Abstract:
The present invention relates to a power tool, including a housing, a motor, and a speed adjusting system decelerating the rotate rotation speed of said motor. The speed adjusting system comprises a includes an output, a main shaft connecting to the output, and a working shaft employed for adapting with corresponding working head during working. The main shaft is connected with a hammer that can move axially against the main shaft. The working shaft is connected with an anvil that rotates together with the working shaft. The hammer has first teeth, the anvil has second teeth, and the hammer drives the anvil on rotate direction through the cooperation between the first teeth of the hammer and the second teeth of anvil. The power tool also includes a clutch, which can move between the first position and the second position to optionally rigidly connect the hammer with at least one of the output and the main shaft.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application is the entry into the U.S. National Phase of PCT/CN2010/076711, filed Sep. 8, 2010, which claims priority to Chinese Patent Application No. CN200910176229.X, filed Sep. 10, 2009, each of which is incorporated herein in its entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    The present disclosure relates to a power tool, especially to a kind of multifunctional power tool that can achieve the functions of the impact wrench, and the functions of the electric drill, the electric screwdriver or the percussion drill. 
       BACKGROUND 
       [0003]    Among the existing power tools, the impact wrench is used to fasten the threaded fastener to workpieces. The impact wrench usually comprises a main shaft driven and rotated by motor, an hammer connected with the main shaft through the cooperation of a helical groove and a rolling ball, and a working shaft situated at the front of the hammer and cooperating with the hammer through end teeth. At the back of the hammer, there is an impact-spring which oppresses the hammer to maintain the reliable cooperation between the hammer and the working shaft. During working, the rotation motion of the main shaft is directly transferred to threaded parts through the hammer and the working shaft&#39;s anvil in order to fasten threaded parts to workpiece. During such fastening, the load of the working shaft becomes heavier and heavier. When the load exceeds the pre-set value, the hammer will move against the axial direction of the anvil mounted on the working shaft and towards the motor, and at the same time, the spring at the back of the hammer will be compressed due to such movement. At the moment when the hammer does not engage with the end teeth of the anvil mounted on the working shaft, the action of the impact-ring causes the hammer to move ahead axially and to impact the anvil mounted on the working shaft in the rotation direction in order to make the working shaft fasten the threaded parts in the rotation direction. Repeatedly like this, the intermittently impacting of the hammer ensures that threaded parts are fastened to workpieces finally. The electric drill is used to drill workpieces. However, users usually need to fasten threaded parts to workpieces or to drill workpieces when they work. In this case, it will be very troublesome for users to change tools during work. 
         [0004]    In order to overcome the above troubles, people have developed a kind of power tool with the functions of both the impact wrench and the electric drill. The two functions of such power tool are usually switched by a function switch. Actually, the function switch can be achieved in many ways. One relatively common and simple way is to use a mobile stopper to optionally limit the axially backward movement of the hammer. Like this, when the stopper does not limit the axially backward movement of the hammer, the hammer can achieve the function of the impact wrench as described above. When the stopper limits the axially backward movement of the hammer, the hammer will maintain its joining with the working shaft, and will not compress the spring at its back in order to achieve functions of energy-accumulation impact and the electric drill. For example, in the China patent application (CN200510099106), a power tool is disclosed. At the back of the hammer of this power tool, an axially mobile stopper is mounted. When contacting the back of the hammer, this stopper limits the axially backward movement of the hammer for the purpose of achieving the function of the electric drill. When this stopper moves axially upward and does not contact the back of the hammer, the power tool gives the function of the impact wrench into play. However, when such function switching mechanism switches to the function of the electric drill, rotation is transferred by the rolling ball structure in the slide groove between the main shaft and hammer; and the rolling ball, main shaft and hammer are connected in mobile way. As a result, the stopper limiting the axially backward movement of the hammer will bear relatively big force from the hammer; and the hammer moves against the stopper, which wears the stopper heavily. In conclusion, such rotation transferring is not stable. 
       SUMMARY 
       [0005]    The disclosure provides a kind of power tool, which comprises of a function switch mechanism to switch among the functions of the impact wrench and the function of the electric drill, or the screwdriver or the percussion drill. The rotation transferring of the electric drill function of this power tool is stable. 
