Abstract: A multiple-type pump has a simple construction and superior durability. The multiple-type pump has the capacity to perform air evacuation at high velocities in the atomospheric pressure zone to high vacuum zone range. The multiple-type pump includes: a screw type pump air transfer portion arranged at a downstream portion of the outer surface of a rotor and has a plurality of screw threads and screw grooves with a width of 5 mm or more; a turbo-molecular type pump air transfer portion arranged at an upstream portion and has a plurality of vanes and air transfer grooves; vanes having vane widths of 3 mm or less at the upstream edge, and formed so that the downstream edge is continuous with the upstream edge of the screw threads; a downstream edge of the base of the air transfer grooves formed so as to be continuous with the upstream edge of the base of the screw grooves.

Abstract: In the case of a vacuum pump, having a screw groove, of the present invention, a rotor is disposed inside a stator with an extremely small clearance provided in-between, under which condition the rotor is designed to rotate at a high speed. The upper and lower end faces of the aforementioned stator are supported with sliding members interposed in-between, thereby enabling the stator to perform sliding rotation. Between the stator and a pump housing is provided a clearance r. In the event that stress corrosion cracking occurs to the rotor, then part of the rotor comes into contact with the stator, thereby causing the stator to be deformed radially outward. Even when such deformation takes place, the stator rotates together with the rotor, since the clearance r is provided on the outside periphery of the stator, with the result that consequent rotational friction causes the rotor to decelerate.

Abstract: A multiple-type pump has a simple construction and superior durability. The multiple-type pump has the capacity to perform air evacuation at high velocities in the atomospheric pressure zone to high vacuum zone range. The multiple-type pump includes: a screw type pump air transfer portion arranged at a downstream portion of the outer surface of a rotor and has a plurality of screw threads and screw grooves with a width of 5 mm or more; a turbo-molecular type pump air transfer portion arranged at an upstream portion and has a plurality of vanes and air transfer grooves; vanes having vane widths of 3 mm or less at the upstream edge, and formed so that the downstream edge is continuous with the upstream edge of the screw threads; a downstream edge of the base of the air transfer grooves formed so as to be continuous with the upstream edge of the base of the screw grooves.

Abstract: In the case of a vacuum pump, having a screw groove, of the present invention, a rotor is disposed inside a stator with an extremely small clearance provided in-between, under which condition the rotor is designed to rotate at a high speed. The upper and lower end faces of the aforementioned stator are supported with sliding members interposed in-between, thereby enabling the stator to perform sliding rotation. Between the stator and a pump housing is provided a clearance r. In the event that stress corrosion cracking occurs to the rotor, then part of the rotor comes into contact with the stator, thereby causing the stator to be deformed radially outward. Even when such deformation takes place, the stator rotates together with the rotor, since the clearance r is provided on the outside periphery of the stator, with the result that consequent rotational friction causes the rotor to decelerate.

Abstract: A multiple-type vacuum pump has a simple construction and superior durability. The multiple-type vacuum pump has the capacity to perform air evacuation at high velocities in the low to high vacuum zone range. The multiple-type vacuum pump includes: a screw type pump air transfer portion arranged at a downstream portion of the outer surface of a rotor and has a plurality of screw threads and screw grooves with a width of 5 mm or more; a turbo-molecular type pump air transfer portion arranged at an upstream portion and has a plurality of vanes and air transfer grooves; vanes having vane widths of 3 mm or less at the upstream edge, and formed so that the downstream edge is continuous with the upstream edge of the screw threads; a downstream edge of the base of the air transfer grooves formed so as to be continuous with the upstream edge of the base of the screw grooves.

Abstract: A multiple-type vacuum pump has a simple construction and superior durability. The multiple-type vacuum pump has the capacity to perform air evacuation at high velocities in the low to high vacuum zone range. The multiple-type vacuum pump includes: a screw type pump air transfer portion arranged at a downstream portion of the outer surface of a rotor and has a plurality of screw threads and screw grooves with a width of 5 mm or more; a turbo-molecular type pump air transfer portion arranged at an upstream portion and has a plurality of vanes and air transfer grooves; vanes having vane widths of 3 mm or less at the upstream edge, and formed so that the downstream edge is continuous with the upstream edge of the screw threads; a downstream edge of the base of the air transfer grooves formed so as to be continuous with the upstream edge of the base of the screw grooves.