Abstract:
An actuator comprises a motor that drives a screw to rotate through a pulley mechanism and a reduction mechanism. The actuator is advantageous by easy assembly, easy replacement of the reduction mechanism and easy reconfiguration of the motor and the reduction mechanism.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Technical Field 
         [0002]    The present invention relates to actuators. 
         [0003]    2. Description of Related Art 
         [0004]      FIG. 1  depicts a conventional linear actuator, wherein a motor  1  outputs a rotational force through a reduction mechanism  2  to a screw  3  so that the screw  3  rotates and in turn drives a screw holder  4  coupled therewith to shift along a rail  5 . 
         [0005]    However, the aforementioned conventional actuator has some defects. 
         [0006]    First, the motor  1  has a transmission shaft that is configured as being perpendicular to the screw  3  with the reduction mechanism  2  connected therebetween. Therefore, such conventional actuator requires a relatively large installment area, thus being inferior in spacial flexibility. 
         [0007]    Besides, the reduction mechanism  2  is substantially a gearbox collocated therein with a plurality gears that have a predetermined gear ratio so as to give an expected reduction ratio. These molded and fixedly collocated gears in the gearbox cannot be re-collocated or replaced for altering the given reduction ratio of the reduction mechanism  2 , thus being inferior in mechanical flexibility. 
       SUMMARY OF THE INVENTION 
       [0008]    One objective of the present invention is to provide an actuator that is adaptable to even a relatively narrow installation area. 
         [0009]    Another objective of the present invention is to provide an actuator that is easy to be assembled. 
         [0010]    Another objective of the present invention is to provide an actuator whose reduction mechanism is replaceable so as to give different reduction ratios. 
         [0011]    Another objective of the present invention is to provide an actuator whose pulleys are easy to be assembled and positioned and serve to belt is automatically tensed as soon as the pulleys are assembled, thereby eliminating additional needs of idler pulleys for tensing the belt. 
         [0012]    Another objective of the present invention is to provide an actuator wherein a configuration of its reduction mechanism and motor is convertible. 
         [0013]    To achieve these and other objectives of the present invention, the disclosed actuator primarily comprises: 
         [0014]    a motor, outputting a rotational force to a pulley mechanism that in turn transfers the rotational force to a reduction mechanism so that the reduction mechanism transfers the rotational force to a screw positioned in an outer cover, wherein the pulley mechanism comprises: 
         [0015]    a central shaft coupled with the reduction mechanism and assembled with a driven pulley of a pulley set, in which the driven pulley is settled in a front cover and a belt winds around the driven pulley; 
         [0016]    a driving shaft of the motor arranged parallel to the screw and assembled with a driving pulley of the pulley set, in which the driving pulley is settled in the front cover and the belt also winds around the driving pulley so that the belt is tensed as receiving a lateral pulling force, and in which the motor has a housing affixed to the front cover; and 
         [0017]    a rear cover, combined with the front cover so as to jointly enclose the pulley set. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    The invention as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein: 
           [0019]      FIG. 1  is a schematic drawing of a conventional actuator; 
           [0020]      FIG. 2  is a perspective view of an actuator of the present invention; 
           [0021]      FIG. 3  is an assembled sectional view of the actuator of the present invention; 
           [0022]      FIG. 4  is a disassembled sectional view of the actuator of the present invention; 
           [0023]      FIG. 5  provides a first configuration of the actuator of the present invention wherein a motor is settled below a reduction mechanism; 
           [0024]      FIG. 6  provides a second configuration of the actuator of the present invention wherein the motor is settled at left of the reduction mechanism; 
           [0025]      FIG. 7  provides a third configuration of the actuator of the present invention wherein the motor is settled on the reduction mechanism; and 
           [0026]      FIG. 8  provides a fourth configuration of the actuator of the present invention wherein the motor is settled at right of the reduction mechanism. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0027]    While a preferred embodiment is provided herein for illustrating the concept of the present invention as described above, it is to be understood that the components in these drawings are made for better explanation and need not to be made in scale. 
         [0028]      FIG. 2  apparently describes an actuator of the present invention. As can be seen in the drawing, the actuator comprises a motor  10 , a pulley mechanism  20 , a reduction mechanism  30 , a screw  40  (shown in  FIG. 3 ), an outer cover  50 , and a shiftable seat  60 . The motor  10  outputs a rotational force to the screw  40  through the pulley mechanism  20  and the reduction mechanism  30  so that the screw  40  are driven by the rotational force to shift the shiftable seat  60  along the screw  40 . 
