KR19990044181A - Liquid Propellant Expansion Device for Expanding Expansion Members - Google Patents

Abstract

Apparatus 10 for deploying an expansion member, such as a safety bag in a motor vehicle, includes hydraulic actuators 16, 18, 27, 24 that initially amplify the fluid pressure in combustion chamber 22 generated by a ignition initiator. Amplified fluid pressure is provided to continuously pressurize the liquid propellant reservoir 30 to a size that exceeds the fluid pressure. All liquid propellants in the reservoir then generate a volume of combustion gas necessary to fully inflate the safety bag by rapidly injecting a continuous stream into the combustion chamber for ignition and continuous combustion.

Description

Liquid propellant inflation device for inflating the inflation member.

Contrary to "active" restraint devices (such as conventional seat belts) that require conscious effort of the occupant to operate, "passive" restraints that currently do not require the vehicle occupant's action to operate are generally present. It is included as a standard installation in motor vehicles according to the requirements of government agents, insurance industry, and consumers. Experience and experimentation show that the most effective approach to passive occupant restraint is to automatically inflate the safety bag suddenly (within a few milliseconds) for heavy collisions. The inflated safety bag protects the occupant from the effects of the crash with a cushion sufficient to prevent serious injuries.

Timely inflation of the safety bag is generally of two forms. One form involves accumulating a volume of high pressure compressed gas, such as argon, in a suitable reservoir. In a crash, the gas is released to inflate the safety bag. However, this approach has a number of disadvantages. The volume and weight of components needed to store large volumes of compressed gas makes it difficult and expensive to install safety devices in the steering column, instrument panel, and door of a motor vehicle. In addition, since the gas is compressed at high pressure, the storage state for a long time in various ambient environments is very weak.

As a result, the expansion of the safety bag by the release of the compressed gas is largely replaced by the use of flammable propellants that can quickly generate large amounts of gas by a heat dissipation reaction. Propellants are generally solids or granules comprising low energy components such as alkali metal azide, cupric oxide, boron nitrate, and the like. A significant disadvantage of solid propellants is that they generate gases that typically contain toxic byproducts and particulate components. As a result, the inflation gas of the safety bag is generally filtered to remove toxic by-products and to prevent the combustion of particulate components that can burn holes in the safety bag. This filter increases the size, weight, and price of the passive restraint device.

Optionally, the propellant for expanding the safety bag may be in liquid form, as known from US Pat. No. 5,060,973 issued to Giovanetti, which publication is incorporated herein by reference. A particularly important consideration in liquid propellant inflation devices is the controlled combustion of all liquid propellants to achieve fast and effective deployment of the safety bag.

The present invention relates to an apparatus and a method for inflating an inflatable member. In particular, the present invention relates to an apparatus and a method for deploying a safety bag for a vehicle occupant.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together provide examples to illustrate the principles of the invention. Only one figure is a sectional view showing a preferred embodiment of the safety bag inflation device according to the present invention.

It is a general object of the present invention to provide an improved device for deploying an inflatable member.

It is another object of the present invention to provide a small and economical device which is economical and efficient in structure for inflating occupant safety bags in a motor vehicle using gas generated while the combustion of liquid propellant is controlled.

It is a further object of the present invention to provide an inflation device of the above features, wherein the volume of the liquid propellant can be conveniently varied with respect to the size of the safety bag.

A further object is to provide a safety bag inflation device that overcomes one or more drawbacks and disadvantages of the art.

As outlined and practiced herein, the apparatus of the present invention for achieving the above and other objects of the present invention includes a housing including a discharge passage through which a fluid connected to the expansion member flows for deployment. An initiator is located in the housing to operate a hot gas that increases the hydraulic pressure in the internal combustion chamber. The housing also includes a liquid propellant reservoir connected to the combustion chamber via a fluid passage and the hydraulic actuator operates in response to the hydraulic pressure in the combustion chamber to continuously pressurize the liquid propellant in the storage chamber to a size greater than the hydraulic pressure in the combustion chamber. do. As a result, the liquid propellant is injected from the reservoir in the combustion chamber through the fluid passage for ignition and combustion to generate combustion gas flowing through the discharge passage in an amount sufficient to fully deploy the expansion member.

