Abstract:
A steering column safety device for use in a motor vehicle having a steering wheel for communicating steering torque to a steering mechanism, and having a collision sensing assembly for sensing a collision, includes a hollow cylinder having a top end and a bottom end, the top end being sized and configured for fixed, torque-transmitting connection to a steering wheel; a piston residing within the cylinder for sliding, telescopic reciprocation between an extended position and a collapsed position; an elongated rod with first and second ends, the first end being secured to the piston and the second end being sized and configured for fixed, torque-transmitting connection to the steering mechanism; structure for transmitting torque between the cylinder and the rod; a sealing assembly for sealing the hollow cylinder to define a fluid-tight cavity within the hollow cylinder between the piston and the top end of the cylinder, the fluid-tight cavity containing prior-to-collision pressurized gas; and, a mechanism to rapidly open the sealing assembly in response to a signal generated by the collision sensing assembly, thereby permitting movement of the hollow cylinder from the extended position to the collapsed position.

Description:
This is a Continuation-in part of application U.S. Ser. No. 08/654,905 filed May 22, 1996 now U.S. Pat. No. 5,893,580 and thus, is entitled to the same filing date of such application for the subject matter in common with that application. 
    
    
     BACKGROUND 
     The present invention pertains to automobile occupant safety apparatus and more particularly pertains to a motor vehicle steering column safety device. 
     Although analysis shows that vehicle air bag cushion systems are working generally as intended, these systems still have some drawbacks. According to the National Highway Traffic Safety Administration (NHTSA), present “explosive-type” air bag inflator devices deploy air bags at speeds of approximately 200 mph. Data collected by NHTSA show that small-stature occupants who must sit closer to the steering wheel than average-sized occupants are especially vulnerable to injury due to the force of the deploying air bag. This is especially the case in low-speed collisions. These devices have caused serious injury and death to small-statured individuals, children, out-of-position occupants, and unbelted or improperly belted occupants, all of whom are closer to the air bag than an average-sized belt-restrained occupant upon vehicle collision. 
     A collapsible steering column also has been recognized as desirable to provide an added safety factor for all vehicle occupants. Some prior systems combine the collapsible steering column and air bag devices together, but the prior art depends upon two independent systems: (1) an air bag inflator system, and (2) an independent steering column collapsing means. 
     Two independent systems take longer to achieve the desired result than a single actuating means. None of the preceding devices collapses the steering column concurrently with inflating the air bag, and the timing of air bag inflation and steering column collapse may be the difference between life and death. Other energy absorbing steering columns have also been developed, but upon collision these apparatus deform and (1) make it impossible for the driver to transmit steering torque and/or (2) jeopardize rapid and efficient air bag inflation. 
     Finally, it is important that a collapsible steering column and air bag safety device meet original equipment manufacturer&#39;s (OEM) specifications and government standards and be economically feasible to implement into all foreign and domestic fleet automobiles. 
     Therefore, it is highly desirable to provide a new motor vehicle steering column safety device. 
     It is also highly desirable to provide a new motor vehicle steering column safety device that inflates an air bag faster than explosive-type inflator systems. 
     It is also highly desirable to provide a new motor vehicle steering column safety device that is capable of protecting small-stature individuals, children, out-of-position occupants, and unbelted or improperly belted occupants. 
     It is also highly desirable to provide a new motor vehicle steering column safety device that collapses the steering column concurrently with inflating an air bag. 
     It is also highly desirable to provide a new motor vehicle steering column safety device capable of delivering steering torque while collapsing the steering column concurrently with inflating an air bag cushion upon collision. 
     It is also highly desirable to provide a new motor vehicle steering column safety device that meets all of the original equipment manufacturer&#39;s (OEM) specifications and required regulations, can be cheaply manufactured and easily installed into any make and model of vehicle. 
     It is finally highly desirable to provide a new motor vehicle steering column safety device which meets all of the above desired features. 
     SUMMARY 
     It is an object of the invention to provide a new motor vehicle steering column safety device. 
     It is also an object of the invention to provide a new motor vehicle steering column safety device that inflates an air bag faster than explosive-type inflator systems. 
     It is also an object of the invention to provide a new motor vehicle steering column safety device that is capable of protecting small-stature individuals, children, out-of-position occupants, and unbelted or improperly belted occupants. 
     It is also an object of the invention to provide a new motor vehicle steering column safety device that collapses the steering column concurrently with inflating an air bag. 
     It is also an object of the invention to provide a new motor vehicle steering column safety device capable of delivering steering torque while collapsing the steering column concurrently with inflating an air bag cushion upon collision. 
     It is also an object of the invention to provide a new motor vehicle steering column safety device that meets all of the original equipment manufacturer&#39;s (OEM) specifications and required regulations, can be cheaply manufactured and easily installed into any make and model of vehicle. 
