centrifugal pendulum

Abstract

Centrifugal pendulum (1) particularly in a drive train of a motor vehicle with a rotary-driven receiving part (3) and pendulum masses (5, 6) distributed around the circumference of the receiving part, which are pivotably arranged relative to the receiving part (3) by means of rolling elements (7) rolling in raceways (10, 11) provided in these and complementarily in the receiving part (3), wherein the raceways (10, 11) have raceway segments (12, 13, 14, 15) that are asymmetrically formed relative to each other in the circumferential direction with respect to a central position, wherein each of the raceways (10, 11) has an arcuate raceway segment (12, 14) and a circular raceway segment (13, 15) in the circumferential direction, which merge into each other in the central position, wherein the arcuate raceway segment has an arcuate extension (R) a+aΔ , R s+sΔ ) has a circular segment of the track, wherein the circular segment has a radius (R a , R s) exhibits, wherein the arc-shaped extension (R a+aΔ , R s+sΔ ) starting from the radius (R a , R s ) of the circular segment-shaped track segment extended with increasing swing angle.

Description

[0001] The invention relates to a centrifugal pendulum, in particular in a drive train of a motor vehicle, with a rotary-driven receiving part and pendulum masses distributed around the circumference of the receiving part, which are arranged pivotably relative to the receiving part by means of rolling elements rolling in these and complementarily in the receiving part.

[0002] Centrifugal pendulums of this type are preferably used in the drive trains of motor vehicles for isolating torsional vibrations introduced into the drive train by an internal combustion engine, for example a diesel engine, superimposed on the applied drive torque. These pendulums are known from the prior art, either alone or in combination with torsional vibration dampers such as dual-mass flywheels. For example, a torsional vibration damper with a centrifugal pendulum disclosed in DE 10 2009 021 355 A1 shows a receiving part rotating about an axis of rotation with several pendulum masses distributed around the circumference, which can be pivoted circumferentially relative to the receiving part by means of rolling elements. The rolling elements roll on raceways in the pendulum masses and in the receiving part, which are shown in cutouts.By designing two raceways in each pendulum mass and complementary raceways in the receiving part, the pendulum masses can perform a limited pendulum motion relative to the receiving part. Under the influence of centrifugal force, the center of gravity of the pendulum masses shifts relative to the receiving part, resulting in rotationally adaptive vibration damping when torsional vibrations are introduced. The pendulum masses are bifilarly suspended from the receiving part. This means that both rolling elements of a pendulum mass are displaced parallel to each other about a pendulum axis, primarily transversely. Consequently, the pendulum masses must be spaced apart from each other, resulting in pendulum masses with low mass and therefore reduced restoring torque.

[0003] From GB 598 811, a centrifugal pendulum is known in which embodiments are provided in which the contact points of the two rolling elements associated with a pendulum mass are trapezoidally arranged with respect to the respective circular segment-shaped cutouts in the receiving part and the pendulum mass, so that the pendulum masses are each pivotable about a single pendulum axis, resulting in transverse and radial movement. It has been found that with a circular segment-shaped design of the raceways, the movement of the two rolling elements is unequal and slipping and sliding conditions can occur.

[0004] Other devices are known, for example, from DE 100 59 101 A1, DE 196 54 915 A1, DE 198 31 160 A1 and DE 10 2008 005 138 A1.

[0005] The object of the invention is therefore to propose a centrifugal pendulum with improved utilization of the installation space and / or improved vibration damping, particularly against the background of avoiding or at least reducing sliding movement of the rolling elements in the raceways.

[0006] The problem is solved by a centrifugal pendulum, particularly in a drive train of a motor vehicle, with a rotary-driven receiving part and pendulum masses distributed around the circumference of the receiving part, which are pivotably arranged relative to the receiving part by means of rolling elements rolling in these and complementarily in the receiving part, wherein the running tracks have raceway segments that are asymmetrically designed relative to each other with respect to a central position in the circumferential direction.

