HVAC Recirculation Control for Battery Gas Ingestion Prevention
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Solution Overview
Problem
In electric and hybrid vehicles, the ingestion of contaminated ambient air, potentially containing harmful and flammable battery gases, into the passenger compartment poses a safety risk during battery failures, as HVAC systems draw in outside air that may be contaminated with vent-gas from a thermal runaway.
Innovation Solution
The HVAC system in the passenger compartment is switched to a recirculation mode upon detection of a battery failure, routing air intake from inside the compartment to prevent the ingestion of contaminated ambient air, and the system can also stop operation, initiate cooling, and trigger alarms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the HVAC system draws ambient air from the outside inlet, then the air quality in the passenger compartment is maintained through fresh air supply, but contaminated air containing battery gases may be ingested into the passenger compartment during battery failure
Solution Approach 1:
The system applies preliminary anti-action by detecting battery abnormal states (thermal runaway, fire) before contaminated air can be drawn into the passenger compartment. When such states are detected, the HVAC control unit proactively switches the air inflow channel from the outside inlet to the inside inlet, preventing the harmful effect of contaminated air ingestion before it occurs.
Solution Approach 2:
The air inflow channel acts as an intermediary that can be switched between two sources (outside inlet and inside inlet). The HVAC control unit controls this intermediary to select the appropriate air source based on battery status, thereby mediating between the need for fresh air and the risk of contaminated air ingestion.
2Object-affected harmful factors
If the HVAC system operates in recirculation mode using inside inlet, then contaminated ambient air is prevented from entering the passenger compartment, but energy consumption increases due to continuous operation of the recirculation fan
Solution Approach 1:
The system applies dynamics by making the air inflow channel switchable between outside inlet and inside inlet based on real-time battery status. Rather than operating in a fixed mode, the system dynamically adjusts its air intake source, enabling recirculation mode (inside inlet) when battery failure is detected to prevent toxic gas entry, while allowing fresh air mode (outside inlet) during normal operation to minimize energy consumption.
Solution Approach 2:
The system changes the operational parameter of the HVAC control unit based on battery status. When thermal runaway or fire is detected, the parameter switches from drawing outside air to recirculating inside air. This parameter change enables the system to prevent toxic gas entry while managing energy consumption by only activating recirculation mode when necessary.
Data Source
AI summary
Embodiments of the present invention are directed to a method and system for preventing ingestion of ambient air contaminated with possibly harmful, toxic, or flammable battery gases into a passenger compartment of a vehicle in the event of a battery failure. If an abnormal state is detected in a battery pack of the vehicle, the vehicle automatically switches the HVAC system to air recirculation mode, thereby preventing any toxic gas emitted from the battery pack from entering the passenger compartment.