Differential gear arrangement for a commercial vehicle and commercial vehicle with such a differential gear arrangement

Abstract

The invention relates to a differential gear arrangement (3) for a commercial vehicle (1) which has a planetary gear set (5) having a planetary axis of rotation, wherein - the planetary set (5) has a first element (7), a second element (9) and a third element (11), wherein - the first element (7) is designed and configured as a drive element to be operatively connected to a driven shaft (13) of the commercial vehicle (1), wherein - the second element (9) is designed as a first output element and is operatively connected via a first connection arrangement (15) to a first output shaft (17) extending along a wheel axle (R) of the commercial vehicle (1), wherein - the third element (11) is designed as a second output element and is operatively connected via a second connection arrangement (19) to a second output shaft (21) extending along the wheel axis (R), characterized in that - the planetary set (5) is arranged relative to the first and second output shafts (17, 21) such that the planetary axis of rotation is oriented orthogonally to the wheel axis (R), wherein - the first connecting arrangement (15) has a first connecting shaft (23) extending along the planetary axis of rotation, which is non-rotatably connected to a first bevel gear (25) which meshes with a first ring gear (27) which is non-rotatably connected to the first output shaft (17), and wherein - the second connection arrangement (19) has a second connecting shaft (29) extending along the planetary axis of rotation, which is non-rotatably connected to a second bevel gear (31) which meshes with a second ring gear (33) which is non-rotatably connected to the second output shaft (21).

Description

[0001] The invention relates to a differential gear arrangement for a commercial vehicle and a commercial vehicle with such a differential gear arrangement.

[0002] From DE 10 2021 005 765 A1 a differential gear arrangement for a commercial vehicle is known, which has a planetary gear set having a planetary axis of rotation, wherein the planetary gear set comprises a sun gear designed as a drive element and operatively connected to a driven shaft of the commercial vehicle, a planet carrier designed as a first output element and operatively connected via a first connection arrangement to a first output shaft extending along a wheel axis of the commercial vehicle, and a ring gear designed as a second output element and operatively connected via a second connection arrangement to a second output shaft extending along the wheel axis.This design can be improved in terms of installation space and the complexity of the construction: in particular, an additional intermediate gear is needed to reverse the direction of rotation of one of the output elements so that the wheels of the commercial vehicle driven by the output shafts can rotate in the same direction.

[0003] The invention is therefore based on the objective of creating a differential gear arrangement for a commercial vehicle and a commercial vehicle with such a differential gear arrangement, wherein the aforementioned disadvantages are at least reduced, preferably do not occur.

[0004] The problem is solved by providing the present technical teaching, in particular the teaching of the independent claims and of the preferred embodiments disclosed in the dependent claims and the description.

[0005] The problem is solved in particular by creating a differential gear arrangement for a commercial vehicle which has a planetary gear set having a planetary axis of rotation, wherein - the planetary set has a first element, a second element and a third element, wherein - the first element is designed and configured as a drive element to be operatively connected to a driven shaft of the commercial vehicle, wherein - the second element is designed as a first output element and is operatively connected via a first connection arrangement to a first output shaft extending along a wheel axle of the commercial vehicle, wherein - the third element is designed as a second output element and is operatively connected via a second connection arrangement to a second output shaft extending along the wheel axis, characterized in that - the planetary gear set is arranged relative to the first and second output shafts in such a way that the planetary axis of rotation is oriented orthogonally to the wheel axis, wherein - the first connection arrangement comprises a first connecting shaft extending along the planetary axis of rotation, which is non-rotatably connected to a first bevel gear which meshes with a first ring gear which is non-rotatably connected to the first output shaft, and wherein - the second connection arrangement has a second connecting shaft extending along the planetary axis of rotation, which is non-rotatably connected to a second bevel gear which meshes with a second ring gear which is non-rotatably connected to the second output shaft.

