Clutch ring gear assembly and method of construction thereof

A clutch ring gear assembly and method of construction thereof are provided. The assembly has a bearing seat including a flange extending radially outwardly from a central axis. The flange has a plurality of holes spaced circumferentially from one another about the central axis. A ring gear carrier includes a rim extending radially outwardly from the central axis. The rim has a plurality of through openings. Each of the through openings of the rim has an annular boss extending axially away from the rim in generally parallel relation to the central axis. The annular bosses are disposed within the holes and have hollow, annular end portions flared radially outwardly into engagement with the flange of said bearing seat to fixedly attach the ring gear carrier to the bearing seat.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present disclosure relates generally to vehicle clutch assemblies, and more particularly to ring gear assemblies including a ring gear carrier fixedly attached to a separate bearing seat and to their methods of construction.

2. Related Art

It is known to construct a clutch ring gear assembly for a transmission clutch assembly, wherein the clutch ring gear assembly includes a ring gear carrier fixedly attached to a separate bearing seat, also referred to as a bearing hub or simply hub. One known mechanism employed for fixedly attaching a ring gear carrier to a bearing seat includes welding the ring gear carrier to the bearing seat. However, welding can be costly, and further yet, a weld joint formed thereby results in hardened heat-affected zones, thereby impacting the material properties of the separate components in ways unintended, and can further result in heat distortion of parts and contamination from splatter. Another known mechanism employed for fixedly attaching a ring gear carrier to a bearing seat includes using a spline and snap ring arrangement; however, this increases the complexity of the assembly, increases the number of component parts required, increases the cost associated with assembly, and requires an undesirable increase in the axial space or envelop of the assembly. Yet another known mechanism employed for fixedly attaching a ring gear carrier to a bearing seat is taught in U.S. Pat. No. 9,022,196, wherein a plurality of circumferentially aligned and enclosed rectilinear slots are formed in a ring gear, with the increased length of the slot extending circumferentially and the decreased width extending radially, and a corresponding plurality of solid protrusions, having a similar rectilinear shape as the rectilinear slots, on a bearing seat are fixed within the slots. The protrusions are formed to extend from the bearing seat for receipt in the rectilinear slots, whereupon ends of the protrusions are punched by an anvil to form circumferentially extending grooves in the ends of the protrusions, causing material of the protrusions to be displaced to form radially outwardly and inwardly extending segments. However, due to the configurations of the slots, the protrusions, and the resulting assembly, problems exist, namely, the process associated with the manufacture of the rectilinear slots is complex, both from a tooling and forming extent, and the cost associated with the manufacture is high. Further yet, the grooves formed in the ends of the protrusions form a source for crack propagation, both during manufacture, thereby resulting in scrap, or while in use of the vehicle, thereby resulting in a potential need to service the vehicle.

A clutch ring gear constructed in accordance with the invention addresses at least those problems discussed above, as well as others that will be readily apparent to those possessing ordinary skill in the art of clutch assemblies.

SUMMARY OF THE INVENTION

This section provides a general summary of the disclosure and is not intended to represent a comprehensive summary of all of its features, advantages, aspect and/or objectives.

It is an aspect of the present disclosure to provide a clutch ring gear assembly having a bearing seat including a flange extending radially outwardly from a central axis, with the flange having a plurality of holes spaced circumferentially from one another about the central axis. Further having a ring gear carrier including a rim extending radially outwardly from the central axis, with the rim having a plurality of through openings. Each of the through openings has an annular boss extending axially away from the rim in generally parallel relation to the central axis. The annular bosses are configured for receipt through the holes and have annular, hollow end portions flared radially outwardly into engagement with the flange of said bearing seat to fixedly attach the ring gear carrier to the bearing seat.

It is another aspect of the present disclosure to provide the flared end portions of the bosses being flared to a frustroconical shape to facilitate retaining the ring gear carrier in fixed attachment with the bearing seat.

It is another aspect of the present disclosure to provide the holes having annular, conically tapered edges, with the annular, radially outwardly flared end portions being engaged with the tapered edges.

It is another aspect of the present disclosure to provide the annular bosses being entirely hollow.

It is another aspect of the present disclosure to provide the ring gear carrier having a cylindrical outer wall, with the rim extending radially inwardly from the cylindrical outer wall.

