Powertrain for a motor vehicle

Abstract

Drive train (1, 1a) for a motor vehicle with an internal combustion engine (2) having a predetermined number of cylinders, some of which are designed to be deactivated, and a crankshaft (3) driven by the cylinders and a torsional vibration damping device (6, 6a) associated with the crankshaft (3) for damping torsional vibrations of the internal combustion engine (2) with a first vibration order when operating with all cylinders and a second vibration order when operating with only some of the cylinders, wherein the torsional vibration damping device (6, 6a) includes a single support flange (18, 18a) on which two torsional vibration dampers (50, 50a, 51, 51a, 51b), each tuned to a specific vibration order, are mounted and wherein the torsional vibration dampers (50, 50a, 51) are formed from two centrifugal pendulums (29, 29a, 30, 30a). where arranged distributed around the circumference,Eccentric to an axis of rotation (d) of the torsional vibration damping device (6, 6a), pendulum mass units (31, 31a, 32, 32a) of both centrifugal pendulums (29, 29a, 30, 30a) are arranged in a plane perpendicular to the axis of rotation (d) along an angle of oscillation, and the pendulum masses (35, 35a) forming the pendulum mass units (31, 31a, 32, 32a) arranged on both sides of the support flange (18, 18a) of one centrifugal pendulum (29, 29a) have a greater thickness (s1) than the thickness (s2) of the pendulum masses (36, 36a) of the other centrifugal pendulum (30, 30a), characterized in that the pendulum masses (35, 35a, 36, 36a) of the two centrifugal pendulums (29, 29a) forming the pendulum mass units (31, 31a, 32, 32a) are arranged on both sides of the support flange (18, 18a). (29, 29a, 30, 30a) are of such different lengths when viewed in the circumferential direction that the shorter pendulum masses (35, 35a) have a greater thickness (s1) than the thickness (s2) of the longer pendulum masses (36, 36a).

Description

[0001] The invention relates to a drive train for a motor vehicle with an internal combustion engine with a predetermined number of cylinders, some of which are designed to be switchable off, and a crankshaft driven in rotation by the cylinders, as well as a torsional vibration damping device assigned to the crankshaft for damping torsional vibrations of the internal combustion engine with a first vibration order when operating the engine with all cylinders and a second vibration order when operating the engine with only some of the cylinders.

[0002] Internal combustion engines whose cylinders are deactivated during certain operating processes, for example, during partial load operation, are known, for example, from WO 2011 / 160 619 A1. Due to the operating principle of such internal combustion engines, the rotational irregularities in the torque transmitted via the crankshaft of internal combustion engines with cylinders change the vibration orders of the occurring torsional vibrations. Therefore, torsional vibration isolation devices are known, for example, from DE 10 2012 221 544 A1, in which different arrangements of one or more centrifugal pendulums in conjunction with torsional vibration dampers are proposed for vibration isolation of different vibration orders.

[0003] A drive train designed according to the features of the preamble of claim 1 is disclosed in DE 10 2014 214 523 A1. The pendulum masses installed therein are designed differently from one another with regard to their extension in the circumferential and / or axial directions, so that one of the pendulum masses is designed to dampen a first excitation order of the internal combustion engine that can be introduced into the pendulum flange. The other pendulum mass is designed to dampen a second excitation order of the internal combustion engine that can be introduced into the pendulum flange.

[0004] DE 10 2014 217 470 A1 discloses another damper device of this type. DE 10 2012 205 793 A1 discloses a drive train for a vehicle with an internal combustion engine that can be switched between operating modes of different power levels, and a torsional vibration damping arrangement.

[0005] The object of the invention is the further development of a drive train with an internal combustion engine with deactivatable cylinders and a torsional vibration damping device for vibration isolation of different vibration orders.

[0006] The object is solved by the subject matter of claim 1. The dependent claims represent advantageous embodiments of the subject matter of claim 1.

[0007] According to the invention, the pendulum masses of the two centrifugal pendulums, viewed in the circumferential direction, are designed to be of different lengths such that the shorter pendulum masses have a greater strength than the strength of the longer pendulum masses.

[0008] The proposed drive train is intended for a motor vehicle and contains an internal combustion engine which drives the drive wheels of the motor vehicle via a transmission. Depending on the design of the transmission, torque transmission devices such as a friction clutch, a dual clutch, a hydrodynamic torque converter and / or, if appropriate in a hybrid drive train, an electric motor can be provided between the internal combustion engine and the transmission. The internal combustion engine contains a predetermined number of cylinders, at least two cylinders, preferably four or six cylinders, some of which are designed to be deactivated. For example, in an internal combustion engine with four cylinders, two cylinders can be deactivated. In an internal combustion engine with six cylinders, for example, two or three cylinders can be deactivated.The deactivatable cylinders serve primarily to save fuel and thus reduce pollutant emissions during partial load operation. The cylinders drive a crankshaft. A torsional vibration dampening device for dampening torsional vibrations of the internal combustion engine is arranged concentrically or axially parallel to the crankshaft, meaning its effect is linked to the crankshaft.

