Tensioning mechanism

A tensioning mechanism, which is installed in a portable packaging machine, comprising a tensioning wheel, a tensioning wheel driving electric motor, a gear connecting mechanism arranged between the driving electric motor and the tensioning wheel, wherein the tensioning mechanism is provided with a rotation direction control and rotation angle keeping mechanism, a non-return mechanism and a rocker arm, the rotation direction control and rotation angle keeping mechanism being connected to the non-return mechanism and the rocker arm, and the rocker arm being provided with a toothed structure matching the tensioning wheel, by means of matching the rotation direction control and rotation angle keeping mechanism and a second reset mechanism, the rocker arm is driven to rotate, and an angle after the rocker arm rotates in place is kept, such that the toothed structure and the tensioning wheel are in a tensioned matching state or a loosened state;

• and by means of matching the rotation direction control and rotation angle keeping mechanism and a first reset mechanism, the non-return mechanism is driven to be in a non-return matching state or released from the non-return matching state, the gear connecting mechanism is connected to the non-return mechanism, and when the non-return mechanism is in the non-return matching state, the tensioning wheel is only driven to rotate in a single direction and cannot rotate reversely, and the single direction is a direction of rotation to tension a packaging strip.