Fuel Injection Device Control Chamber Segmentation for Needle Lift Stability
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Solution Overview
Problem
Existing fuel injection devices face challenges in maintaining accuracy of fuel injection quantity when increasing the needle lift amount, due to pressure pulsation and uneven biasing force from the floating spring, leading to unstable nozzle needle displacement.
Innovation Solution
A fuel injection device with a control chamber divided by a dividing wall into a backpressure chamber and an accommodation chamber, connected by a restriction hole, which stabilizes the nozzle needle displacement and prevents excessive compression of the support spring, ensuring precise fuel injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the volume of the pressure chamber is enlarged to increase the needle lift amount, then the needle lift amount increases, but the pressure pulsation period becomes longer and the fuel injection accuracy deteriorates
Solution Approach 1:
The pressure chamber is divided into a first pressure chamber and a second pressure chamber by a partition wall. The first pressure chamber has a smaller volume to minimize pressure pulsation and maintain fast response, while the second pressure chamber provides additional volume to support the required needle lift amount. This segmentation allows the system to achieve both large needle lift and high injection accuracy simultaneously.
2Quantity of substance
If the needle lift amount is enlarged, then the fuel injection quantity increases, but the floating spring is excessively compressed and the floating plate tilts causing unstable nozzle needle displacement
Solution Approach 1:
The floating spring is divided into a first floating spring and a second floating spring, with each spring supporting a portion of the load. This segmentation distributes the compression force, preventing excessive compression of a single spring and maintaining the stability of the floating plate even when large needle lift amounts are required.
3Quantity of substance
If the needle lift amount is increased, then the fuel injection quantity increases, but the biasing force of the floating spring becomes uneven causing the floating plate to tilt
Solution Approach 1:
The floating spring is segmented into multiple springs (first floating spring and second floating spring) positioned at different locations. This distribution of spring forces ensures uniform biasing force across the floating plate, preventing tilting and maintaining stable operation during large needle lift movements.
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 achieves high accuracy in fuel injection quantity by shortening the pulsation period of fuel pressure and maintaining proper posture of the movable plate, allowing for increased needle lift while maintaining stability and accuracy.
Implementation Method 1
a biasing member which is accommodated in the control chamber in such a manner as to bias the closing member toward the opening wall
Implementation Method 2
The dividing wall portion has a restriction hole fluidly connecting the accommodation chamber and the backpressure chamber with each other
Data Source
AI summary
A fuel injection device is provided with a valve body, a nozzle needle, a movable plate, and a support spring. The valve body has a control chamber therein. The control chamber is defined by a defining wall which has a dividing wall portion. The dividing wall portion divides the control chamber into an accommodation chamber and a backpressure chamber. The accommodation chamber accommodates a movable plate and a support spring. A fuel pressure in the backpressure chamber is applied to the nozzle needle. The dividing wall portion has a restriction hole fluidly connecting the accommodation chamber and the backpressure chamber with each other, and a support surface supporting the support spring.