     It is finally an object of the invention to provide a new motor vehicle steering column safety device which meets all of the above desired features. 
     In the broader aspects of the invention there is provided a collapsible steering column for a motor vehicle that has an elongated hollow cylinder slidably mounted on a piston while also fast to the piston for rotary movement. The space between the interior wall of the cylinder and the piston is sealed in a gas-tight fashion. A head is attached to the top of the cylinder. The head has a frangible seal hermetically secured inside it so that the top of the piston, the interior wall of the cylinder and the seal define an air cavity. The cavity is under pressure such that the cylinder is supported by a column of pressurized gas. A coil spring inside the cylinder urges the piston and the bottom of the cylinder apart. The seal has a bore in which resides an explosive compound. Lead lines connect the explosive compound with an electronic collision sensor, which is located in the front of the vehicle. When a collision occurs, the sensor sends an electronic signal which ignites the explosive compound and fractures the seal permitting the gas to escape from the cavity causing collapse of the cylinder. The vehicle&#39;s steering wheel is secured to the top of the head, and the piston is connected by way of appropriate linkages to the front wheels of the vehicle so that axial rotation of the cylinder, by way of the steering wheel, causes the front wheels to turn in accordance with normal vehicle operations. An air bag stowed in the steering wheel may be connected to the top of the head to capture the air released from the cavity providing additional protection to the occupant. 
    
    
     DRAWINGS 
     The above-mentioned and other features and objects of the invention and the manner of attaining them will become more apparent and the invention itself will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings wherein: 
     FIG. 1 is a fragmentary side view of a motor vehicle showing the steering column safety device in the extended position. 
     FIG.  1   a  is a fragmentary side view of a motor vehicle showing the steering column safety device in the collapsed position. 
     FIG. 2 is a side elevational perspective view of the steering column safety device of the invention. 
     FIG. 3 is a side elevational perspective view of an embodiment of the steering column safety device shown disassembled. 
     FIG. 4 is a side cross-section on the line  4 — 4  of FIG. 2 in the direction of the arrows showing the steering column safety device of the invention in the extended position. 
     FIG. 5 is a side cross-sectional view like the view shown in FIG. 4 except the steering column safety device of the invention is in the collapsed position. 
     FIG. 6 is a side cross-sectional view of the head of the steering column safety device. 
     FIG. 7 is a bottom view of an embodiment of the head of the steering column safety device. 
     FIG. 8 is an elevated side perspective view showing an embodiment of the seal of the steering column safety device of the invention. 
     FIG. 9 is an elevated side perspective view showing an embodiment of the piston. 
     FIG. 10 is a bottom cross-section on the line  10 — 10  of FIG. 9 in the direction of the arrows showing the boss and piston. 
     FIG. 11 is a bottom view of an embodiment of the cap of the invention. 
    
    
     DESCRIPTION 
     FIGS. 1 and 1A show steering column safety device  10  mounted in motor vehicle  12 . Electronic collision sensing means  20 , which is shown diagrammatically, is connected to steering column safety device  10  by wires  140 . Collision sensing means  20  is usually located in the front of vehicle  12  and has a microprocessor which produces the electronic signal for actuating safety device  10 . Referring to FIGS.  2 - 5 , steering column safety device  10  includes hollow cylinder  40 , head  110 , cap  50 , interior wall  41  connecting the top  42  of cylinder  40  with its bottom  44  and axial rod  320 . Cylinder  40 , head  110 , cap  50 , and axial rod  320  are generally axially aligned along axis  390  and formed from machinable metal, such as aluminum, brass, and/or steel alloy as desired. Cylinder  40 , head  110  and cap  50  may be insulated by known means or formed from an insulating material which is rigid and capable of containing elevated gas pressures of about 600 to 1,000 p.s.i. Head  110  is secured to top  42  of cylinder  40 , and cap  50  is secured to bottom  44  of cylinder  40  by known means, such as threads  82 . In an embodiment, the top of cylinder  40  and head  110  are secured together in a gas-tight fashion. Pressurized gas from atmospheric pressure to elevated pressures is contained in hollow cylinder  40 . 
     The top of head  110  is adapted for receiving standard steering wheel  24  in which resides air bag  200 . Cap  50  has bore  56  extending therethrough, as shown in FIG.  11 . The shape of bore  56  is the same as the cross-section of axial rod  320 , and tolerances of bore  56  and axial rod  320  are such as to accommodate axial movement of cap  50  with cylinder  40  and head  110  as a single unit along axial rod  320 . The preferred embodiment includes axial rod  320  having a square cross-section. In that embodiment, bore  56  is configured to the shape of a square such that bore  56  receives rod  320  and steering torque can be transmitted to the steering mechanism of vehicle  12  via steering wheel  24 , cylinder  40 , cap  50  and axial rod  320 , which all rotate as a single unit about axis  390 . 
