Abstract:
An inflatable device ( 10 ) has a vent ( 42 ) for enabling venting of inflation fluid. A patch ( 50 ) covers the vent ( 42 ). A release thread ( 70 ) releasably secures the patch ( 50 ) to the device to close the vent ( 42 ). A holding mechanism ( 82 ) has a first condition in response to a sensor ( 30 ) sensing a condition requiring venting of inflation fluid, and a second condition when venting is not required. The holding mechanism ( 82 ) when in the first condition holds the release thread ( 70 ) so that at least a portion of it pulls away from the patch ( 50 ) and the device ( 10 ), when the device inflates, thereby releasing the patch to open the vent ( 42 ). The holding mechanism ( 82 ) when in the second condition releases the release thread ( 70 ) for movement with the patch ( 50 ) in a direction away from the holding mechanism, when the device ( 10 ) inflates.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a vehicle occupant protection apparatus. In particular, the present invention relates to an air bag having a vent that can be selectively opened to discharge inflation fluid. 
     DESCRIPTION OF RELATED ART 
     It is known to provide an air bag with a vent. The vent opens, or is uncovered, when the air bag inflates to help protect a vehicle occupant, to discharge inflation fluid from the inflated air bag. In some air bags, the vent may be selectively opened depending on sensed factors, for example, whether the occupant&#39;s seat belt is buckled. U.S. Pat. No. 6,290,257 shows one such air bag. 
     SUMMARY OF THE INVENTION 
     The present invention in one embodiment relates to a vehicle occupant protection apparatus comprising an inflatable vehicle occupant protection device having a deflated condition and an inflated condition. The device has a portion defining a vent opening for enabling flow of inflation fluid out of the device. The apparatus includes a patch for covering the vent opening to block flow of inflation fluid out of the device through the vent opening. The apparatus also includes an inflator for directing inflation fluid into the device to inflate the device from the deflated condition to the inflated condition. A release thread sewn between the patch and the device releasably secures the patch to the protection device to close the vent opening. Sensor means senses a condition requiring venting of inflation fluid from the device when the device inflates. A holding mechanism has a first condition in response to the sensor means sensing a condition requiring venting of inflation fluid from the device, and a second condition in response to the sensor means not sensing a condition requiring venting of inflation fluid from the device. The holding mechanism when in the first condition holds the release thread so that at least a portion of the release thread pulls away from the patch and the device, when the device inflates, thereby releasing the patch to open the vent opening. The holding mechanism when in the second condition releases the release thread for movement with the patch in a direction away from the holding mechanism, when the device inflates. 
     In another embodiment, the present invention relates to a release thread that closes the vent opening when the protection device is in the deflated condition. The apparatus includes a clamp having a first condition clamping the release thread and a second condition not clamping the release thread. A controller controls operation of the clamp to cause the clamp to take the first condition in response to the sensor means sensing a condition requiring venting of inflation fluid from the device when the device inflates. The clamp takes the second condition in response to the sensor means not sensing a condition requiring venting of inflation fluid from the device when the device inflates. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and other features of the present invention will become apparent to one skilled in the art to which the present invention relates upon consideration of the following description of the invention with reference to the accompanying drawings, in which: 
     FIG. 1 is a sectional view of a portion of a vehicle occupant protection apparatus including an inflatable vehicle occupant protection device in accordance with the present invention; 
     FIG. 2 is a schematic view of a portion of the inflatable device of FIG. 1, including a patch covering a vent opening, and taken generally along line  2 — 2  of FIG. 1; 
     FIG. 3 is an enlarged view of a holding mechanism that forms part of the apparatus of FIG. 1; 
     FIG. 4 is a view similar to FIG. 1 showing the protection device in an inflated condition with the vent open; 
     FIG. 5 is a view similar to FIG. 4 showing the protection device in an inflated condition with the vent closed; 
