WO2000021800A9

WO2000021800A9 - Vortex valve inflator for inflatable restraint system

Info

Publication number: WO2000021800A9
Application number: PCT/US1999/024179
Authority: WO
Inventors: Michael Fink
Original assignee: AirBelt Systems LLC
Current assignee: AirBelt Systems LLC
Priority date: 1998-10-14
Filing date: 1999-10-14
Publication date: 2000-09-14
Anticipated expiration: 2001-04-14
Also published as: AU1207700A; WO2000021800A1

Abstract

A vortex valve inflator (20) for an inflatable restraint system is disclosed. Upon gas being released from a pressurized vessel (25), the gas travels through a vortex valve (24) to regulate the volume of gas flowing through the valve from the pressure vessel into an inflatable vehicle occupant restraint. The vortex valve achieves this flow regulation without the need for any moving parts. When inflated, the inflatable restraint (201) restrains an occupant of a vehicle during a collision. By controlling the gas flow into the air bag at the appropriate times, the valve achieves the desired bag energy absorbing characteristics for each unique crash condition.

Description

Vortex Valve Inflator for Inflatable Restraint System

Background of the Invention

Field of the Invention

The present invention relates generally to a motor vehicle inflatable restraint system, and more particularly to an inflator having a valve of unitary construction which operates without any moving parts to control the flow of pressurized gas from a high pressure vessel into an air bag of the inflatable restraint system.

Background of the Art

Inflatable restraint systems to protect motor vehicle occupants from injury in the event of a collision have been incorporated into motor vehicles in response to enacted legislation and public demand for safer motor vehicles. Air bags have been widely demonstrated to be highly effective in motor vehicle frontal collisions by reducing the degree of injury to passengers of vehicles equipped with such systems. In a typical inflatable restraint system, as is well known in the art, an airbag inflates upon detection of sudden deceleration indicative of a frontal collision to protect the passengers of the vehicle from forceful contact with hard surfaces in the vehicle interior. Typically, in new motor vehicles the inflatable restraint system is installed in the hub of the steering wheel for driver protection with an additional inflatable restraint system being installed in the dashboard for front seat passenger protection becoming increasing popular as standard equipment. Inflatable restraint systems have also been installed in the doors of motor vehicles to protect against side impact collisions, in the seat backs of the front seats to protect rear seat passengers in the event of a frontal collision, and in the headrest portion of the seats to provide full head protection in any type of collision..

The typical inflatable restraint system includes an inflator, an airbag, deceleration or impact sensors and triggering electronics. The air bag is a folded, expansible bag constructed of suitable fabric. The inflator is connected to the interior of the air bag. The most common inflator in use in motor vehicles is of the pyrotechnic type which contains a solid propellant, such as sodium azide. Upon impact being detected by the sensors, the triggering circuit ignites the sodium azide propellant, which in turn rapidly generates a hot gas discharge filling and inflating the air bag. As the air bag inflates, it escapes from its enclosure and expands, for example, in front of the driver, cushioning the driver as the driver is thrown forward by the impact and prevents the driver from striking the hard interior surface of the vehicle.

Although hot gas inflators currently command a 100% market share for motor vehicle inflatable restraint systems, the limitations and disadvantages associated with inflating an air bag with the hot gas from sodium azide and other types of pyrotechnic inflators are well known and documented in the art. Sodium azide is a known hazardous toxic chemical. In addition, when the air bag is inflated, gas at very high temperatures is released that can inflict severe burns to the occupant. Other limitations and disadvantages of the pyrotechnic inflator technologies include explosions, transportation concerns, environmental issues, and chemical degradation. Accordingly, there is a need for an inflatable restraint system that is not dependent upon a pyrotechnically generated hot gas.

There is known in the prior art a compressed source "cold gas" inflator which does not use a pyrotechnically ignited solid propellant. In an inflatable restraint system using a cold gas inflator, a pure stored compressed inert gas is released to inflate the air bag. Typical inert gases include nitrogen, argon, carbon-dioxide and helium. Helium is generally preferred for use in cold gas inflators due to its low critical temperature, high speed of sound, specific heat ratio and Joule-Thompson coefficient. Although initial research and development of inflatable restraint system focused on both cold gas and hot gas inflators, a major limitation of the prior art cold gas inflator that has prevented it from being incorporated into vehicles is that the output of the cold gas inflator without any type of regulation valve is unacceptably affected by ambient temperature extremes. Any airbag inflator. cold gas or hot gas. is required to function in temperatures ranging from - 40° C (-40° F) to 98° C (208° F), which are possible extremes encountered in various locations during winter extremes to hot summer conditions.

For a compressed gas contained in a fixed volume, it is well known that the gas pressure increases or decreases in proportion to the ambient temperature, as set forth by the Ideal Gas Law: Pι/P₂=Tι/T₂. For example, a vessel pressurized to όOOOpsi @ ambient temperature (70° F) would have its internal pressure affected by temperature extremes as follows:

@ -40° F, internal pressure = 4755psi

@ 208° F, internal pressure = 7570psi. The above example shows how the temperature extremes affect the storage pressures and thus, will affect the total outflow of gas volume that will inflate the airbag.

As a result of this large variance in vessel pressure, a cold gas inflator, designed to fill the airbag to proper proportions at the high temperature conditions, would fill the airbag to only a portion of the desired level during the cold extreme conditions, thus, producing insufficient energy absorbing characteristics for the occupant of the vehicle during an impact. Conversely, if the cold gas inflator was designed to have proper bag filling characteristics at the low temperature extremes, in a high temperature environment the bag would fill to an unacceptably high pressure level possibly causing tearing at the seams or a burst, resulting in loss of energy absoφtion of the occupant. Alternatively, if the airbag did not burst, the higher pressure would produce an unacceptably very "hard" air bag, possibly causing injury to the occupant of the vehicle when in forceful contact with the air bag. Both of these extreme situations are unacceptable limitations and disadvantages of the prior art.

