DE102008038150A1 - Dual mass flywheel for drive train of motor vehicle, has primary flywheel mass and secondary flywheel mass which are rotatably arranged around common rotational axis and are torsionally flexibly coupled to each other - Google Patents

Abstract

The dual mass flywheel has a primary flywheel mass (11) and a secondary flywheel mass (13) which are rotatably arranged around a common rotational axis (A) and are torsionally flexibly coupled to each other. An attenuator unit (17) is provided which dissipatively attenuates twisting movement between the flywheel masses. The attenuator unit has an eddy current brake (19). The attenuating effect of the eddy current brake is dependent on the speed of the twisting movement between the flywheel masses.

Description

The The present invention relates to a dual mass flywheel for a drive train of a motor vehicle, with a primary Flywheel and a secondary flywheel that rotates around a common axis of rotation are arranged and torsionally elastic coupled together, and with a damping device, which dissipatively dampens a twisting motion between the flywheel masses.

One Such dual mass flywheel is used in a motor vehicle for Caching of kinetic energy during the idle cycles of the internal combustion engine and for picking up and steaming of torsional vibrations between the engine and the drive train. Typically, in a manual transmission vehicle, the primary flywheel is rotatably connected to the crankshaft of the internal combustion engine while the secondary flywheel rotatably with the clutch of the gearbox is connected or forms part of it. Because an elastic Coupling the primary flywheel with the secondary flywheel is a swinging system formed, which is designed so that in the regular Driving operation of the motor vehicle operation in the supercritical Area is done. The dual mass flywheel thus acts as a mechanical one Low pass filter.

Around the best possible isolation of the gearbox the rotational irregularities of the engine and a possible to achieve high efficiency is basically one low friction within the dual mass flywheel desirable. issues however, can prepare the transient processes namely, when the dual mass flywheel is the natural frequency the elastic coupling device passes through, for example when starting or stopping the engine, in the dicing operation or at a load change. The resulting resonance effects can damage the dual-mass flywheel and the drivetrain. In such transient Operations is therefore a minimum of friction required to provide sufficient damping of natural oscillations of the dual mass flywheel.

at conventional dual mass flywheels with bow springs as elastic coupling device is such a minimum Friction already by the friction of the springs on the housing given. However, the friction torque achieved is undesirable depends on the speed of the dual mass flywheel.

It is therefore also known, the springs of the elastic coupling device free from the housing and the desired friction by means of its own damping device in one of to set the speed independently. This is It is known, friction disks, with the primary flywheel or the secondary flywheel are coupled, in axial Tension direction with each other. This allows a Grundreibmoment specified whose amount is influenced by the choice of preload force can. The basic friction torque must be set comparatively high, so that when passing through the natural frequency, the required damping effect is achieved. The disadvantage of this, however, is that such a Grundreibmoment during the entire operation of the dual mass flywheel is effective, so even if the elastic coupling device is in the supercritical area and therefore a dissipative damping is not required at all would.

There are therefore also dual-mass flywheels known whose dissipative damping device (friction device) is active only after sweeping over a predetermined clearance angle, ie, when based on a change in direction of the rotational movement between the two flywheel masses, a predetermined change in the rotation angle is reached. To realize such a clearance angle typically moves a driver within a window. Only after reaching a lateral stop a friction lining is moved relative to an associated counter-plate. A dual mass flywheel with such a friction device is for example in the DE 34 47 926 A1 (corresponding US 4,729,465 ) and in the DE 32 06 623 A1 (corresponding GB 2 093 565 A ).

at However, this type of friction devices is a disadvantage again, that in a slow twisting motion between The two momentum masses are not necessarily overshooting Lastwechselvorgang sets, which is why the friction sometimes not free ("getting stuck"). The torque applied to the friction device is thus less than the Haftreibmoment, creating a constant striking the Driver is caused on the friction device. The damping is thus inactive. However, the rigidity of the friction device is (Contact stiffness between the friction lining and the associated Counter plate) parallel to the main rigidity (elastic coupling device) connected. Because of the higher global stiffness of the dual mass flywheel worsens its isolation behavior (The natural frequency is proportional to the root of the global Stiffness).

It is an object of the present invention to provide a dual-mass flywheel with an improved damping device, which is a Dissipative attenuation mainly causes when the primary flywheel and the secondary flywheel move with a high rotational speed relative to each other.

These Task is accomplished by a dual mass flywheel with the characteristics of Claim 1 and in particular in that the damping device having an eddy current brake.

