Radial compressor with axial bearing arrangement for a drive shaft of the radial compressor

Abstract

Axial bearing arrangement for a drive shaft of a radial compressor. The axial bearing arrangement comprises a first axial bearing plate (12) and a second axial bearing plate (13), each having a ring-shaped form, wherein the first axial bearing plate (12) has a first surface (12.1) which faces axially towards the second axial bearing plate (13), and a second surface (12.2) opposite the respective first surface (12.1), wherein the second axial bearing plate (13) has a first surface (13.1) which faces axially towards the first axial bearing plate (12), and a second surface (13.2) opposite the respective first surface (13.1); a spacer ring (14) clamped between the first surfaces (12.1, 13.1) of the first and second axial bearing plates (12, 13), wherein the spacer ring (14) defines an axial distance between the first and second axial bearing plates (12, 13); and a bearing bushing (15) which is clamped on the second surface (13.2) the second axial bearing plate (13) abuts and is secured to a compressor block (16). The axial bearing arrangement includes an elastic element (22) that preloads the first and second axial bearing plates (12, 13) and the spacer ring (14) with a predetermined force against a stop surface (17) of the bearing bushing (15).

Description

[0001] The present invention relates to a radial compressor with an axial bearing arrangement for a drive shaft of the radial compressor.

[0002] As is known, an axial bearing arrangement for a drive shaft of a radial compressor can include the following: - a first axial bearing plate and a second axial bearing plate, also referred to as first and second pressure plates, which are parallel to each other and each have a ring-shaped form, wherein the first axial bearing plate has a first surface facing axially to the second axial bearing plate and a second surface opposite the first surface of the first axial bearing plate, wherein the second axial bearing plate has a first surface facing axially to the first axial bearing plate and a second surface opposite the first surface of the second axial bearing plate, - a spacer ring, clamped between the first surfaces of the first and second axial bearing plates at radial outer portions of the first and second axial bearing plates, wherein the spacer ring defines an axial distance between the first and second axial bearing plates, and - a bearing bushing, secured to a compressor block and abutting the second surface of the second axial bearing plate, in order to fasten the first and second axial bearing plates and the spacer ring against a contact surface provided on the compressor block.

[0003] During operation, a radial flange portion of the drive shaft extends into a space formed between an inner surface of the spacer ring and radial inner portions of the first surfaces of the first and second axial bearing plates, and interacts with the first surfaces of the first and second axial bearing plates to limit axial movement of the drive shaft.

[0004] In such a compressor, especially when operated at very high speeds, high temperature conditions can occur which can cause thermal stresses and deformations in compressor components, for example, when components made of materials with different coefficients of thermal expansion are attached to each other and / or when there is a large temperature gradient in solid parts.

[0005] Particularly critical are the axial bearing arrangements, where the radial flange portion of the drive shaft rotates between the first and second axial bearing plates, with very small clearances between rotating and stationary parts.

[0006] Mechanical stresses in the axial bearing assembly, caused by tolerances during compressor assembly or by the aforementioned uneven thermal expansion, can impair the parallel alignment of the first and second axial bearing plates. This can lead to seizing of the axial bearing assembly and a reduced service life of the radial compressor.

[0007] DE 698 30 961 T2 describes a turbomachine with a flexible fluid-film thrust bearing. The turbomachine comprises a turbine wheel and a compressor wheel at opposite ends of a common shaft or tie rod. A thrust and radial bearing rotor is arranged around the tie rod between the turbine wheel and the compressor wheel. A ball bearing cartridge in a central bearing housing rotatably supports the bearing rotor. The compressor end of the bearing rotor has a radially extending thrust disk that engages in a recess in the compressor end of the central bearing housing. A bearing thrust plate is arranged on the opposite side of the bearing rotor thrust disk, with a stack consisting of a fluid film element and a spring film element arranged on each of the axial sides of the bearing rotor thrust disk.

