Abstract:
A semi automatic brake applicator for wheel chairs which have at least one arm with an actuator lever pivotally attached to the arm, an actuator rod pivotally attached to the actuator lever at the first of two ends and to a clamp at the second end, the clamp being attached to the brake actuator lever of the wheel chair brake system. In operation, the actuator lever is rotationally pivoted which causes the actuator rod to move linearly which, in turn, causes the clamp to rotate the brake actuation handle thereby bringing the brake shoe into contact with the drive wheel thus setting the brake. Reverse motion of the actuator lever causes the brake to release.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a continuation-in-part of U.S. patent application Ser. No. 09/427,365 filed Oct. 26, 1999, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     It has long been recognized that an occupant of a wheel chair can be injured, potentially severely, if the chair is not braked against unwanted motion prior to the applicant attempting to rise out of the chair. This danger occurs because many wheel chair users lack the strength or agility to move from a sitting to a standing position or from a standing position to a sitting position without applying downward pressure on the arms of the wheel chair to assist themselves. Although wheel chairs are equipped with braking mechanisms, these mechanisms are purely manual in operation. That is, the brake must be set by an affirmative motion of either the wheel chair user or the user&#39;s helper. 
     If the brake is not set, at a certain point in the movement from a sitting to a standing position, or from a standing to a sitting position, accompanied by downward force on the arms of the wheel chair, the force applied to the arms of the chair by the user is actually angled toward the back of the wheel chair instead of down towards the surface on which the wheel chair rests. This backward force causes the wheel chair to roll back away from the user, often before the user has gained his balance, causing the user to fall to the ground, frequently injuring the hips, coccyx, or the like. 
     The purpose of this invention is to provide a means to apply the brake in a semi automatic fashion as soon as the occupant attempts to rise from the chair to prevent such catastrophes as described above. 
     SUMMARY OF THE INVENTION 
     There have been many attempts to provide automatic or semi-automatic brake applicators for wheel chairs for many of the reasons set forth herein. Most of the prior art devices involve the use of springs which must be matched to the size and weight of the user to function properly or levers which not only must be tuned to the size and weight of the user, but also expose the user and the user&#39;s helper to numerous pinch points which can trap hands and fingers causing serious injury or clothing or blankets thus inhibiting the intended mode of operation of such devices. 
     For example, in U.S. Pat. No. 5,203,433 to Dugas, the wheel chair brake is actuated when the user rises from the seat. The seat is equipped with a spring to bias it in an upper position in which the brake is applied. The force of the spring is overcome by the weight of the user sitting in the chair thereby causing the brake to be released. Use of this device requires that the springs in the seat not be so powerful that a person who is light in weight cannot overcome its force, yet, at the same time be powerful enough to engage the brake when actuated. 
     U.S. Pat. No. 5,894,912 to Dobben also provides an automatic means to engage a braking device when the wheelchair is unoccupied. In the Dobben device, the brake is released when weight is placed upon sensing levers which run under the legs of the user, or alternatively, when brake actuation handles which are attached to the push handles of the wheel chair are squeezed. Again, in order for the device to function based upon the user&#39;s rising from the chair, the device must be tuned to the weight of the user. If clothing such is a blanket or quilt is trapped in the device, it may not release the brake upon occupancy of the chair by the user, or, alternatively, fail to set the brake as the user attempts to rise from the chair. 
     U.S. Pat. No. 4,350,227 to Knoche provides a spring loaded arm rest biased in a upper position connected to a rod which is in turn connected to a brake actuation lever. The upward biased arm rest is held in a lower position by the weight of the arm of the user. When the user&#39;s arm is lifted from the armrest, the spring loading moves the armrest to the upper position causing the rod to also move upward which in turn causes the brake to be engaged. Obviously, as will be seen, this design offers many drawbacks when compared to the present invention. The Knoche device, first of all, requires that springs of sufficient tension be selected to allow the weight of the arm of the user to depress the arm rest into the lower position while, at the same time, when the arm rest is unloaded, the spring must be strong enough to cause the brake to engage. Additionally, the arms of the user must remain on the armrest at all times, otherwise the brakes will be engaged by the upward motion of the rod in response to the armrest being raised to the upper position as a result of the lack of a depressing weight on the arm rest. 
    
    
     DESCRIPTION OF THE FIGURES 
     FIG. 1 is a plan view of one embodiment of the invention in the brake deactivated position. 
     FIG. 2 is a plan view of the pivot clamp 
     FIG. 3 is a plan view the operator clamp. 
     FIG. 4 is a sectional view of the operator clamp showing placement of pivot holes therethrough. 
     FIG. 5 is a plan view of the embodiment of the invention depicted in FIG. 1 with the brake in the actuated position. 
     FIG. 6 is a perspective view of the actuator rod, operating means and brake activation lever. 
     FIG. 7 is a perspective view of the actuator rod, operating means and brake activation lever showing the linear and arcuate motion of the components in response to depression of the actuator lever. 
     FIG. 8 is a plan view of a first alternative embodiment of the instant invention. 
     FIG. 9 is a perspective view, partially exploded, of the actuator lever for the first alternative embodiment of the invention. 
