Rolling bearings for medical or cosmetic devices

Abstract

To provide a rolling bearing for a medical or cosmetic instrument.SOLUTION: A medical or cosmetic instrument includes a bearing inner ring 1 rotating around a rotation axis 5 and a stationary bearing outer ring 2 enclosing the bearing inner ring. A bearing gap 3 is formed between the bearing inner ring and the bearing outer ring, a plurality of rolling bodies are arranged in the bearing gap, one behind the other in the circumferential direction, and the bearing inner ring is supported by the bearing outer ring via the rolling bodies 4. The rolling bodies are arranged so as to roll on the bearing inner ring and the bearing outer ring, and have a rolling body height in the radial direction. In the axial direction, the bearing gap is attached to the bearing outer ring, attached to a casing accommodating the bearing outer ring or covered by a cover disk 6 integrally formed with the casing or the bearing outer ring. The cover disk jointly with the bearing inner ring, forms a radial gap 7 extending across a gap length in the axial direction, where the radial gap has a gap height in the radial direction. The gap length is at least 25% of the rolling body height.SELECTED DRAWING: Figure 21

Description

[Technical field]

[0001] The present invention relates to a rolling bearing for a medical or cosmetic instrument, in particular a hand-held instrument, as well as to a medical or cosmetic instrument, in particular a hand-held instrument, for example a dental hand-held instrument, provided with such a rolling bearing.

[0002] In rolling bearings, there is a risk that contaminating particles that penetrate between the outer and inner bearing rings, especially in the area of ​​the rolling surfaces of the rolling elements, will cause premature wear, which will shorten the service life of the rolling bearing. Furthermore, in rolling bearings in medical or cosmetic instruments, when the instruments need to be sterilized with more or less powerful germicides, the grease or lubricant will be rinsed from the rolling bearing, which will also cause premature wear and shorten the service life of the rolling bearing. Therefore, at least in handheld instruments, it is common practice to seal the bearing gap between the inner and outer bearing rings, in order to minimize the ingress of foreign bodies or unwanted media.

[0003] At the same time, in rolling bearings in medical instruments, in particular dental hand-held instruments, for example straight or angle handpieces, to which the present invention is particularly concerned, it may be desirable in certain applications for body fluids, such as blood or saliva, to flow through the instrument and then be appropriately treated. In this case too, deposition of particles in the bearing must be avoided, especially at the stop of the drive shaft and the subsequent stationary state of the shaft, since this eliminates the pressure difference in the area of ​​the bearing. Furthermore, the above mentioned references to the ingress of disinfectants are also applicable. Therefore, in such instruments, it is preferable to provide a seal which seals the bearing gap when the rolling bearing is stationary, i.e. when it is not rotating, or when the shaft of the instrument supported in the rolling bearing is not rotating, and which more or less eliminates the bearing gap when the rolling bearing rotates or when the shaft rotates.

[0004] EP 0 689 801 (A2) accordingly discloses a bearing seal with a straight sealing plate or a curved labyrinth ring on the outer and inner bearing rings for a medical or dental treatment tool with a drive, which adequately seals the bearing gap by forming a labyrinth seal. To form the labyrinth seal, it is possible to use sealing plates or sealing rings that are alternately attached to the outer and inner bearing rings. Furthermore, the tool-carrying shaft can be provided with a centrifugal ring, which is arranged upstream of the seal on the erosion side of body fluids such as blood or saliva.

[0005] DE102012000757(A1) discloses an elastically deformable sealing plate for sealing the bearing gap between the outer and inner rings of a bearing. The sealing plate, which is held in a non-rotatable manner on the outer ring of the bearing, floats up from the counter surface due to the pressure difference when the inner ring of the bearing rotates, and abuts against the counter surface when the inner ring of the bearing is stationary with the pressure difference removed. This achieves the aforementioned function of contact sealing in the stationary state and the aforementioned function of non-contact sealing in the operating state with the shaft rotating.

[0006] In EP 0 497 139 (B1) it is proposed to achieve the same function by providing an elastic plate around the tool shaft in the handpiece head which in the stationary state is in surrounding contact with the tool shaft and seals towards the outside, said elastic plate floating above the tool shaft to such an extent that contact no longer occurs under the action of the overpressure which occurs in the handpiece head during operation. When the drive air is switched off and the overpressure in the handpiece head is thus eliminated, the elastic plate again abuts against the still rotating tool shaft, thereby braking it, while at the same time a negative pressure is created in the casing, so that the ingress of foreign matter along the tool shaft is prevented.

[0007] DE 10 2018 200303 (A1) proposes, for a bearing as mentioned at the outset, a sealing plate made of elastic material which is attached to the rotating bearing ring in order to be more or less deformed by centrifugal forces and thus seal the gap in the stationary state and to eliminate the seal in operation. The sealing plate can define a sealing gap together with a counter surface formed by a counter element attached to the stationary bearing ring.

[0008] DE 102019200371 (A1) proposes for such bearings a seal plate with legs which are positioned between the bearing casing and the bearing outer ring and which perform a damping function, the seal plate being able to form a seal gap either at the axial end face of the bearing inner ring or at the radially outer side of the bearing inner ring.

