Patent Abstract:
Pliers with adjustable jaw span have a first member ( 1 ) and a second member ( 2 ) which cooperate with each other. A long slot ( 13 ) is formed in the first member ( 1 ). The second member ( 2 ) is connected with the first member ( 1 ) by means of a pivot ( 3 ) passing through the long slot ( 13 ), and rotatable around the pivot ( 3 ) relative to the first member ( 1 ), while adjusting the span of the jaws by varying the position of the pivot ( 3 ) within the long slot ( 13 ). The edge of the long slot ( 13 ) is provided with ratchet teeth ( 14 ). The pivot ( 3 ) is engaged with the ratchet teeth ( 14 ) by a pawl ( 31 ), thus the pivot is movable within the long slot ( 13 ) in a first direction and immovable in a second direction which is opposite to the first direction. The pliers are convenient to operate because when the position of the pivot ( 3 ) is moved within the long slot ( 13 ), the user&#39;s operation is required only for the movement in one direction.

Full Description:
TECHNICAL FIELD OF THE INVENTION 
     The invention relates to hardware tools, and specifically to pliers, whose jaw span can be adjusted fast, such as water pump pliers. 
     BACKGROUND OF THE INVENTION 
     Conventional pliers (such as wire pliers) are formed in such a way that a pivot connects two members which include a jaw and a handle, respectively. In use, the jaw span (the space between two jaws for clamping objects) is adjustable only by operating the handles to rotate around the pivot, and the applicable range of the jaws is small. However, some types of pliers require the span adjustment of the jaws in use. For example, water pump pliers require the span adjustment of the jaws in accordance with the size of the pipe to be clamped. 
     To this end, pliers appear with a larger adjustable jaw span. Such technical scheme is also repeatedly recorded in patent documents, such as the Chinese Utility Model Patent being representative, entitled “Fast Locking Water Pump Pliers”, with the Authorized Publication Number being CN2790679Y and the Patent Number being ZL200520070493.2. The disclosed water pump pliers include a left member  101  and a right member  102 , as shown in  FIG. 16  and  FIG. 17 . The left member  101  is provided with a bar-shaped hole  113  in an open way. Both sides of the bar-shaped hole are provided with a rack  114 . The right member  102  is provided with a hinged hole  123  in an open way. A hollow bolt  103  tightly fits a blind nut  104  through the bar-shaped hole  113  and the hinged holes  123 . The hollow bolt  103  is axially provided with a hole  131  in the central part in an open way with a sliding part  105  arranged therein, and a gear  151  is arranged at the inner end of the sliding part. One end of a spring  106  is installed on the blind nut  104 , while the other end is installed on the sliding part  105 , so as to bias the sliding part in the predetermined working position. In the position, the gear  151  is engaged with the rack  114  of the left member  101 , so that the hollow bolt  103  cannot slide within the bar-shaped holes  113  of the left jaw. The jaws will be opened and closed when the left and right members  101 ,  102  are operated at this time so as to clamp and twist objects. Now, under the effect of the bias force of the spring  106 , the sliding part  105  is in an ejected state, and the button  107  at the external end thereof extends beyond the hollow bolt  103 . 
     If the span of the jaws needs to be adjusted, the button  107  is pressed only, so that the sliding part  105  overcomes the bias force of the spring  106  to slide inwardly, and the gear  151  at the inner end of the sliding part  105  is disengaged from the rack  114 . Now, the right member  102  can randomly slide in the bar-shaped holes  113  of the left member  101  along with the hollow bolt  103 . When it is adjusted to the required position, the button  107  is released again. The sliding part  105  resets under the effect of the bias force of the spring  106 . The gear  151  is re-engaged with the rack  114 . The left and right members  101 ,  102  are repositioned, and the water pump pliers can be in normal use again. 
     In the configuration, no matter whether the jaw span is adjusted to be larger or to be smaller, the button needs to be pressed so that the gear is disengaged from the rack, which is inconvenient in operation. Specifically, the size of the object to be clamped cannot be estimated very accurately when being clamped and since the force can be best applied to the object to be clamped and it is most convenient and comfortable to use for hands only when the jaws is in the parallel position, it requires repeated adjustment in the actual use. In particular when working in some small or narrow spaces, It is possible that we cannot see the object to be clamped with our eyes, so we can only determine the best jaw span by making continuous attempts. And the pliers with the above configuration can be adjusted only after being pressed by hands. In many positions, hands cannot reach into the position proximate to the object, which makes it more troublesome. Thus we need to take the pliers out for adjustment and then put it in for another try. If it is not suitable, we should take it out again for adjustment. It is rather inconvenient in use. 
