Patent Publication Number: US-7896097-B2

Title: Electric power tool

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a hand tool, and more particularly to an electric power tool capable of switching various operation modes by a single switch. 
     2. Description of the Related Art 
     Typically, a conventional electric power tool includes a motor, a planetary gear reduction mechanism, an impact mechanism, and a hammer mechanism. A shaft of the motor is connected to the planetary gear reduction mechanism to change the speed thereof, and the impact mechanism is connected to the planetary gear reduction mechanism. The conventional impact mechanism includes a shaft and an impact member. The shaft is driven by the planetary gear reduction mechanism. The shaft has slots thereon, in which balls are received. The impact member is fitted to the shaft through the balls. The impact member has two blocks on a top thereof. A spindle, which is connected to the shaft of the impact mechanism, has two arms interacted with the blocks of the impact member. In a normal condition, the shaft will drive the impact member and the spindle rotation together. Under a condition of a resistance on the spindle, the impact member will be reciprocated by the interaction of the blocks of the impact member and the arms of the spindle that the impact member will generate an impact effect, and we call it as “impact mode”. In the conventional electric power tool, a stopper is provided behind the impact member to stop the impact member moving backwards that no impact effect when the stopper behind the impact member. The stopper may be moved away to give a sufficient space behind the impact member that the impact member may provide impact effect. The detail structure and function of the impact mechanism are taught by U.S. Pat. No. 7,308,948. 
     Typically, the hammer mechanism is provided in front of the impact mechanism, which includes a first teeth disk and a second teeth disk, and the first teeth disk is fixed and the second teeth disk is free to rotate. The second teeth disk is connected to the spindle and rotated together with the spindle. A cam is provided behind the first teeth disk to move the first teeth disk to engage or disengage the second teeth disk. The hammer mechanism will generate a vibration effect when the teeth disks are engaged together. We call it as “hammer mode”. The detail structure and function of the hammer mechanism is taught by U.S. Pat. No. 6,142,242. 
     When both of the impact mechanism and the hammer mechanism are shut, the spindle is rotating in a maximum power, and we call it as “drill mode”. Recently, the electric power toll provides “driver mode”. In “driver mode”, the power is adjustable. 
     In the electric power toll of early time, there are two independent switches on the toll to control the impact mechanism and the hammer mechanism respectively. It is inconvenient to consumers. In recent time, however, there are electric power tool equipped with single switch to control all operation modes, for example U.S. Pat. No. 7,308,948. Because the stopper, which is the main device to switch “impact mode”, and the cam, which is the main device to switch “hammer mode” are far away from each other that the switch to control both modes usually has a complex structure. 
     SUMMARY OF THE INVENTION 
     The primary objective of the present invention is to provide an electric power tool, which may switch various operation modes by one switch. 
     The secondary objective of the present invention is to provide an electric power tool, which provides fewer elements for impact mode and hammer mode. 
     The third objective of the present invention is to provide an electric power tool, which provides a novelty switch for driver mode. 
     According to the objectives of the present invention, an electric power tool includes a switching member provided on a housing of the electric power tool for manipulation; a driving member, which is connected to the switch member to be turned in a predetermined angle, having a first driving portion and a second driving member on a side; a first driven member having a driven portion directly engaged with the first driving portion of the driving member that a turn of the driving member moves the first driven member; a second driven member having a driven portion directly engaged with the second driving portion of the driving member that a turn of the driving member moves the second driven member; an impact mechanism having an impact member for reciprocation, wherein the first driven member is located behind the impact member; and a hammer mechanism having a first teeth ring and a second teeth ring, wherein the first teeth ring is provided on the second driven member, and the second teeth ring is connected to a spindle of the electric power tool. 
     The switching member is switchable to an impact mode, a hammer mode, and a drill mode. When the switching member is switched to the impact mode, the driving member moves the first driven member away from the impact member to start the impact mechanism, and the driving member also move the second driven member to disengage the second teeth ring with the first teeth ring to shut the hammer mechanism. 
