CH711020B1 - Bearing and method of assembling such a bearing. - Google Patents

Abstract

The present invention relates to a bearing (10), comprising an outer element (11), an inner element (12), rolling elements (13) arranged between a contact face (11 ') of the outer element (11). ) and a contact face (12 ') of the inner element, as well as a spacer (15) of the rolling elements (13). The rolling elements (13) are retained in a raceway only by the outer element (11) and by the inner element (12). The dimensions of the bearing (10) are reduced so as to be usable in a watch movement and the contact face (11 ') of the outer element (11) and / or the contact face (12') of the 'inner element (12) have a non-circular cross section. Each rolling element (13) and one or each of the contact faces (11 ', 12') are in contact only at two points. The present invention also relates to a method of assembling a corresponding bearing.

Description

Technical field of the invention

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

State of the art

[0002] Ball type bearings 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 ball-type bearings are of small dimensions, so that these ball bearings must also have reduced dimensions.

[0003] One technical field in which ball bearings with reduced dimensions are used is mechanical watchmaking. More specifically, small-sized ball bearings are very often used in a watch movement to support the oscillating mass (also called a rotor) in a self-winding watch.

[0004] An oscillating weight is normally an eccentric element which is arranged in the watch movement so as to be able to turn on itself while driving a set of gears making it possible to arm the mainspring of the movement. The eccentricity of the oscillating weight means that the forces acting on the ball bearings to support them are very high, which significantly increases the stresses at the level of the clearance and / or "kippspiel" and imposes certain restrictions on the performance level. As, in general, self-winding watches are rather high-end products, it is clear that too high clearance and / or "kippspiel" should be eliminated as much as possible.

[0005] An object of the present invention is therefore to provide a bearing of reduced dimensions having a structure which makes it possible to reduce its play and / or its "kippspiel" as much as possible.

[0006] However, even a ball bearing with a suitable structure can present increased problems in terms of clearance and “kippspiel” if its components are not correctly 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 the bearing components can also lead to high clearances and / or "kippspiels", thereby reducing the performance of the bearings.

[0007] Another object of the present invention is therefore to provide a bearing of reduced dimensions which can be assembled in a simpler and more precise manner compared to existing assembly methods.

Summary of the invention

[0008] The present invention therefore aims to overcome all of the aforementioned drawbacks of bearings and to provide a new bearing of reduced dimensions which combines improved performance compared to existing bearings and whose structure also allows assembly (or disassembly ) easy.

[0009] The objects of the present invention are in particular achieved by means of a bearing according to claim 1. Particular or preferred embodiments of the present invention are the subject of dependent claims.

[0010] In particular, the objects of the present invention are achieved by means of a bearing, comprising an outer element, an inner element, rolling elements arranged between a contact face of the outer element and a face of contact of the inner element, as well as a spacer element of the rolling elements. The rolling elements are retained in a raceway only by the outer element and by the inner element. The bearing has reduced dimensions so as to be usable in a watch movement. The contact face of the outer member and / or the contact face of the inner member have a non-circular cross section. Each rolling element and one or each of the contact faces are in contact only at two points

[0011] Of course, the rolling elements can advantageously have the spherical shape (one then speaks of "balls"), but other shapes such as cones or oval elements are of course also possible.

[0012] Such a bearing therefore has a structure which enables it to position and guide the rolling elements more precisely compared to the structures of known small-dimension 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 shape and size of the rolling members helps to minimize clearance and / or "Kippspiel" of a bearing with the 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 an essentially parabolic cross section so as to allow, thanks to its symmetry only two points of contact between each rolling element and one or each of the exterior and interior elements. The advantage of such a cross-section is simple machining and the fact that it is possible to use a spherically shaped rolling element with the dimensions allowing to minimize to the maximum (i.e. up to a point contact) the contact surface between these faces and the rolling element.

[0014] In another preferred embodiment of the present invention, the cross section of the contact face of the outer element and / or the cross section of the contact face of the inner element are composed of two curvilinear portions . The advantage of such a shape is an even simpler machining and the fact that it is also possible to use a rolling element of spherical shape (but also a rolling element having another shape) with the dimensions allowing to minimize at maximum (ie up to a “point” contact) the contact surface between these faces and the rolling element.

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

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

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

[0018] Notably, the bearing can be designed for use in a watch movement. In particular, its size and shape can be chosen in order 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 element and the contact face of the inner element are rectified. When this is the case, the rolling of the rolling elements on the contact faces is smoother and smoother. In particular, it is carried out with less friction and less noise. A rectification of the contact faces has the other advantage of making it possible to obtain greater precision on the shape of these contact faces and therefore to reduce the play, which results in more precise guidance of the rolling elements and increased quality. of rotation.

