CRANKSHAFT ASSEMBLY WITH A CENTRIFUGAL PENDULUM ATTACHED TO THE CRANKSHAFT

Abstract

A crankshaft assembly for a motor vehicle drive train, including a crankshaft segment and a centrifugal pendulum secured thereon, which has a carrier secured to the crankshaft segment and at least one pendulum mass that moves relative to the carrier along a predetermined track. The crankshaft assembly has a friction unit connected to the carrier, which rests on the at least one pendulum mass such that, with a relative movement of the pendulum mass in relation to the carrier, the friction unit applies a frictional torque on the pendulum mass counteracting the relative movement, wherein the friction unit extends over a peripheral section of less than 360°.

Claims

1. A crankshaft assembly for a motor vehicle drive train, the crankshaft assembly comprising: a crankshaft segments; a centrifugal pendulum secured to the crankshaft segment, the centrifugal pendulum having a carrier that is secured to the crankshaft segment and at least one pendulum mass that moves relative to the carrier along a predetermined track; a friction device connected to the carrier which rests on the at least one pendulum mass such that, with a relative movement of the at least one pendulum mass in relation to the carrier, the friction device applies a frictional torque on the pendulum mass counteracting the relative movement; and the friction device extends over a peripheral section of less than 360°.

2. The crankshaft assembly according to claim 1, wherein the peripheral section is between 900 and 270°.

3. The crankshaft assembly according to claim 1, wherein the at least one pendulum mass extends over a predetermined peripheral section, and the peripheral section over which the friction device extends corresponds to the predetermined peripheral section.

4. The crankshaft assembly according to claim 1, wherein the friction device is segmented.

5. The crankshaft assembly according to claim 1, wherein the friction device has a friction element which rests on the pendulum mass, a receiving disc secured to the carrier and a spring element axially supporting between the friction element and the receiving disc, and at least one of the receiving disc, the friction element or the spring element are formed over a peripheral section of less than 360°.

6. The crankshaft assembly according to claim 1, wherein the friction device is arranged opposite a mass region of the crankshaft segment generating an imbalance in a circumferential direction.

7. The crankshaft assembly according to claim 6, wherein the friction device is axially symmetrical, and an axis of symmetry of the friction device corresponds to an axis of symmetry of the mass region.

8. The crankshaft assembly according to claim 1, wherein at least one of the centrifugal pendulum or the friction device is dimensioned in relation to the mass(es) and a position on the crankshaft segment is selected such that the at least one of the centrifugal pendulum or the friction device acts on the crankshaft segment to compensate for any imbalance when the crankshaft segment rotates.

9. The crankshaft assembly according to claim 8, wherein the crankshaft segment has a front-side recess for receiving at least part of at least one of the centrifugal pendulum or the friction device, and the front-side recess is dimensioned to compensate for any imbalance when the crankshaft segment rotates.

10. The crankshaft assembly according to claim 8, wherein a screw-on surface is formed on an axial end face of the crankshaft segment, on which the friction device and the centrifugal pendulum are attached via a common securing device.

11. A crankshaft assembly for a motor vehicle drive train, the crankshaft assembly comprising: a crankshaft segment; a centrifugal pendulum secured to the crankshaft segment, the centrifugal pendulum having a carrier that is secured to the crankshaft segment and two pendulum masses that move relative to the carrier along a predetermined track; and a friction element connected to the carrier which rests on the pendulum masses such that, with a relative movement of the pendulum masses in relation to the carrier, the friction element applies a frictional torque on the pendulum mass counteracting the relative movement.

12. The crankshaft assembly according to claim 11, wherein the friction element comprises a friction ring that is part of a friction device that extends over a peripheral section of less than 360° and presses the friction ring against the pendulum masses.

13. The crankshaft assembly according to claim 12, wherein the peripheral section is between 900 and 270°.

14. The crankshaft assembly according to claim 13, wherein the pendulum masses extend over a predetermined peripheral section, and the peripheral section over which the friction element extends corresponds to the predetermined peripheral section.

15. The crankshaft assembly according to claim 12, wherein the friction device includes a receiving disc secured to the carrier and a spring element axially supporting between the friction element and the receiving disc, and at least one of the receiving disc or the spring element are formed over a peripheral section of less than 360°.

16. The crankshaft assembly according to claim 12, wherein the friction device is arranged opposite a mass region of the crankshaft segment generating an imbalance in a circumferential direction.

