RU2758659C1 - Labyrinth seal - Google Patents

Abstract

FIELD: mechanical engineering.

SUBSTANCE: invention relates to non-contact labyrinth-type sealing devices for sealing bearing assemblies of machines. The labyrinth seal contains disks combined to obtain a long winding gap with alternating annular protrusions and depressions at the end, one of which is mounted on a rotating shaft, and the second is planted in the hole of the bearing cover. The annular protrusions of the disk rotating together with the shaft are made with a decreasing height from the center of the disk to the periphery, while the annular depressions of the fixed disk installed in the bearing cover are made with a decreasing depth from the center of the disk to the periphery, and in the fixed disk in the lower part there is an external longitudinal blind groove and a number of radial holes connecting a common drainage hole in the housing with each of the labyrinth chambers formed by combining the protrusions of the movable disk with the depressions of the fixed disk.

EFFECT: increased manufacturability of the seal.

1 cl, 3 dwg

Description

The seal belongs to the labyrinth-type non-contact sealing devices for sealing machine bearing assemblies.

It is known a labyrinth seal containing two bushings with alternating annular protrusions and depressions on the end surfaces, one of which is seated on a shaft and rotates with it as a whole, and the other is stationary and is part of the housing or bearing cap, and in the assembly, the protrusions of the bushings are seated with a small gap in the depression of the counter sleeve. The resulting long tortuous gap between the bushings has a high hydrodynamic resistance and prevents the fluid from flowing out of the working cavity of the device into the environment. For a greater sealing effect, the gap between the bushings is filled with grease [1].

Known labyrinth seal [2], containing a housing with concentric grooves, which are placed with a gap around the perimeter of the counter protrusions of the sleeve mounted on the shaft. In order to increase reliability, a cover is rigidly fixed to the body, covering the sleeve and forming an internal cavity filled with grease, while the sleeve is made with oppositely located shoulders, on which rolling bodies are installed in cages, through which the lateral surfaces of the sleeve are mated with the surfaces of the body and the cover, and grooves are made on the inner cylindrical surface of the sleeve, into which the sealing elements are hermetically installed.

A common disadvantage of the above structures is a large power loss at high shaft rotation speeds due to the significant viscous resistance of the grease in the gaps of the devices and a decrease in the reliability of the seal due to the likelihood of a heated grease with increased fluidity flowing out of the gap.

The closest analogue is a labyrinth seal [3] containing a disk stationary with grooves on the end surface and a rotating disk mounted on the shaft with protrusions entering the grooves of the stationary disk. In order to increase the tightness, radial grooves are made in the protrusions, and tangential channels are made in the stationary disk, connecting the grooves with the drainage.

The disadvantage of the design is that the holes for liquid discharge, located tangentially to the outer cylindrical surface of the rotating disk and perpendicular to the axis of rotation, will pass through the protrusions of the stationary disk, therefore, normal liquid discharge will become possible only in rare phases of device operation, when the holes are rotating and not rotating discs are combined, which significantly impairs the efficiency of drainage. For permanent drainage of liquid, independent of the phase of operation of the device, it is necessary to provide a complex spatial arrangement of drainage holes tangentially to the labyrinth chambers and at an angle to the axis of rotation of the shaft, which is also a disadvantage. From the point of view of manufacturing elements of such a seal, the design is low-tech.

The technical result is to improve the manufacturability of the seal.

The specified technical result is achieved by the fact that the labyrinth seal contains disks that are aligned to obtain a long tortuous gap with alternating annular protrusions and depressions at the end, one of which is installed on the rotating shaft, and the second is fitted into the hole of the bearing cover. The annular protrusions of the disk rotating together with the shaft are made with a decreasing height from the center of the disk to the periphery, while the annular depressions of the stationary disk installed in the bearing cover are made with a decreasing depth from the center of the disk to the periphery, and an external longitudinal blind is made in the stationary disk in the lower part a groove and a number of radial holes connecting a common drain hole in the housing with each of the labyrinth chambers formed by aligning the protrusions of the movable disk with the depressions of the stationary disk.