     When the switching member is switched to the hammer mode, the driving member moves the first driven member toward the impact member to shut the impact mechanism, and the driving member also move the second driven member to engage the second teeth ring with the first teeth ring to start the hammer mechanism. 
     When the switching member is switched to the drill mode, the driving member moves the first driven member toward the impact member to shut the impact mechanism, and the driving member also move the second driven member to disengage the second teeth ring with the first teeth ring to shut the hammer mechanism. 
     For another objective of the present invention, the electric power tool includes a hammer mechanism and an impact mechanism. The impact mechanism has an impact member for reciprocation. The hammer mechanism has a first teeth ring and a second teeth ring, wherein the second teeth ring is provided on the impact member. 
     For the other objective of the present invention, the electric power tool includes a planetary gear reduction mechanism, which has a casing, in which a torque ring is mounted. A plurality of pins are inserted into the casing in association with a front end side of the torque ring. A driving member may push the pins to press the torque ring. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a preferred embodiment of the present invention; 
         FIG. 2  is an exploded view of the preferred embodiment of the present invention, showing the planetary gear reduction mechanism and the torque adjusting mechanism; 
         FIG. 3  is an exploded view of the preferred embodiment of the present invention, showing the switch mechanism, the hammer mechanism, and the impact mechanism; 
         FIG. 4  is a sectional view of the preferred embodiment of the present invention; 
         FIG. 5  and  FIG. 6  are perspective views of the driving member of the switch mechanism of the preferred embodiment of the present invention; 
         FIG. 7  is a perspective view of the first driven member of the switch mechanism of the preferred embodiment of the present invention; 
         FIG. 8  is a perspective view of the second driven member of the switch mechanism of the preferred embodiment of the present invention; 
         FIG. 9  is a perspective view of the impact member of the impact mechanism of the preferred embodiment of the present invention; 
         FIG. 10  is a sectional view in part of the preferred embodiment of the present invention, showing the power toll in the hammer mode; 
         FIG. 11  is a sectional view in part of the preferred embodiment of the present invention, showing the power toll in the drill mode; 
         FIG. 12  is a sectional view in part of the preferred embodiment of the present invention, showing the power toll in the driver mode; 
         FIG. 13  is a sectional view in part of the preferred embodiment of the present invention, showing the action of the torque adjusting mechanism in the driver mode; and 
         FIG. 14  is a sectional view in part of the preferred embodiment of the present invention, showing the power toll in the impact mode. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As shown in  FIG. 1  to  FIG. 4 , an electric power toll of the preferred embodiment of the present invention includes a housing  10 . The housing  10  has a handle  12  and a machine room  14 . A battery  16  is mounted on a bottom of the handle  12 , and a trigger  18  is provided on the handle  12 . In the machine room  14 , a motor  20 , a planetary gear reduction mechanism  26 , a switch mechanism  70 , an impact mechanism  120 , a hammer mechanism  142 , a torque fixing mechanism  148 , and a torque adjusting mechanism  162  are provided. 
     As shown in  FIG. 4 , the motor  20  is mounted in a rear of the machine room  14 , which has a spindle  22  and a gear  24  on the spindle  24 . 
