Clutch arrangement, and drive train unit

A clutch arrangement (3) with a friction clutch (8) and a dog clutch (9), wherein the output side of the friction clutch (8) and the output side of the dog clutch (9) are connectible to a flywheel mass device (4). A powertrain unit having such clutch arrangement is also described.

PRIORITY CLAIM

This is a U.S. national stage of application No. PCT/EP2018/061748, filed on May 8, 2018. Priority is claimed on German Application No.: 10 2017 209 398.6, filed Jun. 2, 2027, the content of which is incorporated herein by reference.

FIELD OF THE INVENTION

The invention is directed to a clutch arrangement with a friction clutch and a dog clutch.

BACKGROUND OF THE INVENTION

Clutch arrangements in which a friction clutch and a dog clutch are connected in parallel are known. The torque which cannot be transmitted by the friction clutch alone can then be transmitted via a dog clutch.

Further, in hybridized powertrains it is known to use the electric motor to start the internal combustion engine. This has the disadvantage that the electric motor must maintain a corresponding power reserve to enable changing from electric mode to hybrid mode or all-combustion engine mode. Accordingly, the electric motor must be designed to be more robust than would be necessary for all-electric motor operation.

In view of the foregoing, it is an object of the present invention to provide a clutch arrangement by which it is possible for the electric motor to make do without a power reserve or with a smaller power reserve for starting the internal combustion engine.

SUMMARY OF THE INVENTION

This object is met in that the output side of the friction clutch and the output side of the dog clutch are connectible to a flywheel mass device. Accordingly, the clutch device, as such, has only connection points and, after assembly, is connected to the flywheel mass device. The core of the invention is considered to consist in that the clutch arrangement, which can also be referred to as momentum starting clutch arrangement, is arranged upstream of the flywheel mass device. This makes it possible to stop the flywheel mass from turning because of the electric motor, which is why the flywheel mass device has high rotational energy. The internal combustion engine can be disconnected from the flywheel mass device during electric motor transmission via the momentum starting clutch. In order to start the engine, the momentum starting clutch is closed, which can result in large torque peaks. These can be absorbed by the parallel-connected friction clutch and dog clutch.

A hard engagement of the dog clutch is also prevented by the combination of a friction clutch and a positive-engagement clutch in the form of the dog clutch.

The dog clutch can advantageously have a jaw element with at least one input-side toothing and one output-side toothing. One of the toothings, preferably the input-side toothing, can be disengaged in order to achieve uncoupling.

The dog clutch can advantageously have a jaw element which can be supported on the flywheel mass device. Accordingly, the jaw element is constructed substantially hollow-cylindrically. During assembly of the clutch arrangement, the jaw element or a bearing sleeve to which the jaw element is attached or fitted can be connected to the flywheel mass device. In particular, the jaw element is axially movably supported.

The dog clutch can advantageously be formed as a radial dog clutch. Accordingly, the teeth of the toothing are arranged in radial direction.

The dog clutch preferably has a jaw element, and a radially outwardly directed projection by which the dog clutch can be actuated is arranged at the jaw element. An actuation of the dog clutch is accordingly effected by an axial displacement of the jaw element. The projection which is acted upon by an actuation device is provided for this purpose.

The jaw element can advantageously be preloaded in a preferred position by a preloading spring. A defined initial position of the dog clutch occurs as a result of the preloading spring. The preloading spring can advantageously act on the projection which is provided for actuating the dog clutch.

The friction clutch and/or the dog clutch can advantageously be formed as normally closed clutch. In the case of the dog clutch, the preloading spring then supports the jaw element in the closing direction.

The friction clutch can advantageously be formed as a dry clutch. However, in known combined clutches comprising both a friction clutch and a dog clutch, the friction clutch is formed as wet multiple-plate clutch.

While the friction clutch can also be formed as a dry multiple-plate clutch in principle, it is preferred that the friction clutch have a clutch disk. This clutch disk is advantageously arranged on the input side.

Accordingly, the momentum starting clutch arrangement has an opposite construction in contrast to conventional starting clutches. In starting clutches having only a dry friction clutch, the clutch disk is usually connected to the transmission input shaft. It is accordingly arranged on the output side of the clutch. The clutch disk can preferably be connected to the crankshaft via a hub. At least one elastic element, particularly tangential leaf springs, can advantageously be located between the hub and the clutch disk.

The friction clutch can preferably have a pressure plate which is arranged on the output side. This is provided when the clutch disk is arranged on the input side.

The clutch arrangement can advantageously have a counter pressure plate. In known starting clutches, a flywheel or dual mass flywheel is used as counter pressure plate. This is impossible in the described construction because the flywheel mass device lies on the output side of the clutch arrangement and therefore cannot be part of the clutch input.