[0006] By orienting the planetary axis of rotation orthogonally to the wheel axis, the differential gear arrangement can be advantageously integrated into the commercial vehicle in a simpler and space-saving manner; in particular, it is possible to arrange a vehicle drive connected to the drive element in front of or behind the wheel axle, whereby the planetary set can be arranged on the other side of the wheel axle, so that the differential gear arrangement in combination with the vehicle drive is narrower and longer.By continuing to have both connecting arrangements comprise a bevel gear and a ring gear, the drive torque can be split from one connecting arrangement to the left – in the intended forward direction of travel – and from the other connecting arrangement to the right, while simultaneously compensating for the difference in the direction of rotation of one output element relative to the other, without requiring an additional intermediate gear. Furthermore, the ring gears can have a smaller diameter than a conventional ring gear of a differential, since each ring gear only has to absorb half the output torque. Finally, the planetary gear set of the differential advantageously combines the function of a transmission – particularly for slowing down – with the function of a conventional differential.Therefore, the differential gear arrangement is particularly suitable for integrating an electric drive into a commercial vehicle.

[0007] In the context of this technical teaching, an axis is generally understood to be an imaginary axis, in particular an axis of rotation, that is, a one-dimensional straight line extending along a specific direction. In contrast, a shaft is generally understood to be an extended, three-dimensional body made of at least one material, which is in particular arranged and configured to rotate about a specific axis, wherein the axis associated with the body is simultaneously a longitudinal and preferably an axis of symmetry of the body.

[0008] In the context of this technical teaching, the term "wheel axle" refers in particular to an axle on which the driven wheels of the commercial vehicle are or will be arranged; thus, when the differential gear assembly is arranged as intended on the commercial vehicle, the wheel axle is in particular a driven axle of the commercial vehicle. Two or more driven wheels, hereinafter referred to as drive wheels, can be arranged on the wheel axle, preferably an even number of wheels symmetrically distributed between the left and right sides in the direction of forward travel.

[0009] In the context of this teaching, the fact that the output shafts extend along the wheel axis means, in particular, that at least one projection of each output shaft onto an imaginary horizontal plane, for example, an imaginary road surface on which the commercial vehicle rests when the differential gear assembly is arranged as intended, extends in the direction of the wheel axis, and is oriented, in particular, parallel to the wheel axis. Furthermore, the output shafts can form a finite angle with the wheel axis or with the imaginary horizontal plane; however, it is also possible that the output shafts are oriented entirely parallel to the wheel axis in three-dimensional space or coincide with the wheel axis.It is important that the output shafts extend in the direction of the wheel axle to at least one drive wheel, that is to say in particular to exactly one drive wheel or a drive wheel group consisting of at least two driven wheels.

[0010] The output shafts are preferably arranged offset from each other along the wheel axis.

[0011] In particular, the first output shaft extends along a first direction towards a first drive wheel or a first drive wheel group, and the second output shaft extends along a second direction opposite to the first direction towards a second drive wheel or a second drive wheel group.

[0012] The first output shaft extends, for example, to the left – in the forward direction of travel – towards a left-hand driven wheel or a left-hand driven wheel group; the second output shaft then extends accordingly to the right towards a right-hand driven wheel or a right-hand driven wheel group. Naturally, the reverse arrangement of the output shafts is possible.

[0013] In the context of this technical teaching, the fact that the planetary axis of rotation is oriented orthogonally to the wheel axis means, in particular, that at least one projection of the planetary axis of rotation onto the imaginary horizontal plane, for example, the imaginary road surface, is perpendicular to a projection of the wheel axis into the horizontal plane. Furthermore, the planetary axis of rotation can form a finite angle with the wheel axis or with the imaginary horizontal plane. It is also possible that the planetary axis of rotation is exactly perpendicular to the wheel axis in three-dimensional space.

[0014] In one embodiment, the driven shaft is a drive shaft of the commercial vehicle.

[0015] In one embodiment, when the differential gear assembly is arranged as intended on the commercial vehicle, the planetary axis of rotation extends in the direction of a longitudinal axis of the commercial vehicle, in particular in the direction of travel, while the wheel axis is oriented transversely to the longitudinal axis, in particular perpendicular to the longitudinal axis - and to the direction of travel.

