Powertrain

Abstract

Drive train (2) for a motor vehicle with a clutch-controlled all-wheel drive, comprising a first shaft (28) and a second shaft (30) arranged along a common shaft axis (36), and comprising a controllable shaft coupling (26), wherein - the controllable shaft coupling (26) comprises a sliding sleeve (38) which can be moved between a decoupling position (42) and a coupling position (40) along the shaft axis (36) by means of an adjusting body (44) which can be moved transversely to the shaft axis (36), - the two shafts (28,30) are decoupled when the sliding sleeve (38) is in the decoupling position (42), and - the two shafts (28, 30) are coupled when the sliding sleeve (38) is in the coupling position (40), characterized in that the adjusting body (44) and the sliding sleeve (38) touch at a contact surface (52) via which a transverse force exerted by the adjusting body (44) in the transverse direction (50) is converted into a sliding force acting in the direction of the shaft axis (36).

Description

[0001] The invention relates to a drive train for a motor vehicle with a clutch-controlled all-wheel drive comprising a first shaft and a second shaft which are arranged along a common shaft axis, and comprising a controllable shaft coupling, wherein the controllable shaft coupling comprises a sliding sleeve which is displaceable between a decoupling position and a coupling position along the shaft axis by means of an actuating body which is displaceable transversely to the shaft axis, wherein the two shafts are decoupled when the sliding sleeve is in the decoupling position, and wherein the two shafts are coupled when the sliding sleeve is in the coupling position.

[0002] Some currently available motor vehicles are equipped with a so-called clutch-controlled all-wheel drive, which allows an operator or driver to vary the number of driven axles of the respective motor vehicle. The specification of the number of driven axles and thus the control of the all-wheel drive is typically achieved with the help of at least one controllable shaft coupling, which makes it possible to decouple or couple an axle, or rather the shaft of an axle, from the drive unit of the respective motor vehicle.

[0003] Corresponding controllable shaft couplings can be found, for example, in WO 2012 / 171 709 A1, DE 102 17 576 A1 or WO 2013 / 186 076 A1.

[0004] Based on this, the invention is based on the object of specifying an advantageous drive train for a motor vehicle.

[0005] This object is achieved according to the invention by a drive train having the features of claim 1. Preferred developments are contained in the dependent claims.

[0006] A corresponding drive train is designed for a motor vehicle with a clutch-controlled all-wheel drive and comprises a first shaft and a second shaft arranged along a common shaft axis, as well as a controllable shaft coupling by means of which the two shafts can be coupled or decoupled. The controllable shaft coupling has a sliding sleeve or selector sleeve that can be moved between a decoupling position and a coupling position along the shaft axis by means of an actuating body that can be moved transversely to the shaft axis. The two shafts are decoupled when the sliding sleeve is in the decoupling position and the two shafts are coupled when the sliding sleeve is in the coupling position.

[0007] Of particular importance here is that the movement of the actuator transverse to the shaft axis causes a movement of the sliding sleeve along the shaft axis, as this opens up advantageous design options for the shaft coupling. As a result, for example, a compact design for the controllable shaft coupling and / or a design with a simple structure, for example, consisting of a small number of components, can be realized.

[0008] For a simpler and, consequently, typically less prone to defects, it is further advantageous if the controllable shaft coupling is designed such that the movable actuator can only be moved along one axis or direction and therefore performs a purely linear movement. The movement of the actuator is expediently specified and controlled by an actuator, which is preferably designed as a magnetic actuator and is electrically controlled. The actuator is controlled or activated, for example, manually by an operator or vehicle driver and / or automatically by a control unit.

[0009] The position of the sliding sleeve is in turn specified and controlled with the help of the movable actuating body, whereby the position of the movable actuating body correlates with the position of the sliding sleeve, so that the position of the sliding sleeve is also specified by specifying the position of the actuating body. For this purpose, the actuating body and the sliding sleeve touch at a contact surface, at least when the sliding sleeve is in a position between the decoupling position and the coupling position. The design and orientation of the contact surface effects a force deflection such that a displacement of the actuating body transverse to the shaft axis results in a displacement of the sliding sleeve along the shaft axis, so that a transverse force exerted by the actuating body is converted into a sliding force acting in the direction of the shaft axis.The intended force redirection is thus implemented in a very simple manner, which in turn benefits the reliability of the controllable shaft coupling in the drive train.

