EP2019929A1

EP2019929A1 - Rolling element bearing with different guide pockets

Info

Publication number: EP2019929A1
Application number: EP07722454A
Authority: EP
Inventors: Alfred Pecher; Karl Bywalez; Joachim Schleifenbaum
Original assignee: Schaeffler KG
Current assignee: Schaeffler Technologies AG and Co KG
Priority date: 2006-05-24
Filing date: 2007-05-22
Publication date: 2009-02-04
Also published as: CN101484714B; KR20090018969A; DE102006024376B4; WO2007134591A1; CN101484714A; DE102006024376A1; JP2009537773A; US20090290826A1

Abstract

The invention relates to a rolling element bearing comprising a cage (01) with at least one first group of guide pockets (04, 06, 07, 08) in which rolling bodies are guided with a certain play. According to the invention, the degree of play is different at least in a first guide pocket (04) of the first group from the degree of play in a second guide pocket (06) of said first group of guide pockets.

Description

Name of the invention

Rolling bearings with different guide pockets

description

Field of the invention

The invention relates to rolling bearings with a cage for guiding the rolling elements.

Rolling bearings cause in certain operating conditions increased running noise, which is disturbing in many applications. So far, it has been thought that this noise, which occurs especially at higher speeds, is caused by a chaotic cage motion, also known as cage instability.

From DE 197 81 320 B4 a noise-reduced rolling bearing with a raceway is known, which is designed as a composite hollow ring. The hollow ring consists of a first ring part, which is in contact with the rolling elements, and a second ring part, which encloses the first ring part. Between the ring parts, a gap is formed, which is filled with oil or other liquid. The raceway of the first ring part deviates in sections from the circular shape by one or more elastic raceway curvatures. At each point in time, some rolling elements are preloaded, whereby also receives a radial bias by the mounted shaft. The shaft thus has only a small possibility for proper movement, so that a noise is reduced. A disadvantage of this solution is the high cost, which is necessary for the assembly of the liquid-filled gap. The liquid must be under pressure, for which appropriate measures for sealing are required. A further disadvantage is that due to the bias, the rolling friction of the rolling elements is increased on the races. Furthermore, the noise generated by the interaction between the cage and the rolling elements is only slightly damped.

To reduce noise, as is known, for example, from EP 1 083 353 A2, special fats are also used which have a damping effect. However, these fats can not be used at higher storage temperatures due to their low temperature resistance.

The object of the present invention is thus to provide rolling bearings with a cage whose operating noise is lowered by a simple measure to be implemented without the rolling friction of the rolling elements is increased.

This object is achieved by a roller bearing according to the appended claim 1.

The invention is based on the recognition that in rolling bearings with a cage, which consists for example of sheet metal, brass or hard tissue and the leadership of the rolling elements, noise in particular by excitation of the cage occur due to a concerted movement of the rolling elements in conjunction with emerge from the cage. In contrast to the previous assumption of the experts, according to which a chaotic cage movement occurs when the occurrence of the above-mentioned cage instability, the present invention assumes that the rolling elements in the cage of a conventional rolling bearing to an orderly movement to be stimulated. The rolling elements in a rolling bearing in combination with the cage perform no chaotic but a deterministic movement. The rolling bearing changes from a stable state of a quiet operation to a stable state of noisy operation when cage noise occurs.

The stable state of the noisy operation is characterized in that the rolling elements periodically during their movement in the pockets have a certain state, which leads to the excitation of the cage. However, for this excitation, it is irrelevant that sections of the movement of the rolling elements can be uneven, irregular or chaotic. The same design of the rolling elements and their pockets in the cage causes at least the majority of the rolling elements periodically a same state during movement in the pocket, that is, perform a concerted movement. This condition may be characterized by the location of the rolling element within the pocket or also the velocity vector or the acceleration vector with respect to the pocket. This periodic state leads to a periodic excitation of the cage and finally to swinging of the cage. The swinging of the cage is a major cause of the increased operating noise of the rolling bearing. The swinging of the cage can be transferred to other parts of the rolling bearing and the machine.

Essential for the invention is first that the rolling elements are performed with a game in the guide pockets of the cage, which game differs at least in one of these pockets of the game in another pocket of the cage.

The diversity of the games in these leadership pockets can both by different training of the respective leadership pockets, especially in the same rolling elements, as well as by different

Training of the respective rolling elements, in particular rolling elements different dimensions, can be achieved.

In a rolling bearing according to the invention, therefore, the stable state of noisy operation can not occur. Consequently, a periodic excitation of the cage by each of the rolling elements is not possible and a concerted movement between the rolling elements and the cage can not occur.

