Spacer for a roller bearing and roller bearings with such a spacer

Abstract

Spacer (1) for a roller bearing, in particular a crossed roller bearing, with two opposing, away from each other contact surfaces (2.1, 2.2) for adjacent cylindrical rolling elements (8) of the roller bearing, characterized by the fact that a first of the two contact surfaces (2.1) is formed by a concave, simply curved cylindrical surface and a second of the two contact surfaces (2.2) is formed by a saddle surface with a concave and a convex curvature.

Description

[0001] The present invention relates to a spacer for a roller bearing, in particular a crossed roller bearing, according to the preamble of claim 1, and to a roller bearing with such a spacer.

[0002] Spacers are inserted into roller bearings between two adjacent cylindrical or cylindrical rolling elements, so that the rolling elements bear against the spacers and are thus held at a defined distance from each other. The spacers therefore function as a cage.

[0003] The spacers have two opposing, diverging contact surfaces for the adjacent cylindrical rolling elements (cylindrical rollers). The shape of the contact between the rolling elements and the contact surfaces affects the load-bearing capacity and thus the load-bearing capacity and service life of the roller bearing.

[0004] Conventional spacers in crossed roller bearings, where the central axes of the two adjacent rollers are perpendicular to each other when viewed circumferentially, have two concave, simply curved contact surfaces, i.e., cylindrical surfaces, which are largely complementary to the outer surface, i.e., the cylindrical surface, of the respective rolling element to which they face. The spacers are not adapted to the curvature of the bearing raceway, so ideal contact between the spacers and the rolling elements is not achieved. Particularly with small pitch circles, overlaps with the raceway can occur.

[0005] DE 10 2007 054 555 A1 therefore proposes to provide corresponding spacers with grooves in the concave, simply curved cylindrical surfaces forming the contact surfaces in order to achieve optimal line contact between the cylindrical rolling elements and the spacers on both contact surfaces and at the same time to ensure better wetting of the rolling elements with lubricant.

[0006] EP 0 764 791 A1 proposes spacers with simply curved cylindrical surfaces forming the two opposing contact surfaces. Furthermore, each contact surface can be formed by two intersecting simply curved cylindrical surfaces.

[0007] DE 10 2014 117 306 A1 proposes spacers with arc surfaces having different centers on both sides of the spacer.

[0008] To account for raceway curvature, DE 10 2011 003 947 A1 proposes wedge profiles as spacers, which are inserted between two adjacent rolling elements. The wedges can have recesses for accumulating lubricant.

[0009] EP 2 751 436 B1, in turn, reveals conventional concave, simply curved cylindrical surfaces on both sides of the spacer.

[0010] EP 2 623 805 A1 proposes a spacer with two saddle surfaces as contact surfaces.

[0011] For further information on the state of the art, reference is made to JP 2000-314 418 A, US 2014 / 0 016 890 A1 and US 3 517 975 A.

[0012] The present invention is based on the objective of providing, starting from the aforementioned prior art, a spacer that is particularly cost-effective to manufacture and easy to handle, which ensures an optimized fit or contact between the contact surfaces of the spacer and the rolling elements positioned adjacent to it.

[0013] The problem according to the invention is solved by a spacer having the features of claim 1. The dependent claims specify particularly advantageous and practical embodiments of the spacer as well as a roller bearing with spacers according to the invention.

[0014] A spacer according to the invention for a roller bearing, which is particularly suitable for a crossed roller bearing, but is also applicable in other roller bearings, for example in an axial roller bearing with two bearing rings positioned next to each other in the axial direction or in a radial roller bearing with two bearing rings positioned next to each other in the radial direction, has two opposing contact surfaces facing away from each other for cylindrical rolling elements of the roller bearing positioned adjacent to each other, namely a first contact surface formed by a concave, simply curved cylindrical surface, and a second contact surface formed by a saddle surface, i.e. a surface curved in opposite directions in the two main directions, i.e. anticlastically, for example a hyperbolic paraboloid.Preferably, the saddle surface is formed by a concave cylindrical surface in a first principal direction and a convexly curved surface in a second principal direction. The convexly curved surface in the second principal direction can be, for example, a convexly curved cylindrical surface or a hyperbolic surface.

