Construction Machine Exhaust Filter Sensor Failure Handling
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Solution Overview
Problem
Construction machines with exhaust gas purifying devices face issues due to sensor failures, leading to incorrect particulate matter estimation and potential filter damage or malfunction during regeneration treatment, causing operational disruptions.
Innovation Solution
The system uses the EGR valve inlet side pressure sensor to substitute for the failed filter inlet side pressure sensor, allowing for continued operation by calculating differential pressures to control regeneration treatment, ensuring the construction machine can continue working even when the filter inlet side pressure sensor fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the filter inlet side pressure sensor is used to monitor particulate matter accumulation, then the regeneration treatment can be controlled accurately, but the system reliability decreases when the sensor fails
Solution Approach 1:
The EGR valve inlet side pressure sensor acts as an intermediary substitute when the filter inlet side pressure sensor fails. The control device detects sensor failure and uses the EGR valve inlet side pressure sensor to calculate differential pressure, allowing the system to continue monitoring particulate matter accumulation and controlling regeneration treatment without complete system shutdown
Solution Approach 2:
The control device changes the parameter source for differential pressure calculation from the failed filter inlet side pressure sensor to the EGR valve inlet side pressure sensor. This parameter substitution maintains the functionality of particulate matter accumulation monitoring and regeneration control despite sensor failure
2Reliability
If the failsafe control immediately limits fuel injection quantity upon sensor failure, then the filter damage is prevented, but the construction machine operation is disrupted
Solution Approach 1:
The control device performs preliminary assessment by detecting sensor failure and evaluating alternative pressure sensor availability before executing fuel injection limitation. This preliminary check allows the system to maintain normal fuel injection and operation when substitute sensors are available, while only limiting injection when no alternative monitoring is possible
Solution Approach 2:
The control device dynamically adjusts the fuel injection quantity based on the availability of functional pressure sensors. When both filter inlet side and EGR valve inlet side pressure sensors are functional, normal injection continues. When the filter inlet side sensor fails but EGR valve inlet side sensor is available, injection is maintained with alternative monitoring. When no alternative is available, injection is limited to prevent filter damage
3Reliability
If multiple pressure sensors are provided for monitoring, then the system can continue operation during sensor failure, but the device complexity increases
Solution Approach 1:
The EGR valve inlet side pressure sensor serves multiple functions: it monitors EGR system pressure differentials for EGR valve control and acts as a substitute for monitoring filter inlet pressure when the dedicated filter inlet side pressure sensor fails. This multi-functionality provides redundancy without requiring completely separate sensor systems
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 enables the construction machine to maintain operation and prevent filter damage by accurately controlling regeneration treatment even when the filter inlet side pressure sensor fails, ensuring continuous work and preventing excessive temperature rises.
Implementation Method 1
an EGR valve inlet side pressure sensor that detects a pressure in an inlet side of the EGR valve
Implementation Method 2
fuel injection for regeneration treatment, which is called, for example, 'post injection', is performed to increase a temperature of an exhaust gas and burn the particulate matter that is accumulated in the filter
Implementation Method 3
an oxidation catalyst (for example, a Diesel Oxidation Catalyst, also referred to as 'DOC' for short) for oxidizing and removing nitrogen monoxides (NO), carbon monoxides (CO), hydrocarbons (HC) and the like that are contained in the exhaust gas
Data Source
AI summary
A filter (30) traps particulate matter in an exhaust gas. A filter inlet side pressure sensor (34) is provided in an inlet side of the filter (30). An EGR valve inlet side pressure sensor (22) is provided in an inlet side of an EGR valve (20). A regeneration controller (38C) determines whether or not the filter inlet side pressure sensor (34) is in failure based upon a difference between a pressure value detected by the filter inlet side pressure sensor (34) and a pressure value detected by the EGR valve inlet side pressure sensor (22). When the filter inlet side pressure sensor (34) is in failure, the regeneration controller (38C) performs control of regeneration treatment using a differential pressure calculated based upon a pressure value detected by the EGR valve inlet side pressure sensor (22) and a pressure value detected by the filter outlet side pressure sensor (35).