Groove pattern for friction plates

Abstract

Groove pattern (10) for friction plates, wherein the groove pattern (10) is formed by means of friction lining pads (11-13; 14-16) and the friction lining pads (11-13; 14-16) have a diamond-shaped configuration, wherein the friction lining pads (11-13; 14-16) represent a friction surface (80) with an inner diameter (83) and an outer diameter (84), characterized in that each friction lining pad (11-13; 14-16) has a stamped groove (9) which intersects with two pad grooves (8; 78) delimited by the respective friction lining pad at a first intersection point (81) and at a second intersection point (82), both of which are arranged within the friction surface (80), wherein the pad grooves (8; 78) extend obliquely to a radial direction and wherein the stamped grooves (9) extend transversely to the Pad grooves (8;78) extend and wherein a branching angle (7) between the pad grooves (8,78) and the embossed grooves (9) is between 90 and 100 degrees and all friction lining pads (11-16) have the same shape and size.

Description

[0001] The invention relates to a groove pattern for friction plates having the features according to the preamble of claim 1.

[0002] Grooves or groove patterns—also referred to in this document as pad geometry—serve to cool the plates through oil flow, even when the shift elements are closed. They cut through the oil film and thereby stabilize the friction coefficient. This creates the desired friction behavior during shifting. Idling behavior is improved and drag torque is reduced. The area of ​​application of the invention:

[0003] Wet multi-plate clutches and brakes are widely used in conventional powershift transmissions, in innovative hybrid modules in highly stressed drivetrains, or in switchable electric axles, and represent high-performance, highly stressed components. The demands for lower CO2 emissions and improved drivetrain efficiency in automotive applications are of great importance. In addition to reducing load-independent losses in shifting elements, thermal stress and adequate cooling must be considered. The groove pattern of the friction plate plays a central role in the tension between friction characteristics, heat management, and efficiency. (see Fig. 1)

[0004] DE 10 2013 010 651 A1 discloses wet-running clutch plates with friction lining pads which are arranged spaced apart from one another in the circumferential direction and form substantially radially extending cooling channels between them, wherein the cooling channels are inclined in a partial region in the circumferential direction.

[0005] EP 3 147 524 A1 discloses wet-running clutch plates with friction lining pads which are arranged spaced apart from one another in the circumferential direction and form cooling channels between them, wherein the friction lining pads have press grooves.

[0006] DE 10 2017 123 580 A1 discloses wet-running friction plates, with friction lining pieces that constitute a friction lining that is divided into circular ring sectors, of which at least two circular ring sectors have different groove patterns.

[0007] WO 2016 180 540 A1 discloses annular wet-running friction linings with a first groove set consisting of rectilinear grooves that connect the inner and outer circumferences but do not extend radially and do not intersect. US 6 293 382 B1 has an additional second groove set, with each groove of this second groove set connecting two adjacent grooves of the first groove set.

[0008] The invention is based on the object of minimising drag losses in friction plates by means of a suitable groove pattern (cf. Fig. 2) and to optimize the cooling performance (cf. Fig. 4).

[0009] The problem is solved by a groove pattern having the features according to claim 1.

[0010] The groove pattern for friction plates according to the invention therefore provides that the groove pattern is formed by means of friction lining pads and the friction lining pads have a diamond-shaped configuration, with each friction lining pad having an embossed groove.

[0011] In this way, the drag torque is further reduced.

[0012] The diamond-shaped friction lining pads are attached to a carrier plate, for example a carrier sheet. The carrier plate essentially has the shape of a circular disk. Toothing is provided radially inside or radially outside on the carrier plate, which serves to create a rotationally fixed connection with a plate carrier. Advantageously, an edge on the carrier plate, both radially inside and radially outside, remains free of friction lining pads. This allows for the compensation of tolerances in the size and / or shape of the friction lining pads when attaching them to the carrier plate. Furthermore, the friction lining pads are advantageously evenly spaced from one another in the circumferential direction. The distances between the friction lining pads in the circumferential direction create grooves between the friction lining pads. These grooves are referred to below as pad grooves. Due to the diamond-shaped shape of the friction lining pads, the pad grooves extend obliquely to a radial direction.Depending on the direction of rotation in which the friction plates are rotated, with the steel plates rotating faster than the friction plates, either a locking effect or a pumping effect results. Both effects are described in detail in the following figure description. The embossed grooves in the friction lining pads allow the oil flow from radially inside to radially outside between the steel plates and the friction plates to be optimized, particularly with regard to cooling performance. The locking effect resulting from the locking effect can be varied very effectively through the interaction between the pad grooves and the embossed grooves in combination with the diamond-shaped friction lining pads.

