Crank structure for a curtain

A crank structure for a curtain has a base, a rolling wheel set, an engagement set and a crank. The base has a bottom plate and a limiting frame. The rolling wheel set is disposed in the storing space of the base and has two rolling wheels. Each central aperture is jacketed onto the central shaft of the storing space. The two rolling wheels is further respectively provided with a braking gear and an inclined ring. Each inclined ring has a plurality of engagement ribs. The engagement set disposed in the assembling portion of the base and has a socket, a supporting wheel and a bottom member. An engaging pattern is provided at a periphery of the supporting wheel, a passive gear is provided at the supporting wheel, and a shaft is provide at a center position of the supporting wheel.

BACKGROUND OF INVENTION

1. Field of Invention

The present invention relates to curtains, and more particularly to a crank structure for a curtain.

2. Description of the Related Art

Accordingly, curtains are used in modern living rooms, mainly for shading and privacy protection. They are also used to embellish and decorate living area and even highlight the style. However, in order to facilitate the unfolding and winding of the curtains, the modern curtains need to corporate with a pull cord to lift and lower of the curtain blades. However, the falling length of the pull cord is easy to float with the wind, which often causes the entanglement and knotting of the pull cord, and affects the normal operation of the curtain. Furthermore, long hanging cords are mostly made of strong ropes or chains, it is also common for young children in the family to pull the ropes to play with the curtains and cause accidents.

Therefore, it is desirable to provide a vertical blinds structure to mitigate and/or obviate the aforementioned problems.

SUMMARY OF THE INVENTION

An objective of present invention is to provide a a crank structure for a curtain with improvements.

To achieve these and other objects of the present invention, a crank structure for a curtain has a base, a rolling wheel set, an engagement set and a crank. The base has a bottom plate and a tear-shaped limiting frame, the limiting frame has a round shaped storing space with a central shaft, an exit channel disposed above the storing space, and a hollow assembling portion is connected to the storing space and having a groove. The rolling wheel set is disposed in the storing space of the base and has two rolling wheels each respectively having a central aperture and a plurality of assembling apertures. Each central aperture is jacketed onto the central shaft of the storing space. The two rolling wheels is further respectively provided with a braking gear at each outer side and an inclined ring at a periphery of each facing inner side. Each inclined ring has a plurality of engagement ribs. The engagement set disposed in the assembling portion of the base and has a socket, a supporting wheel and a bottom member. The socket has an H shape, two parallel members of the socket provided with a corresponding axial aperture, the horizontal member is provided with a slot. An engaging pattern is provided at a periphery of the supporting wheel, a passive gear is provided at a back side of the supporting wheel, and a shaft is provide at a center position of the supporting wheel and passing through both axial apertures of the two parallel members. The bottom member is secured at a bottom end of the assembling portion and further has a limiting column facing the socket. The limiting column is configured for being jacketed with an elastic member and pushes against the socket and the supporting wheel with the elastic member. The passive gear and the rolling wheel set engages, and the supporting wheel is disposed between the two rolling wheels. The crank is disposed in the storing space of the limiting frame and has a cover and an arm, and the cover is provided with two assembling columns coupling with the two assembling apertures of one of the rolling wheels.

Other objects, advantages, and novel features of invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

First, please refer toFIGS. 1, 2, and 3. A crank structure for a curtain comprises: a base10, a rolling wheel set20, an engagement set30and a crank40. The base10has a bottom plate11and a tear-shaped limiting frame12, and the limiting frame12has a round shaped storing space13with a central shaft14. The central shaft14further has a center screw hole141, two convex members142around the center screw hole141, and a positioning member15. The positioning member15has a through aperture151and two concave holes152. An exit channel16is disposed above the storing space13and is provided with a plurality of vertical ribs161and a stepped portion162for coupling with a sleeve163. The limiting frame12is further provided with an assembling portion17connected to the storing space13and having a groove171. An orifice and two assembling screw holes are provided at the bottom of the groove171. The groove171is further provided with a vertical slot173and a through hole174. The storing space13is further provided with a first ring member131lower than the limiting frame12, and the first ring member131has an opening connected with the groove171. The rolling wheel set20is disposed in the storing space13of the base10and has two rolling wheels21each respectively having a central aperture211and a plurality of assembling apertures212. Two facing sides of the two rolling wheels21are provided with corresponding protrusions213and recesses214around each assembling aperture212for engaging the two rolling wheels22, and the two assembling apertures212are secured with a locking member215. The two rolling wheels21further respectively provided with a braking gear216at each outer side and an inclined ring217at a periphery of each facing inner side, and each inclined ring217has a plurality of engagement ribs219. The engagement set30is disposed in the assembling portion17of the base10and has a socket31, a supporting wheel32and a bottom member33. The socket31has an H shape, two parallel members of the socket31are respectively provided with a corresponding axial aperture311, and the horizontal member is provided with a slot312. The socket31of the engagement set30further has a trigger313passing through the through hole174. An engaging pattern321is provided at a periphery of the supporting wheel32, a passive gear322is provided at a back side of the supporting wheel32, and a shaft323is provide at a center position of the supporting wheel32and passes through both axial apertures311of the two parallel vertical members. The bottom member33has two assembling holes331secured with two locking members332and the assembling portion17, and the bottom member33further has a limiting column333facing the socket31, and the limiting column33is configured for being jacketed with an elastic member34and pushes against the socket31and the supporting wheel32with the elastic member334. Therefore, the passive gear322and the rolling wheel set20engages together, and the supporting wheel32is correspondingly disposed between the two rolling wheels21. The bottom member33further has a positioning cover335corresponding to the through hole174, which defines a distance for the trigger313to move the socket31. The crank40is disposed in the storing space13of the limiting frame12and has a cover41and an arm42. The cover41is provided with two assembling columns411coupling with two assembling apertures21of one of the rolling wheels21. The cover41of the crank40further has a second ring member412corresponding to the first ring member131, and the second ring member412is separated from the first ring member131by a gap.

