Abstract:
A self-locking device having continuous locking positions comprises bases ( 21, 31 ), self-locking components ( 22, 32 ), first locking blocks ( 23, 33, 33 ′) and second locking blocks ( 23   a,    33   a,    33   a ′). Inner walls of the bases ( 21, 31 ) comprise first frictional contact surfaces ( 21 W,  31 W) and fourth frictional contact surfaces ( 21 M,  31 M). The self-locking components ( 22, 32 ) have second frictional contact surfaces ( 22 M,  32 M) and third frictional contact surfaces ( 22 W,  32 W), and are at least partially located in the bases ( 21, 31 ), so that the second frictional contact surfaces ( 22 M,  32 M) face the first frictional contact surfaces ( 21 W,  31 W), and the third frictional contact surfaces ( 22 W,  32 W) face the fourth frictional contact surfaces ( 21 M,  31 M). The first locking blocks ( 23, 33, 33 ′) are disposed between the first frictional contact surfaces ( 21 W,  31 W) and the second frictional contact surfaces ( 22 M,  32 M), and contact the first frictional contact surfaces ( 21 W,  31 W) and the second frictional contact surfaces ( 22 M,  32 M). The second locking blocks ( 23   a,    33   a,    33   a ′) are disposed between the third frictional contact surfaces ( 22 W,  32 W) and the fourth frictional contact surfaces ( 21 M,  31 M), and contact the third frictional contact surfaces ( 22 W,  32 W) and the fourth frictional contact surfaces ( 21 M,  31 M). The first locking blocks ( 23, 33, 33 ′) and the second locking blocks ( 23   a,    33   a,    33   a ′) are in such a structure that the self-locking components ( 22, 32 ) are capable of moving along a first direction (F 1 ) relative to the self-locking bases ( 21, 31 ) under the effect of an external force, and are locked in a second direction (F 2 ) opposite to the first direction (F 1 ). In this way, the self-locking components ( 22, 32 ) can be locked at any one of the continuous locking positions. Also disclosed is a tool ( 7 A- 7 C) for locking and unlocking the self-locking device. The self-locking device is capable of implementing fast locking and unlocking, which is convenient to use.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the priorities of Chinese patent applications No. 201110020106.4 filed Jan. 6, 2011 and titled “Fast mounting and demounting system for supplementary wheel used for motor vehicle”, No. 201120017252.7 filed Jan. 6, 2011 and titled “Fast mounting and demounting system for supplementary wheel used for motor vehicle”, No. 201120017247.6 filed Jan. 6, 2011 and titled “Locking device featured by fast mounting and demounting and tool therefor”, No. 201110143418.4 filed May 31, 2011 and titled “Wheel and a wheel mounting and demounting system”, and No. 201110143416.5 filed May 31, 2011 and titled “Fastener and mounting and demounting equipment for the same”, which are incorporated herein by reference in their entirety. 
       FIELD OF THE INVENTION 
       [0002]    The invention relates to a self-locking device and a locking and unlocking equipment therefor. 
       BACKGROUND OF THE INVENTION 
       [0003]    The existing fastener may be locked by a screw, a buckle, a pin, etc., to fasten objects in position. If the relative positions of the fastened objects are improper, however, the fastener needs to be unlocked, and then locked again after the positions of the objects are adjusted properly, which is timing consuming and strenuous. For example, fasteners (e.g. construction fasteners) are used for connecting pipes (e.g. metal pipes) to build a falsework in the construction field. These fasteners are locked by screws to fasten the pipes, which is timing consuming, strenuous and inefficient. 
         [0004]    To address this problem, a self-locking fastener, which includes a ratchet wheel and a detent or locking teeth, is proposed in the prior art, but is defective for a retracting stroke during its locking and for discontinuous self-locking instead of continuous self-locking, which degrades its locking effect. 
       SUMMARY OF THE INVENTION 
       [0005]    An object of the invention is to provide a self-locking device, particularly but not limited to, a construction fastener, and a locking and unlocking equipment for the self-locking device, to address the above problem. The inventive self-locking device, which is convenient for use, may be used for quickly locking an object to be fastened with a good locking effect. For example, the locking or unlocking of the inventive construction fastener may be achieved in a few seconds. 
         [0006]    In an aspect, a self-locking device with continuous locking positions includes: a housing with an internal cavity, where a wall of the cavity includes a first frictional contact face; a locking member with a second frictional contact face, which is arranged at least partially in the cavity, with the second frictional contact face facing the first frictional contact face; and a lock block, which is arranged between and contacts with the first and second frictional contact faces; where, the lock block allows the locking member to be movable with respect to the housing in a first direction but locked in a second direction opposite to the first direction, so that the locking member is locked at any continuous locking position. 
         [0007]    In another aspect, a self-locking device with continuous locking positions includes: a housing with an internal cavity, where a wall of the cavity includes a first frictional contact face and a fourth frictional contact face; a locking member with a second frictional contact face and a third frictional contact face, which is movable in the cavity, with the second and third frictional contact faces facing the first and fourth frictional contact faces, respectively; and a first lock block and a second lock block, with the first lock block being arranged between and contacting with the first and second frictional contact faces, and the second lock block being arranged between and contacting with the third and fourth frictional contact faces; where, the first and second lock blocks allow the locking member to be movable with respect to the housing in a first direction but locked in a second direction opposite to the first direction, so that the locking member is locked at any continuous locking position. Here, four frictional contact faces and two lock blocks are adopted for achieving a better locking effect comparing with the case where only one lock block and two frictional contact faces are adopted. 
         [0008]    In a further aspect, there is provided a tool for locking and unlocking the above self-locking devices, which applies a force on the self-locking device to lock and unlock the device. 
         [0009]    The tool has a stick shape, one end of the tool is an unlocking end for unlocking the self-locking device, and the other end of the tool is a locking end for locking the self-locking device, wherein the unlocking end is provided with two parallel bent hooks for hooking fixed parts of the housing of the self-locking device to allow the tool to be rotated about the fixed parts; two protrusions are arranged between the bent hooks for pressing the lock blocks of the self-locking device during the rotation; and the locking end is provided with a concave. 
         [0010]    Alternatively, the tool has a stick shape, and each of two ends of the tool is provided with a pair of pawls with a different interval. 
         [0011]    Alternatively, the tool has stick shape, and one end of the tool is provided with two pairs of pawls with different intervals, with one pair of pawls facing the other pair of pawls. 
         [0012]    The continuous self-locking of the inventive device is achieved by the lock blocks(s) and the frictional contact faces, thus achieving a better locking effect comparing with the discontinuous locking in the prior art. Further, the inventive device is easy to unlock, and its operative efficiency is significantly improved due to its simple operations. For example, the locking and unlocking of the inventive device may be achieved in much short time comparing with the fasteners in the prior art, so that a falsework may be built quickly. Further, the inventive device operates stably, and may undertake a large load and a dynamic load. 