[0009] DE 10 2018 2016 21 (A1) proposes a floating sealing plate for a bearing as mentioned at the outset, which contacts the abutment surface in a floating state.

[0010] DE 10 2018 212 721 (A1) proposes a slidable sealing plate for a bearing as mentioned at the outset.

[0011] DE 102005012277 (A1) discloses a bearing arrangement with a hollow cylindrical or cylindrical body and a ring-shaped sealing element.

[0012] JP2004-19722(A) discloses a rolling bearing with a sealing lip which, together with a bearing ring, forms a kind of labyrinth seal.

[0013] Thus, in rolling bearings as mentioned at the outset, a seal is provided which releases the air flow resulting from overpressure during operation of the rolling bearing to the surroundings. When the device with the bearing is used, this escaping compressed air hits a liquid or a surface wetted by a liquid, which can generate aerosols which escape into the surrounding space. If this aerosol is infectious, then people in the surrounding space are at risk of infection. For example, the liquid can be saliva from the mouth of a patient who may be infected with a virus, which is then dispersed together with the aerosol into the air of the surrounding space, since the virus is also present in the saliva. Furthermore, the escaping compressed air can cause emphysema.

[0014] The object of the present invention is therefore to improve a rolling bearing for a medical or cosmetic instrument, in particular a hand-held instrument, in such a way that the above-mentioned risk of infection and / or the risk of emphysema occurring is reduced, preferably such that existing rolling bearings can be easily extended with the solution according to the invention.

[0015] The problem according to the invention is solved by a rolling bearing with the features of claim 1. The dependent claims describe advantageous and particularly preferred embodiments of the invention. Furthermore, a medical or cosmetic device with such a rolling bearing is disclosed as well as a method for mounting a cover disk on such a rolling bearing.

[0016] The rolling bearing according to the invention for a medical or cosmetic device has an inner bearing ring rotating about a rotation axis and a fixed outer bearing ring concentrically surrounding the inner bearing ring. A bearing gap is formed between the inner and outer bearing rings in the radial direction relative to the rotation axis, and a number of rolling elements are arranged one behind the other in the circumferential direction in this bearing gap, with the inner bearing ring being supported by the outer bearing ring via these rolling elements.

[0017] The rolling elements are arranged to roll on the inner and outer bearing rings and have a rolling element height in the radial direction, which, if the rolling elements are spheres, corresponds to the outer diameter of the spheres.

[0018] According to the invention, the bearing gap is covered in the axial direction by a cover disk which is attached to the outer bearing ring or is formed integrally with it, and which together with the inner bearing ring forms a radial gap which extends in the axial direction over a gap length and which has a gap height in the radial direction. Alternatively, the cover disk can also be attached to a casing which receives the outer bearing ring or is formed integrally with it. The attachment is usually arranged in the immediate vicinity of the axial end of the outer bearing ring.

[0019] According to the invention, the gap length is at least 25% of the rolling element height, preferably at least 50% of the rolling element height.

[0020] Due to the size of the gap length relative to the rolling element height, the cover disk can reduce the flow of air out of the interior of the rolling bearing in a medical or cosmetic device, so that the risk of infection due to aerosol formation and / or the risk of emphysema formation as mentioned at the beginning can be significantly minimized, and different heights of rolling elements can be applied to different types of rolling bearings. The inventors therefore realized that a rolling element height of, for example, only 0.5-3 mm, in particular 0.8-1.2 mm, for example 1 mm, has a decisive influence on the air flow rate through the rolling bearing, and that the greater the rolling element height, the greater the air flow rate, so that in accordance with the invention a correspondingly larger gap length is provided in order to reduce the air flow rate.

[0021] The radial gap is preferably consistently open towards the surroundings, i.e. it is not closed by a further sealing element or a further sealing plate, in particular on the outlet side, in either the stationary or rotating state of the bearing inner ring.

[0022] Preferably, on the axial side opposite the rolling body side in the axial direction, no further seal or cover member faces the radial gap.

[0023] Preferably, the maximum height of the gap height is at most 20% of the rolling element height with respect to the radius of the rolling bearing. The minimum height of the gap height is preferably greater than the operating play between the inner bearing ring and the outer bearing ring at the operating temperature of the rolling bearing, so that the operating play is formed by the play between the inner bearing ring and the rolling elements and the play between the rolling elements and the outer bearing ring. This minimum gap height, on the one hand, avoids undesirable contact between the cover disc and the inner bearing ring, and on the other hand, effectively minimizes the passage of air in the rolling bearing on the side of the cover disc.

[0024] It is preferred if the gap length of the radial gap between the cover disc and the bearing inner ring is limited to two or three times the rolling element height. Gap lengths exceeding this have been found to be structurally cumbersome and less effective than shorter gap lengths. Rather, to prevent starting, a long gap length would require a larger radial gap, which would be counterproductive.

[0025] Particularly preferably, the cover disk is attached to the axial end face of the bearing outer ring. The attachment can be, for example, a materially connected attachment, in particular a welding, adhesive or vulcanization attachment. However, a positively or force-locking connection is also conceivable.