[0013] The friction lining pads form a friction surface with an inner diameter and an outer diameter. Pad grooves are formed by the spacing between the friction lining pads. The friction surface has the shape of a circular ring with an inner diameter and an outer diameter. The friction surface is defined by the friction lining pads and can therefore exhibit dimensional deviations, subject to tolerances, on both the inner and outer diameters. According to an essential aspect of the invention, two intersection points of a stamped groove of each friction lining pad with pad grooves defined by the friction lining pad are always located within the friction surface, i.e., radially between the inner diameter and the outer diameter of the friction surface.

[0014] A preferred embodiment of the groove pattern is characterized in that pad interior angles in pad corners have a degree measurement between 40 and 145 degrees. Each pad corner contains a pad interior angle. Due to the diamond-shaped configuration of the friction lining pads, each friction lining pad comprises two opposing interior angles that are greater than 90 degrees and two further opposing interior angles that are less than 90 degrees. The specified size range refers to this. Two of the interior angles are preferably between 40 and 50 degrees. The other two interior angles are preferably between 125 and 145 degrees.

[0015] Another preferred embodiment of the groove pattern is characterized by the fact that all pad corners are rounded along their circumferential contour. This has proven advantageous with regard to the airflow around the friction lining pads.

[0016] Another preferred embodiment of the groove pattern is characterized by rounding radii in the pad corners being greater than or equal to one millimeter. This has proven sufficient with regard to the airflow around the friction lining pads.

[0017] Another preferred embodiment of the groove pattern is characterized in that the friction lining pads have widths and heights with a width-to-height ratio that is less than two for each friction lining pad. The width-to-height ratio of the friction lining pads is preferably between 1.5 and 1.7. This width-to-height ratio advantageously applies to both directions of rotation in which the friction plates can be rotated.

[0018] Another preferred embodiment of the groove pattern is characterized in that between two adjacent friction lining pads, a pad groove is arranged with a groove width that is smaller than the groove width of the embossed grooves in the friction lining pads. The width of the pad grooves is defined by the distance between the diamond-shaped friction lining pads relative to one another. The smaller groove width of the pad grooves is particularly advantageous because the pad grooves preferably have a greater groove depth than the embossed grooves.

[0019] The groove pattern according to the invention is characterized in that the branching angle between the pad grooves and the embossed grooves is between 90 and 100 degrees. A particularly preferred branching angle between the pad grooves and the embossed grooves is 90.4 degrees. This specified angle range results in the embossed grooves running essentially transversely to the pad grooves. This has proven very effective in influencing the oil flow in the claimed groove pattern.

[0020] Another preferred embodiment of the groove pattern is characterized in that the embossed grooves have a maximum depth of 50 percent of the thickness of the friction lining pads. This has proven advantageous with regard to the production and fastening of the friction lining pads.

[0021] The groove pattern according to the invention is characterized by the fact that all friction lining pads have the same shape and size. This has also proven advantageous with regard to the manufacture and assembly of the friction lining pads. The term "same shape and size" includes manufacturing tolerances.

[0022] The invention further relates to a friction lining pad for a previously described groove pattern. The friction lining pads are sold separately.

[0023] Further advantages and advantageous embodiments of the invention are the subject of the following figures and their description.