     Inside hollow cylinder  40  is air cavity  60  for containing pressurized gas, piston  300 , and biasing means, such as coil spring  250  for biasing piston  300  and cap  50  apart. Another coil spring  400  may also be positioned in cylinder  40  in order to provide a means for damping the force placed on cylinder  40  by an occupant upon collision, as shown in FIG.  5 . 
     Referring to FIGS. 9 and 10, piston  300  includes generally cylindrical solid body  310  having boss  312  at one end and air cavity surface  314  at the other end. In the preferred embodiment, boss  312  is integrally formed with solid cylindrical body  310 . Circumferential wall  315  joins boss  312  with air cavity surface  314 . Boss  312  has rod seating bore  321  extending generally axially therein with pin hole  313  extending transversely through boss  312 . One embodiment has at least one o-ring groove  326  formed therein where at least one o-ring  328  resides. O-ring(s)  328  engage the interior wall of cylinder  40  in a gas-tight fashion so that o-ring(s)  328 , interior wall  41  of cylinder  40  and head  110  define air cavity  60 . Piston  300  is formed of machinable metal, such as aluminum, brass, and/or steel alloy as desired, and, in the embodiment shown, axial rod  320  connects boss  312  via roll pin  350  to the steering mechanism of vehicle  12 . Piston  300  may be formed of other material or composites thereof, so long as interior wall of cylinder  40  can slidably engage circumferential wall  315  on orings  328 . 
     Referring now to FIGS.  3  and  6 - 8 , top  42  of hollow cylinder  40  has outlet  43 , and head  110  is coupled thereto in a gas-tight fashion. In that embodiment, cylinder  40  contains pressurized gas. It is entertained, however, that head  110  is well-suited for use in connection with any pressurized fluid or gas container. Head  110  may be used in any vehicle having a collision sensing means connected thereto for producing a signal in response to a collision, where it is desirable to control the flow of pressurized fluid or gas from a container into an air bag connected inside a vehicle and deployed upon collision to protect an occupant. Thus, air bag  200  may be connected to head  110  using means known in the art. Head  110  includes o-rings  328 , seal  190  and spacer member  80 . Axial bore  160  extends through head  110  and includes bore wall  162  with entrance port  170 , outlet  43  and seal housing  175  formed therein. Entrance port  170  is tapered with the larger end contiguous with seal  190 . A generally transverse head bore  111  joins the exterior of head  110  and bore wall  162 . 
     Seal  190  is positioned within seal housing  175  and occludes axial bore  160 , as shown in FIG.  6 . O-rings  328  contact opposite sides  186 ,  188  of seal  190 , and spacer member  80  abuts o-ring  328  contiguous with opposite side  186 . Additional o-rings  328  may be positioned between bore wall  162  and spacer member  80  as desired. 
     Referring now to FIGS. 6 and 8, seal  190  includes frangible disc-shaped body  182  having opposite sides  186 ,  188  and wall  184 , which joins opposite sides  186 ,  188 . Disc-shaped body  182  may be formed from a number of glass composites and may have tempered or annealed portions as desired. One embodiment has opposite sides  186 ,  188  formed from a sodium lime glass composition and wall  184  formed from tempered glass. Seal bore  192  extends transversely into wall  184  of seal  190 . In that embodiment, tempered glass is well-suited for drilling bore  192  and resists shattering during manufacture. Explosive charge  194  resides in bore  192  and is formed from a mixture of pentaerythritol tetranitrate (PETN), lead azide, potassium perchlorate, and sulfur, for example. Explosive charge  194  requires an ignition temperature suitable for igniting by electrical means, such as a signal produced by sensing means  20 . In an embodiment explosive charge  194  has an ignition temperature of about 300 degrees Fahrenheit. 
     Seal  190  is positioned in seal housing  175  and rotated so that transverse bore  192  containing explosive charge  194  is aligned with head bore  111 . Wires  140 , therefore, are able to extend from transverse bore  192  through head bore  111  to the exterior of steering column safety device  10  connecting explosive charge  194  to sensing means  20 . 
     In operation, prior to collision, head  110 , including its contents secured as above-described, threadedly engages top  42  of cylinder  40  and is sealed by known means, such as pipe dope or tape. Pressurized gas or fluid is pumped into cavity  60  using known valving apparatus, such as a Schrader valve for example, connecting the exterior and interior of cavity  60  (not shown). This provides for steering column device  10  to be easily refueled after deployment avoiding the inconvenience of shipping steering column safety device  10  to the manufacturer in the event vehicle  12  is still operational. 
