Differential in a stepped planetary gear set with a decoupling device

Abstract

Gear arrangement (1) with • a reduction gear (2), wherein the reduction gear (2) is designed as a planetary gear with several stepped planets (8) • a bevel gear differential (3), • a decoupling device (4) to interrupt the power flow through the transmission assembly (1), wherein the housing (5) of the bevel gear differential (3) is divided into two parts, wherein the star-shaped differential carrier (7) mounted in the receptacles (6) of the housing (5) is arranged radially within the smaller gear stage of the stepped planets (8) of the reduction gear (2), characterized by the fact that the housing parts (9, 10) of the housing (5) of the bevel gear differential (3) are inserted into each other and are connected to each other by a snap ring.

Description

[0001] The invention relates to an arrangement in a transmission comprising a reduction gear, a bevel gear differential and a decoupling device.

[0002] Various gearboxes in electromechanical axle drive trains are known from the prior art. These include a reduction gearbox to reduce the high speed of the electric motor driving the vehicle and to provide the vehicle with a suitable drive torque for the wheels driven by the electromechanical axle drive train.

[0003] A differential between two driven wheels is also known in the prior art to compensate for a difference in rotational speed between these two wheels, for example when the vehicle is cornering, so that neither of the two wheels experiences slippage during cornering.

[0004] Furthermore, decoupling devices are known in electromechanical axle drive trains that interrupt the power flow from the electric motor to the wheels at a predefined point, for example to enable "coasting" in the vehicle's driving profile.

[0005] The aforementioned "coasting" can increase the range of a vehicle with an electromechanical axle drivetrain. Another factor influencing the range is always the weight of the components installed in the vehicle.

[0006] DE 11 2011 104 355 T5 discloses a multi-stage transmission comprising: a sun gear; a high-speed planetary gear in continuous mesh with the sun gear and a high-speed ring gear, wherein the high-speed planetary gear rotates around the sun gear; a low-speed planetary gear connected to the high-speed planetary gear and in continuous mesh with a low-speed ring gear; a carrier rotatably engaged with the high-speed planetary gear and the low-speed planetary gear, such that either the high-speed planetary gear or the low-speed planetary gear controls the rotation of the carrier; a gear housing surrounding the high-speed ring gear and the low-speed ring gear;and a coupling arranged adjacent to the high-speed ring gear and the low-speed ring gear, wherein the coupling selectively connects the high-speed ring gear or the low-speed ring gear to the gearbox housing.

[0007] DE 10 2022 000 141 A1 discloses an electric drive system for a motor vehicle comprising a housing, an electric machine comprising a rotor non-rotatably connected to a rotor shaft, a planetary gear and an axle gear, wherein the planetary gear comprises exactly one sun gear and exactly one planet carrier, and wherein the rotor shaft is non-rotatably connected to the sun gear.

[0008] DE 10 2021 213 012 B3 shows a differential with a rotating carrier with teeth, at least two planet gears rotatably mounted on bolts or stars in the rotating carrier, with output side gears to side shafts of the drive axle of a vehicle, which mesh with the planet gears.

[0009] DE 699 05 815 T2 discloses a housing assembly for a differential mechanism comprising: a first housing section having a first wall and first recesses arranged on the first wall at angular intervals around a central axis of this housing assembly; and a second housing section permanently connected to the first housing section, having a second wall; second recesses arranged in this second wall; wherein one of these second recesses is aligned at an angle with a corresponding first recess, thereby forming a pair of recesses, and the pairs of recesses are aligned on an axis transverse to this central axis; and a ring gear surrounding and permanently attached to an outer surface of a housing section; wherein the first housing section has a first surface arranged on an outer surface of this first wall;this second housing section has a second surface arranged on an inner surface of the second wall; these first and second surfaces are mutually adjacent, overlapping, and referring to each other, and the first and second housing sections are permanently attached to these first and second surfaces; a shoulder provided on the first housing section engages a complementary shoulder on this second housing section when the housing sections are correctly positioned.

[0010] The purpose of the invention is to create a gear arrangement in an electromechanical axle drive train that requires little installation space.

[0011] The problem is solved according to the invention by a transmission arrangement comprising a reduction gear, wherein the reduction gear is designed as a planetary gear with several stepped planets, a bevel gear differential, and a decoupling device to interrupt the power flow through the transmission arrangement, in that the housing of the bevel gear differential is divided into two parts, wherein the star-shaped differential carrier mounted in the receptacles is arranged radially within the smaller gear stage of the stepped planet of the reduction gear, and the housing parts of the housing of the bevel gear differential are inserted into one another and connected to each other by a snap ring.

[0012] The bevel gear differential according to the invention has the known output gears, each connected to the wheel drive shaft, several differential gears that mesh with the output gears, and a differential gear carrier mounted in the housing of the bevel gear differential. According to the invention, the differential gear carrier is star-shaped, meaning it can support at least two and at most four differential gears. The operating principle of the bevel gear differential is the same as that of known bevel gear differentials from the prior art.