[0007] Such centrifugal pendulums can be provided, for example, individually or in conjunction with a torsional vibration damper, such as a split flywheel in the drivetrain. For instance, the receiving part can be rotationally fixed to one of the flywheels, such as a secondary flywheel, or to a flange part that is rotationally fixed to it, or it can form such a flange part. The flange part can additionally act on circumferentially acting energy storage devices of the split flywheel.

[0008] Due to the specific motion geometry of the pendulum masses in a trapezoidal arrangement of the contact points, such as rolling points, on the raceways, the oscillation angles on the two raceways of a pendulum mass are not equal. Therefore, in a circular segment-shaped design of the raceways, depending on the direction of the deflection, one raceway is less loaded than the other, resulting in slippage on that raceway. According to the invention, the asymmetrical arrangement of the raceway segments, deviating from a circular segment shape, compensates for the uneven loading of the raceways when the pendulum mass has the same tilt angle in both the tension and compression directions.

[0009] To establish a pendulum motion of the pendulum masses relative to the receiving part, preferably two circumferentially spaced raceways are provided for each pendulum mass, extending radially outward in an arc from the central position. In the receiving part, two circumferentially spaced raceways are provided for each pendulum mass, extending radially inward in an arc from the central position. The arc-shaped raceways are divided into raceway segments that have different radial pitches extending from the central position. For example, the raceway segments contacted by the rolling elements when the receiving part is accelerated in the tensile direction can have a steeper pitch than those contacted in the shear direction.It is assumed that, due to inertia, the pendulum masses are accelerated against the axis of rotation when the receiving part is accelerated around the axis of rotation of the receiving part during traction operation, so that the track segments with the larger gradients are arranged circumferentially against the direction of rotation of the receiving part with respect to the central position of the pendulum masses.

[0010] According to the invention, the raceways are divided circumferentially into two overlapping raceway segments, which are formed from two or more circular segments with different radii, or have arc-shaped extensions. A transition point between the circular segments can be located at a maximum transverse deflection of the pendulum masses relative to the receiving part.

[0011] Several pendulum masses, preferably arranged on both sides of the receiving part of the centrifugal pendulum, can be distributed around the circumference. The axially opposite pendulum masses are connected to each other, with a rolling element rolling in the corresponding raceways of the two pendulum masses and the receiving part. For example, four or six pairs of pendulum masses, each consisting of two axially opposite pendulum masses, can be distributed around the circumference. The pendulum masses or pairs of pendulum masses are arranged parallel to a division axis that determines the division of the pendulum masses with respect to their end regions. A division gap can be provided between two end regions to prevent contact between the circumferentially adjacent end regions of two pendulum masses.

[0012] It has proven advantageous if the outer circumference of the pendulum masses has a smaller radius than the radius of the receiving part. The radius of the pendulum masses is dimensioned such that they remain radially within the receiving part during pendulum movement, meaning that the radial installation space is solely determined by the outer radius of the receiving part. Furthermore, the inner radius of the pendulum masses can be matched to an inner radius specified by the installation space requirements, which is not undercut during pendulum movement.

[0013] The invention is described in relation to the invention described in the Fig. 1, Fig. 2 to Fig. 3. This is explained in more detail in the illustrated embodiment.

[0014] These show: Fig. 1 A schematic view of a centrifugal pendulum in a load-free state, Fig. 2 a schematic view of the centrifugal pendulum of the Fig. 1 under load, Fig. 3 a section of the centrifugal pendulum with a pendulum mass in view and Fig. 4 geometric specifications for the formation of the trajectories of a pendulum mass.

[0015] Fig. Figure 1 shows a schematic view of the centrifugal pendulum 1 with the receiving part 3, which is rotatable about the axis of rotation 2, for the pendulum mass pairs 4 distributed around the circumference. Each pendulum mass pair consists of a pendulum mass 5 and a pendulum mass 6, which is not visible and is located on the other side of the receiving part. The pendulum mass 6 is rigidly connected to the pendulum mass 5, for example, by means of spacer bolts (not shown) that extend through corresponding cutouts in the receiving part 3. The pendulum mass pairs 4 are each pivotably mounted on the receiving part 3 by means of rolling elements 7, allowing limited movement in the circumferential and radial directions. For this purpose, complementary cutouts 8, 9 with raceways 10, 11 are provided in the receiving part 3 and in the pendulum masses 5, 6, on which the rolling elements 7 roll.

