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You are an expert at summarizing long articles. Proceed to summarize the following text: 
CROSS REFERENCE To RELATED APPLICATIONS 
       [0001]    Reference is made to and priority claimed from U.S. provisional application Ser. No. 61/190,135 filed on Aug. 26, 2008. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention pertains to the field of door openers. More particularly, the present invention pertains to the field of motorized door openers designed to open and close doors on motor vehicles. 
       BACKGROUND OF INVENTION 
       [0003]    Military and security force motor vehicles are often armored to protect occupants from bullets, bombs and other threats, but armoring creates doors often weighing as much as 1000 pounds, making manually opening the door difficult or impossible when the vehicle is positioned on a sloped or other non horizontal surface. Also, attachments mounted to the outside of the doors create a problem where in a typical four door vehicle, having two doors per side, when the rear door is opened at a particular angle, the front door cannot open fully because the attachment protrudes into the path of the front door, blocking the front door from opening fully. 
         [0004]    Thus, it would be advantageous to have a motorized door opener that automatically opens and closes the doors of a vehicle, but that can also sense the position of all the doors so that the opener does not damage any of the doors while the opener is in operation. Additionally, it would be advantageous for the motorized door opener to be able to use existing door hinges, negating the need to extensively modify or redesign the door itself. It would be further advantageous to have a door opener that does not itself protrude into the door opening, thus maximizing the entry/exit space for passengers and their equipment. 
       SUMMARY 
       [0005]    The invention provides for a motorized door opener which automatically opens and closes a door, senses door position to ensure no door is damaged when the opener is in operation, and has an emergency feature that allows manual opening and closing of the door. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The features and advantages of the invention will become apparent from a consideration of the subsequent detailed description presented in connection with accompanying drawings, in which: 
           [0007]      FIG. 1  is a top perspective view of a motorized door opener according to the invention. 
           [0008]      FIG. 2  is a side perspective view of the door opener attached to a vehicle body with the door in a closed position. 
           [0009]      FIG. 3  is a perspective view of the door opener attached to a vehicle body with the door in an open position. 
           [0010]      FIG. 4  is a top perspective view of the door opener attached to a vehicle body and to a front door and a rear door, both doors in open position showing the location of the opener with respect to the door opening. 
           [0011]      FIG. 5  is a perspective view of a mechanical control link. 
           [0012]      FIG. 6  is a perspective view of a safety release mechanism and the lever arm. 
           [0013]      FIG. 7  is a detailed perspective view of a mechanical bearing housing attached to an end of the actuator and showing the safety release lever in an engaged position. 
       
    
    
     DRAWINGS LIST OF REFERENCE NUMERALS 
       [0014]    The following is a list of reference labels used in the drawings to label components of different embodiments of the invention, and the names of the indicated components.
     20  heim joint     24  safety release mechanism housing     24   c  distal end of the safety release mechanism housing     30  safety release mechanism     32  safety release lever     34  manual release (cable system)     36  notches in housing     46  mechanical control link     46   a  fastener for active gear defining a pivot point     46   b  fastener for gear rack defining the hinge and gear rack pivot point     48  gear rack     49  active gear     50  lever arm     50   a  lever arm first end     50   b  lever arm second end     50   c  attachment point to the linear motor     50   d  pitch diameter (center line of where the gear rack and the active gear meet)     52   a  motor first end     52   b  motor second end     52   c  cover tube     52   d  telescoping arm     54  position sensors     56  controller     60  linear motor including a cover tube and a telescoping arm     100   a  front door opener     100   b  rear door opener     102  vehicle roof     103   a  door adaptor     103   b  door adaptor     104  vehicle door hinge     105  rear vehicle door     105   a  interior rear vehicle door     105   b  exterior rear vehicle door     106  front vehicle door     106   a  interior front vehicle door     106   b  exterior front vehicle door     108   a  vehicle adaptor     108   b  vehicle adaptor     108   c  vehicle adaptor   
 
       DETAILED DESCRIPTION 
       [0054]    The invention is described here in terms of an embodiment including two front door openers and two rear door openers, for opening armored doors of a HMMWV (High Mobility Multipurpose Wheeled Vehicle). It should be understood, however, that the invention has more general applicability. The invention can be used in case of any hinged door of a motor vehicle where the door extends in close proximity to the roof of the vehicle. 
