Torque transmission device

Abstract

A torque transmitting device comprises an idle gear arrangement (2) having a shaft (3) and an idle gear (4) mounted on and coupled to the shaft (3), the idle gear (4) coupled to the shaft (3) via a sliding friction clutch (7).

Description

Technical Field

[0001] The present invention relates to a torque transmission device including an idler gear arrangement having a shaft and an idler gear mounted on and coupled to the shaft. Background Art

[0002] The torque transmission device is used to transfer torque from the input side to anywhere on the output side. An example is a vehicle transmission for an internal combustion engine, for example a vehicle transmission in the form of a dual clutch transmission as described in DE 10 2013 104 468 A1. In this gear arrangement structure, each gear ratio is achieved by means of an idler gear and a fixed gear pair. The fixed gear is usually connected to the input shaft of the transmission, via which the torque is introduced, while the idler gear is initially mounted on the intermediate shaft alone without any torque transmission, i.e. the idler gear is not connected to the fixed gear in a non-rotatable manner. Using a suitable switching device, the idler gear required according to the required gear ratio is connected to the intermediate shaft in a non-rotatable manner, for which purpose the transmission teeth on the idler gear are usually short-circuited with the switching device by means of an internally toothed sliding sleeve. A synchronization unit with a friction cone is usually used to match the speed between the idler gear and the fixed gear.

[0003] When such torque transmission devices are used in the motor vehicle sector or in motor vehicle transmissions, the torque transmission device is part of a drive train, which usually includes side shafts extending to the driven wheels, a differential, a transmission and, if necessary, an electric drive motor. In particular, in the case of electrified drive trains, since no starting element is required, overloads can occur in the form of torque fluctuations, which are introduced into the drive train from the wheels in contact with the road. Such torque fluctuations, which can amount to approximately twice the maximum drive torque, usually occur during braking from higher vehicle speeds, wherein at least one braked wheel rolls over a speed bump and temporarily loses contact with the road, but immediately restores the contact. Such torque fluctuations persist in the drive train, which can lead to corresponding loads on the torque transmission elements in the drive train, including the torque transmission device or the fixed gear-idle gear arrangement.

[0004] The invention is based on the problem of disclosing a comparatively improved torque transmission device. Summary of the invention

[0005] In order to solve this problem, it is provided according to the present invention that in such a torque transmission device, the idler gear is coupled to the shaft via a sliding friction clutch.

[0006] According to the invention, the idler gear is connected to the shaft in a relatively non-rotatable manner to a certain extent via a sliding friction clutch. Therefore, the sliding friction clutch enables torque transmission during normal driving. However, if corresponding torque fluctuations occur, the sliding friction clutch disconnects the torque transmission on the idler gear side, which means that the idler gear rotates relative to the shaft. In this way, for example, such torque fluctuations introduced via wheel contact can be absorbed so that they do not burden the drive train. According to the invention, the intended combination of the sliding friction clutch into the bearing of the idler gear, i.e. into the arrangement structure of the fixed gear-idler gear pair, is combined with a corresponding engagement portion, which engages with the drive train and protects the drive train when excessive torque is applied. In this case, the idler gear mounted on the shaft side via appropriate radial and thrust bearings can be disconnected accordingly via the sliding friction clutch.

[0007] The sliding friction clutch incorporated on the side of the idler gear can act radially, which means that the friction torque is generated between two concentrically arranged radial partners, at least one of which is a friction pair. Alternatively, the sliding friction clutch can also act axially, i.e. the friction torque is generated between friction pairs that are mounted axially adjacent to each other.