         [0013]    In the prior art, any construction fastener relying on a screw connection is very demanding for the alignment of screw holes for the purpose of the screw connection, and hence is demanding for a high size precision and manufacturing processes of various components of the fastener, leading to increased manufacturing costs. In the invention, however, the locking member is used for mutual fastening of various components without demanding for the above high size precision, therefore the inventive device may be manufactured easily at a low cost. 
         [0014]    The inventive device works at a low noise level. 
         [0015]    For a better locking effect of the lock block(s), the self-locking device may further include a holding member including one or more compression springs which apply forces on the lock block(s), to ensure the contact between each lock block and respective two frictional contact faces. 
         [0016]    The inventive self-locking device is advantageous for its continuous self-locking and/or fastening, i.e. locking and/or fastening at any position, so that the locking and/or fastening of the inventive self-locking device may be performed with an improved precision and the locking and unlocking of the inventive self-locking device may be performed within much less time in comparison with screwing. 
         [0017]    The problem of retracting stroke that exists in ratchet wheels and teeth does not happen to the self-locking device, which may be used for locking an object without any retracting stroke, so that the locking and/or fastening precision is improved. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    The accompanying drawings, which form a part of the application, are intended to provide further understanding of the invention. Illustrative embodiments of the invention are intended to explain, but not to limit, the invention. 
           [0019]      FIG. 1A  shows principles of a self-locking device in a first embodiment of the invention; 
           [0020]      FIG. 1B  shows a force triangle illustrating the principles of the self-locking device in the first embodiment of the invention; 
           [0021]      FIGS. 1C-1D  respectively show structures and principles of the self-locking device in a second and a third embodiments of the invention; 
           [0022]      FIGS. 2A-2B  show a front view and a sectional view along a line A-A of the self-locking device in the second embodiment, respectively; 
           [0023]      FIGS. 2C-2D  show sectional views along lines B-B and C-C of the self-locking device in the second embodiment, respectively; 
           [0024]      FIGS. 3A-3B  show a front view and a sectional view along a line A-A of the self-locking device in the third embodiment, respectively; 
           [0025]      FIGS. 3C-3D  show sectional views along lines B-B and C-C of the self-locking device in the third embodiment, respectively; 
           [0026]      FIG. 4  shows a sectional view along a line B-B of a variant of the self-locking device in the third embodiment; 
           [0027]      FIG. 5A  shows a front view of a construction fastener embodying the self-locking device in the second embodiment; 
           [0028]      FIGS. 5B-5C  show sectional views along lines A-A and B-B of the fastener embodying the self-locking device in the second embodiment, respectively; 
           [0029]      FIGS. 6A-6F  show a front view, a top perspective view, a bottom perspective view, a sectional view along a line A-A, a sectional view along a line B-B, and a sectional view along a line C-C of a variant of the fastener embodying the self-locking device of an embodiment; 
           [0030]      FIG. 7  shows a sectional view of a rotatable construction fastener embodying the self-locking device in the third embodiment; 
           [0031]      FIG. 8  shows a perspective view of a right-angle construction fastener embodying the self-locking device in the third embodiment; 
           [0032]      FIGS. 9A-9C  respectively show a front view, a sectional view along a line A-A and a sectional view along a line B-B of a plier-type fastener embodying the self-locking device in the second embodiment; 
           [0033]      FIG. 10  shows a sectional view of a gripper-type fastener embodying the self-locking device in the second embodiment; and 
           [0034]      FIGS. 11A-11C  show dedicated tools of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0035]    The invention is described below referring to the accompanying drawings and embodiments. The embodiments or features in embodiments may be combined without conflict. 
       Self-Locking Device of a First Embodiment 
       [0036]    The self-locking device in the first embodiment includes a housing  1  with a cavity, a locking member  2  and a lock block  3 , and preferably further includes a holding member. The lock block  3  may have a spherical or elliptic shape, for example. The holding member may include a spring and a spring retainer (which may be a part of the housing). The wall of the cavity of the housing  1  includes a frictional contact face (i.e. locking face) W and the locking member includes a frictional contact face M. 
         [0037]    The structure and operation principles of the self-locking device in the first embodiment are described as follows. The above two frictional contact faces form an angle α, with the lock block being sandwiched between the faces. A spring may be provided to apply a pretightening force on the lock block along a direction from the lock block towards the vertex of the angle α, so that the lock block may be kept in contact with the frictional contact faces, and the locking member may be locked by the lock block which is in frictional contact the two frictional contact faces. If a force opposite to the pretightening force of the spring is applied to the lock block to separate the lock block from the frictional contact faces, the lock block is released and hence the locking member is unlocked. That is, the locking member can be unlocked by applying an external force to the lock block. 
         [0038]    The theory about self-locking of the self-locking device in the first embodiment is described below. 
         [0039]    As shown in  FIG. 1A , a force applied to the lock block  3  by the (first) frictional contact face W is denoted by R 13 , a force applied to the lock block  3  by the (second) frictional contact face M is denoted by R 23 , the pretightening force P, which is at an angle β with respect to the first frictional contact face, is applied to the lock block  3  by a spring, the first frictional contact face W is at an angle α with respect to the second frictional contact face M, a frictional angle and a friction factor between the lock block and the first frictional contact face W are denoted by φ 1  and μ 1 , respectively, and a frictional angle and a friction factor between the lock block and the second frictional contact face M are denoted by φ 2  and μ 2 , respectively, where μ 1 =tan φ 1  and μ 2 =tan φ 2 . The normals of the first and second frictional contact faces are denoted by Y 1  and Y 2 , respectively. 
         [0040]    As desired, the friction factor between the lock block  3  and the first frictional contact face may be the same as or different from that between the lock block  3  and the second frictional contact face. Components of the self-locking device may be made of the same or different materials (e.g. metal, plastic, ceramic) as desired, even the same component may be made of several materials. 
         [0041]    According to such a criterion that the generated resistance is less than or equal to zero in the case of reversal of stroke, as shown in  FIG. 1B , a self-locking condition is determined as follows. 
         [0000]    
       