         [0006]    the disclosure provides: 
         [0007]    A power tool, comprising: a housing ( 1 ); a motor ( 11 ) set in said housing, said motor output rotating movement; a speed adjusting system ( 13 ) decelerating the rotate speed of said motor, said speed adjusting system comprises a output ( 22 ), a main shaft ( 24 ) connecting to said output, and a working shaft ( 5 ) employed for adapting with corresponding working head during working, said main shaft is connected with an hammer ( 31 ), said hammer ( 31 ) can move axially against said main shaft, said working shaft is connected with an anvil ( 51 ), said anvil rotates together with said working shaft, said hammer having first teeth ( 311 ) and said anvil having second teeth ( 511 ), said hammer drives the anvil on rotate direction through the cooperation between said first teeth of the hammer and said second teeth of anvil; wherein said power tool also comprises: a clutch ( 41 ), which can move between the first position and the second position so as to optionally rigidly connect said hammer with at least one of said output and said main shaft. 
         [0008]    Preferably, said clutch can operably move axially between said first position and second position so as to rigidly connect said hammer with at least one of said output and said main shaft, so that the hammer rotate together with at least one of said output and said main shaft. 
         [0009]    Preferably, a spline ( 417 ) or end teeth are provided at the part of the clutch facing the hammer, and a matching spline ( 317 ) or end teeth are provided at the part of the hammer facing said clutch, when the clutch is at said second position, the splines or end teeth of the clutch and the hammer engage with each other so as to form a rigid connection. 
         [0010]    Preferably, said clutch is of ring shape so as to connect with said output in muff-coupling way, The inner circumferential surface of said clutch having a slide block ( 413 ) protruding radially; said output is provided with a slide groove ( 221 ), said slide groove is concave extending axially so as to accept said slide block moving within it. 
         [0011]    Preferably, the inner circumferential surface of said clutch having an inner annular groove ( 415 ) in which elastic ring ( 45 ) is set, the outer circumferential surface of said output having a first annular groove ( 223 ) and a second annular groove ( 225 ), said clutch drives the elastic ring to move to make the elastic ring optionally sitting in said first annular groove or said second annular groove, and accordingly the clutch sit at said first position or said second position. 
         [0012]    Preferably, the power tool comprises a function switch ( 44 ) mounted on said housing ( 1 ), said function switch connects the clutch through a connector ( 42 ) mounted in said housing and drives the clutch to move between said first position and said second position. 
         [0013]    Preferably, the power tool comprises an impact-spring ( 32 ) that elastically against the end of said hammer which far from said anvil, and a ball ( 25 ) situated between said hammer and said main shaft, an inner V-shaped groove ( 312 ) and an outer V-shaped groove ( 241 ) in which the ball rolls are respectively provided to the wall of said hammer and the wall of said main shaft. 
         [0014]    Preferably, the power tool comprises an impact mechanism, which realizes the function of the impact wrench by impacting the anvil intermittently with the hammer. 
         [0015]    Preferably, the power tool can achieve drilling function, electric screwdriver function or percussion drilling function. 
         [0016]    Preferably, the function switch comprises an operating part outside the housing and an annular part in the housing, a track channel is provided for said annular part, and the one end of the connector is in said track channel, said operating part is operable and drives the track channel of the annular part to move, so that the connector is driven to move axially. 
         [0017]    Comparing with the current technology, possible benefits of the present disclosure may in some arrangements include: a clutch that can move optionally between the two positions is provided additionally for the power tool, in order to optionally rigidly connect at least one of the output and main shaft with the hammer, so that rotation transferring can be stably and effectively achieved when the power tool is in the drilling mode, percussion drilling mode or screwdriver mode, and so can impacting when in impacting mode. The above-said function switch mechanism is simple and stable in structure, low in manufacturing cost, convenient and easy in operation. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    The present disclosure is further detailed in combination with the drawings attached and embodiments hereinafter, wherein: 
           [0019]      FIG. 1  is the front view of the power tool of the disclosure. 
           [0020]      FIG. 2  is the internal view of the power tool of the disclosure. 
           [0021]      FIG. 3  is the structural view when the power tool of the disclosure is in the mode of the impact wrench function. 