Because of these foregoing described limitations and disadvantages of the prior art cold gas inflator that the early development work in inflatable restraint systems favored the hot gas inflator despite the know problems associated with solid propellants used in the hot gas inflator. Although the solid propellant combustion process is also affected by temperature extremes, the affect is orders of magnitude less than in the pure stored gas inflators. One prior art device, known as the hybrid inflator, uses both a compressed source, which is affected by temperature extremes to the same degree as a stored gas inflator. and a solid propellant to mitigate the effects of ambient temperature, has been developed but has not been commercially accepted. In the hybrid inflator. the solid propellant is used to assist in the total gas output which varies less with temperature. Therefore, the overall temperature dependent pressure variance of the hybrid design is less than the conventional pure stored gas design. However, the cost of the hybrid inflator is much greater than either the hot gas or the cold gas inflator since it incoφorates the inflation mechanism from each. Accordingly, the hot gas inflator has become the commercially accepted prior art device because it was initially demonstrated to reduce these temperature dependent pressure variances to acceptably low levels and offer the greater overall performance and occupant protection.

Another limitation associated with the prior art cold gas inflator is that its output flow of gas during the initial vessel opening is, by nature, very violent and aggressive. When the gas is released unregulated into the air bag it can cause high stress induced loading in the bag itself or to the occupant, if the occupant is close to the air bag as it deploys. It is important, therefore, to provide some means of regulating the gas from the compressed gas source into the air bag during the initial vessel opening stage. A limitation in general that extends to all inflatable restraint systems is that the inflator is designed to pressurize the airbag independent of the ambient environment or other variables, conditions and parameters which exist during a collision. An example of possible crash variables, conditions and parameters are as follows:

-Crash Severity

-Ambient Temperature

-Occupant Weight

-Occupant Position

-Seat belt Fastened/Unfastened. For example, design guidelines for commercially available inflatable restraint systems are provide the maximum protection for the unbelted 50th percentile male (which represents the median size and weight of the population of drivers) at a 30mph crash speed into a rigid barrier (the "ideal crash").

The presently available inflators will deploy the airbag to the same magnitude in every crash with no dependence on any of the previously mentioned variances which occur in all crashes. Therefore, an occupant whose size and weight is considerably different from this median range will experience less than ideal decelerating characteristics from the airbag. The smaller and lighter occupant will have a tendency to rebound off the airbag, where injury and even death from this rebound is typical. Deaths caused to infants and small children from the deployment of airbags are the current focus of media inquiry. The larger and heavier occupant can deflate the entire bag, and with the remaining energy impact the steering wheel or dashboard causing injury which the ideal size and weight occupant would not otherwise suffer.

Commercial available inflatable restraints must employ a very aggressive of the airbag which must be fully inflated in approximately 30-60 milliseconds, depending on location in the vehicle, in order to provide the proper energy absorbing characteristics to the occupant. Because of its high deployment forces, an airbag has the potential to cause great harm in non-ideal crash conditions. During a moderate crash condition with a small occupant, it would be undesirable for the airbag to deploy with its normal high force, as the occupant interaction with the airbag would cause injury from the deployment. However, a great majority of the crashes in real world accidents are not the "ideal crash."

There has been several recent attempts to address the above identified limitations and disadvantages of the prior art inflators. For example, to protect small children from being severely injured or killed form airbag deployment, it has been proposed to provide the vehicle with a defeat switch to disable the inflatable restraint at the location where the child is seated. However, this solution is unacceptable since the child will be exposed to even greater risk of injury or death by being unprotected from striking hard surfaces of the vehicle interior during a collision. Furthermore, the effectiveness of the inflatable restraint system in protecting adults will be seriously comprised should the operator forget to enable the inflatable restraint system for the protection of adult occupants.

Another example of a recent attempt to address the above identified limitations and disadvantages of the prior art inflators is to provide a dual stage in conjunction with weight sensors to detect the weight of the occupant proximate the airbag. If the weight sensor detects the occupant weight below a threshold weight, only one stage will deploy, thereby reducing inflation pressure yet providing sufficient energy absorbing protection to the small occupant. However, the dual stage inflator effectively doubles the cost of the inflator since two separate sources of solid propellant or cold gas are required along with dual triggering electronics.

Yet another example of a recent attempt to address the above identified limitations and disadvantages of the prior art inflators is to provide a mechanical valve at the output of the inflator in conjunction with various sensors which detect one or more of the variables, conditions or parameters described above. A logic circuit or processor may then detect the sensor conditions and command an actuator or motor to adjust the valve element thereby controlling the output flow rate and output pressure of the inflator and hence the inflation rate and pressure of the deployed airbag. Theoretically, such a system could adjust for any of the variables, conditions or parameters in real time from before and after the onset of the collision. However, the reliability and operability of such a system in real world crashes has not been demonstrated. For example, the collision may destroy the logic or processor electronics or the mechanical valve may become physically deformed by the collision forces, in either event causing a failure of the inflatable restraint system.

Accordingly, there is a need for an inflator, whether hot gas, cold gas or hybrid, that overcomes one or more limitations and disadvantages of the prior art discussed hereinabove. Specifically, there is a need for an inflator which has a regulated output pressure. There is a further need for an inflator which provides a time dependent output flow rate. Furthermore, there is a need for an inflator which provides a valve without any moving parts to achieve such regulated output pressure and time dependent output flow rate. Summary of the Invention

It is therefor an object of the present invention to provide an inflator which overcomes one or more limitations and disadvantages of the prior art inflators.

It is another object of the present invention to provide an inflator which provides a regulated output pressure.

It is another object of the present invention to provide an inflator which provides a time dependent output flow rate.

It is yet another object of the present invention to provide an inflator which includes a valve without any moving parts to achieve such regulated output pressure and time dependent output flow rate.