[0009] At least one torsional vibration damper, for example a split flywheel, a torsional vibration damper in a clutch disc, or a torque converter, can be connected in series upstream and / or downstream and / or in parallel to the torsional vibration damping device. The torsional vibration damping device is designed to dampen torsional vibrations of a first vibration order when operating with all cylinders and a second vibration order when operating with only some of the cylinders. For example, an internal combustion engine with four cylinders has a first vibration order O1 = 2 when operating with all cylinders and components of a first and a second vibration order O2 = 1 and O1 = 2 when partially deactivated.In contrast, for example, in an internal combustion engine with six cylinders, the first vibration order O1 = 3 when operating with all cylinders, while when three cylinders are deactivated, components of the first and second vibration orders O1 = 3 and O2 = 1.5 occur. The torsional vibration damping device is therefore designed to at least partially dampen both of the predominantly occurring vibration orders. For this purpose, the torsional vibration damping device contains a single support flange on which two torsional vibration dampers, each tuned to a specific vibration order, are mounted.

[0010] At least one of the torsional vibration dampers is designed as a speed-adaptive centrifugal pendulum. A centrifugal pendulum is understood to mean pendulum mass units distributed around the circumference, which are arranged so as to be displaceable relative to the support flange. The pendulum device is arranged on pivot bearings, which allow the pendulum mass units to oscillate about at least one pendulum axis arranged eccentrically to the axis of rotation. For this purpose, the pendulum mass units are mounted on the support flange by means of rolling elements such as rollers. To form a pivot bearing, a rolling element rolls on raceways of the support flange and the pendulum mass units. The raceways are formed in cutouts from the support flange and the pendulum mass units and, through their respective shape, determine the course of the pendulum path of the pendulum mass unit relative to the support flange in the centrifugal force field of the rotating support flange.The pendulum masses are accelerated outwards in the centrifugal force field and deflected when torsional vibrations occur, so that they absorb and release energy and thus calm the support flange and thus the crankshaft effectively connected to it by absorbing the torsional vibrations. The pendulum mass units can each be mounted on two pivot bearings arranged in the circumferential direction on the support flange, whereby the pivot bearings can represent a parallel or trapezoidal thread guide, based on the consideration of a thread pendulum. Designing the raceways according to a trapezoidal thread guide can increase the absorption effect by causing the pendulum mass units to rotate in addition to the pendulum movement. Furthermore, by designing the raceways accordingly, non-linear, non-circular or free-form guides for the pendulum mass units can be provided.

[0011] The support flange is formed from a central disk part, with pendulum masses arranged on both sides of the support flange. Axially opposite pendulum masses each form a pendulum mass unit. These are firmly connected to one another by means of connecting means that pass through corresponding recesses in the support flange. Alternatively, the support flange can be formed from two side parts that are axially spaced apart in the area where pendulum mass units are accommodated. Each side part, with its own pendulum mass unit, forms the pivot bearing. The side parts are connected radially outside or radially inside the pendulum mass units to the crankshaft or to a component operatively connected to it. When a centrifugal pendulum absorber is combined with a torsional vibration damper, the latter can be effectively connected to the torsional vibration damper on the input side or output side by means of the support flange.The support flange can form a component of the torsional vibration damper, for example a flange part for the output-side loading of the spring device of the torsional vibration damper.

[0012] The torsional vibration dampers are formed from two centrifugal pendulums, with pendulum mass units distributed around the circumference and eccentrically arranged to a rotational axis of the torsional vibration damping device in a plane perpendicular to the rotational axis, capable of oscillating along an oscillation angle. The centrifugal pendulums are mounted on a single support flange. The pendulum mass units are formed from pendulum masses arranged on either side of a single support flange. The pendulum mass units or pendulum masses of the two centrifugal pendulums can be arranged on the same or different diameters. The strength of the pendulum masses of both centrifugal pendulums is different. The pendulum masses of the two centrifugal pendulums are of the same or different lengths viewed in the circumferential direction. The mass of the pendulum masses or pendulum mass units of the two centrifugal pendulums is different.The possible oscillation angles of the pendulum mass units can be the same or different. According to the invention, the shorter pendulum masses have a greater strength than the longer pendulum masses. The longer pendulum masses are designed for a larger oscillation angle than the oscillation angles of the pendulum mass units with the shorter pendulum masses. The centrifugal pendulum with the longer pendulum mass units is designed for operation of the internal combustion engine with all cylinders.

