Centrifugal pendulum with optimized rivet connection

Abstract

Centrifugal pendulum (10) associated with a component of a drive train for an internal combustion engine-driven vehicle, wherein the component includes at least one flywheel rotating around a rotational axis (4) and the centrifugal pendulum (10) includes a plurality of pendulum masses (13) which are movably arranged between two axially spaced flange elements (8, 9) via pendulum tracks in conjunction with rollers, wherein the flange elements (8, 9) connected by spacer bolts (12) are associated with a component of the surrounding structure on the rotational axis side, and the spacer bolts (12) are each fixed in position via end-face engagement sections (15) fitted and riveted into receptacles (16) of the flange elements (8, 9), wherein the spacer bolts (12) are each engaged with play in a corresponding receptacle (16), also called a rivet bore, of the flange elements via the engagement sections (15) which are reduced in diameter at both ends and form a step. (8, 9) lock,and wherein the distance between the steps of the engagement sections (15) defines an axial distance (S) between the flange elements (8, 9), wherein the flange elements (8, 9) are connected via the spacer bolts (12) riveted at the ends and each forming a closing head (19), characterized in that an embossing (18) of the flange elements (8, 9) intended for the closing head (19) of the riveting (14) of the spacer bolt (12) has a defined surface structure (47) that interacts with the engagement section (15) of the spacer bolts (12), wherein the embossing (18) is a contact surface embossed for the closing head (19) of the riveting (14), and that a positive and non-positive connection is established between the closing head (19) and the structured contact surface embossed on the end face, wherein the surface structure (47) is formed from grooves.

Description

[0001] The invention relates to a centrifugal pendulum absorber which is assigned to a component of a drive train for an internal combustion engine-driven vehicle, according to the features of the preamble of patent claim 1.

[0002] The combustion process of an internal combustion engine transmits torsional vibrations into the vehicle's drivetrain via the crankshaft. To reduce these torsional vibrations, torsional vibration dampers are used, among other things. These dampers incorporate a centrifugal pendulum to achieve additional isolation and damping objectives.

[0003] A centrifugal pendulum absorber comprises a plurality of pendulum masses suspended by guide elements from at least one rotating flange element, also called a pendulum mass carrier, and moving relative to the flange element along predetermined guideways. The pendulum masses can be positioned at a variable distance from the axis of rotation of the flange element. As a result, the pendulum masses are caused to oscillate or swing, with their centers of gravity constantly changing and offset from the torsional vibrations in the drive train, which dampens the torsional vibrations in the drive train.

[0004] DE 10 2014 210 320 A1 discloses a centrifugal pendulum associated with a torsional vibration damper, which comprises two flange elements arranged axially spaced apart in the direction of the axis of rotation, which can be pivoted along a predetermined pendulum track between two end positions relative to the flange elements.

[0005] DE 10 2015 208 736 A1 discloses a double-flange centrifugal pendulum absorber comprising a first and a second flange element, also called a pendulum mass carrier, which are arranged spaced apart from one another as viewed in the direction of the rotation axis. A flange element is coupled to a component of the torsional vibration damper via a fastening section. Pendulum masses are arranged between the flange elements and can be pivoted relative to the flange elements between two end positions along predetermined paths. The flange elements are connected via spacer bolts, which are riveted at the ends and each form a locking head.

[0006] Double-flange centrifugal pendulum absorbers are also known, in which the riveting of the spacer bolts includes locking heads positioned in the frontal, axially offset, stamped areas of the rivet hole of the flange elements. This measure is required due to the limited installation space, which disadvantageously reduces the contact area for the hole recess between the spacer elements and the flange element.

[0007] DE 10 2018 118 253 A1 discloses a centrifugal pendulum absorber associated with a component of a drive train for an internal combustion engine-powered vehicle. The component has a flywheel rotating around a rotational axis. The centrifugal pendulum absorber includes several pendulum masses movably arranged between two axially spaced flange elements via pendulum tracks in conjunction with rollers. The flange elements, connected by spacer bolts, are associated with a component of the adjacent structure on the rotational axis side. The spacer bolts are engaged in the receptacles of the flange elements via engagement sections that have a reduced diameter at both ends and form a step. This results in a defined distance between the steps of the engagement sections, which defines the axial distance between the flange elements.Each spacer bolt is provided with an engagement section on one side, with which it is pressed into the receptacle of the flange element. A frictional connection is established between the inner circumferential side of the receptacle and the outer circumferential side of the bolt to connect the spacer bolt to the receptacle. The frictional connection is improved by pointed, axially protruding press-in elements, which penetrate the material of the flange element when the spacer bolt is pressed into it and displace it proportionally toward the end of the spacer bolt inserted into the receptacle, improving the frictional connection.