[0008] DE 11 2012 002 901 T5 describes an air supply device for a fuel cell. The air supply device comprises a shaft with two ends and a compressor wheel arranged in a compressor housing and attached to one end of the shaft. The shaft is driven by an electric motor. The shaft has bearing sections formed from two separate components, with a rotor and the magnetic section of the electric motor arranged between the bearing sections. The bearing sections and the magnetic section are centered relative to each other by a centering arrangement acting on an outer edge, with the bearing sections and the magnetic section each bearing axially against each other. One of the bearing sections has a shoulder held by two thrust bearing halves. The thrust bearing half located closer to the shaft's bearing bushing is tensioned by spring assemblies.

[0009] DE 695 32 538 T2 describes an elastic fluid film element for a hydrodynamic fluid film thrust bearing. An axle journal bearing carrier is arranged in the central bearing housing and rotatably holds an extended turbine end of a bearing shaft. A compressor end of the bearing shaft has a radially extending rotor or disk that extends into a recess at the compressor end of the central bearing housing. A bearing slide plate is arranged on the opposite side of the bearing shaft disk. A radially outward end of the bearing slide plate forms a thin, radially extending, flat spring. A stack consisting of a fluid film element 40 and a spring film element 42 is arranged on both axial surfaces of the bearing shaft disk 24.

[0010] It is an object of the present invention to provide a radial compressor with an improved axial bearing arrangement that overcomes the disadvantages occurring in conventional axial bearing arrangements.

[0011] Another object of the present invention is to provide a radial compressor with an axial bearing arrangement that is reliable and, in particular, is not subject to the deformations mentioned above.

[0012] These tasks are solved by a radial compressor with the features according to claim 1.

[0013] According to the invention, an axial bearing arrangement of the radial compressor includes, among other things: - a first axial bearing plate having a ring-shaped form, wherein the first axial bearing plate has a first surface and a second surface opposite the corresponding first surface, - a spacer ring, abutting the first surface of the first axial bearing plate on a radial outer portion of the first axial bearing plate, - a bearing bushing, attached to a compressor block, characterized in that the axial bearing arrangement further includes an elastic element that is arranged between the second surface of the first axial bearing plate and the compressor block, and that the elastic element axially preloads the first axial bearing plate and the spacer ring with a predetermined force against a stop surface of the bearing bushing.

[0014] Such a design of the axial bearing arrangement, and in particular the presence of the elastic element, allows the first bearing plate and the spacer ring to slide axially relative to the compressor block when thermal expansion occurs, thus preventing deformation of the parts, which could lead to seizing of the parts and a shortened service life of the radial compressor.

[0015] The axial bearing arrangement may also include one or more of the following features, either individually or in combination.

[0016] According to one embodiment of the invention, the stop surface of the bearing bushing extends transversely, and for example essentially perpendicularly, to a longitudinal axis of the bearing bushing.

[0017] According to one embodiment of the invention, the stop surface is located at an axial end of the bearing bushing.

[0018] According to one embodiment of the invention, the elastic element is a ring-shaped spring disc, preferably of the type of a disc spring.

[0019] According to the invention, the predetermined force exerted by the elastic element on the first axial bearing plate is in the range of 1000 to 2000 N, preferably about 1500 N.

[0020] According to the invention, the elastic element is in contact with a radial outer portion of the second surface of the first axial bearing plate, more precisely at a radius close to the mean radius of the spacer ring.

[0021] According to one embodiment of the invention, the elastic element is arranged in a ring-shaped recess formed in an axial surface of the compressor block.

[0022] According to one embodiment of the invention, an axial clearance is provided between the second surface of the first axial bearing plate and the axial surface of the compressor block.

[0023] According to one embodiment of the invention, the axial clearance between the second surface of the first axial bearing plate and the axial surface of the compressor block is in the range of 20 µm.

[0024] The bearing bushing is designed to provide rotational support for the drive shaft.

[0025] According to the invention, the bearing bushing includes at least one radial bearing part, more precisely at least one radial gas bearing part (a gas radial bushing bearing).

