Valve Control Method for Reducing Agent Delivery Unit
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Solution Overview
Problem
Existing delivery units for reducing agents in motor vehicles face challenges such as energy inefficiency and ice pressure issues due to the freezing of reducing agent precursors like urea-water solutions, which require energy-intensive valve operation to manage ice pressure and minimize air bubbles for precise dosing.
Innovation Solution
A method for operating a delivery unit with an electrically controllable valve that applies an activation current for a short interval to switch the valve and a lower holding current to maintain the activated position, adapting these parameters based on operating variables like pressure, temperature, and leakage to minimize energy consumption and ensure reliable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a valve is kept open to relieve ice pressure in the return line, then ice pressure is relieved, but energy is continuously consumed to maintain the valve in the activated position
Solution Approach 1:
The valve is actuated periodically with activation pulses rather than continuously. The control unit sends periodic activation signals to the valve, allowing it to open briefly to relieve ice pressure and then close, thereby eliminating continuous energy consumption while maintaining the ability to relieve ice pressure when needed.
Solution Approach 2:
The system uses the natural freeze-thaw cycles of the reducing agent to trigger valve activation. When ice forms and thaws, the resulting pressure changes and fluid movement automatically signal the need for valve activation, eliminating the need for continuous monitoring and control energy.
2Reliability
If a high activation current is applied to the valve, then the valve switches reliably, but energy consumption increases
Solution Approach 1:
Instead of applying continuous high current, the system uses periodic short-duration activation pulses. These pulses provide sufficient current to reliably switch the valve state, then reduce current to minimal levels for maintaining the state, thereby achieving reliable switching with significantly reduced overall energy consumption.
Solution Approach 2:
The control system dynamically adjusts the current profile based on the valve's operational state. High current is applied only transiently during switching events, while low holding current is used during stable states, optimizing the balance between switching reliability and energy efficiency.
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 approach reduces energy consumption while ensuring accurate and efficient delivery of reducing agents by optimizing the valve's operation based on real-time conditions, preventing ice pressure buildup and maintaining minimal air bubbles, thus enhancing the delivery unit's performance and reliability.
Implementation Method 1
a valve (1) that can be switched over by a valve that can be actuated with an electrical voltage
Implementation Method 2
The armature (10) can be held in the activated position (30) by means of a holding current (9)
Data Source
Figure 1~3
Figure 4~6
AI summary
The invention relates to a method for operating a delivery unit (2) for reducing agent, wherein the delivery unit (2) has a feed line (5) which runs from a tank (3) to a dispensing point (4) and has a return line (6) which branches off from the feed line (5), wherein the return line (6) can be closed off by a valve (1) which can be actuated by means of an electrical current. In the method, an activation current is firstly applied to the valve (1) for a first time interval (8). A holding current is subsequently applied to the valve (1) when the first time interval (8) has expired. An operating variable of the delivery unit (2) is then determined, and at least the activation current, the holding current and/or the first time interval (8) are/is adapted as a function of the determined operating variable.