Oil supply to the back pressure groove of a vane pump

A pump body assembly, comprising:

• an oil supply passage configured for circulating oil;
• two back pressure members, wherein at least one back pressure member of the two back pressure members is provided with a back pressure groove, the back pressure groove comprises a first groove section and a second groove section, the first groove section and the second groove section are disposed at intervals, the first groove section is communicated with the oil supply passage, and the second groove section is communicated with the oil supply passage;
• wherein
• wherein the oil supply passage comprises:
• a flow passage disposed in the at least one back pressure member, wherein the flow passage comprises a first flow passage and a second flow passage, the first flow passage and the second flow passage are through holes penetrating the at least one back pressure member, the first flow passage is communicated with the first groove section, and the second flow passage is communicated with the second groove section;
• wherein an area of a first opening, communicated with the first groove section, of the first flow passage is a, and an area of a second opening, communicated with the second groove section, of the second flow passage is b, and a<b.