[0010] In the simplest case, the contact surface is flat, i.e., has no curvature, and is tilted or obliquely aligned to the direction of movement of the actuator, as well as tilted or obliquely aligned to the shaft axis. It is also expedient if the contact surface is formed by the movable actuator, which has a wedge-shaped design for this purpose. A correspondingly wedge-shaped actuator can be manufactured relatively easily and combined without difficulty with an actuator, particularly a magnetic actuator, thus forming an actuating unit that can be controlled by an electrical control signal.

[0011] Since the sliding sleeve rotates with at least one of the two shafts, at least when coupled, i.e., when in the coupled position, it is further advantageous if the sliding sleeve has a rolling bearing to which the adjusting body engages. This eliminates a simple sliding contact determined by sliding friction between the adjusting body and the sliding sleeve, if they touch. Instead, the continuous load is determined by the contact between the adjusting body and the sliding sleeve through the rolling friction in the rolling bearing, which leads to significantly lower stress on the individual components.

[0012] Since the actuator and the sliding sleeve merely touch when necessary, but are not firmly connected, it is also useful if the sliding sleeve is spring-loaded. In this case, the displacement of the sliding sleeve by the actuator causes the sliding sleeve to move against the spring element. When the actuator is returned, the spring element causes the sliding sleeve to return to its original position due to the acting restoring force. This means that the restoring force of the spring element acts on the sliding sleeve, for example, in the direction of the coupling position when the sliding sleeve is in the uncoupling position. In this case, it is useful to design the spring element as a simple helical spring.

[0013] In order to ensure a simple and compact design of the shaft coupling, it is also advantageous if the first shaft has a hollow cylindrical head piece into which the sliding sleeve extends at least partially. A gear ring is then preferably positioned or formed on the inside of this head piece, which, when the sliding sleeve is in the coupling position, interacts with a gear ring on the outside of the sliding sleeve, so that the meshing of the two gear rings creates a temporary coupling between the sliding sleeve and the first shaft. Moving the sliding sleeve from the coupling position to the decoupling position then decouples the sliding sleeve from the first shaft, with the two gear rings of the head piece, on the one hand, and the sliding sleeve, on the other, being positioned offset from one another in the decoupling position in the direction of the shaft axis.

[0014] In an advantageous development, the head piece, on the one hand, and the sliding sleeve, on the other hand, have a plurality of spaced-apart, annular gear rings, wherein each gear ring on the head piece of the first shaft engages with a gear ring of the sliding sleeve when the sliding sleeve is in the coupling position, and wherein all gear rings, i.e. both the gear rings of the sliding sleeve and the gear rings of the head piece, are arranged next to one another along the shaft axis as long as the sliding sleeve is in the decoupling position. In this way, it is possible, on the one hand, to keep the displacement path of the sliding sleeve, i.e. the distance between the coupling position and the decoupling position, small and, on the other hand, to keep the load on the gear rings small. The loads arising from the torques to be transmitted are simply distributed across several gear rings.

[0015] Furthermore, the sliding sleeve is expediently designed like a hollow cylinder, and a sliding shaft preferably projects at least partially into the sliding sleeve. In this case, the sliding shaft is then connected or coupled to the sliding sleeve and thus interposed between the sliding sleeve and the second shaft. The sliding shaft preferably serves only to bridge the distance, whereby a large proportion of the remaining components and assemblies of the drive train can be left virtually unchanged and do not need to be adapted for a modified drive train presented here. The controllable shaft coupling presented and modified here can therefore be easily combined according to the modular principle with components, parts, or assemblies, such as a front axle transmission, of a state-of-the-art drive train.

