Gear arrangement and electric drive with the gear arrangement

Abstract

Gear arrangement (1) for an electric drive (2), with a ring gear (3), wherein the ring gear (3) has a toothed area (4), with a hub (5), wherein the hub (5) has a mating toothed area (6), wherein the toothed area (4) engages in the mating toothed area (6), so that the hub (5) is positively connected to the ring gear (3) in a direction of rotation about a main axis (H) of the gear arrangement (1), characterized by the fact that the ring gear (3) has a press section (8) and the hub (5) has a counter press section (9), wherein the press section (8) and the counter press section (9) form a press fit (7).

Description

[0001] The invention relates to a gear arrangement having the features of the preamble of claim 1. The invention further relates to an electric drive having the gear arrangement.

[0002] Many vehicle transmissions feature planetary gears, for example, in the gear ratios or differential stages. Such planetary gears often comprise sun gears, planet carriers with planets, and ring gears, which mesh with each other. The sun gears, planet carriers, or ring gears can optionally form inputs, outputs, or support components. Therefore, these components must be mounted or arranged stationary depending on their function. When designing vehicle transmissions, the focus is not only on basic functions such as gear ratios, division, or combination of drive torques, but also on secondary functions such as production-oriented design, requirements related to the reduction of NVH (noise, vibration, harshness), etc.

[0003] DE 20 2014 103 462 U1 shows a drive device for an electric bicycle, in particular for a pedelec which is hybrid driven by an electric motor and muscle power, with a drive housing in which a multi-stage transmission is arranged which is connected on the one hand to an electric motor and on the other hand to a pedal crankshaft and contains a belt transmission and a gear transmission which are connected to one another via a coupling wheel, wherein the gear transmission is shielded from the belt transmission by means of a cover which is arranged concentrically to the coupling wheel and connected to the drive housing.

[0004] It is an object of the present invention to propose a gear assembly that fulfills both the basic functions and the secondary functions while simultaneously being implemented in a manner that is suitable for production. This object is achieved by a gear assembly having the features of claim 1 and by an electric drive having the features of claim 10. Preferred or advantageous embodiments are evident from the subclaims, the following description, and the accompanying figures.

[0005] The subject matter of the invention is a transmission arrangement which is suitable and / or designed for an electric drive for a vehicle. The transmission arrangement forms, in particular, part of the drive train of the vehicle. In particular, a drive torque is transmitted or supported by the transmission arrangement. The vehicle can be, in particular, a passenger car, truck, bus, etc., or even a two-wheeler or three-wheeler. The electric drive can form the exclusive drive of the vehicle, so that the vehicle is designed as an electric vehicle. In alternative embodiments, the vehicle can also be designed as a hybrid vehicle, so that in addition to the electric drive, another drive, such as a drive with an internal combustion engine, is provided.In particular, the electric drive can be designed as an electric axle, wherein the electric axle has two output shafts that are operatively connected to two driven wheels of the vehicle. In particular, the electric axle is arranged between the two driven wheels of the vehicle, wherein the two output shafts are positioned coaxially to each other.

[0006] The gear arrangement has a ring gear, preferably made of metal. The ring gear has a toothed area. The toothed area is preferably designed as an axial toothed area, with teeth extending in the axial direction. The toothed area can be a gear area, so that it is or could be designed for a meshing coupling. Alternatively, however, the teeth can also be designed such that they are sufficiently developed for a positive connection in the circumferential direction. For example, it is possible for only a few teeth, such as fewer than ten teeth, to be provided in the circumferential direction and / or for the teeth to be designed, for example, as webs, in particular axially extending webs. The toothed area is preferably designed as an external toothed area and / or is arranged on the outer circumference of the ring gear.The ring gear further comprises an internal toothing which is particularly preferably suitable and / or designed for meshing engagement with planets.

