HIGH PRECISION GEAR BOX

Abstract

It is disclosed a high precision gear box (1) comprising at least one lubricated unit (40, 52, 64), wherein the lubricated unit (40, 52, 64) comprises a first element (42, 54, 66) and a second element (44, 56, 68), wherein the first element (42, 54, 66) and the second element (44, 56, 68) are configured to rotate against each other, wherein a space (48, 60, 72) is formed between the first element (42, 54, 66) and the second element (44, 56, 68), wherein the space (48, 60, 72) is filled with a polymer material (50, 62, 74) being saturated with oil for lubricating the first and the second element (44, 56, 68).

Claims

1. High precision gear box (1) comprising at least one lubricated unit (40, 52, 64), wherein the lubricated unit (40, 52, 64) comprises a first element (42, 54, 66) and a second element (44, 56, 68), wherein the first element (42, 54, 66) and the second element (44, 56, 68) are configured to rotate against each other, wherein a space (48, 60, 72) is formed between the first element (42, 54, 66) and the second element (44, 56, 68), characterized in that the space (48, 60, 72) is filled with a polymer material (50, 62, 74) being saturated with oil for lubricating the first and the second element (44, 56, 68).

2. High precision gear box according to claim 1, wherein the polymer material (50, 62, 74) is arranged to seal off the space (48, 60, 72) to the environment.

3. High precision gear box according to any one of the preceding claims, wherein the polymer material (50, 62, 74) has a porous structure containing micro-pores, wherein the micro-pores are filled with the oil.

4. High precision gear box according to any one of the preceding claims, wherein the lubricated unit (40, 52, 64) is a bearing unit (40, 52, 64) of the high precision gear box, wherein the first element (42, 54, 66) is at least one inner ring (42, 54, 66) and the second element (44, 56, 68) is at least one outer ring, wherein rolling elements (46, 58, 70) are arranged between the inner ring (42, 54, 66) and the outer ring (44, 56, 68), wherein the space (48, 60, 72) is a rolling chamber (48, 60, 72) formed between the inner ring (42, 54, 66) and the outer ring (44, 56, 68), wherein the polymer material (50, 62, 74) is configured for lubricating the rolling elements (46, 58, 70) or raceways of the inner ring (42, 54, 66) or the outer ring (44, 56, 68).

5. High precision gear box according to claim 4, wherein the polymer material (50, 62, 74) is arranged almost contactless to the rolling elements (46, 58, 70) and raceways of the inner ring (42, 54, 66) and the outer ring (44, 56, 68) so that the bearing unit (40, 52, 64) is adapted to rotate freely.

6. High precision gear box according to claim 4 or 5, wherein the bearing unit (40, 52, 64) comprises a cage being arranged between the inner ring (42, 54, 66) and the outer ring (44, 56, 68) for guiding the rolling elements (46, 58, 70), wherein the cage is configured to support the polymer material (50, 62, 74).

7. High precision gear box according to claim 6, wherein the cage is configured to induce a movement of the polymer material (50, 62, 74).

8. High precision gear box according to claim 4 or 5, wherein the polymer material (50, 62, 74) is configured for providing the functionality of a cage for guiding the rolling elements (46, 58, 70).

Description

BRIEF DESCRPTION OF THE DRAWINGS

[0022] In the following, the present invention will be described by means of embodiments shown in the figures. The shown embodiments are exemplarily, only, and are not intended to limit the scope of protection. The scope of protection is solely defined by the attached claims.

[0023] FIG. 1 shows a high precision gear box comprising lubricated bearing units.

[0024] In the following same or similar functioning elements are indicated with the same reference numerals.

DETAILED DESCRIPTION OF THE INVENTION

[0025] FIG. 1 shows an example of a high precision gear box 1. The high precision gear box 1 comprises a sun wheel 2, a planetary carrier 4 and a hollow wheel 6. Such a high precision gear box 1 may be used for example as an articulated joint within a robot unit.

[0026] The embodiment shown in FIG. 1 is only one potential concept of a high precision gear box. Other concepts are also possible, for example with two hollow wheels.

[0027] Depending on the application, the sun wheel 2, the planetary carrier 4 or the hollow wheel 6 may be stationary. In the case shown in FIG. 1, the hollow wheel 6 is stationary.

[0028] One side of the high precision gear box 1 represents an input side and the opposite side represents an output side. The input side may be coupled to a motor unit. Via such a motor unit, either the sun wheel 2 or the planetary carrier 4 may be driven.

[0029] If the sun wheel 2 is driven, a rotation of the sun wheel 2 is transferred via double planets 8, fixed to the planetary carrier 4, to the planetary carrier 4 and the planets 8 are rolling on the hollow wheel 6.

[0030] Around the sun wheel 2, the planetary carrier 4 is arranged. The carrier 4 may have a ring shape and may comprise multiple hubs 10-1, 10-2, which are circumferentially arranged around the sun wheel 2. The hubs 10-1, 10-2 can be attached to the cover 14 via fasteners 12. The cover 14 can be coupled via an attachment 16 with an input or output element.

[0031] On the axial opposite side, the planetary carrier 4 is coupled with a cover 22 via fasteners 18. In addition, the high precision gear box 1 may comprise a cover 20, which may be coupled via fasteners 24 with an input or output element. The hollow wheel 6 may be coupled via fasteners 26 with a housing or maybe implemented as a housing.

[0032] In order to transfer a movement of the planetary carrier 4 to the sun wheel 2, the planetary carrier 4 comprises double planets 8-1, 8-2. The double planets 8-1, 8-2 each comprise a first gearing 32, which meshes with an external gearing 34 of the sun wheel 2. The double planets 8-1, 8-2 further comprise a second gearing 36, which meshes with an internal gearing 38 of the hollow wheel 6. The rotation of the planetary carrier 4 is transferred to the sun wheel 2 via the first gearings 32. Due to the second gearings 36, the double planets 8-1, 8-2 roll on the hollow wheel 6. The double planets 8-1, 8-2 are also attached to the planetary carrier 4 and mesh directly with the sun wheel 2 and the hollow wheel 6.

