Secondary transmission for a utility vehicle, and utility vehicle comprising such a secondary transmission

Abstract

The invention relates to a secondary transmission (3) for a utility vehicle (1) that has a planetary gear set (19), wherein the planetary gear set (19) has a first element (21), a second element (25), and a third element (29), wherein the first element (21) is in the form of an input element and is designed to be operatively connected to a stub shaft (16), wherein the stub shaft (16) is designed to be operatively connected to a driven shaft of the utility vehicle (1), wherein the second element (25) is in the form of an output element and is designed to be operatively connected to a driven wheel (5) of the utility vehicle (1), and wherein the third element (29) can, by means of a shifting device (35), be selectively braked in a first shifting position and be locked in a second shifting position with an element (21, 25, 29) selected from the first element (21) and the second element (25), characterised in that the shifting device (35) has the stub shaft (16) as a displaceable shifting element.

Description

[0001] Rear-mounted gearbox for a commercial vehicle and commercial vehicle with such a rear-mounted gearbox

[0002] The invention relates to a rear-mounted transmission for a commercial vehicle and a commercial vehicle with such a rear-mounted transmission.

[0003] DE 10 2020 005 019 A1 discloses a rear-mounted transmission for a commercial vehicle, wherein the rear-mounted transmission has a planetary gear set in which a ring gear of the planetary gear set, which is neither directly connected to a drive shaft nor directly to an output, can be switched between two switching positions by means of a switching device, wherein it can be braked in a first switching position of the two switching positions and blocked with a sun gear of the planetary gear set in a second switching position of the two switching positions. In this way, two different gear ratios can be provided for the rear-mounted transmission. The rear-mounted transmission, in particular the switching device, can be improved with regard to its structural design, susceptibility to wear, and efficiency in the main driving ranges.If a neutral position or idle is provided for in such a transmission, the disadvantage is particularly so-called churning losses.

[0004] The invention is based on the object of creating a rear-mounted transmission for a commercial vehicle and a commercial vehicle with such a rear-mounted transmission, wherein the disadvantages mentioned are at least partially reduced, preferably do not occur.

[0005] The object is achieved by providing the present technical teaching, in particular the teaching of the independent claims as well as the embodiments disclosed in the dependent claims and the description.

[0006] The object is achieved in particular by providing a rear-mounted transmission, also referred to as a range transmission, for a commercial vehicle, wherein the rear-mounted transmission has a planetary gear set, wherein the planetary gear set has a first element, a second element and a third element, wherein the first element is designed as an input element and is configured to be operatively connected to a stub shaft, wherein the stub shaft is configured to be operatively connected to a driven shaft of the commercial vehicle, wherein the second element is designed as an output element and is configured to be operatively connected to a driven wheel of the commercial vehicle, and wherein the third element can be selectively braked, in particular braked, in a first switching position by means of a switching device and can be locked, in particular locked, with an element selected from the first element and the second element in a second switching position.The rear-mounted transmission is characterized by the fact that the shifting device incorporates the stub shaft as a movable shifting element. This advantageously enables the shifting device to provide a variety of shifting states in a particularly simple and compact design.

[0007] During operation of the rear-mounted transmission, an input speed is assigned to the first element, and an output speed is assigned to the second element. The input speed can, in particular, be equal to a speed of the driven shaft of the commercial vehicle, while the output speed can be equal to a speed of the driven wheel.

[0008] In the context of the present technical teaching, "locking" an element of the planetary gear set means that the locked element is fixed in a rotationally fixed manner, in particular is connected in a rotationally fixed manner to a non-rotating part, for example a steering knuckle or a chassis frame.

[0009] In contrast, in the context of the present technical teaching, "interlocking" two elements of the planetary gear set means that the interlocked elements of the planetary gear set are connected to one another in a rotationally fixed manner relative to one another, but are rotatable as a connected unit. The two interlocked elements can therefore only rotate at the same common speed.

[0010] In particular, in an advantageous embodiment, by braking the third element in the first switching position, a slow gear ratio can be provided between the input speed and the output speed, in particular in order to improve the starting behavior of a commercial vehicle having the rear-mounted transmission, while by blocking the third element with the first element or the second element in the second switching position, a ratio of 1:1 between the input speed and the output speed can be provided, so that the efficiency of the commercial vehicle in regular ferry operation or normal driving operation is high.

