Pivot bearing

A pivot bearing arrangement, in particular a pivot bearing for a front wheel suspension system of a motorcycle, is provided that substantially reduces bearing breakaway torque, temperature sensitivity, complexity, space requirements and cost. The pivot bearing arrangement includes a first bearing part which enables a component to pivot about a first pivot axis, and a second bearing part which enables a component to pivot about a second pivot axis. The two bearing parts are connected to each other and form a structural unit.

BACKGROUND AND SUMMARY OF THE INVENTION

The invention relates to a pivot bearing, in particular for a front wheel suspension system of a motorcycle. The invention furthermore relates to a front wheel suspension system for a motorcycle with such a pivot bearing.

A front wheel suspension system for BMW motorcycles, which has two trailing links arranged one above the other and in each case mounted pivotably on the frame or on the engine housing, is known under the designation “duo lever”. The front ends of the trailing links are in each case connected via a ball and socket joint to a fork like wheel carrier which—in contrast to the classic design with two sliding and fixed tubes in each case—is formed as a single part. The suspension and damping are undertaken by a suspension strut which is coupled to the lower of the two trailing links and is supported against the frame. The steering movements triggered by the rider are transmitted to the wheel carrier via a trapezoidal shear joint mounted on the steering head and wheel carrier.

It has already been recognized that ball and socket joints have to overcome a breakaway torque for the transition from static friction into sliding friction. In the case of the previously described “duo lever” front wheel suspension system, this relates to the movement of the wheel carrier and to the steering from a rest position.

As a solution to this problem, it is proposed in International patent document no. WO 2007/131590 A1 not to connect the front ends of the trailing links to the wheel carrier by spherical bearings but rather via pivot bearings in the form of rolling contact bearings, the pivot axes of which run transversely with respect to the longitudinal direction of the motorcycle. Said pivot bearings permit spring movements of the wheel carrier relative to the frame of the motorcycle. The further degree of pivoting freedom required for the steerability of the wheel carrier is achieved by a tube which extends between two transverse connecting elements (fork stabilizers) which connect the fork struts of the wheel carrier. The ends of the tube are each connected to the connecting elements via a pivot bearing. These two steering bearings are also formed by rolling contact bearings, and therefore breakaway torques are very substantially avoided even during the steering of the wheel carrier.

The combination of a plurality of standard rolling contact bearings for providing the required degrees of freedom for the suspension and the steerability of the wheel carrier according to International patent document no. WO 2007/131590 A1, however, requires a large amount of construction space. Further disadvantages are the high weight and the outlay on assembly.

It is an object of the invention to avoid these disadvantages and to permit a compact mounting which is simple to fit and has a plurality of degrees of freedom.

This object is achieved by a pivot bearing, which is provided in particular for a front wheel suspension system of a motorcycle, having a first bearing part which permits a component to pivot about a first pivot axis. The pivot bearing furthermore includes a second bearing part which permits a component to pivot about a second pivot axis, wherein the two pivot axes intersect. The two bearing parts are connected to each other and form a structural unit.

The invention is based on the finding that a combined pivot bearing with intersected pivot axes permits all movements which are required in the suspension and in the steering of the wheel carrier.

Owing to the combining of the two bearing parts to form a structural unit, the pivot bearing according to the invention is easier to handle and also affords logistical advantages in respect of storage and transport.

The pivot bearing according to the invention is suitable in particular for the front wheel suspension system of a motorcycle, particularly for the mounting of the wheel carrier. However, other use possibilities in which pivoting movements having a plurality of degrees of freedom are required are also possible.

According to the preferred embodiment of the invention, the first bearing part and/or the second bearing part have/has at least one rolling contact bearing, in particular a tapered roller bearing. With this bearing arrangement, the substantial problems associated with a ball and socket joint are overcome. In this connection, the breakaway torque which is virtually no longer present (considerably reduced static and also sliding friction) and the significantly lower temperature sensitivity (specifically in the vicinity of the engine) no longer stand in the way of use in chassis and steering system.

A configuration in which two tapered roller bearings which are inclined in relation to each other are fitted in the first bearing part and/or in the second bearing part, in particular in an O arrangement, has proved to be particularly advantageous. This configuration makes it possible to absorb radial and axial loads acting simultaneously (“combined loads”).

