Vehicle axle for a two-track vehicle with a torque vectoring function and a superimposed gearbox with a multi-plate clutch on each side of the vehicle

Abstract

The invention relates to a vehicle axle for a two-track vehicle, comprising an axle differential (15) whose input side is driven by a drive unit (EM), and whose two output sides drive onto flange shafts (17, 18) that each lead to vehicle wheels, wherein each flange shaft (17, 18) is associated with a superimposed transmission (28) for torque vectoring, and wherein each of the superimposed transmissions (28) comprises a multi-plate brake or clutch (7) whose actuator (53) is a clamping mechanism consisting of a pair of discs with a rotationally fixed disc (55) and a disc (57) rotatable coaxially thereto. According to the invention, the rotationally fixed disc (55) of the actuator (53) additionally serves a gear carrier in a dual function, on which at least one gear (41, 45) of the superimposed transmission (28) is rotatably mounted.

Description

[0001] The invention relates to a vehicle axle for a two-track vehicle according to the preamble of claim 1.

[0002] A two-track vehicle has one axle with a drive / brake module whose axle differential distributes torque 50 / 50 to the two wheels of the axle. The input side of the axle differential is connected to a drive unit (for example, an electric motor), while its output sides drive to flanged shafts leading to the vehicle wheels.

[0003] Such a drive / brake module can be equipped with a mechanical torque vectoring system, in which each side of the vehicle has its own superimposed transmission. These superimposed transmissions allow the drive unit to directly drive power to the respective flange shaft, bypassing the axle differential. Each of the two superimposed transmissions incorporates a multi-plate clutch with an electrically controlled actuator. Actuation of the actuator results in torque superposition and thus vehicle dynamics control during acceleration or braking.

[0004] The vehicle axle, consisting of the axle differential and the two superimposed gear units, results in a component-intensive design and packaging problems due to the large installation space required by the components integrated within the axle. To reduce the axial installation space requirement, the actuator of the multi-plate clutch in this type of vehicle axle is designed as a space-saving pair of discs, consisting of a rotationally fixed disc and a coaxially rotatable disc. At least one ball-ramp unit acts between the two discs, in which a ball rolls between mutually inclined ball tracks of the disc pair. Depending on the direction of rotation of the rotatable disc, an axial spread of the disc pair is achieved via an axial spreading path, in order to apply or release contact pressure to the multi-plate clutch.

[0005] US Patent 7 211 019 B2 discloses a generic power transmission device for the drive train of a vehicle, which has a clutch actuator system with a motor / brake unit via which a multi-disc clutch is adaptively controlled, but high performance requirements and a complex design are disadvantages.

[0006] DE 10 2005 061 267 A1 discloses a differential arrangement with two axial adjustment devices actuated by a common electric motor. While this arrangement allows for variable torque distribution, it is complex in design and requires significant control effort. DE 10 2006 025 061 A1 describes a device for the axial adjustment of a lamellar switching element using ball ramps. Despite short actuation times, the achievable axial travel is limited, thus restricting the control capabilities. JP 2014 - 1 750 A discloses a power transmission device with a first gear set, two clutches, and downstream second gear sets. This device enables the distribution of the drive force but, due to the required design of the clutches and gears, results in larger dimensions and reduced versatility.DE 103 42 164 A1 discloses a transmission arrangement with differential gear and two multi-plate clutches which can be used for asymmetrical torque distribution, but entails a complex mechanical design and increased installation space and cost requirements.

[0007] From DE 10 2017 208 433 B3, a transfer case device for a motor vehicle is known, comprising a differential gear with at least one ring gear in a first oil chamber and a friction clutch in a second oil chamber. The first oil chamber has a first oil sump, while the second oil chamber has a second oil sump. A valve is arranged between the first and second oil chambers, such that when the valve is open, oil from the first oil chamber can flow through the valve into the second oil chamber, and when the valve is closed, oil from the first oil chamber cannot flow through the valve into the second oil chamber.

[0008] From DE 102 19 920 A1, a drive with integrated brake for electrically driven vehicles is known, with an individual wheel drive for each of the two drive wheels, wherein each individual wheel drive comprises a coaxially arranged motor, a gearbox and a brake device with an actuator. The actuator is designed as a ball ramp actuator, the stationary disk of which simultaneously forms the A-bearing shield for the motor.