Additional features, objects, and advantages of the invention will be described and become apparent in the following examples, and will be understood by the practice of the invention. The objects and advantages of the invention will be obtained and realized in particular by the devices indicated in the examples and claims, as well as in the accompanying drawings below.

The detailed description of the invention and the following examples are merely good examples as claimed, but are not limited to the invention.

Referring to the examples shown in the accompanying drawings, preferred embodiments of the present invention will be understood in detail.

The device labeled 10 in accordance with the present invention is shown an application for deploying an inflatable member, such as an occupant restraint safety bag in a motor vehicle. The device 10 includes a cylindrical housing labeled 12, and the insert 14 in the device is received through one housing opening end in a fluid sealed relationship. The insert 14 is fabricated to provide a pair of axially drawn blind bores provided with two parallel cylinders 16 and 18 of equal length. The plug 20 is installed at the other housing opening end in a fluid sealing relationship with respect to the spaced position relative to the insert, the spaced position being a position for providing an internal combustion chamber 22 between the two ends. The housing 12, insert 14, and plug 20 are preferably metals such as steel or aluminum that are able to withstand the high internal fluid pressures generated during safety bag deployment.

The separator piston 24 is slidably received in the cylinder 16, and the piston 26 is slidably received in the cylinder 18. The open end of the cylinder 16 is sealed off by the plug 28. The space in the cylinder 16 between the plug 28 and the piston 24 provides a reservoir 30 containing a liquid propellant 32. The liquid propellant may be a HAN-based liquid propellant that withstands "XM 46" as specified by the US Army. Optionally, the liquid propellant 32 may be a liquid monopropellant based on hydroxyl ammonium nitrate, such as known in the Giovanetti patent. Formulation of a common liquid propellant may be by a mass of about 60% hydroxyl ammonium nitrate as oxidant, 20% triethane as fuel, triethanol ammonium nitrate, and 20% water as solvent.

A transverse port 34 installed in the insert 14 delivers fluid between the two cylinders in a position adjacent to the closed ends 17, 19 of the two cylinders 16, 18. The division of the cylinders 16, 18 between the two pistons 24, 26, which delivers fluid through the port 34, provides a reservoir 36 containing hydraulic fluid 38 in liquid form.

Attached to the piston 26 is a piston rod 40 that extends axially along the cylinder 18 and extends outward through a tight bore 42 that is drilled past the closed end of the cylinder. The face 25 of the piston 26 facing the hydraulic fluid reservoir 36 has a smaller surface area than the piston face 27 facing the combustion chamber 22 because the piston rod 40 is present. The importance of this surface area difference will be explained in detail below.

The plug 28 installed at the open end of the cylinder 16 includes a one-way valve 42 which allows liquid propellant to flow from the storage chamber 30 into the combustion chamber 22 through the fluid passage 44 and in the combustion chamber. Prevents fluid from flowing back into the reservoir despite the high pressure. Thus, the one-way valve 42 may be a conventional check valve or spring-loaded ball valve.

The housing end plug 20 includes a through-bore 46 for connecting the initiator, denoted 48, to pressurize the combustion chamber 22 that ignites and burns the liquid propellant 32. Preferably, the initiator 48 includes an ignition material 50 and an ignition device 52. The ignition material 50 may be in liquid form, but preferably may be a solid such as boron potassium nitrate or zirconium potassium fluorochloride or smokeless powder. The ignition device 52 may be of a type capable of igniting an ignition material 50, such as a material known from the Giovanetti patent.

In a known embodiment, the ignition 52 is generally connected to one side of the vehicle battery 56 via an open shock sensing internal switch 58 and the wall of the housing end plug 20 and the housing 12. It comes into contact with the electrode 54 coming out through the sealed radial hole as if it were sealed through. The other side of the battery is connected to the housing 12 to allow the ignition circuit to close the switch 58 completely.

The housing end plug 20 also includes an axial bore provided as an outlet passage 60 for transferring fluid between the expansion chamber, such as the safety bag, shown schematically at 64 in FIG. 1 and the combustion chamber 22. The entrance and exit of the safety bag is sealed against the perforated end of the housing 12 by a suitable clamp 66. An orifice member 68 is provided in the discharge passage 60 to help control the safety bag inflation rate. In addition, the bore passage is a burst designed to rupture when the fluid pressure in the combustion chamber 22 reaches a predetermined level, for example 1,000 psi, so that the safety bag inflation is delayed until an appropriate amount of liquid propellant is combusted in the combustion chamber. Join the burst disk 70. Burst disk 70 is preferably a metal such as brass or aluminum.

