Patent Abstract:
A system for automatically detaching a windshield from a vehicle cab comprises a pressure applying device mounted between a windshield and a frame element, a roll-over condition sensor, and a controller connected to receive a signal indicating a roll-over condition from the roller-over condition sensor and connected to activate the pressure applying device responsive to receiving said signal. The pressure applying device may be one or more pyrotechnic devices. The system includes a delay function to delay activating the pressure applying device to allow the vehicle to come to a rest.

Full Description:
BACKGROUND AND SUMMARY 
     In certain vehicle accidents, it may be difficult, impossible, or unsafe to exit from the doors of the vehicle. In a vehicle roll-over, for example, one door is under the cab and the other door facing upward. In heavy trucks especially, the weight of the door makes it difficult to lift open and hold open, both for an emergency responder and more so for a vehicle occupant attempting this from the inside of the vehicle cab. Egress through the windshield frame may be the fastest and safest alternative. 
     The windshields in heavy trucks may be designed so that the windshield can be kicked out in the event exit from the doors is difficult or unsafe. If the driver or passenger is not able to kick out the windshield, however, response team personnel must attempt to remove the windshield with tools, usually by cutting it out. This is laborious and time-consuming, and may pose a safety concern, for example, if there is a fire in or around the vehicle, or if the occupants of the vehicle are in need of immediate medical attention. 
     Methods for dislodging or removing windshields, windows, and doors are known. For example, U.S. Pat. No. 3,737,193 to Cain discloses a collapsed tube disposed about a periphery of a windshield and connected to a high pressure fluid source that inflates the tube when an impact sensor senses the vehicle has been in a collision. Expansion of the tube dislodges the windshield from its mounting. U.S. Pat. No. 3,741,583 to Usui et al. discloses a pyrotechnic device that releases or destroys a windshield or window in a vehicle using the vehicle airbag triggering system to activate it. 
     While the art discloses systems that activate upon sensing a collision or impact on the vehicle, none are known that respond to a vehicle roll-over, which involves different dynamics than front end or side collisions. For example, an event leading to a roll-over may begin with a front end collision, which in prior system may trigger the windshield release system before event concludes, that is, before the vehicle comes to a rest. The dislodged windshield, now movable, may then pose a danger to the vehicle occupants. As another example, a roll-over may result from a driver attempting a curve at too high a rate of speed, which may involve no frontal collision and a side impact that may not be sufficient to trigger the system. 
     The invention provides a system for dislodging a vehicle windshield from its mounting automatically upon a vehicle roll-over event. 
     According to an embodiment of the invention, a system for detaching a windshield from a vehicle cab, comprises a pressure applying device mounted between a windshield and a frame element, a roll-over condition sensor, and a controller connected to receive a signal indicating a roll-over condition from the roller-over condition sensor and connected to activate the pressure applying device responsive to receiving said signal. 
     The invention, according to another aspect, may further comprise an acceleration condition sensor, the controller being connected to receive a signal indicating an acceleration condition from the acceleration condition sensor, and further configured to activate the pressure applying device responsive to receiving the roll-over condition signal and the acceleration condition signal. According to a preferred embodiment, the acceleration sensor generates a signal when vehicle acceleration ends, that is, when the vehicle has come to a rest. The acceleration sensor may alternatively or in addition be configured to detect a collision event, as in vehicle airbag systems. 
     In addition or alternatively, the controller is configured with a delay function to delay activating the pressure applying device for a predetermined time period following receipt of a signal indicating a roll-over condition from the roller-over condition sensor. 
     According to an alternative embodiment, a system of the invention includes the controller being connected to a vehicle device controlling deployment of a vehicle airbag system to receive a signal indicating deployment of the airbag. The controller is configured to use both the roll-over condition sensor and the airbag deployment sensor to trigger the pressure applying device. 
     According to the invention, a pressure applying device comprises at least one pyrotechnic device. A mounting device for a pyrotechnic device includes a frame element that contains and directs the energy from activated the pyrotechnic device toward the windshield to weaken or break the securing elements. 
     Alternatively, a pressure applying device comprises an inflatable tube and a gas generating device connected to inflate the tube upon receipt of a signal from the controller. 
     Other pressure applying devices may be employed, as the invention is not directed to a particular pressure applying device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be better understood by reference to the following detailed description read in conjunction with the appended drawings, in which: 
         FIG. 1  is a schematic of a windshield dislodging system according to an embodiment of the invention; 
         FIG. 2  is a schematic of a windshield dislodging system according to an alternative embodiment; 
         FIG. 3  is simplified section view of an embodiment for mounting a pyrotechnic device to a windshield mounting structure according to a first type; and, 
         FIG. 4  is a simplified section view of an embodiment for mounting a pyrotechnic device to a windshield mounting structure according to a second type. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates schematically an automatic windshield dislodging system in accordance with an embodiment of the invention. The system includes a controller  20  that is operatively connected to at least one pressure applying device  21  disposed in a vehicle windshield mounting frame  10 . The at least one pressure applying device  21  is configured to dislodge a windshield  12  from the mounting frame  10  upon a signal from the controller  20 . By dislodge is meant releasing the windshield  10  from the mounting structure so that it is displaced from the frame or is otherwise readily movable by a person outside the vehicle. 
