Blood pressure measuring device

A blood pressure measuring device comprising a device body, an air bag, an air nozzle and a piston,

• wherein an air pump is provided in the device body, a mounting hole and an air passage connection hole communicating with the mounting hole are provided on a casing of the device body, and the air passage connection hole is communicated with an air outlet of the air pump,
• wherein the piston is installed in the mounting hole-, and the piston includes a piston sealing portion, to form a seal between the piston sealing portion and a part of the mounting hole positioned above the air passage connection hole, and
• wherein the air nozzle includes a through hole communicating with the air bag, and when the air nozzle is inserted into the mounting hole, the air nozzle presses the piston downward until the piston sealing portion is positioned below the air passage connection hole, and the through hole is communicated with the air passage connection hole,
• wherein the air passage connection hole is in an upper part of the mounting hole and on a side of the mounting hole,
• wherein the blood pressure measuring device further comprises a restoring elastic member cooperating with the piston, and the restoring elastic member deforms when the piston moves downward relative to the mounting hole, so as to generate a force that pushes the piston to restore to an upper portion of the air connection hole.