According to the present invention, an inflator comprises a source of gas and a valve having an internal vortex chamber. The vortex chamber has a cylindrical wall disposed intermediate two facing end walls, defining the vortex chamber. An inlet opening is disposed within the valve housing to communicate gas from the source tangentially along the cylindrical wall. The outlet opening is disposed substantially coaxial with respect to the cylindrical wall in one of the end walls to communicate gas from the vortex chamber. The source of gas may be any of a cold gas vessel, a hot gas source such as sodium azide. or a hybrid, each as described hereinabove. Upon the immediate release or generation of the gas. the gas flow, being tangential along the arcuate wall, develops an initial fluidic flow in the vortex chamber spiraling radially inwardly toward the outlet orifice. The fluid flow becomes increasingly radially inward in response to a decreasing pressure differential between the inlet and outlet orifices.

A feature of the present invention is that the vortex chamber, the inlet orifice and outlet orifice may be dimensioned to provide a predetermined regulated output pressure or a predetermined output flow rate, either of which may have a time variant component, of the inflator. For example, the inwardly spiraling flow within the vortex chamber develops an initial pressure higher at the outlet orifice than that the inlet orifice, this pressure differential decreasing as the flow through the valve increases. The radius of the vortex chamber, the axial length of the chamber, the cross sectional area of each of the inlet and outlet orifice be the selected to provide a determined regulated outlet pressure of the inflator or a regulated output flow rate. An advantage of a present invention over the prior art inflators is that the regulation of output pressure or of the flow rate is achieved without any removable valve elements or any external mechanical, hydraulic or pneumatic actuators to move such valve elements.

In another embodiment of the present invention, the valve housing includes a second inlet orifice to communicate gas from the source axially into the vortex chamber. The axial flow is, in one particular embodiment, introduced from the end wall opposite the end wall containing the outlet orifice. The axial flow his initially mixed with the tangential flow along the arcuate wall. As the tangential flow decreases, i.e., becomes more radially inward, the flow rate from the second inlet to the outlet becomes less perturbed by the tangential flow until the flow between the second inlet orifice and the outlet orifice becomes substantially unimpeded within the vortex chamber. In one particular aspect to this embodiment of the present invention, the flow exiting the second inlet orifice may be the partially obstructed to create turbulence within the flow to facilitate mixing with the tangential flow.

In yet another embodiment of the present invention, the gas communicating to the second inlet orifice may be derived from a second source isolated from the source of gas communicated to the first inlet orifice. By utilizing separate sources, one source may be timed to deplete quicker than the other source allowing yet even further tailoring of the inflator outlet pressure and flow rate.

These and other objects, advantages and features of the present invention will become readily apparent to one skilled in the art from a study of the following description of the preferred embodiment when read in conjunction with the attached Drawing an appended Claims.

Brief Description of the Drawing

Fig. 1 is a fragmented cross-sectional view of a basic embodiment of an inflator constructed according to the principles of the present invention.

Fig. 2 is a cross-sectional view taken along line 2-2 of Fig. 1 illustrating the operation of the inflator of Fig. 1.

Fig. 3 is a cross-sectional view of a modification to the basic embodiment of the inflator of Fig. 1 exemplifying utility within an inflatable restraint system.

Fig. 4 is an enlarged fragmented, cross-sectional view of a portion of the inflator of Fig. 3.

Fig. 5 is a view, similar to Fig. 4, illustrating operation of the inflator of Fig. 1. Fig. 6 is a cross-sectional view taken along line 6-6 of Fig. 5, illustrating operation of the inflator of Fig. 1.

Fig. 7 is fragmented, cross-sectional view of a modification to the inflator of Fig. 3.

Fig. 8 is a view similar to Fig. 7 illustrating operation of the modification of Fig. 7.

Fig. 9 is a cross-sectional view of a second embodiment of an inflator constructed according to the principles of the present invention exemplifying utility within an inflatable restraint system.

Fig. 10 is an enlarged fragmented, cross-sectional view of the inflator of Fig. 9.

Fig. 11 is a cross-sectional view taken along line 1 1-1 1 of Fig. 10.

Fig. 12a and Fig. 12b are each a cross-sectional view taken along line 12-12 of Fig. 10 illustrating operation of the inflator of Fig. 9.

Fig. 13 is a cross-sectional view of a third embodiment of an inflator constructed according to the principles of the present invention.

Fig. 14a and Fig. 14b are each a cross-sectional view taken along line 14-14 of Fig. 13 illustrating operation of the inflator of Fig. 13.

Fig. 15 is a schematic block diagram of a control circuit useful in conjunction with practicing of the present invention.

Description of the Exemplary Preferred Embodiments

Referring now to Fig.'s 1-2, there is shown a basic first embodiment of a vortex valve inflator 20 constructed according to the principles of the present invention. The inflator 20 includes a source 22 of an immediately flowable gas, and a valve 24. Although the best mode embodiments of the present invention hereinbelow described are particularly described in conjunction with a cold gas inflator, the principles to the present invention are also applicable to a hot gas inflator and a hybrid inflator.

For the cold gas inflator embodiment, the source 22 contains and stores a gas, preferably inert, under pressure within a vessel 25 constructed to withstand the required gas pressure as is known in the art. the gas is contained and sealed within the vessel 25 by a burst disk 26. To make the gas stored within the vessel 25 immediately releasable from the inflator 20, an initiator 28 is provided. The initiator 28, for example a squib, may detonate in response to an electrical signal applied thereto. The detonation of the initiator 28 in turn ruptures the burst disk 26. Rupture of the burst disk 26 initiates of flow of gas through the valve 24 and its immediate release from the inflator 20.

For the hot gas inflator embodiment the source 22 may contain within the vessel 25 a combustible substance, as a well-known the art, which substance upon ignition develops a gas causing gas pressure to immediately build within the vessel 25 and initiate a flow of gas through the valve 24 and its immediate release from the inflator 20. In such hot gas embodiment, the burst disk 26 is not required and electrical signal used to detonate the initiator 28 present in the cold gas embodiment may instead be utilized to ignite the combustible substance in the hot gas embodiment. The vessel 25 must also then be constructed to withstand the ignition of the combustible substance.

