Double-acting hydrodynamic axial sliding bearing

Abstract

The invention relates to a double-acting hydrodynamic axial sliding bearing (1) comprising: a bearing housing (2) in which there is located a first bearing body (3) having a first axial bearing surface (4), and a second bearing body (5) having a second axial bearing surface (6); and a shaft (7) comprising at least one thrust collar (8), wherein the at least one thrust collar is located in the bearing housing between the first axial bearing surface and the second axial bearing surface and can be supported against the first or second axial bearing surface depending on the axial position of the shaft, and a first or second annular chamber (9, 12) is formed depending on whether the thrust collar is supported against the first or second axial bearing surface.

Description

[0001] Description

[0002] Double-acting hydrodynamic axial plain bearing

[0003] The invention relates to a double-acting hydrodynamic axial plain bearing according to the preamble of independent patent claim 1.

[0004] Double-acting hydrodynamic axial plain bearings are widely used for supporting axially loaded shafts.

[0005] A generic double-acting hydrodynamic axial plain bearing comprises a bearing housing and a shaft with a tracking disc. Axial bearing surfaces are formed at the respective axial ends of the bearing housing, against which the tracking disc of the shaft to be supported can rest. Even though the following discussion refers to the tracking disc being in contact with the bearing surfaces, in a hydrodynamic bearing there is never direct contact between the tracking disc and the corresponding bearing surface. There is always a lubricating film between the tracking disc and the bearing housing. Bearing oil is typically used as the lubricant.

[0006] When the track disc rests on one of the bearing surfaces, an annular chamber is formed which is closed off from the rest of the bearing housing and which is limited in the radial direction by the outer diameter of the shaft and the inner diameter of the bearing body, and in the axial direction by an axial wall (e.g. wall of the bearing housing) and a side of the track disc facing the axial bearing surface.

[0007] The bearing oil and / or air can collect in the annular chamber. In the case of multi-phase filling states (air and oil) in the "chamber", the compressibility of the air results in a delay between the acting force and the counterforce on the axial bearing. This delay can lead to instability in the shaft-bearing system, which is characterized by pressure differences between the two chambers. The multi-phase state can arise during operation if the amount of oil made available is not sufficient to always fill the chamber completely with oil. The pressure differences between the annular chamber and the rest of the space exert an axial force on the shaft, which moves the shaft axially towards the shaft collar side that was not in contact until then.This creates a gap in the previously contacting annular chamber, which favors the presence of air in this chamber during the next oscillation period because the amount of oil supplied to the bearing is generally not sufficient to completely fill the lubrication gap on the non-contacting side with oil. When the shaft then moves from the initially non-contacting side to the initially contacting side, the air present there must first be displaced. If this does not happen quickly enough, the instability described above with the associated axial forces can arise. These alternating axial forces generate an axial vibration in the shaft train, which can be further increased by any axial natural frequency present in the shaft train. The resulting axial vibration can lead to damage to or failure of the axial bearing.

[0008] In addition to axial plain bearings with one track disc, axial plain bearings with two track discs are also known, which also lead to the instabilities described above.

[0009] The object of the invention is therefore to provide a double-acting hydrodynamic axial plain bearing in which the axial vibration excitation is avoided or at least significantly reduced.

[0010] The problem is solved by the features of independent claim 1. Further embodiments of the invention, which can be used individually or in combination with one another, are the subject of the dependent claims.