[0033] For supporting the sun wheel 2 and the planetary carrier 4, the high precision gear box 1 may comprise bearing units 40, 48 between the sun wheel 2 and the planetary carrier 4 as well as between the planetary carrier 4 and the hollow wheel 6. In the shown embodiment, two bearing units 40 are arranged between the sun wheel 2 and the planetary carrier 4. The bearing units 40 each comprise an inner ring 42, which is coupled with the sun wheel 2, and an outer ring 44, which is coupled with the planetary carrier 4. Between the inner ring 42 and the outer ring 44 rolling elements 46, in this case tapered rollers, are arranged. The bearing unit 40 may also comprise different kind of rolling elements or may be a plain bearing. Between the inner ring 42 and the outer ring 44, a rolling chamber 48 is formed. For lubricating the inner ring 42, the outer ring 44 and the rolling elements 46, a polymer material 50 is filled into the rolling chamber 48.

[0034] The rolling chamber 48 between a first element, i.e. the inner ring 42, and a second element, i.e. the outer ring 44, is filled with the polymer material 50 which is saturated with oil for lubricating the inner and outer ring 42, 44. The advantage of using a polymer material for lubricating the bearing unit 40 is that the polymer material does not leave the rolling chamber 48 due to gravitational or centrifugal forces and thus, the lubrication of the bearing unit 40 may be ensured during the lifetime of the high precision gear box 1 and/or the lifetime of the bearing unit 40.

[0035] The polymer material 50 is rigid and does not flow out of the bearing unit 40. This means that the oil being contained in the polymer material 50 resists to leave the bearing unit 40 also during operation of the high precision gear box 1. Thus, there is no need for special retaining mechanisms for keeping the lubricant, i.e. the oil, in the bearing unit 40.

[0036] The polymer material 50 may be in particular a polymer matrix saturated with a lubrication oil that completely fills the rolling chamber 48 and may encapsulate a cage (not shown) and/or the rolling elements 46. The polymer matrix may contain two to four times more lubrication oil than a commonly used sealed, grease-filled bearing. By containing two to four times more lubricant, the bearing unit 40 is sufficiently life lubricated. The polymer material 50 may be arranged contactless to the rolling elements 46 and raceways of the inner ring 42 and the outer ring 44 so that the bearing unit 44 is adapted to rotate freely.

[0037] Further, bearing units 52 are arranged between the planetary carrier 4 and the hollow wheel 6. The bearing units 52 each comprise an inner ring 54 and an outer ring 56. The inner ring 54 is coupled with the planetary carrier 4 and the outer ring 56 is coupled with either the hollow wheel 6 or is realized by the hollow wheel 6. Between the inner ring 54 and the outer ring 56, rolling elements 58 are arranged, which may be for example balls. Alternatively, any other kind of rolling elements may be used or the bearing unit 52 may be a plain bearing. As explained with reference to the bearing units 40, also the bearing units 52 have a rolling chamber 60 formed between the inner ring 54 and the outer ring 56. For lubricating the inner ring 54, the outer ring 56 and/or the rolling elements 58, the rolling chamber 60 may be filled with a polymer material 62 as explained with reference to the bearing units 40.

[0038] Further, to improve the rotation of the double planets 8-1, 8-2, bearing units 64 may be provided between the double planets 8-1, 8-2 and the hubs 10-1, 10-2. The bearing units 64 each comprise an inner ring 66 and an outer ring 68. The inner ring 66 is coupled with the hubs 10-1, 10-2 and the outer ring 68 is coupled with double planets 8-1, 8-2. Between the inner ring 66 and the outer ring 68, rolling elements 70 are arranged, which may be for example rollers. Alternatively, any other kind of rolling elements may be used or the bearing unit 64 may be a plain bearing. As explained with reference to the bearing units 40, also the bearing units 64 have a rolling chamber 72 formed between the inner ring 66 and the outer ring 68. For lubricating the inner ring 66, the outer ring 68 and/or the rolling elements 70, the rolling chamber 72 may be filled with a polymer material 74 as explained with reference to the bearing units 40.

[0039] With the herein described high precision gear box, it is possible to provide an improved lubrication for bearing units or any other kind of lubricated unit within high precision gear boxes. This may be achieved by using a polymer material which is saturated with oil for lubrication.

LIST OF REFERENCE SIGNS

[0040] 1 high precision gear box

[0041] 2 sun wheel

[0042] 3 planetary carrier

[0043] 6 hollow wheel

[0044] 8 double planet

[0045] 10 hub

[0046] 12 fastener

[0047] 14 cover

[0048] 16 attachment to input

[0049] 18 fastener

[0050] 20 cover

[0051] 22 cover

[0052] 24 attachment

[0053] 26 attachment to previous section

[0054] 32 first gearing

[0055] 34 external gearing of the sun wheel

[0056] 36 second gearing

[0057] 38 internal gearing of the hollow wheel

[0058] 40 bearing unit

[0059] 42 inner ring

[0060] 44 outer ring

[0061] 46 rolling elements

[0062] 48 rolling chamber

[0063] 50 polymer material

[0064] 52 bearing unit

[0065] 54 inner ring

[0066] 56 outer ring

[0067] 58 rolling elements

[0068] 60 rolling chamber

[0069] 62 polymer material

[0070] 64 bearing unit

[0071] 66 inner ring

[0072] 68 outer ring

[0073] 70 rolling elements

[0074] 72 rolling chamber

[0075] 74 polymer material