[0007] The gear arrangement has a hub, preferably made of metal. In particular, the hub is designed as a machine element which can be pushed onto the ring gear and / or wherein the ring gear can be pushed into the hub. The hub has a mating toothing region, wherein the mating toothing region engages with the toothing region, in particular to form a positive locking region. Due to the intermeshing of the toothing region and the mating toothing region and / or due to the positive locking region, the hub is positively connected to the ring gear in the circumferential direction. Preferably, the mating toothing region and the toothing region are designed to be complementary to one another, at least in sections. Preferably, the mating toothing region is designed as an internal toothing region and / or is arranged on the inner circumference of the hub. In particular, a plug-in toothed connection is formed by the toothing region and the mating toothing region.The gear assembly preferably has a housing section, wherein the hub is accommodated in the housing section in a stationary manner, particularly preferably rigidly and / or without tolerances with respect to the direction of rotation. The housing section can, for example, form part of a housing of the electric drive.

[0008] Within the scope of the invention, it is proposed that the ring gear has a press section and the hub has a counter-press section, wherein the press section and the counter-press section form an interference fit. In a general embodiment of the invention, the interference fit is designed as a longitudinal interference fit, a transverse interference fit, or an oil interference fit.

[0009] Particularly preferably, the press section and the counter-press section are joined together in an axial direction with respect to a main rotational axis of the gear arrangement, wherein a positive connection in the radial direction to the main axis subsequently occurs in the press connection. In particular, radial forces between the hub and the ring gear can be transmitted in a positive-locking manner. It is preferred that the hub, in particular the counter-press section, encompasses the ring gear, in particular the press section, in the radial direction. The press fit and the positive-locking connection and / or spline connection between the toothing region and the counter-toothing region preferably form parallel connections between the ring gear and the hub.

[0010] One advantage of the invention is that the interference fit centers the ring gear in the hub as soon as it is mounted. Furthermore, additional axial forces can be absorbed in a force-fitting manner thanks to the frictional connection in the interference fit. The interference fit can be implemented with virtually no impact on the installation space. An optional advantage of the interference fit is that the contact pattern on the ring gear can be influenced and, in particular, optimized. The interference fit means that the ring gear is arranged in the hub with no radial play. The interference fit connects the ring gear to the hub and thus to the housing section and / or the housing of the electric drive to form a single unit, significantly improving NVH behavior.

[0011] In a preferred embodiment of the invention, the spline connection, which is formed by the toothing area and the counter-toothing area, is functionally designed so that the entire torque is transmitted in the circumferential direction via the spline.

[0012] For implementation, it is particularly preferred that the spline connection be designed to be free of play and / or tolerances in the circumferential direction. This prevents the pressing section from moving relative to the counter-pressing section in the circumferential direction when the direction of rotation in the gear assembly is reversed. This leads to a further improvement in NVH behavior.

[0013] In an advantageous embodiment, the pressing section has a pressing shoulder and / or the counter-pressing section has a shoulder receptacle. The pressing shoulder is particularly preferably formed as an additional section in or on the ring gear. The shoulder receptacle is preferably formed as an inner contour of the hub.

[0014] It is particularly preferred that the press shoulder has a cylindrical pressing surface on the outer circumference. More preferably, the press surface is implemented as a straight cylindrical surface. In a preferred development of the invention, the press shoulder has a cylindrical support surface on the inner circumference, wherein the cylindrical support surface is particularly preferably designed as a straight cylindrical surface. Overall, it is preferred that the press shoulder is designed as an annular section, which preferably forms an axial edge section of the ring gear. More preferably, no internal toothing of the ring gear is provided in the axial region of the annular section. This configuration is based on the consideration that, due to the interference fit, the annular section has a smaller ring width in the radial extent than the ring gear in the axial region of the internal toothing, so that the internal toothing would have a different load-bearing capacity in this region.Because the internal toothing is recessed in the axial area of ​​the ring section, effects on the basic function of the ring gear are avoided.

[0015] It is particularly preferred that the press shoulder is formed integrally with the ring gear. In particular, the ring gear is formed with the press shoulder as a common material section, which—depending on the manufacturing process—is manufactured from a common, one-piece semi-finished product. Alternatively or additionally, it is preferred that the shoulder receptacle is formed integrally with the hub. In particular, the hub is formed with the shoulder receptacle as a common material section, which—depending on the manufacturing process—is manufactured from a common, one-piece semi-finished product.