           [0022]      FIG. 4  is the structural view when the power tool of the disclosure is in the mode of the drilling function. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]      FIGS. 1-4  show a power tool  100  as an embodiment of the disclosure. In this embodiment, the power tool  100  provide the functions of drilling and impact wrench. As shown in the  FIG. 1 , the power tool  100  comprises a horizontally situated housing  1 , a handle  6  forming an angle with the housing  1 , and a detachable battery pack  8  situated at the bottom of the handle  6 . At the front of the housing  1 , a tool chuck  52  is mounted to hold various working heads when the power tool achieves different functions (not shown in figures). For example, the tool chuck  52  is used to hold fastener head when the power tool achieves the function of the impact wrench, and to hold the spiral drill when the power tool achieves the function of the drilling. Trigger  9  is mounted on the handle  6 . Operator can press the trigger  9  to start the power tool  100 . Function switch  44  is mounted on the housing  1 . Operator can switch the function modes of the power tool  100  by move the function switch  44 . 
         [0024]      FIG. 2  shows the power tool  100 &#39;s working parts mounted in the housing  1 . As shown in  FIG. 2 , the working parts comprises motor  11  and motor shaft extending ahead of the motor  11  (not shown in the figures). According to this embodiment, the speed adjusting system  13  is a planetary gear speed adjusting system, of which the actual realization way is known to common technicians in the industry. So, this actual realization way is not described in detail here. When the motor  11  runs, the motor shaft drives the planetary gear speed adjusting system to run. Accordingly, the rotation output by the motor is transferred to the main shaft  24  connected with the output  22  of the planet gear speed adjusting system in some deceleration proportion. The output  22  is the endmost planet carrier of the planetary gear speed adjusting system. The main shaft  24  inserts this planet carrier in interference fit way to joint with the output  22  deadly. When the output  22  rotates, the main shaft  24  will follow such rotate. 
         [0025]    A mechanism used for achieving the function of the impact wrench is mounted at the front of the speed adjusting system  13 . The mechanism comprises a hammer  31  mounted on the main shaft  24 , a impact-spring  32  mounted between the hammer  31  and the output  22 , and the rolling ball V-shaped groove impact mechanism mounted between the hammer  31  and the main shaft  24 . This impact mechanism comprises an outer V-shaped groove  241  hollowly formed on the surface of the main shaft  24 , the rolling ball  25  (a steel ball in this embodiment) that can roll in the outer V-shaped groove  241 , and the inner V-shaped groove  312  formed on the hammer  31  for receiving the ball  25 . A pair of first teeth  311  are provided on the front surface of the hammer  31  in axial symmetry and protruding way. Gasket and washer are provided between the impact-spring  32  and the hammer  31 . At the front of the hammer  31 , anvil  51  is mounted. A pair of second teeth  511  are provided on the back surface of the anvil  51  (opposite to the hammer  31 ) in axial symmetry and protruding way. The working parts also comprise a working shaft  5  extending to the front of the housing  1 , and the chuck  52  mounted at the front of the working shaft in muff-coupling way. The anvil  51  and the working shaft  5  combines together as a whole. At the front of the working shaft  51 , receiving groove  512  is provided for receiving corresponding working heads when various functions are achieved and for holding and fastening by the tool chuck  52 . 
         [0026]    The function-adjusting mechanism provided between hammer  31 , main shaft  24  and speed adjusting system  13  is also a working part. It comprises clutch  41 , function switch  44  and connector  42 . Wherein, the clutch  41  is in a ring-like form, and is provided around the outer circumferential surface of output  22 . A round of outer annular groove  411  is provided on the outer circumferential surface of clutch  41 , one end of connector  42  is hooked to the inside of outer annular groove  411 , and the other end of the connector is provided on the housing  1  through connection by the function switch  44  for the operator to operate, move the function switch  44  so as to drive the connector  42  and clutch  41  successively to move back and forth along the axis of output  22 . For those of ordinary skill in the art, this is also practicable: directly connect a hinge pin with the function switch  44 , and pass through the housing  1  through the hinge pin to connect to the clutch  41 , which can then be driven to move back and forth. As for specifics of such connection, the function switch  44  is arranged to the housing  1  in a penetrating manner, including an operating part located on the housing  1  and a circular part located in the housing. The operating part can rotate around the