Abstract:
A ratchet wrench includes a wrench body, a driving ratchet, a change-gear set, a retaining lid and a positioning rod. The driving ratchet is configured to removably engage with a tool part. In virtue of the cooperation between the change-gear set and the positioning rod, when the wrench body is turned toward a predetermined direction of the tool part, the driving ratchet can rotate in an increased speed, thereby improving the efficiency of operating the tool part.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates to ratchet wrenches, and more particularly to a ratchet wrench having a change-gear set and a positioning rod that, when cooperating, drive a tool part in an increased speed. 
     2. Description of Related Art 
     For screwing a threaded part (e.g. a threaded bolt or a nut) to tight or loose, it is common to use an open-end wrench or a box wrench. However, for operation performed in spatially limited environments, using such a basic wrench can consume considerable time as the user has to repeatedly engage the wrench with the workpiece, rotate the wrench and remove the wrench from the workpiece. For improving the basic wrenches, ratchet wrenches have been developed to eliminate the need of repeated engagement and disengagement between the wrench and the workpiece. More particularly, a ratchet wrench uses a unidirectionally drivable ratchet so that it drives the workpiece when operated in one direction and runs idly without driving the workpiece when operated in the other direction, thereby simplifying and speeding up the overall operation. 
     Nevertheless, it is clear that in the operation of a conventional ratchet wrench the idle running in the non-driving direction is still a waste, so there is a room for improving the operational efficiency of the conventional ratchet wrenches. 
     In addition, Taiwan Patent No. M427237, titled “ROTATIONAL MECHANISM FOR HAND TOOL”, discloses another wrench that has a turntable, a driving head and an accelerating wheel set positioned therebetween, so that when the turntable drives the driving head through the accelerating wheel set, the wrench can drive a workpiece in an increased speed. However, operation of such an existing wrench requiring a user to use his/her one hand to hold the turntable and use his/her the other hand to operate the same components is inconvenient and difficult to perform in confined operational space (e.g. in a vehicle&#39;s engine room). 
     SUMMARY OF THE INVENTION 
     As stated previously, the existing ratchet wrenches are not perfect for either lacking a design for accelerated operation or having a speed-changing mechanism that is structurally complicated and difficult to manufacture, fabricate and maintain. In view of the shortcomings, the objective of the present invention is to propose a ratchet wrench that uniquely uses a change-gear set and a positioning rod to drive a tool part in an increased speed. 
     The present invention provides a ratchet wrench that primarily comprises: 
     a wrench body, having a head portion and a shank, the head portion containing a ratchet socket that forms a first opening and a second opening at two reverse sides of the head portion connected by a channel; 
     a driving ratchet, having a wheel portion received in the ratchet socket and a connecting portion jutting out of the head portion through the first opening; 
     a change-gear set, having a passive gear mounted on an axle center of the wheel portion, a toothed periphery circling the channel, and a toothed driving ring deposited at the second opening, wherein the toothed driving ring has outer and inner peripheries thereof formed with outer teeth and inner teeth, respectively, and the outer teeth are configured to match the toothed periphery, while the inner teeth are configured to engage with the passive gear; 
     a retaining lid, rotatably covering the second opening, having a positioning recess for receiving the toothed driving ring, and having a positioning hole; and 
     a positioning rod, being movably received in the positioning hole. 
     In operation, by using the positioning rod engaging with the positioning hole, the retaining lid is held still when the wrench body is rotated in a predetermined direction of the tool part, so relative rotation takes place between the retaining lid and the head portion, causing the toothed periphery to drive the toothed driving ring to rotate in the positioning recess, thereby driving the passive gear and the driving ratchet to rotate in the predetermined direction, while the speed-changing function of the change-gear set can speed up the driven rotation of the tool part. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention as well as a preferred mode of use, further objectives and advantages thereof will be best understood by reference to the following detailed description of illustrative embodiments when read in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a perspective view of a ratchet wrench according to the present invention; 
         FIG. 2  is an exploded view of the ratchet wrench; 
         FIG. 3  is another exploded view of the ratchet wrench taken from a different viewpoint; 
         FIG. 4  is partial plane view of the ratchet wrench; 
         FIG. 5  shows a positioning rod combined with the ratchet wrench; and 
         FIG. 6  and  FIG. 7  illustrate operation of a direction controller of the ratchet wrench 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Please refer to  FIG. 1  through  FIG. 4  for one embodiment of the present invention. As depicted, a ratchet wrench is composed of a wrench body  10 , a driving ratchet  20 , a direction controller  30 , a change-gear set  40 , a retaining lid  50  and a positioning rod  60 , which will be described in detail below. 
