Patent Publication Number: US-2010116073-A1

Title: Actuator with an anti-loose structure

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an actuator, and more particularly to an actuator with an anti-loose structure. 
     2. Description of the Prior Art 
     With the rapid development of technical industry, in order to meet the automation needs of the equipments (such as smoke exhausting window, automatic door, cabinet, satellite antenna, elevating wheelchair, hoisting hospital bed, drawing table, massage chair, traffic equipment, or elevating computer desk) an actuator was developed on the market. 
     Referring to  FIG. 1 , a conventional actuator  10  comprises a first tube  11  and a second tube  12 . The first tube  11  is movably mounted on the second tube  12 . A drive screw  13  is axially pivoted in the first tube  11  and provided with an axial driven nut  14 , a limit member  15 , a fixed sleeve  16 , and a sensing sleeve  17 . A drive gear  18  is mounted on the fixed sleeve  16 . The drive screw  13  is connected to the drive gear  18  and the power source through the fixed sleeve  16 . One end of the second tube  12  is fixed at one end of the driven nut  14 , so that the second tube  12  can be subjected to a push force to extend and retract on the first tube  11 . 
     Based on a further analysis of the above conventional actuator, it can be found that it still has the following disadvantages: 
     The fixed sleeve  16  (as shown in  FIG. 2 ) is screwed with the drive screw  13 , so that when the drive gear  18  is rotated clockwise, the fixed sleeve  16  will be driven by the drive gear  18  to rotate clockwise on the drive screw  13 , at this moment, the fixed sleeve  16  which is rotating clockwise will press against the limit member  15  upwards. However, when the drive gear  18  is rotated counterclockwise, the fixed sleeve will be driven by the drive gear  18  to rotate counterclockwise on the drive screw  13 , at this moment, the fixed sleeve  16  which is rotating counterclockwise will push the sensing sleeve  17 , so that the sensing sleeve  17  will be pressed against by the fixed sleeve  16  to deform or even fracture. The sensing sleeve  17  employs a sensor to perform displacement sensing operation, so that once the sensing sleeve  16  is damaged, the function of sensing displacement cannot be performed, thus affecting the normal operation of the actuator  10 . Therefore, it is necessary to disassemble the actuator  10  to repair or replace the damaged sensing sleeve  16 . However, although the damaged sensing sleeve  16  can be replaced, the above condition will continue to occur, thus causing the waste of repair time and material cost, which both weaken the customer trust in the actuator  10 . 
     The present invention has arisen to mitigate and/or obviate the afore-described disadvantages. 
     SUMMARY OF THE INVENTION 
     The present invention relates to an actuator with an anti-loose structure, which can utilize the anti-loose structure to avoid the uncountable movement of relevant members. 
     In order to achieve the above objective, the actuator with an anti-loose structure in accordance with the present invention comprises an actuator and an anti-loose structure. 
     The actuator includes at least two tubes and a drive assembly. One of the two tubes is movably mounted on the other of the two tubes. The drive assembly includes a drive screw, a driven nut and a drive gear. One end of the drive screw is pivoted to one of the tubes of the actuator. The drive gear and the driven nut are disposed on the drive screw. The other of the tubes of the actuator is disposed on the driven nut. 
     The anti-loose structure includes a first limit member and a second limit member. The first limit member is disposed on the drive screw of the drive assembly in such a manner that the first limit is located at one end of the drive gear, and the second limit member is disposed on the drive screw of the drive assembly in such a manner that the second limit member is locate at the other end of the drive gear. 
     Further analysis shows that the present invention has the following advantages: the drive gear of the drive assembly of the present invention is limited by the first limit member and the second limit member of the anti-loose structure, so that the members neighboring the drive gear can be prevented from being damaged due to the uncontrollable movement of the drive gear, thus extending the service life of the neighboring members of the drive gear. Therefore, it is not required to waste time on repair, and the material cost can be relatively saved, thus enhancing customer trust in actuator. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross sectional view of a conventional actuator; 
         FIG. 2  is a partial enlarged view of the conventional actuator of  FIG. 1 ; 
         FIG. 3  is a cross sectional view of an actuator in accordance with the present invention; and 
         FIG. 4  is a partial enlarged view of actuator in accordance with the present invention of  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will be clearer from the following description when viewed together with the accompanying drawings, which show, for purpose of illustrations only, the preferred embodiment in accordance with the present invention. 
