Frictionless Bi-directional 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 valving device for sealing both of the openings. The valve device includes a large diameter first piston element at one end which engages an annular flange at the outlet, a smaller diameter second piston element at the other end which engages an annular member at the second opening, and a valve member moveable with respect to the first and second pistons. The first piston element has a central opening and a surrounding sealing surface facing the outlet. The valve member has a third piston element contacting this sealing surface and a fourth piston element contacting the surface of the second piston element. The third and fourth piston elements are interconnected by a rod which carries a mass element. The piston elements are provided with face seals and the pressure within the container normally holds the seals in contact with the surfaces they butt against 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 increase or decrease in velocity of the container.

Description

BACKGROUND OF THE INVENTION

The present invention relates to apparatus for supplying a fluid medium under pressure in response to a sudden change in velocity of a vehicle carrying 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. In U.S. Application Ser. No. 54,913, of John Cirillo, filed July 15, 1970, and assigned to the assignee of the present application, there is disclosed apparatus for inflating such bags which includes an inertia actuated valve responsive to either a rapid increase or decrease in velocity. In this apparatus a container of pressurized gas 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 area piston which fits into the 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. The large area piston is held in the outlet (against the differential pressure force) by a spring and is moved out of the outlet to discharge the container by motion of the valve member in either direction as a result of abrupt changes in velocity.

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 an the seal is effected by dimensional 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 the present 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 valving device for sealing both openings including a first annular piston element abutting and in sealing relationship with an inwardly facing annular surface at the outlet opening, a second piston element abutting and in sealing relationship with an outwardly facing annular surface at the second opening, and a valve member moveable with respect to the piston elements having interconnected pistons, one abutting and in sealing relationship with the outwardly facing surface of the first piston element and the other abutting and in sealing relationship with the inwardly facing surface of the second piston element.

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 drawings, forming a part of the specification, wherein:

FIG. 1 of the drawing is a longitudinal sectional view of apparatus according to the present invention in its unoperated position.

FIG. 2 is a sectional view of the apparatus of FIG. 1 in its operated position resulting from a decrease in velocity.

FIG. 3 is a sectional view of the apparatus of FIG. 1 in its operated position resulting from an increase in velocity.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawings, there is shown apparatus for supplying fluid medium under pressure which includes a container 10 and an inertia actuated valving device 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 15 pointing in the direction of travel of the vehicle.

The valving device 11 includes a first piston element 21 dimensioned to engage the flange 16, a second piston element 22 slidably positioned within the tubular extension 15 and dimensioned to engage the ring member 19, and a valve member 11 moveable with respect to the piston elements 21 and 22.

The first piston element 21 is provided with a surface 25 for abutting the inwardly facing annular surface 17 of the flange 16. An "O" ring 26 is 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 second piston element 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 28 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 "O" ring 28 is unseated. A spring 29 is positioned within the tubular extension 15 to urge piston element 22 toward the interior of the container.

The first piston element 21 is provided with a central opening 30 and an outwardly facing annular surface 31 surrounding the opening. The second piston element 22 is provided with a central bore 31.

The valve member 11 includes a piston member 32 engaging the first piston element 21, a piston member 34 engaging the second piston element 22, a rod 35 connecting the piston members 32 and 34 and extending into the tubular extension 15, and a stop member 36 mounted on the rod 35 within the extension 15.

The piston member 32 is provided with an inwardly facing surface 37 for abutting the surface 31 of first piston element 21 and carries an "O" ring 39 for providing a face seal between these surfaces. The piston member 34 has a surface 40 for abutting the inwardly facing surface 27 of the second piston element 22. An "O" ring 41 is seated in the surface 40 to provide a face seal between the two surfaces. The ring member 19 is sealed to the tubular extension 15 by means of an "O" ring 42 recessed in the outer periphery of the member 19. A flange 44 is provided at the inner end of the extension 15 and a spring washer 45 is positioned between the flange 44 and the ring member 19.

A mass member 46 is provided on the rod 35 to give the valving device 11 sufficient inertia to operate at the desired rates of deceleration and acceleration.

The effective area of the piston member 32 (the annular area defined by A.sub.2 on FIG. 1) is less than the effective area of the piston member 34 (the annular area defined by A.sub.3 on FIG. 1) so as to pressure bias the valve member 24 toward the left (as viewed in FIG. 1). The effective area of the first piston element 21 (the annular area defined by A.sub.1 on FIG. 1) combined with the area A.sub.3 is greater than the effective area of the second piston element 22 (the annular area defined by A.sub.4 on FIG. 1) combined with the area A.sub.3, so as to pressure bias the entire valving device 11 toward the right as viewed in FIG. 1. The spring 29 has sufficient strength to resist the pressure acting on the area A.sub.4 to maintain the second piston element 22 in sealing relationship with the ring member 19.

For use in the protection of vehicle passengers, the container 10 would normally be mounted in front of a passenger with the tubular extension 15 pointing in the direction of travel of the vehicle. An inflatable bag (not shown) is attached to the neck 12 to be deployed toward the passenger upon inflation. When the velocity of the container 10 is decreased at a dangerous rate, the inertia of the valving device 11 overcomes the differential pressure acting on the first piston element 21 and the entire valving device moves to the left to the position shown in FIG. 2. The surface 25 of the first piston element 21 moves away from the surface 17 of the flange 16 on the outlet 12 to unseal the outlet, and, at the same time, the surface 27 of the second piston element 22 moves away from the surface 20 of the ring member 19. The O-ring seals 26 and 28 of the piston elements 21 and 22 present no frictional forces to retard the movement of the valving device 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.

When the velocity of the container 10 is increased at a dangerous rate, the inertia of the valve member 11 overcomes the differential pressure acting on the piston member 34 and the valve member moves to the right to the position shown in FIG. 3. The surface 37 of piston member 32 moves away from the surface 31 of first piston element 21 to unseal the outlet, and the surface 40 moves away from the surface 27 of the second piston element 22, the seals 39 and 41 presenting no frictional forces to retard the movement of the valve member. The initial movement of the valve member 11 results in pressure being applied to both sides of the piston member 34 so that the pressure drives the piston member 32 rapidly to the right discharging the container.

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

Claims

What is claimed is:

1. Apparatus for supplying fluid medium under pressure in response to either an increase or a decrease in velocity comprising in combination a container of fluid medium under pressure having an outlet opening and an open ended tubular member providing a second opening, means providing a first annular sealing surface at said outlet facing the interior of said container, means at said second opening providing a second annular sealing surface facing away from the interior of said container, a first piston element adapted to be held in sealing relationship with said first surface by the pressure within said container, a second piston element, spring means holding said second piston element in sealing relationship with said second annular surface, said first piston having a central opening and a third annular surface surrounding said central opening facing away from the interior of said container, said second piston element having a fourth annular surface radially inwardly of said second annular surface facing the interior of said container, a third piston element adapted to seal against said third annular surface, a fourth piston element connected to said third piston element and adapted to seal against said fourth annular surface, and means for normally holding said third and fourth piston elements in said sealing relationship with said first and second piston elements.

2. Apparatus according to claim 1 wherein said fourth piston element has a larger effective piston surface than said third piston element to pressure bias said third and fourth piston elements toward said second opening.

3. Apparatus according to claim 2 wherein said first and second piston elements co-operate with said third and fourth piston elements to provide effective piston areas to pressure bias said first and second piston elements to seal said container.