It is another aspect of the present disclosure to provide the bearing seat having a cylindrical inner wall, with the flange extending radially outwardly from the cylindrical inner wall.

It is another aspect of the present disclosure to provide the bearing seat and the ring gear carrier as dissimilar materials.

It is another aspect of the present disclosure to provide the bearing seat and the ring gear carrier as similar materials.

It is another aspect of the present disclosure to provide the bosses including annular concave, radially outwardly facing channels bounded by the radially flared end portions and the rim, wherein the flange of the bearing seat is fixed about its entire periphery in the annular concave channels by the overlying radially flared end portions, thereby forming a reliable, secure fixation of the bearing seat to the ring gear carrier.

It is another aspect of the present disclosure to provide the holes having a rounded edge transitioning to one side of the flange and a tapered edge transitioning to an opposite side of the flange, wherein the rounded edge conforms to a fillet radius of the bosses to form a snug, tight fit therebetween and the tapered edge conforms to the radially flared end portions of the bosses to form a snug, tight fit therebetween, thereby forming a reliable and secure attachment of the ring gear carrier to the bearing seat.

It is another aspect of the present disclosure to provide the holes as circular openings and to provide the bosses having a corresponding cylindrical outer surface for close receipt within the circular openings, thereby forming a relatively low stress, stress riser free connection between the holes and the bosses.

It is another aspect of the present disclosure to provide a method of constructing a clutch ring gear assembly. The method includes forming a bearing seat having a flange extending radially outwardly from a central axis; forming a plurality of holes through the flange in circumferentially spaced relation from one another about the central axis; forming a ring gear carrier having a rim extending radially outwardly from a central axis; forming a plurality of through openings in the rim and forming each of the through openings having an annular boss extending axially away from the rim; disposing each of the annular bosses through the holes of the bearing seat; and flaring end portions of the bosses radially outwardly into engagement with the flange of the bearing seat to fixedly attach the ring gear carrier to the bearing seat.

It is another aspect of the present disclosure to include forming the end portions having a hollow, frustroconical shape.

It is another aspect of the present disclosure to include forming the holes having a conically tapered edge and engaging the radially outwardly flared end portions with the tapered edge to provide a reliable, secure attachment of the bearing seat to the ring gear carrier.

It is another aspect of the present disclosure to include forming the annular bosses being entirely hollow, thereby reducing weight of the assembly while at the same time providing an ability to form a reliable, relatively low stress, stress riser free attachment of the bearing seat to the ring gear carrier.

It is another aspect of the present disclosure to include forming the ring gear carrier having a cylindrical outer wall with the rim extending radially inwardly from the cylindrical outer wall.

It is another aspect of the present disclosure to include forming the bearing seat having a cylindrical inner wall with the flange extending radially outwardly from the cylindrical inner wall.

It is another aspect of the present disclosure to include forming the bosses having annular concave channels bounded by the radially flared end portions and the rim and fixing the flange of the bearing seat in the annular concave channels to provide a reliable, secure attachment of the bearing seat to the ring gear carrier.

It is another aspect of the present disclosure to include forming the holes having rounded edges transitioning to one side of the flange and a tapered edges transitioning to an opposite side of the flange with the rounded edges conforming to a fillet radius of the bosses and the tapered edge conforming to the radially flared end portions of the bosses such that the radially flared end portions extend about the entirety of the circumference of the tapered edges in abutment therewith to enhance the ability to provide a reliable, secure attachment of the bearing seat to the ring gear carrier.

It is another aspect of the present disclosure to include forming the bearing seat having a cylindrical inner wall with the flange extending radially outwardly from the cylindrical inner wall.

It is another aspect of the present disclosure to include attaching the ring gear carrier to the bearing seat in a transfer die process, thereby streamlining and simplifying the manufacture process, thus, reducing the cost associated with manufacture.

DETAILED DESCRIPTION OF PRESENTLY PREFERRED EMBODIMENTS

Referring in general to all of the figures, the present disclosure and teachings described herein are directed to clutch assemblies, and in particular, ring gear assemblies therefor, of the type particularly well-suited for use in motor vehicle applications. While disclosed in accordance with one or more specific exemplary constructions, a clutch ring gear assembly10of the present disclosure may be configured for operable use in any desired vehicle platform. The inventive concepts disclosed are generally directed to an improved connection and method of forming a connection between a ring gear carrier12and a bearing seat14of the ring gear assembly10for vehicle clutch assemblies. The improved connection and method of forming the connection is economical in manufacture and provides a reliable, strong and durable connection between the ring gear carrier12and bearing seat14to enhance the useful life the assembly10.

