Foldable frame for a cart

A foldable frame for a cart, comprising a pair of front wheel unit parts, a pair of rear wheel unit parts, a pair of side-wall connection structures, a first scissor structure, a second scissor structure, a bottom support structure, a tie rod, and a tie rod connection support structure;

• the pair of front wheel unit parts and the pair of rear wheel unit parts are in identical structure;
• each of the front wheel unit parts comprises a column, a wheel clamp, a sliding sleeve and a moving wheel;
• the moving wheel is rotationally mounted at a bottom of the wheel clamp, and the column is mounted at a top of the wheel clamp;
• the sliding sleeve is slidably mounted on the column;
• two bottom ends of the first scissor structure are hinged at two bottom ends of the columns of the pair of front wheel unit parts respectively;
• two top ends of the first scissor structure are hinged at two sliding sleeves on the pair of front wheel unit parts respectively;
• the second scissor structure and the first scissor structure have the same structure;
• the second scissor structure is connected to the pair of rear wheel unit parts in a same manner as the first scissor structure is connected to the pair of front wheel unit parts;
• each of the side-wall connection structures is connected to one of the front wheel unit parts and a corresponding second wheel unit part positioned on a same lateral side of the foldable frame as said one of the front wheel unit parts is positioned;
• the bottom support structure is foldably connected to the pair of front wheel unit parts and the pair of rear wheel unit parts;
• the tie rod connection support structure is foldably connected to the columns of the pair of front wheel unit parts;
• and the tie rod is mounted at the tie rod connection support structure;
• each of the side-wall connection structures comprises a first connection rod, a second connection rod, a third connection rod, a fourth connection rod, a third scissor structure, a first support connector and a second support connector;
• one end of the first connection rod is hinged at a top of the column of a respective rear wheel unit part, and another end of the first connection rod is hinged at a first top end of the third scissor structure;
• one end of the second connection rod is hinged at a top of the column of a respective front wheel unit part, and another end of the second connection rod is hinged at a second top end of the third scissor structure;
• one end of the third connection rod is hinged at the sliding sleeve of the respective rear wheel unit part, and another end of the third connection rod is hinged at a first bottom end of the third scissor structure;
• one end of the fourth connection rod is hinged at the sliding sleeve of the respective front wheel unit part, and another end of the fourth connection rod is hinged at a second bottom end of the third scissor structure;
• one end of the first support connector is hinged at a bottom end of the column of the respective rear wheel unit part, and another end of the first support connector is hinged at a portion of the third scissor structure proximal to the first top end of the third scissor structure;
• one end of the second support connector is hinged at a bottom end of the column of the respective front wheel unit part, and another end of the second support connector is hinged at a portion of the third scissor structure proximal to the second top end of the third scissor structure.