Flange and pump body assembly with same

A pump body assembly, comprising:

• a cylinder, a flange body being located on a side of the cylinder,
• a main shaft having a central part, with a plurality of sliding vane grooves being formed in the central part, a sliding vane being provided in each of the plurality of sliding vane grooves, the main shaft being passed through a shaft hole, and the central part being located in the cylinder, the main shaft configured to drive the sliding vanes to rotate so as to perform compression operation in the cylinder, and
• a flange, comprising:
• a flange body provided with a shaft hole, a back pressure groove being provided beside the shaft hole, a communication part being provided on a side wall between the shaft hole and the back pressure groove, the communication part communicating the back pressure groove with the shaft hole, and the communication part being configured to supply lubricating oil to the back pressure groove or discharge the lubricating oil from the back pressure groove,
• wherein the communication part comprises a first notch located on the side wall between the shaft hole and the back pressure groove, and an included angle α1 being formed by connecting lines between two ends of the first notch and a center of the shaft hole is equal to A, A being an angle of rotation of the shaft from a first rotational position when a sliding vane begins to extend from a first retracted position out of a sliding vane groove to a second rotational position when a speed of the sliding vane reaches its maximum, wherein the sliding vane has a phase of extension from the sliding vane groove beginning with a zero speed position and ending with a maximum extension speed position, wherein the first notch has a circumferential extent from a first position on the side wall in radial alignment with the zero speed beginning position of the sliding vane's extension phase to a second position on the side wall in radial alignment with the maximum extension speed position of the sliding vane's extension phase,
• wherein the communication part further comprises a second notch located on the side wall between the shaft hole and the back pressure groove, and an included angle α2 being formed by connecting lines between two ends of the second notch and the center of the shaft hole is equal to B, B being an angle of rotation of the shaft from a third rotational position when the sliding vane begins to retract from a second fully extended position toward the sliding vane groove to a fourth rotational position when the speed of the sliding vane reaches its maximum, wherein the sliding vane has a phase of retraction back into the sliding vane groove beginning with a zero speed position and ending with a maximum retraction speed position, wherein the second notch has a circumferential extent from a first position on the side wall in radial alignment with the zero speed beginning position of the of the sliding vane's retraction phase to a second position on the side wall in radial alignment with the maximum retraction speed position of the sliding vane's retraction phase.