BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an assembled cross-sectional view of the first embodiment of the present invention;
FIG. 2 is a partially enlarged cross-sectional view of the present invention;
FIG. 3 is a cross-sectional along the line 3-3 in FIG. 2;
FIG. 4 is a cross-sectional along the line 4-4 in FIG. 2;
FIG. 5 is a cross-sectional view showing the operating state of the present invention; and
FIG. 6 is a partially assembled cross-sectional view of another embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The characteristics and the technical contents of the present invention will be described with reference to the following detailed description and the accompanying drawings. However, it should be understood that the drawings are illustrative but not used to limit the scope of the present invention.
FIG. 1 is an assembled cross-sectional view of the first embodiment of the present invention. FIG. 2 is a partially enlarged cross-sectional view of the present invention. FIG. 3 is a cross-sectional along the line 3-3 in FIG. 2. FIG. 4 is a cross-sectional along the line 4-4 in FIG. 2. The present invention provides a lifting device having double screw rods. The lifting device is connected respectively to a first sliding unit 5, a second sliding unit 6 and a third sliding unit 7 which are interconnected with each other so as to control the relative sliding movements among each sliding unit 5, 6, 7. Each sliding unit 5, 6, 7 can be formed into a hollow rectangular tube with different sizes. The lifting device comprises a driving means 10, a first transmission means 20 and a second transmission means 30.
The driving means 10 is fixedly connected to the bottom end of the first sliding unit 5, and it comprises a box-shaped base body 11 fixed on the bottom end of the first sliding unit 5 and a motor 12 connected to the top plate of the base body 11. A transmission shaft 121 protrudes outwardly from the center of the motor 12. The transmission shaft 121 is connected to a spur gear. The interior of the base body 11 is provided with an idle pulley 13 brought into engagement and transmission with the spur gear.
The first transmission means 20 comprises a screw rod 21, a first gear 22 and a telescopic tube assembly 23. The screw rod 21 is provided to be parallel to the transmission shaft 121 of the motor 12. The bottom end of the screw rod penetrates into the base body 11 of the driving means 10 and is fixed into the base body 12 via a bearing. The first gear 22 is connected to the bottom end of the screw rod 21 to rotate with the screw rod 21. The first gear 22 is driven by the idle pulley 13 of the driving means 10. The telescopic tube assembly 23 comprises a telescopic tube 231, a nut 232 fixedly connected to the bottom end of the telescopic tube 231, and an outer tube 233 connected to the outside of the telescopic tube 231. The nut 232 is threadedly connected on the screw rod 21 and circumferentially provided on its outer periphery with a plurality of guiding blocks 234 at intervals (FIG. 4). Further, in the interior of the outer tube 233, a plurality of guiding grooves 235 are provided for cooperating with the guiding blocks 234, so that the telescopic tube 231 can be linearly moved relative to the screw rod 21. The top end of the telescopic tube 231 is fixedly connected to the top end of the second sliding unit 6 via an insertion pin 24.
The second transmission means 30 is provided at one side of the first transmission means 20 and is parallel thereto. The second transmission means 30 comprises a sleeve 31, a screw rod 32 and a tube 33. The sleeve 31 is a cylinder and fixed into the base body 11 via a bearing. The interior of the sleeve 31 has an inner thread 311 for threadedly connecting to the screw rod 32, and the exterior thereof is formed with a second gear 312 for rotatably engaging with the first gear 22. In this way, the sleeve 31 can be driven to rotate by the first transmission means 20. The bottom end of the screw rod 32 is fixedly connected to the bottom end of the third sliding unit 7. The bottom end of the tube 33 is inserted to the base body 11 and connected to the outside of the screw rod 32.
With reference to FIG. 5, it is a cross-sectional view showing the operating state of the present invention. The lifting device of the present invention can be mounted on an electric table or an electric bed. In use, the rotation of the transmission shaft 121 of the motor 12 simultaneously drives the idle pulley 13 to rotate accordingly. Then, the idle pulley 13 drives the first gear 22 and the screw rod 21 to rotate together. The screw rod 21 can make the telescopic tube assembly 23 threadedly connected thereon to linearly protrude, so that the second sliding unit 6 fixedly connected to the distal end of the telescopic tube 231 can protrude relative to the first sliding unit 5. Further, the first gear 22 drives the second gear 312 to rotate, so that the screw rod 32 can be linearly moved relative to the sleeve 31. Since the bottom end of the screw rod 32 is fixedly connected on the third sliding unit 7, it drives the third sliding unit 7 to protrude relative to the first sliding unit 5. On the contrary, with the reverse rotation of the transmission shaft 121 of the motor 11, the second sliding unit 6 and the third sliding unit 7 can be driven to retract relative to the first sliding unit 5.
With reference to FIG. 6, it shows a partially assembled cross-sectional view of another embodiment of the present invention. In addition to the aspect shown in the above embodiment, the driving means 10 of the present invention allows the motor 12 to be fixedly connected to the side plate of the base body 11 and the transmission shaft 121 to penetrate into the base body 11 in the direction perpendicular to each screw rod 21, 32. With such arrangement, the first gear 22 and the second gear 312 of the sleeve 31 can be simultaneously driven to rotate. The transmission shaft is worm, and the first gear 22 and the second gear 312 are worm gears for rotatably cooperating with the worm. The first gear 22 rotates with the screw rod 21, thereby to drive the telescopic tube 231 and the nut 232 to linearly move relative thereto. As a result, the second sliding unit 6 fixedly connected to the distal end of the telescopic tube 231 protrudes relative to the first sliding unit 5. Further, the rotation of the sleeve 31 can drive the screw rod 32 to linearly move relative thereto. Also, since the bottom end of the screw rod 32 is fixedly connected onto the third sliding unit 7, it can drive the third sliding unit 7 to protrude relative to the first sliding unit 5. As a result, the lifting device can be partially changed according to the requirements of various products so as to increase its field of application.
According to the above, the lifting device having double screw rods of the present invention indeed has industrial applicability, novelty and inventive steps. Further, since the construction of the present invention has not been used in any products of the same kind or in public or published prior to applying for patent. Therefore, the present invention completely conforms to the requirements for a utility model patent.
Although the present invention has been described with reference to the foregoing preferred embodiments, it will be understood that the invention is not limited to the details thereof. Various equivalent variations and modifications can still be occurred to those skilled in this art in view of the teachings of the present invention. Thus, all such variations and equivalent modifications are also embraced within the scope of the invention as defined in the appended claims.
Patent Application
20080028878