     FIG. 6 is a view similar to FIG. 1 of a portion of a vehicle occupant protection apparatus including an inflatable protection device in accordance with a second embodiment of the invention; 
     FIG. 7 is a schematic view of a portion of the inflatable device of FIG. 6, including a stitching section closing a vent opening, and taken generally along line  7 — 7  of FIG. 6; 
     FIG. 8 is a view similar to FIG. 6 showing the protection device in an inflated condition with the vent open; 
     FIG. 9 is a view similar to FIG. 6 showing the protection device in an inflated condition with the vent closed; 
     FIG. 10 is an enlarged schematic view of a holding mechanism that forms part of the apparatus of FIG. 6, shown in a first condition; 
     FIG. 11 is a view similar to FIG. 10 showing the holding mechanism in a second condition; 
     FIG. 12 is a view similar to FIG. 7 of a portion of an inflatable protection device in accordance with a third embodiment of the invention, showing a vent in a closed condition; 
     FIG. 13 is a view similar to FIG. 12 showing the vent in an open condition; 
     FIG. 14 is a view similar to FIG. 12 of a portion of an inflatable protection device in accordance with a fourth embodiment of the invention, showing a vent in a closed condition; and 
     FIG. 15 is a view similar to FIG. 14 showing the vent in an open condition. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention relates to a vehicle occupant protection apparatus. In particular, the present invention relates to an air bag having a vent that can be selectively opened to discharge inflation fluid. As representative of the present invention, FIG. 1 illustrates a portion of an inflatable vehicle occupant protection device in the form of an air bag  10 . Other inflatable vehicle occupant protection devices that can be used in accordance with the invention include, for example, inflatable seat belts, inflatable knee bolsters, inflatable head liners, inflatable side curtains, and knee bolsters operated by inflatable air bags. 
     The air bag  10  forms part of a vehicle occupant protection apparatus  12 . The apparatus  12  includes an inflator  14  for inflating the air bag  10 . The inflator  14  may contain a stored quantity of pressurized inflation fluid and an ignitable material for heating the inflation fluid. The apparatus  12  alternatively could include an inflator that uses the combustion of gas generating material to generate inflation fluid in the form of gas to inflate the air bag  10 , or an inflator that contains only a stored quantity of pressurized inflation fluid for inflating the air bag. 
     The apparatus  10  includes vehicle electric circuitry indicated schematically at  20  (FIG.  1 ). The vehicle electric circuitry  20  controls the operation of the inflator  14 . The vehicle electric circuitry  20  includes a power source  22 , which is preferably the vehicle battery and/or a capacitor, and a normally open switch  24 . The switch  24  is part of a collision sensor  26 , which senses a condition indicating the occurrence of a vehicle collision. The collision-indicating condition may comprise, for example, sudden vehicle deceleration caused by a collision. The vehicle electric circuitry  20  further includes a controller, or control module,  28  for controlling the operation of the vehicle electric circuitry, and a sensor assembly  30 . 
     The sensor assembly  30  includes one or more sensors that generate one or more control signals useful in determining whether to inflate the air bag  10  with maximum speed and force when a vehicle collision is sensed. For example, the sensor assembly  30  may include an occupant position sensor that generates a control signal indicative of the position of a vehicle occupant in the interior of a vehicle. The sensor assembly  30  may also include a buckle switch for generating a control signal indicative of a buckled or unbuckled condition of a seat buckle assembly of the vehicle. The sensor assembly  30  may also include one or more of the following: a sensor that senses the presence of a rearward-facing child seat, a weight sensor, a belt tension sensor, an occupant size sensor, a module temperature sensor, or a crash severity sensor. 
     The air bag  10  is preferably made from a flexible fabric material, such as woven nylon. The air bag  10  can alternatively be made from a non-woven material, such as plastic film. The air bag  10  has a generally pillow-shaped configuration when fully inflated and is designed for a driver-side application. The invention is applicable to air bags  10  that are used in other locations, for example, passenger side air bags or side impact air bags. 
