Form-locking and friction-locking clutches

Abstract

The invention relates to a normally closed clutch (2), which comprises a first rotating element (10) and a second rotating element (12), the second rotating element being movable in an axial direction relative to the first rotating element between an engaged position and a disengaged position, wherein a first spring device (26) is provided, which loads the second rotating element (12) into an engaged position with a first spring force, in which a form-locking connection exists between the two rotating elements, wherein a friction clutch (34) and a second spring device (44) assigned thereto are provided, the second spring device loads the friction clutch into a closed position with a second spring force, wherein the second spring force is greater than the first spring force, wherein a disengagement element (60) is provided, by which the friction clutch (34) can be disengaged, and the disengagement element is arranged so that the first spring device, the second rotating element, the second spring device and the disengagement element are connected in series.

Description

Technical Field

[0001] The invention relates to a normally closed clutch which can be used for a drive unit. An example of such a unit is an air compressor which takes on the task of supplying compressed air to a brake system of a commercial vehicle. Background Art

[0002] When the clutch is open, the unit can be disconnected from the drive assigned to it. This is done, for example, for efficiency reasons when the unit is not required to be operated.

[0003] If the unit needs to be coupled to the drive for safety reasons, the clutch is designed to be normally closed ("NC"). For example, if there is a control failure of the mechanism that can open the clutch, the clutch will return to the closed state anyway. This ensures that in the above example, the air compressor is also operated in the event of a fault, so that sufficient pressure is available to actuate the vehicle brakes.

[0004] An example of a normally closed clutch is a friction clutch, which is preloaded into the closed position by means of a spring assembly. To decouple the unit from its drive, the friction lock is released. Conversely, if the unit is to be coupled to its drive, the friction lock is reestablished, wherein the rotational speed of the unit and the rotational speed of the drive are automatically synchronized in a friction-locking manner.

[0005] However, in the case of friction clutches, there is the risk that, due to high rotational non-uniformities and load variations on the auxiliary units, highly dynamic overloads may occur, which may lead to slipping of the friction clutch. In extreme cases, this may lead to the unit not being (anymore) driven in the desired manner and, in the above example, no longer being able to provide sufficient gas pressure for actuating the vehicle brakes. Summary of the invention

[0006] The object of the present invention is to provide a clutch by which a machine set can be driven reliably in all situations and can be opened and closed under load.

[0007] To achieve this object, according to the invention, a normally closed clutch is provided, which has a first rotating element and a second rotating element, which is movable in the axial direction relative to the first rotating element between an engaged position and a disengaged position, wherein a first spring device is provided, which loads the second rotating element into an engaged position with a first spring force, in which there is a positive connection between the two rotating elements, wherein a friction clutch and a second spring device assigned to the friction clutch are provided, which loads the friction clutch into a closed position with a second spring force, wherein the second spring force is greater than the first spring force, wherein a disengagement element is provided, by which the friction clutch can be disconnected, and the disengagement element is arranged so that the first spring device, the second rotating element, the second spring device and the disengagement element are connected in series. The invention is based on the following basic idea: combining a positive connection with a friction connection. The friction connection is used to transmit a driving torque in normal conditions. Only when a (temporary) torque greater than the torque that can be transmitted via the friction connection acts, the excess torque is transmitted by means of the positive connection. This reliably prevents the friction clutch from slipping. In addition, the friction clutch ensures that the positive-locking clutch remains unloaded when the clutch is disengaged and that the rotational speeds of the two rotating elements are synchronized with each other when the clutch is switched from the disengaged state to the closed state. Due to the spring device, the clutch as a whole is loaded into the closed state (with both a closed positive-locking connection and a closed friction clutch), thereby achieving a failsafe.

[0008] The form-locking connection can be formed by a claw clutch, so that it can be produced in a mechanically simple manner.

[0009] It can be provided that the dog clutch has an internal toothing on one of the rotating elements and a complementary external toothing on the other rotating element. Depending on the corresponding structural conditions, these toothings can be designed integrally with the corresponding rotating element or can be arranged on a separate component, which is then connected to the corresponding rotating element in a rotationally fixed manner.

[0010] The first spring device is preferably formed from a plurality of helical springs, so that a large displacement path and (due to the plurality of helical springs) also redundancy is achieved.

[0011] The second spring device is preferably formed by a disc spring assembly, by means of which a very high spring force can be provided with little effort.

