1. Field of the Invention
The invention relates to a radial plain bearing. The invention moreover relates to a method for installing a radial plain bearing with support of the tilting pads on the bearing connection surroundings.
2. Description of the Related Art
Radial plain bearings are known in various designs from the current state of the art. The following publications are referenced as being representative:
The radial plain bearing includes a bearing housing having a bearing bore aligned along a bearing axis and having a number of tilting pads for supporting a shaft, said pads being movable relative to the bearing housing and being arranged circumferentially around the bearing axis at a distance from the latter, whereby the individual tilting pad has an outer radial plain bearing surface that can be supported on a supporting surface of a pressure block provided in the bearing housing.
At least an indirect support of tilting pads is thereby provided on the bearing housing.
When being used in turbo-transmissions the characteristics of such mountings, in addition to the geometry of the shafts, determine thereby definitively the rotor-dynamic characteristics. Previous bearing concepts are characterized by a relatively complex design, expensive manufacture and/or space-intensive construction, particularly in the radial direction.
The present invention provides a radial plain bearing for the use of mountings shafts that rotate at high speed that can be operated at a higher speed and bearing pressure, with lower bearing clearance variation in stationary operation, less bearing deformation and improved vibration characteristics; so that it meets the requirements in applications with high circumferential speeds even more effectively, it is characterized by a rigid pad support and moreover allows a radial space saving design and in regard to manufacturing technology is simple and cost-effectively mountable.
A radial plain bearing including a bearing housing having a bearing bore aligned along a bearing axis and having a number of tilting pads for supporting a shaft, said pads being movable relative to the bearing housing and being arranged circumferentially around the bearing axis at a distance from the latter, whereby the individual tilting pad has an outer radial plain bearing surface that can be supported on a supporting surface of a pressure block provided in the bearing housing, is characterized according to the invention in that the individual pressure block is movably provided in a passage extending radially through the bearing housing and can move radially without being supported on the bearing housing, that said block is secured against rotation in the circumferential direction of the passage by way of an anti-rotation element and that at least part or all of the radial outer surface of the pressure block is situated on a common cylinder surface with the outer diameter of the bearing housing or with a bushing surrounding said housing.
Bushings are used in particular when for example the bearing housing is a cast component and is too soft for the application. The bushing surrounding the bearing housing is for example an eccentric bushing.
The radial plain bearing according to the invention facilitates a rigid support of the tilting pads due to direct force transmission into the bearing connection surrounding and is therefore also suitable for mounting of shafts that rotate at very high speeds. The radial plain bearing according to the invention is moreover constructively simple and easy to install.
The support of the bearing surface on the supporting surface can occur directly or via interposition of additional components. During operation of the radial plain bearing a lubricating film can be provided between bearing surface and supporting surface.
The individual pressure block features at least one guide region for guidance in the bearing housing; and in installation position at the radial inside end region features a support region for creation of the supporting surface, wherein the guide region is designed such that a clearance fit is provided between the outside circumference and the passage; and the guide region has an extension in radial direction that is dimensioned such that the supporting region is not in contact with the inside circumference of the bearing housing.
In one advantageous embodiment the individual pressure block and/or the tilting pad are manufactured from a material having an elasticity module greater than 200 GPa, in particular greater than 250 GPa. Technical ceramics are the preferred choice of material. These facilitate high radial rigidity and at the same time good thermal conductivity. An additional advantage is found in the clearly lower coefficients of thermal expansion which clearly reduce the danger of bearing clearance reductions due to overheating in intermittent operation.
For ease of manufacture the individual passages in the bearing housing are created round or oval in their cross sections.
In one advantageous further development a lubricant and/or coolant system is provided which comprises at least one annular groove extending over at least one section in circumferential direction around the bearing housing and which—when viewed in the direction parallel to the bearing axis—is arranged in the region of the bearing center or eccentrically offset to same, whereby the annular groove is connected via at least one radial bore in the housing with a nip that is formed between the individual tilting pads and the inside circumference of the bearing housing. The design with the central annular groove allows the integration of the pressure blocks in their radial outer end region for this function.
