Gear rim assembly for a spur gear, spur gear, drive unit for a motor vehicle, and motor vehicle

Abstract

The invention relates to a gear rim assembly (2), a spur gear (2), a drive unit (3) and a motor vehicle. A first helical gear rim (5) and a gear body (8) of a spur gear element (7) are rotationally fixedly connected to a gear shaft (4) of the gear rim assembly (1). A second helical gear rim (6) with a larger tip diameter than the first gear rim (5) is formed on the gear body (8), wherein the gear body (8) comprises a reinforcing structure (12) with reinforcing ribs (13) on the wheel body reinforcing side (13) axially facing the first gear rim (5), said reinforcing ribs being inclined in relation to a radius (17) of the second gear rim (6) in such a way that a radially outer reinforcing rib end (15) of the respective reinforcing rib (13) is in advance of a radially inner reinforcing rib end (16) of the same reinforcing rib (13) when the gear rim assembly (1) is rotated in the preferred direction of rotation (11). The gear rim assembly (1) is designed such that, when it is rotated in the preferred direction of rotation (11), and when the second gear rim (6) is a drive element of the gear rim assembly (1), an axial force (19) originating in a tooth engagement zone (18) of the second gear rim (6) is directed away from the first gear rim (5).

Description

[0001] Gear ring arrangement for a spur gear, spur gear, drive unit for a motor vehicle and motor vehicle

[0002] The present invention relates to a gear ring assembly for a spur gear transmission and to a spur gear transmission having such a gear ring assembly. Furthermore, the invention relates to a drive unit having such a spur gear transmission and a motor vehicle equipped with such a drive unit.

[0003] In the automotive industry, there is a general need to build particularly lightweight vehicles that are particularly energy-efficient and low-emission. Therefore, current efforts are being made to design automotive transmissions that are particularly mass-efficient. However, the current trend toward using electric motors as prime movers in motor vehicles is making this more difficult, as the torque provided by the electric motor is particularly high, requiring particularly stable and consequently heavy transmissions. There is therefore a need to optimize automotive transmissions in terms of strength and mass, i.e., to design them to be particularly lightweight without compromising transmission performance. In addition, other constraints must be met, particularly requirements regarding transmission acoustics, installation space limitations, etc.

[0004] DE 10 2021 208 663 A1 discloses a gear body in a structure-borne sound-reducing lightweight design for electric drives, comprising a gear ring and a wheel hub. The wheel hub has a structured web extending essentially within a radial plane between a shaft seat and the gear ring. The web has rib-like, thickened spiral structures that extend from the shaft seat to the gear ring. The spiral structures are aligned such that their spiral shape impinges at least on the gear ring at an oblique angle.

[0005] DE 10 2019 130 185 A1 discloses a spur gear comprising a radially outwardly arranged, spur-toothed gear ring and a radially inwardly arranged hub, which are spaced apart from each other by a rotationally symmetrical radial connection structure. The radial connection structure comprises a disk-shaped base body with a front and a rear side and penetrated by axial openings. Struts are arranged on the front side of the base body and extend between the hub and the gear ring, with the axial openings being arranged between the struts.

[0006] The object of the present invention is to improve spur gears with regard to acoustics, strength and weight.

[0007] This problem is solved by the subject matter of the independent claims. Further possible embodiments of the invention are disclosed in the subclaims, the description, and the figures. Features, advantages, and possible embodiments presented in the description for one of the subject matter of the independent claims are to be regarded, across categories and embodiments, at least analogously as features, advantages, and possible embodiments of the respective subject matter of the other independent claims, as well as any possible combination of the subject matter of the independent claims, optionally in conjunction with one or more of the subclaims.

[0008] According to the invention, a ring gear arrangement is proposed. Furthermore, according to the invention, a spur gear transmission is proposed which has the ring gear arrangement as a component. The spur gear transmission forms a component of a drive unit for a motor vehicle, which is also proposed according to the invention. The drive unit is, for example, a drive train for the motor vehicle, wherein the drive unit can have an internal combustion engine as the traction machine. Alternatively or additionally, the drive unit has an electric traction machine as the traction machine. Thus, the drive unit can further have a drive axle or a wheel-individual drive unit or be formed by such a drive unit. The motor vehicle represents a further subject matter of the invention, wherein the drive unit forms a component of the motor vehicle.If the drive unit has an electric traction machine as an alternative or in addition to the internal combustion engine, the motor vehicle is designed to be driven purely electrically or hybrid-electrically.