[0012] According to one embodiment of the invention, it is provided that the friction clutch has at least one conical friction surface, so that high friction torques can be transmitted due to the resulting wedge effect.

[0013] The friction clutch can also comprise a multi-faceted friction system, so that despite a short axial installation space, a high friction torque is achieved, in particular when using a plurality of conical friction surfaces that are simultaneously loaded with spring forces.

[0014] According to one embodiment of the invention, the friction clutch includes a locking device. The locking device ensures that the positive locking connection can only be engaged when the rotational speeds of the two rotating elements are synchronized with each other. Accordingly, the control or regulation technology expenditure for actuating the friction clutch can be minimized.

[0015] When a locking device is used, the friction clutch comprises a synchronizer ring with a blocking chamfer that can interact with a locking chamfer on one of the rotating elements. This design is generally known from synchronizers for control transmissions of motor vehicles and is therefore a proven design.

[0016] The disengagement element of the friction clutch is preferably equipped with an actuating piston, which together with the disengagement housing forms a disengagement device. The disengagement device can be actuated pneumatically or hydraulically so that it disengages the friction clutch when necessary.

[0017] The first of the rotating elements can be a clutch pot, which is provided with axially extending entraining fingers, wherein a toothed disk is accommodated between the entraining fingers, which is part of the form-locking connection, and a plurality of entraining projections of a friction ring of the friction clutch engage between the entraining fingers. The entraining fingers can be used to produce a geometry that forms the desired rotationally fixed connection between the toothed disk and the clutch pot on the one hand and between the friction ring and the clutch pot on the other hand.

[0018] The second rotating element can be designed as a wheel hub, on which an outer friction disk and an inner friction disk are accommodated in a non-rotatable but axially movable manner relative to each other, and a friction ring is engaged between the outer friction disk and the inner friction disk. By this design, the friction clutch can be assembled on the wheel hub very compactly.

[0019] The second spring device preferably acts between the wheel hub and the inner friction disk, so that the spring force required to close the friction clutch is fully supported on the wheel hub.

[0020] The first spring device is supported on the hub and biases the hub into a closed position relative to the clutch cup.

[0021] In this case, the support for the first spring device can be located on the shaft on which the hub is arranged axially displaceably but non-rotatably, so that no external support for the first spring device is required.

[0022] According to one design, a decoupler for the friction clutch is provided, which is fixedly arranged on the shaft in the axial direction. Therefore, all actuating forces of the clutch are supported in the closed assembly.

[0023] The clutch cup is preferably rotatably mounted on the shaft by means of rolling bearings, so that its position relative to the hub is precisely defined. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The invention is described below with reference to two embodiments shown in the accompanying drawings.

[0025] Figure 1 shows a cut-away partial view of a clutch according to a first embodiment in a closed state;

[0026] Figure 2 shows a perspective sectional view of a clutch according to a first embodiment in a closed state;

[0027] Figure 3 Shows Figure 2 Another perspective cross-sectional view of the clutch shown;

[0028] Figure 4 shows a cross-sectional view of a clutch according to a first embodiment in a closed state, wherein some components are not shown for the sake of greater clarity;

[0029] Figure 5 Shown with Figure 4 A corresponding view in which the clutch is in a neutral state;

[0030] Figure 6 Shows Figure 4 The clutch is in a disengaged state;

[0031] Figures 7a to 7c The spring load deformation curves of the clutch according to the present invention in different states are shown;

[0032] Figure 8 shows a perspective sectional view of a clutch according to a second embodiment in an intermediate state;

[0033] Fig. 9 shows a cross-sectional view of a clutch according to a second embodiment in a disengaged state;

[0034] Fig.10 shows details of a clutch according to a second embodiment in a disengaged state;

[0035] Fig.11 shows a cross-sectional view of a clutch according to a second embodiment in an intermediate state;

[0036] Fig.12 shows a detail of a clutch according to a second embodiment in an intermediate state;

[0037] Fig.13 shows a perspective view of a clutch according to a second embodiment in an intermediate state;

[0038] Fig.14 The clutch according to the second embodiment is shown in the intermediate state. Fig. 9 The corresponding view;

[0039] Fig.15 Shows something like Fig.10 A view of the clutch in a neutral position;

[0040] Fig.16 Shown with Fig. 9 corresponding view, in which the clutch is in a closed state;

[0041] Fig.17 Shown with Fig.10 Corresponding view, in which the clutch is in the closed state. DETAILED DESCRIPTION

[0042] exist Figure 1 In FIG. 2 , a clutch 2 is shown which, in the closed state, serves to transmit a torque originating from a drive plate 6 to a shaft 4 (here the shaft of the compressor). The torque can in principle also be transmitted in the opposite direction.

