Abstract:
An automobile safety glass breaker tool is held against an automobile safety glass window and fired to break the window. The tool is armed by sliding a firing pin piston to the rear against a spring and fired by releasing the firing pin piston. The firing pin piston hits a 22 blank cartridge to fire the blank cartridge. The blank cartridge drives a striker piston forward, and a striker point on the striker piston impacts and shatters the automobile safety glass window. The striker point is limited to reach about 0.6 inches forward and out of the tool to prevent injury to a user.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to controlled breaking of glass and in particular to a tool for breaking automobile windows. 
     Automobiles involved in traffic accidents often are damaged to the extent that the occupants cannot easily escape the automobile. When there is a fire or risk of a fire, or the automobile is submerged or becoming submerged, or there is a risk of the automobile sliding down a slope, a rapid escape by the occupants is very important. 
     Various tools are known for breaking automobile window glass to allow escape. U.S. Pat. No. 6,418,628 issued Jul. 16, 2002 discloses a spring actuated tool for fire fighters and emergency personnel for breaking automobile glass. Unfortunately, such spring actuated tools do not always break the glass, and over time, the springs may weaken. Other similar tools do not always provide the necessary result. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention addresses the above and other needs by providing an automobile safety glass breaker tool which is held against an automobile safety glass window and fired to break the window. The tool is armed by sliding a firing pin piston to the rear against a spring and fired by releasing the firing pin piston. The firing pin piston hits a .22 blank cartridge to fire the blank cartridge. The blank cartridge drives a striker piston forward, and a striker point on the striker piston impacts and shatters the automobile safety glass window. The striker point is limited to reach about 0.6 inches forward and out of the tool to prevent injury to a user. 
     In accordance with one aspect of the invention, there is provided a .22 blank cartridge actuated automobile safety glass breaker tool. Known tools are spring actuated and limited by the impact force of the spring. The springs often do not provide a sufficient impact to shatter automobile safety glass. 
     In accordance with another aspect of the invention, there is provided a very short travel automobile safety glass breaker tool. The expanding gasses provided by the 22 blank cartridge drives the point quickly and firmly against the glass. A preferred travel of 0.060 inches reduces or eliminates the possibility of injury should the tool be fired against a human. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       The above and other aspects, features and advantages of the present invention will be more apparent from the following more particular description thereof, presented in conjunction with the following drawings wherein: 
         FIG. 1  is a side view of an automobile safety glass breaker tool according to the present invention. 
         FIG. 2  is a cross-sectional view of the automobile safety glass breaker tool according to the present invention taken along line  2 - 2  of  FIG. 1 . 
         FIG. 3  is an exploded cross-sectional view of the automobile safety glass breaker tool according to the present invention taken along line  2 - 2  of  FIG. 1 . 
         FIG. 4  shows the automobile safety glass breaker tool according to the present invention pressed against a safety glass window ready for use. 
         FIG. 4A  shows a cross-sectional view of the automobile safety glass breaker tool according to the present invention ready for use. 
         FIG. 5  shows the automobile safety glass breaker tool according to the present invention pressed against a shattered safety glass window after use. 
         FIG. 5A  shows a cross-sectional view of the automobile safety glass breaker tool according to the present invention after use. 
     
    
    
     Corresponding reference characters indicate corresponding components throughout the several views of the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The following description is of the best mode presently contemplated for carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of describing one or more preferred embodiments of the invention. The scope of the invention should be determined with reference to the claims. 
     A side view of an automobile safety glass breaker tool  10  according to the present invention is shown in  FIG. 1 . The tool  10  includes a striker tip  12   a  of a striker  12 , a striker housing cap  14  having a forward face  14   a  of the safety glass breaker tool, a striker housing  16 , a firing pin piston housing  18  providing a handle for the tool  10 , a trigger  20 , a longitudinally extending trigger slot  22 , and a trigger housing cap  24 . The trigger slot  22  includes a first angular recess  22   a  at an end nearest to the striker  12 , and a second angular recess  22   b  farthest from the striker  12 . The second angular recess  22   b  is sloped axially towards the striker  12  providing a cocked position for the trigger  20 . The trigger slot  22  has an overall length L 5  of preferably 0.9 inches. Elements for the tool  10  are generally cylindrical with a round cross-section, except for the trigger  20 , the trigger slot  22 , and the firing pin  29 . 
