Agent Ref 74214/00002

GAS VALVE WITH HIGH SPEED OPENING AND HIGH SPEED GAS FLOW CAPABILITY

CROSS REFERENCE TO PRIOR APPLICATIONS This application claims priority from US Application No. 60/935,965, filed on September 7, 2007, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The invention relates to gas valves with high speed opening and high speed gas flow capability.

BACKGROUND ART

Gas valves with high speed opening and high speed gas flow capability are required for various uses, for example in cold gas airbag inflation test systems for testing automobile airbags that protect occupants of the automobile in the event of a collision. Specifically, airbag deployment systems basically include an airbag and an inflator. The inflator generates and releases the gas necessary to inflate the airbag. During a collision in an automobile, the inflator is triggered by the destruction of a rupture disc, which releases the gas to fill the airbag in a mere fraction of a second. Even a small change in the orientation of a vehicle's dash board could have a significant effect on the deployment of an airbag since the deployment occurs so quickly. As a result, many tests must be performed throughout the design or re-design process of an automobile to ensure that the deployment of the airbags meet all regulations or requirements. The rupture discs are permanently destroyed in automobile airbag systems so the airbags must be completely replaced after use. It is therefore not feasible to use actual airbag systems to run large numbers of tests while designing a vehicle.

Instead, a separate, re-usable valve apparatus is desired to simulate the destruction of the rupture disc and subsequent inflation of the airbag. Such a valve must perform consistently and accurately so that it does not skew data being collected or introduce error into the tests. These valves must also deploy extremely quickly to properly simulate actual airbag deployment. A typical simulation gas valve

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Agent Ref 74214/00002 inflator, for example, may need to consistently open a one inch diameter valve in 2ms. At the present time, suitable gas valves for this purpose do not appear to be commercially available which can properly simulate actual airbag deployment in a nondestructive manner. For example, United States Patent No. 4,635,855 (Kuyel et al.) teaches a method and apparatus for rapidly controlling a flow of gas which utilizes a conductive disc to seal an orifice of a plenum holding the gas, and an electrode located proximate to the plate. By applying a current through the electrode, an eddy current is induced in the disc, which creates a repulsion force that repels the disc away from the electrode for opening the orifice. However, to open the orifice, the repulsion force must overcome a force due to pressure of the gas stored in the plenum, and therefore, is too slow and inconsistent to be used in an airbag deployment simulation. Furthermore, the apparatus taught in this reference would open even slower, or perhaps not at all, when used with gases having significantly high pressures, as the repulsion force would have to be incredibly high to overcome the force due to pressure.

Similarly, Japanese Patent Publication No. JP58191380 (Kazuo) teaches a gas valve which utilizes induced eddy currents in a plate coupled to a rod to open or close the valve by varying the current passing through permanent magnets located proximate to the plate. Like the '855 patent to Kuyel et al., the system taught in this reference must overcome a force on the plate due to a pressure of the gas, and therefore, is too slow and inconsistent to be used to test airbag deployment. Also like the Kuyel et al. apparatus, the system taught in this reference would open even slower, or perhaps not at all, when used with gases having significantly high pressures, as the repulsion force would have to be incredibly high to overcome the force due to pressure.

It is therefore an object of the invention to provide a gas valve which is capable of high speed opening and high speed gas flow and is also suitable for use in a cold gas airbag test system.

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Agent Ref: 74214/00002

DISCLOSURE OF INVENTION

The present invention broadly comprises a high speed gas valve apparatus including a reservoir for holding a gas having a charge port for filling the reservoir with the gas and an outlet for releasing the gas from the reservoir, a rod slidingly housed in the valve apparatus, the rod including a sealing means operatively arranged to engage with the outlet of the valve chamber for sealing the reservoir when the valve is in a closed position, a pneumatic actuator, wherein a piston of the pneumatic actuator is coupled to the rod, an electro-magnetic actuator coupled to the rod, and wherein the gas is released from the reservoir via the outlet when the apparatus is in an open position, and the valve transitions from the closed position to the open position by activating the pneumatic and electro-magnetic actuators to move the rod away from the outlet.

In one embodiment, the valve apparatus further includes a first chamber and a second chamber located on opposite sides of the piston of the pneumatic actuator, wherein the gas in the reservoir has a first pressure that exerts a first force on the rod in a first direction for maintaining the valve in the closed position by forcing the sealing means of the rod to remain engaged with the outlet, wherein a second pressure in the first chamber exerts a second force on the piston in the first direction for forcing the sealing means of the rod to engage with the outlet, wherein a third pressure in the second chamber exerts a third force on the piston in a second direction, wherein the second direction is opposite from the first direction, and wherein subsequent to an activation of the pneumatic actuator, but preceding an activation of the electro-magnetic actuator, a sum of the first and second forces is greater than the third force. In a further embodiment, the third force is slightly less than the sum of the first and second forces for substantially reducing a net force required by the electro-magnetic actuator to transition the valve from the closed position into the open position.