The stepped configuration of the labyrinth chambers makes it possible to simplify the spatial arrangement of the drainage holes, to make them in a row, radially extending from each labyrinth chamber. From the point of view of manufacturing, the radial arrangement of the holes is more technologically advanced than the tangential one presented in [3].

In addition, in order to increase the reliability of the seal, a radial protrusion is made on the outer cylindrical surface with an axial protrusion beyond the end of the stationary disk. The resulting local reduction in the gap at the entrance to the labyrinth performs a guiding function. It prevents the fluid from flowing into the labyrinth gap, and facilitates its dropping into a zone remote from the gap on the housing wall by centrifugal forces arising from the rotation of the ring.

The design is illustrated by drawings, where figure 1 shows a longitudinal section of the labyrinth seal, figure 2 shows the upper part of the disc connection in section, figure 3 shows the lower part of the disc connection in section.

The labyrinth seal consists of a movable disk 1, installed on the shaft 2 and rotating with it as a whole, having a protrusion B on the outer cylindrical surface, aligned with the disk 1 along the depressions and tops of a stationary disk 3, installed in the hole of the bearing cover, or being part of the cover as shown in figure 1 and having a groove D in the lower part, aligned with the drain hole in the housing 4, and a series of holes connecting the groove to each of the labyrinth chambers; housing 4 with a drain hole from the groove cavity D into the crankcase of the device to be sealed.

The seal works as follows.

Oil or other liquid sealed medium, passing through the bearing assembly, enters the end surface of the disk 1 rotating on the shaft. Under the action of centrifugal forces, the liquid flows to the peripheral zone of the disk 1 to the radial protrusion B near the gap between the disks. Since the protrusion B forms the narrowest part of the gap between the discs 1 and 3, the hydraulic resistance to the penetration of liquid into the gap is large and it is easier to drop from the protrusion B onto the wall of the housing 4 than it penetrates into the gap. Part of the liquid trapped in the gap slowly moves along a long, winding path through the labyrinth chambers formed by the protrusions and valleys of the rotating and non-rotating discs. In each chamber, a certain amount of liquid flows into the drain hole under the influence of gravity and centrifugal force from the rotation of the movable disk. Since in each labyrinth chamber there is an outflow of a part of the liquid, the total flow of liquid through the gap decreases. At the same time, the seal is able to operate at significant speeds with minimal power loss.

Sources of information:

1. Design and calculation of gear reducers. Reference manual. Kudryavtsev V.N., Derzhavets Yu.A., Glukharev E.G. L. "Mechanical Engineering". 1971, 328 p.

2. Patent SU No. 1714268 Labyrinth seal. Perm Scientific Research Technological Institute. Application 09.07.90 Publ. 02/23/92 g.

3. Patent SU No. 1086265. Labyrinth seal. Kherson Industrial Institute. Application 03.17.83 Publ. 04/15/84 g.

Claims (2)

1. Labyrinth seal containing a labyrinth gap formed by combining a disk located on the shaft and rotating together with the shaft with alternating annular protrusions and depressions on the end surface with a stationary disk with alternating annular projections and depressions on the end surface responding to the movable disk, a housing with a drain hole , characterized in that the labyrinth gap is made stepwise due to the decreasing in height of the end protrusions of the movable disk from the center of the disk to the periphery and decreasing in depth of the end cavities of the stationary disk from the center of the disk to the periphery, and a blind groove is made in the stationary disk in its lower part, which is aligned with a drain hole in the housing, and a number of holes extending from it in the radial direction to each of the labyrinth chambers. 2. Labyrinth seal according to claim 1, characterized in that the labyrinth gap has a local decrease at the entrance from the side of the cavity to be sealed due to the design of a movable disk with a radial protrusion on the outer cylindrical surface with an axial overhang beyond the end of the stationary disk.

Images