The counter pressure plate is advantageously connected to a housing portion of the clutch arrangement so as to be fixed with respect to rotation relative to it. Further preferably, the counter pressure plate can be supported on the input side of the clutch arrangement. In particular, the counter pressure plate can be supported on the input-side hub of the clutch arrangement. To this end, a rolling element bearing is preferably located between the hub and the counter pressure plate. Accordingly, a closed clutch module is obtained which is connectible in a simple manner to the crankshaft on one side and to the flywheel mass device on the other side.

The friction clutch and the dog clutch can preferably have a common actuation device. When the clutch arrangement is used as momentum starting clutch, the friction clutch and the dog clutch are always used simultaneously. Therefore, it is advantageous to use an individual actuation device by which both clutches can then be actuated simultaneously. Accordingly, in normally closed clutches they are released jointly. As a result of the joint actuation, control of the clutch arrangement is facilitated and, further, component parts can be saved.

In an advantageous manner, the actuation device can first actuate the friction clutch in closing direction. This makes it possible to operate the clutch arrangement in slip mode before the dog clutch is engaged. Conversely, when opening, the dog clutch is disengaged first.

The friction clutch and/or the dog clutch can advantageously have an actuation device which actuates by pressure oil. Accordingly, the actuation is hydraulic, while the clutches of the clutch arrangement are both dry clutches in a preferred configuration. The dog clutch is always a dry clutch; the friction clutch is a dry clutch in the preferred embodiment form.

In an advantageous matter, the pressure oil can be provided through a transmission pump. In this way, the actuation of the clutch arrangement can be realized without additional component parts aside from the piston, supply line and a valve.

The clutch arrangement can preferably have an actuation device with an actuation piston which actuates both the friction clutch and the dog clutch. In particular, the actuation piston can be formed annularly, and pot-shaped walls extend in radial direction radially inwardly as well as radially outwardly. Accordingly, an actuation of the friction clutch and of the dog clutch can be carried out simultaneously through movement of the ring. By different heights or adjustments of the heights of the walls of the actuation piston, it can also be determined whether or not the friction clutch and the dog clutch are actuated simultaneously or the time interval within which the clutches are actuated can be determined. As has already been described, it is advantageous when the actuation of the friction clutch commences shortly before the actuation of the dog clutch. This can be adjusted by the heights of the pot-shaped walls. Alternatively, the actuation piston can have an actuation plate extending in radial direction.

The friction clutch can preferably be configured such that it can absorb negative torques occurring in pull direction. During operation of the clutch arrangement, it is not only positive torques that occur; negative torques can also occur in pull direction when cutting back the engine output. In this regard, the friction clutch is configured such that it can cope with negative torques by itself. Possible noises of the dog clutch, i.e., rattling, are also prevented in this way. The dog clutch is then configured such that it can absorb the remaining peak torques in positive torque direction and can also still provide a safety margin. For example, the friction clutch can transmit 600 Nm. When the peak torques are around 2000 Nm in positive direction, the dog clutch is configured such that it transmits 1500 Nm. As has already been described, the 600 Nm results from the mere fact that this torque in negative pull direction must be covered.

The friction clutch can advantageously have an input-side hub to which the input toothing of the dog clutch is connectible so as to be fixed with respect to rotation relative to it. Thus the input hub of the friction clutch is also the input part of the dog clutch, which produces the parallel connection of the friction clutch and the dog clutch. A connectivity so as to be fixed with respect to relative rotation does not mean that the input toothing of the dog clutch, which is preferably arranged on the jaw element, engages in a toothing directly incorporated into the input hub of the friction clutch. In particular, a kind of toothing carrier can be fixedly connected to the input hub. The input toothing of the dog clutch can then engage in this toothing.

In particular, the input toothing of the dog clutch is disengageable. This means that the positive engagement of the toothing between the hub and input toothing of the dog clutch is canceled when uncoupling. However, the toothing on the output side of the dog clutch can preferably continuously engage with a toothing on the side of the flywheel mass device. It is also true with respect to the side of the flywheel mass device that the toothing can be incorporated integrally in the part of the flywheel mass device that contacts the dog clutch. However, it is also preferable in this case that a kind of toothing carrier is fixedly connected to the flywheel mass device and the flywheel mass device is constructed of multiple parts. This is considerably easier to produce in technical respects with regard to manufacture than a one-piece construction of the flywheel mass device.

The clutch arrangement can advantageously be formed as an assembly unit. In this case, it is a preassembled module which can be inserted into the powertrain.

