Rotary Needle Fluid Injector for Urea Control
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Solution Overview
Problem
Existing urea injection systems for diesel engines lack precise control over urea injection, leading to insufficient or excessive urea discharge and clogging issues due to crystallization, which affects the efficiency of NOx reduction in exhaust emissions.
Innovation Solution
A fluid injector assembly with a rotatable needle and threaded regions, driven by a motor, allowing precise control over urea injection and prevention of clogging, featuring a fluid passageway between the inlet and outlet, and optional heating elements to ensure efficient decomposition of urea into ammonia.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If solenoid or spring activated injection nozzles are used, then the injection system is simple in structure, but precise control over the amount of urea injected is not achieved
Solution Approach 1:
The patent replaces traditional solenoid or spring activated mechanical injection systems with a motor-driven rotary injection system. The motor rotates the injection needle to precisely control the injection timing and duration, enabling accurate control over the amount of urea injected while maintaining manageable system complexity through automated control.
Solution Approach 2:
The injection system transitions from static open/closed positions to dynamic rotary motion. The injection needle rotates through specific angles to control injection duration and quantity, allowing precise adjustment of urea injection amounts based on operating conditions while maintaining a relatively simple structural design.
2Reliability
If compressed air is used for injection and atomization, then the injection process is assisted, but clogging due to crystallization cannot be fully prevented
Solution Approach 1:
The patent replaces compressed air assistance with a motor-driven rotary injection mechanism. The rotational motion of the injection needle creates sufficient atomization and flow control without requiring external compressed air, thereby preventing crystallization clogging while simplifying the overall system structure.
Solution Approach 2:
The injection system uses periodic rotary motion of the injection needle to control fluid delivery. The needle rotates in and out of the fluid stream in controlled cycles, creating periodic injection pulses that prevent stagnation and crystallization without requiring continuous compressed air flow, thus improving reliability while reducing system complexity.
3Productivity
If insufficient urea solution is injected, then the injection control is tighter, but NOx neutralization is not complete
Solution Approach 1:
The motor-driven rotary injection system incorporates control mechanisms that can adjust injection parameters based on operating conditions. By monitoring engine load, exhaust flow, and temperature, the system dynamically adjusts the rotation angle and speed of the injection needle to deliver the precise amount of urea needed for complete NOx neutralization, achieving both high productivity and precise control.
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 provides improved control over urea injection, preventing clogging and ensuring efficient NOx reduction by allowing precise adjustment of urea discharge and maintaining optimal exhaust stream temperatures for decomposition, enhancing the performance of selective catalytic reduction systems.
Implementation Method 1
a first threaded region that cooperates with a corresponding threaded region on the needle, and first and second cooperating coupling members that are arranged axially of the injector needle. The motor is configured to rotate the injector needle within the injector body which causes the threaded region of the injector to be driven in the first threaded region of the fluid injector assembly to thereby move the injector needle along a longitudinal axis
Implementation Method 2
After injection into the exhaust stream, the urea solution evaporates and mixes with the exhaust stream. The urea decomposes and hydrolyzes into ammonia.
Implementation Method 3
The urea decomposes and hydrolyzes into ammonia.
Implementation Method 4
NOx reacts with the thus generated ammonia in the presence of the catalyst and is catalytically reduced.
Data Source
AI summary
A fluid injector assembly (10) for the injection of a fluid including an injector body (14) having distal (20) and proximal ends (22), a fluid inlet (24) disposed towards the distal end, a fluid outlet (26) disposed towards the proximal end, and a fluid passageway (28) extending therebetween the inlet and the outlet. An injector needle (18) is rotatably disposed at least partially in the injector body and is moveable between an open and closed position. The proximal end (32) of the injector needle has a tip that is configured to sealably close the fluid outlet. The fluid injector assembly (10) includes a first threaded region (40) that cooperates with a corresponding threaded region (42) on the needle, and first (50) and second (52) cooperating coupling members (46) that are arranged axially of the injector needle. The first coupling member is attached to a motor (36), and the second coupling member is attached to a distal end (34) of the injector needle. The motor is configured to rotate the injector needle within the injector body which causes the threaded region of the needle to be driven in the first threaded region of the fluid injector assembly to thereby move the injector needle along a longitudinal axis of the fluid injector assembly between the open and closed positions.