Patent Publication Number: US-9833883-B2

Title: Bi-directional screwdriver

Description:
FIELD OF THE INVENTION 
     The present invention relates to a hand tool, and more particularly relates to a bi-directional screwdriver. 
     DESCRIPTION OF THE PRIOR ART 
     In use of hand tools such as common screwdrivers, there is certain limitation to the motion of the hand in the rotation direction, which cannot be along one direction consecutively. In such tools, the rotation shaft and the main shaft of the handle are coaxial, and usually the following is the case when the tools are in use: firstly, rotating the handle with hand in a desired direction (for example, tightening or loosening a screw), then the hand turns in reverse direction so that the tools can be re-positioned for another cycle. In the second part of the above cycle, the reverse turning of the hand can be that after the hand releasing the handle is gripped again, or also a single direction mechanism such as a ratchet mechanism is arranged in the tool, so that the main shaft remains stationary when the handle is rotated in reverse direction, or the tool is detached from the screw and then inserted into the screw again. However, anyway, the reverse turning of the hand will never bring effective motions of a fastener, therefore is considered as a wasted motion. 
     U.S. Pat. No. 5,931,062 has disclosed a mechanical rectifier, comprising a shaft and two driving elements mounted on the shaft, each having a one-way clutch interposed between it and the shaft, with the clutches oriented in the same way on the shaft so that the shaft is always entrained in only one direction of rotation when either one of the two driving elements is rotated in that direction, and the shaft is overrun by a driving element that is rotated in the opposite direction; also comprises a reversing mechanism coupling the two driving elements together and forcing them to always rotate in opposite directions so that one driving element entrains the shaft and the other driving element overruns the shaft, thus causing the shaft to always turn in only one direction, regardless of the direction of rotation of the driving elements. Thus, the rotation of the rotation device (such as a handle) in either direction is converted into unidirectional rotation of the shaft. The mechanical rectifier can efficiently utilize the rotation of the rotation device in any directions, that is, no matter if the handle rotates in clockwise direction or in counterclockwise direction, the main shaft always rotates in one direction, thereby the motion efficiency of the handle is greatly improved and the operation time is saved. 
     However, the reversing mechanism of this invention can only make the main shaft rotate in one direction. In order to adapt to the need of the main shaft rotatable in both directions (such as, tightening or loosening a fastener when implemented as a screwdriver), the handle of this invention have to be removable from the main shaft which is coaxial with the handle, and both ends of the main shaft (set as ends A and B) can be mounted with screwdrivers. Supposing end A of the shaft is used to tighten a fastener in the beginning, if the fastener needs to be loosened, the handle mounted at end B of the shaft has to be dismounted from the main shaft, and the handle is mounted at end A of the shaft and proper screwdriver bit is mounted at end B, and then the motion of loosening the fastener can be proceeded. And if the fastener to be loosened is of the same model as the original fastener being tightened, the screwdriver bit has to be removed from end A and mounted to end B before the handle changes position. Thus it can be seen that the mechanical rectifier of this invention has inconveniences in changing the direction of the main shaft. To multi-function screwdrivers with changeable driver bits, changing driver bits at both ends of the main shaft is even more troublesome. In addition, it must be ensured that the handle can be taken off from the main shaft readily, which means the integrity of the whole screwdriver cannot be guaranteed, and parts can easily be missing. 
     Further, this kind of mechanical structure has relatively low rotation speed, and it is desirable to provide a direction-changeable screwdriver with higher operational efficiency. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to provide a bi-directional screwdriver, comprising a reversing means with pawls, which is convenient for processing. 
     Another object of the present invention is to provide a bi-directional screwdriver, which has a speed increasing mechanism allowing a bi-directional screwdriver to rotate in an increased speed. 
     Another object of the present invention is to provide a bi-directional screwdriver, which, based on the speed increasing mechanism, also has a speed increasing switch allowing a bi-directional screwdriver be selected to use speed increasing or not to use speed increasing. 
     A bi-directional screw driver, comprising a handle, a main shaft, a gearing which comprises a driving gear, a driven gear, a transmission seat and an idle gear which is mounted on an idle gear axle on the transmission seat and is fitted between the driving gear and the driven gear for transferring motion, wherein the handle rotates the driving gear, and a grip ring is securely disposed outside the idle gear axle, and when the grip ring is rotating relative to the handle, the driving gear is rotated and rotates the driven gear in a reverse direction through the idle gear, wherein the driving gear also has a first inside ratchet surface, and the driven gear also has a second inside ratchet surface; and also comprising a reversing means which includes a reversing member, a first pawl member and a second pawl member, and a reversing switch, wherein the driving gear, the driven gear and the transmission seat are all sleeved on the reversing member, the reversing member is sleeved on and main shaft, being able to rotate the main shaft; wherein the first pawl member has a first pawl and a second pawl selectively engaging with the first ratchet surface, wherein the first pawl slides over the first ratchet surface in a first direction, and engages with the first ratchet surface for transmission in a second direction, the second pawl engages with the first ratchet surface for transmission in the first direction, and slides over the first ratchet surface in the second direction; the second pawl member has a third pawl and a fourth pawl selectively engaging with the second ratchet surface, wherein the third pawl slides over the first ratchet surface in the first direction, and engages with the first ratchet surface for transmission in the second direction, the fourth pawl engages with the first ratchet surface for transmission in the first direction, and slides over the first ratchet surface in the second direction; the reversing switch can set the first pawl member and the second pawl member in a first state and a second state, in the first state, the first pawl and the third pawl respectively engage with the first ratchet surface and the second ratchet surface at the same time; in the second state, the second pawl and the fourth pawl respectively engage with the first ratchet surface and the second ratchet surface at the same time; the first direction is a clockwise or counterclockwise direction, the second direction is a reverse direction of the first direction. 
     Further, the first pawl member and/or the second pawl member are fan-shaped, wherein the first pawl and the second pawl, the third pawl and the fourth pawl are fan-shaped toothed surfaces. 
     Further, the reversing switch comprises a central shaft, a first ball plug and a second ball plug, the central shaft is provided through inside the reversing member, the first ball plug and the second ball plug are secured to the central shaft successively, the first ball plug and the second ball plug engage with recesses on the fan-shaped bottom surfaces of the first pawl member and the second pawl member respectively. 
     Further, an elastic member is fitted between the first and the second ball plug and the central shaft. 
     Further, the first pawl member and the second pawl member are mounted on a secondary shaft which is parallel to the reversing member. 
     Further, the front end of the central shaft is provided with a helical sliding slot, the bi-directional screwdriver also comprises a head cover sleeved on the front end of the reversing member, a guide way parallel to the axis of the main shaft is provided on the head cover, a push button assembly is provided in the guide way and is slidable along the guide way and the sliding slot for controlling the position of the central shaft so as to set a rotation direction of the main shaft. 
     The bi-directional screwdriver of the present invention also comprises a speed increasing mechanism comprising a gear shaft arranged at the tail part of the driving gear and a speed increasing planetary gear mechanism which comprises a gear ring securely connected to the grip ring, three planetary gear engaging between the gear shaft and the gear ring, and a planetary carrier sleeve connected to the handle; when the gear ring is rotating relative to the handle, the planetary carrier sleeve rotates the planetary gear which rotates the gear shaft in increased speed, the gear shaft inputs the speeded-up rotation to the driving gear. 
     Further, the gear shaft has thereon a first gear surface engaging with the planetary gear, a smooth surface and a second gear surface, an internal gear is provide on the inner circumferential surface of the planetary carrier sleeve arranged able to slide between an engaging position and a disengaged position on the gear shaft, the planetary carrier sleeve engages with the planetary gear when the planetary carrier sleeve slides to the engaging position, the internal gear is located on the smooth surface of the gear shaft at the moment; the planetary carrier sleeve is disengaged from the planetary gear when the planetary carrier sleeve slides to the disengaged position, the internal gear is located at the second gear surface and engages therewith. 
     The bi-directional screwdriver of the present invention also comprises a speed increasing switch for driving the planetary carrier sleeve to slide between the engaging position and the disengaged position. 
     Further, an outer sleeve is also provided outside the planetary carrier sleeve, the handle is sleeved on the outside of the outer sleeve. 