[0011] The double-acting hydrodynamic axial plain bearing according to the invention, comprising a bearing housing with a first bearing body arranged in the bearing housing with a first axial bearing surface, and with a second bearing body arranged in the bearing housing with a second axial bearing surface, as well as a shaft comprising at least one track disc, wherein the at least one track disc is arranged in the bearing housing between the first axial bearing surface and the second axial bearing surface and can be supported on the first or second axial bearing surface depending on the axial position of the shaft, and depending on whether the track disc is supported on the first or second axial bearing surface,

[0012] - a first annular chamber is formed which is closed off from the rest of the bearing housing and which is limited in the radial direction by the outer diameter of the shaft ( 7 ) and the inner diameter of the first bearing body , and in the axial direction by a first axial wall and the side of the track disc facing the first axial bearing surface , or

[0013] - a second annular chamber is formed which is closed off from the rest of the bearing housing and is delimited in the radial direction by the outer diameter of the shaft and the inner diameter of the second bearing body, and in the axial direction by a second axial wall and the side of the track disc facing the second axial bearing surface, is characterized in that a pressure equalization device is provided, by means of which a pressure difference between the first or second annular chamber and the remaining space separated from the first or second annular chamber can be reduced or compensated for. As a result of the pressure equalization, the axial vibrations resulting from the alternating axial forces are completely eliminated, or at least effectively reduced, so that there is no damage to or even failure of the bearing.

[0014] A first embodiment of the invention provides that the pressure equalization device comprises a first and a second pressure equalization line, which are arranged and designed such that one end of the respective pressure equalization line connects the first or second annular chamber, which is designed depending on the position of the track disc, with the environment, and the respective other pressure equalization line connects the remaining space separated from the first or second annular chamber with the environment.

[0015] Pressure equalization is not achieved directly between the two annular chambers, but rather between the individual spaces (chambers) and the surrounding area. This design is particularly simple to manufacture and requires little construction effort, and can even be retrofitted if necessary.

[0016] A further embodiment of the invention provides that the pressure equalization device comprises a first and a second pressure equalization line, which are arranged and designed in such a way that one end of the pressure equalization lines opens into the first or second annular chamber formed depending on the position of the track disc, and the other ends of the pressure equalization lines are in operative connection with one another directly or via a pressure equalization chamber.

[0017] By means of the lines communicating directly or internally with one another, pressure equalization can again be easily achieved between the respective annular chamber and the space separated from the annular chamber. This solution can also be implemented subsequently if necessary. A further alternative embodiment of the invention is characterized in that the pressure equalization device comprises a first and a second pressure equalization line which are arranged and designed such that the first end of the respective pressure equalization lines opens into the first or second annular chamber formed depending on the position of the track disc, and the other end of the respective pressure equalization line opens into the space separated from the annular chamber.

[0018] Such a solution has lower storage losses than the previous solution.

[0019] Further advantages of the invention are explained below using exemplary embodiments.

[0020] It shows :

[0021] - Fig. 1: A first embodiment of a double-acting hydrodynamic axial plain bearing according to the invention, with pressure equalization with respect to the environment.

[0022] - Fig. 2: A second embodiment of a device according to the invention with pressure equalization by means of a pressure equalization chamber.

[0023] - Fig. 3: A third embodiment of a double-acting hydrodynamic axial plain bearing according to the invention, with internal pressure equalization by means of two separate pressure equalization lines.

[0024] - Fig. 4: A third embodiment of a double-acting hydrodynamic axial plain bearing according to the invention, with two track discs.

[0025] The figures each show only schematic representations of the double-acting hydrodynamic axial plain bearing according to the invention and are not necessarily to scale. Essentially, only the components necessary for the invention are shown. Identical or functionally identical components are provided with the same reference numerals throughout the figures. The double-acting hydrodynamic axial plain bearing shown is an exemplary embodiment of such a bearing; there are other exemplary embodiments on the market which differ from this and to which the invention can be applied and which are covered by the scope of protection of the invention.

