Planetary gearbox and drive unit, especially for electric vehicles

Abstract

Planetary gear (10), in particular for a motor vehicle, with an input shaft (12) forming a sun gear (14), with a planet carrier (16) which carries a first set of planet gears (18) and a second set of planet gears (20), with a first ring gear (22) which is associated with the first set of planet gears (18), and with a second ring gear (24) which is associated with the second set of planet gears (20), and with a first locking means (26) by means of which the first ring gear (22) can be locked, and with a second locking means (28) by means of which the second ring gear (24) can be locked, wherein the ring gears (22, 24) are hood-shaped and the second ring gear (24) is spatially arranged in the first ring gear (22), and wherein the locking means (26, 28) are located in the region of neck sections (23, 25) of the hood-shaped ring gears (22, 24).

Description

[0001] The present invention relates to a planetary gear unit and a drive unit, in particular for electric vehicles.

[0002] Electric vehicles incorporate many familiar components from vehicles with combustion engines.

[0003] Many requirements for current motor vehicles with combustion engines can easily be transferred to electric vehicles, for example within the framework of legal requirements or specifications.

[0004] For example, motor vehicles with combustion engines and automatic transmissions are required to have a parking lock in the transmission. The parking lock is designed to prevent the vehicle from rolling away, especially when parked on steep inclines. These parking locks consist of a locking wheel and an actuator, either on the transmission input side or the output side.

[0005] However, such a parking brake requires a considerable amount of installation space. Furthermore, it increases the vehicle's weight, which is also undesirable in the design of electric vehicles.

[0006] EP 2 388 497 A1 shows a gearbox for a vehicle which includes a parking mechanism which keeps the vehicle in a stopped state by preventing the rotation of an output shaft.

[0007] The DE 11 2011 104 355 T5 reveals a hydraulic-free multi-stage transmission.

[0008] It is therefore the object of the present invention to further develop a planetary gear of the type mentioned at the outset in an advantageous manner, in particular in such a way that a planetary gear and a drive unit are better adapted for installation in an electric vehicle and, moreover, can be manufactured with less weight and a simpler design and at a lower cost.

[0009] This problem is solved according to the invention by a planetary gear with the features of claim 1. According to this invention, a planetary gear is provided with an input shaft forming a sun gear, with a planet carrier carrying a first set of planet gears and a second set of planet gears, with a first ring gear associated with the first set of planet gears, with a second ring gear associated with the second set of planet gears, with a first locking means by means of which the first ring gear can be locked, and with a second locking means by means of which the second ring gear can be locked, wherein the ring gears are hood-shaped and the second ring gear is spatially arranged in the first ring gear, and wherein the locking means are located in the region of neck sections of the hood-shaped ring gears.

[0010] The planetary gear is specifically designed for use in motor vehicles. Due to its simple design, the planetary gear according to the invention is better suited for installation in electric vehicles and is also more cost-effective to manufacture than previously known planetary gears for electric vehicles. The simpler design of the gear also results in weight savings. Different gear ratios can be easily achieved by fixing the individual ring gears.

[0011] The first and second sets of planetary gears provide a two-speed transmission.

[0012] Because the second ring gear is spatially arranged inside the first ring gear, the two ring gears are arranged in a particularly space-saving manner. The planetary gear thus requires less installation space.

[0013] In particular, a shift position may be provided in which both ring gears are blocked by the locking means. This shift position is the park position, in which the parking lock is active. By blocking the two ring gears, the transmission is advantageously preloaded, and thus the output shaft is also blocked. The vehicle cannot roll away in this position.

[0014] Preferably, an output shaft can be driven via the planetary carrier. Direct drive of the input shaft by the planetary carrier saves weight. Furthermore, less installation space is required for the planetary gearbox.

[0015] The input shaft preferably always meshes with the planet gears of the first set and never with those of the second set.

[0016] Furthermore, it is possible to integrate the first and second locking devices into a single locking mechanism. Integrating multiple functions into one component saves installation space and can also reduce costs.

[0017] In particular, the first and second locking devices can be designed as a common locking device.

[0018] Preferably, the first and second locking devices are designed as toggle switches. A toggle switch allows for simple and reliable actuation of the locking devices. In a first position, the common toggle switch can actuate only the first locking device and leave the second locking device in the open position. In a second position, only the second locking device is actuated, and the first locking device remains in the open position. In a third position, both locking devices are actuated, so that both ring gears are locked.

[0019] A rolling bearing can be arranged between the first and second ring gears. In particular, the rolling bearing can be arranged directly between the walls of the ring gears. This allows for a particularly space-saving design.

[0020] Furthermore, the planetary gear can have a first gear in which the first locking device locks the first ring gear and the second locking device does not lock the second ring gear.

[0021] Furthermore, it may be provided that the planetary gear has a second gear in which the first locking device does not lock the first ring gear and the second locking device locks the second ring gear.

