Locking differential gear mechanism

Abstract

The invention relates to a locking differential gear mechanism (1), comprising three connection points (2, 3, 4), wherein at least one locking device (18, 19) is provided, which in each case has a respective actuating device (20) and friction discs (26, 27) situated axially next to each other, a plurality of which are in the form of couplable friction discs (26) and at least one of which is in the form of a friction disc (27) permanently coupled to one of the connection points (2, 3, 4). The couplable friction discs (26) are each equipped with a respective coupling profile (31), wherein the at least one locking device (18, 19) in each case has an associated sliding element, which is guided in a rotationally fixed and axially displaceable manner on the part of another of the connection points (2, 3, 4). The in each case one sliding element can be axially overlapped by a different number of the couplable friction discs (26) by axial displacement and depending on its axial position and in so doing can in each case be connected in a rotationally fixed manner to overlapping, couplable friction discs (26) by being respectively held in the respective coupling profile (31). Here, the in each case one sliding element is designed as a respective annular shift collar (32) which is arranged coaxially and radially adjacent to the friction discs (26, 27) and is equipped with a respective engagement profile (34) at which the respective holding in the respective coupling profile (31) takes place.

Description

[0001] Limited-slip differential

[0002] The invention relates to a limited-slip differential transmission comprising three connection points in the form of a transmission input and two transmission outputs, wherein at least one locking device is provided, each of which has an actuating device and axially adjacent friction discs, several of which are present as connectable friction discs and at least one is present as a friction disc permanently coupled to one of the connection points, wherein the friction discs can be placed axially against one another by the action of each actuating device and thereby frictional couplings can be formed between the connectable friction discs and the at least one permanently coupled friction disc, wherein the connectable friction discs are each equipped with a coupling profile and a sliding element is assigned to each of the at least one locking device, which sliding element is guided in a rotationally fixed and axially displaceable manner by another of the connection points,and wherein each sliding element can be brought into axial overlap with a different number of the connectable friction discs by axial displacement and depending on its axial position, and can thereby be connected in a rotationally fixed manner to the overlapping, connectable friction discs by a respective enclosing in the respective coupling profile.

[0003] Differential gears are used in motor vehicle drivetrains to distribute drive torque introduced on the input side to output sides connected to the transmission outputs of the respective differential gear, thereby enabling different speeds between the output sides through speed compensation. Depending on the specific integration of the respective differential gear, the distribution takes place either in the form of a transverse distribution to the drive wheels of a drive axle or in the form of a longitudinal distribution to several drive axles. In the case of varying traction or an extreme inclination, however, the possible speed compensation can result in spinning on one output side while the other output side remains stationary. In this case, the associated vehicle may then be unable to move.In addition to differentials with differential locks that can be actively engaged by the driver, limited-slip differentials are also known, in which the respective speed compensation is automatically limited. A distinction must be made here between active limited-slip differentials, in which a locking effect is controlled, and passive limited-slip differentials, in which a locking effect is generated either permanently or automatically depending on a parameter. In some cases, limited-slip differentials also incorporate measures to adjust the respective locking effect of a locking device.

[0004] EP 3 453 921 A1 discloses a limited-slip differential designed as a bevel gear differential and having a transmission input in the form of a differential housing and two transmission outputs in the form of output bevel gears. The transmission input and the transmission outputs form connection points to which the limited-slip differential can be integrated into a motor vehicle's drivetrain. The limited-slip differential is also equipped with locking devices, each of which can generate a locking effect in the form of a locking torque between the transmission input and each of the transmission outputs.The locking devices each consist of an actuating device formed by a ramp block and axially adjacent friction discs which can be axially applied to one another under the influence of the ramp block depending on a load introduced via the differential housing, thereby forming frictional couplings between the friction discs. Of the friction discs of the individual locking device, several friction discs are permanently coupled friction discs, each of which is guided radially on the inside via a guide toothing in a rotationally fixed and axially displaceable manner on the respective output bevel gear. These permanently coupled friction discs are arranged axially alternating with coupleable friction discs, each of which is provided radially on the outside with a coupling profile in the form of a coupling toothing.Furthermore, the individual locking device has several sliding elements in the form of selector shafts, which in one variant are guided on the differential housing in a rotationally fixed and axially movable manner and each overlaps with an increasing number of connectable friction discs with increasing axial displacement. When the individual selector shaft overlaps with the respective connectable friction disc, it engages this friction disc in the respective clutch toothing, whereby the individual selector shaft is then rotationally connected to the respective connectable friction disc. As a result, the number of rotationally integrated, connectable friction discs can be changed depending on the axial displacement of the selector shafts, and thus the locking effect can also be modified. The joint axial displacement of the selector shafts can be brought about by a thrust ring or similar.

[0005] Based on the prior art described above, it is now the object of the present invention to provide a limited-slip differential gear in which a respective locking effect of at least one locking device is adaptable and the at least one locking device has the simplest possible structure.