     The air bag  10  defines an inflation fluid volume  32  for receiving inflation fluid from the inflator  14 . The air bag  10  has an inflation fluid opening  34  for receiving inflation fluid from the inflator  14  to inflate the air bag  10 . The air bag  10  is secured to the inflator  14  by a retainer or retaining ring shown partially at  36 . The assembly of the air bag  10 , retainer  36 , and inflator  14  is fixed in position in the vehicle by, for example, a mounting plate (not shown). 
     The air bag  10  includes a panel  40 . The panel  40  has a vent for discharging inflation fluid from the air bag  10 . In the illustrated embodiment, the vent is an opening  42  (FIG. 2) in the panel  40  having a circular configuration centered on a point  44 . The vent  42  is defined by a portion  46  of the panel  40  that extends around and encloses the vent. 
     The vent  42  is covered by a patch  50 . The patch  50  is a piece of material that is secured to the panel  40  of the air bag  10 , in a manner described below, and that blocks flow of inflation fluid out of the air bag through the vent  42 . The patch  50  may be made from the same material as the other parts of the air bag  10 , or may be made from a different material. In the illustrated embodiment, the patch  50  is a circular piece of fabric material larger in diameter than the vent  42 . The patch  50  has first and second opposite major side surfaces  52  and  54  (FIG.  1 ). 
     The air bag  10  includes two stitching sections  60  and  62  (FIG. 2) that together secure the patch  50  to the panel  40 . The stitching section  60  is a permanent stitching section that permanently secures one edge portion  64  of the patch  50  to the panel  40 . The stitching section  62  is a releasable stitching section that releasably secures another edge portion  66  of the patch  50  to the panel  40  when the air bag  10  is uninflated and, in some cases, when it is inflated. 
     The permanent stitching section  60  (FIG. 2) extends through the edge portion  64  of the patch  50  and through the panel  40  of the air bag  10 . The permanent stitching section  60  extends around the vent  42  in an arcuate configuration centered on the center point  44 . The permanent stitching section  60  in the illustrated embodiment has an arcuate extent as indicated by the arrow α of just under ninety degrees. 
     The releasable stitching section  62  extends through the edge portion  66  of the patch  50  and through the panel  40  of the air bag  10 . The releasable stitching section  62  extends around the vent  42  in an arcuate configuration centered on the center point  44 . The releasable stitching section  62  in the illustrated embodiment has an arcuate extent as indicated by the arrow β of just under two hundred seventy degrees. 
     The releasable stitching section  62  is formed by a release thread  70 . The release thread  70  is a filament, a group of filaments twisted together, or a filamentous length formed by spinning and twisting short textile fibers into a continuous strand. The thread  70  may be a fine continuous strand made by plying two or more of these filament groups or lengths with a tight twist and smooth finish. The thread  70  may be made of various materials, such as natural fabric, a plastic (for example, nylon), or another material suitable for sewing. The thread  70  may be the same as, or similar to, the material that is used to sew together various panels of the air bag. The thread  70  used to form the releasable stitching section  62  may be the same as, or similar to, the thread that is used to form the permanent stitching section  60 . 
     The thread  70  shown in FIGS. 1 and 2 is a single continuous length of material having a first portion  72  that forms the releasable stitching section  62 , a second portion  74  (FIG. 3) that forms an opposite end of the thread, and an intermediate or pulling portion  76 . 
     The releasable stitching section  62  has opposite ends  78  and  80 . The releasable stitching section  62  is spaced apart, at its ends  78  and  80 , from the permanent stitching section  60 . 
     The intermediate portion  76  of the thread  70  extends from one end  78  of the releasable stitching section  62 . The intermediate portion  76  extends to the end portion  74  of the thread  70  located adjacent a fixed portion of the vehicle occupant protection apparatus  12 , that is, a portion that does not move when the air bag  10  is inflated. The end portion  74  of the thread  70  is formed as a loop. 
