CH711020A2 - Ball bearings and method for assembling such a ball bearing. - Google Patents

Abstract

The present invention relates to a ball-type bearing (10), comprising an outer member (11), an inner member (12), rolling elements (13) arranged between a contact face (11 ') of the outer member (11) and a contact face (12 ') of the inner member, and a spacer (15) of the rolling members (13). The rolling elements (13) are retained in a raceway only by the outer member (11) and the inner member (12). The dimensions of the bearing (10) are reduced and the contact face (11 ') of the outer element (11) and / or the contact face (12') of the inner element (12) have a cross-section not circular. The present invention also relates to a method of assembling a bearing of the corresponding ball type.

Description

Technical field of the invention

The present invention relates generally to the technical field of ball type bearings and methods of assembling such bearings. More concretely, the present invention relates to a ball-type bearing with reduced dimensions, specifically used to guide in rotation and support objects of small dimensions. The invention also relates to a method of assembling such a bearing.

State of the art

[0002] Bearings of the ball type are used in various fields, in particular with the aim of reducing friction when guiding the rotating elements. In some areas, the elements supported by the ball-type bearings are small, so that these ball bearings must also have the reduced dimensions.

A technical field in which ball bearings with reduced dimensions are used is mechanical watchmaking. More specifically, small ball bearings are very often used in a watch movement to support the oscillating weight (also called rotor) in a self-winding watch.

An oscillating mass is normally an eccentric element which is arranged in the watch movement so as to rotate on itself while driving a set of gears for arming the motor spring of the movement. The eccentricity of the oscillating mass makes the forces acting on the ball bearings to support them are very important, which significantly increases the constraints on the game and / or "kippspiel" and imposes certain restrictions on the level of performance. As, in general, self-winding watches are rather high-end products, it is clear that a game and / or a "kippspiel" too high must be eliminated to the maximum.

An object of the present invention is therefore to provide a ball-type bearing of reduced dimensions having a structure to minimize its game and / or its "kippspiel".

However, even a ball bearing with a suitable structure may present problems with the game and the "kippspiel" if its components are not properly assembled. Indeed, the assembly of a ball bearing with the reduced dimensions is particularly difficult because of the small size of its components. Any inaccuracy in the relative positioning of bearing components can also result in high clearance and / or kippspiels, thereby reducing bearing performance.

Another object of the present invention is therefore to provide a ball-type bearing of reduced dimensions which can be assembled more simply and more precisely compared to existing assembly methods.

Summary of the invention

The present invention therefore aims to overcome all the aforementioned drawbacks of ball-type bearings and to provide a new reduced-size ball bearing that combines improved performance compared to existing bearings and whose structure also allows easy assembly (or disassembly)

The objects of the present invention are in particular achieved by means of a ball-type bearing according to claim 1. Particular or preferred embodiments of the present invention are the subject of dependent claims.

In particular, the objects of the present invention are achieved by means of a ball-type bearing, comprising an outer member, an inner member, rolling elements arranged between a contact face of the outer member. and a contact face of the inner member, as well as a spacer element of the rolling elements. The rolling elements are retained in a raceway only by the outer element and the inner element. The bearing has reduced dimensions so as to be usable in a watch clock movement. The contact face of the outer member and / or the contact face of the inner member have a non-circular cross section.

Of course, the rolling elements may advantageously have the spherical shape (so-called "balls"), but other shapes such as cones or oval elements are of course also possible.

Such a ball bearing therefore has a structure that allows a positioning and guidance of the rolling elements more accurate compared to the structures of small known bearings. Specifically, the non-circular cross-section of the contact face of the outer member and / or the inner member in combination with an appropriate choice of the shape and size of the rolling members minimizes the play and / or "Kippspiel" of a ball-type bearing with reduced dimensions according to the present invention.

In a preferred embodiment of the present invention, the contact face of the outer element and / or the contact face of the inner element have a substantially parabolic cross section so as to allow thanks to its symmetry only four points of contact between each rolling element and the outer and inner elements. The advantage of such a cross section is simple machining and the fact that it is possible to use a spherical rolling element with the dimensions to minimize the maximum (that is to say up to one "punctual" contact) the contact surface between these faces and the rolling element.

In another preferred embodiment of the present invention, the contact face of the outer member and / or the contact face of the inner member are composed of two curvilinear portions. The advantage of such a shape is even simpler machining and the fact that it is also possible to use a roller element of spherical shape (but also a rolling element having another shape) with the dimensions making it possible to minimize the maximum (that is to say up to a "punctual" contact) the contact surface between these faces and the rolling element.