[0043] When the clutch 2 is open, the two members 4 , 6 are decoupled from each other and no torque is transmitted (except for possible residual drag torque).

[0044] The clutch 2 has two rotating elements 10, 12, one of which is designed here as a clutch cup 10 and the other as a hub 12. The clutch cup 10 is supported on the shaft 4 by means of a rolling bearing 8 so as to be freely rotatable.

[0045] The hub 12 is relatively non-rotatable in the circumferential direction (see in particular Figure 2 and 3 The spline shaft toothing 13 in the embodiment of the present invention is supported on the shaft 4 in a manner that allows displacement in the axial direction.

[0046] exist Figures 1 to 4 In the state shown, there is a positive locking connection between the clutch cup 10 and the wheel hub 12, so that they are connected to each other in a rotationally fixed manner. The positive locking connection is formed by a dog clutch, which has teeth on the clutch cup 10 and the wheel hub 12 that engage with each other.

[0047] In particular, the wheel hub 12 has an external toothing 14 which is designed in one piece with a flange 16 of the wheel hub 12 .

[0048] The clutch cup 10 has an internal toothing 18 which is formed on the inner circumference of a toothed disk 20. The toothed disk is connected to the clutch cup 10 in a rotationally fixed manner.

[0049] The toothing 14 , 18 can be provided with a roof toothing or similar inclined surfaces to facilitate axial engagement.

[0050] The toothed disk 20 has a plurality of entraining projections 22 on its outer peripheral edge, which are each arranged in the intermediate spaces between adjacent entraining fingers 24 which extend in the axial direction starting from the outer periphery of the clutch cup 10 .

[0051] In this case, the torque is transmitted via a positive fit from the clutch cup 10, the entraining projection 22, the inner toothing 18, the outer toothing 14 and the hub 10 to the shaft. In principle, the torque can also be transmitted in the opposite direction. In the case of load changes or dynamic load fluctuations, a reversal of the torque transmission direction can also occur.

[0052] exist Figures 1 to 4 In the illustrated state with a positive fit between the hub and the clutch pot, the hub 10 is loaded by a first spring arrangement, which is formed here by a plurality of helical springs 26. The helical springs 26 are accommodated over most of their length in blind holes 28 in the hub 12, which are supported on the bottom of the hub. The opposite ends of the helical springs 26 are supported on a bearing disk 30, which is fixed in the axial direction to the shaft 4 by means of a fixing ring 32.

[0053] The coil spring 26 therefore presses the hub 12 away from the bottom of the clutch cup 10 , ie out of the clutch cup 10 into a position in which the outer toothing of the hub 12 engages with the inner toothing of the clutch cup 10 .

[0054] A part of the clutch 2 is also a friction clutch 34 which acts between the clutch cup 10 and the wheel hub 12 .

[0055] The friction clutch 34 can be designed in principle in different structural ways. The friction clutch is used to transmit torque between two rotating elements 10, 12. The friction clutch 34 is also used to synchronize the rotational speeds of the two rotating elements 10, 12 when a rotationally fixed connection is to be established between the two rotating elements 10, 12 and there is a rotational speed difference between the two components. One application case for this is that the clutch 2 is used to drive a compressor, which is to be switched on or off during operation.

[0056] In the embodiment shown, the friction clutch 34 has a plurality of conical friction surfaces. Specifically, a multi-faceted friction system is used.

[0057] On the wheel hub 12 side, the friction clutch 34 has an outer friction plate 36 and an inner friction plate 38 .

[0058] The two friction disks 36 , 38 are arranged on the hub 12 in a rotationally fixed manner (see splined shaft toothing 40 ).

[0059] The outer friction disk 36 is fixed to the hub 12 in the axial direction by means of a fixing ring 42. The inner friction disk 38 is pressed in the axial direction onto the outer friction disk 36 by a second spring device. In the embodiment shown, the second spring device is composed of a group of a plurality of disc springs 44. They are supported between the flange 16 of the hub 12 and the inner friction disk 38.