[0026] The bearing bushing is designed to surround the drive shaft and to interact with the outer surface of the drive shaft.

[0027] According to one embodiment of the invention, the compressor block includes a ring-shaped shoulder against which the bearing bushing is mounted, and, for example, the stop surface of the bearing bushing.

[0028] According to one embodiment of the invention, the axial bearing arrangement further includes a locking element which is secured to the compressor block and axially secures the bearing bushing against the compressor block and, for example, against the ring-shaped shoulder of the compressor block.

[0029] According to one embodiment of the invention, the bearing bushing includes a crown-like shoulder against which the locking element is mounted.

[0030] According to one embodiment of the invention, the bearing bushing includes a portion clamped between the compressor block and the locking element.

[0031] According to one embodiment of the invention, the locking element is secured by screwing it onto the compressor block.

[0032] According to one embodiment of the invention, the elastic element and the bearing bushing are arranged coaxially.

[0033] The axial bearing arrangement further comprises a second axial bearing plate having a ring-shaped form, wherein the second axial bearing plate has a first surface facing axially to the first axial bearing plate and a second surface opposite the first surface of the second axial bearing plate, wherein the spacer ring is clamped between the first surfaces of the first and second axial bearing plates on radial outer portions of the first and second axial bearing plates, wherein the spacer ring defines an axial distance between the first and second axial bearing plates, the bearing bushing abuts against the second surface of the second axial bearing plate, and the elastic element axially preloads the first and second axial bearing plates and the spacer ring against the stop surface of the bearing bushing with the predetermined force.

[0034] According to one embodiment of the invention, the first and second axial bearing plates are parallel to each other.

[0035] According to one embodiment of the invention, the second axial bearing plate is designed as an integrated component of the bearing bushing.

[0036] According to one embodiment of the invention, the drive shaft includes a radial flange portion that extends into a space between radial inner portions of the first surfaces of the first and the second axial bearing plates.

[0037] According to one embodiment of the invention, the spacer ring surrounds the radial flange portion of the drive shaft.

[0038] According to one embodiment of the invention, an axial play is provided between the radial flange portion of the drive shaft and the first surfaces of the first and second axial bearing plates.

[0039] According to one embodiment of the invention, the axial play between the radial flange portion of the drive shaft and the first surfaces of the first and second axial bearing plates is in the range of 10 µm.

[0040] According to one embodiment of the invention, the radial compressor is designed to introduce a gas fluid between the radial flange portion of the drive shaft and the first surfaces of the first and second axial bearing plates in order to form an axial gas bearing for the drive shaft.

[0041] These and other advantages will become obvious when reading the following description in light of the attached drawing, which, as non-limiting examples, depict embodiments of a radial compressor incorporating an axial bearing arrangement according to the invention.

[0042] The following detailed description of two embodiments of the invention will be better understood if it is read in conjunction with the attached drawings, although it is understood that the invention is not limited to the specific embodiments disclosed. Fig. Figure 1 is a schematic longitudinal sectional view of a radial compressor according to the invention, which has an axial bearing arrangement according to a first embodiment. Fig. Figure 2 is a longitudinal section view of the radial compressor from Fig. 1. Fig. Figure 3 is an enlarged view of a detail of Fig. 2. Fig. 4 is an enlarged view of a detail of Fig. 3. Fig. Figure 5 is a perspective view of an elastic element of the axial bearing arrangement of Fig. 1. Fig. Figure 6 is a schematic longitudinal sectional view of a radial compressor having an axial bearing arrangement according to a second embodiment. Fig. Figure 1 represents a radial compressor 2, which can, for example, be a two-stage radial compressor. The radial compressor 2 includes a drive shaft 3 that extends along a longitudinal axis A.

