EP1027546A1

EP1027546A1 - Anti vibration device and operational method therefor

Info

Publication number: EP1027546A1
Application number: EP98955443A
Authority: EP
Inventors: Thomas Pels
Original assignee: ISAD Electronic Systems GmbH and Co KG; Continental ISAD Electronic Systems GmbH and Co KG
Current assignee: Continental ISAD Electronic Systems GmbH and Co OHG
Priority date: 1997-11-04
Filing date: 1998-10-13
Publication date: 2000-08-16
Also published as: JP2001522023A; DE19748665A1; WO1999023396A1

Abstract

The invention relates to an anti-vibration device, e.g. for the drive train of a motor vehicle, whereby an electric motor (4) is arranged in front of an anti-vibration device (6) in said drive train. The electric motor (4) is used to apply torque to the input shaft (2) or the output shaft (10) in such a way that the anti-vibration device has an enhanced or reduced elastic rigidity with respect to the torque induced by the other shaft (10 or 2).

Description

DEVICE FOR INSULATION INSULATION AND METHOD FOR OPERATING THE SAME

The invention relates to a device for vibration isolation, e.g. in the / drive train of a motor vehicle, according to the preamble of claim 1 and a method for operating such a device.

Due to the discontinuous mode of operation, a large number of different vibration phenomena occur in combustion piston engines. The torsional vibrations in the drive train of a motor vehicle caused by torque fluctuations of the internal combustion engine are particularly noticeable. These propagate through the other vehicle components and lead to a noise and vibration level that is disruptive for the vehicle occupants. To avoid or reduce the propagation of vibrations in the drive train, vibration isolation devices are therefore used which couple the drive side connected to the internal combustion engine and the output side leading to the transmission, for example, in a torsionally elastic manner. Such a vibration isolation device leads to effective "isolation" of the output side from excitation torques of the drive side (and vice versa) if the resonance frequency of the vibration isolation device is less than the excitation frequency, in particular less than 0.7 times the excitation frequency. Since a low resonance frequency is achieved, among other things, by low spring stiffness, this operating range is also called the "soft tuning" range. According to the prior art, such a vibration isolation device can be structurally integrated in the conventional flywheel of a motor vehicle. If two flywheel masses are connected to one another via one or more elastic coupling elements, one speaks of a two-mass flywheel (DMF).

An example of a device of the type mentioned is disclosed in German patent application 196 31 384.8 by the assignee. There, the vibration isolation device, for example in the form of such a two-mass flywheel, is integrated in the rotor of an electric starter machine, the rotor being seated directly on the crankshaft of the internal combustion engine. This arrangement serves to shield the output side from torque fluctuations on the drive side (and vice versa). This arrangement satisfactorily fulfills the tasks assigned to it. When tuning the vibration isolation device, however, it is faced with conflicting requirements. On the one hand, in order to achieve the lowest possible natural frequency - that is, the most effective damping possible - the vibration isolation device is tuned as softly as possible (ie, low spring stiffness). However, there is a risk that in the case of large excitation amplitudes, for example in the event of a load change, the elastic coupling elements of the vibration isolation device are rotated against one another until they stop, so that vibration isolation property is then no longer present. On the other hand, a hard tuning (high spring stiffness) would be desirable in order to remain within the range of effective isolation even with such large excitation amplitudes, ie not to come into contact with the vibration isolation. The known arrangement cannot meet these conflicting requirements. The necessary compromise generally means that the natural frequency of the arrangement is chosen to be relatively high and, in the case of extremely high exciter amplitudes, torsion of the vibration isolation device up to the stop cannot be ruled out. The aim of the invention is to provide a device for vibration isolation which behaves more advantageously in this regard and thus has a wider operating range. This includes specifying a corresponding procedure.

The invention achieves this aim by the subject matter of claims 1 and 10. Advantages of the embodiments of the invention are described in the respective dependent claims.

