Patent Publication Number: US-2010126807-A1

Title: Screw elevator

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a screw elevator, and more particularly to a screw elevator which is driven to move using a screw with a length that is half of the travel of the elevator. 
     2. Description of the Prior Art 
     A conventional screw elevator, as disclosed in Taiwan Patent No. 1296606, entitled “two-way screw drive mechanism for an elevator”, is provided with a screw and a power unit that are both placed at one side of an elevator car. The power unit includes a motor and a deceleration mechanism and is directly connected with the elevator car. The nut is installed in the deceleration mechanism, and the screw is fixed on the beam structure above the elevator car. When being actuated, the motor will output power to the nut through the deceleration mechanism, so that the nut will move along the screw to drive the elevator car to move synchronously. Furthermore, due to the limitation of the guide shoes installed on the elevator car, the elevator car will linearly move upwards and downwards along the screw. 
     In the above conventional screw elevator design, the screw and the motor are disposed at a single side of the elevator car, so that when the motor drives the elevator car to move upwards and downwards, the drive force from the motor will act on the single side of car, thus producing a torque on the car. As a result, the car is likely to deform due to the torque, thus affecting the smoothness of the movement of the elevator. In addition, not only does the space of movement of elevator provide the space for the arrangement of the guide rails, but also extra space is needed for installing the screw. Therefore, the difficulty of design and the cost are correspondingly increased. Furthermore, in such a design, the elevator car is designed to directly move on the screw, so that the length of the screw is the travel of the elevator car. Hence, it is found that the screw is too long, thus increasing the difficulty of production. Additionally, since the power unit must employ the deceleration mechanism to obtain the relatively large torque and proper rotating speed to drive the nut, the use and arrangement of the deceleration mechanism not only increases the cost but occupy the space of movement of the elevator. 
     The present invention has arisen to mitigate and/or obviate the afore-described disadvantages. 
     SUMMARY OF THE INVENTION 
     The primary objective of the present invention is to provide a screw elevator, which employs a power unit to drive the car to move upwards and downwards, wherein the cable is combined at the center of the top of the car, which is just the center of gravity of the car, so that although the principle of screw is applied, the car is subjected to a relatively small torque and shares the pulling fore and weight evenly, thus making the overall elevator more durable and the upward/downward movement of the elevator relatively smooth. 
     The secondary objective of the present invention is to provide a screw elevator in which the screw is installed within the space of the counterweight guide rails without providing extra installation space, thus making the overall structure layout and design relatively simple and reduce the design and construction cost. 
     The third objective of the present invention is to provide a screw elevator in which the length of the screw is just half of the total travel of the car, so that the production of the screw elevator of the present invention is more simplified, and the travel of the screw elevator of the present invention is relatively long, thus widening the application range. 
     The fourth objective of the present invention is to provide a screw elevator in which the power unit includes a motor which is interiorly provided with a motor rotor in which is provided a driving nut to be screwed on the screw, so that the screw elevator of the present invention doesn&#39;t require a complicated deceleration mechanism, thus having the advantages such as lower cost of parts, occupying less space, simple design and easy to install. 
     In order to solve the above technical problems, a screw elevator in accordance with the present invention comprises a pair of counterweight guide rails, a pair of deflection wheels, a counterweight frame, a screw, a power unit, a cable, a car and a car guide rail. The counterweight guide rails are disposed on a fixed wall surface. The deflection wheels are disposed above the counterweight guide rails. The counterweight frame is provided with a traction wheel at a top thereof and further provided with an inner counterweight body. The screw has one upper end fixed at the bottom of the counterweight frame. The power unit is foxed on a wall surface and includes a motor that is assembled with the screw, and the motor is interiorly provided with a motor rotor which is interiorly provided a driving nut to be screwed on the screw, the motor rotor is provided to drive the driving nut to rotate so as to drive the screw to move. The cable has one end fixed at a fixing position above the pair of counterweight guide rails, and the other end of the cable is finally connected to the car after being wound around the traction wheel and straddled over the deflection wheels, and the car is disposed under the deflection wheels and connected to the cable. The car guide rail is disposed on a fixed wall surface parallel to the fixed wall surface fixed with the pair of counterweight guide rails for guiding movement of the car. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a screw elevator in accordance with the present invention; 
         FIG. 2  is a schematic view illustrating how the cable is connected in accordance with the present invention; 
         FIG. 3  is a perspective view of a power unit for the screw elevator in accordance with the present invention; 
         FIG. 4  is a cross-sectional view of the power unit for the screw elevator in accordance with the present invention; 
         FIG. 5  is a perspective view of a screw elevator in accordance with a second embodiment of the present invention; 
         FIG. 6  is a perspective view of a power unit for the screw elevator in accordance with the second embodiment of the present invention; and 
         FIG. 7  is a cross-sectional view of the power unit for the screw elevator in accordance with the second embodiment of the present invention. 
     