[0011] In the context of the present technical teaching, an "element" of a planetary gear set is understood to mean, in particular, a gear or gear set of the planetary gear set. A planetary gear set typically comprises a sun gear, a planet carrier, and a ring gear, wherein the sun gear meshes with the planet carrier, and the planet carrier meshes with both the sun gear and the ring gear; in particular, the planet carrier is arranged radially within the sun gear, and the sun gear is arranged radially within the planet carrier. In particular, the first element, the second element, and the third element are pairwise different elements of the planetary gear set, each selected from a group consisting of the sun gear, the planet carrier, and the ring gear.

[0012] According to a further development of the invention, the shifting device comprises at least one shifting element configured as a claw clutch. Advantageously, due to the design of the at least one shifting element as a claw clutch, the secondary transmission is structurally particularly simple, exhibits low susceptibility to wear, and is improved in terms of its efficiency in the main driving ranges. In particular, a claw clutch is less complex in design compared to a friction shifting element, is less susceptible to wear, and is improved in terms of efficiency due to the significantly lower or nonexistent friction losses.

[0013] In one embodiment, the rear-mounted transmission - except for the design of the stub shaft as a displaceable switching element and optionally the design of the at least one switching element as a claw clutch - is designed and functioning as described in connection with one of the planetary gear sets of the range group in DE 10 2020 005 019 A1.

[0014] In one embodiment, it is provided that the switching device has a first switching element of the at least one switching element, by means of which the third element can be braked in the first switching position, wherein the switching device also has a second switching element of the at least one switching element, by means of which the third element can be blocked in the second switching position with the one element selected from the first element and the second element.

[0015] In one embodiment, the first shifting element is designed as a claw clutch. In another embodiment, the second shifting element is designed as a claw clutch. In yet another embodiment, the first shifting element and the second shifting element are each designed as a claw clutch.

[0016] In one embodiment, the first element and the second element are configured such that, in the first shift position, a gear ratio / with / > 1 (low gear ratio or reduction ratio) results between the input speed of the input element and the output speed of the output element. In this way, the secondary transmission can be used to improve, in particular, the starting behavior of a commercial vehicle equipped with the secondary transmission.

[0017] In one embodiment, the first element and the second element are designed such that the gear ratio / between the input speed and the output speed of the output element in the first switching position is / = 4.

[0018] According to a further development of the invention, the third element is free in a third switching position of the switching device. In particular, the third switching position corresponds to a neutral position of the secondary transmission, in which the secondary transmission is in neutral. The fact that the third element is free in the third switching position means, in particular, that the third element is neither firmly braked nor locked to another element or part.

[0019] According to a further development of the invention, the switching device is designed to couple the stub shaft in the first and second - and optionally in the third - switching position of the switching device into a drive force path formed by the driven shaft, the stub shaft and the first element, or to keep it coupled in the drive force path. The switching device is also designed to decouple the stub shaft from the drive force path in a fourth switching position of the switching device. Thus, in the first switching position and in the second switching position, torque can be transmitted from the driven shaft to the planetary gear set via the stub shaft. The fourth switching position, in contrast, corresponds to a decoupling position in which the torque transmission is mechanically interrupted at at least one point, so that no more torque can be transmitted from the drive shaft to the planetary gear set.Since the planetary gear set is not driven in the decoupled position and therefore does not rotate with the drive shaft or the stub shaft, churning losses can be advantageously reduced, and in particular completely eliminated, which still occur in the third shift position, the neutral position. This makes the efficiency of the rear-mounted transmission particularly high.

[0020] In one embodiment, the switching device is configured to decouple the plug-in shaft from the driven shaft in the fourth switching position. In another embodiment, the switching device is configured to decouple the plug-in shaft from the first element in the fourth switching position, in particular to disengage it from an engagement, in particular a torque-transmitting structure, for example a toothing, of the first element, or to disengage a coupling, for example a claw coupling, existing between the first element and the plug-in shaft.

[0021] In one embodiment, the switching device has a third switching element of the at least one switching element, which is preferably designed as a claw clutch. In one embodiment, the stub shaft can be selectively connected to the first element or decoupled from the first element by means of the third switching element.

[0022] According to a further development of the invention, the switching device comprises an actuator for shifting the stub shaft. Advantageously, the actuator—in particular a controllable actuator—allows for simple control of the switching device and shifting of the stub shaft into the various switching states.

[0023] In one embodiment, the actuator is designed as a pneumatic multi-position cylinder, in particular as a three-position cylinder or four-position cylinder. In another embodiment, the actuator is designed as a hydraulic multi-position cylinder, in particular as a three-position cylinder or four-position cylinder. In yet another embodiment, the actuator is designed as an electric actuator, in particular as an electromotive actuator, in particular as an electric linear actuator or linear motor.