[0008] In the case of a sliding friction clutch that acts in the radial direction, a clutch hub connected to the shaft in a non-rotatable manner and a friction sleeve can be provided, wherein the friction sleeve is seated on the outer peripheral surface of the clutch hub and is in radial friction contact with the inner peripheral surface of the idler gear. The friction torque is achieved here via radial friction contact between the idler gear on one side and the clutch hub on the other side, wherein a friction sleeve is installed between these two components to achieve friction contact. The cylindrical friction sleeve is in contact with the outer peripheral surface of the clutch hub, which is connected to the shaft in a non-rotatable manner. On the other hand, the friction sleeve is in contact with the inner peripheral surface of the idler gear, which means that there are two cylindrical friction surfaces connected via the friction sleeve. The friction sleeve itself, for example a single steel sheet component slotted in the axial direction, supports against the outer peripheral surface and the inner peripheral surface, and corresponding protrusions or similar protrusions are formed on the friction sleeve, so that there is a corresponding friction contact on both sides. The sliding torque is defined by the set support force, the contact radius, the number of friction contacts between the friction sleeve and the corresponding circumferential surface, and the friction value on the corresponding friction surface. This defines the corresponding starting torque or can be used to set the starting torque.

[0009] In a particular embodiment, the clutch hub can be L-shaped in cross section and can have a first leg provided with an inner toothing that meshes with an outer toothing on the shaft side, and a second leg having an outer peripheral surface, the second leg engaging in an annular groove of the idler gear radially delimited by the inner peripheral surface. This quasi-nested arrangement makes it easy to achieve a torque-resistant connection between the clutch hub and the shaft via a corresponding toothed connection, i.e., a spline. On the inner circumference of the first hub leg, radial splines are provided, which engage with corresponding radial splines provided on the outer circumference of the shaft side. The second leg of the L-shaped clutch hub extends into the annular groove on the idler gear, which means that the two are actually axially engaged with each other. The idler gear, which is quasi-C-shaped in cross section in this area, can be mounted on the shaft via its inner circumference using a corresponding radial bearing, while the annular groove forms a corresponding receiving groove for the clutch hub. The annular groove itself is delimited by the inner peripheral surface, which in turn represents a friction pair for the sliding friction clutch, while the other friction pair is provided by the outer peripheral surface of the idler gear. The friction sleeve itself is also located in an annular groove between corresponding circumferential surfaces separated by an annular gap accommodating the friction sleeve. In addition, corresponding radial and axial bearings of the idler gear on the one hand with the shaft and on the other hand with the clutch hub can be realized in a simple manner by means of a corresponding design.

[0010] In the above-described embodiment, a clutch hub is used, via which the torque is transmitted and which forms part of the clutch device. Depending on the specific application in which a torque transmission device of the type according to the invention is used, such a separate clutch hub can also be omitted in the case of lower requirements on NVH behavior (NVH = Noise, Vibration, Harshness). In this case, the sliding friction clutch can have only a friction sleeve seated on the outer circumferential surface of the shaft, wherein the idler gear in turn sits on the friction surface. In this case, the outer surface of the shaft itself therefore represents the friction pair, while the idler gear sits on the friction sleeve with its inner circumference. In addition to the clutch hub itself, in this case it is also possible to omit the radial bearing via which the idler gear is mounted on the shaft side in the above-described alternative design.

[0011] If a sliding friction clutch acting in the axial direction is used, the sliding friction clutch is preferably a multi-disk clutch with a disk pack having an outer disk connected to the idler gear in a non-rotatable manner and an inner disk connected to the clutch hub in a non-rotatable manner, the clutch hub being connected to the shaft in a non-rotatable manner, wherein the disk pack is axially preloaded, wherein the disk pack is axially supported. Here, the corresponding friction pair is formed by the alternatingly mounted outer and inner disks of the disk pack. In the case of the outer disks, these inner disks can be, for example, friction disks with a steel carrier with applied friction linings, while the inner disks are pure steel disks. Alternatively, both types of disks can also be steel disks, so that there is a steel-to-steel contact. In any case, the disk pack is supported by default, wherein the friction torque and therefore the starting torque when the clutch slips are adjusted via this support and, of course, also via the corresponding contact surfaces or surface dimensions and surface pressures and friction materials. Since the outer and inner disks are arranged as disk rings so as to be mounted axially adjacent to each other and form an axial disk pack, the outer and inner disks are inevitably also axially compressed, thereby generating an axially directed friction torque.