[0016] It is advantageous for the ring gear to be inserted into the hub in a plug-in direction, with the pressing section located on an inner side of the ring gear. This ensures that the toothing area and the counter-toothing area already mesh during assembly and perform a pre-centering. The pre-centered ring gear can then be easily inserted, in particular pressed, into the hub.

[0017] Particularly preferably, the hub has a mechanical end stop for the ring gear, wherein the mechanical end stop has a larger pitch diameter than the press section, the counter-press section, and / or the ring section. In this embodiment, the ring gear is already radially centered after mechanical joining and, viewed axially, has a defined end position and / or installation position. This precise adjustment of the ring gear in the hub can be implemented easily and error-free during the assembly process.

[0018] To axially secure the ring gear in the hub, particularly in the mating direction, it is preferred that the gear arrangement has a grooved ring. The grooved ring is optionally designed as a retaining ring or as a lamellar ring. Particularly preferably, the grooved ring has an interruption so that its diameter can be reduced for assembly in an assembled state and has a larger diameter in an operating state than in the assembled state. Particularly preferably, the grooved ring has freely extending ends which do not protrude beyond an inner diameter or an outer diameter of the grooved ring, wherein the respective diameter is defined, for example, by a region of the grooved ring which is arranged diametrically or opposite the ends. The grooved ring is preferably made of metal.

[0019] To accommodate the grooved ring, the hub has a locking groove located on the inner circumference of the hub. Particularly preferably, the grooved ring and / or the locking groove are arranged axially offset from the ring gear and / or act on an axial side surface of the ring gear. The grooved ring thus implements an axial end stop in the mating direction and / or a positive, axial locking of the ring gear in the installed position and / or end position.

[0020] In principle, it is possible for the grooved ring to bear directly against the ring gear, but in order to increase the contact surface between the grooved ring and the ring gear, it is preferred that a spacer disc is arranged between the grooved ring and the ring gear, wherein the spacer disc bears against the ring gear with one axial end face and against the grooved ring with the other axial end face.

[0021] A further object of the invention is formed by an electric drive, in particular as described above, wherein the electric drive has the gear arrangement as described above or according to one of the preceding claims. The electric drive has at least one planetary stage, wherein the planetary stage is designed as a transmission section for transmitting a drive torque and / or as a differential section for dividing the drive torque, in particular between the two output shafts. The planetary stage preferably has at least one planet carrier with planets, wherein the planets are rotatably arranged on the planet carrier and mesh with the ring gear. Preferably, the planetary stage has a sun gear, wherein the sun gear can form an input into the planetary stage.

[0022] Further features, advantages, and effects of the invention will become apparent from the following description of a preferred embodiment of the invention and the accompanying figures. These show: Fig. 1 is a schematic, three-dimensional longitudinal sectional view of a gear arrangement for an electric drive as an embodiment of the invention; Fig. 2 a schematic, three-dimensional view of a ring gear in the gear arrangement in the Fig. 1;

[0023] The Fig. 1 shows a schematic, three-dimensional representation of a transmission arrangement 1 as an exemplary embodiment of the invention. The transmission arrangement 1 forms part of an electric drive 2, wherein the electric drive 2 is designed for a vehicle. For example, the electric drive 2 is implemented as an electric axle with an electric motor. The transmission arrangement 1 forms, for example, part of a planetary stage, wherein a drive torque of the electric motor is translated and / or divided. In particular, the transmission arrangement 1, as a planetary stage, can form a transmission section and / or a differential section. The transmission arrangement 1 defines a main axis H.

[0024] The gear assembly 1 comprises a ring gear 3. The ring gear 3 has an internal toothing, wherein the internal toothing in this embodiment is realized as a helical toothing. In the electric drive 2, planetary gears (not shown) mesh with the internal toothing of the ring gear 3. The ring gear 3 has a circumferential toothing region 4, which is formed on an outer circumference of the ring gear 3. The toothing region 4 has teeth 19 ( Fig. 2) and tooth bases 20 ( Fig. 2), which are arranged alternately and / or in a uniform grid in the direction of rotation around the main axis H. The teeth 19 are designed as axially extending webs, and the tooth bases 20 are arranged as axially extending grooves between the teeth 19.