[0024] They show in detail: Fig. 1 Relationships: Air intake and drag torque Fig. 2 Task and improvements Fig. 3 Conveying effect and blocking effect Fig. 4 Cooling performance Fig. 5 inventive groove design Fig. 6 Dimensioning of the groove design according to the invention Fig. 7 Dimensioning of the groove design according to the invention Fig. 8 Dimensioning of the groove design according to the invention Fig. 9 A pad of the inventive groove design Fig. 10 A similar representation as in Fig. 3A, which illustrates that intersection points between the embossed grooves and the pad grooves are always located within the friction surface. • Angle (1) in Fig. 6 are between 40 and 145 degrees (details see Fig. 9) • Pad outer edges rounded along the circumference, preferably >= 1 mm (cf. Fig. 7 (2)) • Two-row design taking into account the central embossing results in almost identical pad surfaces in triangular shape for the inner and outer rows, basic geometry without taking into account the embossing: pad designed as a rhombus • Width (3) to height (4) ratio of the pad less than 2 (preferably from 1.5 to 1.7) (cf. Fig. 7) • Width of the embossing (5) > width of the groove (6) (cf. Fig. 8) • Ratio of groove angle to embossing angle (7) between 90 and 100 degrees, preferably 90.4 degrees (cf. Fig. 8) - Optimization of manufacturing quality through optimized pad geometry. - Improvement of the fibrousness and edge quality and thus reduction of the drag torques in the open state of the friction system, e.g. by means of a groove embossing. - Robust wear behavior of the pad edges and corners over their lifetime. Preservation of the edge geometry (low rounding (1)) leads to robust, consistent hydrodynamic behavior (lubricating wedge) and thus to stable friction characteristics. The control system's application effort is reduced. - rapid removal of the oil film by a further preferred embodiment of the invention, in which the branching angle (7) is between 90° and 100°, preferably 90.4°. - Due to the angular position of the grooves, depending on the relative direction of rotation of the steel plate relative to the friction plate, a conveying effect ( Fig. 3 A) or blocking effect ( Fig. 3 B) of the oil (direction dependence). Depending on the relative direction of rotation between the friction plate and the steel plate, the cooling performance (cf. Fig. 4) can be varied depending on the application. Due to the pad embossing ( Fig. 5 “Embossed groove”) this influence can be designed as desired (cf. Fig. 8: Embossing depth, width (5), angle (7)) and optimized for the respective application.

[0025] In Fig. 1 shows three Cartesian coordinate diagrams superimposed on each other. On an x-axis 20, a rotational speed during operation of the wet multi-plate clutch 1 with the friction part 15 is plotted in a suitable unit. On a y-axis 21, a volume flow is plotted in a suitable unit. On a y-axis 22, a gap filling ratio is plotted in a suitable unit. On a y-axis 23, a drag torque is plotted in a suitable unit.

[0026] In Fig. Figure 1 illustrates how an air intake 26 occurs due to a conveyed volume flow 24 when this exceeds the supplied volume flow 25. From this limit, the gap filling level 26 decreases, and the lubrication gap between the lamellae contains air. From this limit, a supplied volume flow 25 contains air. Fig. 2 below you can see that the air intake 26 occurs at a maximum drag torque 27.

[0027] In Fig. 2 shows how the claimed friction part 15 achieves a shift of the air intake 28 to a low speed in a drag torque curve 30. By the Fig. The conveying effect of the cooling and / or lubricating medium can be improved using the groove pattern shown in Figure 3.

[0028] Fig. 3 includes the Fig. 3A and Fig. 3B. In the Fig. 3A and Fig. 3B shows a groove pattern 10 according to the invention, also referred to as a groove design. The groove pattern 10 comprises friction lining pads 11 to 13; 14 to 16 arranged on a carrier plate 18. The carrier plate 18 with the friction lining pads 11 to 13; 14 to 16 is referred to as friction plate 19.

[0029] The friction lining pads 11 to 13; 14 to 16 all have a diamond shape with rounded corners. In the circumferential direction, the friction lining pads 11 to 13; 14 to 16 are spaced from one another such that a pad groove 8 is formed between each two adjacent friction lining pads 12, 13; 14, 15. The pad groove 8 is limited in depth by the carrier plate 18. The pad grooves 8 extend obliquely to a radial direction.

[0030] In addition, each of the friction lining pads 11 to 13; 14 to 16 includes a stamped groove 9. The stamped grooves 9 extend transversely to the pad grooves 8. Furthermore, the pad grooves 8 have a greater groove depth than the stamped grooves 9. The groove depth of the stamped groove 9 is a maximum of fifty percent of the thickness of the friction lining pads 11 to 13; 14 to 16. The groove depth of the pad grooves 8 corresponds to the thickness of the friction lining pads 11 to 13; 14 to 16.