[0016] The depicted central position of the rolling elements 7 on the raceways 10, 11 divides the raceways 10, 11 circumferentially into two raceway segments 12, 13 and 14, 15, which are asymmetrically designed relative to the central positions of the rolling elements 7 in the circumferential direction. In the illustrated embodiment, raceway segments 12 of the pendulum masses 5 and raceway segments 14 of the receiving element are displaced relative to the central position in the direction of arrow 16, which indicates the direction of rotation of the receiving part 3 about the axis of rotation 2. These segments have a smaller pitch in the circumferential direction than the raceway segments 13, 15 opposite the central position, which have a higher pitch.Due to this increased pitch of the raceway segments 13, 15, during a pendulum motion of the pendulum masses 5, 6 into the position of the raceway segments 13, 15, the centrifugal force acting on the pendulum masses 5, 6 presses the rolling elements 7 against the raceways 10, 11 with a higher contact force, since the pendulum masses are pulled to a smaller effective diameter. As a result, during a pendulum motion of the pendulum masses 5, 6, both rolling elements 7 are subjected to the same restoring forces in the tension and compression directions on the raceways 10, 11, particularly on the raceway segments 13, 15.

[0017] The pendulum masses 5, 6 are radially located between the outer circumference with the outer radius R. max of the receiving part 3 and the inner circumference with the inner radius R minIn the illustrated embodiment, four pairs of pendulum masses 4 are arranged around the circumference about the fourfold rotation axis 2, each between the division axes 17. To optimally adjust the pendulum angle of the pendulum mass pairs 4, their end regions 18 are each formed parallel to the division axes 17. A small gap 19 may be provided between these.

[0018] Fig. Figure 2 shows the centrifugal pendulum 1 of the Fig. Figure 1 shows the pendulum mass pairs 4 in their fully extended state. Here, the pendulum mass pairs 4 are displaced along arrow 16, opposite to the direction of rotation, about the axis of rotation 2 of the receiving part. The rolling elements 7 are therefore positioned on the raceway segments 13, 15 of the raceways 10, 11. The depicted state of the pendulum mass pairs 4 represents the centrifugal pendulum 1 under tension. Due to the rotational movement, the pendulum masses 5, 6 are displaced along arrow 16, opposite to the direction of rotation. As a result, the center of gravity of the pendulum masses 5, 6 shifts radially inwards due to the design of the raceways 10, 11. The centrifugal force acting on the pendulum masses 5, 6 counteracts this displacement, thus establishing an equilibrium state.For example, if torsional vibrations caused by the internal combustion engine of the drive train occur in the rotational movement of the receiving part 3, these are temporarily stored as potential energy in the centrifugal pendulum masses 5, 6 and later released again, so that the torque curve transmitted via the centrifugal pendulum 1 is smoothed.

[0019] Fig. Figure 3 shows a section of the centrifugal pendulum 1 with the opposing pendulum masses 5 and 6 and the receiving part 3 positioned between them. The tracks 10 and 11 are formed from track segments 12, 13, 14, and 15, which are composed of overlapping circular or arc segments with different radii. Two tracks 10 and 11 of the pendulum mass 5 and the receiving part 3 are mirrored across the line of symmetry 20 passing through the axis of rotation 2. The circular track segments 13 and 15 are defined by the radius R. sin the pendulum mass and the radius R a intended for the receiving part 3. The arcuate track segments 12, 14 are connected by expanding circular segments with increasingly larger arcuate extensions R. a+aΔ on the receiving part 3 and arc-shaped extensions R s+sΔ The pendulum masses 5 and 6 are specified. The arc-shaped extension can extend from the radius R. a or R s to increase the oscillation angle by a predetermined amount, so that a continuous transition to larger radii occurs.