[0009] The gear ring arrangement has a transmission shaft and a first helical gear ring which is connected to the transmission shaft in a rotationally fixed manner. The gear ring arrangement also has a spur gear element which has a gear body which is connected to the transmission shaft in a rotationally fixed manner. A second helical gear ring is formed on the gear body, i.e. on its outer circumference, which second gear ring has a larger tip diameter than the first gear ring. The two gear rings are arranged one behind the other or next to one another with respect to a transmission shaft longitudinal center axis of the transmission shaft, with a longitudinal center axis of the first gear ring and a longitudinal center axis of the second gear ring coinciding with the transmission shaft longitudinal center axis. The gear body has two gear body sides (end faces) which point axially away from one another, one of which forms a gear body stiffening side.The wheel body stiffening side faces axially toward the first gear ring and comprises a stiffening structure with stiffening ribs. The stiffening structure is, in particular, forged, resulting in particularly high stiffness and strength of the stiffening structure. Alternatively or additionally, other forming or machining processes can be used to produce the stiffening structure. For example, the stiffening structure can be produced by sintering or 3D printing. With respect to a radius of the second gear ring, the stiffening ribs are each inclined in the circumferential direction such that a radially outer stiffening rib end of the respective stiffening rib leads a radially inner stiffening rib end of the same stiffening rib when the gear ring arrangement rotates in the preferred direction of rotation.The stiffening ribs are inclined relative to respective imaginary straight lines running radially from the inside to the outside, whereby these straight lines and the stiffening ribs each enclose an angle of inclination that is greater than 0 degrees and less than 90 degrees. If the stiffening ribs are imaginarily extended beyond their radially inner ends, they do not intersect at the center point of the spur gear element, through which the longitudinal center axis of the spur gear element or the second gear ring runs. The stiffening structure thus forms a type of turbine design or turbine-like gear body geometry with its stiffening ribs. Furthermore, the gear ring arrangement is designed such that when it rotates in the preferred direction of rotation, while the second gear ring is the drive element of the gear ring arrangement, an axial force based in a tooth engagement zone of the second gear ring points away from the first gear ring.In other words, the gear ring arrangement, in particular its spur gear element, is designed such that the wheel body stiffening side with the stiffening structure faces away from that wheel body side of the wheel body from which the axial force acts in the axial direction away from the spur gear element when the latter is in traction operation in the preferred direction of rotation, i.e. when a torque driving the gear ring arrangement is introduced into the gear ring arrangement via the second gear ring.

[0010] As a component of the spur gear, the ring gear assembly is installed in the drive unit of the motor vehicle. For the motor vehicle having the drive unit, the ring gear assembly or the spur gear assembly is arranged in the drive unit or motor vehicle in such a way that, with increasing forward acceleration of the motor vehicle, the second ring gear is rotated in the preferred direction of rotation by means of the traction motor.

[0011] According to a possible further development of the drive unit, the second gear ring and an output gear ring of the traction motor mesh directly with each other. With respect to a torque transmission path, the second gear ring and the meshing output gear ring then represent the first gear stage of the drive unit. Alternatively or additionally, the first gear ring and a drive gear ring of a transfer case of the spur gear directly mesh with each other, whereby the second gear stage of the drive unit is then formed by the first gear ring and the meshing drive gear ring.

[0012] The invention is based on the finding that mass can be saved by designing the stability and torque transmission capacity of the spur gear element separately with respect to its possible directions of rotation. The idea behind this is that the motor vehicle is not usually accelerated particularly quickly and / or with increasing speed for a long time when reversing, which is why it is not necessary to design the gear arrangement for transmitting the maximum torque that can be provided by the traction motor when accelerating backwards. In contrast, the gear arrangement is designed for transmitting the maximum torque that can be provided by the traction motor when accelerating forwards, in order to enable a user of the motor vehicle to access the maximum torque safely, in particular repeatedly and / or continuously.For this purpose, the stiffening ribs are inclined relative to the radius of the second gear ring or the spur gear element, as described above. By saving torque transmission potential in relation to a direction of rotation of the gear ring arrangement that is opposite to the preferred direction of rotation, corresponding material components can be omitted, resulting in a particularly mass-efficient design of the gear body without compromising the torque transmission capacity of the spur gear element in the preferred direction of rotation. In the preferred direction of rotation during traction operation, axial forces and associated bending moments are particularly well absorbed due to the gear body geometry according to the invention. Furthermore, the stiffening structure increases the flexural rigidity of the spur gear element and can thus withstand bending moments occurring due to the helical gearing without adversely deforming the spur gear element.Furthermore, the gear body geometry according to the invention contributes to particularly advantageous acoustic properties of the spur gear element and consequently of the gear ring assembly, as the stiffness and natural frequency (frequency of bending of the second gear ring in the axial bending direction of the rotating / orbiting spur gear element) of the gear body are significantly increased due to the stiffening structure. The improved acoustic properties result in particularly quiet operation of the gear ring assembly.

