Delta Pressure Sensor Ambient Port Elimination
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Solution Overview
Problem
Conventional delta pressure sensors in aftertreatment systems for IC engines are prone to failure due to exposure to moisture and particulate matter, leading to increased downtime and maintenance costs, as they require an ambient air port that can be damaged by hot exhaust gas and has rudimentary onboard circuitry with slow processing power.
Innovation Solution
The system eliminates the need for an ambient air port in delta pressure sensors, using a separate ambient pressure sensor and a more powerful controller to determine differential and relative pressures, allowing for faster data processing and reducing the risk of component damage, enabling the delta pressure sensor to be mounted at any orientation without concern for exhaust gas exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a delta pressure sensor includes an ambient air port for pressure measurement, then the sensor can determine differential pressure across the filter, but the sensor is exposed to moisture and particulate matter leading to increased failure rates
Solution Approach 1:
The system separates the ambient pressure measurement function from the delta pressure sensor. A dedicated ambient pressure sensor measures ambient pressure, while the delta pressure sensor only measures exhaust pressure differential across the filter. This segmentation isolates the delta pressure sensor from exposure to ambient moisture and particulates, reducing failure rates while maintaining measurement precision.
Solution Approach 2:
The controller acts as an intermediary that combines readings from the delta pressure sensor and ambient pressure sensor to calculate the differential pressure. This eliminates the need for the delta pressure sensor to have its own ambient air port, as the controller synthesizes the ambient reference pressure from the separate ambient pressure sensor, protecting the delta pressure sensor from harmful environmental exposure.
2Ease of operation
If the delta pressure sensor includes onboard circuitry for processing, then the sensor can determine pressures independently, but the processing power is slow leading to increased downtime
Solution Approach 1:
The pressure determination function is extracted from the delta pressure sensor and transferred to the aftertreatment controller. The controller has superior processing power and can rapidly calculate differential and absolute pressures from sensor readings, eliminating the processing bottleneck of rudimentary onboard sensor circuitry while maintaining independent pressure determination capability.
Solution Approach 2:
The aftertreatment controller serves multiple functions including engine management, emissions control, and pressure determination. By leveraging this existing multi-functional controller with its high processing power, the system eliminates the need for dedicated slow onboard processing in the delta pressure sensor, achieving fast pressure determination without adding redundant components.
3Adaptability or versatility
If the delta pressure sensor is exposed to hot exhaust gas through the ambient air port, then the sensor can function, but the sensor components are damaged leading to increased maintenance costs
Solution Approach 1:
The system uses a separate, inexpensive ambient pressure sensor that can be positioned in a safe location away from hot exhaust gas. This allows the main delta pressure sensor to be protected from thermal damage. The ambient pressure sensor can be replaced more easily and at lower cost if needed, while the expensive delta pressure sensor maintains long service life.
Solution Approach 2:
The ambient pressure sensor serves as an intermediary that provides the ambient pressure reference needed for differential pressure calculation without being exposed to hot exhaust gas. It is positioned in a safe location and transmits its readings to the controller, which combines them with delta pressure sensor readings to determine absolute pressures, eliminating the need for the delta pressure sensor to have an exposed ambient air port.
Data Source
AI summary
An aftertreatment system comprises a housing defining an internal volume. A filter is disposed in the housing and configured to remove particulate matter included in the exhaust gas. A delta pressure sensor configured to measure an inlet apparent pressure value upstream of the filter. An ambient pressure sensor separate from the delta pressure sensor is configured to measure an ambient pressure value of an ambient environment in which the aftertreatment system is located. A controller is configured to receive the inlet apparent pressure value, receive the ambient pressure value from the ambient pressure sensor, determine a relative inlet exhaust pressure value based upon the inlet apparent pressure value and the ambient pressure value, and adjust an exhaust flow rate of the exhaust gas based at least on the relative inlet exhaust pressure value.