[0013] In addition to the proposed drive train itself, the proposed torsional vibration damping device can also be provided as the subject of the invention. The invention is described with reference to the Fig. 1 to 5 are explained in more detail. They show: Fig. 1 shows the part of a drive train with the upper part of a torque transmission device arranged around a rotational axis and containing a torsional vibration damping device in a sectional view, Fig. 2 the torsional vibration damping device of the Fig. 1 in 3D view, Fig. 3 the torsional vibration damping device of the Fig. 1 in section through a pendulum mass unit of the first centrifugal pendulum, Fig. 4 the torsional vibration damping device of the Fig. 1 in section through a pendulum mass unit of the second centrifugal pendulum, Fig. 5 a compared to the drive train of the Fig. 1 modified drive train with modified torsional vibration damping device in the same sectional view and Fig. 6 compared to the drivetrains of the Fig. 1 and Fig. 5 modified drive train not affected by the invention with modified torsional vibration damping device in the same sectional view.

[0014] The Fig. 1 shows a section of the drive train 1 with the symbolically represented internal combustion engine 2 and the torque transmission device 4 connected to the crankshaft 3 of the latter and is arranged around the axis of rotation d of the crankshaft 3 and is shown in section only above this.

[0015] The torque transmission device 4 contains the torsional vibration damper 5, the torsional vibration cancellation device 6, and the dual clutch 7. The torsional vibration damper 5 is designed as a split flywheel, the input part 8 of which forms a primary flywheel mass and the side parts 9, 10 of which accommodate the spring device 12, forming an annular chamber 11 and, by means of non-visible stampings, assumes the input-side loading of the spring device 12. The output part 13 of the torsional vibration damper 5 contains the hub 14, which is rotationally connected to the input part 15 of the dual clutch 7. The housing part 16 is rotatably mounted on the hub 14, and the input part 15 is rotatably mounted on the housing part 16. The hub flange 17 is rotationally connected to the hub 14 and is toothed. The support flange 18 is received radially on the outside of the hub flange 17, for example riveted by means of the rivet 19 radially inside the torsional vibration damping device 6.The support flange 18 has arms 20 radially engaging into the annular chamber 11 outside the torsional vibration damping device 6 for the output-side loading of the spring device 12 formed, for example, from arc springs arranged over the circumference in the circumferential direction.

[0016] The dual clutch 7 is formed by two friction clutches 21, 22 arranged radially one above the other, here designed as wet clutches. These clutches are arranged parallel to each other and enable a switchable frictional engagement between the input part 15 and its output parts 23, 24 by means of the disk packs 25, 26. The output parts 23, 24 are each rotationally connected, for example, by toothing, to one of the transmission input shafts 27, 28 of a dual clutch transmission (not shown in detail).

[0017] The torsional vibration damping device 6 is arranged radially between the arms 20 and the hub flange 17 on the support flange 18. As can be seen from the 3D representation of the Fig. 2, the torsional vibration damping device 6, arranged radially inside the arms 20, contains the two torsional vibration dampers 50, 51 in the form of two centrifugal pendulums 29, 30, whose pendulum mass units 31, 32, arranged alternately around the circumference, are formed from axially opposite pendulum masses 35, 36 arranged on both sides of the support flange 18 and connected to one another by means of connecting means 33, 34. The connecting means 33, 34 extend through recesses 37, 38 of the support flange 18 to enable a pendulum displacement of the pendulum mass units 31, 32 relative to the support flange 18 within the set oscillation angle. The pendulum movement of the pendulum mass units 31, 32 relative to the support flange 18 is achieved by means of the pivot bearings 39, 40.In this case, recesses with raceways are provided on the support flange 18 and on the pendulum masses 35, 36 in a manner known per se, which, depending on their design, specify the oscillation angle and the pendulum path of the pendulum mass units 31, 32.