[0009] From DE 10 2017 210 972 A1 a gear arrangement with at least one switching element for realizing transmission stages is known, wherein the switching element is assigned an actuator, and wherein an electromechanical actuator is provided which includes a ball ramp mechanism for generating an positioning movement.

[0010] The object of the invention is to provide a vehicle axle for a two-track vehicle which, compared to the prior art, has a reduced component effort and a reduced installation space requirement.

[0011] The problem is solved by the features of claim 1. Preferred embodiments of the invention are disclosed in the dependent claims.

[0012] The invention relates to a vehicle axle for a two-track vehicle, which has an axle differential. Its input side is driven by a drive unit, while its two output sides drive onto flange shafts, each leading to a wheel on each side of the vehicle. Each flange shaft is associated with a superimposed transmission for torque vectoring. The drive unit can be directly driven by the respective flange shaft via the superimposed transmission, bypassing the axle differential. Each of the two superimposed transmissions incorporates a multi-plate clutch with an electrically controlled actuator. This actuator can apply pressure to the multi-plate clutch for torque superposition and associated vehicle dynamics control (torque redistribution at the vehicle axle). For this purpose, the actuator is equipped with a pressure mechanism consisting of a pair of discs, one stationary and the other moving.formed with a rotationally fixed disc and a coaxially rotatable disc.

[0013] The axle differential is positioned approximately centrally in the vehicle axle when viewed in the transverse direction, with the vehicle axle being designed as a mirror image with respect to a longitudinal center plane. Thus, a superimposed transmission with a multi-plate clutch and an actuator is positioned on each of the two sides of the vehicle. The components of the vehicle axle result in a component-intensive design and packaging problems due to the large installation space required by the components. To reduce the installation space requirement in the axial direction, the actuator of each multi-plate clutch is implemented according to the invention as a pair of discs with a short axial profile.

[0014] To further reduce the installation space required and the number of components, the rotationally fixed disk of the actuator is designed with at least one additional function, thereby reducing the installation space and component requirements of the vehicle axle. According to the invention, the rotationally fixed disk of the actuator also serves a dual function as a gear carrier on which at least one gear of the superimposed transmission is mounted. For a design with a short axial profile, the superimposed transmission can be constructed in the manner of a planetary gear. In this case, the rotationally fixed disk of the actuator can form a planetary gear carrier on which at least one planet gear of the superimposed transmission is rotatably mounted.

[0015] The axis of rotation of the gear is defined by a support bolt, one end of which is connected to the actuator's non-rotating disc. For stable support, the other end of the support bolt can be connected to a bearing plate axially spaced from the non-rotating disc, which is also fixed to the housing (i.e., rotationally fixed or stationary) within the vehicle axle.

[0016] In one specific embodiment, the superimposed gear unit can comprise the following components: a sun gear located on the outside of the vehicle in the transverse direction, which is mounted as a loose gear on the respective flange shaft; a sun gear located on the inside of the vehicle in the transverse direction, which is fixedly mounted on an output-side hub section of a differential housing of the axle differential, through which the flange shaft extends; and the aforementioned support bolt, on which a planet gear meshing with the inner sun gear and a planet gear meshing with the outer sun gear are rotatably mounted. In a space-saving embodiment, the two planet gears can be joined together to form a common double planet gear, for example, by welding. In this configuration, the outer sun gear, designed as a loose gear, can be coupled to the flange shaft via the multi-plate clutch to transmit torque.

[0017] Viewed from the vehicle's transverse direction, the components of the vehicle axle can be positioned as follows: The double planetary gear, rotatably mounted on the support bolt, can be positioned on the inside of the vehicle, and the multi-plate clutch on the outside. In this case, the actuator with the pair of discs can be positioned axially between the double planetary gear and the multi-plate clutch in the vehicle's transverse direction.

[0018] For a compact design, all components of the vehicle axle, namely the axle differential and the two superimposed gear units, are housed within a single axle casing. Similarly, the components of the superimposed gear unit, particularly its sun and planet gears, are positioned within a gearbox housing. In a simplified version, the gearbox housing is constructed directly from the non-rotating disk and the bearing plate. The non-rotating disk and the bearing plate can be axially (i.e., in the transverse direction of the vehicle) clamped together, for example, by a bolted connection, defining an interior space within which the sun and planet gears are compactly positioned.

