Bearing for a Medical or Cosmetic Instrument

Abstract

The disclosure relates to a rolling bearing for a medical or cosmetic instrument having a bearing inner ring revolving around an axis of rotation and a stationary bearing outer ring, which concentrically encloses the bearing inner ring; wherein in the radial direction to the axis of rotation, a bearing gap is formed between the bearing inner ring and the bearing outer ring and a plurality of rolling bodies is arranged in succession in the circumferential direction in the bearing gap, via which the bearing inner ring is mounted in the bearing outer ring; wherein the rolling bodies are arranged rolling on the bearing inner ring and the bearing outer ring and have a rolling body height in the radial direction; and the bearing gap is covered in the axial direction by a cover disk, which is fastened on the bearing outer ring or on a housing accommodating the bearing outer ring or is integrally formed with the housing or the bearing outer ring, and which jointly with the bearing inner ring forms a radial gap extending in the axial direction with a gap length, which gap has a gap height in the radial direction.

The rolling bearing according to the invention disclosure is characterized in that the gap length is at least 25% of the rolling body height.

Claims

1. A rolling bearing for a medical or cosmetic instrument having a bearing inner ring revolving around an axis of rotation and a stationary bearing outer ring, which concentrically encloses the bearing inner ring; wherein in the radial direction to the axis of rotation, a bearing gap is formed between the bearing inner ring and the bearing outer ring and a plurality of rolling bodies is arranged in succession in the circumferential direction in the bearing gap, via which the bearing inner ring is mounted in the bearing outer ring; wherein the rolling bodies are arranged rolling on the bearing inner ring and the bearing outer ring and have a rolling body height in the radial direction; and the bearing gap is covered in the axial direction by a cover disk, which is fastened on the bearing outer ring or on a housing accommodating the bearing outer ring or is integrally formed with the housing or the bearing outer ring, and which, jointly with the bearing inner ring, forms a radial gap extending in the axial direction with a gap length, which gap has a gap height in the radial direction; characterized in that the gap length is at least 25% of the rolling body height.

2. The rolling bearing according to claim 1, characterized in that a maximum extension of the gap height is at most 20% of the rolling body height.

3. The rolling bearing according to claim 1, characterized in that the gap length is at most twice or at most three times the rolling body height.

4. The rolling bearing according to claim 1, characterized in that a minimum extension of the gap height is greater than an operating clearance between the bearing inner ring and the bearing outer ring at operating temperature of the rolling bearing.

5. The rolling bearing according to claim 1, characterized in that the cover disk is fastened, in particular fastened by material bonding, frontally on the bearing outer ring.

6. The rolling bearing according to claim 1, characterized in that the cover disk encloses the bearing outer ring radially outside and is fastened on a radial outer surface of the bearing outer ring, in particular in an edge-open or edge-closed radial recess of the bearing outer ring.

7. The rolling bearing according to claim 1, characterized in that the cover disk, viewed in an axial section through the axis of rotation, is L-shaped on both sides of the axis of rotation having a radial leg arranged on the bearing outer ring and an axial leg forming the radial gap.

8. The rolling bearing according to claim 7, characterized in that the axial leg extends exclusively in the direction of the rolling bodies starting from the radial leg.

9. The rolling bearing according to claim 1, characterized in that the cover disk, viewed in an axial section through the axis of rotation, is T-shaped on both sides of the axis of rotation having a radial leg arranged on the bearing outer ring and an axial leg forming the radial gap.

10. The rolling bearing according to claim 1, characterized in that the cover disk, viewed in an axial section through the axis of rotation, on both sides of the axis of rotation, has in each case a radial leg extending in the radial direction and arranged on the bearing outer ring and an axial leg extending in steps in the axial direction and forming the radial gap in steps.

11. The rolling bearing according to claim 10, characterized in that the axial leg has a first axial section, which forms a section of the radial gap together with a shaft mounted in the bearing inner ring, and a second axial section, which forms a section of the radial gap together with the bearing inner ring, wherein the two sections of the radial gap are offset to one another in the radial direction.