The invention is directed, in addition, to a powertrain unit with a clutch arrangement and at least part of a flywheel mass device. As was already described in the introductory part, the clutch arrangement is to be employed as a momentum starting clutch in a hybridized powertrain. It is not a start-up clutch but rather a clutch for starting the internal combustion engine. Accordingly, the powertrain is characterized in that a clutch arrangement is formed in the manner described above.

Accordingly, all of the formulations respecting the clutch arrangement insofar as it concerns its function are no longer possible but are realized. For example, the output side of the friction clutch is connected to the flywheel mass device so as to be fixed with respect to rotation relative to it. The jaw element is supported on the flywheel mass device. However, this is not unequivocal with respect to the connection of the dog clutch to the flywheel mass device, since at least one side of the dog clutch remains connectible to the mating toothing because, as was described above, the dog clutch is disengaged for releasing. Accordingly, there is no continuous connection of the toothing on one side of the dog clutch but rather only a meshing in the engaged state.

The flywheel mass device can advantageously be formed as a dual mass flywheel. The output side of the friction clutch is then connected to the primary side of the dual mass flywheel. The output toothing of the dog clutch is likewise connected or connectible to the primary side of the dual mass flywheel.

Instead of a dual mass flywheel, a single mass flywheel could also be used. In this case, the coupling locations are to be provided just as with the dual mass flywheel.

The friction clutch and/or dog clutch can preferably have an actuation device which can be actuated by pressure oil, and the flywheel mass device can be formed to receive a portion of the pressure chamber. The flywheel mass device can form a portion of the wall of the pressure chamber, but it can also receive a wall element of the pressure chamber and accordingly support the latter. As has already been described with respect to the toothing, it is simpler in technical respects having to do with manufacture when the flywheel mass device is not formed in one piece. Accordingly, the flywheel mass device can also comprise a plurality of component parts.

The flywheel mass device can preferably receive a portion of the wall of the pressure chamber, and the output toothing of the dog clutch engages this component part simultaneously. This results in an extremely compact construction of the powertrain, since the pressure chamber simultaneously forms the output of the dog clutch.

A supply of pressure oil can advantageously lead through the flywheel mass device. In particular, the pressure oil supply can be the pressure oil supply of the actuation device of the friction clutch and/or of the dog clutch. When the flywheel mass device is formed as a dual mass flywheel, the pressure oil supply can lead through the primary part of the dual mass flywheel.

The powertrain can advantageously have a disconnect clutch on the output side of the flywheel mass device. This disconnect clutch serves to disconnect the electric motor from the internal combustion engine so that the drag torque of the internal combustion engine need not be overcome in electric motor operation. Further advantageously, the powertrain can have an electric motor on the output side of the flywheel mass device. The electric motor is preferably coupled to the powertrain in P2 arrangement.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

FIG.1shows a powertrain1with an internal combustion engine2, a momentum starting clutch arrangement3, a flywheel mass device4, a disconnect clutch5, an electric motor6and a transmission7. Electric motor6can be configured as an individual electric motor or as electric motors connected in series. It is essential here that electric motor6engages powertrain1upstream of the transmission7.

The momentum starting clutch arrangement3is distinguished by its position upstream of the flywheel mass device4. This has to do with the particular function of the momentum starting clutch arrangement3which serves merely to start the internal combustion engine2and otherwise transmits the torque of the internal combustion engine2. By providing the momentum starting clutch arrangement3, it is possible to configure the electric motor6with lower power reserves, which facilitates production. The momentum starting clutch arrangement3disconnects the internal combustion engine2from the rest of the powertrain during all-electronic operation. Accordingly, the electric motor6also drives the flywheel mass device4as energy accumulator during all-electric motor operation. However, the added power that must be provided by the electric motor6for this purpose in all-electric motor operation is less than the power reserve that would be necessary if the electric motor6had to accelerate not only the internal combustion engine but also the flywheel mass device4in order to start the internal combustion engine.

Accordingly, viewed on the whole, slightly more power must be provided during operation of the electric motor6in order to keep the flywheel mass device4running. In return, however, the electric motor6can be designed less robustly overall because the energy stored in the flywheel mass device4can then be utilized for starting the internal combustion engine2.

The momentum starting clutch arrangement3is notably not a start-up clutch because it is not used to set the motor vehicle in motion. Regardless of whether or not the motor vehicle is already in motion, the momentum starting clutch arrangement3merely serves to start the internal combustion engine2. Therefore, in terms of design, it is configurable differently than a start-up clutch, for example, with respect to the dissipation of heat. To this extent, the different function is noticeable, for example, in the amount of pressure plate material.