[0006] This object is achieved based on the preamble of claim 1 in conjunction with its characterizing features. The dependent claims that follow each of these claim set forth advantageous developments of the invention.

[0007] According to the invention, a limited-slip differential comprises three connection points in the form of a transmission input and two transmission outputs. Furthermore, at least one locking device is provided, each of which has an actuating device and axially adjacent friction discs, several of which are present as connectable friction discs and at least one of which is present as a friction disc permanently coupled to one of the connection points. The friction discs can be axially applied to one another by the action of each actuating device, thereby forming frictional couplings between the connectable friction discs and the at least one permanently coupled friction disc, wherein the connectable friction discs are each equipped with a coupling profile.Furthermore, a sliding element is assigned to each of the at least one locking device, which sliding element is guided in a rotationally fixed and axially displaceable manner by another of the connection points, wherein the respective sliding element can be brought into axial overlap with a different number of the coupling-capable friction discs by displacement and depending on its axial position and can thereby be connected in a rotationally fixed manner to the overlapping, coupling-capable friction discs by a respective enclosing in the respective coupling profile.

[0008] The limited-slip differential according to the invention thus has three connection points, one of which is a transmission input and the remaining connection points are two transmission outputs. At the transmission input, a drive torque can be fed into the limited-slip differential and distributed within the limited-slip differential, in particular via a differential gear set, between the two transmission outputs. Speed ​​differences between the transmission outputs can be permitted via the differential gear set. In this respect, speed compensation can take place within the limited-slip differential. For this purpose, the differential gear set is preferably designed as a differential gear set and couples the three connection points of the limited-slip differential to one another.

[0009] A differential gear set of the limited-slip differential according to the invention can be designed within the scope of the invention such that the differential gear set distributes the drive torque introduced at the transmission input evenly between the two transmission outputs, i.e., it divides it equally between the transmission outputs. The limited-slip differential can then be designed as a transverse differential, although it could also be configured as a longitudinal differential with an even distribution. Alternatively, an uneven distribution of the drive torque between the two transmission outputs via the differential gear set is also contemplated within the scope of the invention, in which case the limited-slip differential is designed as a longitudinal differential.

[0010] The limited-slip differential gear further comprises at least one locking device which, upon respective actuation, serves to limit the speed compensation in the limited-slip differential gear by generating a respective locking effect. The at least one locking device is preferably arranged in the power flow parallel to a differential gear set of the limited-slip differential gear between two of the connection points. Accordingly, these two connection points can be coupled via the at least one locking device parallel to the differential gear set. The respective limitation of the speed compensation takes place in particular partially in order to be able to specifically allocate a higher torque component to one of the transmission outputs while still permitting speed differences between the transmission outputs within a limited range.

[0011] Most preferably, the at least one locking device is in the form of a self-actuating or automatically actuating locking device, i.e. in both cases, actuation of the at least one locking device and thus the induction of a respective locking effect does not have to be brought about actively by a vehicle driver, but takes place without any action on the part of the vehicle driver.

[0012] In particular, the at least one locking device is provided to automatically generate a locking effect between two of the connection points. The generation of a "locking effect" between the connection points means that the at least one locking device creates a coupling between the two connection points that is parallel to a differential gear set of the limited-slip differential, which also limits the speed compensation that can be achieved via the differential gear set. By "automatic" in the sense of the invention, we mean that the generation of the locking effect in the at least one locking device occurs automatically, i.e. is neither actively brought about by a vehicle driver nor by a control or regulation and a corresponding actuator system. In the at least one locking device, the respective locking effect is then generated without drive technology and based on physical effects.In particular, a respective locking effect is brought about automatically via the at least one locking device as a function of a parameter, wherein this parameter can be a drive torque introduced at the transmission input or a speed difference between the transmission outputs.

[0013] In principle, however, the locking device could also be designed to be automatically actuated, i.e., in this case, an actuator is provided via which the at least one locking device is automatically actuated within the framework of a control or regulation system, thereby generating the respective locking effect. This would then make the limited-slip differential an active limited-slip differential.

[0014] The at least one locking device comprises an actuating device and axially adjacent friction discs, several of which are designed as connectable friction discs, while at least one friction disc is permanently coupled to one of the connection points of the limited-slip differential. The friction discs are preferably designed as inner plates and as outer plates, with the connectable friction discs in particular being outer plates and the at least one permanently coupled friction disc each being an inner plate. In particular, the at least one locking device has, in addition to a plurality of connectable friction discs, a plurality of permanently coupled friction discs, each of which is permanently coupled to the one connection point.

