Double-acting hydrodynamic axial plain bearing

Abstract

Double-acting hydrodynamic axial plain bearing (1), comprising a bearing housing (2) with a first bearing body (3) arranged in the bearing housing (2) and having a first axial bearing surface (4), and with a second bearing body (5) arranged in the bearing housing (2) and having 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, depending on the axial position of the shaft (7), can be supported on the first or second axial bearing surface (4, 6), and depending on whether the track disc (8) is supported on the first or second axial bearing surface (4, 6), a first or second annular chamber (9, 12) is formed.

Description

[0001] The invention relates to a double-acting hydrodynamic axial plain bearing according to the preamble of independent patent claim 1.

[0002] Double-acting hydrodynamic thrust bearings are widely used for supporting axially loaded shafts. Such bearings are described, for example, in DE 100 05 309 A1.

[0003] A generic double-acting hydrodynamic thrust plain bearing comprises a bearing housing and a shaft with a thrust washer. Axial bearing surfaces are formed at the respective axial ends of the bearing housing, against which the thrust washer of the shaft to be supported can rest. Although the thrust washer is referred to below as contacting the bearing surfaces, in a hydrodynamic bearing there is never direct contact between the thrust washer and the corresponding bearing surface; a lubricating film is always present between the thrust washer and the bearing housing. Bearing oil is typically used as the lubricant.

[0004] 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.

[0005] Bearing oil and / or air can collect in the annular chamber. In 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 provided is not sufficient to always completely fill the chamber 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 or failure of the axial bearing.

[0006] In addition to axial plain bearings with one track disc, axial plain bearings with two track discs are also known, which also result in the instabilities described above.

[0007] 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.

[0008] The problem is solved by the features of independent patent claim 1.

[0009] Further embodiments of the invention, which can be used individually or in combination with one another, are the subject of the subclaims.

[0010] 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, - 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 - a second annular chamber is formed which is closed off from the rest of the bearing housing and which is bounded 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 by the fact that a pressure compensation device is provided, via 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.

[0011] As a result of the pressure equalization, the axial vibrations caused by the alternating axial forces are completely eliminated, or at least effectively reduced, so that there is no damage or even failure of the bearing.

[0012] 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 formed 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. The pressure equalization is not established directly between the two annular chambers, but rather between the individual spaces (chambers) and the environment. This embodiment can be manufactured particularly easily and without great structural effort and can also be retrofitted if necessary.

[0013] A further embodiment of the invention provides that the pressure compensation device comprises a first and a second pressure compensation line, which are arranged and designed such that one end of the pressure compensation lines opens into the first or second annular chamber formed depending on the position of the track disc, and the respective other ends of the pressure compensation lines are in operative connection with one another directly or via a pressure compensation chamber.

[0014] By means of the lines communicating directly or internally with each other, pressure equalization can be easily achieved between the respective annular chamber and the space separated from the annular chamber. This solution can also be implemented retrospectively if necessary.

[0015] 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 respective other end of the pressure equalization line opens into the space separated from the annular chamber.

[0016] Such a solution has lower storage losses than the previous solution.

[0017] Further advantages of the invention are explained below using exemplary embodiments.

[0018] It shows: - Fig. 1: A first embodiment of a double-acting hydrodynamic axial plain bearing according to the invention, with pressure compensation with respect to the environment. - Fig. 2: A second embodiment of a device according to the invention with pressure equalization by means of a pressure equalization chamber. - 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. - Fig. 4: A third embodiment of a double-acting hydrodynamic axial plain bearing according to the invention, with two track discs.

[0019] The figures show only schematic and not necessarily to scale representations of the double-acting hydrodynamic axial plain bearing according to the invention. 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 represents an exemplary embodiment of such a bearing; there are other, differing exemplary embodiments available on the market, to which the invention can be applied and which are encompassed by the scope of protection of the invention.

[0020] Fig. Figure 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 constructed in several parts for easier assembly. Bearing bodies 3, 5, each with an axial contact surface 4, 7, are formed on the axial walls 10, 13 of the bearing housing 2, against 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: - 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 - 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.

[0021] Fig. 1 shows the position in which the track disc is in the first end position and the first annular chamber 9 is formed.

[0022] 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 compensation device comprises a first and a second pressure compensation line 16, 17, which are arranged and designed such that a first end of the respective pressure compensation line 16, 17 connects the first or second annular chamber 9, 12, which is 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 separated from the first or second annular chamber 9.The second annular chamber 9, 12 connects the space 15 separated by the second annular chamber 9, 12 with the environment. This enables extensive pressure equalization between the spaces 9 and 12, respectively, and 15, which are (largely) separated by the track disc, thus avoiding, or at least significantly reducing, the instability of the shaft-bearing system. The pressure equalization lines 16, 17 can be formed by simple drilling into the bearing housing 2.

[0023] Fig. 2 shows a second embodiment of a double-acting hydrodynamic axial plain bearing 1 according to the invention. The basic structure corresponds to that shown in Fig. 1, to whose 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, which is 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 exemplary embodiment, via a pressure equalization chamber 18. Both embodiments, with or without a compensation chamber, enable effective pressure equalization between the first or second annular chamber 9 or 12 and the space 15 separated from the first or second annular chamber 9 or 12, and thereby in turn effectively prevent axial vibrations of the shaft 13. The pressure equalization chamber 18 is optional, whereby the pressure equalization chamber can dampen pressure surges of the multi-phase fluid in the pressure equalization lines 16, 17.

[0024] Fig. 3 shows a third embodiment of a double-acting hydrodynamic axial plain bearing 1 according to the invention. The 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 embodiment according to Fig. 2, the pressure equalization lines 16, 17 are not connected to each other directly or via a pressure equalization chamber. Rather, the pressure equalization lines 16, 17 are arranged 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 independently of each other into the space 15 separated from the first or second annular chamber 9, 12.

[0025] The embodiment according to Fig. 3 thus 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.

[0026] Fig.Figure 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 washers 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 washers 11 and 14, and the outer surfaces 10 and 13 of an intermediate part of the bearing housing 2. In 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.By definition, the pressure equalization lines described in this invention are 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 bearing operation.

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) and having a first axial bearing surface (4), and with a second bearing body (5) arranged in the bearing housing (2) and having 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 (8) 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 the side (14) of the track disc (8) facing the second axial bearing surface (6), wherein 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 bythat the pressure equalization device comprises a first and a second pressure equalization line (16, 17) which are arranged and designed such that one 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 (16, 17) 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 bythat 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 in operative connection with one another directly or via a pressure compensation chamber (18). [4] Double-acting hydrodynamic axial plain bearing (1) according to claim 1, characterized bythat the pressure compensation device comprises a first and a second pressure compensation line (16, 17) which are arranged and designed such that the first end of the respective 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 end of the pressure compensation line (16, 17) opens into the space (15) separated from the first or second annular chamber (9, 12).

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