In the preferred configuration of the pivot bearing according to the invention, the first bearing part has a bearing housing in which a pin is rotatably mounted, and the second bearing part has an outer bearing shell in which a clamping bushing is rotatably mounted, wherein the bearing shell is formed in the pin or by the pin itself. The bearing housing is mounted fixedly in the installed state of the pivot bearing. The particular configuration with the pin which is rotatable in the bearing housing and the clamping bushing which is in turn rotatable in the pin permits a light and compact design of the pivot bearing with few components and which also requires little construction space.

So that the component to be coupled to the pivot bearing according to the invention can be mounted as easily as possible in the clamping bushing, the clamping bushing is preferably arranged in a portion of the pin that protrudes out of the bearing housing, and is therefore easily accessible.

According to an advantageous aspect of the invention, a preferably cylindrical portion of the pin, which portion faces away from the clamping bushing, is hollow, and a free edge of said portion is flanged outward. The hollow design of the pin portion saves weight and facilitates the flanging of the free edge. The flanging itself is advantageously used for fastening an adjacent bearing component, in particular a bearing ring, to the pin. In this case, it is possible to dispense with nuts or screws which cause weight, construction space and costs and have to be secured against release. The flanging therefore permits a saving on weight, cost and construction space and, in addition, increases the functional reliability of the pivot bearing according to the invention.

As already mentioned, a bearing ring which surrounds that portion of the pin which faces away from the clamping bushing can be supported on the flanged edge of the pin, wherein the outside diameter of the bearing ring preferably increases in the direction of the flanged edge. Owing to the flanging, the bearing ring is held securely on the pin.

The bearing ring constitutes a preferably slightly beveled rolling surface for first rolling contact bodies of the first bearing part, which rolling contact bodies are arranged between the bearing housing, on the one hand, and the bearing ring, on the other hand.

An arrangement, which is matched thereto, of a further tapered roller bearing is achieved by a configuration in which the pin has an intermediate portion which faces the clamping bushing and the outside diameter of which preferably increases in the direction of the clamping bushing, wherein first rolling contact bodies of the first bearing part are arranged between said intermediate portion and the bearing housing.

In a particularly compact configuration of the pivot bearing according to the invention, the pin has a cavity into which the clamping bushing is fitted, wherein second rolling contact bodies of the second bearing part are arranged between a wall of the cavity and the clamping bushing.

For an obliquely inclined second tapered roller bearing, the second rolling contact bodies rest on at least one ring surface of the cavity wall, the center axis of which runs parallel to the second pivot axis, wherein the ring surface or the ring surfaces is or are inclined relative to the second pivot axis.

In the preferred embodiment of the pivot bearing, the second rolling contact bodies rest on at least one inner ring which is coupled to the clamping bushing for rotation therewith. The clamping bushing together with the inner ring forms the inner part of a rolling contact bearing, which inner part is rotatable relative to the outer bearing shell.

According to a particularly advantageous aspect of the invention, at least one free edge of the clamping bushing is flanged outward, and a respective inner ring is supported on the one or two flanged edges of the clamping bushing, the outside diameter of which inner ring preferably increasing in the direction of the associated free edge of the clamping bushing. The hollow clamping bushing makes it possible in a simple manner to accommodate a component to be mounted, wherein the flanging can advantageously be used for fastening at least one inner ring to the clamping bushing. Owing to the flanging, the inner ring is held securely on the clamping bushing. In this case, it is possible to dispense with nuts or screws which cause weight, construction space and costs and have to be secured against release. The flanging therefore provides a saving on weight, cost and construction space and, in addition, increases the functional reliability of the pivot bearing according to the invention. The frustoconical shape of the inner ring is of importance for the configuration as an obliquely inclined tapered roller bearing.

In order to permit or at least to support a defined axial prestressing of the second rolling contact bodies, according to a development of the invention a spacer ring which surrounds the clamping bushing is arranged between the two inner rings.

The invention also provides a front wheel suspension system for a motorcycle, comprising a wheel carrier and trailing links or transverse links which connect the wheel carrier to a supporting component of the motorcycle, in particular to a motorcycle frame or an engine housing. The trailing links or transverse links are in each case connected by a pivot bearing of the type described previously to the wheel carrier.

