Pump housing structure of three-axis multi-stage Roots pump

A pump housing structure of a three-axis multi-stage Roots pump, comprising a first-stage pump housing (1), a second-stage pump housing (2) and a third-stage pump housing (3), wherein the first-stage pump housing (1) is provided with a first center axial hole (4), a first left axial hole (5) and a first right axial hole (6), the first center axial hole (5) and the first left axial hole (6) form a first-stage rotor pump chamber (7) capable of accommodating a pair of first-stage Roots rotor axes, the first right axial hole (6) is an independent closed axial hole, one side of the first-stage pump housing (1) is fixedly connected to a driving end gear end cover (9);

• the other side of the first-stage pump housing (1) is fixedly mounted with a fixed bearing end cover (10), the fixed bearing end cover (10) is provided with three fixed bearing chambers (11) on its surface, and the three fixed bearing chambers (10) correspond to the first center axial hole (4), the first left axial hole (5) and the first right axial hole (6), respectively;
• an end surface at one side of the second-stage pump housing (2) is fixedly mounted on the fixed bearing end cover (10), the second-stage pump housing (2) is provided with a second center axial hole (14), a second a left axial hole (15) and a second right axial hole (16), the third-stage pump housing (3) is fixedly mounted on the other end surface of the second-stage pump housing (2), the third-stage pump housing (3) is provided with a third center axial hole (17), a third left axial hole (18) and a third right axial hole (19), the first center axial hole (4), the second center axial hole (14) and the third center axial hole (17) are coaxially connected, the first left axial hole (5), the second left axial hole (15) and the third left axial hole (18) are coaxially connected, the first right axial hole (6), the second right axial hole (16) and the third right axial hole (19) are coaxially connected, the end surface at an outer side of the third-stage pump housing (3) is fixedly mounted with a non-driving end bearing end cover (12), and a sum of an axial length of the second-stage pump housing (2) and the third-stage pump housing (3) is equal to an axial length of the first-stage pump housing (1).