Fluid Delivery System Glitch Detection for Emissions Compliance
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Solution Overview
Problem
Conventional reagent dosing systems for internal combustion engines require a separate reagent level sensor to prevent urea depletion, which is costly and prone to clogging due to the formation of hard salt crystals from aqueous urea, leading to inaccuracies in fluid delivery and potential non-compliance with emissions regulations.
Innovation Solution
A fluid delivery system using a pump apparatus with an electromagnetic actuator and solenoid to accurately meter a metered dose of fluid, which includes a glitch detect circuit to determine valid pumping strokes and calculate the remaining fluid level in the supply tank, eliminating the need for a separate reagent level sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate reagent level sensor is used to prevent urea depletion, then the reliability of emissions compliance is improved, but the device complexity and cost increase, and the sensor is prone to clogging from hard salt crystals
Solution Approach 1:
The patent extracts the level sensing function from a separate physical sensor and relocates it to the control unit. The control unit determines fluid level by calculating the difference between total fluid delivered (measured by pump stroke counting) and initial fluid level, thereby eliminating the need for a separate reagent level sensor that would be prone to clogging.
Solution Approach 2:
The patent replaces the mechanical level sensor (which would physically contact the urea and be subject to clogging by salt crystals) with an electronic/software-based solution. The control unit uses electrical signals from the pump actuator to track fluid consumption and calculate remaining level, substituting a mechanical measurement system with an electronic calculation system.
2Difficulty of detecting and measuring
If a mechanical float-based level sensor is used, then the measurement function is simple, but the sensor clogs due to hard salt crystal formation from aqueous urea
Solution Approach 1:
The patent introduces an intermediary calculation process in the control unit that indirectly determines fluid level without physical contact with the urea. Instead of using a float that would clog, the system uses the pump actuator signals as an intermediary to track fluid delivery and calculate remaining level mathematically.
Solution Approach 2:
The patent creates a virtual copy of the level sensing function through software calculation rather than using a physical sensor. The control unit maintains a digital representation of fluid level by tracking delivered volume, effectively copying the level detection capability without the physical components that would clog.
3Device complexity
If pump stroke counting is used to determine fluid delivery, then the cost is reduced by eliminating level sensors, but measurement precision may be affected by invalid pumping strokes
Solution Approach 1:
The patent implements a feedback mechanism where the control unit monitors pump actuator signals and validates each pumping stroke. By comparing expected stroke patterns with actual actuator responses, the system identifies and excludes invalid strokes from the total delivery calculation, ensuring precise measurement despite potential pump variations or failures.
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 solution allows for accurate determination of the remaining fluid level and total volumetric delivery, ensuring compliance with emissions regulations and reducing the risk of system clogging, while eliminating the need for an expensive reagent level sensor.
Implementation Method 1
a pump apparatus with an electromagnetic actuator and solenoid to accurately meter a metered dose of fluid
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A fluid delivery system for delivering a metered dose of fluid from a supply tank (28) to a downstream chamber or vessel (10), comprises a pump apparatus (20) comprising a pump plunger (32) which is operable to perform a pumping stroke under the control of an electromagnetic actuator (36), including a solenoid (36a), to effect delivery of the fluid and a control unit (24) for supplying an input signal (58) to the solenoid (36a) to initiate a current flow to the solenoid (36a) and thereby initiate movement of the pump plunger (32). An electronic device (54) provides an output signal to indicate that movement of the pump plunger has stopped at the end of the pumping stroke, and a timer determines a time difference between the input signal (58) being supplied to the solenoid (36a) and the output signal being output by the electronic device (54). A processor (26) compares the time difference with a predetermined time difference and determines, as a result of the comparison, whether or not the pump plunger (32) has performed a valid pumping stroke in which an intended volume of fluid is displaced and which may therefore be used in a totalized flow calculation.