In the event of a strong crash in a vehicle equipped with the device 10 of the present invention, the switch 58 is closed to complete the ignition circuit and activate the initiator 48. The ignition device 52 detonates the ignition material 50 to pressurize the combustion chamber 22. An increase in the fluid pressure in the combustion chamber drives the piston towards the closed end 19 of the cylinder 18, and consequently hydraulic fluid 38 passes through the port 34 into the cylinder 16 behind the piston 24. Is pumped. Due to the difference in surface area of the two surfaces 25, 27 of the piston 26, the hydraulic fluid in the storage chamber 36 is continuously pressurized to a fluid pressure exceeding the fluid pressure in the combustion chamber 22. Accordingly, the hydraulic fluid pressure on the piston 24 is effective to pressurize the liquid propellant 32 in the storage chamber 30 to a fluid pressure that exceeds the fluid pressure in the combustion chamber 22. Thus, the one-way valve 42 opens to allow the liquid propellant to be pumped into the combustion chamber through the fluid passage 44. The combustion chamber into which the liquid propellant enters is immediately ignited by the hot combustion gas generated by the detonating ignition material 50. As the detonated liquid propellant combusts, the fluid pressure in the combustion chamber rises rapidly to a predetermined burst pressure of the burst disk 70. When the burst disk ruptures, combustion gas flows through the orifice member 68 and the discharge passage 60 so that the expansion of the safety bag 64 begins.

Due to the difference in the surface area of the piston 26, the liquid propellant in the reservoir 30 continues to pressurize to a magnitude greater than the pressure in the combustion chamber 22 throughout the expansion process, and from the reservoir to the combustion chamber for ignition and complete combustion. The flowing liquid propellant 32 is injected by the full amount. The safety bag is fully inflated in a few microseconds to prevent injury to the vehicle occupant.

Although the housing 12 is shown as a cylinder, it may be taken in various forms such as a rectangle depending on the installation space in the vehicle, that is, the steering wheel, the instrument panel, or the door. If the space is limited to a rectangle, the piston rod 40 will become increasingly brittle when the free end of the piston rod is driven out of the housing end while the safety bag is inflated.

Although FIG. 1 shows the entrance and exit of the safety bag 64 sealed against one end of the housing 12, the safety bag may be installed in the inflator housing in various ways, depending on the shape of the housing. For example, an external manifold (not shown) may be mounted to the side of the housing to direct the inflation gas from the housing bore passageway into a safety bag that is sealed to the manifold.

An important feature of the present invention is that the inflation device 10 can be easily used to inflate the safety bag to a wide range of sizes at the installation location as indicated in the motor vehicle. For this purpose, the inflation device may be fully assembled in the factory, except for the installation of the safety bag 64 and the filling of the reservoirs 30, 36 with the liquid propellant 32 and the hydraulic fluid 38, respectively. To regulate the next fluid filling, the radial port 80 is drilled through the housing wall into the reservoir 30 at a location adjacent to the cylinder plug 28. The second fill port 82 is drilled through the housing wall into the storage compartment 36. After the size of the safety bag that the inflation device inflates is determined, an appropriate volume of liquid propellant is pumped from the propellant source 84 through the shaft 80 into the reservoir 30. The piston 24 slides backward relative to the filling position, increasing the reservoir volume to adjust the measured amount of liquid propellant 32 pumped into the reservoir 30 by the propellant 84. The port 80 is then sealed with a plug 86. Hydraulic fluid 38 is then pumped through port 82 from fluid source 88 to completely fill reservoir 36. The port 82 is then sealed with a plug 90. It is understood that the position of the piston 24 easily adjusts the volume of liquid propellant pumped into the reservoir 30, and thus the expansion device 10 is generally determined by the amount of liquid propellant pumped into the reservoir 30. It is used to fully inflate one of the safety bags of various sizes.

Although it is described herein that the inflation device of the present invention expands the occupant restraint safety bag installed in the motor vehicle, the present invention does not limit the technical scope. That is, the expansion device of the present invention can be used to rapidly deploy other types of expansion members for various purposes.