     The apparatus includes a holding mechanism  82  located adjacent the inflator  14 , for holding the end portion  74  of the thread  70 . The holding mechanism  82  is fixed in position relative to the inflator  14 , and is thus a fixed portion of the apparatus  12 . The holding mechanism  82  includes a solenoid  84  having a movable pin or part  86 . The looped end portion  74  of the thread  70  extends around the pin  86  of the solenoid  84 . The solenoid  84  is electrically actuatable over lead wires  88  (FIG.  1 ). The lead wires  88  are connected with the controller  28  of the vehicle electric circuitry  20 . Upon actuation of the solenoid  84 , the pin  86  is movable in a direction into and out of the plane of the paper, as viewed in FIG.  3 . 
     If a collision-indicating condition sensed by the collision sensor  26  indicates the occurrence of a collision for which inflation of the air bag  10  may be desired to help protect the occupant of the vehicle, the switch  24  in the collision sensor  26  closes. The controller  28  determines, on the basis of inputs from the sensor assembly  30 , whether the air bag  10  should be inflated and, if so, whether the vent  42  should be opened. 
     If the air bag  10  is to be inflated, the controller  28  transmits an actuation signal to the inflator  14  over lead wires  90 . When the inflator  14  is actuated, it emits a large volume of inflation fluid into the inflation fluid volume  32  of the air bag  10 . 
     If the vent  42  is not to be opened, the solenoid  84  is actuated with a signal over the lead wires  88 . The actuation of the solenoid  84  causes the pin  86  to be moved to a position in which it no longer holds the end portion  74  of the thread  70  against movement away from the holding mechanism  82  and the inflator  14 . 
     As the air bag  10  inflates thereafter, the patch  50  and the portion of the panel  40  surrounding the vent opening  42  move away from the holding mechanism  82 . The force of movement of the patch  50  is transmitted into the thread  70 , pulling the thread away from the holding mechanism  82 . Because the end portion  74  of the thread  70  is not held by the pin  86 , the entire thread  70  moves away from the holding mechanism  82 , with the patch  50  and the inflating air bag  10 . Because the thread  70  moves with the patch  50 , there is no force placed on the thread that would cause it to tear out of, or be released from, the panel  40  and the patch. Therefore, the patch  50  remains secured to the panel  40  by both the permanent stitching section  60  and the releasable stitching section  62 . The vent  42  remains covered, or closed. 
     If, on the other hand, the controller  28  determines that the vent  42  should be opened, the solenoid  84  is not actuated. The solenoid pin  86  remains in a position inside the looped end portion  74  of the thread  70 , holding the end portion of the thread against movement away from the holding mechanism  82  and the inflator  14 . 
     As the air bag  10  inflates thereafter, the patch  50  and the portion of the panel  40  surrounding the vent opening  42  move away from the holding mechanism  82 . The force of movement of the patch  50  is transmitted into the thread  70 , pulling the thread away from the holding mechanism  82 . Because the end portion  74  of the thread  70  is held by the pin  86 , the thread becomes taut. The tensile force on the thread  70  increases to a level at which the thread is caused to tear out of, or be released from, the panel  40  and the patch  50 . Specifically, the releasable stitching section  62  is pulled out of the air bag  10 , releasing the edge portion  66  of the patch  50  for movement away from the panel  40 . The vent  42  in the panel  40  is uncovered or opened. The vent  42  opens to an open condition to permit flow of pressurized fluid from the air bag  10  through the vent. 
     Because the releasable stitching section  62  is spaced apart, at its ends  78  and  80 , from the permanent stitching section  60 , the releasing of the thread  70  does not affect the permanent stitching section. As a result, the permanent stitching section  60  does not rupture or tear out of the panel  40 . The permanent stitching section  60  acts as a tether to keep the patch  50  on the panel  40 , while inflation fluid is venting from the air bag  10 . It should be understood that an air bag in accordance with the present invention may include a patch  50  that comes off the air bag panel  40  completely. Thus, the permanent section stitching  60  may not be needed, and the patch  50  may be secured to the panel  40  by only a releasable stitching section  62 . 