[0008] DE 11 2020 003 827 T5 discloses a centrifugal pendulum with two flange elements, between which a pendulum mass is suspended. The flange elements are fastened to one another by means of rivets 4. An axial projection 13 is formed on each support plate, which could also be designed as an embossing. The holes for the rivets are formed in the embossings so that the closing heads of the rivets rest against the axially recessed surface of the embossing. The embossings protrude axially from the support plates so far that, when riveted, they lie axially against one another and define an axial distance between the support plates, which ensures the movement space for the pendulum masses. The embossings are designed so that they are riveted axially against one another and act as spacers between the two support plates.

[0009] The closest prior art is disclosed in DE 10 2016 209 972 A1. Reinforcing embossments are incorporated into the respective flange element near the riveted joint.

[0010] The invention is based on the object of improving the fatigue strength of the centrifugal pendulum by means of structurally simple and cost-effective measures.

[0011] This object is achieved by a centrifugal pendulum constructed with the features of patent claim 1. Advantageous embodiments and / or further developments are the subject of the subclaims.

[0012] Accordingly, it is provided that the frontally stamped contact surface of the flange elements, intended for a closing head of the riveting of the spacer bolt, has a defined surface structure that interacts with the spacer bolt. An embossing of the flange elements is provided, intended for the closing head of the riveting of the spacer bolt, which embossing has a defined surface structure that interacts with the engagement section of the spacer bolt, wherein the embossing is a contact surface embossed for the closing head of the riveting. A positive and non-positive connection is established between the closing head and the structured and frontally stamped contact surface, wherein the surface structure is formed from grooves.

[0013] It is therefore intended to provide the embossing on the flange element intended for the closing head of the riveting of the spacer bolt, also known as the embossed contact surface, with a surface structure.

[0014] The structured contact surfaces ensure a positive and force-locking connection between the locking head and the structured, front-faced contact surface of the flange elements during riveting.

[0015] Thanks to the structured contact surfaces, the standoff bolt is connected to the corresponding flange elements after riveting without play, providing a force-locking and positive connection, thus reliably protecting it against twisting and axial loosening. Consequently, the surface structure, which can be implemented in various geometric shapes, enables an improved, fatigue-resistant riveted connection, which offers effective protection against rivet failure, also known as bursting, at high speeds. The proposed concept prevents the rivet's closing heads from coming loose by pulling them through the rivet hole, which would otherwise cause the centrifugal pendulum to fail.

[0016] Furthermore, according to the proposal, a centrifugal pendulum absorber can be provided in which a precise axial positioning of the parallel flange elements, between which pendulum masses guided in guideways are arranged, is permanently established within the specified, unchanged installation space. The precise guidance of the pendulum masses relative to the flange elements has a positive influence on the wear of the pendulum masses and the noise generation of the centrifugal pendulum absorber.

[0017] For automotive applications, OEMs (Original Equipment Manufacturers) expect durable centrifugal pendulum absorbers with a long service life and good insulation properties. The newly designed centrifugal pendulum absorber meets these requirements, as well as the vehicle manufacturers' demand for reduced manufacturing costs.

[0018] According to a preferred embodiment, the surface structure for receiving the flange elements is designed as a toothed arrangement. Both the number and size of the teeth can be varied. It is also possible to design the surface structure, for example, with a rectangular or pointed tooth shape, or to implement it as an involute toothing. The toothing advantageously ensures a desired position-oriented installation position of both flange elements after riveting the spacer bolts.

[0019] Another embodiment provides for the surfaces of the flange element mounts to be designed as a thread-like or spiral-shaped embossing. The geometric design regarding the depth and width of the grooves, as well as the pitch, is preferably variable. Furthermore, the shape of the grooves can be pointed, rounded, or designed to resemble a ball screw or a trapezoidal thread.