[0043] According to the embodiment shown in the figures, the drive shaft 3 includes an intermediate bearing part 4, an impeller part 5 arranged at a first axial end portion of the intermediate bearing part 4, and a drive part 6 arranged at a second axial end portion of the intermediate bearing part 4. In particular, the intermediate bearing part 4 includes a cylindrical bearing portion 7 and a radial flange portion 8, which extends radially outwards from the cylindrical bearing portion 7. The radial flange portion 8 has the shape of a flat disk and includes a first axial end surface 8.1 and a second axial end surface 8.2 opposite the first axial end surface 8.1.

[0044] The drive shaft 3 can, for example, be made of high-strength steel, ceramic materials or combinations thereof.

[0045] The radial compressor 2 further includes at least one impeller 9, connected to the impeller section 5 of the drive shaft 3 and designed for compressing a coolant. The radial compressor 2 can, for example, include two impellers 9 arranged in a series configuration.

[0046] The radial compressor 2 also includes an electric motor 11, which is designed for the rotary drive of the drive shaft 3 around the longitudinal axis A. The electric motor 11 is advantageously arranged in a low-pressure chamber and comprises a stator 11.1 and a rotor 11.2. According to one embodiment of the invention, the rotor 11.2 is connected to the drive part 6 of the drive shaft 3. For this purpose, the drive part 6 can include an axial bore within which the rotor 11.2 is arranged. The rotor 11.2 can, for example, be firmly fitted in the axial bore, such as by pressing or shrinking.

[0047] The radial compressor 2 further includes an axial bearing arrangement, also referred to as a thrust bearing arrangement, located in the low-pressure chamber and designed to limit axial movement of the drive shaft 3 during operation. The axial bearing arrangement can be a fluid axial bearing arrangement or, for example, a gas axial bearing arrangement.

[0048] According to the embodiment shown in the figures, the axial bearing arrangement comprises a first axial bearing plate 12 and a second axial bearing plate 13, each having a ring-like shape and arranged in parallel. The first axial bearing plate 12 has a first surface 12.1 facing axially to the second axial bearing plate 13, and a second surface 12.2 opposite the first surface 12.1, whereas the second axial bearing plate 13 has a first surface 13.1 facing axially to the first axial bearing plate 12, and a second surface 13.2 opposite the first surface 13.1.

[0049] The radial inner portions of the first surfaces 12.1, 13.1 of the first and second axial bearing plates 12, 13 define a space in which the radial flange portion 8 of the drive shaft 3 extends. In particular, the first surfaces 12.1, 13.1 of the first and second axial bearing plates 12, 13 are each designed to interact with the first and second axial end faces 8.1, 8.2 of the radial flange portion 8.

[0050] According to one embodiment of the invention, an axial clearance is provided between the radial flange portion 8 of the drive shaft 3 and the first surfaces 12.1, 13.1 of the first and second axial bearing plates 12, 13. Such an axial clearance is advantageously in the range of 10 µm.

[0051] The axial bearing arrangement further includes a spacer ring 14, which surrounds the radial flange portion 8 of the drive shaft 3 and is clamped between the first surfaces 12.1, 13.1 of the first and second axial bearing plates 12, 13 at radial outer portions of the first and second axial bearing plates 12, 13. The spacer ring 14 defines an axial distance between the first and second axial bearing plates 12, 13, the axial distance being slightly greater than the width of the radial flange portion 8.

[0052] The axial bearing arrangement also includes a bearing bushing 15 that surrounds the drive shaft and is secured to a compressor block 16 of the radial compressor 2. Advantageously, the bearing bushing 15 extends along the intermediate bearing section 4 of the drive shaft.

[0053] The bearing bushing 15 includes a stop surface 17 that abuts the second surface 13.2 of the second axial bearing plate 13. The stop surface 17 is located at an axial end of the bearing bushing 15 and extends transversely, and advantageously perpendicularly, to the longitudinal axis A of the drive shaft 3.

[0054] According to the embodiment shown in the figures, the compressor block 16 includes a ring-shaped shoulder 18 against which the bearing bushing 15 and more precisely the stop surface 17 of the bearing bushing 15 is mounted.

