Abstract:
The present invention discloses a force relieving mechanism and a ratchet clamp having a force relieving mechanism. The force relieving mechanism includes a first ratchet member, a second ratchet member, a locking member, an actuating member and a restoring member. A first clamp arm of the ratchet clamp is fixedly arranged with a first ratchet member having a first set of ratchets, and a second ratchet member having a second set of ratchets is coupled to the second clamp arm by a second shaft and is rotatable in relation to the second ratchet member. The second ratchet member is provided with a first hole, the locking member passing through the first hole and being rotatable and translationally movable in the first hole. The actuating member applied a first actuation and a second actuation in turn to the locking member so as to cause the second set of ratchets to be detached from the first set of ratchets. By two actuation, the ratchet clamp having the force relieving mechanism of the present invention enables a smooth operation of the two engaged sets of ratchets, and the force relieving mechanism and the ratchet clamp having the force relieving mechanism of the present invention are simple-structured, easy for manufacturing, and convenient for use, and are conveniently and effort-savingly operated by the user.

Description:
RELATED APPLICATION 
       [0001]    This application claims priority to the PCT application number PCT/CN2014/081484, filed Jul. 2, 2014. The above-identified patent application is hereby incorporated by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to the field of hand tool and, particularly, to a force relieving mechanism and a ratchet clamp having a force relieving mechanism. 
       DESCRIPTION OF THE PRIOR ART 
       [0003]    Hand tools refer to small tools that are gripped by hand, with which a person can apply manual forces or other manually controlled forces to objects for manual cutting and auxiliary decoration. Normally, they are provided with handles facilitating carrying. Pliers are a type of common hand tools used for clamping, securing a workpiece or twisting, bending, shearing metal threads, among which the pliers used for clamping, securing a workpiece are also known as pincers or clamps. 
         [0004]    A pincer or clamp is generally in V-shape, and usually formed by two clamp bodies with symmetrical shapes and structures which are partly superposed and secured by riveting. The clamp can flexibly open and close using its riveting joint as a pivot, which includes a lever principle, thereby transforming a smaller external force (such as a manual force applied to the clamp arms) into a larger clamping force at the clamp tip so that the clamp can clamp effectively. 
         [0005]    Due to the absence of a mechanism locking the position of clamp arms in manual clamps in the prior art, the operator has to keep applying a larger force to the clamp when clamping an object until the clamping job is finished. This is both effort and time consuming, also the clamping is not steady. Regarding that, US Patent “Vise-Grip or Expanding Pliers” (U.S. Pat. No. 6,708,587B1) provides a technical solution using ratchet to lock the position of clamp arms, in which a member having ratchets is arranged on each of two clamp arms respectively, one of the members being stationary in relation to the clamp arm to which it is connected, the other of the members being rotatable in relation to the clamp arm to which it is connected, the ratchets on the two member being engaged with each other, the two sets of engaged ratchets being arranged so as to allow the movement of the two clamp arms toward each other rather than away from each other; and an actuating member is provided at the outside of one of the clamp arms (the side thereof away from the other clamp arm), in particular, a pushbutton that can automatically restore position; the actuating member is connected through a locking member to the member having ratchets and rotatable in relation to the clamp arms to which it is connected, so as to control whether the member having ratchets is engaged with the other member having ratchets. 
         [0006]    When using the clamps, the locking member keeps the two sets of ratchets being engaged with each other and the two sets of ratchets can move in relation to each other when the user applies a pair of opposing forces to the two clamp arms (i.e. one clamp arm is subjected to a force in a direction pointing toward the other clamp arm), thereby allowing the two clamp arms to be movable toward each other, thus the two clamp tips are movable toward each other to hold the object to be clamped; when the object is clamped, the user withdraws the forces applied to the two clamp arms, and the locking member keeps the two sets of ratchets being engaged with each other, the two sets of ratchets being unmovable in relation to each other, thereby keeping the clamp tips in clamping state; when the user push down the actuating member and applies forces in opposite directions to the two clamp arms (i.e. one clamp arm is subjected to a force in a direction away from the other clamp arm), the locking member is opened and the clamping force is at least partly released, the two sets of ratchets no longer being engaged with each other, thereby allowing the two clamp arms to be movable in directions away from each other, thus the two clamp tips are movable away from each other to release the clamped object. 