The radial movability of the pressure block inside the passage and securing in circumferential direction occurs by means of an anti-rotation element which includes a locking element, in particular a threaded pin that is passed through the wall of the bearing housing, and which is effective with clearance at the guide region of the pressure block. As a result of its design it can already be utilized as an assembly aid during the assembly of the bearing.
In the high performance range at least 3 to 7 tilting pads, advantageously 4 to 5 tilting pads, are preferably used for supporting radial plain bearings.
A process for installation of a radial plain bearing is characterized by the following process steps:
The method allows great size accuracy of the bearing since the adjustment can be made directly via the position of the pressure blocks during assembly.
The pressure block can especially advantageously be braced in respect to the passage by means of a fastening element of a positively locking anti-rotation element that is any case provided in the installation condition of the bearing.
In the case of a central annular groove on the outside surface of the bearing housing, the annular groove for a lubrication and cooling system can be integrated in a further embodiment into the bearing housing and/or the pressure block when machining the outside circumference.
The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:
a is a simplified schematic illustration in an axial section of the radial plain bearing of
b illustrates the radial plain bearing of
a is a perspective view of a section of the radial bearing of
b is a section view through A-A of
a is a section illustration of the bearing housing of the radial plain bearing of
b is a side view of a pressure block of the radial plain bearing of
c illustrates an initial assembly of the bearing housing, tilting pad, and pressure block of the radial plain bearing of
d illustrates the final manufactured configuration of the bearing housing, tilting pad, and pressure block of the radial plain bearing of
Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate embodiments of the invention, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.
a and 2b show in schematized and strongly simplified illustration a section of a radial plain bearing 1, as illustrated in
Bearing housing 2 can be formed by a cylindrical sleeve. It consists preferably of at least two half shells 4a and 4b. A design that is not illustrated here, consisting of several partial shells that are arranged adjacent to one another in circumferential direction around bearing axis LA and which can be connected with one another through frictional and/or positive locking, is also conceivable. Radial plain bearing 1 moreover includes a number of tilting pads 5 being arranged movable relative to bearing housing 2 and being arranged in circumferential direction adjacent to one another around longitudinal axis LA at a distance from same. Tilting pads 5 serve to support a shaft around its axis—said shaft not being illustrated in
The guidance of pressure block 9 in bearing housing 2 occurs in passages 12 arranged radially in same and extending through the wall thickness; in other words, from inside circumference 22 to outside circumference 10. The movability of pressure block 9 in the radial direction is realized via a clearance between outside circumference 10 of pressure block 9 that is guided in passage 12, and inside circumference 22 of passage 12. A simple fit is sufficient herein.
To realize the support function and formation of supporting surface 8, pressure block 9 is characterized by at least two regions in regard to its design, a first supporting region 13 and a second guide region 14. The function of supporting region 13 exists in the formation of supporting surface 8. The function of guide region 14 consists in the guide function in bearing housing 2. Supporting region 13 and guide region 14 are designed accordingly. Supporting region 13 is—in regard to its size relative to a center axis of pressure block 9 which coincides with the center axis of passage 12 in installation position—larger than guide region 14. In the illustrated case supporting surface 6 that is located on tilting pad 5 is convex. Consequently, supporting surface 8 on pressure block 9—viewed in circumferential direction around shaft 11—is designed concave.
The specific geometric design of pressure block 9 can vary. Passage 12 is preferably circular or oval. The design of guide region 14 of pressure block 9 is complementary thereto, having a circular or oval cross section.
Pressure block 9 is preferably symmetrical, relative to a plane that is characterized by a center axis of pressure block 9 and a vertical line relative to same in installation position in the axial direction. Supporting region 13 extents in installation position at the radial inside end region of pressure block 9 on both sides beyond guide region 14 and is thus—viewed in circumferential direction around bearing axis LA—designed with a protrusion on both sides. This is also the case for the extension in the axial direction.
By way of an illustration according to
a illustrates a section of a view in an axial sectional plane. One can see bearing housing 2 extending in its axial direction, pressure block 9 after assembly and tilting pad 5 that—viewed in radial direction—is supported in axial and circumferential direction over a contact region on supporting surface 8 of pressure block 9. Originating from lateral surfaces 17 and respectively 18 of bearing housing 2, anti-rotation element 15 is positioned perpendicular to same. In the simplest case a threaded pin 16, originating from one lateral surface 17 in bearing housing 2 is guided in threaded bore 20 extending in direction toward passage 12 and ending in same. Threaded bore 20 progresses preferably orthogonally to passage 12.
b shows the arrangement and design of anti-rotation element 15 in a section A-A of
In a perspective view
Annular groove 19 is arranged centrally relative to the axial extension of radial plain bearing 1 Annular groove 19 is thereby worked into the material of bearing housing 2 and arranged outside 23 of pressure block 9 that is flush with outside circumference 10 of bearing housing 2 and facing away from shaft 11. Annular groove 19 is connected via at least one connection bore with radial direction component in bearing housing 2 with a space between the individual tilting pads 5.
This connection channel guides the lubricant into the region between tilting pad 5 and inside circumference 22 of bearing housing 2 and shaft surface 11.
The lubricant and coolant being used for radial plain bearing 1 according to the invention is normally oil. However, the use of water or another mixture is also conceivable. The function of annular groove 19 consists in the oil supply of each nip formed by a respective tilting pad 5 and shaft 11 that is to be supported. The illustrated embodiment of annular groove 19 represents an especially advantageous design. Embodiments with grooves symmetric to the bearing center on the outside diameter of bearing housing 2 and thus outside of pressure block 9 are also conceivable.
Supply strips 26 for lubricant and coolant are moreover provided which are conductively connected with annular groove 19 via the connection channels, in particular oil channels. Supply strips 26 and the oil channels are preferably tilted relative to a radial beam. The longitudinal axis of the oil channels can for example be arranged in an axis-vertical section through the bearing axis according to secant lines on the circle that is limited by the shell surface of shaft 11. The supply to tilting pad 5 occurs on the side of run-in edge 27. This is understood to be the edge of tilting pad 5 that—in rotational direction of shaft 11—is first swept over by shaft 11. Run-out edge 28 is the edge of the same tilting pad 5 that is positioned after run-in edge 27 in rotational direction of shaft 11. An especially effective injection of lubricant and coolant into the nip is ensured due to the aforementioned tilting. According to an especially advantageous design each of the supply strips 26 includes threaded bores for screwing in of metering screws.
a-d clarify in schematically simplified illustration the individual assembly steps in the assembly of radial plain bearing 1. According to
In order to further increase rigidity of radial plain bearing 1, the material of pressure block 9 should contain an elasticity modulus that is greater than that of steel. Values greater than 200 GPa are hereby to be strived for. Technical ceramics are considered as choice of material. Technical ceramic offers the advantage of excellent thermal conductivity. Moreover, low coefficients of thermal expansion compared to hitherto used pad materials. This reduces the risk of inadmissible reduction of the bearing clearance due to intermittent thermal deformations and the thereby created high bearing temperatures that could lead to shutting down of the system.
For utilization of the bearing in bearing connection surroundings whose material properties differ from those of the bearing housing and whereby there is a danger that their functionality is impaired during operation due to wear and tear, bearing housing 2 is being enclosed by a bushing on the outside circumference. The outside circumference of the bushing then forms the contact surface with the bearing connection surrounding and the pressure parts support themselves on the inside circumference of the bushing.
While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.
1 radial plain bearing
2 bearing housing
3 bearing bore
4
a,
4
b bearing shell
5 tilting pad
6 supporting surface
7 bearing surface
8 support surface
9 pressure block
10 outside circumference
11 shaft
12 passage
13 support region
14 guide region
15 anti-rotation element
16 threaded pin
17 lateral surface
18 lateral surface
19 annular groove
20 threaded bore
21 lateral plate
22 inside circumference
23 radial outside
24 pad locking pin
25 lubricant and coolant supply system
26 supply strips
27 run-in edge
28 run-out edge
29 bushing
LA bearing axis
Number | Date | Country | Kind |
---|---|---|---|
10 2013 209 193.1 | May 2013 | DE | national |
10 2014 209 062.8 | May 2014 | DE | national |
This is a continuation of PCT application No. PCT/EP2014/059827, entitled “RADIAL PLAIN BEARING”, filed May 14, 2014, which is incorporated herein by reference.
Number | Date | Country | |
---|---|---|---|
Parent | PCT/EP2014/059827 | May 2014 | US |
Child | 14943394 | US |