JP2003042091A - Improved lubricating device for regenerative vacuum pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lubricating device avoiding lack of lubrication of an upper bearing supporting a vertical shaft of a vacuum pump. SOLUTION: This invention relates to the lubricating device lubricating an upper side bearing and a lower side bearing of a regenerative type vacuum pump or a vacuum pump including a regeneration section having a vertical shaft 16 supported by the upper side bearing and the lower side bearing. The lubricating device includes an axial direction bore 18 extending along the shaft 16 and the axial direction bore 18 communicates to a radial direction hole 12 aligned with the lower side bearing and to a radial direction hole 14 aligned with the upper side bearing. An open lower end of the axial direction bore 18 extends into a reservoir for the shaft 16 storing lubricating fluid. The radial direction hole 12 aligned with the lower side bearing is formed on a tapered surface of the axial direction bore 18.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a regenerative vacuum pump or a vacuum pump having a regenerative section having a vertical shaft rotatable at high speed by bearings at both ends, and more particularly, to a vacuum pump having a regenerative section. It relates to a lubricating device for the bearing of such a vacuum pump. [0002] In a regenerative vacuum pump, the rotor is
It is mounted on a vertical shaft for rotation in the surrounding stator. The shaft is supported by upper and lower bearings that require lubrication. To facilitate lubrication of both bearings, the vertical shaft has an axial center bore,
The axial center bore communicates with a radial hole aligned with the upper bearing and a radial hole aligned with the lower bearing for supplying lubricating fluid to both bearings. [0003] Lubricating fluid is pulled upwardly from the reservoir through a central axial bore in the form of a thin film and initially reaches a radial bore aligned with the lower bearing. It is known to utilize the centrifugal force generated by the rotating shaft to ultimately reach a radial hole that is aligned with the upper bearing. If a small ledge or ledge is available at the lower end of the axial bore, the lubricating fluid forms a tapered surface of the lubricating fluid itself within the straight axial bore. In known lubrication systems, a radial bore in alignment with the lower bearing terminates the tapered surface, thus preventing further upward flow in the axial bore, thereby depriving the upper bearing of lubrication. To It is an object of the present invention to avoid this disadvantage. In accordance with the present invention, there is provided a regenerative vacuum pump or a vacuum pump including a regenerative section in which a rotatable, generally vertical shaft is supported by upper and lower bearings. A lubrication device for lubricating an upper bearing and a lower bearing, comprising an axial bore extending along a shaft, the axial bore being radially aligned with the lower bearing and radially aligned with the upper bearing. The lower end, which communicates with the bore and has an open axial bore, extends into the shaft reservoir for containing the lubricating fluid, and a radial bore aligned with the lower bearing is formed in the tapered surface of the axial bore. Is done. An embodiment of the present invention will be described below with reference to the accompanying drawings. Regeneration section 1 and molecular aspiration (Holweck)
Reference is first made to FIG. 1 which shows a prior art composite vacuum pump having a section 2. The vacuum pump comprises a casing 3, which is made of a number of different body parts bolted or otherwise fixed to each other and has a seal between them associated with them. . A vertical shaft 6 is provided in the casing 3.
The vertical shaft 6 is provided with an upper bearing 4
And the lower bearing 5. The shaft 6 is rotatable about a longitudinal axis and is driven by an electric motor 7 surrounding the shaft 6. A rotor 9 is fixedly mounted on the shaft 6,
Rotates with. An axial bore 8 extends substantially the entire length of the shaft 6 and communicates with a radial oil hole 8 ′ for supplying lubricating fluid from the shaft fluid lubrication reservoir to the upper bearing 4 and the lower bearing 5. Next, reference is made to FIG. It is known that if a small ledge is available at the bottom end of the axial bore (as shown), a lubricating fluid, such as oil, will form a tapered surface of the lubricating fluid itself within the straight axial bore. Next, reference is made to FIG. It is known to provide two sets of radial holes 14, 12, one end of which communicates with an axial bore 18 of a rotatable shaft 16 and the other end of which communicates with an upper bearing and a lower bearing, respectively.
As the shaft 16 rotates, the centrifugal force of the shaft 16 pushes the lubricating fluid from the reservoir through the open lower end of the shaft 16 along the inner surface of the axial bore 18 in the form of a thin film. However, the lower radial hole 12 effectively terminates the tapered surface of the lubricating fluid film and prevents further upward flow of the film in the axial bore 18 thereby lubricating the upper bearing. Make it deficient. Referring to FIG. 4 in accordance with the present invention, a lower radial hole 12 aligned with the lower bearing is formed in a tapered surface of an axial bore 18. This mechanical taper keeps the lubricating fluid flowing out of the lower radial hole 12 and allows the lubricating fluid to flow through the lower radial hole 1.
It accomplishes both that it continues to flow past the upper bearing through the upper radial hole 14 beyond the two. The flow rate of the lubricating fluid discharged from the lower radial hole 12 and the upper radial hole 14 depends on the diameter of the oil discharge hole, the taper surface angle, the taper height in the taper surface, and the taper surface diameter. .

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a known compound vacuum pump including a regeneration section. FIG. 2 is a detailed view of a known lubricating device showing how the lubricating fluid forms a tapered surface of the lubricating fluid itself in a straight axial bore. FIG. 3 is similar to FIG. 2 except that the prior art shows how excess lubricating fluid is supplied to the lower bearing and how insufficient lubricating fluid is supplied to the upper bearing. FIG. FIG. 4 is a detailed view similar to FIGS. 2 and 3, except that it illustrates a lubricating device according to the invention. [Description of Signs] 1 Regeneration section 2 Molecular absorption section 3 Casing 4 Upper bearing 5 Lower bearing 6 Vertical shaft 8 Axial bore 12 Lower radial hole 14 Upper radial hole 16 Vertical shaft 18 Axial bore

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Claims (1)

Claims 1. An upper bearing and a lower bearing of a regenerative vacuum pump or a vacuum pump comprising a regenerative section, wherein a rotatable substantially vertical shaft is supported by an upper bearing and a lower bearing. A lubrication device for lubricating, comprising: an axial bore extending along the shaft, the axial bore communicating with a radial hole aligned with the lower bearing and a radial hole aligned with the upper bearing. The open lower end of the axial bore extends into a shaft reservoir for containing a lubricating fluid, and a radial hole aligned with the lower bearing is formed in a tapered surface of the axial bore. A lubricating device characterized by that: