A pump body assembly, comprising: a crankshaft, comprising a main shaft part and an eccentric part connected with the main shaft part, wherein a distance between the center line of the main shaft part and the center line of the eccentric part is e; a main bearing, comprising a hub part, wherein the main shaft part penetrates through a through hole in the hub part, and a first spiral oil guide groove is formed in a hole wall of the through hole; and a cylinder body, wherein a sliding vane slot and a center hole are formed in the cylinder body, the crankshaft penetrates through the center hole, the main bearing is located at one side of the cylinder body, a radius of the center hole is R, and a difference value between R and e is r; and a first annular groove which is formed in the hole wall of the through hole, and the first spiral oil guide groove is communicating with the first annular groove; wherein the first spiral oil guide groove is provided such that the rotation angle (σ) corresponding to the rotation of the crankshaft from a first connection line between the center of the center hole and that of the sliding vane slot in the same projection plane to a second connection line between a termination point of the first spiral oil guide groove at one end of the hub part away from the eccentric part is within a first range of value and that the rotation angle (σ0) corresponding to the rotation of the crankshaft from a third connection line between a termination point at the other end of the first spiral oil guide groove and the center of the through hole to the first connection line is within a second range of value; characterised in that the first range of value is comprised between 5π/9 + 1 2 arcsin e 2 r and 17 π / 18 + 1 2 arcsin e 2 r, and that the second range of value is comprised between 3π/2 and 2π. a crankshaft, comprising a main shaft part and an eccentric part connected with the main shaft part, wherein a distance between the center line of the main shaft part and the center line of the eccentric part is e; a main bearing, comprising a hub part, wherein the main shaft part penetrates through a through hole in the hub part, and a first spiral oil guide groove is formed in a hole wall of the through hole; and a cylinder body, wherein a sliding vane slot and a center hole are formed in the cylinder body, the crankshaft penetrates through the center hole, the main bearing is located at one side of the cylinder body, a radius of the center hole is R, and a difference value between R and e is r; and a first annular groove which is formed in the hole wall of the through hole, and the first spiral oil guide groove is communicating with the first annular groove; wherein the first spiral oil guide groove is provided such that the rotation angle (σ) corresponding to the rotation of the crankshaft from a first connection line between the center of the center hole and that of the sliding vane slot in the same projection plane to a second connection line between a termination point of the first spiral oil guide groove at one end of the hub part away from the eccentric part is within a first range of value and that the rotation angle (σ0) corresponding to the rotation of the crankshaft from a third connection line between a termination point at the other end of the first spiral oil guide groove and the center of the through hole to the first connection line is within a second range of value; characterised in that the first range of value is comprised between 5π/9 + 1 2 arcsin e 2 r and 17 π / 18 + 1 2 arcsin e 2 r, and that the second range of value is comprised between 3π/2 and 2π.