[0024] In one embodiment, it is provided that 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.

[0025] Alternatively, the first element is a sun gear, the second element is a ring gear and the third element is a planet carrier of the planetary set.

[0026] Alternatively, the first element is a ring gear, the second element is a planet carrier and the third element is a sun gear of the planetary gear set.

[0027] With each of the previously described assignments of the first to third elements, a slow gear ratio ( / > 1) between the input speed of the input element and the output speed of the output element can advantageously be achieved in the first switching position.

[0028] According to a further development of the invention, it is provided that 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, wherein the ring gear can be locked, in particular locked, to the planet carrier in the second switching position.

[0029] Alternatively, it is provided that 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, wherein the ring gear can be locked, in particular locked, to the sun gear in the second switching position.

[0030] By means of both blockings of the ring gear - either with the sun gear or with the planet carrier - a ratio of 1:1 between the input speed and the output speed can be achieved (also known as direct drive), so that the efficiency of the drive is high outside of a starting process, i.e. especially during normal driving.

[0031] The object is also achieved by providing a commercial vehicle having a rear-mounted transmission according to the invention or a rear-mounted transmission according to one or more of the previously described embodiments. In connection with the commercial vehicle, the advantages already described above in connection with the rear-mounted transmission are particularly advantageous.

[0032] In one embodiment, the switching device is arranged and configured to brake the third element in the first switching position to a steering knuckle of the commercial vehicle. Alternatively, the third element can also be braked in the first switching position to another part of the commercial vehicle that does not rotate with a wheel, for example, a housing of a wheel suspension, a steering knuckle, a chassis frame or chassis part, a frame part, or the like.

[0033] According to a further development of the invention, the stub shaft can be connected, in particular is connected, via a coupling device to an output shaft of a differential gear of the commercial vehicle, which serves as the driven shaft of the commercial vehicle. This advantageously provides a particularly efficient drive.

[0034] According to a further development of the invention, the second element is connected in a rotationally fixed manner to a wheel hub of a driven wheel of the commercial vehicle. This advantageously makes it possible to provide a particularly efficient output. According to a further development of the invention, the commercial vehicle is designed as a truck or as a bus. The advantages described above are particularly realized in connection with these commercial vehicles. However, in other embodiments, it is also possible for the commercial vehicle to be designed as a different type of commercial vehicle, in particular as a tracked vehicle. A wheel of the commercial vehicle is then understood to be a wheel that drives or guides a track of the commercial vehicle.

[0035] According to a further development of the invention, it is provided that the commercial vehicle is designed as an electrically powered commercial vehicle.

[0036] In one embodiment, the commercial vehicle has a drive system as described in DE 102020005 019 A1, except for the design of the stub shaft as a displaceable switching element and optionally the design of at least one switching element as a claw clutch.

[0037] The invention is explained in more detail below with reference to the drawings, which show:

[0038] Fig. 1 A schematic representation of an embodiment of a commercial vehicle with an embodiment of a rear-mounted transmission;

[0039] Fig. 2 is a schematic representation of a first embodiment of the rear-mounted transmission, and

[0040] Fig. 3 is a schematic representation of a second embodiment of the rear-mounted transmission.

[0041] Figure 1 shows a schematic representation of an embodiment of a commercial vehicle 1 with an embodiment of a rear-mounted transmission 3.

[0042] The commercial vehicle 1 has a plurality of wheels 5, specifically a non-driven front axle 7 and a driven rear axle 9 being shown here, with two wheels 5 being arranged on each axle. However, the commercial vehicle 1 can also have more than two axles. It is also possible for the commercial vehicle 1 to have more than two wheels 5 on at least one axle. Furthermore, it is possible for the commercial vehicle 1 to have more than one driven axle; for example, in one embodiment, both the front axle 7 and the rear axle 9 can be driven. In order to drive the rear axle 9, the commercial vehicle 1 in the exemplary embodiment shown here has a drive 11, which is preferably designed as an electric drive, in particular as described in DE 102020005 019 A1. However, the drive 11 can also be designed as a hybrid drive, in particular as a parallel hybrid or as a serial hybrid drive.The drive 11 can also be designed as a purely internal combustion engine drive. If the drive 11 is designed as an electric drive, it can, in particular, be battery-operated and / or have a fuel cell.

[0043] The drive 11 is connected to the driven wheels 5 of the rear axle 9 via a differential gear 13.

[0044] In particular, each driven wheel 5 of the commercial vehicle 1 is assigned a secondary transmission 3 according to one of the exemplary embodiments described in connection with Figures 2 and 3. The exemplary embodiment of the commercial vehicle 1 illustrated here thus has two secondary transmissions 3, which together form a so-called range group 15.

