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EP-4102079-B1 - VACUUM PUMP AND VACUUM PUMP COMPONENT

EP4102079B1EP 4102079 B1EP4102079 B1EP 4102079B1EP-4102079-B1

Inventors

  • SUZUKI HARUKI
  • KABASAWA TAKASHI

Dates

Publication Date
20260506
Application Date
20210129

Claims (2)

  1. A vacuum pump (10), comprising: a first stage, comprising: a first plurality of Siegbahn exhaust mechanisms (60) in which a first plurality of helical grooves (62c) are provided on both faces of an upstream side and a downstream side of a first rotor disc (20) or a first stator disc (19, wherein an end portion (62c1) of one of the first plurality of helical grooves (62c) provided on the upstream side and a start portion of one of the first plurality of helical grooves (62c) provided on the downstream side are situated at least partially overlapping in a circumferential direction, and a width (Cc) of a first channel of a first switchback portion of the upstream side and the downstream side is equivalent or less than a depth (Hc) of a channel of the first Siegbahn exhaust mechanisms (60), wherein the first switchback portion is arranged on at least one of an outer circumferential side of the first rotor disc (20) and an inner circumferential side of the first stator disc (19); a second stage, comprising: a second plurality of Siegbahn exhaust mechanisms (60) in which a second plurality of helical grooves (62c) are provided on both faces of an upstream side and a downstream side of a second rotor disc (20) or a second stator disc (19), wherein an end portion (62c1) of one of the second plurality of helical grooves (62c) provided on the upstream side and a start portion of one of the second plurality of helical grooves (62c) provided on the downstream side are situated at least partially overlapping in a circumferential direction, and a width (Cc) of a second channel of a second switchback portion of the upstream side and the downstream side is equivalent or less than a depth (Hc) of a channel of the second Siegbahn exhaust mechanisms (60), wherein the second switchback portion is arranged on at least one of an outer circumferential side of the second rotor disc (20) and an inner circumferential side of the second stator disc (19), characterized in that the width (Cc) of the first channel of the first switchback portion is greater than the width (Cc) of the second channel of the second switchback portion.
  2. The vacuum pump according to claim 1, wherein a side portion of the helical groove at the end portion and a side portion of the helical groove at the start portion are at least partially situated on a same straight line.

Description

The present invention relates to a vacuum pump such as a turbomolecular pump. There is commonly known a turbomolecular pump, as a type of vacuum pump. This turbomolecular pump is configured to rotate rotor blades by electricity being applied to a motor within a pump main unit, and to exhaust gas by bouncing away gas molecules of gas (process gas) sucked into the pump main unit. One type of such a turbomolecular pump is called a "Siegbahn" type (Japanese Patent Nos. 6228839, 6353195, and 6616560). This Siegbahn type molecular pump has a plurality of helical groove channels formed, partitioned by ridge portions, in a gap between a rotor disc and a stator disc. In the Siegbahn type molecular pump, gas molecules dispersed throughout the helical groove channels are imparted with tangential-direction kinetic momentum by the rotor disc, giving an advantageous directionality toward an exhaust direction by the helical groove channels, and thus performing exhaust. EP3088744A1 provides a prior art example of a vacuum exhaust mechanism and compound vacuum pump that has, in at least either a stator disc to be disposed or a rotating disc to be disposed, a Siegbahn type molecular pump portion in which a spiral-shaped groove with a ridge portion and a root portion is engraved, and is structured to ensure high conductance at a returning flow channel formed at the outer periphery of the Siegbahn type molecular pump portion. Now in a vacuum pump such as the above-described Siegbahn type molecular pump, a compression ratio tends to be insufficient if there is only a single stage of a set of the rotor disc and the stator disc, and may be industrially unusable. Accordingly, multiple stages of sets of the rotor disc and the stator disc are used, to improve the compression ratio. However, if a flow within the helical groove channels of a prior stage is not appropriately connected to a flow within the helical groove channels of a next stage (following stage), the kinetic momentum of the gas molecules will be lost, and compression cannot be performed well. Accordingly, conventionally, the flow in the prior stage and the flow in the following stage have been connected by providing protruding portions (denoted by sign 600, etc., in Japanese Patent No. 6616560) or communicating holes (denoted by sign 501, etc., in Japanese Patent No. 6228839) between the helical groove channels of the prior stage and the helical groove channels of the following stage, thereby preventing loss of kinetic momentum relating to gas molecules, as disclosed in Japanese Patent Nos. 6228839, 6353195, and 6616560. Accordingly, shapes of rotor discs and stator discs have become complicated, necessitating costs for machining the protruding portions and the communicating holes. An object of the present invention is to provide a vacuum pump and a vacuum pump component part capable of improving compression at low costs. (1) In order to achieve the above object, an aspect of the present invention is a vacuum pump, including the features of the appended claim 1.(2) Also, in order to achieve the above object, in the vacuum pump according to the above (1), a side portion of the helical groove at the end portion and a side portion of the helical groove at the start portion may be at least partially situated on a same straight line. According to the above invention, a vacuum pump capable of improving compression at low costs can be provided. FIG. 1 is a longitudinal-sectional view of a turbomolecular pump according to an embodiment of the present invention;FIG. 2A is an enlarged view of part of FIG. 1;FIG. 2B is a further enlarged view of part of FIG. 2A;FIG. 3A is an explanatory diagram schematically illustrating an upstream side of a stator disc at portion indicated by line A-A in FIG.FIG. 3B is an explanatory diagram schematically illustrating a downstream side of the stator disc in FIG. 3A as viewed from an oblique angle;FIG. 4 is a perspective view in which part of an inner circumferential portion of the stator disc is enlarged;FIG. 5A is an explanatory diagram illustrating a positional relation of ridge portions according to the embodiment of the present invention;FIG. 5B is an explanatory diagram illustrating a modification relating to the positional relation of the ridge portions;FIG. 5C is an explanatory diagram illustrating another modification relating to the positional relation of the ridge portions;FIG. 5D is an explanatory diagram illustrating yet another modification relating to the positional relation of the ridge portions;FIG. 6A is an explanatory diagram schematically illustrating part of simulation results of compression effects of the stator disc according to the embodiment of the present invention; andFIG. 6B is an explanatory diagram schematically illustrating part of simulation results of compression effects of a stator disc according to a conventional structure. A vacuum pump according to an embodiment of the present invention will be described belo