WO2022097030A1

WO2022097030A1 - Compressor device and device equipped with a bearing damper

Info

Publication number: WO2022097030A1
Application number: PCT/IB2021/060157
Authority: WO
Inventors: Stijn PITTOIS; Björn VERRELST; Nils VERCAUTEREN
Original assignee: Atlas Copco Airpower, Naamloze Vennootschap
Priority date: 2020-11-09
Filing date: 2021-11-03
Publication date: 2022-05-12
Also published as: BE1028779B1; BE1028779A1

Abstract

Compressor device with a housing (2) and provided with at least one compressor element (3) and a drive (4) for the compressor element (3), characterised in that ail bearings (11) of at Ieast one shaft (10) in the compressor device (1), configured to bear static-axial load with their static bearing ring (12), are arranged axially slidable in the housing (2) relative to the housing (2), wherein all of said bearings (11) are provided with a bearing damper (15) comprising at Ieast one damper (16), wherein the static bearing ring (12) is able to act upon this damper (16) when the static bearing ring (12) axially slides in the housing (2), wherein said bearings (11) and bearing dampers (15) are arranged such that at Ieast two surfaces (19, 20, 22, 23) slide over each other when the static bearing ring (12) axially slides relative to the housing (2).

Description

COMPRESSOR DEVICE AND DEVICE EQUIPPED WITH A BEARING DAMPER

The present invention relates to a compressor device equipped with a bearing damper.

In particular, the invention relates to a compressor device with a bearing damper that can be used with a bearing, with which a shaft of a drive of, for example, a compressor element is arranged in the housing of the drive.

It is known that compressor elements are driven at high speeds by the drive.

This makes the device susceptible to vibration-related problems which occur at such high speeds, since shaft resonances will be situated in the operating range. Vibrations or oscillations generated in the compressor element and/or the drive can propagate through the gear. The excitations or resonances that cause these vibrations mainly orig- inate from an imbalance of the drive and from pulsations of the process forces of the compressor element.

Several dynamic problems arise, both in the drive and in the compressor element.

One of these problems concerns an axial excitation or resonance of the shaft of the drive and/or the compressor element, whereby the shaft will vibrate in the axial direc- tion.

Such axial displacements of the shafts will mainly occur in the motor, but they can also cause problems in the compressor element, since very strict tolerances apply in the compressor element, which allow little or no axial displacement of the shaft.

To date, there is no real good solution for this problem.

Typically, heavier bearings will be used, in order to have sufficient stiffness and/or to replace the bearings at regular time intervals.

However, the use of a flexible coupling between the drive and the compressor element, which provides a dynamic decoupling between dynamics of the drive and the compres- sor element and dampens the excitations or resonances, has some disadvantages: the flexible coupling represents an additional cost; the size of the gear transmission is increased and there is a need for additional bearings; and the flexible coupling is susceptible to wear because the flexible material degrades over time, so that the flexible transmission must be replaced regularly.

That is why in most cases a so-called direct coupling is preferred, in which the flexible coupling is omitted, and one has to resort to heavier bearings and/or regular bearing replacement after all.

In the patent application BE 2019/5934, use is made of a connecting element which is mounted between the bearing and the housing, which comprises several rings between which damping material is arranged.

The rings are flexible and allow axial displacement of the bearing, while the damping material will dampen the vibrations.

A disadvantage of this solution is that it is quite bulky and relatively expensive.

The present invention aims to provide at least a solution to said axial vibrations and other problems, while at the same time to be a relatively compact and inexpensive solu- tion.

The object of the present invention is a compressor device with a housing and provided at least with one compressor element and a drive for the compressor element, charac- terised in that all bearings of at least one shaft in the compressor device, configured to bear static-axial load with their static bearing ring, are arranged axially slidable in the housing relative to the housing, wherein all of said bearings are provided with a bearing damper comprising at least one damper, wherein the static bearing ring is able to act upon this damper when the static bearing ring axially slides in the housing, wherein said bearings and bearing dampers are arranged such that at least two surfaces slide over each other when the static bearing ring axially slides relative to the housing.

