Arrangement for axially securing the position of a sun gear of a planetary gear stage on a rotor shaft of an electric machine and use of such an arrangement

Abstract

Arrangement for axially securing a sun gear (1) of a planetary gear stage on a rotor shaft (2) of an electric machine, wherein the sun gear (1) has an end section (8) offset radially outwards at its inner diameter and is axially fixed on the rotor shaft (2) by at least one retaining ring (6), and in order to secure against the centrifugal forces acting on the retaining ring (6) during rotation of the rotor shaft (2) at least one locking element (9) is provided, which is inserted into the end section (8) on the sun gear (1) for fastening and is at least partially pushed over the retaining ring (6) and secures it radially, characterized by the fact that the locking element (9) is positively inserted into the sun wheel (1), wherein the locking element (9) is designed as a locking sleeve which is axially pressed into the radially offset end section (8) of the sun gear (1), wherein the locking sleeve is angled radially inwards with an end section (10) and radially encompasses the locking ring (6) at the outer diameter with its free end face, wherein the locking sleeve with an end section (10) is angled at a right angle radially inwards and rests axially over a radial ring shoulder (5) formed on the inner diameter of the sun gear (1) and the locking element (9) has several openings (11) for the attack of a puller for disassembly.

Description

Field of invention

[0001] The invention relates to an arrangement for axially securing the position of a sun gear of a planetary gear stage on a rotor shaft of an electric machine and to the use of such an arrangement according to the type defined in more detail in the preamble of claim 1 or 5.

[0002] From DE 10 2011 082 017 A1, a bearing arrangement for a drive device with at least one electric machine is known. This arrangement provides a first and second rolling bearing for supporting the rotor shaft of an electric machine. The rolling bearings are each fixed to the rotor shaft by a retaining ring inserted into a shaft groove. A disadvantage of this design is that, on rotor shafts in electric machines at speeds of approximately 6000 rpm and above, the centrifugal forces acting during operation can cause simple standard retaining rings to expand and loosen, thus compromising axial retention on the rotor shaft. Therefore, in such cases, the use of special retaining rings, particularly those with a so-called self-locking function, is necessary. These are self-contained and therefore cannot open under centrifugal force.The use of special retaining rings is expensive and, in series production, can only be implemented with considerable effort or by hand. Furthermore, disassembly is usually only possible by destroying the retaining ring.

[0003] DE 10 2014 217 129 A1 discloses a starting device for an internal combustion engine, with an electric starter motor whose drive motion can be transmitted via a gearbox to a starter pinion, wherein the rotor shaft of the starter motor is rotatably mounted in a bearing adjacent to its end faces, wherein the gearbox-side bearing is supported on a bearing shield which is arranged on the end face of a pole housing of the starter motor, wherein the bearing on the side facing away from the gearbox is designed as a radial bearing without axial support of the rotor shaft and that the rotor shaft is supported on the bearing shield in both axial directions.

[0004] DE 75 35 901 U discloses a snap ring connection for the axial fixing of a machine part on a shaft, wherein the snap ring transmitting the axial forces is held radially in a recess of the machine part by means of a support ring, and that the support ring is axially fixed with a snap ring sitting in a groove of the machine part, which sits in the groove with a small offset.

[0005] DE 40 079 42 C1 discloses a securing of a radially slotted shaft retaining ring against centrifugal force-induced widening by an axially fixed, radially closed slip-on ring encompassing the retaining ring in a form-fitting manner, wherein the slip-on ring is an angle ring whose radially oriented leg rests radially resiliently on the shaft of the shaft retaining ring, at least in a force-fit manner.

[0006] DE 10 2017 005 462 A1 discloses a drive device for a motor vehicle, comprising at least one first wheel assigned to an axle of the motor vehicle, at least one second wheel assigned to the axle, a first electric machine, a second electric machine, a first transmission device via which the first wheel can be driven by the first electric machine, and a second transmission device via which the second wheel can be driven by the second electric machine, wherein the respective transmission device has at least two planetary gear sets connected in series. Summary of the invention

[0007] The invention is based on the objective of simplifying the design and assembly of an arrangement of the aforementioned type and making it more reliable in operation. Furthermore, it is an objective of the invention to propose a use for an arrangement of the aforementioned type.

[0008] The problem is solved by the features of claim 1 and, alternatively, by the features of claim 5. Further advantageous embodiments will become apparent from the respective dependent claims, the description, and the drawings.

[0009] An arrangement for axially securing a sun gear of a planetary gear stage on the rotor shaft of an electric machine is proposed. According to the invention, the sun gear has an end section with a radially outward offset at its inner diameter and is axially secured to the rotor shaft by at least one retaining ring. To secure the retaining ring against the centrifugal forces acting on it during rotation of the rotor shaft, at least one locking element is provided. This locking element is inserted into the end section of the sun gear and at least partially slid over the retaining ring, thus securing it radially. In this way, a simple and easily installed centrifugal locking mechanism for the retaining ring is achieved, which is at least partially integrated into the sun gear, thus saving installation space.This reliably prevents centrifugal force-induced expansion and loosening of the retaining ring during operation, and allows the use of easily manufactured and installed standard retaining rings on the rotor shafts of electric machines, regardless of their rotational speed. Conversely, expensive special retaining rings or other complex solutions that are difficult to manufacture and install become unnecessary.

