Hydraulic Lash Adjuster Integrating Lost Motion and Automatic Compensation
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Solution Overview
Problem
Existing hydraulic lash adjuster systems for engine valve trains are complex and require multiple components, with manual lash adjusters lacking automatic adjustment capabilities and complicating engine servicing, while current systems do not efficiently integrate lost motion and lash adjustment functions.
Innovation Solution
A hydraulic lash adjuster with a lost motion arrangement that automatically compensates for lash in the engine valve train, incorporating a simplified design with fewer components, allowing for automatic lash adjustment and inhibiting motion transfer from the cam lift profile to the engine valve, utilizing a check ball valve and spring-biased plungers to maintain pressurized oil flow and support valve operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a separate distinct automatic lash adjuster is used in addition to lost motion system, then automatic lash adjustment is achieved, but device complexity increases and manufacturing costs increase
Solution Approach 1:
The patent combines the lost motion system and automatic lash adjuster into a single integrated valve actuation system. The rocker arm assembly incorporates both the lost motion mechanism (through its mechanical design) and the automatic lash adjustment (through the hydraulic lash adjuster), eliminating the need for separate distinct components while maintaining both functions.
Solution Approach 2:
The rocker arm assembly is designed to perform multiple functions simultaneously: it provides lost motion capability through its mechanical structure, enables automatic lash adjustment via the hydraulic lash adjuster, and actuates the engine valve. This multi-functional design reduces overall system complexity while achieving automation.
2Device complexity
If manual lash adjuster is used, then device complexity is reduced, but automatic lash adjustment capability is lost and maintenance requirements increase
Solution Approach 1:
The hydraulic lash adjuster automatically compensates for valve train lash through self-contained hydraulic mechanisms. The check ball valve and spring-biased plunger assembly automatically maintain proper clearance without requiring manual intervention, enabling the system to service itself and eliminating the need for periodic mechanical adjustment.
Solution Approach 2:
The patent uses hydraulic principles with oil-filled chambers, check ball valves, and spring-biased plungers to achieve automatic lash adjustment. The incompressible oil provides rigid support when the valve is open while allowing automatic compensation for lash changes through hydraulic pressure differential.
3Reliability
If check ball valve with closely spaced leak down surfaces is used, then oil can be retained in first chamber, but oil escape rate is limited and chamber pressure equalization is slow
Solution Approach 1:
The check ball valve dynamically transitions between two states: during valve closing, the ball seats against the leak down surfaces to retain oil and provide rigid support; during valve opening, the pressure differential automatically opens the valve to allow rapid oil escape. This dynamic behavior optimizes both oil retention and escape rate based on operational requirements.
Solution Approach 2:
The system changes the flow resistance parameter of the check ball valve based on pressure differential. When pressure in the first chamber exceeds the second chamber by a certain threshold, the valve opens to allow rapid equalization; when pressure is lower, the valve closes to retain oil. This parameter change enables adaptive control of oil flow characteristics.
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 solution simplifies manufacturing, reduces costs, and provides automatic hydraulic lash adjustment and lost motion capability, ensuring efficient engine operation and reduced maintenance by integrating lash adjustment and lost motion functions within a single, less complex system.
Implementation Method 1
a spring biased to enlarge the first oil chamber by pushing the plunger assembly outwardly from the outer body to extend the HLA
Implementation Method 2
the first oil chamber and the second oil chamber are separated by a one way valve and oil flows from the second chamber into the first chamber through the one way valve when the HLA extends (and hence the first chamber enlarges) because the oil pressure in the second chamber becomes higher than that in the first chamber
Implementation Method 3
the incompressible oil in the first chamber provides sufficient rigid support for the HLA to open the valve when a rocker arm pivots (i.e. the incompressible oil prevents the plunger assembly being pushed back inwardly of the outer body so that the HLA acts as a solid body)
Data Source
AI summary
A hydraulic lash adjuster for an engine valve train has a hydraulic lash adjusting arrangement for automatically compensating for lash in an engine valve train, and a lost motion arrangement for inhibiting motion induced in the valve train in response to a lift profile of a rotating cam from being transferred to an engine valve.