         [0007]    However, because the actuating member of the clamps of this prior art is arranged at the outside of one of the clamp arm, the user needs to push down the actuating member when releasing the clamped object. It is understood that when the user pushes down the actuating member, a force pointing toward the other clamp arm needs to be applied to the clamp arm where the actuating member is located, and the direction of the force is opposite to the direction of the forces applied to the hand gripping the clamp arms during the process of two actuations of the clamp arms, therefore, such operation is inconvenient and quite effort consuming. 
         [0008]    Therefore, the person skilled in the field endeavors to develop a force relieving mechanism and a ratchet clamp having a force relieving mechanism to allow the user to operate conveniently and effort-savingly. 
       SUMMARY OF THE INVENTION 
       [0009]    In view of the above defects residing in the prior art, the technical problem to be solved by the present invention is to provide a force relieving mechanism and a ratchet clamp having a force relieving mechanism, which allow the user to take advantage of engaged two sets of ratchets to lock the position of the clamp arm by arranging two sets of ratchets, an actuating member and a locking member, and to realize at least partly releasing the clamping force to the clamped object so as to conveniently and effort-savingly control the clamping and releasing of the object. 
         [0010]    In order to achieve the above object, the present invention provides a force relieving mechanism, which is arranged on a tool and used for at least partly releasing a clamping force applied by the tool on an object, comprising a locking member, an actuating member, a first ratchet member having a first set of ratchets and a second ratchet member having a second set of ratchets, one end of the first ratchet member fixedly arranged on the tool, the second ratchet member coupled to the tool, the first set of ratchets engaged with the second set of ratchets, characterized in that, the second ratchet member is provided with a first hole comprising a first hole portion and a second hole portion; the locking member is arranged passing through in the first hole; 
         [0011]    the actuating member connects the locking member, the actuating member applying a first actuation to the locking member; the first actuation causes the locking member to rotate from a first position to a second position in the first hole portion, the first ratchet member driving the second ratchet member by the first set of ratchets and the second set of ratchets that are engaged with each other, the locking member entering the second hole portion through the first hole portion, the clamping force at least partly released. 
         [0012]    Further, after the first actuation, the actuating member also applies a second actuation to the locking member, the second actuation causing separation between the first set of ratchets and the second set of ratchets. 
         [0013]    Further, the locking member comprises a first column of which the cross-section is an arch, the first column rotating in the first hole portion and the first column moving translationally in the second hole portion, a non-smoothly connected portion is provided between the first hole portion and the second hole portion. 
         [0014]    Further, the non-smoothly connected portion is a step, the step is engaged against a curved sidewall portion of the first column to prevent the locking member from entering the second hole portion from the first hole portion when the first column is in the first position in the first hole portion; the step does not come into contact with the curved sidewall portion of the first column and the locking member is able to enter the second hole portion from the first hole portion when the first column is in the second position in the first hole portion. 
         [0015]    Further, a first end of the actuating member connects the locking member so as to drive the locking member, the actuating member having a handle part extending from the first end thereof. 
         [0016]    Further, the second ratchet member is provided with a blocking part, the blocking part protruding from the second ratchet member; the blocking part is arranged on a path of the handle part swinging toward an end part of the first ratchet member that is fixed to the tool. 
         [0017]    Further, the mechanism also comprises a restoring member comprising a first elastic element arranged at the second hole portion, the first elastic element engaged against a sidewall of the first column. 
         [0018]    Further, the first elastic element is a compression spring, one end of the compression spring engaged against the first column. 
         [0019]    Further, the restoring member also comprises a second elastic element engaged against a sidewall of the handle part that is away from the blocking part. 
         [0020]    Further, the second elastic element is a torsion spring, one end of the second elastic element engaged against the handle part. 
         [0021]    Further, the tool is a clamp or a pincer. 