[0015] The permanent coupling of the at least one friction disc to the one connection point is preferably realized by a rotationally fixed and axially displaceable guide of the at least one friction disc on the side of the one connection point. The latter is carried out in particular directly on a component forming the one connection point, but can also be realized within the scope of the invention indirectly on a component which is permanently coupled to another component forming the one connection point. Very particularly preferably, the at least one friction disc is provided with a driving toothing on which the rotationally fixed and axially displaceable guidance of the at least one friction disc is respectively implemented. The driving toothing of the at least one permanently coupled friction disc is in particular each designed as an axially extending straight toothing.

[0016] The at least one permanently coupled friction disc and the couplable friction discs are arranged axially next to one another, with an alternating arrangement in the axial direction being particularly preferred in that the at least one permanently coupled friction disc is placed axially between two couplable friction discs. If the at least one locking device has a plurality of permanently coupled friction discs, then couplable friction discs and permanently coupled friction discs follow one another alternately in the axial direction. In particular, in addition to the friction discs, an end plate is also provided which is arranged axially at the end on one side of the friction discs. The end plate is preferably permanently coupled to one connection point or to another connection point which is to be coupled to the one connection point via the at least one locking device.

[0017] The friction discs can be acted upon by means of each actuating device of the at least one locking device in such a way that the friction discs are placed axially against one another when acted upon, which results in the formation of frictional couplings between the coupleable friction discs and the at least one permanently coupled friction disc. The degree of frictional coupling depends, in a manner known in principle to those skilled in the art, on the extent to which the friction discs are placed axially against one another, i.e. with which normal force axially adjacent friction discs are pressed against one another. Slippage can also occur between the friction discs that are placed against one another, i.e. the friction discs that are placed against one another have different speeds of rotation when frictionally coupled.If the at least one locking device is designed as an automatically actuating locking device, each actuating device then acts on the friction discs, in particular without drive technology and on the basis of physical effects.

[0018] The at least one locking device of the limited-slip differential gear is also assigned a respective sliding element, which is guided axially displaceably in a rotationally fixed manner by another of the connection points. Each sliding element is preferably guided in a rotationally fixed and axially displaceable manner on a component that forms the other connection point or is permanently coupled to a component that forms the other connection point. In this respect, a rotationally fixed coupling also exists between each sliding element and the other connection point, whereby each sliding element can be axially displaced.During axial displacement, each sliding element can be axially overlapped with a varying number of connectable friction discs, depending on its position. Upon axial overlap of each sliding element with a connectable friction disc, each sliding element is then engaged in a respective coupling profile of the overlapping, connectable friction disc. As a result of this engagement, each sliding element is subsequently connected in a rotationally fixed manner to the respective connectable friction disc, which also results in a rotationally fixed connection of the respective connectable friction disc to the other connection point.

[0019] Depending on its axial position, each sliding element overlaps with a different number of connectable friction discs, i.e. the number of axially overlapping friction discs that are thus also connected in a rotationally fixed manner to each sliding element changes depending on the axial position of each sliding element. As a result, the number of connectable friction discs that are indirectly coupled in a rotationally fixed manner to the other connection point via each sliding element also changes accordingly, so that when the friction discs are applied axially under the influence of each actuating device, the number of active friction surfaces of the at least one locking device also changes. In this way, a locking effect that can be generated by the at least one locking device can be changed depending on the axial position of each sliding element.

[0020] The connectable friction discs are each provided with a coupling profile, to which the respective coupling profile of the respective coupling discs with the respective sliding element is established upon engagement of the respective sliding element. Preferably, each coupling profile is designed as a respective coupling toothing, the latter being designed in particular as an axially extending straight toothing, whereby the respective sliding element can be easily displaced axially relative to the respective coupling disc.

[0021] In the context of the invention, "axial" refers to a parallel alignment to a longitudinal center axis of the limited-slip differential, with the longitudinal center axis preferably being parallel to the rotational axes of the limited-slip differential. "Radial" refers to a direction in the diameter direction of a respective component of the limited-slip differential.

[0022] The invention now comprises the technical teaching that each sliding element is designed as an annular shift sleeve, which is arranged coaxially and radially adjacent to the friction discs and is each equipped with an engagement profile at which the respective engagement with the respective clutch profile takes place. In other words, each sliding element of the at least one locking device is therefore each in the form of a shift sleeve, which is annular in design and arranged radially adjacent to and coaxial with the friction discs. Each shift sleeve is provided with an engagement profile at which an engagement with the respective clutch profile of the respective connectable friction disc takes place when the shift sleeve axially overlaps this friction disc.

[0023] Such a limited-slip differential design offers the advantage that a torsionally fixed connection can be achieved in a compact manner via an annular shift sleeve with axial overlap with the individual, connectable friction disc. Furthermore, a locking device with each annular shift sleeve is characterized by its simple design.

