Abstract:
A strap-tensioning device includes a base that receives a rotatable drum rigidly connected to toothed wheels, and configured to engage a holding pawl; tensioning lever rotatably mounted by hinging onto the drum, and provided with a pawl for driving the toothed wheels; an unlocking pawl configured to release the toothed wheels from the respective engagement thereof with the holding pawl and with the driving pawl, rotatably mounted, independently of the rotation of the tensioning lever, by hinging onto the drum. The unlocking lever is rigidly connected to two parallel cams having the same profile, and configured to simultaneously engage, respectively, the holding pawl and the driving pawl, so as to release the rotation of the drum.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a National Stage Application of PCT International Application No. PCT/FR2010/051534 (filed on Jul. 21, 2010), under 35 U.S.C. §371, which claims priority to French Patent Application No. 0958340 (filed on Nov. 25, 2009), which are each hereby incorporated by reference in their respective entireties. 
     FIELD OF THE INVENTION 
     The present invention relates to a belt- or strap-tensioning device, better known as a “ratchet.” 
     Such a device is conventionally employed to tension straps, particularly on motor vehicle roof racks, luggage racks and in general terms, whenever it is required to tension a strap for the purpose of securing an item, a piece of luggage, or any kind of product. 
     BACKGROUND OF THE INVENTION 
     “Ratchet” systems are now in widespread use for tensioning straps. In the main, they traditionally comprise a base rigidly connected to the end of a strap, the base comprising an axis on which is mounted a rotatable drum around which the other end of the strap, or even another strap, is intended to be wound. This drum is rotated by means of a lever, known as a tensioning lever, that actuates the rotation of the drum in order to allow the other end of the strap to be wound thereupon, thereby tensioning the strap. The axis of the drum is provided with toothed wheels intended to engage with holding pawls mounted on the base, and driving pawls mounted on the tensioning lever, in order respectively to keep the strap tensioned and to drive the drum when the tensioning lever is actuated. 
     One of the major difficulties with this kind of device lies in releasing the tension, when it is required to release the secured product. Indeed, to effect the release of the rotation of the drum, prior art devices are basically provided with an unlocking lever rigidly connected to the tensioning lever, which needs to be pulled first, in order to release the drum from the driving pawl. Consequently, it is also necessary to fully open the tensioning lever, in other words, move it away from the base to its extreme position, in order to release the drum from the holding pawl. This last stage is not that simple, and short of finding the knack, few users are able to correctly release the drum. This dual operation thus causes a problem precisely because of the tension being exerted on the drum when the strap is stretched. 
     The targeted objective of this invention is to simplify this unlocking operation. 
     SUMMARY OF THE INVENTION 
     To this end, the invention relates to a strap-tensioning device that includes: a base, to one of the ends of which is rigidly connected the end of a strap, and receiving at its other end, a rotatable drum receiving the end of the strap or of another strap, the drum being rigidly connected to two toothed wheels, capable of engaging with a holding pawl meshing by default in the toothed wheels under the action of a resilient return means, and able to slide in the base; a tensioning lever that is rotatably mounted by hinging onto the drum, and provided with a pawl for driving the toothed wheels, meshing by default in the toothed wheels under the action of a resilient return component, able to slide in the lever; and an unlocking lever, capable of releasing the toothed wheels from the respective engagement thereof with the holding pawl and with the driving pawl. 
     In accordance with the invention, the unlocking lever is rotatably mounted, independently of the rotation of the tensioning lever, by hinging onto the drum. 
     Additionally, the unlocking lever is rigidly connected to two parallel cams having the same profile and able to simultaneously engage with the holding pawl and with the driving pawl respectively so as to release the rotation of the drum. 
     In other words, the invention mainly comprises disassociating the tension and tension release functions, something that was not offered by prior art devices. Indeed, by disassociating these two functions, the tension release operation is made easier by a straightforward rotary movement exerted on an unlocking lever, independently of any action on the tensioning lever. 
     Because of the presence of cams, the profile of which is adapted, the engagement of the holding and driving pawls is released straightforwardly and without effort, thereby releasing the rotation of the drum and, consequently, enabling the tensioned strap to relax. 
     In accordance with one advantageous feature of the invention, the end of the strap secured to the base is mounted on an axis for winding and storing the strap, which is rotated by means of a crank. Thus, when so required, it becomes possible to store a considerable length of strap, and typically as much as five metres, since it is not stored on the tensioning axis, but on an independent axis. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The manner in which the invention may be implemented, and the resulting advantages, will become clearer from the following embodiment example, given for information purposes and non-restrictively, supported by the appended drawings. 
