DE102014209639A1 - bearing arrangement - Google Patents

Abstract

The invention relates to a bearing arrangement (1) for mounting a first machine part (2) in a second machine part (3) comprising a first rolling bearing (4) and a second rolling bearing (5), wherein the two rolling bearings (4, 5) under axial Preload in the bearing assembly (1) are installed, wherein between at least one end face (6) of at least one ring (7) of the rolling bearing (4) and an axial bearing surface (8) of the two machine parts (3) comprises a device (9) for Generation of an axial biasing force is arranged. In order to maintain the prestress even with temperature changes, the invention provides that the device (9) for generating an axial prestressing force comprises: a first clamping ring (10) having a first conical surface (11) in a radially inner end region, the first one Clamping ring (10) with the axial abutment surface (8) of one of the two machine parts (3) is directly or indirectly in contact, a second clamping ring (12) having a second conical surface (13) in a radially outer end region, which is congruent to the first Conical surface (11) is formed, wherein the second clamping ring (12) with the end face (6) of one of the rings (7) of the rolling bearing (4) is directly or indirectly in contact, wherein the coefficient of thermal expansion (α1) of the first clamping ring (10 ) is smaller than the thermal expansion coefficient (α2) of the second clamping ring (12).

Description

The invention relates to a bearing assembly for supporting a first machine part in a second machine part, comprising a first roller bearing and a second rolling bearing, wherein the two rolling bearings are axially against each other, in particular under axial bias or axial play in the bearing assembly are installed, wherein between at least one End side of at least one ring of the rolling bearing and an axial bearing surface of one of the two machine parts or a component connected thereto, a device for generating an axial displacement, in particular for generating an axial biasing force, is arranged.

Prestressed bearing arrangements of the type mentioned are well known and customary in the prior art. Often two tapered roller bearings (but for example also angular contact ball bearings, thrust roller bearings, thrust ball bearings) axially braced against each other to accomplish a play-free storage, for example, a shaft in a housing. For strength and weight reasons, the bearings and their rings are usually made of steel, while light metal, in particular aluminum, is used for the housing. Pre-stressed bearing arrangements are often realized even when using more than two rows of bearings.

With such employed bearings, it can lead to "hot runners" if the set axial preload does not reduce fast enough during operation when heating the machine parts. It may also lead to unwanted noise, for example, in a gear application, when the set axial bias is lost during operation and the gear pairs, which are located on a supported shaft change their point of engagement. During operation of the bearing arrangement, the optimum preload range or even a possible optimum bearing air area will be left, which is otherwise desired in order to ensure optimum operating conditions of the bearings. The heat development in the bearing and the load distribution in the bearing assembly or any existing axial bearing clearance can then no longer be reliably controlled.

The invention has the object of developing a generic bearing assembly so that it is ensured that even with temperature changes, the desired axial preload or a defined axial bearing clearance is maintained in the bearings, which should also be ensured in particular when the housing of a first Material (especially light metal) exists, while the bearings, and especially their rings and the shaft of a different material (namely mostly steel) exist.

• – einen ersten Spannring, der in einem radial innenliegenden Endbereich eine erste Kegelfläche aufweist, wobei der erste Spannring mit der axialen Anlagefläche eines der beiden Maschinenteile oder mit der Stirnseite eines der Ringe eines der Wälzlager direkt oder indirekt in Kontakt steht,
• – einen zweiten Spannring, der in einem radial außenliegenden Endbereich eine zweite Kegelfläche aufweist, die kongruent zur ersten Kegelfläche ausgebildet ist, wobei der zweite Spannring mit der Stirnseite eines der Ringe eines der Wälzlager oder mit der axialen Anlagefläche eines der beiden Maschinenteile direkt oder indirekt in Kontakt steht,

wobei der Wärmeausdehnkoeffizient des ersten Spannrings kleiner ist als der Wärmeausdehnkoeffizient des zweiten Spannrings.The solution of this problem by the invention is characterized in that the device for generating an axial displacement, in particular an axial prestressing force comprises:

• A first clamping ring which has a first conical surface in a radially inward end region, the first clamping ring being in direct or indirect contact with the axial abutment surface of one of the two machine parts or with the end face of one of the rings of one of the rolling bearings;
• - A second clamping ring having a second conical surface in a radially outer end region, which is formed congruent to the first conical surface, wherein the second clamping ring with the end face of one of the rings of the rolling bearing or with the axial bearing surface of one of the two machine parts directly or indirectly in Contact stands,

wherein the coefficient of thermal expansion of the first clamping ring is smaller than the coefficient of thermal expansion of the second clamping ring.