17. The crankshaft assembly according to claim 16, wherein the friction device is axially symmetrical, and an axis of symmetry of the friction device corresponds to an axis of symmetry of the mass region.

18. The crankshaft assembly according to claim 12, wherein at least one of the centrifugal pendulum or the friction device is dimensioned in relation to the pendulum masses and a position on the crankshaft segment is selected such that the at least one of the centrifugal pendulum or the friction device acts on the crankshaft segment to compensate for any imbalance when the crankshaft segment rotates.

19. The crankshaft assembly according to claim 18, wherein the crankshaft segment has a front-side recess for receiving at least part of at least one of the centrifugal pendulum or the friction device, and the front-side recess is dimensioned to compensate for any imbalance when the crankshaft segment rotates.

20. The crankshaft assembly according to claim 18, wherein a screw-on surface is formed on an axial end face of the crankshaft segment, on which the friction device and the centrifugal pendulum are attached via a common securing device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The disclosure is explained below with the aid of drawings. In the figures:

[0055] FIGS. 1 and 2 show a longitudinal sectional view and a plan view of a crankshaft assembly in a first embodiment,

[0056] FIGS. 3 and 4 show a longitudinal sectional view and a plan view of a crankshaft assembly in a second embodiment,

[0057] FIGS. 5 and 6 show a longitudinal sectional view and a plan view of a crankshaft assembly in a third embodiment, and

[0058] FIGS. 7 to 9 show a longitudinal sectional view and a perspective view of a crankshaft assembly in a fourth embodiment.

DETAILED DESCRIPTION

[0059] The figures are only schematic in nature and serve only for understanding the disclosure. The same elements are provided with the same reference numerals. The features of the individual embodiments can be interchanged.

[0060] FIGS. 1 to 9 show different embodiments of a crankshaft assembly 1 for a motor vehicle drive train. The crankshaft assembly 1 has a crankshaft segment 2. The crankshaft segment 2 is, in particular, an axial section of a crankshaft. The crankshaft assembly 1 has a centrifugal pendulum 3 attached to the crankshaft segment. The centrifugal pendulum 3 serves to absorb a natural vibration of the crankshaft or a main order of excitation of the motor vehicle drive train.

[0061] The centrifugal pendulum 3 has a carrier 4 secured to the crankshaft segment. The carrier 4 is therefore attached to the crankshaft segment 2 in a rotationally fixed manner. The centrifugal pendulum 3 also has a pendulum mass 5. The pendulum mass 5 is attached to the carrier 4 so that it can move relative to the carrier 4 along a predetermined track. The absorbing effect of the centrifugal pendulum 3 is achieved by the relative movement between the pendulum mass 5 and the carrier 4. In the illustrated embodiments, the centrifugal pendulum 3 has a plurality of pendulum masses 5 which are arranged asymmetrically in the circumferential direction/over the circumference. The circumferential direction is defined in relation to an axis of rotation of the crankshaft segment 2.

[0062] The mass of the centrifugal pendulum 3 is dimensioned and its position on the crankshaft segment 2 is arranged in such a way that the centrifugal pendulum 3 acts on the crankshaft segment 2 to compensate for imbalance during operation, i.e., when the crankshaft segment 2 is rotating. The crankshaft segment 2 has a mass region 6 that generates an imbalance during operation. The mass region 6 is arranged eccentrically to the axis of rotation. The mass and the position of the centrifugal pendulum 3 is therefore matched to the mass and the position of the mass region 6. The centrifugal pendulum 3 (in particular its pendulum masses 5) are arranged opposite to the mass region 6 in the circumferential direction. The centrifugal pendulum 3 is arranged in the axial direction (relative to the axis of rotation) at the same height as the mass region 6. The pendulum masses 5 are radially spaced apart at the same distance from the axis of rotation as the mass region 6. In other words, the centrifugal pendulum 3 serves as an imbalance compensation element for the mass region 6. This means that the centrifugal pendulum 3 replaces an imbalanced mass for the crankshaft segment 2 (partially or completely).

