Compression Brake Reset Valve for Secondary Piston Jacking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing exhaust valve opening devices for compression braking in heavy vehicles suffer from secondary piston jacking due to high supply oil pressure, leading to potential engine failure from incomplete valve closure and piston contact, which conventional solutions like stiffer springs and pressure regulation devices require additional packaging volume that may not be feasible.
Innovation Solution
A reset valve positioned in the high-pressure brake circuit to bleed oil pressure when the primary piston returns to the cam lobe base circle, preventing secondary piston jacking and ensuring complete exhaust valve closure, suitable for engine designs with size constraints that cannot accommodate pressure relief valves or stiffer springs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stiffer retention spring is used to prevent secondary piston jacking, then the reliability of exhaust valve closure is improved, but the device complexity and packaging volume increase
Solution Approach 1:
The patent introduces a reset valve as an intermediary component in the hydraulic circuit to bleed excess pressure from the high-pressure circuit. This mediator component prevents the secondary piston from tracking the exhaust valve motion during the exhaust stroke by periodically releasing built-up pressure, thereby avoiding piston jacking without requiring a stiffer retention spring.
2Reliability
If a pressure regulation device is added to the circuit to prevent secondary piston jacking, then the reliability of exhaust valve closure is improved, but the packaging volume and device complexity increase
Solution Approach 1:
The reset valve is integrated into the existing high-pressure brake circuit architecture, merging the pressure relief function with the existing hydraulic system components. The valve utilizes the existing high-pressure oil supply circuit and combines it with a bleed path to the low-pressure circuit, eliminating the need for separate standalone pressure regulation devices and reducing overall packaging volume.
3Power
If the supply oil pressure is increased to improve braking performance, then the power generation from piston is improved, but the secondary piston tracking and jacking effect worsen
Solution Approach 1:
The reset valve operates periodically during the engine brake cycles to bleed excess pressure from the high-pressure circuit. By opening at specific intervals when the primary piston returns to base circle, the valve periodically releases built-up pressure that would otherwise cause secondary piston jacking, allowing the system to tolerate higher supply pressures while maintaining reliable piston return.
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 reset valve enables higher oil supply pressure tolerance and reduces sensitivity to pressure variations, preventing engine failure by ensuring consistent exhaust valve closure and secondary piston return, even in constrained engine packages.
Implementation Method 1
a first port in fluid communication with a high pressure circuit and a second port in fluid communication with a low pressure circuit
Data Source
AI summary
An engine brake reset valve includes a cylindrical housing body having an end and a central cavity therein. The reset valve includes a first valve part attached to a second valve part, wherein the central cavity is sized to receive the first valve part and the second valve part. The first and second valve parts are movable within the central cavity between open and closed positions. When the second valve part is in a closed position, the second valve part engages and blocks the central orifice to prevent fluid pressure from entering the central orifice. When the second valve part is in an open position, the second valve part moves away from the central orifice to enable fluid pressure to enter the central orifice.