[0013] A first variant of the gear ring arrangement is characterized in that, with respect to a plan view along the transmission shaft onto the first gear ring and onto the gear body stiffening side, the preferred direction of rotation is anticlockwise, with the second gear ring having right-hand helical teeth. In a second variant, which is an alternative to the first variant, it is provided that, with respect to the plan view along the transmission shaft onto the first gear ring and onto the gear body stiffening side, the preferred direction of rotation is clockwise, with the second gear ring having left-hand helical teeth. These possible variants create particularly advantageous freedom when designing / constructing spur gears or drive trains.

[0014] According to a further possible embodiment, the first and second gear rings can both be toothed so that they rise in the same direction. For the first variant of the gear ring arrangement, the first and second gear rings both have right-hand toothing, whereas for the second variant of the gear ring arrangement, the first and second gear rings both have left-hand toothing. This makes it possible to specifically influence the axial forces that act on the gear ring arrangement during operation. According to a further possible embodiment, the gear shaft and the gear body are connected to one another by means of an interference fit and a weld that secures the interference fit. This means that the gear shaft and the gear body, and consequently the second gear ring, are connected to one another in a particularly secure and stable manner.Other shaft-hub connection types, through which the transmission shaft and the gear body are torsionally connected, are also conceivable, for example, a splined shaft-splined hub connection, a screw flange connection, a threaded connection, etc. (each with or without a securing material connection, such as welding, bonding, etc.). It is also conceivable for the transmission shaft and the second gear ring, including the gear body, to be formed integrally with one another, for example, by machining or non-machining from a common material blank and / or by means of a common primary forming process.

[0015] According to a possible further development, the transmission shaft and the first gear ring are formed integrally with one another. This provides for the first gear ring and the shaft to be particularly securely and non-rotatably fastened to one another, and the gear ring assembly is advantageously manufactured from a very small number of individual parts. An alternative to this is for the transmission shaft and the first gear ring to be initially manufactured separately and then joined together by a force-fitting, form-fitting, and / or material-fitting connection. This makes it possible to use a different material for the first gear ring than for the transmission shaft, which again contributes to the freedom in designing the gear ring assembly.

[0016] In a further possible embodiment, the stiffening ribs are inclined relative to a radial plane of the spur gear element. The radial plane is an imaginary plane traversed perpendicularly by the longitudinal center axis of the gear rims or the gear shaft, with the radius of the second gear rim or the spur gear element running entirely within this plane. According to this embodiment, the radially outer stiffening rib ends are located further forward in the axial direction of the spur gear element (virtually closer to the first gear rim) than the radially inner stiffening rib ends. A reverse embodiment, according to which the radially outer stiffening rib ends are arranged further back in the axial direction of the spur gear element (virtually further away from the first gear rim) than the radially inner stiffening rib ends, is also conceivable.In any case, this inclined position of the stiffening ribs results in a particularly advantageous absorption of axial forces and bending moments that occur when the gear ring assembly rotates in the preferred direction of rotation. It can therefore be provided that the stiffening ribs are not located entirely within said radial plane, but instead are inclined relative to it.

[0017] Another possible embodiment provides for the stiffening ribs to be straight, which makes them particularly easy to manufacture. Alternatively, the stiffening ribs can be uneven. In particular, the stiffening ribs can be bent in an S-shape in such a case. In an axial plan view of the gear body stiffening side of the spur gear element, the stiffening ribs can have a kind of S-bend. Other non-straight or uneven shapes are also possible. Such an uneven course of the stiffening ribs has a particularly advantageous effect on the absorption of axial forces and the resulting bending moments.This in turn has a positive influence on the bending stiffness and consequently on the bending natural frequency of the spur gear element, since an advantageously high bending stiffness is accompanied by an acoustically particularly inconspicuous operation of the spur gear equipped with the gear ring arrangement.