Then a device for vibration isolation, e.g. for a motor vehicle, provided which comprises: at least one with a primary drive, z.Ξ. an internal combustion engine of the motor vehicle, coupled drive train with an input shaft and an output shaft; a vibration isolating device coupling the input shaft and the output shaft in a torsionally elastic manner; an electrical machine, the rotor of which can be connected or connected in a rotationally fixed manner to the input shaft and the output shaft and whose stator can be fixed or fixed against rotation; and a control device which controls the electrical machine in such a way that it applies torques which vary over time to the input shaft or the output shaft in such a way that the torsion of the vibration isolation device which is induced by the other time (output shaft or input shaft) is reduced or increased.

With the aid of this arrangement, it is possible to influence the effective spring stiffness of the vibration isolation device. The arrangement has the advantage that it can be adapted to different vibration situations with regard to the insulation or damping properties of the vibration isolation device. The elastic coupling elements of the vibration isolation device have a fixed spring characteristic (material, geometry and dimension dependent) (so-called specific spring characteristic). Without control of the electrical machine in the invention The above-mentioned vibration isolation device would react to an excitation torque of the input or output shaft with an elastic deformation of these coupling elements which is dependent on the specific spring characteristic of the elastic coupling elements and thus a corresponding torsion of the vibration isolation device. In the case of periodically variable excitation torques, these are correspondingly periodically variable torsions of the vibration isolation device. The stator of the electrical machine is preferably supported against a fixed reference point, for example a motor or a transmission housing. By actuating the electrical machine in such a way that it also applies a torque in phase with the excitation torque on the side of the vibration isolation device opposite the excitation side, a positive or negative torque is superimposed on the excitation torque, so that the torsion of the vibration isolation device - depending on the sign of the additional torque - is increased or decreased. As a result, this resembles a softer or harder vibration isolating device. The effective spring characteristic of the vibration isolation device therefore appears to be "variable".

The additional torques that are applied by the electrical machine on the side of the vibration isolation device opposite the exciter side can in principle be changed as desired according to the amount and / or direction (in the available power range of the electrical machine). For example, the electrical machine can be controlled in such a way that the torques which it changes over time are proportional to the excitation torques on the exciter side of the vibration isolation device, ie the torques applied by the elastic vibration isolation device. The additional torques then differ only by a constant factor and possibly by the sign. As a result, the shape of the effective spring characteristic remains unchanged, only the slope of the characteristic becomes steeper or flatter. The term "control" as used herein is in accordance with the invention ^¬ He broadly understood and includes in particular and control operations.

Preferably, however, the additional torques applied differ from the excitation torques by a non-constant factor, e.g. If the number increases with increasing torsion, the shape of the effective spring characteristic (spring stiffness) of the vibration isolation device is also changed, e.g. made flatter (softer), in particular linearized, or on the contrary, made steeper (harder) for large excitation moments.

In a particularly preferred variant, the additional torques applied by the electrical machine have the same sign as the excitation torques and increase with increasing torsion of the vibration isolation device in such a way that the torsion does not exceed a predetermined limit value. Such a limit value takes into account, for example, the state of the elastic coupling elements of the vibration isolation device, for example the achievement of a permissible load or stress, in particular the coupling elements striking. The properties of the elastic coupling elements, for example spring constant, spring length, maximum elongation, maximum compression, etc., must be taken into account in the control. For this purpose, a maximum permissible value (limit value) for the torsion is determined for a specific vibration isolation device, at which the vibration isolation device is still functional as such, and an initiation value for the torsion (or a characteristic quantity) that is smaller in amount than the aforementioned limit value. When the initiation value is exceeded, a control signal is generated to apply such a torque which varies over time that the torsion of the vibration isolation device approaches the predetermined limit value asymptotically. The effective spring characteristic curve then has a comparatively "smooth" course. A preferred arrangement for vibration isolation in a motor vehicle provides that the electrical machine is arranged in the drive train between the internal combustion engine and the transmission in front of the vibration isolation device, for example the rotor of the electric machine is non-rotatably connected on the drive side to the crankshaft and the vibration isolation device between the electric machine and a shaft leading to the gearbox. If a soft adjustment is selected in this case, ie a relatively low spring stiffness (flat characteristic) of the elastic coupling element (s), then a large-amplitude excitation torque on the output side, as occurs, for example, during a load change, causes the vibration isolation device to stop. If an additional torque is applied in phase with and with the same sign as the excitation torque on the output side with the electric machine, the total and relative torque to be transmitted by the vibration isolation device is reduced. As a result, the torsion of the vibration isolation is also reduced, especially by an amount such that striking is prevented. As a result, the insulating property of the vibration isolation device is retained even with soft tuning, even for high excitation torques.