         [0022]    The present invention also provides a ratchet clamp, used for clamping an object, comprising a first clamp arm, a second clamp arm, a locking member, an actuating member, a first ratchet member with a first set of ratchets and a second ratchet member with a second set of ratchets, the first clamp arm and the second clamp arm being rotatable around a first shaft connecting the first clamp arm and a first shaft of the second clamp arm; one end of the first ratchet member fixedly arranged on the first clamp arm, the second ratchet member coupled to the second clamp arm, the first set of ratchets engaged with the second set of ratchets, characterized in that, 
         [0023]    the second ratchet member is coupled to the second clamp arm by a second shaft provided on the second clamp arm, the second ratchet member being rotatable in relation to the first ratchet member; 
         [0024]    the second ratchet member is provided with a first hole comprising a first hole portion and a second hole portion, the locking member is arranged passing through in the first hole; 
         [0025]    the actuating member connects the locking member, the actuating member applying a first actuation to the locking member; the first actuation causes the locking member to rotate from a first position to a second position in the first hole portion, the first ratchet member driving the second ratchet member by the first set of ratchets and the second set of ratchets that are engaged with each other, the locking member entering the second hole portion through the first hole portion, the clamping force at least partly released. 
         [0026]    Further, after the first actuation, the actuating member also applies a second actuation to the locking member, the second actuation causing separation between the first set of ratchets and the second set of ratchets. 
         [0027]    Further, the locking member comprises a first column of which the cross-section is an arch, the first column rotating in the first hole portion and the first column moving translationally in the second hole portion, a non-smoothly connected portion is provided between the first hole portion and the second hole portion. 
         [0028]    Further, the non-smoothly connected portion is a step, the step is engaged against a curved sidewall portion of the first column to prevent the locking member from entering the second hole portion from the first hole portion when the first column is in the first position in the first hole portion; the step does not come into contact with the curved sidewall portion of the first column and the locking member is able to enter the second hole portion from the first hole portion when the first column is in the second position in the first hole portion. 
         [0029]    Further, the first set of ratchets and the second set of ratchets are arranged such that they are allowed to move toward each other and obstructed to move away from each other. 
         [0030]    Further, a first end of the first ratchet member is fixed to the first clamp arm, a second end of the first ratchet member pointing toward the second clamp arm; a first end of the second ratchet member pointing toward the first clamp arm, the second end of the second ratchet member pointing toward the second clamp arm; the second set of ratchets starts from the first end of the second ratchet member to be distributed on the side part of the second ratchet member facing the first shaft; the first set of ratchets distributed on a side part of the first ratchet member away from the first shaft. 
         [0031]    Further, a first end of the actuating member connects the locking member so as to drive the locking member, the actuating member having a handle part extending from the first end thereof. 
         [0032]    Further, the second ratchet member is also provided with a blocking part, the blocking part being a portion protruding from the second ratchet member along a direction parallel to the first shaft; the blocking part is arranged on a path of the handle part swinging toward a first end of the first ratchet member. 
         [0033]    Further, the clamp also comprises a restoring member comprising a first elastic element arranged at the second hole portion, the first elastic element engaged against a sidewall of the first column. 
         [0034]    Further, the restoring member also comprises a second elastic element engaged against a sidewall of the handle part that is away from the blocking part. 
         [0035]    Further, the first elastic element is a compression spring, one end of the compression spring engaged against the first column. 
         [0036]    Further, the second elastic element is a torsion spring, a spring coil of the torsion spring surroundingly provided around the second shaft, one end of the second elastic element engaged against the handle part. 
         [0037]    Further, the first end of the actuating member comprises a first wall and a second wall in parallel arrangement, the second ratchet member partly sandwiched between the first wall and second wall; the first end of the actuating member comprises a first pair of holes respectively on the first wall and the second wall, the locking member arranged passing through in the first pair of holes and not rotatable in the first pair of holes. 
         [0038]    Further, the second ratchet member is arranged with an elongated second hole, the second shaft passing through the second hole and translationally movable in the second hole; the second hole is a closed hole or an open hole. 
         [0039]    Further, the clamp also comprises a connecting member comprising a third wall and a fourth wall in parallel arrangement, a barrier wall connected between the third wall and the fourth wall; the second ratchet member partly sandwiched between the third wall and the fourth wall; the connecting member partly sandwiched between the first wall and the second wall; the barrier wall arranged on a path of the handle part swinging toward the second clamp arm. 
         [0040]    Further, the locking member also comprises a second column adjacent to the first column, the second column being a cylinder; a third column connected between the third wall and the fourth wall, the third column longitudinally arranged in the second hole and being closer to the second clamp arm than the second shaft. 
