DE102005058149A1 - Tapered roller bearings with curved raceways - Google Patents

Abstract

Rolling bearing with an inner ring (2), an outer ring (3) and a plurality of rolling elements (5) arranged between the inner ring (2) and the outer ring (3) and having predetermined rolling element surfaces (11), the inner ring having a frustoconical outer surface (7) which is inclined by a predetermined angle (alpha) with respect to a geometrical longitudinal direction (L) of the rolling body, and the outer ring has a frustoconical inner surface (8). According to the invention, at least one surface (7, 8, 11) has a curvature at least in sections.

Description

Territory of invention

The The present invention relates to a rolling bearing, and more particularly Roller bearing, which has an inner ring with an oblique track. such roller bearing are known in the art as tapered roller bearings and have an inner ring with one opposite a bearing axis inclined career on. To the inner ring is a outer ring arranged and between the inner ring and the outer ring a plurality of rolling elements. Also the outer ring indicates in the known from the prior art embodiments an inclined career on.

at such camps with oblique Runways can be extended by existing intersection errors Wälzkörpermantellinie on the one hand and the bearing center line on the other hand kinematically caused a unwanted sliding friction arise.

Of the The present invention is therefore the object of this unwanted increased To prevent or at least reduce sliding friction.

This is inventively achieved the subject matter of claim 1. Advantageous embodiments and further developments are the subject of the dependent claims. It However, it should be noted that not all the objects of the invention achieved in the same way by the objects of all subclaims become.

The Rolling bearing according to the invention has an inner ring, an outer ring and a plurality of arranged between the inner ring and the outer ring rolling elements with predetermined rolling body surfaces. Of the Inner ring has a frusto-conical outer surface, opposite to a geometric longitudinal direction of the rolling bearing is inclined at a predetermined angle. Also the outer ring has a frustoconical inner surface on. This is also a predetermined angle to the longitudinal direction inclined. According to the invention extends at least one surface d. H. at least the rolling element surface, the Outside surface of the Inner ring or the inner surface of the outer ring in the geometric longitudinal direction curved at least in sections.

Under a curved one Course or a curvature longitudinal of the warehouse is understood that the surface in question is not curved only in the circumferential direction is, but also in the longitudinal direction, d. H. has a curvature in the direction of its generatrix. Through this curvature is achieved that at a load-related Lagerverkippung the bearing length the roles can be better adapted to the respective career contours. Also the course of the surface at the predetermined angle to the longitudinal direction is called course longitudinal Understood.

at a preferred embodiment are at least two surfaces in the longitudinal direction at least curved in sections.

Preferably these are two surfaces, at least temporarily in contact with each other, for example, the mantle surface of the Rolling elements on the one hand and, on the other hand, either the inner surface of the outer ring or the outer surface of the outer ring The inner ring. In a further preferred embodiment, both the inner surface of the outer ring as well as the outer surface of the Inner ring as well as the surface at least one rolling element and prefers the surfaces all rolling elements at least in sections in the longitudinal direction curved. Through this adaptation of the surfaces can Join the rolling elements their movement optimally to the outer surface of the inner ring or the palm of the outer ring to adjust. As a result, sliding movements between the rolling elements or the outer ring reduces or prevents and thus the friction torque through the adapting contact area is reduced.

Preferably have the rolling elements in the Essentially cylindrical Take shape, and the lateral surface the rolling element runs in the longitudinal direction curved at least in sections. Particularly preferred runs at least one of said surfaces d. H. the inner surface of the outer ring, the outer surface of the Inner ring and / or the lateral surface the rolling elements convexly curved.

there becomes the convex curvature the respective contact surface in relation to the respective body self-understood.

This convex course leads To ensure that in load-free operation, the contact between the rolling elements on the one hand and the inner and outer surfaces, respectively takes place in a central area of the surfaces. With others Words are the curvatures designed so that the distance between the rolling elements and the inner or outer ring minimal in a central region of the rolling element is increased and in the respective peripheral areas.

In a further preferred embodiment, the inner surface of the outer ring and the outer surface of the inner ring are at least partially substantially parallel to each other. By this embodiment it is achieved that in the longitudinal direction of the bearing, the distance between the inner ring and the outer ring remains substantially constant. As a result, such rolling elements can be used as rolling elements which have a substantially constant diameter in the longitudinal direction. In contrast, in the prior art rolling elements are used which have a frusto-conical outer profile.