longitudinal axis of working shaft  5  and drive the circular part to rotate. Some track channels are provided on the circular part, and include two straight channels parallel to the direction which is perpendicular to the longitudinal axis of working shaft  5 , and provided at intervals along the longitudinal axis of working shaft  5 , as well as a skewed channel connecting the above-said two straight channels. The other end of the said connector  42  is provided in a track channel. To be specific, it is in one of the two straight channels. In function conversion, after the operator stirs the operating part of function switch, the circular part will rotate according to the motion, and the track channels will also move according to the circular part  7  in a direction opposite to the other end of connector  42 . During the moving process of track channels, firstly, a straight channel connects with the other end of connector  42  and moves relative to the connector  42 , while connector  42  does not move axially; then, the skewed channel of track channels moves to the other end of connector  42 , and continues moving to drive the connector  42  to move axially till skewed channel moves to leave the said end, and the other straight channel moves to the position where the other end of connector  42  can be connected. Function switch  44  drives the connector  42  to move axially in the above-mentioned way. Yet for those of ordinary skill in the art, there are various ways to connect and control function switch and clutch  41 , apart from the above-said means. For instance, the function switch  44  can be radially traversed to the inside of outer annular groove  411  on the outer circumferential surface of clutch  411 , to directly drive the clutch  411  to move axially. The symmetrical part of the inner circumferential surface of clutch  41  radially bulges to form a pair of slide blocks  413 , which are disconnected in the middle, and depressed toward the clutch  41  to form an inner annular groove  415 , in which elastic ring  45  is provided. Correspondingly, the symmetrical part on the outer circumferential surface of output  22  is depressed radially to form a pair of slide grooves  221 , and two ring-like grooves are provided on the outer circumferential surface of output  22  and within the axial layout travel of slide groove  221 , which is vertical to and intersects with the ring-like grooves. They are respectively the first annular groove  223  relatively closer to one side of reducing gear system, and the second annular groove  225  relatively closer to one side of hammer  31 . The clutch  41  moves back and forth through slide blocks along the inner axis of slide groove  221  of output  22 , but cannot rotate around the output  22 . The main body of elastic ring  45  is provided in the inner annular groove  415  of clutch  41 , and moves axially on the outer circumferential surface of output  22  according to the clutch  41 . Moreover, when reaching the two ring-like grooves of output  22 , the elastic ring  45  will enter into them and locate along the two axial directions of output  22 , and when it locates at the first annular groove  223 , the clutch  41  lies in the first position, and when it at the second annular groove  225 , the clutch  41  the second position. This arrangement can help the operator to determine whether the clutch has reached the predetermined position or not, and fix the clutch  41  at the position to avoid any random slide except the operator manually moves it. 
         [0027]    A spline  417  is axially provided on the clutch  41  in front of hammer  31 . Meanwhile, a corresponding spline  317  is provided on the axial back end of hammer  31  which facing the clutch  41  so that the clutch  41  and spline  417  can be geared. When the elastic ring  45  is positioned at the first annular groove  223 , there is a certain space between the clutch  41  and hammer  31 , the spline parts of which are out of gear; when the elastic ring is positioned at the second annular groove  225 , the clutch  41  and hammer  31  fit together, with their respective spline parts geared. 
         [0028]      FIG. 3  shows the work by the power tool  100  to realize the function of impact wrench. In the process of realizing the function, when function switch  44  is adjusted to the position where the elastic ring  45  of clutch  41  is positioned at the first annular groove  223  of output  22 , the spline  417  of clutch  41  and spline  317  of hammer  31  are out of gear. Since the first teeth  331  of hammer  31  is geared with the second teeth  411  of anvil  41  due to the pressure by impact-spring  32 , the anvil  41  is restricted so that it can not move. When power tools work, main shaft  24  is rotated and driven by the motor shaft through speed adjusting system  13 , the hammer  31  is driven and rotates by the ball  25  clamped between inner V-shaped groove  312  and outer V-shaped groove  241 , As the anvil  41  also rotates follow that motion, it rapidly fasten nuts (not shown in figures) through working shaft  51 , the working head (not shown in figures) and tool chuck  52 . 