By doing the damping device of the invention Dual mass flywheel is formed by an eddy current brake or has an eddy current brake, can be simple and inexpensive Way a dissipative damping can be effected before all depending on the speed of the twisting movement between the two masses of momentum is effective. The eddy current brake namely generates a braking torque proportional to the relative twisting speed is. Here is the eddy current brake parallel to the elastic coupling device (eg spring packs) arranged the dual mass flywheel. The eddy current brake must but not directly between the two flywheels be effective, but between the eddy current brake and the primary Flywheel and / or the secondary flywheel can be additional Friction or coupling devices may be provided as below will be explained.

Especially It is advantageous that the eddy current brake as a passive Damping device may be formed, ie without electrical Energy supply from outside. This results in a special simple and inexpensive construction. Nevertheless, the Eddy current brake due to their rotational speed dependent Acting self-regulating.

According to one preferred embodiment has the eddy current brake at least one permanent magnet connected to an electrically conductive Brake body cooperates, wherein the permanent magnet on Place the brake body generates a magnetic field. Here is the permanent magnet associated with one of the two flywheels, while the brake body of the other of the two flywheels is assigned, d. H. the permanent magnet and the brake body are directly or indirectly connected to the respective flywheel. The effective at the location of the brake body magnetic field of the permanent magnet caused by a relative movement between the magnetic field and the brake body electrical eddy currents within of the brake body. These in turn generate a force or a torque, the or a relative movement between the Permanent magnets and the brake body (and thus between the counteracts both flywheel masses).

Especially compact and effective designs are possible if the said at least one permanent magnet is aligned in such a way, that of the permanent magnet at the location of the brake body generated magnetic field with respect to the axis of rotation of the flywheels in the axial direction or in the radial direction or in an intermediate direction runs.

Around the magnetic field of the permanent magnet along the desired Direction (in particular perpendicular to the plane of extent of the brake body) align, the permanent magnet is preferably associated with a yoke.

Further For example, the eddy current brake may include a plurality of permanent magnets with respect to the axis of rotation of the flywheels in the circumferential direction preferably arranged uniformly distributed, to a correspondingly even distribution of To achieve braking torque.

What As regards the said brake body, this is along the extent of the magnetic field at the location of the brake body in a normal plane to the direction of the magnetic field, preferably uninterrupted formed in one piece. This allows the desired eddy currents particularly effective be generated. The brake body, for example, the Have the shape of a circular ring or a circular disk.

Of the Brake body is preferably made of a material with high electrical conductivity (eg copper or aluminum).

alternative to the explained passive embodiment of the eddy current brake can also be provided an active embodiment, in which instead of a permanent magnet, for example, an electric Excitable solenoid is provided.

According to an advantageous embodiment, the damping device may additionally comprise a friction device which is active parallel to the eddy current brake effectively and independently of the angle of rotation between the two flywheel masses (ie without clearance angle). In this way, a low Grundreibmoment can be adjusted, which is already effective at a low rotational speed of the two flywheel masses relative to each other. Such a Grundreibmoment is particularly advantageous when the eddy current brake is not directly (rigidly) coupled to the two flywheel masses, but a part of the eddy current brake (in particular the aforementioned brake body) is rotatably arranged to the associated flywheel. In such an arrangement, the Grundreibmoment prevents said additional friction device to large torsions due to the inertia of the relevant part of the eddy current brake.

Especially the damping device can also be a driving device own, between the eddy current brake and the primary flywheel or the secondary flywheel is arranged in series, and depending on a change in the Angle of rotation between the eddy current brake and the primary or secondary flywheel (that is, only after painting a clearance angle) is active. By such a rotation angle dependent active entrainment can be achieved that the eddy current brake only at a predetermined minimum twist of the two masses becomes active. This can be in normal operation of the dual mass flywheel - ie when the elastic coupling means is almost complete Isolation causes - losses due to the dynamically changing Position of the secondary side relative to the primary side at least significantly reduced. Thus, in such an embodiment with a torsion-dependent effective entrainment device the series eddy current brake actually is also dependent on angle of rotation active, has the Damping device preferably the already mentioned Friction device for generating a Grundreibmoments in a parallel circuit to the eddy current brake.

alternative or in addition to the explained, depending on the angle of rotation active entrainment means, the damping device also have elasticity, for example a spring, between the eddy current brake and the primary flywheel or the secondary flywheel is arranged in series, this elasticity generates a restoring moment, that of the angle of rotation between the eddy current brake and the primary or secondary flywheel depends. This can be achieved that with increasing angle of rotation the eddy current brake in accordance with increasing levels becomes active.