In another embodiment, the electro-magnetic actuator comprises an electronic coil and an electrically conductive plate, wherein the plate is fixedly secured to the rod and located proximate to the coil when the valve is in the closed

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Agent Ref 74214/00002 position, wherein the coil is electronically connected to a capacitor, wherein the electro-magnetic actuator is activated by discharging a current from the capacitor through the coil for creating a first magnetic field, wherein the first magnetic field induces a second magnetic field in the plate, and the second magnetic field is oppositely polarized with respect to the first magnetic field, wherein a repulsion force is created due to the first and second magnetic fields being oppositely polarized, and the repulsion force repels the plate away from the coil for transitioning the valve from the closed position to the open position by moving the rod away from the outlet.

The current invention also broadly comprises a method of operating a gas valve comprising the steps of: (a) pressurizing a first chamber in a pneumatic actuator, wherein a first pressure in the first chamber exerts a first force in a first direction on a piston of the pneumatic actuator, wherein the piston is coupled to a rod, for entering the valve into a closed position by forcing the rod to engage with an outlet of a reservoir of the gas valve; (b) pressurizing a reservoir of the gas valve with a gas having a second pressure; (c) depressurizing the first chamber in the pneumatic actuator for reducing the first pressure and the first force, wherein the gas in the reservoir exerts a second force due to the second pressure in the first direction on the piston for maintaining the valve in the closed position by forcing the rod to stay engaged with the outlet; (d) pressurizing a second chamber in the pneumatic actuator located on an opposite side of the piston from the first chamber, wherein a third pressure in the second chamber exerts a third force on the piston in a second direction opposite from the first direction of the first and second forces, wherein the piston transfers the third force to the rod, and wherein a sum of the first and second forces is larger than the third force; and, (e) activating an electro- magnetic actuator coupled to the rod for releasing the gas from the reservoir by transitioning the valve from the closed position to an open position by moving the rod away from the outlet.

In one embodiment, subsequent to step (d), but prior to step (e), the third force is slightly less than the sum of the first and second forces for substantially reducing a net force required by the electro-magnetic actuator to transitioning the valve into the open position. In another embodiment, activating the electro-magnetic

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Agent Ref: 74214/00002 actuator in step (e) further comprises discharging a current through an electronic coil for creating a first magnetic field, wherein the electronic coil is located proximate to a plate which is fixedly secured to the rod, wherein the first magnetic field induces a second magnetic field in the plate, and the second magnetic field is polarized oppositely with respect to the first magnetic field, wherein a repulsion force is created due to the first and second magnetic fields being oppositely polarized, and the repulsion force repels the plate from the coil for transitioning the valve from the closed position to the open position by forcing the rod away from the outlet.

These and other objects and advantages of the present invention will be readily appreciable from the following description of preferred embodiments of the invention and from the accompanying drawings and claims.

BRIEF DESCRIPTION OF DRAWINGS

The nature and mode of operation of the present invention will now be more fully described in the following detailed description of the invention taken with the accompanying drawing figures, in which:

Figure 1 is a partial cross-sectional side view of a gas valve according to the current invention;

Figure 2a is a schematic of a circuit for operating the electro-magnetic actuator of the gas valve shown in Figure 1 ; Figure 2b is a relevant portion of the schematic shown in Figure 2a with the switch open;

Figure 2c is a relevant portion of the schematic shown in Figure 2a with the switch closed; and,

Figures 3-9 are cross-sectional views of the gas valve shown in Figure 1 incrementally illustrating operation of the gas valve.

BEST MODE FOR CARRYING OUT THE INVENTION

At the outset, it should be appreciated that like drawing numbers on different drawing views identify identical, or functionally similar, structural elements of the invention. While the present invention is described with respect to what is presently considered to be the preferred aspects, it is to be understood that the invention as claimed is not limited to the disclosed aspects.

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Agent Ref: 74214/00002

Furthermore, it is understood that this invention is not limited to the particular methodology, materials and modifications described and as such may, of course, vary. It is also understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to limit the scope of the present invention, which is limited only by the appended claims.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this invention belongs. Although any methods, devices or materials similar or equivalent to those described herein can be used in the practice or testing of the invention, the preferred methods, devices, and materials are now described.

