Brake Resistor Air Heating for Fuel Cell Vehicle Braking
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Solution Overview
Problem
Vehicles propelled by electric traction motors face challenges in auxiliary braking, as it strains the cooling system, particularly in fuel cell electric vehicles and battery electric vehicles, due to the energy dissipation requirements.
Innovation Solution
A braking system that uses an electrical brake resistor arrangement connected to an air flow producing unit, where electrical power heats air before it is exhausted to the ambient environment, reducing cooling demands and incorporating an air compressor to increase pressure and temperature for enhanced energy dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If auxiliary braking is implemented in electric vehicles, then braking functionality is improved, but cooling system strain increases
Solution Approach 1:
The patent converts the harmful effect of energy dissipation during braking into a beneficial heating effect. The brake resistor arrangement dissipates electrical energy from the electric machine as heat, which is then used to heat air for the fuel cell air intake. This converts the harmful energy dissipation into a useful thermal resource, reducing cooling system strain while maintaining braking functionality.
Solution Approach 2:
The patent changes the temperature parameter of the air supplied to the fuel cell by using the brake resistor to heat the air. Instead of supplying cold air that requires cooling, the system supplies pre-heated air, thereby reducing the cooling load on the cooling system while maintaining the necessary air flow for the fuel cell.
2Reliability
If cooling capacity is increased to handle braking energy, then cooling system performance is improved, but device complexity increases
Solution Approach 1:
The patent transforms the waste heat generated during braking into a useful resource for heating the air supply to the fuel cell. The brake resistor arrangement dissipates electrical energy as heat, which is then transferred to the air stream. This converts what would be a cooling burden into a heating benefit, allowing for a reduced cooling system capacity.
Solution Approach 2:
The air flow system serves multiple functions: it provides cooling air to the electric machine, supplies air to the fuel cell, and carries the heated air from the brake resistor to the fuel cell air intake. This multi-functionality reduces the need for separate cooling and air supply systems, thereby reducing overall device complexity.
3Loss of energy
If air is heated by brake resistor, then energy dissipation is improved, but air temperature increases
Solution Approach 1:
The patent converts the heat generated by the brake resistor, which would normally be a waste product requiring cooling, into a useful thermal resource. The heated air is directed to the fuel cell air intake, where the heat can be utilized or dissipated without requiring additional cooling capacity. This converts energy loss into a beneficial effect.
Solution Approach 2:
The air flow system serves itself by carrying the heated air from the brake resistor directly to the fuel cell air intake. The same air stream that is heated by the brake resistor is then used to supply the fuel cell, eliminating the need for separate heating and cooling systems and reducing overall system complexity.
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
The system effectively reduces the cooling system's strain during braking, allowing for a downsized cooling system and increased brake capacity by 'burning off' electric energy as heated air, while optimizing the operation of components within their efficient power ranges.
Implementation Method 1
an electrical brake resistor arrangement being electrically connected to the electric source and arranged to heat air supplied from the air flow producing unit by electrical power received from the electric source
Implementation Method 2
incorporating an air compressor to increase pressure and temperature for enhanced energy dissipation
Data Source
Figure 1
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AI summary
The present invention relates to a braking system (100) for a vehicle at least partially propelled by an electric traction motor, the braking system comprising an electric machine (102) electrically connected to an electric source (104); an air flow producing unit (106) mechanically connected to, and operated by, the electric machine (102); and an electrical brake resistor arrangement (108) positioned in fluid communication between the air flow producing unit (106) and an ambient environment, the electrical brake resistor arrangement (108) being electrically connected to the electric source and arranged to heat air supplied from the air flow producing unit by electrical power received from the electric source, and to supply heated air to the ambient environment