Fuel Injector Check Speed Control for Rate Shaping
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Solution Overview
Problem
Existing common rail fuel injection systems lack flexibility in achieving desired injection characteristics such as split injections, square front end injection rate shapes, and abrupt end injection events, which are necessary to effectively reduce undesirable emissions across various engine operating conditions.
Innovation Solution
The fuel injector incorporates a check speed control device with a fixed position within the check control chamber, featuring an upper and lower bowl and an orifice, which controls the speed of the check needle during injection events by restricting fluid flow, allowing for ramp-shaped injection profiles at both the beginning and end of injection events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a pilot operated admission valve is used to control injection timing and quantity, then threshold controllability is achieved, but the ability to produce diverse injection characteristics (split injections, square front end, abrupt ending) is limited
Solution Approach 1:
The injection control function is segmented into multiple independent control mechanisms: a check needle for basic injection control, a check speed control device with adjustable orifices for rate shaping, and an electrical actuator for timing control. This segmentation allows each component to specialize in specific injection characteristics, enabling diverse profiles (ramp, square, abrupt) without compromising threshold controllability.
Solution Approach 2:
The check speed control device incorporates adjustable orifices that can dynamically modify the closing speed of the check needle. By varying the orifice size or positioning, the system can adapt the injection rate shape in real-time, transforming from a static control system to a dynamic one that can produce multiple injection characteristics from a single injector design.
2Manufacturing precision
If a fixed check speed control device with orifice is used to control check needle speed, then ramp-shaped injection profiles are achieved, but the ability to produce abrupt ending and square front end injection is reduced
Solution Approach 1:
The system changes the physical parameters of the check speed control device, specifically the orifice size and positioning, to achieve different injection profiles. By adjusting these parameters, the same basic device can produce ramp-shaped, square front end, and abrupt ending injection characteristics, demonstrating parameter-based adaptability rather than requiring multiple fixed devices.
Solution Approach 2:
The check speed control device is designed with universal functionality to handle multiple injection rate shapes. The adjustable orifices enable a single device to serve multiple purposes: controlling ramp profiles, square front ends, and abrupt endings, thereby eliminating the need for separate control devices for each injection characteristic.
3Extent of automation
If electronically controllable admission valve or direct control needle valve is used in common rail systems, then threshold control independent of crank angle is achieved, but maximum flexibility in injection characteristics remains elusive
Solution Approach 1:
The invention merges the electrical actuator for timing control with the check needle mechanism and check speed control device into a unified injector assembly. This combination allows the electrical actuator to provide automated timing control while the check needle and speed control device provide rate shaping capability, achieving both automation and flexibility simultaneously.
Solution Approach 2:
The check needle acts as an intermediary between the electrical actuator and the nozzle outlet. It translates electrical control signals into mechanical motion while the check speed control device mediates the flow rate characteristics. This intermediary mechanism enables the system to achieve both automated timing control and flexible injection characteristics through the coordinated action of multiple components.
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 enables the production of ramp-shaped injection profiles at both the front and back ends of injection events, providing more flexibility and precision in emission reduction, independent of engine operating conditions, while maintaining control over injection timing and quantity.
Implementation Method 1
a check speed control device fixedly positioned within the check control chamber and having an upper bowl, a lower bowl and at least one orifice through the lower bowl
Implementation Method 2
The check needle further including at least one opening hydraulic surface exposed to a fluid pressure of the nozzle supply passage and at least one closing hydraulic surface exposed to a fluid pressure of the first check control chamber
Data Source
AI summary
A common rail single fluid injection system includes fuel injectors ramp shaped injection curves at both the front and back ends of an injection event. This is accomplished by including a check speed control device fixed in position within the check control chamber of a fuel injector. The check speed control device controls the speed of a check by restricting fuel flowing into and out of the check control chamber.