         [0041]    Further, the connecting member is provided with a second pair of holes fitting with the second shaft and a third pair of holes fitting with the locking member, the third pair of holes being respectively on the third wall and the fourth wall; the second shaft passing through the second pair of holes, the locking member passing through the third pair of holes and being rotatable in the third pair of holes. 
         [0042]    Further, surfaces of the second ratchet member facing the third wall and the fourth wall are provided with a protruded portion coming into contact with the third wall and the fourth wall; the protruded portion being of elongated shape, extending along a direction of a movement of the second ratchet member in relation to the connecting member. 
         [0043]    Further, one of the first pair of holes fits with the first column, the other one of the first pair of holes fitting with the second column; one of the second pair of hole fitting with the first column, the other one of the second pair of holes fitting with the second column; one of the third pair of holes fitting with the first column, the other one of the third pair of holes fitting with the second column. 
         [0044]    In a preferred embodiment of the present invention, provided is a force relieving mechanism and a ratchet clamp having a force relieving mechanism, the first clamp arm and the second clamp arm are connected by a first shaft. A force relieving mechanism is arranged between the first clamp and the second clamp. The force relieving mechanism includes a first ratchet member, a second ratchet member, a locking member, an actuating member and a restoring member, in which, an end of the first ratchet member is fixedly connected to the first clamp arm, the other end pointing toward the second clamp arm, a first set of ratchets distributed on the side part thereof away from the first shaft; the second ratchet member is provided with a first hole including a circular first hole portion and an elongated second hole portion, and an elongated second hole. the opening of the second hole facing the open hole of the second clamp arm, the second shaft arranged on the second clamp arm passing through the second hole so that the second ratchet member is rotatable around the second shaft, the other end thereof pointing toward the first clamp arm, a second set of ratchets capable of fitting with the first set of ratchets being arranged thereon; the first set of ratchets and the second set of ratchets are arranged such that the first set of ratchets and the second set of ratchets allow the movement of the first clamp arm and the second clamp arm toward each other and obstruct that away from each other. The actuating member has a handle part extending from the first end of the actuating member in a direction away from the first shaft. Plate-shaped first and second wall in parallel arrangement are provided on the actuating member at the first end, a first pair of holes provided on the first wall and the second wall. The locking member includes a first column and a second column that are connected, in which the cross-section of first column is an arch, the first column passing through the first hole and rotatable in the first hole portion and translationally movable in the second hole portion. The locking member also passes through the first pair of holes of the first end of the actuation member, thereby the actuating member driving the locking member. The connecting member includes plate-shaped third and fourth walls in parallel arrangement, a third column and a barrier wall connected between the third wall and the fourth wall, the third wall and the fourth wall provided with a second pair of holes fitting with the second shaft and a third pair of holes fitting with the locking member. The second ratchet member is partly sandwiched between the third wall and the fourth wall, and the third column is longitudinally arranged in the second hole and outside the second shaft. The second ratchet member and the connecting member are partly sandwiched between the first wall and the second wall. The restoring member includes a first elastic element, which is a compression spring, arranged in the second hole portion of the first hole and engaged against a sidewall of the first column. The restoring member also includes a second elastic element, which is a torsion spring surroundingly provided around the second shaft, two end portion thereof engaged against the second clamp arm and the handle part, the second elastic element causing the actuating member to keep being engaged against the block part provided on the second ratchet member. When the user does not apply a force to the handle part toward the second clamp arm, the restoring member causes the first column to be kept in the first hole portion, where the second set of ratchets are kept in the state of being engaged with the first set of ratchets, and the first clamp tip portion and the second clamp tip portion of the ratchet clamp keep the clamping force applied to the object. When the use applies a large enough force to the handle part toward the second clamp arm, the actuating member applied a first actuation to the locking member, and the first column rotates in the first hole portion and continues to translationally move to the second hole portion, where the second set of ratchet are kept in the state of being engaged with the first set of ratchets, and the first clamp tip portion and the second clamp tip portion of the ratchet clamp release at least part of the clamping force applied to the object. When the user continues to apply a force to the handle part toward the second clamp arm, the actuating member applied a second actuation to the locking member, driving the second ratchet member to rotate around the second shaft, so that the second set of ratchets are detached from the first set of ratchets. 