     It is entertained that cavity  60  can be pressurized upon manufacture as well. A breathable anhydrous gas such as nitrogen is preferred, because it is nontoxic and contains no water of crystalization. As the pressure inside cavity  60  is elevated, cylinder  40 , head  110  and cap  50  all move forward axially as a single unit relative to piston  300  and axial rod  320 , until reaching the extended position, as shown in FIGS. 1 and 4. Biasing means, such as coil spring  250 , assumes a compressed condition. Damping means, such as coil spring  400 , as shown in FIG. 5, is for the most part generally relaxed in the extended position, the collapsed position and therebetween. Steering column safety device  10  is capable of delivering steering torque and thus, is fully operational assuming normal vehicle steering column functions. 
     The occupant may deliver steering torque by way of steering wheel  24 . Steering torque is delivered to the steering mechanism of the vehicle via head  110 , cylinder  40 , piston  300 , cap  50  and axial rod  320 , which all rotate as a single unit about axis  390 . O-rings  328  on piston  300  engage the interior wall of cylinder  40  and displace rotational force from cylinder  40  to piston  300  and axial rod  320 . In other words, the side walls of bore  56  engage axial rod  320  transferring steering torque from steering wheel  24  to axial rod  320  via piston  300  during the extended position, the collapsed position and therebetween. 
     Upon collision, sensing means  20  produces a signal, which is communicated through wire  140  to head  110 . Wire  140  resides within head bore  111  and contacts explosive charge  194 . The signal ignites charge  194  causing charge  194  to explode such that a breach is formed in body  182 , thereby allowing rapid free flow of pressurized gas from air cavity  60  into air bag  200  via entrance port  170  and axial bore  160 . The amount and composition of explosive charge  194  determines the noise level and size of the breach formed in body  182 . In an embodiment, a small explosive charge  194  is provided such that body  182  is only cracked or fragmented so that the rush of pressurized gas from air cavity  60  completes the destruction of seal  190 . 
     Concurrently with the flow of gas out of cavity  60 , biasing means, such as coil spring  250 , rapidly assumes the relaxed position forcing cap  50  and boss  312  apart moving cylinder  40  axially rearwardly from the extended position to the collapsed position, as shown, respectively, in FIGS. 1,  1 A and  4 ,  5 . Air cavity  60  and head  110  are generally axially aligned such that the pressurized gas flows generally axially out of cavity  60 . The collapsing action of the cavity  60  forces pressurized gas out of cavity  60  axially at a rate exceeding a free flow. In addition, entrance port  170  guides the pressurized gas into the shape of a whirling vortex maximizing the rate at which pressurized gas flows from the cavity  60  and into air bag  200 . The rate of flow of the gas into the air bag far exceeds the rate of explosive-type air bag inflators without the use of toxic chemicals such as sodium azide. 
     Moreover, the same superior rates of collapse of the steering wheel column, like cylinder  40  for example, and inflation of air bag  200  can easily be achieved regardless of the make or model of the vehicle. The length and diameter of cylinder  40 , axial bore  160 , entrance port  170 , the degree of the taper of entrance port  170 , the gauge of coil spring  250 , the length of movement between the extended position and the collapsed position, the amount and size of explosive charge  194 , and so on, may all be adjusted to achieve the desired result specific to any make or model of vehicle. 
     Steering column safety device  10  of the invention discloses a generally axially aligned system that rapidly expands the inflator gas into the air bag cushion without utilizing explosive substances. Ignition of explosive charge  194  makes a sound similar to that of a child&#39;s cap gun whereby the occupant is not frightened and shattering of the vehicle&#39;s windows is precluded. 
     Moreover, the steering column safety device  10  of the invention is capable of delivering steering torque while collapsing the steering column concurrently with inflating an air bag upon collision. In addition, there is no incentive to steal steering wheel  24 , since it is a standard steering wheel  24  and not a fully operational safety device: it contains no inflator gases and is useless without head  110  and cylinder  40 . 
     Steering column safety device  10  collapses the steering column concurrently with inflating an air bag  200  without using pulleys, cables and/or other movable parts which can break or become worn and provides a faster, more efficient collapsible steering column than heretofore available. Thus, steering column safety device  10  is capable of providing added safety for all occupants, regardless of size, non-belt-restrained occupants and out-of-position occupants. 
     Finally, new motor vehicle steering column safety device  10  meets original equipment manufacturer&#39;s (OEM) specifications and all of the required regulations, and novel motor vehicle steering column safety device  10  can be cheaply manufactured and easily installed into any make and model of vehicle. 
     While a specific embodiment of the invention has been shown and described herein for purposes of illustration, the protection afforded by any patent which may issue upon this application is not strictly limited to the disclosed embodiment, but extends to all structures and arrangements which fall fairly within the scope of the claims which are appended hereto.