Urea Water Supply Device Mounting on Construction Machine Frame
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Solution Overview
Problem
The urea water supply system in construction machines experiences instability in urea water injection due to varying elevation differences between the urea water supply device and injection valve, leading to inconsistent discharge pressure and freezing issues in cold conditions, compounded by inefficient thermal insulation and maintenance challenges.
Innovation Solution
The urea water supply device is installed on a connection frame member facing the engine, reducing vertical distance variations and utilizing existing structural elements for efficient mounting, with a thermal insulating cover designed to keep connection portions warm using engine cooling water heat, enhancing maintenance accessibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the urea water supply device is placed on the urea water tank, then the urea water tank can be positioned distant from the engine for overheating prevention and replenishing facilitation, but the piping length becomes long and discharge pressure varies significantly when the machine tilts
Solution Approach 1:
The patent introduces a thermal insulating cover as an intermediary element between the urea water supply piping and the surrounding environment. This cover prevents heat loss from the urea water in the piping, maintaining its temperature and preventing freezing without requiring the piping to be positioned near the engine or other heat sources, thus resolving the contradiction between temperature stability and discharge pressure stability.
Solution Approach 2:
The thermal insulating cover is designed to be self-contained, providing thermal insulation to the urea water supply piping without requiring external heat sources or active heating systems. The cover maintains the temperature of the urea water through passive insulation, allowing the system to serve itself thermally while maintaining stable discharge pressure.
2Temperature
If a thermal insulating cover is provided at the connector portion of the urea water tank, then the connector portion is protected from temperature reduction, but the structure becomes more complex and maintenance becomes difficult
Solution Approach 1:
The thermal insulating cover is designed as a segmented structure with an removable cover portion that can be separated from the main body. This segmentation allows the cover to provide thermal insulation while enabling easy access to the connector portion for maintenance and inspection, resolving the contradiction between temperature protection and maintenance accessibility.
Solution Approach 2:
The thermal insulating cover incorporates a movable or removable cover portion that can be opened or closed as needed. This dynamic design allows the system to switch between providing thermal insulation during operation and allowing access for maintenance, thus resolving the contradiction between temperature maintenance and ease of repair.
3Temperature
If cooling water piping is laid along urea water supply piping to warm the urea water, then freezing is prevented, but the piping cannot be connected at connector portions where thermal insulation is needed
Solution Approach 1:
The thermal insulating cover acts as an intermediary that provides thermal protection to the urea water supply piping without requiring direct contact with heat sources like cooling water piping. This eliminates the need for complex piping arrangements where cooling water pipes must be routed alongside urea water pipes, simplifying the overall system while maintaining temperature stability.
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 ensures stable urea water injection with minimal pressure variation, prevents freezing, and simplifies maintenance by using existing structural elements and efficient thermal insulation, maintaining operational reliability in varying conditions.
Implementation Method 1
a thermal insulating cover designed to keep connection portions warm using engine cooling water heat
Data Source
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AI summary
In a NOx selective catalytic reduction device that purifies NOx in exhaust gas exhausted from an engine (10), a urea water supply system is constructed of a urea water injection valve (20), a urea water tank (24), urea water supply piping (22) and a urea water supply device (30), a connection frame member (3d) is provided on a revolving superstructure (2, 3) to extend in a longitudinal direction in a center in a width direction to reinforce the revolving superstructure and to be located between a pair of main frame members (3b, 3b) that connects a working device (4) so that a rear side faces the engine, the urea water tank is placed on the revolving superstructure on a front side from a center of revolution of the revolving superstructure, the engine is placed on the revolving superstructure on a rear side from the center of revolution of the revolving superstructure, and the urea water supply device (30) is installed on the connection frame member (3d) to face the engine.