         [0045]    It is thus seen that the force relieving mechanism of the present invention realizes at least partly releasing the clamping force applied to the clamped object by arranging two sets of ratchets, an actuating member and a locking member. The ratchet clamp having a force relieving mechanism of the present invention utilizes a force relieving mechanism to cause the detachment of the engaged first and second sets of ratchets by two actuations applied to the locking member by the actuating member. In the first actuation, the two clamp tip portions of the ratchet clamp release at least part of the clamping force, and the ratchets engagement is still kept. In the second actuation, the engaged two sets of ratchets are detached. Thus it can be seen that due to the first actuation at least part of the clamping force is released, the acting force between the engaged two sets of ratchets is reduced, therefore, the operation for detaching the engaged two sets of ratchets in the second actuation can occur in a more smooth way, and causes less damage to the ratchets and protects the ratchets. In addition, due to the fact that the force relieving mechanism and the ratchet clamp having the force relieving mechanism as in the present invention are arranged between the first clamp arm and the second clamp arm, the direction of the force applied by the user to the actuating member is the same as the direction of the acting force applied by the second clamp arm to the hand gripping the second clamp arm in the two actuations when releasing the clamped object, such operation being convenient and effort-saving. 
         [0046]    Referring now to the figures, the conception, detailed structure and induced technical effect of the present invention will be expounded for due understanding of the purpose, characterizations and effects of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0047]      FIG. 1  is a front view of the ratchet clamp of the present invention in a preferred embodiment; 
           [0048]      FIG. 2  is a back view of the ratchet clamp shown in  FIG. 1 ; 
           [0049]      FIG. 3  shows an exploded structural view including a first ratchet member, a second ratchet member, a locking member, an actuating member and a restoring member of the ratchet clamp shown in  FIG. 1 ; 
           [0050]      FIG. 4  shows the shape of the first hole of the second ratchet member, a cross-section thereof as shown; 
           [0051]      FIG. 5  shows the positional relationship of the first ratchet member, the second ratchet member, the locking member, the actuating member, a connecting member and the restoring member of the ratchet clamp shown in  FIG. 1  when a force is not applied to the actuating member; 
           [0052]      FIG. 6  shows the positional relationship of the second ratchet member, the locking member, a first elastic element and a second shaft shown in  FIG. 5 ; 
           [0053]      FIG. 7  shows the positional relationship of the first ratchet member, the second ratchet member, the locking member, the actuating member, the connecting member and the restoring member of the ratchet clamp shown in  FIG. 1  after a force is applied to the actuating member to drive the locking member to rotate; 
           [0054]      FIG. 8  shows the positional relationship of the second ratchet member, the locking member, the first elastic element and the second shaft shown in  FIG. 7 ; 
           [0055]      FIG. 9  shows the positional relationship of the first ratchet member, the second ratchet member, the locking member, the actuating member, the connecting member and the restoring member of the ratchet clamp shown in  FIG. 1  after a force is applied to the actuating member to drive the locking member to move; 
           [0056]      FIG. 10  shows the positional relationship of the second ratchet member, the locking member, the first elastic element and the second shaft shown in  FIG. 9 ; 
           [0057]      FIG. 11  shows the positional relationship of the first ratchet member, the second ratchet member, the locking member, the actuating member, the connecting member and the restoring member of the ratchet clamp shown in  FIG. 1  after a force is applied to the actuating member and drives the locking member to rotate; and 
           [0058]      FIG. 12  shows the positional relationship of the second ratchet member, the locking member, the first elastic element and the second shaft shown in  FIG. 11 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0059]      FIGS. 1 and 2  show a ratchet clamp having a force relieving mechanism of the present invention in a preferred embodiment. A first clamp arm  101  and a second clamp arm  102  thereof are connected through a first shaft  100 , and are rotatable about the first shaft  100  to control the closing or opening of a first clamp tip portion  11  and a second clamp tip portion  12 . In particular, when the user applies forces to the first clamp arm  101  and the second clamp arm  102  to make them close in to each other (i.e. the first clamp arm  101  and the second clamp arm move toward each other), the first clamp tip portion  11  and the second clamp tip portion  12  also close in to each other, thereby clamping the object such as a workpiece; when the user applied forces to the first clamp arm  101  and the second clamp arm  102  to make them away from each other (i.e. the first clamp arm  101  and the second clamp arm  102  moves away from each other), the first clamp tip portion  11  and the second clamp tip portion  12  also moves away from each other, thereby releasing the workpiece. 
