Patent ID: 8251684

Claim:
A trochoid pump, comprising: a driving shaft; a drive gear fixed on a first end of the driving shaft, wherein the drive gear comprises a bevel gear; an inner rotor penetrated onto the second end of the driving shaft; an outer rotor, the center of which is decentered to the inner rotor; a cap and a casing covering both the inner and outer rotor; a first regulatory structure configured to constrain movement of the driving shaft in a first axial direction of the casing; and a second regulatory structure configured to constrain movement of the driving shaft, wherein an end face on the second end of the driving shaft is engaged with an end face of the cap in the direction opposite the first axial direction; the first regulatory structure further comprising: a specially shaped drive pin having a tetrahedral shaped portion comprising two dihedral portions shaped on both ends of the drive pin, wherein the specially shaped drive pin is inserted into the midstream of the driving shaft; and a joint disposed on the inner rotor, wherein the joint is configured for engagement with the tetrahedral shaped portion, wherein one dihedral portion of the tetrahedral shaped portion of the drive pin is engaged with a surface of the joint in an axial direction of the driving shaft, and the other dihedral portion is engaged with a surface of the joint in a rotational direction of the driving shaft, and wherein the first regulatory structure and the second regulatory structure are configured to reduce backlash between the drive gear and another drive gear caused by axial offset of the driving shaft in a thrust direction.