Planetary transmission with a planetary carrier and a sun gear, and method for producing a planetary transmission
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- SEW EURODRIVE GMBH & CO KG
- Filing Date
- 2024-05-29
- Publication Date
- 2026-05-20
AI Technical Summary
Existing planetary gears face challenges in achieving efficient and low-noise operation due to misalignment issues between the sun gear and planet carrier, leading to inefficiencies and increased noise.
The design incorporates a sun gear with a pin area featuring plug-in toothing and a planet carrier with axially continuous bores and bulges that protrude radially, allowing for improved centering of the sun gear during the cutting of splines, ensuring precise alignment and reduced noise.
This design enhances concentricity, resulting in lower noise levels and higher efficiency by maintaining precise centering during the cutting process, allowing for improved smooth running and torque transmission.
Smart Images
Figure EP2024064817_16012025_PF_FP_ABST
Abstract
Description
[0001] Planetary gear with planet carrier and sun gear and method for producing a planetary gear
[0002] Description:
[0003] The invention relates to a planetary gear with a planet carrier and sun gear and a method for producing a planetary gear.
[0004] It is generally known that a planetary gear has a planet carrier.
[0005] A pinion fastening for planetary gears is known from DE 41 34 552 A1.
[0006] A planetary gear is known from DE 102005 052 008 A1.
[0007] EP 3 832 171 A1 discloses a method for producing a composite comprising a sun gear and a planet carrier.
[0008] The invention is therefore based on the object of developing a planetary gear which is intended to enable efficient, low-noise operation.
[0009] According to the invention, the object is achieved in the planetary gear according to the features specified in claim 1 and in the method according to the features specified in claim 13.
[0010] Important features of the invention in the planetary gear with planet carrier and sun gear are that the sun gear has a running toothing and a journal area, wherein the journal area is at least partially provided with a plug-in toothing, in particular knurled toothing, wherein the planet carrier has a central bore, in particular an axially through central bore, wherein the planet carrier has bores, in particular axially through bores, into which planetary bolts are pressed, wherein the bores are spaced from the central bore, wherein bulges in the material of the planet carrier protrude radially inwards into the central bore, which bulges center the journal area and / or into which the plug-in toothing, in particular knurled toothing, is cut.
[0011] The advantage of this is that improved centering of the sun gear to the planet carrier is achieved, resulting in improved concentricity, which in turn results in lower noise and higher efficiency. When the pin section is inserted, it is centered between the recesses and thus also remains centered during the subsequent cutting of the spline, especially the knurled spline, into the material of the planet carrier, especially in the recesses.
[0012] The holes are all arranged at the same radial distance around the central hole, since the planets, in particular planetary gears, which are rotatably mounted on the planetary pins, are all constructed identically to one another.
[0013] The planetary pins protrude from the planetary carrier on the side of the planetary carrier facing away from the running teeth of the sun gear.
[0014] The radial direction, the axial direction, and the circumferential direction are each related to the direction of rotation of the planet carrier and thus also of the sun gear. The axial direction is parallel to the direction of the planet carrier's axis of rotation. The planets are not in mesh with the running gear of the sun gear.
[0015] In an advantageous embodiment, the central bore is arranged centrally in the planetary carrier, in particular with the rotational axis of the rotatably mounted planetary carrier aligned coaxially with the bore axis of the central bore. Advantageously, the planetary carrier of the first planetary gear stage is connected in a rotationally fixed manner to the sun gear of the second planetary gear stage. In an advantageous embodiment, the bore axis of the central bore is aligned parallel to the respective bore axis of the bores. Advantageously, the bores and the central bore are each axially continuous.
[0016] In an advantageous embodiment, the holes are all at the same distance from the central hole, with the holes all being arranged at the same radial distance, particularly relative to the rotational axis of the planet carrier. This has the advantage of minimizing imbalance.
[0017] In an advantageous embodiment, the maximum outer diameter of the running gear is larger than the maximum outer diameter of the journal area. This has the advantage of allowing a high torque to pass through.
[0018] In an advantageous embodiment, planets, in particular planetary gears, are rotatably mounted on the planetary pins, wherein the planets mesh with a first ring gear and with a first sun gear, wherein the running teeth of the sun gear engage with second planets, which mesh with the internal teeth of a second ring gear and are rotatably mounted on second pins connected to a second planet carrier of the planetary gear. It is advantageous that the sun gear belongs to the second planetary gear stage and is rotationally fixedly connected to the planet carrier of the first planetary gear stage.
[0019] In an advantageous embodiment, the radial width of the bulges is less than one-tenth of the inside diameter of the central bore. The advantage here is that the bulges are small, thus allowing the insertion of the pin section with little force.
