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A folding structure for a trolley includes at least two main poles and a movable member. The main poles are connected to a carrying platform having an operating rod, two roller sets, and a base that are motionally linked. A transverse plate is attached to upper ends of the main poles. The movable me

A folding structure for a trolley includes at least two main poles and a movable member. The main poles are connected to a carrying platform having an operating rod, two roller sets, and a base that are motionally linked. A transverse plate is attached to upper ends of the main poles. The movable member is slidably mounted on the main poles and has a pull rod. The pull rod extends beyond the transverse plate for an extension distance. To prepare the trolley for use, the operating rod is pushed downward so that the roller sets expand in a horizontal direction and the base is laid down. Then the pull rod is set for its largest extension distance to facilitate a user's pulling trolley. After use, the trolley can be easily folded by lifting the operating rod that in turn drives the roller sets and the base to retract.

대표청구항 ▼

1. A folding structure for a trolley, the folding structure comprising: at least two main poles that are spaced apart from each other by a preset distance, wherein a carrying platform and a transverse plate are separately mounted with the two main poles; and the transverse plate is provided with a p

1. A folding structure for a trolley, the folding structure comprising: at least two main poles that are spaced apart from each other by a preset distance, wherein a carrying platform and a transverse plate are separately mounted with the two main poles; and the transverse plate is provided with a pressing block, two retaining blocks, and a spring member, in which the pressing block has a receiving groove, the two retaining blocks each have one end provided with a ramp portion in contact with a respective one of two lateral sides of the receiving groove, and the spring member accumulates or releases an elastic potential energy in response to relative movement among the pressing block and the two retaining blocks; anda movable member located below the transverse plate and slidably mounted around the two main poles, wherein the movable member has two hooks extending therefrom and being configured to engage with the two retaining blocks; the movable member has a pull rod extending through the transverse plate and having a portion going beyond the transverse plate; and the portion of the pull rod that goes beyond the transverse plate has a length defined as an extension distance;wherein when the two hooks of the movable member each engage with a respective one of the two retaining blocks, the extension distance is at its maximum;wherein while, with the two hooks of the movable member each engaging with a respective one of the two retaining blocks, being applied with an external force, the pressing block presses against the ramp portions of the two retaining blocks so that the two retaining blocks come close to each other and thus are disengaged from the two hooks, thereby allowing the movable member to freely slide along the two main poles to change the extension distance;wherein the spring member accumulates the elastic potential energy while the external force is applied; andwherein the spring member releases the elastic potential energy to return the pressing block and the two retaining blocks once the external force is removed. 2. The folding structure of claim 1, wherein each of the two retaining blocks has one end being provided with a moving end and another end being provided with a hooking end, in which the two moving ends of the two retaining blocks each have a respective one of the ramp portions, and the two hooking ends of the two retaining blocks each are configured to be engaged with a respective one of the two hooks; and the spring member includes a first spring member arranged between the two moving ends of the two retaining blocks. 3. The folding structure of claim 1, wherein the spring member comprises a first spring member and a second spring member, in which the first spring member is arranged between the two retaining blocks, and the second spring member is arranged in the transverse plate and pressed against the pressing block. 4. The folding structure of claim 3, wherein the two ramp portions each have an incline in contact with said respective one of the two lateral sides of the receiving groove; and when being applied with the external force, the pressing block moves downward along and pushes against the two inclines of the two ramp portions, so that the two retaining blocks come close to each other and compress the first spring member arranged therebetween. 5. The folding structure of claim 1, wherein the carrying platform further comprises an operating rod, two roller sets, and a base; the operating rod has two ends each being pivotally connected to a respective one of the two main poles; each of the two ends of the operating rod is provided with a first gear wheel adjacent to a position where a corresponding main pole is pivotally connected thereto; the two main poles each are provided with a second gear wheel engaged perpendicularly with a respective one of the two first gear wheels; and the two roller sets each are provided with a third gear wheel engaged horizontally with a respective one of the two second gear wheels, so that the two roller sets is able to be retracted or expanded in a horizontal direction when the two first gear wheels are driven by the operating rod to move the two second gear wheels and in turn rotate the two third gear wheels. 6. The folding structure of claim 5, wherein the two roller sets each have a fixing recess, and the two ends of the operating rod each are further provided with a protruding member so that, when the operating rod expand in the horizontal direction, the protruding members are inserted into the two fixing recesses. 7. The folding structure of claim 5, wherein the two roller sets are further provided with two fourth gear wheels, and the base has two ends with a fifth gear wheel pivotally connected to each end; and each said fourth gear wheel is vertically aligned and coaxial with a corresponding third gear wheel and is engaged perpendicularly with a respective one of the two fifth gear wheels so that, when the third gear wheels is driven to rotate the fourth gear wheels, the fifth gear wheels drive the base to fold toward the two main poles, or to deploy away from the two main poles.