Abstract:
A mechanism including a ratchet member mounted for movement in two opposite directions and a second member mounted adjacent the ratchet member, the second member responsive to predetermined pressure to engage the ratchet member to constrain movement thereof in one of the two opposite directions.

Description:
[0001]     This invention relates to a ratchet mechanism. 
     
    
       [0002]      FIG. 1  is an exploded view of a ratchet mechanism according to an embodiment of the present invention;  
         [0003]      FIG. 2  is a top view of various components of the embodiment shown in  FIG. 1 ;  
         [0004]      FIGS. 3 and 4  are top views of portions of the embodiment shown in  FIGS. 1 and 2 , illustrating features of operation thereof;  
         [0005]      FIG. 5  is a top view of the assembled embodiment shown in  FIG. 1 ;  
         [0006]      FIG. 6  is a perspective view of an orthopedic back brace with which the embodiment of  FIGS. 1 through 5  may be used;  
         [0007]      FIG. 7  illustrates an operating position of the back brace shown in  FIG. 6 ; and  
         [0008]      FIG. 8  illustrates a different operating position of the back brace of  FIGS. 6 and 7  useful in conjunction with the description of the embodiment of  FIGS. 1 through 5 . 
     
    
     DETAILED DESCRIPTION  
       [0009]     Reference now should be made to the drawings, in which the same reference numbers are used throughout the different figures to designate the same or similar components.  FIG. 1  is an exploded view of a pressure activated ratchet mechanism which may be incorporated into a variety of different products to provide a useful motion restriction mechanism. Some examples of uses which may incorporate the embodiment shown in  FIGS. 1 through 5  are spinal hypertension braces, ratcheting joints in cervical braces, lounge and pool chairs which require various relative positions between the seat and the back, ratcheting joints in knee braces and prostheses, winches, such as used in boat launch mechanisms, ratcheting joints in ankle-foot braces and prostheses, ratcheting joints in upper extremity braces and prostheses, camping gear, and other mechanisms which require positioning and secure fastening.  
         [0010]      FIG. 1  is an exploded view of an embodiment of the invention; and  FIG. 2  is a top view of various ones of the parts shown in  FIG. 1 . The pressure activated ratchet mechanism illustrated in  FIGS. 1 and 2 , and the operation of which is shown in  FIGS. 3 through 5 , includes a pair of parts arranged for relative rotational movement with respect to one another. One of these parts is shown as an elongated lever  12 ; and the other is shown as a base member  20 . These parts, while illustrated in a generally diagrammatic form in the various figures of the drawings, may be incorporated into a variety of different mechanisms. For example, the lever  12  could be a portion of the seat back of a lounge chair or pool chair, while the base member  20  could be an extension of the frame on which the seat back of such a chair is located. Alternatively, the lever  12  could be apportion of a ratcheting joint in a cervical brace, and the base member  20  another portion of the ratcheting joint of such a brace. The operation, however, is the same, whether the parts  12  and  20  are separate parts of a rotatable ratchet joint for attachment to some other component or are integral parts of such a component.  
         [0011]     As illustrated in the various  FIGS. 1 through 5  of the drawing, the right-hand end (as viewed in  FIG. 1 ) of the lever  12  terminates in a portion  14  having a circular end with ratchet teeth  16  formed about the circumference. The ratchet teeth  16  face generally toward the right (as viewed in  FIGS. 1 and 2 ) in the manner of conventional ratchet mechanisms arranged in a circular configuration. A hole  18  is formed concentrically with the circular end on which the ratchet teeth  16  are mounted; and this hole is designed to slip over a pivot post  22 , which extends upwardly from the base member  20 , as shown in  FIG. 1 .  
         [0012]     A pawl member  30  in the general configuration of an L-shaped lever or a V-shaped lever, has a hole  32  through it at the bight of two arms  34  and  38  which form the pawl member  30 ; and the hole  32  is dimensioned to fit pivotally over an upwardly extending pivot post  24  on the base  20 . As is readily apparent from an examination of all of  FIGS. 1, 2 ,  3  and  4 , the pivot posts  22  and  24  are spaced apart from one another to permit engagement and disengagement of the pawl  30  and the ratchet teeth  16  by relative rotation of the pawl lever  30  with respect to the lower end  14  of the lever  12 .  
         [0013]     In the assembly of the pressure activated ratchet mechanism shown in  FIG. 1 , the hole  18  through the lever arm  12  is slipped over the pivot post  22 ; and the hole  32  through the pawl lever  30  is slipped over the pivot post  24 . A retainer  44 , having corresponding holes  46  and  48  in it, then is placed over the top of the end  14  and over the pawl lever  30  to hold them in place. A leaf spring  54 , in the form of a generally elongated rectangle  58 , with an upward extension  56 , is mounted with the extension  56  extending through a corresponding slot  50  in the retainer  44 . Since the slot  50  is of rectangular configuration, the extension  56  is captivated in the position shown in  FIGS. 3 and 4 , which is the rest position of the spring  54 . After the spring  54  is in place and the retainer  44  has been placed over the pivot posts  22  and  24 , a pair of washers  60  and  62  are placed in recesses in the top of the retainer  44 ; and threaded fasteners, shown in the form of screws  70  and  72 , are threaded into internally threaded openings in the pivot posts  22  and  24  to secure the assembly together, as shown in  FIG. 5 .  