This in turn leads to that in the prior art on the inner or outer ring and usually on the inner ring shelves must be provided on which start the rolling elements. this leads to in the prior art to a friction between the rolling elements and one of the bearing rings and thus increased wear.

By the preferred embodiment with the same angles of inclination, the said retaining boards can on the inside or on the outer ring omitted. The driveline is eliminated. In addition, by eliminating the retaining rims an improved lubricant supply possible on both tracks, since an unimpeded flow of the lubricant is made possible.

By the interaction of the same angle of inclination of the outer surface of the Inner ring and the inner surface of the outer ring on the one hand and the curved ones on the other surfaces On the other hand, overall a reduced susceptibility to seizing becomes of the rolling bearing reached.

Under one parallel to the outer surface frustoconical inner surface It is understood that this surface is essentially the same Taper angle has as the frusto-conical outer surface of the inner ring. Between the frustoconical inner surface of the outer ring and the frustoconical Outside surface of the Inner ring, the rolling elements are arranged. Because the mentioned inner and outer surfaces are parallel are to each other, the rolling elements are not, As in the prior art, executed truncated, but can as cylindrical body with in the longitudinal direction be performed substantially constant diameters.

Preferably is the angle to which the frusto-conical outer surface of the inner ring relative to the longitudinal direction of the rolling bearing is inclined between 2 ° and 50 ° and preferably between 5 ° and 30 °. This Angle range has proven to be particularly favorable in optimizing the friction conditions exposed.

at a further preferred embodiment has the rolling bearing a cage on, in which arranged the rolling elements are. More specifically, preferably, the cage has two shelves and a plurality of webs, whereby pockets are formed, in which arranged the rolling elements are. Preferably, the individual webs of the cage are also opposite to the given angle the longitudinal direction of the rolling bearing inclined.

By the use of a cage as a spacer between the rolling elements, the rolling bearing or tapered roller bearings in comparison to the known in the art tapered roller bearings designed as a bordless warehouse become. In the tapered roller bearing according to the invention are the at a relative displacement of inner to outer ring, for example, a tilt, resulting radial and axial forces of the raceways of the rolling elements and the used cage added.

at a further preferred embodiment is at least one rolling element than Needle roller executed. All rolling elements are preferred as needle rollers executed. Due to the omission of the retaining rims frontal of the rolling elements no longer have to transmit forces become. For this reason, can in the rolling bearing according to the invention Needle rollers are used.

Preferably is the relationship between the diameter of the needle rollers and the length of the needle rollers between 1: 1.5 and 1:20 and preferably between 1: 2 and 1:10. This Size ratio of the needle rollers has also proved to be particularly favorable for minimizing friction proved.

alternative to needle rollers can as a rolling element as well Cylindrical rollers are used. Preferably, a plurality used by cylindrical rollers. Preferably, the rolling bearing either uniform with cylindrical rollers or uniform with needle rollers stocked. Preferably, the ratio is between the diameter of the cylindrical rollers and the length of the Cylindrical rollers between 1: 0.8 and 1: 4 and preferably between 1: 1 and 1: 2.5. Also these proportions the cylindrical rollers, which the overall geometry of the cylindrical rollers determine, have proved particularly favorable to the friction to minimize.

In a further preferred embodiment have the rolling elements at least an unprocessed face on. Preferably, both end faces of at least one rolling element and preferably unprocessed of all rolling elements. As mentioned above, it is possible with the rolling elements according to the invention, on to abandon an on-board start with the inner or outer ring. In order to it is also possible Rolling elements with use unprocessed faces. This way you can the production costs for the tapered roller bearings according to the invention be lowered.

at a further preferred embodiment the width of the inner ring is at least as large as the length of the rolling elements. In this embodiment can longitudinal of the bearing the rolling elements in Essentially complete covered by the inner ring and thus completely between the inner ring and the outer ring be recorded.

Preferably is the height of the rolling bearing greater than the sum of the width of the inner ring and the product of the Diameter of the rolling element and the sine of the given angle. Below the height of the rolling bearing becomes the length of the complete roller bearing considering both the inner ring and the outer ring and the rolling elements in Longitudinal direction of the Stock understood. By the product of the diameter of the rolling element and the sine of the given angle is set at the same time the offset, the outer ring across from having the inner ring. The height must be at least that big like the sum of this offset and the width of the inner ring.