[0024] According to the invention, each shift sleeve is arranged radially adjacent to the friction discs, i.e. it is placed either radially inward or radially outward to the friction discs, depending on which radial side of the connectable friction discs the clutch profiles are formed on. If the connectable friction discs are provided with the clutch profiles radially outward, i.e. are designed as outer plates, each shift sleeve is arranged radially surrounding the friction discs. If, on the other hand, the connectable friction discs have the clutch profiles on their radial inner sides, each shift sleeve is arranged radially inward to the friction discs. In both cases, each shift sleeve is arranged coaxially to the friction discs.

[0025] The respective engagement profile of each shift sleeve is preferably designed as a counterpart to the clutch profiles of the connectable friction discs. In this respect, when the clutch profiles are designed as clutch teeth, the respective engagement profile is preferably designed as engagement teeth. This allows the annular shift sleeve to be enclosed at the engagement teeth essentially all the way around in the respective clutch teeth of the individual connectable and axially overlapping friction disc, whereby a load when transmitting torque between the shift sleeve and the friction disc can be easily distributed over a larger number of teeth of the clutch teeth and the engagement teeth. This can therefore reduce component loads. If the clutch teeth are preferably designed as axially extending straight teeth, the respective engagement teeth are then also designed as axially extending straight teeth.

[0026] On the axial end faces, from which the respective engagement profile is inserted into the respective clutch profile, the engagement profile and the clutch profiles can each be provided with a geometry that facilitates relative rotation of the respective shift sleeve and the respective coupling friction disc in the profile-on-profile position in order to resolve the profile-on-profile position. If the engagement profile and the clutch profiles are designed as toothings, the toothings can, for example, be designed with corresponding roof slopes on the end faces in order to resolve tooth-on-tooth positions. Alternatively or additionally, a type of synchronization could also be provided.

[0027] According to one embodiment of the invention, each shift sleeve is assigned an adjusting device at which an adjusting movement can be initiated and the axial displacement of the respective shift sleeve can be brought about as a result. Each adjusting device preferably serves to initiate a manual adjusting movement so that the axial displacement of the respective shift sleeve of the at least one locking device is also brought about manually. Alternatively, each adjusting device can also have a corresponding actuator via which the adjusting movement can be generated. In a further development of the aforementioned embodiment, each adjusting device has a carrier ring which is arranged coaxially and axially overlapping and radially adjacent to the respective shift sleeve and guides an adjusting pin in at least one recess which is enclosed in a recess on the side of the respective shift sleeve.When the actuating movement is initiated on the respective actuating device, each carrier ring executes an axial sliding movement, thereby axially driving the respective shift sleeve via the respective actuating pin. Advantageously, this allows the axial displacement of the respective shift sleeve via the coaxial and radially adjacent carrier ring to be reliably configured for the respective actuating device, by converting a sliding movement of the carrier ring via the respective actuating pin into the corresponding axial displacement of the respective shift sleeve.

[0028] The fact that each carrier ring is arranged radially adjacent to each shift sleeve means, in the sense of the invention, that each carrier ring is positioned either radially inward or radially outward of each shift sleeve, in particular depending on which radial side of each shift sleeve the respective engagement in the coupling profiles of the connectable friction discs is to take place. If each annular shift sleeve is positioned radially surrounding the friction discs, each carrier ring is preferably in turn positioned radially surrounding each shift sleeve. If, on the other hand, each shift sleeve is arranged radially inward of the friction discs, each carrier ring is positioned in particular radially inward of each shift sleeve. However, each carrier ring is always arranged coaxially to each shift sleeve.

[0029] Alternatively, but preferably in addition to the aforementioned development, each adjusting device has an adjusting ring which is rotatably guided by a screw connection on the side of the other connection point and into which the adjusting movement can be initiated as a rotary movement. Each screw connection converts the adjusting movement initiated as a rotary movement into an axial displacement of the respective adjusting ring relative to the other connection point. As a result, the adjusting movement can be initiated as a rotary movement and, with the help of the respective screw connection, can be easily converted into an axial displacement of the respective adjusting ring, resulting in a movement suitable for initiating the axial movement of the respective shift sleeve.

[0030] Particularly preferably, the developments of the aforementioned embodiment are implemented jointly, wherein the respective one carrier ring and the respective one adjusting ring are arranged coaxially to one another. In addition, the respective one carrier ring is guided axially fixedly on the respective one adjusting ring. This makes it possible to implement a suitable structure for the respective adjusting device. Preferably, the respective one carrier ring is held axially in the respective one adjusting ring between a respective contact shoulder, which is defined by the respective one adjusting ring, and a retaining ring received on the respective one adjusting ring. In this case, in particular a sliding disk can also be provided axially between the retaining ring and the carrier ring.