The valve 24 has an internal cylindrical vortex chamber 30, an inlet orifice 32 and an outlet orifice 34. The vortex chamber 30 has a first end wall 36, a second end wall 38 and a cylindrical wall 40. The second end wall 38 is in a spaced apart facing relationship to the first end wall 36. The cylindrical wall 40 is inteφosed the first end wall 36 and the second end wall 38. The inlet orifice 32 has a first end 42 adapted to receive pressurized gas from the vessel 25 and a second end 44 disposed in the cylindrical wall 40. The second end 44 of the inlet orifice 32 is arranged to communicate the pressurized gas from the vessel 25 into the vortex chamber 30 tangentially along the cylindrical wall 40. as best seen in Fig. 2.

The first end wall 36 of the vortex chamber 30 is formed on an inner surface 27 of a generally planar end portion 29 of the vessel 25. The cylindrical wall 40 of the valve 24 is disposed adjacent the end portion 29 within and spaced from a body portion 31 of the vessel 25 such that the cylindrical wall 40 projects from the inner surface 27 and the second end wall 38 is spaced from the end portion 29. The outlet orifice 34 is disposed in the end portion 29 substantially coaxially with respect to the cylindrical wall 40 to communicate gas externally of the inflator 20. The outlet orifice 34 has a first end 46 at the inner surface 27 and a second end 48 distal therefrom at an outer surface 33 of the end portion 29.

The burst disk 26 is disposed in a fluidly sealing arrangement to block communication of gas through the outlet orifice 34. The initiator 28 is disposed adjacent the burst disk 26. The initiator 28 is responsive to an electrical signal to rupture said burst disk 26. When the burst disk ruptures, gas from the vessel 25 is communicated into the vortex chamber 30 through the inlet orifice 32. The gas. due to the arrangement of the second end 44 of the inlet orifice 32. is caused to enter the vortex chamber 30 tangentially along the cylindrical wall 40, as indicated by the arrows indicative of the flow path in Fig.

2. The tangential flow of gas develops an initial fluid flow in the vortex chamber 30 spiraling inwardly toward the outlet orifice 34. The fluid flow thereafter becomes increasingly radially inward in response to a decreasing pressure differential between the inlet orifice 32 and the outlet orifice 34.

The inflator 20 may further include a diverter 50 disposed the outer surface 33 of the end portion 29 of the vessel 25. The diverter has a generally cylindrical body portion

52 and an end portion 54. The cylindrical body portion 52 has a plurality of openings 56 to communicate gas from the outlet orifice 34 externally of the inflator 20. The cylindrical body portion 52 is disposed coaxially with respect to the outlet orifice 34 and the end portion 54 of the diverter 50 is spaced from the end portion 29 of the vessel 25.

The end portion 54 of the diverter 50 may further include a bore 57 through which the initiator 28 is disposed. The diverter 50 and the end portion 29 of the vessel 25 may further be of unitary construction. As described hereinbelow with reference to Fig.'s 3-5, the end portion 54 of the diverter 50 may also have an inner convex conical surface 58 coaxial with the cylindrical body portion 52.

The valve 24 as hereinabove described with reference to Fig.'s 1-2 has been disclosed as disposed within the vessel 25. However, it is contemplated that in certain applications of the inflator 20, valve 24 may be placed external to the vessel 25, as best seen in Fig.'s 3-6.

With further reference to Fig.^'s 3-6. to accomplish such external placement, the valve 24 may further include a housing 60 having a generally planar first end 62. a second end 64 spaced form the first end 62 and a cylindrical body 66 inteφosed the first end 62 and the second end 64. The first end wall 36 of the vortex chamber 30 is formed on an inner surface 63 of the first end 62 of the housing 60. The cylindrical wall 40 is disposed adjacent the first end 62 within and spaced from the cylindrical body 66 such that the cylindrical wall 40 projects from the inner surface 63 and the second end wall 38 is spaced form the first end 62. The outlet orifice 36 is disposed in the first end 62 substantially coaxially with respect to the cylindrical wall 40 to communicate gas externally of the inflator 20. The first end 46 of the outlet orifice 344 is at the inner surface 63 and the second end 48 of the outlet orifice 34 is distal therefrom at an outer surface 65 of the first end 62.

In the external embodiment, the end portion 29 of the vessel 25 is modified to have an outlet opening 70 and the second end 64 has an inlet opening 72. The second end 64 is attached to the vessel 25 with the inlet opening 70 and the outlet opening 72 in fluidic communication with each other. In one particular embodiment of the present invention, the burst disk 26 is disposed within the outlet opening 72 of the vessel 25.

In either the internal or external embodiments hereinabove or hereinafter described, the inner cylindrical wall 40 may further include a plurality of additional inlet orifices 32|, 32₂, ..., 33_n, wherein n is an integer, identical to inlet orifice 32. Each of inlet orifices 32ι-_n are disposed in the cylindrical wall 40 in the same manner as the inlet orifice 32 and are also arranged to communicate the pressurized gas to the vortex chamber 30 tangentially along the cylindrical wall 40 in the same direction as gas communicated therein by the inlet orifice 32. In particular, the cylindrical wall 40 may include six inlet orifices 32. Furthermore, each of the inlet orifices 32 may be disposed in the cylindrical wall at substantially equally spaced angular intervals.

The inflator 20 of the external embodiment may also include the diverter 50 attached to the outer surface 65 of the first end 62. The cylindrical body 52 extends outwardly from the outer surface 65. The closed end portion 54 is spaced from the first end 62 in a facing relationship thereto. The end portion 54 may further have the inner conical convex surface 58 coaxially aligned with the outlet orifice 32.