         
           
             
               
                 
                   R 
                   13 
                 
                 
                   sin 
                    
                   
                     ( 
                     
                       
                         90 
                          
                         ° 
                       
                       + 
                       
                         ϕ 
                         2 
                       
                       - 
                       β 
                     
                     ) 
                   
                 
               
               = 
               
                 P 
                 
                   sin 
                    
                   
                     ( 
                     
                       α 
                       - 
                       
                         ϕ 
                         1 
                       
                       - 
                       
                         ϕ 
                         2 
                       
                     
                     ) 
                   
                 
               
             
             , 
           
         
       
     
         [0000]    that is, 
         [0000]    
       
         
           
             
               P 
               = 
               
                 
                   R 
                   13 
                 
                  
                 
                   
                     sin 
                      
                     
                       ( 
                       
                         α 
                         - 
                         
                           ϕ 
                           1 
                         
                         - 
                         
                           ϕ 
                           2 
                         
                       
                       ) 
                     
                   
                   
                     cos 
                      
                     
                       ( 
                       
                         
                           ϕ 
                           2 
                         
                         - 
                         β 
                       
                       ) 
                     
                   
                 
               
             
             , 
           
         
       
     
         [0000]    therefore, to prevent the release of the lock block from the first and second frictional contact faces, P shall be less than or equal to 0. Considering −90°&lt;φ 2 -β&lt;90°, then cos(φ 2 -β)&gt;0, and hence α≦φ 1 +φ 2 , i.e. the condition for self-locking. 
         [0042]    That is, if the angle α is less than or equal to the sum of the frictional angles φ 1  and φ 2 , the locking member is allowed to be moved in a first direction F 1  with respect to the housing, but locked in a second direction opposite to the first direction, so that the locking member can be continuously locked, i.e. locked at any of continuous locking positions. 
         [0043]    If the self-locking device is made of steel, the frictional angles φ 1 =φ 2 =8.5° since the friction factor of steel is about 0.15, thus the angle α is less than about 17°. However, the self-locking device may be made of any other suitable material, and even the same component of the device may be made of various materials. 
         [0044]    Based on the operation principle of the self-locking device in the first embodiment, it is possible to combine multiple, e.g. two, self-locking devices as desired. 
         [0045]      FIGS. 1C-1D  show the structure and operation principle of the inventive self-locking device in the second and third embodiments. 
         [0046]    Four frictional contact faces  11 W,  12 M,  12 W,  11 M, two lock blocks (i.e. a first lock block and a second lock block)  13 ,  13   a,  and a holding member (which may include two springs) are provided in the self-locking device of the first or second embodiment. 
         [0047]    The pretightening force P is at an angle β with respect to the second frictional contact face  12 M, the first and second frictional contact faces ( 11 W,  12 M) form an angle α≦φ 1 +φ 2 , where φ 1  denotes the frictional angle between the first lock block and the first frictional contact face  11 W and φ 2  denotes the frictional angle between the first lock block and the second frictional contact face  12 M. The third and fourth frictional contact faces ( 12 W,  11 M) form an angle α′≦φ 3 +φ 4 , where φ 3  denotes the frictional angle between the second lock block and the third frictional contact face and φ 4  denotes the frictional angle between the second lock block and the fourth frictional contact face. The angle between the second and third frictional contact faces ( 12 M,  12 W) is denoted by γ, and the angle between the first and fourth frictional contact faces ( 11 W,  11 M) is denoted by θ, then θ≦φ 1 +φ 2 +φ 3 +φ 4 +γ, so that the locking member is allowed to be moved in the first direction F 1  by an external force, but locked stably in a second direction F 2  opposite to the first direction F 1 . The above angles may be designed according to the above principles, so that the locking member can be locked at any of continuous locking positions by the lock blocks. 
         [0048]      FIGS. 2A-2D  show the structural representation of a preferable example of the self-locking device in the second embodiment. The self-locking device in the second embodiment includes a housing  21 , a locking member  22 , an optional holding member (including springs  24 ) and two lock blocks  23 ,  23   a , and preferably includes spring retainers  25 , a pin  26 , nuts  27 , and screws  28  for fixing the spring retainers. 
