1, the overall structure of the roots vacuum pump
Roots vacuum pump arrangement determines the overall structure of the pump. At present, the overall structure of the domestic and foreign Roots vacuum pumps are basically three types:
Intake and exhaust ports arranged horizontally, assembly and connecting pipe (1) vertical structure is more convenient. But the center of gravity of the pump higher, poor stability at high speeds, so this type are used for small pump.
(2) horizontal pump inlet in the upper and lower exhaust port. Sometimes in order to connect the vacuum system piping installation convenience, you can pick from the horizontal vent out that the intake and exhaust direction is perpendicular to each other. In this case, the exhaust port may be left or right opening in both directions, in addition to the exhaust duct connected to the outer end, and the other end connected to the bypass valve or blocked. This pump structure low center of gravity, good stability at high speeds. Generally large and medium-sized pump more use of such structures.
(3) two pump rotor shaft perpendicular to the horizontal installation. This structure is easy to assemble gap control, easy rotor assembly, small pump footprint. But the higher center of gravity and the gear pump disassembly inconvenience, lubrication mechanism is relatively complex. Found only in foreign products.
2. Vacuum pump Transmission
Roots vacuum pump through a pair of two rotors are precision gear to achieve its relatively synchronous operation. Coupled with the motor drive shaft coupling through. There are two major structural arrangement in the drive: one is that the motor and the rotor gear on the same side as shown. Driven by the motor rotor end gear driven directly pass over, so little active rotor shaft torsional deformation, the gap between the two rotors will not reverse the drive shaft of the large deformation and change, so the gap between the rotor during operation process uniformity. The biggest drawback of this approach is that the drive: a drive shaft with three bearings, increasing the difficulty of machining and assembly of the pump, disassembly and adjustment of the gear is not it; b overall structure is not symmetrical, the center of gravity of the pump motor and gear bias. box side.
The other is an electric motor and transmission gears respectively mounted on both sides of the rotor. This form of symmetry so that the overall structure of the pump, but the larger the drive shaft torsional deformation. To ensure the rotor clearance during operation of uniform requirements should be sufficient rigidity shaft coupling between the shaft and the rotor to be fastened (rotor and shaft are already welded or cast one of the structure). This structure of root vacuum pump is very easy disassembly, it is widely used.