Referring now to the Figures, Figure 1 illustrates high speed gas valve 10, according to the current invention. Gas valve 10 includes valve body 12 that defines valve chamber or reservoir 14, which includes auxiliary inlet 16, outlet 18, and valve charge port 19. Auxiliary charge vessel 20 is detachably securable to inlet 16 and orifice bar 22 is detachably securable proximate to outlet 18.

Since reservoir 14 is a fixed volume, auxiliary charge vessel 20 is attached to reservoir 14 so that the volume of gas that valve 10 can hold is variably changeable. For example, if the reservoir has a volume of 1 L, auxiliary vessels of .5L, .75L, or 1 L could be attached via inlet 16 to increase the volume of gas in valve apparatus 10 to 1.5L, 1.75L, and 2L, respectively. Orifice bar 22 includes a hole that is aligned with outlet 18 for determining the flow characteristics of gas released from chamber 14 via outlet 18. For example, it may be desirable to increase or decrease the exit velocity or mass flow rate of the gas from the outlet by varying the size of the hole in the orifice bar. Valve sealing member 24 which includes valve sealing ring 25 is included on one end of rod 26. The rod is slidingly movable within the valve apparatus for selectably sealing and opening outlet 18. That is, valve closure member 24, which resembles a large bulb on the end of rod 26, is pressed into outlet 18 to create an airtight seal with the aid of sealing ring 25. Thus, the sealing member alone or together with the sealing ring comprises a sealing means for the valve. Sealing ring 25 is preferably a flexible and resilient o-ring fabricated from any

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Agent Ref 74214/00002 number of polymers or other suitable materials. A second end of rod 26, opposite from valve sealing member 24, extends into housing 30, which is secured to valve body 12. Housing 30 is preferably fixed to an immobile object via mount 31 , which may use bolts (not shown) or some other means known in the art to secure valve 10 in place. The second end of rod 26 is affixed to piston 32, which is slidingly mounted within cylinder 34, which in turn is mounted in housing 30. Piston 32 and cylinder 34 are components of pneumatic actuator 36, which may be any pneumatic actuator known in the art, including those that are commonly available commercially, but which preferably takes the general form shown in the Figures and described herein.

Plate 40 is mounted to an intermediate portion of rod 26 between sealing member 24 and pneumatic actuator 36. The disc is located adjacent to electrical coil L ₁ when the valve is in a closed position. By closed position we mean that sealing means 24 on rod 26 is engaged in a sealed relation with outlet 18 so that no gas stored in reservoir 14 can escape the reservoir through the outlet. The coil is fixedly mounted to housing 30 so that it is immovable with respect to valve 10. Plate 40 and coil Li are components of electro-magnetic actuator 44.

A preferred embodiment of main circuit 46 for electro-magnetic actuator 44 is shown schematically in Figure 2A. The circuit includes coil Li, high voltage power source V _H , capacitor d, resistors Ri and R ₂ , diode D-i, silicon- controlled rectifier SCR-i, switch S-i, optocoupler OC, control circuit 48 and low voltage source V _L . High voltage supply V _H is used to charge capacitor Ci, which stores the energy dissipated by the high voltage power source. Silicon-controlled rectifier SCRi acts as a high-speed switch for delivering the energy from capacitor Ci to coil L ₁ . Diode D-i is connected across coil L ₁ to protect the other components of the circuit from the back EMF generated by the rapid collapsing magnetic field in the coil. Optocoupler OC electronically isolates control circuit 48 and sends signals in the form of light or optics from the control circuit to operate main circuit 46. Control circuit 48 may send signals via the optocoupler to open and close switch S ₁ or turn the SCR on and off, for example. Low voltage power supply V _L provides a low voltage to the gate of the SCR to enable the SCR to operate. The resistance of

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Agent Ref 74214/00002 resistor R ₂ is chosen to regulate the voltage that is applied to gate G, as is well known to those having ordinary skill in the art of circuit design.