     FIGS. 6-11 illustrate a vehicle occupant protection apparatus  12   a  in accordance with a second embodiment of the present invention. The apparatus  12   a  is similar in many respects to the apparatus  12  (FIGS.  1 - 5 ). Parts of the apparatus  12   a  (FIGS. 6-11) that are the same as or similar to parts of the apparatus  12  are given the same reference numerals with the suffix “a” attached. 
     In the apparatus  12   a , the vent opening  42   a  in the air bag  10   a  is formed differently. In addition, the holding mechanism  82   a  is different in the apparatus  12   a  than in the apparatus  12 . 
     Specifically, in the apparatus  12   a , the air bag  10   a  includes a vent opening  42   a  that is formed as a cut or slit in the panel  40   a . The cut  42   a  is a linear cut that extends between two adjacent portions  43  and  45  of the panel  40   a . In another embodiment, the cut  42   a  could have a different configuration. 
     The opening  42   a  is closed with a portion  62   a  of a thread  70   a . The thread portion  62   a  is a releasable stitching section that extends for substantially the entire length of the opening  42   a , so that the flow of inflation fluid through the opening is blocked. An intermediate portion  76   a  of the thread  70   a  extends from the stitching section  62   a , to the holding mechanism  82   a . There is no permanent stitching section holding the vent opening  42   a  closed. 
     An end portion  74   a  of the thread  70   a  is clamped in the holding mechanism  82   a . The holding mechanism  82   a  comprises a solenoid shown schematically at  84   a . The solenoid  84   a  has a pin or other movable part  86   a  with a groove  87 . Received in the groove  87  is the end portion  74   a  of the thread  70   a . The end portion  74   a  has a knot  89 . The knot  89  engages the pin  86   a  to block movement of the thread end portion  74   a  through the groove  87 . The pin  86   a  is adjacent a clamping surface  91 . 
     The pin  86   a  of the solenoid  84   a  is movable between a first condition shown in FIG. 10 and a second condition shown in FIG.  11 . Movement of the pin  86   a  is controlled in the same manner as in the first embodiment. Thus, the position of the pin  86   a , holding or releasing the thread  70   a , is set by the vehicle electric circuitry  20 . When the solenoid  84   a  is in the first condition shown in FIG. 10, the engagement of the pin  86   a  with the clamping surface  91  blocks movement of the end portion  74   a  of the thread  70   a  through the groove  87  in the pin. Thus, the thread  70   a  can not be pulled from the holding mechanism  82   a . When the solenoid  84   a  is in the second condition shown in FIG. 11, the pin  86   a  is moved away from the clamping surface  91 . The end portion  74   a  of the thread  70   a  is released from the holding mechanism  82   a.    
     If the air bag  10   a  is to be vented when inflated, the air bag is inflated while the solenoid  84   a  is in the first condition (FIGS.  8  and  10 ). As the air bag  10   a  inflates, the portion of the panel  40   a  surrounding the vent opening  42   a  moves away from the holding mechanism  82   a . The force of movement of the panel  40   a  is transmitted into the thread  70   a , pulling it away from the holding mechanism  82   a . Because the end portion  74   a  of the thread  70   a  is held by the pin  86   a , the thread becomes taut. The tensile force on the thread  70   a  increases to a level at which the thread is caused to tear out of, or be released from, the panel  40   a . Specifically, the releasable stitching section  62   a  is pulled out of the air bag  10   a . The vent  42   a  in the panel  40   a  is uncovered or opened. The vent  42   a  opens to an open condition to permit flow of pressurized fluid from the air bag  40   a  through the vent. 
     If the bag  10   a  is not to be vented when inflated, the air bag is inflated while the solenoid  84   a  is in the second condition (FIGS.  9  and  11 ). As the air bag  10   a  inflates, the portion of the panel  40   a  surrounding the vent opening  42   a  moves away from the holding mechanism  82   a . The force of movement of the panel  40   a  is transmitted into the thread  70   a , pulling the thread away from the holding mechanism  82   a . Because the end portion  74   a  of the thread  70   a  is released from the holding mechanism  82   a , the thread does not become taut. The stitching section  62   a  is not torn out of, or pulled out of, the panel  40   a  of the air bag  10   a . The vent  42   a  in the panel  40   a  remains in the closed condition shown in FIG.  7 . 