[0026] According to a special embodiment of the invention, the cover disk, at its axial end, radially surrounds the outer peripheral surface of the bearing outer ring and is attached to the radially outer surface of the bearing outer ring, in particular in a radial recess of the bearing outer ring with an open or closed edge. The attachment can again be materially connected or force-connected (friction-connected and / or form-connected). For example, attachment by welding, adhesive bonding, interference fitting, clipping or mechanical snapping (elastic form-connected or clamping with the aid of an undercut and a circlip in the bearing outer ring is also conceivable.

[0027] According to one embodiment of the invention, the cover disk, when viewed in an axial section through the axis of rotation, is L-shaped on both sides of the axis of rotation, with a radial leg arranged on the bearing outer ring and an axial leg forming a radial gap. This makes it possible to achieve a solution that is particularly compact in construction and can be easily retroactively installed in existing bearings or in existing bearing environments. Preferably, the axial legs start from the radial legs and extend only in the direction of the rolling elements, i.e. only in the direction of the bearing interior.

[0028] According to an alternative embodiment, the cover disk, when viewed in an axial section through the rotation axis, is T-shaped on both sides of the rotation axis, with a radial leg arranged on the outer bearing ring and an axial leg forming a radial gap, whereby the axial legs start from the radial leg and extend in both axial directions, and can be partly arranged inside the space between the inner and outer bearing rings and partly outside the space between the inner and outer bearing rings. In principle, it is also conceivable to arrange them completely in the corresponding spaces.

[0029] With the T-shaped solution, particularly large gap lengths can be easily achieved without the risk of the axial legs being undesirably bent or broken off due to an excessively large free length.

[0030] According to one embodiment, in the T-shaped configuration of the cover disk, the portion of the axial leg starting from the radial leg and extending in the direction of the rolling elements, i.e. towards the inside of the bearing, may be longer than the portion of the axial leg starting from the radial leg and extending in the circumferential direction, i.e. away from the rolling elements.

[0031] According to a preferred embodiment of the invention, the cover disk, as viewed in an axial section about the axis of rotation, comprises a radially extending radial leg arranged on the outer ring of the bearing and an axial leg extending axially in the step and forming a radial gap in the step. The axial leg thus extends with two parts of different diameters. The axial leg has a first axial part forming part of the radial gap together with the shaft supported on the inner ring of the bearing and a second axial part forming part of the radial gap together with the inner ring of the bearing, the two parts of the radial gap being radially offset from one another, i.e. arranged on different diameters. A particularly effective seal can thus be achieved.

[0032] According to one embodiment of the invention, in order to achieve a sealing air curtain in the radial gap, the cover disk can be provided with at least one hole extending in the radial direction or inclined to the axial direction, which hole opens into the radial gap within the gap length, so that air can flow from the bearing gap through the at least one hole into the radial gap and form the desired sealing air curtain. Preferably, a number of corresponding holes are provided, which are arranged one after the other in the circumferential direction and are arranged next to one another at regular or irregular intervals, in particular at equal intervals.

[0033] According to a particularly preferred embodiment of the invention, if a gap length of at least 50% of the rolling element height is provided, the air leakage can be reduced very effectively and, moreover, can be realized very easily in terms of construction, and at the same time, can be easily retroactively installed in existing rolling bearings.

[0034] According to an embodiment of the invention, the gap height varies over the gap length. In the direction of flow of the medium through the bearing, as viewed from the rolling elements, the cross-sectional area of ​​the gap preferably increases. In particular, in the direction of flow (away from the rolling elements), the gap height increases over the gap length, in particular linearly when viewed in an axial section through the axis of rotation. For example, the radial gap height becomes progressively smaller in the direction towards the inside of the bearing, i.e. in the direction of the rolling elements.

[0035] According to one embodiment, the cover disk is elastically deformable in the axial direction, at least in the region of the end associated with the bearing inner ring, so that in the stationary state of the rolling bearing, in which there is no pressure difference across the cover disk, a stronger seal can be achieved than when the rolling bearing is in operation.

[0036] Preferably, the cover disk is located on a step or end face of the inner bearing ring when the rolling bearing is stationary, and is suspended from the step or end face when the inner bearing ring rotates due to a pressure difference applied to the cover disk.

[0037] In order to produce an even better sealing effect, the cover disk and / or the inner bearing ring have a conveying contour in contact with the radial gap, which allows for an air conveyance of the air present in the radial gap in the direction of the inside of the bearing, i.e. in the direction of the rolling elements. For example, this conveying contour comprises narrow grooves, recesses and / or protrusions in the surface of the cover disk and / or the inner bearing ring in contact with the radial gap. In particular, helical grooves or helical protrusions are conceivable. However, other groove shapes are also conceivable, for example individual circumferential grooves arranged next to each other in the axial direction (direction of the rotation axis), which can extend in the axial section, for example perpendicularly or inclined to the rotation axis.

[0038] In particular, if in the rolling bearing according to the invention the radial gap is provided with a step, i.e. the radial gap starts from a first diameter and extends radially outward to a second diameter, then a conveying contour can also be formed at the step on the surface of the cover disk and / or on the opposing surface of the inner bearing ring, which conveys the air radially outwardly back into the interior of the rolling bearing.

[0039] According to one embodiment of the invention, a cover disk is inserted radially inwardly into the bearing outer ring, which prevents a flow of forces through the cover disk into the housing that accommodates the bearing outer ring if the rolling bearing is designed as a separable ball bearing, for example a flow of forces that occurs when adjusting the rolling bearing in the axial direction. In particular, if the cover disk is welded to the bearing outer ring, the weld seam prevents a corresponding flow of forces.