[0013] The reduction gear according to the invention is designed as a planetary gear and is driven by the electric motor of the electromechanical axle drive train. At the output of the reduction gear, it is connected to a decoupling device that can interrupt the power flow within the gear. The reduction gear has several planets designed as stepped planets, each planet having two gear teeth of different diameters. The gear teeth with the larger diameter are preferably arranged axially next to the bevel gear differential to utilize the radial installation space. Thus, according to the invention, the gear teeth with the smaller diameter are positioned axially in the area of ​​the receptacles for the star-shaped differential carrier.

[0014] Thus, the housing of the bevel gear differential is designed in two parts, without bolting the two parts together. This is because bolting would increase the radial installation space and contradict the compact design achieved by the radial stacking of the mounts for the star-shaped differential carrier with the smaller diameter teeth of the stepped planet gear of the reduction gear.

[0015] Preferably, the two housing parts of the bevel gear differential are inserted into one another and welded together and / or axially secured to each other by a retaining ring.

[0016] The housing division advantageously extends through the receptacles for the star-shaped differential gear carrier. If the star-shaped differential gear carrier is formed in one piece, these receptacles take the form of slots which are closed by the second housing part. If the star-shaped differential gear carrier is multi-part and can be assembled, these receptacles can be formed as bores in one housing part. In any case, the housing division should allow the output gears and differential gears to be mounted in the housing. In other words, the housing division according to the invention provides assembly-oriented access for the output gears and differential gears.

[0017] An advantageous embodiment of the invention provides that a decoupling device is arranged in the power flow between the reduction gear and the bevel gear differential. Advantageously, the decoupling device is arranged on the housing of the bevel gear differential. The decoupling device can include an internally or externally toothed sliding sleeve which can engage with two toothed rings to establish a rotationally fixed connection. One toothed ring is connected to the planet carrier of the reduction gear and the other toothed ring is connected to the housing of the bevel gear differential.

[0018] In a further embodiment, the housing's mounting points for the star-shaped differential carrier are designed as bores. The star-shaped differential carrier is designed in multiple parts for mounting in the bevel gear differential housing, so that the star-shaped bolts of the differential carrier, which hold the differential gears, can be inserted radially into the corresponding bores in the housing. The housing is then axially closed with a cover-shaped housing section.

[0019] The housing division preferably runs through the receptacles for the star-shaped differential gear carrier. The cover-shaped housing part thus closes the first housing part and simultaneously forms part of the housing receptacles for the star-shaped differential gear carrier. In an advantageous embodiment, the housing receptacles for the star-shaped differential gear carrier are therefore designed as slots and are closed circumferentially by both housing parts. The star-shaped differential gear carrier can be inserted axially into the slots of the first housing part and therefore does not necessarily need to be multi-part, but can be formed in one piece.

[0020] The star-shaped compensating gear carrier can have at least two bolts projecting from its center of rotation in a star-shaped pattern. These two bolts are arranged diametrically opposite each other. A maximum of four star-shaped projecting bolts is practical to utilize the available installation space gained by the invention.

[0021] Alternatively or additionally, the housing parts of the bevel gear differential are welded together. To secure the cover-shaped housing part as the second housing part to the first, a weld seam is provided between the two parts. The two housing parts can be pre-assembled by fitting them together.

[0022] The snap ring sufficiently secures both housing parts in the axial direction, while the aforementioned weld also blocks the degree of freedom between the two housing parts in the circumferential direction.

[0023] The interlocking mechanism of both connection methods (snap ring, welding) centers the two housing parts relative to each other by interlocking them, with two cylindrical surfaces engaging. Advantageously, one cylindrical surface of the lid-shaped housing part is an outer surface and the cylindrical surface of the first housing part is an inner surface.

[0024] In one embodiment of the invention, one of the housing parts is made of sheet metal and serves as a cover for the housing of the bevel gear differential. The second cover-shaped housing part can thus be designed as a simple sheet metal cover.

[0025] Furthermore, the other part of the housing components has preferably undergone heat treatment to increase its strength. Advantageously, the heat treatment is provided for the first housing component, since this preferably carries the decoupling device (or at least a part thereof) and primarily forms the receptacles for the star-shaped compensating gear carrier, which must transmit forces in the circumferential direction from the first housing component to the compensating gear carrier.

[0026] Further embodiments of the invention are explained in more detail in the illustrations of the figures. They show with Fig. 1 a schematic representation of the gear arrangement, Fig. 2 the housing of the bevel gear differential in a first embodiment and Fig. 3 into the housing after Fig. 2 matching differential wheel carriers.

