Frictionless Inertia Responsive Gas Dispensing Apparatus

Abstract

Apparatus for dispensing pressurized gas in response to a change in velocity including a container having an outlet opening and a second opening aligned therewith, and a valve member for sealing both of the openings. The valve member has a large diameter piston at one end which engages an annular flange at the outlet and a smaller diameter piston at the other end which engages an annular member at the second opening. The pistons are provided with face seals and the pressure within the container holds the seals in contact with the annular flange and the annular member to seal the openings. The valve member is of sufficient mass to overcome the pressure forces and open the container in response to a predetermined change in velocity of the container. A tubular member at the second opening closely fits the smaller piston so that substantially all of the gas in the container is emptied through the outlet opening.

Description

BACKGROUND OF THE INVENTION

The present invention relates to apparatus for supplying fluid medium under pressure in response to a sudden change in velocity of the apparatus.

In recent years a great deal of attention has been devoted to safety systems and devices for protecting the occupants of passenger vehicles, particularly automobiles. One type of system which is currently being given serious consideration employs an inflatable bag or envelope which is stored in a deflated condition, usually in front of the occupant (for example under the dashboard of an automobile). When the vehicle experiences very rapid deceleration such that the occupant would be thrown forward (for example against the dash or windshield), gas stored under pressure is automatically released and the bag is inflated to restrain and cushion the occupant.

The majority of systems which have been previously proposed have employed electrically detonated explosive charges for rapidly releasing the stored gas. The explosive charge is connected to an electrical circuit which includes an inertia responsive electrical switch that closes in response to a predetermined rate of deceleration. In U.S. Pat. application Ser. No. 862,687 of John Cirillo, filed Oct. 1, 1969 and assigned to the assignee of the present application, there is disclosed apparatus for inflating such bags which does not require an explosive charge or an inertia actuated electrical switch. Instead, the container of pressurized gas is provided with an inertia actuated valve. The container is provided with an outlet opening connected to the inflatable bag and a second opening defined by a tubular formation aligned with the outlet. A valve member is positioned in the container to seal both openings. One end of the valve member is provided with a large piston which fits into the outlet opening and the other end is provided with a piston of lesser area which fits into the tubular formation. Each of the pistons is provided with an O-ring around its outer periphery to seal the openings.

To adequately protect the passenger of an automobile, it is necessary that the inertia actuated valve member respond, to inflate the bag, whenever the auto experiences a "G" loading of a magnitude and duration indicating a dangerously rapid deceleration. Since it is common for an auto to be driven for years without an accident, it is also necessary that the "G" loading required to operate the valve member not change as a result of aging of the components thereof. The valve member should always respond to a force of a given magnitude and duration whether the unit has recently been manufactured or has been sitting unused in an auto for a considerable number of years.

Sliding seals such as those disclosed in the aforementioned application exhibit a frictional force which tends to vary with the pressure within the container. Therefore, temperature changes and gas leakage would tend to effect the frictional forces in the unit. The frictional resistance of these seals also varies if the mechanical squeeze on the seal is effected by dimensioned changes such as those found within normal tolerance ranges. The effect of aging upon the resilience of the seal material is another factor which could alter the frictional resistance exhibited by the seals. It is apparent that any significant changes in the frictional resistance acting upon the inertia sensitive valve member results in a change in the magnitude and/or duration of the force required to operate the unit.

SUMMARY

Accordingly, it is an object of this invention to provide apparatus for supplying pressurized gas including an inertia actuated valve from which frictional forces affecting the operation thereof are substantially eliminated. This object is accomplished by providing such apparatus which includes a container having an outlet opening and a second opening aligned therewith, a valve member for sealing both openings, the valve member having a first end portion abutting and in sealing relationship with an inwardly facing annular surface at the outlet and having a second end portion abutting and in sealing relationship with an outwardly facing annular surface at the second opening.

DESCRIPTION OF THE DRAWING

A preferred embodiment of the invention has been chosen for purposes of illustration and description, and is shown in the accompanying drawing, forming a part of the specification, wherein:

The single FIGURE of the drawing is a longitudinal sectional view of apparatus according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawing, there is shown apparatus for supplying fluid medium under pressure which includes a container 10 and an inertia actuated valve member 11 within the container.

The container 10 is generally cylindrical and is provided with a neck 12 at one end defining an outlet opening 14 and an open-ended tubular extension 15 at the other end. The tubular extension 15 is in alignment with the outlet opening 14 and provides a second opening in the container 10. At the outlet opening 14, a flange 16 extends radially inwardly from the neck 12 providing an annular surface 17 facing the interior of the container. At the second opening, a ring member 19 is positioned within the tubular extension and provides an annular surface 20 facing away from the interior of the container. The container 10 is mounted within a vehicle with the tubular extension pointing in the direction of travel of the vehicle.