     Furthermore, though the spring enables the gear at the other end of the sliding part to engage with the rack of the left member, the spring can only keep the gear in place where the gear can engage with the rack, but the spring cannot ensure a reliable engagement between the gear and the rack. In use, the gear slips from the rack easily, which leads to the failure of the adjustment of the jaw span. In addition, there are so many parts in the configuration which makes the configuration complex. 
     SUMMARY OF THE INVENTION 
     The objective of the invention is to provide pliers with adjustable jaw span, which is more convenient to operate, and do not have to operate a button for the adjustment in a direction. 
     Another objective of the invention is to provide pliers with adjustable jaw span, which enables the positioning and fitting of two members to be more stable and reliable. 
     A further objective of the invention is to provide pliers with adjustable jaw span, which is simple in structure. 
     To achieve the above objects, the invention provides pliers with adjustable jaw span, comprising a first member and a second member which cooperate with each other, a long slot is formed in the first member, and the second member is connected with the first member by means of a pivot passing through the long slot and rotatable around the pivot relative to the first member, the span of the jaws is adjustable by varying the position of the pivot in the long slot, wherein the edge of the long slot is provided with a number of ratchet teeth, and the pivot is engaged with the ratchet teeth by a pawl, thus the pivot is movable in a first direction, and immovable in a second direction which is opposite to the first direction within the long slot. 
     In the invention, the adjustment of jaw span is achieved by the structure in which the ratchet teeth and the pawl cooperate with each other. Since the mating of the ratchet teeth and the pawl is unidirectional, when the jaw span is adjusted it can be randomly adjusted in a direction, and it requires the user&#39;s operation only when it is adjusted in the other direction. In the actual operation, the jaw span can be adjusted to the maximum first, then the jaw of the first member is placed to the object, and then the second member is pushed towards the first direction, so that it can be adjusted to the optimal jaw span, without the user&#39;s operation for the disengagement of the ratchet teeth and the pawl. Therefore, the convenience and efficiency of the operation are greatly improved. 
     Preferably, the pawl can be disengaged from the ratchet teeth by an external force, so that the pivot can move in the second direction within the long slot. The pawl can axially move along the pivot so as to be disengaged from the ratchet teeth. Preferably, the external force can be achieved by pressing one end of the pivot so as to drive the pawl to axially move along the pivot. 
     In the alternative schemes, the pawl can circumferentially move along the pivot or move in the direction vertical to the pivot so as to be disengaged from the ratchet teeth. 
     Preferably, the pliers further include a return spring, which enables the pawl to automatically return to the state in which the pawl is engaged with the ratchet teeth after the external force is eliminated. Therefore, the return spring can keep the pawl in the position in which the pawl can be engaged with the racket. 
     Preferably, the pliers further include an offset spring, which can apply a torque force to the pawl so as to keep a stable engagement between the pawl and the ratchet teeth. Therefore, the offset spring can keep the pawl in a mating state in which the pawl is actually engaged with the ratchet teeth by the elastic force of the spring, so as to prevent the pawl from slipping from the ratchet teeth unexpectedly and ensure the efficient adjustment of the jaw span. 
     Preferably, the return spring and the offset spring are provided by a single coil spring. Preferably, the diameter of the coil spring reduces from one end to the other end gradually so as to form a disc shape when compressed by a force, which saves space, reduces the volume of the products, and facilitates its working in the small or narrow space. Preferably, the pivot is a shaft with different diameters, and the coil spring is installed on the shaft section with a smaller diameter in the shaft with different diameters. 
     Preferably, the pawl is integrated with the pivot, with a simple structure. 
     In a specific application, the pliers are a water pump pliers. 