A particular advantage of this invention is that a far-reaching reduction of the noise generated in the region of the cage of a roller bearing is achieved by a design change that is easy to implement. It requires no additional components or constructive additions, which would increase the cost of producing a rolling bearing according to the invention.

Preferably, many rolling bearings have only the same, i. in the context of usual manufacturing tolerances same, rolling elements. In other words, the rolling elements are within a certain sorting (same nominal size). Some bearings have several groups of identical rolling elements, which are guided in one or more cages. A periodic excitation of the cage of such a rolling bearing can be avoided according to the invention in that the play is designed differently within at least one of the groups of identical rolling elements.

Rolling bearings according to the invention are particularly preferably ball bearings, in which case the rolling bodies are designed as balls.

In a further preferred embodiment, the embodiments of the game in the individual pockets are designed largely irregular, so that in a majority of pockets no bag of this group has the same game as another bag of this group. Some of the bags can Nevertheless, be executed the same, especially if the same pockets are not arranged side by side or opposite each other. Preferably, no bag is exactly the same as another bag.

In a modified embodiment, the game differs in the pockets of a group to guide same rolling elements due to different shapes of the pockets. For example, the pockets may have an elliptical cross-section, these ellipses are not geometrically similar, but have a same or similar circumference. The different shape of the pockets can also be achieved by special shapes such as local widenings or indentations. For cages in which the rolling elements are guided on one or more leading edges, the edges can be designed differently. For example, in case-like pockets in which the rolling elements are guided at four edges, the edge distances of the pockets may vary.

In a particular embodiment, the play does not differ in the pockets of a group for guiding identical rolling elements due to a different shape of the pockets. All pockets of a group for the guidance of identical rolling elements are geometrically similar and differ only by a scaling factor.

Bags for guiding rolling elements can usually be characterized by a radius which describes the size of the volume in which the rolling element can rotate. This volume is determined by the geometry of the cage.

In ball bearings, the pockets are usually dome-shaped. The diversity of the game in the pockets can be described in such cases by different radii. Other pocket shapes included are, for example, a box shape or a frame shape. In an advantageous embodiment of a rolling bearing according to the invention therefore the radii of the pockets are of different sizes, in particular, in the case of a ball bearing according to the invention with balls, the radii of the dome-shaped pockets have different sizes.

In a modified embodiment, the play in the pockets of a group for guiding the rolling elements does not differ due to a different shape of the pockets, but rather due to the different design of the respective rolling elements. That is, different rolling elements or rolling elements of different dimensions are used here, which differ in their dimensions beyond the usual manufacturing tolerance.

Further advantages, details and developments of the invention will become apparent from the following description of several embodiments, with reference to the drawing.

The only Fig. 1 shows two views of a cage 01 of a rolling bearing according to the invention. 1 shows a side sectional view of a four-pocket portion of a cage half of the cage 01. FIG. 1 b shows a plan view of a four-pocket portion of the cage half of the cage 01.

The half of the cage 01 shown in FIG. 1 serves to guide eight balls (not shown), which act as rolling elements in a ball bearing (not shown). The cage 01 has eight dome-shaped pockets 02 for this purpose. Between the pockets 02 holes 03 for the implementation of rivets or other connection means (not shown) are arranged. To mount the ball bearing, place the eight balls between the two halves of the cage and the two halves of the cage 01 with eight rivets connected with each other. In the illustrated embodiment, the cage 01 has an outer diameter of about 70 mm and an inner diameter of 65 mm and consists of a sheet having a thickness of 1 to 2 mm.

The eight pockets 02 are evenly distributed over the annular cage 01. Consequently, the centers of the pockets 02 each have an angle of 45 degrees to each other. The balls have a diameter adapted to the pocket size. The dome-shaped pockets 02 are slightly larger than the balls executed, so that the balls are guided with a game in the pockets 02. The game allows a free rolling of the balls in the cage 01. Furthermore, there is a lubricant in the spaces between the balls and the pockets 02, so that the balls can roll with little friction in the pockets 02.

The radii of the eight dome-shaped pockets 02 are made different sizes. This is not a different size, which is due to manufacturing tolerances, since they would be too small in today's precision manufacturing, to prevent a regular stimulation of the cage. The radii of the pockets 02 are in the illustrated embodiment in the following proportions to each other:

first pocket 04: R1 = 8.45 mm second pocket 06: R2 = R1 + 1, 4 mm third pocket 07: R3 = R1 - 0.41 mm fourth pocket (not shown): R4 = R1 fifth pocket (not shown) : R5 = R2 sixth pocket (not shown): R6 = R3 seventh pocket (not shown): R7 = R2 + 0.5mm eighth pocket 08: R8 = R1 + 0.35mm. The pockets 02 in this example have an average radius of 8.979 millimeters. The radii of the pockets 02 are up to 1, 37 millimeters larger and up to 0.94 millimeters smaller than the average radius of the pockets 02. These deviations amount to a multiple of the usual manufacturing tolerance.