[0022] The planetary gears of the two sets are coupled to each other in pairs for drive purposes.

[0023] Furthermore, the present invention relates to a drive unit. A drive unit according to the invention comprises at least one electric motor and at least one planetary gear unit according to the invention, wherein the electric motor is connected to the planetary gear unit and the drive torque provided by the electric motor is applied to the input shaft.

[0024] The drive unit can be designed such that the planetary gear has a parking lock mode in which the first locking means locks the first ring gear and the second locking means locks the second ring gear.

[0025] In particular, it may be designed that the entire drive unit does not have a separate parking lock. The function of the parking lock is performed exclusively by the two locking devices. When the two ring gears are blocked by the locking devices, the drive unit is in parking lock mode.

[0026] Further features and advantages of the invention will become apparent from the following description and from the following drawings, to which reference is made. The drawings show: - Fig. 1 a schematic view of an embodiment of a schematic planetary gear and an embodiment of a drive unit according to the invention; - Fig. 2 a sectional view through an embodiment of a schematic planetary gear and an embodiment of a drive unit according to the invention; and - Fig. 3 a diagram showing the switching positions of the planetary gear according to Fig. 1 and Fig. 2.

[0027] Fig. Figure 1 shows a schematic view of an embodiment of a drive unit 5 according to the invention with an embodiment of a planetary gear 10 according to the invention of an electrically driven vehicle.

[0028] The drive unit 5 has an electric motor 6 with a stator 7 and a rotor 8.

[0029] The rotor 8 is connected to the input shaft 12 of the planetary gear 10. The input shaft 12 forms a sun gear 14.

[0030] Furthermore, a planet carrier 16 is provided in the planetary gear set 10. The planet carrier 16 carries a first set of planet gears 18 and a second set of planet gears 20, which are coupled to each other and rotate simultaneously. The planet gears 18 have a larger pitch circle than the first planet gears 20.

[0031] Furthermore, a first ring gear 22 and a second ring gear 24 are provided, the second ring gear 24 having a smaller pitch circle than the first ring gear.

[0032] The first ring gear 22 is assigned to and meshes with the first set of planet gears 18. The second set of planet gears 20 meshes with and is thus assigned to the second ring gear 24.

[0033] Furthermore, two locking devices 26 and 28 are provided. The locking devices 26 and 28 can, for example, act like a brake on the ring gears 22 and 24 respectively, in order to selectively block or allow the ring gears 22 and 24 to rotate.

[0034] The planet carrier 16 is connected to an output shaft; the input shaft 12 and the output shaft 30 are coaxial. The drive unit 5 also includes a differential 32, which is coupled to the wheels. The operation of the drive unit corresponds to that of the embodiment shown in [reference to embodiment]. Fig. 2 and will be explained in more detail later.

[0035] The planetary gear set allows for two gear ratios. In first gear, a gear ratio of approximately 5-7 is achieved, for example, via the first set of planetary gears 18 and the stationary ring gear 26. The gear ratio in the embodiment shown here is i1 = 6.24.

[0036] The second set of planet gears 20, if only the ring gear 24 is blocked, can achieve a gear ratio twice as high as that of the first set of planet gears 18, for example, a ratio in the range of approximately 10-12. The gear ratio in the embodiment shown here is i2 = 10.41.

[0037] As from Fig. As can be seen in Figure 2, the drive unit 5 has a compact design and a housing 34 in which the electric motor 6, the planetary gear 10, and the differential 32 are arranged. Functionally identical, already in connection with Fig. 1. The parts described above are provided with the same reference numerals.

[0038] The two ring gears 22 and 24 are arranged one inside the other and are essentially hood-shaped. The second ring gear 24 is spatially arranged within the first ring gear 22.

[0039] Between the first ring gear 22 and the second ring gear 24 there is a rolling bearing 36, namely in the area of ​​the two neck sections 23 and 25 of the two ring gears 22, 24.

[0040] The locking means 26 and 28 are also located in the area of ​​the two neck sections 23 and 25, which are designed here as actuating sections of a common toggle switch 29.

[0041] The toggle switch 29 is connected to a synchronous element 38 (not shown in detail) and the hand switch 40.

[0042] The function of the drive unit 5 with the planetary gear 10 is described below:

[0043] The electric motor 6 drives the input shaft 12. The input shaft 12, in turn, drives the first set of planetary gears 18 via its sun gear 14.

[0044] The first locking device 26 can lock the first ring gear 22, and the second locking device 28 can lock the second ring gear 24.

[0045] Fig. Figure 3 shows a diagram with the switching positions of the planetary gear 10 according to Fig. 1 and Fig. 2.

[0046] The letters A and B further specify the positions of the locking devices 26 and 28. The letters A and B are also correspondingly in Fig. 1 is marked.

