STEPPED HOLLOW WHEEL

Abstract

A gear set for an internal gear machine. Both front areas of the first gearwheel include respectively one running area, which are axially spaced apart by a first gearwheel thickness, and the second gearwheel includes a thickness-reduced region which has a reduced gearwheel thickness in relation to the first gearwheel thickness.

Claims

1. A gear set for an internal gear machine, formed of two gearwheels each having two axial front areas, wherein both front areas of the first gearwheel comprise respectively one running area, which are axially spaced apart by a first gearwheel thickness, and wherein the second gearwheel comprises a thickness-reduced region which has a gearwheel thickness that is reduced in relation to the first gearwheel thickness.

2. The gear set according to claim 1, wherein the thickness-reduced region of the second gearwheel is a planar region, and/or both surfaces of the thickness-reduced region of the second gearwheel respectively have the greatest axial height of the respective front area, and/or the thickness-reduced region extends over the entire second gearwheel, and/or a thickness reduction of the thickness-reduced region is in a range between 2 m and 50 m or between 3 m and 30 m or between 4 m and 10 m.

3. The gear set according to claim 1, wherein both front areas of the second gearwheel comprise a surface of the thickness-reduced region and a running area or consist thereof, wherein the running areas of the two front areas of the second gearwheel are axially spaced apart by the first gearwheel thickness, and wherein the running areas respectively have the greatest axial height of the respective front area, and/or the thickness-reduced region of the second gearwheel is a planar region, and/or a thickness reduction of the thickness-reduced region amounts to at least 2, 4, 6, 10, 50, 100, 200 or 500 m or is in a range between 2 m and 50 m or between 3 m and 30 m or between 4 m and 10 m, and/or an axial height difference between the surface of the thickness-reduced region and the running area is identical on both front areas and/or amounts to one half of the thickness reduction.

4. The gear set according to claim 1, wherein on one or both front area(s) of the first gearwheel the running area respectively has the greatest axial height of the respective front area, and/or one or both front area(s) of the first gearwheel consist of the respective running area, or the first gearwheel comprises a thickness-reduced region, so that the front areas of the first gearwheel comprise the respective running area and a surface of the thickness-reduced region or consist thereof, wherein preferably the thickness-reduced region of the first gearwheel is a planar region, and/or a thickness reduction of the thickness-reduced region amounts to at least 2, 4, 6, 10, 50, 100, 200 or 500 m or is in a range between 2 m and 50 m or between 3 m and 30 m or between 4 m and 10 m, and/or an axial height difference between the surface of the thickness-reduced region and the running area on both front areas is identical and/or amounts to one half of the thickness reduction.

5. The gear set according to claim 1, wherein both running areas of the first gearwheel respectively have the greatest axial height of the respective front area and preferably both running areas respectively form the front areas of the first gearwheel, and the thickness-reduced region of the second gearwheel is a planar, thickness-reduced region, the frontal surfaces of which respectively have the greatest axial height and/or respectively form the front areas of the second gearwheel, and wherein preferably a thickness reduction is in a range between 2 m and 50 m or between 3 m and 30 m or between 4 m and 10 m.

6. The gear set according to claim 1, wherein the running areas on one gearwheel or respectively on both gearwheels are arranged in the axial direction in overlapping manner and/or congruently or mirror-symmetrically and/or the first gearwheel thickness is present continuously in the overlap region and/or on the entire running area(s), and/or the first gearwheel thickness is the maximal thickness of the respective gearwheel or of the gear set, and/or one or each running area is continuously rotationally symmetric or discretely rotationally symmetric and/or one or each running area comprises the front areas of the gearwheel teeth.

7. The gear set according to claim 1, wherein the first and/or the second gearwheel is configured to be mirror-symmetric and/or has an n-fold discrete rotational symmetry with reference to the rotation axis, wherein n is the number of teeth of the gearwheel.

8. The gear set according to claim 1, wherein at least one or all running areas and/or planar surfaces of thickness-reduced regions are grinded surfaces and/or have constant axial heights.

9. The gear set according to claim 1, wherein the first gearwheel is the inner sprocket and the second gearwheel is the hollow wheel or the first gearwheel is the hollow wheel and the second gearwheel is the inner sprocket.

10. The gear set according to claim 1, wherein the first and/or second gearwheel is configured in one-piece or single-piece manner and/or the first and second gearwheel consist of different materials or of the same material.

11. The gear set according to claim 1, wherein the inner sprocket has a diameter between 5 and 100 mm, in particular of 30 mm, and has 10 to 30 teeth, in particular 15 teeth, and/or the hollow wheel has an outer diameter between 20 and 150 mm, in particular of 52 mm, an inner diameter between 10 and 140 mm, in particular 40 mm, and has 12 to in particular 20 teeth, and/or the ratio of the number of teeth of the inner sprocket to the hollow wheel amounts to between 2:3 and 4:5 and in particular is 3:4, and/or the first gearwheel thickness is between 5 and 50 mm and in particular amounts to 13 mm.