         [0060]    A force relieving mechanism is arranged between the first clamp arm  101  and the second clamp arm  102 , used for at least partly releasing the clamping force applied by the ratchet clamp to the workpiece when the ratchet clamp releases the workpiece. The force relieving mechanism includes a first ratchet member  110 , a second ratchet member  120 , a locking member  300 , a connecting member  400 , an actuating member  500  and a restoring member, and  FIG. 3  shows the exploded structural view of them. 
         [0061]    One end of the first ratchet member  110  is fixedly connected to the first clamp arm  101 , and it is enabled to be more reliably fixedly connected to the first clamp arm  101  by an embedded member  111 ; the other end thereof is pointing toward the second clamp arm  102 . A first set of ratchets are distributed on the side part of the first ratchet member  110  away from the first shaft  100 . 
         [0062]    An elongated second hole  121  is provided at one end of the second ratchet member  120 . In the present embodiment, the second hole  121  is an open hole having an opening facing the second clamp arm  102 . In other embodiments, the second hole  121  may also be a closed hole. A second shaft  200  arranged on the second clamp arm  102  longitudinally passing through the second hole  121 . The extending direction of the second shaft  200  is the same as the first shaft  100 , and, in the second hole  121 , it is arranged perpendicular to the cross-section of the second hole  121  (perpendicular to the section of the first shaft, and the unspecified cross-sections in the present Specification all perpendicular to the section of the first shaft), thereby the second ratchet member  110  being rotatable about the second shaft  200 . The second hole  121  is transversely arranged, thereby allowing the first ratchet member  110  to drive the second ratchet member  120  to move transversely by the engaged first and second sets of ratchets. The “transversely” in the Specification refers to along the direction extending from the first clamp arm  101  to the second clamp arm  102  or along the direction extending from the second clamp arm  102  to the first clamp arm  101 . 
         [0063]    The other end of the second ratchet member  120  points toward the first clamp arm  101 . A second set of ratchets engaged with the first set of ratchets are distributed on the second ratchet member  120  at the side part toward the first shaft  100 , and, preferably, the second set of ratchets starts distribution from the end of the second ratchet member  120  pointing toward the first clamp arm  101 . 
         [0064]    The tooth surfaces of each ratchets of the first set of ratchets and the second set of ratchets are arranged such that the movement of the first clamp arm  101  and the second clamp arm  102  toward each other is allowed while that away from each other is obstructed. 
         [0065]    In the present embodiment, the locking member  300  includes a first column  301  and a second column  302  that are connected. The second column  302  is a cylinder, and the cross-section thereof is the first circle; the first column  301  is an incomplete cylinder, the cross-section thereof is an arch, the arc of the arch being a part of circumference of a circle which is a second circle. The arc length of the arch is larger than half of the circumference of the second circle. Preferably, the positional relationship of the first column  301  and the second column  302  is that the first circle and the second circle are arranged concentric on the cross-sections of them, as shown in  FIG. 5 . The locking member  300  may be integrally formed, and may also be formed by fixedly connecting the respectively formed first column  301  and second column  302 . 
         [0066]    The first column  301  is arranged passing through in the first hole  122  of the second ratchet member  120 , and is rotatable in the hole and is transversely movable when rotated to a certain angle. Preferably, the first hole  122  is arranged in the middle part of the second ratchet member  120 , and  FIG. 4  shows its cross-section. It can be seen in  FIG. 4  that the first hole  122  includes a circular first hole portion  1221  and an irregular elongated second hole portion  1222 ; the first hole portion  1221  is adjacent to the first clamp arm  101 , and the second hole portion  1222  is adjacent to the second clamp arm. A non-smoothly connected portion is provided between the two, which is a step  1223 . The shape of the first hole  122  is arranged such that the first column  301  is rotatable but not translationally movable in the first hole portion  1221 , and is translationally movable but not rotatable in the second hole portion  1223 . Specifically, the step  1223  engages against the curved sidewall portion of the first column  301  when the first column  301  is in the first position (for example, the position as shown in  FIG. 6 ) in the first hole portion  1221 , thereby limiting the first column  301  in the first hole portion  1221 , and the locking member  300  cannot move into the second hole portion  1222  from the first hole portion  1221 ; the step  1223  does not come into contact with the curved sidewall portion of the first column  301  when the first column  301  is in the second position (for example, the position as shown in  FIG. 8 ) in the first hole portion  1221 , thereby not limiting the movement of the first column  301 , and the locking member  300  can move into the second hole portion  1222  from the first hole portion  1221 . 