[0063] The crankshaft assembly 1 has a friction device 7 connected to the carrier 4. The friction device 7 is attached to the carrier 4 and/or to the crankshaft segment 2 in a torque-proof manner. The friction device 7 rests against the at least one pendulum mass 5 in such a way that when the pendulum mass 5 moves relative to the carrier 4, the friction device 7 applies a frictional torque counteracting the relative movement to the pendulum mass 5. The friction device 7 has a friction element 8 in contact with the pendulum mass 5. The friction device 7 has a receiving disc 9 which is non-rotatably connected to the carrier 4. The friction element 8 is connected to the receiving disc 9 in a non-rotatable manner. The friction device 7 has a spring element 10 that is supported, in particular braced, axially between the friction element 8 and the receiving disc 9. The spring element 10 is designed, for example, as a disc spring or a wave spring. The spring element 10 applies a normal/axial force to the friction element 8, which presses the friction element 8 axially against the pendulum mass 5, so that when there is a relative movement between the friction element 8 secured to the carrier and the at least one pendulum mass 5, the friction torque that counteracts the relative movement occurs.

[0064] The crankshaft segment 2 has an imbalance compensation flange 11. The imbalance compensation flange 11 is located opposite the mass region 6 in the circumferential direction. The crankshaft segment 2 has a front-side recess 12 (in the imbalance compensation flange 11) for receiving at least part of the centrifugal pendulum 3, in particular the pendulum masses 5. The recess 12 is dimensioned in such a way that it has an imbalance-compensating effect when the crankshaft segment 2 rotates. In particular, the mass removed for the recess 12 corresponds to a mass added by the centrifugal pendulum 3.

[0065] The crankshaft segment 2 has a connection region 13 which is designed to attach an (axially adjacent) second crankshaft segment to it. The connection region 13 is arranged centrally on the crankshaft segment 2. The recess 12 is arranged radially outside the connection region 13. The crankshaft segment 13 has a centering region 14 on its radial outer circumference for receiving the centrifugal pendulum-type pendulum 3 in a centered manner. The crankshaft segment 13 has a screw-on region/surface 15 on an axial end face, to which the centrifugal pendulum 3/the carrier 4 is secured. The screw-on surface 15 is arranged radially outside the connection region 13. The centrifugal pendulum 3 is attached axially to the screw-on surface 15 via a securing device 16, in particular in the form of a plurality of screws. For this purpose, threaded bores are provided in the screw-on surface 15, into which the securing device 16 is screwed.

[0066] The receiving disc 9 of the friction device 7 is designed as a beveled sheet metal component. The receiving disc 9 has an (inner) first radial section 17 serving as a securing section. The radial section 17 is firmly attached to the carrier 4 and the crankshaft segment 2 via the securing device. From a radially outer end of the first radial section 17, an axial section 18 extends in the axial direction away from the crankshaft segment 2/the screw-on surface 15. The axial section 18 extends radially within the pendulum masses 5. An (outer) second radial section 19 extends outwards in the radial direction from an axially distanced end of the axial section 18. As a result, the receiving disc 9 has an S-shape at least in sections. The spring element 10 and/or the friction element 8 are supported axially on the receiving disc 9 in the region of the second radial section 19. An axial projection 20 extends in the axial direction toward the pendulum masses 5 from a radially outer end of the second radial section 19. The spring element 10 and/or the friction element 8 are supported on the axial projection 20 in the circumferential direction.

[0067] In the embodiment shown, the centrifugal pendulum 3 has a plurality of pendulum mass packages. Each pendulum mass package has two pendulum masses 5, which are held by one or more spacing elements 21 spaced axially parallel. The two pendulum masses 5 are connected to one another by a rivet 22, for example.

[0068] FIGS. 1 and 2 show a first embodiment of the crankshaft assembly 1. FIG. 1 shows a plan view without the friction device 7. The carrier 4 has a central through hole 23 via which the carrier 4 is centered on the centering region 14. In the first embodiment, the friction element 8 is designed as a friction ring running in the circumferential direction. The friction element 8 has form-fitting elements 24 on its radial inner side, which engage with corresponding recesses 25 in the receiving disc 9 for form-fitting anti-rotation protection. The friction element 8 is thus fastened radially on the inside. The receiving disc 9 is designed to run around in the circumferential direction. The second radial section 19 and/or the axial projection 20 is designed rotationally symmetrical.