     FIGS. 12-13 illustrate a portion of a vehicle occupant protection apparatus  12   b  in accordance with a third embodiment of the present invention. In the apparatus  12   b , a vent opening  42   b  in a panel  40   b  of an air bag  10   b  is formed as a cut or slit in the bag between two adjacent panel portions  43   b  and  45   b . The vent opening  42   b  is sewn shut with a releasable stitching section  62   b . The releasable stitching section  62   b  is part of a thread  70   b  that extends from the panel  40   b  to a holding mechanism or clamp shown schematically at  82   b.    
     If the air bag  10   b  is to be vented when inflated, the air bag is inflated while the thread  70   b  is held from movement away from the holding mechanism  82   b . As the air bag  10   b  inflates, the portion of the panel  40   b  surrounding the vent opening  42   b  moves away from the holding mechanism  82   b . The force of movement of the panel  40   b  is transmitted into the thread  70   b , pulling the thread away from the holding mechanism  82   b . Because the end portion  74   b  of the thread  70   b  is held by the holding mechanism  82   b , the thread becomes taut. The tensile force on the thread  70   b  increases to a level at which the portion  62   b  of the thread is caused to tear out of, or be released from, the panel  40   b . The thread  70   b , however, is long enough so that not all of it pulls out of or releases from the panel  40   b . Specifically, an end portion  71  of the thread  70   b  remains attached to the air bag panel  40   b , as shown in FIG. 13, when the vent  42   b  in the panel is opened. 
     FIGS. 14-15 illustrate a portion of a vehicle occupant protection apparatus  12   c  in accordance with a fourth embodiment of the present invention. The apparatus  12   c  is similar in many respects to the apparatus  12  (FIGS.  1 - 5 ). Parts of the apparatus  12   c  that are the same or similar to parts of the apparatus  12  are given the same reference numerals with the suffix “c” attached. 
     In the apparatus  12   c , the patch  50   c  of the air bag  10   c  is secured to the panel  40   c  of the air bag solely by a releasable stitching section  62   c . The releasable stitching section  62   c  extends substantially completely around the outer periphery of the patch  50   c , thus closing the vent opening  42   c . The releasable stitching section  62   c  is part of a thread  70   c  that extends from the panel  40   c  to a holding mechanism or clamp shown schematically at  82   c.    
     If the air bag  10   c  is to be vented when inflated, the air bag is inflated while the thread  70   c  is held from movement away from the holding mechanism  82   c . As the air bag  10   c  inflates, the portion of the panel  40   c  surrounding the vent opening  42   c  moves away from the holding mechanism  82   c . The force of movement of the panel  40   c  is transmitted into the thread  70   c , pulling the thread away from the holding mechanism  82   c . Because the end portion  74   c  of the thread  70   c  is held by the holding mechanism  82   c , the thread becomes taut. The tensile force on the thread  70   c  increases to a level at which the portion  62   c  of the thread is caused to tear out of, or be released from, the panel  40   c  and the patch  50   c . The thread  70   c , however, is long enough so that not all of it pulls out of or releases from the panel  40   c . Specifically, an end portion  75  of the thread  70   c  remains attached to the patch  50   c  and to the air bag panel  40   c , as shown in FIG. 15, when the vent  42   c  in the panel is opened. The end portion  75  maintains the patch  50   c  connected with the panel  40   c , even when the vent  42   c  is opened. This prevents the patch  50   c  from coming completely off the panel  40   c.    
     From the above description of the invention, those skilled in the art will perceive improvements, changes and modifications in the invention. Such improvements, changes and modifications within the skill of the art are intended to be covered by the appended claims.