The additional torques applied by the electrical machine therefore depend on the load applied to the vibration isolation device. The torsion of the vibration isolation device or a quantity characterizing this torsion, for example the torque of the input shaft and / or the output shaft or the difference between these two torques, is preferably used as the control variable for characterizing the applied load. To detect these control variables, the control device preferably includes a rotation angle sensor assigned to the vibration isolation device for measuring the torsion of the vibration isolation device or one of the input shaft and / or the output shaft. ordered torque sensor. With the help of a suitable processing device, the manipulated variables necessary for controlling the electrical machine are then derived from the measured control variables. The vibration isolation device used in the invention can in principle be of any type known to the person skilled in the art. In a preferred variant, the vibration isolation device comprises at least two basic elements, of which one basic element is arranged on the drive side and the other basic element is arranged on the output side, and the two basic elements are coupled in a torsionally elastic manner via one or more elastic coupling elements, in particular helical, spiral or rubber springs.

As mentioned above, dynamic vibration isolation is particularly effective in the area of soft tuning, i.e. at low resonance frequency of the vibration system. Such coordination is preferably achieved in that flywheels are provided on one or each of the basic elements. In the case of two flywheel masses, this vibration isolation device then corresponds to the two-mass flywheel mentioned above. The flywheels can also be torsionally flexible, e.g. be coupled to the respective base element via elastomer layers.

In a particularly compact and therefore preferred construction of the arrangement according to the invention, the vibration isolation device is arranged integrated in the rotor of the electrical machine. For this purpose, the rotor of the electrical machine is designed, for example, as a hollow cylinder. The cavity in the rotor then serves to accommodate the vibration isolation.

In addition to the functions described above, the electrical machine of the arrangement for vibration isolation according to the invention can also perform other functions, for example that of a person Starter for starting, especially direct start, egg ^¬ nes internal combustion engine;

Generators for supplying electrical consumers and / or at least one vehicle battery; - regenerative vehicle brake;

Drive of a vehicle, in particular as a drive for support in addition to the internal combustion engine; and or

Damper for torque fluctuations of the shaft to which the rotor of the electrical machine is connected. The torque intervention of the electrical machine takes place on the side of the vibration isolation device on which the torque fluctuation occurs.

Further advantages and refinements of the invention result from the following description of preferred exemplary embodiments. In the description, reference is made to the attached schematic drawing. Show in the drawing:

FIG. 1 shows a schematic illustration of an exemplary device according to the invention for vibration isolation in the drive train of a motor vehicle; FIG. 2 shows a schematic torque-time diagram of an excitation torque on the output side of the arrangement according to FIG. 1 with and without the action of the device according to the invention; and FIG. 3 and 4 are each a schematic torque-angle diagram, which illustrates how the effective characteristic of the vibration isolation device can be influenced with the device according to the invention.

1 schematically shows an example of a device for vibration isolation according to the invention, as can be used in a motor vehicle.

The torque transmission path of the drive shown Stranges runs over a crankshaft 2 - driven by an internal combustion engine (not shown) - to an electrical machine 4, from there through a vibration isolation device 6 to a clutch 8 and via its clutch disc 9 to a transmission input shaft 10, which may have further elements leads to a (not shown here) transmission of the motor vehicle.

