Auto-returning track device

Abstract

An auto-returning track device comprises a retaining track; a lower side of the retaining track having a protrusion; the retaining track having a sliding space enclosed by two stops at two ends and a retaining seat; a movable track received in the sliding space and slideable with respect to the retaining track; the movable track having a hook with respect to the retaining seat; a movable base received in the sliding space and between the movable track and the retaining seat; at least one returning element being installed between the movable base and the retaining seat; and a positioning buckle swingably pivoted with the movable base; an outer surface of the positioning buckle being formed with a positioning groove for hooking with a hook of the movable track; a hook portion extending from a lower surface of the movable track; the hook portion can be hooked to the protrusion.

What is claimed is: 
     
         1 . An auto-returning track device comprising:
 a retaining track having an U shape cross section; a lower side of the retaining track having a protrusion; the retaining track having a sliding space enclosed by two stops at two ends and a retaining seat;.   a movable track received in the sliding space and slideable with respect to the retaining track; the movable track being a hook with respect to the retaining seat; and   a movable base received in the sliding space and between the movable track and the retaining seat; the movable base being pivotally installed with a positioning buckle so as to be interacted with the movable track; an outer surface of the positioning buckle being formed with a positioning groove for hooking with a hook; a hook portion extending from a lower surface of the movable track; each of two lateral sides of the positioning buckle being extended with a guiding portion which is slideable along a lateral wall of the retaining track; between the guiding portion and the retaining seat having a returning element.   
     
     
         2 . The auto-returning track device as claimed in  claim 1 , wherein the movable track has a middle track moveable with respect to the retaining track and an inner track movable with respect to the middle track; the hook is fixed to a frame body of the inner track. 
     
     
         3 . The auto-returning track device as claimed in  claim 1 , wherein the movable base is formed by two L shape guiding sheets and an auxiliary sheet; the two guiding sheets are slideable along the two lateral sides along two sides of the retaining track and the auxiliary sheet is connected between the two guiding sheets; each guiding sheet has an elliptical hole and a notch; two lateral sides of the positioning buckle are formed with two axial rods corresponding to the elliptical holes of the two guiding sheets; the two lateral sides of the positioning buckle are formed with two guiding portions; each guiding portion is formed with a combining hole for hooking a returning element. 
     
     
         4 . The auto-returning track device as claimed in  claim 1 , wherein the notch is formed with a limiting sheet for resisting against the protrusion. 
     
     
         5 . The auto-returning track device as claimed in  claim 1 , wherein a buffer is installed between the auxiliary sheet and the retaining seat. 
     
     
         6 . The auto-returning track device as claimed in  claim 1 , wherein the buffer is an air pressure or a pneumatic cylinder. 
     
     
         7 . The auto-returning track device as claimed in  claim 1 , wherein the buffer is a damper. 
     
     
         8 . The auto-returning track device as claimed in  claim 1 , wherein an outer side of the positioning buckle is formed with a positioning groove by the confinement of two inclined guide blocks. 
     
     
         9 . An auto-returning track device comprising:
 a retaining track having an U shape cross section; a lower side of the retaining track having a protrusion; the retaining track having a sliding space enclosed by two stops at two ends and a retaining seat;   a movable track received in the sliding space and slideable with respect to the retaining track; the movable track having a hook with respect to the retaining seat;   a movable base received in the sliding space and between the movable track and the retaining seat; at least one returning element being installed between the movable base and the retaining seat; and   a positioning buckle swingably pivoted with the movable base; an outer surface of the positioning buckle being formed with a positioning groove for hooking with a hook of the movable track; a hook portion extending from a lower surface of the movable track; the hook portion can be hooked to the protrusion.   
     
     
         10 . The auto-returning track device as claimed in  claim 9 , wherein the movable track has a middle track moveable with respect to the retaining track and an inner track movable with respect to the middle track; the hook is fixed to a frame body of the inner track. 
     
     
         11 . The auto-returning track device as claimed in  claim 9 , wherein the movable base is formed by two L shape guiding sheets and an auxiliary sheet; the two guiding sheets are slideable along the two lateral sides along two sides of the retaining track and the auxiliary sheet is connected between the two guiding sheets; each guiding sheet has an elliptical hole and a notch; two lateral sides of the positioning buckle are formed with two axial rods corresponding to the elliptical holes of the two guiding sheets; the two lateral sides of the positioning buckle are formed with two guiding portions; each guiding portion is formed with a combining hole for hooking a returning element. 
     
     
         12 . The auto-returning track device as claimed in  claim 9 , wherein the notch is formed with a limiting sheet for resisting against the protrusion. 
     
     
         13 . The auto-returning track device as claimed in  claim 9 , wherein a buffer is installed between the auxiliary sheet and the retaining seat. 
     
     
         14 . The auto-returning track device as claimed in  claim 9 , wherein the buffer is an air pressure or a pneumatic cylinder. 
     
     
         15 . The auto-returning track device as claimed in  claim 9 , wherein the buffer is a damper. 
     
     
         16 . The auto-returning track device as claimed in  claim 9 , wherein a rear end of each guiding sheet is extended with a vertical sheet; a C shape combining hole is formed from a lower side to a lateral side of the vertical sheet; one end of the returning element is received in the C shape combining hole and another end of the returning element is connected to the movable base. 
     
     
         17 . An auto-returning track device comprising:
 a retaining track having an U shape cross section; a lower side of the retaining track having a protrusion; the retaining track having a sliding space enclosed by two stops at two ends and a retaining seat;   a movable track received in the sliding space and slideable with respect to the retaining track; a bottom of the movable track protruded with a projection;   a movable base received in the sliding space and being positioned between the movable track and the retaining seat; between each of two rare lateral sides and the retaining seat having a respective elastic element; a lower center of the movable base being formed with a receiving groove; a telescopic block being installed in the receiving groove; between the two lateral sides of the telescopic block and wall of the receiving groove having two respective springs which are used as returning elements; a positioning element having a stop rod extended from a lower side thereof and a pivotal rod extended from an upper side thereof; the stop rod and the pivotal rod being at two opposite sides of the positioning element; one later side of the positioning element being formed with a recess; the positioning element being combined to the movable base by the pivotal rod being inserted into a through hole of the movable base  100  so that the positioning element being rotatable with respect to the movable base.   
     
     
         18 . The auto-returning track device as claimed in  claim 17 , wherein  2 . The auto-returning track device as claimed in  claim 1 , wherein the movable track has a middle track moveable with respect to the retaining track and an inner track movable with respect to the middle track; the hook is fixed to a frame body of the inner track. 
     
     
         19 . The auto-returning track device as claimed in  claim 17 , wherein a buffer is installed between the auxiliary sheet and the retaining seat, and the buffer is selected from an air pressure or a pneumatic cylinder. 
     
     
         20 . The auto-returning track device as claimed in  claim 17 , wherein each of two ends of a rear side of the telescopic block is connected with one end of a returning element and another end of the returning element is connected to a lower end of the receiving groove.