         [0029]    After the nut end surface contacts with the workpiece (not shown in figures) surface, resisting moment rapidly increases to a certain value to make the geared hammer  31  and anvil  41  blocked, and the anvil  41  stopped rotating. Yet, the main shaft  24  still rotates under the driving force of motor output shaft, which forces the ball  25  to roll along the grooves by overcoming the frictional force between itself and inner V-shaped groove  312  outer V-shaped groove  241 , to propel the hammer  31  to move to the direction of motor, making impact-spring  32  compressed. Thus, the hammer  31  is gradually axially move farther and farther from the anvil  41 . When the axial moving distance of hammer  31  exceeds the tooth height of the second teeth  411  of anvil  41 , that is to say, at the moment the hammer  31  and anvil  41  are out of gear, the main shaft  24  drives the hammer  31  to rotate, and make its first teeth  31  to glide over the second teeth  411  of anvil  41 . And at the moment of the gliding and on account of the effect by impact-spring  32 , the ball  25  returns to the original position again along the inner V-shaped groove  312  outer V-shaped groove  241 , the hammer  31  is pushed forward, and as the rotation of main shaft  24  accelerates to impact the second teeth  411  of anvil  41 , the anvil  41  continues moving along the rotating direction. As a result of the cycle, thread pieces are fastened under impact moment. 
         [0030]    In the process of realizing the above impact wrench function, the hammer  31  is required to impact the anvil  51  by intermittent rotation, making the working head (fastening head) to fasten nuts. However, in the process of realizing the drilling function, only the working head (spiral drill) is required to continue drilling, and the hammer  31  isn&#39;t required any more for intermittent impact. As shown in  FIG. 4 , when function switch  44  is adjusted to the position where the elastic ring of clutch  41  is positioned at the second annular groove  225  of output  22 , or the gearing position of the spline  417  of clutch  41  and spline  317  of hammer  31 , the power tool  100  is in the working state of drilling function realization. In drilling process, the hammer  31  tends to move toward motor  11  due to the gradually increasing resisting force suffered by working shaft  5 . At this time, since the clutch  41  restricts the hammer  31  to move backward axially, the first teeth  311  of hammer  31  always fits the second teeth  511  of anvil  51 . Meanwhile, the hammer  31 , anvil  41  and working shaft  51  move together along the rotating direction. Since the anvil  41  and hammer  31  can never be separated, or impact can never be formed between them, continuous drilling of the working head can be ensured. 
         [0031]    For the above-said implementing modes, it is especially important that in drilling function realization, the rotation outputted by the motor can reach the output  22  of speed adjusting system through deceleration, and then pass to the hammer  31  through the middleware clutch  41 . As a result, a rigid connection from the output  22  of speed adjusting system to hammer  31  for passing rotation is formed; since the main shaft  24  and output  22  of speed adjusting system are connected through interference fit, it can be said that a rigid connection between the main shaft  24  and hammer  41  is established. As for the past power tool  100 , when its impact wrench function is converted to the drilling function, the movable connection of the grooves and rolling ball system between the main shaft  24  and hammer  41  have to be relied on to pass rotation. 
         [0032]    For those of ordinary skill in the art, the clutch  31  can be optionally directly provided on the outer circumferential surface of main shaft  24 , where it can glide along the axial direction of main shaft  24 . In this embodiment, some of clutch  41  is connected with the main shaft  24  along the rotating direction in a relatively fixed mode, and some of the clutch  41  is optionally geared or separated from the hammer  31  under the help by the spline. As a result, a rigid connection from the main shaft  24  to hammer  41  is established under the drilling mode of power tool  100 . This embodiment is in the same clues as the above-said preferred implementing cases of this disclosure, and thus it is unnecessary to dwell on its details herein. The rotation output of the motor  11  is decelerated by the speed adjusting system and then passed to the hammer  31  by means of the rigid connected transmission. 
         [0033]    Also for those of ordinary skill in the art, the clutch  41  can be optionally rigid connected with the hammer  31  in a form other than spline gearing, or be relatively fixedly geared with the output  22  or main shaft  24  along the rotating direction in a way different from the slideway form of slide block. For example, clips and holes can be adopted for gearing, or lugs and grooves for gearing to realize optional and rigid connection between the clutch  41  and hammer  31 , the spline gearing can be adopted to realize the gearing between the clutch  41  and output  22  or main shaft  24 , etc. 
         [0034]    In other embodiments, when the anvil moves with the hammer, the function of automatic screwdriver can be correspondingly realized by adding a clutch mechanism between the planetary gear speed adjusting system of power tool and inner ball V-shaped groove impact structure, and the function of percussion drill can be correspondingly realized by adding a dynamic and static end tooth hammer structure (percussion mechanism) in front of the working shaft  5 . The above functions can be separately provided and integrated into a power tool by being combined with the function of impact wrench, and be provided repeatedly to form power tools with three or four functions. Since the above added functional structures are prior art, it isn&#39;t necessary to dwell on them herein.