FIG.2shows a momentum starting clutch arrangement3in a first configuration. Momentum starting clutch arrangement3has a friction clutch8and a dog clutch9arranged parallel to the latter. Friction clutch8is designed as a dry friction clutch. It is configured in particular as a single-disk friction clutch and accordingly comprises a pressure plate10and a clutch disk12. The input side of the friction clutch8is connected to the crankshaft14, specifically via the hub16. For example, hub16can be screwed to crankshaft14by screws18.

Clutch disk12is fastened to the input hub16by rivets20and via tangential leaf springs22. Accordingly, clutch disk12is connected to crankshaft14so as to be fixed with respect to rotation relative to it. The tangential leaf springs22provide for an axial displaceability of the clutch disk12, which can also be realized in a different manner. Also, hub16need not have a hub disk24at which the tangential leaf springs22or clutch disk12engage.

Pressure plate10, counter pressure plate28, tangential leaf springs30, housing32and diaphragm spring34are located on the output side of friction clutch8.

InFIG.2, the diaphragm spring34is fastened to the primary side38of flywheel mass device4by rivets36. However, this is not mandatory as will be appreciated fromFIG.4, for example. As with this type of friction clutch, the pressure plate10is axially displaceably supported at housing32via tangential leaf springs30. Friction clutch8is releasable via diaphragm spring34. Accordingly, friction clutch8is formed as a normally closed clutch.

Dog clutch9likewise connects the crankshaft14to the primary side38of the flywheel mass device4. The input toothing40of dog clutch9which is arranged at a jaw element42communicates with crankshaft14via the input hub16and a driver element44which is arranged at the latter at least so as to be fixed with respect to rotation relative to it. As has already been described, it is simpler to arrange an additional element at hub16or to fasten the driver element44to hub16than to provide the toothing directly at the input hub16. On the other hand, the output toothing46of the dog clutch9or of the jaw element42engages with the primary side38or, generally, with the flywheel mass device4.

From this point of view, the toothing on the side of the hub16and on the primary side38is not part of the dog clutch9. Depending on the construction of the powertrain1and of the momentum starting clutch arrangement3, the latter can also be viewed as, or configured as, part of the dog clutch.

The momentum starting clutch arrangement3has an actuation device48for actuating the friction clutch8and the dog clutch9. The actuation device48is controlled by pressure oil which axially displaces an actuation piston50. Actuation piston50is formed annularly. It has a wall52and54radially inwardly and radially outwardly, respectively. Wall52contacts diaphragm spring34, and wall54contacts a projection57which is arranged at the jaw element42. Due to wall52being higher than wall54and also as a result of the arrangement of the friction clutch8compared to the dog clutch9, the friction clutch8is actuated, i.e., engaged and disengaged, earlier than the dog clutch9.

The pressure chamber is defined not only by the piston50but also by the connection element56. Connection element56is part of the primary side38of the flywheel mass device4. Accordingly, primary side38is formed of multiple parts, the base body58forming a kind of skeleton to which connection element56is fastened. Accordingly, the primary side38and therefore the flywheel mass device4also receive the pressure chamber60. A supply line62to the pressure chamber60leads through the primary side38.

The connection element56performs a dual function. On the one hand, it forms the wall of the pressure chamber60. On the other hand, it has a toothing64which engages with the output toothing46of jaw element42. Toothings46and64are preferably always in engagement, i.e., regardless of whether dog clutch9is engaged or disengaged. This is realized over the axial length of toothings46and64.

FIG.3shows the jaw element42in detail. The input toothing40and the output toothing46can be discerned. Input toothing40is constructed with two toothings66and68so that during an axial movement leftward it is no longer in register with the mating toothing, and the frictional engagement is cancelled. The input toothing40is then disengaged. As was described above, the mating toothing is arranged at driver element44and comprises toothings70and72.

In contrast, output toothing46is much longer in axial direction so that the mating toothing64is not disengaged even when there is an axial displacement relative to toothing46and accordingly remains constantly engaged.

FIG.4shows a further configuration of the momentum starting clutch arrangement3. In contrast to the configuration according toFIG.2, the diaphragm spring is fastened to a driver plate76and not to the primary side38of the flywheel mass device4, so that the momentum starting clutch arrangement can be installed as a finished preassembled module. The momentum starting clutch arrangement3can then be tightly screwed to flywheel mass unit4via screws78. It will be appreciated that only output-side elements are fastened by screws. The construction according toFIG.4agrees in many details with the construction according toFIG.2so that the same reference numerals are used.

A difference consists in the specific configuration of jaw element80compared to jaw element42.

In contrast toFIG.2, the actuation piston82is also no longer provided with walls; rather, it is formed more or less from a straight front side, also known as actuation plate, which can axially move both the diaphragm spring34and the jaw element80. However, piston82is still annular.

REFERENCE NUMERALS