[0026] Fig. 1 shows a first embodiment of a double-acting hydrodynamic axial plain bearing 1 according to the invention. The axial plain bearing 1 comprises a bearing housing 2, which can also be designed in several parts for easier assembly. On the axial walls 10, 13 of the bearing housing 2, bearing bodies 3, 5 are formed, each with an axial contact surface 4, 7, on which a correspondingly designed shaft collar 8 of the shaft 7 to be supported can be supported. Depending on the axial (end) position of the shaft 7 or the track disc 8:

[0027] - a first annular chamber 9 is formed, which is closed off from the rest of the bearing housing 2 and which is limited in the radial direction by the outer diameter DW of the shaft 7 and the inner diameter dK of the first bearing body 3, and in the axial direction by the first axial wall 10 and the side 11 of the track disc 2 facing the first axial bearing surface 4, or

[0028] - a second annular chamber 12 is formed which is closed off from the rest of the bearing housing 2 and which is delimited in the radial direction by the outer diameter DW of the shaft 7 and the inner diameter dK of the second bearing body 5, and in the axial direction by the second axial wall 13 and the side 14 of the track disc (8) facing the second axial bearing surface 6.

[0029] Fig. 1 shows the position in which the tracking disc is in the first end position and the first annular chamber 9 is formed. In this position, the first annular chamber 9 contains bearing oil and air. Due to the multi-phase filling states (air and oil) in the annular chamber 9, the compressibility of the air results in a delay between the acting force and the counterforce on the axial bearing. This delay can lead to instability of the shaft-bearing system, which is characterized by pressure differences between the annular chamber 9 and the remaining space 15 separated from the first annular chamber 9. In order to compensate for the pressure differences, a pressure compensation device is provided.The pressure equalization device comprises a first and a second pressure equalization line 16, 17, which are arranged and designed such that a first end of the respective pressure equalization line 16, 17 connects the first or second annular chamber 9, 12, formed depending on the position of the track disc 8, with the environment, and the respective other pressure equalization line 9 connects the remaining space 15 separated from the first or second annular chamber 9, 12 with the environment. This enables extensive pressure equalization between the spaces 9 or 12 and 15 (largely) separated by the track disc, thereby avoiding or at least significantly reducing the instability of the shaft-bearing system. The pressure equalization lines 16, 17 can be formed by simple bores in the bearing housing 2.

[0030] Fig. 2 shows a second embodiment of a double-acting hydrodynamic axial plain bearing 1 according to the invention. The basic structure corresponds to the axial plain bearing described in Fig. 1, to whose more detailed description reference is therefore made here. The essential difference compared to the first embodiment is that in the embodiment according to Fig. 2 the pressure equalization lines 16, 17 are directly connected to one another in that one end of the pressure equalization lines 16, 17 opens into the first or second annular chamber 9, 12 formed depending on the position of the track disc 8, and the respective other ends of the pressure equalization lines 16, 17 are operatively connected to one another directly or, as shown in the embodiment, via a pressure equalization chamber 18. Both embodiments, with or without a equalization chamber, enable effective pressure equalization between the first or second annular chamber 9 or 12 and the pressure supplied by the first or second annular chamber 9, 12.second annular chamber 9 or 12 separated space 15 and thereby effectively prevent axial vibrations of the shaft 13. The pressure compensation chamber 18 is optional, whereby the pressure compensation chamber can dampen pressure surges of the multi-phase fluid in the pressure compensation lines 16, 17.

[0031] Fig. 3 shows a third exemplary embodiment of a double-acting hydrodynamic axial plain bearing 1 according to the invention. This exemplary embodiment largely corresponds to the structure of the axial plain bearing 1 from Fig. 2, to which reference is made for a detailed description. In contrast to the exemplary embodiment according to Fig. 2, the pressure compensation lines 16, 17 are not connected to one another directly or via a pressure compensation chamber. Rather, the pressure compensation lines 16, 17 are arranged such that the first end of the respective pressure compensation lines 16, 17 opens into the first or second annular chamber 9, 12, which is formed depending on the position of the track disc 8, and the respective other end of the pressure compensation line 16, 17 opens independently of one another into the space 15 separated from the first or second annular chamber 9, 12.

[0032] The embodiment according to Fig. 3 also enables effective pressure equalization between the annular chambers 6, 8 and thereby prevents axial vibrations of the shaft 13, which could otherwise lead to damage or even destruction of the bearing.

