Fluid Injector Needle With Blind Hole For Mass Flow
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Solution Overview
Problem
Conventional fluid injectors for compressed natural gas (CNG) face challenges in achieving a sufficient mass flow due to the limited needle lift, which increases the distance between the armature and pole piece, reducing operational pressure range and minimum controllable mass, especially when injecting gases with lower density.
Innovation Solution
The design incorporates a needle with a blind hole and connecting holes that provide a double passage area, allowing increased fluid flow without increasing the distance between the armature and pole piece, by enabling gas to reach the valve seat from both inside and outside the needle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the needle lift is increased to enable sufficient mass flow of gas, then the mass flow capacity is improved, but the distance between the armature and pole piece increases, reducing operational pressure range and minimum controllable mass
Solution Approach 1:
The fluid path is segmented into multiple passages: an outer passage around the needle and an inner passage through the needle (via blind hole and connecting holes). This segmentation allows the fluid to flow through multiple routes simultaneously, increasing total mass flow capacity without requiring increased needle lift that would affect actuator performance.
Solution Approach 2:
The invention adds a radial dimension to the fluid path by creating passages that extend radially through the needle body (connecting holes from outer surface to blind hole). This transforms the traditionally axial-only flow path into a three-dimensional multi-directional flow system, increasing effective flow area without increasing axial needle lift.
2Quantity of substance
If the needle lift is increased to increase the cross section for fluid passage, then the mass flow is improved, but the impact energy on reaching opening and closing positions increases
Solution Approach 1:
The fluid path is divided into outer and inner passages that operate independently. The outer passage handles the majority of mass flow while the inner passage provides additional flow capacity. This segmentation allows sufficient mass flow with reduced needle lift, thereby reducing impact energy at valve transitions.
3Quantity of substance
If the needle lift is increased to guarantee sufficient mass flow, then the fluid passage capacity is improved, but the operational pressure range decreases
Solution Approach 1:
By introducing radial passages (connecting holes) and a blind hole, the invention creates a three-dimensional flow network within the needle. This multi-dimensional passage system increases effective flow area without increasing axial needle lift, preserving the magnetic field strength and operational pressure range while achieving sufficient mass flow capacity.
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 design enhances the mass flow capacity of the fluid injector, ensuring a larger passage section for gas flow without compromising the operational pressure range or increasing the needle's impact energy, thus addressing the limitations of conventional injectors.
Implementation Method 1
When energized the actuator unit applies an electromagnetic attracting force to the needle in an axial direction by exceeding the force of the spring so that the needle is moved towards its opening position
Implementation Method 2
When de-energized, a needle is moved axially in an outward direction by means of compressed spring towards a closing position where the valve is closed
Data Source
AI summary
Various embodiments include a fluid injector comprising: an injector housing defining a fluid path; a needle within the housing and movable to a closed position and an open position. The needle comprises two axial ends, an end face on the second, and an axial needle section surrounded by the housing. Between the axial section and the surrounding housing, there is a gap comprising at least part of the fluid path. The needle includes a hole extending from the end face and a connecting hole providing fluid connection between the hole and the gap. The valve also includes a plate defining a through-hole. A first valve seat is defined at a surface of the plate facing the end face and adjoining the through-hole and when the needle is in the closed position the through-hole is closed by the end face.