         [0055]    Referring to  FIGS. 1 to 6 , the invention provides front and rear motorized door openers  100   a    100   b  for opening a front door  106  and a rear door  105  ( FIG. 2 ) of a vehicle, respectively. The door openers provided by the invention are especially of use in case of an armored door, which can weigh several hundred pounds, such as a door of a HMMWV armored against blast. The front and rear motorized door openers are substantially the same in the embodiment shown and described here, the main difference being that the front and rear door openers use different door adapter plates  108   a - c,    103   a - b  by which the door openers attach to the vehicle and to the doors. 
         [0056]    In the embodiment of the invention shown in  FIGS. 1-3  and  5  and focusing specifically on the front door opener  100   a,  the front door opener  100   a  includes a rigid mounted gear rack  48  having a plurality of teeth around a substantial part of its perimeter and a non-toothed side of the gear rack  48  affixed to a vehicle adaptor  108   a  that is in turn affixed to a vehicle roof  102 , and an active gear  49  having a plurality of teeth around its perimeter, the teeth of the gear rack  48  constantly meshed with the teeth of active gear  49 . Gear rack  48  and active gear  49  are pivotally attached to a mechanical control link  46  by fasteners  46   a  and  46   b  defining respective pivot points, so that the mechanical control link  46  holds the active gear and gear rack in constant contact by holding the respective pivot points at a fixed separation. The mechanical control link  46 , shown more particularly in  FIGS. 4 and 6 , is affixed to a door adaptor  103   a,  that is in turn affixed to a top of a vehicle door  105 ,  106 . 
         [0057]    Referring now to  FIG. 6 , a lever arm  50  having a first end  50   a  and a second end  50   b  is attached to the active gear  49  at a first end  50   a,  and at the second end  50   b,  the lever arm is attached to a first end  52   a  of a linear motor  60  at a point  50   c,  the motor having a telescoping arm  52   d  and a cover tube  52   c.  The motor housing is attached to a vehicle roof  102  by vehicle adaptor  108   b.  When the motor is activated in one direction, the telescoping arm  52   d  retracts into the cover tube  52   c,  causing the lever arm  50  to swing the vehicle front door  106  open ( FIG. 3 ). When the motor  60  is operated in the opposite direction, the motor forces the arm  52   d  to extend out of the cover tube  52   c,  causing the lever arm  50  to close the front door  106  ( FIG. 2 ). 
         [0058]    Referring now to  FIGS. 2 ,  3  and  4 , which show perspective views of the vehicle&#39;s front and rear doors in closed and opened positions, and  FIG. 6 , showing the front door opener  100   a  in detail (which detail is also representative of the rear door opener  100   b ) the invention according to some embodiments also includes a smart door software system, comprising logic hosted by a controller  56  ( FIG. 3 ), position sensors  54  ( FIGS. 4 and 5 ) and actuation sensors (not shown). The smart door software system senses the position of all the doors when the opener is in operation, and prevents opening a door in case of possible interference. This is necessary because exterior armoring (not shown) on the rear door  105  interferes with the path of opening for the front door  106  when the rear door  105  is opened prior to opening the front door  106 . An actuation sensor (not shown) mounted inside a door handle (not shown) on each interior door  105   a,    106   a  sends information to the controller  56  to signal the actuator  52  to operate. The logic in the controller  56  requires that the front door  106  must be completely open before rear door  105  can be opened through its entire range of motion. While the front door  106  is closed, the rear door  105  can be opened just far enough so that the front door  106  can open without interference. Once the front door  106  is opened past the point of interference, the rear door  105  can be opened further. 
