Patent Application
20140097260
1. Field of the Invention
The present invention relates to a thermal protection system for pressurized gas cylinders, more particularly, a fire protection system for pressurized gas cylinders used as fuel storage in vehicles.
2. Background of the Related Art
Gas cylinder designs for storing compressed gases including propane, methane and hydrogen have been developed that utilize light-weight composite materials. Composite materials are valued for their strength, but they are more susceptible to failure from exposure to high-temperatures and fire than metal tanks. The composite overwrap of a pressurized cylinder may experience structural degradation in the prolonged presence of high temperatures. High temperatures cause the resin to exceed its glass transition point and render the fiber matrix unsupported. High gas pressures within the tank exacerbate this failure mode and may lead to a gas breach within minutes of flame or high temperature exposure. Temperature-activated pressure relief devices (TPRDs) are known as a mechanism for releasing gas in the presence of a high-temperature or fire. If a TPRD reaches a certain temperature threshold, the device activates and reduces the cylinder pressure to avoid a cylinder rupture.
In the case of a localized fire in the vehicle, the heat or flame may not be near the TPRD, but at the opposing end of the cylinder or other concentrated location. The cylinder structural integrity may be compromised before the TPRD is engaged, resulting in a rupture of the cylinder. Localized fire can occur due to a fire originating from another area in the vehicle which then progresses towards the pressurized gas cylinder in a non-engulfing flame path due to the vehicle architecture.
Prior art shows the use of heat conducting mesh layers that are placed around the entire cylinder (JP20066137233A2), the use of a thermally activated fuse cord wrapped around the cylinder (U.S. Pat. No. 6,382,232), and the use of a low melting matrix alloy dispersal in connection with a TPRD (U.S. Pat. No. 6,006,774). These systems use additional materials and devices that increase the complexity and cost without addressing the undesired heating of the cylinder. The present thermal protection system is an integrated solution that provides advantages over the prior art through simplification and robustness of the localized fire mitigation for a pressurized gas cylinder on a vehicle.
The present invention improves on earlier designs by providing a low-cost pressurized cylinder thermal protection system, comprising: a pressurized gas cylinder, a temperature-activated pressure relief device coupled with the pressurized gas cylinder, a thermal concentrator integrated with an opening in a vehicle panel, the panel being located in proximity to the cylinder; and one end of the concentrator directed toward the temperature-activated pressure relief device.
Accordingly, the present invention is directed to a thermal protection system for pressurized gas cylinders in use in vehicles that substantially obviates one or more problems due to limitation and disadvantages of the related art.
An object of the present invention is to provide a thermal protection system to avoid compromise of the structural integrity of the cylinder in the event of a localized fire in the vehicle by concentrating the fire toward the TPRD, thereby engaging the TPRD, and protecting the remainder of the cylinder.
To achieve the object and other advantages, according to one aspect of the present invention, there is provided a pressurized cylinder thermal protection system, comprising: a pressurized gas cylinder, a temperature-activated pressure relief device coupled with the pressurized gas cylinder, a thermal concentrator integrated with an opening in a vehicle panel, the panel being located in proximity to the cylinder; and one end of the concentrator directed toward the temperature-activated pressure relief device.
It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
The accompanying drawings, which are included to provide a further understanding of the invention are incorporated in and constitute a part of the application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings:
A preferred embodiment according to the present invention will now be explained with reference to the accompanying drawings.
Thermal concentrator 6 may or may not be in physical contact with TPRD 4. A number of embodiments for the thermal concentrator 6 are proposed. Thermal concentrator 6 may be a metal funnel shaped shield, as illustrated in
As illustrated in
If a localized fire develops in vehicle 3 in an area away from gas cylinder 2 fuel system location, the concern arises that the structural integrity of gas cylinder 2 may be compromised or degraded to the point of rupture. To ameliorate or reduce that risk, the fire and its accompanying heat are directed and concentrated toward the TRPD 4 location so TRPD 4 is activated earlier and the pressure in gas cylinder 2 released in a controlled fashion away from the occupants and away from likely sources of combustibles. By directing the progression of the fire toward TRPD 4, the remainder of cylinder 2 is protected and the risk of rupture is greatly reduced.
Thermal concentrator 6 is integrated into body panel 8 proximate to gas cylinder 2. Fire is directed by concentrator 6 toward the fuel system location through opening 10 in body panel 8. The fire continues through thermal concentrator end 9 which is joined to opening 10, and then through thermal concentrator 6, then out through opposing end 12, which is directed toward TRPD 4. The path creation for the fire can be further directed by use of wicking material 20. Flames in proximity to wicking material 20 will cause it to ignite and be directed through thermal concentrator 6.
The system illustrated in
Additionally, a pressurized cylinder thermal protection method is disclosed wherein thermal concentrator 6 is integrated with opening 10 in vehicle panel 8. Panel 8 is located in proximity to gas cylinder 2, TPRD 4 is coupled to gas cylinder 2, and one open end 12 of concentrator 6 is directed toward TPRD 4.
The forgoing embodiments are merely exemplary and are not to be construed as limiting the present invention. The present teachings can be readily applied to other types of apparatus. The description of the present invention is intended to be illustrative, and not to limit the scope of the claims. Many alternatives, modifications, and variations will be apparent to those skilled in the art.