[0031] According to one possible embodiment of the invention, each shift sleeve is assigned a locking device, via which the shift sleeve can be locked directly or indirectly in discrete axial positions. An axial overlap of the shift sleeve, each with an associated number of connectable friction discs, is assigned to each discrete axial position. This has the advantage that, with the aid of each locking device, it can be directly or indirectly ensured that each shift sleeve remains in the desired axial position, and thus, due to the associated rotationally fixed connection with an associated number of connectable friction discs, a desired locking effect of the at least one locking device is also realized.“Directly” means that each locking device acts directly on each shift sleeve and thereby locks it in the respective axial position, while “indirectly” means that each locking device acts on a component that is permanently coupled to each shift sleeve.

[0032] In a further development of the aforementioned design option and in combination with one of the previous variants, each locking device is accommodated between each actuating device and the other connection point and locks each actuating device in the discrete axial positions of the respective sliding positions associated with each shift sleeve relative to the other connection point. In this case, an indirect locking of each shift sleeve is realized.

[0033] As an alternative to providing a locking device in each case, a clamping or self-locking of the respective shift sleeve or the respective actuating device can also be provided within the scope of the invention.

[0034] One embodiment of the invention provides that the transmission input is formed by a differential housing in which a differential gear set is accommodated. The differential housing couples to the output gears forming the transmission outputs via the differential gear set. In this case, one connection point in the form of the transmission input is formed by the differential housing, while the remaining connection points and thus the transmission outputs are represented by output gears of the limited-slip differential.

[0035] Part of the differential gear set is preferably at least one differential pin, on which at least one differential gear is rotatably mounted, wherein the at least one differential gear meshes with the output gears. The speed compensation between the output gears can be achieved via the at least one differential gear in a manner known in principle to those skilled in the art, by the at least one differential gear performing corresponding rotational movements on the at least one differential pin. The differential gear set of the limited-slip differential is preferably designed in the manner of a bevel gear set, a planetary gear set, or a spur gear set.

[0036] In a further development of the aforementioned embodiment and in combination with the previously described design of the respective adjusting device, each shift sleeve is guided in a rotationally fixed and axially displaceable manner via a respective driving toothing on an inner surface of a respective wooden cylindrical section of the differential housing. Each screw connection is formed by an external thread on an outer surface of the respective wooden cylindrical section of the differential housing and an internal thread, which is guided on the respective external thread and which is configured on the respective adjusting ring. In addition, each carrier ring is guided radially outwardly of the wooden cylindrical section of the differential housing in the respective adjusting ring, wherein the respective adjusting pin is guided radially through an opening in the wooden cylindrical section.

[0037] According to one possible embodiment of the invention, each actuating device acts automatically on the respective friction discs of the at least one locking device as a function of a load introduced at the transmission input or as a function of a differential speed between the transmission outputs.

[0038] In this case, the limited-slip differential gear according to the invention is designed as a self-locking differential.

[0039] Preferably, each actuating device of the at least one locking device is formed by a thrust ring, which is movable axially against the respective friction discs of the at least one locking device via an element of the differential gear set depending on the load introduced at the transmission input. This advantageously allows for load-dependent actuation of the at least one locking device to be implemented in a simple manner. The element is preferably a differential pin of the limited-slip differential gear.

[0040] According to one embodiment of the invention, two locking devices are provided, each of which serves to couple the transmission input to one of the transmission outputs. This allows for uniform restriction of the speed compensation in the limited-slip differential gear. This design is preferably implemented when the restriction of the speed compensation is to be brought about in a load-dependent manner. In particular, the two locking devices have the same design. The locking devices preferably function independently of one another. Within the scope of the invention, however, a single locking device could also be provided, via which a coupling between the two transmission outputs can be brought about.

[0041] A preferred embodiment of the invention, which is explained below, is illustrated in the drawings. It shows:

[0042] Fig. 1 to 4 show different views of a limited-slip differential gear according to a preferred embodiment of the invention; and

[0043] Fig. 5 to 7 different operating states of a locking device of the limited-slip differential according to Fig. 1 to 4.

[0044] Figs. 1 to 4 show different views of a limited-slip differential 1, which is designed according to a preferred embodiment of the invention. The limited-slip differential 1 comprises three connection points 2, 3, and 4, of which connection point 2 serves as the transmission input 5 of the limited-slip differential 1, while connection points 3 and 4 each represent a transmission output 6 and 7, respectively.

[0045] The limited-slip differential 1 is designed here as a transverse differential and has a two-part differential housing 8, which forms the connection point 2 and thus the transmission input 5 of the limited-slip differential 1 and at which a drive torque can be introduced. For this purpose, the differential housing 8 is designed in particular to be non-rotatably connected to a drive ring gear at circumferential flange sections 9 of housing parts 10 and 11 of the differential housing 8. The housing parts 10 and 11 are each pot-shaped and together define an interior space 12 of the differential housing 8. A differential pin 13 is guided on the differential housing 8 within the interior space 12, with two differential gears 14 and 15 in the form of bevel gears being rotatably mounted on the differential pin 13. The differential gears 14 and 15 are also accommodated in the interior space 12.The two differential gears 14 and 15 are each in meshing engagement in the interior 12 with two output gears 16 and 17, which are also designed as bevel gears and each form one of the transmission outputs 6 and 7. Due to the design of the differential gears 14 and 15 and the output gears 16 and 17 as bevel gears, the limited-slip differential 1 is designed as a bevel gear differential. In a manner known in principle to those skilled in the art, the differential gears 14 and 15 can enable different speeds of the output gears 16 and 17 by rotating them on the differential pin 13, thus providing speed compensation. The output gears 16 and 17 each serve for a rotationally fixed connection to a drive shaft of a motor vehicle drive axle, for which purpose the differential housing 8 has corresponding through-openings.