Of the mentioned device for generating an axial displacement, in particular an axial prestressing force, more than one can also be used, for example in the middle between two bearings or at the end in the region of the bearing arrangement.

The first clamping ring is preferably made of steel. The second clamping ring is preferably made of non-ferrous metal, light metal or a light metal alloy; Eligible and proven materials here are in particular bronze, brass, copper, aluminum, zinc, tin or magnesium or alloys with these components.

While the outer clamping ring is usually made of steel (coefficient of thermal expansion of approx. Α ₁ = 0.000011 to 0.000012 1 / K), the inner clamping ring may contain, for example, brass, copper, aluminum, magnesium or bronze (eg. with a thermal expansion coefficient for special cast bronze of approx. α ₂ = 0.0000185 1 / K) or also tin or zinc.

The difference between the thermal expansion coefficients is preferably at least 0.000002 1 / K.

The first and second conical surfaces preferably have a cone angle to the axis of the bearing assembly which is between 10 ° and 75 °, preferably between 20 ° and 65 ° and more preferably between 25 ° and 60 °.

The first and / or the second conical surface are preferably provided with a friction-reducing coating, wherein the friction-reducing coating is or has in particular polytetrafluoroethylene (PTFE) or bonded coating. The first and / or the second conical surface may also be alternatively or additively provided with a lubricant. In this respect, it can also be envisaged that for receiving lubricant in the surface of the conical surface receiving pockets or grooves are incorporated.

The first clamping ring may be connected to a carrier ring (this is preferably intended to a screw), wherein the support ring between the first clamping ring and the axial bearing surface of one of the two machine parts is arranged. Between the first clamping ring and the second clamping ring, means for securing against rotation about the axis of the bearing arrangement can furthermore be present. These means for preventing rotation are preferably formed by at least one bolt which is fixed in the carrier ring and extending in the direction of the axis of the bearing assembly, wherein the bolt is disposed in a bore in the second clamping ring, wherein the bore to the bolt has radial clearance. The bore can be formed as a blind bore in the second clamping ring. Between the carrier ring and the second clamping ring can finally be arranged a transport lock and / or production fixing; this preferably consists of at least one screw which holds the carrier ring and the second clamping ring temporarily.

The inner second clamping ring may have a turned-in annular groove on an end face in the radially inner region in order to release the plane surface somewhat in this way and to avoid tilting moments.

Easier conforming of the radially inner second clamping ring to temperature variations may be facilitated by having the ring circumferentially with some (eg, four) radially extending slots extending over part of the radial extent of the ring.

The proposed solution ensures a uniform axial preload or a defined internal clearance of the antifriction bearings. When installing rolling bearings in housings, in particular made of aluminum and magnesium can be used in temperature change, for. B. in the warming of 20 ° C to 100 ° C, the bearing preload and the bearing air are kept as constant as possible. Accordingly, "hot runners" can be avoided because the adjusted axial preload is maintained upon heating of the bearing assembly. It is also possible to avoid unwanted noise in gears, since it no longer comes to an unintentional axial bearing clearance, which change the tooth engagement of the gears.

In the present case is spoken of conical surfaces on which the first and the second clamping ring cooperate. Of course, it is also included in the scope of the present invention, when the surfaces in question are slightly convex and then cooperate in the manner of two congruent Kugelkalotten.

The proposed solution can be used, for example, both in industrial gears and in automobile transmissions for cars and trucks (also in differential gears).

It is very advantageous that during operation of the bearing permanently low noise is ensured. This is particularly important in some applications, e.g. B. in actuators of theaters.

The proposed idea is therefore based on a cone Axialscheibenverband, which generates an axial expansion when heated. The inner ring has a greater thermal expansion than the outer ring. Transmission of the axial force is ensured.

In the non-installed state, the plane surfaces of the two clamping rings lie with the conical surfaces on a plane, so that there is no change in the preload in the bearing assembly through the clamping rings in this state.

The application of the proposed solution allows the compensation of the bearing clearance or the bias by an axial displacement, d. H. with temperature changes, there is a gap change (in a play-bearing).

As material for the clamping rings such substances are used, which have a different thermal expansion coefficient; Preferably, there are also good sliding properties, since the conical surfaces must indeed slide on each other in operation. Also, compressive strength and machinability are relevant criteria.

In the drawings, embodiments of the invention are shown. Show it:

1 a radial section through a bearing assembly in which a shaft is mounted by means of two axially preloaded tapered roller bearings in a housing,

2 in radial section, an apparatus for generating an axial biasing force according to a first embodiment of the invention,

3 in radial section, the device for generating an axial biasing force according to a second embodiment of the invention,

4 in radial section an alternatively configured bearing arrangement with which a toothing is mounted on a shaft between two bearings,

5 in radial section, a further alternatively configured bearing arrangement, wherein an axially end-side region of a shaft bearing is shown, and

6 in radial section one too 5 another alternative configured bearing arrangement.

