DE102007044474A1 - Dual-mass flywheel for drive train of motor vehicle, has two inertial masses connected with respect to each other with elastic effect in rotation via spring unit that has coupling characteristic continuously varied by positioning unit - Google Patents

Abstract

The fly-wheel (11) has a primary inertial mass (12) and a secondary inertial mass connected with respect to each other with an elastic effect in rotation through a spring unit (30). The spring unit has a coupling characteristic continuously varied by a positioning unit (41) with an electric engine, and a spring element (32') of the spring unit has pre-stress that is varied using the positioning unit. The spring element has two ends actively connected to the primary and secondary inertial masses, respectively.

Description

The The present invention relates to a dual mass flywheel for a Powertrain of a motor vehicle with a primary flywheel and a secondary one Flywheel. The primary and the secondary Inertia are about one Spring unit torsionally connected to each other.

Dual mass flywheels the The aforementioned type are used in motor vehicles for damping of Torsional vibrations between the engine and the drive train used. In a vehicle with a manual transmission, for example, the primary flywheel rotatably connected to a crankshaft of the motor vehicle, while the secondary Flywheel is rotatably connected to a clutch. The torsional vibrations the primary Flywheels are only attenuated thanks to the spring unit secondary Transferred flywheel. Only with torsional vibrations in the range of the resonance frequency of the Dual mass flywheel can lead to unwanted amplification of Torsional vibrations instead of a weakening come. The resonance frequency of the dual mass flywheel and thus the damping effect at different Operating conditions of the motor depend on the coupling characteristic the spring unit. The softer the suspension (flat spring characteristic), the lower is the resonance frequency for a given moment of inertia the dual mass flywheel, allowing it even at low speeds not to an undesirable reinforcement the torsional vibrations can come and in the operating range - ie at higher speeds - a better one Isolation effect he aims, as the operating range continues in the supercritical Area of the resonance curve is located. However, the suspension can just because of the limited space, which is not appropriate long spring travel is sufficient, not arbitrarily soft to be selected. Another problem in choosing a suitable coupling characteristic are the different requirements for different operating states of the Engine. So far, it has not been able to construct dual-mass flywheels that in all operating states of the engine an optimal attenuation can cause the torsional vibrations. Especially at the very low vibration frequencies at startup the engine is the one with a conventional dual-mass flywheel achievable damping not satisfactory.

Of the The present invention is therefore based on the object, a dual mass flywheel to provide the type mentioned, which at different operating conditions always an optimal mitigation of the undesirable To ensure torsional vibrations able and has a simple structure.

These Task is inventively characterized solved, that the dual mass flywheel has an adjusting device, and the coupling characteristic of the spring unit is continuously variable.

The Coupling characteristic of the spring unit can thus on the Actuator actively changed and the operating conditions prevailing at a given time be adjusted. For example, when starting the engine a softer Suspension available be made as at high speeds.

advantageous embodiments The present invention is the subclaims and the following See description.

According to one preferred embodiment of Invention is over the adjusting device a bias of at least one spring element the spring unit variable. This is a simple way, the coupling characteristic to change the spring unit. By applying a bias, the global twist angle can be small be kept, while at the same time smaller in the operating point Rigidity. An adjusting device, by means of which a bias a spring element changed can be to realize themselves with comparatively little effort. For example, can the spring element having two ends, wherein the one end with the a flywheel is in operative connection and the other end with the other flywheel is operatively connected. To the bias of the To change spring element, can in this arrangement by means of the adjusting device a relative position one of the ends of the spring element with respect to the associated flywheel are changed.

The adjusting device may comprise a hydraulic system or an electric motor. Both an electric motor and a hydraulic system are suitable for driving an adjusting device, for example, to change a bias of a spring element. Thus, pressure can be exerted on one end of a spring element via a hydraulic system in order to change its relative position with respect to a flywheel associated therewith. An electric motor can drive an actuator via a reduction gear, for example an eccentric which, depending on its position, shifts one end of the spring element with respect to the flywheel mass assigned to the spring element, so that a bias voltage is changed. Such a reduction gear is preferably coaxial with an input shaft or an output shaft of the three-mass flywheel and this order arranged gripping.