By "the static bearing ring may act upon the damper" it is meant that the bearing ring will contact and exert a force on the damper and will experience a damping force from the damper when the static bearing ring axially slides in the housing.

An advantage is that such a bearing damper and its arrangement will provide a damping of said axial vibrations and will also allow a certain axial flexibility of the bearing and all this in a compact and inexpensive manner.

The damper will provide axial flexibility, while sliding the at least two surfaces against or over each other will provide damping.

Preferably, the bearing damper also comprises an axially slidable bush or sleeve which is arranged in series between the static bearing ring and the damper.

This offers the advantage that the surfaces of the bush or sleeve which come into con- tact with the bearing and the damper can be suitably shaped to fit the bearing and the damper. Hence, there is no need to provide an adapted design for the bearing and the damper, but it will be possible to use a commonly available bearing and damper.

Preferably, said two surfaces relate to a portion of the surface of the housing and a por- tion of the surface of said bush or sleeve.

This offers the advantage that the size of the surfaces sliding over each other can be adjusted by providing the bush or sleeve with the suitable shape or size, such that the degree of damping can also be selected in this way.

In a practical embodiment, said damper comprises a spring element, such as for instance a cup spring.

However, the damper can be embodied in different ways. It is important that the damp- er will allow the necessary axial flexibility. Preferably, the axial stiffness of the damper is chosen to be smaller than the axial com- ponent of the stiffness of the relevant bearing:

K_de,ax < K_I ax wherein K_de,ax is the axial spring constant of the damper and K_l,ax is the axial spring constant of the bearing.

The radial stiffness of the damper is preferably of the same order of magnitude or greater than the radial component of the bearing stiffness:

A * K_I, rad < K_de,rad < B * K_I, rad, wherein K_de,rad is the radial spring constant of the damper and K_l,rad is the radial spring constant of the bearing, wherein A is between 0.9 and 0.5 and B is between 1 and 10 and preferably be- tween 3 and 7.

The invention also relates to a device with a housing and a rotating shaft with a bearing arranged therein, characterised in that the bearing with its static bearing ring is ar- ranged axially slidable in the housing relative to the housing, wherein the bearing is pro- vided with a bearing damper comprising at least one damper, wherein the static bearing ring is able to act upon this damper when the static bearing ring axially slides in the housing, wherein said bearing and the bearing damper are arranged such that at least two surfaces slide over each other when the static bearing ring axially slides relative to the housing.

It is obvious that the advantages will be the same as those of the compressor device according to the invention.

In order to better demonstrate the features of the invention, some preferred embodi- ments of a compressor device and device equipped with a bearing damper according to the invention are described below, by way of example without any limiting character, with reference to the accompanying drawings, in which:

Figure 1 schematically represents a cross-section of a compressor device according to the invention;

Figure 2 represents on a larger scale the portion indicated by F2 in Figure 1.

The cross section of a compressor device 1 according to the invention, shown schemati- cally in Figure 1, comprises a housing 2 with a compressor element 3 and a drive 4 there- in.

Although the housing 2, in this case, comprises both the compressor element 3 and the drive 4, it is not excluded that both have a separate housing 2, i.e. a compressor element housing and a drive housing, which are connected to each other or are coupled to each other.

Although in the example shown there is only one compressor element 3 of the screw compressor element 3 type, it cannot be ruled out that there are more compressor ele- ments 3 and/or of another type, such as, for instance, a tooth compressor element, a turbocharger element or the like.

The screw compressor element 3 comprises two screw rotors 5 which are rotatably ar- ranged in the housing 2 by means of their shafts 6 with bearings 7.

The drive 4 comprises a motor rotor 8, which will drive the shaft 6 of a screw rotor 5 and a motor stator 9.