     Other features and advantages of the invention can be fully understood through the detailed description of the embodiments of the invention with reference to the accompanying drawings hereinafter, in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows an assembly relationship graph of an embodiment of the pliers according to the invention, and the pliers are a water pump pliers in the embodiment; 
         FIG. 2  is a schematic view showing that the jaws of the water pump pliers in the embodiments of the invention is in a closed state; 
         FIG. 3  is a cross-sectional view along A-A direction in  FIG. 2 ; 
         FIG. 4  is a cross-sectional view along B-B direction in  FIG. 3 ; 
         FIG. 5  is a cross-sectional view along C-C direction in  FIG. 4 ; 
         FIGS. 6 and 7  are schematic views of the spring in the embodiments of the invention, in which  FIG. 7  is a top view of  FIG. 6 ; 
         FIGS. 8 and 9  are schematic views of the pivot assembly in the embodiments of the invention, in which  FIG. 9  is a left view of  FIG. 8 ; 
         FIGS. 10 and 11  are schematic views of the main body of the second member in the embodiments of the invention, in which  FIG. 10  is in the same state as the second member shown in  FIG. 2 , and  FIG. 11  is a rear view of  FIG. 10 ; 
         FIGS. 12 and 13  are schematic views of the first member in the embodiments of the invention, in which  FIG. 12  is in the same state as the first member shown in  FIG. 2 , and  FIG. 13  is a rear view of  FIG. 12 ; 
         FIG. 14  show a cross-sectional enlarged view along D-D direction in  FIG. 11 ; 
         FIG. 15  is a schematic view showing that the jaws of the water pump pliers in the embodiments of the invention is in an open state; 
         FIG. 16  is a structural schematic view of a water pump pliers in the prior art; and 
         FIG. 17  is a cross-sectional structural schematic view of the pivot part of the water pump pliers in  FIG. 16 . 
     
    
    
     The reference numbers in the drawings are as follows:  1 —a first member,  11 —jaw,  12 —handle,  13 —long slot,  14 —ratchet teeth;  2 —a second member,  21 —jaw,  22 —handle,  23   a ,  23   b —pivot holes,  24 —recess,  25 —main body,  26 —cover plate,  27   a ,  27   b ,  27   c ,  27   d —rivet holes,  28 —mounting hole;  3 —pivot member,  31 —pawl,  32 —mounting hole;  14 —spring, D 1 —the diameter of the larger end of the spring, D 2 —the diameter of the smaller end of the spring;  51 ,  52 —abutted surface;  6 —jaw. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The embodiments of the invention are further described with reference to the accompanying drawings of the specification so as to better understand the invention. In the shown embodiments, the pliers are a water pump pliers. As a matter of course, the invention can also be pliers of other types. 
     As shown in  FIG. 1 , the water pump pliers with adjustable jaw span according to the embodiments of the invention includes a first member  1  (referring to  FIG. 12  and  FIG. 13 ) and a second member  2  (referring to  FIG. 10  and  FIG. 11 ). The second member  2  can rotate by means of a pivot  3  relative to the first member  1 , so as to open and close the jaws. The first member  1  is provided with a long slot  13  in an open way. The edge of the long slot  13  is provided with ratchet teeth. The pivot  3  passes through the long slot  13 . The second member  2  is connected with the first member  1  by means of the pivot  3 . 
     In the shown embodiments, the second member  2  is provided with two pivot holes  23   a ,  23   b  located at both sides of the long slot  13 , respectively. The pivot holes  23   a ,  23   b  are used for installing the pivot  3 . The pivot  3  (referring to  FIG. 8  and  FIG. 9 ) is in an integral structure, both ends of which are located movably along the pivot within the two pivot holes  23   a ,  23   b , respectively, and the middle part of which is provided with a pawl  31  corresponding to the ratchet teeth  14 . The radial size (the radial size being the maximal size in the radial direction) of the pawl  31  is larger than the pivot holes  23   a ,  23   b . The second member  2  is provided with a recess  24  (referring to  FIG. 10 ,  FIG. 11  and  FIG. 14 ), with the size being capable of receiving the pawl  31 , which provides the movement space for the axial movement of the pivot  3 . 