     FIG. 10 is a perspective view of the actuator rod, lower clamp and brake actuation lever in the alternative embodiment of the invention. 
     FIG. 11 depicts the relative linear and arcuate motion of the actuator rod, lower clamp and brake actuation system responsive to depression of the actuator lever. 
     FIG. 12 is a plan view of a second alternative embodiment of the invention. 
     FIG. 13 is a perspective view of an actuator lever for the second alternative embodiment of the invention, partially exploded. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Wheelchairs commonly in use have handle -actuated manually applied brakes, one for each large drive wheel, which, when the handle is rotated, causes a brake shoe to come into frictional contact with the large drive wheel. There are generally two types of handle actuated manually applied brakes in use: One type, such as that shown in FIG. 1, has the actuating handle in a substantially vertical position relative to the floor or ground upon which the wheelchair rests when the brake is released. The actuating handle is rotated to a substantially horizontal position relative to the floor or ground on which the wheelchair rests when the brake is applied. 
     The second type of handle actuated manually applied brakes in use is generally in a substantially horizontal position, as shown in FIG. 2, relative to the floor or ground upon which the wheelchair rests when the brake is not applied and rotatable to an essentially vertical position relative to the floor or ground upon which the wheelchair rests when the brake is actuated. 
     FIG. 1 shows a wheelchair  1  in phantom of a type well known in the art, having at least one tubular metallic arm  2  with padded arm rest  3  positioned essentially parallel to the surface on which the wheel chair rests. An actuator lever  10  is pivotally attached to the tubular metallic arm  2  using a pipe clamp of a kind well known in the art, not shown. For purposes of clarity, only one side of the wheel chair and the invention is shown. In practice. however, it is contemplated the wheelchair will have two arms and that a mirror image of the invention as shown is in place on the other arm of the wheel chair. 
     The actuator lever  10  comprises, in side view, an essentially rectangular shape having a front edge and a rear edge, a top edge and a bottom edge. The pivotal attachment point  12  of the actuator lever  10  to the clamp on the tubular metal arm  2  is located near the intersection of the bottom edge and the rear edge of the actuator lever  10 . The actuator lever is attached to the pipe clamp using a pivot pin of suitable size, or any other attachment means suitable to the task. 
     An actuator rod  15  having a first, threaded, upper end and a second, threaded, lower end has threaded onto each of said ends thereof a clamp  17 ,  17   a  as hereinafter described. Clamp  17 ,  17   a  has a forked end with spaced apart furcations  175 ,  176  and a pivot pin  177  mountable between the furcations, and includes threaded means  178  for receiving the actuator rod  15 . Actuator rod  15  is threadedly attached at its upper end by means of upper clamp  17  to pivot point  18  on actuator lever  10  near the intersection of the forward and bottom edges by means of a pivot pin  177  located between the furcations. The pivot pin is secured to clamp  17 ,  17   a  by a threaded nut or other suitable means. The actuator rod  15  reciprocates in response to the pivotal motion of the actuator lever  10 . The lower end of actuator rod  15  is threadedly inserted into lower clamp  17   a.    
     Operator means  20 , shown in FIG. 3 has a body having a first end and a second end, said body being formed into a hook proximal to one end of the operator means. The hook has a first arm  22  and a second arm  24 , said first and second arms being continuously formed from the same piece of material so that a bridge  26  exists between them. The first arm  22  is shorter in length than the second arm  24 . As shown in FIG. 4, which is a cross section of FIG. 3, holes are drilled through the first arm  22  and the second arm  24 . Short arm  22  has a hole proximal  26  to its end, and long arm  24  has two holes: one proximal to the bridge  26  and opposite the hole  26  in the short arm  22  so that hinge pin  28  can simultaneously pass through the hole in the short arm  22  and the hole proximal to the bridge in the long arm  24 . The second hole, not shown in FIG. 3, but obvious from FIG. 4 in long arm  24  is proximal to the end of the long arm farthest from the bridge. 
     Referring now to FIG. 5, operator means  20  is attached in pivotal relationship within the furcations  175 ,  176  of lower clamp  17   a  and clamp  17   a  is threadedly attached to actuator rod  15 . Positioned within the hook portion of operator means  20  and fixedly secured therein by securing means which passes through the mated holes in the short arm  22  and the long arm  24 , not shown, is the brake actuation lever B. 
