Patent ID: 12215775

As shown inFIG.1, the dual clutch transmission system1comprising a shaft assembly4comprising the first shaft part20, the second shaft part10and the transmission member30. The transmission member30may also be referred to as a third shaft part. The transmission member30may be arranged to transfer torque from an internal combustion engine. The shaft assembly extends along the central axis2.

The second shaft part10may be rotatably arranged in the transmission system1and comprises a bore12, a lubricant inlet opening16through which a flow of lubricant may enter the bore12, an axial end18and a lubricant outlet opening14through which a part of the lubricant flow may exit the bore12for lubricating at least a part of the transmission system1.

The first shaft part20may be rotatably arranged in the transmission system1and comprises a bore22extending through the first shaft part20from first axial end25to the second axial end21. The second axial end21is rotatably attached to the axial end18of the second shaft part10. Together, bore12and bore22define a part of a first lubricant channel.

The transmission member30may comprise a first axial end31and a second axial end36relative to the central axis2, wherein the first axial end31is configured to be rotatably connected to the first shaft part20at the first axial end25thereof. The transmission member30comprises a bore32extending along the central axis2from the first axial end31in a direction towards the second axial end36. The bore32is open at the first axial end31. The second axial end may be a closed bore end36opposite the first axial end31.

FIGS.2and4show another transmission system100, wherein all features are the same as described for transmission system1, except that shaft assembly104comprises the first shaft part20, the second shaft part10and the transmission member60, which comprises a stepped bore end instead of the conventional bore end36of transmission member30. Transmission member60may comprise a first axial end61and a second axial end66relative to the central axis2, wherein the first axial end61is configured to be rotatably connected to the first shaft part20. The transmission member60may comprise a bore62extending along the central axis2from the first axial end61in a direction towards the second axial end66. The bore62is open at the first axial end61. The second axial end may be a closed bore end66opposite the first axial end61. As is better visible inFIG.5, the bore62comprises a stepped closed bore end section63in which a diameter of the bore decreases stepwise towards the closed bore end66.

The bore62has a first diameter508in main bore section500adjacent to the stepped closed bore end section63, wherein the stepped closed bore end section63comprises a first diameter decreasing section502in which the bore diameter decreases from the first diameter508to a second intermediate diameter510and a second diameter decreasing section506in which the diameter of the bore62decreases from the second intermediate diameter510towards zero at the closed bore end66.

The stepped closed bore end66comprises a constant diameter section504having the second intermediate diameter510and positioned between the first diameter decreasing section502and the second diameter decreasing section506.

A ratio between the second intermediate diameter and the first diameter is in the range of 0.3 to 0.9, preferably in the range of 0.4 to 0.8, most preferably in the range of 0.51 to 0.78. For example, the diameter508may be 9 mm, while the diameter510may be 5 mm, with a ratio of about 0.55.

The transmission member30comprises a lubricant outlet opening34for allowing a lubricant fluid flow entering the transmission member at the first axial end31to exit the bore32, wherein the lubricant outlet opening34is positioned along the bore32between the first axial end31and the bore end36and extends from the bore32towards an outer surface of the transmission member30in order to, in use, provide lubricant to at least a part of the dual clutch transmission system1.

Likewise the transmission member60comprises a lubricant outlet opening64for allowing a lubricant fluid flow entering the transmission member at the first axial end61to exit the bore62, wherein the lubricant outlet opening64is positioned along the bore62between the first axial end61and the stepped closed bore end66and extends from the bore62towards an outer surface of the transmission member60in order to, in use, provide lubricant to at least a part of the dual clutch transmission system100.

The bore32and bore62of respectively the transmission member30and60may be referred to as first bore32and first bore62respectively, while the bore22of the first shaft part20may be referred to as a second bore22.

The second bore22comprises a main section and an insert receiving section23at the first axial end25of the first shaft part20adjacent to the main section. The first shaft part20is rotatably connected at the insert receiving section25to the transmission member30(FIGS.1and3) or60(FIGS.2and4) at the first axial end31resp.61of the transmission member30resp.60.