     The pivot  3  which is integrated with the pawl  31  has a simple structure, which can move axially so as to adjust the span of the jaws  6 , while acting as a conventional pivot. Since the mating of the ratchet teeth  14  and the pawl  31  is unidirectional, it can be adjusted randomly in one direction without being obstructed when the jaws is adjusted, without requiring that the pawl  31  is disengaged from the ratchet teeth  14 ; while it is adjusted in the other direction, the user&#39;s operation is required so that the pawl  31  is disengaged from the ratchet teeth  14 . Therefore, it is convenient for users to operate. 
     Furthermore, while the pawl  31  mates with the ratchet teeth  14 , since the radial size of the pawl  31  is larger than the pivot holes  23   a ,  23   b , the pawl can be limited between the two pivot holes  23   a ,  23   b  so as to prevent the pivot  3  from falling off, thereby ensuring that the pivot  3  is assembled with the first member  1  and the second member  2 . 
     A coil spring  4  (referring to  FIG. 6  and  FIG. 7 ) is sleeved on the pivot  3 , both ends of which are connected to the second member  2  and the pivot  3 , respectively. On the one hand, the spring  4  acts as a return spring and provides an axial restoring force (referring to restoring pressure in the embodiment) so that the pawl  31  is located in the position where the pawl  31  is engaged with the ratchet teeth  14 , and the pawl leaves the position only when it is subjected to the external force in the axial direction of the pivot so as to be disengaged from the ratchet teeth  14 . On the other hand, the coil spring  4  acts as an offset spring, provides a torque force in the circumferential direction of the pivot, and stably keeps the pawl  31  in a state in which the pawl is engaged with the ratchet teeth  14 , thereby preventing the pawl  31  from falling off from the ratchet teeth  14  unexpectedly. 
     In the shown embodiments, the diameter of the spring reduces gradually from D 1  at one end to D 2  at the other end (referring to  FIG. 6 ). Seeing laterally, the profile of the spring has an isosceles trapezoid shape so that it has a disc shape while compressed, thus the height of the spring can be greatly reduced (which can be reduced to be as large as the diameter of the spring steel wire), thereby saving the installing space and enabling the structure to be compact. 
     The spring  4  in the shown embodiments is a single coil spring, which acts both as a return spring and an offset spring. It has a simple structure and simplifies the assembly relationship. It will be appreciated that the return spring and the offset spring can be two individual spring members in other embodiments. 
     In the shown embodiments of the invention, the pivot  3  (referring to  FIG. 8  and  FIG. 9 ) is a shaft with different diameters, including a shaft section with a larger diameter and a shaft section with a smaller diameter, thereby forming an axial step, which helps the positioning of the pawl  31  and limits the pivot  3  between the two pivot holes  23   a ,  23   b  so as to prevent it from falling off. The spring  4  is installed around the shaft section with the smaller diameter. 
     For facilitating the assembly, the second member  2  includes a main body  25  and a cover plate  26 , both of which are fixedly connected together in riveting or welding and other ways. The two pivot holes  23   a ,  23   b  are located in the main body  25  and the cover plate  26 , respectively. Furthermore, the main body  25  and the cover plate  26  are abutted with the first member  1  on the plane vertical to the axis of the pivot  3 . Such abutting results in abutted surfaces  51 ,  52  between the main body  25  and the cover plate  26  and the first member  1 , respectively, thereby avoiding the relative shaking of the first member  1  and the second member  2  so that they can fit each other accurately. 
     At least one end of the pivot  3  protrudes out of the pivot holes  23   a  or  23   b  so as to facilitate the pressing operation. After the pivot  3  is pressed, the pivot resists the restoring pressure of the spring  4  and axially moves so as to drive the pawl  31  to axially move, thus the pawl is disengaged from the ratchet teeth  14  and is received in the movement space provided by the recess  24 . Upon the pawl  31  is disengaged from the ratchet teeth  14 , the pivot  3  can move freely along the long slot  13  so that the second member  2  can move freely relative to the first member  1 . 
