Explosion-Proof Breather Valve for Power Batteries in Electric Buses — Preventing Pressure Buildup During Thermal Runaway

Electric buses are powered by onboard batteries and are mainly used for facilitating convenient transportation such as urban commuting, intercity travel, long-distance tours, organized group outings, business events, and sightseeing receptions. These buses play a vital role in diversifying China's transportation energy structure, safeguarding national energy security, reducing vehicular emissions, promoting sustainable social development, enhancing the independent innovation capability of the automotive industry, and driving the leapfrog development of the sector.

To achieve a high degree of water and dust protection, electric bus battery enclosures are designed with excellent sealing. However, such airtightness may lead to safety issues. When lithium-ion cells experience overcharge, over-discharge, or are pierced by sharp objects, individual cells can undergo sudden thermal runaway, releasing large amounts of gas and particulates into the enclosure. This causes a rapid pressure buildup inside the battery box. If the internal pressure exceeds the enclosure’s threshold, the resulting pressure differential may cause a sudden and violent explosion of the battery box.

To address this issue, PUW has developed a new Explosion-Proof Breather Valve for Power Batteries in Electric Buses, designed to prevent pressure buildup during thermal runaway, rapidly vent gas, and balance the internal and external pressure of the enclosure.

Key Features of the PUW Explosion-Proof Breather Valve:

• Basic explosion-proof functionality: Enables rapid pressure relief and explosion venting.

• Compact design: Easy to install, highly reliable, and broadly adaptable.

• Effective pressure and temperature management: Quickly expels gases when internal battery pack pressure or temperature rises, preventing explosions.

Technical Specifications:

• Air Permeability Before Rupture: ≥3000 ml/min @ 7KPa (normal airflow)

• Air Permeability After Rupture: ≥1000 L/min @ 14KPa (airflow after reaching explosion pressure)

• Explosion Pressure (customizable): 7 ± 3 KPa

• Low-pressure rupture (5~10 KPa)

• Medium-pressure rupture (15~20 KPa)

• High-pressure rupture (30 KPa and above)

• Available in:

• Temperature Resistance Range: -40°C to +150°C

• Model: PBA4K-50-7KPa

• Flame Retardancy: UL 94-V0

• Ingress Protection: IP68 (submerged in 1m water for 48 hours), IP6K9K

• Patent Numbers:

• ZL201621184072.7

• ZL201730127882.2

• ZL201821571934.0

Core Functions:

• Pressure balancing

• Waterproof and breathable explosion protection

• Pressure relief and gas exhaust (ensures pressure equilibrium inside and outside the battery pack)

• Micro heat dissipation under extreme temperatures