[0046] The limited-slip differential gear 1 according to the invention comprises two locking devices 18 and 19, each of which can automatically transmit torque from the transmission input 5 to the respective transmission output 6 or 7, parallel to a coupling represented by the differential gears 14 and 15 and the output gears 16 and 17. This allows the speed compensation that can be achieved by the differential gears 14 and 15 to be partially limited. The locking devices 18 and 19 are constructed correspondingly to one another, so that for the sake of simplicity, only the construction of the locking device 18 will be described below. Therefore, what is described below regarding the locking device 18 also applies analogously to the locking device 19, which has the same construction but is arranged in a mirror image.

[0047] As can be seen in Figs. 1 to 4, the locking device 18 comprises an actuating device 20 in the form of a pressure ring 21, which is guided in the housing part 10 in a rotationally fixed and axially displaceable manner. For this purpose, the pressure ring 21, as can be seen in particular in Figs. 3 and 4, is equipped with an axially extending guide toothing 22, on which a tooth engagement with a toothing 23 is established. The toothing 23 is formed as an axially extending straight toothing on an inner surface of a hollow cylindrical section of the housing part 10. If a drive torque is introduced into the limited-slip differential gear 1 via the differential housing 8, the differential bolt 13 is moved via the differential housing 8 and runs against the pressure ring 21, which is displaced axially in the direction of a friction disc pack 24 of the locking device 18 depending on the load introduced at the differential housing 8.The friction disc assembly 24 of the locking device 18 is composed of an end plate 25, a plurality of connectable friction discs 26, and a plurality of coupled friction discs 27. The coupled friction discs 27 are designed as inner plates and are each guided in a rotationally fixed and axially displaceable manner on a toothing 29, which can be seen in Fig. 3, on a toothing 28 provided on the output gear 16. Accordingly, the coupled friction discs 27 are each permanently connected in a rotationally fixed manner to the output gear 16. Furthermore, the coupled friction discs 27 are each equipped with friction linings 30 on both axial sides.

[0048] Within the friction disc pack 24, the coupled friction discs 27 and the couplable friction discs 26 are arranged axially alternately, with the last of the coupled friction discs 27 being placed axially between the last of the couplable friction discs 26 and the end plate 25 on a side facing away from the pressure ring 21. Upon axial displacement of the pressure ring 21 in the direction of the friction disc pack 24, the pressure ring 21 presses the friction discs 26 and 27 as well as the end plate 25 against a bottom section of the housing part 10, whereby the friction discs 26 and 27 axially abut one another and thereby frictional couplings are formed between the couplable friction discs 26 and the coupled friction discs 27.

[0049] The connectable friction discs 26 are each designed as outer plates and are each equipped on a respective outer circumference with a coupling profile 31 in the form of a coupling toothing, via which the connectable friction discs 26 can be coupled to the housing part 10 in a rotationally fixed and axially displaceable manner. The respective coupling can be established via an annular shift sleeve 32 which, like the friction disc package 24, is accommodated in the interior 12 of the differential housing 8. The shift sleeve 32 has a driving toothing 33 on an outer circumference, which can be seen in particular in Fig. 4 and on which the shift sleeve 32 is guided in a rotationally fixed and axially displaceable manner on the toothing 23 of the housing part 10.On an inner circumference, the shift sleeve 32 is also provided with an engagement profile 34 in the form of engagement teeth, with which the shift sleeve 32 can engage in the coupling profiles 31 of the connectable friction discs 26. By means of the respective engagement, the respective connectable friction disc 26 is then connected in a rotationally fixed manner to the shift sleeve 32 and thus also to the housing part 10, whereby a frictional coupling of the respective connectable friction disc 26 with the axially adjacent coupled friction disc 27 then also creates a frictional coupling of the housing part 10 with the output gear 16.