[0020] Advantageously, the rolling elements are spherical balls.

[0021] The objects of the present invention are, in another aspect, also achieved by means of a method of arranging a bearing according to claim 9.

In particular, the objects of the present invention according to this second aspect of the invention are achieved using a method of assembling the bearing, comprising the following steps: provision of an external element having a contact face; positioning the rolling elements so as to come into contact with the contact face of the outer element; positioning an inner element having a contact face inside the outer element, so that the rolling elements come into contact with the contact face of the inner element; and positioning a rolling element spacer between the outer member and the inner member so as to secure the rolling elements in position.

Brief description of the drawings

The invention will be clearly understood on reading the following description given by way of non-limiting example with reference to the accompanying drawings which schematically represent: <tb> <SEP> Figure 1: a schematic sectional view of a ball type bearing according to an embodiment of the present invention; <tb> <SEP> Figure 2: a schematic top view of the ball type bearing of Figure 1 with the indication of the cutting position; <tb> <SEP> Figure 3: A schematic perspective sectional view of the ball type bearing of Figure 1, shown in a top view; <tb> <SEP> Figure 4: A schematic perspective sectional view of the ball type bearing of Figures 1 and 2, shown in a bottom view; <tb> <SEP> Figure 5: an exploded schematic view of the ball type bearing of Figure 1; and <tb> <SEP> Figure 6: An enlarged schematic view of the part of the ball type bearing in Figure 1.

Detailed description of the invention

Figure 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 top view in Figure 2.

The ball bearing 10 comprises an outer element 11 in the form of a circular ring and an inner element 12 also in the form of a circular ring positioned concentrically inside the opening of the outer element 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 element 11 and the inner element 12 of the ball bearing 10 in Figures 1 and 2 have these particular shapes, it is quite conceivable to produce a ball bearing corresponding to the present invention with a different exterior shape.

This ball bearing 10 has small 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.

[0027] The ball bearing 10 also includes a number (eg five) of rolling elements 13. The rolling elements 13 shown in Figure 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, especially 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 (the exact number of which can be chosen according to different parameters) are positioned between the outer element 11 and the inner element 12. For this purpose, the outer element 11, on its turned part towards the interior element 12, has a face 11 'of concave shape to come into contact with the rolling elements 13. Equivalently, the interior element 12 has, on its part facing towards the exterior element 11, a face 12 'of concave shape to come into 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 includes a spacer 15 for fixing the rolling elements 13 in position relative to each other. In other words, this spacer 15 (often called a "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. 5. It is an essentially annular element having in particular a number of recesses 15 'corresponding to the number of rolling elements 13. The recesses 15' in the spacer 15 are dimensioned and designed to be able to accommodate the rolling elements 13, while leaving these rolling elements 13 the possibility of turning about their axis of rotation when using the ball bearing 10.

When the ball bearing 10 is used in a watch movement, the outer element 11 can carry on its outer perimeter a toothing 16 capable of engaging with the moving parts in the corresponding gear train. Of course, other shapes of the outer element 11 are quite conceivable and it is for example also possible to provide an outer element 11 having no teeth on its outer perimeter.

[0031] Also, the inner element 12 may include a central opening 14 allowing the ball bearing 10 to be fixed to the plate (or to a bridge) of the watch movement, eg using a screw or another suitable fastening means (not shown). To this end, the inner element 12 also has a higher element 17 also allowing the housing of the head of the screw which is used for the 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. Likewise, the way of fixing the ball bearing 10 can also vary, if necessary.

The components of the ball bearing 10 can be made from 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.

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

The mutual positioning of the outer member 10, the inner member 12, the rolling elements 13 and the spacer element 15 is clearly visible in Figures 3 and 4. Indeed, the rolling elements 13 are arranged equidistantly in the slot positioned between the contact face 11 'of the outer member 11 and the contact face 12' of the inner member 12 and this constant spacing is ensured by the spacer 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 Figure 1 are shown in Figure 5 in an exploded schematic view. Clearly visible is the shape of the cage 15 with the recesses 15 'for housing the balls 13. Also clearly visible is the contact face 12' of the interior element 12 which appears as a groove extending over the entire perimeter. exterior of the interior element 12. Equivalently, the contact face 11 ′ of the exterior element 11 also extends over the whole of its interior perimeter (inside the exterior element 11, therefore on the side facing the rolling elements 13, the spacer 15 and the inner element 12).

