Exhaust Valve Opening System with Nested Piston Arrangement
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Solution Overview
Problem
Hydraulic compression braking systems are typically bulky and large in size and weight, making them difficult to service and increasing the overall engine package size, which limits their efficiency and flexibility.
Innovation Solution
A compact exhaust valve opening system utilizing a primary-secondary piston arrangement with a control fluid supply and check valves to efficiently transfer motion from a cam lobe to an exhaust valve, reducing engine height and weight while maintaining braking power and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a hydraulic compression braking system is used, then braking power is achieved, but the system becomes bulky and large in size and weight
Solution Approach 1:
The patent integrates the hydraulic compression braking system components within the existing exhaust valve mechanism structure. The primary and secondary pistons are nested within the rocker arm assembly, with the secondary piston housed inside the primary piston chamber. This nesting arrangement allows the braking system to occupy the same spatial envelope as the exhaust valve mechanism, eliminating the need for separate hydraulic system housing and reducing overall system weight.
2Power
If a hydraulic compression braking system is used, then braking power is achieved, but the system becomes bulky and increases engine package size
Solution Approach 1:
The rocker arm assembly serves dual functions: it operates the exhaust valve during normal engine operation and houses the hydraulic compression braking system. The primary piston mechanism that normally actuates the exhaust valve is repurposed to also drive the secondary piston that controls the compression braking function. This multi-functionality eliminates the need for separate dedicated braking system components, reducing engine package size while maintaining braking power capability.
3Power
If a hydraulic compression braking system is used, then braking function is achieved, but serviceability becomes difficult
Solution Approach 1:
The hydraulic compression braking system is segmented into modular components that can be independently accessed and serviced. The secondary piston assembly is designed as a separate cartridge that can be removed and replaced without disassembling the entire rocker arm mechanism. The primary and secondary piston chambers are separated by a removable divider, allowing technicians to service the braking components independently from the exhaust valve mechanism, significantly improving serviceability.
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 system provides comparable braking power with improved flexibility and reduced size and weight, enhancing serviceability and engine packaging efficiency.
Implementation Method 1
A control fluid supply is in fluid communication with a controllable valve to provide a control fluid to open at least one exhaust valve. The controllable valve is operable to pressurize the control fluid to open at least one exhaust valve.
Implementation Method 2
The pressurized control fluid is provided to a check valve and primary and secondary pistons, wherein motion imparted to the primary piston by a cam lobe is transferred to the secondary piston to displace the exhaust valve.
Data Source
AI summary
An exhaust valve opening apparatus such as for an engine compression braking system includes a rocker shaft for supplying control fluid to an controllable valve and for distributing the control fluid to a primary and second piston arrangement that selectively opens an exhaust valve in response to the control fluid being pressurized.