[0050] The number of friction discs 26 that can be coupled and are connected to the housing part 10 in a rotationally fixed manner, and thus also the number of active friction surfaces of the locking device 18, is adjusted via the axial position of the shift sleeve 32 in the housing part 10. For axial displacement and thus a change in the axial position of the shift sleeve 32, the locking device 18 has an adjusting device 35 that has an adjusting ring 36. The adjusting ring 36 is equipped with an internal thread 37, on which, together with an external thread 38, a screw connection 39 is formed between the adjusting ring 36 and the housing part 10. The external thread 38 is formed on an outer surface of the hollow cylindrical section of the housing part 10.The adjusting ring 36 can be rotated relative to the housing part 10 via the screw connection 39, whereby a rotary movement manually initiated as an adjusting movement on the adjusting ring 36 is converted via the screw connection 39 into an axial displacement of the adjusting ring 36 relative to the housing part 10. For the manual initiation of the adjusting movement, the adjusting ring 36 is provided with an engagement contour 40 on an outer circumference.

[0051] The adjusting ring 36 guides a carrier ring 41 of the adjusting device 35, wherein the carrier ring 41 is held coaxially to the adjusting ring 36 in the adjusting ring 36 axially between, on the one hand, a contact shoulder 42 and, on the other hand, a retaining ring 43 and an intermediate sliding disk 44. As a result, the carrier ring 41 is moved axially with the axial movement of the adjusting ring 36 towards the housing part 10. The carrier ring 41 is also arranged coaxially and radially surrounding the shift sleeve 32 and has a plurality of recesses 45, in each of which an adjusting pin 46 is guided. In addition to the recesses 45, the adjusting pins 46 each engage in a corresponding recess 47 on the side of the shift sleeve 32, for which purpose the adjusting pins 46 are each guided through corresponding openings 48 in the housing part 10. The openings 48 are designed as elongated holes.The engagement of the adjusting pins 46 results in the axial movement of the carrier ring 41 with the adjusting ring 36 also resulting in a corresponding axial movement of the shift sleeve 32 and thus its axial displacement relative to the housing part 10. Ultimately, by rotating the adjusting ring 36 relative to the housing part 10, a specific axial position of the shift sleeve 32 in the housing part 10 can be set and thus the number of coupled friction discs 26 that are connected to the housing part 10 in a rotationally fixed manner can be selected.

[0052] The adjusting device 35 is also equipped with a locking device 49, by means of which the adjusting ring 36 and thus ultimately also the shift sleeve 32 can be locked in discrete axial positions relative to the housing part 10. The locking device 49 comprises, as can be seen in particular in Fig. 4, a ball 50 which is guided radially displaceably in a bore 51 in the carrier ring 41 and is preloaded via a spring element 52 relative to the adjusting ring 36 against the outer surface of the hollow cylindrical section of the housing part 10. The hollow cylindrical section of the housing part 10 is provided in this area with a locking contour 53 formed by a plurality of axially adjacent notches.In this case, the ball 50 of the locking device 49 then comes to rest in one of the notches of the locking contour 53 for each discrete, axial position of the shift sleeve 32, wherein the number of friction discs 26 that can be coupled and are connected in a rotationally fixed manner to the housing part 10 is changed in each of the discrete positions.

[0053] The different discrete positions of the shift sleeve 32 are shown in Figs. 5 to 7. Thus, in the first position shown in Fig. 5, only one of the friction discs 26 is connected in a rotationally fixed manner to the shift sleeve 32, while in the second position shown in Fig. 6, two of the friction discs 26 and in the third position shown in Fig. 7, even three of the friction discs 26 are each connected in a rotationally fixed manner to the housing part 10. This changes the number of active friction surfaces in each case, which also results in a corresponding change in the locking effect that can be achieved via the locking device 18.

[0054] By means of the inventive design of a limited-slip differential gear, it is thus possible to adapt a respective locking effect in a locking device with a simple structure.

[0055] Reference symbol

[0056] Limited-slip differential connection point

[0057] Junction

[0058] Connection point gearbox input gearbox output gearbox output differential housing flange sections

[0059] Housing part

[0060] Housing part

[0061] Interior

[0062] differential bolt

[0063] Balance gear Balance gear Output gear

[0064] Output gear Locking device Locking device Actuating device Pressure ring

[0065] Guide gearing Gearing

[0066] Friction disc package End plate Couplable friction discs Coupled friction discs Driving toothing Toothing

[0067] Friction linings Clutch profile Shift sleeve Driving teeth Engagement profile Adjusting device Adjusting ring Internal thread External thread Screw connection Engagement contour Support ring Contact shoulder Retaining ring Sliding disk Recesses Adjusting pin Recess Openings Locking device Ball Bore Spring element Locking contour

