Handheld NOx Sensor Tester Bypasses Vehicle CAN Bus
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Solution Overview
Problem
Testing NOx sensors in vehicle repair facilities is time-consuming and challenging due to the need for vehicles to reach stable operating conditions, and faulty readings may not accurately indicate sensor issues, as they depend on various operational variables.
Innovation Solution
A testing device that sends an unverified dew point signal to the NOx sensor, allowing it to operate without requiring a stable operating condition, and determines the sensor's status based on received signals, including NOx and O2 levels, without needing dew point detection capability, thus reducing testing time and variables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional CAN-based testing is used to ensure accurate NOx sensor readings, then measurement reliability is improved, but testing time increases significantly due to the need to reach stable operating conditions
Solution Approach 1:
The invention extracts the essential testing function from the complex vehicle operating system by using a standalone testing device that directly connects to the NOx sensor. This isolation eliminates dependencies on vehicle CAN bus, engine operation, and other sensors, allowing rapid testing without requiring stable operating conditions while maintaining measurement accuracy through direct sensor communication.
Solution Approach 2:
The testing system is segmented into an independent handheld device that separates the NOx sensor testing function from the vehicle's integrated diagnostic system. This segmentation allows the sensor to be tested in isolation with controlled input signals, eliminating the need to wait for vehicle systems to reach stable operating conditions while ensuring reliable readings through dedicated testing circuitry.
2Measurement precision
If traditional CAN-based testing is used to diagnose NOx sensor faults, then diagnostic accuracy is improved by using multiple sensors, but device complexity increases due to dependencies on other sensors and CAN operation
Solution Approach 1:
The invention extracts the NOx sensor from its dependency on the vehicle's CAN bus and other sensors by using a standalone testing device. This extraction simplifies the diagnostic system to focus solely on the NOx sensor, eliminating the complexity of coordinating multiple sensors and CAN communication while maintaining diagnostic accuracy through dedicated testing protocols and direct sensor measurement.
3Reliability
If vehicle operation is required to reach stable conditions for testing, then sensor reading reliability is improved, but productivity decreases due to extended repair time
Solution Approach 1:
The testing device provides self-service functionality by generating its own test signals and measuring responses directly, without requiring the vehicle to be operated or other systems to be functional. This self-contained approach maintains reliable sensor readings through controlled testing while dramatically reducing the time required, thereby improving repair facility productivity.
Data Source
AI summary
A testing device is capable of testing a NOx sensor in an environment that does not have dew point detection capability. The testing device includes a connector configured to be coupled to the NOx sensor, an output indicator, and circuitry. The circuitry is configured to send an unverified dew point signal to the NOx sensor via the connector and receive a sensor signal from the NOx sensor via the connector. The unverified dew point signal includes an indication that a temperature of the environment is at or above the dew point. The sensor signal includes an indication of operation of the NOx sensor in the environment. The circuitry is further configured to determine a status of the NOx sensor based on the received sensor signal and indicate, via the output indicator, the status of the NOx sensor.