Shutdown Pressure Relief Valve for Common Rail Fuel Systems
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Solution Overview
Problem
Current common rail fuel systems experience slow pressure decay after shutdown, leading to unacceptably long times for pressure to return to atmospheric or tank pressure, which increases the risk of fuel spraying during servicing due to residual high pressure.
Innovation Solution
A shutdown pressure relief valve is introduced, which is pressure actuated to open and close a fluid connection between the high pressure and low pressure volumes, utilizing a piston and valve member to control the release of residual pressure from the high pressure volume to the low pressure volume, allowing for controlled pressure decay and safe system shutdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If low static leakage is implemented in the common rail fuel system, then fuel efficiency and performance are improved, but pressure decay time becomes unacceptably long
Solution Approach 1:
The invention extracts the pressure decay function from the normal operation mode by introducing a dedicated shutdown pressure relief valve that activates only during system shutdown. This valve provides a controlled leak path specifically for pressure relief without affecting the low static leakage performance during normal operation, thus resolving the contradiction between fuel efficiency and pressure decay time.
Solution Approach 2:
The shutdown pressure relief valve is positioned and configured to activate automatically when shutdown occurs, performing the pressure decay action immediately upon system stoppage. This preliminary action ensures rapid pressure relief is available as soon as shutdown is detected, addressing the long pressure decay time issue without compromising normal operation efficiency.
2Loss of energy
If zero static leakage is achieved in the common rail fuel system, then fuel efficiency is maximized, but the risk of fuel spraying during servicing increases due to prolonged high pressure
Solution Approach 1:
The shutdown pressure relief valve acts as an intermediary component that mediates between the high-pressure fuel system and the atmosphere during shutdown. It provides a controlled release path that safely reduces pressure without compromising the sealed system during operation, thus eliminating fuel spraying risk while maintaining fuel efficiency.
Solution Approach 2:
The invention separates the pressure containment function during operation from the pressure relief function during shutdown. The shutdown pressure relief valve extracts the pressure relief capability specifically for shutdown conditions, allowing zero static leakage during operation while providing rapid pressure decay during servicing to eliminate fuel spraying risk.
3Object-affected harmful factors
If a pressure relief mechanism is added to enable rapid pressure decay, then safety during servicing is improved, but device complexity increases
Solution Approach 1:
The shutdown pressure relief valve is designed as a passive, self-activating component that automatically opens when shutdown pressure conditions are detected. It uses the pressure differential itself to trigger the relief action without requiring external control systems, actuators, or complex control logic, thus improving safety while minimizing added complexity.
Solution Approach 2:
The shutdown pressure relief valve serves as a simple intermediary component between the high-pressure and low-pressure sides of the system. It provides a straightforward mechanical pressure relief path with minimal moving parts, achieving rapid pressure decay and improved safety without significantly increasing overall system complexity.
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 enables rapid pressure decay, reducing the risk of fuel spraying during servicing and allowing for safe system operation by controlling the release of residual high pressure, potentially achieving pressure reduction within a desired timeframe of less than two minutes.
Implementation Method 1
The shutdown pressure relief valve is pressure actuated to open and close a fluid connection between the first port and the third port, responsive to fluid pressure in the second port
Data Source
AI summary
A passive hydraulically actuated non-electric shutdown pressure relief valve relieves pressure in the high pressure volume of a low static leak common rail fuel system after shutdown. When the common rail fuel system is in operation, a transfer pump provides medium pressure to hold the shutdown pressure relief valve closed. At shutdown, the residual medium pressure downstream from the transfer pump decays back to tank, and the residual high pressure trapped in the common rail and fuel injectors pushes open the shutdown pressure relief valve to release the high pressure after back to tank.