     A further description will be made as to the conception, detailed structure, and expected technical effects of the present invention with reference to the accompanying drawings to make the objects, features, and advantages of the present invention fully understandable. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a main view of the first embodiment of the present invention in the first operating state; 
         FIG. 2  is a sectional view of the embodiment shown in Figure, taken along line E-E; 
         FIG. 3  is a main view of the first embodiment of the present invention in the second operating state; 
         FIG. 4  is a schematic view of the transmission mechanism of the first embodiment of the present invention; 
         FIG. 5  is an exploded schematic view of the transmission mechanism shown in  FIG. 4 , in which the gearing is detached from the reversing means; 
         FIG. 6  is an exploded schematic view of the gearing shown in  FIG. 5 ; 
         FIG. 7  is an exploded schematic view of the reversing means shown in  FIG. 5 ; 
         FIG. 8A  is a sectional view taken along line A-A in  FIG. 1 ; 
         FIG. 8B  is a sectional view taken along line B-B in  FIG. 1 ; 
         FIG. 8C  is a partial schematic view of simplified components shown in  FIG. 2 , at a cross-section taken along line C-C; 
         FIG. 8D  is a partial schematic view of simplified components shown in  FIG. 2 , at a cross-section taken along line D-D; 
         FIG. 9A  a sectional view taken along line A′-A′ in  FIG. 3 ; 
         FIG. 9B  is a partial schematic view of simplified components shown in  FIG. 3 , at a cross-section taken along line C-C; 
         FIG. 9C  is a partial schematic view of simplified components shown in  FIG. 3 , at a cross-section taken along line D-D; 
         FIG. 10  is a partial schematic view of the engagement relationship between the main shaft and the driving gear or the driven gear in the first embodiment of the present invention; 
         FIG. 11A  is a sectional view of a reversing means corresponding to the driven gear in the first operating state of the second embodiment of the present invention, the section position referred to as positions at C-C in  FIGS. 2, 3 ; 
         FIG. 11B  is a sectional view of a reversing means corresponding to the driving gear in the first operating state of the second embodiment of the present invention, the section position referred to as positions at D-D in  FIGS. 2, 3 ; 
         FIG. 12  A is a sectional view of a reversing means corresponding to the driven gear in the second operating state of the second embodiment of the present invention, the section position referred to as positions at C-C in  FIGS. 2, 3 ; 
         FIG. 12B  is a sectional view of a reversing means corresponding to the driving gear in the second operating state of the second embodiment of the present invention, the section position referred to as positions at D-D in  FIGS. 2, 3 ; 
         FIG. 13A  is a sectional view of a reversing means corresponding to the driven gear in the first operating state of the third embodiment of the present invention, the section position referred to as positions at C-C in  FIGS. 2, 3 ; 
         FIG. 13B  is a sectional view of a reversing means corresponding to the driving gear in the first operating state of the third embodiment of the present invention, the section position referred to as positions at D-D in  FIGS. 2, 3 ; 
         FIG. 14A  is a sectional view of a reversing means corresponding to the driven gear in the second operating state of the third embodiment of the present invention, the section position referred to as positions at C-C in  FIGS. 2, 3 ; 
         FIG. 14B  is a sectional view of a reversing means corresponding to the driving gear in the second operating state of the third embodiment of the present invention, the section position referred to as positions at D-D in  FIGS. 2, 3 ; 
         FIG. 15  is a partial sectional view of the fourth embodiment of the present invention, showing structural relationship of its main shaft, stopping block, reversing member and main gear; 
         FIG. 16  is a partial sectional view of the fifth embodiment of the present invention, showing structural relationship of its main shaft, stopping block, reversing member and main gear; 
         FIG. 17A  is a side view of the sixth embodiment of the present invention, in which the push button in the rear; 
         FIG. 17B  is a side sectional view of the sixth embodiment of the present invention, in which the push button in the rear; 
         FIG. 17C  is a transverse sectional view of point A of the sixth embodiment of the present invention, in which the push button in the rear; 
         FIG. 17D  is a transverse sectional view of point B of the sixth embodiment of the present invention, in which the push button in the rear; 
         FIG. 17E  is a transverse sectional view of point C of the sixth embodiment of the present invention, in which the push button in the rear; 
         FIG. 18A  is a side view of the sixth embodiment of the present invention, in which the push button in the front; 
         FIG. 18B  is a side sectional view of the sixth embodiment of the present invention, in which the push button in the front; 
         FIG. 18C  is a transverse sectional view of point A of the sixth embodiment of the present invention, in which the push button in the front; 
         FIG. 18D  is a transverse sectional view of point B of the sixth embodiment of the present invention, in which the push button in the front; 
         FIG. 18E  is a transverse sectional view of point C of the sixth embodiment of the present invention, in which the push button in the front; 
         FIG. 19  is an exploded view of the sixth embodiment of the present invention; 
         FIG. 20  is an exploded side view of the sixth embodiment, in which the grip ring and the handle is removed; 
         FIG. 21  is an exploded perspective view of the sixth embodiment, in which the grip ring and the handle is removed; 
         FIG. 22  is an exploded view of the reversing means and gearing of the sixth embodiment of the present invention; 
         FIG. 23  is a schematic view of the reversing means of the sixth embodiment of the present invention; 
         FIG. 24  is exploded view One of the reversing means of the sixth embodiment of the present invention; 
         FIG. 25  is exploded view Two of the reversing means of the sixth embodiment of the present invention; 
         FIG. 26  is a top view of the ratchet member in the reversing means of the sixth embodiment of the present invention; 
         FIG. 27  is a partial exploded view of the gearing of the present invention; 
         FIG. 28  is an exploded view of the speed increasing mechanism of the present invention; 
         FIG. 29  is a sectional view of the speed increasing mechanism of the present invention; and 
         FIG. 30  is a schematic view of the gear shaft of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiment One 
     Referring to  FIG. 1  and  FIG. 2 , in a preferred embodiment, the bi-directional mechanical converter is applied in a manually actuated screwdriver  100 , and bi-directional multiple speed of transmission is achieved in the screwdriver  100  through a transmission mechanism  120  shown in  FIG. 4 . The transmission mechanism  120  includes a gearing  130  and a reversing means  110  shown in  FIG. 4 , being able to realize the switching of the rotation direction of the main shaft.  FIG. 5  and  FIG. 6  show the structural and mounting relationship between the gearing  130  and the reversing means  110 . The ‘bi-directional multiple speed transmission’ or ‘bi-directional transmission’ are referred to in relation to the input, that is, the handle serves as a rotation mechanism, the input force of which can be in any direction of clockwise direction or counterclockwise direction and can be efficiently utilized, whereas the feature ‘direction-changeable’ of the present invention refers to that the output rotation direction of the main shaft can selectively be clockwise or counterclockwise as desired. The clockwise or counterclockwise direction that is referred to in the present description is defined as a rotation direction that is observed in the direction of from the driver bit to the handle along the shaft. 
     A full description of the structure, operation and principle of operation of the manually actuated screwdriver  100  in this embodiment is set forth as follows: 
     1 Overall Structure of Screwdriver  100   
     The screwdriver  100  includes a main shaft  105 , a transmission mechanism  120  and a rotation device. In this embodiment, the rotation device is a handle  121 , in which the torque inputted from the handle  121  in either directions (either of clockwise or counterclockwise) is transferred to the main shaft  105 , causing the main shaft  105  to output torque in a predetermined direction (one of clockwise and counterclockwise). The transmission mechanism  120  is mounted on the main shaft  105  for transferring the driving torque of the handle  121  to the mains shaft  105 . By means of the driver bit mounted on the main shaft  105 , screwdriver bits  101  of various models can be mounted for outputting torque. 
     When observed from the outside, the screwdriver  100  also includes a head cover  108  and a grip ring  113 . 
     The head cover  108  is securely coupled to the main shaft  105  through a pin  106 , so that the head cover  108  and the main shaft  105  rotate together. 
     The grip ring  113  and the handle  121  are provided for being gripped by two hands of an operator respectively, in which, the grip ring  113  is stationary when being gripped, and the handle  121  can rotate relative to the grip ring  113  in either directions (either of clockwise or counterclockwise). The stationary grip ring  113  is the basis of the rotation of each of the components in the screwdriver  100 . 