         [0067]    The connecting member  400  is a slide block, which includes two plate-shaped walls (the third wall and the fourth wall) in parallel arrangement for containing part of the second ratchet member  120 . A third column  410  and a barrier wall  420  are connected between the first wall and the fourth wall. Preferably, the third column  410  is a cylinder, which is perpendicular to the third wall and the fourth wall; the barrier wall  420  is a section of wall perpendicular to the third wall and the fourth wall. A second pair of holes  421 ,  422  for fitting with the second shaft  200  and a third pair of holes for fitting with the locking member  300  are provided on the third wall and the fourth wall, a hole  431  of the third pair of holes shown in  FIG. 3  and the other hole not shown, in which, the hole  421  and the hole  431  are on the third wall, and the hole  422  and the other hole of the third pair of holes are on the fourth wall. 
         [0068]    The second ratchet member  120  is sandwiched between the third wall and the fourth wall, and is slidable in relation to the connecting member  400 . Preferably, the second ratchet member  120  has a protruded portion on each of the two surfaces thereof toward the third wall and the fourth wall, such as the protruded portion  124 . These protruded portions protrude out from the above surfaces of the second ratchet member  120 , used for coming into contact with the second ratchet member  120 . They are of elongated shape, extending along the direction of the movement of the second ratchet member  120  in relation to the connecting member  400 , thereby reducing the friction to which the second ratchet member  120  is subjected during the movement thereof in relation to the connecting member  400 . 
         [0069]    One end of the actuating member  500  is used for being engaged with the locking member  300 . In the present embodiment, the end includes two plate-shaped walls (the first wall and the second wall) in parallel arrangement. A first pair of holes  531 ,  532  for fitting with the locking member  300  are provided on the first wall and the second wall, in which, the hole  531  is on the first wall and the hole  532  is on the second wall. The actuating member  500  also includes a portion extending along the direction from the above end away from the first shaft  100 . In the present embodiment, the portion is a trigger-like handle portion  510  used for the user to apply force thereto to switch the engaged/separated state between the first set of ratchets and the second set of ratchets. 
         [0070]    On the path of the handle part  510  swinging toward the first clamp arm  101 , a blocking part  123  is arranged on the second ratchet member  120 . In the present embodiment, the second ratchet member  120  is provided with two blocking parts, both of which are a portion protruding out of the second ratchet member  120  along the direction parallel to the first shaft. The blocking parts are used for limiting the degree of swing of the handle part  510  toward the first clamp arm  101 . The barrier wall  420  of the connecting member  400  is arranged on the path of swing of the handle part toward the second clamp arm  102 , used for limiting the degree of swing of the handle part  510  toward the second clamp arm  102 . 
         [0071]    The restoring member includes a first elastic element  610  (see  FIG. 6 ) and a second elastic element  620 . The first elastic element  610  is a compression spring, which is transversely arranged in the second hole portion  1222 , one end of it being engaged against (i.e. contacting and compressing) the first column  301  of the locking member  300  so that the first column  301  is held in the first hole portion  1221 . The second elastic element  620  is a torsion spring, the spring coil thereof being surroundingly arranged on the second shaft  200  and one end  621  thereof being engaged against the sidewall of the handle part  501  that is away from the second ratchets. Preferably, the sidewall is provided with a slot  540  fitting with the end part  621 ; the other end  622  engages against the inner wall of the second clamp arm  102 . Due to being subjected to the engagement against it by the end part  621  of the second elastic element  620 , the actuating member  500  keeps being engaged against the blocking part  123 . 
