JP7676552B2 - Friction disc having groove pattern formed by friction lining pad - Google Patents

Description

The present invention relates to a groove pattern for a friction disc having the features described in the preamble of claim 1.

Grooves or groove patterns, also referred to herein as pad shapes, are used to cool the disks by oil flow even when the switching elements are closed. They disrupt the oil film and thus stabilize the friction values. This results in the desired friction behavior during switching. The idle behavior is improved and the drag torque is reduced.

Application areas of the present invention:
Wet multi-plate clutches and brakes are intended for a wide range of applications in conventional powershift transmissions, new hybrid modules in highly loaded drivetrains or switchable e-axles, where they are high-performance components that meet high demands. In automotive applications, the need to reduce CO2 emissions and increase the efficiency of the drivetrain are of paramount importance. Attention must be paid to low load-dependent losses in the switching elements as well as to thermal loads and adequate cooling. Where friction properties, heat balance and efficiency interact, the groove pattern of the friction discs plays a central role. (See Figure 1)

WO 2016 180 540 A1 discloses an annular wet friction lining having a first groove set of non-intersecting, linearly extending grooves connecting the inner and outer periphery.

US Patent No. 2009 0 211 867 (A1) discloses an annular wet friction lining with a first groove set and a second groove set of embossed grooves that join the inner and outer periphery to form a trapezoidal friction lining pad that forms an annular friction lining.

U.S. Patent No. 3,972,400 (A1) discloses an annular wet friction lining having a first groove set of radially and linearly extending grooves and a second groove set of non-radially and linearly extending grooves connecting the inner and outer periphery.

The objective of the present invention is to minimize drag losses (see Figure 2) and improve cooling (see Figure 7) in the case of friction discs by using an appropriate groove pattern.

This problem is solved by a groove pattern having the characteristics described in claim 1.

The groove pattern according to the invention for a friction disc therefore provides for the groove pattern to be formed using friction lining pads, the friction lining pads having a trapezoidal structure and each friction lining pad having embossed grooves.
The paths between the embossed grooves form a honeycomb-like structure.
The inter-groove paths of the embossed grooves form a honeycomb-like structure that is common on all pads.

In this way, the drag torque is further reduced.

The friction lining pads preferably have an isosceles trapezoidal structure. The trapezoidal friction lining pads are attached to a carrier disk, for example a carrier plate. The carrier disk has a substantially annular disk structure. The carrier disk is provided radially inward with toothed edges, which are used to provide a non-rotatable connection with the disk carrier. Radially inward and radially outward, the edges of the carrier disk preferably remain independent of the friction lining pads. Thus, when attaching the carrier disk, tolerances in the size and/or structure of the friction lining pads can be compensated for. Furthermore, the friction lining pads are preferably uniformly spaced apart from one another in the circumferential direction. However, the trapezoidal friction lining pads are preferably aligned with their respective longer base sides alternately radially inward and radially outward. Due to the spacing of the friction lining pads from one another in the circumferential direction, grooves between the friction lining pads result. These grooves are referred to below as dividing grooves. Due to the trapezoidal structure of the friction lining pads, the dividing grooves run obliquely to the radial direction. Because the friction lining pads are aligned alternately, the split grooves are likewise arranged alternately at different inclinations relative to the radial direction.

A preferred embodiment of the groove pattern is characterized in that the groove pattern comprises at least eight friction lining pads arranged in an annular manner, with one dividing groove arranged between each pair of circumferentially adjacent friction lining pads. The dividing groove is limited in the circumferential direction by the adjacent friction lining pads. Radially inwardly and radially outwardly, the dividing groove is open. The groove depth of the dividing groove is limited by the carrier disk.

A further preferred embodiment of the groove pattern is characterized in that the embossed grooves in the friction lining pads have a groove width that is greater than the dividing grooves between the friction lining pads. The dividing groove widths are relatively mutually defined by the spacing of the trapezoidal friction lining pads. The smaller groove width of the dividing grooves is particularly advantageous, since the dividing grooves preferably have a groove depth that is greater than the embossed grooves. The embossed depth of the embossed grooves is at most 50 percent of the thickness of the friction lining pads. This has been found to be advantageous with a view to the manufacture and installation of the friction lining pads.