[0060] The force applied in the axial direction by the disc spring pack 44 is much greater than the force provided in the axial direction by the coil spring 26 .

[0061] The friction clutch has, on the clutch cup 10 side, a friction ring 46 which is connected to the clutch cup 10 in a rotationally fixed manner and extends into the space between the two friction disks 36 , 38 .

[0062] For the rotationally fixed connection between the friction ring 46 and the clutch cup 10 , the friction ring 46 has on its outer circumference a plurality of entrainment projections 48 which extend between the entrainment fingers 24 of the clutch cup 10 .

[0063] In order to increase the number of effective friction surfaces, the outer friction disk 36 has an auxiliary friction disk 37 coupled thereto in a rotationally fixed manner, and the friction ring 46 has an auxiliary friction ring 47 coupled thereto in a rotationally fixed manner. Thus, there are four pairs of friction surfaces in total.

[0064] The friction clutch 34 is loaded by the disc spring package 44 into a closed position in which the inner friction disk 38 is pressed in the direction of the outer friction disk 36 , so that the friction ring 46 and the auxiliary friction ring 47 as well as the auxiliary friction disk 37 are clamped between them.

[0065] In order to disengage the friction clutch 34 , a clutch disconnector 50 is provided, which is mounted in a housing that is fixed in the axial direction.

[0066] The coupler 50 has a coupler housing 52, in which an actuating piston 54 is arranged. A pressure chamber 56 is formed between the actuating piston and the coupler housing, to which pneumatic or hydraulic pressure can be applied, so that the actuating piston 54 is loaded toward the friction clutch 34. This movement can be transmitted via a rolling bearing 58 to a coupling element 60, which is designed here as a ring with a coupling finger 62.

[0067] The disengagement finger 62 extends through a suitable opening in the outer friction disk 36 so that it bears against the inner friction disk 38 and can move it away from the outer friction disk against the action of the disc spring package 44 .

[0068] exist Figures 1 to 4 , the clutch 2 is shown in a completely closed state, in which there is both a positive locking connection between the clutch pot 10 and the wheel hub 12 and a friction lock of the closed friction clutch 34. In this state, a torque can be transmitted between the two rotating elements 10, 12, wherein the torque is transmitted by the positive lock when the torque that can be transmitted by the friction clutch is exceeded. No external control is required to maintain this state, because the spiral spring 26 and the disc spring 44 ensure that the positive locking connection is maintained and the friction clutch 34 remains closed.

[0069] When the clutch 2 is to be disconnected, the Figure 5 The disengagement element 60 is moved in the direction of the arrow P, thereby firstly moving the hub 12 relative to the clutch pot 10 in the axial direction, thereby releasing the form-locking connection; the flange 16 of the hub 12 no longer extends in the same plane as the toothed disk 20.

[0070] In this state, the hub 12 rests on the support disk 30 .

[0071] In this intermediate state, the friction clutch 34 is still closed. This is because the axial force provided by the first spring device (helical spring 26) is less than the force provided by the second spring device (disc spring set 44). As long as the helical spring can yield, the disc spring 44 can be considered rigid. Therefore, any torque between the clutch pot 10 and the wheel hub 12 continues to be transmitted via the friction clutch 34, while the form-locking connection can be released without force.

[0072] When the force applied to the disengagement element 60 in this state is further increased, the restoring force of the disc spring group 44 is also overcome, whereby the inner friction disk 38 moves away from the outer friction disk 36 in the axial direction. As a result, the friction clutch 34 is disconnected (see Figure 6 ). In this state, the torque flow between the clutch pot 10 and the wheel hub 12 is interrupted.

[0073] exist Figures 7a to 7c , the process of clutch 2 being disconnected is schematically shown.

[0074] exist Figure 7a In FIG. 4 , the clutch 2 is shown in the closed state. It can also be seen that starting from the shaft 4 (specifically from the support plate 30), the first spring device 26, the hub 12 with the flange 16, the second spring device 44, the inner friction plate 38 and the disengagement element 60 (by the operating force F B Indicates) series setting.

[0075] The stiffness of the second spring device 44 is much greater than the stiffness of the first spring device 26. In addition, the corresponding spring preload is such that the preload force provided by the second spring device in the initial state is greater than the preload force of the first spring device.