A hollow tube shaped insert40is placed in the bore22at the insert receiving section23. The first lubricant channel thus also extends along the central axis2through the second bore22and an inside of the hollow tube shaped insert40. An outer diameter of the hollow tube shaped insert40is smaller than an inner diameter of the second bore22at the insert receiving section23such that a second channel47is arranged between an outer side of the hollow tube shaped insert40and an outer circumference of the bore22at the insert receiving section23and concentrically relative to the first channel. The first channel and the second channel are thus separated from each other.

The hollow tube shaped insert40comprises a first end section extension43extending from the first end25of the first shaft part20and into at least a part of the first bore32. An outer diameter of the first end section extension43is such that a lubricant flow path44is formed between an outer side of the first end section extension43and the part of resp. the first bore32and the first bore62into which the first end section extension43extends such that in use lubricant flows from the first bore32or the first bore62through the flow path44to lubricate at least a part of respectively the dual clutch transmission system1or the dual clutch transmission system100.

The first shaft part20may comprise an actuation fluid inlet46and an actuation fluid outlet48in the insert receiving section23such that the second channel47represents an actuation fluid channel. In the transmission systems1and100, the actuation fluid inlet46and actuation fluid outlet48are aligned with respective actuation fluid channels of the dual clutch transmission system such that the actuation fluid is used for selectively coupling at least one of the transmission members of the dual clutch transmission system. For instance, one or more pistons may be actuated for activating one or more respective clutches.

Preferably, the main section of the bore21has a third diameter and the insert receiving section23has a fourth diameter, wherein the fourth diameter is larger than the third diameter. More preferred is that an inner diameter of the hollow tube shaped insert40is substantially equal to the third diameter of the bore21.

The hollow tube shaped insert40may comprise a first sealing member50and a second sealing member52at an outer side of the hollow tube shaped insert40for separating the second channel47that is formed between the first50and second52sealing members is separated from the first channel represented by the bores12,22and32/62. The sealing members50and52may comprise O-rings held between respective protrusions extending from the outer circumference of the hollow tube shaped insert40.

The main section of the first shaft part20comprises lubricant outlet openings24,26and28at respective axial positions along the central axis2. Lubricant can thus flow from the second end21of the first shaft part20into the lubricant outlet openings24,26and28.

InFIGS.6and7, a comparison is made of lubricant flow through openings24,26,28,44and34of transmission system2with a conventional bore end36and lubricant flow through openings24,26,28,44and64of transmission system100with the improved stepped bore end66of the present patent disclosure.FIG.6shows results of the flow rates at the various openings in liter per minute at a rotational speed of 5000 RPM and an inlet flow of 1.6 liter per minute, whileFIG.7shows results of the flow rates at the various openings in liter per minute at a rotational speed of 1500 RPM and an inlet flow of 1.6 liter per minute. InFIGS.6and7, “baseline” indicates the results for the transmission system1with the conventional bore end36. The dataset “stepped_1.2 mm” indicates the results for the transmission system100with the bore end66with diameter508of 9 mm and a step of 1.2 mm at section502, thus making the diameter510equal to 9−2.4=6.6 mm. The dataset “stepped_2.2 mm” indicates the results for the transmission system100with the bore end66with diameter508of 9 mm and a step of 2.2 mm at section502, thus making the diameter510equal to 9−2.4=4.6 mm.

At 5000 RPM (FIG.6), it can be seen that the flow at opening24is increased for both stepped datasets, while the flow is reduced at openings44and64. The flow at openings26and28remains roughly the same, thus achieving the goal of increasing the flow farther away from the bore end66in the transmission member60, and decreasing the flow closer to the bore end66.

Also at 1500 RPM (FIG.7), it can be seen that the flow at opening24is increased for both stepped datasets, while the flow is reduced at openings44and64. The flow at openings26and28remains roughly the same, thus also achieving the goal of increasing the flow farther away from the bore end66in the transmission member60, and decreasing the flow closer to the bore end66, at lower rotational speeds.