[0020] Fig. Figure 4 shows the geometric details for the formation of the pendulum mass 5 with the raceways 10, the circular raceway segments 13, and the arc-shaped raceway segments 13, which are extended relative to the radius of these. The different radii of the raceway segments simultaneously result in different pendulum lengths I, I+I. Δwith different oscillation angles φ L , φ R When the pendulum mass 5 is displaced, it tilts in both pendulum directions by the angle of inclination β from the horizontal and oscillates about the pendulum axis 21 with half the oscillation angle φ. The pendulum axis 21 is displaced by the trapezoidal height h relative to the axis of rotation 2. The value of h can be designed such that the pendulum axis 21 lies radially between the pendulum mass 5 and the axis of rotation 2, on the axis of rotation 2, or the axis of rotation lies between the pendulum axis 21 and the pendulum mass 5. The transition between the two raceway segments 12 forming the tracks 10 is arc-shaped and consists of the circular raceway segments 13 with radius R. s expanding track segments 12 with the arc-shaped extension R s+sΔ ( Fig. 3) preferably occurs at breakout width B m of the pendulum mass 5, which represents a maximum displacement of the pendulum mass 5 in the horizontal direction. Reference symbol list 1 Centrifugal pendulum 2. Axis of rotation 3 Recording section 4 pendulum mass pairs 5 Pendulum masses 6 Pendulum masses 7 rolling elements 8 Excerpt 9 Excerpt 10 Career 11 Career 12 Career segment 13 Career segment 14 Career segment 15 career segment 16 Arrow 17 Dividing axis 18 End range 19 gaps 20 Line of symmetry 21 Pendulum axle B m Breakout width β Inclination angle h Trapezoid height I Pendulum length I+I Δ pendulum length φ Oscillation angle φ L Oscillation angle φ R Oscillation angle R a radius R a+aΔ arc-shaped extension R max outer radius Rmin inner radius R s radius R s+sΔ arc-shaped extension

Claims

Centrifugal pendulum (1) particularly in a drive train of a motor vehicle with a rotary-driven receiving part (3) and pendulum masses (5, 6) distributed around the circumference of the receiving part, which are pivotably arranged relative to the receiving part (3) by means of rolling elements (7) rolling in raceways (10, 11) provided in these and complementarily in the receiving part (3), wherein the raceways (10, 11) have raceway segments (12, 13, 14, 15) that are asymmetrically formed relative to each other in the circumferential direction with respect to a central position, wherein each of the raceways (10, 11) has an arcuate raceway segment (12, 14) and a circular-segment raceway segment (13, 15) in the circumferential direction, which merge into each other in the central position, wherein the arcuate raceway segment has an arcuate extension (Ra+aΔ, Rs+sΔ) has a circular segment-shaped raceway segment having a radius (Ra, Rs), wherein the arc-shaped extension (Ra+aΔ,Rs+sΔ) starting from the radius (Ra, Rs) of the circular segment-shaped track segment, with increasing swing angle. Centrifugal pendulum (1) according to claim 1, characterized in that a transition point of the circular segments into one another is arranged at a maximum transverse deflection of the pendulum masses (5, 6) relative to the receiving part (3). Centrifugal pendulum (1) according to one of claims 1 to 2, characterized in that the pendulum masses (5, 6) are arranged parallel to a division axis (17) which determines the division of the pendulum masses (5, 6) with respect to their end regions (18). Centrifugal pendulum (1) according to one of claims 1 to 3, characterized in that the outer circumference of the pendulum masses (5, 6) has a smaller radius than the outer radius (Rmax) of the receiving part (3). Centrifugal pendulum (1) according to one of claims 1 to 4, characterized in that for each pendulum mass (5, 6) two circumferentially spaced raceways (10) are provided with circular segment raceway segments (13) facing each other and radially outwardly pointing from the central position in the circumferential direction and raceway segments (12) extending arcuately outwardly. Centrifugal pendulum (1) according to one of claims 1 to 5, characterized in that in the receiving part (3) for each pendulum mass (5, 6) two circumferentially spaced raceways (11) are provided with circularly segmented raceway segments (14) extending from the central position in the circumferential direction away from each other and radially inwardly extending raceway segments (12) facing each other in an arcuate manner.

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