Urea Water Pump Gravity Drainage for Construction Machine Exhaust Purification
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Solution Overview
Problem
Conventional technologies for construction machines fail to prevent urea water from freezing in the return conduit line, leading to reduced reliability and stability in exhaust gas purification, especially in low-temperature environments, due to either increased costs from heaters or incomplete return of urea water to the tank.
Innovation Solution
The urea water pump is arranged above the urea water tank, and the return conduit line is positioned vertically between the pump and the tank, allowing urea water to drain back into the tank by gravity when the pump is stopped, preventing freezing and enhancing purification treatment reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heaters are disposed in the return conduit line to prevent freezing, then freezing prevention is achieved, but device complexity and cost increase
Solution Approach 1:
The patent removes the heater components from the system by utilizing the natural gravitational force to drain urea water from the return conduit line. This extraction of unnecessary heating components resolves the contradiction by achieving freezing prevention through a simpler, passive gravitational drainage mechanism rather than active heating elements.
Solution Approach 2:
The system uses the gravitational force and the pump's reverse rotation capability to automatically drain urea water from the return conduit line without requiring external heating assistance. The pump itself serves the dual function of both pressurizing urea water during operation and draining it during shutdown, making the system self-sufficient for freezing prevention.
2Reliability
If the pump is positioned above the tank with vertical return conduit, then urea water drains back by gravity preventing freezing, but device complexity increases due to installation requirements
Solution Approach 1:
The patent positions the pump above the tank to create a gravitational potential difference that enables urea water to drain back into the tank automatically. This equipotentiality principle utilizes gravity as the driving force, eliminating the need for additional drainage pumps or complex valve systems, thereby resolving the contradiction between freezing prevention and installation simplicity.
3Ease of manufacture
If conventional pump positioning is used, then installation is easier, but urea water remains in the return conduit line and freezes
Solution Approach 1:
The patent inverts the conventional pump positioning by placing the pump above the tank instead of below or at the same level. This inversion creates a downward gravitational flow path for urea water in the return conduit line, ensuring complete drainage and preventing freezing. This inverted positioning resolves the contradiction by prioritizing reliability through freezing prevention while maintaining reasonable installation feasibility.
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 configuration effectively prevents urea water from freezing in the return conduit line, improving the reliability and stability of exhaust gas purification and reducing the need for additional heating components, thus lowering costs and extending conduit line lifespan.
Implementation Method 1
a urea water pump that delivers the urea water reserved in the urea water tank to the urea water injection valve
Implementation Method 2
a cooling fan that is arranged in one side in a left-right direction of the engine and suctions external air as cooling air
Implementation Method 3
a heat exchanger that is arranged to face the cooling fan to be positioned in the upstream side in the flow direction of the cooling air by the cooling fan
Implementation Method 4
the return conduit line is positioned vertically between the pump and the tank, allowing urea water to drain back into the tank by gravity when the pump is stopped
Data Source
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AI summary
An exhaust pipe (7A) in an engine (7) is provided with an exhaust gas purifying device (10) with a urea selective reduction catalyst (13A) removing nitrogen oxides in an exhaust gas. The exhaust gas purifying device (10) is provided with a urea water injection valve (14) that injects urea water as a reducing agent to the upstream side of the urea selective reduction catalyst (13A). The urea water injection valve (14) is connected to a urea water tank (22) through a urea water pump (25). The urea water pump (25) is arranged in an upper side to the urea water tank (22). A return conduit line (30) in which the urea water flows from the urea water pump (25) toward the urea water tank (22) is disposed in an upper-lower direction between the urea water pump (25) and the urea water tank (22).