[0076] To disengage the clutch 2, first an actuating force or a release force F is applied. B , which is greater than the force F applied by the first spring device 26 1 Since the force of the second spring device is greater than the force of the first spring device, the second spring device can be assumed to be a rigid direct drive element, which results in the friction clutch 34 remaining closed while the hub 12 is moved relative to the clutch pot 10. Correspondingly, the positive locking connection between the flange 16 and the toothed disk 20 is disconnected.

[0077] When in the second step a spring force F is then applied which is greater than the spring force F provided by the second spring device 2 F B When the inner friction plate 38 is away from the outer friction plate 36, the friction clutch 34 is disconnected (see Figure 7c ).

[0078] In order to close the clutch 2 from the disengaged state, the disengagement force applied to the disengagement element 60 is first reduced to such an extent that it is less than the spring force of the second spring device. This has the effect that the disc spring set 44 can relax (and correspondingly the friction clutch 34 is closed), while the helical spring 26 remains compressed and the wheel hub 12 remains in contact with the support plate 30. Due to the closed friction clutch 34, the rotational speeds of the wheel hub 12 and the clutch pot 10 are equal to each other (if there is a rotational speed difference).

[0079] When the friction clutch 34 is completely closed and the disengagement force drops below the force applied by the spiral spring 26, the spiral spring 26 can move the hub 12 in the axial direction (to the right in the drawing), whereby the external toothing 14 on the flange 16 engages in the internal toothing 18 of the toothed disc 22. This reestablishes the form fit. It is ensured that the clutch 2 ensures a reliable torque transmission in this state even when the torque to be transmitted is higher than the torque that can be transmitted by the friction clutch 34 in a friction-locking manner.

[0080] In particular, the clutch engagement process can be achieved in a timed controlled manner (by appropriately venting the pressure chamber 56 via a diaphragm or a throttle position so that the friction clutch 34 automatically closes slowly enough to synchronize the rotational speeds of the two rotating elements 10, 12) or actively controlled while monitoring the rotational speeds of the two rotating elements.

[0081] exist Figures 8 to 17 A second embodiment of a clutch is shown in . The same reference numerals are used for the components known from the first embodiment and reference is made to the above description in this respect.

[0082] The difference between the first and second embodiments is that in the second embodiment a so-called locking device is used, ie the engagement of the form-locking connection is mechanically prevented before the rotational speeds of the two rotary elements 10 , 12 are equal to one another.

[0083] Such locking devices are known in principle from manual transmissions of motor vehicles and are used to synchronize the rotational speed of an escape wheel designed as a freewheel with the rotational speed of a transmission shaft on which the escape wheel is arranged. The locking device is used to prevent a positive locking (claw clutch) from engaging as long as the shafts to be coupled have different rotational speeds.

[0084] If especially in Fig.10 As can be seen in FIG. 2 , a locking chamfer 70 is provided on the side of the entrainment finger 24 , which extends at an angle of approximately 30° to the axial direction.

[0085] The blocking chamfers 72 provided on the entraining projections 48 of the friction ring 46 can each interact with the locking chamfers 70. The friction ring 46 thus acts similarly to a synchronizer ring having locking teeth.

[0086] Due to the positions of the locking chamfer 70 and the blocking chamfer 72, the clutch 2 in this embodiment is used to transfer torque from the clutch pot 10 to the wheel hub 12, wherein the clutch pot 10 of the clutch 2 is along the Fig.13 Rotate in the direction of arrow R.

[0087] The clutch 2 is disconnected in the same manner as in the first embodiment.

[0088] exist Fig. 9 and 10 , the clutch 2 is shown in a completely disengaged state.

[0089] If the disengagement force on the disengagement element 60 is reduced starting from this state, the clutch reaches Figures 11 to 15 Status shown.

[0090] Depending on the rotation direction of the clutch pot 10, the driving projection 48 of the friction ring 46 rests with its blocking chamfer 72 on the locking chamfer of the driving finger 24 of the clutch pot 10. If the rotation speed of the hub 12 is less than the rotation speed of the clutch pot 10, the blocking chamfer 72 is loaded toward the locking chamfer 70, thereby generating a resistance to the axial movement of the friction ring 46 according to the inclination angle of the two chamfers (see Fig.11 The resistance W shown in ).