     As illustrated, a plurality of pressure applying devices  21  are provided and are distributed on the periphery of the windshield frame  10  so to apply pressure at several points around the frame. In this embodiment, each of the plurality of pressure applying devices  21  is connected to the controller  20  for activation. The pressure applying device may be a pyrotechnic device, such as is used for inflating airbags in vehicles, which generates in a short time highly pressurized gas, which will be directed against the windshield. Those skilled in the art will know how to select a pyrotechnic device having an appropriate energy release to dislodge the windshield. 
     Alternatively, as shown in  FIG. 2 , the pressure applying device may be embodied as an inflatable tube  30  disposed about the periphery of the mounting frame in a position so that upon inflation, the tube applies pressure to the windshield  12 . A source of pressurized gas  23 , for example, a pyrotechnic device, is connected to the tube and activatable by the controller  20 . A pyrotechnic device is convenient as the source for rapid inflation of the tube, as is known in the airbag art. A single pyrotechnic device may be used, which will be selected to generate sufficient gas to inflate the tube to an appropriate pressure. Alternatively, two or more smaller pyrotechnic devices may be connected to various points on the tube, for example, to ensure simultaneous expansion of the tube about the periphery of the windshield  12 . 
     Returning to  FIG. 1 , the controller  20  is connected to receive a signal from a vehicle roll-over sensor or detector  40 . The roll-over sensor  40  detects a condition when the vehicle is no longer in a wheels-down attitude and generates a signal for the controller  20 . The controller  20  receives the roll-over condition signal and generates a signal to activate the pressure applying device or devices  21 . 
     According to a preferred embodiment, upon receipt of the roll-over signal, the controller  20  initiates a timer (not illustrated) to delay activation of the pressure generating device. The time delay may be chosen, for example, to be of sufficient duration so that the vehicle will likely have come to rest before the windshield is dislodged from the frame. 
     The time delay may also be used to avoid activating the system based on a spurious roll-over signal. After the time delay expires, the controller  20  will check that the roll-over signal is still valid before activating the pressure applying device. 
     According to yet another alternative, the system may include an acceleration sensor  50  connected to the controller  20  to deliver a signal relating to the acceleration condition of the vehicle. The acceleration sensor  50  may be configured to detect a collision, which results in a rapid acceleration or deceleration. The controller  20  will use this signal as a check on the validity of the vehicle condition requiring windshield dislodgement, the presence of both a collision condition and roll-over condition indicating an event where release of the windshield is needed. 
     Alternatively, the acceleration sensor  50  may be configured to detect when the vehicle has come to a rest, that is, the deceleration of the vehicle to a stop. This signal may be used by the controller  20  in place of the time delay, or in conjunction with the time delay, to determine when to activate the pressure generating device. 
       FIG. 3  shows a side section view, in highly simplified form, of an example of a windshield mounting frame  60  adapted for the invention. The frame  60  in  FIG. 3  is of the type in which an elastomeric extrusion  61  retains the windshield  12  and seals the frame  60 . The extrusion  61  has an S-shape profile with oppositely facing channels. One channel  63  receives a frame edge  65 , while the other channel  67  receives the windshield  12 . The frame  60  is modified to support the pressure applying device, which may be the pyrotechnic device  21  or the inflatable tube  30 . A member  69  having an arcuate profile is provided to support the device  21 ,  30  and direct the energy of the expansion of gas toward the windshield  12  and extrusion  61 . The member  69  may be a continuous channel formed on the inner periphery of the frame  60 , as illustrated. Alternatively, in the case of the pyrotechnic device  21 , the member may be configured as individual retaining members, such as cup shaped members, fastened to the frame  60  at appropriate locations. 
       FIG. 4  shows another example of windshield mounting frame  80  adapted for the invention. The frame  80  is configured to bond the windshield  12  with a layer of bonding material  81  applied between the frame and an outer periphery of the windshield. The frame  80  includes a member  83  having a cup-shaped profile to support the pressure applying device  21 ,  30  and direct the energy of the gas expansion to the windshield  12 , as in the embodiment of  FIG. 3 . The member  83  may be formed as a channel at an inner periphery of the frame  80 . Alternatively, in the case of the pyrotechnic device  21 , the member  83  may be configured as individual retaining members, such as cup shaped members, fastened to the frame  80  at appropriate locations. 
     The invention has been described in terms of preferred principles, embodiments, and components; however, those skilled in the art will recognize that equivalents may be substituted for what is described without departing from the scope of the invention as defined in the appended claims.

Technology Classification (CPC): 1