According to one preferred embodiment of Invention, the adjusting device comprises an electronic control device, which the bias of the spring element in response to a Differenzverdrehwinkel between the primary and the secondary Flywheel regulates. Since the angle of rotation of the to the dual mass flywheel applied torque can depend the coupling characteristic of the dual mass flywheel so the applied torque and thus be adapted to the engine load.

Preferably is stored in the control device, a desired value for the bias, which depends on the Differenzverdrehwinkel. This setpoint can be set in Table form or in the form of a formula for calculating the preload be deposited from the Differenzverdrehwinkel.

According to one embodiment The invention is at least one measuring device for measuring a Rotation angle provided one of the flywheels. From the one of this Measuring device supplied a differential torsion angle can then be calculated, which as described above for regulating a Preload can be used. This procedure allows a very accurate and fast determination of the instantaneous Differenzverdrehwinkels.

alternative Is it possible, the Differenzverdrehwinkel not directly by an angle measurement but to calculate from a torque. On sensors for angle measurement can be omitted in this embodiment. The torque can, for example, from an already existing Engine control can be calculated. This solution is inexpensive and also easy to implement.

According to one advantageous embodiment of the The invention comprises the spring unit with respect to a rotation axis of the dual mass flywheel substantially radially or obliquely to one Radial alignment arranged spring element. Especially preferred is an arrangement in which the spring element of the rotation axis of the dual mass flywheel is spaced. Compared to a rotationally symmetric Arrangement in which the spring unit with respect to the axis of rotation radially is arranged, has such with respect to the axis of rotation laterally staggered arrangement has the advantage that the effect of centrifugal force is reduced to the spring element. This is the dependency the acting forces reduced by the speed.

According to one particularly preferred embodiment the invention, the spring element is rotatably with one of the flywheel masses connected and has at its radially outer end a rolling element on, which extends at one on the other flywheel Curve track rolls off. This curved path has one with respect to the axis of rotation of the dual mass flywheel varying radius, so that the spring element dependent on from the angle of rotation of the flywheel masses relative to each other the curved path is compressed differently. Independent of one possibly over The actuator variable bias of the spring is thus with purely mechanical means realizes a coupling characteristic, in which the stiffness of the spring element in dependence on the angle of rotation the momentum masses changeable is. The geometry of the curved path can be designed in this way that at a small angle of rotation and thus at a small angle applied torque a comparatively soft suspension is achieved while at larger angles of rotation the Spring element is compressed by the curved path, so that a tougher Suspension is achieved.

In addition, as described above, at the radially inward end of the spring element via a Actuator be applied a variable bias. These Combination allows it, for everyone Operating point a flat coupling characteristic and thus a good To realize vibration isolation.

According to one alternative embodiment the spring unit at least one in the circumferential direction of the flywheels extending coil spring in one with one of the flywheels rotatably connected chamber is arranged, and in a twisting the two flywheels deflected against each other or compressed becomes. Such spring units are already known from the prior art known and can also analogous to the embodiments described above via a Actuator are biased to a coupling characteristic to change the spring unit continuously.

in the The present invention is based on a preferred embodiment with reference to the attached Figures described in more detail become. The figures show in detail:

1 FIG. 2: a longitudinal section through a known dual mass flywheel with a coupling unit, FIG.

2 FIG. 2 is a schematic illustration of a cross section through a dual mass flywheel. FIG.

3 : a schematic representation of a Longitudinal section through the dual mass flywheel 2

4 a schematic view of the dual mass flywheel from the 2 and 3 with a control circuit.