[0019] The bearing shield can be fixed to the outer vehicle axle housing; in the same way, the rotationally fixed disc of the actuator can also be fixed to the vehicle axle housing (for example by screwing).

[0020] In another, space-saving design variant, the bearing shield can also serve a dual function as a pivot bearing for the hub section of the axle differential. In such a pivot bearing position, the axle differential hub section can be supported in a bearing opening of the bearing shield by means of an intermediate pivot bearing.

[0021] Between the rotationally fixed disc and the coaxially rotatable disc of the actuator, at least one ball-ramp unit is formed. Within the ball-ramp unit, a ball can roll between the mutually inclined ball tracks of the disc pair. Depending on the direction of rotation of the rotatable disc, an axial spread of the disc pair is created or removed via an axial spreading path, in order to apply or relieve contact pressure on the multi-plate clutch.

[0022] The non-rotating disc with enhanced functionality is constructed as follows: The rotating disc has a radially outer ring, which is part of the ball-ramp unit. This outer ring transitions radially inwards into a housing cover to which the support bolt is attached. The housing cover of the non-rotating disc can also be connected to the bearing shield, particularly via a screw connection.

[0023] A preferred gearbox configuration for the respective superimposed transmission is as follows: The outer sun gear can be mounted non-rotatably on a hollow sun gear shaft through which the flange shaft passes. The hollow sun gear shaft can have a radially expanded coupling flange with a multi-plate carrier. Similarly, the flange shaft is also provided with a radially expanded coupling flange and a multi-plate carrier. A multi-plate clutch pack is arranged between the multi-plate carriers of the two coupling flanges. The multi-plate clutch pack can, in turn, be subjected to or relieved of contact pressure by means of the rotatable actuator disc.

[0024] Preferably, the two coupling flanges are supported axially, either directly or indirectly, on the actuator's non-rotating disk, thereby saving installation space in the axial direction. For example, the non-rotating disk can have a rolling element raceway that forms part of an axial support bearing, with which one of the two coupling flanges is directly supported on the non-rotating disk. The other coupling flange can be axially supported directly on the coupling flange closest to the disk via another axial support bearing.

[0025] In another specific embodiment, the multi-plate clutch can be implemented as a wet-running unit, so that the plate pack is located in a coolant circuit of the vehicle axle. With regard to a component-reduced design, separate coolant hoses are not required. Instead, according to the invention, a coolant channel can run both in the bearing shield and in the rotationally fixed disc of the actuator, crossing a mating surface between the bearing shield and the rotationally fixed disc. The coolant channel can open directly into a distribution chamber formed radially within the plate pack of the multi-plate clutch. During driving, the coolant can be displaced radially outward from the radially inner distribution chamber by centrifugal force through the plate pack and from there flow, for example, into a coolant sump.

[0026] The invention is described below using an exemplary embodiment.

[0027] They show: Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5 to Fig. 6 different views illustrating the structure and function of the vehicle axle according to the invention.

[0028] In the Fig. Figure 1 is an electrified vehicle rear axle with a drive / brake module. The vehicle axle includes an electric motor EM and a vehicle axle housing 3, in which superimposed gear units 28, an axle differential 15, and a central multi-disc brake 5 are arranged. The electric motor EM is connected to a high-voltage battery (not shown). Conventional vehicle wheel brakes have been omitted from the vehicle rear axle. Instead of such conventional vehicle wheel brakes, the vehicle axle has the central multi-disc brake 5 and multi-disc clutches 7, in which the superimposed gear units 28 are installed. The central multi-disc brake 5 effects vehicle braking.

[0029] The electric machine EM is connected via its rotor shaft 9 and an intermediate reduction stage 11 to the input side of an axle differential 15. The output sides of the differential are driven by the vehicle's rear wheels. In the Fig. 1 The electric motor EM is installed transversely in the vehicle axle. Accordingly, the rotor shaft 9 and the flange shafts 17, 18 are axially parallel to each other, leading from the output sides of the axle differential 15 to the vehicle's rear wheels. Likewise, the multi-plate clutches 7 and the multi-plate brake 5 installed in the vehicle axle are aligned axially parallel to each other in the transverse direction y of the vehicle.

