Injection Unit Cooling for SCR Construction Machines
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Solution Overview
Problem
Construction machines equipped with SCR systems face issues of injection unit failure due to high temperatures after engine stoppage, leading to urea crystallization and clogging, and existing cooling solutions increase failure risk and cost.
Innovation Solution
A construction machine with a temperature detection unit, cooling time computing unit, and notification unit that computes and notifies the operator of the necessary cooling time before engine stoppage, preventing high-temperature failures by ensuring the injection unit is cooled before engine shutdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the engine is stopped immediately after operation, then the productivity is improved, but the injection unit temperature remains high causing urea crystallization and clogging
Solution Approach 1:
The system performs preliminary cooling action by continuing to run the engine at idle speed before actual shutdown. The control unit calculates required cooling time based on exhaust temperature and notifies the operator to maintain idle operation for this duration, ensuring the injection unit cools down before the engine is stopped, thus preventing urea crystallization and clogging
Solution Approach 2:
The system uses feedback from the exhaust temperature sensor to dynamically calculate and adjust the cooling time required. The control unit continuously monitors exhaust temperature, computes the necessary cooling duration, and provides real-time notifications to the operator, creating a closed-loop control system that adapts to actual thermal conditions
2Reliability
If a cooling system is added to cool the injection unit, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The system uses the engine's own exhaust gas to cool the injection unit naturally during idle operation. No external cooling devices or additional active cooling mechanisms are required - the thermal energy from exhaust gas and natural convection are utilized to achieve cooling, making the system self-sufficient and avoiding increased complexity
Solution Approach 2:
The system changes the operational parameter of engine speed, maintaining idle rotation during the cooling period. By controlling the engine to operate at a specific parameter state (idle speed rather than shutdown or full load), the system achieves cooling through continuous low-level operation without requiring additional cooling infrastructure
3Temperature
If urea water is injected after engine stoppage, then the dosing valve is cooled, but water evaporates and urea crystallizes causing clogging
Solution Approach 1:
The system performs preliminary cooling of the dosing valve by maintaining engine idle operation before shutdown. This preliminary action reduces the valve temperature to a safe level where urea water will not crystallize, preventing clogging before it can occur
Solution Approach 2:
The system takes preliminary anti-action by preventing the harmful condition (high temperature) before it can cause damage. By cooling the dosing valve in advance through controlled idle operation, the system prevents urea crystallization and clogging from occurring in the first place
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
Reduces the risk of injection unit failure by ensuring proper cooling before engine stoppage, preventing urea crystallization and clogging, and minimizing the risk of apparatus failure and cost associated with additional cooling systems.
Implementation Method 1
cooling of the injection unit is performed with the exhaust gas discharged from the engine
Implementation Method 2
cooling of the injection unit is performed with the exhaust gas discharged from the engine
Data Source
AI summary
A cooling time computing unit computes, based on a temperature detected by a temperature detection unit, a cooling time during which an injection unit is cooled by driving of an engine. A notification control unit uses a notification unit to notify an operator of a necessity of cooling before the engine is stopped, during the cooling time computed by the cooling time computing unit.