[0015] Due to the shape of the contact surfaces according to the invention, on one side of the spacer with the concave cylindrical surface, line contact is created along one or more lines between the spacer and the rolling element bearing against it. On the opposite contact surface, however, point contact is created, in particular at one or more points, between the spacer and the rolling element bearing against it. In particular, on the first contact surface, line contact is created along exactly two, for example parallel, lines, and on the second contact surface, point contact is created at exactly two points.

[0016] This type of contact between the spacer and the rolling elements bearing against it allows for optimally defined load distribution, largely independent of the roller bearing diameter, i.e., with varying raceway curvatures or radii. The point contact on one side of the spacer allows it to tilt perpendicular to the radial direction of the roller bearing, ensuring the desired line contact on the other side.

[0017] Particularly advantageously, the cylindrical surface forming the first of the two contact surfaces has a first longitudinal axis of its concave curvature, and the saddle surface forming the second of the two contact surfaces has a second longitudinal axis of its concave curvature, the first longitudinal axis being skew to the second longitudinal axis. In particular, the first longitudinal axis is positioned rotated at least substantially by 90° relative to the second longitudinal axis, as viewed in a projection of the two contact surfaces onto each other, or in the circumferential direction of the roller bearing, in which the two contact surfaces are positioned one behind the other.

[0018] Preferably, the spacer is wedge-shaped, so that its shape is adapted to the raceway curvature or raceway radius of the rolling elements or the rolling bearing.

[0019] According to one embodiment of the invention, the two contact surfaces on opposite sides of the spacer are connected by an opening that leads into the spacer. This opening, which is designed, for example, as a bore (i.e., with a circular cross-section), but can also have another shape, extends from one contact surface to the other in the circumferential direction of the corresponding roller bearing. Through this opening or bore, lubricating grease can reach the outer surface of the rolling elements directly.

[0020] Preferably, the spacer has an outer circumference with four external surfaces via which the two contact surfaces are connected. It is advantageous if at least one, two, three, or all four external surfaces have a recess for storing lubricating grease and / or for guiding lubricating grease from the side of the first contact surface to the side of the second contact surface, or vice versa.

[0021] For example, in a top view of the first or second contact surface, the spacer has at least a substantially square shape, which, in the case of cutouts, may have concave sides or other sides deviating from a linear shape. In any case, with such a square shape, the outer surfaces each bridge the same distance in the circumferential direction of the spacer, which encloses the two contact surfaces in a top view.

[0022] To improve the handling of the spacer, for example when filling a roller bearing with rolling elements and the spacers, at least one gripping element can be provided on the outer circumference of each spacer for grasping it with a gripper, tweezers, or the like. For example, only a single gripping element may be provided, or a gripping element may be provided at each of two adjacent corners on the circumference of the spacer. Such targeted placement of gripping elements, rather than at all corners or outer surfaces, helps to prevent incorrect installation of the spacer in a roller bearing.

[0023] The spacer is made primarily of plastic.

[0024] A roller bearing according to the invention comprises two adjacent bearing rings and a plurality of cylindrical rolling elements, as well as spacers according to the invention between adjacent rolling elements. If the roller bearing is designed as a crossed roller bearing, an inner bearing ring and an outer bearing ring are provided accordingly, and the rolling elements are positioned one behind the other with their longitudinal axes alternately crossed in the circumferential direction between the inner bearing ring and the outer bearing ring.

[0025] As a rule, exactly one spacer, in particular a one-piece spacer, is provided between each pair of adjacent rolling elements, against which the rolling elements then rest at the two contact surfaces.

[0026] If the rolling elements are provided with the aforementioned opening and / or the recesses in the outer surfaces, or with at least one recess in an outer surface, a so-called snowplow effect in the roller bearing can be avoided. With such a snowplow effect, the spacers push lubricating grease ahead of them as the rollers or rolling elements roll along the raceways.

[0027] The rolling elements have a diameter between 8 and 15 mm, for example, and particularly between 10 and 12 mm. However, other diameters are also possible. Particularly with the aforementioned diameters, the radius of curvature of the concave areas of the contact surfaces is advantageously less than 6 mm, and particularly less than 5 mm. The radius of curvature of the convex area of ​​the saddle surface is particularly larger than the radius of curvature of the concave area and is, for example, more than 5 or 6 mm.