12. The rolling bearing according to claim 1, characterized in that the cover disk has a bore extending in the radial direction or diagonally to the axial direction or a plurality of bores arranged in succession in the circumferential direction and extending in the radial direction or diagonally to the axial direction, which open inside the gap length in the radial gap.

13. The rolling bearing according to claim 1, characterized in that the gap length is at least 50% of the rolling body height.

14. The rolling bearing according to claim 1, characterized in that the rolling bodies are ball-shaped and the rolling body height corresponds to the external diameter of the rolling bodies.

15. The rolling bearing according to claim 1, characterized in that the gap height is constant over the gap length.

16. The rolling bearing according to claim 1, characterized in that the gap height varies over the gap length.

17. The rolling bearing according to claim 16, characterized in that the gap height decreases over the gap length in a direction from the axial outer end of the cover disk to the rolling bodies, in particular decreases linearly viewed in an axial section through the axis of rotation.

18. The rolling bearing according to claim 1, characterized in that the cover disk is elastically deformable in the axial direction at least in the region of its end assigned to the bearing inner ring.

19. The rolling bearing according to claim 18, characterized in that the cover disk, when the rolling bearing is at a standstill, presses against a step or end face of the bearing inner ring and, when the bearing inner ring is revolving, is raised off of the step or the end face by a differential pressure over the cover disk.

20. The rolling bearing according to claim 1, characterized in that the cover disk and/or the bearing inner ring has a conveyance contour adjoining the radial gap, which effectuates an air conveyance of air located in the radial gap in the direction of the rolling bodies.

21-31. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In the figures:

[0055] FIG. 1 shows an exemplary illustration of a dental handheld instrument (dental handpiece), in which at least one rolling bearing according to the disclosure can be provided;

[0056] FIG. 2 shows an exemplary embodiment of a rolling bearing according to the disclosure:

[0057] FIG. 3 shows a further exemplary embodiment of a rolling bearing according to the disclosure;

[0058] FIG. 4 shows a further exemplary embodiment of a rolling bearing according to the disclosure;

[0059] FIG. 5 shows a further exemplary embodiment of a rolling bearing according to the disclosure;

[0060] FIG. 6 shows a further exemplary embodiment of a rolling bearing according to the disclosure;

[0061] FIG. 7 shows a further exemplary embodiment of a rolling bearing according to the disclosure;

[0062] FIG. 8 shows a further exemplary embodiment of a rolling bearing according to the disclosure;

[0063] FIG. 9 shows a further exemplary embodiment of a rolling bearing according to the disclosure;

[0064] FIG. 10 shows a further exemplary embodiment of a rolling bearing according to the disclosure;

[0065] FIG. 11 shows a further exemplary embodiment of a rolling bearing according to the disclosure;

[0066] FIG. 12 shows a further exemplary embodiment of a rolling bearing according to the disclosure;

[0067] FIG. 13 shows a further exemplary embodiment of a rolling bearing according to the disclosure;

[0068] FIG. 14 shows a further exemplary embodiment of a rolling bearing according to the disclosure;

[0069] FIG. 15 shows a further exemplary embodiment of a rolling bearing according to the disclosure;

[0070] FIG. 16 shows a further exemplary embodiment of a rolling bearing according to the disclosure;

[0071] FIG. 17 shows a further exemplary embodiment of a rolling bearing according to the disclosure;

[0072] FIG. 18 shows a spacer in the radial gap to install a cover disk in the rolling bearing;

[0073] FIG. 19 shows a further exemplary embodiment of a rolling bearing according to the disclosure;

[0074] FIG. 20 shows a further exemplary embodiment of a rolling bearing according to the disclosure;

[0075] FIG. 21 shows a further exemplary embodiment of a rolling bearing according to the disclosure;

[0076] FIG. 22 shows the detail X from FIGS. 19 to 21.