[0030] Viewed in the transverse direction y of the vehicle, the axle has one of the superimposed gear units 28 on each side of the vehicle, with which the electric motor EM can be directly connected to one of the flange shafts 17, 18 by bypassing the axle differential 15. With the aid of the two superimposed gear units 28, the electric motor EM can therefore drive directly to the vehicle wheels via load paths, bypassing the axle differential 15, in order to perform mechanical torque vectoring.

[0031] The reduction gear 11 is driven by an input-side axle differential gear 21. The axle differential gear 21 is rotationally fixed to a rotating differential housing 25. According to the Fig. 1 drives the axle differential 15 in the transverse direction y of the vehicle in a 50 / 50 distribution on both sides to the two flange shafts 17, 18 leading to the vehicle wheels.

[0032] The vehicle axle is designed as a mirror image with respect to a vehicle center longitudinal plane that passes through the axle differential 15. Each of the two superimposed gear units 28 is designed as a transmission stage, constructed in the manner of a planetary gear unit (but without an outer ring gear). The planetary gear unit has a sun gear 47 located on the outside of the vehicle when viewed in the transverse direction y, which is fixedly mounted on a sun gear hollow shaft 48; and a sun gear 29 located on the inside of the vehicle, which is fixedly mounted on an output-side hub section 30 of a differential housing of the axle differential 15. The sun gear 29 is in tooth mesh with an inner planet gear 41, while the outer sun gear 47 meshes with an outer planet gear 45. The two planet gears 41 and 45 are rotatably mounted on a support bolt 43, as shown in the Fig. 2 emerges.

[0033] In the gearbox structure of the Fig. 1 The outer sun gear hollow shaft 48 has a radially expanded coupling flange 50 with a lamellar carrier. Similarly, the respective flange shaft 17, 18 is designed with a radially expanded coupling flange 51 with a lamellar carrier.

[0034] A lamellar pack of the lamellar coupling 7 is arranged between the lamellar carriers of the two coupling flanges 50, 51.

[0035] Each of the lamellar couplings 7 is assigned an actuator 53, which according to the Fig. 2, Fig. 3 to Fig. 4 is formed from a rotationally fixed disk 55 and a coaxially rotatable disk 57. Between the two disks 55, 57, a total of four ball-ramp units 59 are circumferentially distributed (only in the Fig. 3 indicated) are designed in which a ball 61 rolls between mutually inclined ball tracks 63 of the disc pair. Depending on the direction of rotation of the rotatable disc 57, an axial spreading of the disc pair is built up / reduced via an axial spreading path a ( Fig. 2) to apply or relieve contact pressure on the multi-plate clutch pack 7. The rotatable disc 57 is designed according to the Fig. 4 via a gear section formed on the outer circumference with a spindle drive (not shown) in a driving connection.

[0036] A key aspect of the invention lies in the fact that Fig. 2. Reduced installation space and component size design of the vehicle axle shown. In the Fig. 2 is a section of the gearbox structure from the bottom right. Fig. Figure 1 shows that, viewed in the transverse direction y of the vehicle, the axle differential 15 is positioned centrally. Moving outwards in the transverse direction y, the superimposed transmission 28 follows, then the pair of discs of the actuator 53, and then the multi-plate clutch 7. The pair of discs has a ball cage 56 between the non-rotating disc 55 and the rotatable disc 57, in which the balls 61 are held.

[0037] The two planet gears 41, 45 are in the Fig. 2 welded to form a double planetary gear, which is rotatably mounted on the support bolt 43 via a rotary bearing 65, which defines the axis of rotation of the double planetary gear. A key aspect of the invention is that the non-rotating disk 55 of the disk pair of the actuator 53 also acts as a planetary gear carrier in a dual function. For this purpose, the non-rotating disk 55 has a mounting opening 66 ( Fig. 3 or Fig. 4) in which the support bolt 43 is pressed in with its right bolt end. The left bolt end of the support bolt 43 is pressed into a bearing plate 67. Both the bearing plate 67 and the rotationally fixed disc 55 are mounted to the vehicle axle housing 3 via screw connections (not shown).