For the composition of the structure, please refer toFIGS. 2, 3, 4, and 5. The crank40is assembled with the base10, the rolling wheel set20, the engagement set30, and the crank40sequentially. The rolling wheel set20combines the two rolling wheels21together with the sides having the inclined ring217facing each other which positioned by the protrusion213and the recess214provided on the assembly aperture212and then secured by the two locking members215to complete the assembly of the rolling wheel set20. The inclined rings217of the two rolling wheels21form a V-shaped ring groove218, and the central aperture211of the rolling wheel set20is placed through the central shaft14of the storage space13. A positioning member15is further provided at the end of the central shaft14which is configured for limiting the supporting wheel set20to the storage space13. The supporting wheel32of the supporting set30utilizes the shaft323to being pivoted across the shaft holes311of the two vertical members on both sides of the socket31. The bottom member33is pivoted below the socket31, and the limiting column333is sleeved an elastic member334and placed against the slot312of the socket31. Finally, the engagement set30is assembled from the bottom up into the groove171of the assembly portion17, the vertical members of the socket31is incorporated into the groove171along the vertical slot173, the trigger313protrudes from the through hole174of the assembling portion17, and the bottom member33is coupled with the locking member332and fixed on the bottom of the groove171. Therefore, the socket31is pushed up by the elastic member334, the supporting wheel32is located in the V-shaped ring groove218of the two rolling wheels21, and the passive gear322and the braking gear216of one rolling wheel21are engaged to form a linkage. Finally, the crank40is mounted in the storage space13of the limiting frame12, the second ring member412is embedded in the storing space13, and the two assembling columns411of the cover41are inserted into the two assembling apertures212of the two rolling wheels21. Further, the cover41is restrained by the orifice, and the assembling column411is further locked with the rolling wheel21by the bolt413. Therefore, the rotation of the crank40can drive the rolling wheel set20.

The actual use of the structure, as shown inFIGS. 6, 7, and 8. The crank structure is fixed to the wall through the base10and corporates with the rope50of the curtain. The rope50is placed vertical and has with a loop at its end. Since the engagement set30is normally pushed by the elastic member334and touches the rolling wheel set20, the rope50is required to be equipped with the crank40while the crank40is removed from the base10, and then the trigger313protruding from the through hole174is pulled down, so that the socket31is turned downwardly and the supporting wheel32is apart from the rolling wheel set20. Meanwhile, the rope50can be introduced into the storing space13from the exit channel16, and then wound around the V-ring groove218of the rolling wheel set20and form a tight state. By releasing the trigger313, the rope50is pushed by the elastic member334and clamped between the V-ring grooves218by the supporting wheel32. Furthermore, the passive gear322simultaneously engages with the braking gear216of the rolling wheel21, and then finally the crank40is reinstalled to complete the assembly. This crank structure can be additionally installed on the existing curtains with rope, which greatly enhances the practicability of the structure.

The actual state of the structure is retracted, and then refer toFIGS. 3, 4, and5in conjunction withFIG. 9. Since the rope50is looped around the V-shaped ring groove218of the rolling wheel set20and clamped by the supporting wheel32, the passive gear322of the supporting wheel32engages with the braking gear216of the two rolling wheel21, when the user rotates the crank40, the rolling wheel set20rotates as the crank40rotates and drives the supporting wheel32to rotate, and the engagement rib219of the inclined ring217of the two rolling wheels21and the engaging pattern321on the supporting wheel32clamp the rope50to form a pulling down and pushing up repeating cycle to control operation of the curtain.

According to the structure of the above specific embodiment, the following benefits can be obtained: the crank structure can be additionally installed on the existing curtains with drawstring in the market, so that the consumer can be benefited through the simplest installation method. The installation of the crank structure is simple and fast, which greatly improves the practicability of the structure and. In addition, when the rope50is used with the crank structure, the rope50is linearly restricted between the curtain upper rail and the crank, so the rope50can be prevented from swinging to form an entanglement and knotting which prevents infants, young children, children from playing with it