Liquid-Cooled Braking Resistors for Mining Equipment
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Solution Overview
Problem
Existing air-cooled braking resistor systems in mining equipment are bulky, reduce cabin space and payload capacity, and generate high noise levels due to the need for large fans to dissipate braking energy effectively.
Innovation Solution
Implementing a liquid-cooled braking resistor system where the braking current is switched through liquid-cooled resistors, with a closed-loop cooling system that circulates cooling liquid through both power modules and braking resistors, and includes auxiliary heating loops to maintain temperature control, especially at low ambient temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If air-cooled braking resistors are used, then braking energy can be dissipated, but the assembly occupies substantial volume reducing cabin space and payload capacity
Solution Approach 1:
The patent applies liquid cooling (hydraulic principle) instead of air cooling to dissipate heat from braking resistors. A liquid cooling system with coolant circulation provides more efficient heat transfer, allowing compact braking resistor design while maintaining effective temperature control during braking operations.
Solution Approach 2:
The patent changes the cooling medium from gas (air) to liquid, fundamentally altering the heat transfer parameter. Liquid coolant provides higher specific heat capacity and thermal conductivity, enabling the same cooling effect in a much smaller volume, thus resolving the contradiction between temperature control and assembly volume.
2Power
If large high-speed fans are used for air cooling, then adequate cooling power is provided, but noise levels become high posing safety hazards
Solution Approach 1:
The patent replaces mechanical air-moving devices (fans) with a liquid cooling circulation system. The coolant is pumped through channels in the braking resistors, providing efficient heat removal without requiring high-speed rotating fans, thus eliminating the noise hazard while maintaining adequate cooling power.
Solution Approach 2:
The patent substitutes the mechanical fan-based air cooling system with a liquid circulation cooling system. Instead of using mechanical force to move air, the system uses fluid dynamics and thermal conduction through liquid coolant, replacing the noisy mechanical component with a quieter fluid-based thermal management approach.
3Volume of stationary object
If liquid-cooled braking resistors are used, then volume and noise are reduced, but the system cannot operate under low ambient temperatures below the low service temperature limit
Solution Approach 1:
The liquid cooling system is designed to serve multiple functions: it cools the braking resistors during normal operation and provides heating during low ambient temperatures. By circulating heated coolant from the braking resistors to auxiliary heating loops, the system adapts to both hot and cold environmental conditions, extending its operational versatility.
Solution Approach 2:
The system uses the heat generated by the braking resistors themselves to provide auxiliary heating when ambient temperature is low. The coolant absorbs heat during braking and redistributes it to heating loops, making the system self-sufficient for both cooling and heating needs without requiring external heating sources.
4Device complexity
If air-cooled braking resistors are used, then the system is simple, but the fans generate high noise levels and reduce payload capacity
Solution Approach 1:
The patent implements a liquid cooling circulation system that, while slightly more complex than air cooling, eliminates the need for large noisy fans. The hydraulic cooling system uses pumps, coolant channels, and heat exchangers to achieve quieter operation and compact design, trading minor complexity increases for significant noise reduction and space savings.
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 reduces the volume and noise of the braking system, increases payload capacity, and extends the service life of components by efficiently dissipating heat and providing auxiliary heating, while reducing the load on radiators and dependence on external heaters.
Implementation Method 1
Heated generated by the braking resistors is transferred to a cooling liquid
Implementation Method 2
a closed-loop cooling system that circulates cooling liquid through both power modules and braking resistors
Implementation Method 3
The cooling liquid is circulated through auxiliary heating bops to heat portions of the mining equipment under low ambient temperatures
Data Source
AI summary
Braking current generated by an electrical motor on mining equipment during a retard interval is switched through one or more grid resistors that are liquid cooled. Under low ambient temperatures, a heating current can be switched through the grid resistors when the electrical motor is not operating in a retard interval. An integrated cooling system can be used to cool grid resistors and power modules. Heat dissipated by the grid resistors and the power modules can be circulated through auxiliary heating loops to heat portions of the mining equipment under low ambient temperatures. Multiple liquid-cooled power modules, liquid-cooled grid resistors, auxiliary heating loops, control modules, radiators, and pumps can be coupled by a liquid distribution system with various combinations of parallel and serial branches. Temperature, pressure, and flow rate in each branch can be independently controlled. Operation of the integrated cooling system can be controlled by a computational system.