[0020] In an advantageous embodiment, the center of a respective gap of the spline, in particular the knurled toothing, viewed in the circumferential direction has the same circumferential angular position as the center of a respective bulge, viewed in the circumferential direction. This is advantageous in that stable centering is enabled. In particular, the number of teeth of the spline, in particular the knurled toothing, is an integer multiple of the number of bores or planetary pins. This enables very precise centering.
[0021] In an advantageous embodiment, the circumferential angular range covered by the respective bulge in the circumferential direction is encompassed by the circumferential angular range covered by the bore nearest to this bulge, where it overlaps with the latter. It is advantageous that the bulge has the smallest possible width measured in the circumferential direction.
[0022] In an advantageous embodiment, the area covered in the axial direction by the spline, in particular the knurled spline, is encompassed by or similar to the area covered in the axial direction by the journal area. Advantageously, the journal area is partially toothed or fully toothed. A fully toothed design allows for greater torque transmission than a partially toothed design. However, the partially toothed design allows for deeper cutting into the material, as the centering is more robust due to the long cylindrical portion of the journal area.
[0023] In an advantageous embodiment, the maximum internal diameter D1 of the respective bore is greater than half the difference between D3, i.e., twice the center distance between the rotational axis of the planetary gear rotatably mounted on the respective pin, in particular the planetary gear, and the rotational axis of the planet carrier, and the maximum internal diameter of the respective bore. It is advantageous that the minimum web width between the respective bore and the central bore is sufficiently thin to allow for the formation of sufficiently protruding bulges.
[0024] In an advantageous embodiment, the central bore and the bores are arranged and dimensioned such that where D1 is the diameter of the central bore, D2 is the maximum inside diameter of the bore and
[0025] D3 is twice the center distance between the rotational axis of the planets mounted on the pins and the rotational axis of the planet carrier, particularly the axis coaxial with the rotational axis of symmetry of the sun gear. It is advantageous that the minimum web width between the respective bore and the central bore is sufficiently thin to allow for the formation of sufficiently prominent bulges.
[0026] Important features in the method for producing a planetary gear are that the planetary gear has a planet carrier, wherein the planet carrier has a central bore, in particular an axially through central bore, wherein the planet carrier has bores, in particular axially through bores, wherein the bores are spaced from the central bore, in a first method step planetary bolts are pressed into the bores, wherein when the bolts are pressed into the central bore, bulges in the material of the planet carrier project radially inwards are produced, wherein in a second method step following the first method step the journal region of a sun gear is inserted into the central bore, wherein the journal region is centered by the bulges and a spline, in particular knurled spline, of the journal region cuts into the bulges.
[0027] The advantage is that precise centering can be achieved during cutting. This results in improved smoothness and thus reduced noise, as well as increased efficiency.
[0028] In an advantageous embodiment, the journal region has a cylindrical region spaced from the running gear teeth of the sun gear and has a further region provided with the plug-in toothing, in particular knurled toothing, arranged axially between the running gear teeth and the cylindrical region. In the second method step, when inserting the journal region, the cylindrical region is first centered between the bulges and then the plug-in toothing, in particular knurled toothing, of the journal region begins to cut into the bulges. The advantage here is that precise and robust centering is possible during the cutting. This improves the smoothness of the transmission during operation, resulting in less noise and improved efficiency. Further advantages arise from the subclaims. The invention is not limited to the combination of features of the claims.For the person skilled in the art, further reasonable combination possibilities of claims and / or individual claim features and / or features of the description and / or the figures will arise, in particular from the task and / or the problem arising from a comparison with the prior art.
[0029] The invention will now be explained in more detail using schematic illustrations:
[0030] Figure 1 shows a plan view of a planet carrier 1 of a planetary gear according to the invention.
[0031] Figure 2 shows a side view of planetary bolts 20 before being inserted into the planet carrier 1.
[0032] Figure 3 shows the planet carrier 1 in side view, with the planetary bolts 20 inserted.
[0033] In Figure 4, the radially inwardly directed bulges 40, in particular elevations, which were created when the planetary bolts 20 were inserted into the planetary carrier 1 are shown in a plan view of the planetary carrier 1.
[0034] Figure 5 shows a cross section through the planet carrier 1 with the sun gear 50 additionally inserted.
[0035] Figure 6 shows a corresponding plan view of the planet carrier 1 with inserted sun gear 50, which has a partially toothed pin area.
[0036] Figure 7 shows a rear view of the planet carrier 1.
[0037] Figure 8 shows an enlarged view of a portion of Figure 7
[0038] Figure 9 shows a corresponding plan view of the planet carrier 1 with inserted sun gear 50, which has a pin area that is in particular axially completely toothed.
[0039] Figure 10 shows an enlarged view of a portion of the rear view of the planet carrier 1 according to Figure 9. Figure 11 schematically shows the relationship between a web width S and characteristic diameters (D1, D2, D3) of the bore pattern of the planet carrier 1.