[0018] According to a possible further development, the spur gear element has the stiffening structure only on the gear body stiffening side, whereas the gear body side axially opposite the gear body stiffening side is free of a stiffening structure. The gear body side free of the stiffening structure has a flat surface without stiffening ribs. The flat surface is in particular a base or bottom surface of the gear body side free of the stiffening structure. This can be plate-shaped. The geometry, which is only turbine-shaped on one side, allows for particularly efficient optimization in interaction with an oil supply, for example by the stiffening ribs being specifically designed to convey oil. The stiffening ribs can therefore be specifically used to convey or direct the lubrication of the spur gear. The oil is not undesirably deflected on the gear body side free of the stiffening ribs.Furthermore, the arrangement of the stiffening structure on only one side facilitates particularly simple production of the wheel body, in particular by forging.

[0019] The smooth geometry on the gear body side without a stiffening structure also enables particularly easy reworking, especially balancing the spur gear element. Furthermore, the flat design of the gear body side without a stiffening structure allows for particularly easy machining of the spur gear element, allowing for the removal of material as needed and reducing the imbalance of the spur gear element. Alternatively, the stiffening structure can have stiffening ribs on both the wheel body stiffening side and the opposite wheel body side.

[0020] In another possible embodiment, the spur gear element or its gear body has axial openings, each located outside the stiffening ribs and made, for example, as bores. One, some, or all of the openings can be designed as through-holes that completely penetrate the gear body of the spur gear axially. The openings / through-holes can, for example, be manufactured as balancing elements for balancing the gear body. Furthermore, the openings can also serve as mass-reduction elements of the spur gear element or the gear ring arrangement. In the form of through-holes, the openings function as so-called wash holes during the manufacture of the gear ring arrangement, through which chips or other material residues that occur can be flushed away.

[0021] Further features of the invention may emerge from the claims, the figures, and the description of the figures. The features and combinations of features mentioned above in the description, as well as the features and combinations of features shown below in the description of the figures and / or in the figures alone, can be used not only in the respective combinations specified, but also in other combinations or on their own, without departing from the scope of the invention.

[0022] The drawing shows

[0023] Fig. 1 is a perspective view of a first variant of a gear ring arrangement with a view of a wheel body stiffening side of a wheel body of a spur gear element,

[0024] Fig. 2 is a perspective view of the first variant of the gear rim arrangement with a view of a wheel body side of the wheel body axially opposite the wheel body stiffening side,

[0025] Fig. 3 is a schematic plan view of the wheel body stiffening side,

[0026] Fig. 4 is a perspective view of a gear rim arrangement in an alternative, second variant with a view of the wheel body stiffening side of the wheel body, Fig. 5 is a perspective view of the second variant of the gear rim arrangement with

[0027] View of the wheel body side axially opposite the wheel body stiffening side,

[0028] Fig. 6 is a perspective and partial view of a drive unit having the gear ring arrangement.

[0029] In the following, a gear ring assembly 1, a spur gear 2 comprising the gear ring assembly 1, a drive unit 3 comprising the spur gear 2, and a motor vehicle (not shown) comprising the drive unit 3 are explained in a joint description. In the figures, identical and functionally equivalent elements are provided with the same reference numerals.

[0030] The motor vehicle comprising the drive unit 3 (see Fig. 6) is, in the present case, a purely or hybrid electric motor vehicle. Consequently, in addition to the spur gear 2, which contains the gear ring assembly 1, the drive unit, in this example, comprises a traction motor (not shown) designed as an electric machine.