The electrical machine 4 has e.g. on the motor housing or on the vehicle body, a stator 12 which supports it in a rotationally fixed manner and a rotatable rotor 14 screwed to the crankshaft 2 on a hub 13. The rotor 14 has approximately the shape of a hollow cylinder with a U-shaped cross section. The electrically or magnetically effective part of the rotor 14 is located on the outside on the side of the hollow cylinder facing the stator 12. If a three-phase asynchronous machine is selected as the electrical machine 4 (although a machine of the direct current, alternating current, three-phase synchronous or linear type would also be possible), the outer part 16 of the rotor 14 forms a short-circuit squirrel-cage rotor with cage bars running in the axial direction.

The vibration isolation device 6 is accommodated in the cavity of the U-shaped rotor 14. This comprises an elastic coupling element 18 (shown schematically as a spring in FIG. 1) (consisting of several spiral or rubber springs), which is connected on the drive side to the rotor 14 and on the output side to a clutch input part 20 of the clutch 8. The rotor 14 and the clutch input part 20 - consequently primary and secondary side of the vibration isolation device 6 - are therefore coupled to one another in a torsionally elastic manner via the elastic coupling element 18. In this way, the drive side of the drive train is shielded from torque fluctuations on the output side (and vice versa), and the more effectively the coordination is selected, the more effectively, as already discussed in the introduction. The input part 20 of the clutch 8 (at the same time the secondary side of the vibration isolation device 6) is freely rotatable about the same axis as the rotor 14, for example in a ball bearing 21 seated on the inner leg of the U-shaped rotor 14, as shown in FIG. 1 is indicated schematically. The drive train shafts 2 and 10 in front of and behind the electrical machine 4 are guided in bearings.

Furthermore, a control device 24 for controlling the electrical machine 4 is provided. This control device 24 also comprises a pulse-controlled inverter 26 for generating rotating fields with current, freely adjustable frequency, phase and / or amplitude, with which the stator 12 of the electrical machine 4 is supplied for generating a rotating field in order to apply a torque to the rotor 14 - and thus on crankshaft 2 - to exercise. To monitor the current torsion, i.e. the twisting of the vibration isolation device 6, a rotary angle sensor 28 is e.g. arranged in the vicinity of the clutch input part 20 in order to continuously measure its current angle of rotation. The relative angle of rotation φ between the primary and secondary sides of the vibration insulation 6 can be determined by comparison with the current angle of rotation of the rotor 14 of the electrical machine 4 (which is measured by a similar angle encoder or determined from the currents back-induced in the stator 12). However, it is conceivable to have an angle of rotation sensor integrated in the vibration isolation device 6 with a transmitting part, e.g. on the clutch input part 20 and an opposite receiving part on the inside of the rotor.

According to the invention, the electrical machine 4 is controlled in order to specifically influence the insulation behavior of the vibration isolation device 6. In this case, the electrical machine 4 also transmits such torques with the same or opposite sign to the drive side in phase with any excitation torques on the output side Crankshaft 2 that the torsion of the vibration isolating device 6 induced by the excitation torques on the driven side is reduced or increased depending on the sign of the additional torques. If one then considers the relationship between excitation torques and the resulting torsion, the vibration isolation device 6 has a spring stiffness that is different from the specific characteristic of the elastic coupling element 18. This can be specifically coordinated by influencing the additional torques applied by the electrical machine 4, as the following examples show.

FIG. 2 shows an exemplary temporal course of a disturbance or excitation torque 30, as occurs on the output side of the arrangement according to FIG. 1, ie on the transmission input shaft 10 or on the clutch input part 20 (with clutch 8 open), for example when the load changes Internal combustion engine or in the event of an abrupt torque surge by the drive wheels. The excitation torque 30 is superimposed on an essentially uniform output torque 32. The excitation torque 30 on the output side is indeed “caught” by the vibration isolation device 6. However, if the amplitude of the excitation torque 30 reaches a maximum value M_ _ax , which depends on the spring constants of the elastic coupling element 18, the elastic coupling element 18 of the vibration isolation device 6 is deformed up to its stop, so that there is no longer any insulating property.