[0018] By specifying the masses of the pendulum mass units 31, 32, their oscillation angle and pendulum path, the oscillation order to be compensated is set. The centrifugal pendulums 29, 30 are adjusted to different oscillation orders during operation of the internal combustion engine 2 ( Fig. 1) with all cylinders or with partially deactivated or idle cylinders. The radially opposite pendulum masses 35 of the centrifugal pendulum 29 have a shorter length l1 and a greater thickness s1 compared to the length l2 and thickness s2 of the pendulum masses 36 of the centrifugal pendulum 30. Furthermore, the intended oscillation angle of the pendulum mass units 32 is greater than the oscillation angle of the pendulum mass units 31. In the exemplary embodiment shown, the centrifugal pendulum 29 is tuned to the oscillation order of the internal combustion engine when operating with all cylinders. This means that the centrifugal pendulum 29 is tuned to oscillation order O1 = 2 for an internal combustion engine with four cylinders and to oscillation order O1 = 3 for an internal combustion engine with six cylinders.The centrifugal pendulum 30 is tuned to a partial operation of the cylinders of an internal combustion engine, for example, in an internal combustion engine with four cylinders and two deactivated cylinders, to the oscillation order O2 = 1, and in an internal combustion engine with six cylinders and three deactivated cylinders, to the oscillation order O2 = 1.5. During partial operation with deactivated cylinders, both centrifugal pendulums 29, 30 can be proportionally effective due to the forces occurring on the internal combustion engine.

[0019] The Fig. 3 and Fig. 4 show the upper part of the torsional vibration damper 5 with the torsional vibration damping device 6 along different cutting lines. Fig. 3 shows the torsional vibration damper 5 along a section line through the pendulum masses 36 of the pendulum mass unit 32 of the centrifugal pendulum 30. The Fig. Figure 4 shows the torsional vibration damper 5 along a section line through the pendulum masses 35 of the pendulum mass unit 31 of the centrifugal pendulum 29. The comparison shows the different thicknesses s1, s2 of the pendulum masses 35, 36. The section lines each pass through one of the connecting elements 33, 34. The pendulum masses 35, 36 are axially spaced from one another by means of the intermediate plates 41, 42 and the sliding disks 43, 44. A stop buffer 45, 46 is attached radially inside to each of the intermediate plates 41, 42 to prevent or at least dampen noise resulting from the pendulum mass units 31, 32 with the pendulum masses 35, 36 falling back onto the inner sides of the recesses 37, 38 in the event of insufficient centrifugal force.

[0020] The Fig. 5 shows a drive train 1 of the Fig. 1 modified drive train 1a in the same illustration, wherein the spring device 12a is acted upon on the output side by a separate flange part 47a with arms 20a, which is formed separately from the support flange 18a of the torsional vibration damping device 6a. The support flange 18a and the flange part 47a are jointly received on the hub flange 17a by means of the rivet 19a. The two torsional vibration dampers 50a, 51a in the form of two centrifugal pendulums 29a, 30a of the torsional vibration damping device 6a are arranged radially one above the other and are tuned to different vibration orders of the internal combustion engine, for example when operating with all or only some of the existing cylinders. The pendulum mass units 31a, 32a of the two centrifugal pendulums 29a, 30a are pivotably mounted on the single support flange 18a.The pendulum masses 35a, 36a of the pendulum mass units 31a, 32a are each arranged on either side of the support flange 18a, and axially opposite pendulum masses 35a, 36a are connected to one another. In the illustrated embodiment, the radially inner pendulum masses 35a of the centrifugal pendulum 29a are provided with the greater strength s1 than the pendulum masses 36a of the centrifugal pendulum 30a, which have the strength s2. Furthermore, the pendulum mass units 31a, 32a can have the same or different lengths and the same or different adjustable oscillation angles in order to achieve a design for the required, different oscillation orders.

[0021] The centrifugal pendulum 29a of the illustrated embodiment is arranged radially between the riveted connection of the support flange 18a to the hub flange 17a by means of the rivet 19a and the spring device 12a of a corresponding torsional vibration damper, and axially overlaps the spring device 12a. For this purpose, the flange part 47a is provided with a recess 48a.

[0022] The centrifugal pendulum 30a is arranged at the radial level of the spring device 12a and axially between the housing part 16a of a corresponding dual clutch and the side part 10a of the input part 8a of the torsional vibration damper. To protect the surroundings from radially outwardly accelerated components of a potentially bursting centrifugal pendulum 30a, the burst protection 49a is provided radially outside the centrifugal pendulum 30a and axially overlaps it. In the illustrated embodiment, the burst protection 49a is connected to the side part 10a, for example, by welding.