         [0029]      FIG. 3  is an assembled sectional view of the actuator of the present invention. Accordingly, the outer cover  50  comprises a front positioning-seat  51  and a rear positioning-seat  52  that position two ends of the screw  40 . Bearings  511 ,  521  provided at the two ends of the screw  40  for ensure stable rotation of the screw  40  are settled in the front positioning-seat  51  and a rear positioning-seat  52 , respectively. The rear positioning-seat  52  is composed of a first member  522  and a second member  523  that face each other to embrace and position the bearing  521  therebetween. Each of two side plates  53 ,  54  has two ends inlaid in the front positioning-seat  51  and a rear positioning-seat  52 , respectively. A screw seat  41  is mounted on the screw  40  and the shiftable seat  60  is then mounted on the screw seat  41  while side walls of the shiftable seat  60  are passed through by the side plates  53 ,  54 . 
         [0030]    As for the reduction mechanism  30 , it is substantially a gearbox  33  collocated therein with a plurality gears that have a predetermined gear ratio so as to give an expected reduction ratio. Such reduction mechanism  30  is well known in the art and will not be discussed in great detail herein. The reduction mechanism  30  further has a power-outputting shaft  31  connected with the screw  40  through a coupling  32 . 
         [0031]    The pulley mechanism  20  includes a front cover  21 , a rear cover  22  combined with the front cover  21 , and a pulley set  23  deposited between the front cover  21  and the rear cover  22 . The front cover  21  is affixed to the gearbox  33  of the reduction mechanism  30 . The pulley set  23  includes a driving pulley  235 , a driven pulley  231 , and a belt  236  connecting the driving pulley  235  and the driven pulley  231  A central shaft  234  rotatably holds a center of the driven pulley  231  and a bearing  232  for ensuring stable rotation of the central shaft  234  is positioned between the front cover  21  and the rear cover  22 . The central shaft  234  passes through a hole  212  on the front cover  21  and is further coupled with a gear  237  so as to transfer its rotational force into the reduction mechanism  30 . The driving pulley  235  is mounted on a driving shaft  11  of the motor  10  and wound by the belt  236 . The motor  12  is affixed to the front cover  21  at a housing  12  thereof. The rear cover  22  is fixedly combined with the front cover  21  by a fastener  25  so that the front and rear covers  21 ,  22  enclose and hold the pulley set  23 . 
         [0032]    It can be observed in  FIGS. 2 and 3  that the driving shaft  11  of the motor  10  is parallel to the screw  40 . The motor  10  is set adjacent to the pulley mechanism  20  so as to allow the actuator to be installed in a relatively narrow area. 
         [0033]      FIG. 4  illustrates how the pulley mechanism  20  is assembled. After mounted with the driven pulley  231 , the bearing  232  and the gear  237 , the central shaft  234  is received in the front cover  21  and wound by the belt  236 . Then the driven shaft  11  is mounted with the driving pulley  235  and received the hole  211  of the front cover  21 . After wound around the driving pulley  235 , the belt  236  is tensed under a lateral pulling force. At last, the motor  10  is affixed to the front cover  21  and the rear cover  22  is combined with the front cover  21  so that the pulley mechanism  20  is assembled. 
         [0034]    Thereby, the pulleys of the disclosed actuator are easy to be assembled and positioned while the belt is automatically tensed around the pulleys as soon as the pulley mechanism  20  is assembled, thereby eliminating additional needs of idler pulleys for tensing the belt. Furthermore, the pulley mechanism  20  can be easily disassembled by reversely conducting the aforementioned steps, thereby allowing a user to replace the reduction mechanism  30  with another one providing a different reduction ratio as the present one provides. 
         [0035]    Referring to  FIGS. 5 to 8 , while the motor  10  is coupled to the reduction mechanism  30  by means of the pulley mechanism  20 , by differently orienting the pulley mechanism  20 , the motor  10  can be set below or on, or at right or left of the reduction mechanism  30 , resulting in enhanced adaptability of the disclosed actuator to satisfy various mechanical arrangements. 
         [0036]    Although the particular embodiment of the invention has been described in detail for purposes of illustration, it will be understood by one of ordinary skill in the art that numerous variations will be possible to the disclosed embodiments without going outside the scope of the invention as disclosed in the claims.