Torque converter including spherical clutch

A clutch assembly comprising: an axis of rotation; first and second spherical centers positioned along the axis of rotation; a first member having a first spherical surface including: a radius defining a first curvature; the first spherical center; and a first frictional surface; a second member having a second spherical surface including: said radius defining a second curvature about same or equal to the first curvature; the second spherical center; and a second frictional surface. A torque converter comprising a spherical clutch assembly is also disclosed.

FIELD

The invention relates generally to a torque converter including a spherical clutch arrangement.

BACKGROUND

United States Patent Publication No. 2015/0021137, hereby incorporated by reference herein, describes a two pass multi-function torque converter with a resilient element for opening an impeller clutch.

United States Patent Publication No. 2012/0152680, hereby incorporated by reference herein, teaches an embodiment wherein a first friction surface includes an axial bulge in the portion of the friction surface between a first inner diameter and a first outer diameter, wherein the axial bulge is defined by an arc having a radius at least one order of magnitude larger than a radial distance between the inner diameter and the outer diameter.

BRIEF SUMMARY

Example aspects broadly comprise a clutch assembly comprising: an axis of rotation; first and second spherical centers positioned along the axis of rotation; a first member having a first spherical surface including: a radius defining a first curvature; the first spherical center; and a first frictional surface; a second member having a second spherical surface including: said radius defining a second curvature about same or equal to the first curvature; the second spherical center; and a second frictional surface. In an example aspect, the second spherical center is about same or equal to the first spherical center when the clutch is engaged. In an example aspect, the second spherical center is offset from the first spherical center when the clutch is not engaged. In an example aspect, the first spherical surface further comprises a great circle including the radius and the first spherical center, wherein the first and second frictional surfaces are arranged for frictional engagement along the great circle. In an example aspect, the first or second member comprises friction material and wherein the first or second frictional surface is disposed on the friction material. In an example aspect, the friction material includes a bonding surface and an opposite surface. In an example aspect, the opposite surface is convex.

Other example aspects broadly comprise a torque converter comprising: an axis of rotation; first and second spherical centers positioned along the axis of rotation; an impeller including an impeller shell having a first inner spherical surface including: a radius defining a first curvature; the first spherical center; and a first frictional surface; a turbine including a turbine shell having a second inner spherical surface including: said radius defining a second curvature about same or equal to the first curvature; the second spherical center; and a second frictional surface; wherein the first and second frictional surfaces are arranged for frictional engagement. In an example aspect, the impeller shell or turbine shell comprises friction material and wherein the first or second frictional surface is disposed on the friction material. In an example aspect, the friction material includes a bonding surface and an opposite surface. In an example aspect, the opposite surface is convex. In an example aspect, the impeller shell comprises a first spherical portion including the first inner spherical surface, a rear cover outer surface, and a first thickness. In an example aspect, the impeller shell further comprises first and second tapered portions and a second thickness greater than the first thickness. In an example aspect, the impeller shell further comprises a cylindrical portion including an end portion and extending to and arranged for connection with a cover and a bent portion extending and integrally attached to an impeller shell torus portion. In an example aspect, the turbine shell comprises a second spherical portion including the second inner spherical surface and an outer turbine shell surface. In an example aspect, the turbine shell further comprises a radial wall portion extending and integrally attached to a turbine shell torus portion. In an example aspect, the first spherical surface further comprises a great circle including the radius and the first spherical center, wherein the first and second frictional surfaces are arranged for frictional engagement along the great circle.

Other example aspects broadly comprise a torque converter comprising: an axis of rotation; first and second spherical centers positioned along the axis of rotation; a cover; an impeller including an impeller shell having: a first spherical portion including a first inner spherical surface including: a radius defining a first curvature; the first spherical center; and a first frictional surface; a bent portion; and a cylindrical portion including an end portion extending to and arranged for connection with the cover; a turbine including a turbine shell having: a second spherical portion including a second inner spherical surface including: said radius defining a second curvature about same or equal to the first curvature; the second spherical center; and a second frictional surface; wherein the first and second frictional surfaces are arranged for frictional engagement; wherein the second spherical center is about same or equal to the first spherical center when clutch is engaged; and, wherein the second spherical center is offset from the first spherical center when clutch is not engaged. In an example aspect, the first spherical surface further comprises a great circle including the radius and the first spherical center, wherein the first and second frictional surfaces are arranged for frictional engagement along the great circle. In an example aspect, the first or second spherical portion comprises friction material and wherein the first or second frictional surface is disposed on the friction material.