[0023] The Fig. 6 shows a drive train 1b not having the features of the invention in the same illustration. In contrast to the drive train 1a of Fig. 5, only one of the torsional vibration dampers 50b is designed as a centrifugal pendulum 29b to form the torsional vibration damping device 6b. The other, radially outer torsional vibration damper 51b is designed as a mass ring 52b. The mass accumulation for this purpose is achieved in the illustrated embodiment by simply folding over the outer circumference of the support flange 18b. Otherwise, the design of the drive train 1b corresponds to the drive train 1a of Fig.5. The radially outer torsional vibration damper 51b is preferably designed for the vibration order of the internal combustion engine when all cylinders are operating, while the radially inner torsional vibration damper 50b, designed as a centrifugal pendulum 29b, is designed for the vibration order when the cylinders of the internal combustion engine are partially deactivated. List of reference symbols 1 drivetrain 1a drivetrain 1b Drivetrain 2 internal combustion engine 3 Crankshaft 4 Torque transmission device 5 torsional vibration dampers 6 Torsional vibration damping device 6a Torsional vibration damping device 6b Torsional vibration damping device 7 Dual clutch 8 Entrance part 8a Entrance part 9 Side panel 10 side panel 10a side part 11 Annular chamber 12 Spring device 12a Spring device 13 Output part 14 Hub 15 Entrance part 16 Housing part 16a Housing part 17 Hub flange 17a Hub flange 18 Support flange 18a support flange 18b support flange 19 rivet 19a rivet 20 arms 20a Arm 21 Friction clutch 22 Friction clutch 23 Output part 24 Output part 25 slat pack 26 slat pack 27 Gearbox input shaft 28 Gearbox input shaft 29 centrifugal pendulum 29a Centrifugal pendulum 29b Centrifugal pendulum 30 centrifugal pendulums 30a centrifugal pendulum 31 pendulum mass unit 31a Pendulum mass unit 32 pendulum mass unit 32a Pendulum mass unit 33 lanyards 34 lanyards 35 pendulum mass 35a Pendulum mass 36 pendulum mass 36a Pendulum mass 37 recess 38 recess 39 swivel bearings 40 swivel bearings 41 Intermediate plate 42 intermediate plate 43 Sliding disc 44 sliding disc 45 stop buffers 46 stop buffers 47a Flange part 48a indentation 49a Burst protection 50 torsional vibration dampers 50a torsional vibration damper 50b torsional vibration damper 51 torsional vibration dampers 51a torsional vibration damper 51b torsional vibration damper 52b Massering d axis of rotation l1 length l2 length s1 strength s2 strength

Claims

[1] Drive train (1, 1a) for a motor vehicle with an internal combustion engine (2) with a predetermined number of cylinders, some of which are designed to be switchable off, and with a crankshaft (3) driven in rotation by the cylinders, and with a torsional vibration damping device (6, 6a) assigned to the crankshaft (3) for damping torsional vibrations of the internal combustion engine (2) with a first vibration order when operating the engine with all cylinders and a second vibration order when operating the engine with only some of the cylinders, wherein the torsional vibration damping device (6, 6a) contains a single support flange (18, 18a) on which two torsional vibration dampers (50, 50a, 51, 51a, 51b) are received, each tuned to a vibration order, and wherein the torsional vibration dampers (50, 50a, 51) consist of two centrifugal pendulums (29, 29a, 30, 30a), wherein arranged over the circumference,eccentrically to a rotational axis (d) of the torsional vibration damping device (6, 6a) in a plane perpendicular to the rotational axis (d) along an oscillation angle, oscillatable pendulum mass units (31, 31a, 32, 32a) of both centrifugal pendulums (29, 29a, 30, 30a) are arranged, and each pendulum mass forming the pendulum mass units (31, 31a, 32, 32a) arranged on both sides of the support flange (18, 18a) has a greater strength (s1) than the strength (s2) of the pendulum masses (36, 36a) of the other centrifugal pendulum (30, 30a), characterized by that the pendulum masses (35, 35a, 36, 36a) of the two centrifugal pendulums (29, 29a, 30, 30a) are of different lengths when viewed in the circumferential direction, such that the shorter pendulum masses (35, 35a) have a greater strength (s1) than the strength (s2) of the longer pendulum masses (36, 36a). [2] Drive train (1) according to claim 1, characterized bythat the pendulum mass units (31, 32) are arranged on the same diameter. [3] Drive train (1a) according to claim 1, characterized by that the pendulum mass units (32a) of one centrifugal pendulum (30a) are arranged on a larger diameter than the pendulum mass units (31a) of the other centrifugal pendulum (29a). [4] Drive train (1, 1a) according to claim 1, characterized by that the pendulum mass units (32, 32a) with the longer pendulum masses (36, 36a) are designed for a larger oscillation angle than the oscillation angles of the pendulum mass units (31, 31a) with the shorter pendulum masses (35, 35a). [5] Drive train (1, 1a) according to one of claims 1 to 4, characterized by that the centrifugal pendulum (30, 30a) with the longer pendulum mass units (32, 32a) is designed for operation of the internal combustion engine with all cylinders.

Images