     2 Transmission Mechanism  120   
     As shown in  FIG. 4  and  FIG. 5 , the transmission mechanism  120  includes a gearing  130  and a reversing means  110  for realizing a direction-changeable bi-directional multiple speed transmission, in which the gearing  130  is sleeved on the outside of the reversing means  110  and the reversing means  110  is sleeved on the outside of the main shaft  105 . The reversing means  110  serves in two features: i) engaging with the gearing  130  to realize converting bi-directional input to single directional output (i.e. one-way clutch function), and, ii) switching the output direction (i.e. direction switching function). 
     2.1 Structure of Transmission Mechanism  130   
     As shown in  FIG. 6 , the transmission mechanism  130  includes four bevel gears and a transmission seat  114 . The four bevel gears include a driving gear  118 , a driven gear  111  and two idle gears  128  coupling the driving gear and the driven gear, in which the use of two idle gears allows a more balanced transmission, and the use of one idle gear is also feasible, which does not compromise the function of the present invention and is not limited thereby. The driving gear  118  and the handle  121  are coupled securely for transferring torque from the handle. 
     The driving gear  118 , transmission seat  114  and driven gear  111  are coaxially sleeved on the reversing member  115  of the reversing means  110  successively in clearance engagement, in which the reversing means  110  leads the driving gear and the driven gear to form a one-way clutch relationship, respectively, with the main shaft  105 , that is, in one direction, the driving gear rotates the main shaft and the other driven gear rotates idly; in the other direction, the driving gear and the driven gear are functionally interchanged, with the driven gear which was previously rotating idly causing the main shaft to rotate, and the driving gear now rotating idly relative to the main shaft. The detailed embodiment of the one-way clutch relationship will be described in the following chapter 2.2 and 2.3. 
       FIG. 8B  shows the connection relationships between the transmission seat  114 , the reversing member  115  and the grip ring  113 . The transmission seat is rotatable relative to the reversing member  115 . The transmission seat  114  is provided with two idle gear shafts  133  in radial direction for mounting the idle gears  128 . The idle gears  128  cause the driving gear  118  and the driven  111  to always be kept to rotate in opposite directions, that is, when the driving gear is rotating in clockwise direction, the driven gear is rotating in counterclockwise direction; on the contrary, when the driving gear is rotating in counterclockwise direction, the driven gear is rotating in clockwise direction. 
     The transmission seat  114  also includes threaded radial holes  132  used for securing the grip ring  113  which is securely coupled to the transmission seat  114  through screws  112 . In this embodiment, threaded holes  134  are also provided on the idle gear shaft  133  in the axial direction. For the structure to be compact, the threaded holes  134  can also be used for securing the grip ring  113 , meanwhile the grip ring  113  also functions to limit the axial displacement of the idle gears  128 . Naturally, the grip ring  113  of the present invention can also be securely coupled to the transmission seat  114  only through the threaded holes  132 , and at the same time an axial stopping block may be provided through the threaded holes  134 , or blocking members such as blocking rings be provided on the idle gear shaft  133 , for limiting the axial displacement of the idle gears  128 . 
     2.2 The Structure and Principle of the Switching Mechanism  110   
     As shown in  FIG. 5 , the reversing means  110  is sleeved on the main shaft  105 , and a transmission mechanism  130  is sleeved on the outside the reversing means. The reversing means  110  includes a reversing member  115  and two sets of roller pins  127 - 1  and  127 - 2 . The reversing member  115  is coaxially sleeved on the main shaft  105  in clearance engagement. Two sets of slots of dimension larger than the roller pins  127 - 1  and  127 - 2  are machined on the reversing member  115  for mounting the roller pins  127 - 1  and  127 - 2  and allowing the roller pins  127 - 1  and  127 - 2  to roll freely. The axes of the roller pins  127 - 1  and  127 - 2  are parallel to the axis of the main shaft  105 . Referring to  FIG. 2 , two sets of slots and roller pins  127 - 1  and  127 - 2  are positionally corresponding to the driving gear  118  and the driven gear  111  of the transmission mechanism  130  respectively, that is, the first set of slots and roller pins  127 - 2  engage with the inner circumferential surface  138  of the driving gear  118 , and the second set of slots and roller pins  127 - 1  engage with the inner circumferential surface  135  of the driven gear  111 . The inner circumferential surfaces  135  and  138  in this embodiment are circular cylindrical surface. 
     As shown in  FIG. 7  and  FIG. 10 , shaped surfaces  131  are provided on the main shaft  105  at positions corresponding to the slots and roller pins. In this embodiment, three shaped surfaces  131  are provided on the main shaft  105 , corresponding to three roller pins  127 - 1  or  127 - 2  in each set, and the roller pins  127 - 1  and  127 - 2  can roll on the shaped surfaces  131 . In practice, each shaped surface  131  has two sections of operating surface which engage with the inner circumferential surface  135  and the inner circumferential surface  138 , respectively, through the roller pins  127 - 1  and  127 - 2 . The operating surface of the shaped surfaces  131  can be circular cylindrical surface, elliptic cylindrical surface, parabolic surface or other curved surfaces, or plane surface, that is to say, the profile line of the transverse section of the shaped surfaces can be circular arc, elliptic arc, parabolic arc or other arcs, or direction line. A radial clearance is formed between the shaped surface  131  and the inner circumferential surface  138  or the inner circumferential surface  135  (referring to  FIG. 10 , where the engagement relationship between the main shaft  105  and the driving gear  118  or the driven gear  111  is shown), limiting the range of motion of the roller pins within it. As long as the dimension of the middle portion a of the radial clearance is larger than the diameter of the roller pins  127 - 1 ,  127 - 2  along the circumferential direction of the main shaft, and the dimensions of two end portions b, b′ are smaller than the diameter of the roller pins  127 - 1 ,  127 - 2  respectively, the roller pins can move between the two ends of the radial clearance when pushed by the reversing member  115 , and, at the engagement place of the roller pins with the shaped surface and the inner circumferential surface, self-lock condition is met, so that the object of the present invention can be achieved. The radial clearance does not have to be symmetrical, that is, b and b′ being not equal does not affect the object of the present invention. 
     In other embodiments, the number of the shaped surfaces can be one, two or more than three, all being able to achieve the object of the present invention, which is not limited by the present invention. Correspondingly, the number of the roller pins in each set can be one, two or more than three, or the number of the roller pins can even be smaller than or larger than the number of the shaped surfaces. For example, the reversing member  115  in this embodiment is provided with six slots in two sets thereon, for mounting the roller pins  127 - 1  and  127 - 2 . Even if some of the slots are not provided with roller pins therein, but as long as there is at least one roller pin in each set of slot, the object of the present invention can be achieved. 
     Above all, as long as the driving gear and the driven gear of the transmission mechanism  130  engage with the shaped surface through the roller pins respectively, the object of the present invention can be achieved and the present invention does not limit them. The roller pins of the present invention may also be replaced with other rolling members, such as roller balls, conical rollers, etc., and meanwhile, the shape of the corresponding shaped surface and the inner circumferential surface match with the shape of the rolling member, such as the shaped surface and the inner circumferential surface being arranged to be a loop surface or conical surface. Naturally, each shaped surface  131  can also be machined into two sections of operating surfaces, corresponding to two sets of roller pins  127 - 1  and  127 - 2  respectively, so as to achieve the object of the present invention as well. The diameters of the inner circumferential surface  135  and the inner circumferential surface  138  in this embodiment are the same, and if they are different, as long as roller pins of suitable diameters are selected to engage with the corresponding shaped surfaces, the object of the present invention can also be achieved. 
     The operating principles of the reversing means  110  serving as a one-way clutch and a direction switch in the two operating states are respectively illustrated with reference to the accompanying drawings of  FIG. 8A, 8C, 8D  and  FIG. 9A, 9B, 9C . The reversing means  110  in the Figures is simplified into a structure with a roller pin engaging with a shaped surface of one of the planes of the main shaft  105 . 