[0028] The opening can, for example, have a diameter or clear width of more than 1 mm, in particular from 1 mm to 2 mm. The side length of the spacer is, for example, between 9 and 12 mm, in particular between 9.5 and 11.5 mm.

[0029] The handle element, for example, has a thickness to be gripped of more than 1 mm, in particular of 1.4 to 1.6 mm.

[0030] The axis of rotation of a cylindrical roller bearing against the respective contact surface, which forms the rolling element, is in particular slightly offset from the center or the longitudinal axis of the concavely curved cylindrical surface or the concave curvature of the saddle surface.

[0031] The invention will be explained below by way of example using an embodiment and the figures.

[0032] They show: Fig. 1 An embodiment of a spacer according to the invention in a schematic three-dimensional view; Fig. 2 the spacer in a top view which contains several subsequent sections; Fig. 3 the spacer in a side view from the left; Fig. 4 the spacer in section view AA; Fig. 5 the spacer in section view BB; Fig. 6 the spacer in a rear view; Fig. 7 the spacer from the Fig. 1 in a schematic top view of one of the four outer surfaces with adjacent rolling elements; Fig. 8 Front view of a section with rolling elements and spacers according to the invention; Fig. 9 Top view of a section with rolling elements and spacers according to the invention; Fig. 10 Sectional view DD of a section with rolling elements and spacers according to the invention; Fig. 11 View of a section with rolling elements and spacers according to the state of the art; Fig. 12 a top view of a roller bearing with spacers according to the invention; Fig. 13 an axial section through the bearing rings of the roller bearing from the Fig. 4; Fig. 14 the roller bearing from the Fig. 4 with a breakout so that the inserted spacers and rolling elements are visible.

[0033] In the Fig. Figure 1 shows an embodiment of a spacer 1 according to the invention, which is intended for a crossed roller bearing and has two opposing contact surfaces 2.1 and 2.2 facing away from each other for cylindrical rolling elements of the roller bearing which are not shown in detail here and are positioned next to each other.

[0034] The first contact surface 2.1 is formed by a concave cylindrical surface, that is, by a surface simply curved concavely about the first longitudinal axis 3.1. The second contact surface 2.2 has the shape of a saddle surface, that is, a surface with a concave curvature about the second longitudinal axis 3.2 and a convex curvature about a longitudinal axis arranged perpendicular to it. Due to the second longitudinal axis 3.2 being oriented perpendicular to the first longitudinal axis 3.1 in a top view of the first contact surface 2.1, this second longitudinal axis 3.2 runs parallel to the first longitudinal axis 3.1.

[0035] The spacer 1 has four outer surfaces 4.1, 4.2, 4.3 and 4.4, which connect the contact surfaces 2.1 and 2.2 on the outer circumference of the spacer 1. In a top view of the first contact surface 2.1 or the second contact surface 2.2, the outer circumference of the spacer 1 is essentially square, whereby the contour lines of the spacer 1 connecting the four corners are not linear, but arcuate or arcuate with further cutouts, corresponding to the sides of the square.

[0036] Each of the four outer surfaces 4.1, 4.2, 4.3 and 4.4 has a recess 5 which forms a grease pocket to provide sufficient lubricating grease between the parts located in the Fig. 1. The spacer 1 is designed to store the grease on the rolling elements (not shown in detail). A bore 6 is provided in the center of the spacer 1, which connects the two contact surfaces 2.1 and 2.2, so that the grease can reach the outer surfaces or cylindrical surfaces of the rolling elements directly via the bore 6.

[0037] Furthermore, gripping elements 7 are provided at two corners of the spacer. These serve as assembly aids and can be easily grasped, for example with tweezers, to insert the spacer 1 through an opening for filling a roller bearing into the otherwise normally closed space between the two bearing rings, together with the rolling elements. Such an opening can be closed with a filling plug after filling. It is also possible that the space described as closed may have bores or openings for supplying or removing lubricating grease or oil.

[0038] The Fig. Figure 2 shows a spacer 1 according to the invention in a top view. The concavely curved cylindrical surface 2.1 is depicted. Recesses 5 are provided in all four outer surfaces, i.e., the first outer surface 4.1, the second outer surface 4.2, the third outer surface 4.3, and the fourth outer surface 4.4 of the spacer 1, to serve as lubricant reservoirs. Additionally, grip elements 7 are provided at two corners of the spacer to facilitate assembly. Two sections AA and BB are also shown in the top view; these will be discussed later.