         [0049]    The housing  21  further functions for mounting of other components and/or itself. The locking member  22  is rotatablely connected in the internal cavity of the housing  21  through the pin  26 . The wall of the internal cavity of the housing  21  includes two locking faces  21 W and  21 M (which are equivalent to the first and fourth frictional contact faces  11 W,  11 M shown in  FIGS. 1C-1D ) and the spring retainers  25  are provided in the housing  21 , preferably as a part of the housing  21 . The housing  21  may be fixed to an external object such as a clamp by screw holes  21 C, or formed integrally with the clamp. 
         [0050]    The locking member  22  includes two side locking faces  22 M and  22 W (which are equivalent to the second and third frictional contact faces  12 M and  12 W shown in  FIGS. 1C-1D ). The locking faces  22 M and  22 W may have a flat shape, or a partial annular shape (the center of which is the central hole  22 E of the locking member  22 , as shown in the B-B sectional view of  FIG. 2C ), or any other shape facilitating the rolling or sliding of the lock blocks  23  and  23   a  on the locking faces. Preferably, the locking faces  21 W and  22 M and the locking faces  22 W and  21 M are shaped to substantially complementary with the lock block  23  or  23 ′, to increase the contact area between the locking faces and the lock block  23  or  23 ′. The locking faces  21 W and  21 M in the housing  21  are designed such that the vertex of an angle α between the locking faces  21 W and  22 M or the vertex of an angle α′ between the locking faces  21 M and  22 W (i.e. the angle between two frictional contact faces contacting with the same lock block) points substantially along the direction F 1 . If the side locking faces  22 W and  22 M of the locking member  22  form an angle γ, then the angle θ between the locking faces  21 W and  21 M meets a condition of θ≦φ 1 +φ 2 +φ 3 +φ 4 +γ, to achieve the locking of the locking member, that is, the locking member  22  can be rotated along the direction F 1  but not in the opposite direction F 2 . Only if any of the lock blocks is released or separated from any of the frictional contact faces by the effect of an external force, the locking member can be unlocked and then moved in the direction F 2 . Two open grooves  22 B are provided in the two side locking faces of the locking member  22 , and the lock blocks are positioned at the grooves  22 B before the use of the self-locking device  22 , to facilitate the use and improve the use efficiency of the device. 
         [0051]    As shown in  FIGS. 5A-5C , the self-locking device of the second embodiment is provided with a joint member  20 , which is connected rotatablely or detachably with a lower clamp arm of the device and used for joining the lower clamp arm with an upper clamp arm of the device to sandwich an object in the self-locking device, when the joint member  20  is engaged with and tightened by the locking member. The joint member  20  may have various shapes, e.g. a ring shape, a T shape connected with a ring, etc., to join the upper and lower clamp arms. 
         [0052]    The upper and lower clamp arms, which are rotatablely connected by a pin or formed integrally, are used for clamping an object in the self-locking device by means of the joint member  20 . 
         [0053]    For example, the self-locking device in the second embodiment may include a housing  21 , a locking member  22 , two lock blocks  23  and  23   a , two springs  24 , a spring retainer  25 , a pin  26 , a joint member  20 , nuts  27  and a screw  25 A for mounting the spring retainers. 
         [0054]    The locking member  22  includes the second and third frictional contact faces  22 M and  22 W, a rotating tab  22 C, and an engaging portion  22 D for the joint member. 
         [0055]    The housing  21  includes the first frictional contact face  21 W and the fourth frictional contact face  21 M. 
         [0056]    The joint member  20  may be connected to the engaging portion  22 D of the locking member to fasten an object. 
         [0057]    The pin  26  fixed by the nuts  27  improves the effect of locking the self-locking device by an external force. 
         [0058]    The nuts  27  fixing the pin  26  may be used as fulcrums for a lever to unlock the device. 
         [0059]      FIGS. 3A-3C  shows structural representation of the preferable self-locking device in the third embodiment, which is a variant of the self-locking device in the second embodiment but with the same operation principle. The self-locking device in the third embodiment includes a housing  31 , a locking member  32 , two lock blocks  33  and  33   a , and a lock block retainer (which is actuated to lock and unlock the device, as described below)  36 , and preferably includes a holding member (including a set of springs  34 ), and more preferably includes a spring retainer  35  which may be a part of the housing  31 . The self-locking device in the third embodiment is generally different from that in the second embodiment in that the locking member  32  of a different shape and an additional lock block retainer  36  are employed. 
         [0060]    The locking member  32  includes frictional contact faces  32 M and  32 W (which are equivalent to the second and third frictional contact faces  12 M and  12 W shown in  FIGS. 1C-1D ). A prying face  35 A, together with a prying face  36 B on the lock block retainer  36 , is provided for unlocking of the device. 
         [0061]    The locking member may include a cap or head  32 C, like the head of a bolt or T-shaped screw. 
         [0062]    The locking member  32  functions the same as the locking member  22 . 
         [0063]    The lock blocks  33  and  33   a  (which are equivalent to the lock blocks  13  and  13   a  shown in  FIGS. 1C-1D ) may have a trapezoidal shape, a spherical shape, etc. 
         [0064]    The springs  34  (the elastic force of which is equivalent to the force P shown in  FIGS. 1C-1D ) may be used for applying a pressing force on the lock block retainer  36 , which in turn presses against the lock blocks  33  and  33   a ; or the springs  34  apply the pressing forces on the lock blocks  33  and  33   a  directly. 