[0045] The rear-mounted transmissions 3 each have a stub shaft 16, wherein the stub shaft 16 can be, preferably is, connected in a rotationally fixed manner via a coupling device 17 to an output shaft 18 of the differential gear 13 as a driven shaft of the commercial vehicle 1.

[0046] The commercial vehicle 1 is preferably designed as a truck or as a bus.

[0047] Figure 2 shows a schematic representation of a first embodiment of the rear-mounted transmission 3 of the commercial vehicle 1 according to Figure 1.

[0048] Identical and functionally identical elements are provided with the same reference symbols in all figures, so that reference is made to the preceding description in each case.

[0049] The rear-mounted transmission 3 has a planetary gear set 19, which in turn has a first element 21 - here a sun gear 23 -, a second element 25 - here a planet carrier 27 -, and a third element 29 - here a ring gear 31. The first element 21 is designed as a drive element and is configured to be operatively connected to the stub shaft 16. Preferably, the first element 21 is drive-connected to the stub shaft 16. The second element 25 is designed as an output element and is configured to be operatively connected to one of the driven wheels 5 of the commercial vehicle 1. In particular, the second element 25 is rotationally fixedly connected to a wheel hub 33 of one of the driven wheels 5 of the commercial vehicle 1.The third element 29 can be selectively braked, in particular braked, in a first switching position by means of a switching device 35 and can be blocked, in particular blocked, with an element selected from the first element 21 and the second element 25 in a second switching position.

[0050] In Figure 2, the shifting device 35 is shown in a third, neutral shift position, in which the third element 29 is free. This means that the third element 29 is neither locked nor blocked with another element, but rather freely rotatable. In this shift position, the secondary transmission 3 is in neutral, and no torque can be transmitted between the output shaft 18 and the wheel hub 33. However, the elements 21, 25, and 29 rotate in the third shift position, resulting in splash losses.

[0051] Starting from the third switching position shown in Figure 2, the switching device 35 can be moved to the left into the first switching position and to the right into the second switching position.

[0052] By locking the third element 29 in the first switching position, a slow gear ratio is provided between a drive speed of the output shaft 18 and an output speed of the wheel hub 33 and thus also of the driven wheel 5, thereby improving the starting behavior of the commercial vehicle 1. By locking the third element 29 with the first element 21 or the second element 25 in the second switching position, a ratio of 1:1 is provided between the drive speed and the output speed, so that the efficiency of the commercial vehicle 1 is high during regular ferry operation or normal driving.

[0053] The switching device 35 has the stub shaft 16 as a movable switching element. In the embodiment shown here, the stub shaft 16 is movable linearly along its longitudinal extent, i.e., from left to right in the figure and vice versa.

[0054] To move the stub shaft 16, the switching device 35 has an actuator 36. The actuator 36 can be designed as a pneumatic or hydraulic multi-position cylinder or as an electric actuator, in particular a linear actuator.

[0055] In particular, in one embodiment, the actuator 36 can have three different functional positions corresponding to the three switching positions - the first switching position, the second switching position, and the third switching position. In another embodiment, however, the actuator 36 can also have four different functional positions. A fourth functional position of the actuator 36 then corresponds to a fourth switching position of the switching device 35. In this embodiment, the switching device 35 is configured to couple the stub shaft 16 into a drive force path in the first, second, and third switching positions or to keep it coupled into the drive force path, wherein the drive force path is formed from the output shaft 18, the stub shaft 16 - in particular connected to the output shaft 18 via the coupling device 17 - and the first element 21.The switching device 35 is configured to decouple the stub shaft 16 from the drive force path in the fourth switching position.

[0056] In one embodiment, the plug-in shaft 16 can be pulled out of the first element 21, in particular to the left in the figure, which, however, entails a comparatively long switching path.

[0057] In another embodiment, the plug-in shaft 16 can be decoupled from the coupling device 17 to achieve the fourth switching position, or the coupling device 17 can be decoupled from the output shaft 18. The decoupling of the coupling device 17—optionally from the plug-in shaft 16 or from the output shaft 18—can be achieved by the actuator 36 or, in yet another embodiment, by the then actively configured coupling device 17 instead of the actuator 36. In this case, the actuator 36 can have only three functional positions, and the fourth switching position of the switching device 35 can nevertheless be additionally achieved by controlling the coupling device 17.