1 shows a dual mass flywheel clutch unit with a known dual mass flywheel 11 for damping torsional vibrations, which is installed between an engine and a transmission of a motor vehicle. A primary flywheel 12 is non-rotatable with a crankshaft 10 connected. A secondary flywheel 14 is on the transmission side of the dual mass flywheel 11 by means of a coupling 18 Optionally rotatable with an output shaft 16 coupled. From the engine outgoing torsional vibrations are over the crankshaft 10 on the primary flywheel 12 transfer. The primary flywheel 12 and the secondary flywheel 14 are via a spring unit 30 limited torsionally connected with each other. The spring unit 30 includes a spring device 32 and a connecting element 31 , The spring device 32 is of a total of four in the circumferential direction of the flywheels 12 . 14 extending coil springs 36 formed in one with the primary flywheel 12 rotatably connected and not shown chamber are arranged. One end of each coil spring 36 is with this chamber 37 and thus with the primary flywheel 12 connected. The other end of each spring 36 is with the at the secondary flywheel 14 fastened connecting element 31 connected so that the coil springs 36 upon rotation of the primary flywheel 12 in terms of secondary flywheel 14 be compressed or deflected. Due to this compression or deflection counteracting Fe derkräfte the torsional vibrations of the primary flywheel 12 only attenuated to the secondary flywheel 14 transfer.

On the primary flywheel 12 opposite rear side of the secondary flywheel 14 there is a clutch disc 26 which is part of the coupling 18 is. The clutch disc 26 is non-rotatable with the output shaft 16 connected, and when acted upon by an axial pressing force, the clutch disc 26 frictionally engaged with the secondary flywheel 14 or a friction lining provided thereon are coupled. In 1 is the clutch 18 shown in an engaged state in which a clutch pressure plate 24 from a pressure spring 28 on the clutch disc 26 is pressed to make a positive connection. The pressure spring 28 is from one on the, output shaft 16 slidably mounted release 20 held, which has a release lever 21 and a pivot bearing 25 on a housing 40 the entire dual-mass flywheel clutch unit is mounted. The releaser 20 is over a lever 23 so with a clutch actuator 22 connected to it when operating this clutch actuator 22 on the output shaft 16 is moved. In 1 is the clutch actuator 22 in an engagement position, so that due to the bias of the pressure spring 28 a force on the clutch pressure plate 24 is exercised, which thereby against the clutch disc 26 is pressed.

In the 2 and 3 is an inventive dual mass flywheel 11 shown, which allows adaptation of the coupling characteristic to different operating conditions. 4 is a schematic representation of the dual mass flywheel from the 2 and 3 with an associated control circuit. Same components are in the 1 and 2 to 4 each designated by the same reference numerals.

The dual mass flywheel 11 is in 2 indicated only schematically. In particular, the in 3 visible secondary flywheel 14 in 2 for the sake of clarity not shown. It can be seen, however, that the primary flywheel 12 with a curved path 42 is provided, extending in the circumferential direction in a radially outer region of the primary flywheel 12 extends. The curved path 42 has a radially inwardly facing rolling surface 45 (see also 3 ). The radius r of the curved path 42 ie the distance of the rolling surface 45 from the axis of rotation x of the dual mass flywheel 11 , is along the curved path 42 variable. As you also in 2 can recognize, this radius r is in the respective circumferentially outer regions of the cam track 42 maximum and takes to the middle of the curved path 42 down continuously.

The two momentum masses 12 . 14 are in the in the 2 and 3 shown embodiment of the invention via a spring element 32 ' interconnected, which in an in 2 shown rest position substantially radially to the axis of rotation x of the dual mass flywheel 11 runs. More precisely, the spring element 32 ' offset laterally by a distance d with respect to a radial position. This lateral offset d ensures that the influence of centrifugal force on the spring element 32 ' in comparison to those by a relative rotation of the two flywheels 12 . 14 to each other caused forces remains low.