[0031] According to the first variant 1a of the gear ring arrangement 1 shown in Fig. 1 and Fig. 2, this has a gear shaft 4 on which a first helical gear ring 5 is arranged in a rotationally fixed manner, wherein the gear shaft 4 and the first gear ring 5 are formed integrally with one another in this case. Furthermore, the gear ring arrangement 1 has a second helical gear ring 6, which is also rotationally fixedly connected to the gear shaft 4. The gear rings 5, 6 are helically toothed and increase in the same direction. According to the example described here, the gear body 8 and the gear shaft 4 are connected to one another by means of an interference fit. In order to reinforce or secure the interference fit connection, the present example provides for the gear shaft 4 and the gear body 8 to be additionally welded.The second gear ring 6 is an integral component of a spur gear element 7, which has a gear body 8 that is connected in a rotationally fixed manner to the transmission shaft 4. Both gear rings 5, 6, including the gear body 8, are also axially fixedly connected to the transmission shaft 4. It can be seen from Fig. 1 and Fig. 2 that the second gear ring 6 has a larger tip diameter than the first gear ring 5. In Fig. 6, which partially shows the drive unit 3, it can be seen that the second gear ring 6 and an output gear ring 23 of the traction machine mesh directly with one another. With respect to a torque transmission path between the traction machine and an output element of the drive unit, for example, a transfer case 9 of the spur gear transmission 2, the second gear ring 6 and the meshing output gear ring 23 then represent the first gear stage of the drive unit 3.The transfer case 9 is shown here only as an example; a transfer case is not mandatory, for example in the case of wheel- or axle-specific traction machines. Furthermore, in the present example, the first ring gear 5 and a drive ring gear 10 of the transfer case 9 mesh directly with one another, thereby forming the second gear stage of the drive unit 3. The transfer case 9 is used in the motor vehicle, for example, as a longitudinal and / or transverse differential. In any case, the ring gear arrangement 1 is installed in the spur gear 2 or in the drive unit 3 or in the motor vehicle in such a way that when the motor vehicle accelerates forward with increasing speed, the second ring gear 6 is rotated or driven in the preferred direction of rotation 11 with the aid of the traction machine; the second ring gear 6 is rotated in the preferred direction of rotation 11 during traction operation. Starting from this preferred direction of rotation 11 orA stiffening structure 12 of the gear ring arrangement 1 or the spur gear element 7 is formed by this tensile operation.

[0032] The wheel body 8 has a wheel body stiffening side 13, which faces axially toward the first gear ring 5. On the wheel body stiffening side 13, the wheel body 8 has the stiffening structure 12, which comprises two or more—eight in this example—stiffening ribs 14. More or fewer stiffening ribs 14 are, of course, conceivable; the number of stiffening ribs—as well as the strength / thickness of the stiffening ribs 14 and an angle of inclination α of the stiffening ribs 14, explained in more detail below—is determined based on a maximum torque expected during operation, which is to be transmitted by means of the gear ring arrangement 1 during traction operation. In particular, the stiffening ribs 14 are equidistant from one another in the circumferential direction of the spur gear element 7 or the second gear ring 6.

[0033] As can be seen from Fig. 1 and Fig. 2 in conjunction with Fig. 3, the stiffening ribs 14 are inclined such that a radially outer stiffening rib end 15 of the respective stiffening rib 14 precedes a radially inner stiffening rib end 16 of the same stiffening rib 14 when the gear ring arrangement 1 rotates in the preferred direction of rotation 11. In Fig. 3, which shows a schematic plan view of the gear body stiffening side 13, it can be clearly seen that the stiffening ribs 14 are inclined in the preferred direction of rotation 11 with respect to the radius 17 of the spur gear element 7 intersecting the inner stiffening rib end 16. The stiffening ribs 14 together with the radius 17 each enclose the angle of inclination a, which is greater than 0 degrees and less than 90 degrees, for example 30 degrees.It can be seen that the respective outer stiffening rib end 15 is arranged in front of the inner stiffening rib end 16 of the same stiffening rib 14 with respect to the preferred direction of rotation 11. According to the illustration in Fig. 3, the stiffening ribs 14 can be completely straight between their stiffening rib ends 15, 16. Alternatively, the stiffening ribs 14 (see, for example, Fig. 1 and Fig. 2) can be uneven, in particular S-shaped. Furthermore, the stiffening ribs 14 can each have one or more straight sections as well as one or more uneven sections.

[0034] The stiffening ribs 14 can be inclined relative to a radial plane of the spur gear element. The radial plane is an imaginary plane traversed perpendicularly by the longitudinal center axis of the gear rings 5, 6 or the gear shaft 4, with the radius 17 of the second gear ring 6 or the spur gear element 7 extending entirely within this radial plane. Thus, the radially outer stiffening rib ends 15 are located further forward in the axial direction of the spur gear element 7 (virtually closer to the first gear ring 5) than the radially inner stiffening rib ends 16, or vice versa.