       FIG. 8C, 8D  are corresponding to the first operating state of this embodiment, in which the roller pins  127 - 1  and  127 - 2  are pushed toward the right side in the figures by the reversing element  115 . In  FIG. 8C , the roller pin  127 - 1  comes into contact with the inner circumferential surface  135  of the driven gear  111  and the shaped surface  131  simultaneously, and in  FIG. 8D , the roller pin  127 - 2  comes into contact with the inner circumferential surface  138  of the driving gear  118  and the shaped surface  131  simultaneously. 
     When the driving gear  118  is rotating in clockwise direction, the inner circumferential surface  138  entrains the roller pin  127 - 2  to rotate in clockwise direction, and the roller pin  127 - 2  is subject to a rightward friction on the shaped surface  131 , that is, both of the forces applied to the roller pin  127 - 2  by the inner circumferential surface  138  and the shaped surface  131  are rightward, such that the roller pin  127 - 2  is clamped by the wedge angle formed between the shaped surface  131  and the inner circumferential surface  138 , rotating the main shaft  105  in clockwise direction. At this point, the driven gear  111  is rotating in counterclockwise direction, and the roller pin  127 - 1  engaging with the inner circumferential surface  135  is also rotating in counterclockwise direction, which is subject to a leftward friction on the shaped surface  131 , that is, both of the forces applied to the roller pin  127 - 1  by the inner circumferential surface  135  and the shaped surface  131  are leftward; because of the dimension of the left side radial clearance of the roller pin being greater than the diameter of the roller pin, the roller pin  127 - 1  is caused to be in loose state, and, correspondingly, the driven gear  111  rotates idly in relation to the main shaft  105 . 
     When the driving gear  118  is rotating in counterclockwise direction, the inner circumferential surface  138  rotates the corresponding roller pin  127 - 2  in counterclockwise direction, and the roller pin is subject to a leftward friction on the shaped surface  131 , that is, both of the forces applied to the roller pin  127 - 2  by the inner circumferential surface  138  and the shaped surface  131  are leftward; because of the dimension of the left side radial clearance of the roller pin  127 - 2  being greater than the diameter of the roller pin, the roller pin  127 - 2  is caused to be in loose state, therefore, the driven gear  111  is rotating idly in relation to the main shaft  105  at this point. However, because of the existence of the idle gear  128 , the driven gear  111  is caused to be rotating in clockwise direction. the inner circumferential surface  135  rotates the corresponding roller pin  127 - 1  in clockwise direction, and the roller pin  127 - 1  is subject to a rightward friction on the shaped surface  131 , that is, both of the forces applied to the roller pin  127 - 1  by the inner circumferential surface  135  and the shaped surface  131  are rightward, such that the roller pin  127 - 1  is clamped by the wedge angle formed between the shaped surface  131  and the inner circumferential surface  135 , rotating the main shaft  105  in clockwise direction. 
     Accordingly, no matter if the handle rotates the driving gear in clockwise direction or counterclockwise direction, the main shaft  105  rotates in clockwise direction in the first operating state. 
       FIG. 9B, 9C  corresponds to the second operating state of this embodiment, in which the roller  127 - 1  and  127 - 2  are pushed toward the left side in the figures by the reversing member. In  FIG. 9B , the roller pin  127 - 1  comes into contact with the inner circumferential surface  135  of the driven gear  111  and the shaped surface  131  simultaneously, and in  FIG. 9C , the roller  127 - 2  comes into contact with the inner circumferential surface  138  of the driving gear  118  and the shaped surface  131  simultaneously. 
     When the driving gear  118  is rotating in clockwise direction, the inner circumferential surface  138  rotates the corresponding roller pin  127 - 2  in clockwise direction, and the roller pin is subject to a rightward friction on the shaped surface  131 , that is, both of the forces applied to the roller pin  127 - 2  by the inner circumferential surface  138  and the shaped surface  131  are rightward; because of the dimension of the right side radial clearance of the roller pin  127 - 2  being greater than the diameter of the roller pin, the roller pin  127 - 2  is caused to be in loose state, therefore, the driving gear  118  is rotating idly in relation to the main shaft  105  at this point. However, because of the existence of the idle gear  128 , the driven gear  111  is caused to be rotating in counterclockwise direction. The inner circumferential surface  135  rotates the corresponding roller pin  127 - 1  in counterclockwise direction, and the roller pin  127 - 1  is subject to a leftward friction on the shaped surface  131 , that is, both of the forces applied to the roller pin  127 - 1  by the inner circumferential surface  135  and the shaped surface  131  are leftward, such that the roller pin  127 - 1  is clamped by the wedge angle formed between the shaped surface  131  and the inner circumferential surface  135 , rotating the main shaft  105  in counterclockwise direction. 
     When the driving gear  118  is rotating in counterclockwise direction, the inner circumferential surface  138  rotates in counterclockwise direction, and the roller pin  127 - 2  is subject to a leftward friction on the shaped surface  131 , that is, both of the forces applied to the roller pin  127 - 2  by the inner circumferential surface  138  and the shaped surface  131  are leftward, such that the roller pin  127 - 2  is clamped by the wedge angle formed between the shaped surface  131  and the inner circumferential surface  138 , rotating the main shaft  105  in counterclockwise direction. At this point, the driven gear  111  is rotating in clockwise direction, and the roller pin  127 - 1  engaging with the inner circumferential surface  135  is also rotating in clockwise direction, which is subject to a rightward friction on the shaped surface  131 , that is, both of the forces applied to the roller pin  127 - 1  by the inner circumferential surface  135  and the shaped surface  131  are rightward; because of the dimension of the right side radial clearance of the roller pin being greater than the diameter of the roller pin, the roller pin  127 - 1  is caused to be in loose state, and, correspondingly, the driven gear  111  rotates idly in relation to the main shaft  105 . 
     Accordingly, no matter if the handle rotates the driving gear in clockwise direction or counterclockwise direction, the main shaft  105  rotates in counterclockwise direction in the second operating state. 
     Above all, the reversing means  110  achieves the one-way clutch function in two operating states respectively. 
     Referring to  FIG. 7 ,  FIG. 8A  and  FIG. 9A , the reversing member  115  is arranged with two positioning slot  117 - 1  and  117 - 2  thereon, which engage with the positioning steel ball  124  arranged on the main shaft  105  so as to achieve the aforementioned switching between two operating states. The positioning steel ball  124  is pushed into the positioning slot by a spring  123  located inside the main shaft  105 , setting the reversing means  110  into one of the two operating states. By rotating the reversing member  115  through an angle relative to the main shaft  105 , the position of the steel ball  124  can be switched between the two positioning slots, allowing this embodiment switches between the aforementioned first operating state and second operating state, so as to achieve the direction switch function of the reversing means  110 . 
     2.3 the Operating Method of the Embodiment is Described with Reference to the Accompanying Figures as Follows 
     2.3.1 First, the reversing member  115  is rotated relative to the main shaft  105 , and the positioning steel ball  124  is disposed in the desired one of the two positioning slots, as in the positioning slot  117 - 1  as shown in  FIG. 8A , then the main shaft  105  is arranged to be able to rotate only in clockwise direction, and the embodiment is in the aforementioned first operating state.
 
2.3.1.1 The operator holds the grip ring  113  with one hand, and the other hand rotates the handle  121  in clockwise direction to rotate the driving gear  118  to rotate in clockwise direction. At this point, the inner circumferential surface  138  of the driving gear  118  and the shaped surface  131  of the main shaft  105  clamp the corresponding roller pin  127 - 2 , rotating the main shaft  105  in clockwise direction. The idle gear  128  rotates the driven gear  111  in counterclockwise direction, and the roller pin  127 - 1  corresponding to the driven gear  111  is in loose state, being able to roll, causing the driven gear  111  to rotate idly on the main shaft  105 . Therefore, the driven gear does not function at this point.
 
2.3.1.2 The operator rotates the handle  121  in counterclockwise direction to rotate the driving gear  118  to rotate in counterclockwise direction. At this point, the roller pin  127 - 2  corresponding to the driving gear  118  is in loose state, being able to roll, causing the driving gear  118  to rotate idly on the main shaft  105 . The idle gear  128  rotates the driven gear  111  in clockwise direction, and the roller pin  127 - 1  corresponding to the driven gear  111  is clamped, and the main shaft  105  is rotated in clockwise direction.