The ring gear carrier12can be constructed of any suitable metal material, including aluminum or steel, by way of example and without limitation. The ring gear carrier12can be constructed in a progressive transfer die process, such as shown inFIGS. 12A-12P, by way of example and without limitation. In the forming process, the ring gear carrier12is formed having a generally cylindrical outer wall16that extends generally parallel about a central axis18with an annular radially disposed portion or flange, also referred to as rim20, extending radially inwardly from the generally cylindrical outer wall16to an annular inner periphery22. The rim20separates, at least in part, a front side FS of the clutch ring gear assembly10from a back side BS of the assembly10and bounds a central opening24sized for receipt of at least a portion of the bearing seat14therein. In the continuous transfer die process shown,FIGS. 12A-12Dshow respective first and second drawing processes;FIGS. 12E-12Fshow a further drawing process and radii re-striking process;FIGS. 12G-12Jshow rolling processes wherein an outer surface of the cylindrical outer wall16is contoured;FIGS. 12K-12Lshow a further rolling process and a piercing process that is used to initiate forming the through openings26;FIGS. 12M-12Nshow a process for completing the through holes26and bosses28; andFIGS. 120-12Pshow a process for forming the annular inner periphery22. It is contemplated herein that fewer or additional processes could be used in a transfer die process in accordance with the invention. It is also contemplated that other processes could be used to form the ring gear carrier12within the spirit of the invention.

The rim20has opposite sides21,23, with the side21facing the front side FS and the opposite side23facing the back side BS. In an example embodiment, a plurality of through openings26is formed extending through the sides21,23of the rim20adjacent the annular inner periphery22. The through openings26are bounded circumferentially, and as such, are wholly surrounded by material of the rim20. The through openings26can be formed in any desired number and arrangement, and in an example embodiment, a plurality of six through openings26are formed in circumferential alignment with one another and in equidistantly spaced relation from one another. However, it is contemplated that the through openings26could be arranged otherwise, including being radially staggered from one another, thus, not being in circumferential alignment, and being spaced in non-uniform relation from one another, if desired for the intended application. The through openings26are preferably formed, at least in part, in a material displacement process, such as a drawing and piercing process (FIG. 10A-10C) or in a piercing and punching process (FIG. 11A-11B), wherein material of the rim20is extended or deformed axially (with reference to the central axis18) toward the back side BS, whereupon the through opening26is ultimately formed. As such, the through opening26is bounded by an axially extending, generally cylindrical wall forming an annular protrusion or boss28that terminates at an annular distal end, also referred to as free end30, wherein the rim20extends radially inwardly from the bosses28to the annular inner periphery22. The through openings26and bosses28form hollow, generally tubular passages, shown as being cylindrical, that extend axially between the opposite front and back sides FS, BS. With the bosses28being hollow, weight reduction of the assembly10can be recognized. The bosses28transition to the side23, also referred to as back side, of the radially extending rim20via annular, arcuate concave radii, also referred to as fillets29. In the forming embodiment ofFIGS. 10A-10B, it can be seen that material is drawn in a cold forming process to form the desired geometry of the boss28, and then, as shown inFIG. 10C, the base of the deep drawn material is pierced to complete formation of the through opening26and boss28. In contrast, as shown inFIG. 11A, the through openings26can be first initiated, such as in a drilling or piercing operation, and then, as shown inFIG. 11B, a punch46, having the desired configuration, including a nose portion50and a radially outwardly extending annular flared portion52, can be used to first form the finished shape of the preassembled boss28. Then, as discussed further hereafter, the same punch46, or different if desired, can be used, as shown inFIG. 11C, to plastically deform an end region of the boss28to fixedly attach the ring gear carrier12to the bearing seat14. Further discussion regarding the process of constructing the assembly10is provided hereafter.