Advantageously, the height of the outer member and / or the height of the inner member does not exceed 2.4 mm or the width of the outer member does not exceed 14 mm.

Advantageously, the height of the outer member and / or the height of the inner member does not exceed 1 mm or the width of the outer member does not exceed 5 mm.

Advantageously, each rolling element and one or each of the contact surfaces are in contact only at two points.

In another preferred embodiment of the present invention, a toothing is arranged on the outer perimeter of the outer member. Thanks to such a structure, the ball bearing according to this embodiment of the present invention can be used in a gear train without any intermediate element.

[0019] Notably, the bearing can be designed for use in a watch movement. In particular, its dimensioning and shape can be chosen to meet the needs of a specific use (eg to support an oscillating weight in a watch movement of a self-winding watch).

Advantageously, the contact face of the outer member and the contact face of the inner member are rectified. When this is the case, rolling of the rolling elements on the contact faces is smoother and smoother. In particular, it is performed with less friction and reduced noise. A further advantage of the grinding of the contact faces is that it makes it possible to obtain a greater precision on the shape of these contact faces and thus to reduce the clearance, which results in a more precise guidance of the rolling elements and an increased quality. of the rotation.

[0021] Advantageously, the rolling elements are spherical balls.

The objects of the present invention are, in another aspect, also achieved by means of a method of arranging a ball-type bearing according to claim 9.

In particular, the objects of the present invention according to this second aspect of the invention are achieved by means of a method of assembling a ball-type bearing, comprising, in any order, the following steps: providing an outer member having a contact face; positioning the rolling elements so as to contact the contact face of the outer member; positioning an inner member having a contact face within the outer member so that the rolling members contact the contact face of the inner member; and positioning a rolling element spacing element between the outer element and the outer element so as to fix the rolling elements in position.

Brief description of the drawings

The invention will be better understood on reading the following description given by way of non-limiting example with reference to the accompanying drawings which show schematically: <Tb> Fig. 1: <SEP> a schematic sectional view of a ball-type bearing according to an embodiment of the present invention; <Tb> Fig. 2: <SEP> a schematic view from above of the ball-type bearing of FIG. 1 with the indication of the cutting position; <Tb> Fig. 3: <SEP> a diagrammatic sectional view in perspective of the ball-type bearing of FIG. 1, shown in a view from above; <Tb> Fig. 4: <SEP> a diagrammatic sectional perspective view of the ball-type bearing of FIGS. 1 and 2, shown in a view from the bottom; <Tb> Fig. 5: <SEP> an exploded schematic view of the ball-type bearing of FIG. 1; and <Tb> Fig. 6: <SEP> an enlarged schematic view of the ball bearing portion of FIG. 1.

Detailed description of the invention

FIG. 1 schematically shows a cross-sectional view of a ball-type bearing 10 according to a first embodiment of the present invention. This same bearing 10 is shown in a view from above in FIG. 2.

The ball bearing 10 comprises an outer member 11 in the form of a circular ring and an inner member 12 also in the form of a circular ring concentrically positioned inside the opening of the outer member. 11. Because of this circular shape, the outer member 11 and the inner member 12 of the ball bearing 10 are often referred to as "outer ring" and "inner ring", respectively. Of course, even if the outer member 11 and the inner member 12 of the ball bearing 10 in FIGS. 1 and 2 have these particular shapes, it is quite conceivable to make a ball bearing corresponding to the present invention with a different outer shape.

This ball bearing 10 has reduced dimensions compared to conventional ball bearings. For example, its height (which corresponds to the height of the outer member 11) is 1 mm or less and its outer diameter is 5 mm or less. Other dimensions are also possible.

The ball bearing 10 also comprises a number (eg five) of rolling elements 13. The rolling elements 13 shown in FIG. 1 have a spherical shape and are often called "balls". Of course, it would also be possible to use the rolling elements 13 having another shape, in particular a conical or cylindrical shape or even a combination of rolling elements of different shapes (eg a combination of balls and cylinders).

These rolling elements 13 (whose exact number can be chosen according to different parameters) are positioned between the outer member 11 and the inner member 12. To this end, the outer member 11, on its turned part to the inner element 12, has a concave-shaped face 11 for contacting the rolling elements 13. Equally, the inner element 12 has, on its part turned towards the outer element 11, an concave-shaped face 12 to make contact with the rolling elements 13. The shape of the contact faces 11 and 12 will be described in more detail later.

