Patent Publication Number: US-7708507-B2

Title: Locking mechanism for wheelchair in vehicle

Description:
RELATED APPLICATIONS 
   This application claims priority and herein incorporates by reference U.S. provisional patent application 60/738,289, filed Nov. 18, 2005. 

   BACKGROUND OF THE INVENTION 
   The danger of loose items moving or shifting around in a vehicle is apparent. The danger is even greater when transporting wheelchairs users. There are been many lock down mechanisms proposed. Over time, many of these mechanisms become inoperable or difficult to use due to metal fatigue. A phenomenon known as mushrooming can occur when metal is repeatedly compressed. 
   There remains a need for an easy to use, reliable and secure mechanism to safely transport wheelchairs in a vehicle. 
   SUMMARY OF THE INVENTION 
   A locking mechanism to secure a wheelchair while transporting in a vehicle comprises a base with a guide channel adapted to accept a catch pin and has been secured to a wheelchair. The catch pin is guided into the channel by an angled portion of the base. A locking mechanism cooperates with a pivot plate to secure the catch pin within the guide channel. A release mechanism allows disengagement. The guide channel includes a deformation groove that allows the mechanism to operate even when the metal has been deformed through repeated use. Lips are also provided at critical locations to allow free rotation of the parts even when the metal is deformed due to use. 
   Other features and advantages of the instant invention will become apparent from the following description of the invention which refers to the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective drawing of the mechanism in an open position according to an embodiment of the present invention. 
       FIG. 2  is another perspective drawing of the mechanism in a closed position according to an embodiment of the present invention. 
       FIG. 3  is yet another perspective drawing according to an embodiment of the present invention. 
       FIG. 4  is a perspective drawing showing the placement of a solenoid according to an embodiment of the present invention. 
       FIG. 5  is a close-up of the section shown in  FIG. 4 . 
       FIG. 6  is a perspective drawing showing the placement of switches according to an embodiment of the present invention. 
       FIG. 7  is a detailed drawing of the pivot plate according to an embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Reference is now made to the drawings in which reference numerals refer to like elements. 
   Referring now to  FIGS. 1 ,  2 ,  3 ,  5  and  7 , a locking mechanism for a wheelchair includes a base  100  may be attached to a vehicle (not shown) in order to secure a wheelchair. Base  100  may be bolted, welded, riveted or secured by other means known in the art. A front portion of base  100  is angled to ease guiding catch pin  120  into a channel guide. Although in the embodiment shown, two catch pins  120  are shown, other combinations such as using only one catch pin or three catch pins may be used. An advantage to multiple catch pins is resistance to rotation. Catch pin  120  may be mounted to an attachment plate  126  to facilitate mounting a wheelchair. As catch pin  120  makes contact with a trigger plate  106 , trigger plate  106  rotates around a stationary pin  116 , which is secured to base  100 . A stopper plate  118  also rotates around stationary pin  116 . A stopper plate pin  138  is located at the other end of stopper plate  118  and rotates with stopper plate  118 . A torsion spring,  108  provides biasing pressure between trigger plate  106  and stopper plate  118 . Torsion spring  108  fits around stationary pin  116 . 
   Trigger plate  106  has a trigger plate flange  136  that engages stopper plate  118  in one direction only. A locking plate  104  is pivotally connected to base  100  by a locking plate pin  128  which is secured to base  100 . One end of locking plate  104  has a locking plate latch  150 , which engages a pivot plate  102 . Locking plate latch  150  is biased against stopper plate  118  by a pivot plate extension spring  150 . Locking plate latch  150  includes a locking plate pin  140  mounted to its surface. Pivot plate extension spring  150  is attached between locking plate pin  140  and stopper plate pin  138  mounted thereon. Locking plate  104  has a locking plate notch  154  along its outer periphery that engages with a stopper plate pin  138  locking plate  104  in an open condition. In this condition, the wheelchair may be removed. As catch pin  120  makes contact with trigger plate  106 , stopper plate pin  138  moves out of position from locking plate notch  154  to move back into a locked condition. As catch pin  120  moves along the channel guide, it encounters pivot plate  102  which includes a semicircular slotted opening that engages with catch pin  120 . As pivot plate  102  rotates around catch pin  120 , locking plate  104  moves into position securing catch pin  120  within pivot plate  102  and locking plate latch  150  prevents further movement. 
   Pivot plate  102  is biased using a pivot plate extension spring  150  which is connected to a pivot plate pin  146  mounted on the surface of pivot plate  102  and a stationary pin  148  mounted to base  100  and rotates about a pivot plate pin  122  fixed to base  100 . Although the embodiment shown include pivot plate  106 , it is possible to eliminate pivot plate  106  by using an elongated stopper plate  118 . Additionally, pivot plate  102  is not essential to the present invention. Locking plate  104  is capable of securely holding catch pin  120  by itself. 
   Locking plate  104  is released from the locked position by applying a force to the release end of locking plate  104  causing locking plate latch  152  to move out of the locked position. Locking plate  104  is biased by locking plate extension spring  110 , which is attached to a release lever pin mounted on the surface of locking plate  104  and to a stationary pin connected to base  100 . 
   In use when catch pin  120  slams against the end of the channel guide, it can deform the metal causing it to mushroom and interfering with the rotation of locking plate  104 . In order to overcome this problem a deformation groove  124  is provided so that locking plate  104  is rotating on a different plane than the metal at the end of deformation groove  124 . Additionally, the metal can deform around when stopper plate pin  138  engages with locking plate notch  154 . To provide for proper function even if this happens, a locking plate latch lip  162  is provided to allow stopping plate  118  to rotate even if metal deformation happens. Likewise, metal deformation can also occur around the interior portion of pivot plate  102  when catch pin  120  engages. A pivot plate lip  164  is provided to overcome this. 
   Referring now to  FIGS. 4 and 6 , a solenoid  122  is provided to provide electronic operation of the present invention. Solenoid  122  is mounted between a stationary pin  152  attached to base  100  and release lever pin  142  attached to the release lever end of locking plate  104 . Solenoid  132  may be operated by a wired switch or a remote control as is known in the art. Additionally, a switch  156  may be mounted to provide remote status of the position of locking plate  104  further enhancing safety. A switch trigger may be mounted on pivot plate  102  to engage switch  156  when catch pin  120  is securely in place. 
   Although in the embodiments shown, a stopper plate pin  138  is used to engage with locking plate notch  154 , any suitable engagement arrangement would work such as an enlarged portion of stopper plate  118 . The only requirement being that the engagement portion should be able to be selectively positioned within locking plate notch  154 . 
   Although the instant invention has been described in relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art.