DETAILED DESCRIPTION

[0077] A dental handheld instrument is illustrated by way of example in FIG. 1 in a sectional illustration, which only shows the front part of a housing 11, also called head housing, in which a shaft 12 is mounted rotatably around the axis of rotation 5 by means of the rolling bearings 13, 14. A rotor 15 in the form of a turbine wheel, which is driven by means of compressed air, is fastened on the shaft 12. A tool 16 can be fastened at the axial end of the shaft 12. The rolling bearing 13 arranged on the tool side can preferably be provided with the cover disk according to the disclosure.

[0078] Various exemplary embodiments of a rolling bearing according to the disclosure, for example, the rolling bearing 13 in FIG. 1, are shown in FIGS. 2 to 21. The rolling bearings each preferably have a cover disk 6 on the side facing toward the tool 16 in FIG. 1, which is provided with an axial leg 10, which adjoins a radial leg 9. In principle, the cover disk 6 could also be provided on the side of the rolling bearing 13 facing away from the tool 16, in order to reduce an air entry into the rolling bearing 13.

[0079] The radial leg 9 is fastened on the bearing outer ring 2 of the rolling bearing, the axial leg 10 is opposite in the radial direction to a radial outer surface of at least the bearing inner ring 1 in such a way that the bearing inner ring 1 forms a radial gap 7 jointly with the cover disk 6, which has a gap length L in the axial direction, and a gap height H in the radial direction.

[0080] The cover disk 6 covers a bearing gap 3 between the bearing inner ring 4 and the bearing outer ring 2 in the axial direction. Rolling bodies 4 of the rolling bearing are mounted in the bearing gap 3, wherein the rolling bodies 4 roll on a radial inner surface of the bearing outer ring 2 and a radial outer surface of the bearing inner ring 1, so that the bearing inner ring 1 revolving around the axis of rotation 5 is mounted by the rolling bodies 4 in the stationary bearing outer ring 2.

[0081] The rolling bodies 4 have a rolling body height WH in the radial direction, which can be, for example, only 1 mm in the dental handheld instrument shown in FIG. 1.

[0082] According to the disclosure, the gap length L is at least 25% of the rolling body height WH.

[0083] In the exemplary embodiments shown here, the gap length L is preferably at least 50% of the rolling body height WH, in particular 70% or more.

[0084] The minimum extension of the gap height H is preferably greater than an operating clearance between the bearing inner ring 1 and the bearing outer ring 2, viewed with interconnected rolling bodies 4, so that the operating clearance, which is measured at operating temperature of the rolling bearing, results from the mobility of the bearing inner ring 1 in relation to the rolling bodies 4 and of the rolling bodies 4 in relation to the bearing outer ring 2, in particular in the radial direction.

[0085] The maximum extension of the gap height H is advantageously at most 20% of the roiling body height WH.

[0086] The bearing gap 3, as is apparent from FIGS. 2 to 22, preferably opens freely into the surroundings in the axial direction. This means that no additional cover disk, cover element, or seal disk is provided which partially or completely overlaps the bearing gap 3 in the axial direction

[0087] In FIGS. 2 to 5, the cover disk, viewed in an axial section through the axis of rotation 5, is L-shaped, in relation to one half of the axial section on each side of the axis of rotation 5. The axial leg 10 accordingly extends completely on only one axial side of the radial leg 9.

[0088] A bore 6.1 can be provided in the axial leg 10, which effectuates a blocking air curtain in the radial gap 7, because compressed air can flow out of the bearing gap 3 radially inward through the bore 6.1 into the radial gap 7. The bore 6.1 can extend obliquely to the axial direction or radial direction or perpendicularly to the axis of rotation 5. A plurality of corresponding bores 6.1 are preferably arranged in succession in the circumferential direction around the axis of rotation 5.