     As shown in  FIG. 2 , the planetary gear reduction mechanism  26  includes a casing  28 , in which a speed ring  36 , three first planetary gears  38 , a first rotary base  40 , a support base  42 , a pad  44 , a torque ring  46 , three second planetary gears  48 , and a second rotary base  50 . The casing  28  consists of a plate  30 , a first housing  32 , and a second housing  34 . The first housing  32  is a tubular member, in which the speed ring  36 , the first planetary gears  38 , and the first rotary base  40  are received. The speed ring  36  has teeth on an inner side, and the first planetary gears  38  are received in the speed ring  36  to be engaged with the teeth thereof. The spindle  22  of the motor  20  passes through a space within the first planetary gears  38 , and the gear  24  engages the first planetary gears  38 . The first rotary base  40  has three pins  52  on a side to connect the first planetary gears  38  respectively, and a shaft  54  on the other side. The support base  42 , which is received in the first housing  32  at an opposite side, has a hole at a center and a bearing  56  mounted in the hole to be fitted to the shaft  54  of the first rotary base  40 . The second housing  34  is open at one end and has an end wall  58  at the other end. The end wall  58  has a cylinder  60  at a center thereof. The open end of the second housing  34  is connected to the first housing  32 . In the second housing  34 , the torque ring  46 , the second planetary gears  48 , and the second rotary base  50  are received. The second planetary gears  48  are received in the torque ring  46  and engaged with teeth on an inner side of the torque ring  46 . The shaft  54  of the first rotary base  40  passes through a space within the second planetary gears  48  and engages thereto. The second rotary base  50  has three pins  62  on a side connecting the second planetary gears  48  respectively, and a post with a bore  63  therein on the other side. The second housing  34  has a bearing  64  in a hole of the cylinder  60  to connect the post of the second rotary base  50 . A speed switch  66  is provided on the housing  10  to control the speed ring  36  of the planetary gear reduction mechanism  26  that planetary gear reduction mechanism  26  may provide two levels of speed. Two bars  68  are provided on the second housing  34 . 
     As shown in  FIG. 3 , the switch mechanism  70  includes a driving member  72 , a first driven member  74 , a second driven member  76 , and a switching member  78 . As shown in  FIG. 5  and  FIG. 6 , the driving member  72  is a disk-like member having a bore at a center, and a connecting portion  100  and two guiding slots  80  at an edge. The connecting portion  100  connects the driving member  72  to the switching member  78 , and on a sidewall of each guiding slot  80  has two recesses  82 . The driving member  72  has a first driving portion  84  and a second driving portion  86  on a side thereof. The first driving portion  84  and the second driving portion  86  are concentric, and the first driving portion  84  is located at outer side and the second driving portion  86  is located at inner side. The first driving portion  84  has four teeth, each of which has a slope  86 , a first level  88 , a slope  90 , and a second level  92 . The second driving portion  94  has six teeth, each of which includes a slope  96  and a top level  98 . The bars  68  pass through the guiding slots  80  of the driving member  72  that operating the switching member  78  may rotate the driving member  72  in a preset range. The recesses  82  on the sidewall of the guiding slots  80  locate the driving member  72  at some predetermine positions that the power tool may be switched to different operation modes. As shown in  FIG. 7 , the first driven member  74  has a central bore, four slots  102  on a sidewall of the central bore, and an annular rim  104  at an end of the central bore. The first driven member  74  is provided with a driven portion  106 , which has six teeth, on a side thereof around the central bore, and two recesses  108  on a circumference thereof. The bars  68  are received in the recesses  108  of the first driven member  74  that the driven portion  106  of the first driven member  74  is engaged with the first driving portion  84  of the driving member  72 . A diameter of the second driven member  76  is about equal to the second driving portion  94  of the driving member  72 . As shown in  FIG. 8 , the second driven member  76  has a central bore also, and four guiding blocks  110  on a circumference thereof. The second driven member  76  is received in the central bore of the first driven member  74  with the guiding blocks  110  engaged with the slots  102  and stopped by the rim  104 . The second driven member  76  is provided with a driven portion  112 , which has six teeth, on a side thereof to be engaged with the second driving portion  94  of the driving member  72 . The cylinder  60  of the second housing  34  of the planetary gear reduction mechanism  26  is inserted into the central bore of the second driven member  76 . A support plate  114  is fixed to distal ends of the bars  68 . Six springs  116  are provided between the support plate  114  and the first driven member  74  to urge the first driven member  74 , together with the second driven member  76 , toward the driving member  72 . Between the first driven member  74  and the second driven member  76  is provided with four springs  118  also. 