         FIG. 1  is a diagrammatic perspective view of the tensioning device in accordance with the invention, in the closed position. 
         FIG. 2  is a view similar to  FIG. 1  wherein the unlocking lever is in the operational unlocking position. 
         FIG. 3  is a diagrammatic perspective view showing in detail the cams associated with the unlocking lever. 
         FIG. 4  is a view similar to  FIG. 1  in another embodiment of the invention, in the closed position. 
         FIG. 5  is a view of the device of  FIG. 4 , in the tension position. 
         FIGS. 6 and 7  are respective views showing the storage of a strap in the device of  FIG. 4  in accordance with the invention. 
         FIG. 8  is an exploded view of the device of  FIGS. 4-7  in accordance with the invention. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     A perspective diagrammatic view of the inventive tensioning device has thus been shown in  FIG. 1 . Basically, it comprises a base  1 , one of the ends of which is rigidly connected to the end of a strap  3 . In the case in point, the end of the strap  3  is sewn onto itself around an axis (not shown) of the base  1 . 
     The base  1  comprises two parallel lateral surfaces  18 ,  19  rigidly connected to each other by a connection plate  20 , provided with a point  21  for the application of a resilient return member as mentioned in greater detail below. 
     The ends of the lateral parallel surfaces  18 ,  19  of the base  1 , opposite to the point of fastening of the strap  3  define two flanges  22 ,  23 , that are also parallel and provided with a central bore  24 , and each further defining a substantially semi-circular receiving cradle  25  that is external relative to the flanges. 
     The central bore  24  of the two flanges  22 ,  23  is intended to receive, in the manner of a bearing, a rotatable drum  4 , on which the other end of the strap  3 , or even another strap, is intended to be wound. This drum  4  comprises two half-axes  26 ,  27  of substantially semi-circular transverse cross-section, separated from one another through the respective engagement thereof with two lateral toothed wheels  7  and  8 , each drilled with two orifices  28 ,  29  of matching shape. The two half-axes  26 ,  27  are rigidly connected in translatory motion by two folded axes  30 , or possibly by caulking or snapping the ends of the half-axes. 
     On the other hand, in the absence of constraint, the drum  4  is mounted free in rotation, and is therefore able to rotate in one direction or in the other. 
     The two lateral toothed wheels  7  and  8  are rigidly connected to the drum  4 , as will have been understood from the previous description. 
     The teeth of the wheels  7  are shaped so as to promote the rotation of the drum  4  in one direction and, conversely, to counter the rotation of the drum  4  in the other direction, through the engagement of the teeth with a holding pawl  9 , provided in the base  1 , and a driving pawl  10 , provided in a tension lever  5 , described in greater detail later. 
     To be more specific, the holding pawl  9  comprises a rigid blade, made of metal for example, whereof two lateral protuberances are each able to slide in a through aperture  11  which can be better seen in  FIG. 5  or in  FIG. 8 , and is provided in the lateral surfaces  18 ,  19  of the base  1 . The motion of the pawl  9  is purely translatory. The pawl  9  is permanently subject to the action of a resilient return member, typically comprising a spring (not shown), that presses against the projection  21  issuing from the plate  20  connecting the lateral surfaces of the base  1 , and causing the pawl  9  to thrust against the teeth of the toothed wheels  7 . 
     The device includes as already stated a tensioning lever  5 , which is hinged onto the drum  4 . This lever comprises a rigid structure comprising two parallel lateral surfaces  31 ,  32 , rigidly connected to each other by means of a rear plate  33 , and able to receive a grip zone  34  which can be snapped on. The ends of the lateral surfaces on the opposite side to the grip zone define two flanges  35 ,  36 , that are also parallel, each being provided with a central bore  37 , whereof the internal diameter substantially matches the external diameter of the drum  4 . The latter therefore constitutes the hinge pin of the tensioning lever. 
     This lever  5 , as already stated, comprises a driving pawl  10 , which like the holding pawl  9 , also comprises a metal, and therefore rigid, blade, provided with two lateral protuberances, each able to move in a through aperture  12  provided in the lateral surfaces  31 ,  32  of the lever  5 . Like the holding pawl  9 , the driving pawl  10  is subject to the action of a resilient return member, formed in the case in point by a spring (not shown), that presses against a projection  38  issuing from the rear plate  33  (see  FIG. 8 ), in order to cause the driving pawl  9  to thrust permanently against the teeth of the toothed wheels  7 . 