[0089] In the embodiment according to FIG. 6, the cover disk 6, viewed in axial section through the axis of rotation 5, is formed T-shaped on both sides of the axis of rotation 5, wherein the radial leg 9 again extends in the radial direction and the axial leg 10 again extends in the axial direction. The axial leg 10 extends here on both sides in the axial direction in relation to the radial leg 9, however.

[0090] If the axial leg 10, as shown in FIGS. 2 to 6, extends exclusively in the axial direction, i.e., parallel to the axis of rotation 5 in the axial section shown through the axis of rotation 5, the radial gap 7 can thus be embodied having diverging height H if the radial outer surface of the bearing inner ring 1 preferably tapers in the direction of its axial end. Alternatively, however, a radial gap 7 having constant gap height H over the gap length L can be provided, by corresponding mutually opposing parallel surfaces of the cover disk 6 and the bearing inner ring 1, wherein the surfaces can be arranged in the axial section shown in parallel to the axis of rotation 5 or diagonally to the axis of rotation 5.

[0091] In the embodiment according to FIG. 3, it is furthermore shown that an additional cover disk 18 can be provided on the side of the rolling bearing facing away from the cover disk 6, which reduces an airflow into the rolling bearing. This cover disk 18 can also be installed on the bearing outer ring 2 or formed integrally therewith and can form a second radial gap 7′ with the bearing inner ring 1. Alternatively, the additional cover disk 18 is attached to the bearing inner ring 1 or formed integrally (in one piece) therewith and thus conveys air radially outward due to its rotation, so that this air does not enter or enters to a lesser extent into the bearing gap 3.

[0092] In the embodiments according to FIGS. 7 and 8, the cover disk 6 has, in addition to the radial leg 9, an axial leg 10 having two axial sections 10.1 and 10.2 on different diameters to form a stepped radial gap 7. The first axial section 10.1 forms an axial section of the radial gap 7 together with the radial outer surface of the shaft 12. The first axial section 10.1 is attached for this purpose to the radial leg 9 on the side facing away from the bearing gap 3 or the rolling bodies 4. The second axial section 10.2 adjoins the radial leg 9 on the side facing toward the rolling bodies 4 and forms a section of the radial gap 7 with the radial outer surface of the bearing inner ring 1. The two sections of the radial gap 7 are connected to one another by a radial section of the radial gap 7. The radial section is formed by the end face 1.1 of the bearing inner ring 1 and an opposing surface of the cover disk 6, for example of the radial leg 9. The flow of compressed air through the radial gap 7 is reduced once again by this step.

[0093] The embodiment according to FIG. 8 substantially corresponds to that of FIG. 7. However, the axial end section of the bearing inner ring 1, which is opposite to the second axial section 10.2 of the axial leg 10, is inclined comparatively more strongly in relation to the bearing axis 5, so that the radial gap 7 is reduced comparatively more strongly over its course into the bearing interior, i.e., in the direction of the rolling bodies 4.

[0094] The embodiment according to FIG. 9 shows, like the other embodiments also shown here, a radial recess 8 at one axial end of the bearing outer ring 2. A seal element and/or damping element, for example, in the form of a rubber ring, advantageously an O-ring, can advantageously be accommodated therein to support the bearing outer ring 2 against a housing. In spite of this radial recess 8, the cover disk 6 is fastened frontally on the bearing outer ring 2 and does not enclose the bearing outer ring 2.

[0095] In the embodiments according to FIGS. 2 to 9 and 19 to 21, the rolling bodies 4 are only guided on one side on the bearing inner ring 1 in the axial direction, but the bearing outer ring 2 encloses the rolling bodies 4 on both sides in the axial direction. This is reversed in the design according to FIG. 10. It is thus preferably a separable ball bearing in each case. To achieve an axial angulation of the ball bearing having a force flow in the diagonal direction through the rolling bodies 4, the ball bearing could also be embodied as an angular ball bearing, i.e., the rolling bodies 4 would also accordingly only be guided on one side on the bearing outer ring 2 in the axial direction, specifically on the axial side facing away from the guide on the bearing inner ring 1.