[0069] FIGS. 3 and 4 show a second embodiment of the crankshaft assembly 1. Only differences from the first embodiment are explained below. The friction device 7 has an additional cover disc 26 which is arranged in the axial direction between the spring element 10 and the friction element 8. The crankshaft assembly 1 has a burst protection 27. The burst protection 27 surrounds the centrifugal pendulum 3 radially on the outside. As a result, when the centrifugal pendulum 3 rotates, loose components are caught by the burst protection 27. Burst protection 27 is formed by the receiving disc 9. The second radial section 19 is extended radially outwards, so that it protrudes radially outwards beyond the pendulum masses 5. From a radially outer end of the second radial section 19, an outer axial section 28 extends in the axial direction towards the crankshaft segment 2. The outer axial section 28 extends axially beyond the pendulum masses 5. This means that the axial projection 20 is lengthened in the axial direction, at least in the peripheral region of the pendulum masses 5, in order to form the outer axial section 28. The pendulum masses 5 are accordingly enveloped by the receiving disc 9. To form the burst protection 27, the receiving disc 9 has a beveled U-shape, which axially encompasses the pendulum masses 5. The friction element 8 is fastened radially on the outside of the receiving disc 9 to prevent rotation. For example, the friction element 8 and the receiving disc 9 engage with one another. The friction element 8 is supported in a radially inner region on the cover disc 26 and in a radially outer region on the receiving disc 9. The carrier 4 extends approximately in the shape of a crescent in the region of the pendulum masses 5.

[0070] FIGS. 5 and 6 show a third embodiment of the crankshaft assembly 1. Only differences from the first or second embodiment are explained below. In the third embodiment, the friction device 7, in particular the receiving disc 9, the friction element 8, the spring element 10 and/or the cover disc 26, extends over a peripheral section of less than 360°. This means that the friction device 7 is not designed to be completely circumferential in the circumferential direction. The peripheral section is between 90° and 270°, in particular between 180° and 270°. The peripheral section essentially corresponds to a predetermined peripheral section over which the pendulum masses 5 extend. The friction device 7 is segmented, in the embodiment shown in the form of a circular (ring) sector. The friction device 7 can be regarded as part of the centrifugal pendulum 3, so that the configuration, dimensioning and positioning of the friction device 7 also has an imbalance-compensating effect on the crankshaft segment 2 during operation.

[0071] FIGS. 7 to 9 show a fourth embodiments of the crankshaft assembly 1. Only differences from the first, second or third embodiment are explained below. In the fourth embodiment, the carrier 4 of the centrifugal pendulum 3 is extended on a side opposite the pendulum masses 5 in the circumferential direction in such a way that the friction device 7 rests against the carrier 4. The carrier 4 thus extends in the radial direction and circumferential direction up to the mass region 6. The carrier 4 has a connecting section in the form of an axial beveled section 29 which connects a first radial section 30 adjacent to the pendulum masses 5 in the circumferential direction to a second radial section 31 adjacent to the mass region 6 in the circumferential direction. The second radial section 31 is enveloped in the direction of the friction device 7. The first radial section 30 is arranged spaced apart axially and parallel to the second radial section 31. The first radial section 30 serves as a bearing section for receiving the pendulum masses 5. The second radial section 31 serves as a contact section against which the friction device 7 rests. In particular, the friction element 8 rests on the same axial side in one peripheral section against the second radial section 31 and in another peripheral section against the pendulum masses 5. The carrier 4 has a through hole 32. The through hole 32 is formed eccentrically. In a region adjacent to the pendulum masses 5 in the circumferential direction, a radial inner side/surface of the carrier 4 rests against the centering region 14. The through-hole 32 extends further radially outwards in a region adjacent to the mass region 6 in the circumferential direction, so that the carrier 4 rests against the crankshaft segment 2 only over a peripheral section that is less than 360°.

LIST OF REFERENCE SYMBOLS

[0072] 1 Crankshaft assembly [0073] 2 Crankshaft segment [0074] 3 Centrifugal pendulum [0075] 4 Carrier [0076] 5 Pendulum mass [0077] 6 Mass region [0078] 7 Friction device [0079] 8 Friction element [0080] 9 Receiving disc [0081] 10 Spring element [0082] 11 Imbalance compensation flange [0083] 12 Recess [0084] 13 Connection region [0085] 14 Centering region [0086] 15 Screw-on surface [0087] 16 Securing device [0088] 17 First radial section [0089] 18 Axial section [0090] 19 Second radial section [0091] 20 Axial projection [0092] 21 Spacing element [0093] 22 Rivet [0094] 23 Through hole [0095] 24 Form-fitting element [0096] 25 Recess [0097] 26 Cover disc [0098] 27 Burst protection [0099] 28 Axial section [0100] 29 Beveled section [0101] 30 First radial section [0102] 31 Second radial section [0103] 32 Through hole