In order to avoid such a striking, the electric machine 4 is controlled according to the invention in such a way that it additionally applies a time-varying torque to the crankshaft 2 in phase with the excitation torque 30, which torque is proportional to the excitation torque 30 on the output side, for example by a factor k = 0.5 differs, and has the same sign. As a result, the relative torque transmitted between the input side and output side of the vibration isolation device 6 is reduced, so that the torsion of the vibration isolation device 6 is also reduced. As a result, the resulting torque applied to the vibration isolation device 6 is pressed below the maximum value M _max and has, for example, the curve 36 shown in FIG. 2. As a result, this resembles a harder vibration isolation device 6.

As described above, the control device 24 in FIG. 1 determines the instantaneous rotation or relative angle φ between the primary and secondary sides of the vibration isolation device 6, calculates the torque profile of the desired component 32 and the excitation component 30 from this and determines it with the aid of a Data stored in memory of M _max whether there is a risk of striking. If this is the case, the pulse inverter 26 generates an actuating signal for controlling the electrical machine 4, which applies an additional torque to the crankshaft 2 to reduce the torsion of the vibration isolation device 6.

Further control options of the arrangement in FIG. 1 are to be illustrated on the basis of the characteristic curve (torque versus angle of rotation) according to FIGS. 3 and 4 below. The solid line A corresponds to the specific spring characteristic of the elastic coupling element 18, which depends on the material, geometry, size, etc. In the case of an advantageous soft tuning, the elastic coupling element is chosen to be correspondingly soft, ie flat characteristic. If the electrical machine is now controlled in such a way that a positive or negative additional torque is superimposed in phase on an excitation torque on one side of the vibration isolation device, then the torsion of the vibration isolation device, and consequently the angle of rotation φ between the primary and secondary side , enlarged or reduced depending on the sign of the additional torque. If the additional torque applied is proportional to the excitation torque applied to the vibration isolation device 6 (as discussed above in FIG. 2), the shape of the spring remains Characteristic curve A obtained, only the slope of the characteristic curve becomes steeper or flatter, as shown in FIG. 3 with dashed line B (same sign as the excitation moment) or line C (opposite sign to the excitation moment). If the additional torque applied differs from the excitation torque by a non-constant factor, the shape of the spring line A is also changed, as is illustrated in FIG. 4. The characteristic curve A in turn corresponds to the specific spring characteristic of the elastic coupling element 18. In order to avoid that the vibration isolating device 6 comes into contact with large excitation amplitudes, the electrical machine 4 uses an increasing torsion of the vibration isolating device 6, ie with increasing angle of rotation φ disproportionately increasing torque applied with the same sign as the excitation torque. The effective spring characteristic curve then has the curve D shown in FIG. 4 and only asymptotically approaches the limit value φ _max . In addition to the limit value φ _max for the maximum permissible angle of rotation (stop angle), an initiation value φ _{x is also} stored in the control device 24, which is smaller than the limit value and at which an actuating signal for the electrical machine 4 is already generated. As a result, the vibration isolating device 6 is hereby tuned harder at a large angle of rotation φ.

The electrical machine 4 can also be controlled so that it makes the characteristic curve linear. For this purpose, after reaching a predetermined initiation value in phase with an excitation moment, it applies such time-varying additional moments with opposite signs that the effective spring characteristic curve E shown in FIG. 4 results. Then the vibration isolating device 6 has a lower spring stiffness for large excitation amplitudes compared to the specific spring characteristic A of the elastic coupling element 18. As a result, the vibration isolating device 6 is then made softer.

Claims

PATENT CLAIMS

1. Device for vibration isolation with: - at least one drive train coupled to a primary drive with an input shaft (2) and an output shaft (10); a vibration isolation device (6) coupling the input shaft (2) and the output shaft (10) in a torsionally elastic manner; An electrical machine (4), the rotor (14) of which can be connected in a rotationally fixed manner to the input shaft (2) or the output shaft (10) and whose stator (12) can be fixed against rotation, characterized in that a control device (24) controls the electrical

Controls the machine (4) so that it applies such time-varying torques to the input shaft

(2) or the output shaft (10) applies that the torsion of the vibration isolation device (6) induced by the other shaft (10 or 2) is reduced or increased.