As already described above, the two flywheels twist 12 . 14 to each other when a torque on the dual mass flywheel 11 acts. Depending on a Dif Reference twist angle φ of the two flywheels 12 . 14 relative to each other, the position of the changes at the primary flywheel 12 provided curves track 42 in terms of that with the secondary flywheel 14 connected spring element 32 ' , At its radially outer end is the spring element 32 ' with a rolling element 34 provided, which on the rolling surface 45 the curved path 42 at the secondary flywheel 14 rests. If the two momentum 12 . 14 Now twist each other, rolls the rolling element 34 on the rolling surface 45 the curved path 42 from, and the spring element 32 ' becomes dependent on the radius r of the curved path 42 more or less compressed.

At its radially inner end is the spring element 32 ' about one in 2 only schematically indicated adjusting device 41 with the secondary flywheel 14 connected. This in 3 more precisely recognizable actuating device 41 includes an electric motor 44 that has a reduction gear 50 an eccentric 52 with respect to the rotation axis x can rotate. Both the electric motor 44 as well as the reduction gear 50 and the eccentric 52 are coaxial with the axis of rotation x of the dual mass flywheel 11 arranged. The reduction gear 50 and a rotor 48 of the electric motor 44 embrace an output shaft 16 of the dual mass flywheel 11 , A stator 46 of the electric motor 44 is radially outside of the rotor 48 arranged and rotationally fixed with the secondary flywheel 14 connected. Via sliding contacts 54 becomes the electric motor 44 powered. Instead of the electric motor 44 Of course, other drives are conceivable. For example, the adjusting device may comprise a hydraulic system.

Depending on the position of the by the electric motor 44 rotatable eccentric 52 becomes a more or less large pressure p on the spring element 32 ' exercised. The radially inner end of the spring element 32 ' is thus by the actuator 41 shifted and thereby biased the spring element.

The change Δφ of the Differenzverdrehwinkel φ between the two masses 12 . 14 , and thus the angular position of the spring element 32 ' , which adjusts to a certain change .DELTA.M of the applied torque M, thus depends not only on the torque M and the intrinsic stiffness of the spring element 32 ' but can additionally by the over the adjusting device 41 on the radially inner end of the spring element 32 ' applied pressure p can be varied. At the same time, because of the variable radius r of the curved path 42 Also, a relationship with the average Differenzverdrehwinkel φ, which has been adjusted due to an average applied torque M.

With the help of in 4 The control circuit shown, the change Δφ the Differenzverdrehwinkels φ be adjusted so that a desired change Δφ _set the Differenzverdrehwinkels φ is set for a given change ΔM of the applied torque M. An instantaneous mean change Δφ of the differential torsional angle φ can be determined either from measurements of the respective angles of rotation of the primary and secondary flywheel masses 12 . 14 or calculated from a mean torque M calculated by an engine controller. This actual value Δφ can then be compared with a desired value Δφ _Soll . About the adjusting device 41 can in the case of a deviation from this setpoint Δφ _set the bias of the spring unit 32 ' be readjusted by means of a control algorithm to set the desired change Δφ _Soll the Differenzverdrehwinkels and thus the desired spring stiffness for this operating point. If a suitable control algorithm is used, this procedure allows a flat spring characteristic even with large changes in load with only a slight twisting of the two flywheel masses 12 . 14 to achieve each other.

10

crankshaft

11

Dual Mass Flywheel

12

primary flywheel

14

secondary flywheel

16

output shaft

18

clutch

20

releaser

21

release lever

22

clutch

23

lever

24

Clutch Pressure Plate

25

pivot bearing

26

clutch disc

28

pressing spring

30

spring unit

31

connecting element

32 32 '

spring element

34

rolling element

36

coil spring

38

blocking element

40

casing

41

setting device

42

cam track

44

electric motor

46

stator

48

rotor

50

Reduction gear

52

eccentric

54

sliding contacts

d

distance Axis of rotation / spring element

r

radius

x

axis of rotation

Claims (14)

