Fuel Injection Valve Movable Core Gap Configuration
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Solution Overview
Problem
Conventional fuel injection valves face challenges in maintaining consistent valve opening response and injection amount due to variations in flow resistance and moving speed, especially with increasing fuel pressures, which require a large valve opening force and can lead to variations in the time period for valve opening and closing operations.
Innovation Solution
The fuel injection valve design incorporates a movable core with a cylindrical shape and a holder chamber filled with fuel, featuring a press-fit and non-press-fit region with specific gap configurations to minimize flow resistance variations, allowing for reduced variation in moving speed and valve opening response, and includes a stopper member to restrict movement away from the nozzle hole.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If fuel pressure is increased to improve injection performance, then injection pressure is improved, but valve closing force increases requiring larger valve opening force
Solution Approach 1:
The movable core is divided into two separate cores: an inner core and an outer core. These two cores move independently within the holder, allowing the inner core to be optimized for magnetic attraction response while the outer core is optimized for minimizing flow resistance. This segmentation enables each core to perform its specific function efficiently without compromising the other.
Solution Approach 2:
The outer core is designed with different gap configurations at different locations: a first gap configuration near the nozzle hole and a second gap configuration away from the nozzle hole. This local quality variation allows the outer core to minimize flow resistance in critical areas while maintaining structural integrity and magnetic circuit efficiency in other areas.
2Speed
If gap between holder and movable core is reduced to improve response speed, then valve opening response is improved, but flow resistance variation increases
Solution Approach 1:
The movable core is divided into an inner core and an outer core that move independently. This segmentation allows the outer core to maintain a larger, more consistent gap with the holder, reducing flow resistance variation, while the inner core provides the necessary magnetic attraction response through its own magnetic circuit.
Solution Approach 2:
The outer core features different gap configurations at different locations: a first gap configuration near the nozzle hole and a second gap configuration away from it. This local quality approach optimizes flow resistance characteristics in different regions, ensuring consistent performance throughout the valve operation cycle.
3Device complexity
If single core structure is used to simplify design, then device complexity is reduced, but moving speed variation occurs due to flow resistance
Solution Approach 1:
The movable core is divided into an inner core and an outer core that move independently within the holder. The outer core is specifically designed to minimize flow resistance variation by maintaining optimized gaps with the holder, while the inner core provides magnetic attraction response. This segmentation allows each component to be optimized for its specific function, resulting in more consistent moving speed.
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 reduces variation in valve opening response and injection amount by minimizing the influence of gap variations on flow resistance, enabling consistent fuel injection even under high fuel pressures.
Implementation Method 1
a fixed core that generates a magnetic attraction force upon energization of a coil; a movable core that has a cylindrical shape and opens the nozzle hole by moving together with the valve body by the magnetic attraction force
Data Source
AI summary
A fuel injection valve includes a valve body, a fixed core, a movable core, a holder, and a stopper. The movable core has an inner core that contacts the stopper, and an outer core press-fitted to an outer peripheral surface of the inner core. The outer core has, in a moving direction of the movable core, a press-fit region which is press-fitted to the outer peripheral surface of the inner core, and a non-press-fit region which is not press-fitted to the outer peripheral surface of the inner core and is adjacent to the press-fit region in the moving direction. Between the inner peripheral surface of the holder and the outer peripheral surface of the movable core, the smallest gap in the press-fit region is larger than the smallest gap in the non-press-fit region.