         [0065]    The spring retainer  35  supports the springs  34 , guides the lock block retainer  36  to be moved substantially longitudinally within the housing, and prevents sundries from falling into the self-locking device. 
         [0066]    The lock block retainer  36  prevents irregular movements of the lock blocks  33  and  33   a  and falling of the lock blocks  33  and  33   a  out from the housing when the locking member  32  is drawn away. Accommodating holes are provided in the wall of the lock block retainer  36  to accommodate the lock blocks  33  and  33   a,  and prevent the falling of the lock blocks  33  and  33   a  out from the housing when the locking member  32  is drawn away from the retainer  36 . Preferably, the lock block retainer  36  includes a flange at its one end, and the self-locking device can be put in its locked state through the prying by a lever between a prying face  32 A at an end of the locking member  32  and a pivot face  36 A at the top of the flange of the lock block retainer  36 . If the prying face  32 A is lifted while the pivot face  36 A is pressed down, the lock block retainer  36  presses down the lock blocks  33  and  33   a , so that the lock blocks  33  and  33   a  are tightly pressed against the housing and the locking member, and any material deformation of the device is absorbed. If the prying face  36 B is lifted through the prying by a lever, the lock block retainer  36  raises the lock blocks  33  and 33 a  to separate them from the respective frictional contact faces, so that the self-locking device is opened or unlocked. 
         [0067]    A hook  36 C protruding from a side of the lock block retainer  36  is used for keeping the self-locking device in its unlocked state. In use, when a tool  7 B or  7 C is used to pry the prying face  36 B of the lock block retainer  36 , the prying face  36 B is moved away from the housing  31  and the spring retainer  35 , and the hook  36 C is raised above the housing  31  and the spring retainer  35 , at this time, the lock block retainer  36  is pushed and inclined by a spring  34 A arranged at a side of the lock block retainer  3  that is opposite to the hook  36 C, so that the hook  36 C rests on the top surface of the spring retainer  35  and the self-locking may be kept in its unlocked state. The self-locking device may be locked again after the hook leaves the top surface of the spring retainer  35 . 
         [0068]    The inner wall of the housing  31  includes two locking faces  31 W and  31 M (which are equivalent to the first and fourth frictional contact face  11 W and  11 M shown in  FIGS. 1C-1D ), and the springs  34  are limited within the housing  31  through the spring retainer  35 . 
         [0069]    The locking faces  32 M and  32 W at two opposite sides of the locking member correspond to the locking faces  31 W and  31 M in the housing  31 , respectively, so that a lock block  33  may be sandwiched and move between the faces  31 W and  32 M and a lock block  33   a  may be sandwiched and move between the faces  31 M and  32 W. Preferably, the locking faces  31 W and  32 M and the locking faces  32 W and  31 M are shaped to substantially complementary with the lock blocks  33  and  33   a , respectively, to increase the contact area between the locking faces and the lock blocks  33 ,  33   a . The locking faces  31 W and  31 M in the housing  31  are designed such that the vertex of an angle α between the locking faces  31 W and  32 M or the vertex of an angle α′ between the locking faces  31 M and  32 W points along the direction F 1 . If an angle between the locking faces  32 M and  32 W of the locking member  32  is denoted by γ, an angle between the locking faces  31 W and  31 M is denoted by θ, and θ≦φ 1 +φ 2 +φ 3 +φ 4 +γ, then the locking of the locking member may be achieved, to allow the locking member  32  to be moved in the direction F 1  but locked in the opposite direction F 2 , where φ 1 , φ 2 , φ 3 , and φ 4  denote frictional angles as above. 
         [0070]    Preferably, the self-locking device may be structurally symmetrical along the longitudinal axial of the locking member  22  or  32 , that is, α=α′. 
         [0071]      FIG. 4  illustrates a self-locking device with lock blocks of another shape. The lock blocks  33 ′ and  33   a ′ are in surficial contact with the locking member  32  and the housing  31  to increase the frictional contact areas and reduce deformation of the frictional contact faces. 
         [0072]    The inclined first frictional contact face  33 ′W of the lock block  33 ′ is in contact with the inclined first frictional contact face  31 W of the housing  31 ′, the inclined second frictional contact face  33 ′M of the lock block  33 ′ is in contact with the inclined second frictional contact face  32 M of the locking member  32 , the inclined third frictional contact face  33   a ′W of the lock block  33   a ′ is in contact with the inclined third frictional contact face  32 W of the locking member  32 , and the inclined fourth frictional contact face  33   a ′M of the lock block  33   a ′ is in contact with the inclined fourth frictional contact face  31 ′M of the housing  31 ′. The lock block  23 ,  33  may each have a spherical shape, or a column shape with a circular, triangular, trapeziform, diamond, or irregular cross section. 
         [0073]    That is, the shape of any of the first to fourth frictional contact faces of the locking member or housing of the self-locking device is designed to match the shape of the frictional contact face of the lock block, to obtain the maximal frictional contact area as possible. 
         [0074]      FIGS. 6A-6F  show a structural representation of a construction fastener with the self-locking, which includes a housing  31 , a locking member  32 , two lock blocks  33  and  33   a,  a spring  34 , a spring retainer  35 , a lock block retainer  36 , a pin  38  and a lower base (also referred to as a lower clamp arm)  39  connected with the housing  31  through the pin  38 . 