DETAILED DESCRIPTION

At the outset, it should be appreciated that like drawing numbers appearing in different drawing views identify identical, or functionally similar, structural elements. Furthermore, it is understood that this invention is not limited only to the particular embodiments, methodology, materials and modifications described herein, and as such may, of course, vary. It is also understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to limit the scope of the present invention, which is limited only by the appended claims.

A spherical clutch arrangement as disclosed herein provides advantages such as misalignment compensation while at the same time reducing torus size. A spherical clutch assembly is suitable for use in, for example, torque converters. Misalignment of components during operation can lead to undesirable torque fluctuations; the spherical clutch described herein is self-centering. Reducing torus size of torque converters, and thus also reducing total weight of the assembly, is desirable in modern automobiles, for example, to increase fuel economy.

The following description is made with reference toFIGS. 1-5.FIG. 1illustrates a partial cross sectional side view of a torque converter including a spherical clutch assembly according to an example aspect. Torque converter10is interchangeably referred to as torque converter assembly herein. Torque converter10includes front cover12for connecting to a crankshaft of an internal combustion engine via stud11and rear cover16, also referred to as impeller shell interchangeably herein, for an impeller18. Impellers are also referred to in the art interchangeably as ‘pump’. Front cover12and rear cover16are fastened together via weld14. Cover12includes cover pilot portion90. Torque converter10also includes turbine20, turbine shell22, stator32between turbine20and impeller18. Turbines and impellers, as is known in the art, include a plurality of blades. Torque converter10includes torus portion75, generally referring to the fluid coupling portion including turbine20and impeller18between the dashed lines as shown inFIG. 1.

Torque converter10includes one-way clutch30, which supports stator32, and includes inner race88, roller92, and outer race94. Side plate36holds one-way clutch30in place within stator32. Torque converter10also includes damper assembly40, which is connected to and drivable by turbine20, and is positioned between turbine20and front cover12. Damper assembly40includes spring42, flange46, and drive tab44fixed to turbine shell22to damper assembly40.

Torque converter10includes clutch assembly50as will be described in greater detail inFIGS. 3-5. Torque converter10, as shown inFIG. 1, further includes hub80fixed to flange46, bushing86, weld96, and hub98.FIG. 1also shows transmission components spline78, input shaft82, and stator shaft84. Hub80is splined to input shaft82and inner race88is splined to stator shaft84at splines78. Bushing86positions and at least partially seals turbine shell22on shaft82.

Torque converter10includes axis of rotation A, also simply referred to as axis A, as well spherical center60and radius65. Components of torque converter10include spherical surfaces, wherein geometrically speaking, the outline or surface shape of the particular components simulate or equate to at least a portion of a sphere, wherein the sphere is defined by the center and the radius. Spherical center60is positioned on axis of rotation A, where radius65intersects with axis A. Radius65is the distance from spherical center60to a portion of clutch assembly50. More specifically, radius65is the distance from spherical center60to the first spherical surface of clutch assembly50; the first spherical surface is shown in greater detail inFIGS. 3-5. First axial direction AD1is opposite to second axial direction AD2.

FIG. 2illustrates a cross sectional side view of the torque converter ofFIG. 1, rotated about axis of rotation A, according to an example aspect.FIG. 2shows torque converter elements as inFIG. 1and also includes great circle70. Great circle70illustrates a circle of the sphere having spherical center60and radius65. A plane passing through great circle70divides the sphere into two equal parts. Clutch assembly50is arranged for engagement along great circle70.