[0040] According to an advantageous embodiment, the bearing outer ring has radially inwardly, i.e. on its radially inwardly directed surface, a radial groove that is open at its edge, into which the cover disk is inserted, which allows for a particularly good centering of the cover disk on the bearing outer ring, for example before it is welded to the bearing outer ring, in particular without the need for additional centering tools.

[0041] According to a preferred embodiment of the invention, an additional cover disk is provided on the axial side of the rolling bearing opposite to the cover disk side, which together with the bearing inner ring forms a second radial gap, i.e. defines a radial gap. Such an additional cover disk in particular reduces the air flow into the rolling bearing. This cover disk can also be attached to the bearing outer ring or formed in one piece with the bearing outer ring. In particular, the cover disk is welded to the bearing outer ring.

[0042] If the rolling bearing is designed as a single-row ball bearing in the form of a separable ball bearing, a shoulder is preferably provided on the outer bearing ring on the axial side of the cover disk and a shoulder is provided on the inner bearing ring on the axial side opposite the cover disk, so that an axial adjustment of the bearing can be achieved with an oblique force flow from the axial side of the inner bearing ring opposite the cover disk in the direction of the axial side of the outer bearing ring with the cover disk.

[0043] The medical or cosmetic device according to the invention comprises a rotating shaft for accommodating or with a tool and a bearing as described herein, the medical device being configured as a handheld dental device, for example, on which a dental tool is supported or can be supported.

[0044] In order to be able to adjust the gap size according to the invention as accurately as possible, in the method for mounting a cover disk on a rolling bearing according to the invention, the cover disk is placed on the inner bearing ring in the radial gap by means of spacers and is thereby centered relative to the inner bearing ring, and then in the centered state the cover disk is fixed to the outer bearing ring or to the casing, so that only in the fixed state are the spacers removed from the radial gap.

[0045] As spacers, for example, sheets having a certain thickness can be used, which are inserted into the radial gap. In particular, the sheet is first applied to the inner bearing ring in the area that will later define the radial gap. A cover disk can then be slid onto the sheet and thereby centered. Finally, the cover disk can be fixed to the outer bearing ring or the casing, and the sheet can be removed.

[0046] Particularly preferably, the cover disk has a shape that allows it to be easily retrofitted to existing rolling bearings without colliding with the existing bearing components. Alternatively, the geometry of the existing bearing components can be adapted. For example, the bearing inner ring can be provided at its axial end with a recess, which is open, in particular at the edge, into which the cover disk fits. In another embodiment, the structural space that is present anyway between the bearing outer ring and the bearing inner ring can be used for the insertion of the cover disk, for example when the rolling bearing has a so-called cage cage.

[0047] The present invention is applicable to various types of rolling bearings, separable ball bearings and groove ball bearings being only two examples.

[0048] As a material for the cover disk, for example, corrosion-resistant steel (especially 1.4301 or 1.4305) is suitable. Other advantageous materials are the sterilization-resistant polymers PEEK or PTFE.

[0049] Advantageously in medical or cosmetic devices, the cover disk provided on the axially outer side of the bearing located near the tool or tool receptacle can be a single cover disk of a rolling bearing. According to one alternative embodiment, a cover disk is also provided on the opposite side of the rolling bearing, which can be plate-like or have the shape shown in the present description. Other shapes are also possible.

[0050] According to one alternative embodiment, the cover disk provided on the axial inner side of the bearing of the medical or cosmetic device, which is located near the tool or the tool housing, can be a single cover disk of a rolling bearing. This limits the air inflow into the bearing and thus indirectly limits the air outflow from the bearing. According to one alternative embodiment, a cover disk is also provided on the opposite side of the rolling bearing, which can be plate-shaped or have the shape shown in the present description. Other shapes are also conceivable.

[0051] The invention will now be described by way of example only with reference to examples and drawings. [Brief description of the drawings]

[0052] [Figure 1] 1 shows an exemplary diagram of a dental handpiece which may be provided with at least one rolling bearing according to the invention; [Diagram 2] 1 shows an embodiment of a rolling bearing according to the present invention. [Diagram 3] 3 shows another embodiment of a rolling bearing according to the present invention. [Figure 4] 3 shows another embodiment of a rolling bearing according to the present invention. [Diagram 5] 3 shows another embodiment of a rolling bearing according to the present invention. [Figure 6] 3 shows another embodiment of a rolling bearing according to the present invention. [Figure 7] 3 shows another embodiment of a rolling bearing according to the present invention. [Figure 8] 3 shows another embodiment of a rolling bearing according to the present invention. [Figure 9] 3 shows another embodiment of a rolling bearing according to the present invention. [Figure 10] 3 shows another embodiment of a rolling bearing according to the present invention. [Figure 11] 3 shows another embodiment of a rolling bearing according to the present invention. [Figure 12] 3 shows another embodiment of a rolling bearing according to the present invention. [Figure 13] 3 shows another embodiment of a rolling bearing according to the present invention. [Figure 14] 3 shows another embodiment of a rolling bearing according to the present invention. [Figure 15] 3 shows another embodiment of a rolling bearing according to the present invention. [Figure 16] 3 shows another embodiment of a rolling bearing according to the present invention. [Figure 17] 3 shows another embodiment of a rolling bearing according to the present invention. [Figure 18]1 shows a spacer in the radial gap for mounting a cover disk in a rolling bearing. [Figure 19] 3 shows another embodiment of a rolling bearing according to the present invention. [Figure 20] 3 shows another embodiment of a rolling bearing according to the present invention. [Figure 21] 3 shows another embodiment of a rolling bearing according to the present invention. [Figure 22] 22 shows details of X shown in FIGS. 19 to 21.