[0020] Furthermore, a surface structure is proposed on the axial embossing of the flange element, which is intended for the closing head of the rivet. The structured surface, which may be concentric or spiral-shaped and forms grooves, can be variable in both the number and the depth and width of the grooves. Likewise, the structure can include pointed, rounded, or angular grooves, or form a knurling.

[0021] Furthermore, it is proposed to design the surface-structured receptacle in a manner other than circular. For example, the rivet hole can be designed as a wave pattern or in a flower-like shape when viewed from above.

[0022] The design of the proposed centrifugal pendulum absorber further includes a surface structure composed of various geometric shapes. The structure can, for example, be combined with gear teeth, threaded elements, and / or concentric or spiral grooves, which are incorporated into a rivet hole with a limited degree of non-circularity.

[0023] It is also proposed that the flange elements be designed as a sheet metal component, manufactured without cutting from a metallic material. A suitable method for this is, for example, a stamping and bending process, in which the surface structure is cost-effectively introduced into the flange element receptacle (also known as a rivet hole) in a single manufacturing process. The flange elements are preferably made of a material whose hardness exceeds that of the spacer bolt, for example, designed as an extruded part, which makes it easier to rivet.

[0024] The proposed double-flange centrifugal pendulum absorber is preferably assigned to a torsional vibration damper configured as a single-mass flywheel or a dual-mass flywheel in the drive train. Furthermore, the centrifugal pendulum absorber can be attached to a torque converter component or a clutch. The centrifugal pendulum absorber is positioned externally or internally of the torsional vibration damper and is attached, for example, via a flange element to a rotating part, in particular to the output hub of the secondary part of the dual-mass flywheel.

[0025] According to a further preferred embodiment, the proposed centrifugal pendulum is designed as a pre-assembled double-flange centrifugal pendulum in the form of a pendulum module. The centrifugal pendulum can thus be prefabricated or pre-assembled for different applications, which has a beneficial effect on inventory management and positively influences the assembly steps of the drive train during motor vehicle production.

[0026] The invention is described and explained in more detail below with reference to the exemplary embodiments illustrated in the figures. However, the invention is not limited to these exemplary embodiments. It shows: Fig. 1: a torsional vibration damper in a half-section, to which a centrifugal pendulum is assigned; Fig. 2: a first embodiment of the centrifugal pendulum shown enlarged according to the Fig. 1; Fig. 3: a 3D partial view of a third embodiment of the centrifugal pendulum according to Fig. 1, with a surface structure of the rivet hole embossed on the front side of the flange elements; Fig. 4: a front view of the flange element from Fig. 7 with structured embossed front side.

[0027] The Fig. 1 shows a half-section of a torsional vibration damper 1 constructed as a dual-mass flywheel, which is intended, for example, for a hybrid application (DHT) in a drive train (not shown) of a motor vehicle. The torsional vibration damper 1, which is attached to the crankshaft of an internal combustion engine (not shown) on the input or drive side, comprises a primary part 2, also called a primary mass, on the engine side and a multi-part secondary part 3 on the output side, which are jointly rotatable about an axis of rotation 4 and rotatable to a limited extent relative to one another. A spring damper device 5, which includes mechanical energy storage devices designed as arc springs 6, acts between the primary part 2 and the secondary part 3. On the output or output side, the torsional vibration damper 1 is connected, for example, to a transmission input shaft (not shown) via an output hub 7 of the secondary part 4.On the output side, a centrifugal pendulum 10 is mounted axially in front of the torsional vibration damper 1, which is fastened to the drive hub 7 via a flange element 8, also called a pendulum mass carrier, via riveted connections 11.

[0028] The centrifugal pendulum 10 is in the Fig. 2, the flange element 8 is connected to a second flange element 9 via a plurality of spacer bolts 12 arranged circumferentially in two radially offset planes, such that the two are positioned axially spaced from one another. Pendulum masses 13 inserted between the flange elements 8, 9 are pivotally guided via guide rollers in conjunction with slide tracks (not shown). The rotationally symmetrical spacer bolts 12 are fastened to the flange elements 8, 9 by means of end-side rivets 14. The spacer bolts 12 engage, with play, via engagement sections 15 at both ends that have a reduced diameter and form a step, in a corresponding receptacle 16 of the flange elements 8, 9, also called a rivet bore. The distance between the steps of the engagement sections 15 defines an axial distance S between the flange elements 8, 9.A surface structure 17 is consistently introduced into all receptacles 16 of the flange elements 8, 9. During assembly, the spacer bolts 12 are positioned between the first flange element 8 and the second flange element 9 such that their engagement sections 15 engage flush with the receptacles 16 of the flange elements 8, 9. During the subsequent riveting, material of the engagement sections 15 is deformed radially into the surface structure 17 of the receptacle 16. Furthermore, during the riveting, material is filled into an axial embossed recess 18 of the flange elements 8, 9 at the end of the engagement sections 15, forming a closing head 19. The riveting 14 results in a positive and non-positive connection between the spacer bolts 12 and the flange elements 8, 9, thereby ensuring durable and precise positioning of these components.