FIGS. 3-6illustrate a partial side view, as indicated by box B ofFIG. 1, of a torque converter including a spherical clutch assembly according to an example aspect. It is noted that spherical center60and radius65are not viewable in close upFIGS. 3-6, however, the spherical center and radius elements are present as depicted inFIG. 1, whereinFIGS. 3-5are merely close up views ofFIG. 1for clarity.FIG. 6shows the clutch with a smaller diameter for added clarity. Spherical clutch assembly is also referred to interchangeably herein as clutch assembly.FIG. 3shows clutch assembly150including a first member or, in an example aspect, rear cover116. First member or rear cover116comprises first spherical portion152, bent portion154, and cylindrical portion156having end portion158. End portion158connects to cover112at weld114as is known in the art. Spherical portion152includes first spherical surface160, also referred to interchangeably herein as first inner spherical surface; a portion of first spherical surface160includes first frictional surface162. Spherical portion152further comprises rear cover outer surface164, opposite to first inner spherical surface160. Clutch assembly150also includes a second member or, in an example aspect, an extension of turbine shell122including second spherical portion166and radial wall portion168. Spherical portion166includes second spherical surface170, also referred to interchangeably herein as second inner spherical surface; wherein second spherical surface170includes second frictional surface172.FIGS. 3-6also show portions of flange148and spring142.

Referring toFIGS. 1-5generally andFIG. 4-5more particularly, clutch assembly250,350comprises axis of rotation A and first and second spherical centers positioned along the axis of rotation.FIG. 4illustrates a partial side view of spherical clutch assembly250according to an example aspect, wherein the clutch is engaged; whileFIG. 5illustrates a partial side view of a spherical clutch assembly350according to an example aspect, wherein the clutch is disengaged. Disengagement distance of clutch assembly350is exaggerated for clarity. The second spherical center lies on axis A at or near first spherical center60depending upon the state of clutch engagement. In other words, the second spherical center is positioned in the same location as first spherical center60, in the condition that clutch assembly250is engaged. Furthermore, second spherical center is offset from first spherical center, in the condition that clutch assembly350is not engaged or disengaged, in second axial direction AD2relative to first spherical center60along axis A. That is to say, when the clutch is disengaged, the second spherical center moves in a direction parallel to axis A axially away from torus portion75. The second spherical center is not illustrated in the figures as the scale of axial movement is relatively small, and can be thought of in terms of millimeters of movement, so that discernment between spherical centers inFIGS. 1 and 2would be indistinguishable.

Referring again toFIGS. 1-5, in an example aspect, clutch assembly150comprises axis of rotation A and first and second spherical centers, first member116having first spherical surface160including radius65defining a first curvature and first spherical center60; where first spherical surface160includes first frictional surface162. Clutch assembly150also comprises second member122having second spherical surface170including radius65defining a second curvature about same or equal to the first curvature and a second spherical center, which may be coincident with spherical center60in clutch engaged mode or offset relative to spherical center60along axis A in axial direction AD2, which is away from torus portion75, in clutch disengaged mode. In other words, the second spherical center is about same or equal to the first spherical center when the clutch is engaged, and the second spherical center is offset from the first spherical center when the clutch is not engaged. Spherical surface170includes second frictional surface172.

First spherical surface160further comprises great circle70including radius65and first spherical center60, wherein the first and second frictional surfaces162,172are arranged for frictional engagement along great circle70. In providing clutch engagement along great circle70, clutch assembly150is self-centering and therefore provides consistent torque performance and even contact at the frictional surfaces. Misalignment compensation between transmission input shaft82and axis of rotation A is achieved wherein clutch components are aligned within great circle70.

The second member, in an example aspect turbine shell122, comprises friction material174including bonding surface176and opposite surface178. While the second member is shown and described herein as including friction material174, as those skilled in the art would recognize, friction material174is not limited to the second member and could be incorporated into either first or second members. In other words, a first member including friction material174is also contemplated as would, for example, be fixed to an inner surface of an impeller shell. Second frictional surface172is disposed on friction material174. Second frictional surface172is disposed, in an example aspect, on opposite surface178.