FIG.8is a schematic cross-sectional view of an embodiment of a transmission system1000comprising the embodiments of respective aspects of the invention, wherein said transmission system1000comprises at a first end input shaft1001, a dual-clutch assembly1010comprising first clutch assembly1011and second clutch assembly1012, wherein the first and second clutch assemblies1011,1012are arranged coaxially. The first and second clutch assemblies1011,1012comprise respective first and second outer carriers1014,1015that are interconnected by means of drive plate1013that is rotatably supported by bearing unit1016. At a second, opposite end, the transmission system1000further comprises a third clutch assembly1003. The clutch assemblies1011,1012,1003in the embodiment shown are so called multi-plate clutches.

Such multi-plate clutch assemblies1011,1012,1003comprise at least one friction coupling member comprising a respective inner carrier1017,1018,1005and a respective outer carrier1014,1015,1006, wherein at least one of said inner1017,1018,1005and outer carriers1014,1015,1006is rotatable around a first axis, each comprising a friction element assembly1021,1022,1004comprising a respective first set of plates is rotatably connected to the inner carrier1017,1018,1005and arranged between the inner1017,1018,1005and outer carrier1014,1015,1006and a second set of plates is rotatably connected to the outer carrier1014,1015,1006and arranged between the inner1017,1018,1005and outer carrier1014,1015,1006, wherein the plates of the respective first and second set of plates are, as seen in an axial direction I along said first axis, alternately arranged and overlapping in the radial direction, wherein, in a coupled state, the respective alternately arranged plates of the first and second set abut each other, such that a torque can be transferred from the inner1017,1018,1005to the outer carrier1014,1015,1006and wherein, in an uncoupled state, the respective alternately arranged plates of the first and second set are spaced apart, such that said outer carrier1014,1015,1006is arranged to rotate relative to said inner carrier1017,1018,1005.

FIG.9is a schematic cross-sectional view zoomed in on an embodiment of a clutch assembly1011for a transmission system1000showing the outer carrier1014, the friction element assembly1021and the drive plate1013. The outer carrier1014comprises a radially extending flange section1032that extend, with respect to outer carrier1014in the radial direction II. The annular contact section1033is provided with a welded section1031for fixedly connecting the outer carrier1014to the drive plate1013. The weld1031is preferably made from a radial outer edge1034in an inwardly radial direction III. The weld, preferably, does not extend beyond the inner surface1035of the outer carrier1014.

FIG.10is a schematic cross-sectional view zoomed in on a second embodiment of a clutch assembly1012for a transmission system1000. Drive plate1013, which abuts a plate of the friction element assembly1022, is welded to the outer carrier1015at a welded section1041that runs parallel to the axial direction I between the drive plate1013and the outer carrier1015. In the three-dimensional schematic view ofFIG.11it is seen that the plate1042is rotationally locked to the outer carrier1015by means of spline protrusion1043. Said spline protrusions1043and sections1045of said outer carrier1015extend in the axial direction I and are received in cooperating through holes1044arranged in the drive plate1013. In the specific embodiment, each of the axially extending splines1043and sections1045are received in a cooperating through hole1044. The welded sections1041fixedly interconnecting the axially extending splines1043and sections1045to the drive plate1013comprise a start and end section1046,1047and a central section1048, as explained earlier.

FIG.12is a three-dimensional schematic view zoomed in on a central mounting hub1060of an embodiment of an annular drive plate1013for a clutch assembly for a transmission system1000. The central mounting hub1060is formed by an annular protruding section and comprises a first portion1063and a mounting portion1062that is arranged for mounting the bearing1051. The first portion1063and mounting portion1062are delimited in the axial direction I by means of a radially inwardly extending axial abutment section1061for limiting an axial movement of a mounted bearing1051in one direction parallel to the axial direction I. The radially inwardly extending axial abutment section1061comprises ridge sections1066and valley sections1067along its perimeter. A ridge section1066extends further inwardly in the radial direction along direction III as compared to a valley section1067and the ridge sections1066and valley sections1067are alternatively arranged on the perimeter of the radially inwardly extending axial abutment section1061. A contact surface1068of the radially inwardly extending axial abutment section1061contacts the bearing1051, in particular an axial end of the outer ring1052comprising outer raceway of the bearing1051. The outer surface of the outer ring1052contacts a machined surface1069arranged in the mounting portion1062, thereby locking the bearing1051in all radial directions with respect to the annular drive plate1013.