12. An internal gear machine, comprising: a gear set according to claim 1, and axial sealing elements, in particular one or two axial sealing disks or axial housing parts, and preferably further comprising a housing with hydraulic connectors, and/or a hydraulic fluid, in particular a gear oil and/or Pentosin CHF 11S and/or with a viscosity between 500 and 310.sup.6 m.sup.2/s in a temperature range between 30 C. and 150 C.

13. A motor-pump unit, comprising: an internal gear machine according to claim 12, and a shaft which connects the inner sprocket to a motor, wherein the motor-pump unit is preferably adapted for reversing operation and/or the motor is an electric motor generator.

14. A method for manufacturing a gear set according to claim 1, comprising the steps of: supplying the first and the second gearwheel, the axial front areas of which comprise respectively one running area or consist thereof, wherein the running areas are axially spaced apart by the first gearwheel thickness and wherein preferably the supplying takes place through joint frontal grinding of both gearwheels, and grinding in certain regions or over the full area of the second gearwheel for configuring the thickness-reduced region of the second gearwheel.

15. The method according to claim 14, comprising the further step of grinding in certain regions of the first gearwheel for configuring the thickness-reduced region of the first gearwheel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0059] The invention will hereinafter be described by way of example with reference to the attached drawings. The drawings are merely schematic representations and the invention is not limited to the specific represented embodiment examples.

[0060] FIG. 1A is a view of a gear set, an internal gear machine and a motor-pump unit, and

[0061] FIG. 1B is a view of a gear set, an internal gear machine and a motor-pump unit, and

[0062] FIG. 1C is a view of a gear set, an internal gear machine and a motor-pump unit, and

[0063] FIG. 2A shows a perspective sectional view of a gear set supplied in the manufacturing method, and

[0064] FIG. 2B shows a sectional view of embodiment examples of gear sets with thickness-reduced regions.

[0065] FIG. 2C shows a sectional view of embodiment examples of gear sets with thickness-reduced regions.

[0066] FIG. 2D shows a sectional view of embodiment examples of gear sets with thickness-reduced regions.

DETAILED DESCRIPTION

[0067] In the FIGS. 1A to 1C the components of a gear set, an internal gear machine 10 and of a motor-pump unit are represented, which are respectively substantial for the invention. Details going beyond this can be gathered, for example, from the document DE 10 2014 103 958 A1 already stated above.

[0068] The gear set firstly comprises an externally toothed inner sprocket 11 and an internally toothed hollow wheel 12, which mutually engage eccentrically and, depending on the rotation direction, pump a working fluid or hydraulic fluid between two working or pressure chambers which are, among other things, separated by a radial sealing element 13. The radial sealing element 13, also referred to as sickle element, serves for radially compensating or sealing against leakage between the two adjoining pressure chambers.

[0069] So-called axial sealing disks 14, as schematically represented in the perspective exploded view of FIG. 1B, serve for sealing against axial leakage. These create planar areas on which the inner sprocket 11 and the hollow wheel 12 slide in rotating manner during operation. The axial sealing disks 14 can also contain depressions or gaps, which are not represented, and are, for example, subjected to the working pressure of the internal gear machine 10, so that the two axial sealing disks 14 clamp the inner sprocket 11 and the hollow wheel 12 in sealing manner.

[0070] The inner sprocket 11 of the internal gear machine 10 is connected via a shaft 21 to an electric motor 20, which can also be configured as an electric motor generator. Correspondingly, the electric motor generator 20 can drive the internal gear machine 10 or, vice versa, the internal gear machine 10 drives the electric motor generator 20 (for example during recuperation operation).

[0071] The internal gear machine 10, the electric motor generator 20 and an electronic control unit 30 are firmly interconnected and form a common construction unit in the embodiment example shown (see FIG. 1C). The respective housing parts of the internal gear machine 10, the electric motor generator 20 and the electronic control unit 30 form a common housing, so that a compact construction type results. Further, the internal gear machine 10 has hydraulic connectors 15, which connect the pressure chambers of the internal gear machine 10 with a load, for example a shock absorber.

[0072] In the FIGS. 2A-2D various gear sets are represented in cross section along the line AA drawn in FIG. 1A. While FIG. 2A shows a perspective sectional view along the entire line AA, in the FIGS. 2B to 2D the respective gear sets are represented only along the left part (in FIG. 2A) of the line AA as a simple sectional view.

[0073] FIG. 2A shows an embodiment example of a gear set, as supplied in the first step of the manufacturing method according to the invention or as present prior to the grinding of the thickness-reduced region according to the invention. For this purpose the inner sprocket 11 and the hollow wheel 12 were subjected to a joint grinding process so that both front sides of both gear wheels 11, 12 of the gear set are grinded to be completely planar and have the first gear wheel thickness in every place. The front areas of the inner sprocket 11 and the hollow wheel 12 thus form running areas at the same time and are already suitable in this form for employment as a gear set of an internal gear machine 10, as is already known from the state of the art in particular.

[0074] In the sectional views of the FIGS. 2A-2D the sprocket or tooth areas are hatched. FIG. 2A represents, for the inner sprocket 11, the tooth-base circle diameter 16 and the tooth-head circle diameter 17, which represents the (outer) diameter of the inner sprocket 11 at the same time. Likewise, the hollow wheel 12 also has a tooth-base circle diameter and a tooth-head circle diameter, wherein the latter forms the inner diameter of the hollow wheel 12 at the same time.