         [0072]    When assembling the second ratchet member  120 , the locking member  300 , the connecting member  400 , the actuating member  500  and the restoring member, the second ratchet member  120  is partly sandwiched between the third wall and the fourth wall of the connecting member  400 , and the third column  410  is arranged at the opening of the second hole  121  and thereby outside the second shaft (i.e. the side closer to the second clamp arm  102 ). The second ratchet member  120  and the connecting member  400  are partly sandwiched between the first wall and the second wall, and the locking member  300  is passed in turn through the hole  532 , the other hole of the third pair of holes, the first hole  122 , the hole  431  and the hole  531 , in which, the first column  301  passes through the hole  532 , the other hole of the third pair of holes and the first hole  122 , the second column  302  passes through the hole  431  and the hole  531 , and the locking member  300  cannot rotate in relation to the hole  532 , the other hole of the third pair of holes, the first hole  122 , the hole  431  and the hole  531 . In addition, the second shaft  200  is passed in turn through one spring coil of the second elastic element  620 , the hole  422 , the second hole  121 , the hole  421  and the other spring coil of the second elastic element  620 . 
         [0073]    The two sets of ratchets of a ratchet clamp clamping the workpiece keep being engaged with each other, as shown in  FIGS. 5, 6 . When separating the engaged two sets of ratchets of the ratchet clamp clamping the workpiece, the actuating member  500  applies in turn to the locking member  300  a first actuation and a second actuation, in which the process of the first actuation ( FIGS. 7-10 ) specifically is described as follows: 
         [0074]    When the user applies a force F toward the second clamp arm to the handle part  510 , as shown in  FIG. 7 , the actuating member  500  can conquer the friction and the restoring force of the second elastic element  620  and rotate, driving the locking member  300  and rotating it to the position as shown in  FIGS. 7, 8 . In the position, the first column  301  of the locking member  300  can pass over the step  1223  and enters the second hole portion  1222 . Since the clamped workpiece is simultaneously applying a pair of forces in opposite directions away from each other to the first clamp arm  101  and the second clamp arm  102 , the first clamp arm  101  and the second clamp arm  102  are enabled to have the tendency of moving away from each other, thereby the first clamp arm  101  driving the second ratchet member  120  by the first ratchet member  110 ; in relation to the second ratchet member  120 , the locking member  300  will conquer the restoring force of the first elastic element  610  of the restoring member and moves from the first hole portion  1221  of the first hole  122  to the second hole portion  1222 , as shown in  FIGS. 9, 10 . Thus, the distance between the first clamp tip portion  11  and the second clamp tip portion  12  will increase a little, releasing at least part of the clamping force applied to the clamped workpiece; the acting force between the engaged two sets of ratchets is correspondingly reduced. 
         [0075]    The process of the second actuation ( FIGS. 11, 12 ) is specifically described as follows: the user continues to apply a force F toward the second clamp arm to the handle part  510 . The actuating member  500  enables the second ratchet member  120  to rotate around the second shaft  200 , so that the second set of ratchets is detached from the first set of ratchets. Because the detachment is processed when the acting force between the two sets of ratchets is rather small, it is more smooth and causing less damage to the ratchets. After the detachment of the second set of ratchets from the first set of ratchets, the restoring force of the first elastic element  610  of the restoring member will cause the second ratchet member  120  to have a small displacement in the direction toward the second clamp arm  102 , so that the first column  301  of the locking member  300  is enabled to return to the first hole portion  1221 , as shown in  FIG. 12 . 
         [0076]    After the user withdraws the force F applied to the handle part  510 , the restoring force of the second elastic element  620  causes the handle part  510  to rotate in the direction toward the second set of ratchets and engage against the blocking part  123 . The handle part  510  drives the locking member  300  to rotate, causing the first column  301  of it to restore (the position as shown in  FIGS. 5, 6 ), where the step  1223  causes the two sets of ratchets to keep being engaged with each other by the locking member  300 . 
         [0077]    The foregoing described the preferred embodiments of the present invention. It should be understood that an ordinary person skilled in the art can make many modifications and variations according to the concept of the present invention without creative work. Therefore, any person skilled in the art can get any technical solution through logical analyses, deductions and limited experiments, which should fall in the protection scope defined by the claims.