Figures 2B and 2C show a schematic of the relevant portion of circuit 46 and plate 40 when switch Si is opened and closed, respectively. When switch Si is open no current passes through the coil. When switch Si is closed, as in Figure 2C, large currents (several hundred amperes, for example) are generated because of the high voltage and capacitance, and extremely short discharge time of the capacitor, causing the coil to produce a powerful increasing magnetic field 42a, which passes through plate 40. While passing through the plate, magnetic field 42a induces eddy currents 50 in the direction indicated by arrow 52, which is opposite to the direction of current through the coil, as indicated by arrow 54. The induced current in plate 40 generates magnetic field 40a oppositely polarized with respect to magnetic field 42a, as fields 40a and 42a act generally in the direction of arrows 58 and 56, respectively. The two oppositely polarized magnetic fields generate a large repulsive force between the coil and the plate. The coil cannot move, as it is fixedly secured to housing 30 which is immovably anchored by valve mount 31. Consequently, the repulsive force rapidly repels plate 40 from coil L|. Since the plate is fixedly secured to the rod, the plate and the rod are forced in direction 58 away from outlet 18, to open outlet of valve 10. The following describes the parameters of a preferred embodiment of circuit 46, as shown in Figure 2, but it should be understood that the circuit could have other parameters readily recognizable by one skilled in the art. In order to maximize the energy transfer between the coil and the plate, the values of the capacitance, inductance and resistance should be chosen such that they create a critically damped circuit. Further, the below embodiment is designed to produce approximately a 600Ib force for 200μs between plate 40 and coil Li, with the total energy being dissipated in about 500μs. In this embodiment, coil L ₁ has an inductance of approximately 2mH, high voltage power source V _H is a 2000VDC, 6OmA power supply, capacitor C has a capacitance of 150μF, resistor Ri is achieved by approximately 1ω of inherent wire resistance so that an actual resistor is not used, and low voltage source V _L is a 24VDC power supply. The overall length of the

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Agent Ref 74214/00002 coil should be kept to a minimum and the plate should be kept as close to the coil as possible. In order to reduce the length of the wire used to make coil Li and to maintain the physical soundness of the coil, ribbon wire is preferably used instead of traditional magnetic wire. In the preferred embodiment, plate 40 is made of aluminum because it is lightweight and produces a sufficient magnetic field. Steel plates tend to be heavy and may occasionally become magnetically attracted to the coil. In this preferred embodiment, the coil and plate are pressed together, separated by only a thin sheet of plastic. It should be appreciated that the circuit elements and their associated values recited above are illustrative only, and that circuits having elements with different values can easily be configured by one having ordinary skill in the art of circuit design.

The valve is shown in an initial, open state in a cross-sectional view in Figure 3. By open we mean that sealing member 24 on rod 26 is not in a sealed relation with outlet 18 so that gas can freely escape the outlet from reservoir 14. Pneumatic actuator 36 includes chambers 60 and 62 on opposite sides of piston 32 in cylinder 34. Chamber 60 cannot be seen in Figure 3 as the piston is pushed to the far right side of the cylinder, leaving no room for chamber 60. Pressures P-i, P ₂ , and P ₃ represent the pressures in chambers 14, 60, and 62, respectively. In the initial state as shown in this Figure, all of the pressures are substantially equal to the atmospheric pressure, and the system is therefore balanced and in equilibrium. By atmospheric pressure we mean the pressure of the room or area in which valve 10 is housed. It should be appreciated that when pressures P1 , P2, and P3 are discussed in relative terms, or as gauge pressures, atmospheric pressure is assumed to be zero or no pressure. Therefore, a chamber at atmospheric pressure is assumed to exert no forces on the chamber or objects in the chamber, such as the rod.

Valve 10 is shown in a closed position in Figure 4. By closed position we mean that sealing member 24 engages outlet 18 for making reservoir 14 airtight.

An activation of pneumatic actuator 36 forces rod 26 into the closed position shown. Specifically, the activation of pneumatic actuator 36 comprises pressurizing chamber 60 so that pressure P ₂ is high enough to exert a force to move piston 32, and

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Agent Ref 74214/00002 therefore rod 26 and sealing member 24, towards outlet 18. In a preferred embodiment, pressure P ₂ is about 25 psig. As shown in Figure 5, reservoir 14 is filled with a high pressure gas having pressure P ₁ via charge port 19 as indicated by arrow 64. In the preferred embodiment, pressure Pi is about 3,000 psig, but it could be other pressures, as desired. If auxiliary vessel 20 is present, the gas from charge port 19 will also fill the charge vessel, which is initially empty. Pressures Pi and P ₂ exert first and second forces on rod 26 (indirectly through piston 32 and sealing member 24, respectively) in the direction indicated by arrow 56 toward the outlet.

Next, chamber 60 is depressurized so that pressure P ₂ returns to approximately atmospheric pressure, as shown in Figure 6. However, rod 26 is held in sealed engagement with the outlet due to pressure Pi exerting a force on sealing member 24 of the rod. In this Figure, the valve reservoir is storing the gas that is desired to be released when the outlet is opened, such as, for example, the gas necessary to fill an airbag in an airbag inflation test. It may be desirable to leave pressure P ₂ at a relatively low value, such as 10 psig, so that it can cushion the cylinder from the piston when electro-magnetic actuator 44 is fired, as will be described later.