[0039] The Fig. Figure 3 shows a spacer 1 according to the invention in a side view from the left. In this view, the two contact surfaces 2.1 and 2.2 are visible. The contact surface 2.1 consists of a concavely curved cylindrical surface with radius R1, and the contact surface 2.2 consists of a saddle surface having a first concave and a second convex curvature perpendicular to it. The concave curvature of the saddle surface consists of a cylindrical surface with radius R2. The convex curvature of the saddle surface corresponds to an oppositely curved cylindrical surface with radius R3. The radius R3 preferably describes a circle.

[0040] The Fig. Figure 4 shows a sectional view AA of the spacer according to the invention. In this sectional view, the two contact surfaces 2.1 and 2.2 are shown. The radius R1 is also shown here. This defines the concavely curved cylindrical surface. Furthermore, an off-center section CC is shown in the sectional view. This view is shown in the Fig. 7 shown

[0041] The Fig. Figure 5 shows a sectional view BB of the spacer according to the invention. This sectional view shows the two contact surfaces 2.1 and 2.2. Additionally, the radius R2, which defines the concave curvature of the cylindrical part of the saddle surface, is shown in the sectional view.

[0042] Fig. Figure 6 shows the rear view of a spacer 1. The spacer 1 has the grip elements 7 and the recesses 5. The rear view shows the contact surface 2.2 directly. The contact surface 2.2 consists of a saddle surface that has a concave and a convex curvature perpendicular to it. This saddle surface is defined by a contact line 2.21 and by a notch line 2.22. The notch line 2.22 of the spacer according to the invention, which represents the concave curvature, is defined by a radius R2. The contact line 2.21 of the spacer according to the invention, which represents the convex curvature, can, for example, be defined by a radius R3. However, it does not necessarily have to be a radius R3 of a circle. A hyperbola is also possible as the functional surface of the convex curvature of the saddle-shaped contact surface 2.2.

[0043] In the Fig. Figure 7, corresponding to the off-center sectional view of section CC, shows how the spacer 1 is inserted between two adjacent rolling elements 8, such that the rolling elements 8 are supported against each other via the spacer 1. The rolling element 8 bearing against the first contact surface 2.1 has a first axis of rotation 9.1, which corresponds to its longitudinal axis. This axis is parallel to the first longitudinal axis 3.1 of the concave curvature of the first contact surface 2.1, but is offset within a median plane of the spacer 1 relative to the first longitudinal axis 3.1 in a direction away from the first contact surface 2.1. The second axis of rotation 9.2 of the rolling element 8 bearing against the second contact surface 2.2 can also be positioned offset outwards relative to the second longitudinal axis of the concave curvature of the second contact surface 2.2 (not shown in detail here).

[0044] In the Fig. Figure 7 shows the two contact surfaces 2.1 and 2.2 in the sectional view. The radius R1 is also shown. This defines the concavely curved cylindrical surface of contact surface 2.1. The radius R describes the radius of the rolling elements. The spacer according to the invention ensures optimal contact between the rolling elements and the spacers 1, i.e., preferably: R1 < R < R2.

[0045] In the Fig. Figure 8 shows a section consisting of three rolling elements and two spacers 1 according to the invention. In the front view, the grip elements 7 are directly visible on the left spacer 1 according to the invention. Furthermore, the outer surface 4.1 between the grip elements 7 is visible. On the right spacer 1, only one grip element 7 and the outer surface 4.4 are visible. In the transition between the middle rolling element 8 and the right spacer 1, the second contact surface 2.2 is clearly visible. This contact surface 2.2 consists of the contact line 2.21 and the saddle line 2.22, which are already shown in the Fig. 6 was shown and in the Fig. Figure 3 shows the rolling elements again in perspective. Three of the rolling elements 8 are shown in this illustration, with the end face of the middle rolling element 8 being visible.