[0096] Furthermore, in the design according to FIG. 10, the bearing inner ring 1 forms a step 1.2, so that the radial gap 7 has a section extending in the radial direction, which is not formed here by the end face 1.1 of the bearing inner ring 1, however. A further step could be provided on the end face 1.1. According to one exemplary embodiment, a corresponding axial gap always remains between the axial end of the step 1.2 and the cover disk 6. According to another exemplary embodiment, the cover disk 6 is elastically deformable, so that in the idle state of the bearing, the cover disk 6 abuts the step 1.2.

[0097] The embodiment according to FIG. 11 substantially corresponds to that of FIG. 10, except that here the rolling bodies 4 are enclosed on both sides in the axial direction by the bearing inner ring 1 and by the bearing outer ring 2. It is thus preferably a deep groove ball bearing. The design of the cage 19 in which the rolling bodies 4 are held also differs from the preceding embodiments. The cage 19 is thus embodied as a crown cage and only encloses the rolling bodies 4 on one axial side, in contrast to the preceding embodiments, in which the rolling bodies 4 are held on both sides in the cage 19 in the axial direction. However, these details are not necessarily required.

[0098] According to FIG. 12, the cover disk 6 encloses the bearing outer ring 2 at one axial end and extends into the radial recess 8. The cover disk 6 is, for example, pressed radially outside onto the bearing outer ring 2 here.

[0099] In the embodiment according to FIG. 13, a circumferential groove 20 is provided inside the radial recess 8, in which the cover disk 6 engages in a formfitting manner from the radial outside.

[0100] In the embodiment according to FIG. 14, the cover disk 6 frontally abuts the step 1.2 of the bearing inner ring 1 with its axial leg 10 when the rolling bearing is stationary. In operation, the contact between the cover disk 6 and the bearing inner ring 1 is canceled by a pressure difference in that the cover disk 6 elastically deforms.

[0101] In the embodiment according to FIG. 15, the cover disk 6 is arranged at the comparatively other axial end of the rolling bearing, in comparison to the other embodiments shown. This can be the inner end of the rolling bearing 13 in FIG. 1 here.

[0102] In this embodiment, an entry of air into the rolling bearing is thus reduced, so that less air can accordingly also escape at the outer end from the rolling bearing. The cover disk 6 can be embodied in different ways as described above. At the opposite end to the cover disk 6, an additional cover disk 18 is provided, which is fixed, for example, using a snap ring 21 in a recess in the bearing outer ring 2.

[0103] The rolling bearing according to FIG. 15 could, however, also be arranged in the handheld instrument from FIG. 1 in such a way, for example, that the cover disk 6 is positioned on the tool side and the additional cover disk 18 is positioned on the side facing away from the tool 16, so that accordingly the function of the two cover disks 6, 18 is reversed. In this case, the additional cover disk 18 would reduce the entry of air into the bearing gap 3 and the cover disk 6 would reduce the exit of air out of the bearing gap 3.

[0104] In FIG. 16, the rolling bodies 4 are again enclosed in the axial direction on both sides by the bearing inner ring 1 and by the bearing outer ring 2 to form a deep groove ball bearing. In addition to the cover disk 6, an additional cover disk 18 is again provided, which is fastened frontally on the bearing outer ring 2 here, for example, is fastened by material bonding.

[0105] In the embodiment according to FIG. 17, not only the cover disk 6 forms a radial gap 7 having corresponding gap length, but rather the additional cover disk 18 also has an axial leg 10 to form a corresponding gap length of a radial gap 7′.

[0106] The statements made above on the cover disk 6 thus apply to the additional cover disk 18 and the design can be varied accordingly.

[0107] It is schematically shown in FIG. 18 that during the installation of the cover disk 6 in the rolling bearing, a spacer 17, for example in the form of a film, is applied to the radial outside on the bearing inner ring 1, the thickness of which corresponds to the radial gap 7 to be set. The cover disk 6 is placed on the bearing inner ring 1 having the spacer 17 arranged in the radial gap and is thus centered in relation to the bearing inner ring 1. The cover disk 6 is subsequently fixed in the centered state on the bearing outer ring 2 and only then is the spacer 17 removed from the radial gap 7.

