Separable Armature Pintle Fuel Injector
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Solution Overview
Problem
Current solenoid actuated fuel injectors face issues with valve bounce at high speeds due to the large mass of the armature and return spring force, leading to unmetered after injections, and require complex and costly squeeze film damping to control air gaps, which is difficult and expensive to manufacture.
Innovation Solution
A solenoid actuated fuel injector design where the armature decouples from the pintle, maintaining a minimum air gap to avoid squeeze film damping, and introduces fluid shear damping or controlled friction to reduce valve bounce, allowing for reduced manufacturing complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the armature is connected to the pintle in known solenoid actuated fuel injectors, then the solenoid can provide sufficient opening force, but the large mass of the armature causes valve bounce at high speeds leading to unmetered after injections
Solution Approach 1:
The armature is divided into two separate components: a light armature for the solenoid and a separate pintle valve. The solenoid armature has a much smaller mass than the combined armature-pintle assembly in conventional designs, reducing inertia and preventing valve bounce. The pintle is actuated by the solenoid through a magnetic coupling mechanism rather than direct mechanical connection.
Solution Approach 2:
A magnetic field serves as an intermediary between the solenoid armature and the pintle valve. The solenoid generates a magnetic field that acts on a magnetic element in the pintle, providing force transmission without direct mechanical connection. This eliminates the inertia problem while maintaining actuation force.
2Reliability
If squeeze film damping is used to control air gaps and eliminate valve bounce, then valve bounce can be reduced, but the manufacturing complexity and cost increase substantially
Solution Approach 1:
The complex squeeze film damping mechanism with precisely controlled air gaps is completely removed from the design. Instead, the patent uses a simple mechanical stop to define the closed position of the pintle, eliminating the need for complex air gap control systems while still preventing valve bounce through the use of a light armature.
3Reliability
If the armature mass is reduced to prevent valve bounce, then valve bounce is eliminated, but the opening force capability is compromised
Solution Approach 1:
The magnetic field acts as an intermediary that can transmit force without the inertia limitations of direct mechanical connection. The solenoid generates a strong magnetic field that provides sufficient opening force on the lightweight pintle, overcoming the return spring force and hydraulic pressure without requiring a heavy armature.
Solution Approach 2:
The patent changes the physical parameters of the system by using a lightweight armature-pintle assembly with optimized mass distribution. The return spring force is also optimized to work with the reduced mass, allowing rapid valve response without valve bounce while maintaining sufficient opening force through the solenoid's magnetic field.
4Reliability
If precise air gap control is implemented for squeeze film damping, then valve bounce can be controlled, but manufacturing cost and difficulty increase significantly
Solution Approach 1:
The entire squeeze film damping system with its complex air gap requirements is extracted from the design. The patent replaces it with a simple mechanical stop that defines the closed position through direct contact, eliminating the need for precise air gap control and dramatically simplifying manufacturing.
Solution Approach 2:
Instead of using non-contact magnetic coupling throughout the stroke (which would require precise air gap control), the patent uses direct mechanical contact at the closed position through a stop. This inverts the approach from non-contact to contact-based positioning, simplifying manufacturing while still preventing valve bounce.
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 design effectively reduces valve bounce and eliminates the need for precise air gap control, enhancing performance and reducing production costs by decoupling the armature from the pintle and using alternative damping methods, thereby achieving performance comparable to piezo-electric actuated devices.
Implementation Method 1
solenoid means for selectively moving the pintle into said extended position; said solenoid means comprising an electromagnetic coil and a moveable armature capable of being acted upon by the coil
Implementation Method 2
biasing means being provided for biasing the pintle towards its retracted position
Data Source
AI summary
A fuel injector comprises an injector body having a tip portion defining a spray aperture; a pintle extending within the tip portion for axial movement between an extended position and a retracted position, the pintle having a head portion engageable with the spray aperture to close the spray aperture when the pintle is in its retracted position; biasing means being provided for biasing the pintle towards its retracted position; and solenoid means for selectively moving the pintle into said extended position; said solenoid means comprising an electromagnetic coil and a moveable armature capable of being acted upon by the coil to urge the pintle towards its extended position; wherein the pintle and armature are separable from one another whereby the armature can decouple from the pintle when the pintle moves from its extended position to its retracted position.