Structure composition of roots vacuum pump

Structure composition of roots vacuum pump

The ultimate vacuum of the roots pump depends on the structure and manufacturing accuracy of the pump itself but also depends on the ultimate vacuum of the front pump. In order to improve the ultimate vacuum of the pump, the roots pump can be used in series. A roots pump works on a similar principle to a roots blower. Due to the continuous rotation of the rotor, the gas is drawn from the air inlet into the space between the rotor and the pump shell V0, and then discharged through the exhaust port. Since the v0 space is completely closed after suction, there is no compression or expansion of the gas in the pump cavity. But when the top of the rotor turned the edge of the exhaust port, V0 space and the exhaust side are connected, because the exhaust side gas pressure is higher, there is a part of the gas back to the space V0, so that the gas pressure suddenly increased. As the rotor continues to rotate, the gas is discharged from the pump. Roots pump in the pump cavity, there are two "8" shapes of the rotor vertically installed in a pair of parallel shafts, driven by a pair of gear ratio of 1 reverse synchronous rotation movement. There is a certain gap between the rotor and the inner wall of the pump shell, which can achieve high-speed operation.

Structure composition of the two rotors of the roots vacuum pump in the pump body layout, determines the overall structure of the pump at home and abroad roots vacuum pump overall structure layout generally have three kinds of scheme :1 Vertical: two levels of the axis of the rotor is installed, but two rotor axis plane and vertical plane of the horizon, this kind of structure, into the exhaust outlet of pump set horizontally, assembly and connection pipe is more convenient But the downside is the center of gravity of the pump is too high, poor stability in high speed, so in addition to the small specifications of the pump, using this kind of structural type is not too much. 2 Horizontal: the axis of the two rotors is installed horizontally, the plane of the axis of the two rotors is horizontal, the inlet of the pump of this structure is above the pump, and the exhaust port is below the pump (there is also the opposite). The exhaust port is generally connected in the horizontal direction, so the inlet and exhaust direction are vertical to each other Vent by one tee to ask two directions, one end of the exhaust pipe, the other end of the death or bypass valve when using this structure is characterized by a low center of gravity, high speed when the stability is good Domestic and foreign large and medium-sized pump three vertical shaft type: this kind of structure is used more abroad some two rotors of roots pump axis and the vertical plane of the installation The assembly clearance of this structure is easy to control, the assembly of the rotor is convenient, and the floor area is small, but the assembly and disassembly of the gear and other transmission mechanisms is inconvenient, and the lubrication device is more complex. When the overall structure is decided, the structure and shape of the pump body itself are correspondingly determined Roots pump with relief valve: in order to prevent overload caused by accidents, the roots pump is equipped with a more reliable safety protector, that is, in the bypass pipe is equipped with a relief valve exhaust port in the specified pressure, the relief valve is closed When the exhaust pressure in excess of the prescribed pressure, overflow valve open automatically be caused excessive hand, vent pressure became normal after, overflow valve to close on its own It can automatically adjust, also allow differential pressure of the pump device, so the overflow valve is the biggest advantage is to make the roots pump together with the backing pump, can continuous operation in all kinds of pressure range By adopting this design, the stop-time of the vacuum vessel in a rough vacuum can be shortened by 30~50%. For larger pumps, the relief valve is installed in the bypass pipeline outside the pump, and for smaller pumps, the relief valve is installed in the pump shell. Roots pumps with steam condenser: where steam is required to be pumped, the pumping unit must be designed to condense the steam condenser. The condenser can be installed before or after the pump, not on the pump body of the Roots pump. In some cases, the condensation of heat absorption can reduce the heating of the Roots pump Assuming that a multiple condensers is used, the steam can flow smoothly through the duct with the proper solvent to remove dirt during maintenance.

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