Finally, the ball bearing 10 also comprises a spacer 15 for fixing the rolling elements 13 in position relative to each other. In other words, this spacer element (often called "cage") also comes into contact with the rolling elements 13 and ensures a constant spacing between the rolling elements 13 during the use of the ball bearing 10. The shape of the spacer element 15 is visible in FIG. 15. It is a substantially annular element having in particular a number of recesses 15 corresponding to the number of rolling elements 13. The recesses 15 in FIG. the spacer element 15 are dimensioned and designed to accommodate the rolling elements 13, while leaving these rolling elements 13 the possibility of rotating about their axis of rotation during the use of the ball bearing 10.

When the ball bearing 10 is used in a watch movement, the outer member 11 may carry on its outer perimeter a toothing 16 capable of engraining with the mobile in the corresponding gear train. Of course, other forms of the outer element 11 are quite imaginable and it is for example also possible to provide an outer element 11 having no teeth on its outer perimeter.

Also, the inner member 12 may comprise a central opening 14 for fixing the ball bearing 10 to the plate (or a bridge) of the watch movement, eg with a screw or another suitable fastening means (not shown). To this end, the inner member 12 also has a higher element 17 also allowing the housing of the head of the screw which is used for fixing. Of course, and as already mentioned before, the shape of the outer element 11 can also vary depending on the field of use of the ball bearing 10. Similarly, the manner of fixing the ball bearing 10 can also vary, if necessary.

The components of the ball bearing 10 can be made of the same material, but it is of course also possible to manufacture each component in a different material, depending on the needs. Particularly suitable materials are stainless steel or ceramic (eg ZrO2), but other materials can also be used.

Figs. 3 and 4 show schematically in section and in perspective the ball-type bearing 10 according to the embodiment of the present invention of FIGS. 1 and 2, once in sight from the top and once in sight from the bottom.

The mutual positioning of the outer member 10, the inner member 12, the rolling elements 13 and the spacer 15 is clearly visible in FIGS. 3 and 4. Indeed, the rolling elements 13 are arranged equidistantly in the slot positioned between the contact face 11 of the outer element 11 and the contact face 12 of the inner element 12 and this constant spacing is ensured by the spacing element 15 which blocks a possible circular displacement of the rolling elements 13.

The components of the ball bearing 10 according to the embodiment of the present invention of FIG. 1 are shown in FIG. 5 in an exploded schematic view. Visible is the shape of the cage 15 with the recesses 15 for the housing of the balls 13. Also visible is the contact face 12 of the inner member 12 which is a groove extending over the entire perimeter exterior of the inner member 12. Equivalently, the contact face 11 of the outer member 11 also extends over its entire inner perimeter (inside the outer member 11, so on the turned towards the rolling elements 13, the spacer element 15 and the inner element 12).

The cross section of the contact faces 11, 12 is clearly visible in FIG. 6 which is an enlargement of a portion of the ball bearing 10 shown in FIG. 1. A rolling element 13 is illustrated in the center of FIG. 6. Its spherical shape can be appreciated. This rolling member 13 is in contact with both the outer member 11 (right) and the inner member 12 (left) through the contact faces 11 and 12, respectively. As can easily be appreciated, the faces 11 and 12 have shapes that do not follow the spherical shape of the rolling element 13. In fact, the contact faces 11, 12 have non-circular shapes (When this shape is seen in section), resulting in a "point" contact between the rolling element 13 and these contact faces 11, 12 (in fact, two "contact points" are visible between the contact face 11 and the rolling element 13, in an equivalent manner, two "contact points" are visible between the contact face 12 and the rolling element 13).

By choosing the dimensions and / or the shape of the rolling elements 13 according to the shape of the contact face 11 and / or the contact face 12 (or vice versa), the play (and the "Kippspiel") in the ball bearing 10 can be minimized.

The cross section of the contact face 11 of the outer member 11 and / or the contact face 12 of the inner member 12 can also be varied. A preferred cross-section is a parabola which has advantages in particular because of its symmetry. However, other cross sections are also possible, and it is also possible to provide any cross section, composed of two or more segments with different characteristics (eg a circular arc followed by a parabola segment or right, etc.). The contact faces 11, 12 may have a symmetry with respect to the central point, but it is also possible to provide surfaces that are not symmetrical or symmetrical with respect to another point. Finally, it is also conceivable to provide contact faces 11, 12 with the shapes varying along the perimeter of the inner member 12 or the outer member 11, respectively.