[0053] 1 shows an exemplary cross-sectional view of a dental hand-held instrument, in which only the front part of a casing 11, also called head casing, is visible, in which a shaft 12 is rotatably supported about a rotation axis 5 by means of rolling bearings 13, 14. A rotor 15 in the form of a turbine is attached to the shaft 12, which is driven by compressed air. A tool 16 can be attached to the axial end of the shaft 12. The rolling bearing 13, which is preferably arranged on the tool side, can be provided with a cover disk according to the invention.

[0054] Figures 2 to 21 show different embodiments of a rolling bearing according to the invention, for example the rolling bearing 13 in Figure 1. Each rolling bearing preferably has a cover disk 6, which on the side facing the tool 16 in Figure 1 is provided with a radial leg or an axial leg 10 which is continuous with a radial leg 9. In principle, in order to reduce air inflow into the rolling bearing 13, a cover disk 6 can also be provided on the side of the rolling bearing 13 opposite the tool 16.

[0055] The radial legs 9 are attached to the outer bearing ring 2 of the rolling bearing, and the axial legs 10 face at least the radially outer surface of the inner bearing ring 1 in such a way that the inner bearing ring 1 together with the cover disc 6 forms a radial gap 7 with a gap length L in the axial direction and a gap height H in the radial direction.

[0056] The cover disk 6 covers in the axial direction the bearing gap 3 between the inner bearing ring 1 and the outer bearing ring 2. In the bearing gap 3, rolling elements 4 of a rolling bearing are supported, which roll on the radially inner surface of the outer bearing ring 2 and on the radially outer surface of the inner bearing ring 1, so that the inner bearing ring 1, which rotates about the rotation axis 5, is supported via the rolling elements 4 on the stationary outer bearing ring 2.

[0057] The rolling elements 4 have, in the radial direction, a rolling element height WH, which in the dental handheld instrument shown in FIG. 1 can be, for example, only 1 mm.

[0058] According to the invention, the gap length L is at least 25% of the rolling element height WH.

[0059] In the embodiment shown here, the gap length L is preferably at least 50%, in particular 70% or more, of the rolling element height WH.

[0060] The minimum height of the gap height H is preferably greater than the operating play between the inner bearing ring 1 and the outer bearing ring 2 when the rolling elements 4 are present, so that the operating play measured at the operating temperature of the rolling bearing results from the mobility of the inner bearing ring 1 relative to the rolling elements 4 and the mobility of the rolling elements 4 relative to the outer bearing ring 2, in particular in the radial direction.

[0061] The maximum height of the gap height H is advantageously at most 20% of the rolling element height WH.

[0062] Preferably, as can be seen from figures 2 to 22, the bearing gap 3 is open in the axial direction with nothing around it, which means that no additional cover disks, cover elements or sealing plates are provided which partially or completely cover the bearing gap 3 in the axial direction.

[0063] 2 to 5, the cover disk, when viewed in an axial section through the axis of rotation 5, is L-shaped, with reference to each half of this axial section on one side of the axis of rotation 5. The axial leg 10 therefore extends completely only on the axial side of the radial leg 9.

[0064] The axial leg 10 can be provided with holes 6.1. Compressed air can flow from the bearing gap 3 radially inwardly through the holes 6.1 into the radial gap 7, so that the holes 6.1 create a sealing air curtain in the bearing gap 7. The holes 6.1 can run inclined to the axial / radial direction or perpendicular to the axis of rotation 5. Preferably, several corresponding holes 6.1 are arranged adjacent to each other in the circumferential direction about the axis of rotation 5.

[0065] In the embodiment according to Fig. 6, the cover disk 6, when viewed in an axial section through the axis of rotation 5, is T-shaped on both sides of the axis of rotation 5, with the radial legs 9 also extending radially and the axial legs 10 also extending axially. However, here the axial legs 10 extend on both sides of the radial legs 9 in the axial direction.

[0066] 2 to 6, if the axial legs 10 extend only in the axial direction, i.e. parallel to the axis of rotation 5, in the illustrated axial cross section through the axis of rotation 5, the radial gaps 7 can be formed with different heights H if the radially outer surface of the inner bearing ring 1 preferably tapers in the direction of its axial end. Alternatively, however, the radial gap 7 can also be provided with a constant gap height H over the gap length L by corresponding parallel, mutually facing surfaces of the cover disc 6 and the inner bearing ring 1, which surfaces can then be arranged either parallel to the axis of rotation 5 or inclined to it in the illustrated axial cross section.