[0035] If the gear ring arrangement 1 is driven by the output gear ring 23 of the traction machine meshing with the second gear ring 6, the helical gear rings 5, 6 result in an axial force 19 based in the tooth engagement zone 18 of the second gear ring 6, which points away from the first gear ring 5. This results in a bending moment being exerted on the spur gear element 7, which is efficiently absorbed or supported by the stiffening structure 12. The gear ring arrangement 1 is therefore designed and arranged such that when it rotates in the preferred direction of rotation 11, while the second gear ring 6 functions as the drive element of the gear ring arrangement 1 during traction operation, the axial force 19 based in the tooth engagement zone 18 of the second gear ring 6 points away from the first gear ring 5.

[0036] In this example, the spur gear element only or exclusively points to the

[0037] Wheel body stiffening side 13 has the stiffening structure 12, i.e., the stiffening ribs 14, whereas a wheel body side 20 axially opposite the wheel body stiffening side 13 is free of stiffening ribs 14. This can be seen in Fig. 2. The wheel body side 20 free of the stiffening structure 12 has a flat surface 21 without stiffening ribs 14. In this example, it is further provided that the wheel body side 20 has a plate-shaped configuration. The flat surface 21 forms a base or bottom surface of the plate-shaped wheel body side 20, for example, similar to the shape of an unloaded disc spring. It can be further seen in Fig. 1 and Fig. 2 that during operation the axial force 19, starting from the tooth engagement zone 18, points from the wheel body stiffening side 13 and towards the wheel body side 20 which is free of stiffening structure.

[0038] Furthermore, the spur gear element 7 or its gear body 8 according to the present example has axial openings 22, which are each arranged outside the stiffening ribs 14 or between two adjacent stiffening ribs 14. The openings 22 are produced, for example, as bores, whereby some or all of the openings 22 can be designed as through-openings. The openings or through-openings 22 function, for example, as balancing elements for balancing the gear body 8 and / or as mass reduction elements of the spur gear element 7 or the gear ring arrangement 1. In the form of through-openings, the openings 22 function as wash holes during the manufacture of the gear ring arrangement 1.

[0039] In the first variant 1a of the gear ring arrangement 1 described up to this point and shown in Fig. 1 and Fig. 2, the preferred direction of rotation 11 is counterclockwise or left-hand rotation with respect to a plan view along the gear shaft 4 of the first gear ring 5 and the gear body stiffening side 13. It can also be seen that according to the first variant 1a, the second gear ring 6 has right-hand helical teeth. In contrast, in a second variant 1b of the gear ring arrangement 1 which differs from the first variant 1a, the preferred direction of rotation 11 is clockwise or right-hand rotation with respect to the plan view along the gear shaft 4 of the first gear ring 5 and the gear body stiffening side 13. The second variant 1b of the gear ring arrangement 1 is shown in Fig. 4 and Fig.5 and, in addition to the opposite preferred direction of rotation 11, differs from the first variant 1a in that the second gear ring 6 has left-hand helical teeth. In addition, a comparison of Fig. 1 and Fig. 4 shows that the stiffening ribs 14 of the second variant 1b are thicker than the stiffening ribs 14 of the first variant 1a. This is because the second variant 1b of the gear ring arrangement 1 is designed to transmit a higher maximum torque than the first variant 1a of the gear ring arrangement 1. Otherwise, all of the statements made about the first variant 1a also apply to the second variant 1b. Fig. 6 shows a partial perspective view of the drive unit 3, in which the gear ring arrangement 1 is arranged in its intended installation position.The second gear ring 6 and the output gear ring 23 of the traction motor mesh with each other, while the drive gear ring 10 of the transfer case 9 and the first gear ring 5 mesh with each other. It can also be seen that a parking lock gear of a parking lock device 24 of the drive unit 3 or the motor vehicle and the output gear ring 23 are non-rotatably mounted on a common shaft.

[0040] The gear ring arrangement 1, the spur gear 2, the drive unit 3 and the motor vehicle each show a possibility of how conventional spur gears can be improved in terms of acoustics, strength and weight.