The cross section of the contact faces 11 ', 12' is clearly visible in Figure 6 which is an enlargement of part of the ball bearing 10 shown in Figure 1. A rolling element 13 is shown in the center of Figure 6. Its spherical shape can be appreciated. This rolling element 13 is in contact with both the outer element 11 (on the right) and with the inner element 12 (on the left) through the contact faces 11 'and 12', respectively. As can easily be appreciated, the faces 11 'and 12' have shapes which 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' (indeed, 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 of 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 element 11 and / or of the contact face 12' of the inner element 12 can also be varied. A preferred cross section is a parabola which has advantages in particular thanks to 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 (e.g. an arc followed by a parabola segment or right, etc.). The contact faces 11 ', 12' can have symmetry with respect to the central point, but it is also possible to provide the surfaces which do not have symmetry or which have symmetry 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 ground. However, it may be otherwise. For example, the contact faces 11 ′ and 12 ′ may result only from a turning, that is to say that their production may not include any finishing operation after this turning. According to another possibility, a finishing other than grinding can be carried out on the contact faces 11 'and 12' after turning. It can be, for example, a hard shoot.

When the contact faces 11 'and 12' are ground, the rolling of the rolling elements 13 on the contact faces 11 'and 12' is smoother and smoother. In particular, it is carried out with less friction and less noise. A rectification of the contact faces 11 'and 12' has the other advantage of making it possible to obtain greater precision on the shape of these contact faces 11 'and 12' and therefore of reducing the play, which results in a more adjusted guidance of the rolling elements 13 and an increased quality of the rotation.

[0041] The ball bearing 10 according to the present invention is also particularly advantageous because of the fact that it can be assembled easily. To assemble such a ball bearing 10, the following steps are carried out: an outer element having a contact face is provided; rolling elements are positioned so as to come into contact with the contact face of the outer element; 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 spacer is positioned between the outer member and the inner member so as to secure the rolling elements in position.

This assembly method therefore has only four steps, which corresponds to the fact that the ball bearing 10 also has essentially only four components. Assembly is therefore quick and easy, particularly compared to conventional small-sized ball bearings, in which the raceway is delimited by three separate elements, two of which are exterior. Furthermore, the use of the shape and dimensions of the rolling elements 13, of the contact face 11 'of the outer member 11 and / or of the contact face 12' of the inner member 12 to minimize the clearance and / or the "kippspiel" makes it possible to obtain a very precise ball bearing 10 even with very simple assembly. Also, the reduced number of components of the ball bearing 10 produces advantages in production and logistics.

It is obvious to a person skilled in the art that all the information which has just been given concerning a ball type bearing and the corresponding assembly process can easily be adapted and / or supplemented with the aid of other elements well known in the art, without departing from the scope of the present invention as defined by claim 1 attached.

Claims (9)

1. Bearing, 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 element, as well as a spacer (15) of the rolling elements (13), the rolling elements (13) being retained in a raceway only by the outer element (11) and by the inner element (12), in which the bearing (10) has reduced dimensions so as to be usable in a watch movement, in which the contact face (11 ') of the outer element (11) and / or the contact face (12 ') of the inner member (12) has a non-circular cross section, and in which each rolling member (13) and one or each of the contact faces (11', 12 ' ) are in contact only at two points. 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 substantially parabolic cross section so as to allow, thanks to its symmetry, only two points of contact between each rolling element (13) and one or each of the outer (11) and inner (12) elements. 3. Bearing (10) according to claim 1, wherein the cross section of the contact face (11 ') of the outer member (11) and / or the cross section of the contact face (12') of the 'interior element (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) do not exceed 2.4 mm or wherein the width of the outer element (11) does not exceed 14 mm. 5. 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) do not exceed 1 mm or wherein the width of the outer element (11) does not exceed 5 mm. 6. Bearing (10) according to one of the preceding claims, wherein a toothing (16) is arranged on the outer perimeter of the outer member (11). 7. 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 corrected. 8. Bearing (10) according to one of the preceding claims, characterized in that the rolling elements are spherical balls (13). 9. A method of assembling a bearing according to one of claims 1 to 8 comprising the following steps: - provision of an external element (11) having a contact face (11 '); - positioning of the rolling elements (13) so as to come into contact with the contact face (11 ') of the outer element (11); - positioning of an inner element (12) having a contact face (12 ') inside the outer element (11), so that the rolling elements (13) come into contact with the face of contact (12 ') of the inner element (12); and - Positioning of a spacing element (15) of the rolling elements (13) between the outer element (11) and the inner element (12) so as to fix the rolling elements (13) in position.