As is known in the art of applying friction material to a member using a die, it is possible to tailor the shape of opposite surface178by tailoring the thickness of friction material174and the shape of the member to which the friction material will be applied. In an example embodiment, member122includes turbine shell outer surface184and turbine shell inner surface186. In an example aspect, the shape of inner surface186may be spherical or flat prior to applying friction material174; however, in either case, second inner spherical surface170is spherical. This is accomplished as follows. In the example of surface186being flat, friction material174includes a thickness profile that is convex to ensure spherical surface170maintains as spherical. In other words, opposite surface178is convex. Yet in another example embodiment where surface186is spherical, friction material174includes a uniform thickness and thus surface170is also spherical as applied to surface186.

In another example aspect, a torque converter including a spherical clutch assembly is provided herein. Torque converter10comprises: axis of rotation A; first and second spherical centers positioned along axis of rotation A; impeller18including impeller shell16,116having first inner spherical surface160including radius65defining a first curvature, first spherical center60, and first frictional surface162; turbine20including turbine shell22,122having second inner spherical surface170including radius65defining a second curvature about same or equal to the first curvature, second spherical center (offset in axial direction AD2for clutch disengaged mode and coincident with first spherical center60in clutch engaged mode); and second frictional surface172; wherein first and second frictional surfaces162,172are arranged for frictional engagement. Second member22,122comprises friction material174, wherein second frictional surface172is disposed on friction material174. Friction material174includes bonding surface176and opposite surface178. Opposite surface178is, in an example aspect, convex. In an example aspect, first spherical surface160further comprises great circle70including radius65and first spherical center60, wherein first and second frictional surfaces162,172are arranged for frictional engagement along great circle70.

In an example aspect, first member116comprises first spherical portion152including first inner spherical surface160, rear cover outer surface164, and first thickness t1. In an example aspect, first member116further comprises first and second tapered portions180,182and second thickness t2, where t2is at least equal to or greater than t1. First spherical portion152need not be tapered, and the configuration or arrangement of the transition regions between spherical portion152and neighboring portions cylindrical portion156and bent portion154may vary. In an example aspect, first member comprises cylindrical portion156including end portion158and extending to and arranged for connection with cover112. In an example aspect, first member comprises bent portion154extending and integrally attached to torus portion75of impeller shell116, also referred to as impeller shell torus portion.

In an example aspect, second member122comprises second spherical portion166including second inner spherical surface170and turbine shell outer surface184. In an example aspect, second member122further comprises radial wall portion168extending and integrally attached to torus portion75of turbine shell122, also referred to as turbine shell torus portion.

In yet another example aspect, torque converter10comprises: axis of rotation A; first and second spherical centers positioned along axis of rotation A; cover12,112; impeller18including impeller shell16,116having: spherical portion152including first inner spherical surface160including radius65defining a first curvature; first spherical center60; and first frictional surface162; bent portion154; and cylindrical portion156including end portion158extending to and arranged for connection with cover12,112; turbine including turbine shell22,122having second inner spherical surface170including: radius65defining a second curvature about same or equal to the first curvature; second spherical center (offset in axial direction AD2for clutch disengaged mode and coincident with first spherical center60in clutch engaged mode); and second frictional surface172; wherein first and second frictional surfaces162,172are arranged for frictional engagement. In other words, second spherical center is about same or equal to first spherical center60when clutch is engaged (FIG. 4) and, wherein second spherical center is offset from first spherical center60when clutch is not engaged (FIG. 5). In an example aspect, first spherical surface160further comprises great circle70having radius65and first spherical center60, wherein first and second frictional surfaces162,172are arranged for frictional engagement along or aligned with great circle70. In an example aspect, second member22,122comprises friction material174, wherein second frictional surface172is disposed on friction material174.

Of course, changes and modifications to the above examples of the invention should be readily apparent to those having ordinary skill in the art, without departing from the spirit or scope of the invention as claimed. Although the invention is described by reference to specific preferred and/or example embodiments, it is clear that variations can be made without departing from the scope or spirit of the invention as claimed.