The bearing seat14is constructed, at least in part, of bearing grade metal, such as bearing grade steel, and as such, depending on what type of material is selected for the ring gear carrier12, the bearing seat14and ring gear carrier12can be constructed of similar or dissimilar materials, thereby providing a wide range of options, as desired for the intended application. This can result in manufacturing and economic efficiencies if less costly materials are used for one of the components12,14. Dissimilar materials are able to be used primarily as a result of the improved connection mechanism used to fix the components12,14to one another, which is generally not possible or reliable with welding mechanisms. The bearing seat14has an annular inner wall32, shown as being a cylindrical, generally cylindrical or substantially cylindrical wall, that extends axially in generally parallel relation to the central axis18with an annular radially disposed portion, also referred to as flange34, shown as being generally or substantially planar, extending radially and generally outwardly from the inner wall32and generally transversely away from the central axis18to an annular outer periphery36and having opposite sides37,39separating the front side FS of the assembly10from the back side BS of the assembly10, with the side37facing the front side FS and the opposite side39facing the back side BS. In an example embodiment, a plurality of through openings, also referred to as holes38, are formed in the flange34adjacent the outer periphery36. The holes38are bounded circumferentially, and as such, are wholly surrounded by material of the flange34. The holes38are sized for receipt of the ring gear carrier annular bosses28therethrough, preferably in a line-to-line or slight clearance fit to facilitate assembly of the ring gear carrier12to the bearing seat14. It is to be understood that the holes38are provided in a corresponding number, arrangement and spacing with the bosses28to allow the bosses28to be readily disposed into holes38. It is further anticipated that the holes38can be shaped similarly as the outer surface of the bosses28to facilitate forming a close, snug fit therebetween to enhance the resistance of potential relative movement therebetween upon being fixed together. In an example embodiment, as best shown inFIG. 2, each hole38is circular and includes an annular, convex rounded edge40transitioning to the front side37of the flange34and an opposite annular, chamfered, also referred to as tapered or conical edge42, diverging toward and transitioning to the back side39of the flange34.

In an example embodiment, assembly of the ring gear carrier12to the bearing seat14includes aligning and inserting the bosses28, while in a generally cylindrical form, such as shown inFIGS. 3 and 13, into the round or substantially round holes38such that the free ends30of the bosses28extend beyond a leading corner43(FIG. 2) of the tapered edge42and preferably slightly beyond a trailing or free corner45(FIG. 2) of the tapered edge42. Then, as shown inFIG. 9and inFIGS. 14A-14Bof a continuous transfer die process line, upon bringing the front side37of the bearing seat14into compressed engagement with the back side23of the ring gear carrier rim20and disposing the bosses28fully into their respective holes38of the bearing seat14, the convex, rounded edge40of each hole28is brought into mating, conforming or substantially conforming engagement with a corresponding concave fillet29of a respective boss28, and a compressive force is exerted on or adjacent the free ends30of the bosses28, such as via the aforementioned punch46. As a result of the compressive force applied to the bosses28, the free end portions54are plastically deformed and radially displaced radially outwardly, in outwardly flared fashion, into contact with the tapered edges42of the bearing seat14. The flared end portions54take on a frustroconical shape, thereby fully wrapping around and capturing the peripheral edge of the holes38in the flange34of the bearing seat14between the flared end portions54and the rim20of the ring gear carrier12, and bringing the side37of the bearing seat14facing the front side FS into compressed abutment against the side23of the ring gear carrier rim20facing the back side BS.

To facilitate the construction process, as shown inFIG. 9, a horn44can be inserted behind the ring gear carrier rim20against the side21opposite the bosses28to axially support the rim20and the bosses28. The specially configured punch46applies force in axial direction A1to the free end30each of the bosses28to compressively deform and engage the bosses28with the bearing seat14. The horn44applies an equal and opposite force in the axial direction A2, and thus, limits axial motion of the ring gear carrier12so that the boss28is radially and circumferentially expanded within the round hole38, and the concave corner29is pressed into contact with the convex corner40during the application of a suitable force by the punch46, thus, resulting in the increase of a desired uniform compressive stress along segments48. As noted above, the punch46includes the nose portion50sized for close receipt through the through opening26and into a hollow portion of the horn44, and an annular flared portion52that extends radially outwardly from the nose portion50. The annular flared portion52has an annular concave surface that impacts the boss free end30when in its straight cylindrical configuration and causes the free end30to deform along the path of the fared portion52, thereby flaring the circular end portion54of the boss28radially outwardly in mating, conforming relation with the concavity of the punch flared portion52. As the free end30is flared radially outwardly, the annular flared end portion54of the annular boss28immediately adjacent the free end30is caused to wrap or fold into compressed abutment with the tapered edge42of the hole38without being cut or sheared, and as a result, without forming potential sources of crack propagation in the form of grooves, indentions, or otherwise, which tend to act as stress risers. As a result of the flaring, the flange34of the bearing seat14is effectively clamped and fixed within an annular channel55bounded between the flared end portion54and the rim20of the ring gear carrier12. Accordingly, the ring gear carrier12and the bearing seat14become reliably and securely fixedly joined to another against axial separation.