[0025] The gear assembly 1 has a hub 5, wherein the hub 5 is stationary in a housing section of the gear device 2. The hub 4 has a counter-toothing region 6, wherein the counter-toothing region 6 is arranged, in particular formed, on an inner circumference of the hub 4. The counter-toothing region 6 has counter-teeth and counter-tooth roots. The counter-teeth and counter-tooth roots are arranged alternately in the circumferential direction around the main axis H and / or each in a uniform grid. The counter-teeth are designed as axially extending webs, and the counter-tooth roots are designed as axially extending grooves.

[0026] When the gear assembly 1 is assembled, the toothing area 4 engages with the counter-toothing area 6, so that the ring gear 3 and the hub 5 are positively connected to one another in the direction of rotation around the main axis H. In particular, a spline connection and / or a shaft / axle-hub connection is formed. During operation, drive torques are supported via the ring gear 3, and corresponding forces are transmitted via the hub 5 into the housing section.

[0027] The gear assembly 1 has an interference fit 7, wherein the interference fit 7 is formed by a press section 8 of the ring gear 3 and a counter-press section 9 of the hub 5. The interference fit 7 secures the ring gear 3 in the hub 5 in a form-fitting manner in the radial direction relative to the main axis H and in a force-fitting manner in the axial direction relative to the main axis H. The press section 8 lies in the counter-press section 9 in a press fit.

[0028] The pressing section 8 is designed as a pressing shoulder 10, wherein the pressing shoulder 10 and thus the pressing section 8 are formed integrally on the ring gear 3. The pressing shoulder 10 is designed as an annular section which extends coaxially to the main axis H. The pressing shoulder 10 has a cylindrical pressing surface 11, wherein the pressing surface 11 is designed as a straight cylindrical surface which extends coaxially to the main axis H. The pressing surface 11 is arranged on the outer circumference of the pressing shoulder 10. On the inner circumference of the pressing shoulder 10, a supporting surface 12 is arranged which is designed as a straight cylindrical surface which extends coaxially to the main axis H. The supporting surface 12 is arranged without contact. In other embodiments, the supporting surface 12 can also be formed as a bevel. The axial end face of the pressing shoulder 10 lies in a radial plane to the main axis H.

[0029] The counter-pressing section 9 is designed as a shoulder receptacle 13, which supports a counter-pressing surface 14. The counter-pressing surface 14 is designed as a straight cylindrical surface extending coaxially to the main axis H. The counter-pressing surface 14 transitions into a conical section arranged without contact. The shoulder receptacle 13 and in particular the counter-pressing surface 14 are formed on the hub 5 and / or are formed integrally with it.

[0030] During assembly, the ring gear 3 is inserted into the hub 5 in a plug-in direction S. The engagement of the toothed area 4 with the counter-toothed area 6 pre-centers the ring gear 3 in the hub 5. Upon further insertion of the ring gear 3 into the hub 5, the press shoulder 10 slides into the shoulder receptacle 13, thus creating the interference fit 7.

[0031] The toothing area 4 and the counter-toothing area 6 are designed as a flank-centered plug-in connection, which is designed to be free of play and / or tolerances in the circumferential direction, so that the entire torque is transmitted via the plug-in connection formed by the toothing area 4 and the counter-toothing area 6. In particular, the pressing shoulder 10 is arranged rigidly and / or immovably relative to the shoulder receptacle 13 in the circumferential direction.

[0032] On the axially opposite side of the ring gear 3 to the interference fit 7, a grooved ring 15 is arranged, which lies in a form-fitting manner in the axial direction in a securing groove 16, wherein the securing groove 16 is introduced into an inner circumference of the hub 5. The grooved ring 15 serves to axially secure the ring gear 3 in the hub 5 in a counter-plugging direction. In order to enlarge the contact surface on the ring gear 3, a spacer disk 17 is arranged between the grooved ring 15 and the ring gear 3. The spacer disk 17 is designed to be closed all the way around, while the grooved ring 15 is designed to be open once all the way around. The spacer disk 17 rests with one axial end face against an axial end face of the ring gear 3. The other axial end face of the spacer disk 17 rests against the grooved ring 15.