[0067] In the configuration according to FIG. 3, it is further shown that an additional cover disk 18 can be provided on the side of the rolling bearing opposite the cover disk 6, which additional cover disk 18 reduces the inflow of air into the rolling bearing. This cover disk 18 can also be attached to the outer bearing ring 2 or formed in one piece therewith and can form, together with the inner bearing ring 1, the second radial gap or the second radial gap 7'. Alternatively, the additional cover disk 18 is connected to the inner bearing ring 1 or is formed in one piece therewith, so that due to the rotation of the inner bearing ring 1 it conveys the air radially outwards so that no air or only very little air flows into the bearing gap 3.

[0068] In the configuration according to Fig. 7 and Fig. 8, the cover disk 6 has, in addition to the radial leg 9, an axial leg 10 with two axial portions 10.1 and 10.2 at different diameters, whereby a stepped radial gap 7 is formed. The first axial portion 10.1 together with the radially outer surface of the shaft 12 forms an axial part of the radial gap 7. For this purpose, the first axial portion 10.1 is connected to the radial leg 9 on the side facing the bearing gap 3 and away from the rolling elements 4. The second axial portion 10.2 is connected to the radial leg 9 on the side facing the rolling elements 4 and forms, together with the radially outer surface of the bearing inner ring 1, a part of the radial gap 7. The two parts of the radial gap 7 are interconnected by a radial portion of the radial gap 7. The radial portion is formed by the end face 1.1 of the bearing inner ring 1 and the facing surface of the cover disk 6, for example the surface of the radial leg 9. This step further reduces the flow of compressed air through the radial gap 7 .

[0069] The configuration according to Fig. 8 corresponds approximately to the configuration according to Fig. 7. However, the axial end portion of the inner bearing ring 1 facing the second axial portion 10.2 of the axial leg 10 is inclined relatively strongly to the axis of rotation 5, so that the radial gap 7 decreases relatively strongly over the course towards the inside of the bearing, i.e. in the direction of the rolling elements 4.

[0070] 9, like the other embodiments shown here, shows a radial recess or radial recess 8 at one axial end of the bearing outer ring 2, which can advantageously accommodate a sealing and / or damping element, for example in the form of a rubber ring, advantageously an O-ring, for supporting the bearing outer ring 2 against the casing. Despite the provision of this radial recess 8, the cover disk 6 is attached to the axial end face of the bearing outer ring 2 and does not engage around the circumference of the bearing outer ring 2.

[0071] In the embodiments according to FIGS. 2 to 9 and 19 to 21, the rolling elements 4 are guided in the inner bearing ring 1 only on one side in the axial direction, whereas the outer bearing ring 2 engages with the rolling elements 4 on both sides in the axial direction. In the configuration according to FIG. 10, this is reversed; the bearings are thus preferably separable ball bearings in each case. In order to achieve an axial adjustment of the ball bearing by means of an oblique force flow by the rolling elements 4, the ball bearings can also be designed as angular contact ball bearings. This means that the rolling elements 4 are accordingly guided in the axial direction only on one side of the outer bearing ring 2, and only on the axial side opposite to the guide in the inner bearing ring 1.

[0072] Furthermore, in the configuration according to Fig. 10, the inner bearing ring 1 forms a step 1.2, so that the radial gap 7 has a radially extending portion, which is, however, not formed here by the end face 1.1 of the inner bearing ring 1. However, the end face 1.1 may also be provided with a further step.

[0073] According to one embodiment, a corresponding axial gap always remains between the axial end of the step 1.2 and the cover disk 6. According to a further embodiment, the cover disk 6 is elastically deformable and in the stationary state of the bearing, the cover disk 6 rests against the step 1.2.

[0074] The configuration according to Fig. 11 corresponds substantially to the configuration according to Fig. 10, but here the rolling elements 4 are engaged on both sides in the axial direction by the inner bearing ring 1 and the outer bearing ring 2, i.e. preferably a groove ball bearing. The configuration of the cage 19 in which the rolling elements 4 are held is also different from that of the previously described embodiment. That is, the cage 19 is configured as a crown cage and surrounds the rolling elements 4 only on one axial side, unlike the previously described embodiment in which the rolling elements 4 are held by the cage 19 on both sides in the axial direction. However, these details are not essential.

[0075] According to Fig. 12, the cover disk 6 engages at its axial end into the bearing outer ring 2 and reaches up into the radial recess 8. In this case, the cover disk 6 is pressed against the bearing outer ring 2, for example radially outward.

[0076] In the design according to FIG. 13, a circumferential groove 20 is provided in the radial recess 8, into which the cover disk 6 engages radially from the outside in a form-locking manner.

[0077] 14, when the rolling bearing is at rest, the cover disc 6 rests with its axial leg 10 against the step 1.2 at the end face of the inner bearing ring 1. In operation, due to a pressure difference, the cover disc 6 is elastically deformed, so that the contact between the cover disc 6 and the inner bearing ring 1 is eliminated.

[0078] In the configuration according to FIG. 15, the cover disk 6 is arranged at the other equivalent axial end of the rolling bearing in comparison with the other illustrated embodiments. This may be the inner end of the rolling bearing 13 in FIG. 1. This configuration therefore reduces the inflow of air into the rolling bearing, so that the outflow of air from the rolling bearing can also be reduced accordingly at the outer end. The cover disk 6 can be designed in various ways, as explained above. At the end opposite to the cover disk 6, an additional cover disk 18 is provided, which is fixed, for example, by means of a snap ring 21 in a recess in the bearing outer ring 2.