         [0075]    The locking member  32  functions to connect the lower base. Particularly, the upper part of the locking member  32  is used to construct the self-locking device along with the housing  31  and so on, and the T-shaped lower part  32 C (e.g. a T-shaped screw head) of the locking member  32  engages with and locks the lower base. 
         [0076]    The second and third frictional contact faces  32 M and  32 W of the locking member  32  are equivalent to the second and third frictional contact faces  12 M and  12 W shown in  FIGS. 1C-1D . The frictional contact faces are shaped to match with the locking member to increase the frictional area. Like the groove  22 B, the groove  32 B on the locking member  32  is used to accommodate the lock block  33  when the self-locking device is in its unlocked state, to prevent unintended locking of the locking member  32 . Lifting the prying face  32 A on the locking member  32  and meanwhile pressing the pivot face  36 A on the lock block retainer  36  by a lever results in the locked state of the self-locking device. The groove  32 B can be used for unlocking the self-locking device. 
         [0077]    The lock blocks  33 - 33   a  are equivalent to the lock blocks  13 - 13   a  shown in  FIGS. 1C-1D . 
         [0078]    The wall of the lock block retainer  36  contains two slots for the lock blocks. When the pivot face  36 A on the lock block retainer  36  is pressed and the prying face  32 A on the locking member  32  is lifted by a tool  7 B or  7 C, the lock block retainer  36  pushes down the lock blocks  33  and  33   a,  which are respectively tightly sandwiched between the first and second frictional contact faces  31 W and  32 M and between the third and fourth frictional contact faces  31 M and  32 W, to achieve tight locking of the self-locking device. When the prying face  36 B on the lock block retainer  36  is lifted from the prying face  35 B on the spring retainer  35  by a lever, the lock block retainer  36  is lifted, causing the lock blocks  33  and  33   a  to be lifted towards the spring retainer  35  and release from the second and third frictional contact faces  32 M and  32 W of the locking member  32 , so that the locking member  32  can move longitudinally, that is, the locking member  32  can move freely along the direction F 2  or F 1 . Prying holes  36 D in the wall of the retainer  36  function the same as the prying face  36 B but require for a different tool. The self-locking device can also be unlocked by levering an end  36 C of the lock block retainer  36  and the prying face  39 A below. 
         [0079]    The first and fourth frictional contact faces  31 W and  31 M of the housing  31  are equivalent to the first and fourth frictional contact faces  11 W and  11 M shown in  FIGS. 1C-1D . The housing  31  and the spring retainer  35  may be fixedly engaged with each other or formed integrally. 
         [0080]    A spring  34  presses against the lock block retainer  36 , which in turn presses the lock blocks  33  and  33   a  against the respective frictional contact faces. The spring  34  may be alternatively arranged within the housing  31 , and pressed between the spring retainer  35  and the lock blocks  33  and  33   a  as well as the lock block retainer  36 . The force of the spring  34  is equivalent to the force P shown in  FIGS. 1C-1D . 
         [0081]    The lock block retainer  36  extends through the spring retainer  35 , which ensures the substantially perpendicular movement of the lock block retainer  36  and prevents the entry of foreign objects into the self-locking device. The spring retainer  35  is fixedly engaged with the housing  31  by a buckling part  35 A or any other means. 
         [0082]    The pin  38  as a hinge part is used to connect the housing (i.e. an upper arm) with the lower base  39  of the self-locking device. 
         [0083]    The inventive self-locking device may be used alone, or multiple self-locking devices may be combined. 
         [0084]    The inventive self-locking device may be adapted for locking an object having a various shape such as a cylindrical shape to connect, fasten or seal the object. 
         [0085]    For example, a preferable example of the self-locking device in the second embodiment is shown in  FIGS. 5A-5C . The self-locking device may be used as a construction fastener, for example. 
         [0086]      FIGS. 5A-5C  show the self-locking device (i.e. a construction fastener) of the second embodiment, which includes a housing  21  (which is combined with an upper cover to form an upper clamp arm of the construction fastener), a locking member  22 , two lock blocks  23  and  23   a , two springs  24 , a torsion spring  24 A for the locking member  22 , a joint member  20 , a torsion spring  24 B for the joint member  20 , a spring retainer  25 , pins  26  and  26 A, nuts  27 , a lower clamp arm  29  and an optional frictional pad  201 . 
         [0087]    The wall of a cavity of the housing  21  includes the first and fourth frictional contact faces  21 W and  21 M (which are equivalent to the first and fourth frictional contact faces  11 W and  11 M shown in  FIGS. 1C-1D ). 
         [0088]    The lower clamp arm  29  includes: a joint member connector  29 A for connecting the joint member, a hole  29 B for hinging with the upper clamp arm, a frictional pad support  29 C for supporting a frictional pad, a connecting part for connecting with another lower clamp arm, and a stop pole  29 E for limiting the joint member. 
         [0089]    The inventive construction fastener above is similar to conventional construction fasteners, but combines the self-locking device in the second embodiment with the upper clamp arm of the conventional fastener. The joint member  20  is hinged with the joint member connector  29 A of the lower clamp arm through the torsion spring  24 B. The upper clamp arm including the housing  21  is hinged with the lower clamp arm  29  through the pin  6 A. The joint member  20  may be further rotated about the joint member connector  29 A and engaged with the engaging portion  22 D of the locking member. 
         [0090]    The spring retainer  25  may be screwed or snapped on the housing  21 , or may be a part of the housing  21 . 