A further preferred embodiment of the groove pattern is characterized in that the ratio of the area of the dividing groove to the area of the embossed groove is at least 1:2, preferably 1:2 to 1:4. The area of the embossed groove is at least twice the area of the dividing groove. Thus, the drag torque can be effectively reduced.

A further preferred embodiment of the groove pattern is characterized in that the pad interior angles at the pad ends have angles between 60 and 120 degrees. Each pad end includes a pad interior angle. Due to the trapezoidal structure of the friction lining pads, each friction lining pad includes two circumferentially adjacent interior angles that are greater than 90 degrees and two circumferentially adjacent interior angles that are less than 90 degrees.

A further preferred embodiment of the groove pattern is characterized in that all pad edges are rounded along the peripheral contour. This has been found to be advantageous in view of the flow around the friction lining pad.

A further preferred embodiment of the groove pattern is characterized in that the pad end radius is equal to or greater than 1 mm. This has been found to be sufficient, taking into account the flow around the friction lining pad.

A further preferred embodiment of the groove pattern is characterized in that the friction lining pads each have one X-shaped embossment, the intersection of which is centrally located with respect to the friction lining pad. The X-shaped embossments, also called cross embossments, are symmetrical. They contain four central grooves arranged in a cross shape, which may also be called main grooves. Furthermore, depending on the size of the friction lining pad, the X-shaped embossments contain further grooves on the side of the four main grooves, which may also be called edge grooves or secondary grooves. These edge grooves or secondary grooves are even only partially formed, depending on the size of the friction lining pad.

A further preferred embodiment of the groove pattern is characterized in that the X-shaped embossments have groove angles of 90-110 degrees radially inward and radially outward, and circumferentially opposite X-shaped embossments have groove angles of 80-110 degrees or 90-110 degrees. The radially inward and radially outward may also be referred to as lower and upper, taking into account the groove angles. Similarly, the opposite circumferential directions may also be referred to as right and left, taking into account the groove angles. Particularly preferred are angles of 85-95 degrees for the opposite circumferential groove angles, i.e. for the right and left groove angles.

A further preferred embodiment of the groove pattern is characterized in that the friction lining pads have a width and height such that for each friction lining pad, the width to height ratio is less than 2.5. The width to height ratio of the friction lining pads is preferably between 3.1 and 2.4. This width to height ratio advantageously applies in both directions in which the friction disc can twist relative to the steel disc.

A further preferred embodiment of the groove pattern is characterized in that the friction lining pads are aligned with the tooth grooves of the internal toothing of the carrier disc. Thus, direct lubrication of the friction lining pads, in particular the X-shaped embossments of the friction lining pads, is made possible in a simple manner.

A further preferred embodiment of the groove pattern is characterized in that the friction lining pads have a split angle of 140-160 degrees. The split angle indicates how obliquely the split grooves extending through the central intersection of the X-shaped embossments of each friction lining pad are disposed relative to the radius.

A further preferred embodiment of the groove pattern is characterized in that all friction lining pads have the same structure and size. This has also proven to be advantageous with respect to the manufacture and installation of the friction lining pads. The term same structure and size includes manufacturing tolerances.

The present invention further relates to a friction lining pad for the groove pattern described above. The friction lining pad can be handled individually.

Further advantages and advantageous embodiments of the present invention are the subject of the following drawings and their description.

FIG. 1 is a diagram showing the relationship between air intake and drag torque. FIG. 1 is a diagram showing problems and improvements. FIG. 1 illustrates a groove design according to the present invention. FIG. 13 illustrates dimensions of groove designs according to the present invention. FIG. 13 illustrates dimensions of groove designs according to the present invention. FIG. 13 illustrates dimensions of groove designs according to the present invention. FIG. 13 illustrates oil flow in a groove design according to the present invention. FIG. 13 illustrates dimensions of groove designs according to the present invention. FIG. 13 illustrates dimensions of groove designs according to the present invention.