[0029] The Fig. Figures 3 and 4 illustrate an embodiment of the proposed double-flange centrifugal pendulum absorbers, with identical reference numerals being used for corresponding components. The following descriptions are largely limited to different designs of the surface structure in the flange elements 8, 9.

[0030] In Fig. 3 shows a 3D partial view of the flange elements 8, 9 of the centrifugal pendulum 10, in which the axial embossing 18 intended for the closing head 19 of the rivet 14 on the flange elements 8, 9 has a frontal surface structure 47. The surface structure 47 can, for example, enclose concentric circles or be spiral-shaped. Fig. 4 illustrates the position and design of the surface structure 47 in a front view of the flange element 9. List of reference symbols 1 torsional vibration damper 2 Primary part 3 Secondary part 4 axis of rotation 5 Spring damper device 6 bow spring 7 Output hub 8 Flange element 9 Flange element 10 centrifugal pendulums 11 Riveted connection 12 spacer bolts 13 Pendulum mass 14 Riveting 15 intervention section 16 recording 17 Surface structure 18 Embossing 19 Locking head 47 Surface structure S Distance between flange elements

Claims

[1] Centrifugal pendulum (10) which is assigned to a component of a drive train for an internal combustion engine-driven vehicle, wherein the component includes at least one flywheel rotating about an axis of rotation (4) and the centrifugal pendulum (10) includes a plurality of pendulum masses (13) which are movably arranged between two axially spaced flange elements (8, 9) via pendulum tracks in conjunction with rollers, wherein the flange elements (8, 9) connected by spacer bolts (12) are assigned to a component of the surrounding structure on the axis of rotation side and the spacer bolts (12) are each fixed in position by means of end-face engagement sections (15) fitted and riveted into receptacles (16) of the flange elements (8, 9), wherein the spacer bolts (12) are each inserted with play into a corresponding receptacle (16), also called a rivet bore, via the engagement sections (15) which are reduced in diameter at both ends and form a step. the flange elements (8, 9) lock,and wherein the distance between the steps of the engagement sections (15) defines an axial distance (S) of the flange elements (8, 9), wherein the flange elements (8, 9) are connected via the spacer bolts (12) riveted at the ends and each forming a closing head (19), , characterized by that an embossing (18) of the flange elements (8, 9) intended for the closing head (19) of the rivet (14) of the spacer bolt (12) has a defined surface structure (47) which interacts with the engagement section (15) of the spacer bolt (12), wherein the embossing (18) is a contact surface embossed for the closing head (19) of the rivet (14), and that a positive and non-positive connection is set between the closing head (19) and the structured and frontally embossed contact surface, wherein the surface structure (47) is formed from grooves. [2] Centrifugal pendulum (10) according to claim 1, characterized bythat the axial embossing (18) of the flange elements (8, 9) intended for the closing head (19) of the riveting (14) has a surface structure (47). [3] Centrifugal pendulum (10) according to one of claims 1 to 2, characterized by that the surface-structured receptacle (15) in the flange elements (8, 9) is designed in a manner deviating from a circular shape. [4] Centrifugal pendulum (10) according to one of claims 1 to 3, characterized by that the centrifugal pendulum (10) is positioned on a torsional vibration damper (1) constructed as a single-mass flywheel or a dual-mass flywheel or a shift-disconnect clutch. [5] Centrifugal pendulum (10) according to claim 4, characterized by that the centrifugal pendulum (10) is assigned to the torsional vibration damper (1) externally or internally. [6] Centrifugal pendulum (10) according to one of claims 1 to 5, characterized bythat the centrifugal pendulum (10) enclosing a double flange is designed as a pre-assembled pendulum module.

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