     The wrench body  10  has a head portion  11  and a shank  12 . The head portion  11  contains a ratchet socket  13  and the ratchet socket  13  further includes a switching bay  14 . The ratchet socket  13  forms a first opening  15  and a second opening  16  at two reverse sides of the head portion  11 , respectively. The first opening  15  is covered by a cover  151  that is fixed at the first opening  15  through a C ring  152 . The cover  151  is formed with an operating hole  153 . 
     The driving ratchet  20  has a wheel portion  21  received in the ratchet socket  13  and a connecting portion  22  that is jutting out of the head portion  11  through the operating hole  153  for engaging a tool part, such as a socket. 
     The direction controller  30  is installed in the switching bay  14  for being operated to set the driving ratchet  20  for performing unidirectional rotation with respect to the head portion  11 . 
     The change-gear set  40  has a passive gear  41 , a toothed periphery  42  and a toothed driving ring  43 . 
     The passive gear  41  is mounted on the axle center of the wheel portion  21  and fixedly combined with the wheel portion  21 . 
     The toothed periphery  42  circles the channel. The toothed driving ring  43  is deposited around the channel. The toothed driving ring  43  has outer and inner peripheries thereof formed with outer teeth  431  and inner teeth  432 , respectively. The outer teeth  431  are configured to match the toothed periphery  42 , while the inner teeth  432  are configured to engage with the passive gear  41 . 
     The retaining lid  50  rotatably covers the second opening  16 . In one embodiment, a stepped groove  161  is formed at a periphery of the second opening  16  for a C ring  162  to engage therewith so that the retaining lid  50  is rotatably held at the second opening  16 . The retaining lid  50  further has its inner side formed with a positioning recess  51  for receiving the toothed driving ring  43 . In addition, the retaining lid  50  is formed with a positioning hole  52 . The positioning recess  51  is eccentrically formed on the retaining lid  50 , and the positioning recess  51  has an open surface  511  facing the toothed periphery  42 , for accommodating the engaged toothed driving ring  43  and the toothed periphery  42 . 
     The positioning rod  60  is an L-shaped rod having a hexagonal cross-sectional profile, and the positioning hole  52  is a hexagonal hole, so that one end of the positioning rod  60  can be fittingly received in the positioning hole  52  in a removable manner to prevent the toothed driving ring  43  from rotating. 
     Therein, a number of teeth formed on the toothed periphery  42  is greater than a number of the outer teeth  431  that is greater than a number of the inner teeth  432  that is greater than a number of teeth formed on the passive gear  41 . 
     After illustrating the configuration of the certain embodiment of the present invention, the following description will be directed to the operational principles of the present invention. 
     As shown in  FIG. 5 , when a user rotates the wrench body  10  in one direction and hold the positioning rod  60  still, since the retaining lid  50  is held from rotating by the positioning rod  60 , a relative rotation takes place between the head portion  11  of the wrench body  10  and the retaining lid  50 . Thereby, the toothed periphery  42  drives the toothed driving ring  43  to rotate in the positioning recess  51  and in turn drives the passive gear  41  and the driving ratchet  20 . Because the outer teeth  431  engage with the toothed periphery  42 , the toothed driving ring  43  is driven to rotate with the toothed periphery  42  (e.g. in the anti-clockwise direction as shown in  FIG. 6 ). The inner teeth  432  engaging with the passive gear  41  also make the passive gear  41  to rotate with the toothed driving ring  43  (in the anti-clockwise direction). Then the driving ratchet  20  drives the tool part to rotate in the direction where the wrench body  10  is driven by the user. 
     Working with the speed-changing function of the change-gear set  40 , the gear ratios between the toothed periphery  42 , the set of the outer teeth  431 , the set of the inner teeth  432  and the passive gear  41  designed for rotational acceleration can further speed up the rotation of the tool part. 
     On the other hand, as shown in  FIG. 7 , when it is desired to operate the wrench body  10  in the clockwise direction, the direction controller  30  is first operated to switch the unidirectional rotation of the driving ratchet  20 . Then the positioning rod  60  can be similarly held still to fix the retaining lid  50 , so the user&#39;s rotating the wrench body  10  in the clockwise direction will drive the driving ratchet  20  and make the tool part to rotate in the clockwise direction. 
     As described previously, the present invention implements a simple structure where the passive gear  41  is fixedly mounted on the wheel portion  21  and the toothed periphery  42  is essentially a part of the periphery defining the channel. As compared with the existing ratchet wrenches featuring for speed change, the present invention significantly reduces the number of components, and as compared with normal ratchet wrenches, only the toothed driving ring  43  and the retaining lid  50  are added. Thus, the disclosed wrench is easy to manufacture, fabricate and maintain. 
     The present invention has been described with reference to the preferred embodiments and it is understood that the embodiments are not intended to limit the scope of the present invention. Moreover, as the contents disclosed herein should be readily understood and can be implemented by a person skilled in the art, all equivalent changes or modifications which do not depart from the concept of the present invention should be encompassed by the appended claims.