According to one advantageous embodiment is also provided that the dual mass flywheel is formed without a friction device, directly with the primary flywheel on the one hand and the secondary flywheel coupled on the other hand and at each twisting motion between the flywheels (i.e. H. without clearance angle) is active. The dual mass flywheel causes thus not necessarily a basic friction torque in each operating state, which in some operating conditions of the dual mass flywheel at all not needed and due to the hereby associated energy losses would be undesirable.

The Invention will now be described by way of example only with reference to the figures explained.

1 shows a schematic side view of a dual mass flywheel.

2a and 2 B show two embodiments of an attenuator with eddy current brake.

1 shows a schematic side view of a dual mass flywheel whose basic structure, for example, from the publications mentioned above DE 34 47 926 A1 and DE 32 06 623 A1 is known. In particular, this dual mass flywheel has a primary flywheel 11 and a secondary flywheel 13 which are rotatably mounted with respect to a common axis of rotation A and an elastic coupling means 15 (For example, several spring assemblies) are torsionally coupled to each other.

Parallel to the elastic coupling device 15 is a damping device 17 between the two momentum masses 11 . 13 arranged. This damping device 17 has an eddy current brake 19 , Furthermore, the damping device has 17 in the embodiment shown here, a friction device 21 parallel to the eddy current brake 19 is arranged, and a driving device 23 with clearance angle function, in series with the eddy current brake 19 is arranged.

The eddy current brake 19 has a permanent magnet 25 with a yoke 27 for generating a magnetic field B at the location of an electrically conductive brake body 29 , The brake body 29 consists for example of aluminum and is at least in the field of magnetic field B uninterrupted formed integrally, ie solid. The brake body 29 has the shape of a circular disk and is also rotatably mounted with respect to the axis of rotation A in the embodiment shown here. The permanent magnet 25 with the yoke 27 however, with the primary flywheel 11 directly connected.

The friction device 21 acts directly between the primary flywheel 11 and the brake body 29 the eddy current brake 19 , The friction device 21 For example, includes an annular friction lining, which cooperates frictionally with a likewise annular counter-plate, wherein the friction lining is biased by a spring axially in the direction of the counter-plate. The friction device 21 thus generates in the case of a rotational movement of the brake body 29 relative to the primary flywheel 11 regardless of the angle of rotation a Grundreibmoment.

The entrainment device 23 is immediate between the secondary flywheel 13 and the brake body 29 the eddy current brake 19 effective. The entrainment device 23 is formed such that the brake body 29 only then from the secondary flywheel 13 is carried along when the brake body 29 and the secondary flywheel 13 have rotated by a predetermined clearance angle relative to each other, based on a previous change of direction of the rotational movement. To realize such a clearance angle function, for example, a driver element of the secondary flywheel 13 with circumferential clearance in an operating window of the brake body 29 engage, similar to that for friction devices with clearance angle function from the aforementioned publications DE 34 47 926 A1 and DE 32 06 623 A1 is known.

The following is the operation of the in 1 illustrated dual mass flywheel explained.

The elastic coupling device 15 causes a torsionally elastic coupling between the primary flywheel 11 and the secondary flywheel 13 , which are usually connected to an internal combustion engine or via a clutch with a manual transmission. The elastic coupling device 15 ensures isolation of the secondary flywheel 13 in terms of rotational nonuniformity, from the internal combustion engine to the primary flywheel 11 be directed.

The damping device 17 is intended to provide resonance effects when passing through the natural frequency of the oscillatory system 11 . 13 . 15 to dampen. A special feature is the eddy current brake 19 ,

If the brake body 29 relative to the primary flywheel 11 and the permanent magnet attached thereto 25 with yoke 27 turns, the brake body moves 29 by the magnetic field B, that of the permanent magnet 25 with the yoke 27 at the place of the brake body 29 is produced. As a result, in the brake body 29 induces electrical voltages that cause the formation of eddy currents. The eddy currents in turn generate a magnetic field, that of the change of the external magnetic field B in the brake body 29 is opposite. The electrical resistance of the brake body 29 forms an ohmic consumer for the eddy currents, whereby the kinetic energy of the brake body 29 (relative to the rotational movement relative to the primary flywheel 11 ) is converted into heat. The rotational movement of the brake body 29 is thereby dampened dissipatively. This damping effect is proportional to the speed of the relative movement between the brake body 29 and the primary flywheel 11 ,

Parallel to the eddy current brake 19 is the friction device 21 between the brake body 29 and the primary flywheel 11 effective. The friction device 21 generates a permanent Grundreibmoment, ie the friction effect is independent of the angle of rotation between the brake body 29 and the primary flywheel 11 , As the brake body 29 is rotatably mounted in the embodiment shown here, prevents the Grundreibmoment the friction device 21 that the brake body 29 due to its inertia to large rotational movements relative to the primary flywheel 11 performs. For this purpose, it is sufficient if a low Grundreibmoment is set. In particular, this friction torque can be significantly lower than the friction torque of a conventional friction device with clearance angle function, since the required damping effect is mainly generated by the eddy current brake.