[0091] The axial force originating from the disc spring group 44 acts on the entire friction system. That is, all friction rings are loaded with axial force. The resistance W acting through the locking geometry (caused by the torque of the friction system) opposes the restoring force of the compression spring located in the wheel hub. Since the resistance W is greater than the spring force of the compression spring, the claw teeth are prevented from engaging. Based on the total friction torque from the friction group, the angle of the locking chamfer can be designed to be relatively flat. If the friction torque in the friction system decreases (for example, after the rotation speed of the shaft is equal), the compression spring in the wheel hub can push the friction system axially past the locking teeth (locking device), and the claw teeth can engage, for example, when the friction system slips.

[0092] Thus, until the synchronizer ring comes to rest against the locking chamfer, the sequence is identical to variant 1. The pressure or switching force from the disconnector decreases. The disc spring assembly completely closes the friction system. When the axial force decreases further, the inner spring assembly (compression spring) begins to move the hub in the direction of the claw toothing. The synchronizer ring comes into contact with the locking chamfer and the movement stops. If speed equality is achieved and the friction system with the synchronizer ring is, for example, flipped to the other side (without locking chamfer), the inner spring assembly can push the disconnector and the friction system axially past the locking chamfer. The claws can then engage, for example, due to slippage of the friction system.

[0093] In order to allow the friction surface 76 to also participate in the synchronization, the dimensions of the components involved are selected so that when the locking chamfer 70 and the blocking chamfer 72 interact with each other, the hub 12 no longer rests on the support disk 30, but there is a small gap a (see Fig.11). This gap ensures that the supporting force applied by the disc spring assembly to the flange 16 on the left side acts on the outer friction disk 36 via the hub 12 and the fixing ring 42, and this supporting force ensures that the friction surface 72 also transmits the torque required for synchronization.

[0094] If there is no gap a, the spring force from the disc spring group can be supported on the shaft or the bearing plate (Wiederlagerscheibe) 30. As a result, no axial force acts on the friction ring 36, so that the friction torque in the friction system will be reduced to only one friction surface ( Fig.11 For the locking function, however, the full friction torque is required in a flat locking geometry (chamfer).

[0095] When the rotational speeds of the clutch pot 10 and the hub 12 are equal to one another, no drag torque is applied to the friction ring 46 and therefore no (or at most negligible) circumferential forces act between the locking chamfer 70 and the blocking chamfer 72. The spring assembly of the compression spring located in the hub pushes the friction system past the locking chamfer. The starting point in the compressor clutch is that by briefly tilting the entraining cam 48 of the synchronizer ring in the carrier 10 to the opposite side (without the locking chamfer), the spring assembly 26 can axially move the friction system until the claw teeth are in contact or directly engaged, i.e. the hub 12 reaches an axial position in which a positive fit is established between the outer toothing 14 on the hub 12 and the inner toothing 18 of the clutch pot 10.

[0096] The advantage of the second embodiment is that the pressure chamber 56 of the decoupler 50 does not necessarily have to be vented in a controlled manner in order to thereby achieve the desired synchronization of the rotational speeds, but rather, due to the presence of the locking device, a positive lock can only be achieved when the rotational speeds are synchronized. It is therefore possible to suddenly vent the pressure chamber 56. Alternatively, the locking device can be regarded as a safety measure which enables the engagement of the dog clutch in the event of a sudden failure of the decoupler 50 only when the rotational speeds of the clutch pot 10 and the wheel hub 12 are equal.

[0097] The clutch 2 described is particularly suitable for driving an air compressor which is used in the compressed air supply of the brake system of a commercial vehicle. Since the clutch is designed as a normally closed clutch (NC clutch), the clutch assumes a state in which the friction clutch 34 is closed and the dog clutch (composed of the toothing 14, 18) is engaged when the decoupler 50 fails. This state is also assumed when the friction linings of the friction clutch 34 are worn to such an extent that they can no longer transmit the desired torque.

[0098] Depending on the structural boundary conditions, the friction clutch 34 can be designed to transmit only the rated torque, while the dynamic load peak is transmitted via the claw clutch. Optionally, the friction clutch 34 can also be designed to transmit the entire load torque spectrum of the driven unit.