[0046] The Fig. 9 shows the same section as the Fig. 8, only in the top view. This means that the end faces of the two outer rolling elements 8 are visible, while only the cylindrical surface of the middle rolling element 8 is visible. The left spacer has the grip element 7 at one corner, as well as the outer surface 4.4 and the recess 5. Additionally, the contact surface 2.2 is visible at the transition between the first rolling element 8 and the left spacer 1. At this contact surface 2.2, the spacer 1 according to the invention has a point contact 11 with the rolling element 8. The right spacer 1 according to the invention has a line contact 10 with the right outermost rolling element 8 via the contact surface 2.1. In the top view, both grip elements 7 and the outer surface 4.1 of the right spacer 1 are also visible. In the Fig. Cut DD can also be seen in section 9.

[0047] The Fig. Figure 10 shows a section DD through a section consisting of three rolling elements 8 and two spacers 1 according to the invention. Thus, the arrangement again resembles the Fig. 8, whereupon the end face of the middle rolling element 8 is visible. The left rolling element 8 contacts the left spacer 1 according to the invention via the second contact surface 2.2 at a point 11. This is therefore a point contact. The left spacer 1 contacts the middle rolling element 8 with the first contact surface 2.1. This contact is a line contact 10 and is generally present twice. The middle rolling element 8 in turn has a point contact 11 with the right spacer 1 according to the invention. This point contact is visible at points 11, since the spacer is slightly twisted here, as shown in the Fig. As can be seen from Figure 9. Due to the rotation, a possible central point contact 11, located at the saddle point, which is the intersection of the pass line 2.21 and the notch line 2.22, becomes two point contacts 11, located at positions outside the central pass line 2.21. The right-hand spacer 1 according to the invention is in contact with the outermost spacer via the contact surface 2.1 and a line contact 10.

[0048] The design between the rolling element 8 and the first contact surface 2.1 achieves line contact along two parallel lines 10, whereas between the second contact surface 2.2 and the rolling element 8, point contact is achieved at two points 11.

[0049] The view of Fig. Figure 11 shows the state of the art, i.e. a conventional undefined system between the rolling elements 8 and the spacers 1.

[0050] Since the corresponding components or features in all figures are labelled with corresponding reference symbols, one can recognize from the Fig. 8 and Fig. 10 also again the positioning of the adjacent spacers 1 arranged by 90° to each other and by 180° over an imaginary axis of symmetry 19 of the middle rolling element 8, viewed in the circumferential direction of the corresponding roller bearing.

[0051] To achieve a particularly good fit of the spacer to the track curvature, it can be wedge-shaped. However, this is not mandatory.

[0052] In the Fig. 12, Fig. 13 to Fig.Figure 14 shows an embodiment of a roller bearing with spacers 1 and cylindrical rolling elements 8 according to the invention, which are positioned between an inner bearing ring 12 and an outer bearing ring 13. The spacers 1 and the rolling elements 8 can, for example, be inserted into the space 16 between the inner bearing ring 12 and the outer bearing ring 13 via a schematically illustrated filling opening 14, which can be closed by the filling plug 15, if the inner bearing ring 12 is already positioned or mounted within the outer bearing ring 13. Accordingly, the spacers 1 and the rolling elements 8 are alternately inserted one after the other into the space 16 via the filling opening 14 and moved over the circumference of the roller bearing or the space 16, whereby two successively inserted spacers 1 and rolling elements 8 are each inserted offset by 90° to each other in order to form a crossed roller bearing in which two raceways 17.1, 17.2 in the inner ring of the storage area 12 and two tracks 18.1, 18.2 in the outer ring of the storage area 13 are provided, which completely delimit the space 16 over its perimeter. Reference symbol list 1 spacer 2.1 First contact surface 2.2 second contact surface 2.21 Pass line 2.22 Notch line 3.1 first longitudinal axis 3.2 second longitudinal axis 4.1 First outdoor area 4.2 second outdoor area 4.3 third exterior surface 4.4 fourth exterior surface 5 recesses 6 bore 7 Handle element 8 rolling elements 9.1 First axis of rotation 9.2 second axis of rotation Line 10 11 points 12 inner bearing ring 13 Outer bearing ring 14 Filling opening 15 filling plugs Room 16 17.1 Career 17.2 Career 18.1 Career 18.2 Career R radius of the cylindrical rolling elements R1 Radius of the cylindrical surface of the first contact surface R2 radius of the cylindrical surface of the second contact surface 19. Axis of symmetry of the rolling element