[0010] It is advantageous if the locking element is positively inserted into the sun gear for fastening. This makes the assembly particularly easy to assemble and disassemble without damage. Other detachable form-fit or form- and force-fit connections are also conceivable, especially a snap-fit ​​connection.

[0011] According to the invention, the locking element is designed as a locking sleeve which is axially pressed into the radially outwardly offset end section of the sun gear. A particularly advantageous feature is that the locking sleeve is completely integrated into the sun gear, thus saving installation space.

[0012] The locking sleeve has one end section angled radially inwards, such that its free end face radially encompasses the retaining ring at its outer diameter. This design allows for a centrifugal locking mechanism for the retaining ring that can be easily adapted to the installation conditions. Furthermore, the locking element is easily manufactured as a so-called angled sleeve.

[0013] It is further provided according to the invention that the locking sleeve with an end section angled at right angles radially inwards rests axially on a radial ring shoulder formed on the inner diameter of the sun gear.

[0014] According to the invention, particularly easy disassembly is made possible if the locking element has several openings for the attack of a puller.

[0015] The locking element can advantageously be manufactured easily and without machining, particularly from sheet metal or plastic.

[0016] In the arrangement according to the invention, it is particularly advantageous to use at least one standard retaining ring, for example a Seeger retaining ring type SW, to axially secure the position of the sun gear on the rotor shaft, independent of the rotational speed. This retaining ring can be mass-produced cost-effectively and can be simply slipped onto the rotor shaft and secured in a retaining groove on the outer diameter of the rotor shaft. It can also be easily removed without damage.

[0017] The arrangement according to the invention enables the sun gear to be positioned in an end region of the rotor shaft and axially secured. Preferably, its radially offset end section projects axially beyond the end of the rotor shaft. This allows for the space-saving integration, at least partially, of another component in the offset end section of the sun gear, in addition to the locking element. For example, a seal arranged coaxially with the locking sleeve can engage radially in the end section of the sun gear that projects beyond the end of the rotor shaft and be pressed against its inner diameter for sealing. In a particularly advantageous manner, the seal can be supported by its inner diameter on the outer diameter of a shaft that passes coaxially through the hollow rotor shaft for sealing purposes.

[0018] The object of the invention is also achieved by using the arrangement according to the invention in an electric axle drive of a vehicle. In this case, the arrangement with the sun gear and the rotor shaft, together with the electric machine, forms an electric drive as part of the axle drive of the vehicle. Preferably, a shaft is routed through the rotor shaft as the output shaft of the electric axle drive, thus saving installation space. Brief description of the drawings

[0019] Further features of the invention will become apparent from the following description and from the drawings, in which a simplified embodiment of the invention is shown. The drawings show: Fig. 1 a cutaway view of an arrangement according to the invention for axially securing a sun gear on a rotor shaft of an electric machine, Fig. 2 an enlarged section from Fig. 1, Fig. 3 and Fig. 4 Individual views of a locking element of the arrangement according to the invention, Fig. 5 a cutaway view of a safety element made of Fig. 3 and Fig. 4, Fig. 6 an enlarged section from Fig. 5. Detailed description of the drawings

[0020] Fig. 1 and Fig. Figure 2 shows an exemplary arrangement according to the invention for axially securing a sun gear 1 of a planetary gear stage on a rotor shaft 2 of an electric machine. The sun gear 1 is fixedly mounted on the rotor shaft 2 and engages with a set of planet gears 3 of the planetary gear stage (not shown) for driving. The rotor shaft 2 carries a coaxially arranged rotor 4 of the electric machine. On the axial side facing away from the rotor, the sun gear 1 has a radially outward-facing annular shoulder 5 on its inner diameter and is axially secured at this shoulder by a retaining ring 6 arranged on the rotor shaft 2. The retaining ring 6 secures the sun gear 1 axially against the annular shoulder 5 and is inserted into a retaining groove 7 on the outer diameter of the rotor shaft 2 for fastening.The ring shoulder 5 defines an end section 8 of the sun gear 1, which is offset radially outwards at its inner diameter. A locking element 9 is coaxially inserted into this end section at the end of the sun gear 1 facing away from the rotor. The locking element 9, acting as a mounting stop against the ring shoulder 5, is pushed radially over the retaining ring 6, which rests axially against the ring shoulder 5. This secures the retaining ring 6 radially at its outer diameter.