[0041] List of reference symbols

[0042] 1 sprocket arrangement

[0043] 1 a first variant

[0044] 1 b second variant

[0045] 2 spur gears

[0046] 3 Drive unit

[0047] 4 Gear shaft

[0048] 5 first sprocket

[0049] 6 second sprocket

[0050] 7 Spur gear element

[0051] 8 wheel centers

[0052] 9 transfer cases

[0053] 10 drive sprocket

[0054] 11 Preferred direction of rotation

[0055] 12 Stiffening structure

[0056] 13 Wheel center stiffening side

[0057] 14 stiffening ribs

[0058] 15 outer stiffening rib end

[0059] 16 inner stiffening rib end

[0060] 17 radius

[0061] 18 Tooth engagement zone

[0062] 19 Axial force

[0063] 20 Wheel body side

[0064] 21 area

[0065] 22 Opening

[0066] 23 Output gear ring

[0067] 24 Parking lock device a inclination angle

Claims

Patent claims 1. Gear ring arrangement (1) for a spur gear (2), wherein the gear ring arrangement (1) has: - a gear shaft (4), - a first helical gear ring (5) which is connected in a rotationally fixed manner to the gear shaft (4), - a spur gear element (7) with a gear body (8) connected to the gear shaft (4) in a rotationally fixed manner, on which a second helical gear ring (6) with a larger tip diameter than the first gear ring (5) is formed, wherein the gear body (8) comprises, on its gear body stiffening side (13) axially facing the first gear ring (5), a stiffening structure (12) with stiffening ribs (13) which are inclined with respect to a radius (17) of the second gear ring (6) such that a radially outer stiffening rib end (15) of the respective stiffening rib (13) leads a radially inner stiffening rib end (16) of the same stiffening rib (13) when the gear ring arrangement (1) rotates in the preferred direction of rotation (11), wherein the gear ring arrangement (1) is further designed such that when it rotates in the preferred direction of rotation (11), while the second Gear ring (6) is a drive element of the gear ring arrangement (1),an axial force (19) based in a tooth engagement zone (18) of the second gear ring (6) points away from the first gear ring (5).

2. Gear ring arrangement (1) according to claim 1, characterized in that with respect to a plan view along the gear shaft (4) onto the first gear ring (5) and onto the wheel body stiffening side (13), the preferred direction of rotation (11) is the left-hand direction of rotation, wherein the second gear ring (6) is helically toothed to the right.

3. Gear ring arrangement (1) according to claim 1, characterized in that with respect to a plan view along the gear shaft (4) onto the first gear ring (5) and onto the wheel body stiffening side (13), the preferred direction of rotation (11) is the clockwise direction of rotation, wherein the second gear ring (6) is helically toothed to the left.

4. A gear ring arrangement (1) according to one of the preceding claims, characterized in that the gear rings (5, 6) are helically toothed and rising in the same direction.

5. Gear ring arrangement (1) according to one of the preceding claims, characterized in that the gear shaft (4) and the wheel body (8) are connected to one another by means of an interference fit and a weld securing the interference fit.

6. Gear ring arrangement (1) according to one of the preceding claims, characterized in that the gear shaft (4) and the first gear ring (5) are formed integrally with one another.

7. Gear ring arrangement (1) according to one of the preceding claims, characterized in that the stiffening ribs (13) are inclined relative to a radial plane of the spur gear element (7).

8. A gear ring arrangement (1) according to one of the preceding claims, characterized in that the stiffening ribs (13) are straight.

9. A gear rim arrangement (1) according to one of claims 1 to 7, characterized in that the stiffening ribs (13) are uneven, in particular S-shaped.

10. Gear ring arrangement (1) according to one of the preceding claims, characterized in that a wheel body side (20) of the spur gear element (7) axially opposite the wheel body stiffening side (13) has a flat surface (21) without stiffening ribs (14).

11. Gear ring arrangement (1) according to one of the preceding claims, characterized in that the spur gear element (7) has axial openings (22), in particular through openings, outside the stiffening ribs (13).

12. Spur gear (2) for a drive unit (3) for a motor vehicle, wherein the spur gear (2) has the gear ring arrangement (1) designed according to one of the preceding claims.

13. Drive unit (3) for a motor vehicle, which has a traction machine and the spur gear transmission (2) designed according to claim 12.

14. Drive unit (3) according to claim 13, characterized in that the second gear ring (6) and an output gear ring of the traction machine mesh directly with each other.

15. Motor vehicle with a drive unit (3) designed according to claim 13 or 14, wherein the gear ring arrangement (1) is installed such that when the motor vehicle accelerates forward with increasing speed, the second gear ring (6) is rotated in the preferred direction of rotation (11) with the aid of the traction machine.

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