Abstract:
A device is disclosed for very rapidly releasing fluid under pressure from a reservoir in which a sharpened pin is driven at an angle into the center of a sealing diaphragm to release the fluid under pressure from the reservoir.

Description:
BACKGROUND OF THE INVENTION 
     This invention concerns devices for rapidly releasing fluid under pressure from a reservoir. So called &#34;air bag&#34; safety cushion devices used in auto vehicles rely on very rapid inflation of an air bag at the moment a serious collision occurs. Testing and development of these systems require numerous test inflations to be carried out, but since pyrotechnic devices are typically employed in actual air bag inflations, such tests are costly and require licensed facilities. 
     It is difficult or impossible to simulate the gas flow in such systems with reservoirs opened with conventional valving due to the very high rates of flow occurring almost instantaneously when an air bag system is activated. 
     There are other applications where a very rapid opening of a fluid passage would be desirable, preferably with a simple, reliable device. 
     There has heretofore been employed various bursting pieces associated with pressure release discs, but these have been relatively bulky members partially blocking flow in the discharge passage. 
     SUMMARY OF THE INVENTION 
     The present invention comprises a frangible sealing disc or diaphragm installed in a passage extending from the high pressure reservoir. A puncturing pin is mounted on the downstream side of the disc inclined at an angle so that its longitudinal axis intersects the center of the disc, the disc distended as by preforming and/or the exertion of the pressure in the reservoir towards its downstream side. A selectively operable driving means is associated with the pin to enable driving of the pin to force a sharpened end into the distended center of the disc. Penetration of the center of the disc by the sharpened end causes rupturing along radial lines prescored into the disc. 
     The rupturing disc releases fluid under pressure from the reservoir very rapidly which has been found to closely simulate the flow characteristics of typical gas generators used in air bag restraint systems. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a transverse sectional view of the device according to the present invention. 
     FIG. 2 is a plan view of the rupture disc incorporated in the device shown in FIG. 1. 
    
    
     DESCRIPTION 
     In the following detailed description, certain specific terminology will be employed for the sake of clarity and a particular embodiment described in accordance with the requirements of 35 USC 112, but it is to be understood that the same is not intended to be limiting and should not be so construed inasmuch as the invention is capable of taking many forms and variations within the scope of the appended claims. 
     FIG. 1 shows a release conduit 10 in communication with a pressure reservoir 12, shown diagrammatically. The conduit 10 is sealed by a diaphragm 14 having its periphery clamped between flange 16 of conduit 10 and flange -8 of a housing 20, these flanges secured together with threaded fasteners 22. 
     The diaphragm 14 is disc shaped and may be of various materials such as metal or plastic, designed with a thickness to be of sufficient strength to normally withstand whatever pressure exists in reservoir 12. The diaphragm 14 is scored with radially extending score lines 24 (FIG. 2) which intersect at the center 26 of the diaphragm 14. The diaphragm 14 is also formed with a dished or distended bulge feature 28 located on the downstream side as installed. 
     The housing 20 has an internal cavity 21, and is secured to a discharge conduit 30 by means of mating flanges 32, 34 and threaded fasteners 36 
     The discharge conduit 30 receives flow from cavity 21 of the housing 20, and directs outflow to a downstream device 38 which utilizes the outflow, such as an air bag installation to be test deployed. 
     An elongated pin 40 is installed extending through a sidewall of the housing 10, inclined at an acute angle as shown so that its longitudinal axis intersects the bulged center 36 of the diaphragm 14. The sharpened tip 42 of the pin 40 is directed towards the diaphragm 14, but normally held retracted as shown in FIG. 1 by a compression spring 44 contained in a plunger housing 46 engaging a plunger head 48 of the pin 40 to urge it to the retracted position shown. The housing 46 is vented at 50 to insure free movement of the pin 40 in the housing 46. 
     An actuator 52 is provided, selectively operable to drive the pin 40 so to cause the sharpened end 42 of pin 40 to penetrate the center 36 of the diaphragm 14. A suitable actuator may take many forms, such as a pneumatic device, or a mechanical spring operated device as are used to drive firing pins in firearms. Penetration of the center 36 of diaphragm 14 causes the diaphragm 14 to burst under the pressure contained in the reservoir -2, tearing open along the score lines 24, the segments peeling back in flower petal fashion against the interior of the housing 20, to allow immediate release of the gas under pressure in the reservoir 12. The spring 44 causes retraction of the pin 40 so that a substantially unimpeded flow path is afforded for discharge of the fluid under pressure in the reservoir 12. 
     It has been found that this device provides a discharge flow characteristic similar to the gas generators used in air bag systems in that a very rapid valvelike action is achieved. 
     At the same time the device is simple and reliable and may be manufactured at low cost. 
     Variations in thickness and material of the diaphragm 14 may be used to vary the discharge flow characteristics for a particular application.