By the illustrated clearance angle function of the driver 23 is ensured that in normal operation of the dual mass flywheel - so if the elastic coupling device 15 In the supercritical frequency range, the desired isolation of the secondary side from the rotational irregularities of the primary side causes - the eddy current brake 19 is essentially disabled and no unnecessary damping effect. The amplitude of the rotational movement of the secondary flywheel occurring in normal operation 13 relative to the primary flywheel 11 Thus, it is not enough to a large rotational speed of the brake body 29 relative to the permanent magnet 25 to the yoke 27 to effect. The energy losses during normal operation of the dual mass flywheel are thereby kept low. It is advantageous that the friction device 21 the explained Grundreibmoment generated to a completely free swinging of the brake body 29 within the clearance angle of the driver 23 to prevent. At high amplitudes of the rotational movement between the primary flywheel 11 and the secondary flywheel 13 however, the entrainment device ensures 23 for the brake body 29 relative to the permanent magnet 25 is twisted and the eddy current brake 19 thus active.

Overall, this results in a damping device 17 when passing through the natural frequency of the elastic coupling device 15 ensures effective damping, especially if there is a high rotational speed of the secondary flywheel 13 relative to the primary flywheel 11 established. In normal operation of the dual mass flywheel, however, behaves the damping device 17 essentially lossless.

According to the illustrated embodiment according to 1 It should also be noted that in principle a mirror-symmetrically reversed arrangement of primary side and secondary side can be provided.

Instead of the driving device shown 23 can be between the brake body 29 and the secondary flywheel 13 also be provided an elasticity, which is a restoring moment between the brake body 29 and the secondary flywheel 13 generated, which depends on the angle of rotation between the brake body 29 and the secondary flywheel 13 depends. This will cause the eddy current brake 19 activated in a continuously increasing extent, when the angle of rotation between the brake body 29 and the secondary flywheel 13 increased. Such elasticity can also be parallel to the described entrainment device 23 be provided with clearance angle function, in particular to effect an elastic damping of the abutment of the driver element on the stops of the driver.

Alternatively, it is also possible, the brake body 29 with the secondary flywheel 13 rotatably to connect, ie without the interposition of the driver 23 , The damping effect of the eddy current brake 19 then depends directly on the speed of rotation between the primary flywheel 11 and the secondary flywheel 13 from. Optionally, in this case too, the in 1 shown friction device 21 (Grundreibmoment) be provided.

Finally, with regard to the exact configuration of the eddy current brake 19 to note the following:
How out 1 it can be seen is between the brake body 29 and the permanent magnet 25 or the yoke 27 provided an air gap. The permanent magnet 25 and the brake body 29 So preferably interact without contact. The Grundreibmoment is optionally on the explained friction 21 set.

It is in 1 Furthermore, it can be seen that the magnetic field B of the permanent magnet 25 with yoke 27 at the place of the brake body 29 in the axial direction (with respect to the axis of rotation A). It is important here that the magnetic field B perpendicular to the plane of extension of the brake body 29 in the region of the magnetic field B runs.

A simpler embodiment of the eddy current brake 19 is in 2a shown. Here is the permanent magnet 25 also rotatably with the primary flywheel 11 connected. However, there is no yoke, which leads the magnetic flux targeted. At the place of the brake body 29 the stray field of the permanent magnet acts 25 ,

2 B shows an embodiment in which the magnetic field B of the permanent magnet 25 by means of a yoke 27 at the place of the brake body 29 is guided in the radial direction (again with respect to the axis of rotation A). The essentially disc-shaped brake body 29 owns here a collar section 31 which extends into the magnetic field B. The primary flywheel 11 It consists of a material of low magnetic permeability (eg aluminum) to form a magnetic short circuit along the primary flywheel 11 to avoid.