    
    
     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. 
     A screw elevator in accordance with a preferred embodiment of the present invention comprises a pair of counterweight guide rails  10 , a beam frame  20 , a counterweight frame  30 , a screw  40 , a power unit  50 , a cable  60 , a car  70  and a car guide rail  80 . 
     The pair of counterweight guide rails  10  is disposed on a fixed wall surface by at least one guide rail bracket  11 . 
     The beam frame  20  is an H-shaped structure made of angle steel. The beam frame  20  is disposed above and connected to the counterweight guide rails  10 . The beam frame  20  is provided with a pair of deflection wheels  21 . 
     The counterweight frame  30  is located between the pair of counterweight rails  10  by two guide shoes  31 . The counterweight frame  30  is provided at the top thereof with a traction wheel  32  and further provided with an inner counterweight body  33 . The counterweight frame  30  is provided at the bottom thereof with a fixing base  34  to be combined with a screw  40 . 
     The screw  40  has an upper end to be fixed on the fixing base  34  at the bottom of the counterweight frame  30  and screwed with a fixing nut  41 , and a lower end to be disposed at the lower end of the pair of counterweight guide rails  10 , and at the lower end of the pair of counterweight guide rails  10  is further disposed a fixing base  300 . The screw  40  is fixed on the fixing base  300  and screwed with another fixing nut  42 . The two fixing nuts  41 ,  42  at two ends of the screw  40  each are equipped with a rubber mat  43 . 
     The power unit  50  is fixed on a wall surface and includes a motor  51  which is assembled with the screw  40  and disposed between two ends of the travel of the counterweight frame  30 . The counterweight frame  30  moves along the screw  40  to drive the car  70  to move to both ends of the travel of the counterweight frame  30 . The motor  51  is a power source torque motor  51 . 
     The motor  51 , as shown in  FIGS. 3-4 , is interiorly provided with a motor rotor  511 . When the motor  51  is electrified to drive the motor rotor  511  to rotate, the motor rotor  511  will drive a driving nut  512 , which is disposed in the motor rotor  511  and screwed on the screw  41 , to rotate. Consequently, the driving nut  512  will then drive the screw  40  to move. 
     The cable  60  has one end disposed on the beam frame  20  above the counterweight guide rails  10 , and the other end of the cable  60  is finally connected to the car  70  after being wound around the traction wheel  32  and straddled over the deflection wheels  21 . The cable  60  is fixed to the car  70  by a cable coupler  61 . 
     The car  70  is disposed under the deflection wheels  21  and connected to the corresponding end of the cable  60 . The cable  60  is disposed at the center of the top of the car  70 . 
     The car guide rail  80  is disposed on a fixed wall surface parallel to the wall surface fixed with the counterweight guide rails  10  by at least one guide rail bracket  81  and provided for guiding the movement of the car  70 . The car  70  is connected to the car guide rail  80  by a guide shoe  82 . 
     When the car  70  is to be moved, the motor  51  of the power unit  50  will be electrified to drive the motor rotor  511  to rotate, next the driving nut  512  will be rotated to drive the screw  40  to move, and then the counterweight frame  30  will move with the screw  40  between the counterweight guide rails  10 . The cable  60  combined with the counterweight frame  30  includes three sections that are a first section  62 , a second section  63  and a third section  64 . The first section  62  is from the position where the cable  60  is disposed on the beam frame  20  to the traction wheel  32 , the second section  63  is from the traction wheel  32  to the deflection wheels  21 , and the third section  64  is from the deflection wheels  21  to the car  70 . When the power unit  50  drives the screw  40  to move a certain distance, the first section  62  and the second section  63  of the cable  60  will also cooperatively move the same certain distance, but the third section  64  will move a distance that is two times as long as the distance that the screw  40  is moved. 
     In a power unit  50  in accordance with another embodiment of the present invention, as shown in  FIGS. 5-7 , the motor  51  employs the motor rotor  511  and the driving nut  512  to drive the screw  40 , and the driving nut  512  is equipped with a sleeve  513  in such a manner that when the motor  51  needs maintenance and repair, the driving nut  512  and the sleeve  513  can be disconnected for maintaining and repairing the motor  51  only without disassembling the screw  40 , thus facilitating maintenance and repair. 
     The present invention has the following advantages: 
     1. The power unit  50  drives the car  70  to move upwards and downwards by using the cable  60  combined at the center of the top of the car  70 , that is the center-of-gravity of the car  70 , so that although the principle of screw is employed, the car  70  is subjected to a relatively smaller torque and shares the pulling force and weight evenly, thus making the whole elevator durable and the upward/downward movement of the elevator smooth. 
     2. The screw  40  is installed within the space of the counterweight guide rails  10  without providing extra installation space, so that the overall structure layout is relatively simple and the design and manufacturing cost can be consequently reduced. 
     3. The length of the screw  40  is just half of the total travel of the car  70 , so that the screw  40  is relatively short, thus simplifying the production, and the travel of the screw elevator of the present invention is relatively long, thus widening the application range. 
     4. The power unit  50  includes the motor  51  which is interiorly provided with the motor rotor  511 , and the driving nut  512  is disposed in the motor rotor  511  and screwed on the screw  40 , so that the screw elevator of the present invention is not required to employ a complex-structured deceleration mechanism, thus having the advantages such as low cost of parts, occupying less space, simple design, easy to install, etc. 
     5. The power unit  50  is equipped with a sleeve  513  between the driving nut  512  and the screw  40 , so that if the motor  51  needs maintenance and repair, the nut  512  and the sleeve  513  can be disconnected to facilitate the maintenance and repair of the motor  51  without disassembling the screw  40 . 
     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.