The ridges1066are formed by plastically deforming, preferably by means of punching, alternating sections of a first portion1063of the inner radial circumference of said annular protruding section1060to displace material of the alternating sections1070of the first portion1063for forming alternate ridge sections1066on the axial abutment section1061. Thereby the thickness t1of the alternating sections1070is locally reduced, when compared to the nominal thickness t2of the annular protruding section1060. By not plastically deforming the entire circumference of the annular protruding section1060, but only alternating sections1070, a relatively stiff annular protruding section1060is maintained, while still enabling the formation of a stiff and reliable radially inwardly extending axial abutment section1061. This allows the drive plate1013to be manufactured from flat plate material, such as sheet metal, by means of drawing. A cross-sectional three-dimensional schematic view of such a drawn drive plate1013is shown inFIG.13, which also shows the cooperating through holes1044as discussed earlier.

FIG.14is a schematic cross-sectional view zoomed in on an embodiment of an unassembled clutch subassembly1200for assembly onto a transmission system1000for a vehicle. Clutch subassembly1200comprising at least a torque transmission assembly1201comprising a rotatable inner carrier and an subassembly housing member1210and a friction element assembly1221arranged between the inner carrier and subassembly housing member1210. The friction element assembly1221comprises coupling plates1222that are rotatably connected to the subassembly housing member1210by means of a spline connection1225(seeFIG.14). Between the coupling plates1222, friction plates1223and biasing members1224are arranged, wherein the biasing members1224urge the respective plates1222,1223into a second axial direction I2that is parallel to the axial direction, as the friction element assembly1221is constrained at a first axial end in a first axial direction I1along the axis by said subassembly housing member1210. Due to this urging action of the biasing members1224, the respective plates1222,1223are biased towards an uncoupled state wherein the respective plates1222,1223are space apart, i.e. the unengaged state. An axial constraining system1230is provided for limiting the movement of the respective plates1222,1223in the second axial direction I2, such that they cannot fall out of an open second end1213of the subassembly housing member1210in the unassembled state.

The axial constraining system1230is hereto provided with a plurality of retaining bolts1231, preferably at least three retaining bolts1231, wherein the friction element assembly1221abuts a contact surface1232of said retaining bolt1231that is placed in a retaining bolt bore1234arranged in a spline protrusion1235of the subassembly housing member1210.

The subassembly housing member1210can be mounted and fixed, for instance by bolts, in a transmission system housing1240that comprises a friction element assembly contacting surface1241that is arranged to be received in the open second end1213of the subassembly housing member1210. Upon assembly, the friction element assembly1221, in particular an outer coupling plate1222, contacts the friction element assembly contacting surface1241thereby pushing it in the first axial direction I1, such that a non-zero distance d1is obtained between the contact surface1232of said retaining bolt1231and the respective coupling plate1222. The retaining bolt1231is then received in a corresponding space arranged in the transmission system housing1240, such that it does not need to be removed. A sealing member1212is arranged for sealing an interior of the transmission system housing1240.

The description of the different illustrative configurations has been presented for purposes of illustration and description and is not intended to be exhaustive or limited to the configurations in the form disclosed. Many modifications and variations will be apparent to those of skill in the art. Further, different illustrative configurations may provide different features as compared to other illustrative configurations. The configuration or configurations selected are chosen and described in order to best explain the principles of the configurations, the practical application, and to enable others of ordinary skill in the art to understand the disclosure for various configurations with various modifications as are suited to the particular use contemplated.