Abstract:
A power-operated automobile sunshade including a double-threaded screw rod turned by a motor through a single-threaded screw rod via a worm gear to move screw nuts inward toward each other along the double-threaded screw rod so as to move two linked rods in lifting the shade body of a shade roller over the rear windshield of the automobile.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a power-operated automobile sunshade which is controlled by a motor through a mechanical transmission mechanism to lift a shade body over the rear windshield for protection against the radiation of the sun. 
     Various sunshades have been disclosed for protecting the rear windshield from the suns rays. However, these sunshades are still not convenient in use because they must be fitted and collapsed manually. There are still some other power-operated sunshades appearing on the market. However, these power-operated sunshades are not satisfactory in function because or the disadvantages of complicated structure, high cost, and low durability. 
     SUMMARY OF THE INVENTION 
     The present invention eliminates the aforesaid disadvantages. It is one object of the present invention to provide a power-operated automobile sunshade which is controlled by a motor to lift or collapse the shade body through a mechanical transmission mechanism. It is another object of the present invention to provide a power-operated automobile sunshade which fully covers the rear windshield when extended out. It is still another object or the present invention to provide a power-operated automobile sunshade which does not hinder the sight through the rear windshield as it is collapsed. It is still another object or the present invention to provide a power-operated automobile sunshade which is suitable for any or a variety or automobiles. It is still another object of the present invention to provide a power-operated automobile sunshade which is compact and lightweight. It is still another object of the present invention to provide a power-operated automobile sunshade which is inexpensive to manufacture. It is still another object of the present invention to provide a power-operated automobile sunshade which can be installed with a third stop lamp. It is still another object of the present invention to provide a power-operated automobile sunshade which can be conveniently controlled by a control button through a control circuit. It is still another object of the present invention to provide a power-operated automobile sunshade which can be controlled by a remote controller. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a power-operated automobile sunshade according to the present invention; 
     FIG. 2 is an exploded view of the power-operated automobile sunshade of FIG. 1; 
     FIG. 3A is a side view in section of the power-operated automobile sunshade of FIG. 1 when collapsed; 
     FIG. 3B is a side view in section of the power-operated automobile sunshade of FIG. 1 when extended out; 
     FIG. 4 is a schematic drawing showing the power-operated automobile sunshade of the present invention extended out; and 
     FIG. 5 is similar to FIG. 1, but showing a third stop lamp installed in the base frame of the base unit thereof. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 1 and 2, therein illustrated is a power-operated automobile sunshade according to the present invention, generally comprised or a screw rod transmission mechanism 1, a shade roller 2, and a base unit 3. The transmission mechanism 1 is comprised of a double-threaded screw rod 11 having a worm gear 111 in the middle, a guard tube 19 covered around the double-threaded screw rod 11, two screw nuts 13 fastened to the double-threaded screw rod 11 on two opposite ends, each screw nut 13 having a stub screw rod 131, two first end caps 14 respectively fastened to the stub screw rod 131 on either screw nut 13 by a respective locknut l5, two elongated rods 16 respectively connected to the first end caps 14, two second end caps 17 respectively connected to the opposite end or either elongated rod 16, a connector 12 connected between the second end caps 17 by locknuts 18. The two threads of the double-threaded screw rod 11 are disposed in reversed directions and separated by the worm gear 111. The shade roller 2 is comprised of a cylindrical casing 21, a slat 22 inserted through a hole (not shown) on the connector 12 and having two opposite ends fastened with two end caps 24 respectively, and a shade body 23 connected between the slat 22 and a reversing mechanism controlled reel (not shown) inside the cylindrical casing 21. The base unit 3 is generally comprised of a base frame 31, and a carrier 32 fitted over the base frame 31 at the top. The carrier 32 comprises a first two downward clamping plates 325 on two opposite ends thereof respectively clamped on two opposite ends of the base frame 31, a slot 324 in the middle, which receives the worm gear 111 of the transmission mechanism 1, two end caps 322 fastened to two opposite ends of a shade tube 231, a rear flange 321 to hold the cylindrical casing 21 of the shade roller 2 therein, a front flange 323 formed along the front side thereof to hold the guard tube 19 of the transmission mechanism I on the carrier 32 at one side by the rear flange 321. The base frame 31 is made in a hollow structure having a slot 311 in the middle aligned with the slot 324 on the carrier 32. A motor 33 and a single threaded screw rod 331 are respectively installed inside the base frame 31 (see FIG. 3A). The single threaded screw rod 331 is coupled to the motor 33 and meshed with the worm gear 111 of the transmission mechanism 1. 
     Referring to FIG. 3A, when assembled, the shade body 23 is wound round the reel received inside the cylindrical casing 21 held within the rear flange 321 of the carrier 32, the slat 22 is disposed outside the rear flange 321, and the transmission mechanism 1 is retained in place by the front flange 323, 
     Referring to FIGS. 3B and 4, as the single threaded screw rod 331 is driven by the motor 33 to turn the double-threaded screw rod 11 through the worm gear 111, the screw nuts 13 are forced to turn inwards toward each other along the double-threaded screw rod 11, causing the rods 16 to lift the slat 22, and therefore the shade body 23 is lifted. 
     While only one embodiment of the present invention has been shown and described, it will be understood that various modifications and changes could be made without departing from the spirit and scope or the invention. For example: a third stop lamp 4 may be installed in the base frame 31 or the base unit 3 (see FIG. 5); a remote controller may be used to control the operation or the motor 33.