         [0091]    Preferably, a frictional pad  201  is provided to increase the friction force between the fastener and an object (e.g. a pipe) locked by the fastener, thereby improve the locking stability of the fastener. 
         [0092]    The torsion spring  24 A is used to rotate the locking member to its initial position during the unlocking of the self-locking device, so that the joint member may be detached from the locking member  22 . 
         [0093]    The torsion spring  24 B is used to, on one hand, tie the joint member  20  to the lower clamp arm, and on the other hand, draw the joint member  20  against the stop pole  29 , when the joint member  20  is not locked. 
         [0094]    The connecting part  29  of the lower clamp, arm  29 , if available, is used to hinge with or is formed integrally with a lower clamp arm  29  of another fastener. 
         [0095]    The self-locking device may include one or both of the torsion springs  24 A and  24 B. 
         [0096]      FIGS. 7-8  show preferable examples of construction fasteners embodying the self-locking device in the third embodiment. The fastener includes a self-locking device, an individual fastening wrist  49  or a combined fastening wrist  59  and a pin  38 . Please be noted that the features of the construction fastener including the self-locking device of the second embodiment may be combined with the features of the third embodiment. For example, the fastener of the third embodiment may also include an upper clamp arm and a lower clamp arm, which are not described again here. 
         [0097]    The fastening wrist  49  may be formed integrally (including the upper clamp arm and lower clamp arm of the conventional fastener), or composed of the upper and lower clamp arms. 
         [0098]    A right-angle fastener may include the combined fastening wrist  59  and two self-locking devices. 
         [0099]      FIGS. 9A-9C  show an example of an variant (i.e. a plier-type fastener) including the self-locking device in the second embodiment, and the plier-type fastener includes a housing  21  integrated with an upper clamp arm, a locking member  22 , two lock blocks ( 23 ,  23   a ), two springs ( 24 ,  24 A), a spring retainer  25 , a nut  27 , a lower clamp arm, a joint member  20 , and a pin ( 26 ,  26 A). 
         [0100]    As shown, the housing  21  includes an upper locking concave  21 A, while the lower clamp arm  29  includes a matching lower locking concave  29 F. 
         [0101]    The engagement of the upper locking concave  21 A with the lower locking concave  29 F can fasten various objects, and the locking concaves  21 A and  29 F may have different shape depending on the target object to be fastened. 
         [0102]    The spring  24 A drives the housing  21  and the lower clamp arm  29  away from each other. 
         [0103]    The locking and unlocking principles of the plier-type fastener are substantially the same as those of the above fastener, for example, as shown in  FIGS. 1A-2D . 
         [0104]    The plier-type fastener may be used alone or with another plier-type fastener. 
         [0105]    A gripper-type fastener shown in  FIG. 10  includes a housing  21  combined with an upper clamp arm, a locking member  22 , two lock blocks ( 23 ,  23   a ), two spring  24 , a spring retainer  25 , a nut  27 , a pin  28 , a lower clamp arm  29 , and a joint member  20 . 
         [0106]    The housing  21  includes a first locking concave  21 G and a second locking concave  21 H. 
         [0107]    The lower clamp arm  29  includes a first locking concave  29 G and a second locking concave  29 H. The lower clamp arm  29  may also include only one locking concave. Alternatively, the joint member  20  may be used for fastening an object if there is no such lower clamp arm  29 . 
         [0108]    The gripper-type fastener may include one or more self-locking devices. 
         [0109]    The locking and unlocking tool  7 A dedicated for locking and unlocking the second embodiment of the self-locking device is shown in  FIG. 11A . The tool  7 A includes an unlocking end  72  and a locking end  74 . To unlock the self-locking device, two hooks  78  at the unlocking end  72  hook the nuts  27  which are also used as fulcrums, and two pressing points  76  of the tool  7 A rest on the two lock blocks of the self-locking device and then drive the lock blocks to be detached from the respective frictional contact faces due to the rotation of the tool  7 A, so that the locking member  22  is unlocked. To lock the self-locking device, the locking end  74  is engaged with a tab of the locking member and rotated along the locking direction F 1 , so that the locking member may be held at any continuous locked position. 
         [0110]    The locking and unlocking tools  7 B- 7 C dedicated for locking and unlocking the self-locking device of the third embodiment are shown in  FIGS. 11B-11C . 
         [0111]    Locking prying points  71  of the tools  7 B- 7 C are used for contacting the pivot faces  32 A while locking pivot points  73  of the tools  7 B- 7 C are used for contacting the prying faces  36 A, and levering of the tools  7 B- 7 C can lock the self-locking device. 
         [0112]    Unlocking prying points  75  of the tools  7 B- 7 C are used for contacting the prying faces  36 B while unlocking pivot points  77  of the tools  7 B- 7 C are used for contacting the prying faces  35 B, and levering of the tools  7 B- 7 C can unlock the self-locking device. 
         [0113]    The tools  7 B- 7 C may have other various structures, as long as the tools can be used to press the lock block retainer  36  while lifting the locking member  32 , or lift the lock block retainer  36  while pressing the housing  31 . 
         [0114]    The tools  7 A- 7 C may be hydraulic or pneumatic depending on demands by the self-locking devices in the second and third embodiments, or even integrated with the housing of the self-locking device. 
         [0115]    Table 1 below shows a list of reference numerals. 
         [0000]    
       