     As shown in  FIG. 3 , the impact mechanism  120  includes a shaft  122 , two balls  124 , an impact member  126 , a spring  128 , and a spindle  130 . The shaft  122  has teeth adjacent to an end thereof to be inserted through the central bores of the first driven member  74 , the second driven member  76  and the driving member  72 , and inserted into a bore on the cylinder  60  of the second housing  34  to be engaged with the second planetary gears  48 . The shaft  122  is provided with two guiding slots  134 . The impact member  126  has a through hole, in which the shaft  122  is received, two blocks  136  on a top thereof, and two guiding recesses  138  on a sidewall of the through hole. The balls  124  are received in the guiding slots  134  of the shaft  122  and the guiding recesses  138  of the impact member  126 . The spring  128  is fitted to the shaft  122  with an end urging the impact member  126 . The spindle  130 , which is connected to an end of the shaft  122  out of the impact member  126 , has two arms  140 . The impact mechanism  120  as described above is as same as the conventional device that when the spindle  130  is resisted by an external force, the impact member  126  will move backward because of the actions of the balls  124 , the guiding slots  134 , and the guiding recesses  138 , and the arms  140  will cross over the blocks  136  to allow the impact member  126  move forward again because of the spring  128 . For a reciprocation of the impact member  126 , the impact mechanism  120  may provide the impact effect. 
     As shown in  FIG. 3 , the hammer mechanism  142  includes a first teeth ring  144  on a front end the second driven member  76  and a second teeth ring  146  on a rear end of the impact member  126  (as shown in  FIG. 9 ). As the second driven member  76  is driven toward the impact member  126  by the driving member  72 , the first teeth ring  144  will engage the second teeth ring  146  that will generate a vibration of hammer effect. 
     As shown in  FIG. 2 ,  FIG. 6 , and  FIG. 12 , the torque fixing mechanism includes six teeth  150  on a front annular end of the torque ring  46 . The second housing  34  is provided with four bores  152  on the end wall  58  thereof. In each of the bores  152 , a pin  154  and a spring  156  are mounted. The pin  154  has inner ends aligned with the front annular end of the torque ring  46  and outer ends left out of the second housing  34 . The driving member  72  is provided with four recesses  158  on a side opposite to the driving portions  84 ,  86 , and four position portions  160 , which are shallower recesses, between each of the neighboring two recesses  158 . When the driving member  72  is turned to a specific operation mode other than the driver mode, the outer ends of the pins  154  will enter the specific position portions  160 , and the driving member  72  will press the pins  154  to have the inner ends thereof pressing the front annular end of the torque ring  46  and stopped by the teeth  150  that the torque ring  46  is fixed and the planetary gear reduction mechanism  26  outputs a maximum power. When the driving member  72  is turned to a position where the pins  154  enter the recesses  158 , the pin will no longer press the torque ring  46 , and the torque ring  46  is free to rotate that the planetary gear reduction mechanism  26  outputs a minimum power. 
     As shown in  FIG. 3  and  FIG. 13 , the torque adjusting mechanism  162  includes two levers  164  provided on the second housing  34  and pins  168  and springs  170  mounted in two bores  166  of the second housing  34 . The torque ring  46  has teeth  172  on a circumference thereof. The levers  164  may move the pins  168  downward to press the torque ring  46 . Two posts  174  pass through the support plate  114  and the first driven member  74  and touch ends of the levers  164  respectively. Each post  174  is provided with a teethed piece  176  on the other end. A wheel  178  is pivoted on the front of the machine room  14 , which has teeth  178  on an inner side engaged with the teethed pieces  176  that turn of the wheel  178  may move the posts  174 , and the posts  174  will tilt the levers  174  to move the pins  168  downward. The wheel  178  may adjust the pressure of the pins  168  on the torque ring  46  to adjust the torque output. 