 
     Above all, it is achieved that the main shaft rotates in clockwise direction, no matter in which direction the handle  121  rotates. 
     2.3.2 Then, the reversing member  115  is rotated relative to the main shaft  105 , and the positioning steel ball  124  is changed to be in the positioning slot  117 - 2 , then the main shaft  105  is arranged to be able to rotate only in counterclockwise direction, and the embodiment is in the second operating state. The operator holds the grip ring  113  with one hand, and the main shaft rotates in counterclockwise direction no matter if the other hand rotates the handle in clockwise direction or counterclockwise direction.
 
3. The Reversing Means  110  is Further Improved in its Structure.
 
     Referring to  FIG. 1, 2, 3 , the head cover  108  is also arranged with a sliding slot which is parallel to the axis of the main shaft  105 , and which is provided with a push button assembly  126  slidable along the sliding slot, for controlling the position of the reversing member  115 , so as to set the rotation direction of the main shaft  105 . For example, when the push button assembly  126  is toggled to the front side position (i.e. in the direction toward the driver bit, shown in  FIG. 1 ), the positioning slot  117 - 1  of the reversing member  115  engages with the positioning steel ball  124 , the main shaft  105  is rotatable only in clockwise direction, and the screwdriver  100  is used for tightening a screw. When the push button assembly  126  is toggled to the rear side position (i.e. in the direction away from the driver bit, shown in  FIG. 3 ), the positioning slot  117 - 2  of the reversing member  115  engages with the positioning steel ball  124 , the main shaft  105  is rotatable only in counterclockwise direction, and the screwdriver  100  is used for loosening a screw. Surely, the relationship between the push button and the rotation direction of the main shaft can be reversed, which is not limited by the present invention. 
     The control of the reversing member  115  by the push button assembly  126  is achieved through a spatial cam mechanism. As shown in  FIG. 7  and  FIG. 8A ,  FIG. 9A , a helical sliding slot  116  is arranged on the outer circumferential surface of the reversing member  115 . The push button assembly  126  has a portion extending into the sliding slot  116 , such as an arm  126 - 1  or a steel ball, so as to constitute a cam mechanism that converts the axial lineal movement of the push button assembly  126  to the circular movement of the reversing member  115 , that is, by toggling the push button assembly  126  along the axis, the arm  126 - 1  protruding in the sliding slot  116  causes the reversing element  115  to move circularly. Through the cam mechanism, the switching of the push button assembly  126  between the front and rear positions is converted to the switching of the positioning steel ball  124  in the two positioning slots. 
     To achieve the direction switching without a push button assembly  126 , the operator has to hold the main shaft and the reversing member  115  (or the components that are easy to hold, and are respectively securely connected with the above two components) with two hands respectively, and rotate them oppositely. But with the push button assembly  126  disposed, the operator can push it only with one finger to achieve the direction switching. This improvement greatly facilitates the use of the reversing means  110 . 
     In addition, when the method of using the push button assembly  126  to control the rotation of the reversing member  115  is adopted, the structure of the positioning steel ball  124  and two positioning slots can be cancelled. As long as the reversing member  116  can be pushed through the push button assembly  126 , and consequently the roller pin is pushed to reach the operation position of the one-way clutch, the object of the present invention can be achieved. 
     The embodiment also includes structures limiting the unnecessary axial displacement of each component, such as a step, a stop ring, a fastener, etc., and various bearings, shaft sleeve with oil, etc. that are arranged for smooth rotation, which are not detailed described here, and are not limited by the present invention. 
     In general operations, the grip ring  113  of the embodiment is stationary when being held, that is, compared with an ordinary screwdriver without bi-directional multispeed transmission, the efficiency is doubled. But in actual operations, the grip ring  113  can also be caused to rotate in reverse direction relative to the handle  121 , and then the rotation speed of the main shaft  105  is double of that of the handle  121 , i.e. the efficiency is quadruple, compared with an ordinary screwdriver without bi-directional multispeed transmission. 
     Embodiment Two 
     The embodiment is similar to Embodiment One, the only difference is that the reversing means  110  in Embodiment One is replaced with the ratchet-pawl reversing means as shown in  FIG. 11A, 11B  and  FIG. 12A, 12B . Pawl seats are arranged on the main shaft  105 . Two opposed rotatable pawls are arranged symmetrically on the pawl seat, i.e. the pawl seat  223  and pawls  224   a  and  224   b  corresponding to the driving gear  118  in  FIGS. 11B and 12B , and the pawl seat  213  and pawls  214   a  and  214   b  corresponding to the driven gear  111  in  FIGS. 11A and 12A . An opening is provided on the reversing member  215 . Both ends of the opening are capable of pushing the pawls to change the operating position of the pawls (i.e. to set the rotation direction of the main shaft). In  FIGS. 11A and 12A , the two ends of the opening of the reversing member  215  are  216   a  and  216   b , and the two ends are  226   a  and  226   b  in  FIGS. 11B and 12B . The inner circumferential surfaces of the driving gear  118  and the driven gear  111  are changed to be inside ratchet surfaces  238  and  235  having circular distribution. These two inside ratchet surfaces can respectively engage with at least one pawl. Two elastic members  219  and  229  is arranged between each pair of pawls to make the two pawls to open to abut onto the inside ratchet surface, to ensure that the pawls and the inside ratchet surface can engage reliably. The operating principle of the embodiment is: 
       FIG. 11A, 11B  correspond to the first operating state of the embodiment, in which the pawl  224   b  engages with the inside ratchet surface  238 , and the pawl  214   b  engages with the inside ratchet surface  235 . At this point, the opening end  216   a  of the reversing member  215  pushes the pawl  214   a , and the opening end  226   a  of the reversing member  215  pushes the pawl  224   a , detaching from each of their inside ratchet surfaces  235 ,  238 , so as not to serve the function. 
     At this point, if the handle  121  is rotated in clockwise direction, the driving gear  118  is rotated in clockwise direction, and the pawl  224   b  slides over the inside ratchet surface  238  without transferring torque to the main shaft  105 . The driven gear  111  is rotated by the idle gear  128  to rotate in counterclockwise direction, and the inside ratchet surface  235  can transfer torque to the main shaft  105  through the pawl  214   b  engaging with it, to rotate the main shaft in counterclockwise direction. 
     If the handle  121  is rotated in counterclockwise direction, the driving gear  118  is rotated in counterclockwise direction, and the inside ratchet surface  238  can transfer torque to the main shaft  105  through the pawl  224   b  engaging with it, to rotate the main shaft in counterclockwise direction. The driven gear  111  is rotated in clockwise direction, and the pawl  214   b  slides over the inside ratchet surface  235 , that is, the driven gear  111  rotates idly relative to the main shaft  105 . 
     Therefore, no matter if the handle rotates the driving gear in clockwise direction or counterclockwise direction, in the first operating state, the main shaft  105  in the embodiment rotates in counterclockwise direction. 
       FIG. 12A, 12B  correspond to the second operating state of the embodiment, in which the reversing member  21  rotates through a certain angle in clockwise direction, causing the ratchet  224   a  to engage with the inside ratchet surface  238 , and the ratchet  214   a  to engage with the inside ratchet surface  235 . At this point, the opening end  216   b  of the reversing member  215  pushes the pawl  214   b , and the opening end  226   b  of the reversing member  215  pushes  224   b , to detach them respectively from each of the inside ratchet surface  235 ,  238 , so as to not serve function. It is known according to the same principle that no matter if the handle rotates the driving gear in clockwise direction or counterclockwise direction, in the second operating state, the main shaft rotates in clockwise direction. 
     Thus, by toggling the reversing member  215  in relation to the main shaft  105  and using the opening end thereof to cause a suitable pawl to engage with the inside ratchet surface, the switching between the first operating state and the second operating state can be achieved. 