[0108] In the embodiments according to FIGS. 19 to 21, the cover disk 6 is inserted radially inside into the bearing outer ring 2. The bearing outer ring 2, as can be seen in particular from the detail X, which is shown in FIG. 22, preferably has an edge-open radial groove 22 radially inside, in which the cover disk 6 is inserted.

[0109] A radial clearance can be provided between the bearing outer ring 2 and the cover disk 6, in particular inside the radial groove 22, before welding of the cover disk 6 on the bearing outer ring 2, so that the cover disk 6 can be centered in relation to the bearing inner ring 1 in order to produce a constant radial gap 7 over the circumference of the bearing inner ring 1.

[0110] In the embodiment according to FIG. 21, an additional cover disk 18, which forms a second radial gap 7′ with the bearing inner ring 1, is again provided at the axial end of the bearing outer ring 2 which is opposite to the axial end having the cover disk 6. This prevents or reduces the entry of air into the rolling bearing.

[0111] In the embodiment according to FIG. 20, a bore 6.1 is again provided in the axial leg 10 of the cover disk 6, the function of which was explained above, for example, on the basis of FIG. 9.

[0112] In addition, the embodiments according to FIGS. 20 and 21 correspond to that of FIG. 19.

[0113] In the embodiments according to FIGS. 19 to 21, the cover disk 6 is preferably again embodied to be L-shaped, wherein the axial leg 10 preferably extends starting from the radial leg 9 in the direction of the rolling bodies 4. The radial gap 7 can taper here, for example, due to a slightly diagonal alignment of the radial outer surface of the bearing inner ring 1, which is opposite to the axial leg 10.

[0114] The rolling bearings are also embodied as separable ball bearings in FIGS. 19 to 21, having a shoulder 23 in the bearing outer ring 2 on the axial side of the cover disk 6 and a shoulder 23 in the bearing inner ring 1 on the axial side facing away from the cover disk 6. Furthermore, a shoulder 23 is provided in the bearing outer ring 2 on the axial side facing away from the cover disk 6. This shoulder 23 would be omitted in an embodiment of the rolling bearing as an angled ball bearing.

[0115] A diagonal force flow direction from the bearing inner ring 1 through the rolling bodies 4 onto the bearing outer ring 2 results due to the shoulders 23.

[0116] In the embodiments having cover disk 6 inserted radially inside into the bearing outer ring 2, the bearing outer ring 2 can also have a radial recess 8, in particular an edge-open radial recess 8, preferably at one axial end. A seal element and/or damping element, for example in the form of a rubber ring, advantageously an O-ring, can advantageously be accommodated therein to support the bearing outer ring 2 against a housing.

LIST OF REFERENCE SIGNS

[0117] bearing inner ring

[0118] 1.1 end face

[0119] 1.2 step

[0120] 2 bearing outer ring

[0121] 3 bearing gap

[0122] 4 rolling body

[0123] 5 axis of rotation

[0124] 6 cover disk

[0125] 6.1 bore

[0126] 7 radial gap

[0127] 7′ second radial gap

[0128] 8 radial recess

[0129] 9 radial leg

[0130] 10 axial leg

[0131] 10.1 first axial section

[0132] 10.2 second axial section

[0133] 11 housing

[0134] 12 shaft

[0135] 13 rolling bearing

[0136] 14 rolling bearing

[0137] 15 rotor

[0138] 16 tool

[0139] 17 spacer

[0140] 18 additional cover disk

[0141] 19 cage

[0142] 20 circumferential groove

[0143] 21 snap ring

[0144] 22 radial groove

[0145] 23 shoulder

[0146] H gap height

[0147] L gap length

[0148] WH rolling body height