Pad division: At least eight pads are arranged in a ring shape, and there is one division groove between each pad (Figure 6 (6), Figure 9)
Pad angle (Figure 4 (1)) is 60 to 120 degrees (see Figures 8 and 9 for details)
The outer edge of the pad is rounded along the periphery, preferably by 1 mm or more (Figure 5 (2))
- A symmetrical cross-shaped impression (X-shaped impression) is placed on the trapezoidal pad (Fig. 7). The intersection of the X-shaped impression is in the center of the lining pad.
The width (3) to height (4) ratio of the pad is less than 2.5 (preferably between 2.1 and 2.4) (Figure 5)
The width of the embossed portion, i.e. the embossed groove (5), is greater than the width of the pad spacing, i.e. the dividing groove (6) (Figure 6)
X-groove angle (Fig. 6):
Upper/lower (7): 90 to 110 degrees,
Right/Left Side (8): 90-100 degrees (preferably 85-95 degrees)
- Alignment of the gear cutting part with respect to the pad: Direct lubrication to the pad (Fig. 7 (9), Fig. 9)
The angle of the dividing section (Figure 9) is 140 to 160 degrees, which is larger than the angle of the overlapping embossing sections (7) and (8) (X-shaped groove angle, Figure 6).
Ratio of the division section (area of the division groove (6)) to the overlapping embossing section (area of the embossing groove (5)) (FIG. 6): at least 1:2, preferably 1:2 to 1:4

In contrast to figures 11 and 12 of WO 2016 180 540 A1, in the case of the groove design according to the invention there is no ring groove, which results in the following advantages:
- Improved friction force application and utilization of thermal mass lost due to existing ring grooves.
-Improvement of wear characteristics of lining materials.
- The rotationally symmetric trapezoidal honeycomb provides uniform cooling and lubrication.
- Improved friction value build-up due to more effective oil drainage.

Unlike US 2007 0000 747(A1), the groove design according to the present invention has split grooves of equal groove width between pads for internally lubricated friction systems to compensate for oil transport or stagnation effects.

In addition, the groove design of the present invention does not have purely radial grooves in order to reduce the lubricating effect of the groove edges when the friction system is switched (open/closed) and prevent hydroplaning.

The groove design of the present invention may be referred to as a trapezoidal honeycomb design, which has a trapezoidal pad with an X-groove honeycomb embossed section.

The overlapping embossing section results in less fibrousness in the punched pad (reduced drag torque).

The ratio of the division section (division groove) to the overlapping embossing section (embossing groove) to the number of divisions is at least 1:2, preferably 1:2 to 1:4. This allows both cooling and de-oiling of the friction system (see FIG. 7). By adjusting the overlapping embossing section, the cooling oil can be appropriately guided to the opposing friction disc (see FIG. 7), thereby improving the convective heat transfer (cooling). At the same time, the separation of the discs (using lubricating oil) can be performed in an open state, improving the air intake (reducing drag torque).

In FIG. 1 it is specifically shown how the delivered volumetric flow 24 causes air intake 26 when it exceeds the supplied volumetric flow 25. Beyond this limit, the gap volume efficiency 26 decreases and the lubrication gap contains air. Beyond this limit, the supplied volumetric flow 25 contains air. At the bottom of FIG. 2 it is shown that air intake 26 occurs for maximum drag torque 27.

Figure 2 shows how the stressed friction section 15 achieves a shift in the drag torque curve 30 to lower air intake 28 speeds. The groove pattern shown in Figure 3 improves the transport of cooling and/or lubricating media.

In Figures 3 to 9, a groove pattern 10 according to the present invention, also referred to as a groove design, is shown. The groove pattern 10 comprises friction lining pads 11, 12 arranged on a carrier disk 18. The carrier disk 18 with the friction lining pads 11, 12 is referred to as a friction disk 19.