As shown in Figure 7, chamber 62 is then pressurized so that it contains pressure P ₃ . Pressure P ₃ exerts a third force in the direction of arrow 58 on piston 32, which transfers the third force to rod 26 and sealing member 24.

Pressure P ₃ is preferably increased to a point at which outlet 18 is just about to open, but at which the outlet is still completely sealed. That is, the magnitude of the

^" force due to pressure P ₃ in direction 58 is just less than a sum of the forces due to pressures Pi and P ₂ in direction 56. In the preferred embodiment, pressure P ₃ varies between approximately 25-125 psig during this phase.

It is well known that the force exerted on a surface of a chamber is equal to the pressure in the chamber multiplied by the area of the surface. Therefore, by including a surface area of piston 32 on which pressure P ₃ acts which is substantially greater than the surface area of sealing member 24 on which pressure Pi acts, as shown in the Figures, it is possible to exert a force in direction 58 equal to a force in direction 56 with a substantially smaller pressure P ₃ with

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Agent Ref 74214/00002 respect to pressure Pi. Thus, in the preferred embodiment, when pressure Pi is 3,000 psig, pressure P ₃ only has to be about 125 psig to exert a force to sufficiently counteract the force exerted by pressure P-i.

If pressure P ₃ were increased enough, so that the force in the direction of arrow 58 were higher than force due to pressure Pi in the direction of arrow 56, the rod would be forced to move in direction 58, thereby opening outlet 18 by breaking the sealed engagement of the sealing member and the outlet. However, for many applications, particularly for testing the inflation of airbags, an entirely pneumatic valve would open the valve too slowly, and would also result in inconsistent opening times for the valve in repeated trials. Obviously, if valve 10 were used in a testing scenario, the valve must work consistently and quickly to properly simulate the same deployment speed as a real airbag.

Instead of increasing pressure P ₃ further, pressure P ₃ is held so that the forces exerted by pressure P ₃ is just less than the sum of the forces exerted by pressures Pi and P ₂ . That is, the outlet requires only a small amount of force to open, but the outlet is still completely sealed by the sealing member of the rod. For example, if the third force equaled ninety percent of the sum of the first and second forces, the electro-magnetic actuator would only have to overcome ten percent of the sum of the first and second forces to open the valve. As such, P ₃ could be tuned with respect to pressures Pi and P ₂ for varying the opening speed of the valve.

At the stage shown in Figure 9, the pneumatic actuator has completed its activation and electro-magnetic actuator 44 is fired. Pressure P ₃ counteracts the force due to pressure P ₁ , so that the electro-magnetic actuator has a substantially reduced force to overcome to open the outlet. That is, if pressure P ₃ were not present, the electro-magnetic actuator would have to overcome a larger force in opening the outlet, which would result in a slower opening of valve 10. Moreover, by including an appropriate pressure P ₃ , one can quickly and consistently open valve 10 regardless of pressure Pi of the gas stored in reservoir 14.

As discussed with respect to Figures 2a-2c, the activation of electro- magnetic actuator 44 creates powerful oppositely polarized magnetic fields which repel plate 40 from coil L. Since rod 26 is slidingly housed in housing 30 and plate

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40 is fixedly secured to the rod, the repulsion of the plate from coil also moves the rod away from the outlet. If circuit 45 has the parameters described in the preferred embodiment above, the rod is repelled forcefully away from outlet 18, opening a one inch diameter outlet in about 2ms. Advantageously, as soon as the outlet is cracked open, pressure P^ surrounds and acts on the front of sealing member 24 to help open the outlet by pushing the rod in direction 58. Once the outlet is opened, the high pressure gas is released from reservoir 14 (and auxiliary vessel 20, if present) as indicated by arrow 66.

It should be appreciated that one could use valve 10 to do more than just inflate airbags for testing. For example, it has been conceived that one could use different nozzles on the end of valve 10 to produce and examine Shockwaves or special gas flows, such as supersonic flows, in physiological or materials research. Additionally, one could choose to elongate rod 26 to extend out of the back of cylinder 34, for example, to use rod 26 as a ram, punch, plunger, impacting device, or launching means for a projectile, to name but a few possible applications.

Thus, it is seen that the objects of the present invention are efficiently obtained, although modifications and changes to the invention should be readily apparent to those having ordinary skill in the art, which modifications are intended to be within the spirit and scope of the invention as claimed. It also is understood that the foregoing description is illustrative of the present invention and should not be considered as limiting. Therefore, other embodiments of the present invention are possible without departing from the spirit and scope of the present invention.

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