     A cross-sectional view of the tool  10  taken along line  2 - 2  of  FIG. 1  is shown in  FIG. 2  and an exploded cross-sectional view of the tool  10  taken along line  2 - 2  of  FIG. 1  is shown in  FIG. 3 . The striker  12  is attached to a striker piston  13  including a first diameter cylindrical portion  13   a  and a second diameter cylindrical portion  13   b , separated by a step  13   c . The first cylindrical portion  13   a  has a length L 1  of preferably 0.6 inches and a diameter D 2  of preferably 0.25 inches. The second cylindrical portion  13   b  has a length L 2  of preferably 0.4 inches and a diameter D 3  of preferably 0.38 inches. The striker  12  is preferably a very hard material, for example, tungsten carbide or the like, and is preferably embedded in the striker piston  13  and has a diameter D 1  of preferably ⅛ inches and a half angle A preferably between 30 degrees and 45 degrees, and more preferably 45 degrees. The second cylindrical portion  13   b  sides inside the striker housing  16  having an inside diameter ID 1  of preferably 0.385 inches. The striker piston  13  is preferably an oil impregnated bronze material (e.g., oilite) or the like providing smooth sliding in the striker housing  16 . 
     The striker housing cap  14  includes male threads  15  engaging female threads  17   a  in the striker housing  16 . The striker housing cap  14  includes a striker stop surface  14   a  facing the step  13   c  and limiting reach of the striker  12  out of the glass breaker tool  10  to a travel T of preferably between 0.04 inches and 0.1 inches, and more preferably between 0.04 inched and 0.08 inches, and most preferably 0.06 inches. In general, the travel T is not more than 0.06 inches to avoid possible injury to a user. 
     The striker housing  16  further includes a rear reaching male threaded portion  17   b  threading into female threads  18   a  of the firing pin piston housing  18 . The threaded portion  17   b  and  18   a  are preferably a ⅜ inch thread. The firing pin piston housing  18  includes a clip  27  residing in a groove  18   b  recessed past the threads  18   a . When the piston housing is fully threaded onto the threaded portion  17   b , the clip  27  holds a blank cartridge  26  residing in a blank cartridge position  26   c  against a rear facing blank cartridge stop surface  16   a  of the striker housing  16 . The blank cartridge  26  is preferably a 22 blank cartridge, for example, a WALTHER 6 mm Flobert blank cartridge. Alternatively, a step may be formed in the firing pin piston housing  18  to sandwich the blank cartridge  26 . The striker piston housing  16  and blank cartridge  26  form a closed striker housing chamber  16   b  for capturing pressure created by firing the blank cartridge  26  to drive the striker piston  13  forward. The striker housing chamber  16   b  has a volume V of preferably between 0.16 cubic inches and 0.04 cubic inches, and preferably 0.08 cubic inches. The clip  27  may be replaced by an internal forward facing step in the piston housing  18 . 
     A piston  28  slides in the firing pin piston housing  18 . The piston  18  includes the fixed firing pin  29  on a front facing surface for firing the blank cartridge  26 . The blank cartridge  26  is preferably a rim fire blank cartridge and the pin  29  is offset. Alternatively, a centerfire blank cartridge may be used with a centered pin. The piston  28  has a length L 4  of preferably 1.5 inches and includes a front portion  28   a  having a diameter D 4  of preferably 0.312 inches and a rear portion  28   b  having a diameter D 5  of preferably 0.215 inches. A step  28   c  separates the portions  28   a  and  28   b . A spring  30  resided over the rear portion  28   b  and is held between the step  28   c  and the trigger housing cap  24  providing forward force on the piston  28 . The spring  30  preferably has a spring rate between four and twelve pounds per inch, and more preferably eight pounds per inch, and has a free length L 6  of preferably between 1.5 and 2.5 inches and more preferably two inches. The trigger  20  includes a shaft  20   a  engaging a hole  21  in the piston  28 . The shaft  20   a  passes through the firing pin piston housing  18  allowing actuation of the trigger  20  to cock the tool  10  and to fire the tool  10 . The trigger housing cap  24  includes female threads  25  engaging male threads  19  on the firing pin piston housing  18 . 
       FIG. 4  shows the tool  10  pressed against a safety glass window  40  ready for use and  FIG. 4A  shows a cross-sectional view of the tool  10  ready for use. The trigger  20  is drawn to the rear of the slot  22  and may be caught in the second recess  22   b  or held to the rear. 
       FIG. 5  shows the tool  10  pressed against a shattered safety glass window  40  after use and  FIG. 5A  shows a cross-sectional view of the tool  10  after use. The striker  12  is limited to the travel T to prevent injury to a user. 
     While the invention herein disclosed has been described by means of specific embodiments and applications thereof, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope of the invention set forth in the claims.