         [0059]      FIGS. 2 and 5  illustrate the mechanical advantage obtained by the offset gear design of the door opener. The gear assembly offset mount effectively moves the center of rotation of the door from the vehicle door hinge  104  (shown in  FIG. 2 ) to the gear rack  48  (shown in detail in  FIG. 5 ). In one embodiment of the invention, the lever arm  50  is bent, as shown  FIGS. 1-6 , however a straight lever arm will also provide the additional leverage to the motor  60  so enough force is generated to open and close the heavy vehicle door. The gear rack  48  and the active gear  49  are constantly held in meshed position by the mechanical control link  46  ( FIGS. 4 ,  5  and  6 ), which prevents the meshed teeth from slipping due to vehicular or other movement. The gear rack and active gear are sized so as to shorten the mechanical link between the first end of the lever arm  50   a  and the pivot point of the gear rack  46   b,  this point  46   b  being directly above the vehicle door hinge  104 , thereby providing an increased mechanical advantage. The mechanical advantage is defined as the ratio of the difference of the distance between the attachment point  50   c  of the lever arm to the motor and the pivot point  46   a  to the difference of the distance from the pivot point  46   a  and a pitch diameter  50   d.  The pitch diameter  50   d  is defined as the center line at which the teeth of the active gear and the gear rack meet, where there is no sliding of the teeth against one another. 
         [0060]    As seen in  FIGS. 2-4 , the door opener according to some embodiments of the invention is designed to be mounted to the vehicle&#39;s roof  102  and the top of doors  105 ,  106  so that the opener parts neither protrude down into nor stick out over the door opening. Passengers entering and exiting the vehicle are not obstructed by the opener and do not need to stoop to avoid the opener parts. The original door opening profile is unchanged by the addition of the door opener. 
         [0061]    Some embodiments of the invention include a safety release mechanism  30  ( FIGS. 6 and 7 ) that is sandwiched between the motor first end  52   a  and the lever arm second end  50   b.  The mechanism  30  is screwably attached to the telescoping arm of the motor, and disengagably coupled to the lever arm second end by a heim joint  20 . When locked or engaged, the mechanism prevents the free rotation of the telescoping arm  52   d  by positioning a safety release lever  32  inside at least one notch  36  about the periphery of the mechanism&#39;s distal end  24   c.  To disengage the release mechanism, for instance in an emergency situation or when electrical power is lost, the door can be manually opened or closed by pulling the release lever  32  out its position nestled inside a notch  36 , allowing the telescoping arm  52   d  and the housing  24  to rotate freely in and out of the cover tube. The safety release lever  32  can be locked or opened from inside or outside the vehicle using a mechanical system, such as a manual release, comprising a cable pull system  34 , serving as an emergency backup to the electrical system. 
         [0062]    The safety release mechanism  30  as described is made by Ibis Tek, LLC (no part number available yet). The linear motor  60  with the telescoping arm as shown particularly in  FIG. 1  is available as a single unit from Motion Systems Corporation of Eatontown, N.J., part number 85261. 
         [0063]    Thus, the embodiment of the invention described herein provides an automatic door opener for opening a door by pulling on a lever arm attached to a linear motor (and for closing the door by pushing on the lever arm), and arranged to provide substantial mechanical advantage in turning a gear of a gear assembly disposed to open and close a door. The door gear assembly includes a mechanical control link that accommodates flexure of the body to which the door opener is attached. In some embodiments, the door opener includes a safety release mechanism of use in case of a linear motor using a ball screw as a basis for pushing or pulling on the lever arm. It should be noted that other embodiments of the door opener provided by the invention are not limited to linear motors, and a hydraulic motor could be used instead of a linear one. For a hydraulic motor, if a release mechanism is desired, a different release mechanism could be developed. 
         [0064]    It is to be understood that the arrangements shown and described above and in the attachments are only illustrative of the application of the principles of the present invention. Numerous modifications and alternative arrangements may be devised by those skilled in the art without departing from the scope of the present invention, and the appended claims are intended to cover such modifications and arrangements.

Summary:
A motorized door opener for a vehicle (such as a military or security vehicle), featuring a sensor system that determines door position to prevent door damage while the opener is in operation. The opener features an offset gear system that effectively changes the door&#39;s rotation point. Mechanical advantage is gained by using a lengthened lever arm with the gear system, providing increased leverage and allowing the motor to provide enough force to open and close a heavily armored door. The opener can use existing door hinges, and can be provided so as not to protrude into the door space, in order to facilitate passenger and equipment entry/exit through the doors. A safety release mechanism is included in some embodiments, allowing the door to be manually opened or closed.