[0016] In one embodiment, the first connecting shaft and the second connecting shaft extend parallel to each other, particularly along the longitudinal axis. They are preferably arranged one inside the other, with one of the two connecting shafts being designed as a hollow shaft in which the other connecting shaft extends. In another embodiment, the second connecting shaft is designed as a hollow shaft in which the first connecting shaft extends. Alternatively or additionally, the first connecting shaft is designed as a hollow shaft in which the drive shaft extends.

[0017] In particular, the first bevel gear and the first ring gear are perpendicular to each other. Alternatively or additionally, the second bevel gear and the second ring gear are perpendicular to each other. The first bevel gear and the second bevel gear are preferably rotatable about their longitudinal axis. Alternatively or additionally, the first ring gear and the second ring gear are rotatable about their axis.

[0018] In one embodiment, the first bevel gear is arranged on a first side of the first connecting shaft – and preferably also on the second connecting shaft – and the second bevel gear is arranged along the gear axis, or in other words, perpendicular to the planet's axis of rotation, on a second side of the first connecting shaft – and preferably also on the second connecting shaft – opposite the first side. In particular, it is possible for the first bevel gear to be arranged on the left side (in the forward direction of travel) and the second bevel gear on the opposite right side.

[0019] In one embodiment, the two bevel gears mesh with their corresponding ring gears on the same side along the longitudinal axis, i.e., in particular in the direction of travel, preferably both on a rear side or both on a front side. In this way, in particular, the difference in the direction of rotation of the two output elements of the planetary gear set can be compensated for without an intermediate gear.

[0020] In one embodiment, the first and second bevel gears have the same tooth configuration—in particular, external or internal teeth. This represents a particularly simple design. In another embodiment, the first and second bevel gears have different tooth configurations—one with internal teeth and the other with external teeth. Advantageously, radial forces introduced into the output shaft bearings in this way cancel each other out. In one embodiment, the first bevel gear has external teeth, while the second bevel gear has internal teeth. Alternatively, the first bevel gear has internal teeth, while the second bevel gear has external teeth.

[0021] According to a further development of the invention, the first element is a sun gear, the second element is a planet carrier, and the third element is a ring gear of the planetary gear set. In particular, this advantageously provides a reduction gear, or in other words, a gear reduction, through the planetary gear set.

[0022] According to a further development of the invention, the first bevel gear and the first ring gear, and the second bevel gear and the second ring gear, are designed and matched to the planetary gear set such that when a torque is introduced into the first element of the planetary gear set, any torque difference between the second and third elements is compensated for, ensuring that the same torque is applied to both the first and second output shafts. Due to the design, the torques at the first and second output elements differ, and this torque difference can advantageously be compensated for by the design of the ring and bevel gears, so that the same torque can be introduced into both output shafts—and thus ultimately into the drive wheels on both sides of the vehicle.

[0023] Preferably, the gear ratio with the planetary gear set and the bevel gear stages is selected such that in a main driving range of a vehicle having the differential gear arrangement, the gear ratio i = 1, thus minimizing the losses of an upstream gearbox (pre-transmission) in direct drive. In particular, the gear ratio in the pre-transmission should be equal to 1 as the main driving gear, and the gear ratio of the planetary gear set and the bevel gear stages should be suitably adapted to this.

[0024] According to a further development of the invention, the first bevel gear and the first ring gear are designed such that a first gear ratio i1 is obtained from the first connecting shaft to the first output shaft. Additionally, the second bevel gear and the second ring gear are designed and matched to the planetary gear set and the first gear ratio i1 such that a second gear ratio i2, different from the first gear ratio i1, is obtained from the second connecting shaft to the second output shaft, thus compensating for any torque difference between the second and third elements of the planetary gear set at the output shafts.

[0025] In one embodiment, the first gear ratio i1 = 1 is provided. Additionally, the second gear ratio i2 – particularly in terms of its magnitude – is equal to a torque ratio – particularly a steady-state ratio – between the second element and the third element. This advantageously compensates for the torque difference between the second and third elements at the output shafts.