In 1 is a bearing arrangement 1 outlined, with the first machine part 2 in the form of a shaft in a second machine part 3 is stored in the form of a housing. The storage takes place with two roller bearings 4 and 5 which are designed here as tapered roller bearings (here in X arrangement). The two rolling bearings 4 . 5 are axially, ie biased in the direction of the axis a of the bearing assembly.

In the case 3 or in one with the housing 3 connected lid 19 is an axial contact surface 8th for a device 9 designed to generate an axial biasing force; at this contact surface 8th is the device 9 at. With its other (right) outside is the device 9 on the bearing outer ring 7 of the left rolling bearing 4 and here on one end 6 of the bearing ring 7 at. Does it come with the device 9 to an extent in the direction of the axis a, this consequently acts biasing on the two rolling bearings 4 . 5 ,

The embodiment of the said device 9 for generating an axial biasing force is best from the 2 and 3 out.

It follows that the device 9 two clamping rings 10 and 12 has, which are arranged concentrically to each other. The radially outer clamping ring 10 has a first conical surface in its radially inner region 11 , The radially inner clamping ring 12 has a second conical surface in its radially outer region 13 , The two conical surfaces 11 . 13 are congruent and have a cone angle β (s. 2 ). This is in the exemplary embodiment at about 45 °.

The first clamping ring 10 is with a carrier ring 14 screwed, including the screws 18 serve. So that the second clamping ring 12 relative to the first clamping ring 10 can not rotate about the axis a, are means 15 intended to prevent rotation. These consist in the present case of at least one bolt which is tightly seated in a bore in the carrier ring 14 sits and extends in the axial direction a. In the second clamping ring 12 is a corresponding hole 16 introduced (in the present case designed as a blind bore), in which the bolt 15 sitting with radial play.

It is essential that the thermal expansion coefficient α _{1 of} the material of the first clamping ring 10 is smaller than the thermal expansion coefficient α _{2 of} the material of the second clamping ring 12 , This has the consequence that when heating the device 9 the inner second clamping ring 12 due to temperature increases more than the outer first clamping ring 10 , so that the inner clamping ring 12 over the conical surfaces 11 . 13 pushed out in the figures to the right and so on the front page 6 of the bearing outer ring 7 of the rolling bearing 4 suppressed; this has an effect on the bearing preload. This can be tuned so that a temperature-induced expansion of the housing 3 (For example, consisting of aluminum) is exactly balanced. The bearing preload in the two bearings 4 . 5 thus remains constant despite temperature increase.

To mention is still a transport safety or manufacturing fixation, by screws 17 (S. 3 ) is accomplished. With these screws 17 becomes a composite consisting of first clamping ring 10 , second tension ring 12 and carrier ring 14 manufactured, so that a captive unit for transport is given; during assembly of the device 9 in the bearing arrangement 1 be the screws 17 then removed.

The screws 17 but also serve in the manufacture of the device 9 to a flush (right) face between the two clamping rings 10 . 12 to create while grinding.

In the 4 to 6 Variations of the illustrated bearing arrangement are shown.

In 4 is a bearing arrangement 1 shown in which the two rolling bearings 4 and 5 in sections of the housing 3 are arranged and the shaft 2 to store. On the shaft is a gearing 20 arranged.

On the left side is the case 3 through a lid 19 completed. In the present case are two devices 9 (as described above) provided between the respective rolling bearings 4 respectively. 5 and the housing 3 or the lid 19 are positioned.

Is shown in 4 a bearing assembly in X-arrangement.

In 5 can be seen as an axial end of the shaft 2 in the case 3 is stored. Again, as in the solution according to 4 - two devices 9 used as described above.

Is shown in 5 a fixed bearing assembly in X-arrangement.

According to 6 are the two devices 9 arranged adjacent and between the two rolling bearings 4 and 5 placed. Again, the case is 3 again by means of a lid 19 completed.

Is shown in 6 a fixed bearing arrangement in O arrangement.

It is possible in all the above solutions also that the first clamping ring 10 - Made of steel - is integrally formed with the bearing outer ring.

