Expandable Shell of a Suitcase

Abstract

An expandable shell of a suitcase includes first and second surrounding shell bodies mated with and stackable on each other and cooperatively defining an expandable accommodation chamber for increasing the volume of the suitcase. A control unit includes a pulling cord secured to the first surrounding shell body and reeled on a reel member that is mounted to the second surrounding shell body, and a pawl and ratchet teeth disposed to control the rotation of the reel member so as to adjust a distance between the first and second surrounding shell bodies and the volume of the expandable accommodation chamber.

1 . An expandable shell of a suitcase, comprising:
 a first surrounding shell body surrounding a longitudinal axis in a longitudinal direction;   a second surrounding shell body surrounding the longitudinal axis and configured to mate with and to be stackable on said first surrounding shell body so as to cooperate with said first surrounding shell body to define an expandable accommodation chamber for increasing volume of the suitcase;   a control unit including
 a pulling cord having an anchoring end which is secured to said first surrounding shell body, a cord body which extends from said anchoring end in the longitudinal direction to terminate at a connected end, 
 a reel member which is rotatably mounted to said second surrounding shell body about a reel axis that is transverse to the longitudinal direction, and which is configured to permit said connected end to be secured thereon such that, by means of rotation of said reel member, said cord body is reeled in or out to shorten or lengthen a distance between said first and second surrounding shell bodies, said reel member having a flange which surrounds the reel axis and which is formed with a plurality of ratchet teeth that are angularly displaced from one another, 
 a reel spring disposed to bias said reel member to perform a reel-in movement, 
 a pawl having a retaining end and movable relative to said reel member between a blocking position, where said retaining end is engaged with one of said ratchet teeth so as to guard against a reeling-out movement of said reel member, and a free-rotating position, where said retaining end is disengaged from said reel member to permit said reel member to reel out said cord body, and 
 a pawl spring disposed to bias said pawl to the blocking position; and 
   an extension spring disposed to bias said second surrounding shell body away from said first surrounding shell body in the longitudinal direction so as to enlarge said expandable accommodation chamber, and having a biasing force larger than that of said reel spring such that, once said pawl is moved to the free-rotating position, said second surrounding shell body is pushed away from said first surrounding shell body by the biasing force of said extension spring, while said cord body is permitted to be reeled out from said reel member against the biasing force of said reel spring.   
     
     
         2 . The expandable shell according to  claim 1 , wherein said control unit further includes a push button configured to be manually operable to perform a stroke movement in the longitudinal direction relative to said second surrounding shell body so as to move said pawl to the free-rotating position. 
     
     
         3 . The expandable shell according to  claim 2 , wherein said control unit further includes
 a mount which is secured to said second surrounding shell body and which has an axle extending along the reel axis for mounting said reel member thereon, and a guide rail which extends in the longitudinal direction for guiding said push button to perform the stroke movement, and   a button spring which is disposed between said mount and said push button to bias said push button against the stroke movement.   
     
     
         4 . The expandable shell according to  claim 3 , wherein said control unit further includes a positioning mount which is secured to said first surrounding shell body and which has a retaining cavity and a guiding slot that is in spatial communication with said retaining cavity to permit said anchoring end to be led into said retaining cavity, and a retained block which is retained in said retaining cavity, and which is configured to secure said anchoring end in said retaining cavity. 
     
     
         5 . The expandable shell according to  claim 1 , further comprising:
 first and second tubular members which are disposed to extend respectively from said first and second surrounding shell bodies in the longitudinal direction toward each other and which are telescopically fitted to each other to form a tubular unit which is movable between retracted and extended positions;   said extension spring being disposed in said tubular unit so as to bias said tubular unit toward the extended position.