Claims

Patent claims 1. Limited-slip differential transmission (1), comprising three connection points (2, 3, 4) in the form of a transmission input (5) and two transmission outputs (6, 7), wherein at least one locking device (18, 19) is provided, each of which has an actuating device (20) and axially adjacent friction discs (26, 27), of which several are present as couplable friction discs (26) and at least one is present as a friction disc (27) permanently coupled to one of the connection points (2, 3, 4), wherein the friction discs (26, 27) can be placed axially against one another by the action of each actuating device (20), and thereby frictional couplings can be formed between the couplable friction discs (26) and the at least one permanently coupled friction disc (27), wherein the couplable friction discs (26) are each equipped with a coupling profile (31) and the at least one locking device (18, 19) each has a sliding element assigned to it,which is guided in a rotationally fixed and axially displaceable manner by another of the connection points (2, 3, 4), and wherein each sliding element can be brought into axial overlap with a different number of the connectable friction discs (26) by axial displacement and depending on its axial position, and can thereby be connected in a rotationally fixed manner to the overlapping, connectable friction discs (26) by a respective engagement in the respective coupling profile (31), characterized in that each sliding element is designed as an annular shift sleeve (32) which is arranged coaxially and radially adjacent to the friction discs (26, 27) and is each equipped with an engagement profile (34) at which the respective engagement in the respective coupling profile (31) takes place.

2. Limited-slip differential gear (1) according to claim 1, characterized in that each of the shift sleeves (32) is assigned an adjusting device (35) at which an adjusting movement can be initiated and thereby the axial displacement of each of the shift sleeves (32) can be brought about.

3. Limited-slip differential gear (1) according to claim 2, characterized in that each actuating device (32) has a carrier ring (41) which is arranged coaxially and axially overlapping with and radially adjacent to the respective shift sleeve (32) and in at least one recess (45) in each case an actuating pin (46) which, on the side of each of the respective shift sleeves (32), is engaged in a respective recess (47), wherein each of the respective carrier rings (41) executes an axial sliding movement when the adjusting movement is initiated and thereby axially entrains each of the respective shift sleeves (32) via the respective adjusting pin (46).

4. Limited-slip differential gear (1) according to claim 2 or 3, characterized in that each adjusting device (32) has an adjusting ring (36) which is rotatably guided by a screw connection (39) on the side of the other connection point (2) and into which the adjusting movement can be introduced as a rotary movement, wherein each screw connection (39) converts the adjusting movement introduced as a rotary movement into an axial displacement of the respective adjusting ring (36) relative to the other connection point (2).

5. Limited-slip differential gear (1) according to claim 3 and claim 4, characterized in that the respective one carrier ring (41) and the respective one adjusting ring (36) are arranged coaxially to one another, wherein the respective one carrier ring (41) is guided axially fixedly on the respective one adjusting ring (36).

6. Limited-slip differential gear (1) according to one of the preceding claims, characterized in that a locking device (49) is assigned to each shift sleeve (32), by means of which locking device each shift sleeve (32) can be locked directly or indirectly in discrete axial positions, wherein each discrete axial position is assigned an axial overlap of each shift sleeve (32) with an associated number of coupling friction discs (26).

7. Limited-slip differential gear (1) according to claim 6 and according to one of claims 2 to 5, characterized in that the respective locking device (49) is accommodated between the respective adjusting device (35) and the other connection point (2) and the respective adjusting device (35) locks in the respective sliding positions associated with the discrete axial positions of the respective shift sleeve (32) to the other connection point (2).

8. Limited-slip differential gear (1) according to one of the preceding claims, characterized in that the gear input (5) is formed by a differential housing (8) in which a differential gear set is accommodated, couplings of the differential housing (8) to output gears (16, 17) forming the gear outputs (6, 7) being established via the differential gear set.

9. Limited-slip differential gear (1) according to claim 8 and claim 5, characterized in that each shift sleeve (32) is guided in a rotationally fixed and axially displaceable manner via a respective driving toothing (33) on an inner surface of a respective wooden cylindrical section of the differential housing (8), wherein each screw connection (39) is formed by an external thread (38) on an outer surface of each wooden cylindrical section of the differential housing (8) and an internal thread (37) which is guided on the respective external thread (38) and which is formed on the respective adjusting ring (36), and wherein each carrier ring (41) is guided radially outwardly of the wooden cylindrical section of the differential housing (8) in each adjusting ring (36) and each adjusting pin (46) is guided radially through an opening (48) in the wooden cylindrical section.

10. Limited-slip differential transmission (1) according to one of the preceding claims, characterized in that the respective actuating device (20) acts automatically on the respective friction discs (26, 27) of the at least one locking device (18, 19) as a function of a load introduced at the transmission input (5) or as a function of a differential speed between the transmission outputs (6, 7).

11. Limited-slip differential gear (1) according to claim 8 or 9 and according to claim 10, characterized in that the respective actuating device (20) of the at least one locking device (18, 19) is formed by a respective pressure ring (21) which is movable axially against the respective friction discs (26, 27) of the at least one locking device (18, 19) via an element of the differential gear set as a function of the load introduced at the transmission input (5).

12. Limited-slip differential gear (1) according to one of the preceding claims, characterized in that two locking devices (18, 19) are provided, wherein in each case one locking device (18, 19) serves to couple the transmission input (5) to one of the transmission outputs (6, 7).

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