[0012] In a specific implementation of this variant of the invention, it can be provided that the idler gear has an axially open annular groove in which the disk package is accommodated and in which the clutch hub engages, the annular groove being L-shaped in cross section and having a first leg provided with an inner toothing which meshes with an outer toothing on the shaft side, and a second leg having an outer peripheral surface, wherein teeth engaging with the teeth of the outer disk are provided on the inner peripheral surface of the idler gear radially delimiting the receiving groove, and teeth engaging with the teeth of the inner disk are provided on the outer peripheral surface of the clutch hub. Thus, the outer disk is fixed to the idler gear side via a corresponding toothing engagement, i.e. a spline, while the inner disk is fixed to the clutch hub side via a corresponding toothing engagement, likewise a corresponding spline. A corresponding torque transmission takes place via this toothing engagement, which continues via friction contact until a maximum friction torque is reached, at which point slippage occurs.

[0013] For assembly reasons, it is advantageous if the idler gear is two-part and has a radially outer annular gear body and a radially inner support ring connected to the gear body, the gear body and the support ring delimiting an annular groove. This two-part design allows easy arrangement of the disk pack and the corresponding bearing, provided that they are present in the region of the annular groove. For final assembly, it is only necessary to screw the support ring tightly to the gear body.

[0014] As described, the disk set is axially supported. For this purpose, a spring element supporting the disk set is advantageously mounted on the idler gear. Via this spring element, the degree of friction and thus the friction torque, ie the torque at which the slipping friction clutch starts to slip, can be adjusted.

[0015] In this case, it can be advantageous to attach a clamping ring to the idler gear, via which the spring element is clamped axially against the disc pack. The spring element, for example a disc spring or a laminated disc spring, is pressed axially against the disc pack via the clamping ring. The clamping ring can be attached to the gear body using separate fastening screws. However, the clamping ring is preferably attached using connecting screws, which are also used to screw the support ring to the gear body.

[0016] Depending on the design of the torque transmission device, a corresponding number of radial bearings and thrust bearings is required. For example, in the case of a clutch hub that is provided for both a sliding friction clutch that acts in the radial direction and a sliding friction clutch that acts in the axial direction, the idler gear must be mounted radially on the shaft. An axial bearing or support for the idler gear relative to the shaft on one side is required, and an axial bearing or support for the clutch hub in the other axial direction, for example relative to an adjacent rolling bearing, via which the shaft is radially mounted. These bearings can be sliding bearings, needle roller assemblies, needle sleeves, needle roller bearings, ball bearings or a combination of these bearing types. However, it is also conceivable in principle to omit the combined bearings at one point or another and to provide instead, for example, a direct steel-to-steel contact between the idler gear and the shaft, since the corresponding relative movement of the two components to each other can only occur in a very short time or for a few turns. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be described below based on exemplary embodiments with reference to the accompanying drawings. The accompanying drawings are schematic representations, in which:

[0018] Figure 1 shows a schematic diagram of a first embodiment of a torque transmission device according to the present invention,

[0019] Figure 2 Shows Figure 1 A partial enlarged view of the sliding friction clutch area,

[0020] Figure 3 shows a perspective view of the friction sleeve, and

[0021] Figure 4 A second specific embodiment of the torque transmission device according to the invention is shown, which has an axially acting sliding friction clutch. DETAILED DESCRIPTION

[0022] Figure 1 as well as Figure 2 The partially enlarged view in FIG. 1 shows a torque transmission device 1 according to a first embodiment variant of the present invention. The torque transmission device comprises an idler gear arrangement 2, which comprises a shaft 3 and an idler gear 4 coupled to the shaft. The shaft 3 is supported via two radial bearings 5, 6 and is rotatably mounted on the surrounding structure.