     As shown in  FIG. 1 , the housing  10  is provided with four icons beside the switching member  78 , which represents, from left to right, hammer mode  180 , drill mode  182 , driver mode  184 , and impact mode  186 . When one operates the switching member  78  to the hammer mode  180 , as shown in  FIG. 10 , the first driving portion  84  of the driving member  72  has the first level  88  touching the driven portion  106  of the first driven member  74  to move the first driven member  74  toward the impact member  126 . In the mean time, the second driving portion  94  of the driving member  72  has the top level  98  touching the driven portion  112  of the second driven member  76  to move the second driven member  76  toward the impact member  126  and to engage the first teeth ring  144  on the second driven member  76  with the second teeth ring  146  on the impact member  126 . In such condition, the impact member  126  is stopped by the first driven member  74  so that the impact mechanism  120  is shut, and the first teeth ring  144  and the second teeth ring  146  are engaged so that the hammer mechanism  142  is started. As a result, the spindle  130  is vibrated to have the hammer effect. 
     Next, when the switching member  78  is switched to the drill mode  182 , as shown in  FIG. 11 , the first driving portion  84  of the driving member  72  has the second level  92  touching the driven portion  106  of the first driven member  74  to move the first driven member  74  toward the impact member  126 . In the mean time, the top levels  98  of the second driving portion  94  of the driving member  72  leave the driven portion  112  of the second driven member  76  to move the second driven member  76  backward and to disengage the first teeth ring  144  with the second teeth ring  146 . In such condition, the impact member  126  is still stopped by the first driven member  74  so that the impact mechanism  120  is shut, and the first teeth ring  144  and the second teeth ring  146  are disengaged so that the hammer mechanism  142  is shut also. As a result, the spindle  130  is simply rotating to have the drill effect. 
     It has to be mentioned that, in the drill mode  812 , the impact mode  180 , and the hammer mode  186 , the pins  154  of the torque fixing mechanism  148  are received in the position portions  160  of the driving member  72  that the pins  154  will press the teeth  510  of the torque ring  46 . As a result, the motor  20  has a maximum torque output. While the switching member  78  is switched to the driver mode  184 , as shown in  FIG. 12 , the driving member  72  has the second level  92  of the first driving portion  84  touching the driven portion  106  of the driven member  74 , and the slope  96  of the second driving portion  94  touching the driven portion  112  of the second driven member  76 . In such condition, both of the impact mechanism  120  and the hammer mechanism  142  are shut. Besides, the recesses  158  of the driving member  72  are moved to positions behind the pins  154  that the pins  154  are no longer pressing the torque ring  46 , and the torque ring  46  are free to rotate. In such condition, the torque output is minimum. In the driver mode  184 , as shown in  FIG. 13 , one may turn the wheel  178  on the housing  10  to move the posts  174  and tilt the levers  164 . The tilting angles of the levers  164  will affect the pressure of the pins  168  pressing the torque ring  46  that may adjust the torque output. 
     As shown in  FIG. 14 , when the switching member  78  is switched to the impact mode  186 , the teeth of the first driving portion  84  of the driving member  72  leave the driven portion  106  of the first driven member  74  to move the first driven member  74  away from the impact member  126  that there is a sufficient space behind the impact member  126 , and the impact mechanism  120  is started. In the mean time, the second driving portion  94  of the driving member  72  leave the driven portion  112  of the second driven member  76  to move the second driven member  76  away from the impact member  126  to disengage the first teeth ring  144  with the second teeth ring  146  that the hammer mechanism  142  is shut. In the impact mode  186 , the impact member  126  of the impact mechanism  120  is reciprocating to provide the impact effect. 
     The main characters of the present invention include switching hammer mode, drill mode, driver mode, and the impact mode only by the switching member. Besides, the second teeth ring  146  of the hammer mechanism  142  is provided on the rear end of the impact member  126  of the impact mechanism  120 , and the first teeth ring  146  is provided on the second driven member  76  that the driving member  72  may directly control the second driven member  76  to start or shut the hammer mechanism  142  without the complex control mechanism in the conventional device. The extra advantage of above is that there is one element less in the present invention because the second teeth ring  146  is provided on the rear end of the impact member  126 . Therefore, the length of the present invention may be shortened. The least character of the present invention is that we use the front end side of the toque ring  46  to be the position of controlling the start or shut of the torque adjustment, and the circumference of the torque ring  46  to be the position of adjusting the torque. The separated control positions on the torque ring make the torque adjustment more precisely.