[0026] In particular, the second translation i2 is equal to a quotient of the sum of the number of teeth of the first and third elements divided by the number of teeth of the third element.

[0027] In general, the stationary torque M3 on the third element - in particular the ring gear - is given by: M3=M1z3z1, where M1 is the torque on the first element – ​​in particular the sun gear –, Z3 is the number of teeth on the third element, and Z1 is the number of teeth on the first element. The steady-state torque M2 on the second element – ​​in particular the planet carrier – is given by: M2=−M3z3+z1z3=−M1z3+z1z1, where M2 is the torque at the second element – ​​in particular the planet carrier. Thus, the magnitude of the torque ratio between the second element and the third element – ​​and therefore the second gear ratio i2 – is given by i2=|M2M3|=z3+z1z3, thus by the quotient of the sum of the number of teeth Z1 of the first element and the number of teeth Z3 of the third element divided by the number of teeth Z3 of the third element.

[0028] According to a further development of the invention, the first output shaft is connected to a first wheel shaft via a first switching mechanism in a first switching position of the first switching mechanism and disconnected from the first wheel shaft in a second switching position of the first switching mechanism. Additionally, the second output shaft is connected to a second wheel shaft via a second switching mechanism in a first switching position of the second switching mechanism and disconnected from the second wheel shaft in a second switching position of the second switching mechanism. Advantageously, the output shafts can be connected to or disconnected from their respective wheel shafts – individually or together – in a torque-transmitting manner, thus enabling, in particular, a simple and energy-saving coasting mode for the commercial vehicle.

[0029] In the context of this technical teaching, a wheel shaft is understood to be a shaft that is rotationally fixed to at least one drive wheel of the commercial vehicle, and through which, in other words, a torque can be directly introduced into the respective drive wheel or drive wheel group. In an embodiment in which the differential gear arrangement does not have the first gear unit, the first output shaft can be identical to the first wheel shaft; alternatively or additionally, in an embodiment in which the differential gear arrangement does not have the second gear unit, the second output shaft can be identical to the second wheel shaft.

[0030] The problem is also solved by creating a commercial vehicle that has a differential gear arrangement according to the invention or a differential gear arrangement according to one or more of the embodiments described above. In connection with the commercial vehicle, the advantages that have already been explained in connection with the differential gear arrangement are particularly evident.

[0031] According to a further development of the invention, the commercial vehicle has a drive system that is connected to the first element of the planetary gear set of the differential gear assembly via a drive shaft, transmitting torque. The drive shaft extends along a longitudinal direction of the commercial vehicle and is oriented orthogonally to the wheel axle. Advantageously, this allows for a long but narrow design of the drive system in combination with the differential gear assembly, which is particularly beneficial from an installation space perspective.

[0032] In the context of this technical teaching, the fact that the drive shaft is oriented orthogonally to the wheel axle means, in particular, that at least one projection of the drive shaft onto the imaginary horizontal plane—especially the road surface—is oriented orthogonally to a projection of the wheel axle onto this horizontal plane. Furthermore, the drive shaft and the wheel axle can form a finite angle with each other, or they can be exactly perpendicular to each other in three-dimensional space.

[0033] Preferably the drive shaft extends in the direction of the planetary axis of rotation, or - put another way - the planetary axis of rotation is aligned along the drive shaft.

[0034] In one embodiment, the vehicle drive is arranged in front of the wheel axle (in the forward direction of travel). In another embodiment, the vehicle drive is arranged behind the wheel axle (in the forward direction of travel). Preferably, the planetary gear set is arranged on the side of the wheel axle opposite the vehicle drive.

[0035] According to a further development of the invention, the vehicle drive is designed as an electric drive. In this configuration, the aforementioned advantages are realized in a particularly effective way, especially the combination of a reduction gear – the planetary gear set can have a low-speed reduction ratio of up to 10 or more – with the function of a conventional differential gear within the planetary gear set.

