The special geometry of the stator and rotor makes them cooperate with each other to form several mutually unconnected sealing cavities (cavities), and the cooperation between them is interference fit. When the motor operates, it will transfer power to the rotor and make the rotor move planetary along the axial direction, so as to push the sealing cavity to move to the discharge end and achieve the purpose of conveying liquid. When the stator begins to wear, the fit gap between the rotor and stator will become larger, which may cause the rotor not to be too tight in the stator. When the delivered fluid reaches the outlet of the pump, the discharge pressure of the circuit must be overcome; However, the fluid will generally seek the path with the least resistance; If the resistance of the seal chamber between the stator and the rotor is the minimum, part of the liquid will leak to the previous chamber.