[0079] However, it is also possible to arrange the rolling bearing according to Fig. 15, for example in the hand-held tool shown in Fig. 1, in such a way that the cover disc 6 is positioned on the tool side and the additional cover disc 18 is positioned on the opposite side to the tool 16, thereby correspondingly reversing the functions of the two cover discs 6, 18. In this case, the additional cover disc 18 will reduce the inflow of air into the bearing gap 3 and the cover disc 6 will reduce the outflow of air from the bearing gap 3.

[0080] 16, the rolling elements 4 are again surrounded on both sides in the axial direction by the inner bearing ring 1 and the outer bearing ring 2 to form a groove ball bearing. Here too, in addition to the cover disc 6, an additional cover disc 18 is provided, which is here attached to the axial end face of the outer bearing ring 2, for example by means of a material connection.

[0081] In the configuration according to FIG. 17, not only does the cover disk 6 form a radial gap 7 with a corresponding gap length, but the additional cover disk 18 also has axial legs 10 for forming a corresponding gap length of the radial gap 7'.

[0082] Accordingly, for the additional cover disc 18, what has been explained above for the cover disc 6 applies, with the design being modifiable accordingly.

[0083] 18 shows diagrammatically that when the cover disk 6 is mounted on the rolling bearing, a spacer 17, for example in the form of a sheet, having a thickness corresponding to the radial gap 7 to be adjusted, is applied to the inner bearing ring 1 on the radial outside. The cover disk 6 together with the spacer 17 is placed in the radial gap, rests on the inner bearing ring 1 and is thereby centered relative to the inner bearing ring 1. The cover disk 6 is then fixed in the centered state to the outer bearing ring 2, and only afterwards is the spacer 17 removed from the radial gap 7.

[0084] In the embodiment according to Figures 19 to 21, a cover disk 6 is inserted radially inside the bearing outer ring 2. Preferably, as can be seen in particular from detail X shown in Figure 22, the bearing outer ring 2 has a radially inner radial groove 22 that is open at its edge, into which the cover disk 6 is inserted.

[0085] Between the bearing outer ring 2 and the cover disk 6, particularly in the radial groove or radial groove 22, radial play can be provided before the cover disk 6 is welded to the bearing outer ring 2, so that the cover disk 6 can be centered relative to the bearing inner ring 1 in order to form a constant radial gap 7 over the circumferential surface of the bearing inner ring 1.

[0086] 21, an additional cover disk 18 is also provided at the axial end of the outer bearing ring 2 opposite the axial end provided with the cover disk 6, which additional cover disk 18 forms, together with the inner bearing ring 1, a second radial gap 7' which prevents or reduces the inflow of air into the rolling bearing.

[0087] In the configuration according to FIG. 20, the axial leg 10 of the cover disk 6 is provided with a hole 6.1, the function of which is, for example, that explained above with reference to FIG.

[0088] Moreover, the embodiment according to FIGS. 20 and 21 corresponds to the embodiment of FIG.

[0089] 19 to 21, the cover disk 6 is also preferably L-shaped, with the axial leg 10 preferably starting from the radial leg 9 and running in the direction of the rolling elements 4. The radial gap 7 can be tapered, for example, by orienting the radially outer surface of the bearing inner ring 1 facing the axial leg 10 with a slight incline.

[0090] 19 to 21, the rolling bearing can also be configured as a separable ball bearing, with the outer bearing ring 2 having a shoulder 23 on the axial side facing the cover disc 6 and the inner bearing ring 1 having a shoulder 23 on the axial side facing away from the cover disc 6. Furthermore, the outer bearing ring 2 is provided with a shoulder 23 on the axial side facing away from the cover disc 6. This shoulder 23 can be omitted if the rolling bearing is configured as an angular contact ball bearing.

[0091] The shoulder 23 creates an oblique force flow from the inner bearing ring 1 via the rolling elements 4 to the outer bearing ring 2 .

[0092] Even in the configuration with a cover disk 6 inserted radially inside into the bearing outer ring 2, the bearing outer ring 2 can have a radial recess 8, in particular a radial recess 8 that is open at the edge, preferably at the axial end, in which a sealing element and / or a damping element, for example in the form of a rubber ring, advantageously an O-ring, can be advantageously accommodated in order to support the bearing outer ring 2 relative to the casing. [Explanation of symbols]

[0093] 1 Bearing inner ring 1.1 End face 1.2 Stepped section 2 Bearing outer ring 3 Bearing clearance 4 Rolling elements 5 Rotation axis 6 Cover Disc 6.1 hole 7 Radial clearance 7' Second radial gap 8 Radial recess 9 Radial legs 10 Axial legs 10.1 First axial portion 10.2 Second axial portion 11 Casing 12 Axis 13 Rolling bearings 14 Rolling bearings 15 Rotor 16 Tools 17 Spacer 18 additional cover discs 19 Cage 20 Circumferential groove 21 Snap ring 22 Radial groove 23 Shoulder H Gap height L gap length WH Rolling element height