In a further preferred embodiment has at least one rolling element longitudinal the rolling body tapering end portions.

Further Advantages and embodiments emerge from the attached Drawings. Show:

1 a tapered roller bearing according to the prior art;

2 an inventive tapered roller bearing;

3 a partial view of a rolling element;

4 a partial view of the rolling element 3 ,

5 a schematic representation of an inner ring;

6 a representation of the outer surface of the inner ring; and

7 a representation illustrating the curvature

1 shows a tapered roller bearing according to the prior art. This has an inner ring 2 on, its outer surface 7 is inclined at a predetermined angle relative to the longitudinal direction L of the rolling bearing. An outer ring 3 of the rolling body has an inner surface 8th on, which is also inclined by a further angle relative to the longitudinal direction L. This angle to the outside surface 7 of the inner ring 2 is inclined relative to the longitudinal direction and the one to which the inner surface 8th of the outer ring 3 are inclined, are different. For this reason, the distance between the outer surface changes 7 and the inner surface 8th in the longitudinal direction L of the rolling bearing. Therefore, the rolling element must 5 be formed with a frusto-conical mantle surface. This reverse leads to the fact that it is necessary, the inner ring 2 with Borden 2a and 2 B to provide to the Wälzköper 5 respectively. This leads to a ramp-up of the rolling elements and thus to additional unwanted friction losses.

2 shows an inventive tapered roller bearing 1 , This bearing also has an inner ring 2 and an outer ring 3 on, between which the rolling elements 5 are arranged. The outer surface 7 of the inner ring 2 is inclined at a predetermined angle α with respect to the longitudinal direction L. The inner surface 8th of the outer ring 3 is also inclined at the same angle α with respect to the longitudinal direction L of the bearing. When considering these angles, any slight curvatures of the surfaces remain 7 . 8th In the determination of the angle α, a central region of the rolling bodies is considered, in which the latter is located at the in 2 embodiment shown is substantially planar.

By the same inclinations α of the inner surface 8th and the outer surface 7 is it possible that the rolling elements 5 be performed with a substantial constant diameter Dw. The reference number 4 refers to a cage through which the individual rolling elements 5 kept apart from each other. The reference numerals 12 refer to the guide lugs on the respective webs 4a the cages are attached. As in 2 shown is the bridge of the cage 4 also by the angle α with respect to the longitudinal direction L of the rolling bearing 1 inclined.

The reference number 9 refers to a projection or collar on the bearing cage 4 is arranged. This here in the circumferential direction outwardly facing collar 9 prevents falling apart of the tapered roller bearing, for example during assembly. At the in 2 In the embodiment shown, the webs extend 4a the bearing cages below the center line or axis of rotation of the rolling elements. In this embodiment, so that the rolling elements on the outer ring 3 held. The collar 9 is preferably in positive connection with the outer ring 3 ,

Through the collar 9 will prevent that the cage 4 with the rolling elements in 2 can be pulled out to the right. Without the collar could the cage 4 and the rolling elements are pulled off to the right and the rolling elements would be out of the through the webs 4a and slide out the rims of the cage formed pockets upwards. Pulling the cage to the left in 2 is also not possible because in such a movement, the rolling elements would be pushed deeper into the pockets and in this way the movement would be prevented.

Instead of the embodiment shown here are also further embodiments conceivable, such as those where the projection on the right side is arranged, projects radially inward and with the inner ring in form-fitting Connection stands. The cage shown here is preferably made of metal, but can be made of plastic.

The inner ring width IB is preferably greater than the length Lw of the rolling body 5 or this same. In this way, in essence, the complete surface or lateral surface of the rolling body 5 in contact with the outside surface 7 of the inner ring. The ratio between the diameter Dw of the rolling element and the length of the Lw rolling element is in the 2 embodiment shown preferably between 0.1 and 1. For the overall height BH of the bearing, the following relationship applies: BH ≥ Dw · sin (α) + IB, where IB is also the inner ring width here. The product of the rolling element diameter Dw and the sine of the angle α determines the displacement x between the inner ring 2 and the outer ring 3 occurs.