[0036] According to a further development of the invention, the drive shaft is connected to the first element of the planetary gear set via a transmission for torque transmission. Advantageously, a transmission can be integrated into the drive train of the commercial vehicle in this way. The transmission can also be designed as a planetary gear set, for example as a three-speed transmission.

[0037] Alternatively or additionally, it is provided that at least one drive wheel of the commercial vehicle, connected to one of the output shafts selected from the first and second output shafts, is connected to transmit torque via a secondary transmission. Advantageously, this allows the gear ratio to be increased further in a simple manner – particularly for starting on inclines or for reverse. The secondary transmissions can also be designed as planetary gear sets. In particular, a so-called range group can be provided as a secondary transmission. In one embodiment, the secondary transmissions are integrated into the wheel hubs of the drive wheels or drive wheel groups. Such a secondary transmission can, for example, have two gears.

[0038] According to a further development of the invention, the commercial vehicle is designed as a truck or a bus. The advantages already mentioned are realized particularly well in these configurations.

[0039] The invention will be explained in more detail below with reference to the drawing. The drawing shows: Fig. 1 a schematic representation of a first embodiment of a commercial vehicle with a first embodiment of a differential gear arrangement, and Fig. 2 a schematic representation of a second embodiment of a commercial vehicle with a second embodiment of a differential gear arrangement.

[0040] Fig. Figure 1 schematically shows a first embodiment of a commercial vehicle 1 - preferably designed as a truck or as a bus - with a first embodiment of a differential gear arrangement 3.

[0041] The differential gear assembly 3 comprises a planetary gear set 5 with an imaginary planetary axis of rotation extending along an imaginary longitudinal axis L of the commercial vehicle 1. A forward direction of travel of the commercial vehicle 1, also longitudinally oriented, is indicated by an arrow P1. The planetary gear set 5 comprises a first element 7, a second element 9, and a third element 11, wherein the first element 7 is designed as a drive element and is operatively connected to a driven shaft, here a drive shaft 13 of the commercial vehicle. The second element 9 is designed as a first output element and is operatively connected via a first connection arrangement 15 to a first output shaft 17 extending along a wheel axis R of the commercial vehicle.The third element 11 is designed as a second output element and is operatively connected via a second connecting arrangement 19 to a second output shaft 21 extending along the wheel axis R. The planetary gear set 5 is arranged relative to the first and second output shafts 17, 21 such that the planetary axis of rotation is oriented orthogonally to the wheel axis R. Furthermore, the first connecting arrangement 15 has a first connecting shaft 23 extending along the planetary axis of rotation, which is rotationally fixed to a first bevel gear 25 that meshes with a first ring gear 27 that is rotationally fixed to the first output shaft 17. The second connecting arrangement 19 has a second connecting shaft 29 extending along the planetary axis of rotation, which is rotationally fixed to a second bevel gear 31 that meshes with a second ring gear 33 that is rotationally fixed to the second output shaft 21.

[0042] The first bevel gear 25 and the first ring gear 27 are perpendicular to each other, and the second bevel gear 31 and the second ring gear 33 are perpendicular to each other. The first bevel gear 25 and the second bevel gear 31 are rotatable about the longitudinal axis L, and the first ring gear 27 and the second ring gear 33 are rotatable about the gear axis R, in particular, they are rotatably mounted.

[0043] A drive torque is branched from the first connecting arrangement 15 - in the intended forward direction of travel - to the left and from the second connecting arrangement 19 to the right, whereby at the same time the design-related difference in the direction of rotation of the second element 9 relative to the third element 11 is compensated, without the need for an additional intermediate wheel.

[0044] In the embodiment shown here, the second connecting shaft 29 is designed as a hollow shaft in which the first connecting shaft 23 extends. The first connecting shaft 23 is also designed as a hollow shaft in this embodiment, in which the drive shaft 13 extends. However, the first connecting shaft 23 could also be designed as a non-hollow shaft, particularly a solid one, if a vehicle drive 45 and the planetary gear set are located on the same side of the wheel axle R.