With further reference to Figures 7-8. the diverter 50 may further include a vent orifice 86. a pyrotechnic material 88 sealingly disposed in said vent orifice, and a squib 90 disposed in the pyrotechnic material 88. The squib 90 is responsive to an electrical signal to ignite the pyrotechnic material 88 to open the vent orifice 86, as best seen in Figure 8. The vent orifice may be disposed in the end portion 54 of the diverter 50.

Referring now to Figures 9-12. there is shown an inflator 100 constructed according to the principles of a second preferred embodiment of the present invention.

The inflator 100 includes a vessel 102. a burst disk 26. a valve body 104 and an initiator

28. Similarly as described in conjunction with vessel 25. the vessel 102 is adapted for containing a pressurized gas. The vessel 102 includes a vessel body 106 and a vessel top 108. The vessel body 106 has at least a cylindrical end portion 110 disposed adjacent the vessel top 108. The vessel top 108 has an outlet opening 112 coaxially aligned with the cylindrical end portion 1 10. The vessel 102 defines a reservoir chamber 114. The burst disk 26 is disposed in the outlet opening 1 12 of the vessel top 108. The initiator 28 is responsive to an electrical signal to rupture the burst disk 26.

The valve body 104 has a cylindrical wall 1 16. an end wall 118 and a flange 120.

The cylindrical wall 116 is coaxially disposed in a radially spaced relationship to the

I I cylindrical end portion 1 10 defining a cylindrical chamber 122 therebetween. The end wall 118 is disposed in a facing spaced apart relationship to the vessel top 108 defining a vortex chamber 124 therebetween. The flange 120 radially extends from the cylindrical wall 116 in sealing engagement with the cylindrical end portion 110. The cylindrical wall 116 has at least one radially skewed orifice 126 therein inteφosed the flange 120 and the end wall 118 to communicate the cylindrical chamber 122 with the reservoir chamber 114. The cylindrical chamber 122 is in communication with the vortex chamber 124.

Upon rupture of the burst disk 26. the radially skewed orifice 126 will communicate gas - into the vortex chamber 124 substantially tangential along the cylindrical end portion 1 16, as best seen in Figure 12A. The flow of gas within the vortex chamber 124 is similar as hereinabove described with reference to the vortex chamber 30 of the valve 24 of the inflator 20 of the first embodiment of the present invention. The flow of gas within the vortex chamber 124 becomes increasingly radially inward in response to a decrease of the pressure differential between the radially skewed orifice 126 and the outlet opening 112, as best seen in Figure 12B. The gas exits the vortex chamber 124 through the outlet opening 112.

More particularly, the flange may include at least one axial orifice 128 to communicate the reservoir chamber 1 14 with the cylindrical chamber 122. The cylindrical wall 116 may also include a reduced diameter portion 130 proximate the flange 120. The axial orifice 128 may further be disposed proximate the reduced diameter portion 130.

The inflator 100 may further include a cylindrical cup 132 disposed coaxially adjacent the valve body 104. The cup 132 has an open end 134 sealingly attached to the cylindrical wall 116 distal from the end wall 1 18. The valve body 104 and the cup 132 define an isolation chamber 136.

The inflator 100 may also further include a generally cylindrical diverter 138 coaxially disposed with the outlet opening 1 12. The diverter 138 is attached to an outer surface 140 of the vessel top 108 and has a cylindrical portion 142 extending outwardly from the vessel top 108, a closed end wall 144 spaced from the vessel top 108, and a plurality of openings 146 disposed through the cylindrical portion 142 The initiator 28 may be disposed through a bore 148 within the closed end wall 144.

Referring now to Figures 13-14. there is shown an inflator 160 constructed according to the principles of a third embodiment of the present invention. The inflator

160 includes the vessel 102 as hereinabove described, a burst disk 26. a valve body 164, and an initiator 28. The vessel 102 in the embodiment of inflator 160 also includes the hereinabove described vessel body 106 and a vessel top 108. Similarly, the vessel body

106 has at least the cylindrical end portion 1 10 disposed adjacent the vessel top 108, and the vessel top 108 has the outlet opening 112 coaxially aligned with the cylindrical end portion 110. Also similarly as described above, the vessel 102 defines a reservoir chamber 114. The burst disk 26 is disposed in the outlet opening 112. The initiator 28 is responsive to an electrical signal to rupture the burst disk 26.

The valve body 164 has a cylindrical wall 166 and an end wall 168. The cylindrical wall 166 is coaxially disposed within the end portion 110 and sealingly engaged to the vessel top 108. The end wall 168 is in a facing spaced apart relationship to the vessel top 108 defining a vortex chamber 170 therebetween. The end wall 168 has at least one axially skewed orifice 172 disposed in the end wall 168 adjacent the cylindrical wall 166 to communicate the vortex chamber 170 with the reservoir chamber

1 14.

Upon rupture of the burst disk 26. the axially skewed orifice 172 will communicate gas into the vortex chamber 170 substantially tangential along the cylindrical wall 166, as best seen in Figure 14A. The flow of gas within the vortex chamber 170 is similar as hereinabove described with reference to the vortex chamber 30 of the valve 24 of the inflator 20 of the first embodiment of the present invention. The flow of gas within the vortex chamber 170 becomes increasingly radially inward in response to a decrease of the pressure differential between the axially skewed orifice 172 and the outlet opening 1 12. as best seen in Figure 14B. The gas exits the vortex chamber

170 through the outlet opening 1 12.

More particularly, the cylindrical wall 166 of the valve body 164 may further include at least one radially disposed orifice 174 to communicate the reservoir chamber

114 with the vortex chamber 170.

The inflator 160 may also further include a cylindrical cup 176 disposed coaxially adjacent the valve body 164. The cup 176 has an open end 178 sealingly attached to the cylindrical wall 166 adjacent the end wall 168. The end wall 168 and the cup 176 define an isolation chamber 180.