The motor rotor 8 is rotatably arranged with its shaft 10 in the housing 2 by means of bearings 11.

The bearings 11 comprise a so-called static bearing ring 12, in this case the outer ring 12 of the bearings 11, with which the bearing 11 is arranged in the housing 2. The inner ring 13 is the moving bearing ring 13 and is arranged around the shaft 10 of the motor rotor 8. This inner ring 13 will rotate when this shaft 10 rotates. As is known, roller elements 14, in this case balls, are arranged between the inner ring 13 and the outer ring 12. All bearings 11 of the shaft 10 of the motor rotor 8, which are configured to bear static- axial load, are arranged according to the invention in the housing 2 with their static bearing ring 12 axially slidabie relative to the housing 2.

This means that under the influence of an axial force, the static bearing ring 12 will move relative to the housing 2 in the axial direction X-X’.

In Figure 2 one such bearing 11 of the shaft 10 is shown carrying an static-axial load. Each bearing 11 of this shaft 10 carrying static-axial load will be constructed in a similar manner.

Furthermore, all of said bearings 11 according to the invention are provided with a bear- ing damper 15 comprising at least one damper 16.

In this case, this damper 16 comprises a spring element 17 in the form of a cup spring.

However, it is not excluded that the damper 16 comprises several spring elements 17 or cup springs or that the damper 16 comprises an annular element made of an elastomer such as, for instance, a rubber.

As can be seen in Figure 2, the damper 16 is mounted against a radially extending face 18 of the housing 2.

The static bearing ring 12 can act upon this damper 16 when the static bearing ring 12 axially slides in the housing 2.

This means that, when the static bearing ring 12 axially slides in the housing 2 under the influence of axial forces, this bearing ring 12 will directly or indirectly exert a force on the damper 16.

The arrangement of the bearing 11 and bearing damper 15 is such that at least two sur- faces 19, 20 slide over each other when the static bearing ring 12 axially slides with re- spect to the housing 2. As can be seen in Figure 2, said two surfaces 19, 20 relate to a portion of the surface 19 of the housing 2 and a portion of the surface 20 of the static bearing ring 12. in particu- lar, the portion of the surface 19 of housing 2 contacting the respective bearing 11 and the outer surface 20 of the static bearing ring 12.

It should be noted that both of said surfaces 19, 20 are in direct physical contact with each other, without a void or other material such as, for instance, a lubricating liquid being present between both surfaces 19, 20.

In the illustrated embodiment, the bearing damper 15 also comprises an axially slidable bush or sleeve 21.

This bush or sleeve 21 is arranged in series between the static bearing ring 12 and the damper 16.

Thus, as can be seen in Figure 2, the bush or sleeve 21 contacts both the static bearing ring 12 and the damper 16.

Although not necessary for the invention, in this case, the outer surface 22 of the bush or sleeve 21 will contact the housing 2.

As a result, a portion of the surface 22 of the bush or sleeve 21, in particular, in this case, the outer surface 22 of the bush or sleeve 21, can slide over a portion of the surface 23 of the housing 2. Note that this portion of the surface 23 of the housing is a different portion than the portion of the surface 19 of the housing 2 that contacts the outer sur- face 20 of the static bearing ring 12.

In other words, in this case, the arrangement of the bearing 11 and the bearing damper 15 is such that there are four surfaces 19, 20, 22, 23 which can slide over each other when the static bearing ring 12 axially slides with respect to the housing 2: the outer surface 20 of the static bearing ring 12 and the corresponding portion of the surface 19 of the housing 2, the outer surface 22 of the bush or sleeve 21 and the corresponding portion of the surface 23 of the housing 2.

Although the bush or sleeve 21 is a separate component in the example shown, it can- not be ruled out that it forms part of the respective bearing 11.

The operation of the compressor device 1 is very simple and as follows.

During the operation of the compressor device 1, the drive 4 will drive the compressor element 3, wherein the motor rotor 8 will drive the shaft 6 of a screw rotor 5.

