Three-Stage Proportional Spool Valve for Zero-Flow Fuel Pump Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing common rail fuel delivery systems face challenges in efficiently managing three operating conditions: limp-home, zero flow, and metering, with high power consumption and inadequate controllability, particularly in the zero flow condition, due to reliance on digitally controlled valves and solenoids.
Innovation Solution
A multi-stage spool valve with a proportional solenoid actuator and biased springs allows for variable positioning to manage three stages of high pressure pump operation, ensuring efficient fuel delivery by aligning bypass and metering ports with the spool valve, maintaining fluid communication with a drain port, and controlling the inlet check valve to achieve low-pressure flow, zero flow, and metered high-pressure flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a digitally controlled valve is used to achieve zero flow condition, then zero leakage is achieved, but power consumption becomes excessively high
Solution Approach 1:
The control valve is divided into three distinct stages: bypass stage, zero fueling stage, and metering stage. Each stage handles specific flow conditions, allowing the system to achieve zero flow (zero fueling stage) without requiring full digital valve closure, thereby reducing power consumption while maintaining reliability.
Solution Approach 2:
The system transitions from binary digital control (open/closed) to multi-stage proportional control with variable spool positions. By changing the control parameter from binary to continuous multi-position, the system achieves zero flow condition through mechanical positioning rather than full electronic actuation, reducing power consumption.
2Ease of operation
If a proportional solenoid actuator is used to enable variable displacement of the spool valve, then controllability is improved, but device complexity increases
Solution Approach 1:
The spool valve serves multiple functions across three stages: bypass flow control, zero flow achievement, and metered flow regulation. By making the single spool valve multi-functional rather than using separate valves for each function, the system improves controllability without proportionally increasing overall device complexity.
Solution Approach 2:
The spool valve acts as an intermediary element that translates proportional solenoid actuation into three distinct control stages. This intermediary mechanism provides smooth transitions between bypass, zero fueling, and metering conditions, improving controllability while keeping the added complexity localized to the spool assembly rather than the entire system.
3Reliability
If check valves are used to maintain bypass flow, then flow direction control is achieved, but flow capability is limited under power failure conditions
Solution Approach 1:
Instead of using check valves to force flow in one direction (which creates resistance), the bypass stage design allows low-pressure feed pump flow to naturally pass through the open inlet check valve and spool valve to the common rail. This inverted approach eliminates the need for flow to overcome check valve opening pressures, significantly improving bypass flow capability while maintaining reliable flow direction control.
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
This solution reduces overall power consumption, decreases parasitic load on the engine, and lowers specific fuel consumption by making power consumption proportional to the required fuel flow, while improving controllability and reducing leakage.
Implementation Method 1
A proportional actuator, such as a proportional solenoid magnetically coupled to the back end of the spool valve, provides selective variable displacement of the spool valve
Implementation Method 2
A bypass spring and a metering spring may be situated at the back end of the spool valve for biasing the spool valve axially toward the inlet check valve member
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An energize-to-close solenoid operated spool type inlet control valve for a high pressure fuel pump is variably positionable relative to a sleeve having three inlet feed ports and the inlet check valve member, to implement three stages of pump operation: limp-home, low-pressure flow from the low-pressure feed pump to the common rail, no flow to the common rail, and metered quantity of flow to the common rail. The spool valve includes an axially extending internal passage fluidly connected to a fluid volume at the front end of the spool valve, and a control port at the back end of the spool valve, selectively alignable to fluidly connect the ports. Two springs of different lengths either alone or together, bias the spool valve toward opening of the inlet check valve.