[0031] In a multi-plate clutch, several friction plates 19 with steel plates are arranged in a plate pack. Fig. 3A and Fig. 3B, the directions of rotation during operation of the friction plates 19 are indicated by arrows 60; 70. The condition applies that an associated steel plate rotates faster than the respective associated friction plate 19. Arrows 61 to 64; 71 to 74 indicate forces acting during operation, which result from an oil flow between the friction plate 19 and the steel plate from radially inside to radially outside.

[0032] Arrows 61; 71 illustrate a centrifugal force. Arrows 62; 72 illustrate a flow through the pad groove 8, which, due to the diamond-shaped configuration of the friction lining pads 11 to 13; 14 to 16, causes a force indicated by arrow 62; 72, depending on the pad interior angles and the direction of rotation 60; 70.

[0033] An arrow 63; 73 is in the Fig. 3A and Fig. 3B indicates a force caused by the relative movement between the steel plate and the friction plate 19. An arrow 64; 74 indicates the force resulting from the forces 61 to 63; 71 to 73.

[0034] Fig. 3A illustrates a locking effect resulting from the friction lining pads 11 to 13 when the friction plate 19 rotates less quickly than the associated steel plate in the direction of rotation 60. Fig. 3B illustrates a pumping effect resulting from the friction lining pads 14 to 16 when the friction plate 19 rotates in the direction of rotation 70 less quickly than the associated steel plate.

[0035] In Fig. Figure 4 shows a bar chart with a y-axis 40 and bars 41 to 44. The y-axis 40 represents the cooling capacity in kilowatts. Bars 41 to 44 represent cooling capacities for different volume flows, which are determined by the groove patterns 10 of the Fig. 3A and Fig. 3B can be realized.

[0036] Bars 41 and 42 illustrate a relatively low oil flow rate. Bars 43 and 44 illustrate a rather high oil flow rate.

[0037] The bars 41, 43 are in Fig. 3A is assigned to the pumping effect. Bars 42, 44 are in Fig. 3B assigned to the blocking effect.

[0038] The pumping effect results in greater cooling performance at both low and high flow rates. However, the cooling performance varies, as can be seen in Fig. 4, the blocking effect is not as strong at high flow rates as at low flow rates. Depending on the application, the blocking effect can be mitigated or varied by changing the design of the embossed groove or the cross-section, i.e., the width and depth of the embossed groove. The larger the cross-section, the more oil can flow through the embossed groove.

[0039] In Fig. 5 shows that the friction lining pads 11 to 13 are rounded at their pad corners 31 to 34. In Fig. 7, rounding radii are designated by 2, which are essentially the same in all pad corners 31 to 34. The rounding radii 2 are advantageously greater than or equal to one millimeter.

[0040] In Fig. 6, the pad inner angles 1 on the friction lining 12 are indicated by double arrows. The pad inner angles 1 range between 40 and 145 degrees. The central arrangement of the embossed groove 9 in the friction lining pad 12 results in a two-row groove design with identical pad surfaces radially inside and radially outside. Due to the diamond-shaped configuration of the friction lining pad 12, the identical pad surfaces each have a triangular shape.

[0041] In Fig. 7, a width of the friction lining pad 12 is indicated by a double arrow 3. A height of the friction lining pad 12 is indicated by a double arrow 4. The ratio of width 3 to height 4 is preferably less than two for all friction lining pads. The ratio between width 3 and height 4 is advantageously between 1.5 and 1.7 for all friction lining pads 11 to 13; 14 to 16 of the groove pattern 10.

[0042] In the Fig. 6 and Fig. 7, dimensioning guide lines are drawn on the friction lining pad 12. There are some gaps between the guide lines and the friction lining pad 12. These gaps are intended to illustrate tolerances that may be present on the friction lining pad 12 due to manufacturing.

[0043] In Fig. 8, a groove width of the embossed groove 9 is indicated by a double arrow 5. A groove width of the pad groove 8 between the friction lining pads 12 and 13 is indicated by a double arrow 6. A branching angle between the pad groove 8 and the embossed groove 9 is indicated by a double arrow 7.