The screw rotors 5 will in turn co-rotate and compress gas in the known manner.

During the operation of the compressor device 1, axial vibrations or oscillations will oc- cur, whereby the shaft of the motor rotor 8 will move in axial direction X-X'.

As a result, the bearing 11 and said bush or sleeve 21 will move according to the arrow C in Figure 2.

Due to the displacement, said surfaces 19, 20, 22, 23 will slide over each other, as a re- sult of which friction will occur.

This friction will generate a damping force, as a result of which the axial vibrations will be damped, since the forces will be absorbed by the friction.

The bearing 11 itself will experience much smaller axial forces and stresses, since the greater part thereof is absorbed by the bearing damper 15.

Moreover, the axial displacement of the shaft 10 of the motor rotor 8, as a result of said vibrations, will hereby be able to be limited by the correct choices of the stiffness and the damping properties of the damper 16, since the vibrations are prevented from propagating further in the drive 4 and the compressor element 3.

Hence, problems due to these axial vibrations and the axial displacement of the shaft 10 of the motor rotor 8 further down in the compressor device 1 are avoided.

Although in the example described and illustrated above, the bearings 11 of the shaft 10 of the motor rotor 8 are provided with a bearing damper 15, it is not excluded that all bearings of another shaft of the compressor device 1 which carry a static-axial load, are provided with a bearing damper 15.

Although the examples shown and described above always refer to a compressor device 1, the invention can also be applied in other devices in which there is a rotating shaft 10 which is carried by, or mounted in, the machine by means of a bearing 11.

The present invention is by no means limited to the embodiments described by way of example and shown in the figures, but a compressor device and device equipped with a bearing damper according to the invention can be realised in all kinds of shapes and dimensions without departing from the scope of the invention.

Claims

CLAIMS A compressor device with a housing (2) and provided with at ieast one compres- sor element (3) and a drive (4) for the compressor element (3), characterised in that ail bearings (11) of at least one shaft (10) in the compressor device (1), con- figured to bear static-axial load with their static bearing ring (12), are arranged ax- ially slidable in the housing (2) relative to the housing (2), wherein all of said bear- ings (11) are provided with a bearing damper (15) comprising at least one damper (16), wherein the static bearing ring (12) is able to act upon this damper (16) when the static bearing ring (12) axially slides in the housing (2), wherein said bearings (11) and bearing dampers (15) are arranged such that at least two sur- faces (19, 20, 22, 23) slide over each other when the static bearing ring (12) axially slides relative to the housing (2). The compressor device according to claim 1, characterised in that said two sur- faces (19, 20) concern a part of the surface (19) of the housing (2) and a part of the surface (20) of the static bearing ring (12). The compressor device according to claim 1 or 2, characterised in that the bear- ing damper (15) also comprises an axially slidable bush or sleeve (21) arranged in series between the static bearing ring (12) and the damper (16). The compressor device according to claim 3, characterised in that said two sur- faces (22, 23) concern a part of the surface (23) of the housing (2) and a part of the surface (22) of said bush or sleeve (21). The compressor device according to any one of the preceding claims, character- ised in that said damper (16) comprises a spring element (17), such as, for exam- ple, a cup spring. The compressor device according to any one of the preceding claims, character- ised in that said damper (16) comprises an annular element, made of an elasto- mer. ,- A device with a housing (2) and a rotating shaft (10) with a bearing (11) arranged therein, characterised in that the bearing (11) with its static bearing ring (12) is arranged axially slidable in the housing (2) relative to the housing (2), wherein the bearing (11) is provided with a bearing damper (15) comprising at least one damper (16), wherein the static bearing ring (12) is able to act upon this damper

(16) when the static bearing ring (12) axially slides in the housing (2), wherein said bearing (11) and the bearing damper (15) are arranged such that at least two sur- faces (19, 20) slide over each other when the static bearing ring (12) axially slides relative to the housing (2).