         [0014]     In the relaxed position of the spring  56 / 58 , the upper or rightward end (as shown in  FIG. 3 ) of the spring  58  rests against the arm  34  of the pawl  30  to bias the arm  38 , which has pawl teeth  40  on its extremity, out of engagement with the teeth  16 , on the end  14  of the ratchet lever  12 . This allows the ratchet lever  12  to rotate freely in either direction, as indicated by the arrow across the lever  12 , as shown in  FIG. 3 . This is considered the release or rest position of the pawl and ratchet mechanism.  
         [0015]     As shown in  FIG. 4 , when the lever arm  34  of the rotatable pawl  30  is pulled by a suitable force or pressure (source of which is not shown), to the right and slightly downwardly in a clockwise direction, the pawl  30  rotates clockwise about the pivot post  24  to cause the pawl teeth  40  to engage the ratchet teeth  16  on the end  14  of the ratchet lever  12 . As is apparent from an examination of  FIGS. 2 and 3  particularly, the direction or orientation of the teeth  16  and  40  is such that the ratchet lever  12  is permitted to rotate in the direction of the arrow shown in  FIG. 4  (clockwise, as shown in  FIG. 4 ), but is prevented from opposite (counterclockwise) rotation because of the manner in which the teeth  40  on the lever arm  38  and the teeth  16  on the end  14  of the ratchet are oriented. As the force or pressure applied to the end of the arm  34  is increased to increase the clockwise rotational force (as shown in  FIG. 4 ) of the teeth  40  on the pawl  30  into engagement with the teeth  16  on the end of the ratchet lever  12 , the holding force preventing rotation of the arm  12  in a reverse or counterclockwise direction, is increased. As soon as the pulling force or pressure indicated by the arrow adjacent the end of the lever arm  34 , however, is released, the mechanism reverts back to the configuration shown in  FIG. 3  under the force of the spring  54 . This allows full free rotation in either direction of the lever  12  relative to the base member  20 .  
         [0016]     It should be noted that while a leaf spring  54 , comprising the elements  56  and  58 , is indicated for applying the return or disengaging force to the pawl  30 , other types of springs, such as coil springs (operated either in compression or extension), or a spiral spring around the pivot  24  may be used equally as well, and effectively as the leaf spring  54  which is illustrated in the drawings. Also, for some applications, the return force to the relative positions shown in  FIG. 3  can be applied magnetically or by gravity. The principle of operation is the same. The spring force which is applied to return the parts of the mechanism to the relative positions shown in  FIG. 3  is the force which initially needs to be overcome by application of a pulling force or pressure on the end of the lever arm  34 , as shown in  FIG. 4 . Once that force, however, is overcome, additional pressure applied to tend to rotate the pawl  30  in a clockwise direction (as shown in  FIGS. 3 through 5 ) serves to more tightly engage the teeth  40  with the teeth  16  to prevent reverse relative rotation of the parts  12  and  20 , as described previously.  
         [0017]      FIG. 6  illustrates a typical configuration of a cervical brace comprising upper and lower parts, which are hinged together substantially at the mid point. The upper part comprises a generally U-shaped rigid member  82  having a front portion with a pad  88  on its reverse side, designed to rest against the upper chest of a user, as illustrated most clearly in  FIG. 8 . The arms  82  then extend along the side of the wearer, and terminate in downwardly extending portions  84  and  86 . Pads  90  and  92  typically are located on the inside of the brace to prevent abrasions, and to increase comfort. The lower terminus of the arms  84  and  86  is hingedly connected through a pressure activated ratchet mechanism of the type shown in  FIGS. 1 through 5  to the upper ends of a pair of arms  102  and  112 , each of which are formed as extensions of lower members  100  and  110 . The lower ends of the members  100  and  110  extend forwardly and downwardly to terminate in arm portions  104  and  114  attached to a lower rigid pressure member  120 , which also carries a pad on the side facing the wearer.  
         [0018]     The back side of the cervical brace has a flexible belt or strap  130  on it, with opposite ends  132  attached to the lever arm  34  of the pressure activated ratchet mechanism shown in  FIGS. 1 through 5 . This attachment is effected in any suitable manner, including, but not limited to, a pin (not shown) extending from the end  132  through the hole  36  in the arm  34  of the pawl  30 . The strap  130  carries a pad  136  approximately at its center point for resting against the back of the wearer, again, to provide comfort.  