     As shown by comparing FIG. 1, in which the wheel chair brake is released with FIG. 5 in which the wheel chair brake is engaged, the operation of the invention becomes clear. In the brake released position, actuator lever  10  is maintained in an upwardly angled position relative to wheel chair arm  2 . In this position brake lever B is in an essentially vertical position relative to the floor or ground under the wheel chair. When the user attempts to rise from the wheel chair, it is a natural motion for the user to place his or her hands on the forward end of the arm of the wheel chair. With the actuator lever  10  positioned so that it protrudes beyond the end of the wheelchair arm as shown in FIG. 1, the natural tendency is for the user to place his or her hands on the lever to push himself or herself into a standing position. This downward force occasioned by the efforts of the user to rise causes the pivotally mounted actuator lever to move in a downward arc from the first upwardly angled position to a second, essentially horizontal position. The downward force of the moving actuator lever  10  is translated into a downward force along the long axis of actuator rod  15 . In turn, the downward force along actuator rod  15  is translated into an essentially forward motion of operator means  20  thereby moving brake actuator lever B from its initial vertical position towards a forward and horizontal position causing movement of the brake shoe into frictional contact with the large drive wheel on the wheel chair. FIGS. 6 and 7 respectively illustrate the reciprocal motion of actuator rod  15  and the arcuate motion of actuator  20  which cause an arcuate motion of brake actuator lever B as the brake is engaged and disengaged. Prior to placing the wheelchair with the semi automatic braking means described herein into service, the effective length of actuator rod  15  is adjusted by screwing more or less of actuator rod  15  into clamps  17  and  17   a  so that when the actuator lever is fully depressed, the possibility of over rotation of the brake actuator lever is eliminated. 
     Referring now to FIG. 8, a first alternative embodiment of the invention is shown. In a small number of styles of wheel chairs, the wheel chair brake is actuated by moving brake activator lever B from an essentially horizontal position to an essentially vertical position. In actuality, this arrangement is less than desirable than that showed in the first embodiment described above because if excessive upward force is applied to the brake handle B, it is possible over rotate brake handle B and move the handle into past the vertical axis, thereby disengaging the brake. 
     In this first alternative embodiment, brake actuator lever  50  has an essentially rectangular face  52  with a front edge and a back edge. A pivot hole  54 , drilled approximately in the center of said face, and an actuator rod pivot hole  56  near the back edge of said face. 
     Using clamping means attached to the arm  2  of the wheel chair, brake actuator lever  50  is pivotally attached to said clamp using a pivot pin of suitable design. Clamp  17  is attached to the actuator rod pivot hole  56  by means of a pivot pin which is guided through holes, not shown in the furcations  175 ,  176  in the forked end of the clamp. Threadingly engaged with the clamp  17  is upper end of the brake actuator rod  15 . The lower end of brake actuator rod  15  is threadingly engaged to clamp  17   a  of the same general type as clamp  17 . Brake actuator lever B is positioned between the furcations of clamp  17   a  and is pivotally attached to brake actuator lever B by a pivot pin  58  which passes through the furcations and through a hole provided in the brake actuator lever B as aforesaid. 
     Turning now to FIG. 9, a perspective view of brake actuator lever  50 , with the soft protective pad  58  removed, an important feature of this embodiment is disclosed. Because of the possibility of over rotating the brake actuator lever B as described above, brake actuator  50  has arresting tab  59  protruding in an essentially perpendicular relationship to rectangular face  52  and, since it is intended that the brake actuator lever  50  be mounted on the outside of arm  2 , relative to the seat so that arresting tab  59  points towards the inside or chair portion of the wheel chair. The pivotal motion of brake actuator lever  50  in a downward motion at its front edge causes arresting tab  59  to rotate upward until it comes in contact with wheel chair arm  2  thereby prohibiting further motion of the actuator lever and preventing brake actuator lever B from over rotating. 
     Turning now to FIG. 10, the connection of clamp  17   a  is depicted. Comparison of FIG. 10 with FIG. 11 illustrates the relative motion of the actuator rod  15  and clamp  17   a  with the brake actuator lever B to show how the brake shoe is brought into contact with the drive wheel. 
     FIG. 12 depicts a second alternative embodiment of the invention. In FIG. 12, a model of wheel chair commonly described as a“desk” or“table” chair is shown. In a desk or table chair, the arms  2  are removable from the frame of the chair, thereby allowing the occupant to move the chair into a knee hole of a desk or under a counter or table top allowing the occupant to sits squarely and straight in the seat, as opposed to having to slide forward towards the front end of the seat or having to lean forward to reach the desk top or table top. In this alternative embodiment, a removable pin  28   a  is substituted for the pivot pin which is inserted into pivot hole  28 . 
     The structure of removable pin  28   a  is well known in the art and comprises an essentially hollow pin which has within it several ball bearings which protrude from the conically shaped surface of the pin. The ball bearings are spring loaded and biased outwardly from the surface of the pin. When the pin is inserted into the pivot hole and clamp, the ball bearings retract into the body of the pin allowing the pin to pass through the metal boundaries of the various channels. The bearings then extend when the metal of the actuator lever and clamp have been cleared, thereby retaining the pin removably in place. It is understood that there are several types of securable pins commonly available, and this description is not intended to limit the invention to the ball-bearing type of pin described here. Thus, when the occupant of a desk or table chair wishes to remove the arms so as to move into the knee hole of a desk or under a table top, all he or she must do is pull the pivot pins  28   a  from the actuator lever, as shown in FIG.  13 . The actuator assembly will fall forward, as shown in FIG. 12, then the arms  2  are free to be removed in the usual manner. The process would then be reversed to reinstall the arms and the brake actuator mechanism. Of course, it is understood that pin  28   a  could be used in any of the embodiments shown herein, but that it only has utility when employed with a desk or table type wheel chair. 
     Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, and representative devices and methodologies shown are described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.