11

primary Inertia

13

secondary Inertia

15

elastic coupling device

17

attenuator

19

Eddy current brake

21

friction device

23

entrainment

25

permanent magnet

27

yoke

29

Brakes

31

collar section

A

axis of rotation

B

magnetic field

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 3447926 A1 [0006, 0026, 0030]
• US 4729465 [0006]
• - DE 3206623 A1 [0006, 0026, 0030]
• - GB 2093565 A [0006]

Claims (17)

Dual mass flywheel for a drive train of a motor vehicle, with a primary flywheel ( 11 ) and a secondary flywheel mass ( 13 ), which are arranged rotatably about a common axis of rotation (A) and are coupled in a torsionally elastic manner to each other, and with a damping device ( 17 ), a rotational movement between the flywheels ( 11 . 13 ) dissipatively attenuates, characterized in that the damping device ( 17 ) an eddy current brake ( 19 ) having. A dual mass flywheel according to claim 1, wherein the damping effect of the eddy current brake ( 19 ) of the speed of a rotational movement between the flywheel masses ( 11 . 13 ) is dependent. Dual mass flywheel according to claim 1 or 2, wherein the eddy current brake ( 19 ) parallel to an elastic coupling device ( 15 ) is arranged, the the flywheel masses ( 11 . 13 ) coupled to each other in a torsionally elastic manner. Dual-mass flywheel according to one of the preceding claims, wherein the eddy current brake ( 19 ) is formed as a passive damping device without electrical power supply. Dual-mass flywheel according to one of the preceding claims, wherein the eddy current brake ( 19 ) at least one permanent magnet ( 25 ), which with an electrically conductive brake body ( 29 ), wherein the at least one permanent magnet at the location of the brake body generates a magnetic field (B), wherein the at least one permanent magnet ( 25 ) the one ( 11 ) is assigned to the two flywheel masses, and wherein the brake body ( 29 ) of the other ( 13 ) is assigned to the two flywheel masses. A dual mass flywheel according to claim 5, wherein the at least one permanent magnet ( 25 ) is aligned in such a way that that of the permanent magnet at the location of the brake body ( 29 ) generated magnetic field (B) with respect to the axis of rotation (A) of the flywheels in the axial direction or in the radial direction or along a combination of these two directions. A dual mass flywheel according to claim 5 or 6, wherein the at least one permanent magnet ( 25 ) a yoke ( 27 ) assigned. Dual-mass flywheel according to one of claims 5 to 7, wherein the eddy current brake ( 19 ) a plurality of permanent magnets ( 25 ), which are arranged distributed uniformly with respect to the axis of rotation (A) of the flywheels in the circumferential direction. A dual mass flywheel according to any one of claims 5 to 8, wherein the at least one permanent magnet ( 25 ) with the brake body ( 29 ) interacts without contact. Dual-mass flywheel according to one of claims 5 to 9, wherein the brake body ( 29 ) along the extent of the magnetic field (B) at the location of the brake body in a normal plane to the direction of the magnetic field (B) is formed integrally without interruption. Dual-mass flywheel according to one of claims 5 to 10, wherein the brake body ( 29 ) has the shape of a circular ring or a circular disk. Dual-mass flywheel according to one of claims 5 to 11, wherein the brake body ( 29 ) is formed of aluminum or copper. Dual-mass flywheel according to one of the preceding claims, wherein the damping device ( 17 ) a friction device ( 21 ) parallel to the eddy current brake ( 19 ) effectively and independently of the angle of rotation between the flywheels ( 11 . 13 ) is active. Dual-mass flywheel according to one of the preceding claims, wherein the damping device ( 17 ) a driver device ( 23 ), which between the eddy current brake ( 19 ) and the primary or secondary flywheel ( 11 . 13 ) and is operative in response to a change in the angle of rotation between the eddy current brake and the primary and secondary flywheels, respectively. Dual-mass flywheel according to one of the preceding claims, wherein the damping device ( 17 ) has an elasticity between the eddy current brake ( 19 ) and the primary or secondary flywheel ( 11 . 13 ) is arranged and which generates a restoring torque, which depends on the angle of rotation between the eddy current brake and the primary and secondary flywheel. Dual mass flywheel after one of the previous ones Claims, wherein the dual mass flywheel without friction device is formed, which directly with the primary flywheel one hand and the secondary flywheel coupled on the other hand is and is constantly active. A dual mass flywheel according to any one of the preceding claims, wherein the primary Flywheel ( 11 ) is designed for connection to a crankshaft of an internal combustion engine and the secondary flywheel ( 13 ) is formed for connection to a clutch of a gearbox or forms part of such a clutch.