[0016] Furthermore, the sliding shaft is expediently secured relative to the motor vehicle against movement in the direction of the shaft axis and accordingly, preferably only the sliding sleeve is displaced along the shaft axis for a coupling or decoupling process.

[0017] The coupling between the sliding sleeve and the sliding shaft is preferably designed as a permanent or permanent coupling and more preferably as a gear connection. For this purpose, the sliding sleeve on the inside and the sliding shaft on the outside each have at least one gear ring, which extend so far in the direction of the common shaft axis that they mesh with each other regardless of the position of the sliding sleeve.

[0018] Conveniently, the second shaft is then also connected to the sliding shaft via a gear connection, in particular a permanent gear connection.

[0019] Depending on the application, the sliding sleeve and the sliding shaft and / or the sliding shaft and the second shaft are permanently coupled by other non-rotatable connections, for example by a connection similar to a bung.

[0020] As previously mentioned, to implement the modified drivetrain presented here, as few components and assemblies as possible should be modified or adapted from a previously used drivetrain. Therefore, both the first shaft and the second shaft are preferably unchanged components, with the first shaft preferably being arranged as an intermediate shaft between an axle drive and a bearing block, and the second shaft preferably being arranged as a wheel drive shaft of a wheel suspension between the bearing block and a wheel.

[0021] The controllable shaft coupling, which connects the first shaft and the second shaft in a coupling manner and is interposed between the first shaft and the second shaft, is preferably integrated into the bearing block and is preferably prefabricated as an assembly unit for the final assembly of the drive train. According to one embodiment, the controllable shaft coupling is part of the front axle and serves to form a clutch-controlled all-wheel drive, with the drive train preferably having exactly two controllable clutches for this purpose, namely a controllable axle transfer case and the controllable shaft coupling.

[0022] Embodiments of the invention are explained in more detail below with reference to a schematic drawing. In the drawing: Fig. 1 in a block diagram representation of a drive train with a front axle transmission of an intermediate shaft and a shaft coupling in a bearing block, Fig. 2 in a perspective view the front axle gearbox together with the intermediate shaft and the shaft coupling in the bearing block, Fig. 3 in a side view the intermediate shaft and the shaft coupling, Fig. 4 in a sectional view the intermediate shaft and the shaft coupling, Fig. 5 in a perspective view the intermediate shaft, Fig. 6 in a side view a sliding sleeve and a sliding shaft of the shaft coupling, Fig. 7 in a perspective view the sliding sleeve, Fig. 8 in a side view the sliding shaft and Fig. 9 shows the sliding shaft in a perspective view.

[0023] Corresponding parts are provided with the same reference numerals in all figures.

[0024] An example described below and in Fig. The drivetrain 2 shown in Figure 1 is part of a passenger car with a clutch-controlled all-wheel drive (not shown in full). The drivetrain 2 comprises an internal combustion engine 4, a transmission 6, which is designed, for example, as an automatic transmission, and an axle transfer case 8.

[0025] The axle transfer case 8 is designed such that a rear axle drive shaft 10 is permanently coupled to the transmission gear 6 via the axle transfer case 8. The rear axle drive shaft 10 is in turn permanently connected to the wheels 14 of the rear axle 16 via a rear axle transmission 12, thus ultimately achieving permanent rear-wheel drive.

[0026] Furthermore, the axle transfer case 8 allows a front axle drive shaft 18 to be coupled to the transmission 6 at any time, so that additional torque can be transmitted to a front axle transmission 20 and thus to a front axle 22. The passenger car thus has permanent rear-wheel drive with selectable front-wheel drive.

[0027] In addition to the coupling and decoupling of the front axle drive shaft 18 by the axle transfer case 8, a further coupling and decoupling is always carried out simultaneously on the front axle 22 in the area of the right bearing block 24, whereby the front axle drive shaft 18 and other components and assemblies are decoupled from the wheels 14 of the front axle 22 as soon as the front-wheel drive is deactivated, so that they no longer rotate but are virtually shut down.