2. Device according to claim 1, characterized in that the electrical machine (4) is arranged in the drive train of a motor vehicle between the internal combustion engine and the transmission in front of the vibration isolation device (6).

3. Apparatus according to claim 1 or 2, characterized in that the control device (24) uses the torsion of the vibration isolation device (6) itself as a control variable.

4. Apparatus according to claim 1 or 2, characterized in that the control device (24) as a control variable a characterizing the torsion, namely the torque of the input shaft (2) and / or the output shaft (10) or the difference between these two torques.

5. Apparatus according to claim 3 or 4, characterized labeled in ^¬ characterized in that said control means comprises: - at least one rotary angle encoder (30) for measuring the torsion of the vibration isolation

(6) or a torque sensor for measuring the torque of the input shaft and / or the output shaft or the difference of these two torques; and a processing device (26) for generating manipulated variables for the electrical machine

(4), which acts on the movement of the input shaft (2) or the output shaft (10).

6. Device according to one of the preceding claims, characterized in that the vibration isolation device (6) has at least two basic elements (14, 20), of which one basic element (14) on the drive side and the other basic element (20) arranged on the output side and the two basic elements (14, 20) via one or more elastic coupling elements (18), in particular helical, spiral or rubber springs, are coupled in a torsionally elastic manner.

7. The device according to claim 6, characterized in that one or more flywheels are arranged on one or each of the basic elements (14, 20).

8. Device according to one of the preceding claims, characterized in that the vibration isolation device (6) in the rotor (14) of the electrical machine (4) is integrated.

9. Device according to one of the preceding claims, characterized in that the control device (24) controls the electrical machine (4) so that it as a starter of an internal combustion engine, as a generator, as a generator vehicle brake, as a drive Vehicle or as an active damper for torque fluctuations of the shaft (2 or 10) to which the rotor (14) is connected, is used.

10. A method for operating a device for vibration isolation according to one of the preceding claims, wherein the electrical machine (4) on the input shaft (2) or the output shaft (10) applies such time-varying torques that the vibration isolation device (6) for the other shaft (10 or 2) induced torques has an increased or reduced effective spring stiffness.

11. The method according to claim 10, wherein the control variable for characterizing the load applied to the vibration isolation device (6) is the torsion of the vibration isolation device (6) and / or the torque of the input shaft (2) or the output shaft (10) or the difference between them two torques is measured and control variables for controlling the electrical machine (4) are derived therefrom.

12. The method according to claim 10 or 11, wherein the torques applied by the electrical machine (4) to the input shaft (2) or the output shaft (10) are proportional to the excitation torques of the other shaft (10 or 2) and the like or have the opposite sign.

13. The method according to claim 10 or 11, wherein the torques applied by the electrical machine (4) to the input shaft (2) or the output shaft (10) are a factor dependent on the instantaneous torsion from the excitation torques of the other shaft (10 or 2) differs.

14. The method of claim 13, wherein the trical of the elec ^¬ increase machine (4) applied torques with increasing torsion and in such a way entgegengeset- zes sign as the exciter have moments that the vibration isolation has a substantially linear spring characteristic.

15. The method according to claim 13, wherein the torques applied by the electrical machine (4) increase with increasing torsion and have the same sign as the excitation torques that the torsion of the vibration isolation device (6) does not exceed a predetermined limit value.

16. The method of claim 15, further comprising the following steps:

Determining a maximum permissible value (limit value) for the torsion of the vibration isolating device (6) or for a variable characterizing the torsion, and a corresponding initiation value which is smaller than the limit value;

Acquisition of actual values of the torsion or the quantity characterizing the torsion and comparison of the actual values with the corresponding one

Initiation value; and

Generating an actuating signal for applying such time-varying torques when the initiation value is exceeded that the torsion of the vibration isolation device

(6) approximates the specified limit asymptotically.