The friction lining pads 11, 12 all have a trapezoidal structure with rounded ends. The friction lining pads 11, 12 are spaced apart from one another in the circumferential direction, so that a dividing groove 9, 13, 14 is formed between each two adjacent friction lining pads 11, 12. The dividing grooves 9, 13, 14 are limited to the depth of the carrier disk 18.

In FIG. 3, the short base side of the trapezoidal friction lining pad 11 is arranged radially inward. The short base side of the trapezoidal friction lining pad 12 is arranged radially outward. This results in the dividing grooves 9, 13 being arranged obliquely to the radius and in opposite directions, as shown in FIG. 3.

Furthermore, in FIG. 3, the carrier disk 18 is shown to have an internal toothing 17 with teeth 15 and tooth spaces 16 between the teeth 15. The friction lining pads 11, 12 are each assigned to a tooth space 16.

Furthermore, the friction lining pads 11, 12 are provided with an X-shaped embossment 40. In FIG. 3, the friction lining pad 12, together with its X-shaped embossment 40, is shown aligned with the tooth groove 16 of the internal toothing 17 of the carrier disk 18.

In FIG. 4, the friction lining pad 12 is shown to include a total of eight embossed grooves 41-48 along with an X-embossed portion 40. The embossed grooves 41-44 are arranged in a cross shape, with the X represented by a center 49 indicated by a circle in the center of the friction lining pad 12. The friction lining pad 12 is symmetrical about a centrally located axis of symmetry 50.

The embossed grooves 41-44 are also referred to as main or central grooves. The embossed grooves 45-48 are also referred to as edge or secondary grooves. The edge grooves 45 and 46 are not always completely formed due to the trapezoidal structure of the friction lining pad 12.

Each pad end of the friction lining pad 12 is assigned a pad interior angle 1. At least eight trapezoidal friction lining pads 11, 12 are preferably mounted on the carrier disk 18. The angle of the pad interior angle 1 is between 60 and 120 degrees.

In FIG. 5, the width of the friction lining pad 12 is indicated by the double arrow 3. The height of the friction lining pad 12 is indicated by the double arrow 4 in FIG. 5. All ends of the friction lining pad 12 are provided with a rounding radius 2.

In FIG. 6, the groove width of the embossed groove 41 in the friction lining pad 12 is indicated by a double arrow 5. The groove width of the dividing groove 13 is indicated by a double arrow 6. All dividing grooves 9, 13 preferably have substantially the same groove width 6. The embossed grooves 41-48 also preferably have substantially the same groove width 5.

The groove angle between embossed groove 43 and embossed groove 44 is indicated by double arrow 7. Groove angle 7 is also referred to as radially inner or lower groove angle 7. Similarly, groove angle 7 between embossed groove 41 and embossed groove 42 is also referred to as radially outer or upper groove angle 7.

The groove angle between embossed groove 41 and embossed groove 43 on the left side of FIG. 6 is indicated by double arrow 8. The similar groove angle between embossed groove 42 and embossed groove 44 is referred to as the right groove angle. Left groove angle 8 and right groove angle 7 are also referred to as circumferentially opposed groove angles.

In FIG. 7, the four pad ends are assigned the reference numbers 31-34. All pad ends 31-34 of the friction lining pad 12 are rounded. The friction lining pad 12 is aligned with its long base side in the center of the tooth groove 16 of the internal toothing 17 of the carrier disk 18.

The arrows 59 indicate the inflowing cooling medium, in particular oil. The oil 59 is supplied, for example, via the external toothing of a disk carrier (not shown). In FIG. 7, the arrows 51-54 show how the oil 59 supplied radially inward is distributed to the X-shaped impressions 40 of the friction lining pad 12. The oil 59 then flows out radially outward of the friction disk 19.

In FIG. 8, the pad interior angles of friction lining pads 11 and 12 are indicated by double-headed arrows 61-64 and 71-74. The pad interior angles 61-64 are 61.5 degrees, 119.8 degrees, 119.8 degrees, and 61.5 degrees. The pad interior angles 71-74 of friction lining pad 12 are 115.3 degrees, 163.4 degrees, 163.4 degrees, and 115.3 degrees.