[0021] The locking element 9 is designed as a locking sleeve, which is fully axially pressed into the inner diameter of the radially outwardly annularly offset cylindrical end section 8 of the sun gear 1 with its outer diameter ( Fig. 1 and Fig. 2) The locking sleeve 9 is angled radially inwards at a right angle with an end section 10, thus forming a so-called angled sleeve ( Fig. 3 to 5). It rests axially against the ring shoulder 5 with its angled end section 10, acting as a mounting stop ( Fig. 2) With its free end face 17 of the end section 10, the locking sleeve 9 radially surrounds the entire outer diameter of the retaining ring 6 in an annular fashion. In this way, it prevents the retaining ring 6 from opening under centrifugal force and from detaching from the rotor shaft 2. This makes it particularly advantageous to use a standard external retaining ring, for example of the Seeger SW type, for axially securing the sun gear 1 to the rotor shaft 2. Such a retaining ring is easy to install and remove without damage. The retaining ring 6 is radially enclosed by the locking sleeve 9, which is fully integrated into the sun gear 1, to prevent centrifugal force.

[0022] The locking sleeve 9, together with the radially angled end section 10, forms a right-angled L-shaped longitudinal profile as a so-called angle sleeve or L-disc ( Fig. 3 to 6). The outer diameter d1 of the locking sleeve 9 is selected such that it forms an interference fit with the inner diameter of the radially outwardly annularly offset end section 8 of the sun gear 1, while the inner diameter d2 of the locking sleeve 9 formed at the free end face 17 of the angled end section 10 has a size that allows the locking sleeve 9 to be slid over the outer diameter of the retaining ring 6 with a small amount of radial play during assembly. In the area of ​​the 90° bend at the base of the angled end section 10 of the locking sleeve 9, several openings 11 are provided, evenly distributed around the circumference ( Fig. 6), which are designed as radial through-holes into which a puller can engage at the inner diameter of the retaining sleeve 9 in order to pull the retaining sleeve 9 out of the sun gear 1. In this way, non-destructive disassembly of the retaining sleeve 9 and the retaining ring 6 is possible.

[0023] The sun gear 1 with the ring shoulder 5 and the retaining ring 6 are arranged at one end of the rotor shaft 2, with the end section 8 of the sun gear 1 projecting beyond the end of the rotor shaft 2. This allows a seal 16, arranged coaxially with the retaining sleeve 9, to engage radially in the radially shouldered end section 8 of the sun gear 1 and be integrated against its inner diameter. Fig. 1 and Fig. 2).

[0024] In this way, the locking sleeve 9 and the seal 16 can be arranged coaxially one behind the other in the offset end section 8 of the sun wheel 1 in a space-saving manner.

[0025] The arrangement according to the invention is particularly advantageous for use in an electric axle drive of a vehicle ( Fig. 1 and Fig. 2) Here, the arrangement with the sun gear 1 and the rotor shaft 2 of the electric machine forms part of the axle drive. The bearings 12 form the rotor shaft bearings. The rotor shaft 2 is designed as a hollow shaft through which a shaft 15 passes coaxially. This forms an output shaft of the electric axle drive, with the seal 16 bearing its inner diameter against the outer diameter of the shaft 15 for sealing purposes. Reference symbol list 1 sun wheel 2 Rotor shaft 3 planetary gear 4 Rotor 5 ring heel 6 retaining ring 7 locking groove 8 Final Section 9 locking element, locking sleeve 10 Final Section 11 Opening 12 warehouses 13 warehouses 14 cases 15 wave 16 Seal 17 End d1 outer diameter d2 inner diameter

Claims

[1] Arrangement for the axial position securing of a sun gear (1) of a planetary gear stage on a rotor shaft (2) of an electrical machine, wherein the sun gear (1) has an end section (8) which is offset radially outwards on the inner diameter and is axially fixed on the rotor shaft (2) by at least one retaining ring (6), and for securing against the centrifugal forces acting on the retaining ring (6) during rotation of the rotor shaft (2), at least one securing element (9) is provided which is inserted into the end section (8) on the sun gear (1) for fastening and is pushed at least partially over the retaining ring (6) and secures it radially, characterized by , that the locking element (9) is inserted into the sun gear (1) in a force-locking manner, wherein the securing element (9) is designed as a securing sleeve which is pressed axially into the radially offset end section (8) of the sun gear (1), wherein the securing sleeve is angled radially inwards with an end section (10) and radially encloses the securing ring (6) at the outer diameter with the free front end, wherein the securing sleeve, with an end section (10) angled radially inwards at right angles, lies axially against a radial annular shoulder (5) formed on the inner diameter of the sun gear (1) and the securing element (9) has a plurality of openings (11) for engagement of a removal tool for disassembly. [2] Arrangement according to claim 1, characterized by that the securing element (9) is produced by forming without cutting. [3] Arrangement according to one of claims 1 or 2, characterized by that the retaining ring (6) is designed as a standard retaining ring which is placed on the rotor shaft (2) and fastened in a retaining groove (7) on the outer diameter of the rotor shaft (2). [4] Arrangement according to one of claims 1 to 3, characterized bythat the sun gear (1) is arranged in an end region of the rotor shaft (2) and projects axially with the radially offset end section (8) beyond the end of the rotor shaft (2). [5] Use of an arrangement according to one of claims 1 to 4, characterized by that the arrangement is used in an electric axle drive of a vehicle.

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