The radii of the pockets 02 are randomly selected within a given bandwidth. They are preferably up to 20 percent larger or smaller than the average radius of the pockets 02.

The dimensions of the game in the pockets 02 range in the o. G. Example of 0.29 millimeters to 2.6 millimeters and therefore differ by about a factor of 10. This relative indication is a benchmark for the execution of the game in the pockets 02 of a rolling bearing according to the invention. The difference in the size of the play in the pockets is limited by the minimum allowable amount of play and the maximum allowable amount of play. The minimum permissible game is given when an even smaller game would result in a significant increase in rolling friction and consequent warming. The maximum permissible game is given when an even larger game would not allow safe guidance of the ball. In a rolling bearing according to the invention, these limits must not necessarily be exploited for the design of the game. The rolling bearing according to the invention can be designed so that the dimensions of the game are significantly larger than the minimum allowable game and clearly leu less than the maximum allowable game. The ratio between the smallest and the largest measure of the game, for example, be from twice to a hundred times. This relation must be adapted to the rolling bearing and its operating parameters.

The above example list of radii of the pockets 02 it can be seen that the third pocket 07 and the sixth pocket 02; the first pocket 04 and the fourth pocket 02 as well as the second pocket 06 and the fifth pocket see each are the same size. The same size pockets 02 should not be arranged side by side and not opposite each other. A majority of five of the eight pockets 02, which is formed for example by the first, second, third, seventh and eighth pockets 02, has no pocket 02, in which the game is the same size as the game another pocket 02 this majority executed , The aforementioned matches do not lead to a regular excitement of the cage 01 and thus to an increased noise development. The number of matches and the value range for the dimensions of the game are to be selected according to the rolling bearing and its operating behavior. For example, for a rolling bearing with an intensive

Lubrication and low rotational speeds several matches and a small range of values for the dimensions of the game are chosen as a sol-

^'Che roller bearing is less liable to change in a state of noisy operation. By contrast, the dimensions of the play in the pockets 02 of a rolling bearing with very high speeds are significantly more irregular and can be selected in a larger value range.

LIST OF REFERENCE NUMBERS

01 cage

02 bag 03 rivet hole

04 first bag

05 -

06 second bag

07 third bag 08 eighth bag

Claims

claims

1. rolling bearing with a cage (01) with at least a first group of guide pockets (02, 04, 06, 07, 08), in which rolling elements are guided with play, characterized in that the play at least in a first guide pocket (04) the first group is designed differently than the game in a second management pocket (06) of this first group of leadership pockets.

2. Rolling bearing according to claim 1, characterized in that all belonging to a group of guide pockets (02) rolling elements are formed the same.

3. Rolling bearing according to claim 1 or 2, characterized in that for a majority of the guide pockets (02) in the first group applies that none of the guide pockets (02) of this majority has the same game as another guide pocket (02) of this majority.

4. Rolling bearing according to one of claims 1 to 3, characterized in that all guide pockets (02) of the first group match in shape and the different game results from different dimensions.

5. Rolling bearing according to claim 4, characterized in that all rolling elements are designed as balls and the Fϋhrungstaschen (02) have a dome shape, wherein the game between balls and cage is defined by a radius of the dome shape.

6. Rolling bearing according to claim 5, characterized in that the radii of the dome shape of the guide pockets (02) have a value in the interval between 0.8 times and 1, 2 times an average radius measure, wherein the largest radius at least the 1st , 1 times the smallest radius.

7. Rolling bearing according to one of claims 1 to 6, characterized in that the cage (01) comprises a plurality of groups of guide pockets (02).

8. Rolling bearing according to one of claims 1 to 7, characterized in that the cage (01) is formed in one or more parts, in particular consists of two complementary cage halves, which are connected at connection points between the individual guide pockets (02) with connecting means.

9. Rolling bearing according to claim 8, characterized in that the cage consists of sheet metal, plastic, brass or hard tissue.

10. Rolling bearing according to at least one of the preceding claims, characterized in that at least two to a group of guide pockets (02) associated rolling elements are designed differently, in particular have different dimensions.

11. Rolling bearing according to at least one of the preceding claims, characterized in that the rolling bearing is a ball bearing and the associated rolling elements are formed as balls.