     The assembly process of the water pump pliers of the embodiment is described hereinafter. As shown in  FIG. 1 , the first member  1  is placed onto the main body  25  of the second member  2  with the long slot  13  corresponding to the pivot hole  23   a  in the main body  25  of the second member. And then, both ends of the spring  4  are installed on the main body  25  of the second member and the pivot  3  as required, respectively (as shown in the drawings, the main body of the second member  2  and the pivot  3  are provided with installing holes  28 ,  32 , respectively). The pawl  31  is made to be engaged with the ratchet teeth  14 . And then, the cover plate  26  is overlapped on the main body  25  of the second member  2  so that the main body  25  of the second member  2  and the cover plate  26  retain the first member  1  therebetween. And then, the cover plate  26  is fixed on the main body  25  of the second member  2  in a fixed connection (such as riveting, welding and so on), and the assembly is completed, referring to  FIG. 2  to  FIG. 5 , and  FIG. 15 . 
     According to the embodiment, in the natural state, both the bias force and the restoring force of the spring  4  keep the pawl  31  in place where the pawl is engaged with the ratchet teeth  14 . Namely, the restoring force of the spring  4  keeps the pawl  31  in place where the pawl is capable of being engaged with the ratchet teeth  14  (referring to  FIG. 3 ), while the bias torque of the spring  4  keeps the pawl  31  in a stable mating state in which the pawl is actually engaged with the ratchet teeth  14  (referring to  FIG. 5 ). 
     When the span of the jaws  6  is adjusted, if the span of the jaws is adjusted to be larger (being adjusted from the state as shown in  FIG. 2  to the state as shown in  FIG. 15 ), it is required that the pivot  3  is pressed axially (pressing towards the right, as shown in  FIG. 3 ), the pressure of the spring  4  is overcome so that the pawl  31  is disengaged from the ratchet teeth  14 , then the second member  2  is slid downwardly relative to the first member  1  to complete the adjustment. After it is adjusted in place, the pivot  3  is released from pressing, and the pivot  3  resets to the state in which the pawl  31  and the ratchet teeth  14  are engaged under the effect of the spring  4 . At this moment, the pipe fittings and other work pieces can be clamped with the jaws  6 . If the jaws is adjusted to be smaller (being adjusted from the state as shown in  FIG. 15  to the state as shown in  FIG. 2 ), it is not required that the pivot  3  is pressed axially, instead, the second member  2  is slid upwardly relative to the first member  1  directly, and the adjustment is achieved. During the adjusting process, the pawl  31  slides up and over the ratchet teeth  14  one by one, and makes a sound of click . . . click . . . click. After it is adjusted in place, the pawl  31  is engaged with the ratchet teeth  14 . As a matter of course, when the jaw span is adjusted to be smaller, the pivot  3  can also be pressed axially (pressing towards the right, as shown in  FIG. 3 ), the pressure of the spring  4  is overcome so that the pawl  31  is disengaged from the ratchet teeth  14 , then the second member  2  is slid upwardly relative to the first member  1 , to complete the adjustment. 
     In the actual use, the jaw span is adjusted to the maximum first, then the jaw  11  of the first member  1  is placed on the object to be clamped, the handle  22  of the second member  2  is pushed directly, and an unidirectional and rapid adjustment can be carried out. It can be adjusted into the optimal position with a single attempt, which saves time and facilitates operation. 
     The preferable embodiments of the invention are described in detail with reference to the accompanying drawings previously. It should be appreciated that the skilled in the art can conceive many flexible embodiments without departing from the spirit of the invention. 
     For example, though in the shown embodiments, the pawl  31  is driven to axially move along the pivot by pressing the pivot  3  so that the pawl is disengaged from the ratchet teeth  14 , in other alternative manners, it is also contemplated that the pawl  31  circumferentially rotates along the pivot or moves in the plane vertical to the axis of the pivot  3  so that the pawl is disengaged from the ratchet teeth  14 . 
     Although in the shown embodiments, there is only one pawl  31 , it can be appreciated that there can be a plurality of pawls  31 , which are circumferentially arranged on the pivot  3 . A plurality of pawls  31  are provided, which can mate with several ratchet teeth  14  at the same time, transferring a greater force and strengthening the stability of the engagement. Furthermore, if one tooth of the ratchet teeth  14  is damaged, it can still be used continuously. In addition, in the installing process, it is unnecessary to pay special attention to the circumferential position of the pivot  3 . It is only required that the pawl  31  should be capable of mating with the ratchet teeth  14 . 
     Therefore, the scope of protection of the invention should be based on the appended claims hereinafter.

Technology Classification (CPC): 1