The inflator 160 may also further include a generally cylindrical diverter 138 coaxially disposed with the outlet opening 112. The diverter 138 is attached to an outer surface 140 of the vessel top 108 and has a cylindrical portion 142 extending outwardly from the vessel top 108. a closed end wall 144 spaced from the vessel top 108, and a plurality of openings 146 disposed through the cylindrical p rffiM-*f42 The initiator 28 may be disposed through a bore 148 within the closed end wall 144.

The construction of each embodiment of the present invention having been hereinabove described, the operation of the inflator 20, 100, 160 of the present invention will be hereinbelow set forth with reference to Figure 15. As best seen in Figure 15, there is shown a circuit 181, having a processor 183 and a plurality of sensors 185. Although the circuit 181 is well known in the art. the circuit 181 will be generally described so that the more casual reader of the specification herein may obtain a better understanding of the use of present invention.

The sensors 185 may include a deceleration sensor 187, a seatbelt sensor 189, a PSI sensor 191, an occupant position sensor 193 and a occupant weight sensor 195. The deceleration sensor 187 detects the deceleration of a vehicle (not shown) and develops a first deceleration electrical signal commensurate with the magnitude of the deceleration of the vehicle. The deceleration signal may be compared to a threshold signal, and if it exceed such threshold, a second deceleration signal is developed for application to the processor 183.

For example, the deceleration sensor 187 may develop the first deceleration signal as a digital signal which is applied to a memory 197. The memory 197 may contain one or more digitized signals representative of deceleration profiles of a vehicle involved in a collision. If the digital first deceleration signal matches a digitized signal in the memory 197 indicative of a collision, the second deceleration signal is applied to the processor 183. The processor 183 in response to the second deceleration signal develops a first output electrical signal for application to the initiator 28. The initiator 28 in response to the first output electrical signal causes the burst disk 26 to rupture. The rupture of the burst disk 26 allows the sudden discharge of compressed gas from the vessel 25, 102, 162 used in each respective embodiment of the inflator 20, 100, 160 hereinabove described.

In the first embodiment described in conjunction with Figures 3-6, rupture of the burst disk 26 allows pressurized gas inside the vessel 25 to escape through the outlet opening 70 of the vessel 25 and into the inlet opening 72 of the second outer body member 52 of the valve 24. A screen 199 may be disposed within the inlet opening to filter any shrapnel and other remnants remaining from the rupture of the burst disk 26. As the gas enters the valve 24 at high pressure, it begins to flow through the inlet orifices 32, as best seen by the flow direction arrows of Figure 5, and begins to swirl within the vortex chamber 30, as best seen by the flow direction arrows of Figure 6, due to the tangential introduction along cylindrical wall 40 as hereinabove described. The operation of the internal embodiment of Fig.'s 1-2 is substantially similar and has been described hereinabove.

Initially within the vortex chamber, a pressure differential between the second end

44 of the inlet orifices 32 and the first end 46 of the outlet orifice 34 is sufficient to maintain the angular flow. However as gas begins to exit the vortex chamber 30, and the pressure in the vessel 25 lessens due to depletion of gas, the pressure differential decreases, thereby allowing the flow within the vortex chamber to become increasingly radial inward. The flow rate is maximized as the flow direction approaches radially inward, however, the pressure of the flow exiting the vortex chamber 30 remains relatively constant until it decreases toward the end of the flow as the vessel 25 is nearly depleted as compared to the initial high pressure flow entering the vortex chamber 30 upon rupture of the burst disk 26. which pressure gradually decreases as the vessel 25 depletes.

When the inflator 20 of the present invention is used within an inflatable restraint

201, as best seen in Figure 3. its advantages over prior art cold gas inflators, as well as hot gas inflators, becomes readily apparent to those skilled in the art. The inflatable restraint

201 includes an air bag 203 (shown folded), a reaction can 205, and the inflator 20 disposed within the reaction can 205. When the burst disk 26 is ruptured, the gas from the vessel 25 exits the inflator 20 through the openings 56 of the diverter 50. the gas flow through the valve 24 being hereinabove described. As the gas exits the diverter 50 into the reaction can 205, the airbag 203 begins to inflate. Because of the flow of gas through the valve 24, the initial inflation pressure is substantially less than prior art inflators wherein the vessel discharges directly into the reaction can 205 and airbag 203. The prior art cold gas inflators would cause excessively rapid expansion of the airbag, which could cause additional injury to children, small adults and unbelted occupants of the motor vehicle. However, the inflator 20 of the present invention restrains an initial "explosive" expansion of the airbag 203 while allowing the airbag 203 to continue to expand during the collision thereby providing enhanced protection of the occupant by absorbing the forces of collision over an increased time duration.

The inflation characteristics of the airbag 203 can be further tailored when using the vent orifice 86 which allows gas to exhaust external of the reaction can 205 thereby becoming unavailable for inflation of the airbag 203. as best seen in Figures 7-8. For example, the maximum inflation pressure of the airbag 203 ideally decreases with decreasing weight of the occupant to be protected. The maximum inflation pressure required may also depend on the occupant position within the vehicle and relative position with respect to the airbag 203, and may further depend upon whether the occupant is passively restrained by a seatbelt/harness. Finally, the maximum inflation pressure of the airbag also depends upon the initial pressure of the vessel 25.

Accordingly, the seatbelt sensor 189, pressure sensor 191, position sensor 193 and weight sensor 195 may be additionally provided for, alone or in any desired combination, within the circuit 181. Their respective output signals are applied to the processor 183 which contains appropriate algorithms, which are well known in the art, depending ion the combination of sensors 185 utilized. In response to each electrical signal developed by the particular ones of sensors 185 utilized, the processor 182 develops a second electrical signal, subsequent in time to the first electrical signal, for application to the squib 90. The squib in response to the second electrical signal explodes, thereby opening the vent orifice 86 to exhaust gas within the diverter 74 external of the reaction can 205 to reduce the maximum inflation pressure of the airbag 203.