Claims

1. 1.1 A bearing comprising an inner bearing ring (1) that rotates around a rotation axis (5) and a fixed outer bearing ring (2) that concentrically surrounds the inner bearing ring (1), 1.2 A bearing gap (3) is formed between the inner bearing ring (1) and the outer bearing ring (2) in a radial direction relative to the rotation axis (5), a plurality of rolling elements (4) are arranged one behind the other in the circumferential direction in the bearing gap (3), and the inner bearing ring (1) is supported by the outer bearing ring (2) via the rolling elements (4), 1.3 The rolling elements (4) are arranged to roll on the inner bearing ring (1) and the outer bearing ring (2) and have a rolling element height (WH) in the radial direction, 1.4 The bearing gap (3) is covered in the axial direction by a cover disk (6) attached to the bearing outer ring (2) or to a casing (11) which accommodates the bearing outer ring (2) or which is formed integrally with the casing (11) or the bearing outer ring (2), the cover disk (6) forming, together with the bearing inner ring (1), a radial gap (7) which extends in the axial direction over a gap length (L), the radial gap (7) having a gap height (H) in the radial direction, The gap length (L) is at least 25% of the rolling element height (WH), The gap height (H) decreases over the gap length (L) from the axially outer end of the cover disc (6) in the direction of the rolling elements (4) and decreases linearly as viewed in an axial section passing through the rotation axis (5). A rolling bearing for a medical or cosmetic device, comprising:

2. 2. The rolling bearing according to claim 1, wherein the maximum height of the gap height (H) is a maximum of 20% of the rolling element height (WH).

3. 3. The rolling bearing according to claim 1, wherein the gap length (L) is at most two or three times the rolling element height (WH).

4. 4. Rolling bearing according to claim 1, characterized in that the minimum height of the gap height (H) is greater than the operating play between the inner bearing ring (1) and the outer bearing ring (2) at the operating temperature of the rolling bearing.

5. 5. Rolling bearing according to claim 1, characterized in that the cover disk (6) is attached to the axial end face of the bearing outer ring (2) and is attached by material connection.

6. 6. The rolling bearing according to claim 1, wherein the cover disk (6) is mounted in a radially open or closed radial recess (8) at an edge portion, which is an axial end portion, of the radially outer surface of the bearing outer ring (2) and surrounds the bearing outer ring (2).

7. 7. The rolling bearing according to claim 1, wherein the cover disk (6) is L-shaped with radial legs (9) arranged on the bearing outer ring (2) and axial legs (10) forming the radial gap (7) on either side of the rotation axis (5) as viewed in an axial section through the rotation axis (5).

8. 8. Rolling bearing according to claim 7, characterized in that the axial leg (10) starts from the radial leg (9) and extends only in the direction of the rolling elements (4).

9. 7. The rolling bearing according to claim 1, wherein the cover disk (6) is T-shaped with radial legs (9) arranged on the bearing outer ring (2) on both sides of the rotation axis (5) as viewed in an axial section through the rotation axis (5) and with axial legs (10) forming the radial gap (7).

10. 7. The rolling bearing according to claim 1, wherein the cover disk (6), when viewed in an axial section through the axis of rotation (5), has, on both sides of the axis of rotation (5), radial legs (9) which extend radially and are arranged on the bearing outer ring (2) and axial legs (10) which extend axially in the step (1.2) and form the radial gap (7) in the step (1.2).

11. The radial gap (7) is formed between a shaft (12) supported by the bearing inner ring (1) and the bearing inner ring (1), said axial leg (10) having a first axial portion (10.1) forming part of said radial gap (7) with said shaft (12) and a second axial portion (10.2) forming part of said radial gap (7) with said bearing inner ring (1); 11. Rolling bearing according to claim 10, characterized in that the first axial portion (10.1) and the second axial portion (10.2) are radially offset from one another.

12. 12. The rolling bearing according to claim 1, wherein the cover disk (6) has one hole (6.1) extending radially or at an angle to the axial direction or has a number of holes (6.1) arranged one behind the other in the circumferential direction and extending radially or at an angle to the axial direction, the holes (6.1) opening into the radial gap (7) within the gap length (L).

13. 13. Rolling bearing according to claim 1, characterized in that the gap length (L) is at least 50% of the rolling element height (WH).

14. 14. Rolling bearing according to claim 1, characterized in that the rolling elements (4) are spherical and the rolling element height (WH) corresponds to the outside diameter of the rolling elements (4).

15. Rolling bearing according to any one of the preceding claims, characterized in that the gap height (H) is constant over the gap length (L).

16. 16. Rolling bearing according to claim 1, characterized in that the cover disk (6) is elastically deformable in the axial direction at least in the region of its end associated with the inner bearing ring (1).

17. 17. The rolling bearing according to claim 16, characterized in that in the stationary state of the rolling bearing, the cover disk (6) is arranged on a step (1.2) or an end face (1.1) of the inner bearing ring (1) and, during rotation of the inner bearing ring (1), is suspended from the step (1.2) or the end face (1.1) due to a pressure difference across the cover disk (6).

18. 18. The rolling bearing according to claim 1, wherein the cover disk (6) and / or the bearing inner ring (1) have a conveying contour in contact with the radial gap (7) which enables air conveyance of the air present in the radial gap (7) in the direction of the rolling bodies (4).

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