[0075] According to the invention, proceeding from the gear set represented in FIG. 2A, on at least one of the two gearwheels a thickness-reduced region is created which has a reduced gearwheel thickness.

[0076] In the simplest case, exactly one of the two gearwheels is subjected to a further or additional grinding process over its entire front area(s), i.e. in the simplest case over the full area, so that the thickness-reduced region thus created extends over the entire gearwheel. In the embodiment example represented in FIG. 2B the hollow wheel 12 (in this embodiment example corresponding to the second gearwheel) is subjected to the additional grinding process over its entire area, so that the resulting thickness-reduced region extends over the entire hollow wheel 12, while the inner sprocket 11 (in this embodiment example corresponding to the first gearwheel) continues having the first gearwheel thickness in every place of its front area. In the embodiment example represented in FIG. 2C the inner sprocket 11 (in this embodiment example corresponding to the second gearwheel) is subjected to the additional grinding process over its entire area, so that the resulting thickness-reduced region extends over the entire inner sprocket 11, while the hollow wheel 12 (in this embodiment example corresponding to the first gearwheel) continues having the first gearwheel thickness in every place of its front area.

[0077] In the embodiment example represented in FIGS. 2B and 2C the hollow wheel 12 has an outer diameter of 52 mm and 20 sprocket teeth. The inner sprocket 11 has an outer diameter of 30 mm and 15 sprocket teeth. Further, the first gearwheel thickness amounts to 13 mm and the thickness reduction, i.e. the thickness difference between the thickness-reduced region and the first gearwheel thickness amounts to 6 m. These dimensionswhere applicableare also valid for the other embodiment examples.

[0078] It is generally also possible to provide the thickness-reduced region on one or on both gearwheel(s) only in certain regions, as represented for both gearwheels by way of example in the embodiment example of FIG. 2D. A concentric thickness-reduced region is created in an inner region of the inner sprocket 11, said region not extending over the sprocket teeth in the represented embodiment example. The maximal diameter of the thickness-reduced region of the inner sprocket 11 is presently the tooth-base circle diameter, and the minimal diameter is the inner diameter or the shaft fitting of the inner sprocket 11. At the same time or alternatively, a concentric thickness-reduced region is created in an outer region of the hollow wheel 12, which likewise does not extend over the sprocket teeth in the represented embodiment example. The maximal diameter of the thickness-reduced region of the hollow wheel 12 is presently the outer diameter, and the minimal diameter is the tooth-base circle diameter of the hollow wheel 12.

[0079] In the not thickness-reduced regions, which are not subjected to further grinding, the previous surface is maintained, usually the running areas on the respective front area, which extends over the front areas of the sprocket teeth in the represented embodiment example, and thereby continues ensuring efficient axial leakage sealing. In the case of a reduced gearwheel thickness provided only in certain regions of a front area, a stronger thickness reduction can be provided, presently a thickness reduction of 200 m.

[0080] In further, not represented embodiment examples, the various configuration possibilities of the gearwheels are combined: [0081] inner sprocket 11 with reduced gearwheel thickness in certain regions and hollow wheel 12 without thickness-reduced region, [0082] inner sprocket 11 with reduced gearwheel thickness in certain regions and hollow wheel 12 with thickness-reduced region extending over the entire hollow wheel 12, [0083] hollow wheel 12 with reduced gearwheel thickness in certain regions and inner sprocket 11 without thickness-reduced region, and [0084] hollow wheel 12 with reduced gearwheel thickness in certain regions and inner sprocket 11 with thickness-reduced region extending over the entire inner sprocket 11.

[0085] In the embodiment example represented in FIG. 2D or generally in the case of reduced gearwheel thickness only in certain regions, the supplying of the thickness-reduced region on the inner sprocket 11 and/or the hollow wheel 12 takes place through additional grinding on both sides, so that the axial height difference between the thickness-reduced regions and the (supplied) running areas is identical on both front areas. Correspondingly, the gearwheels are mirror-symmetric with reference to an axial central plane of the respective gearwheel.

[0086] In a not represented embodiment example the grinding process is carried out asymmetrically, so that on both front areas of a given gearwheel there result mutually differing axial height differences between the (supplied) running area and the surface of the thickness-reduced region.

[0087] In a further not represented embodiment example, the additional grinding process is effected only on one side, so that there result axial height differences between the surface of the thickness-reduced region and the (supplied) running area only on one front area, whereas on the opposite front area the surface of the thickness-reduced region and the running area form a continuously planar surface or running area.

LIST OF REFERENCE NUMERALS

[0088] 10 internal gear machine [0089] 11 inner sprocket [0090] 12 hollow wheel [0091] 13 radial sealing element [0092] 14 axial sealing disk [0093] 15 hydraulic connectors [0094] 16 tooth-base circle diameter [0095] 17 tooth-head circle diameter [0096] 20 electric motor, electric motor generator [0097] 21 shaft, drive shaft [0098] 30 ECUelectric control unit