[0099] The friction clutch 34 can also be dimensioned in such a way that it can only transmit the torque for synchronizing the driven unit at the operating speed, whereas the dynamic setpoint torque of the unit occurring during operation must be transmitted via the claw clutch.

[0100] Can be provided: in the case of a fault, the valve for operating the disconnect 50 is introduced into a switching position in which the disconnect 50 can no longer be actuated. In this case, the clutch 2 will remain permanently in the closed state, which corresponds to a state with maximum operational safety.

[0101] A play can be provided between the toothings 14, 18 in the circumferential direction, which play is greater than the play in the friction clutch 34. This has the effect that the collisions caused by the play in the dog clutch are reduced by the frictional engagement of the friction clutch 34. Optionally, it can be provided that the play of the dog clutch is less than or equal to the play in the friction clutch 34. This has the effect that the positive connection reduces microslips in the friction system in the event of dynamic overload.

[0102] It is also possible to design the dog clutch to be play-free, which is particularly suitable for coupling units that are very strongly excited to vibration.

Claims

1. A normally closed clutch (2), comprising a first rotating element (10) and a second rotating element (12), wherein the second rotating element is movable in an axial direction relative to the first rotating element (10) between an engaged position and a disengaged position, wherein: A first spring device (26) is provided, which first spring device loads the second rotating element (12) into the engagement position with a first spring force, in which a positive connection exists between the two rotating elements (10, 12), wherein a friction clutch (34) and a second spring device (44) assigned to the friction clutch are provided, the second spring device (44) loads the friction clutch (34) into the closed position with a second spring force, wherein the second spring force is greater than the first spring force, wherein a disengagement element (60) is provided, by which the friction clutch (34) can be disengaged, and the disengagement element (60) is arranged so that the first spring device (26), the second rotating element (12), the second spring device (44) and the disengagement element (60) are connected in series.

2. The clutch according to claim 1, characterized in that: The form-locking connection is formed by a dog clutch (14, 18).

3. The clutch according to claim 2, characterized in that: The dog clutch has an internal toothing (18) on one of the rotating elements (10) and a complementary external toothing (14) on the other rotating element (12).

4. The clutch according to claim 1, characterized in that: The first spring device is composed of a plurality of coil springs (26).

5. The clutch according to claim 1, characterized in that: The second spring device is composed of a disc spring group (44).

6. The clutch according to claim 1, characterized in that: The friction clutch (34) has at least one conical friction surface (74, 76).

7. The clutch according to claim 1, characterized in that: The friction clutch (34) comprises a multi-surface friction system.

8. The clutch according to claim 1, characterized in that: The friction clutch (34) comprises a locking device (60, 62).

9. The clutch according to claim 8, characterized in that: The friction clutch (34) includes a synchronizer ring (46) having a blocking chamfer (62) which can interact with a locking chamfer (60) on one of the rotating elements (10).

10. The clutch according to claim 1, characterized in that: The disconnecting element (60) is assigned an actuating piston (54), which together with the disconnecting device housing (52) forms the disconnecting device (50).

11. The clutch according to claim 1, characterized in that: One of the rotating elements is a clutch pot (10) which is provided with axially extending entraining fingers (24), wherein a toothed disc (20) is accommodated between the entraining fingers (24) and is part of a positive connection, and a plurality of entraining projections (48) of a friction ring (46) of a friction clutch (34) engage between the entraining fingers (24).

12. The clutch according to claim 11, characterized in that: One of the rotating elements (12) is a wheel hub, in which an outer friction disk (36) and an inner friction disk (38) are accommodated in a manner that is fixedly rotatable but axially movable relative to each other, and the friction ring (46) is engaged between the outer friction disk and the inner friction disk.

13. The clutch according to claim 12, characterized in that: The second spring device (44) acts between the wheel hub (12) and the inner friction disk (38).

14. The clutch according to claim 12, characterized in that: The first spring device (26) is supported on the wheel hub (12).

15. The clutch according to claim 12, characterized in that: A shaft (4) is provided on which the hub (12) is arranged axially displaceably but non-rotatably, wherein a support (30, 32) for the first spring device (26) is provided on the shaft (4).

16. The clutch according to claim 15, characterized in that: A disconnector (50) is fixedly arranged in the housing in the axial direction.

17. The clutch according to claim 15, characterized in that: The clutch cup (10) is rotatably supported on the shaft (4) by means of a rolling bearing (8).

Images