[0045] The first ring gear 27 is located on the left side of the drive shaft 13 (in the forward direction of travel), and the second ring gear 33 is located on the opposite right side. The two bevel gears 25 and 31 mesh longitudinally on the same side with their respective ring gears 27 and 33, both on the rear side.

[0046] At the in Fig. In the first embodiment shown in Figure 1, the first bevel gear 27 and the second bevel gear 33 have the same toothing, namely external teeth.

[0047] Preferably, the first element 7 is a sun gear, the second element 9 is a planet carrier, and the third element 13 is a ring gear of the planetary set 5.

[0048] The first bevel gear 25 and the first ring gear 27, and on the other hand the second bevel gear 31 and the second ring gear 33, are preferably designed and matched to the planetary gear set 3 such that when a torque is introduced into the first element 7, the torque difference occurring due to the design between the second element 9 and the third element 11 is compensated for in such a way that the same torque is applied to the first output shaft 17 and the second output shaft 21. In particular, it is provided that the first bevel gear 25 and the first ring gear 27 are designed such that a first gear ratio i1 = 1 is obtained from the first connecting shaft 23 to the first output shaft 17.In addition, the second bevel gear 31 and the second ring gear 33 are designed and matched to the planetary gear set 3 such that a second gear ratio i2 from the second connecting shaft 29 to the second output shaft 21 is equal – in particular in magnitude – to a torque ratio – in particular a steady-state ratio – between the second element 9 and the third element 11. The second gear ratio i2 is preferably equal to a quotient of the sum of the number of teeth of the first element 7 and the third element 11 divided by the number of teeth of the third element 11, as given above in equation (3).

[0049] In particular, to provide a so-called sailing mode, the first output shaft 17 is preferably connected to a first wheel shaft 37 via a first switching mechanism 35 in a first switching position of the first switching mechanism 35 and disconnected from the first wheel shaft 37 in a second switching position of the first switching mechanism 35; additionally, the second output shaft 21 is connected to a second wheel shaft 41 via a second switching mechanism 39 in a first switching position of the second switching mechanism 39 and disconnected from the second wheel shaft 41 in a second switching position of the second switching mechanism 39. The wheel shafts 37, 41 are each rotationally fixed to at least one drive wheel 43 or a drive wheel group of the commercial vehicle 1.

[0050] The commercial vehicle 1 preferably has the particularly electric vehicle drive 45, which is connected to the first element 7 of the planetary set 5 via the drive shaft 13 in a torque-transmitting manner.

[0051] The vehicle drive 45 is preferably arranged behind the wheel axle R in the forward direction of travel. Preferably, the planetary gear set 5 is arranged on the side of the wheel axle R opposite the vehicle drive 45, i.e., in front of the wheel axle R.

[0052] The drive shaft 13 can be connected to the first element 7 via a transmission 47 to transmit torque. Alternatively or additionally, it can be provided that each of the drive wheels 43, which are connected to the output shafts 17, 21 to transmit torque, is assigned a secondary transmission 49.

[0053] Fig. Figure 2 schematically shows a second embodiment of the commercial vehicle 1 with a second embodiment of the differential gear arrangement 3.

[0054] Identical and functionally equivalent elements are provided with the same reference symbols in all figures, so that reference is made to the preceding description in each case.

[0055] In this second embodiment, the first bevel gear 27 and the second bevel gear 33 have different tooth configurations, namely the first bevel gear 27 has internal teeth and the second bevel gear 33 has external teeth. Reference symbol list 1 commercial vehicle 3 Differential gear arrangement 5 Planetary Set 7 first element 9 second element 11 third element 13 Drive shaft 15 first connection arrangement 17 first output shaft 19 second connection arrangement 21 second output shaft 23 first connection wave 25 first bevel gear 27 first bevel gear 29 second connection wave 31 second bevel gear 33 second ring gear 35 first circuit 37 first wheel axle 39 second circuit 41 second wheel axle 43 Drive wheel 45 Vehicle propulsion 47 manual transmissions 49 secondary gearboxes L Longitudinal axis R wheel axle P1 Arrow QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2021 005 765 A1

[0002]

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