3 shows a detailed representation of a rolling body. This rolling element 5 has a lateral surface 14 on. This lateral surface has the convex curved course described above. However, towards the end regions, the diameter Dw of the rolling element decreases, whereby a logarithmic relationship is preferred for this decrease. This course of the diameter prevents increased radial bearing wear from occurring as a result of radial loads occurring. Instead of a logarithmic decrease, a linear decrease of the diameter would also be possible. Also, other functional relationships would be possible for the decrease in diameter, such as those relationships that are composed of a linear and a logarithmic portion.

At the left and right ends of the rolling elements each have a bevel 15 on. At the in 3 In the embodiment shown, the chamfer runs 15 at an angle between 30 and 60 degrees and preferably between 40 and 50 degrees with respect to the longitudinal direction L.

4 shows a partial view of the end portion of a rolling body 5 , It can be seen that the diameter of the rolling element to the outside initially slightly and then in the end 15 relatively steeply decreasing (logarithmic course). Preferably, the rolling element 15 at the in 4 shown embodiment on a reinforced end profiling.

The end areas 15 have curved surfaces. This also strong wear of the bearing should be prevented by one-sided loads. The radius of curvature R of these curvatures is preferably less than 1 mm.

5 shows a schematic and highly simplified representation of an inner ring 2 , This is formed in the prior art frusto-conical shape, which is illustrated by the dashed line generatrix m. In the embodiment according to the invention, this surface line m is not rectilinear but curved, more specifically convexly curved outward. The course of this curvature is in 5 exaggerated.

6 shows a representation of the outer surface 7 of the inner ring. This shows the lower part of 6 the area of the surface in the upper part of the image through the line 7 is shown. In this figure, reference character X refers to the longitudinal direction of the rolling element and reference character Y to a direction perpendicular thereto. It can be seen that the inner ring or its outer surface 7 has a convex profile ie its diameter is increased in the central region. The diameter of the inner ring increases towards the sides 2 each preferably from logarithmically.

As mentioned above, occur in tapered roller bearings intersection error between the extension of the generatrix of the rolling element and the extension of the center line of the bearing. This intersection error leads to increased sliding friction and between the inner and Au ßenringflächen and the lateral surface of the rolling element. By the in 6 shown profiling or design of the contacting Wälzkörperoberflächen and the surfaces 7 . 8th the outer and inner rings can be optimally adapted to the respective raceway contours at a load-related Lagerverkippung the bearing length of the rolling elements. The edge run of the rolling elements occurring in the prior art is prevented by this design of the outer surfaces and in this way also sliding movements (which lead to wear) and the friction torque can be reduced by the adapting contact area.

7 shows an enlarged view of Illustration of the curvature. In this case, the left upper part of the image was stretched in the Y direction in order to illustrate the size relationships. Unlike the in 6 shown curvature was in 7 used a linear curvature. However, it would also be possible to provide on the outer surface of the inner ring a linearly extending curvature and on the inner surface of the outer ring a logarithmic curvature. Also, both the inner ring and the outer ring each logarithmic or linearly extending curvatures may be provided.

The reference number 8th refers to the surface of the outer ring or its course. You realize that this surface 8th along the midline M furthest in 7 protrudes downwards.

The reference h refers to the distance hereinafter referred to as bale height, which is a measure of the curvature of the surface. By definition, this is the distance that the point X1 and the point X2 are both on the surface 8th are in, Y-direction to each other. In the X direction, the two points X1 and X2 are spaced apart by 0.3 times the total longitudinal extent X of the outer ring.

In complex Experiments became a particularly suitable bale height for different outer diameter of the rolling bearing determined. For small outside diameters in the range between 0 and 90 mm has a bale height between 0 and 2 μm turned out to be particularly suitable. For outside diameters between 90 and 240 mm lies the bale height advantageous in the range between 0 and 3 microns. For outside diameter between 240 and 60 mm gives a bale height in the range of 4 microns and for large outer diameter of more than 600 mm, the bale height is preferably between 0 and 6 μm.

For the tapered roller bearing according to the invention alternatively metal or plastic cages are used. These can be special have matched geometries that control the flow of oil through the bearing improve and also reduce the friction between the cage and the rolling elements.