In the embodiment of the inflator 100 described in conjunction with Figures 9-12, when the burst disk 26 is ruptured, gas enters the vortex chamber 124 through the radially skewed orifices 126. The swirl within the vortex chamber 124 is similar as hereinabove described and is best seen by the flow arrows of Figure 12. Figure 12A is especially indicative of the initial flow and Figure 12B is especially indicative the subsequent increased radially inward flow.

When the cylindrical cup 132 is utilized, the gas entering the vortex chamber 124 originates from the isolation chamber 136. Prior to rupture of the burst disk, the pressure of within the isolation chamber 136 is equal to the pressure within the reservoir chamber 1 14, since each are in fluid communication with each other through the radially skewed orifices 126 and the axial orifices 128. The lesser volume of the isolation chamber 136 will deplete first reducing the effect of the swirl within the vortex chamber 124 prior to depletion of the reservoir chamber 1 14. Since gas exiting the reservoir chamber 114 proceeds axially along the cylindrical wall 116. it does not contribute to the vortex effect. However, by sizing the diameter the radially skewed orifices 126 and the axial orifices 128, the flow and pressure of gas exiting the inflator 100 can be tailored to meet certain predefined inflation characteristics of the airbag 203 when the inflator 100 is placed within the reaction can 205. Furthermore, the placement of the axial orifices 128 and the diameter of the reduced diameter portion 130 can also be adjusted to provide more or less restriction of gas exiting the axial orifices 128 as it impinges upon the cylindrical wall 116.

In the embodiment of the inflator 160 described in conjunction with Figures 13- 14, when the burst disk 26 is ruptured, gas enters the vortex chamber 170 through the axially skewed orifices 172. The swirl within the vortex chamber 170 is similar as hereinabove described and is best seen by the flow arrows of Figure 14. Figure 14A is especially indicative of the initial flow and Figure 14B is especially indicative the subsequent increased radially inward flow.

When the cylindrical cup 176 is utilized, the gas entering the vortex chamber 170 originates from the isolation chamber 180. Prior to rupture of the burst disk, the pressure of within the isolation chamber 180 is equal to the pressure within the reservoir chamber 1 14, since each are in fluid communication with each other through the axially skewed orifices 172 and the radial orifices 174. The lesser volume of the isolation chamber 180 will deplete first reducing the effect of the swirl within the vortex chamber 170 prior to depletion of the reservoir chamber 1 14. Since gas exiting the reservoir chamber 1 14 proceeds radially into the vortex chamber 170 through the radial orifices 174, it does not contribute to the vortex effect. However, by sizing the diameter the axially skewed orifices 172 and the radial orifices 174, the flow and pressure of gas exiting the inflator 160 can be tailored to meet certain predefined inflation characteristics of the airbag 203 when the inflator 160 is placed within the reaction can 205.

There has been described hereinabove exemplary preferred embodiments of a vortex valve inflator constructed according to the principles of the present invention. Those skilled in the art may now make numerous uses of. and departures from, the hereinabove described embodiments without departing the inventive concepts disclosed herein. Accordingly, the present invention is to be construed solely by the scope of the appended claims and their permissible equivalents.

Claims

The ClaimsWhat is claimed as my invention is:

1. A vortex valve inflator comprising: a source of an immediately releasable gas; and a valve having an internal cylindrical vortex chamber, an inlet orifice and an outlet orifice, said vortex chamber having a first end wall, a second end wall in a spaced apart facing relationship to said first wall and a cylindrical wall inteφosed said first wall and said second wall, said inlet orifice having a first end adapted to receive gas from said source and a second end disposed in said cylindrical wall, said second end of said outlet orifice being arranged to communicate said gas to said vortex chamber tangentially along said cylindrical wall, said outlet orifice being disposed in said first wall substantially coaxial with respect to said cylindrical wall to communicate gas externally of said inflator, said gas when entering said vortex chamber tangentially along said cylindrical wall developing an initial fluid flow in said vortex chamber spiraling inwardly toward said outlet orifice, said fluid flow becoming increasingly radially inward in response to a decreasing pressure differential between said inlet orifice and said outlet orifice.

2. An inflator as set forth in Claim 1 wherein said source includes a vessel having a body portion and an end portion, said end portion having an inner surface and an outer surface, said cylindrical wall projecting from said inner surface and said second end wall being spaced from said end portion, said first end wall being formed by a portion of said end portion bounded by said cylindrical wall.

3. An inflator is set forth in Claim 2 wherein said inflator further includes: a burst disk disposed within said outlet orifice in a fluidly sealing arrangement; and an initiator detonatable in response to an electrical signal applied thereto, said burst disk being rupturable in response to detonation of said initiator, said vessel being adapted to store said gas under pressure.

4. An inflator is set forth in Claim 2 wherein said inflator further includes a diverter attached to said outer surface of said end portion, said diverter having a generally cylindrical body portion coaxial with said outlet orifice and extending from said outer surface, and an end portion spaced from said end portion of said vessel, said cylindrical body portion having a plurality of openings therethrough to communicate gas from said outlet orifice externally of said inflator.

5. An inflator is set forth in Claim 4 wherein said end portion of said diverter has an inner conical convex surface coaxial with said cylindrical body portion.

6. An inflator is set forth in Claim 4 wherein said end portion of said diverter includes a bore, said initiator being dispose through said bore.

7. An inflator as set forth in Claim 1 wherein said valve further includes a housing, said housing having first end. a second end in a facing relationship to said first end of said housing, and a cylindrical body inteφosed said first end and said second end. said cylindrical wall being disposed coaxially within and spaced from said cylindrical body, said first end of said housing having an inner surface and an outer surface, said first end wall being formed by a portion of said inner surface contained within said cylindrical wall, said outlet orifice being disposed in said first end of said housing coaxially with respect to said cylindrical wall, said second end of said housing having an inlet opening to receive gas from said source.