     In other words, and as may be seen, for example, in  FIG. 5 , the two pawls: the holding pawl  9  and the driving pawl  10  respectively, are permanently engaged or, in other words, mesh with the teeth of the toothed wheels  7  because of the respective actions of the springs to which they are subject. Thus, because of the particular orientation of the teeth, the pawls  9 ,  10  counter the rotation of the drum  4  in one particular direction, and in the case in point, as is shown in the figures, in the clockwise direction. 
     On the other hand, and again because of the orientation or particular profile of the teeth, this engagement of the pawls  9 ,  10  with the teeth does not counter the rotation of the drum  4  in the opposite direction, namely in the figures in the trigonometric direction. 
     Thus, when a user wishes to tension a strap, he actuates the lever  5  in a steady manner which, by means of the driving pawl  10 , causes the drum  4  to rotate. Pulling the lever down against the base  1  to rotate the drum anew in order to obtain the required tension, is not detrimental to the previously obtained tension because of the engagement of the holding pawl  9  with the toothed wheels  7 , keeping the drum in the position it was in when the tensioning lever  5  was previously actuated. 
     In accordance with the invention, the strap tensioning device also includes an unlocking lever  6 , described in greater detail below. 
     This unlocking lever  6  is also hinged onto the drum  4 . In accordance with one inventive feature, the unlocking device  6  can be actuated completely independently of the driving pawl  5 . 
     This unlocking lever  6  comprises two lateral flanges  13  drilled at the centre thereof with a bore  39 , whereof the internal diameter substantially matches the external diameter of the drum  4 . The two flanges  13  are rigidly connected to one another by a plate  40 , able to receive a grip zone  41  which can be snapped on. 
     The periphery of each of the flanges  13  is extended by a cam-forming protuberance  14 , of gradually increasing width, the gradual crease in the width of the cams also being orientated in the trigonometric direction in  FIG. 3 . 
     It is clear from these explanations as well as from the various figures, that the base  1 , the tensioning lever  5  and the unlocking lever  6  are embedded within each other. These various elements are thus rotated relative to each other relative to the axis of rotation of the drum  4 . 
     As may be clearly seen in  FIG. 3 , the cams  14  are intended to engage with the holding pawl  9  of the base  1 , and the driving pawl  10  of the tensioning lever  5  respectively. Thus, when the unlocking lever  6  is actuated, and in the case in point as shown in  FIG. 2 , the cams thrust the two pawls  9 ,  10 , which slide in their respective apertures, releasing them from their engagement with the toothed wheels  7 . The drum  4  is then once again free in rotation thereby unlocking the tension previously provided by the inventive tensioning device. 
     It is in fact easy to understand the extreme simplicity of releasing the tension imparted to the strap or straps by using the inventive device, merely by actuating this unlocking lever, the cams which are associated therewith acting as power reduction system. 
     When it is wished once again to tension the strap or straps, the unlocking lever  6  has only to be towered towards the base  1 , as shown in  FIGS. 1 ,  4  to  6 , in order to eliminate the engagement of the cams  14  with the end of the holding and driving pawls, so that they re-engage with the toothed wheels  7 , and restrict the rotation of the drum  4  only in the direction of the tension. 
     Advantageously, the strap  3  is rigidly connected to the base  1  on a rotatable axis  15 , accommodated in the lateral surfaces  18 ,  19 , that can be manually actuated by a crank  16 , hinged onto one of the ends of the axis. It is thus possible to store the strap  3  on this axis, as is shown in  FIGS. 6 and 7 , and not on the axis providing the tension, in the case in point the drum  4 . 
     Storage of the strap on the inventive tensioning device is thus facilitated, since, because of the relative distance of the storage axis  15  from the remainder of the device, it is typically possible to store some five metres in length of strap, which could not be achieved with prior art devices. 
     Incidentally, the crank  16  may be locked against the base  1  when it is not in use, by inserting its free end into a through aperture  17 , provided on one of the lateral walls of the base  1 . 
     It is easy to understand the full advantage of the inventive device, which facilitates the use of the tensioning member, without significant effort, and in complete safety. 
     Although embodiments have been described herein, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.