[0038] According to the Fig. 2 The non-rotating disk 55 and the bearing plate 67 form a gearbox housing 68, in the interior of which the double planetary gear and the vehicle's inner and outer sun gears 29, 47 are arranged. The bearing plate 67 also serves a dual function as a pivot bearing for the hub section 30 of the axle differential 15. For this purpose, the hub section 30 of the axle differential 15 is mounted in a bearing opening 71 of the bearing plate 67 via an intermediate pivot bearing 69.

[0039] From the Fig. 3 and Fig. Figure 4 details the specific construction of the rotationally fixed disk 55. According to this figure, the rotationally fixed disk 55 has a radially outer ring 73, which is part of the ball-ramp units 59. According to the figure, the radially outer ring 73 is equipped with Fig. Three inclined ball tracks 63 of the ball-ramp units 59 are formed. The radially outer ring 73 transitions radially inwards into a housing cover 75, on which the mounting openings 66 ( Fig. 4) are designed for pressing in the five support bolts 43. The housing cover also has 75 screw holes 76 ( Fig. 3, Fig. 4 or Fig. 6) for screwing onto the bearing plate 67.

[0040] With a view to extending its functionality, the rotationally fixed disc 55 is additionally equipped with a rolling element raceway 77 (only in the Fig. 5 indicated). The rolling element raceway 77 is part of an axial support bearing 79 ( Fig. 2 or Fig. 5), with which the coupling flange 50 of the sun gear hollow shaft 48 is supported on the rotationally fixed disk 55. The coupling flange 51 of the flange shaft 18 is in turn supported directly on the coupling flange 50 by a further axial support bearing 81. The side of the rotationally fixed disk 55 axially opposite the rolling element raceway 77 can come into sliding contact with an end face of the double planetary gear.

[0041] In the Fig.Figure 5 indicates a further functional extension of the rotationally fixed disc 55. Accordingly, a coolant channel 83 runs in the bearing shield 67 and in the rotationally fixed disc 55. This channel crosses a mating surface between the bearing shield 67 and the rotationally fixed disc 55 and opens directly into a distribution chamber 85, which is formed radially within the multi-plate clutch pack 7. The coolant channel 83 is part of a coolant circuit in which coolant is fed into the distribution chamber 85 during operation. From there, the coolant is displaced radially outwards by the multi-plate clutch pack 7 due to centrifugal force. REFERENCE MARK LIST: 3 vehicle axle housings 5-disc brake 7-plate clutch 9 Rotor shaft 11th gear stage 15 axle differential 17, 18 flange shafts 21 Axle differential gear 25 Differential housings 28 Superimposed gear or transmission stage 29 vehicle interior sun gear 30 Hub section of the differential housing 25 41 vehicle interior planetary gear 43 support bolts 45 vehicle outer planetary gear 47 vehicle exterior sun wheel 48 Sun gear hollow shaft 50 coupling flange 51 Coupling flange 53 Actuator 55 non-rotating disc 57 rotating disc 59 Ball Ramp Unit 61 balls 63 Marble Run 67 Storage sign 68 Gearbox housings 56 ball cages 65 swivel bearings 66 Mounting opening 69 Hub section swivel bearing 71 Warehouse opening 73 radial outer ring 75 Housing cover 76 screw holes 77 Rolling element raceway 79 axial support bearing 81 axial support bearing 83 Coolant channel 85 Distribution Room a axial spreading path EM electric machine