[0058] The switching device 35 preferably has switching elements 37 designed as claw clutches, namely a first switching element 37.1, by means of which the third element 29 is braked in the first switching position, and a second switching element 37.2, by means of which the third element 29 is blocked with the first element 21 or the second element 25 in the second switching position.

[0059] Due to the switching elements 37 designed as a claw clutch, the secondary transmission 3 is structurally less complex, has a reduced susceptibility to wear, and it is improved with regard to its efficiency in the main driving ranges.

[0060] In the first embodiment shown in Figure 2, the ring gear 31 is locked to the planet carrier 27 in the second switching position. In the first switching position, the ring gear 31 is braked to a steering knuckle 39 of the commercial vehicle 1.

[0061] Figure 3 shows a schematic representation of a second embodiment of the rear-mounted transmission 3.

[0062] This second exemplary embodiment differs from the first exemplary embodiment according to Figure 2 in that the switching device 35 has a third switching element 37.3, by means of which the stub shaft 16 is connected in a rotationally fixed manner to the first element 21, namely the sun gear 23, in the first, second and third switching positions, wherein it can be decoupled from the first element 21 in the fourth switching position, in particular by the stub shaft 16 in Figure 3 being displaced into a position arranged far to the left, in which the ring gear 31 is not blocked with the planet carrier 27 and is also no longer connected to the steering knuckle 39.

[0063] Preferably, the third shifting element 37.3 is also designed as a claw clutch. It has a larger diameter than the sun gear 23 itself, which advantageously requires a smaller engagement depth of its claws to transmit the same torque.

Claims

Patent claims 1. A rear-mounted transmission (3) for a commercial vehicle (1), comprising a planetary gear set (19), wherein the planetary gear set (19) comprises a first element (21), a second element (25), and a third element (29), wherein the first element (21) is designed as a drive element and is configured to be operatively connected to a stub shaft (16), wherein the stub shaft (16) is configured to be operatively connected to a driven shaft of the commercial vehicle (1), wherein the second element (25) is designed as an output element and is configured to be operatively connected to at least one driven wheel (5) of the commercial vehicle (1), and wherein the third element (29) can be selectively braked in a first switching position by means of a switching device (35) and can be locked in a second switching position with an element (21, 25, 29) selected from the first element (21) and the second element (25), characterized in thatthat the switching device (35) has the plug-in shaft (16) as a displaceable switching element., 2. Rear-mounted transmission (3) according to claim 1, characterized in that the switching device (35) has at least one switching element (37) designed as a claw clutch.

3. Rear-mounted transmission (3) according to one of the preceding claims, characterized in that the third element (29) is free in a third switching position of the switching device (35).

4. Rear-mounted transmission (3) according to one of the preceding claims, characterized in that the switching device (35) is designed to switch the stub shaft (16) in the first, second and optionally third switching position of the switching device (35) into a drive force path formed from the driven shaft, the plug-in shaft (16) and the first element (21) or to keep it coupled in the drive force path, and to decouple the plug-in shaft (16) from the drive force path in a fourth switching position of the switching device (35).

5. Rear-mounted transmission (3) according to one of the preceding claims, characterized in that the switching device (35) has an actuator (36) for displacing the stub shaft (16), which is optionally designed as a pneumatic or hydraulic multi-position cylinder or as an electric actuator.

6. Rear-mounted transmission (3) according to one of the preceding claims, characterized in that the first element (21) is a sun gear (23), the second element (25) is a planet carrier (27), and the third element (29) is a ring gear (31), or the first element (21) is a sun gear (23), the second element (25) is a ring gear (31) and the third element (29) is a planet carrier (27), or the first element (21) is a ring gear (31), the second element (25) is a planet carrier (27) and the third element (29) is a sun gear (23) of the planetary gear set (19).

7. Rear-mounted transmission (3) according to one of the preceding claims 1 to 5, wherein the first element (21) is a sun gear (23), the second element (25) is a planet carrier (27) and the third element (29) is a ring gear (31) of the planetary gear set (19), wherein the ring gear (31) can be locked to the planet carrier (27) or to the sun gear (23) in the second switching position.

8. Commercial vehicle (1) with a secondary transmission (3) according to one of claims 1 to 7.

9. Commercial vehicle (1) according to claim 8, wherein the second element (25) is connected in a rotationally fixed manner to a wheel hub (33) of a driven wheel (5) of the commercial vehicle (1).

10. Commercial vehicle (1) according to one of claims 8 or 9, wherein the commercial vehicle (1) is designed as a truck or as a bus.

11. Commercial vehicle (1) according to one of claims 8 to 10, wherein the commercial vehicle (1) is designed as an electrically driven commercial vehicle (1).

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