[0040] As shown in the figures, the planet carrier 1 has a central bore into which the at least partially toothed pin region of a sun gear 50 is inserted, in particular coming from the axial direction.
[0041] Opposite to the axial direction, the planetary bolts 20 are inserted into holes 3 of the planetary carrier 1 arranged off-center.
[0042] The bores 3 are regularly spaced from one another in the circumferential direction and are all arranged at the same radial distance from the axis of rotation of the planet carrier 1, in particular which passes through the center of gravity of the planet carrier 1.
[0043] The bolts 20 are pressed into the bores 3, whereby material is displaced by the pressing in of the bolts 20. This causes radial bulges 40 in the material of the planet carrier 1, which protrude radially inward into the central bore 2. In particular, the bulges are created by compressing the material.
[0044] The circumferential angular range covered by the respective bulge 40 in the circumferential direction and related to the axis of rotation of the planet carrier 1 overlaps with the circumferential angular range covered by the bore 3 closest to the bulge 40 or is at least contained in it.
[0045] The bulges 40 reduce the clear inner diameter of the central bore 2 in the respective circumferential angle range covered by them.
[0046] The central bore 2 extends axially through the planet carrier 1. The bores 3 also extend axially through the planet carrier 1. The sun gear 50 has a first axial region, in which the running gearing of the sun gear 51 is arranged, and a second axial region, which is designed as a journal region 52. This journal region 52 has a smaller outer diameter than the running gearing region and is pressed into the central bore 2.
[0047] When the journal area 52 is inserted, the sun gear 50 centers itself over the bulges 40. A spline, in particular a knurled spline, present on the journal area 52 cuts into the material of the planet carrier 1. In particular, the spline 52, in particular a knurled spline, cuts and / or forms into the bulges and also into the undeformed area of the bore edge of the central bore 2.
[0048] As shown in Figure 5, in the exemplary embodiment shown there, the spline, in particular the knurled, extends only over a portion of the area covered in the axial direction by the pin portion 52. When the pin portion 52 is inserted, it is thus first centered with its tooth-free cylindrical portion centrally between the preferably three bulges 40, and then the spline, in particular the knurled, cuts and / or forms itself into the material. Thus, during cutting and / or forming, the guidance provided by the cylindrical portion is always effective, and therefore the cutting and / or forming is well guided.
[0049] As shown in Figure 9, in another embodiment, the entire pin region 52 can also be designed with a spline, in particular knurled spline, and thus a very strong, load-bearing connection can be achieved between the sun gear 50 and the planet carrier 1.
[0050] Preferably, the minimum distance D3 / 2, in particular the web width, between the central bore 2 and a respective bore 3 is smaller than the diameter of this respective bore 3.
[0051] Particularly preferably, the minimum distance D3 / 2, in particular the web width, between the central bore 2 and a respective bore 3 is smaller than the radius of this respective bore 3. In further embodiments according to the invention, the planet carrier, in particular according to the schematic representation of Figure 11, is dimensioned such that where D1 is the diameter of the central bore 2, where D2 is the maximum inside diameter of the bore 3 and
[0052] D3 is twice the center distance between the axis of rotation of the planets rotatably mounted on the bolts 20 and the axis of rotation of the planet carrier, in particular which is coaxially aligned with the axis of rotational symmetry of the sun gear 50.
[0053] The maximum clear diameter D1 of the bore 3 is therefore greater than half the difference between D3, i.e. twice the center distance between the axis of rotation of the planets rotatably mounted on the bolts 20 and the axis of rotation of the planet carrier 1, and the maximum clear diameter of the bore 3.
[0054] With this dimensioning, the web width, in particular the material thickness, is so small that the bulges are sufficiently large to provide three-point support and centering of the pin area 52 during insertion.
[0055] Although the pin portion 52 may also have play, in the preferred embodiment, it has an oversize of less than 200 μm and more than 10 μm when inserted into the respective bore. The maximum diameter of the pin portion then exceeds the maximum inside diameter of the respective bore 2 by a maximum of 200 μm.
[0056] The maximum diameter of the running gear teeth of the sun gear 50 is greater than twice the radial distance of the axis of rotation of the planets rotatably mounted on the bolts 20.
[0057] The planets mesh with a ring gear, which is non-rotatably connected to the planetary gear housing, and with another, rotatably mounted sun gear, which, together with the planets and the ring gear, forms a first gear stage of the planetary gear. Sun gear 50, on the other hand, belongs to a second gear stage, which has second planets and a second ring gear, with these second planets and the second ring gear also meshing with sun gear 50. The second planets, in turn, are rotatably mounted on a second planet carrier.
