymmetric configuration creates a clearance area between the HLA and the nose of the exhaust rocker lever assembly, allowing the fuel injector to be positioned in this clearance area without interference. The asymmetric design resolves the space conflict while maintaining the HLA's functional integrity.
Solution Approach 2:
The patent utilizes dimensional change by introducing an offset in the lateral dimension (perpendicular to the main axis of the HLA). This offset creates additional clearance space in the lateral direction, allowing the fuel injector to be positioned between the intake and exhaust rocker lever assemblies. This dimensional approach transforms a 1D space conflict into a 2D spatial arrangement that accommodates all components.
2Reliability
If the HLA size is increased for midrange and heavy duty markets, then the lash adjustment capability is improved, but the NVH requirements are not adequately addressed due to interference with the fuel injector
Solution Approach 1:
The asymmetric offset configuration allows the HLA to maintain its full size and lash adjustment capability for midrange and heavy duty markets while creating the necessary clearance for the fuel injector. This resolves the contradiction by preserving both the enhanced HLA size needed for reliability and the spatial arrangement needed to meet NVH requirements.
Solution Approach 2:
The patent applies local quality by creating a specific clearance area with offset positioning, while maintaining the HLA's full functional properties in other regions. The local offset creates space only where needed (in the nose area), while the HLA maintains its full size and adjustment capability elsewhere, thus satisfying both requirements.
3Reliability
If the HLA is positioned in the nose of the rocker lever, then the lash adjustment is effective, but the fuel injector placement is restricted
Solution Approach 1:
The patent resolves this contradiction by utilizing the lateral dimension through the offset pivot ball position. This creates a clearance area that allows the fuel injector to be positioned in the nose region without interfering with the HLA's lash adjustment function. The dimensional approach provides placement flexibility for the fuel injector while maintaining HLA effectiveness.
Solution Approach 2:
The asymmetric offset configuration creates the necessary clearance area that provides placement flexibility for the fuel injector. The asymmetric design allows the HLA to remain effective in adjusting lash while creating space for the fuel injector, thus resolving the contradiction between HLA effectiveness and injector placement flexibility.
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 allows for the positioning of a fuel injector between the rocker lever assemblies, reducing noise and vibration by maintaining the lash adjustment functionality without interfering with the fuel injector, thus meeting the NVH requirements of the light duty engine segment in midrange and heavy duty engines.
Implementation Method 1
hydraulic lash adjuster (HLA) eliminates valve train clearance (lash) under all operating conditions
Implementation Method 2
the HLA applies a load onto the valve bridge
Implementation Method 3
The eccentric hydraulic lash adjuster can include an outer housing and a pivot ball, wherein the pivot ball is positioned at an offset from a lateral centerline of the outer housing
Data Source
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AI summary
A valve train assembly (16) includes a fuel injector (1), an intake rocker lever assembly (10), and an exhaust rocker lever assembly (14). The intake and exhaust rocker lever assemblies (10) can include an eccentric hydraulic lash adjuster (11) that is located in the nose (31) of the respective rocker lever assemblies (10). The rocker lever assemblies (10) are configured to allow a clearance area between a nose (31) of the intake rocker lever assembly (10) and the nose (31) of the exhaust rocker lever assembly (14). As such, the fuel injector (1) can be positioned in the clearance area, while still allowing the eccentric hydraulic lash adjusters to apply a load onto a corresponding valve bridge (2). For example, the eccentric hydraulic lash adjuster (11) can include an outer housing (20) and a pivot ball (21), wherein the pivot ball (21) is positioned at an offset (23) from a lateral centerline of the outer housing (20).