Claims

[1] Vehicle axle for a two-track vehicle, comprising an axle differential (15) whose input side is drivenly connected to a drive unit (EM), and whose two output sides drive onto flange shafts (17, 18) each leading to vehicle wheels, wherein each flange shaft (17, 18) is associated with a superimposed transmission (28) for torque vectoring, and wherein each of the superimposed transmissions (28) comprises a multi-plate clutch (7) whose actuator (53) is a clamping mechanism consisting of a pair of discs with a rotationally fixed disc (55) and a disc (57) rotatable coaxially thereto, wherein the clamping mechanism comprises at least one ball-ramp unit (59) with a ball (61) which rolls between mutually inclined ball tracks (63) of the pair of discs,namely, depending on the direction of rotation of the rotatable disc (57), an axial spreading of the disc pair is applied or relieved of pressure by means of an axial spreading path (a) around the multi-plate clutch (7), wherein the non-rotating disc (55) of the actuator (53) additionally forms a gear carrier in a dual function, on which at least one gear (41, 45) of the superimposed transmission (28) is rotatably mounted, wherein the axis of rotation of the gear (41, 45) is defined by a support bolt (43) which is connected at one end to the non-rotating disc (55) of the pressure mechanism, . characterized by , that the non-rotatable disk (55) has a radially outer ring (73) which is part of the ball ramp unit (59), and that the radially outer ring (73) transitions radially inwards into a housing cover (75) to which the support bolt (43) is attached. [2] Vehicle axle according to claim 1, characterized by, that the other bolt end of the support bolt (43) is attached to a bearing plate (67). [3] Vehicle axle according to claim 2, characterized by , that the superimposed gear unit (28) has the following components: - a sun gear (47) on the outside of the vehicle in the transverse direction (y) and which sits as a loose gear on the flange shaft (17, 18), and a sun gear (29) on the inside of the vehicle in the transverse direction (y) and which is fixed against rotation on an output-side hub section (30) of a differential housing (25) of the axle differential (15) through which the flange shaft (17, 18) extends, and - the support bolt (43) on which a planet gear (41) meshing with the vehicle inner sun gear (29) and a planet gear (45) meshing with the vehicle outer sun gear (47) are rotatably mounted, and that the two planet gears (41, 45) are joined together to form a double planet gear, and / or that the vehicle outer sun gear (47), designed as a loose gear, can be coupled to the flange shaft (17, 18) via the multi-plate clutch (7) in a torque-transmitting manner. [4] Vehicle axle according to claim 3, characterized by , that, viewed in the transverse direction (y) of the vehicle, the double planetary wheel rotatably mounted on the support bolt (43) is positioned inside the vehicle and the multi-plate clutch (7) is positioned outside the vehicle, and that the pressure mechanism with the pair of discs is arranged in the transverse direction (y) of the vehicle between the double planetary wheel and the multi-plate clutch (7). [5] Vehicle axle according to one of the preceding claims, characterized by, that the vehicle axle has a vehicle axle housing (3) in which the axle differential (15) and the superimposed gear units (28) are arranged, and / or that the components of the superimposed gear unit (28), namely sun and planet gears (29, 47, 41, 45), are arranged in a gear unit housing (68), and that the gear unit housing (68) is made up of the rotationally fixed disk (55) and the bearing shield (67). [6] Vehicle axle according to claim 5, characterized by , that the bearing plate (67) is fixedly connected to the vehicle axle housing (3), and / or that the bearing plate (67) also serves as a pivot bearing for the hub section (30) of the axle differential (15), in which the hub section (30) is supported in a bearing opening (71) of the bearing plate (67) by means of a pivot bearing (69), and / or that the bearing shield (67) and the rotationally fixed disc (55) of the pressure mechanism are firmly connected to each other via a screw connection. [7] Vehicle axle according to one of claims 2 to 6, characterized by , that the housing cover (75) of the rotationally fixed disc (55) is connected to the bearing shield (67) by screw connection. [8] Vehicle axle according to one of claims 3 to 7, characterized by , that the outer sun gear (47) is fixedly mounted on a sun gear hollow shaft (48) through which the flange shaft (17, 18) is guided, that the sun gear hollow shaft (48) has a radially expanded coupling flange (50) with a plate carrier, that the flange shaft (17, 18) also has a radially expanded coupling flange (51) with a plate carrier, that a plate pack of the multi-plate clutch (7) is arranged between the plate carriers of the two coupling flanges (50, 51), which can be subjected to or relieved of contact pressure by means of the rotatable disc (57) of the pressure mechanism, and / or that the non-rotating disc (55) has a rolling element raceway (77) which is part of an axial support bearing (79) with which one of the coupling flanges (50, 51) is supported on the non-rotating disc (55). [9] Vehicle axle according to any one of claims 2 to 8, characterized by, that a coolant channel (83) runs in the bearing shield (67) and in the rotationally fixed disc (55) of the pressure mechanism, which crosses a joining surface between the bearing shield (67) and the rotationally fixed disc (55), that the coolant channel (83) opens into a distribution chamber (85) which is formed radially within the plate pack of the multi-plate clutch (7), and that coolant is displaced radially outwards from the distribution chamber (85) through the plate pack due to centrifugal force.

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