[0055] In addition, the axial bearing arrangement includes a locking element 19, secured, for example, by screwing it to the compressor block 16, which axially secures the bearing bushing 15 against the compressor block 16, more precisely against the ring-shaped shoulder 18 of the compressor block 16.

[0056] According to the embodiment shown in the figures, the bearing bushing 15 includes a ring-shaped shoulder 21 against which the locking element 19 is mounted, and the bearing bushing 15 is partially clamped between the compressor block 16 and the locking element 19.

[0057] The axial bearing arrangement further includes an elastic element 22, arranged between the second surface 12.2 of the first axial bearing plate 12 and the compressor block 16. The elastic element 22 axially preloads the first and second axial bearing plates 12, 13 and the spacer ring 14 with a predetermined force, for example in the range of 1000 to 2000 N, and preferably about 1500 N, against the stop surface 17 of the bearing bushing 15. Advantageously, the elastic element 22 is a ring-shaped spring washer, preferably of the type of a disc spring, which is arranged coaxially to the bearing bushing 15 and the drive shaft 3.

[0058] Advantageously, the elastic element 22 is arranged in a ring-shaped recess 23 formed in an axial surface of the compressor block 16 and is in contact with a radial outer portion of the second surface 12.2 of the first axial bearing plate 12, at a radius close to the mean radius of the spacer ring 14.

[0059] The elastic element allows, especially when thermal expansion occurs in the radial compressor, axial sliding of the first and second axial bearing plates 12, 13 and the spacer ring 14 relative to the compressor block 16, thus preventing deformation of the parts, which could lead to a shortened service life of the radial compressor.

[0060] According to one embodiment of the invention, an axial clearance C is provided between the second surface 12.2 of the first axial bearing plate 12 and the axial surface of the compressor block 16, which is provided with the ring-shaped recess 23. The axial clearance C is advantageously in the range of 20 µm.

[0061] According to the embodiment shown in the figures, the bearing bushing 15 is designed for the rotational support of the drive shaft 3. In particular, the bearing bushing 15 includes a radial bearing part 24 with an inner surface designed to interact with the outer surface of the cylindrical bearing portion 7 of the drive shaft 3. Therefore, the bearing bushing 15 forms a radial bushing bearing and, for example, a gas radial bushing bearing.

[0062] According to one embodiment of the invention, the radial compressor 2 is designed such that a gas fluid is introduced between the radial flange portion 8 of the drive shaft 3 and the first surfaces 12.1, 13.1 of the first and second axial bearing plates 12, 13 to form an axial gas bearing for the drive shaft 3. The radial compressor 2 is also designed such that a gas fluid is introduced between the cylindrical bearing portion 7 of the drive shaft 3 and the inner surface of the radial bearing part 24 to form a radial gas bearing for the drive shaft 3.

[0063] According to another in Fig. In the embodiment of the invention shown in Figure 6, the second axial bearing plate 13 can be designed as an integrated component of the bearing bushing 15.