LIST OF REFERENCE NUMBERS

1

 bearing arrangement

2

 first machine part (shaft)

3

 second machine part (housing)

4

 first rolling bearing (tapered roller bearing)

5

 second rolling bearing (tapered roller bearing)

6

 front

7

 bearing ring

8th

 axial contact surface

9

 Device for generating an axial preload force

10

 first clamping ring

11

 first conical surface

12

 second clamping ring

13

 second conical surface

14

 support ring

15

 Anti-twist device (bolt)

16

 drilling

17

 Transport security / production fixation

18

 screw

19

 Cover (component connected to the housing)

20

 gearing

α ₁

 Thermal expansion coefficient of the first clamping ring

α ₂

 Thermal expansion coefficient of the second clamping ring

β

 cone angle

a

 Axle of the bearing assembly

Claims (11)

Bearing arrangement ( 1 ) for storing a first machine part ( 2 ) in a second machine part ( 3 ), comprising a first rolling bearing ( 4 ) and a second rolling bearing ( 5 ), whereby the two rolling bearings ( 4 . 5 ) are set axially against each other, in particular under axial bias or axial play in the bearing assembly ( 1 ) are installed, wherein between at least one end face ( 6 ) at least one ring ( 7 ) one of the rolling bearings ( 4 ) and an axial contact surface ( 8th ) one of the two machine parts ( 3 ) or a component ( 19 ) a device ( 9 ) is arranged for generating an axial displacement, in particular for generating an axial prestressing force, characterized in that the device ( 9 ) for generating an axial displacement, in particular an axial prestressing force, comprising: - a first clamping ring ( 10 ), which in a radially inner end region has a first conical surface ( 11 ), wherein the first clamping ring ( 10 ) with the axial bearing surface ( 8th ) one of the two machine parts ( 3 ) or with the front side ( 6 ) one of the rings ( 7 ) one of the rolling bearings ( 4 ) is directly or indirectly in contact, - a second clamping ring ( 12 ), which in a radially outer end region has a second conical surface ( 13 ) which is congruent to the first conical surface ( 11 ), wherein the second clamping ring ( 12 ) with the front side ( 6 ) one of the rings ( 7 ) one of the rolling bearings ( 4 ) or with the axial bearing surface ( 8th ) one of the two machine parts ( 3 ) is directly or indirectly in contact, wherein the coefficient of thermal expansion (α ₁ ) of the first clamping ring ( 10 ) is smaller than the thermal expansion coefficient (α ₂ ) of the second clamping ring ( 12 ). Bearing arrangement according to claim 1, characterized in that the first clamping ring ( 10 ) consists of steel. Bearing arrangement according to claim 1 or 2, characterized in that the second clamping ring ( 12 ) consists of non-ferrous metal, light metal or a light metal alloy. Bearing arrangement according to one of claims 1 to 3, characterized in that the difference between the Wärmeausdehnkoeffizienten (α ₂ - α ₁ ) is at least 0.000002 1 / K. Bearing arrangement according to one of claims 1 to 4, characterized in that the first and the second conical surface ( 11 . 13 ) a cone angle (β) to the axis (a) of the bearing assembly ( 1 ), which is between 10 ° and 75 °, preferably between 20 ° and 65 °, more preferably between 25 ° and 60 °. Bearing arrangement according to one of claims 1 to 5, characterized in that the first and / or the second conical surface ( 11 . 13 ) are provided with a friction-reducing coating, wherein the friction-reducing coating in particular polytetrafluoroethylene (PTFE) or lubricating varnish is or has. Bearing arrangement according to one of claims 1 to 5, characterized in that the first and / or the second conical surface ( 11 . 13 ) are provided with a lubricant. Bearing arrangement according to one of claims 1 to 7, characterized in that the first clamping ring ( 10 ) with a carrier ring ( 14 ), in particular screwed, is, wherein the support ring ( 14 ) between the first clamping ring ( 10 ) and the axial contact surface ( 8th ) one of the two machine parts ( 3 ) or a component ( 19 ) is arranged. Bearing arrangement according to claim 8, characterized in that between the first clamping ring ( 10 ) and the second clamping ring ( 12 ) Medium ( 15 ) for preventing rotation about the axis (a) of the bearing arrangement ( 1 ), whereby the funds ( 15 ) for preventing rotation, preferably by at least one bolt ( 15 ) formed in the carrier ring ( 14 ) and in the direction of the axis (a) of the bearing assembly ( 1 ), wherein the bolt ( 15 ) in a bore ( 16 ) in the second clamping ring ( 14 ), wherein the bore ( 16 ) to the bolt ( 15 ) has radial clearance. Bearing arrangement according to claim 9, characterized in that the bore ( 16 ) as a blind hole in the second clamping ring ( 14 ) is trained. Bearing arrangement according to one of claims 8 to 10, characterized in that between the support ring ( 14 ) and the second clamping ring ( 14 ) a transport security and / or manufacturing fixation ( 17 ) is arranged, preferably at least one screw, the carrier ring ( 14 ) and the second clamping ring ( 12 ) temporarily together.

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