Reverse-Spring Hydraulic Lash Adjuster for Engine Braking
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Solution Overview
Problem
Existing engine compression braking systems using hydraulic lash adjusters (HLAs) cause the exhaust valve to remain open after an engine braking event, leading to potential engine damage or inoperability.
Innovation Solution
A valve train arrangement incorporating a reverse-spring hydraulic lash adjuster (RSHLA) with a predetermined closing velocity, where the engine brake system engages and disengages the exhaust valve such that the RSHLA expands to maintain contact during activation and compresses during deactivation, ensuring the exhaust valve closes properly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional HLA or RSHLA is used in a valve train arrangement with an engine braking system, then the HLA can accommodate lash during normal operation, but the exhaust valve remains open after the engine braking event, causing damage to the engine or rendering the engine inoperable
Solution Approach 1:
The patent changes the closing velocity parameter of the HLA by designing the deactivation velocity of the engine brake system to be lower than the predetermined closing velocity of the RSHLA. This parameter change ensures that the HLA can properly close the valve assembly after engine braking, preventing the harmful effect of the exhaust valve remaining open while maintaining reliable lash accommodation during normal operation
2Ease of operation
If a RSHLA is used to accommodate lash in the valve train, then the valve assembly can remain open during engine braking, but the HLA cannot compress fast enough to close the valve assembly when the engine brake system deactivates
Solution Approach 1:
The patent applies dynamics by creating a velocity relationship where the deactivation velocity of the engine brake system is controlled to be lower than the predetermined closing velocity of the RSHLA. This dynamic velocity matching allows the valve assembly to remain open during engine braking activation while ensuring it can close properly when deactivation occurs, resolving the speed contradiction
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
Prevents engine damage by ensuring the exhaust valve closes correctly after an engine braking event, maintaining system functionality and safety.
Implementation Method 1
a checkball spring or valve spring is provided that biases a checkball or closing body away from a valve seat such that the valve assembly is open in the free state. To close the valve assembly, the plunger or piston must move fast enough relative to the outer housing such that hydraulic fluid in the pressure chamber forces the closing body against the valve seat
Implementation Method 2
a return spring arranged between the outer housing and the plunger
Implementation Method 3
a valve spring positioned between the opening and the closing body. The valve spring biases the closing body to an open position
Data Source
AI summary
A valve train arrangement including at least one exhaust valve and a reverse-spring hydraulic lash adjuster (RSHLA) is provided. The RSHLA has a predetermined closing velocity. An engine brake system is configured to engage the exhaust valve, such that: (i) upon activation of the engine brake system, the engine brake system engages the at least one exhaust valve to open the at least one exhaust valve; and (ii) upon deactivation of the engine brake system, the engine brake system disengages the at least one exhaust valve such that the at least one exhaust valve is closed. A deactivation velocity of the engine brake system is less than the predetermined closing velocity of the RSHLA.