Furthermore, the invention provides a front wheel suspension system for a motorcycle, comprising a wheel carrier in the form of a telescopic fork. At least one bearing point between a supporting component of the motorcycle, in particular a motorcycle frame or an engine housing, and the wheel carrier is formed by a pivot bearing of the type described previously.

With regard to the advantages of the front wheel suspension systems according to the invention, reference is made to the statements above regarding the advantages of the pivot bearing according to the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1illustrates a known motorcycle front wheel suspension system of the “duo lever” type. A wheel carrier10, which is formed here as a single-part wheel carrier in the form of a casting with a central suspension strut (not shown here) for suspension, is mounted on the motorcycle frame and/or on the engine housing of the motorcycle by a lower trailing link12and an upper trailing link14, wherein the front ends of the trailing links12,14are connected to the wheel carrier10via ball and socket joints16.

The prior art front wheel suspension system shown inFIGS. 2 and 3has a fork-like wheel carrier10′ with a lower fork stabilizer18and an upper fork stabilizer20, which connect together two fork arms22, of which only the left one is shown here. As in the previously described embodiment, the wheel carrier10′ is mounted on the motorcycle frame by a lower trailing link12and an upper trailing link14. Each of the two trailing links12,14has a left trailing link arm12aand14a, respectively, and a right trailing link arm12band14b, respectively, of which only the left in each case can be seen inFIG. 2.

A head tube24extends between the lower fork stabilizer18and the upper fork stabilizer20. A lower end of the head tube24is connected to the lower fork stabilizer18via a first rolling contact bearing26. In a corresponding manner, an upper end of the head tube24is connected to the upper fork stabilizer20via a second rolling contact bearing28. The first and second rolling contact bearings26,28are arranged coaxially and serve as steering bearings. Front ends of the trailing link arms12a,12band14a,14bare connected in an articulated manner to the head tube in each case via a lower, third rolling contact bearing30and an upper, fourth rolling contact bearing32. The third and fourth rolling contact bearings30,32permit spring movements of the wheel carrier10′ with respect to the frame of the motorcycle.

A pivot bearing according to the invention which can replace a respective ball and socket joint16or in each case two lower rolling contact bearings26and30or two upper rolling contact bearings28and32in the previously described front wheel suspension systems, will now be described below.

The pivot bearing34shown inFIGS. 4 to 6is a combined pivot bearing with a first bearing part36and a second bearing part38. For the sake of simplicity, the pivot bearing34is illustrated without any sealing.

The first bearing part36comprises a bearing housing40with a substantially cylindrical housing portion42and a radially protruding collar44, which are provided for the fixed installation of the first bearing part36.

A pin46which is generally rotationally symmetrical with respect to the center axis M1thereof is accommodated centrally in the bearing housing40. The pin46has a cylindrical lower portion48which merges into an intermediate portion50, which widens continuously in diameter. The intermediate portion50is adjoined by an upper pin portion52which is, in turn, substantially cylindrical.

The lower portion48of the pin46has a free edge54and can be of hollow design for weight reasons and in order to facilitate flanging of the free edge54. The lower end of the pin46is surrounded by a bearing ring58, the outside diameter of which is reduced upward. The bearing ring58therefore has a frustoconical shape. The free lower edge54of the pin46is flanged outward, and therefore the bearing ring58is held fixedly on the pin46. Further fastening for holding the bearing ring58on the pin46is not provided at this point.

The shape of the bearing housing40is matched to the geometry of the bearing ring58and of the intermediate portion50of the pin46. A plurality of first rolling contact bodies56in the form of frustoconical or cylindrical rollers are arranged distributed over the circumference between the bearing ring58and the bearing housing portion opposite the latter, and also between the intermediate portion50of the pin46and the bearing housing portion opposite the latter. The rotation axes of the first rolling contact bodies56are inclined in relation to the center axis M1of the pin46.

This construction of the first bearing part36corresponds to that of two tapered roller bearings which are inclined in relation to each other, are mounted in an O-arrangement and permit the pin46(including the bearing ring58) to rotate about the center axis M1of the pin46relative to the bearing housing40. The axis M1therefore constitutes the pivot axis of the first bearing part36.