[0058] List of reference symbols
[0059] 1 Planet carrier 2 Central bore, especially for the pin of the sun gear
[0060] 3 Hole for planetary bolt
[0061] 20 planetary bolts
[0062] 40 radial bulge
[0063] 50 Sun gear 51 Spline, especially knurled spline
[0064] 52 Sun gear journal area 50
[0065] D1 maximum clear diameter of the central bore 2
[0066] D2 clear diameter of one of the holes for planetary bolts 20
Claims
Patent claims:
1. Planetary gear with planet carrier and sun gear, wherein the sun gear has a running toothing and a journal area, wherein the journal area is at least partially provided with a plug-in toothing, in particular knurled toothing, wherein the planet carrier has a central bore, in particular an axially through central bore, wherein the planet carrier has bores, in particular axially through bores, into which planet pins are pressed, wherein the bores are spaced from the central bore, wherein bulges in the material of the planet carrier protrude radially inwards into the central bore, which bulges center the journal area and / or into which the plug-in toothing, in particular knurled toothing, is cut.
2. Planetary gear according to claim 1, characterized in that the central bore is arranged centrally in the planet carrier, in particular wherein the axis of rotation of the rotatably mounted planet carrier is aligned coaxially to the bore axis of the central bore.
3. Planetary gear according to one of the preceding claims, characterized in that the bore axis of the central bore is aligned parallel to the respective bore axis of the bores.
4. Planetary gear according to one of the preceding claims, characterized in that the bores all have the same distance from the central bore, wherein the bores are all arranged at the same radial distance, in particular with respect to the axis of rotation of the planet carrier.
5. Planetary gear according to one of the preceding claims, characterized in that the maximum outer diameter of the running gear teeth is larger than the maximum outer diameter of the journal area.
6. Planetary gear according to one of the preceding claims, characterized in that planets, in particular planetary gears, are rotatably mounted on the planetary bolts, the planets being in engagement with a first ring gear and with a first sun gear, the running teeth of the sun gear being in engagement with second planets, which are in engagement with the internal teeth of a second ring gear and which are rotatably mounted on second bolts connected to a second planet carrier of the planetary gear.
7. Planetary gear according to one of the preceding claims, characterized in that the radial width of the bulges is less than one tenth of the clear diameter of the central bore.
8. Planetary gear according to one of the preceding claims, characterized in that the center of a respective gap of the plug-in toothing, in particular knurled toothing, seen in the circumferential direction has the same circumferential angular position as the center of a respective bulge seen in the circumferential direction.
9. Planetary gear according to one of the preceding claims, characterized in that the circumferential angular range covered by the respective bulge in the circumferential direction is encompassed by or overlaps with the circumferential angular range covered by the bore next adjacent to this bulge in the circumferential direction.
10. Planetary gear according to one of the preceding claims, characterized in that the area covered by the plug-in toothing, in particular knurled toothing, in the axial direction is encompassed by or is similar to the area covered by the pin area in the axial direction.
11. Planetary gear according to one of the preceding claims, characterized in that the maximum clear diameter D1 of the respective central bore (2) is greater than half the difference between D3, i.e. twice the axial distance between the axis of rotation of the planet, in particular planetary gear, rotatably mounted on the respective bolt and the axis of rotation of the planet carrier, and the maximum clear diameter D2 of the respective bore 3.
12. Planetary gear according to one of the preceding claims, characterized in that the central bore and the bores are arranged and dimensioned such that where D1 is the diameter of the central bore, D2 is the maximum inside diameter of the bore and D3 is twice the center distance between the axis of rotation of the planets rotatably mounted on the bolts and the axis of rotation of the planet carrier, in particular which is coaxially aligned to the axis of rotational symmetry of the sun gear.
13. A method for producing a planetary gear, in particular according to one of the preceding claims, wherein the planetary gear has a planetary carrier, wherein the planetary carrier has a central bore, in particular an axially through central bore, wherein the planetary carrier has bores, in particular axially through bores, wherein the bores are spaced from the central bore, in a first method step, planetary bolts are pressed into the bores, characterized in that when the bolts are pressed into the central bore, bulges of the material of the planetary carrier projecting radially inward are produced, wherein in a second method step following the first method step, the journal region of a sun gear is inserted into the central bore, wherein the journal region is centered by the bulges and a spline, in particular knurled spline,of the tenon area cuts and / or forms into the bulges., 14. Method according to one of the preceding claims, characterized in that the pin region has a cylindrical region spaced from the running toothing of the sun gear and has a further region arranged axially between the running toothing and the cylindrical region and provided with the plug-in toothing, in particular knurled toothing, wherein in the second method step when inserting the pin region, the cylindrical region is first centered between the bulges and then the plug-in toothing, in particular knurled toothing, of the pin region begins to cut into and / or form into the bulges.