[0023] The idler gear 4 itself is coupled or connected to the shaft 3 via a sliding friction clutch 7, which means that, on one side, a non-rotatable torque transmission connection is provided between the idler gear 4 and the shaft 3 at a certain torque. If a defined torque is exceeded, a relative movement of the idler gear 4 with respect to the shaft 3 is possible, so that the excessive torque is reduced.

[0024] The sliding friction clutch 7 includes a clutch hub 8 having an L-shaped cross section on one side. The clutch hub includes a first leg 9 having an internal toothing 10 that engages with an external toothing 11 provided on the shaft 3, so that a non-rotatable spline connection is provided between the clutch hub 8 and the shaft 3. The clutch hub 8 also includes a second leg 12 having an outer peripheral surface 13 that serves as a bearing and a friction pair for a friction sleeve described below.

[0025] The clutch hub 8 is engaged with the second leg portion 12 in a corresponding annular groove 14 formed on the idler gear 4 having a C-shaped cross section. Figure 2 . The clutch hub 8 is supported or mounted radially and axially relative to the idler gear 4 via a radial-thrust bearing 15, so that relative movement of the two parts with each other is possible. The idler gear 4 is in turn supported radially on the shaft 3 via a radial bearing 16 and axially on a corresponding shoulder of the shaft 3 via a thrust bearing 17. For the axial support on the other side, a further thrust bearing 18 is provided, via which the clutch hub 8 is axially supported on the rolling bearing 6, wherein the rolling bearing 6 is fixed in place on the shaft 3 via a circlip 19. The entire idler gear arrangement is therefore supported and mounted for rotation both radially and axially via the two thrust bearings 17, 18 as well as the radial bearing 16 and the radial-thrust bearing 15.

[0026] As described, the idler gear 4 has a corresponding annular groove 14, which is radially delimited to the outside by the inner peripheral surface 20 of the idler gear 4. The inner peripheral surface 20 forms two corresponding bearings and friction pairs together with the outer peripheral surface 13 of the clutch hub 8, which are connected via a friction sleeve 21 in contact with the two peripheral surfaces 13, 20. Figure 3The friction sleeve shown enlarged in FIG. 1 is provided with a groove 22 at one position, i.e. is slotted, so that the friction sleeve can be inserted into the corresponding annular gap between the two circumferential surfaces 13, 20 and is received in the groove under radial support. In the example shown, a plurality of elongated protrusions 23 protruding toward the outer circumference are formed on the friction sleeve 20, which are supported against the inner circumferential surface 20, while the inner circumferential surface 24 of the friction sleeve 21 is seated on the outer circumferential surface 13 of the clutch hub 8. The sliding torque provided by the friction sleeve 21 is defined on one side by the supporting force, via which the friction sleeve 21 is radially supported in the annular gap; the contact radius; the number of contact portions, i.e. the number of protrusions 23; and the friction coefficients at the contact surfaces, i.e. the corresponding circumferential surfaces 13, 20 and the friction sleeve 21 itself or the friction coefficients of the contact surfaces. Obviously, for example, the corresponding friction torque can be appropriately changed by simply changing the number of protrusions or the width of the protrusions or the protrusion height of the protrusions and thus changing the supporting force, that is, the torque that causes the sliding friction clutch 7 to start slipping can be set accordingly.

[0027] Due to the combination of the sliding friction clutch 7 according to the invention with the axial bearing and radial bearing of the idler gear 4 or the idler gear bearing arrangement, the idler gear 4 can rotate relative to the shaft 3 at sufficiently high torques, such as, for example, in the case of torque fluctuations, while transmitting or supporting the tooth forces from the conventional torque transmission in the pulling direction and the pushing direction. The radially supported friction sleeve 21 is a steel sheet sleeve, which has no radial play at all, wherein this play-free state persists even after the triggering event. Thus, any unbalance changes are minimized. During assembly and release, the concentricity deviations between the input side and the output side of the sliding friction clutch 7 are minimized by a low-tolerance radial fit.