[0028] The coupling unit or shaft coupling 26 provided for this purpose is integrated into the bearing block 24 and in Fig. 2 to Fig. 4. It connects an intermediate shaft 28, which is connected to the front axle transmission 20, with a wheel drive shaft 30, which is connected in a rotationally fixed manner to a wheel 14 of the front axle 22, and couples them together when required for torque transmission.

[0029] To form the shaft coupling 26, the intermediate shaft 28 has a hollow cylindrical head piece 32 at the end facing the long block 24, on the inner surface of which several annular gear rings 34 are arranged. The gear rings 34 are evenly distributed in a section along a shaft axis 36, with a distance being left between each two gear rings 34 that is slightly larger than the uniform width of the gear rings 34.

[0030] Part of the shaft coupling 26 is also a hollow cylindrical selector sleeve or sliding sleeve 38, on whose outer surface gear rings 34 are also arranged. In the shaft coupling 26, the sliding sleeve 38 is displaced as needed, i.e., for coupling or decoupling the intermediate shaft 28 and the wheel drive shaft 30, between a coupling position 40 and a decoupling position 42, wherein the gear rings 34 of the sliding sleeve 38 and the gear rings 34 of the head piece 32 engage with one another when the sliding sleeve 38 is in the coupling position 40, and wherein the gear rings 34 of the sliding sleeve 38 are positioned offset in the direction of the shaft axis 36 from the gear rings 34 of the head piece 32 when the sliding sleeve 38 is in the final coupling position 42.The two middle gear rings 34 of the sliding sleeve 38 are then located exactly between two gear rings 34 of the head piece 32, as seen in the direction of the shaft axis 36, and the gear connection between the sliding sleeve 38 and the head piece 32 is no longer present.

[0031] The sliding sleeve 38 is moved between the coupling position 40 and the decoupling position 42 by means of an adjusting body 44 and a helical spring 46, which is located in the head piece 32 and on which the sliding sleeve 38 virtually sits.

[0032] By means of a magnetic actuator 48, the adjusting body 44 can be displaced along a transverse direction 50 transverse to the shaft axis 36. Due to the wedge-shaped design of the adjusting body 44, the force exerted by the adjusting body 44 is deflected in the transverse direction 50 and the sliding sleeve 38 is displaced in the direction of the shaft axis 36 against the helical spring 46, essentially sliding along the inclined contact surface 52 on the adjusting body 44. If the adjusting body is moved back to its original position via the actuator 48, the restoring force of the screw fields 46 causes the sliding sleeve 38 to return, and thus the sliding sleeve 38 is guided back and forth between the coupling position 40 and the decoupling position 42 by the interaction of the adjusting body 44 and the helical spring 46.

[0033] To minimize the loads on the adjusting body 44 and the sliding sleeve 38 caused by contact in the area of the contact surface 52, the sliding sleeve 38 has a roller bearing 54 designed as a ball bearing, which is firmly connected to the hollow cylindrical body of the sliding sleeve 38 and is part of the sliding sleeve 38. The contact surface 52 then lies directly against the roller bearing 54. The contact surface 52 is the only surface that lies against the outer circumference of the roller bearing 54.

[0034] The sliding sleeve 38 has a toothing on the inside that runs in the direction of the shaft axis 36, via which the sliding sleeve 38 is connected in a rotationally fixed manner to a sliding shaft 56, which in turn has a corresponding toothing or a corresponding gear ring 34 on the outside. The sliding shaft 56 serves only to bridge the distance and is in turn connected in a rotationally fixed manner to the wheel drive shaft 30, whereby a gear connection is also used here.