     Referring to  FIGS. 3-4 , an actuator with an anti-loose structure in accordance with the present invention comprises an actuator  20  and an anti-loose structure  30 . 
     The actuator  20  includes a first tube  21 , a second tube  22  and a drive assembly  23 . 
     The first tube  21  is oppositely provided with an open end  211  and a closed end  212 . The second tube  22  is oppositely provided with an open end  221  and a closed end  222 . The second tube  22  is smaller than the first tube  21  in cross section. The second tube  22  is movably installed in the first tube  21  in such a manner that the open end  221  of the second tube  22  is opposite the open end  211  of the first tube  21 . The direction in which the second tube  22  is assembled to the first tube  21  is the same as the extending/retracting direction of the second tube  22  with respect to the first tube  21 . 
     The drive assembly  23  includes a drive screw  231 , a driven nut  232 , a fixed sleeve  233 , a sensing sleeve  234 , a drive gear  235  and a motor  236 . One end of the drive screw  231  is axially disposed on the closed end  212  of the first tube  21  of the actuator  20 , and the other end of the drive screw  231  extends toward the closed end  222  of the second tube  22  of the actuator  20 . The sensing sleeve  234 , the fixed sleeve  233  and the driven nut  232  are successively disposed on the drive screw  231 , and the drive gear  235  is mounted on the fixed sleeve  233 . The drive gear  235  is drivingly connected to the motor  236  to obtain the rotary power. In the present embodiment, the motor  236  serves as the power source, but the power source of the present invention is not limited to the motor, and it can also be other power devices as desired. One end of the driven nut  232  is coaxially opposite the open end  221  of the second tube  22  in such a manner that the open end  221  of the second tube  22  can be engaged on the driven nut  232 . When the drive gear  235  obtains power to drive the drive screw  231  to rotate in place through the fixed sleeve  233 , the driven nut  232  will move along the drive screw  231  to drive the second tube  22  to extend/retract with respect to the first tube  21 . 
     The anti-loose structure  30  includes a first limit member  31  and a second limit member  32 . The first limit member  31  is a bearing, and the second limit member  32  is a nut. The first limit member  31  is mounted on the drive screw  231  of the drive assembly  23  in such a manner that the first limit member  31  is located between the driven nut  232  and the fixed sleeve  233 . The second limit member  32  is locked on the drive screw  231  of the drive assembly  23  in such a manner that the second limit member  32  is located between the fixed sleeve  233  and the sensing sleeve  234 . By such arrangements, both ends of the fixed sleeve  233  are limited by the first limit member  31  and the second limit member  32 . 
     When the drive gear  235  rotates clockwise, the fixed sleeve  233  will be driven by the drive gear  235  to rotate clockwise on the drive screw  231 , at this moment, the fixed sleeve  233  which is rotating clockwise will be stopped and limited by the first limit member  31 . When the drive gear  235  rotates counterclockwise, the fixed sleeve  233  will be driven by the drive gear  235  to rotate counterclockwise on the drive screw  231 , at this moment, the fixed sleeve  233  which is rotating counterclockwise will be limited by the second limit member  32 . 
     As known from the abovementioned, under the condition that both ends of the fixed sleeve  233  are limited by the first limit member  31  and the second limit member  32 , even though the fixed sleeve  233  is driven by the drive gear  235 , it cannot be moved uncontrollably. Therefore, the fixed sleeve  233  can be prevented from pressing against the sensing sleeve  234 , thus avoiding the damage to the sensing sleeve  234 , and the user doesn&#39;t need to disassemble the actuator  20  to repair and replace the sensing sleeve  234 . 
     While we have shown and described various embodiments in accordance with the present invention, it is clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.