Claims

[1] Radial compressor (2) with a drive shaft (3) extending along a longitudinal axis (A), at least one impeller (9) connected to an impeller part (5) of the drive shaft (3) and designed to compress a coolant, and an axial bearing arrangement for the drive shaft (3) of the radial compressor (2), wherein the axial bearing arrangement comprises: - a first axial bearing plate (12) having a ring-shaped form, wherein the first axial bearing plate (12) has a first surface (12.1) and a second surface (12.2) opposite the first surface (12.1) of the first axial bearing plate (12), - a spacer ring (14) abutting the first surface (12.1) of the first axial bearing plate (12) on a radial outer portion of the first axial bearing plate (12), - a bearing bushing (15), attached to a compressor block (16), wherein the bearing bushing (15) is designed for the rotational support of the drive shaft (3) and includes a radial bearing part (24) with an inner surface designed for interaction with an outer surface of a cylindrical bearing part (7) of the drive shaft (3), wherein the axial bearing arrangement further includes an elastic element (22) arranged between the second surface (12.2) of the first axial bearing plate (12) and the compressor block (16), and wherein the elastic element (22) preloads the first axial bearing plate (12) and the spacer ring (14) with a predetermined force against a stop surface (17) of the bearing bushing (15), wherein the axial bearing arrangement further comprises a second axial bearing plate (13) having a ring-shaped form, wherein the second axial bearing plate (13) has a first surface (13.1) facing axially towards the first axial bearing plate (12), and a second surface (13.2) opposite the first surface (13.1) of the second axial bearing plate (13), wherein the spacer ring (14) is clamped between the first surfaces (12.1, 13.1) of the first and the second axial bearing plates (12, 13) at radial outer portions of the first and the second axial bearing plates (12, 13), wherein the spacer ring (14) defines an axial distance between the first and the second axial bearing plates (12, 13), the bearing bushing (15) abuts against the second surface (13.2) of the second axial bearing plate (13), and the elastic element (22) flexes the first and the second axial bearing plates (12, 13) and preload the spacer ring (14) against the stop surface (17) of the bearing bushing (15) with the predetermined force, characterized by , that the radial compressor (2) includes an electric motor (11) designed to rotate the drive shaft (3) around the longitudinal axis (A), that the bearing bushing (15) forms a gas radial bushing bearing for the drive shaft (3), that the elastic element (22) is in contact with the radial outer portion of the second surface (12.2) of the first axial bearing plate (12) at a radius close to a mean radius of the spacer ring (14), and that the predetermined force exerted by the elastic element (22) on the first axial bearing plate (12) is in the range of 1000 to 2000 N. [2] Radial compressor (2) according to claim 1, wherein the elastic element (22) is a ring-shaped spring disc. [3] Radial compressor (2) according to one of the preceding claims, wherein the elastic element (22) is arranged in a ring-shaped recess (23) formed in an axial surface of the compressor block (16). [4] Radial compressor (2) according to claim 3, wherein an axial clearance (C) is provided between the second surface (12.2) of the first axial bearing plate (12) and the axial surface of the compressor block (16). [5] Radial compressor (2) according to one of the preceding claims, further comprising a locking element (19) secured to the compressor block (16) which axially secures the bearing bushing (15) against the compressor block (16). [6] Radial compressor (2) according to claim 5, wherein the compressor block (16) includes a ring-shaped shoulder (18) against which the stop surface (17) of the bearing bushing (15) is supported, wherein the locking element (19) axially secures the bearing bushing (15) against the ring-shaped shoulder (18) of the compressor block (16), wherein the bearing bushing (15) has a ring-shaped shoulder (21) against which the locking element (19) is supported, wherein the bearing bushing (15) comprises a portion clamped between the compressor block (16) and the locking element (19), wherein the locking element (19) is secured by screwing it to the compressor block (16). [7] Radial compressor (2) according to one of the preceding claims, wherein the stop surface (17) is located at an axial end of the bearing bushing (15). [8] Radial compressor (2) according to claim 1, wherein the second axial bearing plate (13) is formed as an integrated component of the bearing bushing (15). [9] Radial compressor (2) according to one of the preceding claims, wherein the drive shaft (3) includes a radial flange portion (8) which extends into a space between radial inner portions of the first surfaces (12.1, 13.1) of the first and the second axial bearing plate (12, 13). [10] Radial compressor (2) according to claim 9, wherein an axial clearance is provided between the radial flange portion (8) of the drive shaft (3) and the first surfaces (12.1, 13.1) of the first and second axial bearing plates (12, 13). [11] Radial compressor (2) according to claim 9 or 10, wherein the radial compressor (2) is designed such that a gas fluid is introduced between the radial flange portion (8) of the drive shaft (3) and the first surfaces (12.1, 13.1) of the first and second axial bearing plates (12, 13) to form an axial gas bearing for the drive shaft (3).

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