     Embodiment Three 
     The embodiment is similar to Embodiment One, the only difference is that the reversing means  110  in Embodiment One is replaced to be a stopping-block reversing means as shown in  FIG. 13A, 13B  and  FIG. 14A, 14B . Slots are provided in parallel at both sides of the axis on the main shaft  105 , and a stopping block is arranged in the slot, that is, the stopping bocks  324   a  and  324   b  corresponding to the driving gear  118  shown in  FIG. 13B  and  FIG. 14B , and the stopping blocks  314   a  and  314   b  corresponding to the driven gear  111  shown in  FIG. 13A  and  FIG. 14A . The outside end faces of the stopping blocks  314   a  and  314   b  are inclined surfaces, and the two inclined surfaces are opposedly facing in V-shape. Openings are provided on the reversing member  315 , and the end portion of the opening can push the outside end face of the stopping block, to cause the stopping block to extend or retract in the slot, so as to change the operating position of the stopping block (i.e. to set the rotation direction of the main shaft). In  FIGS. 13A and 14A , the acting ends of openings of the reversing member  315  are  316   a  and  316   b , and the opening work ends of the opening in  FIGS. 13B and 14B  are  326   a  and  326   b . The acting ends of openings of the reversing member  315  are respectively located between the two V-shaped inclined surfaces. The inner circumferential surfaces of the driving gear  118  and the driven gear  111  are changed to be inside toothed surfaces  338  and  335  having a plurality of toothed portion. The two toothed surfaces can respectively engage with at least one stopping block. A spring  319  is also provided in the slot of the stopping block arranged on the main shaft  105 , for pushing the stopping block outward to ensure the stopping block can reliably engage with the inside toothed surface. The principle of the embodiment is: 
       FIG. 13A, 13B  correspond to the first operating state of the embodiment, in which the opening work end of the reversing member  315  pushes the stopping block  324   a  to retract into the slot, and the stopping block  324   b  engages with the inside toothed surface  338 . The opening′acting end  316   a  of the reversing member  315  pushes the stopping block  314   a  to retract into the slot, and the stopping block  314   b  engages with the inside toothed surface  335 . 
     At this point, if the handle  121  is rotated in clockwise direction, the driving gear  118  is rotated in clockwise direction, and the inside toothed surface  238  can transfer torque to the main shaft  105  through the stopping block  324   b  engaging with it, to rotate the main shaft in clockwise direction. The driven gear  111  is rotated by the idle gear  128  to rotate in counterclockwise direction, and the stopping block  314   b  slides over the inside toothed surface  335  without transferring torque to the main shaft  105 , that is, the driven gear  111  rotated idly relative to the main shaft  105 . 
     If the handle  121  is rotated in counterclockwise direction, the driving gear  118  is rotated in counterclockwise direction, and the stopping block  324   b  slides over the inside toothed surface  235  without transferring torque to the main shaft  105 . The driven gear  111  is rotated by the idle gear  128  in clockwise direction, and the inside toothed surface  335  can transfer torque to the main shaft  105  through the stopping block  314   b  engaging with it, to rotate the main shaft in clockwise direction. 
     Therefore, no matter if the handle rotates the driving gear in clockwise direction or counterclockwise direction, in the first operating state, the main shaft  105  in the embodiment rotates in clockwise direction. 
       FIG. 14A, 14B  correspond to the second operating state of the embodiment, in which the opening&#39;s acting end  326   b  of the reversing member  315  pushes the stopping block  324   b  to retract into the slot, and the stopping block  324   a  engages with the inside toothed surface  338 . The opening&#39;s acting end  316   b  of the reversing member  315  pushes the stopping block  314   b  to retract into the slot, and the stopping block  314   a  engages with the inside toothed surface  335 . It is known according to the same principle that no matter the handle rotates the driving gear in clockwise direction or counterclockwise direction, in the second operating state, the main shaft  105  rotates in counterclockwise direction. 
     Therefore, by pushing the reversing member  315  in relation to the main shaft  105  and using the acting ends of openings thereof to cause a suitable stopping block to engage with the inside toothed surface, the switching between the first operating state and the second operating state can be achieved. 
     Embodiment Four 
     The embodiment is a variation of the stopping block in Embodiment Three, that is, the outside end face of the stopping block is changed to be a plane surface. Take the components corresponding to the driving gear  118  as shown in  FIG. 15  as an example, the outside end faces of the stopping blocks  424   a  and  424   b  are plane surfaces, and the opening&#39;s acting ends  426   a  and  426   b  of the reversing member  415  are located between the two stopping blocks, being able to push the outside end face of the stopping block, to cause the stopping block to extend and retract in the slot, so as to change the operating positions of the stopping block (i.e. to set the rotation direction of the main shaft). The inside toothed surface  438  of the driving gear  118  can engage with at least one stopping block. It can be understood by the person skilled in the art that the operating principle of the embodiment is the same as that of Embodiment Three, also being able to achieve the object of the present invention. 
     Embodiment Five 
     The embodiment is a variation of the stopping block and the reversing member in Embodiment Three. Take the component corresponding to the driving gear  118  as shown in  FIG. 16  as an example, the outside end faces of the stopping blocks  524   a  and  524   b  are of a tooth form that engage with the inside toothed surface  538  of the driving gear  118 , and the opening&#39;s acting ends  526   a  and  526   b  of the reversing member  515  are located outside of the two stopping blocks, being able to push the outside end face of the stopping block, to cause the stopping block to extend or retract in the slot, so as to change the operating position of the stopping block (i.e. to set the rotation direction of the main shaft). The inside toothed surface  538  of the driving gear  118  can engage with at least one stopping block. It can be understood by the person skilled in the art that the operating principle of the embodiment is the same as that of the Embodiment Three, also being able to achieve the object of the present invention. 
     Embodiment Six 
     The embodiment discloses another reversing means, as shown in  FIGS. 17-26 , in which the reversing means  110 ′ is sleeved with a transmission mechanism  130  about the outside. The reversing means  110 ′ includes a reversing member  115 ′, a central shaft  220 , a first ball plug  221  and a second ball plug  222  constituting a reversing switch, and a first pawl member  211  and a second pawl member  212 , in which the main shaft  105  and the central shaft  220  are sleeved with the reversing member, and they can rotate together; the first ball plug  221  and the second ball plug  222  are secured on the central shaft  220  at intervals. Preferably, an elastic member such as a spring, etc. is fitted between the first ball plug  221  and the second ball plug  222  and the central shaft. The first pawl member  211  and the second pawl member  212  are mounted on the reversing member  115 ′ through a secondary shaft  210 , as shown in  FIG. 25 , the secondary shaft  210  are parallel to the reversing member  115 ′ but its central axis is not coincident with the central axis of the reversing member  115 ′, and the first pawl member  211  and the second pawl member  212  are rotatable about the secondary shaft  210 . 
     The first pawl member  211  and the second pawl member  212  have similar structures, both including a first fan-shaped pawl, a second fan-shaped pawl and the fan-shaped middle portion therebetween. Take the first pawl member  211  as an example,  FIG. 26  shows a top view of the first pawl member  211 , and it can be seen from  FIG. 26  that the first pawl member  211  includes a first fan-shaped pawl  2111 , a second fan-shaped pawl  2112  and a fan-shaped middle portion  2110  therebetween. The fan-shaped toothed surface of the first fan-shaped pawl  2111 , the fan-shaped surface of the fan-shaped middle portion  2110  and the fan-shaped toothed surface of the second fan-shaped pawl  2112  constitute a first surface of the first pawl member  211 . The first pawl member  211  also includes a second surface, that is, bottom surface, which is a shaped surface. In the embodiment the shaped includes a recess  2113  having a first side wall  2114  and a second side wall  2115 . A via hole engaging with the secondary shaft  210  is provided in the first pawl member  211 , and the secondary passes through the via hold  2101  and mounts the first pawl member  211  on the reversing member  115 ′. In the embodiment, the via hole  2101  is arranged at the fan-shaped middle portion of the first pawl member  211 , preferably, at the center of gravity of the first pawl member  211 . The structure of the second pawl member  212  is similar to the first pawl member  211 , which are not described here, in the embodiment, its thickness is smaller than the thickness of the first pawl member  211 , but in other embodiments, its thickness can be equal to the thickness of the first pawl member  211 , or greater than the thickness of the first pawl member  211 . 