In general, any tensile force associated with torque loads on the assembly10, in particular on segments48, work to separate the bearing seat14from the ring gear carrier12. Advantageously, with the creation of additional compressive stress in segments48and with the entirety of the outer periphery of the holes38being captured within the annular channels55, the tensile forces are countered sufficiently, thereby increasing the torque capacity of assembly10.

FIG. 8is a detail of showing bearings incorporated for rolling engagement against the bearing seat14of the assembly10, wherein an example embodiment shows the assembly10as used in a transmission. In an example embodiment, bearings B1are used to radially guide the assembly10and thrust bearings B2and B3are used to axially guide the assembly10. As further described below, the fabrication of assembly10advantageously facilitates the hardening of surfaces of the bearing seat14upon which bearings B1, B2, B3ride.

The following provides further detail and information regarding the ring gear assembly10and the fabrication of assembly10. In an example embodiment, the tapered edges42are formed by any desired forming process, such as within the transfer die process, wherein the material of the bearing seat14is flared conically to act as a stop surface and conform to the flared portion54upon being compressed. As well, the forming process eliminates the need for machining of the bearing seat14in the areas of the bosses28to reduce the thickness. Machining could result in an interrupted cut that would require deburring at a substantial cost. By ‘forming’ we mean a process that produces the indented regions by compressing the material in the area of the tapered edges42.

In an example embodiment, corners or rounded edges40and corners or fillets29also are formed by a forming process, such as in the continuous transfer die process, that is, by applying compressive force to form their respective radii of curvature, wherein the formed radii help to improve fill, that is, the expansion of the bosses28to fill the holes38and compressively engaged the bearing seat14, and to better seat the bearing seat14and the ring gear carrier12. In an example embodiment, once the bosses28are inserted into the holes38, spring loaded, by way of example and without limitation, punch46provides the axial force discussed above, which press the bearing seat14and the ring gear carrier12together. During the application of the axial force an additional amount of residual compressive stress is put into the annular rounded edge40and segments48. This residual compressive stress results in a durability improvement, that is, the compressive stress counteracts the tensile forces associated with operation of assembly10.

In an example embodiment, as discussed above, while punch46is applying axially compressive force, the bosses28are fully supported by the horn44to prevent the bosses28from being pushed outwardly from the holes38.

Advantageously, the configuration of the assembly10minimizes the axial extent of the ring gear carrier12, in particular, the axial extent of space56needed to accommodate the horn44. The assembly10also replaces welding of the bearing seat14to the ring gear carrier12. Welding would undesirably increase cost and complexity for fabricating the assembly10and could result in undesirably heating, embrittlement, and possible warping of parts forming the assembly, as discussed above. Further, as mentioned above, welding typically requires similar materials to be used to form reliable weld joints, whereas the improved connection mechanism discussed and shown herein does away with such need for similar materials.

Upon fixing the ring gear carrier12to the bearing seat14, further processes can be performed in the continuous transfer process, such as shown inFIGS. 14C-14P, by way of example and without limitation. For example, finish forming processes can be performed on the cylindrical outer wall16of the ring gear carrier12, such as shown inFIGS. 14C-14F; final forming a spline and burls, such as shown inFIGS. 14G-14H; trimming and piercing, such as shown inFIGS. 14I-14P. It is contemplated herein that fewer or additional processes could be used in a transfer die process in accordance with the invention. It is also contemplated that other processes could be used to form the ring gear carrier assembly10within the spirit of the invention.