[0027] The Fig. Figure 1 shows a schematic representation of the transmission arrangement 1. The transmission arrangement 1 includes a reduction gear 2, a bevel gear differential 3, and a decoupling device 4. The decoupling device 4 disconnects the power flow from the reduction gear 2 to the bevel gear differential 3, so that no torque is transmitted. The reduction gear 2 is designed as a planetary gear and has a planet carrier 11 and several stepped planets 8 with a larger gear stage 13 and a smaller gear stage 12. The reduction gear 2 is driven by an electric motor (not shown), which serves as a traction motor for propelling the vehicle. The bevel gear differential 3 has, as is known, a housing 5, several output gears and differential gears (not shown), and a differential gear carrier. The output gears and differential gears are, as is known, meshing bevel gears.

[0028] The housing 5 has several receptacles 6 for the compensating gear carrier 7, which are shown as an exemplary embodiment in the figure. Fig. Figure 3 is shown. According to the invention, these receptacles 6 are now located axially in the area of ​​the smaller gear stage 12 of the reduction gear 2, so that the smaller gear stage 12 can follow the receptacle 6 in a radial direction.

[0029] The decoupling device 4 is operatively connected to the housing 5 on one side and to the reduction gear 2 on the other. In the exemplary embodiment, the decoupling device 4 is arranged adjacent to and connected to the planet carrier 11.

[0030] In this way, a particularly compact design of a reduction gear 2 with stepped planets 8 in combination with a bevel gear differential 3 and a decoupling device 4 is made possible.

[0031] The Fig. Figure 2 shows the housing 5 of the bevel gear differential 3 in a first embodiment. The housing 5 is designed in two parts and has a housing part 9 and a housing part 10 designed as a cover. The housing part 9 has the receptacles 6, which in this embodiment are designed as axial slots and are closed axially by the housing part 10 as a cover. The housing part 10, as a cover, also closes the interior of the bevel gear differential 3 with the bevel gears (not shown) at one axial end. The housing part 10 is inserted into the housing part 9 from one axial end and centered by mutually adapted cylindrical surfaces of the two parts 9 and 10. A retaining ring 14, inserted in a groove of the housing part 9, secures the housing against axial disassembly.

[0032] The Fig. 3 shows the one into the housing 5 after Fig. 2 matching star-shaped differential gear carriers 7. The star-shaped differential gear carrier 7 has three bolts 15 projecting from a center point for receiving the differential gears. The carrier 7 is inserted axially into the housing part 9 if the second housing part 10 is not yet mounted. Mounting the housing part 10 secures the carrier 7 axially in the housing 5.

[0033] According to the illustration of Fig. The larger gear stage 13 of the stepped planet 8 can be axially spaced and radially overlapped within the lid-shaped housing part 10, thus finding space. A very compact design of the gear assembly 1 is therefore possible. Reference symbol list 1 Gear arrangement 2 reduction gearboxes 3 bevel gear differential 4 Decoupling device 5 Housing (bevel gear differential) 6 recording 7 compensating wheel carriers 8-Tiered Planet 9 Housing part 10 Housing part 11 planetary carriers 12 Smaller gear stage (stepped planet) 13 Larger gear stage (stepped planet) 14 retaining ring 15 bolts

Claims

[1] Gear arrangement (1) with • a reduction gear (2), wherein the reduction gear (2) is designed as a planetary gear with several stepped planets (8) • a bevel gear differential (3), • a decoupling device (4) to interrupt the power flow through the transmission assembly (1), wherein the housing (5) of the bevel gear differential (3) is divided into two parts, wherein the star-shaped differential carrier (7) mounted in the receptacles (6) of the housing (5) is arranged radially within the smaller gear stage of the stepped planets (8) of the reduction gear (2), characterized by , that the housing parts (9, 10) of the housing (5) of the bevel gear differential (3) are inserted into each other and are connected to each other by a snap ring. [2] Gear arrangement (1) according to claim 1, characterized by, that a decoupling device (4) is arranged in the power flow between the reduction gear (2) and the bevel gear differential (3). [3] Gear arrangement (1) according to one of the preceding claims, characterized by , that the decoupling device (4) is arranged on the housing (5) of the bevel gear differential (3). [4] Gear arrangement (1) according to one of the preceding claims, characterized by , that the receptacles (6) of the housing (5) for the star-shaped compensating gear carrier (7) are designed as bores. [5] Gear arrangement (1) according to one of the preceding claims, characterized by , that the housing division runs through the receptacles (6) for the star-shaped compensating wheel carrier (7). [6] Gear arrangement (1) according to one of the preceding claims, characterized by , that the receptacles (6) of the housing (5) for the star-shaped compensating wheel carrier (7) are designed as a slot which is closed by both housing parts (9, 10). [7] Gear arrangement (1) according to one of the preceding claims, characterized by , that the housing parts (9, 10) of the housing (5) of the bevel gear differential (3) are welded together. [8] Gear arrangement (1) according to one of the preceding claims, characterized by , that one of the housing parts (9, 10) is made of sheet metal and closes the housing (5) of the bevel gear differential (3) as a cover. [9] Gear arrangement (1) according to claim 8, characterized by , that the other part of the housing parts (9, 10) has undergone heat treatment to increase strength.

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