Dual mass flywheel ( 11 ) for a drive train of a motor vehicle with a primary flywheel ( 12 ) and a secondary flywheel ( 14 ), with the primary and secondary flywheels ( 12 . 14 ) via a spring unit ( 30 ) are torsionally elastic connected to each other, characterized in that the dual mass flywheel ( 11 ) an adjusting device ( 41 ), by means of which a coupling characteristic of the spring unit ( 30 ) is continuously variable. Dual mass flywheel ( 11 ) according to claim 1, characterized in that on the adjusting device, a bias voltage of at least one spring element ( 32 . 32 ' ) of the spring unit ( 30 ) is changeable. Dual mass flywheel ( 11 ) according to claim 2, characterized in that the spring element ( 32 . 32 ' ) has two ends, one end having one flywheel ( 12 ) is operatively connected and the other end with the other flywheel ( 14 ) is operatively connected, wherein by means of the adjusting device ( 41 ) a relative position of one of the ends of the spring element ( 32 . 32 ' ) with regard to the assigned flywheel mass ( 14 ) is changeable. Dual mass flywheel ( 11 ) according to one of the preceding claims, characterized in that the adjusting device comprises a hydraulic system. Dual mass flywheel ( 11 ) according to one of the preceding claims, characterized in that the adjusting device ( 41 ) an electric motor ( 44 ). Dual mass flywheel ( 11 ) according to claim 5, characterized in that a reduction gear ( 50 ) coaxial with an input shaft ( 10 ) or an output shaft ( 16 ) of the dual mass flywheel ( 11 ) and this is arranged encompassing. Dual mass flywheel ( 11 ) according to one of the preceding claims, characterized in that the adjusting device ( 41 ) comprises an electronic control device, which the bias of the spring unit ( 30 ) as a function of a difference twist angle (φ) between the primary ( 12 ) and the secondary flywheel ( 14 ) regulates. Dual mass flywheel ( 11 ) according to claim 7, characterized in that in the control device, a desired value for the bias voltage is stored, which depends on the Differenzverdrehwinkel (φ). Dual mass flywheel ( 11 ) according to claim 7 or 8, characterized in that at least one measuring device for measuring a rotation angle of one of the flywheel masses ( 12 . 14 ) is provided and from the measured value supplied by this measuring device a Differenzverdrehwinkel (φ) can be calculated. Dual mass flywheel ( 11 ) according to claim 7 or 8, characterized in that the Differenzverdrehwinkel (φ) from a torque (M) is calculable, said torque (M) is preferably calculated by a motor controller. Dual mass flywheel ( 11 ) according to one of the preceding claims, characterized in that the spring unit ( 30 ) with respect to an axis of rotation (x) of the dual mass flywheel ( 11 ) arranged substantially radially or obliquely to a radial alignment spring element ( 32 ' ). Dual mass flywheel ( 11 ) according to claim 11, characterized in that the spring element ( 32 ' ) from the axis of rotation (x) of the dual-mass flywheel ( 11 ) is spaced. Dual mass flywheel ( 11 ) according to claim 11 or 12, characterized in that the spring element ( 32 ' ) with one of the flywheels ( 12 ) is rotatably connected and at its radially outer end a rolling element ( 34 ), which at one on the other flywheel ( 14 ) extending cam track ( 42 ) rolls, the curved path ( 42 ) has a relation to the axis of rotation (x) of the dual mass flywheel radius variie-generating radius (r), so that the spring element ( 32 ' ) as a function of the differential torsion angle (φ) of the flywheel masses ( 12 . 14 ) is compressed differently relative to each other. Dual mass flywheel ( 11 ) according to one of claims 1 to 10, characterized in that the spring unit ( 30 ) at least one in the circumferential direction of the flywheels ( 12 . 14 ) extending coil spring ( 36 ) in one with one of the flywheels ( 12 ) rotatably connected chamber is arranged, and in a rotation of the two flywheel masses ( 12 . 14 ) is deflected or compressed against each other.