[0033] Furthermore, the hub 15 has a mechanical end stop 18, against which the ring gear 3 rests flatly with another axial end face. Thus, the ring gear 3 is positively secured on one axial side by the end stop 18 and on the other axial side by the grooved ring 15, optionally with the spacer disk 17. In the radial direction, the ring gear 3 is positively secured by the interference fit 7. In the circumferential direction, the ring gear 3 is positively secured by the spline connection.

[0034] Thus, the ring gear 3 is positively mounted in the hub 5 in all directions and is held at least in the circumferential direction and radial direction and optionally additionally in the axial direction without tolerances and / or play.

[0035] In the Fig.2, the ring gear 3 is shown in a schematic three-dimensional representation, with the toothing area 4 being visible on the outer circumference. The toothing area 4 is formed by the teeth 19 and the tooth roots 20. The teeth 19 are designed as axially extending webs. The tooth roots 20 lie between the teeth 19 and are designed as axially extending grooves. The counter-toothing area 6 is designed to be complementary to this. The press shoulder 10 can be seen as an annular section. If one considers the axial division of the ring gear 3, a first axial area is formed by the toothing area 4 and a second, adjoining axial area is formed by the press shoulder 10, so that the press shoulder 10 does not weaken the toothing area 4. However, it is possible to influence the contact pattern of the toothing area 4 or the internal teeth of the ring gear 3 by designing the press shoulder 10. List of reference symbols 1 Gear arrangement 2 electric drive 3 ring gear 4 Gearing area 5 Hub 6 Counter-toothing area 7 Press association 8 Pressing section 9 Counter-press section 10 Press shoulder 11 Pressing surface 12 Support surface 13 Shoulder shot 14 Counter-pressing surface 15 Grooved ring 16 locking groove 17 spacer disc 18 End stop 19 teeth 20 dental reasons S Plug direction H main axis

Claims

[1] Gear arrangement (1) for an electric drive (2), with a ring gear (3), wherein the ring gear (3) has a toothed area (4), with a hub (5), wherein the hub (5) has a counter-toothing region (6), wherein the toothing region (4) engages in the counter-toothing region (6), so that the hub (5) is positively connected to the ring gear (3) in a circumferential direction about a main axis (H) of the gear arrangement (1), characterized by , that the ring gear (3) has a pressing section (8) and the hub (5) has a counter-pressing section (9), wherein the pressing section (8) and the counter-pressing section (9) form a press fit (7). [2] Gear arrangement (1) according to claim 1, characterized by that the pressing section (8) is designed as a pressing shoulder (10) and / or the counter-pressing section (9) is designed as a shoulder receptacle (13). [3] Gear arrangement (1) according to claim 2, characterized bythat the pressing shoulder (10) has a cylinder-shaped pressing surface (11) on the outer circumference. [4] Gear arrangement (1) according to claim 2 or 3, characterized by that the press shoulder (10) has a cylinder jacket-shaped support surface (12) on the inner circumference. [5] Gear arrangement (1) according to one of claims 2 to 4, characterized by that the pressing shoulder (10) is designed as a ring section. [6] Gear assembly (1) according to one of claims 2 to 5, characterized by that the pressing shoulder (10) is formed integrally with the ring gear (3) and / or that the shoulder receptacle (13) is formed integrally with the hub (5). [7] Gear arrangement (1) according to one of the preceding claims, characterized by that the ring gear (3) is inserted into the hub (5) in a plug-in direction (S), wherein the pressing section (8) is arranged on an inner side of the ring gear (3). [8] Gear arrangement (1) according to one of the preceding claims, characterized by that the ring gear (3) is secured in the hub (5) by a grooved ring (15) in the axial direction. [9] Gear arrangement (1) according to claim 8, characterized by a spacer disc (17), wherein the spacer disc (17) is arranged between the retaining ring (15) and the ring gear (3). [10] Electric drive (2) for a vehicle, characterized by a gear arrangement (1) according to one of the preceding claims.

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