Patent Application
20140246533
1. Field of Invention
The present invention relates to a tie-down device and, more particularly, to a tie-down device equipped with a speed-increasing gearbox.
2. Related Prior Art
As disclosed in U.S. Pat. Nos. 5,611,520, 7,100,902 and 8,172,203, a tie-down device includes a frame, two axles and a knob. The frame includes two separate walls extending from a base. The axles are supported on the walls. The knob is connected to an end of one of the axles that extends beyond one of the walls. The knob is operable to wind a strap onto the axle that is connected thereto. However, the winding of the strap onto the axle is troublesome and slow.
As disclosed in U.S. Pat. No. 6,609,275, a tie-down device includes a frame, an axle, a reel and a coil spring. The axle is non-rotationally supported on the frame. The reel is rotationally provided around the axle. The coil spring includes an end connected to the axle and another end connected to the reel. The coil spring is loaded as a strap is unwound from the reel. The strap can be wound onto the reel by the coil spring. The wind of the strap onto the reel is automatic. However, the diameter of the coil spring is large as the strap is long. That is, a large coil spring requires a lot of steel which is heavy and expensive.
Therefore, the present invention is intended to obviate or at least alleviate the problems encountered in prior art.
It is the primary objective of the present invention to provide a light tie-down device that winds a strap fast.
To achieve the foregoing objective, the tie-down device includes a frame, a strap, a reeling unit, a driving unit and a gear box. The frame includes two walls extending from a base. The reeling unit includes a reel rotationally supported on the walls for reeling the strap. The driving unit is supported on the first wall. The gearbox connects the driving unit to the reeling unit.
Other objectives, advantages and features of the present invention will be apparent from the following description referring to the attached drawings.
The present invention will be described via detailed illustration of embodiments referring to the drawings wherein:
Referring to
The handle 12 is connected to the axle 14. The axle 14 is supported on the walls 24 rotationally. A long strap 34 includes an end connected to the reeling unit 40 and another end connected to a hook 32. The long strap 34 is inserted via a slot defined in the axle 14. The long strap 34 can be wound onto the axle 14 by operating the handle 12.
The reeling unit 40 includes a reel 42 rotationally supported on the walls 24.
The speed-increasing gearbox 60 includes a shell 62, a large gear 70, a small gear 72 and an axle 80. The axle 80 is rotationally supported on the walls 24. The axle 80 includes a butt 82 formed at an end and a slit 86 defined in an opposite end. A clip 84 is placed in a groove defined in the axle 80 near the butt 82. The butt 82 is placed against an internal side of the outwardly protrusive portion 28 of the wall 24 while a clip 84 is placed against an external side of the same to keep the axle 80 on the outwardly protrusive portion 28 of the wall 24.
The large gear 70 is secured to the axle 80 so that they are rotatable together. The small gear 72 is secured to the reel 42 so that they are rotatable together. The small gear 72 is meshed with the large gear 70. Preferably, the large gear 70 includes teeth three times as many as the small gear 72 so that the small gear 72 rotates for three rounds as the large gear 70 rotates for one round.
The large gear 70 and the small gear 72 are protectively covered by the shell 62. Screws 64 are used to connect the shell 62 to the wall 24 that is formed with the outwardly protrusive portion 28.
The driving unit includes a coil spring 50 and a cover 52. The coil spring 50 includes an external end 54 hooking a tab extending from an internal side of the cover 52 and an internal end 56 extending through a slit 86 defined in the axle 80. The cover 52 is connected to the wall 24 that is formed with the outwardly protrusive portion 28.
The coil spring 50 is loaded as the long strap 34 is unwound from the reel 42. The long strap 34 can be wound onto the reel 42 by the coil spring 50 via the speed-increasing gearbox 60. The coil spring 50 does not have to be long to wind a long strap onto the reel 42 due to the use of the speed-increasing gearbox 60. The coil spring 50 can be small and light. The coil spring 50 requires only a small amount of steel and is hence inexpensive.
Referring to
Referring to
The internal gear 90 is non-rotationally placed in the shell 62. The carrier 96 is connected to the axle 80 so that they are rotatable together. The sun gear 94 is connected to the reel 42 so that they are rotatable together.
The coil spring 50 rotates the axle 80 as well as the carrier 96. The carrier 96 rotates the sun gear 94 as well as the reel 42 via the planetary gears 92. The axles 80 and 42 rotate in a same direction.
Preferably, the internal gear 90 includes forty-eight teeth, each of the planetary gears 92 includes twelve gears, and the sun gear 94 includes twenty-four teeth. Thus, the sun gear 94 rotates for four rounds as the carrier 96 rotates one round.
The present invention has been described via the detailed illustration of the embodiments. Those skilled in the art can derive variations from the embodiments without departing from the scope of the present invention. Therefore, the embodiments shall not limit the scope of the present invention defined in the claims.