Claims

Spacer (1) for a roller bearing, in particular a crossed roller bearing, with two opposing contact surfaces (2.1, 2.2) facing away from each other for cylindrical rolling elements (8) of the roller bearing positioned adjacent to each other, characterized in that a first of the two contact surfaces (2.1) is formed by a concave, simply curved cylindrical surface and a second of the two contact surfaces (2.2) is formed by a saddle surface with a concave and a convex curvature. Spacer (1) according to claim 1, characterized in that the concave curved part of the second contact surface (2.2) is formed by a concave curved cylindrical surface. Spacer (1) according to claim 1 or 2, characterized in that the convexly curved part of the second contact surface (2.2) is formed by a convexly curved cylindrical surface or a hyperboloid. Spacer (1) according to one of claims 1 to 3, characterized in that the radius (R) of the cylindrical rolling elements (8) is larger than the radius of curvature (R1) of the first contact surface (2.1). Spacer (1) according to one of claims 1 to 4, characterized in that the radius (R) of the cylindrical rolling elements (8) is smaller than the radius of curvature (R2) of the convexly curved part of the second contact surface (2.2). Spacer (1) according to one of claims 1 to 5, characterized in that the first contact surface (2.1) has a first longitudinal axis (3.1) of its concave curvature and the second contact surface (2.2) has a second longitudinal axis (3.2) of its concave curvature, wherein the first longitudinal axis (3.1) is positioned skew to the second longitudinal axis (3.2). Spacer (1) according to claim 6, characterized in that the first longitudinal axis (3.1) is rotated by 90° relative to the second longitudinal axis (3.2) in a projection of the two contact surfaces (2.1, 2.2) onto each other. Spacer (1) according to one of claims 1 to 7, characterized in that the spacer (1) is wedge-shaped, with a contact surface (2.1, 2.2) on each wedge surface. Spacer (1) according to one of claims 1 to 8, characterized in that the two contact surfaces (2.1, 2.2) are connected to each other by an opening opening into them. Spacer (1) according to claim 9, characterized in that the opening is made by a bore (6). Spacer (1) according to one of claims 1 to 10, characterized in that the spacer (1) has an outer circumference with four outer surfaces (4.1, 4.2, 4.3, 4.4) via which the two contact surfaces (2.1, 2.2) are connected to each other, and that at least one recess (5) for storing or conveying lubricating grease from the side of one contact surface (2.1, 2.2) to the side of the other contact surface (2.2, 2.1) is provided in one, two, three or all outer surfaces (4.1, 4.2, 4.3, 4.4). Spacer (1) according to claim 11, characterized in that the spacer (1) has at least substantially a square shape with concave sides in a top view of the first contact surface (2.1) or second contact surface (2.2). Spacer (1) according to one of claims 1 to 12, characterized in that at least one gripping element (7) for gripping the spacer (1) with a gripper, tweezers or the like is provided on the outer circumference of the spacer (1). Spacer (1) according to claim 13, characterized in that only a single handle element (7) is provided, or that a handle element (7) is provided at each of two corners positioned adjacent to each other on the circumference of the spacer (1). Roller bearings with two bearing rings (12, 13) positioned next to or inside each other and a plurality of cylindrical rolling elements (8), characterized in that spacers (1) according to one of claims 1 to 14 are provided between adjacent rolling elements (8). Roller bearing according to claim 15, characterized in that the roller bearing is designed as a crossed roller bearing with an inner bearing ring (12) and an outer bearing ring (13) and the rolling elements (8) with their axes of rotation (9.1, 9.2) are alternately crossed in circumferential direction one behind the other between the inner bearing ring (12) and the outer bearing ring (13). Roller bearing according to one of claims 15 or 16, characterized in that exactly one spacer (1) is provided between each pair of adjacent rolling elements (8), against which the rolling elements (8) bear at the contact surfaces (2.1, 2.2). Roller bearing according to one of claims 15 to 17, characterized in that the first contact surface (2.1) forms a line contact with a rolling element (8) adjoining it along one or two lines (10) and the second contact surface (2.2) forms a point contact with a rolling element (8) adjoining it at one or two points (11).

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