     The first surfaces of the first pawl member  211  and the second pawl member  212  face the toothed surfaces of the first ratchet surface  311  at the inside of the driving gear  118  and the second ratchet surface  321  at the inside of the driven gear  111 , respectively. Specifically, the teeth of the fan-shaped pawl of the first pawl member  211  (including the first fan-shaped pawl  2111  and the second fan-shaped pawl  2112 ) face the teeth of the first ratchet surface  311 , and the teeth of the fan-shaped pawl (including the first fan-shaped pawl and the second fan-shaped pawl) of the second pawl member  212  face the teeth of the second ratchet surface  321 . The second surfaces of the first pawl member  211  and the second pawl member  212  face the surface of the central shaft  220  respectively. Specifically, the second surface of the first pawl member  211  faces the first ball plug  221 , and the second surface of the second pawl member  212  faces the second ball plug  222 . By rotating the central shaft  220 , the first ball plug  221  is caused to come into contact with the first side wall  2114  of the recess  2113  of the first pawl member  211 , and at the same time, the second ball plug  222  is caused to come into contact with the first side wall of the recess of the second pawl member  212 . At this point the bi-directional screwdriver of the present invention is in the first operating mode; or, the first ball plug  221  is caused to come into contact with the second side wall  2115  of the recess  2113  of the first pawl member  211 , and at the same time the second ball plug  222  is caused to come into contact with the second side wall of the recess of the second pawl member  212 . At this point the bi-directional screwdriver of the present invention is in a second operating mode. 
     When the bi-directional screwdriver of the present invention is in the first operating mode, as shown in  FIGS. 17A-17E , the teeth of the first fan-shaped pawl  2111  of the first pawl member  211  comes into contact with the teeth of the first ratchet surface  311 , and likewise, the teeth of the first fan-shaped pawl of the second pawl member  212  comes into contact with the teeth of the second ratchet surface  321 . When the handle causes the first ratchet surface  311  of the driving gear  118  to rotate, and when the moving direction of the teeth of the first ratchet surface  311  at the first fan-shaped pawl  2111  is directing at the second fan-shaped portion  2112  from the first fan-shaped portion  2111 , because the first ball plug  211  contacts the first side wall  2114  of the recess  2113  of the first pawl member  211  when the first ratchet surface  311  rotates in clockwise direction, the first ratchet surface  311  cannot cause the first pawl member  211  to rotate with it together, that is, the teeth of the first fan-shaped pawl  2111  do not engage with the teeth of the first ratchet surface  311  for transmission; and when the moving direction of the teeth of the first ratchet surface  311  at the first fan-shaped pawl  2111  is directing at the first fan-shaped portion  2111  from the second fan-shaped portion  2112 , that is, when the first ratchet surface  311  rotates in counterclockwise direction, because the first ball plug  211  contacts the first side wall  2114  of the recess  2113  of the first pawl member  211 , the first ratchet surface  311  can cause the first pawl member  211  to rotate with it together, that is, the teeth of the first fan-shaped pawl  2111  engages with the teeth of the first ratchet surface  311  for transmission. The rotation of the first pawl member  211  is transferred to the reversing member  115 ′ through the secondary shaft  210 , so as to rotate the reversing member  115 ′. 
     At the same time, when the moving direction of the teeth of the second ratchet surface  321  at the first fan-shaped pawl of the second pawl member  212  is directing at the second fan-shaped portion from the first fan-shaped portion of the second pawl member  212 , that is, when the second ratchet surface  321  rotates in clockwise direction, because the second ball plug  222  contacts the first side wall of the recess of the second pawl member  212 , the second ratchet surface  321  cannot cause the second pawl member  212  to rotate with it together, that is, the teeth of the first fan-shaped pawl of the second ratchet member  212  do not engage with the teeth of the second ratchet surface  321  for transmission; and when the moving direction of the teeth of the second ratchet surface  321  at the first fan-shaped pawl of the second pawl member  212  is directing at the first fan-shaped portion from the second fan-shaped portion of the second pawl member  212 , that is, when the second ratchet surface  321  rotates in counterclockwise direction, because the second ball plug  222  contacts the first side wall of the recess of the second pawl member  212 , the second ratchet surface  321  can cause the second pawl member  212  to rotate with it together, that is, the teeth of the first fan-shaped pawl of the second pawl member  212  engages with the teeth of the second ratchet surface  321  for transmission. The rotation of the second pawl member  212  is transferred to the reversing member  115 ′ through the secondary shaft  210 , so as to rotate the reversing member  115 ′. 
     Because of the aforementioned transmission among the idle gear  128  and the driving gear  118  and the driven gear  111 , when the grip ring  113  is stationary, the rotation direction of the second ratchet surface  321  is reverse to the first ratchet surface  311 . It thus can be known that in the first operating mode of the present invention, when the inputted torque from the handle is clockwise torque, it causes the first ratchet surface  311  to rotate in clockwise direction, and the second ratchet surface  321  in counterclockwise direction. At this point the first pawl member  211  does not connect with the first ratchet surface  311 , and the second pawl member  212  connects with the second ratchet surface  321 . Therefore, the second pawl member  212  rotates the reversing member  115 ′ in counterclockwise direction, and the outputted torque is counterclockwise torque; when the inputted torque from the handle is counterclockwise torque, it causes the first ratchet surface  311  to rotate in counterclockwise direction, and the second ratchet surface  321  in clockwise direction. At this point the first pawl member  211  connects with the first ratchet surface  311 , and the second pawl member  212  does not connect with the second ratchet surface  321 . Therefore, the first pawl member  211  rotates the reversing member  115 ′ in counterclockwise direction, and the outputted torque is counterclockwise torque. 
     When the bi-directional screwdriver of the present invention is in the second operating mode, as shown in  FIGS. 18A-18E , the teeth of the second fan-shaped pawl  2112  of the first pawl member  211  come into contact with the teeth of the first ratchet surface  311 , and likewise, the teeth of the second fan-shaped pawl of the second pawl member  212  come into contact with the teeth of the second ratchet surface  321 . When the inputted torque from the handle causes the first ratchet surface  311  to rotate, and when the moving direction of the teeth of the first ratchet surface  311  at the second fan-shaped pawl  2112  is directing at the second fan-shaped portion  2112  from the first fan-shaped portion  2111 , that is, when the first ratchet surface  311  rotates in clockwise direction, because the first ball plug  221  contacts the second side wall  2115  of the recess  2113  of the first pawl member  211 , the first ratchet surface  311  cause the first pawl member  211  to rotate with it together, that is, the teeth of the second fan-shaped pawl  2112  engages with the teeth of the first ratchet surface  311  for transmission; the rotation of the first pawl member  211  is transferred to the reversing member  115 ′ through the secondary shaft  210 , so as to rotate the reversing member  115 ′. When the moving direction of the teeth of the first ratchet surface  311  at the second fan-shaped pawl  2112  is directing at the first fan-shaped portion  2111  from the second fan-shaped portion  2112 , that is, when the first ratchet surface  311  rotates in counterclockwise direction, because the first ball plug  221  contacts the first side wall  2115  of the recess  2113  of the first pawl member  211 , the first ratchet surface  311  cannot cause the first pawl member  211  to rotate with it together, that is, the teeth of the second fan-shaped pawl  2112  do not engage with the teeth of the second ratchet surface  311  for transmission. 
     At the same time, when the moving direction of the teeth of the second ratchet surface  321  at the second fan-shaped pawl of the second pawl member  212  is directing at the second fan-shaped portion from the first fan-shaped portion of the second pawl member  212 , that is, when the second ratchet surface  321  rotates in clockwise direction, because the second ball plug  222  contacts the second side wall of the recess of the second pawl member  212 , the second ratchet surface  321  can cause the second pawl member  212  to rotate with it together, that is, the teeth of the second fan-shaped pawl of the second ratchet member  212  engage with the teeth of the second ratchet surface  321  for transmission; the rotation of the second pawl member  212  is transferred to the reversing member  115 ′ through the secondary shaft  210 , so as to rotate the reversing member  115 ′. When the moving direction of the teeth of the second ratchet surface  321  at the second fan-shaped pawl of the second pawl member  212  is directing at the first fan-shaped portion from the second fan-shaped portion of the second pawl member  212 , that is, when the second ratchet surface  321  rotates in counterclockwise direction, because the second ball plug  222  contacts the second side wall of the recess of the second pawl member  212 , the second ratchet surface  321  cannot cause the second pawl member  212  to rotate with it together, that is, the teeth of the first fan-shaped pawl of the second pawl member  212  do not engage with the teeth of the second ratchet surface  321  for transmission. 