The second bearing part38is formed in the upper pin portion52and comprises a clamping bushing60which is mounted therein so as to be rotatable about the center axis M2thereof and serves for accommodating a component which is to be mounted. For this purpose, the upper pin portion52is provided with a cavity which extends completely through the upper pin portion52transversely with respect to the axis M1. The clamping bushing60which, together with two inner rings62, forms the internal part of a rolling contact bearing, is fitted into the cavity.

In order to hold the two inner rings62fixedly on the clamping bushing60, the edges64of the free ends of the clamping bushing60are flanged outward. Further fastening for holding the inner rings62on the clamping bushing60is not provided at this point.

The outside diameter of the two axially spaced-apart inner rings62decreases from the outside inward, and therefore the two inner rings62, in a similar manner to the bearing ring58of the first bearing part36, have a frustoconical shape.

The cavity in the upper pin portion52has two ring surfaces66which lie opposite the inner rings62and are coordinated therewith. The center axis of the ring surfaces66is parallel to the center axis M1of the pin46, in more precise terms, coincides therewith. The ring surfaces66are inclined with respect to the axis M2, wherein the distance of the ring surfaces66from the axis M2increases in each case in the direction of the flanged edges64of the clamping bushing60.

Second rolling contact bodies68in the form of frustoconical or cylindrical rollers rest on the inner rings62in a manner distributed over the circumference and are supported against the ring surfaces66of the pin46. The rotation axes of the second rolling contact bodies68are in turn inclined in relation to the center axis M2of the clamping bushing60.

The construction of the second bearing part38therefore likewise corresponds to that of two tapered roller bearings which are inclined in relation to each other and are mounted in an O-arrangement. Owing to the second rolling contact bodies68, the clamping bushing60(including the inner rings62) can rotate about the center axis M2thereof relative to the pin46of the first bearing part36, which pin serves as the outer bearing shell. The axis M2therefore constitutes the pivot axis of the second bearing part38.

The outer bearing shell of the second bearing part38is formed by the pin46, in more precise terms by the upper pin portion52, of the first bearing part36, and therefore a structural unit of the two bearing parts36,38is produced.

As can be seen inFIG. 6, the pivot axes M1and M2of the two bearing parts36,38intersect at right angles.

FIG. 7shows a variant of the pivot bearing34according to the invention. A spacer ring70surrounding the clamping bushing60is arranged in the second bearing part38between the two inner rings62. The spacer ring70maintains the axial prestressing of the second rolling contact bodies68irrespective of the tension force of the flanging and the tension force of the fastening elements.

The location at which the ball and socket joints16are arranged inFIG. 1, i.e. between wheel carrier10and trailing or transverse links12,14, is provided as the installation site for the combined pivot bearing34. The pivot bearing34therefore connects wheel carrier10and trailing or transverse links12,14and permits both wheel travel movements and steering movements in a single-part wheel carrier which is designed, for example, in the form of a casting with a suspension strut.

The combined pivot bearing34can also be used in the case of two-wheeled vehicles having a conventional telescopic fork with two fixed and two sliding tubes. Said pivot bearing then replaces the upper or lower bearing in the steering head. The otherwise customary adjustment of the steering head bearings is therefore omitted.

The combined pivot bearing34can be used in the same manner in the steering linkage72of a front wheel suspension system (seeFIG. 1).

In principle, the pivot bearing34according to the invention can be used wherever a pivoting movement with a plurality of degrees of freedom is required.

LIST OF REFERENCE NUMBERS

10,10′ Wheel carrier12Lower trailing link12aLeft trailing link arm of the lower trailing link12bRight trailing link arm of the lower trailing link14Upper trailing link14aLeft trailing link arm of the upper trailing link14bRight trailing link arm of the upper trailing link16Ball and socket joint18Lower fork stabilizer20Upper fork stabilizer22Fork arm24Head tube26First rolling contact bearing28Second rolling contact bearing30Third rolling contact bearing32Fourth rolling contact bearing34Pivot bearing36First bearing part38Second bearing part40Bearing housing42Cylindrical housing portion44Collar46Pin48Lower pin portion50Intermediate portion52Upper pin portion54Lower edge of the pin56Bearing ring58First rolling contact body60Clamping bushing62Inner ring64Free edge of the clamping bushing66Ring surface68Second rolling contact body70Spacer ring72Steering linkage