8. An inflator as set forth in Claim 7 wherein said source includes a vessel having an end portion, said end portion of said vessel having an outlet opening, said second end of said housing being attached to said end portion of said vessel with said inlet opening and said outlet opening in fluid communication.

9. An inflator as set forth in Claim 8 further comprising: a burst disk disposed in said outlet opening; and an initiator disposed in said outlet opening proximate said burst disk.

10. An inflator as set forth in Claim 7 wherein said inflator further includes a diverter attached to said outer surface of said first end of said housing and having a cylindrical body portion extending outwardly from said first end of said housing, and an end portion spaced from said first end of said housing, said cylindrical body portion having a plurality of openings disposed therethrough.

11. An inflator as set forth in Claim 10 wherein said end portion of said diverter has an inner conical convex surface coaxially aligned with said outlet orifice.

12. An inflator as set forth in Claim 1 1 wherein said diverter further includes: a vent orifice disposed in said diverter; a pyrotechnic material sealingly disposed in said vent orifice; and a squib disposed in said material and being responsive to an electrical signal to ignite said material to open said vent orifice.

13. An inflator as set forth in Claim 12 wherein said vent orifice is disposed in said end portion of said diverter.

14. An inflator as set forth in Claim 1 wherein said cylindrical wall includes a plurality of inlet orifices, each of said inlet orifices disposed in said cylindrical wall arranged to communicate said pressurized gas to said vortex chamber tangentially along said cylindrical wall.

15. An inflator as set forth in Claim 14 wherein each of said inlet orifices are disposed in said cylindrical wall at substantially equally spaced angular intervals.

16. An inflator comprising: a vessel adapted for containing a pressurized gas and including a vessel body and a vessel top, said vessel body having at least a cylindrical end portion disposed adjacent said vessel top, said vessel top having an outlet opening coaxially aligned with said cylindrical end portion, said vessel defining a reservoir chamber; a burst disk disposed in said outlet opening; a valve body having a cylindrical wall coaxially disposed in a radially spaced relationship to said end portion defining a cylindrical chamber therebetween, an end wall in a facing spaced apart relationship to said vessel top defining a vortex chamber therebetween, and a flange radially extending from said cylindrical wall in sealing engagement with said end portion, said cylindrical wall having at least one radially skewed orifice therein inteφosed said flange and said end wall to communicate said cylindrical chamber with said reservoir chamber, said cylindrical chamber being in communication with said vortex chamber; and an initiator responsive to an electrical signal to rupture said burst disk, said initiator being responsive to an electrical signal to rupture said burst disk thereby communicating gas from said vessel into said vortex chamber through said radially skewed orifice, said gas when entering said vortex chamber tangentially along said cylindrical end portion developing an initial fluid flow in said vortex chamber spiraling inwardly toward said outlet opening, said fluid flow becoming increasingly radially inward in response to a decreasing pressure differential between said radially skewed orifice and said outlet opening.

17. An inflator as set forth in Claim 160 wherein said flange includes at least one axial orifice to communicate said reservoir chamber with said cylindrical chamber.

18. An inflator as set forth in Claim 17 wherein said cylindrical wall includes a reduced diameter portion proximate said flange, said axial orifice being disposed proximate said reduced diameter portion.

19. An inflator as set forth in Claim 17 wherein said inflator further includes a cylindrical cup disposed coaxially adjacent said valve body, said cup having an open end sealingly attached to said cylindrical wall at an end distal from said end wall, said valve body and said cup defining an isolation chamber.

20. An inflator as set forth in Claim 19 wherein said cylindrical wall includes a reduced diameter portion proximate said flange, said axial orifice being disposed proximate said reduced diameter portion.

21. An inflator as set forth in Claim 16 wherein said inflator further includes a generally cylindrical diverter coaxially disposed with said outlet opening, said diverter attached to an outer surface of said vessel top and having a cylindrical portion extending outwardly from said vessel top, a closed end wall spaced from said vessel top, and a plurality of openings disposed through said cylindrical portion.

22. An inflator comprising: a vessel adapted for containing a pressurized gas and including a vessel body and a vessel top, said vessel body having at least a cylindrical end portion disposed adjacent said vessel top, said vessel top having an outlet opening coaxially aligned with said cylindrical end portion, said vessel defining a reservoir chamber; a burst disk disposed in said outlet opening; a valve body having a cylindrical wall coaxially disposed within said end portion sealingly engaged to said vessel top. and an end wall in a facing spaced apart relationship to said vessel top defining a vortex chamber therebetween, said end wall having at least one axially skewed orifice disposed in said end wall adjacent said cylindrical wall to communicate said vortex chamber with said reservoir chamber; and an initiator responsive to an electrical signal to rupture said burst disk, said initiator being responsive to an electrical signal to rupture said burst disk thereby communicating gas from said vessel into said vortex chamber through said axially skewed orifice, said gas when entering said vortex chamber tangentially along said cylindrical wall developing an initial fluid flow in said vortex chamber spiraling inwardly toward said outlet opening, said fluid flow becoming increasingly radially inward in response to a decreasing pressure differential between said axially skewed orifice and said outlet opening.

23. An inflator as set forth in Claim 22 wherein said cylindrical wall includes at least one radially disposed orifice to communicate said reservoir chamber with said vortex chamber.

24. An inflator as set forth in Claim 22 wherein said inflator further includes a cylindrical cup disposed coaxially adjacent said valve body, said cup having an open end sealingly attached to said cylindrical wall adjacent said end wall, said end wall and said cup defining an isolation chamber.

25. An inflator as set forth in Claim 22 wherein said inflator further includes a generally cylindrical diverter coaxially disposed with said outlet opening, said diverter attached to an outer surface of said vessel top and having a cylindrical portion extending outwardly from said vessel top. a closed end wall spaced from said vessel top, and a plurality of openings disposed through said cylindrical portion.