     Because of the aforementioned transmission among the idle gear  128  and the driving gear  118  and the driven gear  111 , when the grip ring  113  is stationary, the rotation direction of the second ratchet surface  321  is reverse to the first ratchet surface  311 . It thus can be known that in the second operating mode of the present invention, when the inputted torque from the handle is clockwise torque, it causes the first ratchet surface  311  to rotate in clockwise direction, and the second ratchet surface  321  in counterclockwise direction. At this point the first pawl member  211  connects with the first ratchet surface  311 , and the second pawl member  212  does not connect with the second ratchet surface  321 . Therefore, the first pawl member  211  rotates the reversing member  115 ′ in clockwise direction, and the outputted torque is clockwise torque; when the inputted torque from the handle is counterclockwise torque, it causes the first ratchet surface  311  to rotate in counterclockwise direction, and the second ratchet surface  321  to rotate in clockwise direction. At this point the first pawl member  211  does not connect with the first ratchet surface  311 , and the second pawl member  212  connects with the second ratchet surface  321 . Therefore, the first pawl member  211  rotates the reversing member  115 ′ in counterclockwise direction, and the outputted torque is clockwise torque. 
     As aforementioned, by rotating the central shaft  220 , the bi-directional screwdriver of the present invention can switch and select between the first operating mode and the second operating mode. For the convenient of use, in the embodiment, a helical sliding slot  116 ′ is arranged at the front end of the central shaft  220 . The head cover  108  is arranged with a sliding slot which is parallel to the axis of the main shaft  105 . The sliding slot is provided with a push button assembly  126  which is slidable along the sliding slot, for controlling the position of the central shaft so as to set the rotation direction of the main shaft  105 . 
     The push button assembly  126  achieves the controlling of the central shaft  220  through a spatial cam mechanism. As shown in  FIG. 24 , a helical sliding slot  116 ′ is arranged on the outer circumferential surface of the central shaft  220 . The push button assembly  126  has a portion extending into the sliding slot  116 ′, such as arm  126 - 1  or a steel ball, so as to constitute a cam mechanism that converts the axial lineal movement of the push button assembly  126  to the circular movement of the central shaft  220 , that is, by toggling the push button assembly  126  along the axis, the arm  126 - 1  extending into the sliding slot  116 ′ causes the central shaft to be in circling motion. 
     Above noted are several embodiments of a screwdriver having bi-directional mechanical converter, which is also suited for wrenches, especially with Embodiment Six. No matter which direction of the rotation torque inputted from the screwdriver or wrench is, the bi-directional mechanical converter transfers torque to the main shaft of screwdriver or wrench for output according to a predetermined direction. 
     On the basis of the above screwdriver or wrench having bi-directional mechanical converter, the present invention further provides a bi-directional screwdriver or wrench having speed increasing mechanism. A speed increasing bi-directional screwdriver is described in the following with reference to embodiments. 
       FIGS. 17-21  show an embodiment of the speed increasing bi-directional screwdriver, and it can be seen from the figures that on the basis of the above bi-directional screwdriver, the screwdriver also has a speed increasing mechanism, and further includes a speed increasing switch  5 . When the speed increasing switch  5  is turned on, the rotation inputted from the handle  121  is speeded up before being transferred into the bi-directional mechanical converter; when the speed increasing switch  5  is turned off, the rotation inputted from the handle  121  is directly transferred into the bi-directional mechanical converter. 
       FIG. 20  shows the screwdriver after removing the handle  121 , the grip ring  113 . The visible part  6  is an embodiment of a bi-directional mechanical converter as aforementioned, which is not described here. And the part  7  related to the part  6  is the speed increasing mechanism part, which will be described as follows. 
       FIGS. 28 and 29  are exploded view of the speed increasing mechanism  7 .  FIG. 8  shows the driving gear  118  of the bi-directional mechanical converter, which is arranged with a gear shaft  81  at the tail part. It requires to be explained that although in the embodiment the gear shaft  81  is not integrated with the driving gear  118 , but in other embodiments, the integrated connection can be used to allow the gear shaft  81  to cause the driving gear  118  to rotate together. Referring to  FIGS. 28 and 29 , the gear shaft  81  is sleeved with a speed increasing planetary gear mechanism  9  thereon which includes a gear ring  91  securely connected to the grip ring  113 , three planetary gears  92  engaged between the gear shaft  81  and the gear ring  91 , and a planetary carrier sleeve  10 . The gear shaft  81  serves as a sun gear in the speed increasing planetary gear mechanism at this point. When the operator holds the grip ring  113  and rotates the handle  2 , the gear ring  91  is stationary, and the handle transfers the rotation to the planetary carrier sleeve  10  which rotates the planetary gear  92  which rotates the gear shaft  81  to rotate with speed increasing. In the embodiment, if the gear ring  91  is stationary, the rotation is inputted by the planetary gear  92 , and outputted by the sun gear i.e. the gear shaft  81 . 
     In the embodiment, the number of the teeth of the gear ring  91  is 36, and the number of the teeth of the gear of the planetary gear  92  is 12, and thereby the speed increasing planetary gear mechanism  9  causes the rotation inputted from the handle  2  to be increased by four times of speed and then the rotation is transferred to the driving gear  8  of the bi-directional mechanical converter. In other embodiments, other speed ratio can be configured according to actual requirements. 
     In the screwdriver of the embodiment, although the rotation speed of the main shaft  105  is increased through speed increasing mechanism  7 , the screwdriver operating efficiency under low torque requirement operating situations can be improved, whereas with the increase of the rotation speed, the outputted torque of the screwdriver is decreasing, it cannot meet the requirement of use under high torque requirement operation situation. Therefore, in the embodiment, the speed increasing mechanism part  7  is further arranged with a clutching feature, that is, to cause the speed increasing mechanism to engage when under low torque requirement operation situation so as to improve the rotation speed outputted by the screwdriver, and to detach when under high torque requirement operation situation so as to increase the outputted torque by the screwdriver. The realizing of the clutching feature in the embodiment will be described as follows. 
     As shown in  FIG. 30 , the gear shaft  81  includes three parts: a first gear surface  811  engaging with the planetary gear  92 , a smooth surface  812  and a second gear surface  813 . An inner gear  101  is arranged on the inner circumferential surface of the planetary carrier sleeve  10 , which can be driven by the speed increasing switch  5  to slide between the engaging and detaching positions on the gear shaft  81 . When the planetary carrier sleeve  10  slides to the engaging position, the planetary carrier sleeve  10  engages with the planetary gear  92  and rotates the planetary gear  92 . At this point, the inner gear  101  is located at the smooth surface  812  on the gear shaft  81 ; when the planetary carrier sleeve slides to the detaching position, the planetary carrier sleeve  10  detaches from the planetary gear  92  without rotating the planetary gear  92 , and the inner gear  101  is located at the second gear surface  813  and engages with it, so that the inputted rotation by the handle  121  can be directly transferred to the driving gear  118 , and keep the original torque without being speed-increased by the speed increasing mechanism  7 . 
     In the embodiment, an outer sleeve  11  is provided about the outside the planetary carrier sleeve  10 , a handle  121  is sleeved on the outside of the outer sleeve  11 , the rotating inputted by the handle  121  is transferred to the planetary carrier sleeve  10  through the outer sleeve  11 . It can be understood by the person skilled in the art that, in other embodiments, other connection method can be used between the handle  2  and the planetary carrier sleeve  10  to transfer the inputted rotation to the planetary carrier sleeve  10 . 
     The invention has been exemplified above with reference to specific embodiments. However, it should be understood that a multitude of modifications and varieties can be made by a common person skilled in the art based on the conception of the present invention. Therefore, any technical schemes, acquired by the person skilled in the art based on the conception of the present invention through logical analyses, deductions or limited experiments, fall within the scope of the invention as specified in the claims.