[0047] Depending on the activation of the locking devices 26 and 28, either the first gear, the second gear or the parking lock is engaged.

[0048] The planetary gear 10 has a first gear in which the first locking device 26 blocks the first ring gear 22 and the second locking device 28 does not lock the second ring gear 24. This first gear corresponds to position A in the table according to Fig. 3.

[0049] For this purpose, the toggle switch 29 is actuated accordingly and its locking device 26 is positioned against the first ring gear 22. This blocks the first ring gear 22.

[0050] In this gear, the planet carrier 16 is driven by the first set of planet gears 18. This torque is then transmitted from the planet carrier 16 to the output shaft 30. The second set of planet gears 20 rotates freely with its unblocked ring gear 28.

[0051] In first gear, the planetary gear 10 has a gear ratio i1=6.24.

[0052] At approximately 10,500 revolutions per minute, a speed of approximately 206 km / h can be reached, and at approximately 11,500 revolutions per minute, a speed of approximately 226 km / h can be reached.

[0053] Furthermore, the planetary gear 10 has a second gear in which the first locking device 26 does not lock the first ring gear 22 and the second locking device 28 locks the second ring gear 24. This second gear corresponds to position B in the table according to Fig. 3.

[0054] In this second gear, the planet carrier 16 is driven by the second set of planet gears 20. The resulting torque is then transmitted from the planet carrier 16 to the output shaft 30.

[0055] In second gear, the planetary gear 10 has a gear ratio i2=10.41.

[0056] At approximately 10,500 revolutions per minute, a speed of approximately 124 km / h can be reached, and at approximately 11,500 revolutions per minute, a speed of approximately 135 km / h can be reached.

[0057] Furthermore, a switching position is provided in which both ring gears 22, 24 are blocked. In this case, the first locking device 26 locks the first ring gear 22 and the second locking device 28 locks the second ring gear 24.

[0058] The planetary gear 10 is then in parking lock mode.

[0059] The in the Fig. 1, Fig. 2 to Fig. The drive unit 5 shown, with the planetary gear 10, thus makes it possible to completely eliminate a conventional, separate parking lock. This saves weight, costs and installation space.

[0060] For this reason, the drive unit 5 or the planetary gear 10 described above is advantageously usable in electric vehicles.

[0061] In particular, the drive unit 5 can be used in the area of ​​the rear axle of an electric vehicle.

Claims

[1] Planetary gear set (10), in particular for a motor vehicle, comprising an input shaft (12) forming a sun gear (14), a planet carrier (16) carrying a first set of planet gears (18) and a second set of planet gears (20), a first ring gear (22) associated with the first set of planet gears (18), a second ring gear (24) associated with the second set of planet gears (20), a first locking means (26) by means of which the first ring gear (22) can be locked, and a second locking means (28) by means of which the second ring gear (24) can be locked, wherein the ring gears (22, 24) are hood-shaped and the second ring gear (24) is spatially arranged in the first ring gear (22), and wherein the locking means (26, 28) are located in the region of neck sections (23, 25) of the hood-shaped ring gears (22, 24). [2] Planetary gear (10) according to claim 1, characterized by, that a switching position is provided in which both ring gears (22, 24) are blocked. [3] Planetary gear (10) according to claim 1 or 2, characterized by , that an output shaft (30) can be driven by means of the planet carrier (16). [4] Planetary gear (10) according to claim 1 or 2, characterized by , that the first and second locking means (26, 28) are integrated in a common locking device, in particular wherein the first and second locking means (26, 28) are designed as a common locking means. [5] Planetary gear (10) according to any of the preceding claims, characterized by , that the first and second locking means (26, 28) are designed as toggle switches (29). [6] Planetary gear (10) according to any one of the preceding claims, characterized by , that a rolling bearing (36) is arranged between the first ring gear (22) and the second ring gear (24). [7] Planetary gear (10) according to any of the preceding claims, characterized by , that the planetary gear (10) has a first gear in which the first locking means (26) locks the first ring gear (22) and the second locking means (28) does not lock the second ring gear (24). [8] Planetary gear (10) according to any of the preceding claims, characterized by , that the planetary gear (10) has a second gear in which the first locking means (26) does not lock the first ring gear (22) and the second locking means (28) locks the second ring gear (24). [9] Planetary gears according to any one of the preceding claims, characterized by , that the planet gears of the first set are coupled to the planet gears of the second set in pairs for drive purposes. [10] Drive unit (5) comprising at least one electric motor (6) and at least one planetary gear (10) according to one of claims 1 to 9, wherein the electric motor (6) is connected to the planetary gear (10) and the drive torque provided by the electric motor (6) is applied to the input shaft (12). [11] Drive unit according to claim 10 for an electrically powered vehicle, characterized by , that the planetary gear (10) has a parking lock mode in which the first locking means (26) locks the first ring gear (22) and the second locking means (28) locks the second ring gear (24).

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