Other embodiments of the present invention will become apparent to those skilled in the art from considerations herein and practice of the invention known herein. The invention is capable of modifications and variations of the invention without departing from the scope of the claims.

Claims (13)

A housing provided with an expansion member, the housing including a discharge passage for transmitting a fluid flow to the expansion member; A combustion chamber in the housing, An initiator located in the housing for activating and generating a hot gas which increases the fluid pressure in the combustion chamber; A reservoir in a housing containing a liquid propellant, A fluid passageway communicating between the liquid propellant reservoir and the combustion chamber, A hydraulic actuator responsive to the fluid pressure in the combustion chamber to continuously pressurize the liquid propellant in the storage chamber to a magnitude greater than the fluid pressure in the combustion chamber, And continuously inject a liquid propellant from the reservoir into the combustion chamber for ignition and combustion that generates combustion gases flowing through the discharge passage to deploy the expansion member. 2. The apparatus of claim 1 further comprising a one-way valve positioned within the fluid passageway. 2. The apparatus of claim 1 further comprising a frangible member positioned to block the discharge passage until the fluid pressure in the combustion chamber exceeds the inlet level. 4. The device of claim 3, further comprising an orifice element disposed in the outlet. 2. The apparatus of claim 1 wherein the hydraulic actuator includes a hydraulic fluid reservoir coupled at fluid pressure with respect to a liquid propellant reservoir and a hydraulic piston is disposed between the combustion chamber and the hydraulic fluid reservoir. 6. The expansion member of claim 5 wherein the hydraulic piston comprises a first face exposed to fluid pressure in the combustion chamber and a second face facing the hydraulic fluid reservoir, the first face having a surface area greater than the second face. Deployment device. 7. The apparatus of claim 6 wherein the hydraulic actuator further comprises a slideable piston separating the liquid propellant reservoir and the hydraulic fluid reservoir to associate the fluid pressure of the hydraulic fluid to the liquid propellant. A housing provided with an expansion member, the housing including a discharge passage for transmitting a fluid flow to the expansion member; A combustion chamber in the housing, An initiator located in the housing for activating and generating a hot gas which increases the fluid pressure in the combustion chamber; First and second cylinders positioned in parallel in the housing and respectively facing the combustion chamber and having first and second closed ends, respectively; An opening adjacent the first and second closed ends communicating the first and second cylinders for fluid delivery; A closure in the first cylinder open end including a fluid passage; A first piston slidably received within said first cylinder for interacting with a closure forming a first reservoir, A liquid propellant contained in the first reservoir, A second piston slidably received at the second cylinder open end forming a second reservoir between the first and second pistons; A hydraulic fluid filling the second reservoir, The second piston transmits a force proportional to the fluid pressure in the combustion chamber by the hydraulic fluid to the first piston, One of the first and second pistons has two opposite surfaces having different surface areas effective to continuously pressurize the liquid propellant in the first reservoir at a fluid pressure greater than that in the combustion chamber, And continuously inject the liquid propellant from the first reservoir into the combustion chamber through a fluid passage for ignition and generation of combustion gas flowing through the discharge passage to deploy the expansion member. 9. The housing of claim 8 wherein the housing is filled for a first port through which the measured fill amount of liquid propellant can be introduced into the first reservoir and for a volume of the first reservoir sufficient to receive a fill of the liquid propellant. A first port that slides in the first cylinder, a second port introduced to fill the second reservoir formed between the first piston and the second piston at a position where hydraulic fluid is filled, and the first port; And a plug sealing the second port. 9. The apparatus of claim 8 further comprising a one-way valve positioned within the fluid passageway. 11. The apparatus of claim 10 further comprising a brittle member positioned to block the discharge passage until the fluid pressure in the combustion chamber exceeds the inlet level. 12. The apparatus of claim 11 further comprising an orifice element disposed in the outlet. 9. The second cylinder of claim 8, wherein the second piston is slidably received through a first face facing the combustion chamber, a second face facing the second reservoir, and an opening in the second cylinder closed end. A piston rod fixed to the second face to extend through the piston, wherein the piston reduces the surface area of the second face to a value less than the surface area of the first face such that the surface areas of the two side faces of the second piston are different. Apparatus for expanding the expansion member to have a.