[0044] The branching angle 7 between the pad groove 8 and the embossed groove 9 in the complete groove pattern 10 is advantageously between ninety and one hundred degrees, preferably 90.4 degrees.

[0045] In Fig. 9, the pad inner angles 51 to 54 of the friction lining pad 12 are indicated by double arrows. The degrees of the pad inner angles 51 to 54 are, in the order mentioned, 132; 44.5; 142; 41.6.

[0046] In Fig. 10, the friction plate 19 is made of Fig. 3A is shown with auxiliary lines that illustrate that the friction lining pads 11 to 13 form a friction surface 80. The friction surface 80 is bounded radially inward by an inner diameter 83 and radially outward by an outer diameter 84. Manufacturing tolerances may occur here.

[0047] It is essential, however, that intersection points 81, 82 between the embossed groove 9 of the friction lining pad 12 and two pad grooves 8 and 78, which are delimited by the friction lining pad 12, are arranged within the friction surface 80. List of reference symbols 1 pad inner angle 2 rounding radii 3 Width 4 Height 5 Groove width 6 groove width 7 branching angles 8 Padnut 9 embossed groove 10 groove patterns 11 Friction pad 12 friction pad 13 Friction pad 14 Friction pad 15 Friction pad 16 Friction pad 18 carrier slats 19 Friction plate 20 x-axis 21 y-axis 22 y-axis 23 y-axis 24 delivered volume flow 25 supplied volume flow 26 Air intake 27 Drag torque 28 Air intake 30 Drag torque curve 31 Pad Corner 32 Pad corner 33 Pad corner 34 Pad corner 40 y-axis 41 bars 42 bars 43 bars 44 bars 51 Pad inner angle 52 pad inner angle 53 Pad inner angle 54 Pad inner angle 60 direction of rotation 61 Arrow 62 Arrow 63 Arrow 64 Arrow 70 Direction of rotation 71 Arrow 72 Arrow 73 Arrow 74 Arrow 78 Padnut 80 friction surface 81 first intersection point 82 second intersection point 83 inner diameter 84 outer diameter

Claims

[1] Groove pattern (10) for friction lamellae, wherein the groove pattern (10) is formed by means of friction lining pads (11-13; 14-16) and the friction lining pads (11-13; 14-16) have a rhomboid shape, wherein the friction lining pads (11-13; 14-16) represent a friction surface (80) with an inner diameter (83) and an outer diameter (84), characterized by , that each friction pad (11-13;14-16) has an embossed groove (9) which intersects with two pad grooves (8;78) bounded by the respective friction pad at a first intersection point (81) and at a second intersection point (82), both of which are arranged within the friction surface (80), wherein the pad grooves (8;78) extend obliquely to a radial direction and wherein the embossed grooves (9) extend transversely to the pad grooves (8;78) and wherein a branching angle (7) between the pad grooves (8,78) and the embossed grooves (9) is between 90 and 100 degrees and all friction pads (11-16) have the same shape and size. [2] Groove pattern according to claim 1, characterized by , that pad interior angles (1) in pad corners have a degree measurement between 40 and 145 degrees. [3] Groove pattern according to one of the preceding claims, characterized by that all pad corners are rounded along their perimeter contour. [4] Groove pattern according to one of the preceding claims, characterized by , that the radii of curvature (2) in the pad corners are greater than or equal to one millimeter. [5] Groove pattern according to one of the preceding claims, characterized by , that the friction pad pads (11-16) have widths (3) and heights (4) which have a width (3) to height (4) ratio that is less than 2 for each friction pad pad (11-16). [6] Groove pattern according to one of the preceding claims, characterized by , that between two adjacent friction lining pads (11-16) a pad groove (8; 78) with a groove width (5) is arranged which is smaller than a groove width (6) of the embossed groove (9) in the friction lining pads (11-16). [7] Groove pattern according to one of the preceding claims, characterized by , that the embossing depth of the embossed grooves (9) corresponds to a maximum of 50 percent of the thickness of the friction lining pads (11-16). [8] Friction pad (11-16) for a groove pattern (10) according to one of the preceding claims.

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