Preferably, the contact faces 11 and 12 are rectified. It may be otherwise. For example, the contact faces 11 and 12 may result only from a turning, that is to say that their realization may not include a finishing operation after this shoot. According to another possibility, a finishing other than a grinding can be carried out on the contact faces 11 and 12 after the turning. It can be, for example, a hard shoot.

When the contact faces 11 and 12 are ground, the rolling elements rolling 13 on the contact faces 11 and 12 is more regular and softer. In particular, it is performed with less friction and reduced noise. Another advantage of rectification of the contact faces 11 and 12 is that it makes it possible to obtain a greater precision on the shape of these contact faces 11 and 12 and thus to reduce the clearance, which results in more precise guidance of rolling elements 13 and increased quality of rotation.

The ball bearing 10 according to the present invention is also particularly advantageous because it can be assembled in an easy manner. To assemble such a ball bearing 10, the following steps are carried out in any order: an outer member having a contact face is provided; rolling elements are positioned to contact the contact face of the outer member; an inner member having a contact face is positioned in the opening inside the outer member, so that the rolling elements also come into contact with the contact face of the inner member; and a rolling element spacing member is positioned between the outer member and the outer member to fix the rolling members in position.

This assembly process therefore has only four steps, which corresponds to the fact that the ball bearing 10 also has essentially only four components. The assembly is therefore quick and easy, especially compared to conventional small-size ball bearings, in which the raceway is delimited by three separate elements, two of which are external. In addition, the use of the shape and dimensions of the rolling elements 13, the contact face 11 of the outer element 11 and / or the contact face 12 of the inner element 12 to minimize the play and / or the "kippspiel" makes it possible to obtain a very precise ball bearing even with a very simple assembly. Also, the reduced number of ball bearing component 10 provides production and logistical advantages.

It is obvious to a person skilled in the art that all the information that has just been given concerning a ball-type bearing and the corresponding assembly method can easily be adapted and / or supplemented with the aid of others. elements well known in the art, without departing from the scope of the present invention.

Claims (11)

Ball-type bearing (10), comprising an outer member (11), an inner member (12), rolling elements (13) arranged between a contact face (11) of the outer member (11) and a contact face (12) of the inner member, and a spacer (15) of the rolling elements (13), the rolling elements (13) being retained in a raceway only by the outer member (11) and the inner member (12), wherein the bearing (10) is reduced in size so as to be usable in a watch clock movement, and wherein the contact face (11 ') of the outer member (11) and / or the contact face (12) of the inner member (12) have a non-circular cross-section. 2. Bearing (10) according to claim 1, wherein the contact face (11) of the outer member (11) and / or the contact face (12) of the inner member (12) have a cross section essentially parabolic so as to allow through its symmetry only four points of contact between each rolling element (13) and the outer elements (11) and inner (12). 3. Bearing (10) according to claim 1, wherein the contact face (11) of the outer member (11) and / or the contact face (12) of the inner member (12) are composed of two curvilinear portions. 4. Bearing (10) according to one of the preceding claims, wherein the height of the outer member (11) and / or the height of the inner member (12) does not exceed 2.4 mm or in which the width of the outer element (11) does not exceed 14 mm. Bearing (10) according to one of the preceding claims, wherein the height of the outer member (11) and / or the height of the inner member (12) does not exceed 1 mm or in which the width of the the outer element (11) does not exceed 5 mm. 6. Bearing (10) according to one of the preceding claims, wherein each rolling element (13) and one or each of the contact surfaces (11, 12) are in contact only at two points. 7. Bearing (10) according to one of the preceding claims, wherein a toothing (16) is arranged on the outer perimeter of the outer member (11). Bearing (10) according to one of the preceding claims, characterized in that the contact face (11 ') of the outer element (11) and the contact face (12) of the inner element (12) ) are rectified. 9. Bearing (10) according to one of the preceding claims, characterized in that the rolling elements are spherical balls (13). 10. A method of assembling a ball-type bearing, comprising, in any order, the following steps: - providing an outer member (11) having a contact face (11); Positioning the rolling elements (13) so as to come into contact with the contact face (11) of the outer element (11); Positioning an inner element (12) having a contact face (12) inside the outer element (12) so that the rolling elements (13) come into contact with the contact (12) of the inner member (12); and - Positioning a spacer (15) of the rolling elements (13) between the outer member (11) and the outer member (12) so as to fix the rolling elements (13) in position. 11. Assembly method according to claim 10, characterized in that it is a method of assembling a bearing according to any one of claims 1 to 9.