The valve member 11 includes a first end portion comprising a piston member 21 dimensioned to engage the flange 16, a second end portion comprising a piston member 22 slidably positioned within the tubular extension 15 and dimensioned to engage the ring member 19, and a rod 24 connecting the piston members.

The piston member 21 is provided with a surface 25 for abutting the inwardly facing annular surface 17 of the flange 16. An O-ring 26 recessed into the surface 25 provides a face-type seal for sealing the piston member 21 to the flange 16 to close the outlet opening.

The piston member 22 is provided with a surface 27 facing the interior of the container for abutting the annular surface 20 of the ring member 19, an O-ring 29 is recessed into the surface 27 to provide a face-type seal for sealing the piston member 22 to the ring member 19 to close the second opening. The outer diameter of the piston member 22 is dimensioned to closely approximate the inner diameter of the tubular extension 15 to minimize fluid flow through the second opening when the valve member 11 is moved into the open position.

The ring member 19 is sealed to the tubular extension 15 by means of an O-ring 30 recessed in the outer periphery of the member 19. A flange 31 is provided at the inner end of the extension 15 and a spring washer 32 is positioned between the flange 31 and the member 19 to ensure that the surface seal O-rings 26 and 29 are simultaneously in sealing relationship with their respective mating surfaces 17 and 20.

The piston member 22 carries a pressure gauge or transducer 34 and a fill valve 35, each connected to the interior of the container by suitable passageways.

The piston 21 has an effective area which is larger than the effective area of the piston 22 to produce a force normally holding the valve member 11 in the closed position shown in the drawing. The piston 22 is made to have a mass, which together with the mass of the piston 21 and the connecting rod 24, is sufficient to move the valve member into an open position in response to a dangerously rapid deceleration of the vehicle.

For use in the protection of vehicle passengers, the container 10 would normally be mounted in front of a passenger with the tubular extension pointing in the direction of travel of the vehicle. An inflatable bag would be attached to the neck 12 to be deployed toward the passenger upon inflation. The unit is pressurized through the fill valve 35 and the pressure acting on the piston 21 presses the seals 26 and 29 against the surfaces 17 and 20. The ring member 19 moves against the spring washer 32 to compensate for any difference between the distance separating the surfaces 17 and 20 and distance separating the surfaces 21 and 27.

When the velocity of the container 10 is decreased at a dangerous rate, the inertia of the valve member 11 overcomes the differential pressure acting on the piston 21 and the valve member moves to the left (as viewed in the drawing). The surface 25 moves away from the surface 17 to unseal the outlet, and, at the same time, the surface 27 moves away from the surface 20. The seals 26 and 29 present no frictional forces to retard the movement of the valve member 11.

After the initial movement of the valve member 11, the pressure within the container acts on the pistons 21 and 22 to rapidly drive the valve member to a full open position. The contents of the container is rapidly discharged through the opening 14 with only a negligible amount escaping around the piston 22 through the second opening.

It will be seen from the foregoing that the present invention provides apparatus for supplying pressurized gas including an inertia actuated valve from which frictional forces affecting the operation thereof are substantially eliminated.

Claims

We claim:

1. Apparatus for supplying fluid medium under pressure comprising in combination a container of fluid medium under pressure having an outlet opening and a second opening aligned with said outlet opening, means providing a first annular surface at said outlet opening facing the interior of said container, a valve member mounted for movement along the axis of said openings including a first portion for closing said outlet opening having a second annular surface facing said first surface for engaging said first surface to seal said outlet opening, means providing a third annular surface at said second opening facing away from the interior of said container, said valve member including a second portion at said second opening having a fourth annular surface to seal said second opening.

2. Apparatus according to claim 1 wherein a tubular formation is provided at said second opening and said second portion is formed to closely fit within said formation to prevent excess fluid flow past said second portion when said first and second valve member portions are moved away from said first and third surfaces to open said outlet openings.

3. Apparatus according to claim 2 wherein both said first and second valve member portions are provided with piston surfaces in fluid flow communication with the interior of said container.

4. Apparatus according to claim 3 wherein said piston surfaces on said first portion has a larger effective area than said piston surface on said second portion whereby said valve member is pressure biased in the closed position.

5. Apparatus according to claim 2 wherein said means for providing said third annular surface includes an annular member slidably positioned in said tubular formation and means providing a fluid medium seal between said annular member and said formation, said third annular surface being provided on said annular member.

6. Apparatus according to claim 5 including a stop member for limiting movement of said annular member toward the interior of said container and spring means between said stop member and said annular member to bias said third annular surface against said fourth annular surface.