         
               
               
             
           
               
                   
               
               
                 Terms 
                 Numerals 
               
               
                   
               
             
             
               
                 First frictional contact face 
                 W, 11W 21W, 31W 
               
               
                 Second frictional contact face 
                 M, 12M, 22M, 32M 
               
               
                 Third frictional contact face 
                 12W, 22W, 32W 
               
               
                 Fourth frictional contact face 
                 11M, 21M, 31M 
               
               
                 Housing 
                 1, 11, 21, 31 
               
               
                 Locking member 
                 2, 12, 22, 32 
               
               
                 Lock block 1 
                 3, 13, 23, 33, 33′ 
               
               
                 Lock block 2 
                 3a, 13a, 23a, 33a, 33a′ 
               
               
                 Spring 
                 24, 24A, 34, 34A 
               
               
                 Spring retainer 
                 25, 35 
               
               
                 Pin 
                 26, 26A, 38 
               
               
                 Nut 
                 27 
               
               
                 Screws for fixing spring retainers 
                 28 
               
               
                 Lower clamp arm 
                 29, 39 
               
               
                 Joint member 
                 20 
               
               
                 Screw hole 
                 21C 
               
               
                 Upper locking concave 
                 21A 
               
               
                 First locking concave of upper clamp arm 
                 21G 
               
               
                 Second locking concave of upper clamp arm 
                 21H 
               
               
                 Central hole 
                 22E 
               
               
                 Open groove on locking face 
                 22B, 32B 
               
               
                 Tab 
                 22C 
               
               
                 Engaging portion 
                 22D 
               
               
                 Joint member connector 
                 29A 
               
               
                 Hinging hole 
                 29B 
               
               
                 Frictional pad support 
                 29C 
               
               
                 Connecting part for another lower clamp arm 
                 29D 
               
               
                 Stop pole for joint member 
                 29E 
               
               
                 Lower locking concave 
                 29F 
               
               
                 First locking concave of lower clamp arm 
                 29G 
               
               
                 Second locking concave of lower clamp arm 
                 29H 
               
               
                 Locking prying face of tool 
                 32A 
               
               
                 Head (or T-shaped head) 
                 32C 
               
               
                 First frictional contact face of lock block 1 
                 33′W 
               
               
                 Second frictional contact face of lock block 1 
                 33′M 
               
               
                 Third frictional contact face of lock block 2 
                 33a′W 
               
               
                 Fourth frictional contact face of lock block 2 
                 33a′M 
               
               
                 Buckling part 
                 35A 
               
               
                 Prying face 
                 35B 
               
               
                 Lock block retainer 
                 36 
               
               
                 Pivot face 
                 36A 
               
               
                 Prying face 
                 36B 
               
               
                 Unlocking end 
                 36C 
               
               
                 Prying hole 
                 36D 
               
               
                 Unlocking groove 
                 36E 
               
               
                 Lower base (lower clamp arm) 
                 39 
               
               
                 Unlocking pivot face (or prying point) 
                 39A 
               
               
                 Fastening wrist 
                 49 
               
               
                 Combined fastening wrist 
                 59 
               
               
                 Dedicated tool 
                 7A, 7B, 7C 
               
               
                 Frictional pad 
                 201 
               
               
                 Unlocking end 
                 72 
               
               
                 Locking end 
                 74 
               
               
                 Pressing point 
                 76 
               
               
                 Hook 
                 78 
               
               
                 Unlocking pivot point 
                 77 
               
               
                 Unlocking prying point 
                 75 
               
               
                 Locking Prying point 
                 71 
               
               
                 Locking pivot point 
                 73 
               
               
                   
               
             
          
         
       
     
         [0116]    The preferable embodiments of the invention have been described, but the invention is not limited thereto. Various modifications and alterations to the invention may occur to those skilled in the art, and all such modifications and alterations fall into the scope of the invention, without departing from the principle of the invention.