         [0019]     Typically, the wearer of the device rotates the parts  82  and  100  in a forward position, as shown in  FIG. 7 , in order to apply the device. Since this is a cervical brace, the wearer generally is bent over in a forward position; and the brace is intended to assist the wearer in maintaining his or her back in a generally upright position. When the device is in the relative position shown in  FIG. 7 , the pawl and ratchet mechanisms which are included at the pivots on the ends  132  of the strap  130  are in the released configuration shown in  FIG. 3 . Thus, it is relatively easy for the wearer to place the device about the lower abdomen, as indicated in  FIG. 7 , with the upper portion  93  in a forward direction.  
         [0020]     The strap  130  across the back then is fastened together to apply pressure to the arm  34  of the pawl  30 . This pulls the plate  120  against the pelvic region of the wearer; and the pressure force applied through the end  132  to the lever  34 , pivots the pawl  30  in the direction shown in  FIG. 4  to engage the teeth  40  and  16  of the pawl and ratchet mechanism, as shown in  FIG. 4 . This allows rotation of the member  82  in its clockwise direction (as shown in  FIG. 7  and as illustrated in  FIG. 4 ). It should be noted that the lever  12  of  FIG. 4  may be either incorporated integrally into the lower end  84  of the upper portion of the cervical brace; or it may be separately attached to the upper portion  84  of the cervical brace. Similarly, the base member  20 , which is illustrated in  FIGS. 1 through 5 , may be an integral part of the arms  102  and  112  of the cervical brace; or a base member  20  of the type shown in  FIGS. 1 through 5 , alternatively may be separately attached to the arms  102  and  112 . Irrespective of whether the ratchet mechanism is integrally formed as a part of the brace or is separately constructed and subsequently attached to the brace, the operation is the same.  
         [0021]     Once the ends  132  are secured to the lever arms  34  of the pawl mechanism  30  on each side of the brace  80 , rotation either in a step-by-step fashion, or directly to a pre-established position, with the assistance of a therapist or under control of the wearer himself or herself, allows the brace to apply pressure on the upper chest and the pelvic plate  120  to assist the wearer in attaining an upright position, as shown in  FIG. 8 . The amount of rotation depends upon the nature of the therapy and support which is desired. In any event, reverse rotation (in the counterclockwise direction, as shown in  FIG. 7 ) is prevented so long as pressure is applied to hold the teeth  40  of the pawl  30  into engagement with the teeth  16  on the ratchet member  12 . It also should be noted that, initially, a relatively lower amount of pressure is applied when the device is first being moved from the position shown in  FIG. 7  to the position shown in  FIG. 8 . Any attempt, however, whether voluntarily or involuntarily, made by the wearer to bend forward meets with greater resistance, at increased pressure, to hold the teeth  40  and  16  into ever tighter engagement as the pressure is increased. Thus, the safety factor of the pawl mechanism increases as pressure increases.  
         [0022]     Whenever removal of the cervical brace of  FIGS. 6,7  and  8  is desired, all that is necessary is to release the strap  130  (by any suitable means provided to do this); and immediately the spring  56 / 58  returns the pawl  30  to the position shown in  FIG. 3  by rotating it in an counterclockwise direction (as viewed in  FIGS. 3 and 4 ). This allows the wearer to bend forward or just simply drop the support on the upper portion of the chest to the position shown in  FIG. 7  for removal of the cervical brace.  
         [0023]     Although the embodiment shown in FIGS.  6  to  8  specifically has been illustrated in conjunction with a cervical brace, the mechanism employed is suited for use in all of the various pawl and ratchet situations which previously have been described, and others which particularly will benefit from a pressure activated pawl mechanism. As mentioned above, the pressure activated mechanism increases in its safety (against reverse rotation or movement) as the pressure on the arm  34  is increased. It also should be noted that the principles which have been disclosed in conjunction with the embodiment shown may be applied to pressure activated linear pawl and ratchet operations as well. A rotary configuration is particularly suitable for pivoted joints; but situations exist which utilize a linear pawl and ratchet for lifting items from one position to another. The principles of operation are the same.  
         [0024]     It also should be noted that while pivot posts  22  and  24  are shown affixed to the base member  20  provide the pivoting operation, a comparable operation also may be achieved by providing holes or recesses in the locations of one or both of the posts  22  and  24  on the member  20 , with affixed mating pivot posts or pins at the locations of the holes  18  and  32  on the ratchet and the pawl  30 , respectively, to achieve the same operating results.  
         [0025]     The various parts also may be made of different materials, depending upon the particular application which is to be made of the pawl and ratchet mechanism. In many cases, the parts will be made of steel or aluminum, while for some applications, plastic or other materials capable of applying the desired amount of force for the particular application may be employed.  
         [0026]     Various other changes and modifications will occur to those skilled in the art for performing substantially the same function, in substantially the same way, to achieve substantially the same result without departing from the true scope of the invention as defined in the appended claims.