[0033] Fig. 4 shows a fourth embodiment of a double-acting hydrodynamic axial plain bearing 1 according to the invention. In this case, it is a bearing with two track disks 8 and 8a, the annular chambers 9 and 12 are formed by the outer diameter of the shaft dw, the inner diameter of the axial bearings dk, the inner surfaces of the track disks 11 and 14 and the outer surfaces 10 and 13 of an intermediate part of the bearing housing 2. In the case of a combined axial-radial plain bearing, this intermediate part of the bearing housing 2 can contain the radial plain bearing and be designed as a separate component. In this example, pressure compensation can be achieved by pressure compensation lines 16 and 17 in the bearing housing.The pressure equalization lines described in this invention are, by definition, not limited to bores or other closed channels, but also include open channels such as channels / grooves milled into the bearing housing. In principle, all of the pressure equalization measures described can also be retrofitted to existing bearings. The effort required and the costs associated with such a conversion are manageable. At the same time, axial vibrations of the shaft are prevented, thus ensuring significantly safer operation of the bearing.

Claims

Patent claims 1. Double-acting hydrodynamic axial plain bearing (1), comprising a bearing housing (2) with a first bearing body (3) arranged in the bearing housing (2) with a first axial bearing surface (4), and with a second bearing body (5) arranged in the bearing housing (2) with a second axial bearing surface (6), as well as a shaft (7) comprising at least one track disc (8), wherein the at least one track disc (8) is arranged in the bearing housing (2) between the first axial bearing surface (4) and the second axial bearing surface (6) and can be supported on the first or second axial bearing surface (4, 6) depending on the axial position of the shaft (7), and depending on whether the track disc (8) is supported on the first or second axial bearing surface (4, 6), - a first annular chamber (9) is formed, which is closed off from the rest of the bearing housing (2) and which is defined in the radial direction by the outer diameter (D w) of the shaft (7) and the inner diameter (d K ) of the first bearing body (3) , and in the axial direction by a first axial wall (10) and the side (11) of the track disc (2) facing the first axial bearing surface (4) , or - a second annular chamber (12) is formed, which is closed off from the rest of the bearing housing (2) and which is defined in the radial direction by the outer diameter (D w ) of the shaft (7) and the inner diameter (d K ) of the second bearing body (5), and in the axial direction by a second axial wall (13) and that of the second axial bearing surface (6) facing side (14) of the track disc (8) is characterized in that a pressure compensation device is provided, via which a pressure difference between the first or second annular chamber (9, 12) and the remaining space (15) separated from the first or second annular chamber (9, 12) can be reduced or compensated.

2. Double-acting hydrodynamic axial plain bearing (1) according to claim 1, characterized in that the pressure compensation device comprises a first and a second pressure compensation line (16, 17) which are arranged and designed such that one end of the respective pressure compensation line (16, 17) connects the first or second annular chamber (9, 12) formed depending on the position of the track disc (8) with the environment, and the respective other pressure compensation line (9, ) connects the remaining space (15) separated from the first or second annular chamber (9, 12) with the environment.

3. Double-acting hydrodynamic axial plain bearing (1) according to claim 1, characterized in that the pressure compensation device comprises a first and a second pressure compensation line (16, 17) which are arranged and designed such that one end of the pressure compensation lines (16, 17) opens into the first or second annular chamber (9, 12) formed depending on the position of the track disc (8), and the respective other ends of the pressure compensation lines (16, 17) are operatively connected to one another directly or via a pressure compensation chamber (18).

4. Double-acting hydrodynamic axial plain bearing (1) according to claim 1, characterized in that the pressure compensation device comprises a first and a second pressure compensation line (16, 17) which are so are arranged and designed such that the first end of the respective pressure equalization lines (16, 17) opens into the first or second annular chamber (9, 12) formed depending on the position of the track disc (8), and the respective other end of the Pressure equalization line (16,17) opens into the space (15) separated from the first or second annular chamber (9,12).

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