Also, the rolling element, not shown, preferably has a like in the 5 and 6 shown curvature.

All Features disclosed in the application documents are considered to be essential to the invention as long as they are individually or in combination with respect to State of the art are new.

1

Tapered roller bearings

2

inner ring

2a, 2 B

shelf of the inner ring (prior art)

3

outer ring

4

bearing cage

4a

Footbridge of the camp cage 4

5

rolling elements

7

Outer surface of the inner ring 2

8th

Inner surface of the outer ring 3

9

collar

12

guide nose

13

in the longitudinal outer region of the rolling body 5

14

Lateral surface of the rolling element 5

15

End of the rolling element 5

15a

curved surface of the end region

dw

Diameter of the rolling element 5

IB

Width of the inner ring 2

lw

Length of the rolling element 5

bra

Height of the rolling bearing

α

tilt angle the rolling elements

L

longitudinal direction of the rolling bearing

R

radius of curvature

H

ball height

m

surface line of the inner ring

Claims (16)

Rolling bearings with an inner ring ( 2 ), an outer ring ( 3 ) and a plurality of between the inner ring ( 2 ) and the outer ring ( 3 ) arranged rolling elements ( 5 ) with predetermined rolling body surfaces ( 14 ), wherein the inner ring has a frustoconical outer surface ( 7 ) which is inclined relative to a geometric longitudinal direction (L) of the rolling bearing by a predetermined angle (α) and the outer ring has a frusto-conical inner surface ( 8th ), characterized in that at least one surface ( 7 . 8th . 14 ) is curved at least in sections in the longitudinal direction (L). Rolling bearing according to claim 1, characterized in that the inner surface ( 8th ) of the outer ring ( 3 ) and the outer surface ( 7 ) of the inner ring ( 2 ) are at least partially substantially parallel to each other. Rolling bearing according to at least one of the preceding claims, characterized in that at least two of the surfaces ( 7 . 8th . 14 ) are curved at least in sections in the longitudinal direction (L). Rolling bearing according to at least one of the preceding claims, characterized in that both the inner surface ( 8th ) of the outer ring ( 2 ) as well as the outer surface ( 7 ) of the inner ring ( 3 ) As well as the outer surface of at least one rolling element in the longitudinal direction are at least partially curved. roller bearing according to at least one of the preceding claims, characterized in that the rolling elements a essentially cylindrical Have shape and the lateral surface of the rolling elements in the longitudinal direction (L) is curved at least in sections. Rolling bearing according to at least one of the preceding claims, characterized in that at least one surface ( 7 . 8th . 14 ) is convexly curved. roller bearing according to at least one of the preceding claims, characterized in that the predetermined angle (α) between 2 ° and 50 ° and preferred between 5 ° and 30 °. Rolling bearing according to at least one of the preceding claims, characterized in that the rolling bearing a cage ( 4 ), in which the rolling elements ( 5 ) are arranged. Rolling bearing according to at least one of the preceding claims, characterized in that at least one rolling element ( 5 ) is a needle roller. roller bearing according to claim 9, characterized in that the ratio between the diameter (Dw) of the needle rollers and the length of the needle rollers (Lw) between 1: 1.5 and 1:20 and preferably between 1: 2 and 1:10. Rolling bearing according to at least one of the preceding claims, characterized in that at least one rolling element ( 5 ) is a cylindrical roller. roller bearing according to claim 11, characterized in that the ratio between the diameter (Dw) of the cylindrical rollers and the length (Lw) the cylindrical rollers between 1: 0.8 and 1: 4 and preferably between 1: 1 and 1: 2.5. Rolling bearing according to one of the preceding claims, characterized in that the rolling bodies ( 5 ) at least one unprocessed end face ( 15 ) exhibit. roller bearing according to at least one of the preceding claims, characterized in that that the width (IB) of the inner ring is at least as large as the length (Lw) of the rolling elements. roller bearing according to at least one of the preceding claims, characterized in that the height (BH) of the rolling bearing is larger as the sum of the width (IB) of the inner ring and the product from the diameter (DW) of the rolling element and the sine of the given angle (α). Rolling bearing according to at least one of the preceding claims, characterized in that the at least one rolling element ( 5 ) in the longitudinal direction of the rolling body ( 5 ) has tapered end portions.