Blowout latch

Details Blowout latch Blowout latch

2002-06-18

2004-06-29

Miller, William L. (Department: 3677)

Closure fasteners

Bolts

Hooked end

C292S247000, C292S341120, C292SDIG001, C244S129400, C244S05300R, C244S11000H

Reexamination Certificate

active

06755448

ABSTRACT:

BACKGROUND
This disclosure relates to latching mechanisms for securing an aircraft panel to an aircraft structure. In particular, the present disclosure relates to latches which disengage when a predetermined load is exceeded.
A disengageable latch, or blowout latch, disengages when the pressure against a panel, to which the blowout latch is mounted, exceeds a predetermined limit. Aircraft employ many types of latches including blowout latches to secure aircraft panels to adjacent aircraft structures. For example, blowout latches are used to secure panels enclosing an aircraft's engine. When used in such an environment, the blowout latch opens and relieves pressure which is built up inside the engine enclosing structure defined by the panels due, for example, to the jet exhaust stream flowing through the jet engine. The opening of the blowout latch allows the panels to pivot open and vent the excessive pressure thus preventing any damage due to excessive loads on the panels or other structural components.
A variety of such blowout latches are available which include devices which require a tool for opening or have a trigger for opening the latch. Additionally, latches are available which allow the handle to pivot outwardly thereby indicating that the latch has been disengaged by excessive loads or “blown”.
One element that is relatively consistent in the blowout latch mechanisms is the use of a biasing mechanism to impose force upon a bolt of the latching mechanism. The biasing mechanism applies a force in relation to the spring force of the spring used in the mechanism. This retains the bolt in engagement against another structure such as the structural portion of the aircraft against which when the panel is closed. When a force which is greater than the biased load against the bolt occurs against an interior surface of the panel, the panel is blown. In other words, the bolt is retained against the blowout force until the blowout force is exceeded whereupon the biasing mechanism is compressed or otherwise exceeded thereby releasing the panel under the force exerted from within the enclosed area.
A problem arises when the latching mechanism must be disengaged in order to open the panel. For example, it is desirable to selectively disengage the panel for maintenance, inspection and other activities. In other words, prior art blowout latches are difficult to selectively disengage because the biasing load or force applied against the bolt must be overcome in order to disengage the latch. For example, if the spring loaded force on the latch is 150 pounds, at least 150 pounds of pressure must be applied to the handle to disengage the latch from the abutting structure. It can be difficult to disengage the handle when overcoming such forces. This situation can be exacerbated depending upon the strength and size of the person opening the panel.
As such it would be desirable to provide a latching mechanism which eliminates the need to overcome the biasing force used to retain the panel against blowout forces.
According to the present disclosure, a pressure relief or blowout latch is provided for latching a first panel to a second panel. The latch is releasable under pressure when overcoming a biasing force of a biasing mechanism of the latch or by selective disengagement by bypassing the biasing mechanism with relatively little force. The latch includes a roller movable between an engaged position in contact with the second panel and a disengaged position spaced-away from the second panel. The latch further includes a shaft coupled to the roller for rotational movement with the roller about an axis along the shaft. A handle support of the latch is provided for rotational movement with the shaft and the roller. A bolt is coupled to the shaft and includes a channel for receiving at least a portion of the handle support. The handle support is rotatable relative to the bolt. The latch further includes a trigger and a biasing mechanism. The trigger includes a pin normally engaged with the bolt and the handle support and is selectively movable to release the pin from engagement with the handle support and the bolt. Release of the pin permits the handle support to move relative to the bolt to rotate the shaft and roller to move the roller to the disengaged position. The biasing mechanism is normally engaged with the bolt to prevent the bolt from rotating about the axis. The bolt is configured to disengage the biasing mechanism when internal pressure on the roller is translated to the bolt through the shaft, handle support, and pin.
The latch of the disclosure further includes a roller assembly rigidly coupled to the shaft for rotation therewith. The roller assembly includes a generally “L-shaped” arm having a first end coupled to the shaft and a second end coupled to the roller.
The latch further includes a second roller assembly.
The bolt of the latch includes an aperture and a portion of the shaft is received within the aperture for rotational movement of the shaft relative to the bolt. The bolt further includes a notch and a portion of the biasing mechanism is received within the notch. The biasing mechanism includes a pin received within the notch of the bolt, a slide coupled to the pin, a spring configured to bias the pin into engagement with the bolt, and an adjuster to adjust the compression of the spring. The adjuster as disclosed is a threaded screw.
The bolt further includes a ledge normally engaged with the pin of the trigger and the handle support includes a ledge normally engaged with the pin to position the pin between the handle support and the bolt.
The latch further includes a housing coupled to the first panel and a handle pivotally coupled to the housing. The trigger is pivotally coupled to the handle and includes a spring to bias a body of the trigger to an upright position where the pin of the trigger is engaged with the bolt and the handle support. Pivoting movement of the trigger against the spring of the trigger from the upright position to a depressed position disengages the pin from the handle support and the bolt to permit the handle to rotate relative to the housing. The handle support is pivotally coupled to the handle. Movement of the handle carries the handle support and urges the handle support to pivot about the axis to rotate the shaft to move the roller to the disengaged position.
The handle support as disclosed includes an aperture for receiving a portion of the shaft. The shaft includes an aperture generally perpendicular to the axis and the latch further includes a pin received within the shaft to rigidly couple the shaft to the handle support.
The blowout latch as disclosed includes structures which function to disengage the biasing force within the latch, thus, allowing the latch to be disengaged with relatively little force. The latch, even though disengaged, maintains the biasing load on the bolt even when the latch is selectively opened and disengaged from the corresponding aircraft structure. In use, the blowout latch as disclosed allows a person to activate the trigger disengaging the handle support, coupled to the releasable handle to disengage corresponding roller assemblies which are coupled to the handle support. When the handle and handle support are returned to a closed position the associated roller assembly can once again be engaged with the corresponding second panel. The bolt is not disengaged when the blowout latch is selectively opened. Instead, the bolt is retained in the loaded position with the biasing mechanism maintaining a load on the bolt. When excessive forces are exerted on an interior surface of the first panel to which the latch is attached, the biasing forces of the biasing mechanism are exceeded thereby causing the roller assembly to operate to move the bolt to disengage the handle causing disengagement of the first panel from the second panel.
Additional features of the disclosure will become apparent to those skilled in the art upon consideration of the following detailed description of an embodiment exemplifying a

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