[0028] Figure 4 A variant of the torque transmission device 1 according to the invention is shown, wherein the same reference numerals are used for the same components. Here too, an idler gear arrangement 2 is provided, which comprises a shaft 3 and an idler gear arrangement 4. The idler gear 4 comprises here a radially outer gear body 24 and a radially inner support ring 25 connected to the gear body, which is radially mounted on the shaft 3 via a radial bearing 26 and axially supported on a corresponding shaft shoulder via a thrust bearing 27. The shaft 3, which is in turn radially supported via two rolling bearings 5, 6, is also coupled to the idler gear 4 in a disconnectably coupled manner via a sliding friction clutch 7, wherein the sliding friction clutch 7 is here a multi-disk clutch acting in the axial direction.

[0029] The sliding friction clutch 7 again comprises a gear hub 8, which here is also of approximately L-shaped cross section and is also connected to the shaft 3 in a rotationally fixed manner via a first leg 9 by means of a corresponding spline connection. The second leg 10 of the clutch hub 8 extends into an annular groove 14 formed between the gear body 24 and the support ring 25, in which a disc set 28 is also received. The disc set 28 comprises a plurality of outer discs 29, each of which has an outer toothing, which in turn engages with a corresponding inner toothing on the inner circumference of the gear body 24, as is known from a multi-disc clutch. The disc set 28 also comprises a plurality of inner discs 30, each of which is toothed on the inner circumference and engages with a corresponding outer toothing on the second leg 10 of the clutch hub 8, as is also known from a multi-disc clutch. The outer discs 29 and the inner discs 30 are mounted alternately, wherein the disc set 28 is axially supported on the support ring 25. The outer disk 29 can be a friction disk with a steel ring carrier with a friction lining applied, for example, and the inner disk 30 can be a pure steel disk. Instead of using different outer disks 29 and inner disks 30, both can also be designed as simple steel disks, so that the friction contact is steel-to-steel contact.

[0030] On the other side of the disk package 28, a spring element 31, here a laminated disc spring, is mounted, which axially supports the disk package 28 and clamps it against the support ring 25, by means of which, in particular, the friction torque of the disk package 28 is adjusted. For this purpose, a support ring 32 is provided, which is fixed by means of suitable connecting screws 33, via which the gear body 24 is also axially screwed to the support ring 25, and which clamps the spring element 31 axially against the disk package 28. Here, the axial support of the left side is likewise provided via a further thrust bearing 34, via which the clutch hub 8 is axially supported on the rolling bearing 6. The clutch hub 8 is in turn supported against the support ring 25 via a thrust-radial bearing 35.

[0031] During normal operation, as long as the torque is less than the corresponding defined starting torque, this torque is transmitted via the permanently closed supported disk set 28. When the starting torque is reached, the sliding friction clutch 7 slips, so that the outer disk 29 rotates relative to the inner disk 30, although only for a short time and only for a few revolutions, until the applied torque is correspondingly reduced again. This means that the idler gear 4 can also rotate relative to the shaft 3. However, due to the combined thrust bearing and radial bearing, which can again be different types of bearings, there is also sufficient support for the tooth forces from the torque transmission in the pulling direction and the pushing direction.

[0032] In both design variants, the contact surfaces or friction surfaces can also be supplied with lubricant. The corresponding shaft 3 has a central hole 36, from which several transverse holes 37 branch out, which extend into the area of ​​the sliding friction clutch 7 and are open in this area, so that lubricant can be supplied from the inside.

[0033] As described in the exemplary embodiments, such torque transmission can be used in different applications. One example is incorporation into a transmission for an electrified drive train, in particular for a purely battery-powered vehicle or a hybrid vehicle, but the application is not limited thereto.