[0035] The invention is not limited to the exemplary embodiment described above. Rather, other variants of the invention can also be derived therefrom by those skilled in the art without departing from the subject matter of the invention. In particular, all individual features described in connection with the exemplary embodiment can also be combined with one another in other ways without departing from the subject matter of the invention. List of reference symbols 2 Drivetrain 4 combustion engine 6 transmission gears 8 axle transfer cases 10 Rear axle drive shaft 12 rear axle transmission 14 wheels 16 Rear axle 18 Front axle drive shaft 20 front axle transmission 22 front axle 24 bearing block 26 Shaft coupling 28 Intermediate shaft 30 Wheel drive shaft 32 headpiece 34 gear ring 36 Shaft axis 38 sliding sleeve 40 coupling position 42 Decoupling position 44 actuators 46 coil spring 48 Actuator 50 transverse direction 52 contact surface 54 rolling bearings 56 sliding shaft

Claims

[1] Drive train (2) for a motor vehicle with a clutch-controlled all-wheel drive, comprising a first shaft (28) and a second shaft (30) arranged along a common shaft axis (36), and comprising a controllable shaft coupling (26), wherein - the controllable shaft coupling (26) comprises a sliding sleeve (38) which can be moved between a decoupling position (42) and a coupling position (40) along the shaft axis (36) by means of an adjusting body (44) which can be moved transversely to the shaft axis (36), - the two shafts (28,30) are decoupled when the sliding sleeve (38) is in the decoupling position (42), and - the two shafts (28,30) are coupled when the sliding sleeve (38) is in the coupling position (40), characterized bythat the adjusting body (44) and the sliding sleeve (38) touch at a contact surface (52) via which a transverse force exerted by the adjusting body (44) in the transverse direction (50) is converted into a sliding force acting in the direction of the shaft axis (36). [2] Drive train (2) according to one of the preceding claims, characterized by that the adjusting body (44) is wedge-shaped. [3] Drive train (2) according to one of the preceding claims, characterized by that the sliding sleeve (38) has a rolling bearing (54) and that the adjusting body (44) engages the rolling bearing (54). [4] Drive train (2) according to one of the preceding claims, characterized by that the actuating body (44) is movable by means of a magnetic actuator (48). [5] Drive train (2) according to one of the preceding claims, characterized by that the sliding sleeve (38) is spring-mounted by means of a spring element (46). [6] Drive train (2) according to one of the preceding claims, characterized by that the first shaft (28) has a hollow cylindrical head piece (32) and that the sliding sleeve (38) projects at least partially into the head piece (32). [7] Drive train (2) according to claim 6, characterized by that the head piece (32) on the inside and the sliding sleeve (38) on the outside each have a gear ring (34), wherein these two gear rings (34) engage with each other when the sliding sleeve (38) is in the coupling position (40), and wherein these two gear rings (34) are positioned offset from each other in the direction of the shaft axis (36) when the sliding sleeve (38) is in the decoupling position (42). [8] Drive train (2) according to claim 6 or 7, characterized by that the head piece (32) on the inside and the sliding sleeve (38) on the outside each have a plurality of spaced-apart, annular gear rings (34). [9] Drive train (2) according to one of the preceding claims, characterized by that the sliding sleeve (38) has a hollow cylindrical shape and that a sliding shaft (56) projects at least partially into the sliding sleeve (38). [10] Drive train (2) according to one of the preceding claims, characterized by that the sliding shaft (56) is secured relative to the motor vehicle against movement in the direction of the shaft axis (36). [11] Drive train (2) according to one of the preceding claims, characterized by that the sliding sleeve (38) on the inside and the sliding shaft (56) on the outside each have a gear ring (34) which engage with each other regardless of the position of the sliding sleeve (38). [12] Drive train (2) according to one of the preceding claims, characterized by that the sliding shaft (56) is connected to the second shaft (30) in a rotationally fixed manner by means of a gear ring connection. [13] Drive train (2) according to one of the preceding claims, characterized by that the controllable shaft coupling (26) is integrated into a bearing block (24) which is arranged between a wheel suspension (30) and an axle transmission (20). [14] Drive train (2) according to claim 13, characterized by that the first shaft (28) is arranged as an intermediate shaft (28) between the axle gear (20) and the bearing block (24) and that the second shaft (30) is arranged as a wheel drive shaft (30) of the wheel suspension (30) between the bearing block (24) and a wheel (14).

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