In FIG. 9, the split angle is indicated by double arrows 77, 78. Split angle 77 is 147.5 degrees and is sandwiched between dashed and dotted lines 76 and 79. Dashed line 76 coincides with the radial axis of symmetry of friction lining pad 11. Dashed line 79 extends along the left leg of friction lining pad 11 in FIG. 9.

The split angle 78 is 157.5 degrees and is sandwiched between dashed lines 50 and 80. The dashed line 50 coincides with the radial axis of symmetry of the friction lining pad 12. The dashed line 80 extends tangent to the right leg of the friction lining pad 12 in FIG. 9.

1 Pad inner angle 2 Radius 3 Width 4 Height 5 Groove width 6 Groove width 7 Groove angle 8 Groove angle 9 Dividing groove 10 Groove pattern 11 Friction lining pad 12 Friction lining pad 13 Dividing groove 14 Dividing groove 15 Tooth 16 Tooth groove 17 Internal toothing 18 Carrier disk 19 Friction disk 20 x-axis 21 y-axis 22 y-axis 23 y-axis 24 Conveyed volume flow 25 Supplied volume flow 26 Air intake 27 Drag torque 28 Air intake 30 Drag torque curve 31 Pad end 32 Pad end 33 Pad end 34 Pad end 40 X-embossed portion 41 Embossed groove 42 Embossed groove 43 Embossed groove 44 Embossed groove 45 Embossed groove 46 Embossed groove 47 Embossed groove 48 Embossed groove 49 Center 50 Axis of symmetry 51 Arrow 52 Arrow 53 Arrow 54 Arrow 57 Arrow 58 Arrow 59 Arrow 61 Inner pad angle 62 Inner pad angle 63 Inner pad angle 64 Inner pad angle 71 Inner pad angle 72 Inner pad angle 73 Inner pad angle 74 Inner pad angle 76 Axis of symmetry 77 Partition angle 78 Partition angle 79 Line 80 Line

Claims (7)

A groove pattern (10) for a friction disc (19), said groove pattern (10) being formed using friction lining pads (11, 12), said friction lining pads (11, 12) having a trapezoidal structure, in the groove pattern (10), each friction lining pad (11, 12) having embossed grooves (41-48),
The groove pattern (10) comprises at least eight trapezoidal friction lining pads (11, 12) arranged in a ring, the friction lining pads (11, 12) being arranged in a circumferential direction with the longer base sides of the trapezoids aligned alternately radially inward and radially outward, one dividing groove (9, 13, 14) being arranged between each two adjacent friction lining pads (11, 12), the embossed grooves (41-48) in the friction lining pads (11, 12) have a groove width (5) larger than the dividing grooves (8, 13, 14), the friction lining pads (11, 12) each have one X-shaped embossment (40), and an intersection (49) of the X-shaped embossment (40) is arranged centrally with respect to each friction lining pad (11, 12) . The groove pattern of claim 1, characterized in that the ratio of the area of the dividing grooves (9, 13, 14) to the area of the embossed grooves (41-48) is between 1:2 and 1:4. The groove pattern according to claim 1 or 2, characterized in that the X-shaped embossments (40) have groove angles (7) of 90 to 110 degrees on the radially inner side and the radially outer side, and the X-shaped embossments (40) have groove angles (8) of 80 to 110 degrees or 90 to 110 degrees on opposite sides in the circumferential direction. 4. A groove pattern according to claim 1, wherein the friction lining pads (11, 12) have a width (3) and a height (4) such that for each friction lining pad (11, 12 ) the ratio of the width (3) to the height (4) is less than 2.5. A groove pattern according to any one of claims 1 to 4 , characterized in that the friction lining pads (11, 12) are aligned with the tooth spaces (16) of the internal toothing (17) of the carrier disc (18). A groove pattern according to any one of claims 1 to 5 , characterized in that the split angle (77, 78) of the friction lining pads (11, 12) is between 140 and 160 degrees. Friction lining pads (11, 12) for a groove pattern (10) according to any one of claims 1 to 6 .

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