[0034] Reference numerals list

[0035] 1 Torque transmission device

[0036] 2 Idler gear arrangement

[0037] 3 Axis

[0038] 4 Connected idler gear

[0039] 5 Radial bearings

[0040] 6 Radial bearings

[0041] 7 Sliding friction clutch

[0042] 8 Clutch hub

[0043] 9 First Leg

[0044] 10Inner teeth

[0045] 11 External teeth

[0046] 12 Second Leg

[0047] 13 Peripheral surface

[0048] 14 Annular groove

[0049] 15 Radial-thrust bearing

[0050] 16 Radial bearings

[0051] 17 Thrust bearing

[0052] 18 Thrust bearing

[0053] 19 Circlip

[0054] 20 Circumferential surface

[0055] 21 Friction sleeve

[0056] 22 slots

[0057] 23 Protrusion

[0058] 24 Inner peripheral surface

[0059] 25 Support ring

[0060] 26 Radial bearings

[0061] 27 Radial bearing

[0062] 28 Plate Group

[0063] 29 External disk

[0064] 30 Internal disk

[0065] 31 Spring element

[0066] 32 Support ring

[0067] 33 Connecting screw

[0068] 34 Thrust bearing

[0069] 35 thrust-radial bearing

[0070] 36 Central hole

[0071] 37 Horizontal hole

Claims

1. A torque transmission device, comprising an idler gear arrangement (2), the idler gear arrangement having a shaft (3) and an idler gear (4) mounted on the shaft (3) and coupled to the shaft, characterized in that: The idler gear (4) is coupled to the shaft (3) via a sliding friction clutch (7).

2. The torque transmission device according to claim 1, characterized in that: The sliding friction clutch (7) acts in the radial direction or in the axial direction.

3. The torque transmission device according to claim 2, characterized in that: The radially acting sliding friction clutch (7) has a clutch hub (8) connected to the shaft (3) in a rotationally fixed manner and a friction sleeve (21), wherein the friction sleeve (21) is seated on the outer peripheral surface (13) of the clutch hub (8) and is in radial friction contact with the inner peripheral surface (20) of the idler gear (4).

4. The torque transmission device according to claim 3, characterized in that: The clutch hub (8) is L-shaped in cross section and has a first leg (9) and a second leg (10), the first leg being provided with an inner toothing (10) which meshes with an outer toothing (11) on a shaft side, the second leg having the outer peripheral surface (13) which engages in an annular groove (14) of the idler gear (4) which is radially delimited by the inner peripheral surface (20).

5. The torque transmission device according to claim 3, characterized in that: The sliding friction clutch (7) has a friction sleeve (21) seated on the outer peripheral surface of the shaft (3), wherein the idler gear (4) is seated on the friction sleeve (21).

6. The torque transmission device according to claim 2, characterized in that: The axially acting sliding friction clutch (7) is a multi-disc clutch comprising a disk package (28) having an outer disk (29) which is non-rotatably connected to the idler gear (4) and an inner disk (30) which is non-rotatably connected to a clutch hub (8), the clutch hub being non-rotatably connected to the shaft (3), wherein the disk package (28) is axially supported.

7. The torque transmission device according to claim 6, characterized in that: The idler gear (4) has an axially open annular groove (14), the disk set (28) is accommodated in the annular groove and the clutch hub (8) is engaged in the annular groove, the clutch hub is L-shaped in cross section and has a first leg (9) and a second leg (12), the first leg is provided with an inner tooth portion (10) which meshes with an outer tooth portion (11) on the shaft side, and the second leg has an outer peripheral surface, wherein teeth engaging with teeth of the outer disk (29) are provided on the inner peripheral surface of the idler gear (4) which radially defines the receiving groove (14), and teeth engaging with teeth of the inner disk (30) are provided on the outer peripheral surface of the clutch hub (8).

8. The torque transmission device according to claim 7, characterized in that: The idler gear (4) has a radially outer annular gear body (24) and a radially inner support ring (25) connected to the gear body (24), the gear body and the support ring defining the annular groove (14).

9. The torque transmission device according to one of claims 6 to 8, characterized in that A spring element (31) for axially supporting the disk set (28) is mounted on the idler gear (4).

10. The torque transmission device according to claim 9, characterized in that A clamping ring (32) is attached to the idler gear (4), via which the spring element (31) is axially clamped against the disk pack (28).

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